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Full text of "Report of the Nicaragua canal commission, 1897-1899"

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REPORT 



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NICARAGUA CANAL COMMISSION 



REPORT 



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NICARAGUA CANAL COMMISSION 



1 897- 1 899 



REAR ADMIRAL JOHN G. WALKER, U. S. N. 

PRESIDENT 

COLONEL PETER C. MAINS, U. S. A. PROFESSOR LEWIS M. HAUPT 

Corps of Engineers Civil Engineer 



^I^ANSPORTATION LIBRARV 



WITH AN ATLAS 



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The Frihdenwald Company 
BALTIMORE 

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CONTENTS 

PAGB 

■ 

Act Authobizing the Appointment of the Commission XI 

Letter of Appointment to Members of the Commission XI 

Supplemental Letter of Instructions XII 

Organization of the Commission 1 

Letter of Instructions to the Chief Engineer 2 

Itinerary of the Commission 3 

Physics of the Canal Region 5 

Lake Nicaragua 5 

Western Division 6 

Eastern Division 7 

San Juan River 7 

Slopes and Distances 7 

Velocity and Discharge 8 

Lateral Drainage 8 

Capacity of the Channel 9 

Controlling Section 9 

Computed Velocities and Discharges 10 

Stability of Slopes 10 

Sanitary and Climatic 12 

Earthquakes and Volcanoes 13 

Materiaus for Structural Purposes 13 

Alluvium 13 

Sand 13 

Clay 14 

Wood 14 

Iron and Steel 14 

Stone 15 

Classification and Weathering 16 

Dimensions of the Canal 16 



yj CONTENTS 

PAGE 

Regulation of the Lake Level 17 

Rainfall 18 

Evaporation 18 

Run-off , 19 

Lockage 1*9 

Limits of Regulation 19 

Location of Spillways 23 

Projects and Routes 24 

Western Division 24 

Lake Division 26 

Eastern Division 26 

Gebytown Harbob 29 

Brito Harbor 31 

Dams and Embankments 32 

Dams on the Eastern Division 33 

Sites for Low Dams . 34 

San Carlos and San Francisco Embankment Lines 34 

Dams on the Western Division 35 

Canal Looks 35 

Quantities 36 

Unit Prices 37 

Fbasibility 42 

Estimate 43 

Conclusions 45 

Appendix I. Report of the Chief Engineer 47 

n. Geologic Report 87 

m. Hydrographic Report * 193 

IV. Report of J. W. G. Walker, Assistant Engineer 343 

V. Report of F. L. Stuart, Assistant Engineer 359 

VI. Report of H. H. Trundle, Assistant Engineer 387 

Vn. Report of Boyd Ehle, Assistant Engineer 401 

Vm. Report of S. S. Evans, Assistant Engineer 419 

LX. Report on Precise Levels * 431 

X. Report of A. Onderdonk, Assistant Engineer 475 

XI. Report of L. Hankins, Assistant Engineer 485 



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ILLUSTRATIONS 

Appendix II. 

PAGE 

Plate. I. Map of the San Juan Delta 98 

11. Map showing changes of coast lines and divides 102 

m. Sections showing topographic forms in the San Juan Valley 104 

IV. Volcano Momotombo from Lake Managua 110 

V. The Brito formation near La Flor 116 

VI. Map to illustrate recent shifting of divides 142 

VII. Map of Brito harbor, showing depth to rock 1<)4 

Vni. Drill Sections, Eastern Divide 192 

IX. Drill Sections, San Francisco Embankment 11)2 

X. Drill Sections, Tambor Grande and Tamborcito 192 

XL Drill Sections, Lower Ochoa and San Carlos Embankment 192 

XII. Drill Sections, Upper Ochoa 192 

XTTL Drill Sections, Boca San Carlos •. 192 

XIV. Drill Sections, Machuca, Santa Cruz and Conchuda 192 

XV. Longitudinal Sections of Eio Grande and San Juan Valleys 192 

XVI. General Geologic Sections 192 

XVn. Geologic Sections at dam sites 192 

XVni. Geologic Sections at Embankment lines 192 



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Appendix III. 

Plate I. Gaging Station at Brito 198 

n. Lake gage at Las Lajas 202 

m. Gaging Rio Viejo 204 

IV. Gaging Station at Tipitapa 208 

V. Zapatero and Lake Nicaragua 212 

VI. Scene on San Juan River 218 

Vn. Starting to Gage a River 227 

VHl. Gaging Rio San Carlos, showing use of staywire 233 

IX. Rating curves, San Juan at Ochoa 236 

X. Comparative Diagram, San Juan and San Carlos 240 

XL Rainfall Diagram, Brito — Deseado 262 



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yill ILLUSTRATIONS 

PAGE 

Plate XII. Rainfall Diagram, Tipitapa — ^Rio Viejo 2C6 

" XIII. Rainfall Diagram, Rio San Juan 274 

*' XIV. Rainfall Diagram, Las Lajas — ^Ft. San Carlos — San Francisco 276 

" XV. Monthly Rainfall at Rivas, 1880-1898 278 

" XVL Daily Rainfall at Rivas, 1890, 1807, 1898 280 

" XVII. Dam site at Tipitapa in dry season 292 

" XVIII. Elevation of Lake Nicaragua compared with syndironous rainfall in its basiin. 294 

" XIX. Inflow to Lake Nicaragua, compannl with accumulated rainfall 296 

" XX. Measuring the sediment 301 

Figure 1. Diagram of Daily Discharge of Rio (Jninde, 1898 200 

" 2. Diagram of Daily Discharge of Rio Viejo, 1898 203 

" 3. Diagram of Daily Discharge of Rio Tipitapa, 1898 211 

*^ 4. Diagram of Daily Discharge of Tributaries of San Juan l)etwo(»n Sahalos and Bo 

ca San Carlos, 1898 225 

" 5. Diagram of Daily Discharge of Rio San Jimn above Boca San ('arlos 220 

** 6. Diagram of Daily Discharge of Rio San Francisco at Embankment line 248 

*' 7. Comparative monthly rainfall at Greytown, Ochoa, Ft. San Carlos and Tola. . . .278 

" 8. Comparative rainfall at Rivas and Masaya 297 

'* 9. Sediment Trap ready for use 300 



CONTENTS OF ATLAS 

Map No. 1 — In 4 sheets: 

Sheet No. 1 — General Map of the Nicaragua Canal Region. 

Sheet No. 2 — Geology of Canal Region. 

Sheets Nos. 3 and 4 — ^Hydrology of Canal Region. 

Map No. 2 — In 3 sheets, showing the projected lines of the Nicaragua Canal on the scale 5000 

feet to 1 inch. 

Map No. 3 — In 20 sheets and Index sheet, showing the projected lines of the Nicaragua Canal 

on the scale of 1500 feet to 1 inch. 

Map No. 4 — Greytown harbor. 

Map No. 5 — Brito harbor, showing Hydrography. 

Map No. 6 — Hydrography Caribbean Coast from Indio river to the mouth of the Colorado 

river. 

Map No. 7 — Lake Nicaragua. 

Profiles. 

Profile No. 1 — In 2 sheets, showing Lull route, Variant I, East Side. 

Profile No. 2 — In 2 sheets, showing Menocal route. East Side. 

Profile No. 3 — Showing Childs route. Variant I, West Side. 

Profile No. 4 — Showing Childs route, Variant 11, West Side. 

Profile No. 5 — Showing proposed railroad, from Greytown to Rio Savalos. 

Profile No. 6 — Showing proposed railroad, from Lake Nicaragua to the Pacific ocean. 

Table of Quantities for various Nicaragua Canal Routes. 
Plate XlXa, Diagram of Lake Level R^ulation. 



NICARAGUA CANAL COMMISSION 



To continue the surveys and examinations 
authorized by the Act approved March second, 
eighteen hundred and ninety-five, entitled " An 
Act making appropriations for the sundry civil 
expenses of the Government for the fiscal year 
ending June thirtieth, eighteen hundred and 
ninety-six, and for other purposes," into the 
proper route, the feasibility and cost of construc- 
tion of the Nicaragua Canal, with the view of 
making complete plans for the entire work of 
construction of such canal as therein provided, 
one hundred and fifty thousand dollars; and to 
carry out this purpose the President of the 
United States is authorized to appoint, by and 
with the advice and consent of the Senate, a 
commission to consist of one engineer from the 
Corps of Engineers of the United States Army, 
one officer of the Navy, who may be taken from 
the active or retired lists, and one engineer from 
civil life, said commis^^ion to have all the i>owers 
and duties conferred upon the commission pro- 
vided for in said Act. 

(Public No. 2. Approved June 4, 1897. 
Page 54.) 

Department of State, 
Washington, August 2, 1897. 
Gentlemen: — Pursuant to* that portion of the 
Sundry Civil Appropriation Act (Public No. 2) 
approved June 4, 1897, constituting a Nica- 
ragua Canal Commission, to be appointed by 
the President, " to continue the surveys and 
examinations authorized by the Act approved 
March 2, 1895, . . . into the proper route, the 



feasibility and cost of construction of the Nica- 
ragua Canal, with the view of making com- 
plete plans for the entire work of construction 
of such canal as therein provided," you have 
been appointed by the President members of 
said Commission, and it is incumbent upon me, 
as Acting Secretary of State, to communicate 
to you the following instructions, which have 
been approved by the President, for the guid- 
ance of the Commission: 

The Commission is authorized to make such 
journeys and to do such work as may be neces- 
sary to carry into effect the instructions contain- 
ed in the Act. To facilitate its work, the Com- 
mission is authorized to purchase in open market 
such materials, including instruments, field out- 
fit, supplies, etc., as in its judgment are neces- 
sary, and to employ such skilled and other assist- 
ance as it may deem essential, and to pay such 
rates of compensation as may be deemed proper. 
The approval of the President of the Commission 
shall be final authority for all expenditures. 

An itemized account of all disbursements, 
with proper vouchers, will be submitted through 
the Department of State for audit . . . .' 

Respectfully yours, 

Alvey a. Adee, 
Acting Secretary^ 
Admiral John G. Walker, U. S. N., 

President, 
Captain Obbrlin M. Carter, 

Corps of Engineers, U. S. A. 
Prof. Lewis M. Haupt, 

Civil Engineer. 

Members of the yicaraguu Canal Commission, 



ZII 



NICARAGUA CANAL COMMISSION 



Department of State, 

Washington, November 3, 1897. 

Rear-Admiral John G. Walker, U. S. N., 
President; Colonel Peter C. Hains, 
Corps of Engineers, TT. S. A.; Professor 
Lewis M. Haupt, Members of Nicaragua 
Canal Commission, Army Building, New 
York City. 

Gentlemen: — Referring to the Department's 
instructions of August 2, 1897, concerning the 
prosecution of the work of the Nicaragua Canal 
(^mmission agreeably to the Act of Congress 
approved June 4, 1897, I have now to supple- 
ment those instructions in the following par- 
ticulars. 

It is impossible to give you specific instruc- 
tions for the execution of your work beyond 
referring you to the provisions of the Act re- 
ferred to and enjoining upon you the desira- 
bility and the necessity of prosecuting your 
labors to completion as rapidly as circumstances 



will permit. It will be observed, by reference 
to the Act, that it contemplates a continuance 
of the previous surveys, " with a view of making 
complete plans for the entire work of construc- 
tion of such canal as therein pro\'ided." 

The Department's understanding of this lan- 
guage is that your report should not only em- 
brace all features of the work authorized by Con- 
gress under the present law, but that such field 
notes or other data as may be acquired and that 
may be necessary for the complete understand- 
ing of the President and Congress, shall be spe- 
cifically included in your report. In other 
words, your report should be as full and con- 
clusive upon the subject as it is practicable to 
make it, to the end that " the proper route, the 
feasibility and cost of construction of the Nica- 
ragua Canal " may, if possible, be absolutely 

fixed and determined 

Respectfully yours, 

John Sherman. 



REPORT OF THE NICARAGUA CANAL 

COMMISSION. 



Washikgton, D. C, May 9, 1899. 
The President of the United States. 

Sir: — The Nicaragua Canal Commission, 
having completed its labors, has the honor to 
report as follows: 

The Commission was organized July 29, 1897, 
and its first meeting was held on that day. It 
consisted of Rear-Admiral John G. Walker, 
U. S. Navy, President; Captain O. M. Carter, 
U. S. Corps of Engineers; and Professor Lewis 
M. Haupt, Civil Engineer, members. Captain 
Carter was relieved from duty with the Com- 
mission and was succeeded on October 18 by 
Colonel Peter C. Hains, U. S. Corps of Engi- 
neers. 

This Commission has imderstood the law, ap- 
proved June 4, 1897, by which it was consti- 
tuted, to require that all routes heretofore pro- 
posed, having any merit, should be considered, 
new routes that appear to have merit should be 
developed, and the entire region of canal possi- 
bilities should be examined with sufficient thor- 
oughness to enable a just and comprehensive 
comparison of the various routes to be made and 
the most desirable one selected. In short, to 
enable it to make a complete and exhaustive 
report. 

With this in view the Commission established 

its headquarters in the Army Building in New 

York and devoted considerable time to a careful 
1 



examination and study of all data bearing upon 
the Nicaragua Canal question obtainable in the 
United States, including Government surveys 
and surveys by private parties, going back nearly 
fifty years. During this time an engineering 
staff was engaged, and the organization of ex- 
ploring, surveying, geological and hydrographic 
parties was proceeded with, considerable delay 
being caused by the necessity for a change of 
Engineer Members of the Commission. A 
Commissary Department was also organized for 
the handling of supplies and food from the 
United States, as it was impossible to supply the 
large force employed with promptness -and cer- 
tainty from the resources of Nicaragua in the 
wild part of the country where the work was 
prosecuted. 

The preliminary studies having been made 
and the organization completed, the expedition 
sailed from New York on the U. S. S. " New- 
port," on December 5, 1897, nearly one lum- 
dred strong, and amved off Grey town Decem- 
ber 17. The men and stores were landed as 
promptly as possible, and as fast as laborers 
could be engaged, the various parties were put 
into the field and entered upon the work as- 
signed them. 

Through the courtesy of the Secretary of the 
Navy, the U. S. S. '* Newport '' was assigned 
to the service of the Commission for the survey 



2 



NICARAGUA CANAL COMMISSION 



of Grevtown harbor and vieinitv, the U. S. S. 
" Alert " for the survey of Brito and its vicinity, 
and a strong hydrographic party under Lieut. 
Hanus, of the Xavy, was assigned to the survey 
of Lake Nicaragua and the San Juan river. 

The following instructions for the guidance 
of the Chief Engineer of the Commission were 
issued December 21, 1897: 

San Juan del Xorte, Nicaragua, 

December 21, 1897. 
Mr. E. S. \\"iieelek, C. E., Chief Engineer to 
the Nicaragua Canal Commission. 

Sir: — The Nicaragua Canal Commission, ap- 
pointed by the President under the Act ap- 
proved Jime 4, 1807, has selected you to take 
charge of the field work and direct the opera- 
tions of the various parties to make the surveys 
and examinations provided for in the Act above 
referred to in reference to the Nicaragua Canal. 

The scope and character of the work are indi- 
cated by the words of the law, *^ to continue the 
surveys and examinations . . . into the proper 
route, the feasibility and cost of construction of 
the Nicaragua Canal, with the view of making 
complete plans for the entire work of construc- 
tion of said canal as therein provided." 

Your familiarity with the methods employed 
in conducting surveys and examinations under 
the Government with a view to projecting works 
of improvement renders it unnecessary at this 
time for the Commission to give you other than 
general instructions. The details and methods 
the Commission leaves to vou to work out as 
you find best and as circumstances render ad- 
visable, the field parties being directly under 
your orders. The Commission desires as a final 
result, to be in possession of all the physical 
data which bear in any important way upon the 
construction of the Nicaragua Canal, and it is 
expected that the accuracy and trustworthiness 



of these results shall be unquestioned. Due 
care will Ix? exercised not to unnecessarily dupli- 
cate anv of the accurate w^ork alreadv done. 

Naval hydrographic parties working under 
the direction of the Commission will survey 
Brito harbor and vicinity, Greytown harbor and 
vicinity, Lake Nicaragua and the San Juan river. 
All these parties will connect their gages w4th 
the benches established by your topographical 
parties, so that their soimdings and your work 
shall confonn to the same datum plane. You 
are expected to confer freely with the chiefs of 
these parties, that you both may have a clear 
understanding of your mutual work. 

The Commission desires, among other things, 
that vou determine at Grevtown and Brito the 
mean sea levels and connect them, if practicable, 
with a line of precise levels from ocean to ocean. 

You will also make such survevs between Brito 

t-' 

and Lake Nicaragua as may be necessary to 
locate the best line for the canal, and such other 
investigations as may serve to determine the 
practicability of controlling the lake level by a 
weir on the west side. 

Borings should be made to ascertain the kind 
and quantity of material to be removed in form- 
ing the harbor at each terminus of the canal and 
along its entire route, including the San Juan 
river. These borings should be made more 
numerous at the proposed site of locks, sluices 
and dams than are necessarv elsewhere. Par- 
ticular attention should be given to the Ochoa 
and other important dams and to the San Fran- 
cisco and San Carlos embankment lines. The 
feasibility of the Canal Company's project 
hinges on the control of the lake level, the Ochoa 
dam and the maintenance of the Divide cut. 
All possible data bearing on these questions 
should be gathered. 

The proper Naval hydrographic party will 



REPORT OF THE COMMISSION 



make the necessary survey of Lake IXicaragua 
to determine with sufficient accuracy its area, 
in order that the question of controlling its level 
may be properly studied, the extent of the avail- 
able anchorage between Ometepe island and 
the west shore be ascertained, as well as the 
safety of the course which would be followed by 
steamers between the western entrance to the 
canal and the head of the San Juan river. 

AVhere the bends of the river are sharp it 
may be necessary to cut through them. The 
survey should be made to cover such possible 
contingency. The disposal of the spoils from 
the excavations in the river must be taken into 
consideration. These should be deposited where 
thev will facilitate rather than interfere with 
navigation. 

A suitable number of rain and evaporation 
stations should be established at the most de- 
sirable points in the drainage basin affecting the 
canal. The records of these should be continued 
as long as practicable. 

The low-level line following the San Juan 
to near its junction with the Colorado should 
also be surveved, and an estimate of its cost de- 
termined for comparison with other projects. 
This lipe has always been regarded as practica- 
ble, and while it has considerably greater length 
than the comparatively direct line through the 
Divide, it will avoid some of the difficult engi- 
neering problems of the latter route. 

The survev of the San Juan should also in- 
elude the gaging of the river at numerous 
points, the determination of its slope in high and 
low stages, its discharge in both stages, the dis- 
charge and regimen of the principal streams that 
empty into it and generally all information nec- 
essary to determine? the best method of improv- 
ing its navigation, whether by canalization or 
otherwise. 



All the field parties will receive their instruc- 
tions directly from you. It is expected, how- 
ever, that you will keep the Commission fully 
infonned as to the character of the work being 
done and the methods adopted by you in doing 
it. For this purpose you will submit monthly 
reports to the Commission (which shall contain 
a concise history of the operations and progress 
of the work), and such special reports as may 
from time to time be necessary. These instnic- 
tions are not intended to be final and complete, 
but may be supplemented by others from time 
to time as the exigencies of the work demand. 
I am, very respectfully, 

J. G. Walker, 
President of the Commission. 

The Commission remained in Grevtown until 
January 8, 1898, when it proceeded in a special 
steamer, kindly placed at its disposal by the 
Kicaraguan Government, to the examination of 
the San Juan river from the sea to where it 
leaves Lake Nicaragua, including the Colorado 
branch. 

Five days were occupied in this examination. 
The Commission, arriving at Fort San Carlos, 
the head of the San Juan river, on the evening 
of January 13, proceeded at once by steamer 
to San Jorge, where it arrived on the following 
morning, and after putting ashore its equipment, 
supplies and extra baggage, continued to Gra- 
nada and Managua for the purpose of paying its 
respects to the President of the Republic. 

Arriving at Managua on the afternoon of the 
15th of January the Commission was specially 
received by the President at 8 o'clock, on the 
same evening, w^th all the ceremonies and 
honors pertaining to such occasions. During 
its stay in Managua every attention w^as shown 
by the President, members of the Cabinet and 



NICARAGUA CANAL COMMISSION 



other ofRcers of the Government. On the morn- 
ing of the 18th, the Commission called upon the 
President to take formal leave and then pro- 
ceeded by rail to Granada, was transferred to 
the lake steamer " Victoria," and reached San 
Jorge late the same afternoon, arriving at Kivas 
shortly aftenvards, where temporary headquar- 
ters were established. 

Promptly upon its arrival at Rivas the Com- 
mission took up the investigation of the canal 
route from the lake to the Pacific, and remained, 
either in Rivas or upon the proposed line of the 
canal, until February 13, having been some- 
what delaved bv an attempt at a revolution dur- 
ing that period. 

On the 13th the Commission left by steamer 
for San Carlos, at the head of the river San 
Juan, arriving at that point on the morning of 
the 14th. 

After inspecting the work of the parties under 
Lieutenant Hanus, U. S. N., and Mr. Stuart, 
Assistant Engineer, the Commission, on the fol- 
lowing morning, proceeded down the river, land- 
ing that afternoon at Ochoa, and, after exam- 
ining the work going on in that neighborhood, 
which included borings at the proposed site of 
the Ochoa dam, started on foot upon the trail 
over the Divide, for a personal examination of 
that part of the line, arriving at Greytown at 
C P. M. on the 21st. 

The Commission remained in Greytown imtil 
February 27, when it left on board the IT. S. S. 
" ^Newport " for Port Limon, Costa Rica, arriv- 
ing there on the following day, and proceeding 
by special train, provided by order of the (^osta 
Rican Goveniment, to the capital (San Jose), 
for the purpose of paying its respects to tlie 
President of Costa Rica. Thc^ Commission was 
pleasantly received by the President, by special 
appointment, at 8 P. M., March 1. The next 



day was spent in visiting the neighborhood of 
the capital, leaving San Jose by special train on 
the morning of the 3d for Port Limon, and go- 
ing immediately on board the " Xewport.^' 
During the trip to and from San Jose the cuts 
and embankments along the line of railroad 
were carefully observed with a view^ to obtaining 
information w^itli regard to the stability of slopes 
in tropical regions in connection with the pro- 
posed canal. 

The " Newport •• sailed at P. M., March 3, 
for Colon, arriving the following day (^larch 4). 
The five succeeding days were spent in exam- 
ining the Panama Canal line, the work being 
done, and the plans, drawings and data in the 
oflice of the company in Panama. 

In this connection the Commission wishes to 
express its warmest thanks to Monsieur Belin, 
the Director-General, and to the officers of his 
staff, for their kindness and untiring efforts to 
facilitate its work in every way possible, also to 
Mr. John F. Shaler, the Superintendent of the 
Panama Railroad, for his aid, assistance, personal 
efforts and care during its entire stay upon the 
Isthmus. 

On the 10th, having taken leave of the offi- 
cials at Colon, the " Xewport '' sailed for Port 
Limon and Greytown, arriving at Greytown on 
March 12. 

On March 20 the Commission, having com- 
pleted its personal examination of the proposed 
Nicaragua Canal Route, took its departure for 
the United States, leaving its working parties in 
the field to prosecute the work assigned them 
under the direction of Mr. E. S. Wheeler, its 
Chief Engineer. 

Much delay to the work and great annoyance 
to working parties were caused by attempts at 
revolution and bv the strained relations between 
the Governments of Nicaragua and Costa Rica, 



REPORT OF THE COMMISSION 



which rendered it difficult and often impossible 
to forward supplies, provisions and orders to 
working parties in the field and to receive re- 
ports from them. It is a difficult country in 
w^hich to carry on work of the kind assigned to 
this Commission at any time, but the difficulties 
were increased many fold, and great delay was 
caused bv the disturbed conditions referred to. 
The outbreak of the war between the Ignited 
States and Spain w^as, also, a serious matter. It 
deprived the Commission of two ships and the 
naval parties which were working with and 
under its direction, rendering a new organiza- 
tion of parties necessary and with a much de- 
creased force. 

Further delay was caused by the assignment 
of Colonel Hains to militarv duty in command 
of troops at Chickamauga, and later, in Porto 
Kico. 

But in vspite of these troubles and delays the 
work w^as prosecuted as rapidly as practicable. 

As portions of the work were completed, 
parties were withdrawn, until the last surveying 
party left Greyto^vn, February 18, 1899, leav- 
ing 13 men in the country at 10 stations for the 
purpose of continuing the observations for rain- 
fall and evaiK)ration, and for the gaging of the 
lake and the various rivers necessary to a com- 
plete understanding of the hydrology of the 
region of the country through which a canal 
across Nicaragua must pass. 

Soon after the (/Ommission's arrival home, the 
necessities of the war forced it to vacate its head- 
quarters in the Army Building in Xew York, 
and they were removed to Washington, where 
the work of examining, computing and assem- 
bling the data has been steadily prosecuted. 

The Commission desires to express its obliga- 
tions to the Maritime Canal Company, which 
kindly and freely furnished all data and infor- 
mation in its possession; 



To the Navy Department, for assistance with 
ships, parties and instruments; 

To Commanders Tillev and I^utze, command- 
ing the U. S. S. '' Newport," and the U. S. S. 
" Alert," for their excellent surv^eys of Grey- 
town and Brito; 

To the Director of the Geological Sun^ey for 
the services of C. W. Hayes, Geologist, and A, 
P. Davis, Hydrographer; 

To the Chief of Engineers and to the Super^ 

intendent of the Coast Sun-ev for instruments 

«. 

kindly loaned; 

To the Panama Canal Company and the 
Panama Railroad for aid and courtesies ren- 
dered ; 

To E. S. Wheeler, C. E., Chief Engineer to 
the Commission, and to the members of the en- 
gineering staff for their faithful services in con- 
nection with the w^ork. 

Physics. 

To secure the Ix^st location for the canal care- 
ful attention must be given to the physical fea- 
tures of the isthnms and their adaptation to the 
purpose. 

As the repoi-ts of the specialists, hereto an- 
nexed, cover the subjects of geology, topog- 
raphy, hydrology and meteorology quite fully, 
it would seem unnecessary to do more than call 
attention to a few distinct features which char- 
acterize the route on which this (/'ommission is 
directed to report. 

Lake Nicaragua. 

It is an interesting and peculiar feature of this 
route that in early geologic time the lake was 
evident Iv an arm or bav of the Pacific ocean, 
while the Continental Divide traversed the 
isthmus to the eastward in the vicinity of Cas- 
tillo Viejo, and the Rio San Juan, as an outlet 
of the lake, had no existence. This is attested 



NICARAGUA CANAL COMMISSION 



by the remains of an old river channel of large 
dimensions which crossed the Western Divide 
and formed the outlet of the lake after it be- 
came separated from the ocean, and by other 
geologic features. 

An old drainage channel is also traceable 
under the Eio San Juan west of C^istillo, which 
has gradually filled up with alluvium to the 
present bed of the stream. There is, therefore, 
but little rock found in this portion of the river. 

In consequence of the closure of the western 
outlet and the elevation of the lake to a mean 
altitude of over one hundred feet above the sea, 
the outflow was diverted to the eastward over a 
depression in the original divide, so that this 
river now forms the only outlet for tlie drainage 
of the entire basin. 

The physical elements which are of most im- 
portance in the consideration of the problem of 
water supply, lake regulation, storage and oper- 
ation, have been ascertained by obser\"ation, sur- 
veys and measurements as far as possible and 
mav be stated as follows: 



convenient for anchorage. Xear the outlet of 
the lake it shoals to such an extent as to require 
a considerable amount of dredging through soft 
material. Xo rock is found near this portion of 
the channel. The area of that portion of the 
lake extending below sea level is about 20 square 
miles. A steady northeast trade sweeps over the 

lake during a large portion of the year. 

• 

Western Division. 

The lake is separated from the Pacific on the 
west by a strip of land about 12 miles wide with 
a range of hills having heights varv'ing from 155 
feet to more than a mile above sea level. The 
lowest point has been selected for the route of 
the canal, and is where a low plateau sei)arates 
the drainage of the Rio Lajas, which empties 
into the lake, from the Rio Grande, emptying 
into the Pacific near Brito head. This latter is 
a bold, rocky promontory 248 feet high, which 
guards a natural bight in the coast and affords 
an admirable site for an artificial entrance and 
harbor. 



Area of water surface of Lake Nicaragua 2,000,000 acres, 3,000 sq. miles. 

Approximate area of entire drainage basin 12,900 sq. miles. 

Maximum dimensions of Lake Nicaragua 101 x 45 miles. 

Elevation of Lake Nicaragua, 98' to 111', mean 104^' above mean sea level. 

Elevation of Lake Managua (above Lake Nicaragua) approximately 28 feet. 

Area of Lake Managua 438 sq. miles. 

Length of Rio San Juan 121.7 miles. 

Extreme range of temperature on line of canal for 1898 (G5° to 9C^). . . .31 degrees. 

Maximum rainfall observed at Rivas was in 1897, when it was 123.43 inches. 

Minimum rainfall observed at Rivas was in 1890 31.81 inches. 

The average rainfall in the basin for 1898 is found to be 28 per cent, less than that 
at Rivas. 



The lake is elliptical in form and has several 
islands. The principal one, containing the sym- 
metrical cones of the extinct volcanoes Ometepe 
and Madera, rises over a mile above the lake 
level and affords an excellent harbor to leeward. 



The streams of this section are small and have 
a limited drainage, being nearly drv for five 
months of the year. The sIojk? of the upper 
Rio Grande, however, is steep and its bed is 
therefore sinuous and deeply eroded. Between 



REPORT OF THE COMMISSION 



Espinal and the sea, a distance of less than 11 
miles, it falls about 120 feet. The topography 
of the valley is, however, well adapted to the 
purposes of a canal on either bank, or to the 
creation of an artificial basin by a dam closing 
the gorge through which the lake drainage for- 
merly passed to the sea. The rocks on this di\d- 
sion are sedimentarv'^ and readily worked, being 
loose shales and sandstones with traces of cal- 
cium. The material composing the coastal plain 
is a light sandy loam and easily eroded. 

Eastern Division. 

The country traversed by the San Juan may 
be conveniently divided into two sections, to 
wit : that portion lying above the confluence with 
the San Carlos, in which the deposit of sediment 
is relatively small, and that below, in which it 
is large. Further subdivisions are suggested by 
the topographic conditions. From the lake to 
the first rapids at Toro, 27 miles, the slope is 
gentle, being about 2^ inches per mile, while the 
banks are low and the adjacent swamps exten- 
sive. From the head of the Toro to the foot of 
the Machuca, embracing the four rapids, the fall 
is nearly 43 feet in 23 miles, or 22i inches per 
mile. This comprises the rocky section of the 
ancient Continental Divide and is the gorge of 
the river valley. Below Machuca occurs a 
stretch of about 15 miles of deep water, the bot- 
tom of which extends in places to below sea level, 
known as the Agua Muerta (dead water). This 
is a portion of the old river channel not silted up 
by the volcanic sands brought into the lower San 
Juan by the San Carlos river. This sand be- 
comes a characteristic feature of the entire lower 
reach of the river and its delta, from this point 
to the sea. It is confined, however, mainly to 
the bed of the channel, the banks through the 
hill country being the stiff clays resulting from 



the weathering of the rocks of the region. These 
banks are remarkably stable, notwitlistanding 
the heavy rains and large volume of water which 
sweep past their bases at high stages. 

Physics of the Stream. 

As the bed of the upper river forms an im- 
portant part of the route, a more detailed descrip- 
tion of it is believed to be necessarv. 

The slope as given by the survey and corrected 
for stage may be stated to best advantage in 
tabular form. This, taken with the cross sec- 
tions, velocity and volume of discharge as stated 
in detail in the accompanying reports of the as- 
sistants, will show the characteristics of the 
streams in a state of nature. 

San Juan Kfver Statistics. 

Slopes and Distances. — Upper River. 

(Lake at 105.) 

Rate of fall 
M^o^u Distance, Fall, per mile, 

Keacn. miles. feet. feet. 

From the lake to Sabalos. 27.16 5.4 0.198 

Sabalos to foot of Toro 

rapids 1.70 7.8 4.294 

Toro to head of Castillo. . 7.98 1.2 0.150 

Castillo to bottom of rapids .38 6.0 15.789 

Bottom of Castillo rapids 

toPuntaGorda 2.08 2.5 1.202 

Punta Gorda to 1 mile be- 
low Machuca rapids. . .10.62 26.0 2.448 

One mile below Machuca 
rapids to Boca San Car- 
los . .14.79 1.0 0.067 

Upper river 64.71 49.4 0.763 

IX)WER Rn^ER. 

Rate of fall 
M^nnv^ Distance, Fall, per mile, 

Keach. m\\Q%. feet. feet. 

Boca San Carlos to San 

Juanillo 33.02 30.0 0.908 

San Juanillo to Colorado. 5.28 4.0 0.757 
Colorado to ^!ea (via San 

Juan) 18.65 21.0 1.12^ 

Lake to sea 121. 6() 104.4 0.86 



8 



NICARAGUA CANAL COMMISSION 



The slopes are, however, constantly varying 
witli the stage and local conditions. In fact a 
heavv rainfall on the San Carlos basin niav re- 
verse the slope for a time in the Agua !^^uertx^ 
causing the water to run up stream. 

At Sahalos, where the slojw is about 2^ inches 
per mile, the maximum velocities and discharges 
as observed were reported as follows: 

Cro88 section, Mean vclority, Diwhargo, 
sq. tt. ft. iH»r nev. cu. ft. per sec. 



Date. 

Jan. 21, '98.. 8,819 

Feb. 21, '98 . 8,570 

Sept. 11, -98. 11,273 

'' 1-1, '98. 10,684 

" 21, '98. 10,720 

Dec. 3, '98 . . 11,273 



2.10 
1.92 
1.95 
2.12 
2.09 
2.39 



19,000 
16,530 
21,995 
22,673 
22,431 
26,700 



In the up]>er reaches, the slo]>e being verv^ 
flat, the river carried over 20,000 cubic feet 
through sections of over 10,000 square feet at 
velocities exceeding 2 feet per second, with cor- 
responding increase at the gorges and rapids. 

Observkd ^Iaximum Vfxocities of San Juan. 

At Ochoa station, about 69 miles from the 
lake, the banks are steep clay slopes. The bed 
of the river consists of black sand of the same 
character as that comjiosing the sea Iwach near 
Grevtow^n. 

i\u*n Cross section. Mean velocity, Dischartfe, 

iiait. sq.ft. ft. per sec. cu. ft per sec. 

Jan. 8, '98... 13,100 

June 28, '98. 14,462 

Nov. 17, '98. 19,717 

Sept. 12, '98. 10,336 

'' 16, '98. 12,761 

" 2ij, '98. 9,895 

From which it appears that in a state of na- 
ture the mean velocity of the stream is fre- 
quently over 4 feet ix?r second and at times ex- 
ceeding 5, while the lower river disc*harges over 
50,000 cubic feet per second and occasionally 



4.00 


52,400 


4.25 


61,410 


5.32 


104,930 


4.00 


41,199 


4.47 


57,047 


4.24 


41,975 



over 100,000 without i>erceptible effect upon the 
banks. 

The slopes of the stream, therefore, vary from 
about one inch per mile in the Agua Muerta to 
6 feet in one-third of a mile on the rapids at Cas- 
tillo, and the velocitv from less than one foot 
per second to over 12, while the recorded dis- 
charge at Ochoa ranges from 16,145 to 104,930 
cubic feet })er second. To pass the Castillo rap- 
ids at low stages of the river a tram-way has 
been constructed under the brow of the hill 
for the j)urix)se of transferring passengers and 
freight. The width of the upper river is quite 
variable. Its narrowest limits are about 350 
feet, while in some places it wi<lens out to 1200 
feet. Its general alignment is direct, but there 
are several shaq:) horseshoe cun'es where cut- 
offs would be required across alluvial flats by 
which over 4 miles of distance would be saved. 

The Lateral Dkainaoe. 

The principal tributaries from the Costa Rican 
side are the Rio Frio, P(h*(> Sol, San Carlos and 
Sarapiqui, the former emj)tying into the lake 
just at the head of the river. These large 
streams exert a controlling influence in confin- 
ing the location of the canal to the left bank. 
The streams on th(* left bank are the Melchora, 
Palo de Arco, Negro, Sabalos, Machuca, La 
Cruz, Alachado, Danta, San Francisco and oth- 
ers, none of which have a large drainage basin. 
They have many small branches penneating the 
swanqw and ravines which characterize the 
brok(Mi topography of this section. 

On reaching the edge of the coastal ]>lain the 
river drainage is distribute<l through the San 
Juanillo, Colorado, lower San Juan, Taura and 
their branches, Parado and Cafio linivo, leading 
to the sea. 

The minimum computed discharge of the 



REPORT OF THE COMMISSION 



upper river at the Sabalos station during 1898 
was found to be 11,206 cubic feet per second on 
May 13, while the maximum occurred on jS'o- 
vember 13, when it was 28,490 feet, the differ- 
ence in stage being 3.55 feet. At Ochoa, below 
the mouth of the San Carlos, the minimum com- 
puted discharge on May 10 was 16,300 and the 
maximum was 107,000 cubic feet per second on 
Xo vember 17, the variation in stage being 13.35 
feet. To provide for extreme cases, however, it 
is estimated that the river above the San Carlos 
may, at rare inten-als, imder the cumulative dis- 
charges from the lake and river, reach a possible 
maximum of 100,000 second-feet and that the 
San Carlos, a flashv and torrential stream, mav 
add 100,000 more to this quantity in the lower 
section for a short time. 

The Capacity of the Channel. 

The entire river bed has been carefully sur- 
veyed \dth a view to determine its carrying ca- 
pacity imder the regimen resulting from the 
creation of such dams and locks as mav be found 
best adapted to convert it into a navigable chan- 
nel for deep draft vessels. The upper river will 
require dredging from the lake to the Castillo 
rapids, and as the channel as proposed will be 300 
feet wide at bottom and extend to a depth of 30 
feet below the lowest lake level, this cut will 
largely increase the cross section and thus enable 
a larger volume to be discharged without any 
material increase of velocity. Moreover, the 
river falls about 13.9 feet below" the 105 stiige in 
the lake before reaching the head of the Castillo 
rapids so that a dam farther down stream im- 
l)ounding this water would still further augment 
the cross section by raising the surface. As the 
capacity is regulated by the smallest sections, it 
is necessarv to ascertain their location and effects 
upon the discharge under the new regimen. 



The Controlling Section. 

Under existing conditions the ruling sections 
of the stream are found to be at stations 1494 
and 1515 near the head of the Toro rapids and 
Castillo rapids, in that section of the upper river 
betw^een Fort San Carlos and the Castillo Viejo, 
as indicated below. The relation of the existing 
cross section of the stream to that of the im- 
proved section when raised to the upper level of 
the lake and dredged to the requisite depth of 
30 feet with a bottom width of 300 feet, is 
stated in square feet and percentages. 

Relative Areas at Controlling Sections. 



Ijocation. 
Station. 

268 

680 
1,265 
1,494 
1,515 
1,665 
Castillo, 



Miles, ^""^^^ft,"^^ 



5 



13 

24 

28J 

28f 

3H 



7,810 
7,697 
7,960 

2,948 
3,758 

6,435 



5- 

5' 



Enlargred area, Percentagre 
sq. ft. of incieaee. 

I 94.6 

f 94.0 

116.0 

641.0 

775.0 



Lower Machua, 6,060 



15,200 
15,920 
17,200 
21,840 
32,824 

23,406 
44,370 



264.0 
632.0 



From this it appears that the location of the 
controlling section would be changed from its 
present position to a point 5 miles from the lake, 
while the area of that section would be very 
nearlv doubled at a lake elevation of 110 feet 
above tide. As the maximum discharge re- 
quired to pass through this section, with a range 
of 6 feet for the greatest fluctuation, would not 
produce velocities exceeding 3.3 feet per second, 
such a discharge would not materially affect the 
stability of the channel nor its navigation. A 
further discussion of the rc*sulting velocities 
under different volumes of discharge is submitr 
ted by Mr. F. L. Stuart, Assistant Engineer, 
sho\\nng that at no other })lace in the channel 
would the velocity be as great. 



10 



NICARAGUA CANAL COMMISSION 



Computed Velocity in River and Canal at Vari- 
ous Points, with Different Discharges, re- 
ferred to Lake at 110: 



Location. 

Sta. 268 
in Ri\ 

Sta. 680 
in Ri\ 

Sta. 1265 
in Ri 



30,000 50,000 DlgShar^a. Velocity, 

cu. ft. cu.ft. ^*?^, f?^®* feet per 

Velocity, Velocity, ^'^ second, 

ft. per sec. ft. per sec. P®^ ^^• 



3.6 



8 K. oo 55,000 

iver,P'' ""'^ 35,000 2.3 



3.7 



' h-^ 3.1 J0,000 

iver, I 40,000 2.5 



^' ll.' 
iver, J 



2.0 



70,000 
50,000 



4.1 
2.0 



Cut-Off Palo de Arco to Isla Grande. 
Surface of Water 110. 

Discharge, Discharge, 
30,000 60,000 

Location. cu. ft. cu. ft. 

Velocity, Velocity, Various discharges, 

ft. per sec. ft. iwr sec. cu. ft. Vel. cu, ft. Vel. 

In River, 1.16 1.86 2.4 1.66 

62,500 42,500 

In Canal, 1.3 2.2 2.8 1.86 

Cut-Off Sombrero de Quero to Santa Cruz 

River. 
Surface of Water 110. 

Discharge, Discharge, 
30.000 50,000 

Location. cu. ft. cu. it. 

Velocity, Velocity. Various discharges, 

ft. per sec. ft. per sec. cu. ft. Vel. cu. ft. Vel. 

In River, 1.4 2.3 3.56 2.3 

75,000 50,000 

In Canal, 
hot. 150 

In River, 1.03 1.72 2.56 1.72 

75,000 50,000 
In Canal, ) 



2.3 4.00 



5.0 



4.0 



hot. 250 



}>• 



3.23 



4.86 



3.23 



Cut-off 2 miles west of Boca San Carlos. 
Surface of Wat^r 110. 

Discharge, Discharge, 
30,000 50,000 

Location, ou. ft. cu. ft. 

Velocity, Velocity, Various discharges, 

ft. per sec. ft. per sec. cu.ft. Vel. cu. tt. Vel. 

In River, 0.6 1.0 2.01 1.0 

100,000 80,000 

In Canal, 0.7 1.18 2.36 1.8 



2 Dams Above (\tt-Off, H-Lock System. 
Surface of Water 82.4. 

Discharge, Disdiarge, 
30,000 50.0U) 

Location. cu. ft. cu. ft. 

Velocity, Velocity, Various discharges, 

ft. per sec. ft. per sec. cu. ft. Vel. cu.ft. Vel. 

In River, 0.8 1.35 2.7 — 

100,000 — 

In Canal, 1.23 2.1 4.1 — 

2 Dams Above Cut-Off, 6-Lock System. 
Surface of Water 73.2. 

Discharge, Discharge, 
30,000 50.000 

location. cu. ft. cu. ft. 

Velocity, Velocity, Various discharges, 

ft. per sec. ft, i>er sec. cu.ft Vel. cu fi. Vel. 

In River, 0.83 1.30 2.77 1.2 

100,000 80,000 

In Canal, 1.30 2.17 4.33 3.45 

This table further demonstrates that instead 
of having velocities exceeding 12 feet per second 
over the rapids, which would he submerged, the 
maximum current in the river under a discharge 
of 30,000 cubic feet would not exceed 2 feet or 
IJ miles per hour, which would not readily dis- 
turb the banks of this section of the stream. 
Under ordinarv conditions and throughout 

nearlv this entire reach the velocities wouM be 

ft- 

less than one foot per second. 

With a discharge of 50,000 cubic feet, which 
is higher than will probably (»ver be reached in 
this (upper) part of the river, the maximum ve- 
locity through the controlling sections would not 
therefore much exceed 3 feet jxt second, impos- 
ing no material restrictions on navigation. 

Stability of Slopes. 

Xature's Com}M?nsations. 

So much stress has been laid upon the exces- 
.sive ])reci])itation and its destructive (effects uix>n 
the ])roposcd works, as well as u])on the labor 
and machinerv' requiivd, that the Commission is 
impelled to call attention to the fact that the 



REPORT OF THE COMMISSION 



11 



physical features of the country furnish the most 
conWncing and conchisive evidence that these 
uncontrolled forces are not so injurious as has 
been alleged, for the angle at which freshly 
made earth-slopes stand is found to be much 
steeper than that prevailing in our more north- 
ern latitudes, where they are also exposed to the 
destructive action of frost and the internal stress 
due to greater ranges of temperature. In some 
cases in the northwest the range covers 160 de- 
grees, whereas in Nicaragua the greatest fluctua- • 
tion seldom exceeds 25 degrees. The absence of 
frost more than compensates for the excessive 
downpour. 

Observ^ations by engineers of experience in 
tropical countries, lead them to believe that the 
same security and greater permanency may be 
obtained with less first cost and economy of 
maintenance by making the side slopes steeper 
and thus reducing the prisms of cut and fill, 
than by employing the typical sections of our 
own latitudes. Xature compensates for the 
greater rainfall by the uniformity of heat and 
moisture. The spontaneous growth of vegeta- * 
tion revets the natural surface, clothing it with 
a protecting thatch which not only acts as an 
elastic cushion to break the impact but also to 
retain the water and thus prevent the sudden 
and destructive floods so familiar to us during 
the spring, when the rain and melting snows 
combine to produce their maximum effects. 

The Board of 1895, in referring to the char- 
acter of the work done in Grevtown harbor, re- 
marks that " The material excavated was almost 
entirely volcanic sand, similar to that of the 
beach. . . . When piled in heaj^s it fonns a por- 
ous mass through wliich the toiTential rainfalls 
descend with suq)risiiigly little effect upon its 
contour, even though the slopes be steep. This 
feature was noted both in the mounds of dredg- 



ings near the entrance and in the canal banks, 
where the sands dropped from the dredge chutes 
still stood seemingly undisturbed since they were 
put there." 

Of the cuts along the railroad the Board also 
adds: "The cuts have heights up to 20 feet, 
^vith slopes from vertical to 45 degrees, and in 
most cases stood with an extraordinary stability 
under the tropical downpours. At several, the 
original tool marks were still visible, both picks 
and steam shovel. In several others, there had 
been slides, but none of great extent. The 
ditches were generally clean and in but few 
points had wash reached the rail. The surface 
of the cuts was in some cases protected by vines, 
but in most was quite bare unless for a minute 
lichen. 

"As these clay cuts have been exposed for 
over three years to the severest rainfall of record 
on this continent and were found in better con- 
dition on the whole than an exposure in the 
United States for a single winter would have left 
them, it is evident that the absence of frost more 
than balances the tropic downpour and for the 
material in question constructions can quite as 
safely be designed as in the United States. . . . 
The natural growth in the road-bed was unex- 
pectedly slight, although in two or three cases 
the canebrakes had invaded the track. 

** On the whole, taking into account the con- 
dition of the sand dumps at Greytown and of 
the clay cuts and fills on the line of the railroad, 
it is evident that the heavy rainfall is not neces- 
sarilv as formidable an obstacle to outdoor con- 
struction as might be supposed." 

The Geologist, Dr. Hayes, also states, con- 
cerning the resistance of the slopes to abrasion 
on the western division, that 

** The present channel of the Rio Grande is 
from 15 to 25 fi*et in depth and its sides are gen- 



12 



NICARAGLTA CANAL COMMISSION 



erally steo]>, often nearly or quiti^ vertical, out there was no mortality in the country. The 
They serve to show the capacity of the material constant motion of the wind, sweeping through 
to staml at very steep slopes. It would also this low divide, appears to I'emove the noxious 
probably form fairly imix^rvious embankments." exhalations which characterize other portions of 
There is no reason, therefore, for departing the isthmus. Yellow f(»ver finds no habitat at 
from the usual engineering ])ractice, unless it be ( Jreytown and even when im})orted it does not 
to make the slopes steeper and thus redu<'(» the become ei)ideniic. Abstemious habits and care- 
cube of excavation and the conseipient cost of ful police of camps will insuiv as gooil health 
the work. amongst laborers as will be found in many lo- 
calities in this country. The climate would af- 
Saxitarv and CLniATir. f^^.^ ^j^, IqX^ov question, therefore, chiefly by the 

The impression that this jiortion of the isth- lassitude resulting from its enervating influence, 
mus is unasually unhealthy, is eiToneous. On Assistant Engineer Stuart says that, ** The 

the contrarj', the Iwal conditions are such that atmospheric conditions are excellent, and for the 

with ordinarv hygienic precautions the risks r^vvon months we were in the field, we worked in 

from disease are slight. all conditions of weather, losing but one entire 

The frequent rainfall on the east coast fur- day on account of a heavy down}>our of twelve 

nishes an ample supply of frt^-^h, soft water con- houi*s." 

densed directly from the clouds; the porous Tlu^ narrow limits within which the temjx^ra- 

sandy soil absorbs it so rapidly as to prevent ture ranges are shown from a few stdected ob- 

stagnation, while animal refuse is quickly re- scrvations at various stations during the year as 

moved by the scavenger birds and tish con tin- below. The l{io A'^iejo station is locat<:»d on the 

ually on the alert for food. west(mi slope of the Cordilleras east of the lake 

With their light, hx>se clothing, vegetable and at a higher altitude than the othei*s. Hence 
diet and cleanly habits, the natives ^^eldom suf- its greater range of J50^. This uniformity of 
fer from fevers. Even our unacclimated Ameri- temi)erature is one of the important factors in 
cans passing from a rigorous winter temperature the consideration of the iK'rmanency of import- 
to the mild region of the trade winds were, with ant works as well as in the health of the inhabi- 
few excej)tions, exempt from febrile complaints, tants. 
and amongst the large number of engineers sent 

Exhibit ok Extreme Kanoe of the Observed Temperatire in Nicaragua. 

lA^cati«m. Date, 1H96. Maximum. Minimum. Dato, 18U8. Kaiif^>. 

Brito and Tola Stations Dec. 22, 88° F. 75^^ E. June 28, 13° 

Liis Lajas Station ifay 12, 91° E. 7:]° E. Sept. 10, 18^' 

Rio Viejo Station Mar. 3, 97"^ E. (>2^ E. Mar. 12, 35° 

Eort San Carios Station May 8, 91 ° E. 70° E. Mar. 28, 21 ° 

Sabalos Station Mar. 20, 90° E. 05.2° E. Dec. 25, 2-1.8^ 

San Carios Kiver May 7, 95° E. 00° E. Eeb. 7, 29° ' 

Ochoa Station ..Oct. 1, 95° E. 00.5° E. Jan. 3, 28.5° 

Deseado River Station May 25, 9 1 ° E. 05=^ E. Jan. 3, 20° 

Greytown Sept. 29, 90° E. 09° E. .Mar. 14, 27° 



REPORT OF THE COMMISSION 



13 



Earthquakes and Volcanoes. 

From the most reliable data obtainable the' 
Commission believes that the canal region is 
practically exempt from any seismic influences 
of sufficient force to cause destruction or danger 
to any part of the canal route or suspension of 
its traffic. Dr. C. W. Haves has treated this 
question fully in his report.' He says that: 

" Earthquakes due to the dislocations of strata 
(faults) are perhaps no more liable to occur in 
the vicinity of the Nicaragua Canal Route than 
elsewhere, and hence thev do not constitute a 
danger which is peculiar to this region more 
than to almost any other in which a ship canal 
might be constructed." 

He then proceeds to discuss those due to vol- 
canic agencies at some length and concludes 
that those activities are on the wane and so re- 
mote from the route as not to constitute a men- 
ace. In quoting from Major Button, he adds: 

" Briefly, then, the risk of serious injury by 
earthquakes, to the constructions proposed for 
the Pacific section of the canal is so small that it 
ought to be neglected; . . . also that the 
risks to the Atlantic section are still smaller than 
those to the Pacific section." 

Materials for Structural Purposes. 

The cost and durability of the canal are also 
affected by the character and distribution of 
such native material as may be utilized for the 
purposes of construction. These consist chiefly 
of earth, rock, timber and sand, all of which are 
abundant and free. Cement, iron, explosives, 
tools, plant, and some provisions and clothing 
will need to be imported but ^\all be exempt from 
duty. 

Alluvium.' 

" All unconsolidated material w^iich has been 
transported and deposited by streams is classed 



' See Report of Dr. Hayes, Appendix II. 



as alluvium. ... It varies considerably in 
composition, dei)ending ui>on the source from 
which it was derived and the manner in which 
it was deposited. It varies all the way from 
coarse, clean-washed sand or gravel to the finest 
clay. It may for convenience be separated into 
three sub-classes, (1) sand, (2) silt, a variable 
mixture of fine sand and clay, and (3) clay-silt, 
composed chiefly of clay, with little or no sand. 
All three subclasses contain variable quantities 
of vegetable matter. 

" The alhudum is everywhere of such charac- 
ter that it can be e^ly handled with dredges. 
Almost everywhere the silt and clay-silt are suffi- 
ciently solid to stand at moderate slopes, the 
slope of one on one probably being sufficient. 
In some cases, as in the Florida lagoon, special 
precautions may be needed to preserve the slopes. 
The material becomes very hard when dry, and 
even when it is piled up so that the water can 
drain off it becomes comparatively firm. This 
is shown in the vertical stream banks where 
drainage is possible, while the same material 
forms a soft mud in the swamps at some distance 
from the stream channels. The black sand when 
free from clay is, of course, quite pensions to 
water and would not be suitable for banks where 
the water level was permanently different on its 
two sides. This material, however, will not be 
encountered beyond the site of the first lock on 
the proposed low-level line. It is probable that 
wherever the canal is more than lialf in excava- 
tion the silt will form banks sufficiently imper- 
vious to hold the required height of water with- 
out the addition of anv other material. Where 
the head is greater than fifteen feet it may be 
necessary to add a puddled core to the bank 
unless the latter is made of more than ordinary 
thickness.'' ^ 

OAND. 

The black volcanic sand of the east coast and 
lower river section is not composed of the partly 



14 



NICARAGUA CANAL COMMISSION 



decayed minerals derived from a deeply weath- 
ered rock, but is made up entirely of finely com- 
minuted fragments of fresh volcanic rock evi- 
dently broken up and ejected by explosive vol- 
canic eruptions. It would thus make a good, 
sharp, clean material for hydraulic mortar, con- 
crete or beton. Its specific gravity is 1 . 68 or 
104 lbs. per cubic foot, comparing very favor- 
ably with the best building sand in the United 
States. 

Clay. 

Clay of excellent quality is abundant and wtU 
distributed. When mLxed in suitable propor- 
tions with sand and gravel, it makes an admir- 
able puddling material. 

" Quartz occurs in only a few of the rocks, so 
that much of the clay is remarkablv free from 
grit, tough and compact. Although it is pene- 
trated by numerous roots and burrowing insects, 
the absence of frost permits it to remain more 
compact than any surface clay in higher lati- 
tudes. Next to the silt it will form bv far the 
largest part of the excavation. It will make per- 
fectly impervious embankments if some means 
are taken to puddle it as it is deposited, but 
probably if simply dumped in the bank it would 
be pervious to water." ' 

Wood. 

Numerous large trees occur in the forests 
along the river and on the border of the lake, 
which are denser and stronger than our Ameri- 
can oaks and pines. The clearing of the canal 
route will also furnish a large number of cross- 
ties. Some of these native woods, according to 
Col. Childs, will last above ground from forty 
to fifty years. The Madera Negra is one of the 
most valuable for ties and is abundant. It mav 



1 See Report of Dr. Hayes, Appendix II. 



also be obtained for dimension timber up to 
thirty-foot lengths and eleven inches square. 

The Nispera will cut in lengths of fifty feet 
and square eighteen inches. It is very com- 
mon and durable, but heaw. Manv other va- 
rieties exist, as the Palo Cortez, Guachipilin, 
Roble, Cocobole, Pine, Cedar, Xiambaro, Ca- 
oba or Mahogany, Palo-de-Arco, Granadillo, 
Guyacan, Almendro, Feniscaro, etc. The ship- 
ment of timber is one of the industries of the 
port of San Juan del Sur. As much of the na- 
tive timber is valuable for export and as no mills 
exist for its local manufacture, it mav doubtless 
prove more expedient to import the piling and 
dimension material from the extensive forests of 
the Southern States and to use the local product 
mainly for fuel and ties. 

Shelter. 

There is also ample material available without 
cost, for the protection of men and materials 
from the rain and sun. The usual habitations 
of the natives consist of a carefully laid thatched 
roof, substantially built, reaching nearly to the 
ground, with walls of bamboo or adobe. These 
afford free circulation of air and are cool and 
dry. Their only cost is for the labor of erection, 
which is slight. 

The fuel in general use is wood, which is cut 
and stacked under shelter on the banks of the 
river. A considerable quantity of cord w^ood 
can be secured from the clearing of the route 
and adjacent forests. In some localities water- 
power may be made available. 

Iron and Steel. 

These metals will necessarily be imported, but 
the climatic conditions are such as to cause re- 
markably little deterioration. Templates of the 
rails which have been exposed to the rain and sun 



REPORT OF THE COMMISSION 



15 



for about nine vears do not exhibit anv measnr- 

able loss in section of weight. The spikes also 

retain the sharp edges of the tool marks on their 

heads and shanks. Onlv where the salt water 

of the ocean reaches the iron rails and bolts on 

the pier is there any considerable amount of 

scale visible. 

Stone. 

A large amount of material on the route of 
the canal, classified as rock and soft rock, will 
require excavation to create the channel. A 
portion of this is suitable for structural pur- 
poses. On the western division the rock is 
generally a calcareous non-fissile shale, inter- 
stratified with beds of sandstone varying from a 
few inches to two or three feet in thickness. 
The shales constitute the greatest bulk of the 
rock to the eastward of Brito Head, where the 
sandstones of the northern headland are too 
thin for use as building stones but are suitable 
for concrete or rip-rap. 

About half a mile east of Brito, however, is 
found a group of heavy sandstone beds forming 
a spur extending into the Kio Grande valley. 
" These beds would probably yield a good 
quality of dimension stone; would be easily 
quarried in dimensional blocks up to 20 or more 
inches in thickness; w^ould dress readilv and be 
as durable as the average sandstone." * 

North of the canal line at Buen Ketiro is a 
large deposit of intruded andesite or trap which 
makes a verv desirable material for structural 
purposes. 

** It is probable that all the material on the 
west side which has been classed as soft or dis- 
integrated rock can be excavated with a steam 
shovel without blasting. The material stands 
in natural slopes of 60° or more (to the hori- 
zontal) and artificial slopes equally steep will 
probably be entirely safe." * 



I See Report of Dr. Hayes, Appendix II. 



The rocks on the eastern division are chiefly 
of igneous origin, but from a few miles below 
Castillo to half-way between Machuca and Boca 
San Carlos they are largely sedimentary with 
a few small igneous dikes. 

Xo coarse conglomerates nor pure limestones 
have been discovered in this formation, although 
thev mav occur. " The beds of massive sand- 
stone exposed on Machuca creek being to a large 
extent free from joints could probably be quar- 
ried for dimensional building stone, which would 
be easily worked and fairly durable." * 

The principal varieties of the igneous rock 
found in this section are augite-andesite, olivine 
basalt, hypersthene basalt and dacite. The first 
three are commonly known as trap rocks. They 
are generally compact and heavy. The dacite is 
lighter than the trap and somewhat softer. (This 
w^as called conglomerate by the Canal Company.) 

The basalt (trap) extends from the Boca San 
Carlos eastward bevond the San Francisco hills, 
forming the Sarapiqui hills and others bordering 
the lower portion of the San Juan river as well 
as those in the vicinity of Silico lake, and is 
suitable for dams, jetties and concrete. 

The dacite is found at lower Ochoa and Tam- 
bor Grande, where it comes to the surface and 
continues to the Eastern Divide. It is there 
interbedded with the andesite tuffs and basalt 

Associated with the above-named massive 
rocks is a group of fragmental igneous rocks 
whose members vary from coarse conglomerate 
or breccia to beds of fine volcanic ash. The 
coarser varieties resemble in their physical prop- 
erties the igneous rocks from which they are de- 
rived, while the fine ash is generally talcose and 
crumblQs on exposure to the air. 

Deposits of hard rock also exist near the site 
(^f Lock Xo. 1 of the Canal Company's line to 
which the railroad has been built. 



16 



NICARAGUA CANAL COMMISSION 



Several outcrops of rock reported to be suit- 
able for jetty construction exist on the coast 
at Point of Rocks and at Monkey Point, but no 
samples from these ledges have been secured. 
The quarries are readily accessible from the sea 
and furnish material for ballast to coasters. 

Classification and Weathbrino. 

" The three classes of materials — alluvium, 
residual clay and soft rock — should be consid- 
ered as earth in making estimates for excavation. 
The soft rock, however, may require some blast- 
ing, particularly toward the bottom and where 
it contains very large boulders. It will stand 
with much steeper slopes than the silt and clay 
and will be less liable to slip. Not being plastic, 
it will also support a heavier load, and hence may 
be relied upon for foundations where the weight 
of the structure is not excessive. For these 
reasons it seems desirable to make the distinction 
between clay and soft rock wherever possible." * 

The weathering of rocks is brought about by 
two processes — rock disintegration and rock 
decay. The first varies directly and the second 
inversely with latitude when humidity is con- 
stant. The first process depends on changes 
. of temperature and expansion of interstitial 
water by freezing, hence is inactive in the 
tropics. The second process depends on high 
temperature and a rapidly decaying vegetation, 
hence is active in the tropics. Special atten- 
tion is directed to the fact that it is chiefly the 
first process of disintegration which is inimical 
to the permanence of structures, and hence that 
their relative durability will be greater in the 
tropics than in higher latitudes. 

Such being in brief the physical conditions 
of the route, it remains to determine the dimen- 
sions, which, all things considered, will best 



1 See Report of Dr. Hayes, Appendix II. 



subserve the interest of the world's commerce in 
making this transit of the isthmus. 

Dimensions of Canal. 

To provide ample facilities for the safe and 
expeditious passage of vessels, the trunk of the 
water-way has been considerably enlarged over 
that of any previous project. The dimensions 
adopted by the Commission as the basis of the 
estimates are as follows: 

The canal nowhere to be less than 30 feet in 
depth. The width varying with the local con- 
ditions as follows: From Grey town harbor to 
Boca San Carlos the bottom width to be 150 
feet with slopes in earth of 1 : 1 and in alluvial 
silt of 1 : 2. In hard rock vertical sides up to 
40 feet from the bottom, then slopes of 5 : 1. 
In soft rock the slopes to be 2 : 1. 

In the river the \Wdth at bottom to be 300 
feet, with slopes of 1 : 2 with enlargements at 
the bends, and at the eastern end of the lake the 
excavation to be 600 feet wide at the outer end, 
decreasing to 300 feet at the river, and having 
slopes of 1 : 5 to the depth of 6 feet and then 
1:3; for all routes from the Caribbean sea to 
the lake, excepting the Menocal route, the same 
dimensions are used. The bottom width of the 
canal from the lake to the Pacific to be 150 feet, 
with slopes as on the east side, and the compu- 
tations have been based upon a minimum lake 
elevation of 104 feet above mean sea level, 
Caribbean sea, as a datum. The minimum 
radius is limited to 3000 feet with enlargements 
of width in bends varv'ing according to the de- 
gree of curvature. 

The locks are 80' x 30' x 665' between quoins, 
giving an available length of 620 feet with varia- 
ble lifts. 

Estimates were also made upon numerous 
modifications of the above dimensions. 



REPORT OF THE COMMISSION 



17 



10.3 

9.1 

50.0 

131.0 
84.0 
73.0 

210.0 



For convenient reference and comparison with 
the canal prism as proposed by the Maritime 
Canal Company, the areas of the several cross 
sections and the percentages of increase are 
stated herewith: 

Area of cross 
sections in wiuaro Per cent, of 
feet. increase. 

Between jetties, Greytown, 23,400 
Entrance to harbor. Grey- 
town \ 14,700 

Coastal section 6,300 

Canal proper 5,400 

Through rock 4,500 

In the river (in rock) 9,900 

In the river (in earth) .... 10,800 

I'^t^^i*'^^ { is%l 

WEST SIDE. 

Area of cross 
sections in square Per cent, of 
feet. increase. 

Western Divide 4,500 50.0 

Across coastal plain 5,850 8.0 less 

Distances along the line of the Canal route pro- 
posed by this Commission from the seven- 
fathom curve in the Pacific ocean to the 
seven-fathom cur\'e in the Caribbean sea: 

Miles. 

1. Brito Harbor 0.93 

2. Brito to Buen Ketiro 8.12 

3. Buen Retiro to west side of lake 8.71 

4. Lake Nicaragua 71.34 

5. East side Lake Nicaragua to Boca San 

Carlos 5G.96 

6. Boca San Carlos to Sarapiqui 21.59 

7. Sarapiqui to Greytown 20.59 

8. Greytown Harbor 1.74 



Total 189.98 

Kegulatiox of the Lake Level. 

All plans for a canal by the Nicaragua route 
contemplate using the lake as the summit for the 



canal and as a feeder. The regulation of its 
level is therefore a matter of the greatest im- 
portance. 

It is known with reasonable certainty that the 
lake has varied in its elevation above sea level 
as much as 13 feet. It has probably been as 
low as 98 feet above mean sea level and as high 
as 111 feet above the same plane. These ex- 
tremes have occurred at relativelv remote inter- 
vals, but their occurrence must be admitted, 
and their recurrence in the absence of regulating 
works must be reasonably anticipated. It is also 
known, as a result of the observations of 1898, 
that notwithstanding the losses due to the out- 
flow through the San Juan river and to evapora- 
tion, the lake has risen as much as two feet in 
six weeks. 

The higher the lake is held the less will be the 
excavation in the upper level, and as this is a 
heavy item in the cost of construction, the effort 
has always been to keep that level up as high as 
practicable, without causing unnecessary dam- 
age to private property. On the other hand, 
a spillway of capacity sufficiently great to pre- 
vent the lake from rising is expensive. The 
problem, therefore, is how best to meet the vary- 
ing conditions. A careful investigation has 
been made of the discharge of all streams of 
importance, measurements of rainfall observed 
at points widely distributed throughout the 
basin, and the rate of evaporation from the lake 
surface determined. 

The area of Lake Nicaragua, in round num- 
bers, is 3000 ?i(iuare miles, nearly 2,000,000 
acres. The drainage area, including both lakes, 
is about 12,000 square miles. During the dry 
season of 1898 measurements were taken to de- 
termine the total inflow into Lake Nicaragua, 
which was found to be onlv al)ont 1700 cubic 
feet per second, showing that in the dry season 



18 



NICARAGUA CANAL COMMISSION 



the inflow into the lake is very small, scarcely 
worth considering. Nearly all the streams 
showed evidences of being stagnant several 
months, yet the year 1898 was one of more than 
average rainfall. 

Kainfall. 

Observations to determine rainfall have been 
kept at Rivas for the last 19 years. During the 
year 1898 obsers^ations were taken at several 
scattered stations in the drainage basin to deter- 
mine the rainfall of the lake region. These 
records are given in the accompanying ap- 
pendices. 

Comparing the records at Rivas for the year 
1898 with those for the other points, it will be 
noted that the rainfall at Rivas was greater than 
the averiage for other parts of the basin ; that at 
Rivas being 108 inches and the average in the 
basin 78 inches, a difference of about 28 per 
cent, in favor of Rivas. This might at first 
appear anomalous, but it may be accounted for 
by the peculiar topographical features of the 
country in connection with the prevailing winds. 
It will therefore be assumed that, in order to 
obtain the rainfall in the basin for other years 
than that of 1898, the Rivas record will have to 
be reduced by 28 per cent. The number of 
observation stations in the basin are not great, 
but they offer a basis for estimating rainfall in 
those years for which there is no other record 
than that of Rivas. 

There are two distinctly marked seasons in 
the drainage area of the lake — the wet and the 
dry. The latter begins about December 15 and 
lasts until about May 15, a period of five months. 
The wet season then begins and lasts until De- 
cember 15 following. This period has a dura- 
tion of about seven months. It is probable, 
however, that the length of the wet and dry sea- 



sons may vary in some years, but it is well un- 
derstood among the people in that region that 
those are the dates from which they are reck- 
oned, and the observations for the year 1898 
confinn this. 

Evaporation. 

The amount of evaporation as determined for 
the year 1898 was 52 inches. That year was 
an abnormally wet one and it is therefore prob- 
able that the evaporation was somewhat below 
the average. Mr. Davis estimates a normal 
annual aggregate at about 60 inches, or five feet. 
The amount of evaporation in the lake itself is 
greater during the dry and less in the wet period. 
It has been taken at 4 inches per month during 
the wet period, and 6 inches during the dry, 
which corresponds closely with the observations 
for 1898. 

These results have been checked by the Com- 
mission's study of the exhibits, as follows: 

From Plate XVIII, Appendix HI, it appears 
that during the year of 1898, throughout which 
careful observations were made, the lake fell 
about 3.09 feet between January 6 and May 15, 
a period of 131 days or 4.5 months, while in the 
following season of rainfall it rose 4.72 feet by 
December 5, when it again began falling. The 
net gain in storage during this entire year from 
January 5, 1898, to January 5, 1899, was 15.6 
inches. 

It will be observed that during that portion of 
the season beginning February 1 and ending 
May 15 the lake surface declined uniformly (the 
slight fluctuations being due to wind and not to 
rainfall), and that in this time the total rainfall 
did not exceed 2f inches over the lake surface. 
The run-off from the parched ground at this sea- 
son is practically zero. Hence the only gain 
was the direct rainfall while the losses were those 



REPORT OF THE COMMISSION 



19 



due to evaporation and outflow, which latter 
quantity was measured by continuous observa- 
tions at the Sabalos station on the San Juan 
river, the onlv outlet. 

The outflow between February 1 and !^[ay 15 
is given as 2,817,748 acre-feet, equivalent to a 
vertical depth over the lake area (2,000,000 
acres) of 1.408 feet. If this be deducted from 
the loss in storage and rainfall, which is 2.840 
feet, it leaves 1.432 feet loss due to evaporation 
in 104 days, or a diurnal rate of .165 inch 
(i"), or 5 inches per month, or a rate of 5.00 
feet per annum for a dry year. This being de- 
duccd during the dry season would doubtless 
represent the maximum for the year. 

Run-off. 

The run-off or inflow to the lake, from 
rainfall on its drainage basin exclusive of the 
lake proper for the year 1898, has been found 
to be about 30 per cent, of the rainfall. This 
is computed as follows: The average rain- 
fall at six stations in the basin of Lake Nica- 
ragua for 1898, was 78.29 inches. During that 
vear the lake rose 18 inches. The outflow if 
held would have raised the lake 84 inches. 
Evaporation as determined was 52 inches, so 
that if there had been no outflow nor evapora- 
tion the lake would have risen 154 inches. Of 
this, 78.29 was by direct fall on the lake, leav- 
ing 75.7 inches as the rise due to the fall on 
the land, or the rim-off. The area of the lake 
is 3000 square miles; the area of the tributary 
basin is 9900 square miles. The latter is, there- 
fore, 3.3 times that of the former. Dividing 
the inflow into the lake, 75.7 inches, by 3.3, 
tlio ratio of the lake surface to the exterior 
drainage, we have 22.94 inches as the rise 
due to run-off. This is 29.3 per cent, of the 
rainfall. 



Lockage. 

When the canal is built, the lake will be 
drawn upon for water for lockage and for power. 
There will also be some leakage, the amount 
depending largely on the kind of dams and 
waste-ways used. The estimate for leakage is 
necessarily arbitrary, but a computation based 
on large traffic through the canal gives three 
inches as the estimate for annual requirements 
for lockage, leakage and power. 

Regulation. 

The surface of the lake is acted upon by sev- 
eral opposing forces. They must be so regulated 
that its fluctuations can be controlled within 
proper limits. Evaporation, outflow and use of 
the canal will lower the lake's level. Rainfall 
and inflow will raise it. Water must therefore 
be stored for evaporation and use, and the ex- 
cess of rainfall and inflow be discharged. For 
purposes of storage against evaporation years of 
minimum rainfall must be considered, and for 
determining spillway capacity years of maximum 
rainfall. 

The data for an absolute determination of 
these problems would necessitate a series of ob- 
servations extending over many years. But 
with the records for 1898 in connection with the 
rainfall records of Rivas for the past 19 years, 
conclusions may be reached which, while they 
may not be absolutely correct, will be sufficiently 
close for all practical purposes. 

The year of minimum rainfall, as determined 
by the Rivas record, is 1890. During that year 
31.81 inches of rain fell. If this be reduced 
by 28 per cent., the difference between Rivas 
and the average of other parts of the basin, we 
have 22.9 inches as the average for the basin in 
an extreme drv vear. It is well known that 
variations in annual rainfall are greater at sin- 



20 



NICARAGUA CANAL COMMISSION 



gle stations than over an extended area. It is 
therefore probable that this estimate is too low 
for a very dry year. Twenty-eight inches have, 
therefore, been assumed as the minimum annual 
rainfall in (he basin. 

The estimated run-off for 1898 was 29.3 per 
cent, of the rainfall, and as the nm-off will di- 
minish with the diminution of rainfall, 25 per 
cent, of the rainfall has been taken as the 
average for a dry year. We then have 28 inches 
falling directly on the lake and 28 inches on the 
drainage area tributary thereto. The latter be- 
ing about 9900 square miles, enough water 
would fall on the land to raise the lake 23.1 
inches. This added to that falling direct would 
raise the lake 51.1 inches if all sources of loss 
were cut off. But the loss from evaporation 
would be about 60 inches, and three inches would 
be. lost by lockage, leakage and use — a total of 
63 inches, or 5 feet and 3 inches. There would 
then be a deficit of 11.9 inches at the end of 
the year. If the year ends with the end of the 
wet period, the succeeding dry period will be 
begim with this deficit. For this period, lasting 
about 5 montlis, during which the lake would 
receive practically no rain, and evaporation 
would be at the maximum, the loss to the lake 
would be 30 inches for evaporation and 1^ inches 
for lockage, leakage, etc., total loss 31-^ inches, 
which, added to the deficit of 11.9 inches, gives 
43.4 inches as the deficit at the beginning of the 
wet season, when the lake would probably fill 
up again. Temporary storage of about 4 feet 
in the lake is therefore needed to provide for 
evaporation and use in a time covering two dry 
periods and one wet one. In other words, if 
the lake had been at 108 at the beginning of the 
first dry period, it would have fallen to 104 at 
the end of the succeeding dry period. 

Substantially the same result is reached by 
^Ir. Wheeler in another way (see his report). 



In a year of maximum rainfall and minimum 

* 

evaporation the conditions are revei'sed. The 
problem will be to get rid of surplus water and 
prevent the lake from rising to a high level. 

The year of maximum rainfall, according to 
the Rivas record, was in 1897, when 123 inches 
fell. Keducing this by the 28 per cent, ratio, 
we have a rainfall in the basin of 88.6 inches for 
the maximum year. As l>efore stated, the varia- 
tion in annual rainfall over a large area is not 
as great as it is at one station. It is therefore 
probable that for the entire basin this estimated 
rainfall is too great. Suppose it be taken at 84 
inches, or 7 feet, there results: 

Rainfall direct on the lake. . 84 inches 
Run-off, 30 per cent., about. 84 



Total inflow 168 

Deduct for evaporation and 
use 03 



u 



10 



i> 



** =8' 9 



ff 



This represents what must be taken care of 
by storage and discharge. 

This rainfall will not be extended uniformlv 
over a year, but most of it will fall within the 
wet season of seven months. A mean discharge 
of about 40,000 cubic foot i)er second would 
discharge it all in this time Or, if four feet be 
stored in the lake, a moan dij^charge of 22,000 
cubic foot per second would take oaro of it. In- 
asmuch as it is imposv-iihlo to know in advance 
whether the rainfall of a season is to bo heavy or 
light, it will not l)e safe to begin discharging at 
the full capacity of the outlet imtil enough water 
has been stored for possible doficioncies. Con- 
sequently, instead of having seven months' time 
in which to discharge the sui'plus, a large part of 
it might have to be discharged in a loss time, 
and a spillway of greater capacity would be 



REPORT OF THE COMMISSION 



21 



needed. With a spillway capacity of 50,000 
cubic feet per second the entire siirplns could 
be handled in al>out 92 davs. 

The following method is used by Mr. E. S. 
Wheeler for determining the amount of water 
to be taken care of in years of maximum rain- 
fall: 

"Between June 18 and October 29, 1898, a 
period of 132 days, the rainfall at Rivas was 
70.30 inches; the lake rose 48.00 inches; the 
outflow lowered it 32.70 inches and the evapora- 
tion of the lake surface lowered it 10.38 inches. 
Therefore, if there had been no evaporation on 
the lake nor outflow from it, it would have risen 
97.04 inches. 

" Between May 17 and October 27, 1897, a 
period of 104 days, the rainfall at Rivas was 
112.42 inches. This was the period of greatest 
rainfall shown in the Rivas records since 1879. 
The amount of fluctuation in the surface of Lake 
Nicaragua caused by this rainfall was not ob- 
served; an attempt will be made to determine it 
by comparison with the wet portion of 1898, 
when both fluctuations and rainfall were care- 
fully measured. The problem may then be 
briefly stated as follows: If a rainfall of 70.30 
inches in 132 davs would cause a rise in the lake 
surface of 97.04 inches, w^hat rise would be 
caused bv a rainfall of 112.42 inches in 104 
days? The ratio between rainfall and change 
in lake level, as given in the preceding table, 
cannot be used for this problem, because in this 
case only portions of a season are considered. 
At the beginning of these periods the streams 
and marshes were drained and empty; at the 
end they were overflowing and the entire nm- 
off due to the rainfall had not vet occurred. 
Therefore, this problem must be solved as a 
special case. If the rise w^as exactly propor- 
tional to the rainfall it would be 143.7 inches, 



provided there w^as no evaporation on the lake 
or outflow from it. It is, however, probable that 
in this case as in the preceding one, the greater 
dailv rate of rainfall in 1897 w-ould cause the 
lake to rise slightly more than the proportional 
amount. An examination shows that the daily 
rate of rainfall in 1897 was 18 per cent, greater 
than in 1898. losing the ratio as before, the 
rise in the lake would be 22 per cent, greater. 
Applying this per cent., the computed rise in the 
lake for 1897 would be increased from 143.7 
inches to 148.58 inches. This, then, is the esti- 
mated amount of fluctuation that would have 
occurred during the period of greatest rainfall 
of the last 20 years if there had been no evapora- 
tion on the lake or outflow from it. 

" The question as to what amount of fluctua- 
tion in the lake will be necessary to take care of 
this rainfall will next be considered. The esti- 
mated rise of 148.58 inches must be provided for 
by evaporation, outflow and temporary storage in 
the lake. 

" Assuming the ratio of evaporation from the 
lake surface to be the same as in 1898, it would 
for the 104 days amount to 20.97 inches. Sub- 
tracting this from 148.58 inches leaves 127.01 
inches that must be provided for by the outflow 
and temporary storage. 

" The lake has an area of 3000 square miles; 
a rise in its surface 127.01 inches would be 
equivalent to 889,408,018,000 cubic feet. If 
this should nm out of the lake in 104 days the 
mean discharge would be 02,709 cubic feet per 
second and there would be no change in the 
elevation of the lake surface. If the lake should 
be permitted to rise one foot then the mean dis- 
charge would be reduced to 50,800 and each ad- 
ditional foot that the lake is allowed to rise 
w^ll reduce the mean rate of discharge by an 
equal amount. The following table shows the 



22 



NICARAGUA CANAL COMMISSION 



required rate of diseliarge for each foot of fluc- 
tuation : 

feet require 62,800 cubic feet of discharge. 

1 " " 56,900 " 

2 " " 51,000 " 
3- " " 45,100 '' 

4 " " 39,200 " 

5 " " 33,300 



kk 



<c 


ik 


a 


<( 


(( 


a 


a 


iC 


(( 


u 



" It appears from this table that if a waste- 
way having a capacity of 33,000 cubic feet per 
second be provided, the fluctuation in the lake 
could be limited to five feet for rainfall as great 
as any that has occurred in the last twenty years. 

" Since the canal itself will incidentally pro- 
vide waste-ways exceeding this in capacity, it 
appears that not more than five feet of rise will 
be caused by the largest rainfall. Therefore, no 
addition need be made to the six feet already 
provided for dry periods." 

The Commission has therefore concluded that 
in any plan of a canal by the Nicaragua route a 
spillway of 50,000 cubic feet per second capacity 
should be provided, and that the lake may vary 
in its level from elevation 104, the minimum, to 
110, the maximum. 

The endeavor would be to approach the dry 
season with the water level of the lake at about 
108, and during that dry season to draw it 
down to 106 if it did not go to that level from 
natural causes. At the beginning of the wet 
season the lake would be allowed to rise, but 
when it reached 108 the spillway would be op- 
ened, gradually at first, and at its full capacity if 
necessary. In this way there would be a margin 
of four feet for the lake to fall in dry seasons 
and the same amount for it to rise during wet 
seasons. This is believed to be ample. 

The possibility of securing complete control 
is manifest by inspection of Plate XlXa,' which 



1 See Plate XlXa iu Atlas. 



shows that had all the water entering the lake 
been impounded, the surface during the first 
twenty days of January, 1898, would have risen 
throe inches, or, since there was no rainfall, 
that the nm-off and seepage from the previous 
season were still feeding it. 

From this period it would then have declined 
quite uniformly from loss by evaporation until 
the end of the dry season, May 15, when it 
would have stood at an elevation of 104.07 
above datum, after which it bore a nearlv con- 
stant relation to the accumulated rainfall and 
would have reached its highest level of 113.69 
on January 20, 1899, a gain of 9.6 feet in about 
eight months had all the water been held. If, 
on the contrary, it had been desired to prevent 
any further rise at any particular stage, even the 
lowest, it might have been done by a spillway 
having a capacity of discharge indicated by the 
red line of the chart which represents an incre- 
ment at the rate of 45,940 cubic feet per second. 
With this spillway capacity for this year the 
lake could have been held at any desired stage, 
or by a reduction of the discharge, it could have 
been allowed to fluctuate within anv reasonable 
limits. 

A spillway of 50,000 cubic feet capacity di- 
vided between the eastern and western outlets 
will afford ample facilities for the regulation and 
control of the lake and its drainage. 

The relation of such a spillway capacity to the 
observed fluctuations during 1898 may be exhib- 
ited graphically by assuming this quantity of 
water to be poured into the lake basin and draw- 
ing a curve representing the rise due to this in- 
flow, all the water being stored (see Plate XIX, 
Appendix III). 

By taking the difference between the curve 
representing the lake fluctuation and the curve 
representing 45,940 second-feet at any date, as 



REPORT OF THE COMMISSION 



23 



for example on July 14, and plotting this diflfer- 
ence, the result will represent the fluctuation of 
the lake under the physical conditions as they 
existed between July 14 and the end of the 
record. Had the sluices remained closed be- 
tween January 1 and Julv 14 the lake would 
have risen to 107, and if then thrown fully 
open the lake would have risen only one inch 
higher during the entire season. Had they 
been entirely closed again on October 28, the 
lake would have gained two feet more in storage 
preparatory to the next dry season, which it 
would have entered at 108.68. By closing 
earlier more water could have been stored. This 
matter could readily be regulated by the judg- 
ment of the manager, who would doubtless have 
closed the valves throughout the dry season and 
thus have stored the entire outflow during that 
time. 

Location of Spillways. 

An important matter in connection with the 
regulation of the lake level is the location of the 
regulating works or spillway. It is seen that 
the lake may at times have to discharge as much 
as 50,000 cubic feet per second. An ideal ar- 
rangement would be to have the spillway en- 
tirely independent and separated from the canal 
proper or canalized river. A careful search has 
been made for such location on the west side 
between the lake and the Pacific, but no suitable 
place could be found that did not involve an 
expense almost as great as the- constniction of 
the western division of the canal itself. It has 
therefore been suggested that this surplus water 
might be discharged through the canal itself as 
far as Buen Retire, and there turned into the 
valley of the Rio Grande, which it would be 
forced to follow on its way to the sea. This 
plan is objectionable for several reasons. 

It will necessitate a widening of the canal 



proper from the lake to Buen Retiro, a dis- 
tance of about nine miles, the most of which 
will be excavation in rock. This part is the 
Divide cut of the western division. Even if this 
cut be made reasonably wide, the current 
through it will be swift. . Of course the greater 
the width the less the current, but it may be 
questioned whether a current of five feet a sec- 
ond in a canal 200 feet wide would be entirely 
satisfactory to navigation. Moreover, 200 feet 
width will only discharge about 35,000 cubic 
feet per second with a five-foot current, and 
there may be times when the discharge ought to 
run as high as 50,000 cubic feet per second. To 
carrv this amount of water with a five-foot 
cuiTcnt would require a width of about 300 
feet. 

A further objection would be the difficulty 
of properly controlling these discharged waters 
after they had left the canal. The discharge 
of 35,000 to 50,000 cubic feet of water per 
second into the vallev of tlie Rio Grande, means 
the creation of a torrential river ten times the 
magnitude of the existing river in its highest 
floods. This might not be an insuperable ob- 
jection if the valley of the river were rock or 
some material not easily eroded. The soil of 
this valley is for the most part light, sandy and 
easily put in motion by swift-running water. 
The distance from Buen Retiro to the Pacific 
is about eight miles, and the river in that dis- 
tance would have a fall of about 80 feet from 
the foot of the spillway. Moreover, the canal 
itself will be located in this valley, and at the 
gorge the width is reduced to 2000 feet. A 
stream like the one thus created might endanger 
the canal itself. The difliculties of controlling 
it would 1)0 groat, and a large amoimt of the 
matorial would bo sc»oured and carried to the 
ocean, perhaps to the groat detriment of the 



24 



NICARAGUA CANAL COMMISSION 



entrance to the canal. It is possible that from 
10,000 to 15,000 cubic feet of water per second 
might be discharged througli the canal on the 
west side and into the Rio Grande river if wid- 
ened and straightened without damage, but the 
discharge of two or three times that amoimt is 
believed to be impracticable except at imwar- 
ranted expense. 

Xor does there appear to be any absolute ne- 
cessity for discharging all the surplus water of 
the lake on the west side. The San Juan river 
is to-day, and has been, its natural and only 
avenue of discharge. According to the esti- 
mates of the geologist and the hydrographer, 
its discharge in high stages has at times been as 
much as 50,000 cubic feet per second. The 
evidence appears to be conclusive that even this 
great discharge does not erode its banks to such 
a degree as to carry much sediment. The Agua 
Muerta below the Machuca rapids indicates 
that no great amoimt of sediment is carried in 
the upper San Juan, and this notwithstanding 
the fact that the currents have been greater than 
thev would be under the new condition of affairs 
created bv the canalization of the river. The 
fact that the small tributaries that drain into the 
San Juan may at times discharge as much as 
50,000 cubic feet per second between the lake 
and the San Carlos river, is objectionable, but 
such discharges come at rare intervals and last 
but a short time. Even if the regulating works 
could not take care of it, the onlv effect w^ould 
be to raise the water in the river and stop the 
discharge from the lake for a short period, or 
possibly turn the current towards the lake. If, 
then, the San Juan river, discharging sometimes 
as much as 50,000 cubic feet per second, in ad- 
dition to that of its own drainage basin, as it 
exists to-dav, with a fall from the lake to the 
foot of Machuca rapids of 48 feet, does not 



seriously erode its banks, it does not seem rea- 
sonable to expect more erosion when that fall is 
reduced and the discharge area of the river in- 
creased. 

The Commission has, therefore, concluded 
that the discharge from the lake through the 
canal and down the Rio Grande river on the west 
side, should not exceed about 15,000 cubic feet 
per second, and that the remainder should be 
discharged through the San Juan river. The 
principal regulating works are therefore de- 
signed to be located at the site of the dam near 
Boca San Carlos, capable of a maximum dis- 
charge of S5,000 cubic feet per second, while 
the works on the west side should have a ca- 
pacity of 20,000 cubic feet. 

Projects and Routes. 

The region within which a canal can be con- 
structed is comprised within comparatively nar- 
row^ limits. By the term '* Nicaragua Route ''" 
is imderstood a canal route which uses Lake 
Nicaragua as a part of its system. For conveni- 
ence this mav be divided into three divisions: 

First, the division between the Pacific and 
the lake, called the western division ; 

Second, the lake itself; 

Third, the division between the lake and the 
Caribbean sea, called the eastern division. 

Western Division. 

Col. Childs, an eminent civil engineer, in 
1850-51, surveyed and located a route for a canal 
over this western division. His route, starting 
from the Pacific ocean and going eastward, from 
Brito, at the mouth of the Rio Grande, fol- 
lowed the valley of this river to a point about 
eleven miles from the lake, thence across the Di- 
vide to the valley of the Lajas, which it followed 
to the lake. There was no harbor at Brito^ 



REPORT OF THE COMMISSION 



25 



and he proposed to form one by the construction 
of jetties and by excavating the alluvium of 
which the coastal plain is composed. A detailed 
description of the project is given in the report 
of the Board of 1895. 

In 1873 a survey was made by Commander 
Lull of the TJ. S. Xavy. He proposed to con- 
struct a harbor at Brito and to follow the route 
suggested by Col. Childs up the valley of the 
Rio Grande, but to cross the Divide farther to 
the north and to follow the valley of the Medio 
to the lake. This line was somewhat shorter 
than the other, but involved heavier cutting in 
the Divide. A full description of this route is 
given in Commander Lull's report. 

Mr. Menocal, the Chief Engineer of the Mari- 
time Canal Company, after furtlier surveys, 
proposed to abandon the Medio route on account 
of the heavy cutting in the Divide and adopted 
practically the route suggested by Col. Childs. 
His first project was for a canal in excavation 
along the north side of the valley of the Rio 
Grande. Subsequently he suggested a modi- 
fication of this project, which was adopted by 
the Maritime Canal Company, of building a dam 
at La Flor and creating an artificial basin 6.25 
square miles in area, reaching from near the 
westerlv side of the Divide to w^ithin four miles 
of the Pacific ocean. At the projKJsed site of 
the dam the vallev of the Rio Grande narrows 
to about 2000 feet, and the surface indications 
of the adjacent hills seemed to promise good 
foundations for a dam. The construction of 
this dam would practically extend the lake level 
westward to within four miles of the Pacific 
ocean. From the basin thus created the Pa- 
cific ocean was reached bv a canal with three 
locks. 

The Board of 1S95 suggested still another 
project for a canal across this western division 



which did not differ in location materially from 
that at first proposed by Col. Childs, but fol- 
lowed the left bank of the Rio Grande instead 
of the right. These several routes are shown 
on the map accompanying this report and a fur- 
ther description of them seems imnecessary, as 
full descriptions are to be found in the various 
reports and Congressional documents published 
bv the U. S. Government from time to time. 

The relative advantages and disadvantages of 
these several routes will now be considered, but 
solely on a physical basis without reference to 
relative cost. 

The ^fenocal project of creating a basin in the 
vallev of the Rio Grande by the construction of 
a dam at La Flor has the advantage of bringing 
the lake level close to the Pacific ocean. The 
deep part of such a basin could be more rapidly 
and conveniently navigated than a qanal in ex- 
cavation. Moreover, the flood discharges of the 
Tola and Rio Grande could be admitted into 
the basin without materially affecting the sur- 
face level, and it avoided all necessity for divert- 
ing the waters of these streams from the canal 
eastward of the dam. 

The disadvantages of this plan are, first, the 
La Flor dam itself. Its crest would have to be 
about 120 feet above sea level, allowing 10 feet 
for freeboard, while the solid rock is found at 
about 45 feet below sea level. The total height 
of the dam in the deepest part would, therefore, 
be not less than 105 feet. 

Second. If a high dam be built at La Flor 
to hold the leve\ of the basin at 110 feet above 
sea level, all the locks will have to be placed on 
the west side of the Rio Grande. This is a dis- 
advantage because the area suitable is limited. 

The l(K'ks will necessarily be of high lift and 
located on the slope of the hills close to each 
other, where there is little room for additional 



26 



NICARAGUA CANAL COMMISSION 



locks sRould they become necessary by future 
developments in the commerce through the 
canal. Moreover, a part of the canal itself will 
necessarily be built with heavy embankments or 
retaining walls on the slope of these hills, and 
the lower Rio Grande will either have to be 
crossed, taken into the canal, or discharged to 
the eastward of the proposed harbor. 

Third. The creation of this basin would sub- 
merge many acres of land, not at present of 
great value, but which would become valuable 
should a canal be built. 

A canal in excavation, whether it follows the 
right or left bank of the Rio Grande, avoids the 
construction of the La Flor dam, presents no 
special engineering difficulties, enables good sites 
for locks to be selected, and preserves for culti- 
vation the fertile land bordering immediately on 
its banks. Of the two routes in excavation the 
one on the east side allows the river to discharge 
through its natural mouth on the west side of 
the proposed harbor. It is somewhat shorter 
than the other, but the most important advan- 
tage is that it enables the harbor at Brito to be 
constructed on the east side of the Rio Grande, 
which is considered advisable since it is con- 
templated to discharge a part of the water of 
the lake on the west side for regulation of lake 
level. 

The Menocal project could, however, be 
varied by providing a lock and dam at or near 
Buen Retiro, and dropping down to a lower 
level. The basin would in this case be diminished 
in size, and the dam would be lowered in height 
by the number of feet lift in the lock. Less land 
would be submerged, but the basin would not 
be as deep nor as long. On the other hand, 
fewer difficulties would be encountered in con- 
structing the locks from the La Flor dam to the 
Pacific, and the canal could be carried down to 



the sea on either side of the river with less diffi- 
cultv. 

The Commission is of the opinion, in view of 
all the circumstances, that the best location is on 
the left bank or east side of the Rio Grande. 

Lake Division. 

The lake division will be the same for any 
project. 

Eastern Division. 

The projects that have been proposed and con- 
sidered for the eastern division admit of more 
variants than those on the western division, but 
all projects for the eastern division look to canal- 
izing the San Juan river by means of locks and 
dams, from the lake to the vicinity of the mouth 
of the San Carlos river. 

Three projects with their variants are all that 
need be considered on the eastern side. 

The first is that for canalizing the San Juan 
river from its source at the lake to the sea. So 
far as the canalization of the river from the lake 
to Boca San Carlos is concerned, no doubt exists 
as to its practicability. But for that portion of 
the river from thence to its mouth, it is not 
deemed practicable, because of the difficulties of 
securing good foundations for dams, the torren- 
tial discharge of the San Carlos and Sarapiqui 
rivers and the great quantities of sand carried by 
them and deposited along the river channel of 
the lower San Juan. 

A second project is that suggested by Mr. 
Menocal, which had for its object the extension 
of the lake level through the " Divide cut '' to 
within twelve miles of Grey town. It is similar 
to that suggested by him for the west side. It 
looked to the construction of a high dam at 
Ochoa, a short distance below the mouth of the 
San Carlos river, by means of which the waters 
of the San Juan were to be raised to the level 



REPORT OF THE COMMISSION 



27 



of the lake. From the south end of this dam 
embankments were to be built in the saddles 
of the San Carlos ridge, to connect with the 
tills in Costa Rica, thus cutting off the escape 
of the raised waters of the San Juan on that 
side. In this embankment line sluices were to 
be built to discharge the surplus waters of 
the lake which find their way down to the San 
Juan river, as well as the floods of the San 
Carlos itself. 

From the north end of the Ochoa dam similar 
embankments were to be built across the saddles 
in the hills on this side, until connection was 
made mth the high ridge known' as the 
"^^ Divide." This was known as the San Fran- 
cisco embankment line, and it crossed the rivers 
San Francisco, Danta and Chanchos. The num- 
ber of dams, large and small, was 67, those across 
the rivers named being the largest. This em- 
bankment line had a length of about 15i miles 
from the north end of the Ochoa dam to the Di- 
vide, of which six miles were artificial. Sluices 
were to be built at convenient places along this 
embankment to discharge the surplus waters of 
the drainage area to the northward. 

By means of the Ochoa dam and the San 
F'rancisco and San Carlos embankments a large 
pool or basin of irregular shape was to be created 
and the surface of the water maintained at or 
near the level of that in the lake itself. The 
excavation in the upper river and in the pool was 
thus reduced to a minimum. 

From a point near the eastern end of the 
Ochoa dam the canal was carried in excavation to 
the valley of the Danta, or Florida lagoon, and 
from thence in pools and cuts to the valley of the 
Limpio which it followed to the Divide cut. 
This cut is about three miles long and has an 
average depth of 134.4 feet, the maximum depth 
being about 350 feet. After crossing the 



Divide the canal descends, by means of three 
locks of high lift, into the valley of the Deseado 
which it follows to the coastal plain, after reach- 
ing which it continues in a nearly direct line to 
Greytown. 

A third project is to construct a dam in the 
San Juan river just above the mouth of the San 
Carlos, giving slack water navigation from the 
lake to the dam, and thence by a canal in excava- 
tion along the left bank of the San Juan or near 
it, to the junction of the San Juan with the San 
Juanillo, and from thence across the coastal 
plain to Greytown. 

Each of the two latter projects admits of vari- 
ants. The Menocal project can be varied by 
locating the dam across the San Juan above the 
mouth of the San Carlos river, starting with ex- 
cavation to the eastward of that dam and thence 
following a route substantially as projected by 
Mr. Menocal himself. Or, a lock may be used 
in connection with this dam and the height of 
the embankments be correspondingly reduced. 
This would increase the depth of the Divide cut 
by the same amount. The practicability of a 
dam only a short distance above the mouth of 
the San Carlos river has heretofore been doubt- 
ed, but the surveys show that such a dam is not 
only practicable but will be easier of construction 
than one at Ochoa. 

Another variant would be to build a dam near 
the lower Machuca rapids and lock down 24 to 
30 feet, then follow the rest of the route practi- 
cally as laid down l)y Mr. Menocal, the object of 
the latter variant being to avoid the constniction 
of a high dam at Ochoa and to reduce the height 
of the San Francisco and San Carlos embank- 
ment lines. This would increase the depth of 
the Divide cut. 

Another variant would be to construct a dam 
at Tambor Grande and an embankment on the 



28 



NICARAGUA CANAL COMMISSION 



south side connecting with the hills in Costa 
Rica. This would take the place of the Ochoa 
dam and eliminate the San Francisco and San 
Carlos embankments. This is regarded as im- 
practicable. 

Other variants, such as increasing the number 
of locks or varying their location, suggest them- 
selves. 

The third project can be varied by construct- 
ing one or more dams with locks in the upper 
river, thus reducing the height of the dam at 
San Carlos. Or, after reaching the junction of 
the San Juan with the San Juanillo any one of 
several routes may be taken to the sea. 

ifr. MenocaPs project has an advantage in 
that it is two miles shorter than the other project 
following the bank of the river.' 

Its disadvantages are, first, the engineering 
difficulties encountered in building the Ochoa 
dam. This dam being located but a short dis- 
tance below the mouth of the San Carlos river, 
its construction would be attended with no little 
risk. 

Second, the San Francisco embankment line 
is another troublesome engineering construction. 
This embankment follows an irregular line from 
Ochoa to the Divide. Xo less than 67 dams will 
be required, some of them insignificant in size, 
but four of them of great length and of more 
than ordinary difficulty to build and maintain, 
because of their great height and the pressure 
of water to which they would be subjected, as 
well as to the fact that the soil on which they 
would have to be founded is overlain for a great 
depth with soft ooze. 

A third disadvantage is the Divide cut itself. 
This, as before stated, is over three miles long. 
In addition, it is curved, the curvature being in 



1 Comparison of distances between the lake and Grey town 
harbor. 



places the maximum that should be allowed in a 
canal of this magnitude. This would render 
navigation difficult. Its great depth would also 
be a constant menace, for while it is believed 
that the rock for the most part would stand, 
there is some likely to cause trouble. A large 
portion of it, dacite, a rock that weathers rapidly, 
is of light specific gravity, and not to be trusted 
in a deep cut like that through the Divide. 
Again, on account of its depth and length it 
would necessarilv be made of the minimum 
width practicable for navigation; consequently 
if the canal were working to its full capacity 
there would inevitably be some delay to vessels 
passing through it, since two large ships could 
not paas each other.. Vessels would therefore 
accumulate at either end to be passed at stated 
intervals in fleets. 

The variant providing for the constniction 
of a lock and dam at Machuca, locking down 
say 24 feet, would reduce the height of the San 
Francisco embankments and the Ochoa dam; 
but the excavation in the San Juan river and 
eastward to the eastern end of the Divide cut 
would be increased by this extra depth. There 
would still be the Ochoa dam, though of less 
height, to be constructed in contention with the 
floods of the combined San Juan and San 
Carlos rivers. If the dam be built above the 
mouth of the San Carlos river instead of below 
it at Ochoa, there would yet remain the objec- 
tionable San Francisco embankments and the 
Divide cut. 

The project which looks to the construction of 
a dam above the mouth of the San Carlos river, 
and follows close to the north bank of the San 
Juan river as far as the junction of the San Juan 
and San Juanillo, has the disadvantage of an 
increase in length of about two milet?,' but on 
the other hand it is believed the difficulties of 



REPORT OP THE COMMISSION 



29 



construction will be lessened because of the re- 
duction in the height of the embankments and 
by avoiding the Divide cut. 

There are, nevertheless, several hills of con- 
siderable height to be cut through on this route. 
The Tamborcito hill will require a maximum 
depth of 230 feet of cutting in rock, but it is less 
than a half mile in length, and the material will 
be required on the work, while an attempt to cir- 
cumvent the hills mav involve an embankment 
founded upon a depth of 80 feet or more of 
black sand in the bed of the river. From this 
point to Lock Xo. 1 most of the canal tnmk 
will be enclosed between embankments built 
of the silt from the excavations. In short dis- 
tances they may exceed 30 feet in height, with 
a pressure of twenty feet of water. 

A variant on this project will be in the con- 
struction of two dams in the river al)ove the one 
near the mouth of the San Carlos. But it has 
no advantage over the other except that it 
enables the Iriwer dam to be reduced in height. 
This is not considered of great importance, for 
while the construction would be easier, the main 
difficulty would be in the foimdations and they 
would not be materiallv different. It has several 
serious disadvantages, however, in obstructing 
the passage of large volumes of water at narrow 
sections of the river and in confining the navi- 
gation below the upper dam to a narrow channel 
excavated in large part through rock. 

Numerous other adjustments in detail ninv be 
made, both in the alignment and grade, but they 
an* not of sufficient importance to warrant con- 
sideration prior to final location. 

Gkevtowx Hakiku:. 

A suitable harbor with a safe entrance, at the 
oast(»rn end of the canal, is an essential rinpiisite 
to its proper operation. Xo such harbor now 



exists. About fifty years ago there was a good 
harbor at Grey town with thirty feet of water in 
the anchorage and at the entrance. The sand, 
however, that has been brought down by the 
San Juan river and deposited in the sea has 
closed the entrance, and in a large measure filled 
up the harbor itself. This sand movement has 
been .going on for ages, as the numerous lagoons 
that have been formed parallel to the coast 
line testify. The sand has been ejected from 
volcanoes in the region of the headwaters of the 
Costa Rican tributaries of the San Juan, car- 
ried down to the sea by the river, deposited on 
the ocean bed, and then transported by wave ac- 
tion in one direction or the other according to 
the prevailing winds and the resulting direction 
of the waves. 

By the term ** harbor '' it is not intended to 
convey the idea that a large harbor should be 
constructed for commercial purposes. A harbor 
of sufficient area to accommodate the vessels 
that arrive for the purpose of passing through 
the canal is all that is considered necessarv. It 
is not expected that vessels will lie in such a 
harbor for any length of time, but will move 
through, either in one direction or the other. 

For canal construction purposes a harbor is 
necessary. One of the first things, therefore, to 
be done in undertaking the construction of the 
canal will be to form a harbor of reasonable 
depth. This has an important bearing in esti- 
mating the cost of construction. 

The San Juan river drains a basin of about 
17,000 square miles. The silt d(»posited in its 
delta during past ages has built out the coast, 
with characteristic lagoons and extensive marshes 
covering the broad plain between the ])r(*sent 
shore linc^ and the original foot-hills of the (.V»r- 
dilleras. 

The delta may be said to begin at a point 



30 



NICARAGUA CANAL COMMISSION 



twelve miles in an air-line from the outer coast, 
where the San Juanillo leaves the main trunk. 
This stream has been turned parallel to the coast, 
and finally reunites, through a series of lagoons, 
with the lower San Juan. The latter is flanked 
by lagoons indicative of original beaches, the 
three to the north being typical of the prevailing 
direction of the drift on this portion of the coast, 
due to the angle of wave incidence. These la- 
goons are nearly parallel to the existing coast 
line and are separated by strips of land enclosing 
long, narrow lakes. The date of these forma- 
tions is not ascertainable from any existing 
records. 

It woidd seem that what is now the lower 
San Juan river was at one time the main stream 
and discharged most of the sediment, the waves 
produced by the trade winds carrying a part of 
the material to the westward and a part of it to 
the southward, the westerly movement of this 
sand having formed lagoons whose longer axes 
are nearly parallel to the coast. The prevailing 
winds are from the northeastward and while they 
rarely blow with great violence, they blow 
steadily and with considerable force, creating a 
sea which stirs up the light sand of which the 
beach is composed and carries it along in great 
volume. One has only to observe the waves 
charged with black sand, running diagonally 
along the beach, to realize their potent agency 
in transporting this material. 

The Board of 1895 gives a very complete de- 
scription of the sand movement on this coast, a 
full discussion showing how the destruction of 
Grey town harbor as it formerly existed was 
brought about, and the steps necessary to be 
taken in the construction of a new harbor. The 
conclusions arrived at by that Board were that 
. the Maritime Canal Company's proposed en- 
trance is inadmissible, and the Harbor Head en- 



trance inexpedient, and that the best results will 
be obtained by locating the entrance approxi- 
mately half-way between the two. This Com- 
mission is of opinion that equally good results^ 
at less cost, can be obtained by a change in the 
entrance and form of the harbor itself. The 
Commission has, therefore, located the east jetty 
about 2000 feet westward of the position sug- 
gested by the Board of 1895, the harbor itself 
to be about 5000 feet long by 1000 feet wide„ 
and the entrance between the jetties to be 60O 
feet. 

The construction of a jetty across the path of 
moving sand must of necessity cause accumula- 
tions of drift to windward, hence the angle 
formed between any such projecting structure 
and the shore must gradually fill up and the 
shore line advance seaward until the capacity of 
this receptacle is exhausted. This advance di- 
minishes as the depth and consequent capacity 
of the pocket increase, but it shows that some 
expense must be incurred for the maintenance 
of the harbor either by jetty extension or by 
the removal of the material from time to time,, 
which would otherwise find its wav around the 
end of the jetty and into the channel. A study 
has therefore been made of the various surveys 
of the harbor with a view to determining the 
probable amount of material to be controlled in 
the maintenance of the entrance. This amount 
is estimated to vary from 500,000 to 730,000 
cubic yards annually. 

The entrance to the harbor will be formed 
by two parallel jetties about 600 feet apart, the 
easterly one about 20 70 feet in length, the 
westerly one 2500 feet. They will extend sea- 
ward in a northerly direction, thus giving shelter 
from the sea, which comes generally from the 
northeastward. As the sea strikes the shore 
line with considerable violence at times, these 



REPORT OF THE COMMISSION 



31 



jetties will be constnieted chiefly of heavy stones 
not easily moved by the force of the waves. To 
obtain suitable stone for this purpose in large 
quantities and with the utmost dispatch, so that 
a part at least of the jetty can be quickly con- 
structed, quarries will have to be opened at the 
most favorable locations. 

Brito Haebor. 

At the westerly terminus of the canal there is 
no harbor. The nearest harbor is that at San 
Juan del Sur, about eight miles to the south- 
eastward, but this cannot be put to any useful 
purpose so far as the canal itself is concerned, 
though it may be utilized in a measure during 
the early stages of canal construction. A har- 
bor will have to be constnieted at Brito as at 
GreytowTi. San Juan del Sur could only be 
used to advantage during construction by the 
building of a railroad from there to the canal. 

The remarks as to the capacity of a harbor at 
Greytown will apply with equal force to Brito. 
In other words, a harbor of refuge is not needed, 
but only such a harbor as will make the canal 
available for commerce. Vessels will seldom go 
to Brito imless entering or leaving the canal. 

The conditions on this coast are not as forbid- 
ding as they are on the eastern. The sand move- 
ment is slight and the winds are mostly off shore, 
consequently the difficulties to be encountered 
will be more easily overcome. The mean rise 
and fall of tide is about 7 feet The sea during 
the greater part of the year breaks normal to the 
direction of the shore; the prevailing wind is 
from the northeast, and while west and south 
winds sometimes blow tliev are of rare occur- 
rence. 

The shore is bold, and deep soundings are 
found at no great distance from it. The shore 
line trends from northwest to southeast, but the 



rocky promontory on the north side of the Kio 
Grande projects into the sea and gives a certain 
amount of protection. 

On account of the rapid increase in depth 
from shore seaward, an outer harbor is almost 
impracticable within the limits of reasonable 
cost, so that one is restricted to the formation of 
an inland harbor within the area that is now oc- 
cupied by a swamp. From borings made and 
all information obtainable it is believed that this 
material is easv to excavate. In fact it is known 
that some of the borings taken by the Canal 
Company in close proximity to the proposed har- 
bor, which seemed to indicate rock at no great 
depth, were deceptive and that the boring appa- 
ratus struck boulders which were supposed to be 
solid rock. 

The harbor proposed by Col. Childs opened 
directly to the south, and was protected by two 
jetties, one springing from the sandy beach and 
nmning southward, the other, but smaller jetty, 
springing from the Brito promontory and run- 
ning southeastward. The entrance was 400 feet 
wide. An inner harbor was formed by a chtage 
in direction of the entrance at nearly a right 
angle, which gave good protection. The size 
and depth of the harbor proposed would be ut- 
terly inadequate to the present size and draft of 
ships. A diversion of the Rio Grande to the 
eastward of the entrance was a necessary feature 
of this scheme. 

Capt. Lull, in his project for a harbor, made 
some changes in the Childs project, with a view 
to giving a wider entrance and more capacious 
and deei)er harbor, suited to the increased depth 
which he proposed. 

The Maritime Canal Company also proposed 
a plan for a harbor, increasing the area to 103 
acres. 

The Board of 1895 suggested still another 



32 



NICARAGl'A CANAL COMMIS.-I()N 



project, the main feature <»f wliicli was the ex- 
tension of the west jetty of the Lull phm to u 
length of 3C00 feet. This was, liowevrr, niily 
provisional, with a view to an appn)xiniati' esti- 
mate and not as a definite projeet n(M*essarily to 
be followed. That Boanl di-tinrtly stated that 
"the information avaihal>le is not suHiricnt to 
enalde final plans and estimates to h(» ni:i«lf." 

All the plans proposeil liave crrtain inlim-nt 
defects, and it is scaively possilih* to cnu^ti'iirt a 
harbor at this ])hu*e that will he ]MM'fect. A 
bn^akwater to shelter an i*ntranr(» becomes a 
verv exjKMisive stnictnre in such a pla^e as Hrito 
and is liable to introduce other objectioual>lc 
features. 

It is believed, however, that the ditfirulties of 
a vessel's enterin^r between two jetties that pnv 
ject seaward in the direction of the advancin<r 
waves have been overestimated in tin- case un- 
der consideration. San Juan del Sur is a fairlv 

« 

good harbor, yet its entrance is ojx-n to the sea. 
It is said that no trouble is experieneej] by ship- 
ping at this place from >\U'\\ exposure. A Va- 
eitie Mail steamer calls at this harbor miee a 
week throughout the year. She does not g<> to 
a dock, for thei-e is nrnie at which she could lie, 
but it is understooil no trouble i.- experienced in 
lightering from her anchorage. 

To pennit a vessel to ent»'r the harbor normal 
to the swell, and at the sauH' time tti guard it 
against agitation from the adnli^^si^ul of largi- 
waves, are conditions not easily ^atistied, but tin* 
Commission believes that the form of Imrbnr 
presented with this reiMjrt will mei'i tiie con«li- 
tions as nearly as it is ju-acticable to do within 
the limits of reasonable cost and in a maiiMer le-s 
objectionable than any other yet proj>oM'.|. 

The plan is to build a jetty from a j joint on 
the beach about oGOO feet east of the iJritn 
promontoiy, extending out into the -ea in a tli- 



rection nearlv >4)uth-sout Invent to the seven- 
fatliom <»urve: tln*n excavate u harbor of tbe 
t'nrm shtrwn on the plan, to the eastward oft 
north an<l -uMith line through the root of the 
iettv, the entnince to lie iJOO feet wide at the 
thritat. This will give .sei-iirity an<l compara- 
tively .-still water in all winds exoept those com- 
ing fn>ni -onth by west and a few deprcres either 
>ide. Tin* proniontory will prote«*t from winds 
comiiiir fr«»m a nion' wi'stiTlv dirot'tion and the 
jetty from all wind*^ coming' froui a direction east 
of sonth. The ba.-in to lie exc'avat4*<l ha$ a bot- 
tom area of iilMiut l*»a acres and a depth of 30 
feet at nu-an li»w tide with a de|>th of 36 at the 
I ntrance. As the movement <»f san<l Ls slight 
the co^t of maintenanc(» will not 1h* ^cat. 

The Kio drand*' in this project will not be 
<liverti'd at its lnwer end, btit it will have to he 
enlarged in cross section in order to carrv in- 
i-reased discharge. 

If the c« nclusions reaehe<l l>y this Commi:^ 
>ion that thir- harbor gives all the protection that 
i< ne<«h'd, be found by time and ex[)erience to W 
inci»rre«'t, a jettv from the proinontorv eastwanl 
«-an beailded at any future tini€». It is iKdieve^l, 
however, that such jetty will never he requinJ, 
and no provision has bei'n made in the estimate 
for one. 

1)a.MS AM> KMaANKMKS'TS. 

T«» (Min^truct <afe, ilurable and stahle stnic- 
tnre^ fnr the control of the drainage and for 
navii!atiMn i- a sinr ifitu lum. 

T\u' jirincijKi! .-auses for the failures of dani-^ 
cir rc-» rvoirs mny be traced to defective founda- 
tions imjiropiT di >ign or imi>erfeet construction, 
-ingle or ciinibined. Probahly the most frt- 
»iue!it «mum- of their failtirc; are, their permea- 
biliiy cjni>ing a breach by seepage, and their 
lack I'f -jjillway capacity allowing the dams to 

in- nV( ll«i|ip<'il hv tlutnls. 



REPORT OF THE COMMISSION 



33 



The sites projX)sed in Xicaragna for the dams 
are such that, in connection with the large im- 
pounding capacity of the lake acting as a reser- 
voir, there is little or no danger of sudden floods 
reaching their crests, so that the risk from this 
source is believed to be eliminated by providing 
an ample waste-way and freeboard. This re- 
mark applies with still greater force to the em- 
bankment lines, which may be used for the pur- 
pose of enclosing large artificial lakes in basins 
of limited drainage area and not subject to the 
discharge from the river. 

Moreover, there is an almndance of material 
suitable for puddle, which if properly applied 
will secure impenneability. The main diffi- 
culty, therefore, is that resulting from insecure 
foimdations. For the dams in the rivers clos- 
ing the summit level, satisfactory rock bottoms 
and abutments are available, but to reach rock 
on the San Francisco embankment line is a morc 
difficult and expensive problem. 

Dams ox the Eastern Division. 

In view of the large amount of earth and rock 
excavation and the necessity for disposing of the 
spoils, it was decided by the Maritime Canal 
Company to construct high rock-fill dams on 
both sides of the lake for the purpose of im- 
pounding the waters of the summit level, but 
the desirability of avoiding the San Carlos river 
and of facilitating the construction of the dam 
itself, has led this Commission to select a new 
and better site a short distance above the mouth 
of the San Carlos river. 

The borings made on the site of the proposed 
Ochoa dam revealed rock at 17 feet below sea 
level, suitable for foundations. The width be- 
tween banks is n^latively nan*ow, for at an eleva- 
tion of 100 feet above sea level it is about 1400 
feet. As this site is below the junction ^f the 

3 



San Carlos river, which at flood stages, it is esti- 
mated, may discharge 100,000 cubic feet per 
second in addition to the lake and San Juan 
river drainage, this large volume must either be 
disposed of over spillways on the San Carlos 
ridge or be allowed to waste over the dam itself. 
It-s sediment also would l)e deposited in the bed 
of the stream above the dam and cause constant 
shoaling. At lower Ochoa the sand extends to 
30 feet below sea level. To avoid these serious 
objections as well as to eliminate, if possible, 
the embankments of the San Francisco and 
Florida lagoons, examinations were made for a 
dam site at Tambor Grande island. The subse- 
quent borings in the bed of the river at this site, 
however, showed an erosion of the bed rock ex- 
tending to 128 feet below sea level, which would 
necessitate a dam in this narrow gorge of the 
river nearly 250 feet in height, subject to the 
flow of the entire drainage basin. This project 
was, therefore, discarded. 

The more recent examinations and surveys, 
made on the wider reach of the river above the 
San Carlos, gave results which were quite satis- 
factor5\ Here the flowage line is almost con- 
tinuous, requiring but one small embankment, 
while the section affords ample weir length. 
Good solid rock foundations exist at about 15 
feet below sea level. Thus the maximum height 
of the dam from the bottom of the foundation 
would be 138 feet. The construction of a dam 
at this point avoids the serious objections to the 
Ochoa site, and also reduces the cost and diffi- 
culties of construction. 

The estimates are based upon concrete, which 
can be mixed on the site. Kegulating works 
and sluices can be provided in the original 
river channel, and the entire length of the crest 
may be utilizcnl for a spillway in case of ne- 
cessitv. 



34 



NICARAGUA CANAL COMMISSION 



The typical section on which the estimates are 
based is the ogee rising from the natural bed of 
the stream at an elevation of about 38 feet above 
sea level to the proposed weir sill at 98, with 
regulating sluices to control the higher stages. 
The width of the base at the deepest point is 100 
feet. The ordinary stage of water at the foot 
of the dam is about 55 above sea level, while ex- 
treme low water is about 45. 

Sites for Low Dams. 

There are various locations on the river where 
dams may safely be placed for variations of pro- 
ject. Taking these in order, coming down 
stream, the first mav be at Castillo where the 
river flows over ledges of basalt which is some- 
what jointed, giving it the appearance of being 
stratified, but it is believed to be firm and strong. 
The anchorages also are good. 

At Upper Machuca, three miles above Ma- 
chuca, the rock is calcareous sandstone with 
limited weathering. Solid rock is usually found 
under a few feet of sand in the river channel, 
but the rock in the adjacent hills is weathered 
down nearlv to the same level as the surface of 
the solid rock in the channel so that the anchor- 
age must be in residual clay and soft rock. 

Tlie Macliuca site is situated across the head 
of Campafia island. It is based on a fine-grain- 
ed light-bluish gray rock, evenly bedded, and 
closely resembling a fine-grained quartzite. The 
borings on the south banks, however, show 
great depths of weathering, making it desir- 
able to shift the location farther up or down 
stream. 

Conchuda about two miles above the Boca 
San Carlos also affords a possible dam site and 
has been considered with a view to reduce the 
large amoimt of rock excavation incidental to the 
Machuca dam projects. 



Relative Cost of the Several Oonoeete Dam 

Projects Between the Lake and Boca 

San Carlos, Including the Latter. 

These estimates are based upon the same 

prices in each case and are submitted merely as 
a guide to the relative merits of the plans: 

Low^ dam at Upjier Machuca $1,045,569 

Low dam at Lower Machuca 866,040 

Low dam at Boca San Carlos 2,633,124 

$4,544,733 

Low dam at Lower Machuca $1,240,785 

Low dam at Conchuda 2,721,411 

Low dam at Boca San Carlos 2,633,124 

$6,595,320 

Both of the above schemes would require in 
addition a large amount of rock excavation in 
the river to create navigable channels in the 
pools, which would be avoided by the higher 
single dam. 

High dam at Boca San Carlos, of concrete, 
$4,570,340. 

San Carlos and San Francisco Embankment 

Lines. 

The hills to the southeast of the San Carlos 
river contain depressions which would have to 
be closed by earthen embankments to provide 
for the Menocal project, with weirs through the 
saddles. The depth to hard rock varies from 
probably 60 to 100 feet, but as the San Carlos 
embankments will be avoided by the change of 
the dam site to a point al>ove the Boca San Car- 
los, no further discussion of its embankment line 
is required. It would be necessary, however, to 
extend the San Francisco embankment line from 
Ochoa up the left bank of the river to comiect 
with this new location, involving heavy w-ork. 



REPORT OP THE • COMMISSION 



35 



Embankment Foundations. 

To ascertain the character of the material un- 
deriying the proposed embankments crossing the 
Florida, San Francisco, Nicholson and Chan- 
chos depressions, deep borings were made in each 
which revealed the residual clav and soft rock 
beneath the alluvium but in thinner strata than 
on the hills. 

" The rock is only moderately hard, consisting 
chiefly of talcose volcanic tuff wth a thin bed 
of earthy limestone.'' The silt in these depres- 
sions and swamps apparently extends to about 
ten feet below sea level and renders it desirable 
to reduce the height of the embankments as 
much as possible. All the routes traverse the 
reach on the left bank of the San Juan from 
Boca San Carlos to the San Francisco near its 
mouth and hence cross these lateral tributaries, 
but at different elevations dependent upon the 
number and location of the locks. 

Dams on the Western Division. 
The LuV Flor Site. 

Much has been said pro and con concerning 
the possibility of constructing a dam at this site, 
and the Board of 1895, basing its conclusions 
upon certain exhibits as to geological structure, 
declared it inexpedient, in view of the slight ad- 
vantages and the ability to construct a canalized 
channel at a somewhat greater cost on the left 
bank of tlie Rio Grande. 

In the light of more recent borings and their 
interpretation by Dr. Hayes, this Commission is 
of opinion that a dam at this point is practicable. 

BcEN Retiro. 

The summit level would terminate at Buen 
Retire, about miles from the lake, where the 
topography is well adapted for the puiiK>se, as it 
affords opportunities for spillways directly into 



the bed of the Rio Grande and Guachipilin, and 
for a good lock site. Here a small ovoidal hill 
rises from the bottom of the valley " composed 
of a calcareous shale more or less disintegrated, 
but sufBciently firm for foundation purposes." 
The rock is about 50 feet above sea level, and 
comparatively little silt would have to be exca-^ 
vated to place the foundations. The regulating 
works with the lock will close the summit level, 
making it unnecessary to build a dam at this site. 
Xo other dams are required on the west side 
under any of the variants. 

Canal Locks. 

On the route selected as a basis for the esti- 
mate it is proposed to construct 6 locks of 18.41 
feet lift each on the eastern division, giving a 
total of 110.46 feet, and four locks of 29 feet 
lift each on the western division, giving a total of 
116 feet, the difference of 5.54 feet being due 
to the difference in rise of tides in the two oceans. 

In estimating the cost of the locks the large 
Poe lock at the Sault Ste. Marie canal at the 
outlet of Lake Superior was taken as a standard, 
and the dimensions of lock chamber, fore- and 
tail-bays, gates, culverts, etc., were modified to 
adapt them to the present requirements. The 
lock pits were extended to 15 feet below the 
floor to provide for the culverts and valves and 
the necessary foundations. The following are 
the dimensions used for one of the 18.41 feet 
lift locks: 

Number of culverts 4 

Length of floor and side walls 939.5 ft. 

Width of floor in the clear 80. " 

Height of side walls = lift + draft 

+ 4 ft 52.41 " 

Length of sides between abutments. .601.75 " 

Width of side walls at top 10. 

Width of side walls at bottom 21.53 *' 

Width of abutment walls at quoins . . 31.77 " 



36 



NICARAGUA CANAL COMMISSION 



On the western division the topography is 
such that the best results are obtained bv the use 
of four locks having the same dimensions as to 
length and breadth, the only modification being 
in the lift and thickness of the walls and foun- 
dations. 

Upon this basis the 6 locks on the 

eastern division will cost $0,560,400 

The 4 locks on the western division 

will cost 7,412,580 

Making the total cost $16,972,980 

QUAXTITIES. 

The general advantages and disadvantages of 
the several locations have alreadv been stated 
under the head of ^' Projects and Routes," but 
no final location nor estimate could be com- 
pleted until after the quantities of the different 
classes of material on the several routes had been 
detennined. 

As a large number of variants are |X)ssible, 
particularly on that part of the route lying be- 
tween Boca San Carlos and the sea, and as it 
was impossible to determine before the prelimi- 
nary sun^eys were completed and plotted which 
would give promise of the best results, the de- 
tailed geological examination by borings on any 
specific route had to be defeiTcd for a later date. 
The classification which has been made along 
these low level routes is therefore based upon 
outcrops, borings by the Canal Company con- 
firmed by the Commission at a few |)oints, and 
an examination of the region, which is believed 
to be ample for the puii.)ose of an estimate. 

The collection, plotting and computing of 
tliese data have required considerable time, but 
so far as quantities are coneenied they are quite 
reliable. There may be variations in the classi- 
fication where the lines of 8ei>aration between 



different materials merge into one another, but 
they will be more or less equalized, so that errors 
due to this cause will be small. 

For more convenient reference and ^ompari- 
son of the quantities under the variations of line 
and grade, they have been aiTanged in a table ' 
which gives the amount of excavation and em- 
bankment in each division and for each project 
and class of material, excepting for the harbors, 
railroad and dams. The cost of the dams, locks, 
weirs, and other structures is given in the item 
entitled " Auxiliary Cost," appended to each di- 
vision. 

By the aid of this tabular statement of quan- 
tities an estimate of the cost of constructing the 
canal trunk may readily be obtained by apply- 
ing any suitable unit price to the factors as 
stated. The amount of dredging for the two 
harbors, not included in the table, which should 
be added to the totals, is, for Grey town, 10,- 
748,900 cubic yards, and for Brito, 9,500,000 
cubic yards. The jetty and other harbor work 
is not included in the table, but is stated in the 
estimates. 

For the route recommended bv the Commis- 
sion, passing to the nortli side of Silico lake, fol- 
lowing the left bank of the San Juan and Rio 
Grande rivers, and having a bottom width of 
150 feet, ^\dth 10 locks and one dam, the quan- 
tities from ocean to ocean, exclusive of the rail- 
road, are: 

Cu. yds. 

Dredging, river and coastal plain. . 01,738,842 

Dredging, lake and harbors 37,557,750 

Earth excavation and embankment. 29,907,990 

Disintegi-ated rock • 15,248,312 

Solid rock 7,573,992 

Rock under water 754,378 

152,781,270 



» See '* Table of Quantities " in Atlas. 



REPORT OF THE COMMISSION 



37 



Unit Prices. 

The Commission has endeavoretl to reach con- 
clusions in respect to the probable cost of the 
canal that w-ill be fair and just. It has tried to 
have the figures represent the probable cost of 
the canal as nearly as can be ascertained, with- 
out being too high or too low. It must be ad- 
mitted, however, that any estimate? of probable 
cost is to some extent a matter of judgment. It 
is not possible to determine this matter with ab- 
solute certainty, as many of the elements on 
which one's judgment would be based are not 
accurately known. One's experience in like 
work, and the experience of others, are. the only 
guides. There has never yet been a work of 
.similar character executed under exactly similar 
conditions, and it should be remembered that 
work on a small scale, or which is greatly dis- 
tributed and not en masse, involves more loss of 
time and labor and is consequently more expen- 
sive. The work on the Panama canal would 
perhaps come near it in some respects, but no 
one would think of comparing the extravagant 
methods which characterized the early history of 
that enterprise with the methods that should be 
employed on this. 

The latest work of magnitude of this char- 
acter which affords to some degree a means of 
comparison is the Chicago drainage canal. The 
total excavation for this work amounted to about 
12,318,000 cubic yards of rock and 20,087,000 
cubic yards of earth, a total of 38,405,000 cubic 
yards, of which about 10 per cent, was dredging. 

The earth was of every variety from soft mud to 

« t.' 

hard indurated clay with boulders; all being 
included under the name of " glacial drift." 
The rock was the Joliet limestone, stratitied in 
nearly horizontal layers, and Is described as ideal 
for ease in excavation. The proi)ortiou of rock 
to earth is less in Nicaragua than in the Chicago 



drainage canal. The actual average price paid 
for excavating '" glacial drift " at Chicago was 
29 cents per cubic yard. The average cost of 
rock was 77 cents. If the Nicaragua canal were 
locat<?d near Chicago and its rock and earth simi- 
lar in character to those of the Chicago drainage 
canal, it is probable that the average cost for 
earth excavation would be the same in each. 
The earth in the Nicaragua canal varies in char- 
acter from stiff, indurated clav to diluted silt. 
The range is equally wide in the Chicago drain- 
age canal. It cannot be asserted that the earth 
is alike in the two places, but it is l)elieved that 
it may be substantially so. lender such circum- 
stances it might be fairly assumed that the aver- 
age cost of earth excavation, if the canal were 
located near Chicago, would be 29 cents. 

As the Chicago drainage canal affords the 
nearest precedent available and as the actual 
average prices of that work have been taken as 
a basis, it is necessary to state the classification of 
the material as specified for that work, which 
was as follows: 

^' For the purpose of letting the contracts the 
material to be excavatx^d was divided into two 
classes, rock and ' glacial drift.' The first tenn 
explains itself, but the character of the material 
termed ^ glacial drift,^ this being an entirely ar- 
bitrary classification, needs some further expla- 
nation. As defined in the specifications, ' glacial 
drift shall comprise the top soil, earth, muck, 
sand, gravel, clay, hardpan, boulders, fragmen- 
tary rock displaced from its original bed, and any 
other material that overlies bed rock.' In fact, 
all these materials are found in all degrees of 
intennixture, from soft black muck, which can 
be pumped with centrifugal pumps, to a con- 
glomerate of sand, gravel, clay, and boulders 
cemented together with almost the hardness of 
rock, and only to be excavated bv means of the 



38 



NICARAGUA CANAL COMMISSION 



strongest steam shovels, and sometimes even re- 
quiring blasting to break it up." 

In Nicaragua the rock on the western division 
is chiefly a calcareous shale, thinly stratified and 
much broken. Some pits of considerable depth 
have been excavated without blasting, and the 
rock has been used for macadamizing the roads. 
It is believed that a large part of this rock could 
be excavated with steam shovels without blast- 
ing. It is drilled slightly easier than the Chi- 
cago limestone, and is more brittle. The loca- 
tion of the spoil banks would be quite similar to 
that of the Chicago work. It is therefore prob- 
able that some of this rock could be excavated 
for a price slightly cheaper than the Chicago 
rock. Some of it, however, it is known, will 
cost more. It is probable that, taken as a whole, 
it could be done for the same price, and it is so 
assumed. 

Between Lake Nicaragua and the Caribbean 
sea, viz., the eastern division, the rock is basalt, 
dacite, sandstone and volcanic tuff. The basalt 
and dacite are both considerably harder to drill 
and blast than the Chicago limestone. In the 
larger cuts the waste material will have to be 
transported some distance to the dumping 
grounds. For these reasons it is estimated that 
the cost per yard will be increased 10 cents. 
Therefore it is assumed that if the Nicaragua 
canal were located near Chicago, the cost of ex- 
cavating its rock would be 87 cents per cubic 
yard on the eastern division and 77 cents per 
cubic yard on the western division. 

With reference to the actual cost of work at 
Chicago Mr. Isham Randolph, the present Chief 
Engineer of that work, writes as follows: 

" The prices on our work ranged from 59 cents 
to 80 cents for solid rock and from 19.9 cents 
to 56 cents per cubic yard for glacial drift. This 
glacial drift, however, covered material which 



under railroad specifications would come under 
the heads of loose rock and hardpan. The av- 
erage price paid on this work per cubic yard 
was for solid rock 77.3 cents, for glacial drift 
28.7 cents." 

" In the light of our experience I believe that 
a work of like magnitude prosecuted under simi- 
lar conditions could be put under contract at a 
reduction of about 15 per cent, from our ruling 
prices; in other words, that rock work should be 
done for 65 cents and earth for 24i to 25 cents, 
which prices would, I believe, provide a fair 
margin of profit for the contractor." 

Mr. Lyman S. Cooley, former Chief Engineer 
and Director of this work also concurs in this 
opinion, stating that some very hard glacial 
drift was removed for 26 cents per cubic yard 
and that the actual cost of rock work was about 
as follows: 

Per cu. yd. 



For plant 15 cts. 

loading 15 

hoisting 15 

channeling 5 

drilling 6 

explosives 8 



a 

a 
a 



Total 

including contractors' profits. 



64 



t( 



It yet remains to assign the relative cost of 
work in the United States and in Central Amer- 
ica. This will involve greater uncertainty, for 
the reason that there have been no large works 
in Central America with which comparison 
could be made. There has, however, been 
some railroad building in all of the Central 
American States, often in amount sufficiently 
large to require the importation of labor, thus 
making the conditions of labor similar to those 
which would obtain if the Nicaragua canal 
should be built. 



REPORT OF THE COMMISSION 



39 



Mr. Wm. H. Keith, Contractor, reports the 
cost of work on the National Railway of Costa 
Rica to be for solid rock 60 cents in gold per 
cubic yard, for loose rock 30 cents in gold per 
cubic yard, and dry earth 18 cents in gold per 
cubic yard, concrete in place, including "forms," 
$9.00 per cubic yard. 

Mr. Louis Wichmann, General Manager of 
the Atlas Company, who has been engaged in 
building a railroad, six miles and a half in 
length and 2i feet gage, from Greytown to the 
lower San Juan river, states " that the total cost 
per cubic yard of excavation on the Silico Rail- 
road is $1.25 Nicaraguan currency, equal to 50 
cents gold." 

In explanation of this abnormally high price, 
he says that " the disadvantages were extremely 
bad weather, especially in June and July, during 
which time we had some seven weeks of con- 
tinuous rain, and the principal part of the ma- 
terial being heavy clay, it was very difficult to 
handle." 

" Being entirely without mechanical applian- 
ces, I had to rely on manual labor, which, con- 
sidering the nature of the soil and constant down- 
pour of rain, has proved a great drawback." 

" The material on the first big through cut at 
the Silico end consisted of conglomerate with 
large round boulders, which could only be re- 
moved after blasting, and unfortunately, owing 
to the American-Spanish war, we were unable 
to secure explosives at the time when they were 
most needed." 

Other difficulties mentioned were the long car- 
riage to the spoil banks and the fact that all sup- 
plies, tools and provisions had to be transported 
on the backs of the laborers. 

These conditions and prices cannot therefore 
be cited as being comparable to the probable 
cost of 90 great a work as the construction of this 



canal, where the most modern appliances should 
be used. 

Quite recently it is credibly stated that the 
Silico railroad had cost more than was antici- 
pated, and that the total cost was from $110,000 
to $120,000, length 6^ miles, equivalent to $16,- 
923 to $18,461 per mile, and that this cost in- 
cluded everything — road-bed, rails, rolling stock, 
bodegas, wharves, and all terminal facilities at 
both ends. It was built in very bad weather and 
under great difficulties. The rolling stock con- 
sists of one locomotive, eight freight ears, two 
construction cars and two passenger cars, which 
were imported. The ties on this road were fur- 
nished and put in place for about 24: cents apiece 
in gold. 

'* The cost of excavation varied from 50 cents 
to $1.00 (Xicaraguan currency) per cubic yard, 
depending upon the condition of the weather 
and the labor. During the early part of the 
construction. Fortune island negroes were em- 
ployed, but were found unsuitable for the work. 
While these men were employed, the cost of ex- 
cavation was rather high. The labor now con- 
sists of natives and Jamaicans, and the cost of 
excavation is kept below 70 cents. 

" The cost of food for each man per day 
varied from 52 cents to 75 cents. This is in- 
cluded in the cost of excavation. The material 
chiefly excavated was blue and brown clay. In 
handling the blue clay, the rains had no eflFect 
upon it whatever. The brown clay becomes 
rather difficult to shovel when wet, as it has a 
tendency to stick. In the former, the same 
amount of material can be hauled on a wet day 
as on a drj- day. The haul in some cases was 
over four hundred feet. During rainy days the 
work was not interrupted. 

" The rate of exchange at present is 200 per 
cent, premium." 



40 



NICARAGUA CANAL COMMISSION 



An engineer of large experience in Guatemala 
states that prices for grading on railroad work in 
that country were as follows: for earth, from 30 
to 40 cents; for loose rock, from 05 to 85 cents, 
and for solid rock, from $1.40 to $1.75, exclusive 
of cost of administration and engineering. The 
prices paid for clearing ranged from $G5 per 
acre on the swamp work, to as low as $25 for the 
upper end of the line. The cost of masonry, 
where the haul was less than half a mile, was 
about $24 to $28 for first-class, $14 to $18 for 
second, and $10 to $12 for third. " In all of the 
foregoing, prices are expressed in the silver of 
the countiy." The rate of exchange is not 
stated. 

Another engineer, also in Guatemala, states 
that the unit prices there were, for earth 40 cents, 
telpetate $1.00, loose rock $1.25, solid rock 
$1.80, masonrv' exclusive of cement, third class 
$10, second class $16 and first class $25 per cubic 
yard. '' These prices include a good profit if 
work is propc^rly handled." They are all on a 
silver basis. Converted into gold at the Nicara- 
gua ratio they Avould be: for earth, 16 cents; tel- 
petate, 40 cents; loose rock, 50 cents; solid rock, 
72 cents; third-class masonry, $4.00; second- 
class, $6.40; first-class, $10.00. 

Mr. M. P. Carter, Civil Engineer on the con- 
struction of the Cauca Railroad in Colombia, 
where the rainfall is said to exceed 300 inches a 
year, testified under oath that " a man working 
in earth w-ork would move three or four yards 
a day at 40 cents a yard, that is the average. For 
loose rock, that has been loosened a little with a 
pick, he might move a yard and a half or two 
yards a day at 80 cents a yard, and for conglom^ 
erate, a man would not move more than two- 
thirds or three-quarters of a yard per day at 
$2.20 per yard." All of the above prices are in 
Colombian money, wdiicli would make the equiv- 



alents in gold for earth, 17.2 cents, for loose 
rock, 34.4 cents; for conglomerate, 92 cents. 

(Extract from a letter from Mr. Harold R. 
Miller, dated Atlas Line of Mail Steamers, New 
York, April 22, 1899.) 

" The three rates for earthwork and conglome- 
rate were 40 cents, 80 cents, and $2.20, Colom- 
bian, as per ^Ir. Carter's evidence. TTie ex- 
change at that time was 130-150, say 140 per 
cent. ; that makes 17 cents, 34 cents, and 92 cents, 
gold. To-day the exchange is 230 per cent., 
viz: $1 gold is $3.30 Colombian. Labor, of 
course, has not risen in proportion with the ex- 
change, so that constniction work is really cheap- 
er to-day than then, because contractors get more 
cuiTency for their gold and pay about the same 
rates. Labor is about $1 Colombian in the in- 
terior, $1.40 to $1.60 on the coast. The condi- 
tions on the isthmus are different from the rest 
of the Republic, owing to the silver currency, 
which alone prevails on the isthmus; the rest of 
the Republic iLses paper, which has about 20 per 
cent, discoinit as compared with silver." 

(Extract from communication, dated October 
30, 1897, from Edwin F. Smith, Civil and Hy- 
draulic Engineer.) 

" In conclusion, I desire to say that, . . pro- 
cesses of dredging have improved very much in 
recent years, and large companies in the United 
States would, I think, be found willing to take 
such contracts at Greytown, and on the line of 
the Nicaragua canal at less than the figures 
given in the estimates of the Canal Company. 

" This is true not only of dredging, but also 
of rock excavation. There are construction com- 
panies and contractors handling material on the 
Chicago drainage canal wntli modern appliances, 
wdio would, no doubt, eagerly compete for such 
contracts as those of the rock cut through the 
Eastern Divide and the building of the Ochoa 



REPORT OF THE COMMISSION 



41 



dam, and the dredging of Grey town harbor and 
the canal through the lagoons." 

(Extract from a communication from Col. T. 
P. Roberts, Chief Engineer Monongahela Im- 
provement.) 

'' On the Nicaragua canal, if extra good prices 
are paid foremen and bosses, the actual cost of 
work will not be much in excess of that for 
which it could be done here. A general increase 
of 25 per cent, over American prices ought to 
be sufficient. While I would thus suggest a 
reasonable unit price for items of labor, I would 
advise a liberal percentage on the whole work, to 
cover engineering and management. Admin- 
istration ex}>enses will doubtless be very high at 
first, but this it^^m will diminish after the officials 
have become acclimatized. Physicians and 
sanitary engineers should be employed to select 
the i)laces for camps, provide the water supply, 
and look after the drainage. If this be properly 
done, the cost for hospital service would not be 
great. I do not see why this item should be dif- 
ferentiated A millage tax on all salar- 
ies and wages should be fixed to maintain hos- 
pitals. 

" It has been my observation for several years 
past that American engineers have been overes- 
timating the cost of work. They appear to me 
to not fully realize the wonderful improvements 
which have been made in this countiy. Many 
of them still think that French and German 
methods on canal work admit of little improve- 
ment, but such engineers have not been atten- 
tive students of the Chicago drainage canal ex- 
perience. 

"" In July of this year, six locks and dams were 
let on the Monongahela river. The United 
States Engineers' estimate for them all was 
about $1,200,000, which amount I thought was 
about the right thing, but, although the estimate 



was publicly known, a number of responsible 
contractors bid less than $800,000, and it was 
actually awarded for less than $700,000. The 
bidder failing to isecure bondsmen, the Depart- 
ment ordered another letting." 

For convenience of comparison these prices 
are tabulated as follows: 

Earth. SoUd rock. 

Chicago basis. . . .29 77 

Earth. Loose rock. ttoUd rock. 

Costa Rica 18 30 60 

Guatemala 14 30 63 

16 50 72 

Colombia 17 34 92 



Average . . .16^ 



36 



71J 



From this it appears that the actual cost of 
earth work in these tropical countries is in gen- 
eral less than that given for the Chicago basis. 
The average for earth and loose rock is 26 cents, 
which is less than the Chicago price of 29. The 
average of the rock work is also five cents below 
that at Chicago, so that it would seem that the 
statement of Mr. Shunk, Chief Engineer of 
the Intercontinental R. R. Commission, is ap- 
parently correct that *' an estimate of like work 
at home would be fairly applicable down 
there.'' 

In view, however, of the difiiculties of secur- 
ing a sufficient supply of laborers for so great a 
work, and of regulating their wages, the Com- 
mission has concluded to increase the actual av- 
erage prices paid at Chicago by 33 J per cent, for 
all earth and rock work on the western division 
and by 50 per cent, for work on the eastern di- 
vision, after allowing an increase of 10 cents for 
rock on the eastern division because of local 
differences and character of material. 

The prices applied to the quantities will there- 
fore be as follows: 



42 



NICARAGUA CANAL COMMISSION 



On the East Side. 

For Greytown harbor, dredg- 
ing $ .25 per cu. yd. 

For Greytown harbor, jetties. 2.50 " " *' 

For dry earth excavation 44: " " " 

For solid rock excavation. . . . 1.30 " " " 

For dredging in upper river. . .30 " " ^' 

For dredging in lake 20 " " " 

For rock under water 5.00 " *' " 

Timber cribs 3.25 " '' " 

Clay puddle and back filling, 
exclusive of cost of excava- 
tion .50 " " '' 

Concrete in structures other 

than locks 8.30 " " " 

Concrete in locks 7.23 " " " 

Stone pitching on embank- 
ments 2.00 " sq. yd. 

Timber in structures 60.00 " M.B.M. 

Clearing 75.00 " acre. 

Clearing and grubbing 100.00 " " 

On the West Side. 

For dry earth excavation. . . .$ .39 per cu. yd. 

For solid rock excavation 1.03 " " " 

For dredging harbor 20 " " " 

For rock under water 5.00 " " " 

For jetties 2.00 " " " 

Timber cribs 3.00 " " " 

Clay puddle and back filling, 
exclusive of cost of excava- 
tion 50 " " " 

Concrete in structures other 

than locks 8.30 " " " 

Concrete in locks 7.23 " " " 

Stone pitching on embank- 
ments 1.75 " sq. yd. 

Timber in structures 60.00 " M.B.M. 

Clearing 75.00 " acre. 

Clearing and grubbing 100.00 " " 

The prices for structural work of locks and 
weirs are based on the cost of similar work in 
the United States, to which 33 per cent, has 
been added for diflFerence of location, including 
climate, etc. 



Feasibilfiy. 

Under this division of the subject, the Com- 
mission would respectfully submit that it has 
failed to find any competent authority that de- 
nies the feasibility of constructing a canal across 
Nicaragua. 

The feasibilitv of the canal is conceded for 
the following reasons: 

. 1. There are at this date sufficient precedents 
for ship canals capable of passing the largest 
vessels, so that any question of the navigation of 
such a channel is eliminated. 

2. The ability to construct and operate locks 
of the requisite dimensions is sufficiently estab- 
lished by existing structures on the Manchester 
and Keil canals, at Davis island on the Ohio, 
and at the St. Mary's canal, Michigan. 

3. The possibility of constructing the neces- 
sary dams, weirs, sluices and embankments, 
which shall be sufficiently stable and imperme- 
able to control the water required for naviga- 
tion, as well as to regulate the floods, is within 
the resources of the engineering profession and 
is fully demonstrated by the many hundreds of 
miles of embankments, levees and dams, both at 
home and abroad. There is no reason to doubt 
the ability to build them out of the native rocks 
and earth and to give them the required strength 
and tightness to retain or to discharge the water 
with safety. 

4. . There is no question as to the adequacy of 
the supply of water for all purposes at all sea- 
sons nor as to its control in times of flood. 

5. Neither is there any doubt with reference 
to the ability to secure good supporting ground 
for the trunk of the canal nor suitable sites for 
locks and dams. 

6. The harbor question is only a matter of 
money and it is believed that good, capacious 
and safe artificial harbors can be created at a 



REPORT OF THE COMMISSION 



43 



reasonable cost In brief, this Commission sees 
no reason to doubt the entire feasibility of the 
project, but it realizes the necessity of exercis- 
ing due care in the preparation of the specifica- 
tions and in the conduct of the work, that the 
details of construction l)e tlioroughly inspected 
and properly executeii under competent super- 
vision. 

Estimate. 

After a careful analysis and comparison of the 
physical features and quantities aflFecting the 
numerous variants, the Commission has selected 
that route which it believes will give the best 
results. 

This route, starting from the harbor at Grey- 
town, crosses the coastal plain, passes to the 
north of Lake Silico, and up the left bank of the 
San Juan to the dam at Boca San Carlos, thence 
follows the improved river channel, crosses the 
lake, and traverses the valleys of the Lajas and 
Eio Grande to Brito on the Pacific. 

It is characterized by 6 locks on the eastern 



division, having a lift of 18.41 feet, all Mng 
east of the dam, and 4 locks on the western di- 
vision, having a lift of 29 feet. The summit 
level extends from the lock .43 of a mile east of 
the beginning of the cut at Boca San Carlos to 
the lock 1.80 miles west of Buen Retiro, a dis- 
tance of 139.3 miles. 

The details of the estimates are stated in the 
reports of the assistants hereto appended, and it 
will suffice here to summarize and classify the 
quantities for the excavation of the canal trunk 
and to affix their unit prices in order to ascer- 
tain the approximate cost. The auxiliary works 
have also been computed for each subdivision 
separately and in detail, but the totals only are 
stated in this connection. The calculations are 
based upon a minimum elevation of 104 for the 
summit level, with a depth of 30 feet and a 
minimum bottom width of 150 feet, as set forth 
more particularly under the " Dimensions of the 
Canal." 



General Estibiate of Cost. 
East side, with 50 per cent, over Chicago prices for earth and rock. 



Classification. Cu. yds. 

Earth 23,206,836 

Rock 1,309,375 

Rock under water 472,705 

Dredging (harbor) 10,748,900 

Dredging (lake) 17,308,850 

Dredging river «fe canal . . 46,555,742 

Dredging upper river . . . 15,183,100 

114,785,508 



Price. 

at$ .44 

" 1.30 

" 5.00 

" .25 

" .20 

" .30 

" .39 



Amount. 

$10,211,007.84 
1,702,187.50 
2,363,525.00 
2,687,225.00 
3,461,700.00 
13,966,722.60 
5,921,409.00 

$40,313,846.94 



West side, with 33i per cent over Chicago prices. 



Earth 21,949,472 

Eock 6,264,617 

Rock under water 281,673 

Dredging harbor 9,500,000 

37,995,762 



at$ .39 
" 1.03 
" 5.00 
" .20 



152,781,270 



$ 8,560,294.08 
6,452,555.51 
1,408,365.00 
1,900,000.00 

$18,321,214.59 

$58,635,061.53 



44 



NICARAGUA CANAL COMMISSION 



Auxiliary AVorks. 

Cu. yds. 



Classifloation. 

Amount brought forward 

Jetties, Greytowii 550,000 

Jetties, Brito 144,107 



Price. 



at $2.50 
'' 2.00 



Amount. 

$58,035,061.53 

$ 1,375,000.00 

288,214.00 



$ 1,063,214.00 

Concrete dam and regulating works at Boca San Carlos. . . . 4,570,340.00 

4 locks on west side, 28 feet lift 7,412,580.00 

6 locks on west side, 18.41 feet lift 9,560,400.00 

Weir on west side, Buen Retiro 1,102,300.00 

AVeirs on east side below San Carlos 207,890.00 

Clearing and grubbing (7463 acres) 615,625.00 

Guard gates, timber piers, piling, etc 1,089,343.00 



Miscellaneous. 

100 miles of R. R. for construction purj^oses, at $50,000 
per mile (double track) 

Sanitary and police 

For maintenance of harbors during construction of canal, 
and for buoys, beacons and lighting 



$24,558,478.00 
$84,856,753.53 



5,000,000.00 
2,000,000.00 

1,000,000.00 



Engineering and administration, 6 per cent. 



General contingencies, 20 per cent 



$92,856,753.00 
5,571,405.00 

$98,428,158.00 
19,685,632.00 



Total. $118,113,790.00 



For the cost of engineering and administra- 
tion an estimate of 6 per cent, has been made. 
This estimate is large, but in a work of such 
great importance, the engineering and superin- 
tendence must be thoroughly and carefully done 
by men of ability and integrity who w^ill neces- 
sarily command higher rates of pay than would 
be deemed sufficient in the United States. 

An estimate of 20 per cent, for contingencies 
has been made. It is intended to cover all 
items of expense due to unforeseen accidents or 



emergencies. Owing to the extent and charac- 
ter of the work, there are more uncertainties 
than usual, including that of labor, which w411 
have to be largely imported from the islands of 
the West Indies and from our Southern States. 
No work of this character and importance has 
ever been completed within the tropics. There 
is, therefore, nothing to serve as a precedent or 
guide for the proper contingent percentage, but 
after careful consideration and with a desire to 
make an ample allowance, the Board has decided 



REPORT OF THE COMMISSION 



45 



to include an estimate of 20 per cent., which is 
believed to be quite sufficient for all probable ac- 
cidents or emergencies. 

It is believed that if honestly and properly 
administered, with money at command as re- 
quired, the canal can be built within the limits 
of the above estimate. 

Conclusions. 

The Commission after mature deliberation has 
adopted and estimated for the route from Brito 
to Lake Nicaragua, called Childs' route, variant 
Xo. 1, and from the lake to Grey town, that 
called Lull route, variant No. 1. This line leav- 
ing Brito, follows the left bank of the Rio 
Grande to near Buen Re tiro, crosses the West- 
ern Divide to the valley of the Lajas which it 
follows to Lake Nicaragua. Crossing the lake 
to the head of the San »Tuan river, it follows the 
upper river to near Boca San Carlos, thence, in 
excavation, bv the left bank of the river to the 
San Juanillo, and across the low county to Grey- 
town, passing to the northward of Lake Silico. 
It requires but a single dam, with regulating 
works at both ends of the summit level. 

The new location selected for the dam at Boca 
San Carlos eliminates one of the most serious 
engineering difficulties by avoiding entirely the 
San Carlos river with its torrential floods and 
large volume of sediment, and by locking down 
immediatelv from this dam the difficulties and 
risks of the high embankments of the Menocal 
line are also avoided. 

Instead of the dam at La Flor a lock and 
regulating works have been substituted at Buen 
Retiro where the topography is well adapted for 
the purpose. It is also proposed to divide the 
sui'plus waters of the lake basin between the east 
and west sides, thus reducing the velocities in 
the San Juan and securing ample waste-way 



cai)a(*ity for the maximum discharge that can 
ever occur, if stored and distributed over a short 
period of time. Ample provision has also been 
made for a possible fluctuation of the lake of 6 
feet or more without injury to property, by fix- 
ing the elevation of the bottom of the canal 
sufficientlv low to cover seasons of minimum rain- 
fall. The surveys have in general revealed better 
physical conditions than were hitherto supposed 
to exist, especially as to the amount of rock in 
the upper river, whereby it is possible greatly to 
reduce the estimated cost of construction. This 
fact will account largely for the comparatively 
moderate amount of the estimate when the en- 
larged dimensions of the project are taken into 
consideration. Other reductions are due to the 
improved methods and machinery available, as 
developed on the Chicago drainage canal, and 
which cannot be ignored in discussing a work 
of this magnitude. 

The creation of sufficiently capacious interior 
harbors presents no unusual difficulties, and they 
can be secured at a reasonable cost. 

The field work, under the authoritv of this 
Commission, has been carefully and well done, 
and is believed to be all that is necessary for the 
preliminary location of a canal, and to deter- 
mine, within narrow limits, the final location of 
(lams, lo<^ks, and other constructions. Should a 
canal across Nicaragua be authorized, it will be 
neccssar\' to make further minute and careful 
investigations by borings to determine the exact 
location of locks and dams, for which this Com- 
mission had neither the time nor money, nor 
would it have been justified in doing work of 
this character until the construction of a canal 
was assured. The computations of amounts to 
be excavated have been carefully made and 
checked to guard against errors and are believed 
to be accurate within narrow limits. All pos- 



46 



NICARAGUA CANAL COMMISSION 



sible information has been sought with regard 
to cost of similar work in the United States and 
in Central America, and a careful comparison 
made of the probable diflFerences between Nica- 
ragua and the United States. 

To determine the proper unit prices for ex- 
cavation the average of prices actually paid to 
contractors on the Chicago drainage canal, which 
represent cost of plant, prices paid for work 
done, and contractors' profits, were taken. Up 
to this point the Commission dealt only with 
facts. To the prices paid at Chicago certain 
percentages have been added for the difference 
in location, climate, etc., etc. These percent- 
ages are, of course, a matter of judgment, upon 
which men may honestlv differ. But from all 
the information obtainable by this Commission 
and after careful consideration, with a desire to 
arrive at a proper conclusion, those used in the 
estimate are deemed fair and reasonable. 

In obtaining the estimate for cost of locks the 
prices actually paid for building the Govern- 
ment locks at the Sault Ste. Marie were taken, 
and 33 per cent, was added for the difference of 
location. This percentage is believed to be 
ample, as a large part of the expense of con- 
structing the locks will be for material, much 
of which can be furnished in Nicaragua at the 
same or only a small advance upon the prices in 
the United States. 



After giving due weight to all the elements 
of this important question and with an earnest 
desire to reach logical conclusions, based upon 
substantial facts, the Commission believes that 
a canal can be built across the isthmus on this 
route for a sum not exceeding that stated in the 
estimate. 

The dimensions of the canal proposed are 
much larger than any hitherto considered and 
will be ample not only to meet the present re- 
(luirements of commerce but also for many years 
to come. A navigable channel of smaller di- 
mensions than those proposed, only sufficient for 
present needs, can be constructed for a lesser 
sum if deemed expedient. 

We have the honor to be. Sir, 

Your obedient servants, 

J. G. Walker, 
Eear- Admiral, U. S. Navy, 

President of Commission. 

Lewis M. Haupt, 
Civil Engineer, Member. 

In appending my signature to this report, I 
desire to state that I concur generally with the 
views expressed, but my estimate of the cost is 
$134,818,308. 

Peter C. Hains, 
Colonel, U. S. Corps of Engineers, Member. 



APPENDIX I 



REPORT OF E. S. WHEELER 



CHIEF ENGINEER 



CONTENTS 

Field Work. 

Organization and Ingtnictions to Parties 51 

Results aecomplishecl 52 

Topography axd Physics. 

General Discussion . 54 

South of the San Juan River 54 

North of the San Juan River 55 

Lake Nicaragua to the Pacific 56 

Lake Nicaragua 57 

Earthquakes 58 

San Juan River 58 

Volume and Tributaries 59 

Character of Bed of River 60 

Delta Plain 61 

Sand Movement 61 

Location. 

The Canalization of the Lower San Juan 62 

The Canalization of the Upper San Juan 63 

Fluctuations in the Lake Level 64 

Grade 68 

Additional AVaste-ways 68 

Estimates. 

Nomenclature of Routes 70 

Unite Prices 70 

Prices for the East Side 72 

Prices for the AVest Side 72 

Maritime Canal Co.'s Proposed Canal 72 

Menocal Route, Variant 1 73 

Lull Route, Variant 1 75 

Various Routes, Sarapiqui Ridge to Caribbean Sea 76 

Locks 78 

Various Estimates 78 

Comparison of Estimates 79 

Route with One Dam 80 

Route with Three Dams 81 

The 100-ft. Canal 83 

Value of Estimates 84 

4 



APPENDIX I 



Washington, D. C. 

Rear-Admiral J. G. Walker, U. S. Navy, 
President Nicaragua Canal Commission, 
Washington, D. C. 

Sir: — I have the honor to submit the follow- 
ing report of operations connected with the 
Nicaragua Canal Commission: 

The expedition sailed from New York De- 
cember 5, 1897, on the U. S. Gimboat " New- 
port." There were on board, the Commissioners 
and sixty-nine employes. The expedition landed 
at Greytown December 18. On the 21st 
I received your instructions to " take charge of 
the field work and direct the operations of the 
various parties." 

The force was divided into eight parties with 
the following organization and instructions: 

Dr. C. W. Hayes, from the U. S. Geological 
Survey, was directed to take charge of the geo- 
logical work, including the earth and rock bor- 
ings. There were assigned to him the following 
assistants: 

Ignatius O'lleardon, Moriz Bernstein, 
Ilarrv Spence, W. E. Herbert, 

P. Tiemey, E. F. Fischer, 

T. J. H. Archambault, E. P. Humphrey. 

Mr. A. P. Davis, also from the U. S. Geo- 
logical Sur\'ey, was directed to take charge of 
the hydrology and meteorology. There were 
assigned to him the following assistants: 



R. C. Wheeler, 
D. H. Baldwin, 
W. M. Barton, 
F. C. Green, 
H. S. Reed, 
W. W. Schlecht, 



G. P. Philip, 
H. W. Miller, 
G. R. Wadleigh, 
R. Breese, 
Neil P. Leary. 



Mr. J. W. G. Walker was directed to make a 
topographical survey of the west side. The fol- 
lowing assistants were assigned to him: 



E. B. Harden, 
M. A. Coroalles, 
H. C. Hurd, 
C. P. E. Peugnet, 
O. B. Powell, 



L. R. Lee, 
J. A. Bull, 
P. H. Belknap, 
J. D. Forster. 



Mr. George W. Brown was directed to make 
a survey of the San Juan river, beginning at 
Lake Nicaragua. The following assistants were 
assigned to him: 



S. S. Evans, 
C. L. Hammond, 
Lester Bernstein, 
F. R. Torrington, 



E. G. Nicewamer, 
Thaddeus Merriman, 
G. H. AVilliams. 



Mr. H. H. Trundle was directed to make a 
survey of the Canal Company's route from Grey- 
town to Ochoa. The following assistants were 
assigned to him: 

A. J. Norris, 
L. F. McNeil, 
P. J. Brune, 



W. A. Smith, 
Dion Martinez. 



52 



NICARAGUA CANAL COMMISSION 



Mr. Boyd Ehle was directed to make a survey 
for a dam at Tambor Grande and an embank- 
ment southward to the Costa Riean highland. 
The following assistants were assigned to him: 

O. A. F. SaalVve, E. G. Heyl, 
L. S. Snyder, ' T. F. Boltz. 

J. C. Elson, 

Mr. Andrew^ Onderdonk was directed to make 
a survey of the San Juan river beginning at 
Greytown. The following assistants were as- 
signed to him: 

W. G. Fitzgerald, W. D. Thomas, 
R. N. Begien, John Carmichael, 

L. E. Lannan, A. V. Montes. 

Messrs. F. L. Stuart and Stephen Harris were 
directed to run separate lines of precise levels 
from the Caribbean sea to the Pacific ocean. 
The following assistants were assigned to them: 

J. O. Jones, J. A. Mitchell, 

R. B. Post, G. F. Seymour, 

Sherwood Wilson, L. W. Mohun. 

Mr. F. P. Davis was directed to build a line of 
camps along the Canal Company's route from 
Greytown to Ochoa. Mr. George J. Smart was 
assigned to him as an assistant. 

Mr. H. C. Miller was assigned to the Chief 
Engineer as First Assistant. 

Mr. J. Crowninshield was given charge of 
supplies and warehouse at Greytown. He was 
assisted by Mr. J. H. Barnard. 

The following gentlemen were sent out from 
the United States later and were distributed 
among the field parties on their arrival: 

C. H. Stockton, H. W. Durham, 

H. C. C. Shute, J. C. Taylor, 

R. Morrin, H. E. Anschutz, 

John Stockton, L. Hankins, 

H. F. Collins, A. S. Miller. 



The following gentlemen were employed in 
Nicaragua and distributed among the parties: 

A. L. Scott, J. A. Austin, 

Alfred Ahrling, A. E. L. Pain, 

George Challice, Fred. Davis, 

H. E. Webb, E. T. Vargas, 

F. H. Davis, F. D. Glennv. 
Charles Hayman, 

Mr. Brown was recalled to the United States 
shortly after he began work. Mr. Stuart was 
put in charge of his party and Mr. Harris took 
entire charge of the precise leveling. 

Late in the season a new topographical party 
was organized and Mr. Martinez put in charge 
of it; after one month he was replaced by Mr. 
Evans. There were no other changes among 
chiefs of parties, though the exigencies of field 
work made many changes necessary among the 
subordinate members. 

The several parties completed the field work 
assigned them as follows: Mr. Boyd Ehle in 
August, 1898; Messrs. Miller, Onderdonk, 
Trundle and the Chief Engineer returned to the 
United States in September; Messrs. Walker 
and Hayes in October; Mr. Harris in November; 
Mr. Stuart in December; and Mr. Evans in Feb- 
ruary, 1899. " 

Mr. A. P. Davis returned in October, 1898, 
leaving his party in the field under the charge 
of Mr. Hurd, who still remains in Nicaragua. 

The work done and the results obtained by 
each of the parties are given in detail in the 
attached appendices. 

A brief and general outline of the aggregate 
results is as follows: The geology of the coun- 
try has been sufficiently developed so that a 
trustw^orthy geological map of the Nicaraguan 
valley has been made. The material along the 
line of the various canal locations has been clas- 
sified with sufficient accuracy for a preliminary 



APPENDIX I.— REPORT OP THE CHIEF ENGINEER 



53 



estimate. Earthquakes and other seismic dis- 
turbances have been investigated with reassuring 
residts. Tlie rainfall has been measured con- 
tinuouslv for more than a vear at twelve dif- 
ferent stations. The discharge of all important 
streams in the entire drainage basin has been 
measured, both at high and low water, and the 
amoimt of sediment transported by them deter- 
mined. Evaporation obser\^ations have been 
made at different places. 

The probable maximum discharge of all im- 
portant streams has been deduced from their 
flood-plains and such old records as were avail- 
able. 

The fluctuations of Lake Nicaragua, its evap- 
oration, inflow and outflow have been continu- 
ously observed for more than a year. Their 
maximum values have been deduced flx)m the 
elevation of flood-plains and lake beaches, and 
from former observations. A similar study has 
been made of Lake Managua. The possibility 
of diverting certain streams into Lake Managua 
has been investigated and the cost estimated. 

On the west side a topographical survey has 
been made of the vallevs of the Rio Grande 
and the Lajas and the connecting pass betw^een 
their headwaters. This survey has been made 
with sufficient minuteness so that locations and 
estimates can be made directly from the map. 

A topographical survey of the San Juan river 
has been made from the lake to the sea, includ- 
ing all of its distributiaries and the lower reaches 
of its principal tributaries. (The hydrography 
between the lake and Castillo was done by Lieu- 
tenant Hanus of the Xavy, and was not under 
my charge.) This survey has been made with 
suflScient accuracy so that wherever the river 
is canalized the location of the channel and the 
estimate of material can be made directly from 
the map. 



Probable dam sites have been more minutely 
developed. 

A survey has been made of Lake Nicaragua, 
showing the shore line and soundings. 

An outline survey has been made of Lake 
Managua. 

A survev has been made for a dam at Tambor 
Grande and an embankment line running south- 
ward to the highlands of Costa Rica. 

A resurvey has been made of the Maritime 
Canal Company's proposed route from Greytown 
to Ochoa. This survey has been made with 
sufficient detail so that an accurate estimate of 
the amount and classification of material can 
be made. Surveys for a canal location have 
beeif made from the mouth of the San Carlos 
river to Greytown. From the source of the 
San Juanillo to the sea three different lines have 
been run. All of these survevs have been made 
with sufficient accuracy for an estimate along 
the lines themselves, and in most places the 
topography has been so well determined that 
new locations and estimates can be made from 
the map. 

An investigation has been made of the move- 
ment of sand along the shore of the Caribbean 
sea between Port Limon and Monkey Point. 

A duplicate line of precise levels has been 
run from Greytown to Brito. Tide gages have 
been read for several months at both places, so 
that the difference in the elevation of the two 
oceans is quite accurately known. 

In addition, hydrographical surveys of the 
coast in the vicinity of Greytown and Brito 
were made from the U. S. Gunboats " New- 
port " and " Alert." This work was not under 
my charge. 

The aggregate results of this field work, when 
combined with the results of previous canal 
surveys, together with all other existing data, are 



54 



NICARAGUA CANAL COMMISSION 



sufficient to sharply define the limits of the 
" canal region " and to present the important 
physical features of this region which relate 
to canal construction. 

The limits of the canal region and its salient 
physical features will first be presented. 

TOPOGEAPHY AND PllVSICS. 

The following discussion of the topography 
and physics of the Nicaraguan valley is for 
the purpose of determining, first, the limits of 
the canal region; and, second, such physical 
features of this region as relate to canal con- 
struction. 

Much of the data in this discussion is tftken 
from the attached appendices. The geology 
is derived entirely from the report of Dr. C. 
W. Hayes, the hydrology from the report of 
Mr. A. P. Davis and the topography, hydro- 
graphy, sand movement, etc., from the reports 
of the assistant engineers. 

By the term " canal region " is meant the 
region in which a canal may be built at a cost 
so much less than elsewhere that no other lo- 
cality need be considered. Professor Keasbey 
has termed this " the region of comparative fea- 
sibility." 

It is assumed, without discussion here, that 
no canal route is practicable or need be consid- 
ered that does not pass through Lake Nicaragua 
and use it for its feeder and summit level. 

The canal region is shown on Map No. 2 in 
red. It will be seen to be a very narrow strip 
for two-thirds of its length. In the remaining 
third it expands to a width of fifteen or twenty 
miles. All of the proposed canal routes lie 
within this region, and it will be sho^vn that none 
outside of it are as good. (If there were a com- 
plete and accurate topographical map of the en- 
tire country, this fact would become apparent 



by a simple reference to it. In the absence 
of special knowledge derivable from such a 
source, evidence must come from the considera- 
tion of general laws sufficiently convincing to 
those familiar with the conditions.) 

For convenience, the country bordering on the 
canal region will be considered in three parts. 
The first part lies south of the San Juan river 
and is limited on the south bv the foot-hills of 
the Costa Rican mountains. 

The second part lies north of the San Juan 
river and between Lake Nicaragua and the 
Caribbean sea. 

The third part is the narrow strip of land ly- 
ing between Lake Nicaragua and the Pacific 
ocean. 

In the present discussion it is not intended to 
give a complete analysis of the topography and 
physics of the entire Nicaraguan valley; only 
such points will be considered as relate to the 
location of a canal and tend to permit or pre- 
vent its construction. 

A reference to the accompanying map will 
show^ that the portion of the Nicaraguan valley 
which lies between the San Juan river and the 
foot-hills of the Costa Rican mountains is 
crossed by a number of rivers, some of them of 
considerable size. The San Carlos is the largest. 
The Sarapiqui, Frio and Poco Sol are streams 
of considerable size. An inspection of the map 
shows that these streams have their sources in 
the Costa Rican mountains and flow in a north- 
erly direction across the plain into the San Juan 
river. Thev have a swift current but no falls 
or great rapids below the foot of the mountains. 

An examination of the map shows that a canal 
location from the Caribbean sea to Lake Nica- 
ragua, south of the San Juan river, would cross 
all of those streams. This would make its con- 
struction practically an impossibility. The ex- 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



55 



istence of these streams is deemed entirely suf- 
ficient to exclude from the canal region all that 
part of the Nicaraguan valley lying south of 
the San Juan river. The southern boundary 
of the canal region on the eastern side is then 
the south banks of the San Juan and Colorado 
rivers. Before leaving the discussion of the 
flouthem part of the valley a few points will be 
mentioned that relate to and assist in elucidating 
the topography north of the river. An inspec- 
tion of Map No. 1, Sheet Iso. 2, shows that the 
material of this southern part of the Nicaraguan 
valley is volcanic ejecta and alluvium. The 
alluvium is found at the eastern and western ends 
of the valley, where it borders on the Caribbean 
«ea and Lake Nicaragua. The volcanic material 
was ejected from the line of Costa Rican vol- 
canoes and flowed down to the northward, until 
it met the older plain which slopes from the 
north, southward. A reference to Map No. 1, 
Sheet No. 2, will show that the San Juan river 
•does not exactly follow the junction of these two 
plains but cuts through the southern portion of 
the northern plain, leaving a few of the older 
hills south of the San Juan. Of these hills, 
those at the junction of the San Carlos with the 
San Juan are most conspicuous, having an esti- 
mated height of more than 1100 feet. 

The second part is the region lying north of 
the San Juan river and between Lake Nicaragua 
and the Caribbean sea. A reference to Map 
No. 1 will show by the sources of the streams 
that there is a crest-line or divide which is 
nearly parallel to the eastern shore of Lake Nica- 
ragua and about twenty miles distant. If the 
narrow strip of land between Lake Nicaragua 
and the Pacific were removed, this crest would 
become the Continental Divide. This was prob- 
ably the case until quite recent geologic times, 
and the shape of the Pacific shore, before the •out- 



break of the Nicaraguan volcanoes, was some- 
what as shown on Plate No. 11, Appendix 11. 
This is mentioned here because the country be- 
tween Lake Nicaragua and the Caribbean sea is 
much older than the Nicaraguan volcanoes, 
and much of its surface configuration was made 
before Lake Nicaragua was cut off from the 
sea. With this condition in mind it becomes 
easier to understand certain features of the 
topography. The streams east of the Divide 
run in an easterly direction to the Caribbean 
sea; those west of the Divide run in a south- 
westerly direction to Lake Nicaragua. It will 
be observed that the direction of this drainage 
is about parallel to the course of the San Juan 
and at right angles to that of the country south 
of the river. This is an indication that the two 
plains north and south of the river are essen- 
tially dissimilar and that they were formed at 
different times and by different causes. 

It is also very fortunate for canal purposes 
that no large rivers flow into the San Juan from 
the north. The importance of this fact will 
be referred to later. In addition to the two 
plains which slope to the sea and the lake, there 
is a third important line of descent not shown 
on the map, and this is the Divide itself. In the 
northern part of Nicaragua the summits along 
this crest-line reach an elevation of five to seven 
thousand feet. Following the Divide south- 
ward, its elevation steadily diminishes until it 
crosses the San Juan in the vicinity of Castillo 
and is soon lost in the Costa Rican plain. 

Referring again to the map, it will be seen 
that the shortest distance between Lake Nica- 
ragua and the Caribbean sea is less than sixty 
miles, while the canal route is about one hundred 
miles. It will also be seen that the streams and 
consequently the valley lie in a generally east 
and west direction, or favorable for a canal 



56 



NICARAGUA CANAL COMMISSION 



route. The question, then, whether or not this 
shorter route can be utilized becomes an impor- 
tant one; and if this narrowest part of the isth- 
mus is excluded from the canal region it should 
be for a sufficient reason. That reason is the 
elevation of the dividing ridge between the lake 
and the sea. The proof that there are no low 
passes through this divide is quite conclusive. 
Some of the evidence is as follows: When the 
San Juan first overtopped and broke through 
the pass at Castillo, it was at least fifty feet 
higher than it is now. The evidence that it 
has been eroded and cut down fifty feet is ample. 
Since the water would find the lowest pass, it is 
evident, therefore, that there is no other pass 
that is not at least fifty feet higher than the 
present river valley. Again, it has been men- 
tioned that in the northern part of Nicaragua 
the summits of this ridge are seven thousand feet 
high, while the intermediate valleys have ele- 
vations of two and three thousand feet. Both 
the summits and the valleys slope quite uni- 
formlv to the southeast until both are lost in the 
Costa Rican plain. The rate of this descent is 
about ten feet per mile for the valleys. There- 
fore, if this ridge be followed from Castillo in a 
northwesterly direction, the average height of 
its valleys or passes will increase at the rate of 
about one hundred feet in ten miles. So far as 
observations go, this seems to be the case. Per- 
haps the most convincing proof of the consider- 
able elevation of this ridge is the actual observa- 
tions that have been made. In this countrv, 
without roads, the streams are used as thorough- 
fares. All of these streams are continuallv 
traveled by rubber hunters and explorers of all 
kinds. The invariable report of these men is 
that for the first five or ten miles from the sea 
the current is sluggish; after that it is found to 
be rapid all the way to its source, indicating that 



all of the larger streams have their sources in 
elevations of not less than three or four hun- 
dred feet. The small streams that flow into 
the San Juan from the north are rapid in their 
upper reaches and soon rise to a considerable ele- 
vation. Again, the summit of this ridge when 
seen from a distance, shows a uniform slope to 
the southward, but with no indication of notches 
or low passes in it. The cumulative evidence 
of the height and continuity of this ridge is suf- 
ficient to exclude from the canal region all of 
that country lying north of the San Juan, ex- 
cept the narrow valley of the river itself, from 
the lake to the San Juanillo and the broader 
delta plain from there to the sea. The north- 
em boundary of the canal region on the east side 
is, therefore, as shown in Map Xo. 2. 

The third section is the narrow strip of land 
lying between Lake Nicaragua and the Pacific 
ocean. It will be seen that the canal region 
here occupies the valleys of the Rio Grande and 
the Lajas. The route is seventeen miles long. 
The greatest elevation is about forty-five feet 
above Lake Nicaragua. This country is tra- 
versed by roads in every direction. It is quite 
accurately mapped. All the lower passes have 
been examined, and the evidence is complete and 
convincing that the route chosen is through 
much the lowest pass between the lake and the 
ocean, and that the cost is much less here than 
by any other route. This conclusion has been 
reached through actual surveys and observa- 
tions. The boundaries of the canal region on 
the west side are, therefore, as shown on the 
map. 

The physical reasons w^hich limit the canal 
region may be briefly summarized as follows: 
On the east side the country south of the San 
Juan river is excluded by the large rivers which 
cross it. The coimtrj- north of the valley of the 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



57 



San Juan river is excluded by the range of high 
hills which crosses it in a northwesterly and 
southeasterly direction. This leaves for the 
canal region on the east side only the narrow 
valley and delta plain of the San Juan river. 

On the west side the countrv both north and 
south of the valleys of the Rio Grande and 
Lajas is excluded by the range of high hills 
which form the Continental Divide. 

The character and importance of this region 
may be illustrated and emphasized by the state- 
ment that it is believed that anv canal location 
whollv outside of it would cost at least five times 
as much as a similar canal properly located 
within it. 

The boundaries of the canal region having 
thus been determined, the physical features of 
the region itself will next be considered. 

On the west side it is made up of the valleys of 
two small streams and the low pass connecting 
them. The Rio Grande flows into the Pacific. 
Its observed maximum discharge is 2975 cubic 
feet per second. Its minimum discharge is al- 
most nothing. This river has, in former times, 
been much larger than now and has worn a cor- 
responding channel. This old channel has been 
silted up and the present smaller river has cut 
its way through the silt, using only a portion of 
the old river bed. It is probable that this old 
river was the outlet for a time of Lake Nica- 
ragua. Eventually the San. Juan river cut back 
through the Divide at Castillo and turned the 
drainage of the lake to the Caribbean sea. 
Whatever the cause mav have been, the old 
river bed is here and diminishes to a considerable 
extent the rock-cutting in the channel. The 
probability that the outlet of Lake Nicaragua 
was at one time on the Pacific side is of interest 
and some importance and will be referred to 
later. The Rio Grande at times carries con- 



siderable sediment. It shows, however, no signs 
of a delta. The coast in the vicinity of its 
mouth is defended by a series of rocky promon- 
tories. Between them the sand and alluvium are 
shaped by the sea into a slightly concave shore 
line, which appears to be practically permanent. 
The shore where the Rio Grande discharges into 
the sea shows no changes from the earliest maps. 
The sea floor is quite steep, the seven-fathom 
cun^e being about 1300 feet from the shore. 
The tides have a range of about nine feet. 

The Lajas is a small stream flowing into Lake 
Nicaragua. It carries some sediment. The 
bottom of the lake at the mouth of this stream is 
quite steep, the six-fathom curve being about 
4000 feet from the shore. 

The first seven miles of the canal region on 
the west side, beginning at Brito and going east- 
ward, are the flood-plain of the Rio Grande. 
This plain is quite irregular in shape. It has a 
seaward slope of about ten feet to the mile. The 
alluvium of which it is composed varies from 
forty to one hundred feet in depth. It is partly 
imder cultivation but generally wooded. It is 
the most fertile and beautiful valley in the canal 
region. From the head of this valley to Lake 
Nicaragua is about ten miles. The excavation 
for the canal here is almost entirely through 
rock. The average thickness of the earth on 
the rock is about six feet. The rock is shale 
and sandstone, much broken and easy to exca- 
vate. This part of the canal region is quite nar- 
row, the hills approaching closely on each side. 

Lake Nicaragua. 

This lake is about one hundred miles long 
and fortv-five miles wide. It has an area of 
about 3000 square miles. Its greatest depth is 
two hundred feet. It is about one-third the size 
of Lake Erie. The length of the sailing line, 



58 



NICARAGUA CANAL COMMISSION 



between the points where the canal enters and 
leaves it, is about seventy miles. Its total drain- 
age area is 12,900 square miles. Its inflow dur- 
ing periods of great rainfall is sometimes suf- 
ficient to raise the surface six inches in forty- 
eight hours. The maximum calculated outflow 
is 50,000 cubic feet per second. Its evapora- 
tion is estimated to be about five feet annually. 
During the dry season the evaporation exceeds 
the inflow. During exceptionally dry years the 
evaporation exceeds the inflow for the entire 
year. This causes considerable fluctuation in 
the elevation of its surface. It is reported as 
having been as low as ninety-seven feet above 
sea level and as high as one hundred and twelve. 
These reports or traditions are somewhat uncer- 
tain. It is, however, reasonably certain that it 
fluctuates between one hundred and one hundred 
and ten above sea level, at no very infrequent 
intervals. Its depth along the proposed sailing 
line is ample except for thirteen miles on the 
east side. Here submarine excavations will be 
necessary. Borings show that the material to 
be excavated is silt. 

Earthquakes. 

Before considering the east side some of the 
salient facts connected with earthquakes will be 
mentioned. In the northwestern part of Nica- 
ragua slight earthquakes are frequent. Scarcely 
a month passes without one or more being no- 
ticed. The center of these disturbances is 
always near the line of the Nicaraguan vol- 
canoes. The line of volcanoes begins with Ma- 
dera at the southern end, in Lake Nicaragua, 
and terminates with Casiguina at the northern 
end near the Gulf of Fonseca. This country is 
geologically very recent. The great seismic dis- 
turbance which caused this upheaval has nearly 
passed. Nearly all the volcanoes are extinct; 



only two or three are* still . smoking. It is be- 
lieved that this is an era of subsidence and that 
earthquakes and other seismic manifestations 
will continue to grow lighter and finally cease 
altogether. Again, the canal route is entirely 
south of the earthquake area. In the historic 
period there have been no earthquakes in the 
canal region of sufficient violence to injure canal 
structures. It is believed that the danger from 
earthquakes here is now no greater than in any 
other seacoast region. 

East Side. 

The physical features of the east side will next 
be considered. It has already been stated that 
the canal region is only the narrow San Juan 
valley and its broader delta plain. The con- 
trolling physical feature of this region is the San 
Juan river. At one time it was separated into 
two parts by the Continental Divide crossing at 
Castillo. One part flowed eastwardly into the 
Caribbean sea and the other westwardly into the 
Pacific ocean. This condition was so recent 
that many of its topographic and hydrographic 
effects still remain, some of them having an im- 
portant bearing upon canal work. The western 
branch had its sources west of Castillo and was 
formed by the junction of the Poco Sol and the 
Savalos rivers. It then flowed westwardly and 
emptied into the Pacific ocean near where Ma- 
dera now stands. An inspection of the map of 
Lake Nicaragua shows two sections of this old 
river valley not yet silted up; one in the vicinity 
of Madera and the other near Solentiname. This 
latter will be utilized for canal purposes. It will 
be noticed that the depth of this submerged river 
valley is considerably below sea level, showing 
that at the time it was formed the land stood 
higher than now. The southern end of Lake 
Nicaragua has been so silted up that a consid- 



APPENDIX I— REPORT OP THE CHIEF ENGINEER 



59 



erable portion of this old channel is concealed. 
Its old location can, however, be determined by 
boring. The single line of borings between the 
mouth of the lake and Castillo shows it in many 
places. It is probable that considerable rock 
excavation can be avoided by properly develop- 
ing this old channel and following it with the 
canal, rather than the present river bed. An in- 
spection of the map shows that all the tributaries 
of the San Juan river west of Castillo still run 
westwardly in their lower reaches as they did 
when they ran to the Pacific ocean. The east- 
ern branch had its sources on the east of Castillo 
and was formed by the junction of the Bartolo 
with other small streams and flowed eastwardly 
to the Caribbean sea in nearly the same channel 
that it now occupies; except perhaps through the 
delta plain. Its bed has been developed by 
borings in a number of places. Its seaward slope 
seems to have been quite uniform with a gra- 
dient of about four feet per mile, which is much 
steeper than the present river bed. The Ma- 
chuca rapids must have had a fall of about fifty 
feet more than at present, because immediately 
below Machuca the bottom of the old river bed 
is found to be about fiftv feet lower than at 
Machuca. There still remains one section of 
this old channel that has not yet been completely 
silted up. This is between Machuca and the 
mouth of the San Carlos river. This is called 
Aguas Muertas, or dead waters. There are 
soundings in this reach that go below sea level. 
This channel, like the one on the Pacific slope, 
is very deeply worn, thus indicating again that 
the land must have stood higher at that time 
than at present. The tributaries to this branch 
turn eastwardlv in their lower reaches. The 
present San Juan has, therefore, two sets of 
tributaries, those of the lower half, flowing east- 
wardly in the normal direction, and those of the 



upper half, flowing westwardly or opposite to 
the direction of the main stream. 

Volume and Tributaries. 

The San Juan river as it is at present is about 
one hundred and twenty miles long. Where it 
leaves Lake Nicaragua its estimated maximum 
discharge is fifty thousand cubic feet per second; 
above the mouth of the San Carlos it is one hun- 
dred thousand. When it enters the Caribbean 
sea the estimated maximum discharge of all its 
distributaries is three hundred thousand cubic 
feet per second. This makes the upper San 
Juan river a stream comparable in maximum vol- 
ume with the St. Mary's river or the Potomac 
at the head of tidewater, and the lower San Juan 
comparable with Niagara or the Susquehanna at 
Harrisburg. The two principal tributaries are 
the San Carlos with an estimated maximum dis- 
charge of one hundred thousand cubic feet per 
second and the Sarapiqui with an estimated 
maximum discharge of sixty thousand cubic feet 
per second. The reason that so large a river is 
possible in so small a drainage basin is the enor- 
mous rainfall. In the country between Lake 
Nicaragua and the Caribbean sea the average 
annual rainfall is about fifteen feet. The aver- 
age annual evaporation from the land surface is 
about four feet. This leaves eleven feet for 
run-off or about eleven times as deep as the aver- 
age run-off in the United States east of the 
Mississippi. Again, the valley is so small that 
flood-waters are precipitated very quickly into 
the main river. 

When the San Juan first leaves the lake it is 
almost wholly free from sediment, but very little 
is added above the San Carlos. This is evident 
from the fact that the deep channel through the 
Aguas Muertas has not yet been silted up. The 
San Carlos carries large quantities of sand, and 



60 



NICARAGUA CANAL COMMISSION 



from its junction to the sea the San Juan is 
heavily laden with sand. At the head of the 
delta plain the San Juan separates into several 
distributaries. The Colorado is the principal 
stream and carries perhaps four-fifths of the 
water. The lower San Juan is next in im- 
portance. It has a small branch called the 
Tauro. The San Juanillo leaves the main river 
and, after a circuitous curve of about tw^enty 
miles, rejoins it again. The Cario Bravo is a 
branch of the Colorado. The Parado is a small 
stream that leaves the lower San Juan and flows 
into the Agua Dulce lagoon. 

Character of Bed of River. 

From the lake to near Castillo the river bed 
to a depth of thirty feet or more is earth, being 
chiefly silt, sand and clay that has been deposited 
in the old river bed, which has already been de- 
scribed and which was much deeper than the 
present one and sloped westwardly to the Pacific 
ocean. From a little above Castillo to a little 
below Machuca, a distance of about fourteen 
miles, the river flows over a bed of sandstone 
rock in practically the same channel that it has 
always followed. This part of the river has 
never been worn down. The sandstone has re- 
sisted erosion and the river bed here is the same, 
or probably worn a little deeper than it was be- 
fore the drainage of Lake Nicaragua \tas turned 
eastward. This is the only river section in 
which there will be, for canal purposes, any con- 
siderable amount of rock work. Most of the 
rapids occur in this section. There is a fall 
of thirty-seven feet in fourteen miles. At the 
foot of the Machuca rapids the sandstone dis- 
appears. It has previously been mentioned that 
the upper San Juan brings no sediment from 
the lake, and the small streams that flow into it 
carry but little. This is believed to be the ex- 



planation as to why this portion of the old chan- 
nel still remains. The San Carlos carries a large 
amount of sand, so that from its mouth to the 
sea the old channel has been silted up and the 
San Juan now flow^s over a sandv bed betw^een 
banks of sand. 

The important features of the bed of the San 
Juan river may be summarized as follows: 
From the lake to Toro rapids the river flows in 
the partially silted channel of an older stream 
that formerlv flowed westwardlv to the Pacific 
ocean. From Machuca to the Caribbean, the 
river flows in the deeply-worn and partially- 
silted channel of an older stream that had its 
source near Castillo and flowed eastwardly to 
the Caribbean sea. Between Toro and Ma- 
chuca the river flows in what may properly be 
called its own bed, that is, the earlier streams 
that flowed through this section were so small 
and the material over which they ran so hard, 
that thev left no traces of their channel. The 
great amount of sediment and the immense 
floods below the San Carlos make the canaliza- 
tion of this part of the San Juan very difficult. 
Fortunately the topography is such that alterna- 
tives are possible. An inspection of the map 
shows that from the mouth of the San Carlos to 
the sea no large streams enter the San Juan from 
the north. The largest one is the San Francisco 
which has a drainage of about forty square miles. 
Its greatest observed discharge is two thousand 
cubic feet per second. Its estimate'd maximum 
discharge is four thousand cubic feet per second. 
This amount of water is not so great that it can- 
not be admitted to the canal and passed out 
again through sluices without serious inconveni- 
ence. There are some hills that approach close 
to the river but none that cannot be either cut 
through or passed around. There are, therefore, 
no serious physical objections to building a canal 



APPENDIX I.— REPORT OP THE CHIEF ENGINEER 



61 



along the north side of the San Juan from the 
lake to the sea. 

Delta Plaix. 

The delta plain is of considerable extent. Its 
outlines are quite accurately shown on the map. 
It has a seaward slope of about one and one- 
half feet per mile. It is heavily wooded and 
for the most part marshy. There are some hills 
in it, mostly between Lake Silico and the Colo- 
rado river. These hills are much older than the 
plain. They resemble islands in a sea of allu- 
vium. The material and surface of the delta 
plain are so uniform that the cost per mile of 
building a canal would be nearly the same in 
any part. 

Sand Movement. 

After the sand has been carried to the sea 
by the streams it is transported by wave action 
along the shore. The observed facts concerning 
the movement of sand along the shore in the 
vicinity of Grey town harbor are as follows: 
From Port Limon, seventy miles south of Grey- 
town to Point of Rocks, forty miles north of 
Greytown, the shore is formed of a coarse black 
sand of volcanic origin. In places this sand is 
known to extend two or three miles inland. The 
hydrographic map of the coast between the Colo- 
rado and the Indio rivers shows that it extends 
seaward to between the seven- and eight-fathom 
curves. Xone is shown beyond the eight-fathom 
curve. To the northwest of Grevtown the 
amount of sand along the shore steadily dimin- 
ishes, until at Point of Kocks it disappears en- 
tirely. This sand is at present being brought 
to the sea by all the streams having their 
sources in the Costa Rican mountains. The 
Colorado and the San Juan carry considerable 
quantities which are obtained from the San 
Carlos and the Sarapiqui. The streams north 



of the San Juan do not carry any. A consider- 
able amount of this sand stops in and about 
Greytown harbor. This quantity has been com- 
puted by Professor Mitchell, by the Board of 
1895, and by Professor Haupt. All have found 
it to be about seven hundred and fifty thousand 
cubic yards annually. An examination of old 
maps shows that at the point where the Maritime 
Canal Company's harlwr is located, the six-fath- 
om curve has been pushed seaward at an average 
rate of seventy-five feet per annum since 1809. 
Dr. Hayes has pointed out that temporary 
harbors have been formed several times near 
where GreytowTi now stands. The first one of 
these was Lake Silico. It was at one time a 
sheltered bay. Some of the hills which now 
surround it were then islands. The silt and 
northward-moving sea drift finally shut it off 
from the sea. Then other harbors were succes- 
sively formed in front of Lake Silico. The 
several long parallel lagoons still show the sites 
of these harbors. The last one, which has been 
known as Greytown harbor, has been entirely 
formed and closed within the historic period. 
The first trustworthy map of the vicinity was 
made in 1809. At that time the sand spit had 
pushed out from harbor head % about three- 
quarters of a mile. If its rate of growth or ac- 
cretion before that time had been the same 
that it was af tenvards, it must have begun about 
the middle of the last centurv. In 1809 there 
was a small but deep and safe harbor behind the 
sand spit. The lengthening of this sand spit 
was very uniform, imtil in 1852 it reached the 
mainland, and the harbor of Greytown was con- 
verted into another lagoon. At present there 
are no definite signs of the beginning of another 
sand spit. It may or may not be that the form 
of the shore is now such that this process will 
not be again repeated. The littoral current off 



62 



NICARAGUA CANAL COMMISSION 



this coast is for the most part southward. On the 
hydrographic charts it is so marked with a velo- 
city of from one to two knots per hour. During 
the year 1898 it ran southward about eleven 
months. When the trade winds were mildest 
the southerly current diminished and finally 
stopped and then flowed gently northward for 
about one month. I was told by the sailors and 
fishermen that this change in the direction of 
the current was expected by them each year. 
An inspection of the map shows that all the 
streams between G rev town and Port Limon have 
at their mouths sand spits which are turned 
northward. The Rio Indio north of Greytown 
has a sand spit now turned southward, though 
formerly it seems to have been turned to the 
northward. The inferences that have been 
drawn from the preceding data are as follows: 
There is a stream of sand moving northward 
along the coast between Port Limon and Point 
of Rocks. It is confined to the belt between 
the eight-fathom curve and the shore. It is, 
therefore, not carried by the littoral current 
which is for the most part southward, but is 
urged along the shore by wave action. The 
amount that has been delivered by the streams 
to the sea is much greater than the amount which 
the sea has been able to move to the northward, 
as shown by the fact that nearly the entire shore 
from Grevtown to Port Limon has been built 
out into the sea by this sand. The volume of 
this sand stream is then limited by the trans- 
porting power of the waves and not by the 
amount delivered by the streams to the sea. 
The volume of the sand stream must vary in 
different localities because portions of it stop in 
the indentations of the shore. Greytown is a 
conspicuous example of this. Northward from 
Greytown the sand stream must diminish stead- 
ily until off Point of Rocks it ceases altogether. 



Since the building out of the shore in the vicin- 
ity of Greytown is much more rapid than it is 
to the northward, it is assumed that more sand 
stops at Greytown than passes by. It has been 
previously stated that the amoimt which stops 
at Greytown is known to be about 750,000 cubic 
vards annuallv. It has therefore been assumed 
that not more than one million cubic yards pass 
Harbor Head annually. This latter assumption 
is a conjecture and is not entitled to much 
weight. 

If these inferences are correct it follows that 
any pier or jetty built out from the shore, at the 
proposed harbor entrance, must cross and stop 
this sand stream and that, to have kept the sea- 
ward end of such pier or jetty at the six-fathom 
curve for the last ninety years, an annual exten- 
sion of at least seventy-five feet (may be much 
more) would have been necessary. It also 
follows that the further north the location, the 
smaller will be the volume of the intercepted 
sand stream. 

Location. 

The limits of the canal region having been 
found to be narrow and the region itself small, 
the question of location is very much simplified. 
But narrow and small as it is, there are several 
alternative locations, each having merits suffi- 
cient to demand consideration. 

The canalization of the San Juan river may 
first be considered. It has been pointed out 
that the floods in the San Juan at the mouth of 
the San Carlos may be expected to exceed 
200,000 cubic feet per second, while in the 
lower reaches they will exceed 300,000. 

The San Carlos discharges into the San Juan 
a large amount of black sand which is carried 
by the latter river to the sea. The channel of 
the San Juan was formerly much deeper than 



APPENDIX I.— REPORT OP THE CHIEF ENGINEER 



63 



now and has been filled to a considerable depth. 
For example, at Upper Ochoa the black sand in 
the bed of the river was found to be sixty feet 
deep; at Lower Ochoa it was seventy feet deep; 
at Tambor Grande it was one hundred and fifty 
feet deep. Below the black sand was found in 
everv case the solid rock of the old river bed. 
This shows that suitable foundations for dams 
can only be found at great depths. 

The objections to canalizing this part of the 
river are its great floods, its sediment transporta- 
tions and the great depth of suitable foundations 
for dams. These objections are not wholly in- 
surmountable, and if there were no alternative 
they might be considered. It has, however, 
been already pointed out that there is an alterna- 
tive route going across country from the mouth 
of the San Carlos to the sea, and that this route 
crosses no large streams or high hills and pre- 
sents no unusual difiiculties. Since it is unques- 
tionably the better of the two plans, the canali- 
zation of the river between the mouths of the 
San Carlos and the Colorado will not be further 
considered. 

The canalization of the lower San Juan from 
the Colorado to Greytown is feasible, because it 
can be cut off from the main river by a dam, 
thus preventing floods and sediment trans- 
portation. It will be considered later in con- 
nection with one of the locations. 

The Canalization of the Upper San Juan. 

It has already been pointed out that this reach 
of the river has flood discharges of 50,000 cubic 
feet per second where it leaves Lake Nicaragua, 
and 100,000 above the mouth of the San Carlos, 
that it carried but little sediment, and that its 
bottom between Machuca and Castillo is solid 
rock and near the surface, which is verv favor- 
able for dam foundations. Between Machuca 



and the mouth of the San Carlos the solid rock 
is about sixty-five feet below tlie surface of the 
river. These conditions are much more favor- 
able for canalization than those of the lower 
part of the river. The flood discharge of 50,000 
and 100,000 cubic feet per second through fifty 
miles of dredged channel, with earth banks, is 
the most objectionable feature. It is feared 
that the stream velocities caused by such floods 
would be sufficient to seriously erode the channel 
banks, and make na\ngation difficult. It is be- 
lieved that a waste-way to the Pacific would suf- 
ficients reduce the torrential floods so that the 
question of canalizing this part of the river 
would become a fairly simple one. Fortunately 
a western waste-way is possible and at a cost not 
80 great as to be prohibitive. This question will 
be more fully discussed under the head of 
"Additional Waste- Ways.'' 

The conclusion reached may be summarized 
as follows: The upper San Juan from the lake 
to the mouth of the San Carlos and the lower 
San Juan from the Colorado to Greytown, can 
be canalized at a reasonable cost. The re- 
mainder of the river from the mouth of the 
San Carlos to the mouth of the Colorado could 
not be canalized except at an expense that would 
be practically prohibitive. 

The location of the canal from Lake Nica- 
ragua to the mouth of the San Carlos is shown 
on Map Xo. 2. It is practically the river itself. 
It will be observed that some bends in the river 
are shortened by cut-offs while others are not. 
The question whether or not a shortening in the 
route is desirable has been determined by its 
extra cost. The following rule has governed: 
Wherever the length of the canal could he short- 
ened with an extra cost of less than one-quarter 
of a million dollars per mile of shortening , it hus 
been done. TT7ien the extra cost exceeded one- 



64 



NICARAGUA CANAL COMMISSION 



quarter of a million dollars per mile of short- 
ening it has not been done. 

This rule has been derived as follows: It is 
assumed that the business through the canal will 
be ten million tons annually, that the tolls will be 
adjusted so as to produce the maximum revenue, 
and that the rate of interest upon the capital 
to be invested in the canal is four per cent, an- 
nually. The average rate for carrying freight 
over ocean routes of three thousand miles or 
more is usually assumed by statisticians to be 
one mill per mile-ton. Of this amount one-half 
is for shore expenses, loading and unloading, 
warehouse, insurance, etc., leaving one-half mill 
per mile-ton for moving freight through the 
water. It is assumed that vessels move at half 
speed in the canal. Then the cost in the canal 
would be one mill per mileton, and the cost of 
moving ten million tons one mile would be ten 
thousand dollars. Therefore, if the canal could 
be shortened one mile, ten thousand dollars ad- 
ditional tolls could be collected annually. At 
four per cent, this would pay the interest on 
one-quarter of a million dollars. Therefore, 
under these assumptions, one-quarter of a million 
dollars could be borrowed and expended without 
loss in shortening the canal one mile. If the 
shortening cost less, it would be desirable; if 
more, it would be undesirable. The assumptions 
are arbitrary. Therefore, the rule derived from 
them has equal, but no greater, weight than the 
assumptions themselves. 

From the mouth of the San Carlos river to 
the sea several routes and variants have been 
considered. They are all shown on Map No. 2. 
They include all of the characteristic feasible 
routes. An infinite number of minor changes 
in location are possible, some of them probably 
profitable to some small extent But it is be- 
lieved that there is no route worthy of considera- 



tion that is not substantially included within the 
limits of those here given. 

The locations on the west side are shown 
on Map Xo. 2. They include former loca- 
tions made by the Maritime Canal Company. 
The Commission's location is made with ref- 
erence to minimum excavation, suitable lock 
sites and a waste-way to the Pacific. The 
valleys are so narrow and the physical condi- 
tions so sharply defined that no considerable 
variation in location is possible. It is believed 
that the route chosen cannot be much, if any, 
improved. 

Fluctuations in Lake Level. 

It has already been mentioned that Lake 
Nicaragua has a range in elevation of at least 
ten feet, and there are traditions of still greater 
changes. 

If used for a canal it is desirable to limit these 
fluctuations as much as possible. A very fair 
determination of what can be safely done in this 
direction, can be derived from the data now in 
hand. These data consist, first, of the observa- 
tions made by the Commission during the year 
1898. There were observed, the rainfall in the 
entire basin of Lakes Nicaragua and Managua; 
the continuous outflow from Lake Nicaragua; 
the evaporation from its surface, and the daily 
changes in its elevation. These obsei*vations are 
trustworthy and ample for the year. In addi- 
tion there is available a rainfall record made at 
Rivas, continuous for nearly twenty years. Mr. 
Davis shows that this record appears to be trust- 
worthy. Since the fluctuations in the lake sur- 
face are a direct and almost linear fluctuation of 
the rainfall, it is possible to determine what this 
relation is from the observations of 1898, when 
both rainfall and fluctuations were observed, 
and then apply it directly to the preceding years 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



65 



when only rainfall was observed. In this way 
the fluctuations at any time during the last 
twenty years, can be determined with reasonable 
accuracy. The investigation has been made as 
follows: Th3 observed evaporation from the 
lake surface in 1898 was fiftv-two inches. This 
result is the mean of three stations around the 
lake. The monthly rate ranged from 6.5 inches 
in April to 3.1 inches in September; April be- 
ing a dry month and September a wet month. 
1898 was an imusually wet year. It has been 
assumed by Mr. Davis that in a dry year the 
evaporation from the lake surface would be as 
much as sixty inches. Only one other assump- 
tion has been found necessary to complete the 
discussion. In determining the relation be- 
tween rainfall at Rivas and rise in the lake sur- 
face the following method was used. It was 
found that for the year 1898 one hundred and 
eight inches (108) of rainfall at Rivas corre- 
sponded to a rise in the lake of one hundred and 
fifty-four (154) inches. This is the only di- 
rectly observed relation that we have. It is not 
believed that exactlv the same ratio will hold 
for the different rates of rainfall. Mr. Davis 
says in Appendix III: 

" While we have no conclusive data upon 
which to estimate the percentage of nm-off to 
rainfall in the basin of Lake Nicaragua, it is well 
established, as a general rule, that in any given 
basin the greater the rainfall in a given time the 
greater the percentage of nm-oif. So that if 
the rainfall were increased twenty-one per cent, 
the nm-off should be increased somewhat more. 
Say twenty-five per cent." 

If this assumption be applied to the preceding 
observations, the following table is obtained 
showing the rise in Lake Nicaragua, cor- 
responding to different rates of rainfall at 

Rivas. 

5 



30 in. of rainfall at Rivas corresponds to 34 
in. rise in lake. 

40 in. of rainfall at Rivas corresponds to 48 
in. rise in lake. 

50 in. of rainfall at Rivas corresponds to 63 
in. rise in lake. 

60 in. of rainfall at Rivas corresponds to 78 
in. rise in lake. 

70 in. of rainfall at Rivas corresponds to 93 
in. rise in lake. 

80 in. of rainfall at Rivas corresponds to 109 
in. rise in lake. 

90 in. of rainfall at Rivas corresponds to 125 
in. rise in lake. 

100 in. of rainfall at Rivas corresponds to 141 
in. rise in lake. 

110 in. of rainfall at Rivas corresponds to 157 
in. rise in lake. 

120 in. of rainfall at Rivas corresponds to 175 
in. rise in lake. 

130 in. of rainfall at Rivas corresponds to 192 
in. rise in lake. 

This table is intended to be used onlv in com- 
paring the total rainfall of different years. 
When partial seasons are discussed a special de- 
termination is made for each case. 

As a preliminarv step in the investigation, the 
amount of water nccessarv for the use of a canal 
has been determined as follows: If the busi- 
ness of the canal should be 10,000,000 tons an- 
nually and 2000 tons should be passed at each 
lockage, then 5000 lockages would be required 
on each side. If the vessels were all going one 
wav 5000 lockfuls of water would l)e used, 
which would be the maximum. If going alter- 
nately in opposite directions, then 2500 lock- 
fuls would be used, which would bo a mininiuni. 
If the mean be taken then 3750 lockfuls would 
be used annually on each side, or 7500 on both 
sides. With a six-lock svstem this would amount 
to 7,341,600,000 cubic feet annually. 

leakage is a more variable quantity, depend- 



66 



NICARAGUA CANAL COMMISSION 



ing upon the condition of the gates, valves, em- 
bankments, etc. It is estimated that the leak- 
age in the Poe Lock at Sault Ste. Marie averages 
200 cubic feet per second. If this be taken 
for the leakage of one lock out of Lake Nica- 
ragua then the total leakage of the two sides 
would be 12,014,400,000 cubic feet annually. 

For the purposes of operating the machinery 
of the locks, generating lights, etc., it is assumed 
that sixty horse-power operating half the time 
.will be sufficient for one lock. With a fall of 
18.4 feet and a loss of twenty-five per cent, in 
installation, this will require 1,135,290,000 
cubic feet annually. The sum of these three 
quantities is sufficient to low^er the lake level 
three inches annually. The probable changes 
in the lake level during the period of least rain- 
fall \vill first be determined. 

From November 1, 1889, to June 1, 1891, a 
period of nineteen months, the total rainfall at 
Rivas was 38.39 inches. This, from the pre- 
ceding table would have raised the lake 45.75 
inches. Evaporation would have lowered it 
ninety-five inches and the needs of the canal 
w^ould have lowered it 4.75 inches. Therefore, 
the lake at the end of this period would have 
been 54 inches lower than at the beginning, 
even though there had been no outflow. This 
is the driest period observed, but it is not at all 
anomalous. From the beginning of December, 
1884, to the end of April, 1886, a period of sev- 
enteen months, the total rainfall was 37.43 
inches, which w^ould raise the lake surface 44.40 
inches, while evaporation and the needs of a 
canal would lower it 89 inches, thus leaving 
it 44.6 inches lower at the end of the period 
than at the beginning. Again, from the begin- 
ning of November, 1894, to the end of April, 
1896, a period of 19 months, the total rainfall 
was 45.15 inches which would cause the lake to 



rise 55.72 inches, w^hile evaporation would have 
lowered it 95 inches and the needs of a canal 
w^ould have lowered it 4.75 inches more, thus 
leaving the lake 44 inches low^r at the end of 
the dry period than at the beginning. The re- 
currence of such dry periods three times in 
twenty years show-s that they are to be expected 
in the future and should be provided for. The 
only way in which such provision can be made, is 
by the temporary storage of water in the lake. 
If at the beginning of the dry period the lake 
had been 54 inches higher than necessary for a 
30-foot draft, then at the end of the dry period 
the draft would have been reduced to exactlv 
30 feet. A fluctuation of 54 inches is, there- 
fore, absolutely necessary to provide for periods 
of as small rainfall as have occurred in the last 
20 years. Since it would be impossible to con- 
trol the lake within exact limits an additional 
18 inches of fluctuation has been arbitrarily 
added, making the total allowable fluctuation 
six feet. This fluctuation is necessarj^ in order 
to maintain a 30-foot draft during dry periods. 

The periods of large rainfalls will next be con- 
sidered. 

Between June 18 and October 29, 1898, a 
period of 132 days, the rainfall at Rivas was 
76.36 inches, the lake rose 48.00 inches; the out- 
flow lowered it 32.76 inches and the evaporation 
on the lake surface lowered it 16.88 inches. 
Therefore, if there had been no evaporation on 
the lake or outflow from it, it would have risen 
97.64 inches. 

Between May 17 and October 27, 1897, a 
period of 164 days, the rainfall at Rivas was 
112.42 inches. This was the period of greatest 
rainfall shown in the Rivas records since 1879. 
The amount of fluctuation in the surface of Lake 
Nicaragua caused by this rainfall was not ob- 
served; an attempt will be made to determine 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



67 



it by comparison with the wet portion of 1898, 
when both fluctuation and rainfall were care- 
fully measured. The problem may then be 
briefly stated as follows: If a rainfall of 76.36 
inches in 132 days would cause a rise in the lake 
surface of 97.64 inches, what rise would be 
caused by a rainfall of 112.42 inches in 164 
days? The ratio between rainfall and change 
in lake level, as given in the preceding table, 
cannot be used for this problem, because in this 
case only portions of a season are considered. 
At the beginning of these periods the streams 
and marshes were drained, and empty. At the 
end they were overflowing and the entire run-off 
due to the rainfall had not yet occurred. There- 
fore, this problem must be solved as a special 
case. If the rise was exactly proportional to 
the rainfall it would be 143.7 inches, provided 
ithere was no evaporation on the lake nor out- 
flow from it. It is, however, probable that in 
this case as in the preceding one, the greater 
dailv rate of rainfall in 1897 would cause the 
lake to rise slightly more than the proportional 
amount. An examination shows that the daily 
rate of rainfall in 1897 was 18 per cent, greater 
than in 1898. Using the ratio as before, the 



The question as to what amoimt of fluctuation 
in the lake will be necessary to take care of this 
rainfall will next be considered. The estimated 
rise of 148.58 inches must be provided for by 
evaporation, outflow and temporary storage in 
the lake. 

Assuming the ratio of evaporation from the 
lake surface to be the same as in 1898, it would, 
for the 164 davs, amoimt to 20.97 inches. Sub- 
tracting this from 148.58 inches leaves 127.61 
that must be provided for by outflow and tem- 
porary storage. 

The lake has an area of 3000 square miles, a 
rise in its surface of 127.61 inches would be 
equivalent to 889,408,618,000 cubic feet. If 
this should run out of the lake in 164 days, the 
mean discharge would be 62,769 cubic feet per 
second and there would be no permanent change 
in the elevation of the lake surface. If the lake 
should be permitted to rise one foot,, then the 
mean discharge would be reduced to 56,866 and 
each additional foot that the lake is allowed to 
rise will reduce the mean rate of discharge by 
an equal amount. The following table shows 
the required rate of discharge for each foot of 
fluctuation : 



!N'o fluctuation requires 62,800 cubic feet of discharge. 



1 foot 




56,900 








2 feet 




51,000 








3 " 




45,100 








4 " 




39,200 








5 " 




33,300 









rise in the lake would be 22 per cent, greater. 
Applying this per cent, the computed rise in 
the lake for 1897 would be increased from 143.7 
inches to 148.58 inches. This, then, is the esti- 
mated amount of fluctuation that would have 
occurred during the period of greatest rainfall 
of the last 20 years, if there had been no evap- 
oration on the lake nor outflow from it. 



It appears from this table that if a waste-way 
having a capacity of 33,300 cubic feet per sec- 
ond be provided, the fluctuation in the lake could 
be limited to five feet for a rainfall as great as 
any that has occurred in the last twenty years. 

Since the canal itself will incidentally provide 
waste-ways, exceeding this in capacity, it ap- 
pears that not more than five feet of rise need 



68 



NICARAGUA CANAL COMMISSION 



be caused by the largest rainfall. Therefore, 
the range of fluctuation of 6 feet found suf- 
ficient for dry periods will also suffice for wet 
seasons. 

This determination of the volume of the larg- 
est flood in the last twenty years is believed to 
be reasonably correct. It is confirmed by a dis- 
cussion of the flood-plains of the San Juan river. 
This discussion made by Dr. Hayes, shows that 
floods as great as the one under consideration 
probably occur as frequently as once in twenty 
years, while still greater floods occur at much 
longer intervals. It is believed, however, that 
it will be sufficient to control floods equal to 
the largest that have occurred in the last twenty 
years, simply providing locks, embankments, 
etc., with sufficient heights so that when higher 
floods occur no damage will be done to the canal. 

It will be observed that the preceding deter- 
mination of the probable changes in lake level 
are based upon the assumption that the average 
rainfall in the basin of Lake Nicaragua varies 
as the rainfall at Rivas. In general, the aver- 
age rainfall in any considerable area does not 
have as wide a range as the rainfall at a single 
station within the area. Therefore, the pre- 
ceding determination of the fluctuation in the 
level of Lake Nicaragua is more likely to be too 
large than too small. 

Grade. 

Under your instructions the grade has been 
designed so as to give a minimum depth of 30 
feet in the canal at all stages of the sea, lake and 
ocean. For this purpose tide gages w-ere ob- 
served at Greytown and Brito for several 
months. The grade at the bottom of the canal 
at these points was placed at 30 feet below mean 
low tide. At Greytown mean low tide is about 
one-half foot below mean sea level; at Brito it 



is about four and one-half feet. The precise 
levels show that the Pacific ocean, during the 
time our observations were made, was about one 
foot lower than the Caribbean sea, therefore, 
the grade at Brito is about five feet lower than 
at Greytown, and consequently the maximum 
lift on the west side will be five feet more than 
on the east side, while the minimum will be three 
feet less. The upper level of the canal extends 
from near Buen Eetiro on the west side, to near 
Machuca on the east side. 

The upper limit to which the lake will be al- 
lowed to rise has been fixed by you at 110 feet 
above the mean level of the Caribbean sea. 
The permissible fluctuation has been limited to 
six feet. Therefore, the lower limit of the lake 
surface is 104 feet above sea level and the grade 
of the upper level of the canal is 74 feet above 
sea level. The grade of the intermediate parts 
of the canal is determined bv the lifts of the 

ft- 

locks. 

Additional W^vste-Ways. 

It is proposed to control the lake level be- 
tween an elevation of 104 feet and 110 feet 
above sea level by means of dams in the San 
Juan river. These dams are to be provided with 
valves and the outflow from the lake will be 
entirely cut off for a considerable part of each 
season. It is also proposed to place the material 
which is excavated from the river in piles along 
both banks of the river. 

There will be four things that will tend to 
make the floods in the riv^r higher than hereto- 
fore. First, the dams in the river will some- 
what obstruct the flow by diminishing the slope 
and velocity. Second, the spoil banks will con- 
tract the section and prevent the flood waters 
from so readily escaping into the adjacent 
marshes. Third, the water will be retained in 
the lake by the dams so that at the beginning of 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



69 



the rainy season the river will be at a much 
higher stage than formerly. Fourth, the en- 
tire outflow from the lake will be precipitated 
into the river in five or six months instead of the 
entire year as formerly. On the other hand, 
the increased cross section of the river caused 
by the excavation will tend to facilitate the out- 
flow. This is a large factor and it appears (so 
far as computations can show) sufficient to about 
offset the preceding four so that the water might 
all be carried through the San Juan river, with 
no greater velocity or higher floods than for- 
merly. 

The computed effect of all these hypothetical 
cases is uncertain, and it is possible that the 
completed canal might have greater floods and 
velocities than the San Juan river now has. 
Again it is desirable that the current in a canal 
shall be as small as possible. Still water is the 
ideal case. If the upper San Juan is canalized 
its channel banks will be of sloping earth, sub- 
merged, and invisible. Its curves have a pro- 
posed minimum radius of 3000 feet. It is evi- 
dent that strong currents will make navigation 
difficult and will tend to erode the banks and 
refill the excavated channel. In order to re- 
duce these objections to a minimum, a waste-way 
on the west side is proposed. 

The conditions are as follows: The estimated 
maximum outflow from Lake Nicaragua is 50,- 
000 cubic feet per second. The drainage of 
the valley of the upper San Juan sometimes 
amounts to 50,000 cubic feet per second, so that 
the estimated maximum discharge of the San 
Juan above the San Carlos is 100,000 cubic 
feet per second. In order to obtain a minimum 
current in the canalized portion of the river, it 
is proposed to divert all the drainage of Lake 
Nicaragua westward to the Pacific. The drain- 
age of the San Juan valley will be taken down 



the river, though at times of great floods it will 
be divided into two parts by the dam at Ma- 
chuca, one-half being temporarily turned back 
into the lake. In this way the maximum dis- 
charge in the river will be reduced to 25,000 
cubic feet per second, and the maximum velocity 
to 1.5 feet per second. 

It is proposed to make the waste-way on the 
west side through the canal for the first ten 
miles from the lake. The water will then pass 
out of the canal through controlling works, sim- 
ilar to those in the Chicago drainage canal. 
After being discharged from the canal the water 
will pass down to the sea through the channel 
of the Eio Grande, which will be enlarged and 
rectified in places. 

The ten miles of canal that it is proposed to 
use for a waste-way will be almost entirely 
through rock cutting. The sides of the canal 
will be almost vertical and may be protected by 
timber fenders. The water from the lake car- 
ries practically no sediment. A velocity of five 
feet per second will neither injure the canal 
nor materially interfere with navigation. It is 
proposed to make this ten miles of the canal 
200 feet wide with a fall of two feet. This 
with a velocity of not more than five feet per 
second will give a mean discharge of 33,000 
cubic feet per second which, as already shown, 
will be sufficient to limit the fluctuations of the 
lake surface within five feet. The widening of 
this part of the canal to 200 feet will be a sub- 
stantial benefit to navigation. If greater floods 
should occur, there are additional resources in 
reserve. The discharge through the waste-ways 
both on the east and west sides could, with some 
inconvenience to navigation, be temporarily in- 
creased and finally, if the lake should rise a little 
higher than 110 feet above sea level, but little 
harm would be done. 



70 



NICARAGUA CANAL COMMISSION 



Estimates. 

Estimates of amounts of material and com- 
parative cost of construction have been made 
for all the routes indicated on the map. The 
following nomenclature has been directed by 
vou. The several routes on the west side are 
called variants of the Childs route. 

The Maritime Canal Company's route from 
the lake to Greytown, leaving the river at Ochoa 
and crossing the Eastern Divide is called the 
Menocal route. It has one variant. 

The route from the lake to the mouth of the 
San Carlos and then across the coimtry by way 
of Lake Silico is called the Lull route. There 
are four variants to this route. The one north 
of Lake Silico is called Variant I. The one 
through Lake Silico is called Variant II. The 
one south of Lake Silico is called Variant III, 
and the one passing through the Agua Dulce 
lagoon is called Variant IV. 

A number of different forms of construction 
have been considered. On the east side esti- 
mates have been made for different lock systems. 
Systems of 3, 5, 6, 7 and 8 locks with 1, 2 and 3 
dams in the river have been considered. On 
the west side systems of 3, 4, 5 and 6 locks have 
been considered. 

Unit prices have been derived as follows: 

The cost of excavating has been obtained by 
comparison with the Chicago Drainage Canal. 
Here the actual average cost was: for cubic yard 
of rock, 75 cents; for cubic yard of earth, 28 
cents, ilessrs. L. E. Cooley and Isham Ran- 
dolph have expressed their opinions that if the 
work should be repeated, it could be done for 65 
cents and 25 cents, respectively. These prices 
are, therefore, used as a basis of comparison. 

If the Nicaragua Canal were located near 
Chicago and its rock and earth excavation simi- 
lar in character to that of the Drainage Canal, 



then its rock and earth could be excavated for 
65 cents and 25 cents per cubic yard. Com- 
paring the material in the two localities: The 
earth in the Nicaragua Canal varies in character 
from soft rock to diluted silt. In the Chicago 
Canal, the range is equally as wide. It is be- 
lieved that the general average in the two lo- 
calities w^ould prove to be substantially the same. 
Therefore, it is assumed that, if the Nicaragua 
Canal were located near Chicago, the average 
cost of its earth excavation would be 25 cents 
I>er cubic yard. 

The rock between Lake Nicaragua and the 
Pacific is shale and sandstone, thinlv stratified 
and much broken. Some pits of considerable 
depth have been excavated without blasting; the 
rock has been used for macadamizing the roads. 
It is believed that a large part of this rock could 
be excavated with steam shovel without blast- 
ing. It is drilled slightly more easily than the 
Chicago limestone, and is much more brittle. 
The location of the spoil banks is not quite so 
favorable as in the Chicago works. These two 
opposite conditions have been taken as equal, it 
has, therefore, been assumed that it could be 
handled for the same price as the Chicago rock. 
Between Lake Nicaragua and the Caribbean sea 
the rock is basalt, dacite and sandstone. The 
sandstone is in such small quantities that it need 
not be considered. The basalt and dacite are 
both considerablv harder to drill and blast than 
the Chicago limestone but somewhat easier than 
granite. Again in the larger cuts the waste ma- 
terial will have to be transported horizontally 
three or four miles to the dumping ground. For 
these reasons it is estimated that the cost per 
yard will be increased 10 cents. Therefore, it 
is assumed that if the Nicaragua Canal were lo- 
cated near Chicago, the cost of excavating this 
rock would be 75 cents {x?r cubic yard on the 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



71 



east side and 65 cents per cubic yard on the 
west side. So far the data has been reasonably 
full and exact and the conclusions cannot be 
much in error. 

It yet remains to assign the relative cost of 
work in the United States and in Central Ameri- 
ca. This will involve greater uncertainty, for 
the reason, that there have been no large works 
in Central America with which comparison can 
be made, except the Panama Canal, and for 
many reasons it is believed that comparison with 
this work would be misleading. There has, 
however, been some railroad building in all of 
tlie Central American States, often in amounts 
sufficiently large so that the entire labor was 
brought to the country from the outside, thus 
making the conditions of labor somewhat similar 
to those which would obtain if the Nicaragua 
Canal should be built. An analysis of the cost 
of several of these roads has been obtained from 
engineers who built them. In one case a small 
amount of work under very unfavorable circum- 
stances cost about 100 per cent, more than it 
would in the United States. In other cases the 
difference was less than 50 per cent The range 
in results was quite wide but all fell between 
25 and 100 per cent in excess of similar work 
in the United States. 

From a consideration of all the data available 
the following ratios have been assigned: 

The rock on both sides and the earth on the 
west side will cost 50 per cent, more to exca- 
vate in Nicaragua than in the United States. 

In view of the excessive rainfall, the earth on 
the oast side would cost 75 per cent, more in 
!Xiearagua than in the United States. Apply- 
ing these ratios to the prices previously obtained, 
the unit cost of excavation is found to be as fol- 
low? : 



Rock on the east side $1.12 per cubic yd. 

Rock on the west side 07 " " ** 

Earth on the east side 44 '•' " " 

Earth on the west side 37 " " " 

The cost of the locks has been obtained by 
comparison with those at Sault Ste. Marie. The 
material estimated for is concrete walls, steel 
gates, wooden floors and conduits. The strength 
and dimensions of the parts necessary for the re- 
quired Nicaragua locks, were first determined 
by comparison with the locks at Sault Ste. Marie. 
The imit prices that have actually been paid at 
the Sault were then applied. Up to this point 
the data are quite full and the result is believed 
to be reasonably exact. The excess of cost in 
Nicaragua over that in the United States is more 
uncertain. It is assumed to be 33 per cent. It 
has been taken lower than that for excavation 
because a large part of lock construction is for 
material, some of which can be furnished in 
Nicaragua at only a slight advance over the 
price in the United States. These added per- 
centages of 75, 50 and 33 are believed to be 
large enough to cover all contingencies. There- 
fore, in the following estimates these unit prices 
have been reduced so that an item of 20 per 
cent, for contingencies can be added to the total. 
The two items of excavation and lock building 
amount to about 80 per cent, of the total cost 
These unit prices are, therefore, relatively very 
important. The remaining imit prices are de- 
termined from such information as could be ob- 
tained in Nicaragua and the United States. 
Some of the items are ver^' uncertain, but it is 
believed that the aggregate will prove to be 
reasonablv correct. 

The following are the imit prices used in all 
the estimates: 



72 



NICARAGUA CANAL COMMISSION 



Prices for the East Side. 

Earth excavation $ .37 per cu. yd. 

(Obtained by adding 60^ to 
Chicago price of 25^ per 
cii. yd.) 

Rock excavation 93 '' '' " 

(Obtained by adding 10^ to 
Chicago price of 65ff and 
then adding 24ji^ to the 
sura.) 

Rock in Greytown breakwater. 1.75 " ^* " 

Timber cribs 3.25 '' " " 

Clay puddle and back-filling, 
exclusive of cost of excava- 
tion 50 " " " 

Concrete in structures, other 

than locks 8.30 " '' " 

Concrete in locks 7.23 " *"• " 

Stone pitching, on embank- 
ments 2.00 " sq. yd. 

Timber in structures 60.00 " M.B.M. 

Clearing 75.00 " acre. 

Clearing and gnibbing 100.00 " " 

Prices for West Side. 

Earth excavation $ .31 per cu. yd. 

(Obtained by adding 24:^ to 

Chicago price of 25^ per 

cu. yd.) 
Rock excavation 81 " ** " 

(Obtained by adding 24j^ to 

Chicago price of 65^ per 

cu. yd.) 
Rock in Brito breakwater . . . 1.50 '' " " 

Timber cribs 3.00 '' '' " 

Clay puddle and back-filling, 

exclusive of cost of excava- 
tion 50 " *^ " 

Concrete in structures, other 

than locks 8.30 " " " 

Concrete in locks 7.23 " " '' 

Stone pitching 1.75 " sq. yd. 

Timber in structures 60.00 " M.B.'m. 

Clearing 75.00 " acre. 

Clearing and grubbing 100.00 " " 



The first estimate is for the Maritime Canal 
Company's proposed canal. 

The location is shown by the dotted lines on 
Map No. 2, and is exactly the location chosen 
by the Canal Company. The dimensions are 
those assigned by the Company. The more im- 
portant ones are as follows: 

Width of canal, in earth 80 to 120, in rock 
100, in river 125, in lake 125 to 275. Depth 
28 to 30. 

The number of locks is 6. The 3 on the east 
side have lifts of 31, 35 and 40 feet; and the 3 
on the west have lifts of 42.5, 42.5 and 30 feet; 
usable length C50 feet; width 80 feet 

The slopes in rock range between one hori- 
zontal to one vertical and one horizontal to five 
vertical; in earth between six horizontal to one 
vertical and three horizontal to one vertical. 

The total length of the canal from the 7-fath- 
om curve in the Caribbean sea to the 7-fathom 
curve in the Pacific ocean is 186.56 miles. 

Minimum elevation of lake surface 110 feet 
above mean sea level (Caribbean sea level). 

The estimate of cost is made up as follows: 

Estimate ox Menocal Route and Pl^vns. 

Eastern Division. 

Excavation earth, cu. yds. 45,731,- 

712, at 37ff $16,920,733 

Excavation rock, cu. yds. 9,278,803, 

at 93^ 8,629,287 

Embankment, Deseado basin 1,304,919 

Embankment, San Carlos ridge. . . 261,114 

Embankment, San Francisco ridge. 4,780,960 

Ochoa dam 1,875,071 

Three locks 5,154,760 

San Francisco and Deseado sluices. 1,947,484 

San Carios sluices 879,408 

Clearing and grubbing, acres 731.5, 

at $100 73,150 

Clearing, acres 1186, at $75 88,950 

Greytown breakwater, etc 1,273,295 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



73 



Stone pitching, sq. yds. 7680, at 

$1.67 $12,820 

Guard gate 171,708 

Railway, Greytown to Ochoa 1,604,200 

Telegraph, miles 72, $500 36,000 

$45,013,865 

Western Division. 

Childs Route. — ^Variant 11. 

Excavation earth, cu. yds. 0,928,- 

756, at 31^^ $ 3,077,914 

Excavation rock, cu. yds. 10,638,- 

010, at 81^ 8,616,788 

Three locks 4,751,897 

Wast^way 406,173 

Timber piers, cu. yds. 148,410, at 

$3.08 457,103 

Clearing and grubbing, acres 384, 

at $100 38,400 

Clearing, acres 417, at $75 31,275 

Railway and telegraph, 18 miles. . 909,000 

Right of way and bridges 160,000 

Jetties, cu. yds. 264,369, at $1.50. 396,554 
Stone pitching, sq. yds. 23,450, at 

$1.67 39,162 

La Flor dam 2,903,804 

Guard gates 153,416 

Wall at Lock ISTo. 4 241,405 

Western Division $22,182,891 

Western Division . . $22,182,891 

Eastern Division 45,013,865 

$67,196,756 
Sanitary and police. ' 1,000,000 
Lights and buoys . . . 500,000 

$68,696,756 
Superintendence and engineer- 
ing 4,121,805 

$72,818,561 
Contingencies 20;?^ 14,563,712 

Grand total $87,382,273 



It is believed that a canal of this kind if con- 
structed would be both inadequate and unstable. 
The following are some of the deficiencies that 
should be supplied in order to make it adequate 
to the present needs of commerce: the draft 
should be increased from 28 to 30 feet; the foun- 
dations of the San Francisco embankment 
should be carried, down to solid earth, 60 feet in 
some cases; the Ochoa dam should be built of 
masonry with its foundations on the rock; the 
width of the channel in the San Juan river 
should be increased to 300 feet; several cut-offs 
should be made; the minimum elevation of the 
surface of Lake Nicaragua should be reduced to 
104 feet above mean sea level so as to permit a 
fluctuation of 6 feet in the surface of the lake; 
the width of the canal for 10 miles on the west 
side should be increased to 200 feet, and 
waste-ways provided; the La Flor dam should be 
built of masonry with its foundations on the 
rock, or as an alternative, omitted entirely and 
a "low level" route substituted; the harbor at 
Brito should be modified. 

Menocal Route. — Variant L 

Under your instructions an estimate has been 
made with these modifications: This plan is 
called the Menocal route. Variant I. The route 
is shown on Map No. 2 and is on the east side, 
the same as the Canal Company's route, just 
considered, except some cut-offs in the San Juan 
river, which both shorten and cheapen it. On 
the west side the route is the same for the first 
10 miles from the lake. It then i)asses down 
the south of the valley of the Rio Grande and 
the La Flor dam is omitted. This route is some- 
what similar to the " low level " plan of the 
Canal Company. 

The dimensions are those assigned by the 
Commission for all routes. The j)rincipal ones 
are as follows: Depth of water in the canal and 



74 



NICARAGUA CANAL COMMISSION 



locks not less than 30 feet for all stages of sea, 
lake and ocean. Usable length of locks 620 
feet, width of locks, 80 feet Width of canal at 
bottom 100 feet in rock cuts; 150 feet between 
Greytown and East Divide and between Florida 
lagoon and Ochoa; 200 feet through the San 
Francisco and Florida lagoons; and 300 feet in 
the San Juan river with* greater widths at the 
bends. In Lake Nicaragua the width begins at 
300 feet and increases to 600 feet at the outer 
end. On the west side the width is 200 feet 
from the lake to the first lock, then 150 feet 
from there to the sea. The minimum elevation 
of the surface of Lake Nicaragua is fixed at 104 
feet and the maximum at 110 feet above sen 
level. The number of locks on the east side is 
3, with lifts of 36.8 feet each. On the west 
side there are locks with lifts of 19.3 feet 
each. 

The total length of the route between the 
7-fathom curves is 185.32 miles. The estimate 
of cost is made up as follows: 

Estimate. 

Caribbean Sea to Pacific Ocean. 

East Side. 

Menocal Eoute. — Variant I. 

Three locks. 

Small harbor at Greytown. 
Summit level base at elevation 74 (Caribbean 
datum). 

Excavation, earth 87,284,170 cu. 

yds. at 37ff $32,295,143 

Excavation, rock 10,157,152 cu. 

yds. at 93^ 9,446,151 

San Carlos embankment, dry exca- 
vation, earth 353,600 cu. yds. at 
37ff 130,832 

Ochoa dam and controlling works. . 6,666,700 

San Francisco embankment and 

dam 4,460,000 



Three locks, lift 36.82 feet at $2,- 

204, 630 6,613,900 

Guard gate 172,000 

Sluices and weirs, San Francisco 

and Deseado basins 1,506,000 

Clearing and grubbing, 1461 acres 

at $100 146,100 

Clearing 2460 acres at $75 184,500 

Greytown breakwater, stone 550,- 

000 cu. yds. at $1.75 962,500 

Timber work for cribs and retain- 
ing walls 1,000,000 

Stone pitching 100,000 

Railroad complete, Greytown to 

Toro rapids " 4,125,000 

Total, Eastern Division $67,808,826 

West Side. 

Childs Route. — Variant I. 

Six-lock system, with summit level 200 feet 
wide, remainder 150 feet. 

Small harbor at Brito. 

Excavation, earth 16,063,377 cu. 

yds. at 31^ $ 4,979,646 

Excavation, rock 22,625,710 cu. 

yds. at 81^ 18,326,825 

6 locks 19.33 feet lift at $1,601,250 9,607,500 

1 lock foundation in alluvium 125,000 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber pier west side lake, 151,000 

cu. yds. at $3.08 465,080 

Jetties Brito harbor, 144,107 cu. 

yds. at $1.50 216,160 

Clearing and grubbing, 661 acres at 

$100 66,100 

Clearing 1127 acres at $75 84,525 

Railroad complete 514,942 

Total Western Division $35,641,078 

Total Western Division. $35,641,078 
Total Eastern Division. 67,808,826 

$103,449,904 



APPENDIX I.— HEPORT OF THE CHIEF ENGINEER 



iO 



Sanitary and police. . 1,000,000 
Lights and buoys .... 500,000 

$104,949,904 
Superintendence and 
Engineering, Q^... 6,296,994 

$111,246,898 
Contingencies, 20^ . . 22,249,380 

Grand total $133,496,278 



Lull Routes. 
Lull Route. — Variant I. 

An estimate has been made of a route which 
follows the Lull route for a portion of its course. 
It has, therefore, been called a Variant of the 
Lull route. Its location is shown on Map No. 

2. Leaving Greytown harbor it passes north of 
Lake Silico across the delta plain and approaches 
the San Juan a few miles above the San Juan- 
illo. It then follows along the north side of the 
San Juan to the mouth of the San Carlos, above 
which it enters the river. From this point to 
the lake it follows the river with a few cut-offs 
which are shown on the map. On the west side 
the route is the same as Variant I of the Childs 
route, which has been previously defined. The 
dimensions are also the same except that the 
width from Greytown to the mouth of the San 
Carlos is 150 feet throughout. The number of 
locks on the east side is 6, with lifts of 18.4 feet. 

The number of dams in the San Juan river is 

3. The total length of the line between the 7- 
fathom curves in the Caribbean sea and the Pa- 
cific ocean is 189.08 miles. The estimate is 
made up as follows: 

East Side. 
Lull Route. — Variant I. 

Six-lock system with 3 dams in river (Boca 
San Carlos, Conchuda and Machuca) passing 



north of Lake Silico, includes small harbor at 
Greytown, lake dredging and curve widening on 
river section. Summit level base at elevation 
74 (Caribbean datum). 

Excavation, earth 106,441,923 cu. 

yds. at 37^ $39,383,511 

Excavation, rock 6,158,160 cu. yds. 

at 93^ . » 5,727,088 

Clearing, acres 4100 at $75 307,500 

Clearing and grubbing, acres 1575 

at $100 157,500 

Dam masonry, concrete 385,529 cu. 

yds. at $8.30 3,199,890 

Dam construction, not masonry. . . . 3,395,430 
Four locks, lift 18.4 feet, depth 

48.4 feet 6,406,400 

Two locks, lift 18.4 feet, depth 53.4 

feet 3,414,800 

Waste-weirs 450,300 

Sheet piling 1,059,800 feet B. M. 

at $60 63,588 

Breakwater 550,000 cu. yds. at 

$1.75 "^ 962,500 

Stone pitching, 120,000 sq. yds. at 

$2.00 240,000 

Guard gate 172,000 

Cribs, retaining wall 1,000,000 

Railroad, complete, Greytown to Sa- 

valos river \ 2,701,110 

Total Eastern Division $67,581,607 

West Side. 

Childs Route. — Variant I. 

Six-lock system with summit level 200 feet 
wide and remainder 150 feet. Small harbor at 
Brito. 

Excavation, earth 16,063,377 cu. 

yds. at SU $ 4,979,645 

Excavation, rock 22,625,710 cu. 

yds. at 81^ 18,326,825 

Six locks, 19.33 feet lift at $1,601,- 

250 9,607,500 



76 



NICARAGUA CANAL COMMISSION 



One lock foundation in alluvium. . 125,000 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber pier, west side of lake 151,- 

000 cu. yds. at $3.08 465,080 

Jetties, Brito harbor, 144,107 cu. 

yds., stone at $1.50 216,160 

Clearing and grubbing, 661 acres at 

$100 • 66,100 

Clearing 1127 acres at $75 84,525 

Railroad complete 514,942 

Total Western Division $35,641,078 

Total Western Division . $35,641,078 
Total Eastern Division . 67,581,617 

$103,222,695 
Sanitary and police. . 1,000,000 
Lights and buoys. . . . 500,000 

$104,722,695 
Superintendence and 

engineering, 6j^. . . 6,283,361 

$111,006,056 
Contingencies, 20j^ . . 22,201,211 

Grand total $133,207,267 

Estimates have been made of Variants I, II, 
III and IV of Lull route. These estimates 
have all started from a common point in the 
Sarapiqui ridge. The dimensions, number of 
locks, etc., are the same as for the preceding 
estimate. 

Lull Eoute. — Variant I. 

Estimate of quantities for a 6-lock system on 
the line passing north of Lake Silico between 
Greytown and Sarapiqui ridge. Length of line 
22.324 miles. 

Excavation, earth 23,406,600 cu. 

yds. at 37^ $ 8,660,442 



Excavation, rock 1,069,500 cu. yds. 

at 93ff 994,635 

Greytown breakwater, stone in 

place, 550,000 cu. yds. at $1.75. 962,500 

Eio Negro waste-weir, dry excava- 
tion, clay 410,000 cu. yds. at 37ff. 151,700 

Rio Negro waste-weir, masonry, 

2770 cu. yds. at $8.30 22,991 

Lock No. 1, waste-weir, dry excava- 
tion, clay 26,000 cu. yds. at 37ff . 9,620 

Lock No. 1, waste-weir, masonry, 

250 cu. yds. at $8.30 2,075 

Two locks 18.414 feet lift at $1,- 

577,000 3,154,000 

One lock 18.414 feet lift 1,675,400 

Stone pitching on embankment 

120,000 sq. yds. at $2 240,000 

Clearing, 1500 acres at $75 112,500 

Grubbing, 750 acres at $100 75,000 

Piers at Greytown harbor 5500 lin. 

ft. at $150 825,000 

Total $16,885,863 

Lull Route. — Variant 11. 

Estimate of quantities for a 6-lock system on 
the line through Lake Silico between Greytown 
and Sarapiqui ridge. Length of line 22.068 
miles. 

Excavation, earth 24,393,700 cu. 

yds. at 37^ $ 9,025,669 

Excavation, rock 1,368,700 cu. yds. 

at 93^ 1,272,801 

Greytown breakwater, stone in 

place, 550,000 cu. yds. at $1.75. 962,500 

Eio Negro waste-weir, dry excava- 
tion, clay 410,000 cu. yds. at 37^ 151,700 

Eio Negro waste-weir, masonry, 

2770 cu. yds. at $8.30 22,991 

Lock No. 1, waste- weir, dry excava- 
tion, clay 26,000 cu. yds. at 37^ . 9,020 

Lock No. 1, waste-weir, masonry, 

250 cu. yds. at $8.30 2,075 

Two locks, lift 18.414 feet at $1,- 

577,000 3,154,000 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



77 



186,600 

112,500 

75,000 



One lock, lift 18.414 feet 1,675,400 

Stone pitching on embankments, 

93,300 sq. yds. at $2 

Clearing, 1500 acres at $75 

Grubbing, 750 acres at $100 

Piers at Greytown harbor, 5500 lin. 

feet at $150 825,000 

Total .$17,475,946 

Lull Route. — Variant III. 

Estimate of quantities for a 6-lock system on 
the line south of Lake Silico from harbor head to 
Sarapiqui ridge. Length of line 24.02 miles. 

Excavation, earth 26,548,100 cu. 

yds. at 37ff $ 9,822,797 

Excavation, rock 1,231,800 cu. yds. 

at 93^ 1,145,574 

Harbor head breakwater, stone in 
place, 550,000 cu. yds. at $1.75 . . 

Rio Negro waste-weir, drj' excava- 
tion, clay 410,000 cu. yds. at 37^ 

Rio Nc.gro waste-weir, masonry, 
2770 cu. yds. at $8.30 

Lock No. 1, waste-weir, dry excava- 
tion, clay 26,000 cu. yds. at 37^ 

Lock No. 1, masonry 250 cu. yds. at 
$8.30 

Two locks, lift 18.414 feet at $1,- 

577,000 3,154,000 

One lock, lift 18.414 feet 1,675,400 

Stone pitching on embankment 
113,000 sq. yds. at $2 

Clearing, 1650 acres at $75 

Grubbing, 825 acres at $100 

Pier at harbor head, 5500 lin. feet 
at $150 



962,500 

151,700 

22,991 

9,620 

2,075 



226,000 

123,750 

82,500 



825,000 



Total $18,203,907 

Lull Route. — Variant IV. 

Estimate of quantities for a 6-lock system on 
the line from Agua Dulce along the lower San 
Juan river to Boca Colorado, then across swamp 
to Sarapiqui ridge. Length of line 24.53 miles. 



Excavation, earth 23,095,100 cu. 

yds. at 37^ 

Excavation, rock 570,000 cu. yds. 

at 93ff 

Agua Dulce breakwater, stone in 

place 550,000 cu. yds. at $1.75. . 
Rio Negro waste-weir, dry excava- 
tion, clay 410,000 cu. yds. at 37^, 
Rio Negro waste-weir, masonry, 

2770 cu. yds. at $8.30 

Three locks, lift 18.414 feet at $1,- 

675,400 

Stone pitching 194,900 sq. yds. at 

$2 .'^ 

Clearing, 1240 acres at $75 

Grubbing, 620 acres at $100 

Pier Agua Dulce, 5500 lin. feet at 

$150 



$ 8,545,187 

530,100 

962,500 

151,700 

22,991 

5,026,200 

389,800 
93,000 
62,000 

825,000 



Total $16,608,478 

If each of these partial routes be combined 
with the total estimate of the Lull Variant I, the 
following are obtained: 

Lull Route. — Variant I. 

Total cost of route north of Silico. $133,207,267 
Length 189.98 miles (see page 76). 

Lull Route. — Variant II. 

Through Silico $133,957,853 

Length 189.76 miles. 

Lull Route. — Variant III. 

South of Silico $134,883,819 

Length 191.75 miles. 

Lull Route. — Variant IV. 

Agua Dulce • $132,854,433 

Length 192.25 miles. 

The route through Agua Dulce is a little the 
cheapest of the four, but it is two miles longer 



78 



NICARAGUA CANAL COMMISSION 



and is rejected on that account. The route 
through Lake Silico is one-quarter of a mile 
shorter than the northern route, but costs a half 
a million more. It is therc^fore rejected. The 
route soutli of the lake is longer and more ex- 
pensive than the northern one, it is therefore re- 
jected and the northern one selected. The small 
difference in the cost of thej?e various routes 
shows that choice, so far as cost alone is con- 
cerned, is practically immaterial. The northern 
route has in addition some advantages over the 
others, for example, it can, without additional 
cost, be made to enter the sea near Tndio river. 
This may prove desirable. This completes the 
estimate of the proposed locations. 

Locks. 

So far, for the purposes of comparison, 6-lock 
svstems have been considered on botli the east 
and west sides. 

An attempt will now be made to determine 
the most desirable number of locks. Tlie east 
and west sides will be considered separately. 

In anv svstem of locks there are some advan- 
tages in having the dimensions of all the locks 
uniform. The lift for each lock in any system 
has been found by dividing the total lift by the 
number of locks in the system. The total lift 
on the east side from low water in the Caribbean 
sea to high water in Lake Nicaragua being 110.5 
feet, the lift of a single lock in a 5-lock system 
is 22.1 feet; in a 6-lock system 18.4 feet; in a 
7-lock system 15.8 feet; and in an 8-lock system 
13.8 feet. 

The number of dams in the San Juan river is 
also variable. Systems of 1, 2, and 3 dams have 
been considered. A single dam at the mouth of 
the San Carlos river would have a head of 55 
feet in ordinary stages of water. In a system of 
2 dams, each dam would have a head of 27.5 



feet and in a system of 3 dams that head would 
be 18.4 feet 

Estimates have been made of the cost of 5, 6, 
7 and 8-lock systems on the east side, and each 
one of these has been combined with systems of 
2 and 3 dams. The results are as follows: 

Estimates. 

« 

Lake Xicaragua to Caribbean Sea. 

Totals, various systems with one to three dams 
in river. Passing north of Lake Silico and in- 
cluding small harbor at (Ireytown, lake dredg- 
ing and curve widening on river section. Sum- 
mit level 74 (Caribbean datum). 

5-Lock System, 1 dam in river. . . .$65,852,817 
5-Lock System, 2 dams in river. . . 67,354,539 
5-Lock Svstem, 3 dams in river. . .Not feasible. 

6-Lock System, 1 dam in river $63,240,141 

6-I^ck System, 2 dams in river. . . 64,812,470 
6-Lock System, 3 dams in river. . . 67,581,610 

7-Lock System, 1 dam in river 62,669,099 

7-Lock System, 2 dams in river. . . 63,818,731 
7-Lock System, 3 dams in river. . . 67,411,672 

8-Lock System, 1 dam in river. . . . 66,829,093 
8-Lock System, 2 dams in river. . . 68,780,662 
8-Lock System, 3 dams in river. . . 71,157,210 

On the west side the total lift from low water 
in the Pacific ocean to high water in Lake Nica« 
ragua is 115.5 feet. 

In a system of 4 locks the lift for each lock 
would be 28.9 feet; 5 locks would be 23.1 feet, 
and 6 locks would be 19.3 feet. Estimate of 
cost of 4, 5 and 6-lock systems have been made 
and are as follows: 

West Side. 

Childs Eoute. — Variant I. 

Four-lock system with summit level 200 feet 
wide and remainder 150 feet. Small harbor at 
Brito. 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



79 



Excavation, earth 10,226,281 cii. 

yds. at 31^ 

Excavation, rock 23,099,488 cu. 

yds. at 81^ 

Four locks, 29 ft. lift at $1,853,1-45 

Guard gate 

Waste-weir 

Timber pier, west side of lake, 151,- 

000 cu. yds. at $3.08 

Jetties, Brito harbor, stone 144,107 

cu. vds. at $1.50 

Clearing and grubbing, acres 661 at 

$100 ... .! 

Clearing, acres 1127 at $75 

Railroad complete 



$ 5,030,147 

18,710,585 

7,412,580 

153,000 

1,102,300 

465,080 

216,160 

66,100 

84,525 

514,942 



Total AVesteni Division $33,755,419 



West Side. 

Cliilds Eoutc. — Variant I. 

Five-lock system with summit level 200 feet 
wide and remainder 150 feet. Small harbor at 
Brito. 

Excavation, earth 16,372,379 cu. 

yds. at 31ff $ 5,075,623 

Excavation, rock 22,923,053 cu. 

yds. at 81^ 18,567,673 

Five locks, 23.2 feet lift at $1,701,- 

900 8,509,500 

One lock foundation in alluvium. . 125,000 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber piers west side of lake 151,- 

000 en. yds at $3.08 465,080 

Jetties, Brito harbor, stone 144,107 

cu. yds. at $1.50 216,160 

Clearing and grubbing, acres 661 at 

$100 66,100 

Clearing, acres 1127 at $75 84,525 

Railroad complete 514,942 



West Side. 
Childs Route. — Variant I. 

Six-lock system with summit level 200 feet 
wide and remainder 150 feet. Small harbor at 
Brito. 

Excavation, earth 16,063,377 cu. 

yds. at 31^ $ 4,979,646 

Excavation, rock 22,625,710 cu. 

yds. at 81^ 18,326,825 

Six locks, 19.33 feet lift at $1,601,- 

250 9,607,500 

One lock foundation in alluvium . . 125,000 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber pier, west side of lake, 151,- 

000 cu. yds. at $3.08 

Jetties, Brito harbor, stone 144,107 

cu. vds. at $1.50 

Clearing and grubbing, acres 661 at 

$100 

Clearing, acres 1127 at $75 

Railroad 



465,080 
216,160 



66,100 

84,525 

514,942 



Total Western Division $34,879,903 



Total Western Division $35,641,078 

This completes the estimates. They are in- 
tended to include all the characteristic variants, 
both in location and construction. It yet re- 
mains to point out their relative merits and de- 
fects and to select the one which seems most de- 
sirable. 

The Menocal plan, as has been previously 
pointed out, is both inadequate and unstable. 
The variants of this plan, though adequate, are 
unsafe. For example, one feature of the plan 
is an artificial lake of nearly 100 square miles 
in area and 60 feet deep in places and retained 
by dams and earth embankments having a 
length of more than 10 miles. A single well- 
placed charge of dynamite might break through 
the crest, in which case the whole delta plain of 
the San Juan river would be inundated. There 



80 



NICARAGUA CANAL COMMISSION 



might be great loss of life and it is not probable 
that the canal could be used again in less than 
three years. 

It does not seem advisable to place such tre- 
mendous possibilities within easy reach of the 
malice of an enemy or the caprice of a madman. 

The plan of a single dam at the mouth of the 
San Carlos is open to the same objection, though 
in a much less degree. In this case an artificial 
lake is formed having an area of 48 square miles 
and a maximum depth of 55 feet, much land, 
both in Costa Rica and Nicaragua, that might 
become valuable, would be submerged. The 
cost, however, is about $5,000,000 less than for 
a system of 3 dams, and this might be deemed 
sufficient to govern. 

The plan of 3 dams in the river practically 
eliminates the danger from floods that might be 
caused by the failure of dams, because the pools 
of impoimded water are small in area and have 
a maximum depth of only 18 feet. If one of 
these should be suddenly discharged into the 
river it would cause a temporary rise of only a 
few feet. The maximum unit pressure on a 
system of 3 dams is only one-third as great as for 
a single dam. For these reasons a system of 3 
dams is preferred. 

With 3 dams in the river a system of 7 locks 
is slightly cheaper than any other, the difference 
between it and a G-lock system is only $170,000. 

The cost of operating a lock is estimated at 
$40,000 annually. This, if capitalized at 4 per 
cent, would add $1,000,000 to the first cost, 
which would make the 7-lock system more ex- 
pensive than the 6. 

The 6-lock svstem with 3 dams in the river, 
is therefore chosen for the east side. 

On the west side three systems of locks have 
been considered. Their relative costs are as fol- 
lows: 



4 Locks $33,755,000 

5 Locks 34,879,900 

6 Locks 35,641,000 

The 4-lock system is the cheapest of the three. 
The lift in each lock is 28.9 feet. This large 
lift is objectionable. Again its capacity for 
passing boats is 13 per cent, less than that of 
the 6-lock system on the east side. It, however, 
has the advantage of having rock foundations 
for all its lock sites. 

In order to make the systems comparable with 
each otTier, the capitalized cost of operating the 
additional locks should be included. If, then, 
we add to the 5-lock system $1,000,000, and to 
the 6-lock system $2,000,000, their cost can be 
compared with the 4-lock system. This leaves 
the 4-lock system decidedly the cheaper of the 
three. 

Since it is unlikely that any system of locks 
would be pushed to its full capacity during the 
first years of use and also since it is likely that 
a duplicate system of locks would soon be con- 
structed, the 4-lock system has been chosen for 
the present 

A canal with one dam in the river, 6 locks 
on the east side, 4 locks on the west side and 
small waste-way to the Pacific has been esti- 
mated for as follows: 

Estimate. 

Caribbean Sea to Pacific Ocean. 

6-Lock system east side. 4-Lock system west side. 

East Sede. 

Lull Route. — Variant I. 

Six-lock system, one dam in river (Boca San 
Carlos) passing north of Lake Silico, includes 
small harbor at Greytown, lake dredging and 
curve widening on river section. Summit level 
74 (Caribbean datum). 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



81 



Excavation, earth 102,099,463 cu. 

yds. at 37^ $37,776,801 

Excavation, rock 5,490,770 cu. yds. 

at 93ff \ . . 5,106,416 

Clearing and grubbing, acres 1575 

at $100 157,500 

Clearing, acres 4100 at $75 307,500 

Dam, concrete 4,570,340 

Six locks 9,560,400 

Waste-weirs 456,386 

Sheet piling 3,819,800 ft. B. M. at 

$60 229,188 

Breakwater 550,000 cu. yds. at 

$1.75 ' 962,500 

Stone pitching 120,000 sq. yds. at • 

$2 * 240,000 

Guard gate 172,000 

Pier Greytown 1,000,000 

"Railroad complete, Greytown to Rio 

Sahalos .' 2,701,110 

Total Eastern Division $63,240,141 

West Side. 

Childs Eoute. — Variant I. 

Four-lock system. 150 feet w^ide throughout. 
Small harbor at Brito. 

Earth excavation 15,500,530 cu. 

yds. at 31ff $ 4,805,164 

Rock excavation 18,081,334 cu. yds. 

at 81ff 14,645,881 

Four locks, 29 ft. lift, at $1,853,145 7,412,580 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber piers, west side of lake, 151,- 

000 cu. yds. at $3.08 465,080 

Jetties, Brito harbor, stone 144,107 

cu. yds. at $1.50 216,160 

Clearing and grubbing, acres 661 at 

$100 66,100 

Clearing, acres 1127 at $75 84,525 

Railroad complete 514,942 

$29,465,732 
6 



Total Western Division . . $29,465,732 
Total Eastern Division . . 63,240,141 



$92,705,873 

Sanitary and police 1,000,000 

Lights and buoys 500,000 



$94,205,873 
Superintendence and 

engineering, 6j^. . . . 5,652,352 



$99,858,225 
Contingencies, 20j^ ... 19,971,645 



$119,829,870 



This plan is the cheapest of any that has 
been considered, but it includes a high dam in 
the San Juan river and an insufficient waste-way 
on the west side, therefore, for reasons already 
given, it is not preferred. 

The preferred location and plan of construc- 
tion are then as follows: 

The route on the east side is shown on the 
map as *^ Lull Route, Variant L" It passes 
north of Lake Silico, enters the San Juan river 
above the mouth of the San Carlos, follows the 
river with some cut-offs to Lake jSTicaragua, 
crosses the lake to the mouth of the Lajas. On 
the west side it is shown as " Childs Route, Va- 
riant I." It passes up the valley of the Lajas, 
crosses the Continental Divide, enters the valley 
of the Rio Grande and follows down its southern 
side to Brito. 

Its construction contemplates harbors at Grey- 
town and Brito .with safe entrances, but small 
interior basins, 6 locks on the east side with 3 
dams in the San Juan river, 4 locks on the west 
side and waste-way to the Pacific with a mean 
capacity of 33,000 cubic feet per second. The 
proposed sites of harbors, locks, dams and waste- 
ways are shown on the map. 



82 



NICARAGUA CANAL COMMISSION 



It is neither the shortest route nor the cheap- 
est plan, but, for reasons given, it is preferred. 
Its estimated cost is as follows: 

Estimate. 

Caribbean Sea to Pacific Ocean. 

6-Lock system east side. 4-Lock system west side. 

Lull Route. — Variant I. 

Six-lock system with 3 dams in river (Boca 
San Carlos, Conchuda and Machuca) passing 
north of Lake Silico, includes small harbor at 
Greytown, lake dredging and cun-e widening on 
river sections. Summit level at elevation 74 
(Caribbean datum). 

Excavation, earth 106,441,923 cu. 

yds. at 37^ $39,383,511 

Excavation, rock 6,158,100 cu. yds. 

at 93^ 5,727,088 

Clearing, acres 4100 at $75 307,500 

Clearing and grubbing, acres 1575 

at $100 157,500 

Dam masonry, concrete, cu. yds. 

385,529 at $8.30 3,199,890 

Dam construction not masonry. . . . 3,395,430 
Four locks, lift 18.4 ft., depth 

48.4 ft 6,406,400 

Two locks, lift 18.4 ft., depth 53.4 

ft 3,414,800 

Waste-weirs 450,300 

Sheet piling, feet B. M. 1,059,800 

at $60 per M 63,588 

Breakwater, cu. yds. 550,000 at 

$1.75 962,500 

Stone pitching, sq. yds. 120,000 at 

$2 240,000 

Guard gate 172,000 

Cribs, retaining walls 1,000,000 

Railroad complete, Greytown to Sa- 

balos river 2,701,110 



West Side. 

Childs Koute. — Variant I. 

Four-loi.»k svstem with summit level 200 feet 
wide and remainder 150 feet. Small harbor at 
Brito. 

Excavation, earth 16,226,281 cu. 

yds. at 31^ $ 5,030,147 

Excavation, rock 23,099,488 cu. 

yds. at 81^ 18,710,585 

Four locks, 29 ft. lift at $1,853,145 7,412,580 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber pier, west side of lake 151,- 

000 cu. yd?, at $3.08 465,080 

Jetties, Brito harbor, stone 144,107 

cu. yds. at $1.50 216,160 

Clearing and grubbing, acres 661 at 

$100 66,100 

Clearing, acres 1127 at $75 84,525 

Railroad complete 514,942 



Total, Western Division $33,755,419 

Total Western Division. .$33,755,419 
Total Eastern Division . . 67,581,617 



$101,337,036 
Sanitary and police. . 1,000,000 
Lights and buoys. . . . 500,000 



$102,837,036 
Superintendence and 

engineering add 6^ 6,170,222 



$109,007,258 
Contingencies add 20^ 21,801,451 



Total Eastern Division $67,581,607 



Grand total $130,808,700 

There are some additional conditions bearing 
upon the cost and order of construction that may 
be considered here. 

The assumed dimensions of the canal are 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



83 



larger in tlie aggregate than any hitherto pro- 
posed. They are supposed to be sufficient for 
the growing needs of commerce for a term of 
years, perhaps 20. It is known that large 
canals, such as St. Mary's Falls, Manchester and 
Suez, had comparatively little business during 
the first years of their \ise. It is safe to assume 
that if the Nicaragua Canal should be built, its 
business would be relatively small at first, and 
that if adequate to do the business for 20 years 
it would at first have a capacity largely in excess 
of its needs. It is possible, and even probable, 
that a canal 100 feet wide in earth and rock 
cuts, and 150 feet wide in the river, with suit- 
able passing places would do all the business 
that came to it for the first few years. The 
widening of the channel could be done when 
the needs of commerce demanded it and at no 
greater cost than if done at first Wooden locks 
could be used at first; there is even a possibility 
that thov would be better in the end than 
masonr\' locks. They would certainly answer 
for the first set, until duplicate ones were neces- 
sary. An estimate has, therefore, been made of 
a canal with nan*ow channels and wooden locks. 
The estimated cost is as follows: 

Estimate. 

Caribbean Sea to Pacific Ocean. 

6-Lock system east side. 4-Lock system west side. 

East Side. 

Lull Eoute. — ^Variant I. 

Six-lock system (timber) 3 dams in river (Low- 
er [Machuca, Conchuda and Boca San Carlos) 
passing north of Lake Silico, including small 
harbor at Greytown and lake dredging. Kivcr 
section 150 feet wide, balance of canal 100 feet. 
Summit level 74 CCaribbean datum). 



Excavation, earth 78,251,986 cu. 

yds. at 37^ $28,953,234 

Excavation, rock 4,573,027 cu. yds. 

at 93^ 4,252,914 

Clearing, acres 4100 at $75 307,500 

Clearing and grubbing, acres 1575 

at $100 157,500 

Dam, masonry (concrete) 385,529 

cu. yds. at $8.30 3,199,890 

Dam construction other than ma- 
sonry 3,395,430 

Two locks, depth 53.4 ft., lift 18.4 

ft 2,000,000 

Four locks, depth 48.4 ft., lift 18.4 

ft 3,818,824 

Waste-weirs 450,280 

Sheet piKng, ft. B. M. 1,059,800 at 

$60 per M 63,588 

Breakwater, 550,000 cu. yds. at 

$1.75 962,500 

Stone pitching, 120,000 sq. yds. at 

$2 240,000 

Guard gate 172,000 

Piers, Greytown 1,000,000 

Railroad, Greyto^vn to Rio Sabalos 2,701,110 

Total, Eastern Division $51,674,776 

West Side. 

Childs Route. — Variant I. 

Four-lock system (timber) summit level 200 
feet wide. Remainder of canal 100 feet wide, 
except at passing points which are 150 feet wide. 
Small harbor at Brito. 

Excavation, earth 14,966,500 cu. 

yds. at 31^ $ 4,639,615 

Excavation, rock 21,310,967 cu. 

yds. at 81^ .' 17,261,883 

Four locks, lift 29 ft. at $1,220,000 4,880,000 

Lock foundation in alluvium 125,000 

Guard gate 153,000 

Waste-weirs 1,102,300 

Timber pier, west side lake 151,000 

cu. yds. at $3.08 465,080 



84 



NICARAGUA CANAL COMMISSION 



Jetties, Brito harbor, stone 144,107 

cu. yds. at $1.50 216,160 

Clearing and grubbing, acres 661 

at $100 66,100 

Clearing, acres 1127 at $75 84,525 

Kailroad 514,942 

Total Western Division $29,508,605 

Total Eastern Division . .$51,674,778 
Total Western Division. . 29,508,605 

$81,183,383 
Sanitary and police. . . 1,000,000 
Lights and buoys 500,000 

$82,683,383 
Superintendence and 

engineering, 6ji ... 4,961,003 

$87,644,386 
Contingencies, 20j^ ... 17,528,877 

Grand total $105,173,263 

This estimate has been made without any 
change of location or plan. The only dimen- 
sion that has been changed is the width of the 
canal. The material in the locks has been 
changed from concrete to wood. 

It is thus possible to so arrange the order of 
construction that the use of the canal can be- 
gin when an expenditure of $105,000,000 has 
been made. The remaining $25,000,000 of ex- 
penditure need not be made until commerce de- 
mands it. This order of construction should, in 
my opinion, be followed. 

In preparing this report all available data have 
been used; its weight upon different points is va- 
riable, and an attempt has been made to point 
this out in the body of the report. It will be 
given again here in compact form, so that the 
relative "weight and value of the various conclu- 
sions may be fully understood. 



First the field work is all of good quality, 
there are no weak or doubtful parts; as far as it 
professes to go, it is entirely trustworthy. The 
many difficulties in the way of doing the field 
work served only to retard its accomplishment, 
but did not in any way lower its quality. In 
amount it is sufficient for preliminarj" estimates. 
It is not and was not intended to be minute 
enough for the preparation of specifications and 
final exact locations. The computation of quan- 
tities has been made and checked with the care 
usual in such work, and the totals are entirely 
trustworthy. The relative amounts of earth and 
rock have been derived from a line of borings 
along the proposed line of the canal. These 
borings in important places ai*e usually not more 
than three thousand feet apart. It is believed 
that the relative amounts as given will not prove 
to be much in error. The unit prices for exca- 
vation and locks have been obtained by compar- 
ison with the known cost of the Chicago Drain- 
age Canal and the locks in the St. ^Mary's Falls 
Canal. 

Up to this point there can be no large error, 
at least no larger than would enter into the esti- 
mates for a second drainage canal near Chicago 
or an additional lock at Sault Ste. Marie. 

The next step is to assign the difference be- 
tween the cost of work done in the United 
States and similar work done in Nicaragua. In 
this, there is a large amount of uncertainty. 
The Panama Canal is the onlv similar work in 
this region. For obvious I'easons it cannot be 
used for comparison. Again, comparison with 
work in Central America done bv native labor 
would bo misleading, for this is sometimes al> 
normally cheap. Comparisons have been made 
with such works as are large enough to require 
imported labor. The results are not accordant, 
but the following limits seem reasonably certain. 



APPENDIX I.— REPORT OF THE CHIEF ENGINEER 



85 



The excess of cost in Central America would not 
be less than twenty-five per cent, and would not 
be greater than one hundred per cent These 
are wide limits, but the information at present 
available does not seem to me sufficient to make 
them any smaller. I have assigned different 
percentages to different parts of the work for 
reasons given. In the aggregate it is assumed 
that the work in Mcaragua will cost about sixty 
per cent, more than similar work in the United 
States. This is but little more than an opinion, 
which may be changed at any time upon better 
information. 

These estimates have been made for the con- 
ditions deemed most likely to occur; unlikely 
conditions, though possible, have not been con- 
sidered: for example, an exceptionally healthy 
period, or a period in which the prices of labor 



and material were below the average, has not 
been assumed ; these would tend to make the cost 
of the work less. On the other hand a corrupt 
administration or a season of pestilence would 
make the cost of the work more, but these possi- 
bilities are remote and have not been considered. 

The estimates are intended to be the most 
probable, that is, they are equally likely to be 
small or large. 

I have the honor to transmit herewith, the 
special reports of Assistant Engineers, C. W. 
Hayes, A. P. Davis, J. W. G. Walker, F. L. 
Stuart, H. H. Trundle, Boyd Ehle, S. S. Evans, 
Stephen Harris, Andrew Onderdonk, and L. 
Hankins. 

Very respectfully, 

E. S. Wheelee, 
Chief Engineer, Nicaragua Canal Commission. 



APPENDIX 11 



REPORT 



ON THE 



GEOLOGY AND PHYSIOGRAPHY 



OF THE 



NICARAGUA CANAL ROUTE 



BY 

CHARLES WILLARD HAYES 

Geologist, U. S. Geological Survey. 



CONTENTS 

Letter of Transmittal. 

PAGB 

Personnel of the Party 93 

Drilling Operations 93 

General Geologic Work 94 

Scope of the Report 94 

PART 1 

PHYSIOGRAPHY AND GEOLOGY OF THE CANAL REGION. 

Topography. 

The Nicaraguan Depression 95 

Classification of Topographic Features 95 

The Alluvial Plains 97 

The Dissected Peneplain 100 

The Residual Hills 105 

The Western Divide 106 

Regions Adjacent to the Nicaraguan Depression 107 

The Lake— Caribbean Divide 107 

Volcanic Mountain Ranges 108 

Volcanic Plateaus 110 

Climate. 

9 

Amount and Distribution of Rainfall Ill 

Physiographic Effects 112 

Eastern Division 112 

Western Division 113 

Rock Formations. 

Conditions for Study 114 

Classification of the Rocks 114 

Brito Formation 114 

Distribution 114 



90 NICARAGUA CANAL COMMISSION 

PAGE 

Lithologic Character 114 

Structure 115 

, Utilization 117 

Age of the Foiination 117 

Machuca Formation 117 

Distribution ■. 117 

Lithologic Character 118 

Structure 118 

Utilization 118 

Age of the Formation 119 

Tertiary Igneous Rocks 119 

Massive Igneous Rocks 120 

Fragmental Igneous Rocks 121 

Recent Alluvial Formations 122 

Recent Volcanic Rocks 123 

Rock Decay. 

Importance of the Subject 124 

Conditions Favoring Rock Decay 125 

Effect of Chemical Composition 125 

Effect of Original Structure 126 

Effect of Secondary Structures 127 

Rock Decay in the Eastern Division 127 

Products of Rock Decay 128 

Red Clav 128 

Blue Clay 129 

Soft rock (saprolite) 129 

Rock Decay in the Western Division 130 

Earthquakes. 

Relation of the Canal Route to Centers of Volcanic Activity 132 

Considerations Affecting Earthquake Forecasts 133 

Seismic records in the Canal Region 136 

Recent Gdologic History. 

Conditions Anterior to Tertiary Time 138 

Early Tertiary Deposition and Volcanic Activity 138 

Middle Tertiary Uplift and Erosion 139 

Post-Tertiary Elevation and Gorge Cutting 140 



APPENDIX II.— GEOLOGIC REPORT 9][ 

PAGE 

Recent Depression and AUuviation 143 

Formation of Lake Nicaragua 144 

Subsequent Modification of the Lake 146 

Physiography of the San Juan Valley. 

Physiographic Subdivisions of the River and Valley 148 

The Upper Division 149 

The Middle Division 149 

The Lower Division 151 



PART II 

APPLICATION OF GEOLOGIC FACTS TO ENGINEERING PROBLEMS. 

Classification of !&La.teeials. 

Alluvium 153 

Residual Clay 155 

Soft Rock 155 

Hard Rock 158 

Factoes Determining Relative Cost of Excavating Hard Rock, 160 

Character of Data on which Geologic Sections are Based. 

Boring Operations 161 

Surface Examinations 161 

Records of Canal Company's Borings 162 

Geologic Details. 

Western Division 162 

La Flor Dam Site 162 

Rio Grande Dam Site 163 

Brito 164 

Excavation Lines, Lake Nicaragua to Pacific Ocean 165 

Dam Sites on the Rio San Juan 167 

Castaio 167 

Upper Machuca 167 

Machuca 167 

Conchuda 168 

Boca San Carlos 169 

Ochoa 169 



92 NICARAGUA CANAL COMMISSION 

PAQB 

I^wer Ochoa 170 

Tambor Grande 171 

Embankment Lines 171 

San Carlos 171 

San Francisco 172 

Tamborcito Point 172 

Tamborcito Lagoon 173 

Excavation Lines, Eastern Division 173 

Eiver Section (Lull Route), Lake Nicaragua to Boca San Carlos 173 

Menocal Route 175 

Variants of the Lull Route 177 

Additional Geologic Work Required for Final Location. 

On Excavation Lines 182 

On Foundations 183 



PART 111 

MICROSCOPIC PETROGRAPHY OF THE ROCKS FROM THE NICARAGUA 

CANAL REGION. 

By F. LESLIE RANSOME 

Asst. Geologist, U. S. G. S. 



APPENDIX II 



Mr. E. S. Wheeler, Chief Engineer, Nica- 
ragua Canal Commission, Washington, 
D. C. 

Sir: — I have the honor to submit herewith a 
report of my work for the Nicaragua Canal 
Commission, carried on under your direction. 
In accordance with your letter of instructions, 
dated December 21, 1897, received at Grey- 
town, Nicaragua, I assumed immediate charge 
of the geological party. The \york of that 
party included drilling operations as well as a 
generaUgeologic and physiographic study of the 
region adjacent to the route of the proposed 
canal. 

Personnel of the Party. — The following 
men were assigned to the party under my charge: 
Ignatius O'Reardon, as general assistant; Harry 
Spence and Patrick Tierney, as chief drillers; 
T. J. II. Archambault, Moriz Bernstein, W. E. 
Herbert, E. F. Fischer, and E. P. Humphrey, as 
drillers. Mr. Humphrey was detached from 
the party and ordered to report to Assistant En- 
gineer Walker on the 15th of Febniary, 1898. 
On the 13th of August George H. Seymour was 
added to the party, and on September 1, W. A. 
Smith and A. H. Miller. With the exception 
stated above, these men remained with the party 
continuously until the completion of the work, 
when they were ordered to report to the Com- 
mis>iion at Washington and there discharged. 
Mr. O'Reardon has continued as mv assistant in 
the office. 



Drilling Operations. — Drilling operations 
were begun at Ochoa early in January, 1898. 
Work was continued at this point and on the 
San Francisco embankment until early in March. 
The party was then divided; one party, consist- 
ing of Messrs. Tierney, Bernstein and Archam- 
bault, being sent to the west side, and another, 
consisting of Messrs. Spence, Herbert and 
Fischer, beginning work on the upper San Juan 
river. The work on the west side was done under 
my immediate direction, while Mr. O'Reardon 
was left with the river party to make locations 
and to keep the records. He was later placed 
in charge of the party. The work on the west 
side was completed on July 13, and the party 
was moved back to the east side and began work 
on the various proposed dam sites on the river. 
This work was completed about ibjd middle of 
September, and the work by the river party was 
completed on the 23d of that month. Messrs. 
O'Reardon, Spence and Archambault were then 
ordered to report at headquarters in Washington, 
and a single party was started at work on the 
Eastern Divide. This consisted of Mr. Tier- 
ney, in charge, with Messrs. Bernstein, Fischer, 
Herbert, Seymour, Smith and Miller. The 
Eastern Divide work was completed early in 
November, and the boring outfit was stored in 
Greytown, and all members of the party re- 
turned to Washington except Bernstein and 
Seymour, who remained at Greytown subject 
to your orders. Early in December it was de- 



94 



NICARAGUA CANAL COMMISSION 



cided to have some additional work done on the 
site of the proposed dam at Boca San Carlos, 
and this was placed in charge of Mr. Bernstein. 
He began work early in January, 1899, &nd 
completed it in about a month. 

General Geologic Woek. — From the date 
of receiving your letter of instructions until 
my return to Washington at the end of Septem- 
ber, the greater part of my time was devoted 
to the personal direction of the boring parties. 
In connection with this, I was able to make a 
somewhat detailed examination of the surface 
geology in the region adjacent to the canal 
route. It was found, however, that from the 
nature of the country, and especially by reason 
of the luxuriant vegetation and the depth of 
rock decay, conclusions derived from a study of 
the natural rock outcrops were unsatisfactory, 
and most of the exact data obtained was by 
means of the drilling operations. Observations 
were made on the physiography of the region, 
which not onlv have considerable scientific in- 
terest, but are believed to have a very direct 
bearing upon the practical engineering prob- 
lems connected with the construction of the 
canal. Some examination was made of regions 
at some distance from the canal route, though 
less of this was done than desired, and a much 
further exploration of this portion of the isth- 
mian region might be made with distinct advan- 
tage to the solution of problems connected with 
the canal. In connection with iir. Davis a 
nearly complete circuit of the lake was made and 
the geology of its shores examined. The region 
to the northwest of Lakes Nicaragua and Man- 
agua was studied with special reference to the 



origin of those lakes, and also with reference 
to the practicability of constructing a waste- 
way from the lake westward to the Pacific. 

Scope of the Report. — The accompanying 
report consists of two parts. The first is in the 
main theoretical. It embraces some account of 
the topography of the region, the climatic con- 
ditions in their relation to physiographic pro- 
cesses now going on, a description of the vari- 
ous rock formations, a consideration of the seis- 
mic phenomena of the region, and the proba- 
bility of the occurrence of earthquakes and 
finally a brief outline of the recent geologic his- 
tory of the region. The second part is a more di- 
rect practical application of the facts of geology 
to the engineering problems. In this the classi- 
fication of materials is discussed and a somewhat 
fuller description of the rock formations and 
their mode of weathering is given, and second, 
the various localities at which it is intended to 
erect structures, such as dams, weirs and locks, 
are described; also the various lines in excavation 
and the various embankment lines. Xot the 
least important feature of this portion of the 
report is the discrimination between that which 
is actually known concerning the geological con- 
ditions prevailing at various points and that 

which is inferred. This naturallv leads to the 

t' 

final section of the report, in which the addi- 
tional work needed before final plans can be 
made, is pointed out in some detail. 

Very respectfully submitted, 

C. WiLLARD Hayes, 

Geologist, U. S. G. S. 

April 12, 1899. 



APPENDIX II.— GEOLOGIC REPORT 



95 



PART I 

PHYSIOGRAPHY AND GEOLOGY OF THE 

CANAL REGION 



TOPOGRAPHY. 



The Nicaraguan Depression. — The region 
whose topography has a direct bearing upon the 
problem of the Nicaragua Canal embraces north- 
ern Costa Kiea and southern Nicaragua. It is 
sharply limited on the south by the high vol- 
canic range of Costa Rica which rears its mas- 
sive form dia<ronallv across the isthmus. It is 
less definitely limited on the north by the in- 
creasing height of a deeply dissected plateau- 
which merges with the high mountains of north- 
ern Nicaragua. Between these limits lies a 
broad irregular depression which extends very 
nearly across the isthmus in a diagonal direction 
parallel with the Costa Rican range. This de- 
pression is now occupied chiefly by Atlantic 
drainage, the Continental Divide lying within a 
short distance of the Pacific. It contains the 
basins of Lakes Nicaragua and ^Managua and 
their outlet, the San Juan river, the latter occu- 
pying a position toward its northern margin. It 
is important to note at the outset that the de- 
pression is not a simple river valley. The por- 
tion with which we are chieflv concerned, that 
lying between the lake and the Caribbean, em- 
braces two distinct drainage basins whose 
streams formerly flowed in opposite directions, 
although by a geologically recent reversal of 
the drainage they now have a single outlet to 
the sea. 



Classification of TopooRArnic Features. — 
When examined in detail the surface of the 
Nicaraguan depression presents considerable 
relief and its topographic features naturally 
group themselves in three classes. 

Extending from the base of the Costa Rican 
volcanoes northward to the San Juan river and 
beyond are many hills whose summits reach to 
a tolerablv uniform elevation on north and south 
lines but increase in height from either side of 
the isthmus toward its axis. In the vicinity of 
the larger streams as the San Juan and San 
Carlos these hills have steep slopes and rounded 
summits. Farther back from the streams the 
valleys which separate them are narrower and 
there are considerable areas of level or undu- 
lating surface at an altitude corresponding with 
the hill tops near the streams. It is evident that 
if the valleys were filled even with the summits 
of these hills there would be formed a broad 
undulating plain, sloping gradually up from 
either side toward the axis of the isthmus. It 
is entirely probable that such a plain once ex- 
isted and that it has been converted into a series 
of even-topped hills and ridges by the cutting 
of stream channels below its surface. The man- 
ner in which this plain was originally formed 
is manifestly by the long-continued action of 
streams when the land stood considerably lower 



96 



NICARAGUA CANAL COMMISSION 



than now, that is, by the process of stream degra- 
dation or base leveling. It was, therefore, a 
gradational and not a constructional plain. If 
it were reconstructed by the filling of the stream 
valleys its present altitude would vary between 
100 and 200 feet. 

As indicated above, numerous valleys now in- 
tersect the surface of this old plain. They vary 
with the size of the streams except in the case of 
the San Juan. The reasons for this exception 
will be pointed out later. They are broadest 
near the large streams where the old plain is 
nearly or quite destroyed and grow narrower 
with increasing distance from the main drainage 
lines. The smaller streams generally head in 
narrow gorges, but in some cases they have not 
completely dissected the old plain, flowing upon 
its surface in shallow vallevs which lower down 
give way to narrow gorges and these in turn to 
the rather ^vide alluvial valleys near the trunk 
stream. The greater part of the erosion which 
has dissected the surface of the old plain was 
accomplished when the latter stood much higher 
than at present. The valleys were then much 
deeper, and none had extensive flood-plains ex- 
cept perhaps the largest streams near the sea. A 
recent change in the altitude of the land has 
brought the valleys below sea level, changing 
the rivers, at least in their lower portions, from 
corrading to aggrading streams. They have 
since silted up the estuaries thus formed, pro- 
ducing the wide alluvial plains through which 
they now meander. 

Corresponding in some degree w4th the valleys 
incised within the old plain are eminences ris- 
ing distinctly above its surface. These are re- 
sidual hills which bv reason of the harder rocks 
of which they are composed, or their position 
on the divides, far from the main drainage lines, 
were never reduced to the level of the plain. 



Where the plain was best developed, that is near 
the sea margin on either side, these residual hills 
are infrequent and inconspicuous. Thus to the 
southward of the San Juan, in the region lying 
between the Sarapiqui and the San (.^arlos, there 
is an extensive area in which the hills are almost 
wholly remnants of the dissected plain, their 
summits in general presenting little variation 
in altitude. To the northward of the San Juan 
the residual hills occur with increasing fre- 
quency and greater altitude, and finally merge 
with the mountains of northern Nicaragua. 
It is only where the old plain is somewhat well 
presented that the true character of the residual 
hills is clearly seen. At certain points along 
the San Juan they rise directly from the river 
valley, all remnants of the intermediate plain 
having been destroyed. The residual hills also 
increase in number and height from either side 
of the isthmus toward its center, being most 
abundant along a line which crosses the San 
Juan valley in the vicinity of Castillo. If the 
plain were reconstructed by the filling of the 
vallevs it would not be continuous but would 
pass from one side of the isthmus to the other 
through comparatively low gaps between the 
residual hills. 

Summing up the above statements very 
briefly, then, it appears that we have in this 
region a broadly undulating plain formed by the 
erosion of streams flowing to the Pacific and to 
the Atlantic from low gaps at the Divide. 
Above this plain are residual hills, most abundant 
at the axis of the isthmus where the Continental 
Divide was formerly located, but increasing 
toward the north where they merge with the 
mountains of northern J^icaragua; and, finally, 
there are many valleys cut in the surface of the 
plain by the erosion of the streams after the 
region had been lifted to a higher altitude, 



APPENDIX II.— GEOLOGIC REPORT 



97 



The lower portions of these valleys have sub- 
sequently been drowned and silted up, with the 
formation of broad alluvial flood-plains. 

With these fundamental eonceptioms clearly 
in mind the topographic features of the Nica- 
raguan depression may be taken up and de- 
scribed more in detail. They will be considered 
in the reverse order, that is, the youngest of the 
topographic forms will be considered first and 
the successively older ones later. 

Alluvial Plains. — Since the river valleys are 
in general closely followed by canal routes the 
alluvial flood-plains become of prime importance 
in planning any canal. They should be con- 
sidered not alone with reference to their present 
form and composition, but also, in this region at 
least, with reference to their origin and the topo- 
graphic forms which they cover and conceal. 

The coastal plain on the Atlantic side of the 
isthmus increases from a mere fringe at the 
base of the mountains in Costa Eica northward 
to a belt from 10 to 15 miles wide in the 
vicinity of Greytown. This portion of it is 
formed chiefly from materials brought down by 
the rivers heading in the Costa Eican volcanoes; 
it is, in fact, a series of coalescing deltas of 
which the largest is that formed by the San 
Juan. The sediment brought down to the sea 
by streams north of the San Juan is very small 
compared with that brought down by those to 
the south. The more rapidly growing southern 
deltas would, therefore, be extended seaward 
except for a strong northward littoral sand cur- 
rent set up by the oblique direction at which the 
prevailing winds strike the shore. The true litr 
toral current in this portion of the Caribbean is 
to the southward, but its capacity for transport- 
ing sediment is more than neutralized by the 
active northward sand drift within the zone of 
surf action. This sand drift tends to distribute 
7 



the sediment evenly along the coast and preserve 
gently curving coast lines. Notwithstanding 
this tendency the San Juan delta has been built 
out a short distance into the Caribbean forming 
a shallow embayment to the northward of Har- 
bor Head. 

The level surface of the delta plain is inter- 
rupted by numerous low rounded hills com- 
posed of residual clay derived from the decay 
of rock in situ, and differing decidedly in ap- 
pearance and composition from the surrounding 
alluvium. These hills have the form and ap- 
pearance of islands rising above the level delta 
plain, and it is quite probable that they were at 
one time islands fringing the shore before the 
alluvial deposits extended out to them and con- 
nected them with the mainland. 

The inner margin of the delta plain is ex- 
tremely irregular. The isolated hills increase 
in number and size and finally merge with the 
dissected interior highland while the delta plain 
itself merges with the broad flood-plains of the 
streams. 

The surface of the delta plain in its seaward 
portion is but a few feet above tide level. Its 
extreme outer margin is marked by low ridges 
parallel with the shore, formed by the sand 
thrown up during exceptional storms. From 
the shore margin the surface of the plain ascends 
towards the interior at a fairly uniform rate of 
about 18 inches to the mile. 

The surface of the delta plain is also diver- 
sified by numerous small lakes and lagoons. 
These are produced chiefly in two ways: (1) by 
the formation of sand spits and, (2) by unequal 
sedimentation. 

Sediment is delivered by the larger streams 
slightly faster than it can be distributed by the 
littoral current. Hence it tends to build out a 
delta, but this is deflected in the direction of 



98 



NICARAGUA CANAL COMMISSION 



the current and forms a curved sand spit which 
for a time makes a well-sheltered harbor. As 
the sand spit continues to pn'ow, however, its 
point eventually joins the mainland and the 
harbor is converted into a chased lagoon. This 
complete cycle of changes has taken place at 
Greytown during the last century and a half. 
The cycle has also been repeated at the same 
point several times ])revi()us to the last, giving 
rise to the Shei)ard, Sucio, Barca and Ibo bgoons 
which occur back of and parallel with the one 
last formed. (See Plate I.) 

Agua Dulce and Parada lagoons doubtless owe 
their origin to the same process. The mouth of 
the stream emptying into the lagoon is for a 
time candied forward in the direction of the 
littoral current, but when this has gone to a 
certain point, the river seeks a more <lirect 
course to the sea, breaking through the barrier 
as the Colorado has evidently done verv recently 
while the deserted outlet is quickly obliterated. 
The lagoons are thus arranged in parallel series 
on that side of the stream toward which the lit- 
toral current sets. The position of the Agua 
Dulce and Parada lagoons with reference to the 
Colorado river therefore proves conclusively 
that the northward sand current observed oppo- 
site Greytown originates to the southward, at 
least beyond the Colorado. 

The second method by which lagoons are 
formed on the delta plain is by unequal sedi- 
mentation. As the coast was built outward bv 
additions to its outer margin it advanced past 
numerous islands which had fringed the shore. 
These in some cases prevented the uniform 
deposition of sediment by interrupting the lit- 
toral sand stream and the areas in which little 
or no deposition took pjace subsequently formed 
lakes. Perhaps the best example of a lake 
formed in this manner is Lake Silico. This oc- 



cupies what was evidently at one time a bay 
sheltered bv the Silico hills which then formed 
a group of islands. As the delta plain was 
built outi?onnecting these islands with the main- 
land the sheltered bav was not filled bv sediment, 
but its opening was cut oil and a lake thus 
formed. 

Another class of lakes or lagoons formed by 
unequal sedimentation is found about the mar- 
gins of the delta plain and of the river flood- 
plains. The rivers which head upon the Costa 
Pican volcanoes carrv a much more abundant 
sup])ly of sediment than the smaller streams 
which flow from a region compos(»d of compact 
residual clays protected by a heavy mantle of 
vegetation. Hence the flood-plains of the San 
Juan, below the confluence with the San Carlos, 
are built up more rapidly than those of its tribu- 
taries. The latter are therefore dammed and 
form lagoons in their upper basins. The 
Florida lagoon is a typical example of this class. 
Since they occupy drowned stream basins in a 
region wdiich originally had considerable relief, 
their outlines are very irregular, the water back- 
ing up all the minor tributari(»s of the basin. In 
some cases, as in the Taud)orcito region, the 
water surface has been raised above the gaps be- 
tween neighboring streams and their basins are 
now confluent while the residual land rising 
above the lagoon level forms isolated groups of 
hills. 

The lagoons of the delta plain formed in these 
various ways are at first open lakes, but they 
gradually become choked by vegetation and filled 
wuth fine silt so that thev are converted into 
grassy marshes and finally when the silt be- 
comes sufficiently consolidated to form a stable 
support the forest trees encroach upon the 
marsh and all trace of the lagoon is lost. Num- 
erous examples occur in the delta plains, illus- 



NICARAGUA CANAL COMMI88IDN. 


APPENDIX 2, 


PLATE 1. 




r r 

-57 


jat 


- ~-~^ -<- 






'.- >>-^, 






* ^^S n' N ui 




„ ^r^jr«-»iw«» -S^2 


>^^^^s ^^S"^ ^ II 


j^ -^Mk enmcMi^g; 


'3|B»«'^<5™^ ' ^" 


„ 


■f^^^r""^ f^^s, 


^^r«eao^x\ ' 


■^ 




^Kf'^°^l^ \s ' ' ^ 




W'^ ^ ^^a>,-\Tee^«« 


^^"^yy \ ' ^ 




» r *1^$ f 






/ * ^i*^^ / ' 






1 M^^jI 


V w 




\ \^\ 


_M 


■"^ A^^^^ 


1 r^ W\ 




9 A '" Vs^^^^^^^ 


"^\l\ 




-"/i^-^ *v?^p^^ 




.f? ^-^^Sdi^^ 


ft luA 




^^ T"^, 


^J^\ 


- 


^^v 


A:i/ js~a^a^ 


I 




^7^ 


V\^ 




^ 


11 


L 1. 


I .L 


j1 



MAP OF THE SAN JUAN DELTA. 



APPENDIX II.— GEOLOGIC REPORT 



99 



trntin«r everr step in the process: first, the open 
lagoon, then the floating grass-mat, then the 
Silieo swamp, and finally the heavy forest. 

A> alrea<lv indicated, the delta-plain at its 
inner margin merges with the broad flood-plain 
of the San Jnan river and any line separating 
the two wonld be pnrely arbitrary. For con- 
venience, however, the head of the delta may be 
placed at the point where the first distributary, 
the San Jnanillo, leaves the main stream. 

Most flood-plains are formed by the lateral 
cutting of streams as they swing from side to 
side in their valleys. A plain thus cut in the 
nnderlving rocks is nsnallv covered with a thin 
sheet of alluvial material. The flood-plains of 
this region, however, belong to a totally dif- 
ferent class. They include* no level plains cut 
in the underlying rock or residual material which 
covers the rock. On the other hand, the allu- 
vium has very considerable depth, and instead of 
forming a layer of uniform thickness, fills a 
series of old stream channels. It is evident that 
these channels were formed when the land stood 
higher than now, for manv of them extend 
below sea level. There is thus an old land sur- 
face concealed beneath the alluvial deposits, and 
a consideration of its topography becomes a 
matter of prime importance to the engineer. 
This buried topography will be considered more 
fully in connection with the unburied portion of 
the same surface, that is, the surface of the hills 
rising above the margins of the alluvial plains. 

Extensive flood-plains extend up the San Juan 
river to the mouth of the San Carlos; above this 
to the head of the Toro rapids the river flows 
in a comparatively narrow gorge and its flood- 
plains are narrow and inconspicuous. From 
the Boca San Carlos downward to the head of 
the delta, flood-plains are always present on one 
or both sides of the river, though they are most 



extensively developed on the south side. The 
surface is slightly higher near the river, forming 
the natural levee which characterizes most flood- 
plains. The outer margins are depressed and 
occupied by swamps or lagoons. The surface 
of the flood-plains in the vicinity of the Boca 
San Carlos varies from 15 to 20 feet above the 
river at ordinary low stages. As the plains be- 
come more extensive downstream, their surface 
is slightly less elevated, since the floods which 
deposit the alluvium, having opportunity to 
spread over a much larger area, do not rise so 
high. 

The slope of the flood-plains from the Boca 
San Carlos to the head of the delta is about 12 
inches per mile. This slope is dependent upon 
the volume of the river and the character and 
quantity of the sediment wdiich it carries. It 
is therefore nuich steeper below the mouth of 
the San Carlos than above, for it is from this 
stream that the greater part of the coarse sedi- 
ment in the lower river is derived, but it is only 
about two-thirds as great as the slope of the 
delta plain. 

As stated above, the flood-plains are incon- 
spicuous from the Boca San Carlos to the head 
of the Toro rapids. The river flows in a compara- 
tively nari'ow gorge and is generally bordered 
by rather steep hills which approach nearly 
to the river channel. At the head of the Toro 
rapids, however, the valley widens, and from 
this point to the lake the river is everywhere 
bordered on one or both sides bv extensive flood- 
plains. Although their general relations to the 
river are similar to those bordering its lower 
course they yet differ in some important par- 
ticulars. They liave been formed bv sediment 
borne, not bv the river itself, but bv tributaries 
coming into the valley on either side. They 
thus have the form of coalescing deltas. The 



100 



NICARAGUA CANAL COMMISSION 



natural levee which is a conspicuous feature in 
the flood-plains of the lower river is absent, and 
the plains generally show a gradual descent from 
their outer margins toward the river. Hence 
there are no lagoons upon the tributaries such 
as are found on the tributaries of the lower river, 
and the flood-plain becomes gradually firmer 
and more heavily wopded with increasing dis- 
tance from the river. From the mode of forma- 
tion of these plains it is manifest that the river 
is in a stable position and does not show that 
tendency to seek a new channel which is char- 
acteristic of delta streams. 

Most of the streams entering Lake Nica- 
ragua on its northeastern side at one time en- 
tered the heads of estuaries. These estuaries 
have been almost entirely filled mth alluvial 
deposits, and in some cases somewhat extensive 
deltas have been built out into the lake. The 
absence of a surf in this portion of the lake, ex- 
cept on rare occasions, owing to the direction of 
prevailing winds, permits the building of deltas 
which carry the distributaries of the streams 
a considerable distance out from the general 
shore line. The most extensive alluvial deposits 
about the lake are at its southern end. This 
portion of the lake basin appears to have been 
originally rather shallow and the sediment 
brought in by streams from the south, notably 
by the Rio Frio, has considerably contracted 
its area. The newly-added land forms about 
the margin of the lake an extensive swamp 
through which the streams meander in a network 
of interlacing distributaries, all more or less 
obstructed by vegetation. The land becomes 
gradually firmer at increasing distances from 
the lake and finally passes into an ordinary allu- 
vial flood-plain. Streams entering the lake from 
the southwest in general flow in channels which 
were at one time excavated to a very inconsid- 



erable depth below the present surface of the 
plain through which they flowed. This plain, it 
may be remarked in passing, is not alluvial, but 
is a plain of degradation. Hence these streams 
are bordered by very inconsiderable alluvial 
plains and that only near the lake. The streams 
entering the Pacific from this portion of the 
isthmus are all short and consequently small, 
since the Continental Divide is near the west 
coast. They occupy valleys which have been 
cut to a much greater depth than they have at 
present, and these old valleys have been recently 
drowned and more or less perfectly filled with 
alluvial deposits. Where the filling is not quite 
complete an estuary occupies the old river valley 
and forms a harbor as in the case at San Juan del 
Sur. Where the filling is complete, as in the val- 
ley of the Eio Grande, the headlands which mark 
the margins of the former deep valley are con- 
nected by a curved beach which does not indent 
the coast to any appreciable extent. The depth 
of the alluvium in the Rio Grande vallev varies 
from about 40 feet at the head of the flood-plain 
to something over 100 feet at the coast. The 
stream which has filled this vallev carries at 
certain seasons an abundant supply of sediment, 
so that the seaward slope of the flood-plain is 
rather steep, a little over ten feet to the mile. 
The conditions in this region which determine 
the rate of erosion are much more favorable to 
rapid degradation of the surface than in the 
region of much greater rainfall to the east, where 
the rain is distributed somewhat equally through- 
out the year. The streams are alternately 
shrunken to mere rivulets and swelled to tor- 
rents and the resulting flood-plain has somewhat 
the character of an alluvial cone. 

The Dissected Peneplain, — The group of 
topographic forms to be described next in order 
after the alluvial plains, consists of a more or 



APPENDIX II.— GEOLOGIC REPORT 



101 



less completely dissected plain or peneplain of 
degradation. In order to understand the present 
topography it is necessary to consider the orig- 
inal form of this plain and the manner in which 
it was developed. The conditions which pre- 
vailed prior to its formation cannot be definitely 
determined, but may be inferred in a general 
way. There was probably a somewhat elevated 
plateau growing broader and higher both to the 
northward and the southward from a somewhat 
constricted region now occupied by the Xica- 
raguan depression. The Continental Divide at 
that time probably occupied a position near the 
central part of the isthmus, crossing the present 
San Juan vallev in the vicinitv of the Castillo 
rapids, and streams heading upon this Divide 
flowed to the seas on either side. Another im- 
portant difference was in the form and position 
of the Pacific coast line. The differences in 
the geography of the region, so far as they can 
be inferred, are represented on the accompany- 
ing sketch map, Plate 11. It will be noted that 
Lake Nicaragua did not then exist. Its present 
basin was occupied in part by a bay indenting the 
coast line and in part by the basins of rivers trib- 
utary to this bay. The region occupied by the 
volcanic peaks of the Xicaraguan range and the 
volcanic plateau west of the lake was then oc- 
cupied by the sea. A cape projecting north- 
ward between the sea and the bay was composed 
of low hills now forming the Continental Di- 
vide southwest of the lake. 

In still other respects the drainage of the 
region during the formation of this peneplain 
differed from the present. The San Juan river 
receives onlv small tributaries from the north 
while it receives both small and large from the 
south. The large tributaries include the Frio, 
Poco Sol, San Carlos and Sarapiqui. These all 
head upon the slopes of the Costa Rican volcanic 



range which forms the southern margin of the 
Nicaraguan depression. The upper portions of 
these streams are normal to the mountain range, 
the axes of their valleys being at right angles 
to the axis of the range and also to the general 
course of the San Juan. Midway of their 
courses, however, there is an abrupt change in 
direction. The Frio and Poco Sol bend west- 
ward while the San Carlos and Sarapiqui bend 
eastward, the axes of the lower valleys in every 
case making a rather acute angle with the course 
of the San Juan. It seems probable that when 
the peneplain was being developed in this region 
the two rivers whose basins now form that of 
the San Juan occupied the axes of those basins 
receiving tributaries of equal length from either 
side. The volcanic eruptions to the south, 
however, obliterated the former drainage of that 
region, and the consequent streams developed on 
the flanks of the newly-formed moimtains were 
turned northward, discharging into the head^ of 
the pre-existing small tributaries. It thus ap- 
pears that the four above-named southern tribu- 
taries of the San Juan have composite courses. 
Their upper courses, normal to the trunk stream, 
are consequent) upon the constructional slope 
of the recent volcanic range, their lower courses 
making acute angles with the trunk stream are 
inherited from the normally-developed, small 
tributaries of two streams flowing east and west. 
The rapidity with which the streams heading 
upon the Continental Divide reduced their val- 
leys to base level depended chiefly upon the 
character of the rocks which they encountered, 
while the rate at which the Divide was lowered 
by the action of opposing streams depended upon 
the character of the rocks and the distance of 
the Divide from the coast, or the width of the 
isthmus. The region to the northward is prob- 
ably occupied by older and more resistant rocks, 



102 



NICARAGUA CANAL COMMISSION 



iiichuling gneisses, schists and quartzites. Of 
tliat to the south \crj little is known since its 
topography has been entirely changed and its 
older rock formations concealed bv the recent 
eruptions of its A'olcanoes. From this com- 
bination of circnmstances it followed that the 
surface was most completely degraded and the 
Divide most rapidly lowered along a belt ex- 
tending diagonally across the isthmns and now 
forming the great Xicaraguan depression. A 
broad river basin was developed- on the east side 
of the Divide, occupying the present position 
of the lowcT San Juan basin. The land be- 
tween its various southern tributaries was re- 
duced to low relief. Its nortluTU tributaries 
were separated by somewhat higher hills, prob- 
al)ly the result chieflv of the greater oriijinal 
elevation of this portion of the region. Another 
river system developed a similar basin with its 
outlet to the Avest. The several upper tribu- 
taries of each of these two river svstems headed 
upon the Continental Divide in low ga])s against 
the tributaries of the other system. The basin 
of the western svsteni was somewhat larger 
than the one on the east of the Divide. Its lower 
portion Avas separated from the Pacific by a range 
of hills Avhich continued nortlnvestward, form- 
ing the cape between the then existing bay and 
the ocean. The southern portion of the present 
basin of Lake Nicaragua Avas occupied by this 
river system, and extensive plains Avere devel- 
oped on either side of the axis extending up the 
tributaries as broad valleys well back into the 
surrounding liills. 

The foregoing brief account of the original 
extent of this peneplain and the manner in 
which it Avas formi^d is an essential preliminary 
to an understanding of the present topography of 
the region. At the conclusion of the long 
period of degradation, during which the Xica- 



raguan dei>res>ion was reduced to a region of 
low relief, the laud was sIoavIa- elevated until it 
stood some hundred feet higher than before and 
perhaps tAvo hundred feet higher than now. 
The elevation stimulated the streams to rencAved 
activity, and they began trenching the A'alleys 
AA'hich they had previously formed. The ero- 
sion was at first most active near the coast and 
worked backward toward the interior most rap- 
idly along the largest streams. The portions of 
the peneplain most completely dissected Avere, 
therefore, its ontor margins. Here the surface 
was almost entirelv reduced to the lower base- 
level and ouIa- a few rounded hills on the divides 
retained any trace of the former plain. The first 
of these remnants s(»en on ascending the San 
Juan are in the vicinitv of the delta head Avhere 

« 

low hills approach the river on the north side. 
This region, however, has been so deeply dis- 
sected that the hilltops scarcely suggest the ex- 
istence of a former plain. Other hills of sim- 
ilar character occur along the river, chiefiy on 
the north side, although the most prominent hills 
Avhich come down to the river do not belong to 
the group now being described but to the residual 
hills Avhich rose above the surface of the old 
plain at the time of its most perfect development. 
The remnants of the dissected plain increase in 
number and in the regularity of their summits 
until in the vicinitv of Ochoa their uniformitv 
is such that the position of' the old peneplain 
(»an be accurately determined. The dense troi> 
ical forests mask the minor topographic features 
so that the uniformitv in the summits of the 
hills is not at once apparent. The detailed 
contour maps, however, of those portions of 
the rcgion Avhich have been actually surveyed 
exhibit the uniformity in a striking manner. 
The present elevation of the hilltops in this 
region is about 150 fe(»t above sea level, and the 



NICARAGUA CANAL COMMISSION. 




TerTiary baselevefiog period ^ — 

f^acific coast line at ttie end oftHe 

poSt-lerTiary baseleveling period 

Pi'esetnt conTrn«nTal divide **♦» + »♦♦ 

Former corftmentsl divide »-**■»*-* 

Recent" volcanoes O OO 




MAP SHOWING CHANGE 



APPENDIX 2, PLATE II. 




ST LINES AND DIVIDES. 



APPENDIX II.— GEOLOGIC REPORT 



103 



uniformity of tlieir summits is shown in the 
sections of the San Carlos embankment line, 
Fig. 2, Plate III. To the south of the river 
the old plain was very extensively developed, and 
while it has suffered much subsequent dissection, 
there is a large area in which its former position 
can be readily determined by th(» summits of 
the present hills. To the north of the river it 
was less extensive, forniinsi: onlv broad vallevs 
between the residual hills which occupied the 
divides. Although not so extensively devel- 
oped here as south of the river, the plain has 
been somewhat better preserved and many 
streams are found which have not vet lowered 
their valleys appreciably below the old surface. 
Heading upon the steep residual hills their up- 
per courses are in sharply cut V-shaped valleys. 
Emerging from these they flow in shallow val- 
leys across the remnant of the old plain, tlieir 
channels meandering and obstructed by swamps. 
Farther down they enter nari'ow gorges which 
they have cut and are still deepening in the old 
peneplain. Still farther down they are bor- 
dered by alhwial plains where the valleys which 
they cut in the old plain have been depressed 
below base level and so silted up. 

These features are admirablv shown on the 
Machado and other tributaries of the San Juan 
in the vicinity of Ochoa. They may perhaps 
be made clearer by reference to the somewhat 
idealized sketch and section forming Fig. 1, 
Plate III. The surface of the i>eneplain is in- 
dicated bv the even summits of the hills to the 
right. Residual hills are represented to the left, 
rising abruptly and distinctly above the surface 
of the pene])lain. The profile shows a trans- 
verse section of the San Juan valley and a longi- 
tudinal section of the vallev of a tributary 
stream. The latter is re[)re.sented as rising in 
the residual hills to the left and flowing for 



some distance in the narrow gorge a 6. From 
h to c the stream flows in a broad, shalfcw valley 
at about the level of the peneplain. From c to 
d it is in a narrow gorge recently cut and still 
being actively deepened within the peneplain. 
It emerges from this gorge at d and thence to 
the margin of the main river valley at e it 
meanders through an alluvial plain, the con- 
tinuation of the San Juan flood-plain e /. The 
bottom of the vallevs which the tributarv and 
the trunk stream occupied before the recent de- 
pression of the region is represented in the pro- 
file by the solid line between the alluvium and 
the underlving rock. When these vallevs w^ere 
formed they were considerably above sea level 
and the streams had a much more rapid fall than 
at present, but they arc^ now somewhat below 
sea level. 

Continuing westward from Ochoa the sum- 
mits of the hills become less uniform in altitude, 
corres])onding with the originally less perfect de- 
velopment of the old peneplain in the vicinity 
of the former Continental Divide. Along the 
upper portion of the river, west of the Toro 
rapids, are numerous low, rounded hills merging 
on either side of the vallev with a more con- 
tinuous upland and these probably mark the po- 
sition of the former peneplain. It slopes gently 
westward and probably passes beneath the waters 
of Lake Nicaragua. The broad valleys bordering 
the streams which enter the noi^theastem side 
of the lake and the level plain which forms the 
western margin of the lake basin probably con- 
stitute parts of this old plain, which have here 
almost entirely escaped dissection. 

In connection Avith the remnants of this old 
peneplain the topography of the surface now 
concealed by the alluvial deposits should be con- 
sidered. At the close of the period of high 
level, during which. the plain was dissected, the 



104 



NICARAGUA CANAL COMMISSION 



valleys were rather narrow w^ith steep slopes ex- 
cept near the coast. If the subsidence which in- 
augurated the period of alluviation had occurred 
all at once, tidewater would have extended up 
the valley of the San Juan beyond the Boca 
San Carlos and also some distance up its tribu- 
taries. It is probable, however, that the land 
sank very slowly so that the estuaries were never 
deep, but were filled by alluvium almost as fast 
as formed. The depth of these old valleys hav- 
ing been determined by borings at various points 
on the trunk stream and some of its tributaries, 
it is possible to reconstruct the former surface 
and determine approximately the depth of the 
alluvial filling in any part of the drainage sys- 
tem. It is found that the erosion of the hills 
has been inconsiderable since the submergence, 
for the slopes above the margin of the flood- 
plains are practically the same as the old slope 
beneath the alluvial cover. The forms of the 
alluvium-filled vallevs are shown on the sections 
representing portions of the San Francisco em- 
bankment line, Plate XVIII. The valleys of 
the lower San Juan and its tributaries have been 
filled in such a manner that the present streams 
follow very nearlv the same course as the 

streams which formed the vallevs. In some 

t/ 

cases their meanders have carried them to one 
side or the other of the old valley where they 
are now cutting against the bordering hills of 
residual clay. 

While the existence of this old channel might 
be inferred with certainty from a study of the 
present river valley, its form and seaward gradi- 
ent could be determined only by boring. From 
the data obtained with the drill at the various 
dam sites and other points on the river between 
Machuca and Tambor Grande, transverse and 
longitudinal sections have been constructed, 
which show fairly well the characteristics of the 



buried channel. Its gradient as shown on the 
longitudinal section. Fig. 2, Plate XV, is fairly 
uniform but considerably steeper, than the gra- 
dient of the present river. The lower portion is 
also steeper than the upper. Thus from Cas- 
tillo to Ochoa the gradient of the rock chan- 
nel is about 3 feet per mile, while from 
Ochoa to Tambor Grande it is 5.8 feet. 
The minor irregularities in the channel are 
doubtless due to differences in the hardness of 
the rocks, but the increased slope of the lower 
portion of the channel is probably due to some 
change in conditions during its formation, such 
as a slight uplift toward the end of the gorge- 
cutting period. The form of the buried chan- 
nel is shown on the five transverse sections at 
dam sites between Machuca and Tambor Grande, 
Figs. 3 to 7, Plate XVII. In general the 
buried slopes conform with those above the pres- 
ent river, and its flood-plains and the sections are 
about what would have been inferred from the 
exposed slopes. 

The original form of the surface concealed by 
the flood-plain of the upper San Juan is much 
more difficult to make out. This plain was 
formed by deposition in quiet water, the river 
valley being entirely drowned. Hence the pres- 
ent channel was not determined by the deepest 
portion of the old vallev but bv the relative 
amounts of sediment brought into this portion 
of the lake bv tributaries on either side. It is 
evident that the stream bearing the largest 
amount of sediment is the Rio Frio, and the 
delta of this stream has pushed the outlet of the 
lake northward away from the deeper portion 
of the old valley and against the hills which 
formed its margin. The same thing is seen at 
various points between the lake and the Toro 
rapids. At numerous points the meanders of 
the river carry it away from the deeper portions 



APPENDIX II.— GEOLOGIC REPORT 



105 



of the old valley and against the marginal hills. 
In most eases these meanders are not accidental, 
but are determined by the entrance of a tribu- 
tary on the opposite side. It is therefore im- 
possible to determine the position of the stream 
which formerly occupied this valley, from the 
present position of the San Juan. Sufficient 
boring has been done in this portion of the river 
channel, however, to determine the fact that the 
rock or residual clay slopes of the hills which at 
present rise above the alluvial plain continue 
practically unchanged beneath the alluvium. 
The importance of this fact in the location of 
the canal line is at once apparent. The line in 
general follows the channel of the river, but if 
tliis were strictly followed considerable rock ex- 
cavation would be necessarv wherever the chan- 
nel swings against one of the marginal hills. It 
is evident, however, that by shifting the line 
away from the hill the rock slope will pass be- 
low the bottom of the canal so that the excava- 
tion necessary to secure the required depth will 
be entirely in alluvium. 

The Residual Hills. — The third group of to- 
pographic forms which characterizes the Nicara- 
guan depression embraces the elevations rising 
distinctly above the present tops of the lower 
hills and representing portions of the surface 
never reduced to the level of the old peneplain. 
The summits of these residual hills are entirely 
different from the dissected remnants of the 
peneplain above described. The crests are al- 
ways sharp and serrate with no uniformity what- 
ever in their altitudes. As already stated these 
residual hills increase in frequency and magni- 
tude toward the north, occupying the divides 
between the northern tributaries of the San 
Juan. 

The hills of the Eastern Divide lying between 
the basins of the Deseado and the San Fran- 



cisco form a characteristic group belonging to 
this class. Their slopes are steep and their sides 
are furrowed by sharp V-shaped ravines. Around 
their base are remnants of the old plain above 
which they formerly rose, now appearing as 
rounded hills with uniform summits. Long 
spurs radiate from the central mass of the East- 
ern Divide hills and reach the San Juan river 
at several points, forming the high ridges at 
Sarapiqui, Tamborcito, Tambor Grande and San 
Francisco. Another prominent group of hills 
belonging to this series occurs at the junction of 
the San Juan and San Carlos. These have a 
form similar to that of the Eastern Divide hills, 
but the group is somewhat smaller. The upper 
slopes are extremely steep and the sides are 
deeply gullied while the summit as seen from 
either side presents a sharply serrate outline. 
The altitude of the San Carlos hills is about 
1200 feet. These isolated groups of high hills 
occur with increasing frequency toward the line 
formerly occupied by the Continental Divide, 
which probably crossed the present valley of the 
San Juan in the vicinitv of Castillo. West of 
this line they decrease in frequency and height 
to the lake. Along the northeastern margin of 
the lake the hills of this class are represont-ed by 
the high spurs occupying the divides between 
the broad river valleys. On the west side of 
the lake they are perhaps represented by the 
ranges of hills which rise abruptly from the 
Eivas plain and extend from its western margin 
nearly or quite to the Pacific. Northward 
from the San Juan valley these residual hills 
increase gradually in height and numbers, form- 
ing the divides between the lake and Caribbean 
drainage and the subordinate divides between 
the streams of each system. By their gradual 
increase in this direction they form the indefinite 
northern limit of the great Nicaraguan depres- 



106 



NICARAGUA CANAL COMMISSION 



sion. In northern Nicaragua they attain con- 
siderable size, forming mountains which reach 
altitudes of five to seven thousand feet. 

The AVkstekx Divide. — As alreadv indi- 
cated, the great Kicaraguan depression was 
formed before Lake Nicaragua came into exist- 
ence. It originally extended entirely across the 
isthmus, terminating to the westward at the bay 
which then indented the Pacific coast, a cape 
projecting to the northwestward between this 
bay and the ocean. The cape now forms the 
southern part of the narrow isthmus lying to the 
southwestward of Lake Nicaragua and separating 
it from the Pacific. This strip of land is not 
properly, therefore, a part of the Nicaraguan 
depression and its topography should be inde- 
pendently considered. 

Bordering the southwestern shore of the lake 
and extending northwestward nearly to Zapatera 
island, is a very perfectly base-leveled surface, 
termed, for convenience, the Kivas plain. It 
varies in width from five to twelve miles and is 
continuous along the lake margin except near 
the Sapoa river where it is interrupted for a 
short distance by high hills coming down to the 
lake. Very little is known concerning the 
southeastern extension of this plain, but it is 
probably nearly or quite continuous around the 
end of the lake with the pcne^>lain of the Nica- 
raguan depression already described. Its north- 
eastern margin is the lak(^ shore, where the 
waves have cut a shallow terrace backed by a 
cliff from ten to fortv feet in hei^rht. A few 
low rounded hills rise above its even surface but 
they seldom attain heights of more than one 
hundred feet. In the vicinity of Rivas, where 
it is most thoroughly known, the plain ascends 
toward the southwest at the rate of about eight 
feet to the mile to the base of the hills which 
occupy the greater part of this strip and form 



the Continental Divide. These hills rise abruptly 
from the Rivas plain to heights of 800 to 1200 
feet above tide, and extend northward to a ix)int 
opposite the island of Zapatera where they meet 
the Jinotepe plateau and the serrate residual out- 
line of the former gives place to the even con- 
structional slope of the latter. A single break 
occurs in this continuous line of hills. This is 
the gap betw^een the waters of the Rio Lajas and 
of the Rio Grande. Here the level plain bor- 
dering the lake extends entirely through the 
range of hills, fonning a low broad gap whose 
summit is but fifty feet above the lake. 

The manner in which this single low gap was 
formed is described at some length in a later part 
of this report (page 142), where the recent geo- 
logical history of the region is given. It may 
be stated here, however, that the gap is the pro- 
duct of the familiar process of stream capture. 
Owing to the decided advantages possessed by 
the streams flowing directly to the Pacific over 
those flowing eastward at first to the bay of Nica- 
ragua and afterwards to the lake, the former 
were able to cut back through the divide into 
the drainage area of the latter and divert their 
headwaters. In this way an eastward flowing 
stream originally occupying the position of the 
Tola, the upper Rio Grande, the Guiscoyol and 
the Lajas was beheaded, and the drainage of a 
large part of its basin was diverted to the Pacific. 
The deserted vallev of this stream fonns the low 
gap through which the canal route is located. 
It is so broad and level that accurate instru- 
mental work is required to determine the actual 
summit of the Continental Divide. 

The Pacific coast in the southern part of this 
region is formed by alternating short strips of 
sandy beach and bold rocky promontories. The 
stretches of beach are fonned by the silting up 
of deeply cut valleys and the promontories by 



APPENDIX II.— GEOLOGIC REPORT 



107 



the truncated points of ridges which extend 
down to the coast between the valleys. To the 
northward of Brito, the proposed western termi- 
nus of the canal, at the month of the Rio 
Grande, the hills are farther inland and fewer 
sjnirs reach the coast. A coastal plain of some 
extent is here developed, increasing in width to 
tlic northward until it passes beneath the recqnt 
voU'anic deposits which form the Jinotepe 
plateau. 

This coastal plain probably at one time passed 
around tlie northern end of the divide hills and 
was continuous wuth the Rivas plain to the 
east. "With the formation of the Jinotepe 
plateau the tnffs of which it is composed buried 
this northern portion of the plain and piled up 
against the end of the divide hills three or four 
hundred feet in thickness. 

Regions Adjacent to the Xicaraguax De- 
PKEssioN. — The Nicaraguan depression and the 
AVcsteni Divide as above defined and described 
embrace the naiTow belt of country to which all 
feasible variants of the Nicaragua Canal route 
are confined. The topography of the adjacent 
regions, however, is of more or less interest and, 
particularly from hydrographic considerations, 
has a direct bearing upon canal problems. Its 
main features will therefore be ver}^ briefly de- 
scribed. 

Tlip Lake-Caribbean Divide, — Consider first 
the region lying north of the San Juan, between 
the lake and the Caribbean. As alreadv stated 
the residual hills which rise*above the ])fnoplain 
of the Nicaraguan depression increase in height 
and numbers toward the north, finally merging 
w^ith tlie mountains of northern Nicaragua, 
where they reach elevations from six to seven 
thousand feet above tide. Comparatively little 
is known of any portion of this region except its 
western margin. The eastern part is covered 



with a dense tropical forest, is almost entirely 
without settlement, and has been only partially 
explored. 

The divide between the lake and the Carib- 
bean drainage passes some distance to the west- 
ward of the axis of the isthmus, being approxi- 
mately parallel with the Pacific coast north- 
westward to the Matagalpa river, where it makes 
an abrupt bend to the eastward, passing around 
the basin of that stream. This region between 
the lake and the Caribbean mav be described as 
a deeply dissected upland. During Tertiary 
time it was doubtless the locus of intense vol- 
canic activity, but subsequent erosion has en- 
tirely destroyed all trace of the original (;on- 
structional topography, and the location of the 
vents by which the volcanic rocks were erupted 
cannot be determined from the present fonn of 
the surface, though it might be detennined by 
a systematic study of the distribution and varia- 
tions in character of the volcanic rocks. To- 
ward the northern end of the lake, opposite Gra- 
nada, the summits of the hills present an even 
skyline as though they were remnants of a pla- 
teau, but this surface may be a degradational 
rather than a constructional plain. 

The streams flowing into the lake have base- 
leveled their vallevs for a considerable distance 
back into the upland, but are separated by sharp 
ridges and hills which occupy the divides. Al- 
though the higher portions of the divides attain 
somewhat unifonn altitudes which increase 
northward, the uniformity is not sufficient to de- 
termine the former existence of a distinct plain, 
and it is probable that the present valleys are 
carved in a surface which, since its final emer- 
gence above sea level, has always had ratlu^r 
high relief. So far as known the trend of the 
ridg(h^ and lines of hills which cK,*cupy this re- 
gi(m have been determined entirely by the direc- 



108 



NICARAGUA CANAL COMMISSION 



tion of the drainage and is consequently nearly 
east and west. It is possible, however, that the 
original geological structure may have deter- 
mined the position and direction of the streams, 
although they occupy the position which they 
would have assumed if developed normally upon 
a gently arched plateau. 

The much greater rainfall in the eastern por- 
tion of this region has given the Caribbean 
streams a decided advantage, and they have 
pushed the di\'ide westward probably some dis- 
tance from its original position. A few cases 
occur which clearly indicate stream diversion. 
The most striking of these is the upper portion 
of the Rio Grande which flows to the Caribbean 
north of Bluefields. (See Plate II.) This river 
heads in the high valley of Matagalpa, from 
which it flows southwestward for thirty-five 
miles, approaching the Viejo within about five 
miles, being separated from that stream by a 
level swampy plain. The Viejo flows southwest- 
ward to the upper end of Lake Managua and it 
is entirely probable that the upper portion of the 
Eio Grande was formerly a tributary^ of the 
Viejo. From the point where it approaches 
most nearly to the Viejo it flows southward for a 
distance of twenty-five miles, and this southerly 
direction is continued in a tributary which enters 
at that point. This portion of the stream ap- 
pears to have been at one time a part of the 
IMalacapoya which enters the head of Lake Nica- 
ragua. From the point of nearest approach to 
the Malacapoya the Rio Grande turns abruptly 
back to the northeast and for a distance of thirty 
miles is approximately parallel to its upper 
course in the valley of Matagalpa. It appears 
highly probable that the Rio Grande by reason 
of the greater rainfall in the eastern part of this 
region pushed the divide westward until its 
headwaters intercepted the upper portion of the 



Malacapoya. The same process was continued 
and the extended headwaters affected another 
conquest, diverting a large tributary * of the 
Viejo. The latter capture has been so recent 
that the channel of the diverted stream has not 
been perceptibly lowered and a part of its waters 
in the wet season may still follow their former 
course to the Viejo across the inter\-ening 
swampy plain. A few other cases of stream di- 
version are indicated by the character of the 
present stream channels, but none of them are 
so striking or important as that of the Rio 
Grande. 

Volcanic Mouniain Banges. — As indicated 
above, the southern margin of the Nicaraguan 
depression is formed by the foothills of the 
Costa Rican volcanic range. This range termi- 
nates to the northwestward in the probably ex- 
tinct volcano Orosi. It contains a large num- 
ber of volcanic peaks, most of which are extinct 
while a few are quiescent or moderately active. 
These peaks have a striking linear arrangement 
and form two nearly parallel lines of vents. 
The line terminating in Orosi extends southeast- 
ward into Costa Rica, passing to the southward 
of a parallel range whose northern peak is the 
volcano Turrialba. These two lines are about 
ten miles apart, but their peaks are so high that 
their slopes merge and they form a single range. 
If the line connecting the northeasteni series of 
peaks were continued to the northwestward 
through the southern portion of Lake Nicaragua 
it would coincide very nearly ^vith the line con- 
necting the peaks of the Nicaraguan range. The 
latter range terminates to the southward in the 
extinct volcano of Madera; thence it stretches 
to the northwestward, terminating in the vol- 
cano Coseguina w^hich occupies a peninsula pro- 
jecting into the gulf of Fonseca. Between 
these two extreme peaks there is a large number 



APPENDIX II.— GEOLOGIC REPORT 



109 



of extinct, quiescent or active volcanic vents 
forming more or less isolated mountains. Of 
these Ometepe, Masaya, Momotombo and sev- 
eral others to the northwest of the latter have 
been in eruption within historic times. Others 
are in the solfataric stage, while still others ap- 
pear to be entirely extinct. The group of peaks 
between Momotombo and Coseguina is called 
the Marabios range. 

It is probable that the vents which formed 
the Costa Rican range broke out upon a some- 
what elevated plateau, while those which formed 
the Nicaraguan range were at first submarine. 
The latter, also, are farther apart, except those 
northwestward of Momotombo, which form the 
Marabios range. This may explain the greater 
height and massiveness of the Costa Rican range, 
and the amount of material erupted from the 
two series of vents may not differ greatly. 

As already indicated it is probable that the 
form of the Pacific coast has been materially 
modified by this recent volcanic activity. The 
whole of the country between the northern por- 
tion of Lakes Nicaragua and Managua and the 
Pacific consists entirely of recently ejected vol- 
canic material, and the r^on which it now oc- 
cupies was doubtless a portion of the Pacific 
until recent geologic times. The former coast 
line is represented on the sketch map forming 
Plate n. The surface of this newly-added land 
is composed of level or gently sloping plains, 
isolated conical volcanic peaks and the more 
crowded peaks of the Marabios range. Types 
of the entirely isolated peaks are Ometepe and 
Momotombo. Both of these are composed of 
alternate layers of lava and ash. The latter, 
however, gives them their perfect conical form. 
Both have been in eruption within historic times 
and considerable smoke still comes from Momo- 
tombo. (Plate IV.) Only a small amount of 



steam and sulphurous vapors are at present emit- 
ted from the crater of Ometepe. Modification 
by the ordinary processes of erosion, in the form 
of these steep cones of unconsolidated ash, is ex- 
tremely rapid and their summits vary in detail 
of outline from year to year. Madera and Za- 
patera are volcanoes which have been extinct 
for some time and the agents of degradation 
have materially reduced their height and de- 
stroyed the original conical form of their sum- 
mits. The unconsolidated ash has been largely 
removed from their upper portions, leaving only 
the massive lava beds in place. Hence their 
formation has been ascribed to a different form 
of eruption from that which produced Ometepe 
and Momotombo. It is probable, however, that 
the summits of the former once consisted of ash 
cones and that the eruptions in all have been ac- 
companied by more or less explosive violence to 
which the unconsolidated fragmental material is 
due. The lower slopes of Mombacho are rather 
smooth and symmetrical, but instead of a single 
cone its summit is truncated and forms a series 
of ragged peaks which surround a deep depres- 
sion occupied by a small lake. There is a tra- 
dition that this mountain formerly had a conical 
summit which was destroyed by an explosive 
eruption. The present appearance of the moun- 
tain makes it extremely probable that this tra- 
dition is based upon fact Its outline closely re- 
sembles that of Coseguina, and, as is well known, 
the latter was formerly capped by a symmetri- 
cal cone which was blown off in the explosive 
eruption of 1835. This was perhaps the most 
violent recorded eruption of this character up 
to the time of the eruption of Krakatoa in 1883. 
Since this final burst of activity Coseguina has 
remained perfectly quiet. The volcano of Ma- 
saya, which erupted a flow of lava in 1858, is at 
present a mountain of moderate height, about 



110 



NICARAGUA CANAL COMMISSION 



2200 feet. It occupies the position, however, 
of a mountain which may once have been very 
much higher. The former volcanic peak occu- 
pying this position was destroyed, not by an ex- 
plosive eruption, but by engulfment. The peak 
now occupies a depressed area having an oval 
shaj^ and regular outline about four by six 
miles. It is located a little north of the center 
of this depression, the northern portion of which 
its lavas have nearly filled, flowing out over the 
edge at several points upon the surrounding 
countr\'. The outlines of the depression, how- 
ever, can be traced continuously with the ex- 
ception of these few breaks where its rim has 
been overtopped by the recent lava. It is nearly 
everywhere a vertical cliff, descending abruptly 
from the level or rolling plain. The southern 
end of the depression which is not filled by the 
lavas of Masaya is occupied by the waters of 
Lake Masaya. The lake has a crescentic form 
and is bordered on the convex side bv the verti- 
cal cliffs of the caldera wall rising 360 or more 
feet above its surface. On the concave side it 
is bordered by the gentle slope of the lavas of 
Masaya. It appears, therefore, that a portion 
of the volcanic plateau and perhaps a volcanic 
cone of considerable height have disappeared by 
engulfment, and that a subsequent eruption at 
the same point has partially filled the depression, 
building up a new cone over the same vent, 
though not to so great a height as the former 
one. This new cone is Masava. It has the 
rather low dome shape characteristic of cones 
composed largely of lava flows and is broadly 
truncated by a double crater. A similar engulf- 
ment has occurred south of Masaya, forming the 
present Lake Apoya. The latter depression did 
not coincide with a volcano but occurred on the 
northern side of Mount Catrina, a low ash cone, 
carrying down one side of the latter and a por- 



tion of the adjacent plain. The depression is 
somewhat smaller than the one occupied by the 
lake and volcano Masaya, being nearly circular 
and about four miles in diameter. The depres- 
sion is now occupied by the waters of Lake 
Apoya, the surface of which is 260 feet below 
the lowTi?t point of the surrounding rim and 
about 1500 feet below the highest point of the 
rim. This highest point probably coincides 
very nearly with the former volcanic peak, al- 
though the latter being composed almost entirely 
of unconsolidated ash has been ver\" much re- 
duced in height by erosion. Several other cal- 
dera lakes of this type occur in the vicinity of 
Managua. 

Volcanic Plateaus, — Ilefercnce has been 
made to a plateau lying southwest of Lake ilan- 
agua and the northern end of Lake Nicaragua, 
which I have called the Jinotepe plateau, from 
the principal town upon it. This plateau is 
composed entirely of recently ejected volcanic 
material, chiefly a partially consolidated vol- 
canic tuff which was sj)read out in the form of a 
semi-liquid mud. The plateau has an altitude 
along its northeastern margin of twelve to eigh- 
teen hundred feet. From this gently undulat- 
ing summit it descends gradually southward and 
southwestward to its margin against the older 
rocks to the south and to the Pacific coast. The 
central portion of the plateau has been but little 
modified by erosion and probably presen- es verv' 
nearly its original constructional form. This is 
due largely to the porous nature of the volcanic 
ash of which the surface is composed. The rain 
waters sink into the ground before they have an 
opportunity to collect into sufficient volume to 
effect any modification of the surface except 
where the original slopes were very steep. A 
belt along the coast, however, has been rather 
deeply dissected by stream channels, where the 



NICARAGUA CANAL COMMISSION 



APPENDIX 2, PLATE IV 




VOLCANO MOMOTOMBO FROM LAKE MANAGUA. 



APPENDIX II.— GEOLOGIC REPORT 



111 



smaller interniittcnt tributaries are collected into 
pcnnanent trunk streams and where the plateau 
has a decided seaward slope. Toward the north 
and nortlieast the plateau is terminated by a 
somewhat abrupt escarpment which separates it 
from the lower plain of Leon and from the plain 
lying between Lakes Managua and Nicaragua, 
These lower plains have precisely the same ori- 
gin as tlie Jinotepe plateau, and it is quite pos- 
sible that at one time the lower and higher plains 
mav have been continuous, but were subse- 
quently separated by a depression of the region 
to the northeast. In other words, the escarp- 
ment which limits the .Tinotepe plateau to the 
north and east may possibly mark the line of a 
rather recent fault. The escarpment has been 
deeply scored by stream channels so that it does 
not now have the characteristic form of a re- 
cent fault scai-p but the character of the ma- 
terials of which it is composed are such that it 
would be rapidly modified, and so retain its 
original form but a short time. 

CLIMATE. 

The climatic conditions prevailing in this re- 
gion have so direct a bearing upon its geology 
and physiography that a brief statement of the 
more important characteristics of the climate is 
essential. Lying only ten degrees north of the 
equator the climate of the region is tropical, 
frost being entirely unknown. Furthermore 
since it forms a narrow belt between two oceans 
its climate is also insular, the annual range of 
temperature being very much smaller than all 
continental areas experience. 

Amount and Distribution of Rainfall. — 
Throughout the greater part of tho year the 
trade winds prevail with fairly constant direction 
and force. These winds are probably deflected 
slightly to the northward by the high voncanic 



range of Costa Rica, and to the southward by 
the mountains of central and northern Nicara- 
gua. Tho low gap across the isthmus constitu- 
ting the Nicaraguan depression, thus receives 
considerably more wind than would be due to 
the nonnal trades. It is probably this conges- 
tion of the air currents that causes the excep- 
tional precipitation in this region. Coming from 
the warm Caribbean sea the trade winds are 
saturated with moisture, and as they strike the 
slightly elevated land forming the isthmus the 
precipitation is there veiy abundant. Within 
the zone of maximum precipitation which em- 
braces the coastal plain and the adjacent hills, 
forming a belt from 50 to 100 miles wide, the 
annual raihfall reaches nearly 300 inches. Be- 
yond this belt at increasing distances from the 
Caribbean coast it decreases very rapidly, and in 
the western part of the region the annual rain- 
fall is less than a third of that on the eastern 
coast. 

More important, however, than the absolute 
amount of rainfall is its distribution throughout 
the year. The isthmus may be divided into two 
distinct and well marked subdivisions by a line 
coinciding approximately with the present di- 
vide between lake and Caribbean drainage and 
crossing the San Juan near the point where that 
river leaves the lake. In the eastern division 
the rain is distributed with tolerable uniformity 
throughout the entire year. There are some 
years in which little rain falls for a period of 
three or four weeks in August and September, 
but this scarcely constitutes a dry season. In 
the western division, on the other hand, there is 
a distinct drv season of five or six months, in 
which there is practically no rainfall. The rain 
begins about the middle of May when the trade 
winds become less constant and an occasional 
storm comes from the northwest. 



112 



NICARAGUA CANAL COMMISSION 



Physiographic Effects. — ^These climatic dif- 
ferences between the eastern and western por- 
tions of the region give rise directly to very 
striking differences in vegetation, and either di- 
rectly or indirectly to differences in the appear- 
ance and structure of the soils, in the topo- 
graphic forms of the land surface and in the ef- 
fectiveness of various physiographic processes. 

Eastern Division, — The eastern division, in 
which the rain is distributed with tolerable uni- 
formity throughout the year, is covered with a 
dense tropical forest. The only breaks in this 
forest are the stream channels and the open 
lagoons, or those so recently silted up that the 
soil is not sufficiently firm to support large trees. 
Throughout this region there are no human hab- 
itations except in the few small towns along the 
coast and an occasional hut in a clearing upon 
the banks of the rivers. There are no roads or 
other means of intercourse except by way of the 
streams. 

The most directly apparent effect of the forest 
is to protect the land surface from erosion. The 
falling rain is intercepted by the canopy of foli- 
age, and filters down gradually to the surface, 
where the smaller vegetation consists largely of 
palms whose broad leaves afford a still further 
protection so that the soil never receives the di- 
rect impact of the raindrops. Since there are 
no forest fires the surface is more or less per- 
fectly covered with forest litter which acts as a 
further protective covering to the soil. The 
character of the soil will be described more fully 
in treating of the regolith, but it may be stated 
here that the surface of this eastern division, 
wherever it rises above the level flood-plains of 
the streams, is composed of a tenacious red clay. 
This clay never becomes dry enough to be in- 
tersected by shrinkage cracks and is of course 
never loosened by the action of frost. Although 



it is penetrated by roots and to some extent by 
the burrows of insects, it nevertheless resists 
degradation to a remarkable degree. It was 
often observed that during a heavy rainfall the 
water flowing from the st^ep hillsides would be 
scarcely at all discolored by sediment. After 
a careful study of the region it was concluded 
that the absence of frost more than counterbal- 
ances the enormous rainfall and that degradation 
of the surface is, on the whole, slower than in 
temperate regions where the rainfall is less than 
a quarter of that in Nicaragua but where the 
surface soil is thoroughly loosened by the action 
of frost. Many of the small brooks which carry 
water throughout the year and have very steep 
gradient, flow in shallow channels cut in this 
clay. The clay often forms cascades and ap- 
pears to offer more resistance to corrasion than 
many varieties of rock. Although the hill 
slopes are steep they are comparatively smooth, 
not deeply gullied, as is usually the case in tem- 
perate regions, and it is only after the water has 
collected in considerable volume that it is able 
to lower its channel through the clay to the un- 
derlying rock. A further effect of the vegeta- 
tion, and hence indirectly of the climate, is that 
many of the streams are filled with an abundant 
growth of vegetation by which their current is 
checked and their effectiveness as an eroding 
agent correspondingly reduced. The decay of 
vegetable matter is so rapid that there are no 
considerable accumulations of such matter either 
in the forest generally or in the lagoons and 
swamps. In boring through the alluvial flood- 
plains, many of which have once been open la- 
goons, while an occasional Ic^ was encountered, 
nothing was found in the nature of peat, and the 
silt contains only a relatively small proportion 
of finely comminuted organic matter. On well- 
drained surfaces, such as moderately steep hill- 



APPENDIX II.— GEOLOGIC REPORT 



113 



sides, there is generally no humus layer. The 
red soil, practically free from incorporated or- 
ganic matter, forms the surface, only in part 
covered by the forest litter. 

Western Division, — ^In the western division, 
particularly that portion of it lying west of the 
lake, the distribution of the rainfall produces a 
distinctly different type of vegetation. This re- 
gion is characterized by open savannas in which 
the trees are small and grow in isolated patches, 
the greater part of the surface being open and 
covered with grass or small bushes. These sa- 
vannas are probably due to deforesting, in part 
by clearing for cultivation and grazing, and in 
part by fires. Wherever a forest covers the sur- 
face its character is entirely different from that 
in the eastern division. It has the thorny habit 
and scant foliage which characterizes the vege- 
tation of a semi-arid region. The light is not 
cut off by the foliage of the higher trees, and 
hence the smaller herbaceous vegetation is much 
more abundant than in the eastern division. 
Fires prevail in the dry season so that the forest 
litter does not accumulate, and at the beginning 
of the wet season, before the vegetation is re- 
newed, the surface is entirely unprotected from 
the effects of the heavy rainfall which inaugu- 
rates that season. 

Red soil is rarely seen west of the lake, the 
prevailing colors being blue, bluish-gray or 
black, and this is quite independent of the char- 
acter of the rock from which it is derived, since 
the rocks are essentially the same as those which 
yield red soils in the eastern division. Toward 
the end of the dry season the surface is inter- 
sected by many deep cracks, often two or three 
inches wide and as many feet deep, which ef- 
fectually destroy the coherence of the clay. 
This alternate saturation and baking of the soil, 

therefore, effects somewhat the same result as 
8 



that accomplished elsewhere by frost. It also 
permits the incorporation of much organic mat- 
ter with the upper portions of the soil, forming 
an exceptionally thick humus layer. From these 
and perhaps other conditions it results that the 
smaller rainfall of the western division is a very 
much more efficient agent ot erosion than the 
greater rainfall of the eastern division. 

The effect of these climatic conditions is seen 
in the topography which characterizes the region 
west of the lake. The hills are extremely steep 
and deeply gullied. At the mouth of each ra- 
vine there is an alluvial cone, showing that a 
heavv load of coarse and fine detritus is moved 
by the occasional flood which the ravine carries. 
The depth of the residual material, the regolithy 
is also very much less on the west side than it is 
on the east. This is doubtless due in part to the 
fact that the conditions of rock weathering are 
less favorable in the former than in the latter 
region, but it is also due in part to the more 
favorable conditions under which the agents of 
degradation act. Both of these factors, how- 
ever, are directly dependent on climate. 

Another factor which on the west side may 
be effective in modifying topographic forms is 
wind erosion. During the dry season when the 
protecting vegetation has been removed by 
forest fires, the steady force of the trade winds 
raises clouds of dust, and the total amount of 
transportation effected by this agency must be 
very considerable. The effects are most notice- 
able on the lake and ocean beaches where the 
sand is driven with great force and piled up in 
dunes. Roads on which there is sufficient travel 
to keep down the vegetation are usually sunk 
below the surface of the adjacent country. The 
track is often bordered by a vertical bank from 
five to fifteen feet high, and a part of this ero- 
sion is doubtless due to w4nd action. 



114 



NICARAGUA CANAL COMMISSION 



ROCK FORMATIONS. 

Conditions for Study. — The geology of the 
region uiiJer eonsideration has been examined 
in detail onlv in the vicinitv of the route of the 
proposed canal. Even where studied most care- 
fully the relations of the various rock forma- 
tions are extremely obscure. This obscurity 
arises chiefly from the nature of the exposures 
which must be depended upon in making out 
these relations. East of the lake rock exposures 
are very infrequent, and it is practically impos- 
sible from them alone to determine the relations 
of the various rock formations. The vegetation 
is so abundant that no distant views can be ob- 
tained, and the information which can usually 
be derived from a broad study ot* the topo- 
graphy is entirely w^anting. The extreme 
depths to which the rocks are decayed and tlie 
uniform mantle of red clav which covers their 
outcrojis effectually conceal their distribution 
and relations. The larger streams, as ah*eady 
explained, are chiefly flowing in old valleys 
which they are now silting up. Since they are 
not corrading their beds, their channels furnish 
exposures of materials other than alluvial only 
where they hap])en to impinge upon the adjoin- 
ing hills in their lu'oad meandei's. The only 
exception to this general statement is the San 
Juj^n l)etween Castillo and ilachuca. The con- 
ditions west of Lake Nicaragua are somewhat 
more favorable. The vegetation is iu>t so abun- 
dant, and the removal of the residual matter has 
more nearly kept pace with the rock decay; also 
the slopes are more abnipt, and most of the 
streajjis are corrading their channels except in 
the lower portions of their valleys. 

Xo attemj)t was made in the field to do areal 
mapping, and the distribution of the formations 
represented on the accompanying map (Map 
Xo. 1, Sheet 2) must therefore be regarded as 



in most cases only approximate. For the 
reasons stated above the most detailed areal work 
would secure but little additional information 
concerning distribution in some portions of the 
region. 

Classification of the Rocks. — The rocks of 
the region are placed in two groups, Tertiary 
and post-Tertiarv\ Each includes both igneous 
and sedimentary formations. Xo rocks cer- 
tainly older than the Tertiaiy occur along the 
line of the canal, although such have been re- 
ported from northern Xicaragua and also from 
central Costa Rica. The Tertiary sedimentary 
formations include the Brito and Machuca. 

Bkito Formation. — Distribution. — With the 
exception of a few areas of intrusive igneous 
rocks, the strip of land between Lake Xicaragua 
and the Pacific is occupied entirely by the Brito 
formation. It extends from the Sapoa river to 
a point o})posite the island of Zapatera. Rem- 
nants of the formation are also found along the 
lake shore to the southeast of Sapoa, and its 
present outcrops may extend continuously east- 
ward to the area occupied by the Machuca sand- 
stone. To the southward the formation is prob- 
ably covered bv the recent lavas of the Costa 
Rican volcanoes. It also probably extcmds some 
distance to the northwest of Zapatera where it 
is covered by the recent tuffs which form the 
Jinotcpe plateau. 

Lithologic Character. — The fonnation presents 
considerable variety in its lithological composi- 
tion, but it has not vet been suflicientlv studied 
to permit of its subdivision, even if this may be 
eventually ])ossible. Much the larger mass of 
the formation consists of somewhat calcareous 
non-fissile shale. When fresh this is bluish- 
urav and weathers to a yellowish or brownish 
color. Distributed through the shale are nu- 
merous beds of sandstone. These are also some- 



APPENDIX II.— GEOLOGIC REPORT 



115 



what calcareous and doubtless contain a consid- 
erable proportion of volcanic ash. The sand- 
stone beds vary in thickness from a few inches 
to two or three feet and occur singly or in 
groups. The latter are sufficiently heavy to ma- 
terially affect the topography in some places. 
These sandstones, like the shales, are blue when 
entirely fresh, but are always weathered at the 
surface to some shade of yellow or brown. The 
hills immediately west of Rivas, rising abruptly 
above the Rivas plain, are due chiefly to the 
presence of these resistant sandstones. They 
occur most abundantly, however, near the Pa- 
cific coast and are well exposed in the headland 
northwest of the Rio Grande valley at Brito. 
The beds here have a general, though some- 
what variable, dip to the southwest, hence the 
higher portions of the formation make the cliffs 
along the Pacific. This seems also to be its 
most variable portion. In addition to the shales 
which constitute its greatest bulk to the east- 
ward, it here contains also beds of sandstone, 
conglomerate and coarse volcanic breccia on the 
one hand, and on the other marly beds and 
lenses of pure limestone. Forming a part of 
the headland south of Brito is a bed of lime- 
stone something over a hundred feet in thick- 
ness. Small outcrops of this bed, or one very 
similar, have been noted at several other locali- 
ties to the eastward in the Divide hills. Its 
limited extent is due in part to erosion, since 
the dip of the bed would carry it above the tops 
of most of the hills to the eastward, but it is 
doubtful if its original extension was very great. 
Several of the limestone outcrops noted are 
probably small lenses in the shale and not con- 
nected with the more continuous bed at Brito. 
A portion of this limestone has a peculiar con- 
cretionarv structure, some of the concretions at- 
taining a diameter of an inch and a half while 



other portions of the bed are oolitic. Imme- 
diately west of this exposure of limestone, form- 
ing a group of islets nearly covered by high 
tide, is a very coarse volcanic conglomerate or 
breccia. Tlie larger fragments are a foot or 
more in diameter and quite angular, and from 
this extreme they grade downward to small peb- 
bles some of which are well rounded. The pres- 
ent relations indicate that the conglomerate is 
the stratigraphical equivalent of the limestone, 
replacing it within a few yards. In some places 
the two rocks are seen to merge, the limestone 
containing numerous angular fragments of vol- 
canic rock. At other points along the coast both 
north and south of Brito similar conglomerates 
occur. Their bedding is extremely irregular, 
and they afford evidence of having been formed 
rapidly and near the source from which their 
constituents were derived. While it is possible 
that the source of this material mav have been 
to the eastward it seems much more likely that 
it came from volcanic vents to the southwest, 
from volcanoes which have been entirely re- 
moved by the waves of the Pacific. 

Although their connection has not been con- 
tinuously traced it is assumed that the sedimen- 
tary rocks found at various points along the 
southern margin of the lake east of Sapoa, be- 
long to the Brito formation. This region was 
examined by coasting along the lake shore, so 
that it was chiefly the rocks fonning the pro- 
jecting headlands which were observed. These 
consist almost entirely of sandstones very simi- 
lar in appearance to the sandstones found inter- 
bedded with the Brito shales, and also con- 
glomerates and breccias similar to those occur- 
ring at various points along the Pacific coast. 

Structure. — (See general geological sections, 
Plate XVI.) The Brito formation wherever ob- 
served w^as foimd to be intersected by numerous 



116 



NICARAGUA CANAL COMMISSION 



joint planes as shown in Plate V. In some 
places these occur as two well-developed sets of 
approximately parallel planes which intersect 
each other at right angles. In others the joint 
planes are vers- numerous and irregular, cutting 
the beds in all directions. The latter form is 
less common and appears to be confined to rather 
narrow zones where sh(*aring and faulting have 
probal)ly taken place. The frequency of the 
joint planes varies with the thickness of the 
beds. The rhomboidal blocks into which the 
beds of shale and sandstone are broken usually 
have diametei*s approximately equal; that is, the 
more massive the original beds the farther apart 
are the intersecting joint planes. These joints 
have permitted the percolation of surface 
waters to great depths and have facilitated the 
deep Aveathering \vhicli is generally observed. 
The weathering proceeding outward from the 
joints has resulted in the fonnation of concentric 
layers about a core, which coincides with the 
center of the original rhomboidal block. The 
accompanying illustration, Plate V, is from a 
photograph of the Brito sandstone exposed in a 
ravine near La Flor. It shows the effect of the 
jointing and to some extent the subsequent con- 
centric weathering in the sandstone. The re- 
sulting rounded blocks in some places give the 
appearance of a rude rubble wall. In the vi- 
cinity of Las Lajas the horizontal sandstone beds 
have been laid bare by the action of the waves, 
and where the rhomboidal blocks produced by 
jointing have been rounded by concentric weath- 
ering, the appearance is that of a cobble pave- 
ment. 

The Brito formation has suffered onlv a mod- 
erate amount of disturbance since its beds were 
deposited. Where its rocks are best exposed 
along the Pacific coast numerous small faults 
are observed, the displacement in many cases 



being but a few inches. The inclination of tlie 
beds is generally under 20° though in a few lo- 
calities the disturbance has been much greater 
and the dips increase* up to the vertical. Xeg- 
lecting these minor iiTcgularities the dominant 
structure is a broad anticline whose axis extends 
in a northwest-southeast direction approximately 
parallel with the Pacific and lake shores and a 
short distance southwest of the latter where the 
beds are a|>proximately horizontal. The greater 
poi*ti(>n of the region between the lake and the 
Pacific, therefore, is occupied by the western 
limb of the anticline and has prevailing south- 
west dips. From San Jorge to Lajas the dips 
are somewhat variable but generally to the 
northeast. The greater part of the eastern limb 
of the anticline is covered bv the lake. The nu- 
merous exposures of the Brito fonnation along 
the southern margin of the lake from the Sapoa 
to the Kio Orosi belong to this eastern limb of 
the anticline, and the beds have northeasterly 
dips of 5° to 30°. The strike of these beds is 
not strictly parallel with that of the beds on the 
Pacific coast. They converge slightly toward 
the northwest, indicating a pitch of the anti- 
cline in that direction. 

The exposures of the Brito formation are so 
infrequent and the dips are so variable that no 
satisfactorv' measure of the thickness of the for- 
mation can be obtained. Taking the observed 
dips between the Pacific coast and the lake shore 
the thickness exposed is estimated at about 
10,000 feet. This of course is not the total 
thickness of the formation, since the bottom is 
not exposed at the axis of the anticline. Also 
the fonnation has undoubtedly suffered an un- 
known but considerable diminution in thickness 
by erosion, and there are no data for determin- 
ing the thickness of strata which have been re- 
moved from the highest beds now obsen^ed. 



NICARAGUA CANAL COMMISSION 



APPENDIX 2, PLATE V 




THE BRITO FORMATION NEAR LA FLOP. 



Interbedded aandatone and shale ahowlng intersecting jolnta and 
concentric weathering. 



APPENDIX II.— GEOLOGIC REPORT 



117 



Utilization, — ilost of tlie ^JalKlstones of the 
Brito formation are too thin-bedded for utiliza- 
tion as building stone. This is the character of 
the beds exposed in the northern Brito headland, 
although a part of them at least might be util- 
ized for concrete and rip-rap work. Abont half 
a mile back from the coast a group of heavy 
sandstone beds occurs in the shales. Thev form 
a spur from the hills to the north extending 
out a short distance into the Rio Grande valley. 
These beds would probably yield a good quality 
of building stone. They would be easily quar- 
ried in dimensional blocks up to twenty or more 
inches in thickness: would dress readilv and be 
as durable as the average sandstone. 

Age of the Formation, — The greater part of 
the Brito formation is apparently barren of or- 
ganic remains. The only locations at which fos- 
sils have been found are on or near the Pacific 
coast. This, however, may be due to the fact 
that the rock exposures are not elsewhere of such 
a character as to fa(^ilitate the discover' of fos- 
sils, and the latter may possibly be more gener- 
ally distributed than present knowledge would 
indicate. The fossils are confined almost whollv 
to the limestones and marlv beds. Thev con- 
sist of corals, moluscan and foraminiieral re- 
mains. The latter are especially abundant. 
The rather meager collections have been sub- 
mitted to Dr. Dall for determination. He pro- 
nounces them Oligocene and probably identical 
with the foraminiferal beds described bv Hill 
from the Caribbean coast at Panama. One of 
the most abimdant forms is a small numulite, 
orbitoides, probably forbcsei which is character- 
istic of the lower Oligocene. The moluscan re- 
mains were collected on the Pacific coast about 
seventy-five miles northwest of Brito in what 
was supposed to be a higher portion of the same 
formation. Dr. Dall states that these have the 



upper Oligocene aspect though there are not 
enough of them to be conclusive. lie thus con- 
firms the view entertained in the field that suc- 
cessively higher beds in tlie Brito formation are 
exposed along the coast toward the northwest. 

In addition to the fossils on which is based 
the above conclusion concerning the age of the 
Brito formation it also contains rather abundant 
plant remains. They are in the form of drift- 
wood and coal, and as vet no remains sufficientlv 
well preserved for identification have been dis- 
covered. Associated with the coarser sandstones 
are numerous blocks of wooil whose rounded 
forms suggest that they are fragments of drift 
which were incorporated with the sand and 
gravel while it was accumulating. In some 
cases they still contain a large proportion of 
their original carbon, and in others this has been 
more or less perfectly replaced by silica or iron 
pyrites. The coal occui*s associated with the 
finer sediments, and although a careful search 
was made, the thickest seam observed was under 
half an inch. AVhile sufficient carbonaceous 
matter is sometimes disseminated through the 
shales to give them a black color, no indications 
were found pointing to the existence of work- 
able coal deposits in the region examined. 

Coal in workable quantity has been reported 
from the region southwest of the lake, between 
the lake shore and the Costa Rican volcanoes. 
The exact localitv is on the Rio Hacienda, 
twelve miles from its mouth. It was not visited 
and no samples of the coal were seen, so tliat the 
report lacks verification. There appears to be 
no reason, however, why conditions favorable 
for coal accumulation should not have prevailed 
in some portions of this region during the depo- 
sition of the Brito beds. 

Maciiuca Pormation. — Distribution. — The 
immediate margins of the San Juan valley from 



118 



NICARAGUA CANAL COMMISSION 



the lake eastward to Castillo are, so far as 
known, composed entirely of igneous rocks. 
From a point a few miles below Castillo to an- 
other midwav between ]\[achuca and the Boca 
San Carlos, tlie rocks are largely sedimentary, 
although they contain some igneous rocks in 
the form of small dikes. These sedimentary 
rocks constitute the Machuca formation. Its 
present extent is known only in the immediate 
vicinity of the river. The region south of the 
upper San Juan, foraiing the lower valleys of 
the Frio and Poco Sol, is geologically unex- 
plored. It is therefore possible that the Ma- 
chuca formation may extend westward through 
this region and be nearly, if not quite, contin- 
uous Avith the outcrops of the Brito formation 
south of the lake. TTntil this connection is es- 
tablished, however, the original continuity of 
the two formations is a matter of doubt. 

Lithologic Character. — The rock exposures in 
this region to the eastward of Castillo are veiy 
much less satisfactory than those along the Pa- 
cific coast; hence the character of the Machuca 
formation is not so well known as is that of the 
Brito. Like the latter, it appears to consist 
chiefly of calcareous shales with w^hich sand- 
stones are interbedded. The constituents of the 
rocks are largely igneous in their origin, but 
there are no coarse conglomerates or breccias 
such as occur in the Brito. Also no pure lime- 
stones or distinctly marly beds have been dis- 
covered, although the examination of the forma- 
tion has not been sufficiently exhaustive to en- 
able one to say that such beds do not occur. 

Structure, — (See general geological sections, 
Plate XVI.) The exposures are comparatively 
few in which the dip of the Machuca sandstones 
can be determined. At the Cano Bartola the 
dip is about 15° and to the north. At Machuca 
it is 20° and to the northwest. These dips sug- 



gest the presence of a synclinal basin, the south- 
em end of which is crossed by the San Juan. 
They are not sufficient, however, to locate its 
axis. Although in general the dips are light, 
the formation has suffered considerable local dis- 
turbance. Breccias, probably due to faulting, 
have been observed at several points, the best 
example being the ledge which projects into the 
river opposite the mouth of the Machuca. Also 
numerous sharp folds occur in the vicinity of 
Machuca. The same evidence of faulting and 
folding would probably be found elsewhere if 
the exposures were sufficiently abundant to ren- 
der the structure determinable. 

The rocks of the Machuca formation are gen- 
erally found deeply weathered. The weather- 
ing is hastened by the igneous constituents 
which they contain, and the final product is a 
residual red clay which is indistinguishable from 
the product of the decay of igneous rocks. Ex- 
cept for the fresh rock obtained beneath the 
residual mantle by means of the diamond drill, 
it would have been impossible to determine even 
approximately the limits of the sedimentary and 
igneous rocks. At some points, as at Machuca, 
the sandstone contains a very large pro|X)rtion 
of iron pyrites which by oxidation also tend to 
hasten its decay. 

Nearly everywhere the beds are intersected 
by numerous joint planes, the only marked ex- 
ception being the rather massive interbedded 
sandstones exposed on Machuca creek. Weath- 
ering has proceeded inward from the joints to- 
ward the centers of the rhomboidal blocks pro- 
ducing concentric shells about a central nucleus 
exactly as in the Brito formation. 

Utilization, — The beds of massive sandstone 
exposed on Machuca creek, being to a large ex- 
tent free from joints, could probably be quarried 
for dimensional building stone. This stone 



APPENDIX II.— GEOLOGIC REPORT 



119 



would be easily worked and fairly durable. The 
chief difficulty in quarrying would be the ex- 
tent of the stripping required which would 
doubtless be considerable. These are the only 
beds known in the region east of the lake from 
which dimensional stone could be obtained. 

Age of the Formation, — No fossils have as 
yet been found in the Maehuca formation which 
are sufficiently well preserv^ed for specific deter- 
mination. At Cruzita, one mile below Ma- 
ehuca, the core from the diamond drill hole in 
the bed of the river contains numerous indis- 
tinct organic forms. The rock is described by 
Dr. Ransome as an andesitic tuff containing 
fragments of limestone. The organic forms are 
revealed by the weathering of the rock with the 
removal of the soluble limestone, and they are 
also shown in the thin section under the micro- 
scope. While they cannot be identified, they 
strongly suggest the forms which occur so abund- 
antly in portions of the Brito formation. The 
beds in which they occur are evidently derived 
in large part from fresh volcanic tuff, though 
the latter was not so abundant as to prevent the 
growth of organisms in the sea in which it was 
being deposited. In the absence of conclusive 
fossil evidence, therefore, the age of the Ma- 
ehuca formation, so far as it may be determined, 
rests upon other and less satisfactory evidence. 
It is believed to be nearly or quite contempora- 
neous with the Brito formation, that is,01igocene 
(Tertiary). The grounds on which this con- 
clusion is based are briefly as follows: (1) 
There is a general similarity in lithologic compo- 
sition and appearance between the two forma- 
tions. (2) Both have suffered about the same 
amount of deformation, elevation and erosion 
since they were deposited. The value of this 
fact for correlation depends upon the proximity 
of the areas which they occupy and the evi- 



dence that the recent geologic conditions have 
been similar in both. (3) Both formations bear 
about the same relation to a group of igneous 
rocks which was in part contemporary with them 
and in part subsequently invaded their beds. 
The differences in composition of these intrusive 
rocks are not gi'eater than differences in igneous 
rocks within the same area which are known to 
be nearly or quite contemporaneous. (4) Fi- 
nally, as pointed out above, it is possible and 
even probable that the two formations are nearly 
or quite continuous through the southern part 
of the upper San Juan valley. 

In the vicinity of the Toro rapids, some dis- 
tance westward from the present limit of the 
Maehuca formation, a few siliceous boulders 
have been found which contain fossil remains. 
The original location of the beds from which 
these boulders are derived is not known, though 
they have probably not been transported a great 
distance. These fossils are unfortunately only 
casts. Thev have been examined bv Dr. Dall 
who savs thev " are not determinable, but have 
the general look of a fresh-water assembly.'' 
They are not regarded, however, as having any 
special bearing upon the age of the Maehuca 
since it is by no means certain that they have 
been derived from that formation. 

Tertiary Igneous Kocks.' — As stated above, 
the beds of the Maehuca fonnation occupy a 
broad belt which crosses the valley of the San 
Juan extending from a point a little below Cas- 
tillo eastward gome distance beyond Maehuca. 
While this formation contains a considerable 
proportion of volcanic material and is intersected 
by numerous dikes, it contains no lava flows and 



>The writer is indebted to Dr. F. L. Ransome, of the 
U. S. Geological Survey, for a petrographic examination of 
the igneous rocks collected in Nicaragua, and for the deter- 
mination of the rock species. Dr. Ransome's petrographic 
notes are appended to this report as Part III. 



120 



NICARAGUA CANAL COMMISSION 



no beds, the constituents of which are exclu- 
sively of volcanic origin. In the remainder of 
the countrv between the lake and the Caribbean, 
wherever the underlying rocks or their residual 
products rise above the 'recent alluvium of the 
flood-plains, the rocks are almost entirely of vol- 
canic origin. They present a great variety in 
structure and appearance, varying through the 
extreme types of volcanic products from dis- 
tinctly stratified beds of fine volcanic ash, 
through well-rounded conglomerates, fine and 
coarse angular breccias, surface lava flows and 
intrusive masses of rather coarsely holocrystal- 
line rock which did not reach the surface be- 
fore cooling. 

!Massive Igneous Rocks. — The principal va- 
rieties of igneous rocks which are found between 
the lake and the Caribbean are augite andesite, 
olivine basalt, hypersthene basalt and dacite. Of 
these four varieties the first three are very simi- 
lar in appearance. They belong to the class 
commonly designated as trap rocks. They are 

• 

dark bluish-gray to black in color; generally 
fine-grained but often containing certain min- 
erals as olivine and feldspar which can be read- 
ily distinguished Avith the unaided eye. They 
are generally compact and heavy, though a well- 
marked vesicular structure characterizes some 
portions of the basalt. The red clay which is 
the final product of their decay contains numer- 
ous residual boulders of the fresh rock covered 
wdth a thin ocherous crust. 

The dacite is light gray in color and is made 
up of abundant quartz and feldspar crystals em- 
bedded in a fine-grained or glassy, gray ground- 
mass. It is lighter than the trap rocks and is 
considerably softer, even when entirely unweath- 
ered. The dacite contains numerous fragments 
of darker basic rocks. It doubtless reached its 
present position as a lava flow, and these inclu- 



sions are fragments of the underlying rock 
which were picked up and incorporated in the 
molten mass during its passage through the 
lower formations to the surface. Many of them 
are a soft greenish rock exactly like the tuff on 
which the dacite rests. The presence of these 
included fragments of a different rock is doubt- 
less the reason the dacite was called conglomer- 
ate in the Canal Company's Eastern Divide sec- 
tions. Of the fragmental igneous rocks two 
classes may be made, according as their igneous 
or sedimentary characteristics are the more 
prominent. In the first class are included the 
tuffs which form the western portion of the 
Eastern Divide, passing under the dacite at an 
angle of about 5°. This tuff is related to a 
basic lava either andesite or basalt. It has a 
dark greenish color and very fine grain. It is 
soft and talcose, and on exposure to the air the 
cores generally crumble into small fragments. 
While this tuff owes its kaolin-like character to 
the decomposition of a basic glass, it was prob- 
ably never a hard rock. The pressure to which 
it has been subjected since its deposition has apn 
parently not been sufiicient to produce complete 
induration. 

The extent to which these rocks have weath- 
ered has been already pointed out, but may be 
referred to again in explanation of the difficulty 
which has been experienced in determining the 
relations of the various members of the volcanic 
formations. All weather to a red clay, and ex- 
posures which afford any indication of the origi- 
nal character of the underlying rock are ex- 
tremely infrequent. The chief reliance must 
be placed upon the occasional residual boulders, 
upon the presence or absence of quartz grains 
in the clay and upon the occassional cut banks 
along the streams. The large-scale sections of 
the proposed dam sites which are published with 



APPENDIX II.— GEOLOGIC REPORT 



121 



this report, indicate the complexity of the rela- 
tions between the various volcanic formations, 
and the hopelessness of attempting to work out 
these relations from surface indications alone, 
without tlie aid of sections derived from drilling. 
For the reasons given above it is practically im- 
possible to map the surface outcrops of these va- 
rious rock varieties. Their distribution can only 
be indicated in a general way. 

The rock forming tlie hill on which San Car- 
los is located consists of augite andesite. This 
extends eastward down the river to the Rio 
Melchorita forming the hills which rise above 
the level alluvial plains. At Palo de Arco oc- 
curs olivine basalt, and this rock continues east- 
ward a short distiince bevond Castillo. At the 
Savalos it presents an amygdaloidal phase, and in 
the hill near the mouth of the Santa Cruz it con- 
sists of a veiy coarse breccia. The high hills at 
the junction of the San Carlos with the San 
Juan consist of hyperstheno basalt This is a 
holocrj'stalline rock and one which probably 
cooled at some distance below the surface. It 
may possibly mark the center of eruption from 
which lavas in the surrounding region, which 
have a similar composition but less perfect crj^s- 
talline structure, were derived. A similar but 
less crystalline rock also occurs in the hills on 
the north side of the San Juan river. To the 
eastward at Oclioa the hyperethene basalt occurs 
south of the river, while the rocks at the river 
bank on both sides and extending to the north- 
ward are olivine basalts. This olivine basalt ex- 
tends eastward bevond the San Francisco hills. 

t' 

At the Tambor Grande it is replaced for a short 
distance by dacite, then in the Tamborcito hills 
by hypersthene basalt, but again comes in in the 
Sarapiqui hills and thence extends eastward 
forming all of the hills which border the lower 
portion of the San Juan river and also those 



about Silico lake. The dacite, while it does not 
reach the surface at Ochoa, was encountered 
there in boring. It was also found at lower 
Ochoa beneath a bed of volcanic tuff or breccia 
and some unconsolidated sediments. It comes 
to the surface at Tambor Grande and is probably 
continuous northward in the high ridge connect- 
ing the Tambor Grande hills with the Eastern 
Divide. It forms the surface through the 
higher portion of the Eastern Divide overlying 
andesitic tuffs and passing under basalt. 

Fragmental Igneous Rocks. — Since the 
closely related fragmental rocks, both the bed- 
ded tuffs and the conglomerates, do not weather 
in such a way as to furnish residual boulders, 
their presence is much more difficult to detect. 
From the character of the exposures in the bluffs 
along the San Juan river, and from the results 
of the drill sections, it seems probable, however, 
that the bulk of these fragmental rocks is as 
great or greater than that of the massive rocks. 
About four miles above the Boca San Carlos 
these beds are exposed in a high bluff on the 
north bank of the river. There is shown a con- 
siderable diversity in the character of the ma- 
terial, varying from the finest tuff to coarse 
rounded conglomerate. All parts of the beds 
are equally weathered, forming a tough clay 
quite free from grit. The different beds vary 
considerably in color, although the prevailing 
colors consist of various shades of red and brown. 
The planes of stratification between the differ- 
ent beds are not sharply marked, and the indi- 
cations are that the deposit was made rather 
rapidly and in the presence of strong currents. 
Similar exposures of thoroughly decayed sedi- 
mentary beds occur in the river bluffs at various 
points between Ochoa and the mouth of the San 
Francisco. 

It is probable that during the extrusion of the 



122 



NICARAGUA CANAL COMMISSION 



volcanic rocks in this rcpon numerous hodies of 
water were formed by the interruption of drain- 
age lines by the lava flows. In these bodies of 
standing water the finer tuffs were accumulated 
with considerable regularity in their planes of 
stratification. Forests were present on the ad- 
joining shores and much vegetable^ matter was 
accumulated along vdth these silts. There thus 
resulted deposits of considerable <l(»])th such as 
those encountered at lower Ochoa (see Fig. G, 
Plate XVTI). These were subsequently covered 
by lavas or deposits of f ragmen tal material but 
have never been buried sufficiently deep to bring 
about their complete consolidation. In some 
places conditions were favorable for the deposi- 
tion of calcareous material. In the section at the 
San Francisco a bed of very fine-grained (»arthy 
limestone about three feet in thickness was en- 
countered with fine volcanic tuff al)Ove and be- 
low. The limestone was ])erhaps originally a 
calcareous mud which has lx»en thoroughly solidi- 
fied and is now comparatively hard. The adja- 
cent tuffs both above and below may have been 
solidified at one time but are now soft and tal- 
cose. No traces of organisms can be detected 
in this limestone, and it may have been precipi- 
tated from solution without the intervention of 
life. In the railroad cut near Silico lake there 
occurs a bed of clay enclosing water-worn peb- 
bles and numerous fragments of wood which is 
immediately overlain by a flow of basaltic lava. 
This clay was doubtless alluvial or accumulated 
in a lake and has probably not been buried to a 
sufficient depth to produce consolidation. 

The beds of lava and volcanic tuff above des- 
cribed have been but little changed from the po- 
sition in which they were originally deposited. 
Wherever bedding planes can be detected in the 
stratified tuffs, they are practically horizontal. 
The planes separating lava flows generally have 



a decided original inclination, and this may be 
increased or diminished by subsequent tilting. 
In the sections of the upper and lower Ochoa 
dam sites (Figs. 5 and fi, and Plate XVII) the 
planes separating the several formations have a 
slight dip to the northeast. The same thing is 
observed in the sections of the San Francisco 
embankment line and of the Eastern Divide 
(Figs. 1 to 4 and 0, and Plate XVIII). Inso- 
far as these dips are due to deformation, they 
suggest the ])resence of a low anticline to the 
east of the Machuca basin, its axis approxi- 
mately parallel with the Caribbean coast and 
crossing the San Juan near the Boca San Carlos. 
For reasons given above, the structure of these 
igneous fonnations as well as of the Machuca 
sandstone shown on the geological sections, Plate 
XVI, rests on a verv few observations and 
should not be accepted with too great confidence. 
TiKCENT Alluvial Formations. — The post- 
Tertiary formations of the region include the 
recent deposits which make up the flood-plains 
of the rivers and the delta plains about their 
mouths, together with the products of the recent 
volcanic activitv. 

ft 

The character of the alluvium has been some- 
what fully described in a previous section of this 
report and requires but little further mention. 
It varies in character with the local conditions 
imder which it is deposited and with the char- 
acter of the rocks from which it is derived. On 
the west side, filling the valley of the Rio 
Grande, it consists of fine brown sand and clay, 
derived from the decay chiefly of the sandstones 
of the Brito fcnnation. In some places it con- 
tains enough calcareous cement, which has been 
deposited by infiltration from above, to give the 
alluvium a fair degree of coherence. 

In the vallev of the San Juan there is con- 
siderablv wider diversitv in the character of the 



APPENDIX II.— GEOLOGIC REPORT 



123 



alluvium. In the upper portion of the valley 
it consists of fine blue clav interbedded with 
fine blue and brown sand. The sand occurs 
chieflv in the river channel and is the residuum 
which the sluggish current of the river has been 
unable to transport. It is probable that but 
little sand would be encountered in the alluvium 
at any considerable distance from the present 
channel. In the lower portion of the valley the 
alluvium in the immediate vicinitv of the river 
contains considerable black sand, such as it is at 
present transporting in gi'cat volume. This oc- 
curs either disseminated through the finer silt 
which is derived from the decav of rocks in the 
adjoining region, or it occurs as distinct layci*s 
interstratified with the clay. The presence of a 
considerable proportion of sand in the silt ren- 
ders it much firmer than when the latter con- 
sists chiefly of clay. The sand does not extend 
to any great distance from the present river 
channel, and hence the silt becomes less stable 
with increasing distance from the river. The 
material which fills the tributary valleys, such 
as the Danta, the San Francisco, the Cureno and 
the Tamborcito, is a fine silt, generally quite 
free from grit, with a blue color, and containing 
abundant fragments of wood and leaves. When 
this material is thoroughly drained it becomes 
fairly compact, as shown in the vertical banks 
of the most of the streams, but at some distance 
from these streams, where the drainage is im- 
perfect, it is quite soft to a depth of 25 to 50 
feet. This alluvial silt or mud when first ex- 
posed sometimes has a brilliant blue color which 
quickly changes to a yellowish brown on expo- 
sure to the air. In some cases the change in 
color takes place at the exposed surfaces within 
a few minutes after the air has access to them. 
The material forming the delta plain of the 
San Juan is similar to that composing its flood- 



plains. The black sand is carried out to sea and 
transported along the shore by littoral currents 
and thrown up to some distance above tide level 
by the waves, so that within a belt two or three 
miles broad along the coast, the surface is com- 
posed chiefly of black sand with a small amount 
of vegetable mould. The fine silt increases in 
thickness from a feather-edge at its outer margin 
at a rate somewhat greater than the eastward 
slope of the delta plain. It is probable that the 
delta has always been fringed by a belt of sand 
which never rose more than a few feet above 
sea level. The region, however, has been sink- 
ing while the delta was forming. As the delta 
grew by accretions of sand to its outer margin, 
the corresponding growth upon its surface was 
made by the fine silt deposited from the flood 
waters of the rivers. The plane separating the 
sand from the overlying silt thus appears to have 
a gentle landward inclination, being slightly 
above sea level at the present coast and some 
distance below sea level toward its inner margin. 
Recent Volo.vnio Rocks. — The vulcanism 
which gave rise to the igneous rocks associated 
with the Tertiary sediments appears to have be- 
come entirely extinct in this region, and doubt- 
less a long interval elapsed in which it was free 
from any manifestations of volcanic activity. 
In comparatively recent times the vulcanism 
was renewed, and its products form the Costa 
Rican and Nicaraguan volcanic ranges which 
have already been described. Its products also 
form the Jinotepe plateau and the plain of Leon 
which extend northwestward from the great 
lakes to the Pacific. In mineralogical composi- 
tion these recent volcanic products consist very 
largely of hypersthene andesite. The last erup- 
tion from Masaya was a basaltic lava, and a 
comparatively recent lava flow from Ometepe is 
also a basalt With these two exceptions the 



124 



NICARAGUA CANAL COMMISSION 



recent activity so far as obson-ed has given rise 
only to andesitic lavas and tuffs. The cone of 
Ometepe consists largely of lapilli with occa- 
sional interlaminated lava flows. The lapilli 
consist in about equal parts of black or gray 
pumice and of black glassy rock which has been 
thoroughly shattered and ground up by explo- 
sive eruptions. The tuffs from this volcano 
which have been carried to a considerable dis- 
tance from the center of eruption, chiefly by 
wind, are composed more largely of tufaceoua 
material. The materials erupted from the other 
volcanic centers forming the various peaks of 
the Nicaraguan range appear to be similar in 
composition to those found in Ometepe. The 
Jinotepe plateau is composed largely, if not alto- 
gether, of volcanic tuffs which probably reached 
their present jjosition in the form of a more or 
less fluid mud. This mud becomes solidified, 
but never sufficiently so to form hard rock. It 
is quarried in many places and used as a build- 
ing stone. It can be readily cut out with a 
pick, but becomes somewhat harder on exposure 
to the air. The rock fragments which consti- 
tuted this tuff vary widely in size from large 
boulders several feet in diameter to the finest 
dust. They are all angular, and in this respect 
they differ from the volcanic conglomerates as- 
sociated with the Tertiary rocks of the San Juan 
valley. A further difference is the almost com- 
plete absence of stratification and sorting of the 
rock constituents. This tuff appears to have 
been sufficiently fluid to flow upon rather low 
slopes and the present southward and westward 
slopes of the Jinotepe plateau are probably the 
original constructional slopes. In the vicinity 
of Managua planes separating successive mud 
flows intersect the rock and are utilized in 
quarrying. In these quarries human tracks 
have been found in the rock where they were 



made while it was still in the form of mud. 
They prove the recency of the tuffs and indicate 
something as to its physical condition when first 
deposited. At the margin of this plateau the 
tuff is found filling the valleys in the older for- 
mations and smoothing out the former irregu- 
larities of the topography. In many cases the 
present streams have in part re-excavated the 
old valleys, though not to their original width. 
The vertical cliffs surrounding the caldera 
lakes, Apoya and Masaya, display the underly- 
ing structure of this plateau near the centers 
from which its material Avas derived. These 
cliffs are composed of alternating layers of tuff 
and solid lava flows. It is impossible to say how 
far from the centers of eruptions these lava 
flow^s extend, but the distance is probably not 
very great. Near the centers of eruption the 
character of the tuff is somewhat different from 
that at greater distances. It is less homogene- 
ous in character and frequently consists of 
sharply-defined alternating tuff beds which 
differ widely in appearance. In the bluffs sur- 
rounding Lake Apoya this is well shown. Nu- 
merous distinct bands of white pumice occur 
interbeddcd with dark lapilli and fragmental 
rocks, and these in turn are interbedded with the 
lava flows. 

ROCK DECAY. 

Importance of the Surtect. — One of the 
features which first impresses the geologist or 
the engineer in Nicaragua is the extent to which 
the surface rocks are weathered. This feature 
is common to all tropical regions, at least to 
those in which there is an abundant rainfall. 
While the extent of rock weathering has an im- 
portant bearing on the geology of the country, 
and thus a high degree of scientific interest, it 
is a fact of prime importance to the engineer in 



APPENDIX II.—GEOLOGIC REPORT 



125 



planning any structures in this region. It en- 
ters directly into the cost of excavation and also 
into the cost and permanence of foundations for 
all heavy structures. The weathering of rocks 
is effected by two processes which should be 
carefully discriminated. These are rock disin- 
tegration and rock decay. By the first a rock is 
broken down to smaller masses or even to its 
constituent minerals without the alteration of 
the minerals themselves. The most active 
agents are changes of temperature and the ex- 
pansion of interstitial water by freezing. Hence, 
in general, the activity of the process varies with 
latitude and in the humid tropics where the 
range in temperature change is slight, the effects 
are practically reduced to zero. By the second 
process the constituent minerals themselves un- 
dergo alteration and, as will be more fully 
pointed out below, the active agents are the 
acids derived from the decay of organic matter. 
Hence this second process varies inversely with 
latitude, being most active in the humid tropics 
and reduced to zero in the arctic regions. 

It should be noted that it is the first of these 
processes, rock disintegration, which is chiefly 
inimical to the permanence of structures and 
hence that their relative durability is greater in 
the tropics than in higher latitudes. 

CoNDiTioxs Favoring Rock Decay. — It has 
been shown by various investigators that the 
conditions most favorable to rapid rock decay, 
and hence to the accumulation of an extensive 
mantle of residual materials, are high tempera- 
ture and abundant moisture. These conditions 
are only indirectly responsible for a large part 
of the rapid rock decay which always accompa- 
nies them. They are also the conditions on 
which the rapid growth and decay of a luxuriant 
vegetation depends, and it is the latter process 
which is chiefly instrumental in hastening the 
process of rock weathering. 



It is manifest that heat alone without mois- 
ture does not give rise to conditions which favor 
rock decay, for it is a common observation in 
desert regions where the temperatures reach the 
maximum, that rocks are disintegrated to a lim- 
ited depth by the alternate expansion and con- 
traction due to changes in temperature, but that 
rock decay is practically absent. On the other 
hand, abundant moisture and continuous low 
temperature do not give conditions favorable for 
rock decav since these conditions favor the ac- 
cumulation of ice and snow. Glaciers are effec- 
tive instruments for transportation of rock debris 
and to a limited extent are efficient as eroding 
agents, but practically no rock weathering goes 
on in their presence. 

Even where the moisture is abundant and the 
temperature is sufficiently high for the growth 
of an abundant vegetation, unless the conditions 
are also favorable for the decay of that vegeta- 
tion they are not favorable for rock weathering. 
This is seen in the extremely luxuriant forests 
of the north Pacific coast, where the successive 
generations of forests grow upon the remains of 
their predecessors. The conditions are here 
favorable for the preservation of vegetable re- 
mains in the form of peat, and rock decay is 
practically absent. It appears, therefore, that 
an essential condition for rapid rock decay is the 
rapid decay of abundant vegetable matter, and 
this leads to the conclusion that the most effi- 
cient factor in the process is the presence of the 
complex organic acids which are derived from 
the decay of vegetation. 

Effect of Chemical Coin position. — The depth 
to which the rock decay has gone and the char- 
acter of the products depend in a considerable 
measure upon the chemical composition of the 
rock, upon its original j?tructure and upon the 
subsequent alterations which it has under- 
gone, such as fracturing in the process of 



126 



NICARAGUA CANAL COMMISSION 



consolidation or by subsequent d^Tiamic disturb- 
ances. But few rocks are found in this region 
wliicb are not either wholly or in large part com- 
posed of material of volcanic origin. Hence 
their chemical composition does not present so 
wide a range as is usually foimd among sedi- 
mentary and igneous rocks. A few are appar- 
ently the products of thermal springs, and the 
composition of these is perhaps the best suited 
of any to resist the process of rock decay. Ex- 
amples of rocks of this origin are found in the 
small hill opposite San Francisco, a short dis- 
tance east of the lake and also at CHiorrera on 
the Aguas ^[uei*tas. These arc composed 
chiefly of silica Avhich is the mineral least acted 
upon by the processes to which rock decay 
is chiefly due. The ifachuca sandstone, as al- 
ready explained, contains a large proportion of 
feldspathic minerals as well as iron sulphide and 
carbonate of lime. Hence it is peculiarly sus- 
ceptible to hydration, oxidation and solution. 
The igneous rocks belong to the basic and inter- 
mediate classes and hence contain a large pro- 
portion of the lime-soda feldspars and the ferro- 
magnesium minerals. Both of these groups of 
minerals are especially liable to alteration. 
Quartz, on the other hand, is relatively scarce. 
There are in the region no quartzites and argil- 
lites, the two classes of rocks which are especi- 
ally indifferent to the action of the weathering 
processes. Certain beds associated with the 
lavas are composed of fine volcanic^ ash in which 
the constituent particles had never acquired a 
crystalline structure but were entirely glassy. 
These are perhaps the most rapidly altered rocks 
in the region, and wherever they have been en- 
countered, even as in the (^astern division at very 
great deptlis beneath the thick sheet of dacite, 
they are found in the form of a soft soapy or 
talcose rock. 



The rocks of the Brito formation contain a 
much smaller proportion of igneous constituents 
than any of those in the eastern division. Hence 
they are in a measure free from this source of 
weakness. They contain, however, a large pro- 
portion of lime carbonate, and in them the 
weathering process consists chiefly in the solu- 
tion and leaching out of this cementing material. 
Tn most of these rocks the lime forms so small a 
pro])ortion of the entire mass that the bulk is 
not diminished or the structure altered by its 
removal. The rock merely changes in color 
from bluish gray to brown or yellow and at the 
same time bcM^onies soft and porous. 

Effect of Original Structure. — The original 

structure of manv of the rocks is such as to 

I. 

facilitate weathering to a considerable degree. 
This is especially tnie of the basalts which are 
largely composed of surface lava flows and have 
the vesicular structure which is characteristic of 
such flows. In manv cases it is observed that 
the degree of weathering in the case of basalts 
varies directlv with the extent of the vesicular 
structure. The up|x*r and lower surfaces of the 
flows which were rapidly cooled by contact with 
the underlying rocks and by exposure to the 
air, contain more or less abundant gas bubble-, 
while their central portions are relatively com- 
pact. Tn such cases it is foimd that the vesicu- 
lar portions are .thoroughly weathered, w^hile the 
interior compact portion contains large boulders 
of fresh rock or continuous beds of the same. 
The dacite which so far as obsen'ed never has 
the vesicular structure of the basalt, does not 
show these striking differences in the degree to 
which its different portions have weathered. 
The depth of weathering in the volcanic san<l- 
stones and conglomerates naturally depends 
largely upon the original structure of their con- 
stituents which shows considerable variation. 



APPENDIX II.— GEOLOGIC REPORT 



127 



Thus the conglomerate encountered at upper 
Ochoa is composed chiefly of pebbles of com- 
pact fine-grained basalt and is weathered only to 
a moderate depth. A conglomerate was en- 
countered at lower Ochoa similar to the above, 
except that its constituent pebbles arc largely 
composed of vesicular or pumiceous basalt. This 
diflFerence in the composition of the pebbles is 
accompanied by a corresponding difference in 
the depth of weathering which has extended to 
a very great depth in case of the latter rock. 

Effect of Secondary Structures, — A third im- 
portant factor in determining the depth to which 
rock decay has gone is the extent to which tlie 
rocks have been affected by dynamic agencies 
with the production of secondary structures, 
puch as folds, faults and joint planes. Of these 
effects jointing is perhaps the most important 
It pervades all the rocks of the region, both ig- 
neous and sedimentary. The joints which in- 
tersect the igneous rocks are perhaps largely 
due to shrinkage on (.*ooling. The regular pris- 
matic jointing common in basaltic lava flows 
has not been observed in this region. In its 
stead is a system of more or less regular joints 
which divides the rock into large rliomboidal 
blocks. The loss basic rocks, such as the dacite, 
and the volcanic conglomerates are nearly or 
quite free from these joints, and the manner in 
which thev weather is therefore different from 
that of the basalt. 

The sedimentary formations are generally 
very d(»eply fractured. In these the joints are 

doubtless due to the action of dvnamic forces 

« 

which, while tliey have not greatly changed the 
original position of the beds, have been sufficient 
to thoroughly shatter them to great depths. 
Onlv a few of the more massive beds of sand- 
stone have in some measure escaped this gen- 
eral fracturing. Its effect is most pronounced 



in the less massive portions of the Brito forma- 
tion. At the surface the joints have been en- 
larged by the weathering process, and the rock 
consists of a loose mass of small fragments. 
This condition prevails to a depth of more than 
a lumdred feiet from the surface, as shown by 
the boring at La Flor. One effect of the joint- 
ing of the rocks is to make it nearly impossible 
to obtain a core with the diamond drill. This 
fractured calcareous shale is the material which 
has been termed " telpetate " and " cascajo " in 
the reports of the drilling done by the Canal 
Company. In some cases it was obsen^d that 
the cracks which intersected the rocks had sub- 
sequently been healed up by the deposition of 
calcite. This, however, is not general at ordi- 
narj' depths. 

A direct consequence of the presence of these 
cracks intersecting the rocks is the development 
of secondary concentric structures. The crackS 
permit the percolation to great depths of surface 
waters bearing the agents which are most active 
in rock decay. The weathering proceeds out- 
ward from these joints with the production of 
successive concentric lavers about a central nu- 
cleus. The concentric stnictures which have 
already been described were thus produced. 

KocK Decay in the Eastern Division. — As 
has been already pointed out there is a marked 
difference in the distribution of the rainfall on 
opposite sides of the isthmus with a corresjx>nd- 
ing difference in the character of the vegetation 
and in the extent and products of rock decay. 
It will be necessary, therefore, to consider the 
process and tlu* products in the two divisions of 
the isthmus separately. 

The eastern division is characterized bv a 
heavy rainfall, so distributed throughout the 
vear that there is no well-marked dr>' season. 
Hence the surface soil is never permitted to be- 



128 



NICARAGUA CANAL COMMISSION 



come dry, and the forest litter is never removed 
bv fires. The entire surface is covered with a 
dense mantle of vegetation. This consists of a 
heavy forest growth except where the land sur- 
face has been so recently reclaimed from swamps 
and lagoons that it has not yet been invaded by 
the forest, or that its surface is not sufficiently 
firm to support forest trees. Even where the 
forest does not extend, the smaller vegetation is 
extremelv dense, and the surface is even more 
eflFectually protected than under the forest. It 
may be stated in general, however, that all of 
the land which rises above the margins of the 
extensive flood-plains and the silt-filled valleys, 
that is, all which is underlain by rocks older than 
the recent silt, is forest-clad. The canopy of 
foliage formed by the tree tops is so perfect that 
much of the light and all of the direct sunlight 
is intercepted, hence the smaller vegetation at 
the surface is not exceptionally luxuriant and 
only partially covers the surface. 

The forest trees of this region are nearly all 
deciduous, but the season of shedding their foli- 
age is different for different species ; hence there 
is a continuous supply of forest litter through- 
out the entire year, and its decay not being 
checked by frost is a continuous process. 

All rocks of this eastern division show the 
effects of weathering to great depth, not only 
the igneous but the sedimentary rocks as well. 
In the course of the drilling operations which 
were carried on in this region, a large amount 
of data was obtained concerning the depth to 
which decay has gone in rocks of various origin 
and composition, and also the products of the 
weathering. The sections which were obtained 
by means of the drill arc so numerous that only 
a few typical examples have been selected for 
publication in detail in this report. The infor- 
mation obtained in all is of course embodied in 



the various sections which have been prepared 
for the use of the engineers. These sections 
which appear in Plates VIII to XIV will be re- 
ferred to for the purpose of illustrating the 
statements here made concerning the process 
and products of rock decay. 

Products of Rock Decay. — The final pro- 
duct of rock decay in this region is a red clay. 
This represents the complete oxidation of all the 
constituent minerals of the rock except the 
quartz, and the complete obliteration of the 
original rock structure. From this extreme the 
products of rock decay present all possible gra- 
dations to the perfectly fresh rock. While there 
are no sharp lines of demarkation between dif- 
ferent phases of the rock weathering, the pro- 
ducts may be conveniently, though somewhat 
arbitrarily, separated into three groups, namely, 
red clay, blue clay and soft rock. The first two 
differ chiefly in the degree of oxidation, and the 
second differs from the third chieflv in the ex- 
tent to which the original structure of the rock 
has been obliterated. The third group itself is 
not sharply separated from the fresh rock but 
passes into it in most cases by imperceptible 
gradations. 

Red Clay. — As already stated, in the eastern 
division of the region under discussion, all por- 
tions of the surface which rise above the mar- 
gins of the alluvial flood-plains, are covered with 
this final product of rock decay. 

Its appearance and doubtless also its compo- 
sition vary somewhat from place to place. The 
bright red is varied by shades of yellow, b^o^vn 
and occasionally olive green, but the prevailing 
tint is nevertheless very generally red. The 
abrupt change in color between the residual 
clay and the adjacent alluvial clay is very strik- 
ing. The latter is never red, but is always some 
shade of gray or blue. The only essential dif- 



APPENDIX II.— GEOLOGIC REPORT 



129 



ference between the two clavs is in the form of 
their iron. In the alhivium this is in the fer- 
rous state, forming light-colored compounds. 
In the residual clay it is in the ferric state, and 
not only more highly oxidized but the oxide is 
in large measure dehydrated, giving the bright 
red color of hematite. The cause of this differ- 
ence in the state of oxidation in clays which ap- 
pear to be affected by the same conditions, is 
doubtless the different amounts of organic mat- 
ter incorporated Avith them. As already des- 
cribed, the residual clay is very compact. , It is 
never loosened by frost or by shrinkage cracks. 
The only means by which vegetable matter 
finds its way below the surface is by growing 
roots and insect burrows. The amount thus in- 
troduced is not sufficient to niateriallv affect the 
chemical conditions within the zone of rock de- 
cay. The vegetable matter at the surface is so 
rapidly and thoroughly oxidized that the or- 
ganic compounds which result from the process 
are not effective reducing agents when they per- 
colate downward in contact with the red clav, 
but probably carry an excess of oxygen which is 
expended in the oxidation of the rock constitu- 
ents below. In the alluvium, on the other 
hand, the vegetable matter while only rarely 
constituting a large proportion of the mass, is 
thoroughly disseminated through it and con- 
trols the chemical conditions, preventing the 
oxidation of ferrous compounds and reducing 
X ferric compounds to the lower state of oxidation. 
Before the deposition of the alluvium which 
now fills the valleys of the region, the bottoms 
of these valleys were covered with residual clay 
the same as that now covering the hills. This 
clay underlying the alluvium and subjected to 
the constant downward percolation of the redu- 
cing solutions from the latter has generally, 
though not always, lost its red color. It is often 
9 



found to be mottled with blue patches where the 
reducing solution has gained access to the ferric 
oxide. 

Doubtless the proportion of silica, alumina and 
iron depends to some extent on the composition 
of the rock from which the clav was derived, but 
this variation is not sufficient to produce marked 
differences in its appearance and pliysical prop- 
erties. The depth of this upper division is not 
very great, usually from ten to thirty feet. The 
separation between the red clay and the under- 
lying blue clay is usually rather sharp, although 
in many cases there is a band of mottled clay 
between the two. 

Blue Clay, — This division is usually some- 
what thicker than the overlying red clay. 
While its prevailing color is blue, it varies from 
white to various shades of yellow and brown, 
depending largely upon the original composi- 
tion of the rock from which it was derived. It 
represents the zone of complete rock decay and 
disintegration but incomplete oxidation. The 
blue color is due not to the presence of a redu- 
cing agent but to the absence of a sufficient oxid- 
izing agent to convert the iron into the higher 
oxides. It generally contains more or less 
abundant fragments of thoroughly weathered 
rock which retain their original structure, and 
where it is derived from basalt it usuallv con- 
tains numerous boulders of fresh rock, the nu- 
clei about which concentric weathering has 
taken place. The lower limit of the blue clay 
division is often more indefinite than its upper 
limit. By an increase in the number and size 
of the rock fragments, both fresh and weathered, 
it passes into the zone of soft rock. As will be 
readily seen, the point at which the division 
should be drawn is, to a large extent, arbitrary, 
since the distinction is at best only one of degree. 

Soft Bock, — The red clay contains but few of 



130 



NICARAGUA CANAL COMMISSION 



the characteristics of the rock from wliich it was 
derived, hence it is fairiy uniform throughout 
the region. In the blue clay, also, the original 
character of the rock is almost entirely obliter- 
ated and it is therefore somewhat uniform. In 
case of the soft rock, however, in so far as it re- 
tains the original structure of the rock from 
which it was derived, it presents the same diver- 
sity as the hard rocks of the region. In some cases 
this division is wanting and the blue clay ex- 
tends entirely down to the fresh rock. This is 
the case with the Machuca sandstone as shown 
in the sections 1 and 2, Plate XIV. In other 

cases the blue clav is thin or absent and there 

*• 

is a great thickness of soft rock. This is the 
case with the dacite as shown at Tambor 
Grande in sections 1 to 3, Plate X. 

The material classed as soft rock represents 
the zone of practically complete rock weathering 
but of incomplete rock disintegration. The 
forms of the constituent minerals can usually 
be made out in rocks which were originally 
coarse-grained. The original structure is gen- 
erally well presei'\"ed. In the vesicular lavas 
the gas cavities are nearly as perfect as in the 
hard rock. In the volcanic conglomerates and 
breccias the distinction of matrix and inclosed 
pebbles or angular fragments is perfectly sharp. 
Yet all the material included in this class can 
be cnmibled in the Angers. 

The extensive beds of fine basaltic and andes- 
itic tuff which occur in the Eastern Divide and 
elsewhere are perhaps the most easily altered 
rocks in the region. There is some doubt as to 
their ever having been thoroughly consolidated, 
and this may account for the depth to which 
they are weathered. Wherever found, even 
under a great mass of compact, fresh dacite, the 
tuffs are soft and talcose, resembling a very- 
compact, structureless clay. The principal al- 



teration which the material appears to have un- 
dergone is hydration. It can be easily cut with 
a knife, and on exposure to the air it loses 
water and is intersected bv numerous cracks. 
If thoroughly dried and then immersed in water 
it immediately crumbles to a fine, incoherent 
sand. This material has not been placed in the 
class with the soft rock although it might prop- 
erlv be so classed. Since the classification 
shown on the sections was made w^ith a view to 
its practical application to engineering prob- 
lems, the upper limit of hard rock does not gen- 
erally correspond with the limit of rock weather- 
ing from the surface downward. The rock 
classed as hard usually shows more or lees altera- 
tion of its constituent minerals, but not enough 
to affect their coherence. While this incomplete 
weathering does not materially affect the exca- 
vation of the rock, it becomes very important 
and should be carefullv considered when the 
rock is intended for use in construction. Rock 
which appears to be perfectly fresh when first 
removed from the quarry often contains many 
incipient fractures, and these develop rapidly on 
exposure. It is probable, as will be pointed out 
later, that all of the tuff and a considerable pro« 
portion of the dacite in the Eastern Divide cut 
would develop this weakness on exposure and 
hence w^ould be entirelv unsuited for structural 
purposes. 

Rock Decay in the Western Division. — 
Turning now to the western division the phe- . 
nomena of rock decay arc found to be strikingly 
different, and, as already pointed out, this prob- 
ably depends largely on climatic differences 
which prevail on opposite sides of the isthmus. 
The most striking difference is the almost com- 
plete absence of red color in the surface soils. 
This change in color coincides so exactly witli 
the change in climatic conditions that it is diffi- 



APPENDIX II.— GEOLOGIC REPORT 



131 



cult to escape the conclusion that the change in 
color is due directly to climatic causes. The 
prevailing color in the surface soil in the region 
west of the lake is a bluish-gray, varying to 
black. It is sometimes a yellowish-gray and 
very rarely red. One reason suggested for the 
absence of the complete oxidation of the surface 
soil and the consequent red color is the greater 
amount of vegetable matter which becomes in- 
corporated with the upper layers of the soil. 
As pointed out in the discussion of the climate 
it was shown that the surface is alternately 
baked and saturated with water. The numer- 
ous cracks which form during the dry season 
collect leaves and twigs, and when the cracks are 
closed up by the moistening of the soil this vege- 
table matter is thoroughly incorporated with the 
clay to a very considerable depth. It may be 
that it is present in sufficient quantity to com- 
bine with all the oxygen which is carried down 
by the percolating waters and thus prevent the 
oxidation of the iron contained in the underly- 
ing rocks. This reducing action of the con- 
tained vegetable matter prevents the oxidation 
of the iron contained in the alluvial silts in the 
eastern division, and there seems no reason why 
it should not be equally effective in preventing 
oxidation in the residual clays in the western 
division. 

Another difference at once noted is the ex- 
tent to which rock decay has extended. The 
opportimities for determining the extent of rock 
weathering on the west side have not been so 
good as for determining its extent in the eastern 
division, and the rocks which are there present 
do not aflFord the same variety in composition 
and structure. Observations are confined prac- 
tically to two kinds of rock, namely, the igneous 
basic rock forming the large area north of the 
Kio Grande valley, and the rocks of the Brito 



formation. The basic igneous rocks do not 
differ essentially from those which occur on the 
east side, whei*e they are covered with a great 
depth of red and blue clays. On the west side, 
however, the residual material covering them 
consists of a comparatively thin layer of bluish- 
gray clay. It is somewhat doubtful whether 
the thinness of this residual mantle is due to the 
loss rapid decay of the rock or to the more rapid 
removal of the products of weathering. Cer- 
tainly the latter factor is important, but the rate 
of weathering may also be very much slower, 
under the climatic conditions which here pre- 
vail, than in the eastern division. The blue clay 
appears to constitute practically the only pro- 
duct of decay, and the extensive zone of soft 
rock in which the minerals are entirely altered 
but in which the original rock structure remains 
is entirely wanting. 

The clay derived from the decay of the Brito 
formation is quite similar to that derived from 
the igneous rocks, except that it contains a 
notable amount of sand where it is derived from 
the more sandy portions of the formation. 
Where derived from the calcareous shales it 
forms a blue or black tenacious plastic clay. Its 
depth varies from nothing up to ten or fifteen 
feet, depending upon the position in which it 
occurs. The greatest tliickness is found in the 
level valleys where the surface is practically at 
base level and where the surface erosion is prac- 
tically reduced to zero. Upon the steep hill- 
sides, on the other hand, the same kinds of rocks 
are covered with a very scanty layer of residual 
soil, or it may be entirely wanting. 

So far as known there is nothing on the west 
side which con*esponds to the zone of soft rock 
generally represented in the sections from the 
eastern division. Wherever opportunity was af- 
forded for observing the character of the passage 



132 



NICARAGUA CANAL COMMISSION 



from the overlying blue clay to the underlying 
igneous rocks, the transition wa^ found to be 
abrupt and the intennediate zone of weathered 
rock was absent. 

Overlying the shales of the Brito formation 
there is a zone of weathered rock which corre- 
sponds in some measure with the zone of soft 
rock generally observed in the eastern division. 
Within this zone the beds are thoroughly shat- 
tered by the presence of numerous joint planes, 
and concentric weathering has been more or less 
extensively developed. The mechanical altera- 
tions which the rocks have suffered, however, 
are much more important and striking than the 
chemical changes, hence in the sections this is 
called the zone of disintegrated rather than de- 
cayed rock. For the purposes of the engineer, 
however, the distinction is not specially import- 
ant. As stated above, this is the material which 
has been very loosely termed " telpetate " and 
cascajo. 

EARTHQUAKES. 

Relation of the Canal Route to Centers 
OF Volcanic Activity. — Most earthquakes for 
which a cause can be assigned with any degree 
of probability are produced either by an explo- 
sion at greater or less depth below the earth's 
surface or by a dislocation of the earth's crust 
producing a fault. The former class is confined 
chiefly to volcanic regions, and if the explosions 
are sufficiently long continued they eventually 
find a vent at the surface and produce an active 
volcanic eruption. Earthquakes produced by 
faulting are also to some extent characteristic 
of volcanic regions, but may occur remote from 
any scene of volcanic activity, especially in 
regions which are undergoing rapid elevation or 
depression. They are especially characteristic 
of regions in which the mountain-building 



forces are active. Earthquakes of the latter 
class, due to dislocations of the strata, are per- 
haps no more liable to occur in the vicinity of 
the Is icaraguan Canal route than elsewhere, and 
hence they do not constitute a danger which is 
peculiar to this region more than to almost any 
other in which a ship canal might be con- 
structed. Earthquakes of the first class, how- 
ever, are assumed to constitute a menace to the 
permanence of the canal inasmuch as the region 
is one of considerable volcanic activity. The 
question of the risk incurred from this source is 
certainly one which should be considered. 

In the foregoing description of the topography 
and geology of the region tlie distribution of 
modem volcanic activity was indicated. It was 
shown that, while the Xicaraguan depression is 
occupied to a considerable extent by volcanic 
rocks, these belong in large measure to a former 
geological period, and the activity to which they 
owe their origin has long since entirely ceased. 
It was shown further that the onlv manifestation 
of volcanic activity in recent times has been 
along two lines of vents which have given rise 
respectively to the Costa Rican and the Nica- 
raguan volcanic ranges. The former terminates 
to the northward in the peak of Orosi. This 
volcano appears at present to be entirely extinct, 
and there is no authentic record or tradition of 
its having been in eruption since the occupation 
of the country by the Spaniards. Button de- 
scribed it as to all appearances a long extinct vol- 
cano; an old cone in an advanced stage of degra- 
dation by weathering and showing no traces of 
recent action. Squire,' however, speaks of it 
as in a state of constant activitv, but he does not 
describe it from personal observation, nor does 
he give the date of any authenticated eruption. 



» E. G. Squire, " The States of Central America," New 
York, 1858, p. 361. 



APPENDIX II.— GEOLOGIC REPORT 



133 



Of the numerous volcanoes in the Costa Rican 
range to the southeast of Orosi only one has 
shown anv activity within historic times. This 
is Irazu, near the center of the range, which was 
last in eruption in 1726. As described by Hill, 
" the entire crater occupies but a relatively small 
portion of the great moimtain mass which it 
caps and is apparently a later parasitic summit 
growth upon a much older mass." ' It is evi- 
dent that the eruption which gave rise to the 
present conical summit of Irazu is an expiring 
phase of the activity which produced the massive 
mountain range. 

The Xicaraguan range terminates to the 
southward in the twin peaks of Madera and 
Ometepe, occupying the island of Ometepe. 
The interval between the northern terminus of 
the Costa Rican range and the southern termi- 
nus of the Xiearaguan range is about thirty 
miles, and between these points passes the sailing 
line of the canal in Lake Nicaragua. Madera 
may be regarded as extinct. There is no tra- 
dition of its having shown activity, and its sum- 
mit has been greatly modified by erosion, indi- 
cating that there have been no eruptions for a 
very considerable time. Ometepe is quiescent. 
It manifested a slight activity in 1883 when 
there was an eruption of lapilli with explosions 
of moderate violence. At present the only sign 
of activity consists in numerous fumeroles from 
which steam and sulphurous gases escape. 
While no eniption of Ometepe appears immi- 
nent, there is no certainty that its activity has 
entirely ceased, although the indications are that 
it is on the wane. Mombacho has been extinct 
for a long time. Its last eruption was probably 
one of the explosive type and destroyed its con- 



1 Tbe Geological History of the Isthmus of Panama and 
Portions of Costa Rica, by Robert T. Hill, Bull. Mus. 
Comp. ZooL, Vol. XXVIII, 1898, p. 230. 



ical summit. Ifasaya was in eruption in 1858, 
but the eruption was not accompanied by explo- 
sion, simply consisting of the welling up and 
overflow of fluid basaltic lava. Momotombo at 
the northern end of Lake Managua shows signs 
of moderate activity. It is not at present erupt- 
ing solid material, but throws off great volumes 
of vapors which form a black cloud over its sum- 
mit. Steam and other vapors are escaping from 
several craters to the northward of Momotombo, 
l)ut from none of them are any lavas or lapilli 
being extruded. 

It is thus seen that the present activity of the 
volcanic vents which form the Costa Kican and 
Nicaraguan ranges belongs almost entirely to 
the solfataric stage which characterizes the ex- 
tinction of volcanic activity. Considering the 
great mass of material which has been extruded 
from these vents in comparatively recent geo- 
logic times, it is very clear that the activity in 
this region is on the wane; and while eruptions 
will doubtless occur in the future, it can be as- 
serted with a fair degree of confidence that these 
will be less violent and occur at longer intervals 
than in the past. It is also clear that the great- 
est activity at present and hence the source of 
greatest danger in the immediate future is not 
in the vents which terminate the volcanic ranges, 
but rather in the central portion of those ranges, 
that is, in central Costa Rica and in northern 
Nicaragua. The experience of many years 
proves that these regions which are the centers 
of greatest volcanic activity are also the centers 
from which emanate most of the earthquakes felt 
throughout the Nicaraguan depression. 

(^OXSl DERATIONS AfFECTING EARTHQUAKE 

Forecasts. — The subject of earthquakes in this 
region and their bearing upon the problem of 
the canal have been studied by Major C. E. But- 
ton, than whom no one is better qualified to 



134 



NICARAGUA CANAL COMMISSION 



speak on tliis subject. His report accompanies 
the report of the Nicaragua Canal Board of 
1895, and his discussion of some of the princi- 
ples of earthquakes in general and their applica- 
tion to this particular region are quoted below. 
^' As regards earthquakes, it is well known 
that they are comparatively frequent, especially 
in Costa Rica and Nicaragua, and a few have 
been destructive in verv restricted localities. It 
is no doubt a matter of great interest to the 
Canal Company; for the question at once arises 
whether there is not danger of serious damage 
from this cause to the works of construction, and 
of the still more serious damage of long suspen- 
sions of traffic. In order to reach some esti- 
mates of the magnitude of this danger, it may be 
well to state, as briefly as possible, some general 
considerations which must sen^e for a logical 
basis of any estimate: 

*^(1) The forecast of earthquakes contemplates 
probabilities only and not certainties. That one 
will happen in a particular region in a specified 
number of years is a probability which is great 
or small according to the nature of the locality 
and its extent. We may view such probabilities 
as having the nature of risk analogous to those 
of fire and shipwreck, with the following differ- 
ence: Fires and shipwTecks are of such fre- 
quent occurrence, and have been so thoroughly 
investigated by insurance companies, that their 
probabilities under widely varying circumstances 
can be estimated with great precision, and the 
commercial value of the risk accurately deter- 
mined. Earthquake risks have never been so 
investigated, and it is therefore impossible to as- 
sign specific numerical values to them. Never- 
theless it is sometimes practicable to show that 
the risk is so small that it can be left out of 
consideration with prudence, though we may not 
be able to assign its precise value. 



" (2) In attempting to forecast the future prob- 
abilities of earthquakes, we must assume that 
the future will be like the past, precisely as is 
done in insurance probabilities. We must as- 
sume that where they have been frequent and 
violent they will continue to be so, and that 
countries seldom visited by them in the past will 
be as seldom visited in the future. There is no 
other possible basis of reasoning. 

*' (3) Eartl^quakes originate at very different 
depths in the earth, rarely, perhaps never, ex- 
ceeding twelve miles, and generally not exceed- 
ing three or four miles. We know almost noth- 
ing of the ultimate nature of the forces or 
causes which generate them; but we know con- 
siderable about the manner in which thev are 
propagated after they have been started, and 
concerning their subsequent action and effects. 
Whatever may be the causes, we must assume 
that the subterranean tract or seat in w^liich they 
originate occupies some space of very limited 
extent and contains some point which may be re- 
garded as its center — commonly called the cen- 
trum. From the seat of origin the impulses 
are propagated as elastic waves in every direc- 
tion, in a manner having much in common with 
waves of sound in the air. 

" (4) The intensity or violence of these waves 
diminishes like that of the air, at as rapid a rate 
as they are propagated. At any given spot the 
intensity is inversely proportional to the square 
of the distance from the centrum. 

" (5) In all destructive earthquakes, the extent 
of the country in which they are destructive is 
but a small fraction of the total area throughout 
which the tremors are perceptible. Ordinarily 
it is not far from the four-hundredth part of the 
area perceptibly shaken. The area in which the 
shocks may cause damage varying from slight 
to serious (but not demolition or what are usu- 



APPENDIX II.— GEOLOGIC REPORT 



135 



ally considered destructive eflFects) is commonly 
about four to eight times as large as the destruc- 
tive area, or from the fiftieth to the one-hun- 
dredth part of the area of perceptible vibration. 
Those ratios are only roughly approximate, and 
they are subject to some qualification, ordinarily 
not large, dependent on the depth of the cen- 
trum. They are of importance as showing the 
comparatively narrow localization of destructive 
and even damaging effects. Still, the destruc- 
tive areas may in some cases be absolutely con- 
siderable, being proportional to the total energy 
of the shock at the centrum. The destructive 
area of the Charleston quake had a radius of not 
far from forty miles, but its tremors were per- 
ceptible at a distance of 700 to 1000 miles. Its 
great extent, as well as the distances at which 
its tremors were felt, cause it to rank among the 
most powerful shakes of the present century. 
Its intensity at the surface, however, while for- 
midable, was not so excessive as has been ex- 
perienced in some other memorable earthquakes. 
This was because its depth was extreme, being 
in all probability one of the most deeply seated 
of which we have sufficient knowledge to form 
an opinion. In striking contrast was the Casa- 
micciola earthquake, on the island of Ischia in 
the Bay of Naples, in 1884. Here the destruc- 
tive area had a radius of less than two miles, but 
within that area the violence was superlative and 
the havoc great. At Naples, twenty-five or 
thirty miles away, the shock was only a faint 
tremor. The depth of the Charleston quake is 
computed at about twelve miles, with a verv' 
moderate probable error. The Casamicciola 
quake had its origin at a depth, probably, of less 
than half a mile. Immediately over the cen- 
trum its intensity was apparently quite equal to 
that in the central area of the Charleston, but 
the total energy of the shocks w^as hardly one 



seven-hundredth ])art as great. These two ex- 
treme instances may illustrate the varv'ing effects 
of total energy and depth upon surface intensity. 
The comparison is analogous to one on a smaller 
scale between the explosion of one hundred 
pounds of dynamite at a depth of one hundred 
feet and thirty tons at a depth of half a mile. 
The effects at the * epicentrum ' (jx)int on the 
surface vertically over the centrum) would not 
differ much, but the larger and deeper charge 
would affect a vastly greater area, and would be 
felt at a much greater distance. 

" There is a tendency on the part of all per- 
sons ^vho have not made special study of the 
subject to entertain exaggerated ideas of the 
risks and dangers of what are termed earthquake 
countries. The terrors of the ^ epicentral tract ' 
in a great devastating series of shocks cannot, 
indeed, be exaggerated. The error consists in 
assuming them to be frequent, widespread, and 
typical of the coimtry. In truth, they are rare, 
even in the most afflicted region, and when they 
do come they are destructive within relatively 
narrow limits only, while the country' at large 
is shaken only by harmless quivers. It is ex- 
ceedingly rare for one generation living on any 
spot on earth to have seen two destroying earth- 
quakes in the same locality. In many volcanic 
countries there are a few spots where such catas- 
trophes rei>eat themselves, though usually after 
very long inten-als of years. These are known 
and can be shunned by the engineer and archi- 
tect, if need be. Apart from these, all locali- 
ties within an earthquake country' sufficiently re- 
moved from the known centers or axis niav be 

t.' 

regarded as being in far less peril from earth- 
quakes than from sweeping destruction by an 
uncontrollable fire. 

" Briefly, then, my opinion is that the risk of 
serious injury by earthquakes to the construe- 






136 



NICARAGUA CANAL COMMISSION 



M 



tions proposed for the Pacific section of the canal 
is so small that it ought to be neglected; .... 
also, that the risks to the Atlantic section are 
still smaller than those to the Pacific section." 

SsiSBnc Records in the Cakal Reoios, — On 
the 29th of April, 1898, there occnrred an earth- 
quake which was perceptible throughout the 
greater part of tlie Nicaraguan depression, and 
which was moderately destructive in the towns 
of Leon, Managua and Chinandaga. A com- 
mission consisting of Dr. Carlos Sapper and Dr. 
Bnino Miersch was appointed by the Govern- 
ment of Nicaragua to investigate the cause of 
this earthquake. This commission visited the 
region affected and made the ascent of numerous 
volcanic peaks in the vicinity of its greatest 
violence. They found no signs of imminent 
eruption in any of the craters visited, and reached 
the conclusion that the earthquake was due, not 
to a volcanic explosion beneath one of the nu- 
merous craters of the region, but to a dislocation 
of the strata. It is probable, as has been indi- 
cated in a preceding part of this report, that this 
region to the north of Lake Kicaragua has been 
affected by faults in comparatively recent times, 
and the present earthquake may he due to a 
further displacement along one of these old 
lines of fracture or to the inauguration of a new 
fracture. The absence of any signs of increased 
activity in the volcanic craters, however, is 
scarcely conclusive evidence that the earthquake 
was not due to a deep-seated explosion intimately 
connected with the causes of the vulcanism. It 
is the deep-seated explosions, those not relieved 
by an eruption at the surface, which probably 
cause tlie most destnictive earthquakes. "When 
a vent is formed with an open passage from the 
seat of the explosion to tlic surface, the violence 
of the effects is diminished, or rather it is mani- 
fested in an eruption of lapilH and lava rather 



than in earthquake waves transmitted through 
the crust to the surface. 

Leon was visited by the writer shortly after 
the earthquake of April, 1898. The effects ob- 
seri'ed in that city were chiefly the formation of 
eracks in the walls and the partial destruction of 
buildings constructed of adobe. This material 
has very slight coherence and is poorly adapted 
to resist the strains produced by earthquake vi- 
brations. Xo solidly built wooden or stone 
buildings suffered greater damage than the for- 
mation of a few cracks over the doors and win- 
dows. The cathedral of Leon suffered no dam- 
age except the displacement of a large globe 
which rested on a slender support on the orna- 
mental facade of the building. It was con- 
cluded that if such a structure as a canal lock 
built on a suitable foundation, had occupied the 
epicentral tract of the Leon-Chinandaga earth- 
quake it would have suffered no material dam- 
age, almost certainly not enough to interfere 
with its continuous use. The risk at points two 
hundred miles distant from the epicentrum, that 
is at the nearest point on the canal route, would 
have been entirely negligible. 

The only source of possible danger from earth- 
quakes to the eastern division of the canal liea 
in the Coeta Rican volcanoes. Occasional 
earthquakes are experienced in central Costa 
Rica, the most violent since the occupation of 
the country by the Spaniards having been the 
one which destroyed the town of Cartego in 
1841. This emanated from the neighboring 
volcano of Irazii and was of the shallow type 
with a small epicentral tract. It was only 
slightly doatructive at San Jose, about thirteen 
miles farther from the source than Cartego. 
The much greater distance of the canal from 
this volcano renders the probability of an rarth- 
quakf from that source extending its destruc- 



APPENDIX IL— GEOLOGIC REPORT 



137 



tive area so far as the canal structures extremely 
small. 

Two sdurces of clanger to the western division 
of the canal are present, in Orosi to the south 
and in Ometepe to the northeast. As stated 
above, there is some doubt as to the condition of 
Orosi. The probability, however, is that this 
volcano is extinct. There arc no records or tra- 
ditions of destructive earthquakes having af- 
fected this region, although from the absence of 
large towns it is doubtful if the absence of 
records should be considered as conclusive evi- 
dence that such earthquakes have not occurred. 
The distance of this volcano from the nearest 
canal structures whicli would be liable to injury 
is so great that unless the disturbances were of 
exceptional violence the only effect at the canal 
line would be harmless earth tremors. The ex- 
tent of the danger from Ometepe can be some- 
what more accurately gaged. This volcano was 
regarded as extinct up to the date of its eruption 
in 1883. It was clothed with vegetation en- 
tirely to the summit. Some earthquakes had 
emanated from Ometepe before the eruption. 
Squire speaks of the town of Rivas as having 
suffered much from earthquakes previous to 
1850, but gives no details of their frequency or 
violence. The one which accompanied the erup- 
tion of Ometepe in 1883 was only very slightly 
destructive even at Rivas, and at the line of the 
canal its destructive violence had doubtless en- 
tirely disappeared. Even with the intensity 
manifested at Rivas it would in all probability 
have been entirely harmless to such a structure 
as a canal lock. It is not probable that those 
which preceded that of 1883 were much more 
destructive or some record of them would have 
been preserved. Indeed the excellent state of 
presentation in which the ancient churches of 
Rivas and San Jorge are found is conclusive evi- 



dence that the region has not been visited by 
earthquakes of destructive violence for more 
than a century. 

A consideration of the present activity in 
these two volcanoes, therefore, and of the avail- 
able records of earthquakes in this region would 
seem to remove all apprehension concerning the 
probability of damage to canal structures by 
earthquakes emanating from them. If the dan- 
ger from these sources, which are comparatively 
near, be considered so small that it may be dis- 
regarded, that from the more distant centers of 
volcanic activitv, both to the north and the 
south, may be dismissed as altogether too small 
to merit consideration. Even if there should 
originate at the present centers of greatest ac- 
tivity an earthquake with as great violence as 
that which has characterized some that have 
wrought the most destructive effects in Peru and 
San Salvador, it is probable that the earth 
waves would there be so far dissipated before 
reaching the line of the canal that they would be 
comparatively harmless. It therefore appears to 
the writer that the opinion above quoted from 
Major Button is entirely correct, namely, that 
the risk of serious injury by earthquakes to the 
constructions proposed is so small that it ought 
to be neglected. 

RECE^'T GEOLOGIC HISTORY. 

The relation between the topography and the 
recent geological history of the region is so inti- 
mate that a description of the former neces- 
sarily involves some statements concerning the 
latter. The same is to a somewhat less extent 
true of the lithologj\ Hence in the foregoing 
description of the topography and of the rock 
formations some of the main features of the 
geological historj' have been briefly outlined. 
With these prerequisite facts of topography and 



138 



NICARAGUA CANAL COMMISSION 



lithology the geological history may now be 
taken up systematically and in some detail. 

Conditions Anterior to Tertiary Time. — 
As already indicated, no rocks older than the 
Tertiary occur in the region of the Xicaraguan 
depression so that there is only negative evidence 
as to the conditions which prevailed here during 
geological periods earlier than the Tertiary. In 
the region to the northward, in Guatemala and 
northern Nicaragua, the oc»currence of granites 
and crystalline schists has been described; also 
small areas of paleozoic rocks. The present 
extent of these older formations, however, as 
well as their former distribution is not known. 
The region to the south in Costa Rica also con- 
tains older formations, but thev are almost com- 
pletely covered by the recent volcanic rocks so 
that the former extent of the land in this direc- 
tion also is unknown. It is quite possible that 
a depression of this portion of the isthmus oc- 
curred at the beginning of Tertiary time, and 
that a somewhat extensive land area was whollv 
submerged or converted into an archipelago. 

Early Tertiary Deposition and Volcanic 
Activity. — As indicated in the description of 
the Brito and Machuca formations these rocks 
were deposited on the sea bottom in early Ter- 
tiary time. It is assumed that during their 
deposition there was open communication be- 
tween the Atlantic and the Pacific oceans across 
this portion of the isthmus, although it will be 
readilv conceded that this conclusion is merelv 
an hypothesis. Sedimentary formations have 
not as yet been traced entirely across the isthmus 

and there is no other direct evidence bv which 

»■ 

this hypothesis can be proven. If, however, 
there had been any land separating the two 
oceans, its rocks ought to be recognizable at the 
present time as distinctly older than the Ter- 
tiary sediments or the volcanic rocks which are 



intimately associated with them. As already 
stated, no such older rocks are recognized in the 
region of the Xicaraguan depression, and al- 
though the volcanic activity which was contem- 
poraneous with the deposition of the sedimentary 
formations mav have cut off the communication 
l)etw(»en the two oceans earlv in Tertiarv time, 
it app<*ars at least probable that at the beginning 
of that period and perhaps through the Oligocene 
the sea had free access across the isthmus. 

The character of the sedimentarv rocks indi- 
cates in some measure the conditions which pre- 
vailed during their deposition, not only in the 
seas in which thev were laid down, but also in 
the adjoining lands. These conditions were 
somewhat shallow seas with an abundant supply 
of sediment alternating between sand and mud. 
The sediment appears to have been chiefly de- 
rived, not from a region underlain by deeply 
decayed rocks, but rather from unconsolidated 
and recently ejected volcanic material. The ex- 
tremely coarse conglomerates which occur in the 
Brito formation along the Pacific coast and on 
the southwest shore of Lake Nicaragua point 
to the proximity of active volcanoes. The 
coarser material supplied by these volcanoes 
was transported but a short distance and shows 
the effect of only a moderate amount of wear. 
The finer material was widely disseminated and 
constitutes a very considerable proportion of 
the sedimentarv formations. These contain, 
however, a certain proportion of clay which was 
doubtless derived from the residual mantle cov- 
ering the older rocks which formed adjacent land 
areas. The conditions at certain points were 
favorable for the deposition of limestone. Con- 
siderable lime is disseminated throughout the 
entire Brito formation and is segregated in 
marly beds and in occasional lenses of pure 
limestone. The volcanic activity not only fur- 



APPENDIX II.— GEOLOGIC REPORT 



139 



nished a large portion of the material of which 
the sedimentary rocks are composed, but it con- 
tinned for some time after their deposition, and 
produced numerous dikes, cutting the beds and 
also the extensive lava flows which in places rest 
upon them. This volcanic activity appears to 
have been much more violent and long-continued 
near the axis of the present isthmus than on the 
west side. The region between Lake Nica- 
ragua and the Pacific ocean, as already indi- 
cated, is occupied chiefly by sedimentary beds 
and by recent volcanic material. Only a few 
large areas and occasional dikes of intrusive 
rocks have been found associated with the Brito 
fonnation, and it is not certain that these ever 
reached the surface. While the coarse con- 
glomerates along the Pacific coast demonstrate 
the near proximity of volcanoes, the indications 
are that the volcanic vents from which this ma- 
terial was derived were to the west of the present 
coast line. The conglomerates are confined, so 
far as known, to the immediate margin of tlie 
ocean, and the source of the material seems 
clearly to have been to the westward. The sim- 
ilar conglomerates which occur on the south- 
west shore of the lake appear to have been de- 
rived from vents to the southward and to mark 
the southern margin of the sea in which the 
Brito formation was deposited. 

As stated al)ove, the Tertiary volcanic ac- 
tivity was more prevalent in the region east of 
the lake. More than two-thirds of the area 
which has been examined between the lake and 
the Caribbean is now occupied by igneous rocks 
which present considerable variety in compo- 
sition and structure. It is probable that the 
present area of the ^lachuca formation does not 
represent its original extent, but merely a region 
in which the volcanic rocks have failed to wholly 
conceal the sediments. The numerous beds of 



conglomerate and stratified ash associated with 
the lavas in the region eastward from Machuca 
point to the presence of standing water during 
the period of volcanic activity. This water in 
which the ejecta were deposited may have been 
a shallow sea from whose bed the volcanoes rose, 
or a series of lakes formed upon the imperfectly 
drained constructional surface. It is very dif- 
ficult, however, to determine even approximately 
the conditions which prevailed during the depo- 
sition of this heterogeneous collection of forma- 
tions. The difliculty is, of course, greatly en- 
hanced by the deeply-weathered condition in 
which the rocks are now found. 

MroDLE Tektiary Uplift and Erosion. — The 
period of deposition in this region appears to 
have been terminated toward middle Tertiary 
time by an uplift which was coincident with a 
suspension of the volcanic activity. The ex- 
tent of the land after the uplift can only be de- 
termined in a very general way. It is probable 
that the Pacific coast was some distance farther 
southwest than at present, and there may have 
been volcanic peaks along this coast which have 
subsequently been entirely removed by marine 
erosion. The isthmus was very likely somewhat 
broader than now, although the elevation was 
such that any particular rock stratum was from 
one to two hundred feet lower than at the pres- 
ent time. The uplift inaugurated a period of 
active degradation. It is probable that the sur- 
face at the beginning of this period was, in gen- 
eral, broadly undulating with perhaps isolated 
volcanic peaks but no distinct mountain chain. 
The uplift was accompanied by only moderate 
warping and tilting of the surface, for the Ter- 
tiary beds have suffered comparatively little dis- 
turbance up to the present time. Their average 
dips are between ten and fifteen degrees. In 
general, the character of the deformation was 



140 



NICARAGUA CANAL COMMISSION 



such as to produce a series of gentle folds whose 
axes are approximately parallel with the coast 
lines. This was doubtless accompanied by 
more or less faulting, although evidence of the 
latter is very meager. The character of the 
present drainage makes it evident that no struc- 
tures were developed in the region suiRciently 
well-defined and pronounced to have a marked 
influence on the direction of the drainage. The 
stream courses, with the exceptions which have 
been already noted, and which will be explained 
later, are such as would have resulted from nor- 
mal stream development upon a low, gently un- 
dulating arch. 

The region now occupied by the Xicaraguan 
depression appears to have been originally the 
lowest and narrowest portion of the isthmus; 
hence its surface was more nearlv reduced to 
base level (luring this degradation period than 
that of the broader portion to the north. A 
somewhat perfect peneplain was developed along 
its margins, and broad base-leveled valleys were 
extended well back to the divide in w-hich there 
were numerous low, broad gaps. Although the 
position of the coast lines at the beginning of 
this period is not easily determined, their posi- 
tion at its conclusion mav be made out with a 
fair degree of probability. The Atlantic coast 
was perhaps about where it now is or possibly 
a little farther east than at the present time, for 
although it has subsequently been moved west- 
ward by submergence and by marine erosion, it 
has also been considerably extended by emerg- 
ence and by deposition, so that its oscillations 
have about balanced each other. The Pacific 
coast, on the other hand, differed materially in 
outline from the present. As already indicated. 
Lakes Nicaragua and Managua then had no ex- 
istence, and the coast line occupied a position 
indicated by one of the lines on the accompany- 



ing sketch map, Plate II. The second line is 
intended to represent the position of the coast 
at a somewhat later period. 

Post-Tertiaky Elev^ation and Gorge-Cut- 
ting. — The middle and late Tertiary time as in- 
dicated above, w^as occupied by a period of ero- 
sion with the reduction of much of the region to 
the condition of a peneplain. In the late Ter- 
tiary or Pleistocene the region was again ele- 
vated, this time probably without deformation 
of its surface, although there may have been a 
slight arching of the isthmus on the northwest- 
southeast axis, and possibly also an arching on 
a subordinate axis west of the present lake basin. 
The total elevation w-as probably between 200 
and 300 feet. The immediate effect of this up- 
lift was to stimulate the streams to renewed 
activity. They began at once to trench the 
penei)lain and the broad base-leveled valleys 
which they had formed in the preceding period. 
The effect of the uplift was necessarily first felt 
in the lower courses of the streams and their 
vallevs were there first lowered to the newlv- 
established base level. Thence the deepened 
channels were cut backward toward their head- 

w^aters. In the vallev of the river which occu- 

« 

pied the present position of the San Juan from 
Castillo eastward various phases in the process 
of reduction were present. In the low^er course 
of the stream a broad valley was developed with 
only a few isolated remnants of the former plain 
remaining. This extended upward as far as 
Tambor Grande. From Tambor Grande to the 
Boca San Carlos the valley was rather broad, but 
the adjacent hills retain distinct evidences of 
the former peneplain, and wherever the rocks 
w^ere unusually hard the valley of the stream 
was correspondingly restricted. Between the 
Boca San Carlos and the Continental Divide, 
which was then near the present position of (^as- 



APPENDIX II.— GEOLOGIC REPORT 



141 



tillo, the stream was comparatively small and 
flowed in a narrow gorge. Its channel was cut 
down to a rather low gradient backward to the 
present position of the Machuca rapids. At 
this point was the junction of three branches, 
probably of nearly equal size, occupying the val- 
leys of the Infiernito, the ]N[achuca and the 
present San Juan. 

The tributaries of this river also cut down 
into the old valleys, and the extent to which they 
succeeded in lowering their channels varied with 
their position and size. Xaturally those nearest 
the mouth of the stream were earliest stimulated 
to renewed activity by the lowering of the trunk 
stream into which they flowed, and hence these 
had the longest time in which to effect the low- 
ering of their own channels, while those nearer 
the headwaters of the trunk stream were not ma- 
terially affected until late in the gradation 
period. Thus the tributaries of the San Juan 
as far up as the San Francisco have lowered 
their channels below their old base level, if not 
entirely to their headwaters, at least well back 
toward them. Beyond the San Francisco the 
upper portions of the tributaries are found still 
flowing at the level of their old valleys, which 
they have not as yet had time to completely dis- 
sect. Excellent examples of this immature 
drainage are seen in the basin of the Machado 
and with increasing frequency from that point 
westward to the Toro rapids. Thus the Ma- 
chuca and Bartola are rapid streams, still ac- 
tively corrading their channels almost down to 
their junction with the San Juan. 

The stream which occupied the upper portion 
of the San Juan valley, as indicated above, 
headed upon the Continental Divide iii the 
vicinity of Castillo, and receiving as tributaries 
the Rio Frio and other streams now emptying 
into the lower end of the lake, flowed northwest- 



ward to the head of a bay in the vicinity of the 
island of Madera. This stream, like the other, 
was stimulated by the uplift and rapidly cut its 
channel backward, dissecting its old valley well 
up toward the Continental Divide. This old 
channel, now drowned by the waters of Lake 
Nicaragua, has been traced more or less contin- 
uously from the vicinity of ^Fadera southeast- 
ward with gradually decreasing depth to the 
vicinity of the Balsillas islands. It may very 
likely have extended beyond this point, and its 
upper portion have been subsequently filled by 
the sediment carried into the southern end of the 
lake, chiefly by the Rio Frio. 

The cape which extended northwestward be- 
tween the waters of the Pacific ocean and the 
Bay of Nicaragua appears to have suffered some 
differential uplift, its southern portion being 
elevated more than its northern portion. Not 
enough study has yet been given to the whole 
of this region, however, to determine with any 
degree of certainty the details of its recent his- 
tory. Nevertheless it is known that the rivers 
to the southward of the Rio Grande have cut 
their channels much deeper than those to the 
northward and that some of the latter appear to 
have been affected but little either by this uplift 
or by the subsequent depression. Only the val- 
ley of the Rio Grande has been carefully studied, 
and it is certain that the uplift in this region 
was at least 200 feet. 

The active wave-cutting along the Pacific 
coast during this and the preceding period short- 
ened the distance from the coast to the subor- 
dinate divide on the highland forming the cape, 
thus rendering the length of the streams flowing 
in opposite directions from this divide very un- 
equal. Those flowing to the Pacific, therefore, 
had a very steep gradient while those flowing 
eastward to the Nicaraguan depression had a 



142 



NICARAGUA CANAL COMMISSION 



comparatively flat slope. Hence the corrasion 
of their channels was proportionately greater by 
the streams flowing directly to the Pacific than 
by those which reached the ocean indirectly 
through the Bay of Nicaragua. The former 
group, of which the stream occupying the lower 
portion of the present Kio Grande valley is the 
best studied example, cut their valleys well down 
toward the new base level nearly up to the di- 
vide; while the inner portion of the peneplain 
occupied by the eastward flowing streams was 
scarcely at all affected, and the gorge-cutting 
was confined chiefly to their lower portions, 
which are now occupied by the waters of the 
lake. It is true the main trunk stream entering 
the head of the bay cut its channel backward 
well toward its headwaters, but the tributaries 
from the southwest cut only shallow trenches 
in the outer portion of the Kivas plain and none 
at all in its inner portion. The relations of 
coast lines and divides which prevailed at this 
period are represented on the outline map, Plate 
n, while the former drainage, together with the 
present drainage and relief, are shown on the 
map forming Plate VI. The divide between 
the streams flowing to the Pacific and those flow- 
ing to the bay, which after the bay had been 
converted into a lake became the Continental 
Divide, is shown by the broken line near the 
Pacific coast. The length of the streams flow- 
ing in opposite directions from this Divide is 
seen to be very unequal. The inequality in 
length is so great that before the acceleration in 
corrasion could be felt half-way up the courses 
of the longer eastward flowing streams it had 
caused a deepening of the entire channels of the 
shorter Pacific streams. With such advantages 
the shorter streams began an active conquest of 
drainage area from those less favorably located 
on the east of the Divide. The result was that 



at one point where the advantages of the Pacific 
stream were most decided, the divide between 
contending streams was pushed eastward and 
successive portions of the eastern drainage were 
diverted to the Pacific. The rapidity with 
which different portions of the divide were 
shifted eastward depended largely on its relative 
height and the length of the contending streams. 
The conditions were evidentlv most favorable 

1 

nearly opposite the end of the bay, probably be- 
cause the soft sedimentarv rocks here extended 
entirely across from the ocean to the bay, while 
to the north and south there were considerable 
areas of harder igneous rocks. Hence the sur- 
face had here been well reduced in the preced- 
ing period and was favorably circumstanced for 
further rapid reduction. The stream which 
sufferefd diversion earliest appears to have occu- 
pied the present position of a portion of the 
Tola, the. upper Rio Grande, the Guiscoyol and 
the lower Lajas. This stream was probably five 
or six times the length of its opponent on the 
Pacific side, so that the same fall from the di- 
vide was distributed over a correspondingly 
greater distance, and hence had relatively much 
less than a fifth of the efliciencv of the shorter 
stream. The eastward flowing stream had in 
the preceding period developed a rather broad 
valley, the upper portion of which lay between 
the main divide and the hills bordering the Rivas 
plain. The remnants of this base-leveled valley 
are found in the upper Tola basin, while the 
lower portion of that basin is very perfectly re- 
duced to the present base level, only the uniform 
summits of a few rounded hills suggesting the 
former existence of a plain at a higher level. 
In the upper Rio Grande basin the Rivas plain 
can be traced from its typical development 
at the present Continental Divide westward 
through the increasing degrees of dissection to 



NICARAGUA CANAL COMMISSION. 




MAP TO ILLUSTRATE RECENT 



APPENDIX 2, PLATE VI. 




G OF THE CONTINENTAL DIVIDE. 



APPENDIX H.—GEOLOGIC REPORT 



143 



the summits of a few hills nearly down to the 
Tola. The inference, therefore, that the rem- 
nants of the plain observed in the upper Tola 
and in the upper Kio Grande valleys were orig- 
inally portions of the same base-leveled plain, is 
fairly well established. Accelerated by the low- 
ering of its outlet the diverted Tola has itself 
made considerable progress in the conquest of 
drainage formerly belonging to the eastward 
flowing streams. It has diverted branches both 
of the Gonzales and Medio, the reversed streams 
now forming the Chacalapa and Matinga, and 
leaving low gaps in the present Continental Di- 
vide. The Guachipilin now flowing into the 
upper Rio Grande, formerly found an outlet 
eastward to the Medio, and its deserted valley is 
the point for crossing the divide selected by Com- 
mander Lull for his canal route. The latest 
diversion has evidently been the Guiscoyol, 
which was perhaps the largest stream in this 
region flowing eastward. Its source, now 
forming the headwaters of the Eio Grande, 
was in the high hills which border the lower 
Rio Grande valley. The Rio Grande is thus 
seen to have a composite course, which, con- 
sidering the Cascabel as its head, now makes 
a nearly complete circuit before reaching the 
sea. 

The recently deserted gap between the di- 
verted upper Rio Grande and the beheaded 
Guiscovol is a broad shallow valley, its highest 
point being 154 feet above sea level. It is oc- 
cupied during the wet season by a swamp from 
which the water appears to flow in both direc- 
tions. That flowing toward the lake occupies 
a shallow channel evidentlv once the bed of a 
larger stream, while that flowing west soon finds 
itself in a narrow, sharply cut ravine with rapid 
descent to the rather deep channel of the Rio 
Grande. 



The process of diversion above outlined was 
inaugurated at the beginning of the high-level 
period now being considered, but it doubtless 
continued during the succeeding period after the 
formation of the lake. It is evident that the 
process is still going on and that the Continental 
Divide is now moving eastward at a rate which 
may be regarded as extremely rapid compared 
with most drainage changes and, with the de- 
cided advantages possessed by the Rio Grande, 
it is somewhat surprising that the latter stream 
has not already tapped the lake. 

Recent Depression and Alluviation. — 
The process of gorge-cutting which characterized 
the period of high level just described was ter- 
minated by a depression of the region, amount- 
ing to a little more than half the elevation which 
had inaugurated the preceding period. The 
effect of the depression was to drown the lower 
portions of the river valleys, converting them 
into tidal estuaries. At first the depression af- 
fected only those portions of the river valleys 
which were brought below sea level, while in 
the upper portions the deepening of the stream 
channels continued as actively as before. The 
waste from the land, however, instead of being 
carried out to sea and distributed by littoral cur- 
rents began at once to shoal and fill up the heads 
of the estuaries. With the consequent length- 
ening of the streams their beds were raised and 
consequently the influence of the depression was 
extended up their valleys at a rate correspond- 
ing to the extension of their lower courses. It 
is probable that the depression of the surface was 
comparatively slow, and the filling of the estu- 
aries may have very nearly kept pace with their 
formation. As soon, however, as the depression 
of the land was at any point slower than the 
filling of tlie estuary, the influence of the de- 
pression would proceed upstream at a rate de- 



144 



NICARAGUA CANAL COMMISSION 



pending upon the extension of the lower course 
of the river. 

The depression of the land appears to have 
been accompanied by a moderate local warping 
of the surface. This warping may have affected 
the entire isthmus, but the means of detecting it 
are not at hand except in the western portion. 
The Kivas plain has evidently suffered a gentle 
tilt to the northeast and it is more than probable 
that this tilting was accomplished during the 
depression of the land surface. It will be re- 
called that the Rivas plain is a plain of degra- 
dation formed by the action of streams flowing 
near base level. A plain formed in this way 
must necessarily be nearly horizontal, but the 
present Kivas plain has a slope to the northeast 
of about eight feet to the mile. This is mani- 
festly greater than the gradient of streams form- 
ing a base-leveled plain. It is considerably 
greater th^n the gradient of the present streams 
which cross it. The latter, emerging from 
rather deep, narrow gorges in the residual hills 
to the southwest, cut narrow channels in the 
inner portion of the Rivas plain. These chan- 
nels in some cases have a depth of sixty feet or 
more. They gradually decrease in depth toward 
the outer margin of the plain, the unequal slopes 
of the stream bed and the peneplain surface 
bringing them together at the lake margin. 

Accompanying the depression of the land 
which inaugurated this period was a renewal of 
the volcanic activity of the region. It is pos- 
sible that the vulcanism and the depression may 
be intimately related as cause and effect, or may 
be both the effects of a common cause. How- 
ever this may be with regard to the depression 
of the region as a whole, it is more than prob- 
able that the observed deformation of the sur- 
face is due directly to the volcanic activity. 
This activity was manifested along two lines of 



vents, forming the lines of volcanic craters whose 
topography has already been described. The 
southern series of vents, forming the Costa 
Rican volcanic range, broke out within a land 
area and possibly upon a somewhat elevated 
plateau. These volcanoes have obliterated the 
pre-existent topography and built up a massive 
mountain range. The northern series of vents 
forms the Nicaraguan volcanic range. Between 
the nearest peaks of the two ranges, Orosi to 
the south and Madera to the north, there is a 
gap of about thirty miles. However closely 
the two ranges may be associated in the causes 
which led to the extrusion of their lavas and 
in the character of their lavas, thev are en- 
tirely distinct at the surface and are separated 
by sedimentary and igneous rocks belonging to 
an earlier geological period. As seen from the 
map (Plate H) on which the fonner position of 
the Pacific coast line is shown, the volcanic 
vents which formed the Nicaraguan range broke 
out upon the sea bottom and extended nearly 
parallel to the western coast. The northern 
vents of the group were much more active and 
have given rise to a somewhat continuous moun- 
tain chain and also to the extensive Jinotepe 
plateau. 

FOEMATION OF LaKE NICARAGUA. TllC posi- 

tion of these volcanic vents with reference to the 
coast line was such that when their ejected ma- 
terial had reached the surface of the sea it 
formed a barrier across the Bay of Nicaragua. 
This barrier was built gradually higher by suc- 
cessive eruptions, and since in the area behind 
it precipitation was greater than evaporation, the 
waters rose above sea level and doubtless escaped 
westward over the barrier during the occasional 
periods of quiescence in the volcanic activity. 
As the surface of the barrier was raised by suc- 
cessive additions of volcanic ejecta, the surface 



APPENDIX II.— GEOLOGIC REPORT 



145 



of the impounded waters was raised to a height 
probably somewhat above the present elevation 
of Lake ^Nicaragua. The lake thus formed occu- 
pied not only the position of the former bay but 
flooded the basins of the tributary streams. Its 
surface finally reached the lowest point in the 
Continental Divide where a westward-flowing 
stream headed against one which occupied the 
present position of the San Juan. When this 
point was reached, the intermittent escape of the 
impounded waters across the volcanic dam to the 
westward was changed for a permanent outlet 
to the eastward. The gap, when first discovered 
and overtopped by the rising waters, was doubt- 
less underlain by deeply weathered rock and 
residual clay. This must have been very rapidly 
cut down by the escaping waters until the under- 
lying hard rock was reached, when the perma- 
nent level of the lake was established which it 
has retained practically unchanged to the present 
time. 

It is quite possible that the gaps through the 
Continental Divide to the east and through the 
divide across the western strip of land, between 
the former bay and the Pacific ocean, were so 
near the same level that the lake had for a short 
time an outlet both to the Atlantic and the 
Pacific. 

An examination of a portion of the Rio 
Grande gorge possibly throws some light on this 
point. From the point where the Rio Grande 
turns abruptly to the northwest in the reversed 
channel of the streams which formerly flowed 
eastward, for a distance of four or five miles to 
the point where the gorge opens out to the allu- 
vial plain bordering the lower river, there is an 
old channel which has been partially silted up by 
the present river. The stream only occasionally 
touches the rock walls of the gorge on the con- 
vex sides of its meanders. At the same time it 
10 



nowhere departs wholly from the old channel, 
that is, it nowhere has the character of a super- 
posed stream. It is evident that the present 
stream is smaller than one which excavated and 
formerly occupied this valley. There are three 
ways in which the present conditions might have 
been brought about: 

1. The present valley might have been occu- 
pied by a stream which was once larger than at 
present, but which has suffered a-^partial diver- 
sion of its headwaters by capture through the 
encroachment of a neighboring stream. This 
possible explanation, however, is not applicable 
in this case, since the Rio Grande is itself a grow- 
ing stream and is constantly adding to its drain- 
age area, and hence to its volume by encroaching 
on the basins of its neighbors. There is no 
evidence from the arrangement of the drainage 
in this region that the Rio Grande has ever lost 
any territory in this way. 

2. The former volume of the Rio Grande 
might have been greater by reason of different 
climatic conditions which at some former time 
gave the region a greater rainfall than it now 
has. There is no direct evidence in favor 
of this hypothesis. So far as known there is no 
evidence whatever that the rainfall has ever been 
greater in this region than it is at the present 
time. On the contrary, if a greater rainfall had 
been the cause of the old valley this condition 
would have been general in its effects and all the 
streams of the region would show the same evi- 
dence of greater volume in the past. So far as 
known, however, the Rio Grande is exceptional 
in this respect. 

3. The third possible explanation is that the 
lake may have found an outlet for a short time 
by way of the Rio Grande valley. As pointed 
out above, the lake rose behind the barrier 
formed of the volcanic ejecta until the level of 



146 



NICARAGUA CANAL COMMISSION 



the impounded waters reached the lowest gap 
in the Continental Divide where they spilled 
over and escaped by way of a river channel 
leading eastwanl to the Caribbean. Now the ma- 
terial forming the gap in the Divide must have 
been residual clay and deeply w^eathered rock, 
material which would be rather readily removed 
by the corrasion of the escaping waters. Also 
a study of the present river gorge where the 
Continental Divide formerlv existed shows that 
the channel has here been considerablv lowered. 
It does not seem at all improbable, therefore, 
that the lake for a short time may have been 
fifty or more feet higher than now with refer- 
ence to the surrounding country. But if it 
were raised fifty feet its waters w^ould escape 
by the Lajas-Grande gap westward to the Pa- 
cific. It seems possible that, when the w^aters of 
the lake were first raised by the growing barrier 
to the northwest, they found two gaps at ap- 
proximately the same altitude and for a time 
escaped in part eastward to the Atlantic and in 
part w-estward to the Pacific. Active corrasion 
of the two outlets began at once. The gorge of 
the Rio Grande was excavated, but the gap in 
the main divide in the east was at first in less 
resistant material and was consequently cut 
down the more rapidly. By the time hard rock 
was reached in this gap the w^aters had been en- 
tirely withdrawn from the western outlet. The 
eastward tilting of the region west of the lake 
may have continued well into this period and 
have been in some measure instrumental in 
finally turning the outlet to the east. 

It is possible that at first the gap in the main 
divide to the east was so much higher than the 
one to the west that all the water escai>ed by the 
latter; that the backward cutting of the east- 
ward flowing stream lowered a gap in the divide 
and by reason of the less resistant material of 



which it w^as composed diverted at first a part and 
finallv all the waters of the lake to the eastward. 
This is only a modification of the third hy- 
pothesis and does not affect the main point, 
namely, that for a longer or shorter period the 
lake had two outlets, one by the Lajas-Grande 
gap and the other by the valley of the present 
San Juan.^ 

This modification of the hypothesis removes 
one of the most serious objections to the above- 
stated theory for the origin of the lakes. An 
examination of the region which it assumes to 
have been occupied by the Continental Divide 
leads to the conclusion that the lowest gap in 
the Divide was probably more than fifty feet 
above the present river. An elevation for the 
present divide above the San Juan at Castillo 
of one hundred feet or possibly more would ac- 
cord better than an elevation of fifty feet or less 
with the topography and drainage of the region 
and wuth the characteristics of divides in gen- 
eral. And it is by no means impossible that 
the backward cutting of the eastward flowing 
stream should lower the gap fifty or seventy-five 
feet in residual clay, while the outlet of the lake 
was cutting the four or five miles of ruck gorge 
now occupied by the Rio Grande. 

Subsequent Modification of the Lake. — 
The original outline of the lake formed behind 
the bari'ier of volcanic ejecta was probably quite 
different from that of the present lakes. The 



' In support of the above theory for the origin of Lake 
Nicaragua some evidence may be deduced from its fauna. 
As is well known, the lake contains many sharks and sword 
fish. These characteristically marine forms have evidently 
occupied a body of salt water which has been separated 
from the ocean by a barrier they were unable to pass, and 
subsequently so gradually freshened that they have been 
able to adapt themselves to the changed conditions. Of 
special significance is the fact communicated to the writer 
by Dr. Theo. Gill that the sharks of Lake Nicaragua are 
specifically identical with those found in adjacent portions 
of the Pacific, but distinct from those found in the Carib- 
bean. 



APPENDIX II.— GEOLOGIC REPORT 



147 



subsequent modification has been due to several 
agencies. The continuation of volcanic erup- 
tions lias doubtless very much contracted the 
northwestern portion of the depression. It is 
probable that the original depression was occu- 
pied by a single lake which extended northwest- 
ward beyond the present limits of Lake Man- 
agua. Later eruptions encroached upon this 
portion of the lake basin, and finally a flood of 
volcanic ash and mud was carried entirely across 
the depression, forming a barrier which cut off 
the upper portion of the lake, raising its surface 
between thirty and fortv feet above the sur- 
face of the larger portion to the southeast. The 
strip of land separating the two lakes is a nearly 
perfect plain composed of partially consolidated 
volcanic tuff. The Tipitapa river which forms 
the outlet of Lake Managua, crossing this bar- 
rier has cut its channel backward nearly to the 
upper lake. It falls about thirteen feet within 
less than half a mile of the point where it 
emerges from Lake Managua. In a very short 
time, therefore, unless the backward cutting of 
this stream is arrested, the level of Lake Man- 
agua will be lowered to the extent of thirteen 
feet. The original outline of Lake Nicaragua 
has further been slightly modified by the recent 
volcanic eruptions in the vicinity of Madera 
and Ometepe and perhaps also of Mombacho. 
The northeastern side of the latter volcano ap- 
pears to have suffered an enormous landslide, 
which has pushed before it a gi'eat mass of 
earth and rock. This now has a peculiar hum- 
mocky surface and forms a long point project- 
ing into the lake and a large number of small 
islands. 

The outline of the lake has further been 
modified bv the action of the waves. The trade 
winds produce a nearly constant surf on its west- 
ern side* and this has accomplished considerable 



erosion at certain j)oiiits. The wave action has 
probably cut a shelf into the adjoining plain en- 
tirely around this portion of the lake, the extent 
of the shelf depending upon the character of the 
rocks which were encountered by the waves. In 
the region south of Madera bold headlands are 
formed by masses of hard igneous rocks which 
tend to protect the less resistant rocks between. 
At some points the steeply inclined sedimentary 
rocks contain certain beds of sandstone which 
are much more resistant than the mass of the 
formation, and these form parallel ledges which 
extend into the waters of the lake in some cases 
a mile or more, the softer rocks between having 
been removed by the wave action to a consider- 
able depth. Some estimate may be made as to 
the extent of the wave-cut terrace along the lake 
shore west of Ometepe from the height of the 
cliff. The Rivas plain has an average slope of 
about eight feet to the mile, and it is assumed 
that this plain extends to the eastward under 
the waters of the lake. If it retains the same 
slope a cliff 24 feet in height would represent a 
terrace at least three miles broad. It is prob- 
able that the wave-cut terrace varies between two 
and four miles along this portion of the shore. 
From Zapatera northward to Granada the wave- 
action is more efficient than on any other portion 
of the lake by reason of the greater sweep which 
the prevailing winds and waves possess. Since 
the shore is here composed of only partially con- 
solidated volcanic ash, the modification of its 
outline, due to wave action, has been very con- 
siderable. It is probable that this action has 
severed Zapatera from the mainland and that the 
many islands surrounding it were originally por- 
tions of that volcanic cone. They probably 
represent the more resistant lavas from which the 
softer materials have been washed awav. 

The modification of the northeastern shore of 



148 



NICARAGUA CANAL COMMISSION 



the lake by wave action has been extremelv 
slight. This portion of the lake shore is without 
a beach, and only rarely is there any considerable 
surf. Hence only a few |X)int3 which project 
well out into the lake show anv effect of wave 
action. 

The material eroded bv the waves from the 

*. 

western shore has been carried northward bv 
the action of the waves and deposited in the 
upper end of the lake. A bar has been built 
across the point of the lake enclosing a broad, 
shallow lagoon behind it, and the outlet of Lake 
Managua has been pushed northward by the 
sand drift well toward the northern margin of 
the vallev. 

The third way in which the outline of the lake 
has been modified is by the building out of its 
shores by material brought down by tributary 
streams. The effect of this is seen almost ex- 
clusively along the southern and eastern shores. 
Elsewhere the constant surf and consequent lit- 
toral currents have been sufficient to distribute 
the sediment as rapidly as brought down by 
tributary streams, so that not onlv have no addi- 
tions been made to the lake shore but the new 
material added has not been sufficient to com- 
pensate for the wave erosion. When the waters 
first occupied the depression behind the barrier 
to the northwest, the outline of the lake must 
have been quite iiTegular, since it filled a river 
basin, some portion of which had rather strong 
relief. !Much of its basin occupied a region 
which had been comparatively well base-leveled, 
but its waters als() extended up the valleys where 
the divides remained in strong relief. Many 
shallow estuaries were thus formed, and these 
have subsequently been entirely filled with sedi- 
ment by the streams entering their heads. The 
most extensive filling was at the southeastern 
end of the lake where the largest tributaries en- 



ter it. It is evident that the broad swampy plains 
bordering the Itio Frio and the upper San Juan 
were originally portions of the lake which have 
subsequently been silted up. 

Reference has been made to the effect of the 
Costa Eican volcanoes upon the drainage of the 
Xicaraguan depression. The series of eruptions 
which give rise to this range probably broke out 
in a land area on which there was a well-devel- 
oped system of drainage, similar to that north of 
the present San Juan valley. This drainage 
system, however, was entirely obliterated, and a 
new divide was established following the line 
on which the vehts were located. The effect of 
this was to greatly enlarge the drainage area of 
the San Juan. The streams which were devel- 
oped on the northern sides of the rising volcanoes 
were compelled by the slope of the region to 
flow northward, where they intersected the heads 
of the small tributaries of the San Juan. This 
resulted in the composite courses of the present 
southern tributaries of the San Juan, which has 
already been pointed out and explained. The 
eruptions of the Costa Itican volcanoes not only 
added to the drainage area of the San Juan, but 
also furnished its southern tributaries wnth an 
abundant supply of unconsolidated material. 

PHYSIOGRAPHY OF THE SAX JUAX 

VALLEY. 

In the foregoing account of the topography of 
the region and its recent geological history many 
of the peculiarities of the San Juan river have 
been referred to or partially described. This 
river and its valliy, however, bear such an inti- 
mate relation to any canal scheme that a some- 
what more explicit account should be given 
of its peculiarities. 

Physiographic Subdivisions of the Riveb 
AND Valley. — Considered from any point of 



APPENDIX H.—GEOLOGIC REPORT 



149 



view, either with reference to the history of its 
development, the present character of its chan- 
nel and banks, or the problem of utilizing it for a 
canal route, the San Juan river falls naturally 
into three sections. Starting from the point 
where it leaves Lake Nicaragua the first extends 
to the head of the Toro rapids, the second from 
the head of the Toro rapids to the mouth of the 
San Carlos river, and the third from the mouth 
of the San Carlos river to the sea. These three 
sections will be taken up in order, and their pe- 
culiar features pointed out in some detail. 

The Upper Division. — The distance from the 
lake to the head of the Toro rapids by the river 
is about twentv-seven miles. In this distance 
the river receives a number of tributaries, but 
none of any size, unless the Eio Frio be regarded 
as a tributarv of the San Juan. The Frio enters 
the latter at the point where it leaves the lake, 
and its mouth is separated from the lake only by 
a narrow tongue of swampy land which is sub- 
merged at high water. In this upper section the 
San Juan river has a moderate current and a 
considerable depth. Its banks are low and 
swampy except where its meanders bring it 
against the foot of one of the numerous hills 
which rise above the alluvial plain. It is evi- 
dent that the lake formerlv extended down to 
this point and considerably beyond, and that a 
large amount of territory has been reclaimed 
from the waters of the lake. The ordinarv 
method bv which lakes are obliterated is bv the 
filling from their upper ends and by the cutting 
down at their outlets. In this case, however, a 
part of this process is exactly reversed. The 
lake is being filled most rapidly from its lower 
end. This filling is manifestly accomplished not 
by the water which comes from the lake, since 
this is practically clear, but by the tributaries 
which enter this lower portion. The present 



river channel does not necessarilv coincide with 

t' 

the position of the river which formerly occu- 
pied this basin. Its present position is depen- 
dent upon the relative amounts of sediment 
brought down by the tributaries upon either side. 
If the Castillo and Toro rapids were cut back 
and the channel of the river permitted to sink 
through the alluvium, forming the greater part 
of its banks and bed, upon the old land surface 
which the alluvium conceals, it would have the 
characteristics of a superposed stream. At 
numerous points where its present channel does 
not follow the old channel, it would discover 
hard rocks in its downward cutting. In its 
present condition this may be described as a 
residual river channely that is, a broad arm of 
the lake has been gradually constricted by the 
addition of sediments on its margin, and all that 
remains is the narrow river channel kept open 
by the current of the water flowing from the 
lake. To make a navigable canal it is evident 
that the channel of the river can be followed the 
greater part of this distance, the material to be 
excavated in order to obtain the requisite depth 
being alluvial silt and sand. At certain points, 
however, the river in its meanders impinges 
upon the hills which border the valley or rise 
above its level surface, and here if the channel 
of the river were followed it would be neces- 
sary to excavate in rock. Knowing the origin 
of the alluvial plain, it is evident that at such 
points, by shifting the line away from the hills 
a short distance, the surface of the rock will pass 
below the excavation line of the canal and the 
latter will be entirely in alluvium. The recog- 
nition of this point will effect a very material 
saving in the building of the canal, and at the 
same time will improve its alignment. 

The Middle Division. — The second section 
of the river extends from the head of the Toro 



150 



NICARAGUA CANAL COMMISSION 



rapids to the mouth of the San Carlos. Its 
essential characteristic is the rapid fall of the 
river and the narrow valley in which it flows. 
The Toro rapids which retain the lake at its 
present level are not formed by a solid ledge of 
rocks crossing the valley, but by boulders, sand 
and clay. It is some distance below the Toro 
rapids that the rock is first found crossing the 
valley. 

It appears that, when this arm of the lake ex- 
tended down to the Continental Divide, it re- 
ceived a rather large and swift tributary, the 
Rio Sabalos, near its head. The sediment car- 
ried by the Sabalos, consisting of clay, sand and 
boulders, was deposited on reaching the quiet 
water of the lake. A delta was thus formed, 
which extended across this arm of the lake, 
forming a shoal. As the river channel sank in 
the gap across the Divide, the latter became 
lower than the surface of the Sabalos delta, and 
the crest of the dam w^hich retained the surface 
of Lake Nicaragua moved westward from its 
original position on the Divide to the present 
position of the Toro rapids. It is evident that 
the dam formed of this unconsolidated material 
is only very temporary, and that the backward 
cutting of the river channel, unless artificially 
checked, will soon low^er this barrier and eventu- 
allv affect the level of the lake. 

It is difficult to determine exactly the position 
of the old divide. It undoubtedly crossed the 
valley of the present San Juan below the mouth 
of the Poco Sol. That stream has evidently in- 
herited the lower portion of its course from a 
tributary to the stream flowing northwest. The 
Santa Cruz also probably belonged to the west- 
ern drainage. The general course of the Bar- 
tola, on the other hand, indicates that it be- 
longed to the eastern system. Hence the divide 
was probably between the Bartola and the Santa 



Cruz. It may have been at the present Castillo 
rapids, although it is prol>able that the rapids 
would show some recession due to erosion since 
the lake was formed. This, however, might be 
comparatively little by reason of the character 
of the rocks, and the fact that the river at this 
point carries comparatively little coarse sedi- 
ment and hence is relativelv inefficient in cor- 
rading its channel. 

From the head of the Toro rapids to Ma- 
chuca the river channel consists of rather long 
quiet reaches separated by rapids. The total 
fall in this section is about forty feet, or an 
average of about two feet to the mile. Of this 
fall all but about six feet is accomplished by the 
numerous rapids. Between the Bartola and 
Machuca creeks ra])ids appear to be due to the 
unequal hardness of the underlying rocks, and 
their position is probably, in large measure, 
permanent, the intervening quiet stretches being 
located upon softer rocks which are worn down 
by the moderate cun*ent more rapidly than 
the harder rocks bv the swift current of the 
rapids. 

Between Machuca and the mouth of the San 
Carlos the river is deep and narrow and the cur- 
rent is generally moderate. In some places at 
low stages of the river it is almost imperceptible, 
and when the San Carlos is in flood the current 
in this portion of the channel may even set up- 
stream for a time. The water has a depth var^'- 
ing between fifteen and sixty feet, the bottom 
of the channel at some points being below sea 
level. It is evident that the present river is 
flowing in a channel which had been cut when 
the land stood higher than now and which has not 
yet been filled by sediment. Where tributaries 
join the river they have deposited small deltas 
in its channel, sometimes shoaling it entirely 
across. But the amount of sediment delivered 



APPENDIX II.— GEOLOGIC REPORT 



151 



to the river by its upper tributaries has evidently 
been no greater than its waters were able to 
transport, even with the moderate current which 
prevails in this part of tho channel. It is im- 
portant to note that although not enough sedi- 
ment has been delivered to the river above this 
point to fill its old channel, the river has built up 
occasional narrow flood-plains. It is evident 
that, while the sediment was of such a character 
and in such quantity that it could be readily 
transported by the river in the unobstructed 
channel, it was retained by the vegetation upon 
the banks, and in this way served to build up the 
surface of the flood-plains. 

The Lo^rER Division. — The third section of 
the river extends from the mouth of the San 
Carlos to the Caribbean sea. With the en- 
trance of the San Carlos the character of the 
San Juan is entirely changed. Above this it 
is a comparatively clear stream and, except at 
the rapids, has only a moderate current. Below 
the entrance of the San Carlos it is usually 
muddy, is shallow with a shifting sandy bed and 
has a uniformly strong current. Its slope is 
verv nearlv a foot to the mile in this section. 
The Sarapiqui is very similar in character to 
the San Carlos, although it is somewhat smaller. 
Heading in the Costa Rican volcanoes it also 
carries a large amount of sand which it delivers 
to the San Juan. Many of the smaller tribu- 
taries of the San Juan deliver practically no sedi- 
ment to the main stream. The flood-plain of the 
latter has been built up so rapidly that they are 
ponded in their upper courses, and the lagoons 
thus made, filled with vegetation, form settling 
basins or filters which effectually remove all sedi- 
ment from their waters. They reach the San 
Juan as clear streams, except that their waters 
are discolored by decaying vegetation. Below 
the mouth of the Sarapiqui the channel of the 



San Juan bends slightly to the northward and 
very distinctly follows the northern margin of 
the valley. This position is probably due to 
the more abimdant supply of material furnished 
by the southern tributaries and to the northward 
drift of the littoral current in the Caribbean 
sea. Although, as stated on a previous page, 
the subsidence which permitted the San Juan 
and its tributaries to silt up their valleys, was 
probably slow, the head of the estuary formed 
by the drowning of the lower valleys may have 
extended at least as far as the mouth of the 
Sarapiqui. As the river extended its course 
eastward by the filling of the estuary and later 
by the foraiation of the delta plain, it would be 
continually crowded to the northward by the 
direction of sand-drift along the coast. This 
tendency became more pronounced the farther 
out the delta was built, and the sharp northward 
bend of the lower San Juan is its direct conse- 
quence. As the river channel was carried 
northward, this portion of the valley would be 
filled first and to a higher level than the southern 
portion. The river would thus at times find 
itself in a position of unstable equilibrium and 
would seek a new channel on the lower part of 
the delta plain to the southward. Thus it is 
probable that the river originally occupied the 
present position of the San Juanillo (see Plate 
I), flowing to the northward between the spurs 
coming down from the Eastern Divide and the 
Silico hills, the latter having previously formed 
a group of islands. This position was probably 
occupied until the coast line was approximately 
at the point where the San Juanillo and Deseado 
now unite. It then gi*adually deserted its north- 
em channel for the present position of the lower 
San Juan. Subsequently the latter became un- 
stable and a more favorable course to the sea 
was found still farther south. The recent clian- 



152 



NICARAGUA CANAL COMMISSION 



nel of the Rio Colorado was then developed at 
the expense of the lower San Juan. This pro- 
cess is still going on, and the relative amounts of 
water carried bv the two channels have verv ma- 
terially changed within a generation. Unless 



artificially modified, the lower San Juan will 
continue to dwindle and practically all the water 
will find its way to the sea by way of the Colo- 
rado or some more favorably located channel 
still farther southward. 



PART II 

APPLICATION OF GEOLOGIC FACTS TO 

ENGINEERING PROBLEMS 



The foregoing account of the topography and 
geology of the Nicaraguan depression is written 
from the view-point of the geologist rather than 
the engineer. "While it contains information 
which it is believed has the most direct and im- 
portant bearing upon engineering problems, it 
also contains much which has only an indirect 
bearing upon the work of the engineer, and even 
where the connection is the most intimate, it has 
not generally been explicitly pointed out. It 
remains, therefore, in the second part, to treat 
the region from the view-point of the engineer, 
and to make explicit the application of the geo- 
logic facts to the engineering problems. Num- 
erous profiles have been funiished to the engi- 
neers showing, so far as the infonnation available 
permits, the geological conditions and the classi- 
fication of materials on the various lines in ex- 
cavation, and at the localities where it is planned 
to construct controlling works, as dams, locks, 
weirs, etc. Upon these profiles the estimates are 
based as well as the plans of the canal and its 
appendages. Very much fuller and more reli- 



able information is at hand concerning certain 
portions of the line than others; hence the in- 
formation conveyed by the profiles has a great 
variability in value. It is diflicult to represent 
those differences upon the profiles themselves, 
and it is therefore important that a somewhat de- 
tailed statement should be made concerning the 
information on which the sections are based and 
the degree of confidence with which they should 
be regarded. The attempt will be made in this 
portion of the report to discriminate between 
that which is known from actual observation and 
that which is merelv inferred. 

In the foregoing chapters upon the rock for- 
mations and rock decav, as well as elsewhere 
throughout the report, many statements have 
been made regarding the character of tlie ma- 
terials with which the engineers will have to 
deal, both in excavation and for foundations. 
Xo systematic statement, however, has been 
given concerning the classification of materials 
adopted and the basis for the same. The classi- 
fication employed will, therefore, be explained 



APPENDIX H.—GEOLOGIC REPORT 



153 



in detail, although some repetition of statements 
made in other portions of the report may be ren- 
dered necessary. 

CLASSIFICATIOK OF MATERIALS. 

All the materials in place with which the en- 
gineer will have to deal in thd construction of 
the Nicaragua Canal, have been for convenience 
divided into four classes, viz.: (1) alluvium, (2) 
residual clay, (3) soft rock and (4) hard rock. 
Each class presents considerable variety in the 
origin and physical properties of the materials 
which it embraces, but the classification is a prac- 
tical one and it is believed to be sufficiently de- 
tailed, at least for preliminary plans and esti- 
mates, if the following explanation is kept in 
view. 

Alluvium. — All unconsolidated material 
w^hich has been transported and deposited by 
streams is classed as alluvium. Bv reason of 
the recent geologic changes which have taken 
place in this region, a very large amoimt of 
this unconsolidated material is encountered on 
the canal line. As pointed out more fully else- 
where, this entire region has recently stood con- 
siderably higher with reference to sea level than 
now, having a much rougher topography, with 
comparatively high hills and deep narrow valleys. 
A recent subsidence of the land has submerged 
many of these valleys, which have subsequently 
been silted up. The alluvium varies consider- 
ably in composition, depending upon the source 
from which it was derived and the manner in 
which it was deposited. It varies all the way 
from coarse, clean-washed sand or gravel to 
the finest clay. It may, for convenience, be 
separated into three sub-classes, viz.: (1) sand, 
(2) silt, a variable mixture of fine sand 
and clay, and (3) clay silt, composed chiefly of 
clay with little or no sand. All three sub- 



classes contain variable quantities of vegetable 
matter. 

On the west side the alluvium is derived 
chiefly from the wearing down of calcareous 
shales and sandstones, with only a few igneous 
rocks. It consists, therefore, chiefly of fine sand 
with comparatively little clay, although there is 
usually enough cementing material to make it 
quite compact. In the Rio Grande flood-plain 
where the alluvium fills a drowned valley, it 
becomes in general somewhat coarser downward, 
and at the surface is composed of characteristic 
flood-plain deposits, generally very fine, sandy 
clay. The present channel of the Rio Grande 
is from fifteen to twenty-five feet in depth, and 
its sides are generally steep, often nearly or quite 
vertical. They servo to show the capacity of the 
material to stand at very steep slopes. It would 
also probably form fairly impervious embank- 
ments. ^ 

The level land bordering the upper San Juan 
from the lake ^ to Savalos ' consists of alluvium 
brought down for the most part by streams head- 
ing upon deeply decayed igneous rocks. It 
consists largely, therefore, of the finest clay silt, 
much of it containing no perceptible grit. Some 
fine sand is found in the river channel where it 
remains as a residuum separated from a large 
amount of sediment, the sluggish current of this 
portion of the river not being able to transport 
the heavier particles. The clay silt in this 
region has usually a gray or bluish color. Be- 
tween Savalos and the Boca San Carlos the flood- 
plains are not extensive, but the alluvium of 
which they are composed is similar in character 
to that bordering the upper river. Below the 
San Carlos there is much greater variation in 
its character, since the material brought down by 
that stream is entirely different from any derived 
from the adjoining country. It consists largely 



154 



NICARAGUA CANAL COMMISSION 



of sand, the larger grains well rounded, but the 
smaller ones quite angular. The prevailing 
color is black with a few grains of red or white 
minerals. The sand is entirely of volcanic ori- 
gin, evidently a finely comminuted, fresh vol- 
canic rock broken up and ejected by explosive 
volcanic eruptions. This sand is transported 
chiefly by rolling along the bottom of the river, 
so that only the very finest portions reach the 
flood-plain. It forms the filling material of the 
old river channel under the bed of the present 
stream. A section taken in the flood-plain, a 
little distance from the river channel, reveals 
fine sandy silt for a considerable distance down- 
ward, with perhaps some beds of black sand to- 
ward the bottom. It seems that as the river 
gradually built up its bed to preserve a normal 
gradient with increasing length, the deposit on 
the flood-plain nearly always kept it so far above 
the bed of the stream that the coarser sediment 
transported by tJie latter was not spread over 
its surface. Enough of the finer portions of 
this volcanic sand, however, were deposited on 
the flood-plain in the immediate vicinity of the 
river, to materially modify the character of the 
alluvium. Of the manv tributaries of the San 
Juan only the San Carlos and the Sarapiqui 
carry volcanic sand of this character. The 
basins of the smaller streams are located entirely 
upon areas of deeply weathered rocks, and the 
sediment which they bear consists of the pro- 
ducts of decay derived from these rocks. The 
only mineral which has withstood the process of 
rock w^eathering is quartz, and this is not found 
in suflficient abundance in any of these fonna- 
tions to materially modify the sediment derived 
from them; hence the outer portions of the San 
Juan flood-plain in which the material is de- 
rived from the sediment borne bv the smaller 
streams, diifer in character from those imme- 



diately bordering the San Juan itself. Not only 
is the deposition near the main stream more 
rapid, so that the current of the tributaries is 
checked and lagoons are formed, but the allu- 
vium, consisting in one case of fine sand with 
a matrix of clay, is relatively much firmer than 
that which is composed of fine clay and vegeta- 
ble matter without any admixture of sand. 

The material forming the delta of the San 
Juan consists almost entirely of sand within a 
belt about four or five miles broad, bordering 
the Caribbean. At some distance from the 
coast this is overiain by a thin stratum of fine 
swamp mud which increases in thickness toward 
the inner margin of the delta plain. 

The alluvium is everywhere of such character 
that it can be easily handled with dredges. Almost 
evervwhere it is suflScientlv solid to stand at 
moderate slopes, the slope of one on one probably 
being sufficient. In some cases, as in the Flor- 
ida lagoon, special precautions may be needed to 
preserve the slopes. The material becomes very 
hard when dry, and even when it is piled up so 
that the water can drain off, it becomes compara- 
tively firm. This is shown in the vertical stream 
banks where drainage is possible, while the same 
material forms a soft mud in the swamps at some 
distance from the stream channels. The black 
sand when free from clay is of course quite per- 
vious to water and would not be suitable for 
banks where the water level was permanently 
different on its two sides. This material, how- 
ever, will not be encountered bevond the site of 
the first lock on the proposed low-level line. 
It is probable that, wherever the canal is more 
than half in excavation, the silt will form banks 
sufficiently impervious to hold the required 
height of water without the addition of any 
other material. Where the head is greater than 
fifteen feet, it may be necessary to add a puddled 



APPENDIX IL—GEOLOGIC REPORT 



155 



core to the bank unless the latter is made of 
extraordinary thickness. 

Residual Clay. — The climatic and other 
conditions which prevail in Nicaragua are ex- 
tremely favorable to rock decay, and the final 
product from the weathering of all the rocks of 
the region is nearly the same. In the eastern 
division this final product is red clay. West of 
the lake, where the climatic conditions are dif- 
ferent, the product is a gray or black clay. The 
red clay represents the zone not only of complete 
rock decay, but also of complete oxidation of all 
or nearly all the constituent minerals. The 
complete oxidation- and the accompanying red 
color usually extend only to a moderate depth, 
ten to thirty feet, while the rock decay usually 
extends much farther. The red clay passes, by 
more or less abrupt transition, into a zone of 
blue clay which underlies it. The latter is gen- 
erally mottled with red near its contact with the 
upper zone. Rarely the red clay extends en- 
tirely down to hard rock. Since the rocks of this 
region, that is east of the lake, are almost en- 
tirely volcanic, or, where sedimentary, contain 
a large proportion of volcanic material, the f elds- 
pathic minerals are abundant and the resulting 
clay contains a large proportion of kaolin. The 
iron-bearing minerals are also abundant as the 
rocks belong to the basic igneous group, and 
hence the brilliant red color of the clay when 
thoroughly oxidized. Quartz occurs in only a 
few of the rocks, so that much of the clay is 
remarkably free from grit, tough and compact. 
Although it is penetrated by numerous roots 
and burrowing insects, the absence of frost per- 
mits it to remain more compact than any surface 
clay in higher latitudes. Xext to the silt it will 
form by far the hirgest part of the excavation. 
It will make perfectly impervious embankments 
if some means are taken to puddle it as it is 



deposited, but probably if simply dumped in the 
bank it would be pervious to water. When 
water is once thoroughly incorporated with the 
clay, it will remain indefinitely, and the resulting 
mixture will probably be more fluid than the 
silt. 

The clay on the west side differs from that on 
the east chiefly in the matter of color. At the 
surface it is almost black, but becomes a bluish- 
black or gray a few feet below the surface and 
sometimes yellow near the rock. Nearly all 
of the clay west of the lake which will be en- 
countered in excavating the canal is derived from 
calcareous shales and sandstones. These rocks 
have originally contained a considerable pro- 
portion of volcanic material, probably deposited 
as fine dust while they were being laid down, 
and the clay does not differ in composition ma- 
terially from the red clay on the east side. It 
seems to be considerably more pervious to water, 
however, but this, as explained on a previous 
page, may be due to the fact that, owing to cli- 
matic conditions, it is alternately thoroughly dry 
and wet. 

Soft Rook. — The residual clay passes by im- 
perceptible gradations downward into the next 
class of materials, which, for convenience, have 
been grouped together as soft rock. The clay 
represents the zone of complete rock weathering 
in which the original minerals are entirely al- 
tered, with the exception of quartz, and in which 
the original rock structure is also in general ob- 
literated. The soft rock represents the zone of 
rock weathering in which the process is only 
partially completed. The most altered minerals 
are entirely changed and the soluble constituents 
are largely removed, but the structure of the 
rock, and some of the more obdurate minerals 
remain more or less perfectly preserved. The 
material may be soft, but is not plastic like clay. 



156 



NICARAGUA CANAL COMMISSION 



It will be readily understood that the line sepa- 
rating these two divisions is, to a large extent, 
arbitrary. They are never separated by a sharp 
line, and it is sometimes a matter of opinion 
where the division should be placed. The rocks 
generally weather inward from cracks which sep- 
arate the mass into rhomboidal blocks. As the 
weathering proceeds suc»ceFsive concentric layers 
of weathered rock break off, and if the process is 
not entirely complete a core of fresh rock re- 
mains at the center. These fresh cores persist 
longest in the case of basalt and are generally 
found more or less abundant not only in the soft 
rock, but in the residual clay as well, becoming 
more abimdant downward until they merge with 
the solid rock. While the final product of the 
weathering of nearly all the rocks of the region 
is practically the same, mainly a tough, red 
clay, each variety of rock has a mode of disin- 
tegrating and weathering which is, in a measure, 
peculiar to itself. Since the original character 
of the rock remains to a certain extent in the 
zone of soft rock, the original character and the 
peculiar method of weathering become more im- 
portant than in the consideration of the residual 
clay. 

In the Brito formation, the calcareous sand- 
stones and shales of the west side, the bedding 
is nearly horizontal, rarely dipping more than 
15°, but the rocks are intersected bv numerous 
joints which are more pronounced than the bed- 
ding planes. There are usually at least two sys- 
tems of vertical joints and frequently more, so 
that the rocks are broken up into rhomboidal 
blocks which usuallv var\'^ in size with the thick- 
ness of the beds. The distance between the main 
joints is generally about the same as the distance 
between the main bedding planes. Only a few of 
the more massive beds of sandstone appear to be 
continuous and unbroken by these joints. Much 



of the rock is a fine-grained calcareous mudstone 
or non-fissile shale. This is broken up into small 
rhomboidal blocks a few inches in diameter, and 
in the zone of soft rock these are weathered in 
such a manner that concentric flakes split off 
from the blocks and, when exposed, they crum- 
ble entirely down to the center. The weathering 
is produced by the leaching of the soluble con- 
stituents, chiefly lime, and the decay of felds- 
pathic minerals. The disintegration of the rock, 
however, which is due to jointing, is a much 
more marked feature than the rock decay. This 
zone extends to a very considerable distance be- 
low the surface, but its depth is dependent 
largely upon the original character of the rock, 
being less in proportion. to its original massive- 
ness. This rock, so thoroughly disintegrated that 
it breaks upon exposure into small fragments, 
is the material to which the native name cascajo 
is applied. The term is a convenient one with 
a perfectly definite meaning, and should be 
used, if at all, with discrimination. It is prob- 
able that all the material on the west side which 
has been classed as soft or disintegrated rock can 
be excavated with a steam-shovel without blast- 
ing. The material stands in natural slopes of 
60° or more, and artificial slopes equally steep 
will probably be entirely safe. 

The Machuca formation in its original com- 
position is very similar to the Brito, but it 
weathers in a very different manner owing to 
the different climatic conditions on the opposite 
sides of Lake Nicaragua. The Machuca sand- 
stone is intersected by numerous joint planes, 
but the consequent disintegration is much less 
prominent than the rock decay, and this has gen- 
erally gone so far that the resulting product is 
more properly classed with the clay than the 
soft rock. Although some traces of the orig- 
inal rock structure remain within a zone covering 



APPENDIX II.— GEOLOGIC REPORT 



157 



the hard rock, it will for all engineering pur- 
poses be treated as clay. 

Among the volcanic rocks of the east side the 
material classed as soft rock is quite different 
from the cascajo above described. It may be 
considered under three varieties; first, that de- 
rived from basalt; second, from dacite; and, 
third, from volcanic sandstones and conglom- 
erates. 

The basalt is fii*st intersected by joints which 
break it up into large rhomboidal blocks. From 
these joints the weathering progresses inward, 
and successive layers are separated from the core 
of fresh rock within. These cores remain as 
boulders, and, as already stated, are found in the 
zone of residual clay as well as in that of the 
soft rock. The basalt varies considerably in 
texture. The upper and lower surfaces of a lava 
flow are usually more or less vesicular, and the 
basalts of this region appear to be largely lava 
flows. These vesicular portions are more readily 
penetrated by the percolating waters from the 
surface and their decay is correspondingly more 
rapid, hence it often happens that the central 
compact portion of a lava flow will be marked 
by a nearlv continuous layer of fresh boulders, 
while the vesicular portions above and below will 
be thoroughly decayed and few if any boulders 
will remain. The basalt is, when fresh, a hard 
black rock which rings under the hammer, and 
is altered to a soft, bluish-gray or rusty yellow 
material which can be readily cut with a knife, 
but in which the original structure of the rock 
is more or less distinctly preserved. This ma- 
terial is not plastic and is more permeable to 
water than the residual clay. 

The dacite is originally a very firm rock which 
generally weathers from the surface downward 
rather than from joints toward the center of 
rhomboidal blocks. The soft rock derived from 



its decay, therefore, is more imiform in structure 
than that derived from the basalt. It rarely 
contains residual boulders of the fresh rock, and 
presences much more perfectly the original struc- 
ture of the rook from which it is derived. It 
forms a pink or gray material soft enough to be 
cut with a knife, in which the constituent min- 
erals can be readily diatinguished, but in which 
all minerals except the quartz are thoroughly 
decayed. 

The volcanic sandstones and conglomerates 
weather somewhat like the dacite. There is a 
regular downward increase in amount of decay 
and all parts of the rock weather equally, the 
fine matrix as well as the large pebbles. The 
resulting material retains perfectly the original 
structure of the rock, the pebbles being distinct 
and in their original shape, but the whole mass 
so soft that it can be readily cut, and in some 
cases it might well be classed as clay. 

The three classes of materials above described 
— alluvium, residual clay and soft rock — should 
be considered as earth in making estimates for 
excavation. The soft rock, however, may re- 
quire some blasting, particularly toward the 
bottom and where it contains very large boul- 
ders. It will stand w^ith much steeper slopes 
than the alluvium and clay and will be less 
liable to slip. Xot being plastic it will also sup- 
port a heavier load and hence may be relied' upon 
for foundations where the weight of the struc- 
ture is not excessive. For these reasons it seems 
desirable to make the distinction between clay 
and soft rock wherever possible. It should be 
clearly understood, however, that when consid- 
ered with reference to cost of excavation the ma- 
terial classed as soft rock must be regarded as 
earth. It will be somewhat more difficult to 
handle than the residual clay, chiefly by reason 
of the greater number of boulders which it con- 



158 



NICARAGUA CANAL COMMISSION 



tains, but it will probably be handled with con- 
siderably less difficulty than glacial drift, boulder 
till or hardpan. 

Hard Rock. — So extensive has been the rock 
weathering in this region that fresh rock rarely 
appears at the surface, and in most cases none 
has been reached at the depths penetrated by 
the diamond drill. Bv fresh rock is here meant 
one in which the constituent minerals have suf- 
fered no alteration. The residual boulders of 
basalt, however, are surprisingly fresh, and even 
when examined under the microscope it is found 
that the constituent minerals have been altered 
scarcelv at all. Bv hard rock is meant, in this 
connection, therefore, not a rock which is un- 
altered, but one which is hard enough to require 
blasting for excavation. In practice the line 
between hard and soft rock was, in general, 
placed at the point where the diamond drill be- 
gan to yield a fairly continuous core. This cri- 
terion is open to objection, since a very soft rock 
will yield a core if it is perfectly homogeneous, 
while a .very hard rock will not core if some por- 
tions are harder than others. The hard por- 
tions choke in the bit and grind up the softer 
portions, particularly if the rock is intersected 
by joints. 

As there is a gradual transition from residual 
clay to soft rock, so there is a similar gradual- 
transition from soft rock to hard rock, and the 
separation of the two classes of material is, to a 
certain extent, arbitrary. In some cases the 
residual boulders become more and more abund- 
ant until they pass into a massive rock inter- 
sected by few insignificant joint planes. In 
other eases, as in that of dacite, the rock be- 
comes very gradually harder by reason of the 
less altered condition of the constituent minerals 
until it may be regarded as hard rock. It is 
safe to predict that the surface separating the 



two will nowhere be found so regular as it is 
represented on the sections. 

The rocks of the region have been rather fully 
described in a previous part of this report, and 
but little further remains to be said concerning 
them. The primary classification as sedi- 
mentary and igneous rocks is of considerable im- 
portance to the engineer and also the particular 
manner in which each class of rocks weathers. 

The heavv dark-colored basic rocks which are 

»,■ 

grouped together as trap are the hardest rocks 
which will be encountered on the line of the 
canal. They are admirably adapted for con- 
crete work but would shatter in blasting and 
hence probably could not be taken out in blocks 
of sufficient size for use in a rock fill dam as the 
Canal Company proposed to build at Ochoa. 
They would also be poorly adapted for use where 
dimensional blocks were required on account of 
the cost of quarrying and dressing. 

Xext in hardness is the dacite. This is 
tougher than the trap and probably would not 
shatter in blasting, so that blocks of any size 
required might be taken from the cuts. It 
might also be quarried in dimensional blocks and 
dressed with comparative ease. Quarrying, 
however, would be expensive by reason of the 
great depth of residual and decayed material 
which evervwhere covers the hard rock. Its 
rapid weathering, noted above, would render it 
a decidedly inferior building stone. The vari- 
ous sedimentarv rocks diflFer widelv in hardness 

•■■ »■ 

and show considerable variation even in a single 
formation. In a general way the hardness de- 
creases in the following order — Machuca sand- 
stone, volcanic sandstone (Ochoa), Brito sand- 
stone, basaltic tuff (Eastern Divide). This order 
apj)lies only to the average hardnoss, and cer- 
tain l)e(ls could be selected from the several 
formations which would occupy a different order. 



APPENDIX II.— GEOLOGIC REPORT 



159 



A matter of considerable importance to the 
engineer is the specific gravity of the rock with 
which he has to deal, especially that which is 
used for construction purposes. 

The following table gives the specific gravity 
and weight per cubic foot of the more important 
varieties of rock on the canal lines. The deter- 
minations were made by Mr. George Steiger in 
the laboratory of the U. S. Geological Survey. 
The material was allowed to stand in water for 
several hours before weighing, so that the values 
given in the table correspond with those which 
would be found if freshly excavated material 
were examined. The specific gravities are 
somewhat lower than would be found for thor- 
oughly air-dried material. The weights per 
cubic foot, however, exceed those for dried ma- 
terial by the weight of the water which a cubic 
foot of the dried material would absorb. 

The average values given by Trautwine for 
four varieties of rock are added to the table for 
comparison. 



No. 1 Andesite forming the hills north of the 
Rio Grande valley about 8 miles from Brito, is 
a compact crystalline rock which will prob- 
ably be found the best available material for 
the construction of breakwaters at Brito harbor. 
Its density is slightly greater than that of the 
average granite. 

Xos. 2 and 3 represent a fair average of the 
dacitc in the Eastern Divide. This is the light- 
est rock on the canal line, and in that respect is 
inferior to the traps as material for rock-fill 
dams, where high specific gravity is of special 
importance. It is, however, the rock which 
would be chiefly employed for that purpose if 
the Alenocal route were adopted. 

No. 4 is a dacite encountered at Lower Ochoa 
which is more compact and much darker in color 
than the dacite of the Eastern Divide. The 
presence of the dark iron silicates gives it a 
rather high specific gravity, though it is lower 
than that of the basalts. 

Nos. 5, 6, 7 and 8 represent the dark igneous 



Name. Locality. S. G. 

1. Andesite Rio Grande, hole 3, 37' 2.75 

2. Dacite Eastern Divide, hole 3, 109' 2.26 

3. Dacite Eastern Divide, hole 4, 140' 2.30 

4. Dacite Lower Ochoa, hole 3, 33' 2.63 

5. Olivine free Basalt Sarapiqui hills, spec. 170 2.77 

6. Olivine Basalt San Francisco hills, spec. 168 2.88 

7. Olivine Basalt Upper Ochoa, hole 9, 83' 2.88 

8. Hypersthene Basalt San Carlos Hills, spec. 44 2.73 

9. Sandstone Machuca creek, spec. 139 2.67 

10. Sandstone Las Lajas, hole 1, 16' 2.67 



Average Wt. |>er 
8. O. cu. ft. 



I 

i 

1 



2.28 



]• 2.81 



I 



2.6 



171 
141 
143 
164 
173 
180 
180 
170 
166 
166 



AVEKA(.E8 (ilVEN HV TRAUTWINE. 

Average Wt. i)er 

Name. S. O. cu. ft. 

Basalt 2.9 181 

Granite* ..'. 2.72 170 

Limestone 2.7 1 C>9> 

Sandstone 2.41 151 



rocks, varieties of basalt, classed together as trap. 
Their average specific gravity is slightly under 
the average given by Trautwine for basalt. 
These are the rocks which will be chiefly relied 
upon for structural purposes if th(» Lull route is 
selected. 



160 



NICARAGUA CANAL COMMISSION 



Xo8. 9 and 10 represent average samples of 
the sandstone beds in the Machuca and Brito 
formations. Their specific gravity is somewhat 
above the average for sandstone given by Traut- 
wine. 

FACTORS DETERMINING RELATIVE 
COST OF EXCAVATING HARD 

ROCK. 

In considering the cost of excavating the ma- 
terial classed as hard rock on the line of the 
canal, two elements of cost which need to be con- 
sidered here as elsewhere are, first, the drilling, 
and, second, the blasting. These two elements 
may or may not vary in the same direction in dif- 
ferent rocks, since they depend upon different 
physical properties. The relative ease of drilling 
depends on the hardness of the constituent min- 
erals, on the character and amount of cements by 
which they are bound together, and, to some ex- 
tent, on their density; in other words, on their 
relative induration. The relative ease of blast- 
ing, on the other hand, depends on the cement 
which binds the particles together, or their co- 
hesion; on the original or secondary planes of 
weakness in the rock, such as bedding planes, 
flowage surfaces, fault fractures, shrinkage 
joints, compression joints, etc.; also on the 
presence or absence of grain in the rock. It is 
thus seen that many variables enter into the 
^problem. An idea as to the cost of excavation 
can best be reached perhaps by arranging the 
various rocks to be excavated in the Nicaragua 
Canal, together with other known types, in a 
scale showing relatively their induration, which 
may be regarded as determining the cost of drill- 
ing, and their toughness, which determines the 
cost of blasting. 

It should be noted that the arrangement is 
based on the character of the various classes of 



rocks as they actually occur in this region in a 
more or less disintegrated and weathered condi- 
tion. If the rocks were entirely unaltered their 
relative position in the scale might be quite dif- 
ferent from that given. 



Relative Induration. 

Basaltic tuff. 



Brito sandstone. 

Limestone of Chi- 
cago drainage canal. 



Volcanic sandstone. 
Machuca sandstone. 
Dacite. 

Basalt. • 



Granite (unaltered). 



1 
2 
3 
4 
5 
6 
7 
8 
9 
10 

11 
12 
13 
14 
15 
16 
17 
18 
19 
20 



Relative Toujrbness. 

Basaltic tuff. 



Brito sandstone. 



Machuca sandstone. 

Limestone of Chi- 
cago drainage canal. 

Volcanic sandstone. 



Basalt. 
Dacite. 



Granite (unaltered). 



The basaltic tuff is at the bottom of the scale 
both in induration and toughness, and there may 
perhaps be some question as to the propriety of 
placing it in the class of hard rock. 

The Brito sandstone is low in the scale of 
induration because it is composed largely of soft 
minerals bound together by a calcareous cement. 
It is low in the scale of toughness because it is 
intersected by well marked bedding planes and 
also, to a greater depth than the excavation will 
reach, by many joint planes. 

The Machuca sandstone is low in the scale of 
toughness because of its bedding and joint 
planes, and rather high in induration because of 



APPENDIX II.— GEOLOGIC REPORT 



161 



the considerable proportion of quartz which it 
contains. 

Dacite and basalt are rather high both in the 
scale of relative induration and relative tough- 
ness because of the hardness and cohesion of 
their constituent minerals and the scarcity of 
primary or secondary planes of weakness in the 
rock. Joint planes are somewhat more abimd- 
ant in the basalt than in the dacite, otherwise 
the former would be higher in the scale of tough- 
ness than the latter. 

It will be readily understood that the above 
table represents conclusions arrived at, not by 
any exact methods, but by a careful consideration 
of the physical characteristics of the rocks in 
question and an attempt to assign to these vari- 
ous characteristics their proper weight as affect- 
ing the result. Too much importance should 
not, therefore, be attached to the conclusions 
there expressed, and it is quite possible that 
actual experience may materially alter the rela- 
tive positions which the various rocks may oc- 
cupy in the table. 

CHAKACTEK OF DATA ON WHICH 

GEOLOGIC SECTIONS AKE 

BASED. 

The facts on which are based the conclusions 
stated in this report and on the various sections 
furnished to the engineers for use in making esti- 
mates are derived from three sources: first, bor- 
ings made under the direction of the present 
Commission ; second, the examination of surface 
outcrops and natural sections; and, third, records 
of borings made by the Canal Company. 

Boeing Operations. — The outfit employed in 

the boring operations recently carried on under 

the direction of the Commission consisted of 

two parts: the Pierce well-driving outfit, and the 
11 



diamond drill. Bv means of the former a two- 
inch casing was driven down through the uncon- 
solidated residual or alluvial material at the sur- 
face into the soft rock and in some cases to the 
hard rock. Tlie diamond drill w^as then set up 
and the section continued to any depth required. 
During the process of driving the pipe, samples 
of the material passed through were taken at 
frequent intervals and a complete suite pre- 
served. All the core obtained bv means of the 
diamond drill has been preserved and arranged 
in the order in which it was taken. Wherever 
the rock failed to core, the material brought up 
by the water was collected and samples pre- 
served. Four hundred drill sections Avere ob- 
tained in this manner, having an aggregate 
length of 12,337 feet. These sections are dis- 
tributed as follows: At the La Flor dam site 
four sections, with a total length of 528 feet; 
Brito harbor, thirty-nine, with a total length of 
1773 feet; on the excavation line near the end of 
the Rio Grande gorge and at Las Lajas, eleven 
sections with a total length of 668 feet; at the 
various dam sites and embankment lines on the 
east side, 101 sections, ^vith a total length of 
4590 feet; in the channel of the San Juan river, 
239 sections, with a total length of 4018 feet; 
and in the Eastern Divide, four sections, with a 
total length of 759 feet. 

Surface Examinations. — The value of the 
surface examinations varied somewhat widelv. 

ft' 

In some portions of the region outcrops are so in- 
frequent that little information concerning the 
character of the rocks could be secured bv such 
an examination and it was therefore devoted 
chiefly to the physiographic features. Enough 
residual boulders were usuallv found in the clav 
at the surface to determine the character of the 
underlying rock, although the limits of the vari- 
ous formations could rarelv be determined with 



162 



NICARAGUA CANAL COMMISSION 



accuracy by this means. West of Lake Nicara- 
gua the iiifonnation to be obtained by surface 
examination is much greater than in the eastern 
division. This is chiefly due to the much great- 
er depth of the residual mantle in the latter 
than in the former region. Also the sea and 
lake cliffs and the stream channels give tolerably 
good geological sections which afford much in- 
formation concerning the character of the under- 
lying rocks. 

Records of the Canal Company's Borings. 
— The records of borings made by the Canal 
Company are the least satisfactory of the three 
sources of information. None of this work 
appears to have been done by men trained in 
making geological observations. The records 
are very meager and incomplete. There is no 
harmony in the terminology employed, and with- 
out the specimens it is generally impossible to 
gain much information from these records. 
Although many borings were made, in most cases 
they were not carried to a sufficient depth to 
furnish the definite information required. In 
most cases, except on the Eastern Divide, they 
merelv furnish a minimum measure of the un- 
consolidated surface material. When rock is 
reported there is always a question whether the 
rock is not simply a boulder. In a few cases the 
records appear to be erroneous, perhaps through 
mistakes in transcribing them. These mistakes, 
wherever thev have been detected, have been 
uniformly unfavorable to the Canal Company's 
plans so that they cannot be regarded as inten- 
tional. They serve, however, to cast a shade of 
doubt upon all the records and thus detract 
materially from any value which they might 
otherwise have. The most svstematic work 
done by the Canal Company was on the Eastern 
Divide and the La Flor dam site. The records 
at these two places, however, would have been 



quite unintelligible without the additional work 
done bv the Commission. 

GEOLOGIC DETAILS. 

Western Division. — Beginning wuth the Pa- 
cific terminus the various canal routes will be 
taken up and the geology of the immediate lo- 
calities concerned will be descrilx?d in some 
detail. This description is given wuth special 
reference to the needs of the engineers. Natur- 
ally some repetition is involved of matter con- 
tained in the first part of this report, but a re- 
iteration of some of the more important geo- 
logical facts may be made with advantage. 

La Flor Dam Site. — Section, Fig. 1, Plate 
XYII. — The boring done by the Canal Com- 
pany at the proposed La Flor dam site was more 
thorough and systematic than at any other 
point on the line. Only four holes, therefore, 
were put down by the Commission, and these 
were for the purpose of verifying the results 
obtained by the Canal Company and interpreting 
their records. As a result of this combined work 
the conditions at La Flor may be regarded as 
very perfectly known. The old river valley at 
this point has a depth of fifty feet below sea 
level, or about ninety feet below the present 
flood-plain. The section of the valley as devel- 
oped by the borings is that which would be pro- 
duced by the continuation of the present slopes 
with normal curves below the margm of the allu- 
vium. The matenal forming the sides and bot- 
tom of this old vallev beneath the alluvium is 
precisely the same as that exposed in the hills 
on either side. It is a calcareous shale contain- 
ing numerous layers of fine sandstone. This 
material has been somew^hat fullv described in a 
previous part of this report. The rock is in- 
tersected by numerous joints which break it up 
into small rhomboidal blocks. In drilling 



APPENDIX II.— GEOLOGIC REPORT 



163 



through such material very little continuous 
core is obtained since the harder sandy layers 
tend to choke the bit and grind up the softer 
portions. The material which comes to the sur^ 
face with the water then very closely resem- 
bles clay. These conditions have led to the 
designations previously applied to this material, 
such as " clav and rock in lavers; " ** rock with 
clay seams;" " argellite with clay seams;" 
" layers of stones in clay," etc. Much of the 
material has been classed as telpetate and cascajo, 
Telpetate or tepetate is a term used in Mexico 
and other Spanish- American countries for a soft, 
friable, chalky gray or yellow rock, formed by 
precipitation from calcareous water, i. e, tufa, 
or from partial solidification of volcanic ash and 
mud, i. e. tuff. 

Talpeiate is thus described by Levy:' "If 
a cloud of ashes be suspended in the air it is 
readily seen that the heavier particles are the 
first to obey the attraction of gravity and that 
the lighter are the last to reach the surface. 
Moreover, if the heavier portions are formed of 
a soft material or are in a state of semi-fusion, it 
is known that they will become round before 
they reach the earth. In Nicaragua the name 
talpetate or talpuja is given to these layers of 
ashes. It is a species of fine-grained conglom- 
erate formed of small, smooth and round balls, 
partially cemented by a finely powdered tuff. 
In some places the ash does not contain soft 
material and then it is simply deposited in the 
order of increasing density; also it is without 
cohesion and does not contain the small balls." 

Nothing which would answer this description 
occurs at La Flor, and it is clearly a misnomer to 
apply the term to this more or less disintegrated 
rock, which is distinctly of sedimentary origin, 

1 Notas Geographicas y Economicas sobra la Repnblica 
de Nicaragua, Pablo Levy, Paris, 1873, p. 145. 



and contains only a relatively small proportion 
of volcanic material. Cascajo, on the other 
hand, is properly applied to the surface rock in 
the vicinitv of La Flor. The term is defined 
by Levy as follows: 

** In Nicaragua the name laja is given to lava ; 
also the layers of stratified tfap are called lajas, 
and, in general, any rock which is distinctly and 
evenly bedded. When lajas, that is bedded 
rocks of any kind, are disintegrated, forming 
small easily di^asible fragments, this disinte- 
grated material is called cascajo." 

While the rock which forms the bottom and 
sides of the old river vallev at La Flor is more 
or less disintegrated and breaks up into small 
blocks when it is removed, it is nevertheless 
abundantly competent to sustain any pressure to 
which it would be subjected by a structure such 
as the proposed La Flor dam. It would, there- 
fore, be necessary in constructing a masonry 
dam at this point merely to excavate the allu- 
vium down to the bottom of the old channel, 
fifty feet below sea level. On the sides of the 
valley above the present alluvium, and perhaps 
a sh9rt distance below it, it would of course be 
necessarv to excavate a few feet of residual 
sandy clay and thoroughly disintegrated rock in 
order to secure a satisfactory foundation. In 
the deeper portions of the valley, however, the 
transition from alluvium to rock appears to be 
comparatively sharp and the residual material, 
if present, is very thin. 

Rio Grande Dam Site, — Section, Fig. 2, Plate 
XVn.— The two Variants I and III of the 
Childs route between Lake Nicaragua and the 
Pacific involve the location of a dam and locks at 
some point in the upper portion of the Rio 
Grande valley. The site for such a dam having 
greatest natural advantages appears to be at 
Buen Retiro, about nine miles from the lake. 



164 



NICARAGUA CANAL COMMISSION 



The soetion referred to above sliows the geologi- 
cal conditions at this point. The hill which occu- 
pies the center of the valley is composed of cal- 
careous shale more or less disintegrated, but suf- 
ficiently firm, however, for foundation purposes. 
The saddle north of this hill was formerlv a 
channel of the river, the rock bottom of which 
is about fifty feet above sea level. This is con- 
siderably below the present bed of the river and 
is approximately the same depth as the old river 
channel which is now partially occupied by the 
Rio Grande. The foundations of the dam at 
this point would, therefore, be about fifty feet 
above sea level and comparatively little silt 
would have to be excavated to place the foun- 
dations upon rock. The long gentle slopes of 
the hills south of the valley are covered by a 
tliin layer of residual clay, under which is more 
or less disintegrated rock, passing downward at 
an unknown depth into solid rock. This ma- 
terial would afford suitable foundations for locks 
or other structures. The material filling the old 
channel in the saddle is compacted, sandy clay 
and sand similar to that which partly fills the 
upper portion of the Eio Grande channel. At 
some point beneath this silt is the contact of the 
Brito shale and the underlying andesite. The 
shale appears to dip away from the andesite as 
though it had been tilted up by the intrusion of 
the igneous mass. The andesite forming the 
hill immediately north of the dam site will af- 
ford a convenient supply of excellent rocks for 
the construction of dams and controlling works 
at this point. 

Brito, — The borings made by the Canal Com- 
pany on the site of the proi>osed Brito harbor 
and shown on the published map which accom- 
panies the report of the Canal Board of 1895, 
indicate the presence of a rock ledge a short 
distance below the surface, extending from a 



point near the beach about 2000 feet, north 30° 
east, up the valley of the Eio Grande. In order 
to determine the extent of this ledge thirty- 
eight holes were drilled, their location being 
shown on the accompanying map, Plate VII. 
These holes were put down to depths between 
forty-five and forty-eight feet below high tide 
of April 20, 1S98. Bock was found in six of 
these holes but not at the depth or in the posi- 
tions indicated by the previous drilling. The 
form of the rock surface developed by these bor- 
ings is shown by means of contour lines on the 
map. It will be noticed that the rock occurs 
only near the northwestern margin of the Rio 
Grande valley. The prevailing direction of the 
wind along the beach is such, that the sand is 
drifted toward the western margin of the valley, 
and the lower portion of the Rio Grande is con- 
stantly crowded over to this side of its valley and 
for a short distance back from its mouth is cut- 
ting the cliff which forms the northwestern head- 
land. By cutting away the base of the cliff the 
river appears to have formed a narrow shelf on 
the side of the old valley where the rock is a 
comparatively short distance below the surface. 
Portions of the rock have been cut away to a 
considerable depth, but two ledges formed by 
harder beds in the sandstone extend out into the 
valley as shown by the contours. These are 
similar to the ledge which projects from the ex- 
treme outer point of the headlanfl except that 
their surface is somewhat lower. Southeast- 
ward from this rock shelf the old valley extends 
to the southeastern margin of the Rio Grande 
flood-plain, and it is probable that no rock would 
be encountered in this direction to within a short 
distance of the margin of the valley. Hence a 
harbor might be located at any point between 
the headlands with little danger of encountering 
rock in excavation. The material filling the 



NICARAGUA CANAL COMMISSION 



BRITO HARBOR 

showing location of borings 

made by '\yi^)\ 

US. NICARAGUA CANAL COMMISSION J ( 
1898. 

SCALE 

Location of Borings 
o Depth of hole below Mean "fide 

• Depth Tc rocK below Mean Tide 
Contours ofrocK sui'face below MeaoTide 




MAP OF BRITO H* 



APPENDIX 2, PLATE VII 




IG DEPTH TO ROCK. 



APPENDIX II.— GEOLOGIC REPORT 



165 



old valley consists entirely of sand near the 
present beach. A short distance back from the 
beach' the sand is overlain by fine alluvial silt 
which increases in thickness up the valley and 
forms the banks of the present Rio Grande 
channel. The greatest thickness of the fine allu- 
vium is perhaps thirty or forty feet at a distance 
of several miles from the coast. Below this 
the greater portion of the material filling the old 
river valley is sand with more or less clay silt. 

In the construction of the harbor at Brito a 
large amount of stone will be required for break- 
waters, etc. The character of the rock in the 
headlands on either side of Brito has already 
been described. That forming the northwest 
headland is thin bedded sandstone and shale in- 
tersected by many joints. It is, therefore, not 
suitable for the construction of breakwaters. 
The limestone forming the southeast headland 
can be readily quarried in blocks of any desired 
size and will doubtless be employed until the 
supply is exhausted. The next most convenient 
source of supply is in the hills north of the Rio 
Grande valley at Buen Retiro. The rock here 
is andesite, a dark, compact, crystalline rock 
with high specific gravity, 2.75, which can be 
quarried in any sized blocks required. The 
residual clay covering the hard rock is compara- 
tively thin, so that quarries can be opened with 
little dead work. 

Excavation LineSy Childs Eoute, Lake Nica- 
ragua to Pacific Ocean. — Numerous holes were 
put down bv the Canal Company, chiefly with 
the earth auger, between Las Lajas and the head 
of the Rio Grande flood-plain. The classifica- 
tion of materials for this portion of the line has 
been based largely upon the records of these 
holes, supplemented by one hole put down on 
the lake shore at Las Lajas and by an examina- 
tion of the surface conditions in the vicinity of 



the line. The underlying rock is the Brito for- 
mation, which has been already fully described. 
That part of the formation which reaches the 
surface from a point a short distance west of the 
lake to the site of the Rio Grande dam, consists 
largely of argillaceous shales containing fewer 
beds of sandstone than the portions of the for- 
mation which are exposed on the lake shore and 
on the Pacific coast. The rock is everywhere 
deeply disintegrated, and the line between the 
materials classed as disintegrated rock and as 
hard rock is difficult to draw, since the passage 
from one class of materials to the other is gen- 
erally gradual. In the classification represented 
on the section the effort has been made to draw 
this line at the bottom of the material which can 
probably be excavated without blasting. With- 
in a mile and a half of the lake the line crosses 
the Rio Lajas four times. This stream appears 
to be flowing in an old channel which was some- 
what deeper than its present channel and which 
has been silted up. The geological significance 
of this old channel has been pointed out in an 
earlier part of this report. It considerably in- 
creases the proportion of soft material to be ex- 
cavated on this part of the canal line. Beyond 
this old channel the surface is covered with a 
verv uniform layer of residual clav derived from 
the decay of the underlying shales. Its thick- 
ness varies from four to six feet and it passes 
downward somewhat abruptly into the underly- 
ing disintegrated shale or cascajo. As indicated 
by the Canal Company's borings the disintegra- 
tion of the rock has extended to a somewhat 
greater depth upon the Divide than elsewhere, 
and if the conditions are found to be as repre- 
sented on the section, the hard rock will extend 
but a few feet above the water level in the canal 
through the greater portion of the Divide cut. 
The hard rock is represented as passing below 



166 



NICARAGUA CANAL COMMISSION 



the bottom line of the canal between six and 
seven miles from the lake. 

The Rio Grande is also found to be flowing 
in an old channel which has been in part silted 
up. The present river channel occupies from a 
third to a half of the old channel. Bv a careful 
examination of the present river banks it has 
been possible to map the old channel with tol- 
erable accuracy. The Canal Company's borings 
have given its depth and upon this basis the 
canal profile has been constructed, showing the 
proportions of earth and disintegrated rock to be 
excavated. On the Childs route, Variant II, no 
excavation wnll be required between the head of 
the Rio Grande flood-plain and the dam at La 
Flor. Three sections were made bv the Canal 
Company on the site of the proposed locks in the 
hills north of the La Flor dam site. The records 
of these holes would be difficult to interpret but 
for the work done under tlie direction of the 
Commission at La Flor. The surface is covered 
with a thin mantle of residual clay which passed 
downward into disintegrated rock. Below the 
disintegrated layer the rock consists of inter- 
bedded sandstones and shales, the latter being 
rather soft and intersected by many joints. A 
considerable proportion of the material to be ex- 
cavated in these hills and in the foundations for 
the locks should be classed as hard rock, but it 
is impossible with the present information to 
make definite statements concerning the propor- 
tions of hard and soft rock. Beyond La Flor 
the excavation will be entirely in alluvial ma- 
terial consisting of clay and sand to the site of 
Brito harbor. 

Only a single route has been considered from 
the lake to the Cano Guachipilin. From this 
point westward three alternatives have been con- 
sidered. These are, the three variants of the 
Childs route described in the report of the Chief 



Engineer. Variant III follows the north side 
of the Rio Grande valley; and, Variant I follows 
the south side of the vallev. The classification 
of materials on Variant II has alreadv been 
given. Variant III provides for a dam across 
the Rio Gi-ande at Buen Retiro, the canal paSvS- 
ing through the low saddle north of the hill 
which here occupies the center of the valley. 
Ten holes were put down by the Commission on 
this line with.in a distance of about two miles 
from the crest of the Buen R(»tiro saddle. 
These holes show that the hill in the center of 
the vallev was former Iv an island in the river. 
There is an old (»hannel to the north of it, ex- 
tending to a depth of seventy feet below the 
present surface, the material with which it is 
filled being compacted sand. Three thousand 
feet beyond the saddle the line crosses a spur 
from the hills to the north, the old channel bend- 
ing to the left and joining the present river chan- 
nel. Sandstone is found beneath a thin mantle 
of residual clay on the point of this spur. Be- 
yond this the alluvium of the present Rio 
Grande flood-plain is encountered, and this ex- 
tends below the bottom of the canal entirelv to 
Brito. The hills north of Buen Retiro are 
composed of hard black crystalline rock which 
is probably a large intrusive mass in the Brito 
fonnation. 

Variant I follows the southern side of the 
Rio (jrande >'alley from a point above Buen 
Retiro to Brito. It also involves a dam at the 
same point as Variant III. The excavation on 
the south ^de of the vallev will bo chieflv in 
residual clay and disintegrated rock to a point 
nearly oj)posite the mouth of the Rio Tola. 
From this point to La Flor the excavation will 
be in the alluvial silt of the Rio Grande flood- 
plain. At La Flor the point of the hill which 
forms the southern end of the proposed La Flor 



APPENDIX II.— GEOLOGIC REPORT 



167 



dam is utilized as a site for a lock. The rock 
here is entirely a disintegrated sandy shale, and 
probably no solid rock would be encountered. 
The remainder of the excavation to Brito will 
be entirely in alluvial silt with the exception of 
a short distance through a hill on the south side 
of the valley which has been selected as a lock 
site. The depth of the residual clay in this hill 
has been taken at about twelve feet, and it is 
assumed that below this will be found disinte- 
grated rock extending below the bottom of the 
lock foundation. This disintegrated rock, how- 
ever, is abundantly competent to sustain any 
structure such as a lock which may be placed 
upon it. 

Dam Sites on the Rio San Juan. — Sections 
showing the geological conditions at the pro- 
posed sites of eight dams across the San Juan 
have been prepared for use by the engineers in 
making estimates. Xo boring w^as done with 
special reference to three of these sections which 
are therefore based upon the general series of 
river holes. Five of the proposed sites were 
more or less thoroughly investigated with special 
reference to their use for dams. The sections 
of these will be found on Plate XVII. 

Castillo. — At Castillo the site selected for a 
dam required by one of the variant plans, is 
immediately above the rapids. But little bor- 
ing was required here to determine the character 
of the material forming the river bed and hence 
the foundation of the proposed dam. The rap- 
ids are formed by solid ledges of basalt included 
with the group of trap rock already described. 
At low Stages of the river the rock can be readily 
examined on either side. It is intersected by 
horizontal joint planes which give it somewhat 
the appearance of a stratified rock. It is be- 
lieved that the rock in the bed of the river is 
firm and solid and will fonn a suitable founda- 



tion for any structure which it may be desired 
to place on it. In the hills on either side of 
the river the rock is considerably fractured near 
the surface and the slopes are covered with 
talus, but the solid rock is exposed at various 
points and no difficulty need be apprehended in 
securing suitable anchorages. Three holes were 
put down here, two on opposite sides of the 
rapids, and one below on the south side. The 
first two penetrated solid rock from the bed of 
the stream downward, while the one below the 
rapids revealed a deep hole excavated in the rock 
in the nature of a large pothole. Some addi- 
tional topography should be taken on the north 
side of the river before a suitable site for locks 
can be selected. 

Upper Machuca. — The next site selected as a 
possible dam site is about three miles above Ma- 
chuca. Xo borings were made directly upon 
this site so that the section rests largely upon 
inferences from the character of the river bed 
as revealed by borings short distances above and 
below. The rock here is calcareous sandstone, 
belonging to the Machuca formation, which is 
not usually found weathered to anything like 
the same depth as the igneous rocks of the 
region. Solid rock is usually found under a 
few feet of sand in the river channel, but the 
rock in the adjacent hills is probably weathered 
down nearly to the same level as the surface of 
the solid rock in the channel, so that the an- 
chorages must be in residual clay and soft rock. 

Machuca. — Section, Fig. 3, Plate XVII. — 
The Machuca dam site is located about half a 
mile below the mouth of the Cano Machuca at 
the upper end of Campaiia island. Six holes 
were put down on the center line; one on the 
north bank of the river, one in each channel on 
opposite sides of the island, and three on the 
south bank. The Machuca sandstone is exposed 



168 



NICARAGUA CANAL COMMISSION 



on the north bank of the river. It is a fine- 
grained, light bluish-gray rock, evenly bedded 
and closely resembling a fine-grained quartzite. 
It, however, contains some carbonate of lime as 
well as some feldspathic minerals and much dis- 
seminated pyrite. The beds have a dip of about 
12° to the west, that is upstream. 

The hole on the north bank penetrated twelve 
feet of tough red clay and then twenty-six feet 
of soft vellow and w^hite rock derived from the 
decay of the Machuca sandstone, and at a depth 
of thirty-eight feet from the surface encountered 
a hard sandstone similar to that exposed on the 
river bank. In the center of the north channel 
a few inches of sand were found, under which 
is hard sandstone. The sandstone is also ex- 
posed on both sides of Campafia island near 
its upper end. It here has the same character 
as on the north bank. At the extreme upper 
point of the island there are large blocks of ig- 
neous rock which appear to be nearly if not 
quite in place. This rock is a weathered dio- 
rite and probably occurs as a dike intersecting 
the Machuca sandstone. In the center of the 
south channel there are about seven feet of 
boulders and sand, then twelve feet of soft rock, 
below which the hard sandstone is encountered 
at a depth of thirty-five feet below the water 
surface. The two holes located on the south 
bank near the outer and inner edges of the flood- 
plain, penetrated silt and sand to a depth of 
about twenty-eight feet from the surface, and 
then soft rock for a distance of about twenty 
feet. The hole upon the river bank reaches 
hard rock at a depth of fifty feet below the sur- 
face. The hole on the hillside at the south end 
of the dam shows forty feet of red and yellow 
clay and ninety feet of clay and soft rock. The 
great depth to which the rock is here weathered 
is somewhat surprising since it does not appear 



to differ essentially from that found on the north 
side of the river, where the depth of weathered 
material is only moderate. It seems probable 
that the presence of the diorite dike in the sand- 
stone has led to its more rapid decay here than 
elsewhere. Large blocks of the diorite are 
found at the head of the island, as stated above, 
and residual boulders of the same rock are found 
in the red clav on the hills south of the river. 
It is quite probable that hard rock wnll be found 
much nearer the surface a short distance either 
up or down the river. The influence of the 
dike probably does not extend more than a few 
hundred feet on either side of the center line of 
the dam. Of the two channels the one on the 
north side of Campafia island now carries the 
most water. The south channel, however, was 
form(»rly much the larger and this channel has 
been contracted to half its original dimensions 
by the deposition of silt. At present the river 
appears to be cutting only upon the north bank. 
Conchuda, — Xo borings were made with a di- 
rect reference to the investigation of a dam site 
at this point. A few holes were put down in 
the vicinity, however, which afford a fairly 
satisfactory measure of the depth of the old river 
channel and afford some information concerning 
the character of the rock and the depth of rock 
decay. The depth of the old river channel is 
about sixtv-five feet below the level of the flood- 
plain, or four feet above sea level. This old 
river channel is partially filled with fine clay, 
silt and sand. The river appears to be cutting 
its southern bank and has perhaps recently modi- 
fied the slope of the old valley. The rock in 
this region is a sandstone containing a very 
large proportion of volcanic material. In a 
hole on the point of the hill at the Conchuda 
cut-off the depth of the residual clay was found 
to be fifty-four feet. Below this soft rock was 



APPENDIX II.— GEOLOGIC REPORT 



169 



penetrated to some distance, growing gradually 
harder and probably passing into hard rock at 
a depth of about sixty-five feet from the surface. 
It will be readily understood that the informa- 
tion concerning conditions at this point is suffi- 
cient only for a preliminary estimate and that 
further boring would be necessary before final 
plans could be made if it should be selected as 
a dam site. 

Boca San Carlos, — Section, Fig. 4, Plate 
XVII. — The dam site at the Boca San Carlos 
extends from the point of a spur' connected with 
the high hills lying between the San Juan and 
the San Carlos and a long spur from the lower 
hills to the north of the San Juan valley. Six 
holes were put down on the center line of the 
dam site and one at a little distance from it to 
the east. Of these one is upon the flank of the 
hill to the north, three on the flood-plain, one 
in the river channel near the northern bank and 
one on the hill to the south of the river. The 
sections derived from four of these holes are 
shown on Plate XIII. On the north side of the 
river above the margin of the flood-plain the red 
and yellow clay has a depth of about twenty 
feet. Below this is soft rock containing many 
residual boulders derived from the decav of ba- 
saltic lava. The depth to hard rock, which was 
reached only in one of three holes, above the 
flood-plain, and tliat at a distance of 1000 feet 
east of the dam line, is probably between fifty 
and sixty feet from the surface. The holes 
upon the flood-plain and at the edge of the 
river channel pass through silt and sand to a 
maximum depth of fifteen feet below sea level 
or eighty-two feet below the surface of the flood- 
plain. This is the greatest depth of the old 
river channel at this point. The position of the 
present river is at the extreme southern side of 
the old channel, and it appears to be cutting 



this bank to a moderate extent. On the south 
side of the river the red and yellow clay has a 
depth of forty feet and the soft rock an equal 
depth, making the distance from the surface to 
hard rock eighty feet. Both the residual clay 
and the soft rock contain many residual boulders 
of hard rock, and the distinction between the 
two clashes of material is not sharp. The ma- 
terial filling the old river channel is in part 
black sand and in part fine blue sandy clay silt. 
The sand is doubtless derived from the San 
Carlos river, being similar to that found in the 
river channel from the mouth of the San Carlos 
to the sea. When the San Juan is low and the 
San Carlos is in flood, the current in the former 
is reversed, and the black sand brought down 
by the latter has been carried some distance up 

the San Juan. The silt and the sand are not 
separated by a distinct plane, but are to a certain 

extent interstratified at their contact. 

It is evident that the foundation for a masonry 
dam will have to be carried down to solid rock, 
which is found at the bottom of this old channel. 
At the ends of the dam the foundation should 
be carried down to hard rock, at least as far into 
the hills as the end of the crest over which the 
water is allowed to discharge. Beyond this the 
soft rock will probably afford a sufficiently solid 
foundation. 

Oc/roa.— Section, Fig. 5, Plate XVII.— More 
systematic work was done under the direction of 
the Commission at Ochoa than elsewhere, and 
the information concerning the underground 
conditions is correspondingly complete. The 
conditions actually found and inferred were rep- 
resented for use of the engineers by means of 
seven section^s — three transverse and four longi- 
tudinal. One transverse section (C), the one re- 
ferred to alMJve, Fig. 5, Plate XVII, is approxi- 
mately upon the center line of the proposed dam 



170 



NICARAGUA CANAL COMMISSION 



as located by the Canal Company. This section 
is based on the results obtained in eleven holes 
and may be regarded as very accurately repre- 
senting the conditions as they actually exist. 
Two additional sections are given parallel with 
the center line of the dam and about two hun- 
dred feet on either side. The downstream sec- 
tion (B) is based on two holes on the south side 
and one on the north side of the river. So far 
as they were determined the conditions here cor- 
respond very nearly with those on the center 
line. The upstream section (A) is based on the 
inferred rock slopes represented on the longitu- 
dinal sections. 

It should be noted that two distinct classifica- 
tions are represented on this section. One is 
purely from the engineer's standpoint and con- 
sists as elsewhere of alluvial silt, residual clay, 
soft rock and hard rock. The geological classi- 
fication has been referred to on a previous page 
and is quite different. Thus the residual clay 
and soft rock are derived from three entirely 
distinct formations, which differed somewhat 
widely in their original composition and appear- 
ance. The hard rock on the south side of the 
river is composed of two distinct varieties of 
lava, while that on the north side is composed 
of a volcanic conglomerate or sandstone. The 
residual clay as elsewhere is deep red in color 
for a distance of ten or twelve feet from the 
surface, below which it is generally blue or gray, 
and becomes less plastic downward. It merges 
into soft rock by insensible gradations, so that 
the line separating the two classes of material 
is here as elsewhere to a large extent arbitrary. 
As stated above, the soft rock is derived from 
three distinct formations, and its character varies 
somewhat with the original character of the 
rock. The most compact is that derived from 
the volcanic sandstone. Next, that derived 



from the dacite, although the latter is apt to be 
talcose and hence would not form a reliable 
foundation material. The soft rock derived 
from the basalt varies in character with the 
original character of that rock. Where the lat- 
ter was compact the material resulting from its 
weathering is also compact, and where it was 
vesicular the resulting material is porous. 

Lower Ochoa, — Section, Fig. G, Plate XVII. 
— Six holes were ])ut down at the proposed dam 
site at lower Ochoa, two on either bank and two 
in the river channel. These holes reveal con- 
ditions which are very much less favorable for 
foundations than was anticipated. The rock 
forming the surface is a volcanic conglomerate 
or breccia somew^iat similar to that underlying 
the basalt at upper Ochoa. On the south side 
of the river this is weathered only to a moderate 
depth of about forty-five feet, while on the north 
side it is weathered to a much greater depth, in 
fact, entirely to the bottom of this formation. 
On the south side it has a depth of about fifty 
feet, and is underlain bv a bed of hard basalt. 
The upper surface of the basalt, which is doubt- 
less a lava flow, dips rapidly to the north and 
passes from about thirty-five feet above sea level 
on the south side to eighty-five below sea level 
on the north side of the river. As stated above, 
the volcanic conglomerate and basalt are in con- 
tact on the south side of the river, but on the 
north they are separated by the thin edges of 
two other formations. These are a bed of soft 
talcose volcanic rock, probably tuff, about 
twenty feet thick and a bed of extremely soft 
sandstone or partially cemented sand which con- 
tains nunioriiis fragments of wood, leaves, etc. 
This latter material is undoubtedly of sedimen- 
tary origin, but the constituents are probably 
derived in large part from a volcanic source. 

It is thus seen that in order to secure a solid 



APPENDIX II.— GEOLOGIC REPORT 



171 



foundation on the north side of the river it would 
be necessary to go down to the surface of the 
basalt, which is eighty-five or more feet below 
sea level and at least 135 feet below the surface 
of the river. 

Tamhor Grande, — Section, Fig. 7, Plate 
XVII. — Five holes were put down at tlie Tarn- 
bor Grande dam site, two on either bank and one , 
in the river channel. The geological condi- 
tions found at this site are more uniform than 
those observed at any other point. Only a 
single gf^ological fonnation was encountered, 
namely, dacije. This is a rather coarse granu- 
lar gray crj'^stalline rock which weathers uni- 
formlv from the surface downward, the weath- 
ered products containing no residual boulders of 
fresh rock. The surface, as elsewhere, is cov- 
ered with red clay which passes down into the 
soft rock by a gradual transition. The soft 
rock in turn becomes gradually harder down- 
ward, and at a depth varying between 100 and 
120 feet from the surface the rock becomes suf- 
ficiently hard to yield a continuous core with the 
diamond drill. The surface of the hard rock 
has a somewhat more gentle slope than the pres- 
ent land surface. The hole in the river channel 
and the one on the flood-plain north of the river 
revealed the presence of an old river channel of 
great depth. The hole on the flood-plain passed 
through thirty feet of fine silt, then alternate 
beds of silt and sand, and, at a depth of eighteen 
feet below sea level, j)enetrated the soft weath- 
ered dacite, and, at forty feet below sea level, 
hard rock. The hole in the river penetrated 
black sand to a depth of 108 feet below sea level 
when the hard dacite was encountered. The 
black sand throughout the entire distance was 
very uniform in character, except that a few 
boulders were found immediately overlying the 
hard rock in the bottom of the channel. Draw- 



ing a line through the points which mark the 
bottom of the alluvial material and continuing 
the slope of the southern bank downward until 
it meets the other line, a symmetrical curve is 
obtained which probably very nearly represents 
the outline of the old river channel. The find- 
ing of a sand-filled channel at the Tambor 
Grande site was by no means a surprise, though 
it was scarcely expected to find it so deep. From 
the borings which had been made at various 
points on the river above, it was found that the 
old river channel had a fairly uniform gradient 
which was considerably steeper than the gradient 
of the present river. Thus from Castillo to 
Ochoa the gradient averages three feet to the 
mile, while from Ochoa to Tambor Grande it 
averages 5.8 feet to the mile. The observed 
irregularities in the gradient are doubtless con- 
nected with variations in the hardness of the un- 
derlying rock. 

EMBANKMKirr Lines. — San Carlos, — Two em- 
bankment lines have been examined connecting 
the hills southeast of the Boca San Carlos with 
the upper and lower dam sites. The section of 
the embankment line which reaches the river at 
upper Ochoa is based upon surface examination 
and borings made by the Canal Company. The 
conditions are verv similar to those found at the 
south end of the Ochoa dam site. The rocks of 
the region are basalts forming a heavy mantle of 
deep red clay at the surface with soft rock be- 
low, both the clay and soft rock containing 
numerous residual boulders. The depth from 
the surface down to hard rock is probably from 
sixty to one hundred feet. The line reaching 
the river at lower Ochoa is based upon surface 
examination and seven holes put down under the 
direction of the Commission. From the river 
to a point where the line approaches nearest 
Cano Curano the surface rock is the volcanic 



172 



NICARAGUA CANAL COMMISSION 



conglomerate shown in the section at lower 
Ochoa. This is weathered to a great depth, 
forming a brown sandy clay; The holes were 
put down below sea level, varying in depth from 
80 to 130 feet, but did not reach hard rock ex- 
cept in the hole farthest from the river where 
the rock is basalt similar to that on the upper 
line. It was assumed in investigating these em- 
bankment lines that the waste-wxirs and sluices 
would be of such a character that firm clay 
would afford a suitable foundation. If a rock 
foundation is essential it will be found at a 
much shorter distance below the surface on the 
upper than on the lower line. It is thus seen 
that the upper and lower embankment lines have 
about the same relative advantages as do the 
corresponding dam sites. 

San Francisco, — See sections. Figs. 1 to 4, 
Plate XVIII. — On the San Francisco embank- 
ment line borings were made by the Commis- 
sion only on the flood-plains of the streams to 
determine the depth of their alluvial deposits. 
Three holes were put down in the Florida la- 
goon, three in the flood-plain of the San Fran- 
cisco, and one each at the Nicholson and Chan- 
chos. A study of the physiography of the re- 
gion had already indicated the existence of an 
old land surface developed in the region when it 
stood at a higher altitude than now and subse- 
quently in part concealed by the alluvial deposits 
of the present streams. These borings deter- 
mined the character of the alluvial materials 
and the depth of the former valleys. It was 
found that the slopes of the present valleys if 
continued below the covering of alluvium would 
coincide with the surface of the old vallev. The 
depth of the alluvial filling having been deter- 
mined at a few points, it was possible to draw 
contours representing the surface of the old val- 
leys, and thus to show the probable depth of the 



alluvium at any point. There are two swamps 

crossed bv the embankment line between the 
Florida lagoon and the Chanchos which have not 

been investigated with the drill. Since these 

swamps occupy valleys trilnitary to the Danta 

and the Nicholson thev could not have been 

»• 

deeper than the tnmk valley at the point where 
they joined the latter. The depth of the allu- 
vium in the trunk valley having been deter- 
mined, it is therefore certain that the depth in 
the tributary will be at least no greater. Hence 
while the section through these swamps is based 
upon an inference, it is of such a character that 
it is considered nearly as satisfactory for giving 
a maximum measure of the silt as an actual ex- 
amination with the drill. In all of these old 
valleys residual clay and soft rock are found be- 
neath the alluvium, although they are not so 
thick as upon the adjacent hills. The rock ob- 
tained beneath the alluvium and residual mate- 
rial is only moderately hard, consisting chiefly of 
talcose volcanic tuff with the thin bed of earthy 
limestone already described at the San Fran- 
cisco. The remainder of the section showing 
the geological conditions and classification of 
material in other portions of the San Francisco 
embankment line than those noted above, is 
based upon a few borings made by the Canal 
Company or on inferences from borings made 
bv the Commission at various dam sites in the 
vicinity. 

Tamhorcito Point. — One of the alternative 
lines at Tamborcito swings to the south around 
the point of the hills and avoids the deep cut 
involved in the other line. It encroaches, how- 
ever, upon the channel of the river and requires 
an embankment from the point of thq hills to 
the lower end of Tamborcito island and thence 
across the northern channel to the north bank. 
No reliable information is available concerning 



APPENDIX II.— GEOLOGIC REPORT 



173 



the character of the foundation for this embank- 
ment. A line, however, has been drawn on the 
section to indicate the probable limit of the allu- 
vial material. This line is based on the known 
depth of the old river channel at Tambor Grande 
and on the slopes of the adjacent hills. The ma- 
terial below is probably hard rock similar to that 
exposed at water level and in the point of the 
hills. That above the line is chiefly black sand 
with sandy silt forming the island and the flood- 
plains north of the river. It should be clearly 
understood that this line represents only a fair 
degree of probability. There can be little 
doubt, however, that the black sand has a depth 
of at least eighty feet on the line of the embank- 
ment, and it may be considerably greater. Hence 
it will probably be necessary to design an em- 
bankment which can rest upon this sand as a 
foundation. 

Tamhorcito Lagoon, — Section, Fig. 5, Plate 
XVIII. — An essential part of the plan which 
involves the construction of a dam at Tambor 
Grande, is an embankment connecting the hills 
immediately south of the river with the high 
land in the interior. This necessitates the filling 
of a few gaps in the crest of the hills between 
the river and Tamborcito creek. This latter 
stream meanders through a broad alluvial flat, 
similar to those which border the San Francisco 
and Danta creeks. This alluvial flat is a lagoon 
more or less perfectly silted up and forested. 
Four holes were put down to determine the 
depth of the alluvial material. The old resid- 
ual surface beneath the alluvium is found to 
be somewhat irregular, as might have been ex- 
pected from a consideration of the geological 
historj^ of the region. The greatest depth of the 
alluvium was found to be eighty-six feet, or 
forty-six feet below sea level. Since the foun- 
dations for an embankment of the height re- 



quired would have to rest upon material at least 
as firm as residual clay, the difficulties of con- 
structing such an embankment across the Tam- 
borcito valley would be very considerably great- 
er than across the San Francisco valley. This 
embankment line, therefore, has about the same 
degree of availability compared with the San 
Francisco embankment line as the Tambor 
Grande dam site has compared with the Ochoa 
dam site. 

Excavation Lines, Eastern Division. — River 
Sectioriy Lull Route. — The information con- 
cerning the materials fonning the bed of the 
San Juan is based chiefly upon a series of bor- 
ings made under the direction of the Commis- 
sion, extending from a point in Lake Nicaragua 
one and a quarter miles from its outlet down the 
river to the Colorado junction. From the lake 
to the Toro rapids the holes were put down at 
intervals of 1000 feet with intermediate holes 
wherever rock was encountered or its presence 
above the datum suspected. Between the head 
of the Toro rapids and Castillo the holes were 
put down at irregular intervals at points deter- 
mined by the configuration of the banks and the 
presence of rock outcrops. Five holes were 
put down at intervals of 1500 feet on the cut-off 
between Sombrero de Cuero and Santa Cruz. 
From Santa Cruz to Machuca the holes were at 
intervals of about half a mile. So far but a 
single line of holes was put down as nearly as 
possible to the probable center line of the canal. 
Below Machuca another plan was adopted. Cer- 
tain points on the river were selected at inter- 
vals of two or three miles and at each a trans- 
verse section of the river channel was developed. 
The principal object here was to determine the 
depth and form of the old river channel which 
extends from Machuca to the sea. Additional 
holes were also put down between the sections 



174 



NICARAGUA CANAL COMMISSION 



to determine the depth of the old channel and 
the character of the rock in the river bed. 

The results of this work are shown on the 
profiles of the river section and may be briefly 
summarized. Between the lake and the Toro 
rapids the only points at which rock was found 
in the river channel were in the immediate vi- 
cinity of the hills which rise abruptly above the 
broad alluvial plain. The conclusion reached 
independently from a study of the surface feat- 
ures of the region were thus verified by the drill- 
ing operations, viz.: that the region once had 
considerably greater relief, but has recently been 
submerged by the waters of the lake, and the 
lower portions of the land surface concealed by 
the alluvium which has filled their irregularities. 
While the work is not sufficiently extended to 
develop this old topography to any considerable 
extent, it has shown that the slopes of the old 
land surface beneath the cover of alluvium are 
essentially continuous with the slopes of the hills 
which rise above the low-level plain. This con- 
clusion has very greatly supplemented the in- 
formation obtained by drilling and has afforded 
a basis for the construction of numerous sections, 
both longitudinal and transverse to the river 
channel at all points where rock was found. 
These sections have been used to determine the 
distance that the canal line should be shifted 
away from the hills in order to reduce the 
amount of rock excavation to a minimum or 
avoid it entirely. Since it is probable that the 
canal line can be so located between the lake and 
the Toro rapids as to avoid all rock excavation, 
the character of the rock found at various points 
in the channel of the river is not of great im- 
portance. It may be stated, however, that these 
rocks all belong to the class of traps already des- 
cribed. AVhile a consideration of the physio- 
graphy of the region as well as the results of 



the boring in the Toro rapids indicates the pres- 
ence of an old channel below the bottom of the 
canal, but subsequently filled with alluvial ma- 
terial, it is probable that this channel cannot be 
followed by the canal and consequently some 
rock excavation will be required. The princi- 
pal part of this will probably be on the point 
opposite the mouth of the Rio Sabalos. The 
rock here is a rather soft red rock, probably an 
altered vesicular lava, although it may possibly 
be a consolidated tuff. No samples sufl[iciently 
fresh for exact determination were obtained. 
But little excavation will be required below the 
Toro rapids, except on the cut-off between Som- 
brero de Cuero and Santa Cruz. Five holes 
were put down approximately on the canal line 
between these points. No rock was encoun- 
tered, the material being in part alluvial and in 
part residual. The alluvial material was chiefly 
verj' fine blue clay, some portions of which con- 
tained a large proportion of vegetable matter. 
The residual clay was red and mottled and in 
places somewhat sandy, containing some of the 
original minerals but partially decomposed. A 
little hard rock will be found above the datum 
75 between Santa Cruz and Castillo. This be- 
longs to the class of trap already described. Be- 
low Castillo the river bed is nearly everywhere 
below the datum 75 and no excavation will be 
required, except a small amount of sand, until 
the Balas rapids are reached, where the rock 
rises about eight feet above the datum for a 
short distance. The rock here is the Machuca 
sandstone which will probably be found more or 
less disintegrated to a depth somewhat greater 
than the excavation. Throughout the whole ex- 
tent of the Machuca rapids rock occurs in the 
bed of the river. It is seldom covered by more 
than a few feet of sand and boulders. Hence, 
if a lock is located at the upper Machuca dam 



APPENDIX II.— GEOLOGIC REPORT 



175 



site considerable rock excavation will be required 
between that point and Machiica. This excava- 
tion will be in the Machuca sandstone, and, as 
shown in the section of the dam site at Machuca, 
the extent to which it is weathered is somewhat 
variable. The depth of residual clay repre- 
sented on the section is more probably a mini- 
mum than an average measure, and the amount 
of excavation in hard rock may be considerably 
less than the estimates which have been made. 
The character of the rock at the Machuca dam 
site has alreadv been described. Bevond this 
point, through the Aguas Muertas, no excava- 
tion will be required, except in cut-offs, even if 
a drop is made both at the upper and lower 
Machuca dam sites. In the cut-off at Conchuda 
the greater part of the excavation will be in 
residual clay and soft rock. A core of hard 
rock in the highest ridge crossed probably ex- 
tends to an elevation of seventy feet above 
tide, or twenty-five feet above the bottom of the 
canal on the plan which provides for two locks 
above this point. If the summit level is con- 
tinued eastward to the Boca San Carlos it is 
probable that no hard rock will be encountered 
in the Conchuda cut-off. 

Menocal Route, — The section of the high- 
level canal line from Ochoa to Greytown is based 
entirely upon borings made by the Canal Com- 
pany, with the exception of four on the Eastern 
Divide. These were put down to an elevation 
of sixty feet above sea level, or fifteen feet below 
the proposed excavation line. From the infor- 
mation afforded by these four sections in the 
Eastern Divide a part of the data obtained by 
the Canal Company has been rendered intel- 
ligible. Fourteen holes were put down in the 
divide by the Canal Company, most of them ex- 
tending to an elevation of seventy-five feet above 
sea level, but the terms employed in describing 



the material encountered are so vague and often 
meaningless that they have very little value in 
classifying material. 

The comparatively simple geological condi- 
tions which prevail in the Eastern Divide are 
shown on the section. Fig. 6,' Plate XVIII. 
The rocks forming these hills are entirely ig- 
neous in origin. They include three distinct 
varieties. Since they all weather at the surface 
to a red clay, the discrimination of these varie- 
ties and the determination of their underground 
relations would be impossible except for the in- 
formation afforded bv the drill. The rock form- 
ing the surface on the western side of the divide 
consists of basaltic or andesitic tuff. On the 
Canal Company's sections this is called " telpe- 
tate,^' " concrete," " conglomerate " and " slate." 
It is a dark greenish brown in color, generally 
fine-grained, but occasionally showing frag- 
ments of basalt or andesite and is generally soft 
and talcoee. On exposure to the air it loses 
water, and crumbles. The surface of this basalt- 
ic tuff dips eastward at an angle of five degrees. 
It is overlain by a lava flow of dacite about 240 
feet in thickness, which also dips eastward at a 
low angle. The dacite also has a variety of 
designations on the Canal Company's sections. 
It is called "concrete," " conglomerate," "trap," 
" talc " and " dacite." It is deeply weathered, 
but becomes gradually harder downward and at 
depths of 50 to 175 feet below the surface it is 
a comparatively fresh, hard rock. Although the 
dacite does not crumble when exposed to the 
action of the atmosphere, as the tuff, it weathers 
quite rapidly. Cores which were taken out by 
the Canal Company and left on the surface 
showed, after an exposure of seven years, a zone 
of weathering which had penetrated to a depth 
of one-tenth of an inch. This rate of alteration 
is very much more rapid than would be permis- 



176 



NICARAGUA CANAL COMMISSION 



sible in any building stone. The surface of the 
daeite dips eastward at an angle of about 5 de- 
grees, and it is overlain by basaltic and andesitic 
lavas which extend eastward to the margin of 
the San Juan delta. These lavas in the Canal 
Company's sections are termed " telpetate,^^ 
"trap," "talc," "concrete" and "andesite." 
They weather in an irregular manner, unlike the 
daeite. Many residual boulders of fresh rock 
occur in the red clay at the surface, but the 
depth to continuous hard rock is perhaps greater 
than in areas underlain by the daeite. 

As shown on the section of the Eastern Di- 
vide tlie sides of the western third of the cut 
would be wholly or in part composed of the ba- 
saltic tuff. This material, as explained above 
(p. 126), when exposed to the air crumbles rap- 
idly, and it would therefore constitute a source 
of considerable danger to the permanence of the 
walls. It might be sufficiently firm when first 
exposed to sustain the pressure to which it would 
be subjected but would probably disintegrate so 
rapidly on exposure as to undermine the daeite 
and produce slides. 

An attempt has been made to estimate the 
proportion of material which would be excavated 
from the Eastern Divide cut suitable for dams or 
other structures. It appears probable that the 
material which would be taken out in blocks of 
sufficient size and which would resist disintegra- 
tion, is confined wholly to the bed of daeite. 
The tuff underlying the daeite can be removed 
from consideration at the outset. Even if it could 
be taken out in blocks of sufficient size, which is 
extremely doubtful, it would rapidly disinte- 
grate when exposed to the action of the atmos- 
phere, and it would thus introduce an element 
of weakness into any structure to which it was 
applied. Practically the same may be said of 
the basaltic and andesitic lavas overlying the 



daeite. While some durable material might be 
derived from the residual boulders in the clay 
and soft rock, it is not probable that any consid- 
erable body of solid rock would be found on the 
line of excavation above the elevation of 75 A. 
T. In the daeite itself the material classed as 
soft rock would of course be excluded, but in 
addition to this a large amount of material 
classed as hard rock from the standpoint of ex- 
cavation and of permanent slopes, would also be 
excluded from the material suitable for construc- 
tion purposes. This material is what is known 
to quarrymen as " dead rock." It gives a dull 
sound under the hammer, and when examined 
with the microscope its minerals are found to 
have undergone extensive alteration. It is usu- 
ally intersected by incipient fractures which 
quickly develop when it is exposed to the atmos- 
phere and relieved from pressure. It would be 
necessary to rigidly exclude all such material 
from all important structures. When these va- 
rious classes of objectionable material are ex- 
cluded there remains about 46 per cent, of the 
material classed as hard rock or 24 per cent, of 
the total material to be moved, which would be 
suitable for use in large and permanent struc- 
tures. 

The borings made by tlie Canal Company on 
the Menocal route at other points than the 
Eastern Divide do not in any case penetrate the 
hard rock. They therefore afford merely a 
minimum measure of the residual mantle of clay 
and soft rock which covers the surface of the 
countiy. It is probable, however, that little, if 
anv, hard rock would be encountered on the line 
of the canal, except at the Eastern Divide. The 
surface of the hard rock may extend above the 
bottom line of the canal in the divide between 
the Machado and the Danta and also between 
the San Francisco and the Xicholson. There are 



APPENDIX II.— GEOLOGIC REPORT 



177 



no exact data, however, for these portions of the 
line, and the classification of materials repre- 
sented upon the sections is derived chiefly by in- 
ference from other localities where the original 
composition of the rocks and the conditions of 
rock weathering appear to have been similar. 
The uncertainty connected with estimates based 
upon such inferences should, however, be fully 
recognized. 

Variants of the Lull Route, — The several va- 
riants of the Lull route are so nearly on the same 
line that they may be considered together from 
the point at which the line leaves the channel 
of the San Juan at Boca San Carlos to the head 
of the delta. Beyond this point the three main 
variants diverge so widely that they require sepa- 
rate consideration. 

After leaving the narrow alluvial flat border- 
ing the river above the Boca San Carlos dam site 
the line crosses a spur from the high hills to the 
northward, the highest point passed as indicated 
by the profile being 160 feet above sea level. 
No borings have been made directly on this line, 
but one made at the point of the ridge near the 
river and the series made on the line of the 
Boca San Carlos dam site indicate the depth of 
the residual clay and soft rock at this point. 
Following the rule elsewhere observed, the thick- 
nesses of the two zones are represented as in- 
creasing slightly on the higher parts of the ridge. 
The section, however, must be regarded as 
merely tentative and subject to very material 
modification on more thorough examination. 
It represents merely a tolerable degree of prob- 
ability. After passing this first ridge the exca- 
vation will be in silt and residual clay until the 
point of the hill is reached at the mouth of the 
San Carlos. Here it is probable that some soft 
rock will be encountered, but no hard rock. 

Crossing a broad, alluvial plain formed in a 
12 



tributary valley where only silt will be encoun- 
tered, the line cuts the points of the ridge west 
of the Machado. While no borings have been 
made in this ridge, the rocks are very similar to 
those encountered at the Ochoa dam site, and it 
is assumed that the residual material and the 

* 

soft rock have an equal depth. If this is the 
case no hard rock will be encountered in cutting 
these points. It is certain, however, that nu- 
merous boulders will be encountered in the resi- 
dual clav, and these will become more abundant 
in the soft rock, possibly forming more or less 
continuous layers. Excavation across the Ma- 
chado valley will of course be entirely in silt. 
The high point just east of the Machado forms 
the northern terminus of the proposed Ochoa 
dam, and the materials of which it is composed 
have therefore been thoroughly investigated. 
Above an elevation of forty-five feet above tide 
the rock was originally basalt and below this con- 
sisted of volcanic conglomerate. The latter 
weathers more rapidly than the former so that 
while a few feet at the base of the basalt are 
fresh and hard, this is underlain by twenty-five 
feet of soft rock, and the hard basalt may be re- 
garded simply as a large boulder. Beyond 
Ochoa the excavation will be across alternating 
low, alluvial flats and the points of steep ridges 
which extend down to the river. The former 
contain only silt and the latter chiefly residual 
clay with probably a few points of soft rock ris- 
ing above the bottom of the canal. Leaving the 
main valley and following up the valley of Em- 
bankment creek only residual clay and a small 
amount of silt will be encountered, until the di- 
vide is reached between Embankment creek and 
the drainage of the Danta. Borings at frequent 
intervals have been made through this divide by 
the Canal Company. While none of them pene- 
trate the rock they afford a minimum measure 



178 



NICARAGUA CANAL COMMISSION 



of the depth of the residual material, but prob- 
ably in most cases do not pass entirely through 
it. The basalt which forms the surface rock at 
Ochoa disappears at some point to the west of 
this divide, and the underlying volcanic con- 
glomerate comes to the surface. As shown by 
the borings at Ochoa, this conglomerate weath- 
ers more rapidly than the basalt, and the depth 
of the residual material, as shown by the Canal 
Company's borings and by those made at lower 
Ochoa through similar material, is considerably 
greater than where basalt forms the surface 
rock. It is probable, therefore, that only resi- 
dual clay and soft rock will be encountered in 
this divide until the point selected for the lock 
is reached, while the lock foundations will prob- 
ably be, in part at least, upon hard rock. 
Beyond the lopk the line follows a tributary of 
the Danta, and finally the Danta itself, and the 
excavation will be entirely in clay silt and resid- 
ual clay. The alluvium encountered in the 
upper portion of the Danta valley will be found 
much softer than that forming the flood-plain of 
the river. Lowei> slopes will have to be pro- 
vided for, and probably in some cases, as in the 
Florida lagoon, special precautions will be neces- 
sary to prevent the material from flowing back 
into the excavated channel. The hills crossed 
between the Danta and San Francisco rivers are 
simply the protruding points of much higher 
hills which have been nearly submerged by the 
alluvium. They are composed at the surface of 
residual clay which probably extends below the 
level of the surrounding flood-plains. The silt 
forming the San Francisco valley is similar to 
that of the Danta, but will be found considerably 
firmer. In the San Francisco hills, the points of 
which are cut by the canal line, basalt again 
forms the surface rock. The records of six holes 
drilled by the Canal Company on the line near 



the one given in the section have been utilized. 
As elsewhere they give only a minimum meas- 
ure of the residual clay. They may in some 
cases extend a short distance into the soft rock, 
but there is nothing in the record to indicate it^ 
The section is drawn, therefore, largely by in- 
ference from the depth to which the rock decay 
has been found extending elsewhere under simi- 
lar conditions. Numerous boulders will be en- 
countered almost from the surface, and these will 
increase in size and abundance downward until 
they merge with the solid rock. It is not prob- 
able, however, that any considerable body of 
solid rock will be encountered in cutting the 
points of these hills. From the San Francisco 
to the Tambor Grande hills the line crosses a 
level alluvial plain, while the surface of the resi- 
dual clay passes entirely below excavation. 
Since the line is near the river the silt will 
doubtless be found much firmer than that en- 
countered in the San Francisco valley. At 
some points between the San Francisco and 
Tambor Grande hills the basalt disappears, and 
the latter are composed entirely of dacite which 
extends at least 120 feet below sea level, and 
possibly much farther. 

As already indicated, this rock weathers in a 
manner quite different from basalt. The decay 
proceeds downward from the surface, and no 
sharply defined residual boulders remain either 
in the clay or the underlying soft rock. There 
is a gradual transition from the surface down- 
ward, and the division between the different 
classes of material is to a large extent arbitrary. 
As elsewhere, however, the rock is considered 
hard only when it will give a practically contin- 
uous core with the diamond drill. As shown on 
the section on which estimates have been based, 
the upper zone of residual clay is thinner and the 
intermediate zone of soft rock is thicker than in 



APPENDIX II.—GEOLOGIC REPORT 



179 



basalt. While the borings from which these 
thicknesses were taken were on the point of the 
ridge at the Tambor Grande dam site, at some 
distance from the line, the classification given in 
the section may be accepted with a fair degree 
of confidence. 

At some point between the Tambor Grande 
and Tamborcito hills occurs another change in 
the rocks, and the dacite of Tambor Grande gives 
place to basalt in the Tamborcito hills. At the 
water's edge in the point of the hills there is 
exposed a coarse volcanic breccia. The constit- 
uents vary in size from the smallest fragments 
np to angular blocks two or three feet in diame- 
ter. The matrix is finely comminuted rock and 
volcanic ash and is only slightly softer than the 
enclosed fragments. The rock as exposed at the 
water's edge appears to be almost perfectly 
fresh. This breccia does not extend far above 
the level of the rivier, for at numerous points on 
the sides and top of the ridge are exposures of 
weathered basalt with numerous fresh boulders. 
Two alternative lines have been located across 
the point of these hills. Line A curves to the 
south, crossing a bend in the river, the center 
line nearly touching the point of Tamborcito 
island. Line B cuts directly across the ridge, 
the highest point on the center line being 360 
feet above sea level. Xo borings have been 
made directly upon either of these lines, but a 
few were made by the Canal Company on the 
point of the ridge between the two lines, 'fhey 
di<l not penetrate the rock, however, and afford 
little information concerning the character of 
material wliich would be encountered in excava- 
tion. The classification of materials as repre- 
sented on the sections is taken chiefly by infer- 
ence from the conditions found at Ochoa, where 
the character of the rocks is somewhat similar. 
The classification must, therefore, be taken with 



considerable allowance, and the relative propor- 
tions of the three classes of material may be 
found quite different from that represented. 
The section represents, however, the best infor- 
mation available at the present time. On line 
A the hard rock is represented as reaching a few 
feet above the flowage line of the canal, involv- 
ing an excavation of about thirty-two feet in this 
material. Above this is represented a maxi- 
mum thickness of foily feet of soft rock and 
forty feet of residual clav. As elsewhere the 
slopes of the upper surface of soft rock and hard 
rock each become successivelv flatter than the 
preceding. On the alternate line B which 
crosses the ridge near its highest jx^int the resi- 
dual clay is represented with a thickness of 
seventy-three feet. This may be an extreme 
thickness, but has been observed under similar 
conditions elsewhere. The soft rock is repre- 
sented with the same thickness as on the other 
line. The hard rock is sliown reaching to an 
elevation of 260 feet. The excavation of this 
line would thus involve a cut of 230 feet in hard 
rock, and the character of the rock is such that 
the excavation would be expensive. 

From Tamborcito to Sarapiqui the line crosses 
a broad alluvial plain in which the surface of the 
residual material probably passes far below the 
excavation line. 

The proposed location across the Sarapiqui 
hills follows the location made by the Canal 
Company. Fourteen holes were put down by 
the Canal Company on the line across these hills. 
The work was done, however, with an earth 
auger and does not in any case penetrate the 
rock. Rock is in places reported, but there is 
no indication that it was not a boulder, and it is 
probable that the surface of the hard rock was 
nowhere reached. The information afforded by 
these borings has been utilized in drawing the 



180 



NICARAGUA CANAL COMMISSION 



sections, but they are at best very unsatisfactory, 
and an inference from the conditions found else- 
where is in general considered more reliable. 
The hills are composed entirely of basalt as de- 
termined by numerous residual boulders. 
Where the point of the hills is cut by the river 
opposite the mouth of the Sarapiqui, the boulders 
are very abundant and some of the outcrops may 
represent bedrock in place. Considerable hard 
rock will be encountered in this cut, and the pro- 
portion of hard rock may possibly be somewhat 
larger than is represented in the section, 
although the latter is considered a liberal esti- 
mate. * Unless the alternate line B located across 
the Tamborcito hills is selected, this is the first 
point upon the low-level line where any con- 
siderable volume of rock would be excavated 
suitable for constructing dams or for making 
concrete. As elsewhere in regions underlain by 
basalt, residual boulders will be found in increas- 
ing abundance from the surface downward to 
hard rock. 

After leaving the Sarapiqui hills the line re- 
mains in the San Jiian flood-plain where the ex- 
cavation will be entirely in silt until the hills 
north of Buena Vista are reached, where a lock 
is located. A number of borings were made by 
the Canal Company in this region, but they give, 
as elsewhere, only a minimum measure of the 
residual clay and afford no information con- 
cerning the maximum depth of either clay or 
soft rock. The rock of the region is entirely 
basalt, and the classification of materials given 
on the section is derived chiefiy by inference 
from other regions where conditions are similar. 
It is probable that no hard rock will be en- 
countered either in the canal excavation or in 
excavation for the lock foundations. The latter, 
however, will be upon soft rock which will 
doubtless be sufficientlj^ solid for the purpose. 



After leaving the site of lock No. 3 the line 
crosses a few low hills in which residual clay only 
will be encountered, and then passes to the allu- 
vial plain of the Rio Xegro. Here the excavation 
w^ill be chiefly in silt, with some residual clay, 
and possibly also soft rock where the spurs from 
the adjoining hills project into the valley. In 
the lower portion of the valley of the Rio Xegro 
the excavation will be chiefly in residual clay 
with possibly a small amount of soft rock. 
Across the flood-plain of the San Juanillo the 
material will be silt until the hill is reached 
which forms the divide between the San Juanillo 
and the Misterioso. From this point to the next 
lock site the excavation will be partly in resi- 
dual clay, but probably no hard rock will be 
encountered. This lock (No. 2) has not been 
actually located on the ground and the topog- 
raphy from which the profile was taken is 
largely hypothetical. The classification of the 
materials partakes of the same uncertainty as 
the topography. No boring has been done 
nearer this locality than at a point five miles dis- 
tant, and the character of the rock is not accu- 
rately known. It is presumed, however, to be 
basalt such as is exposed at various points along 
the San Juanillo and in the hills about Lake 
Silico a few miles to the south. The geological 
conditions represented on the section at the site 
of lock No. 2 are taken by inference from those 
observed under similar conditions elsewhere. 
The residual clay is represented with a maxi- 
mum depth of thirty feet at the top of the ridge 
and the soft rock with a depth of thirty-five 
feet. The hard rock is represented as reaching 
above the center of the lock excavation, so that 
if the conditions are as represented the lock will 
rest upon a foimdation of solid rock throughout 
its entire extent. It must be clearly understood, 
however, that the section represents only a fair 



APPENDIX II.— GEOLOGIC REPORT 



181 



degree of probability and that conditions may- 
be found entirely different from those which 
have been assumed. 

Bevond these hills the line enters the alluvial 
plain through which the Misterioso meanders, 
passing a succession of lagoons and deep swamps. 
The surface material here will be very soft mud 
which is replaced at moderate depths by rather 
compact sandy clay silt. The last lock (No. 1) 
is located on a low hill which rises above the allu- 
vial plain of the Misterioso. The information 
available with regard to the topography and 
geolog\' of this site is similar to that of lock No. 
2. The topography is only approximate, and no 
examination has been made of the geology by 
boring or otherwise. The conditions represented 
on the section, therefore, must be taken with 
considerable allowance. It is quite possible that 
both the residual clay and the soft rock will be 
found much deeper than represented, so that no 
hard rock may be found at the depth to which 
excavation for the lock foundations will go. 

The second variant of the Lull route passes 
through Lake Silico while the third passes to the 
south of the lake. The statements made in the 
above paragraph concerning the geology of Va- 
riant I to the north of the Silico hills and east 
of the San Juanillo apply equally well to the 
Variants II and III except that they should be 
supplemented with regard to one point. This 
is the region immediately adjacent to Lake Silico. 
Although no boring was done in this vicinity 
opportunity was afforded for examining the geo- 
logical conditions by the cuts on the railroad now 
in process of construction. The same deep rock 
weathering observed at other points was found 
here, and the conditions are essentially the same 
as elsewhere except that at one point beds of 
clay and sand with fragments of plants were 
found apparently underlying a lava flow. These 



beds are somewhat distinctly stratified and ap- 
pear to have been deposited in quiet water, pos- 
sibly a lake basin. They are entirely uncon- 
solidated and so far as could be observed were 
not materially affected by the lava flow which 
has covered them. In the railroad cut the clay 
beds show a decided tendency to slip. If these 
beds continue to the southeastward near the 
level at which they are exposed at the edge of 
the lake, their upper surface will be considerably 
above the bottom of the canal. If they are 
found in this position it is probable that they 
will occasion considerable trouble in excavating 
and maintaining the canal. They will tend to 
slip out from beneath the lava and by sapping 
it permit the overlying rock to fall down. 

The proflle indicates that a lock is planned at 
this point If the beds of clay have any con- 
siderable thickness, as is altogether probable, 
they would afford an insecure foundation for a 
lock. On the profile these beds have not been 
represented on account of the lack of exact in- 
formation concerning them, but conditions have 
been represented as they would probably be 
found if the lava forming the surface continued 
indefinitely downward. The presence of the 
beds, however, and the probability that they ex- 
tend some distance to the southwestward should 
be taken into account in deciding upon the rela- 
tive merits of alternative routes in this region. 

Practically the same geological conditions 
will be met on the Variants I, II and III, across 
the alluvial delta plain between the last residual 
hills and the coast. As already stated the inner 
portion of this delta plain is covered* by a layer 
of fine clay silt or swamp mud overlying sand or 
sandy clay. The layer of mud thins out toward 
the coast, and the outer margin of the delta plain 
is composed entirely of sand. The lagoons 
which are crossed by these lines in the delta 



182 



NICARAGUA CANAL COMMISSION 



plain have already been described. They con- 
tain occasional small bodies of open water, but 
are generally in a somewhat advanced stage in 
the process of silting up and where the larger 
trees have not yet secured a footing are occupied 
by coarse grass and Silico palms. Low slopes 
will be required through the more open of these 
lagoons, and all the alluvium excavated will 
probably be sufficiently firm to stand in banks 
with steep slopes when it has an opportunity to 
become thoroughly drained. With the con- 
struction of the canal the water surface in the 
lagoons will be materially and permanently low- 
ered so that much of the surface now covered 
with water will be comparatively dry and firm. 
The extent of this drainage will of course be in 
proportion to the porosity of the silt which in 
turn depends on the proportion of sand which it 
contains. The change which will follow the ex- 
cavation may be seen in the vicinity of the short 
section of canal dredged by the Canal Company. 
The land at some distance on either side of the 
ditch is perceptibly firmer than elsewhere in the 
same region. 

The behavior of the sand which forms the 
outer margin of the delta plain when deposited 
in banks alongside an excavation is seen where 
dredging has been done at Greytown. The 
sand is so porous that water falling upon it is at 
once absorbed and consequently does not gully 
the steepest slopes. 

ADDITIONAL GEOLOGIC WORK RE- 
QUIEED FOR FINAL LOCATION. 

The geological work done under the direction 
of the U. S. Nicaragua Canal Commission is 
sufficient for the preliminary location and pre- 
liminary estimates of cost. Before the final lo- 
cation can be made considerable additional in- 



formation should be secured. This required 
information will be obtained chiefly by means 
of drills, although some additional general geo- 
logical work might well be carried on with 
advantage. This is generally true of the work 
which it has been proposed to do at greater or 
less distance from the line of the canal for the 
purpose of obtaining information which will be 
of use for the selection of the best materials to 
be used in construction and for protecting the 
works when completed. 

The work with earth auger and diamond drill 
may be divided into two general classes; first, 
that needed for the classification of materials on 
excavation lines, and, second, that needed for 
the determination of the character of founda- 
tions for structures such as locks, dams and 
weirs. Less of the former class of work will 
be required than of the latter. 

On Excavation Lines. — More or less work 
should be done at the following named locali- 
ties: At Brito, while it is probable that if the 
harbor be located toward the south side of the 
Rio Grande valley no rock will be encountered, 
still there is no certainty of this, and a sufficient 
number of test borings should be made to deter- 
mine this point definitely. If these borings are 
carried to a considerable depth below the pro- 
posed bottom of the harbor the number required 
\vill be fewer than if thev are carried down 
barely to the depth of the proposed excavation. 

Borings should be continued along the line of 
the canal on the west side at intervals not 
greater than a thousand feet, and wherever the 
line approaches the edge of the valley they 
should be put down at intervals of three to five 
hundred feet. This work should be continued 
entirely to the lake for the purpose of making 
an accurate classification of the material to de- 
termine the methods of excavation, and the slope 



APPENDIX II.— GEOLOGIC REPORT 



183 



at which the material will stand and hence the 
amount of excavation, these two elements chiefly 
determining the cost. 

Coming to the east side of the lake additional 
work should be done on the river from the lake 
to the point where the canal leaves the river 
channel. Between the lake and the Toro rapids 
a series of transverse sections should be deter- 
mined by means of the drill in order to deter- 
mine more definitely the slope of the rock sur- 
face which the work already done has discov- 
ered. This will be necessary before the most 
advantageous location of the canal line can be 
made. Special attention should be paid to the 
Toro rapids and sufficient work done at this 
point to locate the old river channel through this 
obstruction if such a channel exists. Between 
the Toro rapids and the Boca San Carlos little 
work will be required except on proposed cut- 
offs. The extent of the work will be deter- 
mined somewhat by the plan which is adopted 
and the consequent grade of the canal between 
Machuca and the San Carlos. 

Assuming that the low-level line is decided 
upon, which leaves the river channel at the Boca 
San Carlos, boring should be done at a number 
of localities between this point and Greytown. 
The greater part of the work would naturally 
be where the excavation was heaviest; that is, 
where the line crosses the points of hills which 
extend down to the San Juan river. The object 
of this work would be, as on the west side, to 
determine the character of the materials, and 
hence the methods which can be employed in 
excavation, and the slopes of the excavation. A 
further purpose which would be served by care- 
ful and systematic boring on these points would 
be to determine the availability of the material 
which will be excavated for structural purposes 
on other parts of the line. If the rock is not of 



such a character as to form suitable material for 
concrete and rip-rap it will be necessary to search 
for such material elsewhere. Systematic boring 
should be done wherever the canal line crosses 
alluvial plains at such an elevation that a con- 
siderable embankment will be required, in order 
to determine • the character of the silt and 
whether or not it will form a water-tight em- 
bankment without a clay core. 

On Foundations. — No work has been done on 
the west side except at La Flor, with the distinct 
object of determining the character of founda- 
tions for locks and dams. If a low-level route 
is adopted on the west side systematic examina- 
tion should be made of the character of the foun- 
dations at the various points where locks will be 
located. The information at hand concerning 
this region is ample for preliminary location and 
plans, but considerable additional information 
should be obtained before the final plans are 
adopted. The drilling operations will prob- 
ably show that in some cases the location of the 
lock sites can be shifted with advantage, since it 
is not probable that the site selected purely on 
account of topographic considerations will in 
every case afford the best foundation. The 
point selected for a dam and controlling works 
in the upper portion of the Rio Grande valley 
should be systematically examined, and the sec- 
tions which have been based chiefly upon sur- 
face examinations should be carefully verified 
by drilling. 

Sufficient work has been done on the various 
possible dam sites on the San Juan river to af- 
ford a basis for preliminary location and to de- 
termine the relative merits of the various 
schemes which involve construction of dams at 
one or more of these localities. When the plan 
which appears most favorable has been selected, 
the dam sites which it involves should be exam- 



184 



NICARAGUA CANAL COMMISSION 



ined with ^ great thoroughness before the final 
plans are adopted. Even at the Ochoa site 
where the most thorough work has been done, 
considerable additional work would be required. 
Most of the boring done was confined to a single 
line, approximately the center line of the dam, 
but it is evident that the entire arej which would 
be covered by the foundation of the dam should 
be thoroughly examined. At the other sites this 
additional work is even more important. No 
boring has been done on the east side at any 
locality which will probably be finally selected 



for the lock sites. The sections which have 
been submitted showing the geological condi- 
tions at the various suggested lock sites are 
chiefly derived by inference from other locali- 
ties where examination has been made. While 
this inference is perhaps sufficient for prelimi- 
nary location, its weakness has been pointed out 
in the foregoing report, and no final location or 
final plans should be made imtil a thorough ex- 
amination has been made by means of the drill 
of the exact conditions below the surface. 



PART III 

MICROSCOPIC PETROGRAPHY OF THE ROCKS 
FROM THE NICARAGUA CANAL REGION 

By F. LESLIE RANSOME 

y4sst. Geologist, U. S. Geological Survey 



The following notes make no pretense of be- 
ing exhaustive. They merely record observations 
made on the hand-specimens and their sections, 
unconfirmed by chemical examination. The 
feldspars have been determined by the methods, 
of Michel Levy, Fouque, and Becke. It is evi- 
dent that some of the volcanic rocks described 
are close to the line between augite-andesites and 
olivine-free plagioclase basalts. In such cases 
chemical examination might result in placing 
with the basalts one or more of the andesites of 
the following table, or vice versa. Although 
in many cases collected from residual boulders 
in clay, the massive volcanic rocks are usually 
strikingly fresh, showing that the active trans- 



formation, from rock to soil or clay, is often 
confined to a very narrow zone. The passage 
from clay to fresh rock would seem to be re- 
markably sharp as compared with the weather- 
ing which takes place in temperate regions. 

In their general character, the volcanic rocks 
resemble those described by Hague and Iddings * 
from San Salvador. The rocks of both regions 
range from acid to basic varieties. The basalts 
and andesites are frequently hypersthene-bear- 
ing, and dacites occur which possess both ande- 
sitic and rhyolitic features. 

March 18, 1899. 

1 Notes on the Tolcanic rocks of the Republic of Salva- 
dor. Am. Jour. Sci., Vol. XXXII, 1886, pp. 26-30. 



APPENDIX II.— GEOLOGIC REPORT 



185 



Number ; 

of 
Specimen. 



Name. 



7-a ! Hypersthene- 
basalt. 



14 ' Olivine-basalt. 



15-a 



Hypersthene- 
basalt. 



33-a 



Basalt 
(glassy). 



35 



Olivine-basalt. 



Locality. 



Description. 



San Carlos embankment 
Line, 2J miles S. of 
Upper Oehoa dam site. 
Kesidnal boulders in 
red clav. 



Upper Ochoa dam site, 
200 feet below center 
line, S. bank of Kio 
San Juan. Kesidnal 
boulder in clay forming 
bluff above hole No. 7 ; 
15 to 25 feet above 
river. 



Upper Ochoa, bank of , 
Caflo Benito; 500 ft. 
S. of Kio San Juan ; ' 
residual boulder in red i 
clay. 



Southern point of Tam- 
borcito hills. Exposed 
at low water on N. 
bank of Rio San Juan. 
Coarse volcanic brec- 



cia. 



Buena Vista; 3 miles 
below Boca Sarapiqni 
cleared hill on N. bank 
of Rio San Juan. Re- 
sidual boulder in red 
clay. 



Megascopically : Dark, nearly aphanitic, of 
basaltic aspect. Weathers superficially to 
a yellow ocherous crust. 

Microscopically: Porphyritic structure, with 
nearly holocrystalline fluidal groundmass. 
Essential constituents are basic plagioclase 
(labradorite or anorthite) >• hyperstnene >• 
aiigite ^ olivine, and a little glass. Acces- 
sory iron ore and apatite. Olivine serpenti- 
nized. 

Megascopically : Dark grey and fine-grained, 
with small phenocrysts of olivine. W eathers 
light grey and then ocher yellow. 

Microscopically : Porphyritic ; phenocrysts of 
olivine in nearly holocrystalline intersertal 
groundmass. Essential constituents are 
Basic plagioclase (labradorite or anorthite) >• 
pale greenish augite ]> olivine >• glass. Ac- 
cessory iron ore, apatite, and minute prisms 
of an undetermined brown mineral. 

Megascopically : Dark, heavy, even-textured 
rock of doleritic aspect. Weathers to an 
ocherous crust. 

Microscopically : Nearly holocrystalline doler- 
itic structure. Basic labradorite ]> augite X 
hypersthene]> glass. Accessory apatite and 
iron ore. Secondary serpentine, probably 
from alteration of olivine phenocrysts. 

Megascopically : Dark and basaltic, with small 
phenocrysts of feldspar, and green specks of 
chlorite. 

Microscopically : Porphyritic structure. Small 
phenocrysts of basic labradorite or anorth- 
ite ]> augite ^ iron ore, in a fine groundmass 
of plagioclase microlites, iron ore and glass. 
Amygdules of chlorite, and opal (?). 

Megascopically: Ordinary olivinitic basalt. 

Microscopically : Porphyritic with holocrystal- 
line groundmass. Phenocrysts of basic lab- 
radorite or anorthite ^ olivine ^ augite. 
Groundmass : Augite ]>^ iron ore ]> pla- 
gioclase. Groundmass is unusually rich in 
augite. Olivine partly resorbed and usually 
serpen tinized. 



186 



NICARAGUA CANAL COMMISSION 



Number 

of 
Specimen. 



38 



44 



50 



81 



82 



84 



Name. 



Olivine-basalt. 



Hypersthene- 
baealt. 



46 i Olivine-basalt. 



Hyperethene- 
andesite. 



Locality. 



Machado ; 1 mile N. SO*' 
W. from Upper Ochoa 
dam site. Boulder in 
small brook, nearly in 
place. 

San Carlos hills, about 1 
mile N. AV. of Boca 
San Carlos, 1000 ft. A. 
T.; top of bench on a 
narrow spur. Residual 
boulder in red clay. 



Castillo ; steep rounded 
hill on S. bank of Rio 
San Juan. Rock ledge 
in place. 



Granada ; from quarry 
W. of town ; used as a 
building stone. 



Hypersthene- 
andesito 
pumice. 

Hypersthene- 
andesite. 



Olivine-basalt 

(glassy). 



Volcano Ometepe; near 
top of cone on west side. 
Loose block in ash. 

Volcano Ometepe ; large 
blocks of lava in loose 
ash at highest point of 
crater rim. 



Volcano Ometepe; lava 
flow on west side near 
base. 



Description. 



Megascopically : Dark grey, nearly aphanitic. 

Microscopically: Porphyritic structure. Phen- 
ocrysts of olivine ^]> biotite. Groundmass 
of augite >• plagioclase X glass >• iron ore. 
Biotite is in ragged plates. 

Megascopically: Grey, even-grained, and ap- 
parently holocrystalline. 

Microscopically : Holocrystalline porphyritic 
structure; phenocrysts grade into ground- 
mass. Essential constituents: basic labra- 
dorite^ augite X hypersthene. Accessory 
iron ore, biotite and apatite. 

Megascopically : Minute phenocrysts of feld- 
spar in an aphanitic, dark grey oase. 

Microscopically : Porphyritic structure with 
fine, rather glassy groundmass. Olivine 
altered to iddingsite pseudomorphs. 

Megascopically : Light grey and of porous 
texture. 

Microscopically : Porphyritic, with hyalopilitic 
groundmass. Essential constituents labra- 
dorite>'augiteXhypersthene]> brown horn- 
blende, and abundant glass. Accessory iron 
ore, apatite and tridymite. 

Megascopically : A dark grey, vesicular glass. 
Microscopically : Phenocrysts of labradorite 
and hypersthene in a microlitic glass. 

Megascopically : Nearly black pitchstone, 
showing small phenocrysts of feldspar. Is 
somewhat pumiceous. 

Microscopically : Hyalopilitic structure. Es- 
sential constituents are labradorite^ hypers- 
thene >• augite (in groundmass), with abun- 
dant brown glass. A beautifully fresh rock. 

Megascopically : Dark grey vesicular, glassy 

rock of andesitic aspect. 
Microscopically : Vesicular and porphyritic 

structure. Phenocrysts of basic labradorite 

»olivine]> augite, in a turbid microlitic 
. glass. There is perhaps a little hypersthene 

present. 



APPENDIX II.— GEOLOGIC REPORT 



187 



Number 

of 

Spocimcn. 



88 



91 



109 



115 



120 



123 



Nanio. 



Diorite (?) 
(altered). 



Quartz-diorite 
(altered). 



Hyperethene- 
andesite. 



HyperBthene- 
audesite. 



Hyperstliene- 
I andesite 
(\'itrophyre). 



l/ocality. 



Description. 



Hyperstliene- 
basalt 
(vitropliyric). 



Machiica dam site; Cam- 
pafla island ; i mile 
below Maehiica. Large 
boulders at head of 
island from dike; nearly 
in place. 

Maehuca dam site ; center 
line 200 ft. S. of Rio 
San Juan. Residual 
boulder in red clay. 



Lake Apoya ; inner slope 
of caldera basin ; lava 
flow associated with 
ash-beds. 



Ravine IJ miles S. W. of 
La Flor dam site ; dike 
in Brito sandstone. 



Rio Grande valley; north 
side; on Childs route 
variant II, Sta. 503, 
near hole No. 4. Rock 
ledge in place. 



Escalante river; about 
50 miles N. W. of 
Brito on the Pacific 
coast. Residual boul- 
der in black clay soil. 



Megascopically : Fine-grained, holocrystalline 
grey rock, with slight porphyritic develop- 
ment of hornblende. / 

Microscopically : An altered holocrystalline 
granular rock — probably once a diorite. 
Epidote is very abundant. 

Megascopically : A rather fine-grained gran- 
ular rock of dioritic aspect, with abundant 
specks of pyrite. 

Microscopically: An altered quartz diorite, 
full of secondary minerals. It may have 
been an augite-diorite originally, as horn- 
blende is green and fibrous. 

Megascopically: Light grey and porous, with 
small phenocrysts of plagioclase and horn- 
blende. ' 

Microscopically : Por])hyritic structure with 
hyalopilitic groundmass. Phenocrysts of 
labraaorite]> hypersthene> greenish aug- 
ite]> hornblende. Groundmass of feldspar 
laths, augite, iron ore, and much glass. 

Megascopically : Compact dark grey, with 

numerous small phenocrysts of plagioclase. 

Microscopically : Porphyritic structure with 

f>ilotaxitic groundmass. Phenocrysts of 
abradorite (Abg An4) > augite ]> hypers- 
thene. Augite and hypersthene frequently 
intergrown. Groundmass consists of same 
minerals as phenocrysts, with usual access- 
ories and perhaps a little glass. 

Megascopically : Abundant small phenocrysts 
of plagioclase in nearly black glassy base. 

Microscopically : Porphyritic structure. 
Essential constituents are phenocrysts of 
labradorite (Ab, An4)> hypersthene >• au- 
gite, in an abundant microlitic brown glass. 
A fresh and beautiful rock. 

Megascopically : Like above, but apparently a 
little more weathered. 

Microscopically: Structure vitropliyric. 

Essential constituents are labradorite (near 
Abs A n4)]> hypersthene ]> pale green augite 
>iron ore, with much microlitic brown 
glass. Plagioclase shows beautiful skeletal 
and spherulitic growths. The rock may be 
a basic facies of a hypersthene andesite, but 
is rather rich in dark minerals. 



188 



NICARAGUA CANAL COMMISSION 



Number 

of 
Specimen. 



Name. 



129 Olivine-baBalt. 



133 I Basaljb 

I (olivine-free). 



135 Aplitic dike- 
rock. 



150 -a 



Hypersthene- 
baealt. 



159 



163-c 



Olivine-basalt. 



01 i vine-basalt. 



Ix)cality. 



Palo de Arco; on point 
of low hill, south bank 
of Rio San Juan. Re- 
sidual boulder in red 
clay. 



Castillo; hill on north 
bank of Rio San Juan ; 
jointed ledge in place. 



Pilares rapids ; rock ledge 
in place; exposed at 
low water in channel 
of Rio San Juan; dike 
in Machuca sandstone. 



San Carlos embankment; 
near Cafio Cnreno, li 
miles from lower Ochoa 
dam site, 150 miles N. 
E. of No. 7. Rock ledge 
in place. 

San Francisco hills ; N. 
bank of Rio San Juan, 
opposite San Francisco 
island. Residual boul- 
ders in red clay. 



ElTigre: N. bank of Rio 
San Juan, li miles 
above Boca San Carlos. 
Residual boulder. 



Description. 



Megascopically : Nearly black, with pheno- 
crysts of plagioclase and olivine in a com- 
pact base. 

Microscopically : Porphyritic structure, with 
phenocrysts distinct from groundmass. 
thenocrysts of anorthite^olivine^augite. 
Groundmass a fine intersertal aggregate of 
augite X plagioclase ^ iron ore X glass. 
Olivine is partly serpentinized. 

Megascopically : Irregularly banded or mot- 
tled, aphanitic rock, of somewhat purplish 
tint. Shows a few minute phenocrysts of 
feldspar. 

Microscopically: Porphyritic structure. Small 
phenocrysts of anorthite and pale augite, in 
a fine groundmass of plagioclase, augite, iron 
ore and glass. 

Megascopically : A light grey porphyry with 
small phenocrysts of feldspar. 

Microscopically : Porphyritic, with pheno- 
crysts of oligoclase and orthoclase (?), in a 
fine granular groundmass of alkali feldspar 
and quartz. A little iron ore and a few 
biotite scales largely changed to chlorite. 
Feldspathic phenocrysts are partly changed 
to calcite. Rock is somewhat obscure. 
Might be termed an aplite-porphyry. 

Megascopically : Dark grey and nearly aphan- 
itic. Weathers to an ocherous yellow crust. 

Microscopically : Essential constituents are 
labradorite ]> augite ]> hypersthene ]> glass. 
Usual accessories. Hypersthene partly ser- 
pentinized. Some serpentine may have been 
derived from olivine. 

Megascopically: Dark grey, and of ordinary 

basaltic character. 
Microscopically : Ordinary olivine-basalt, with 

olivine largely serpentinized. 



Megascopically : Dark grey, with small pheno- 
crysts in an aphanitic base. 

Microscopically : Typical olivine-basalt of near- 
ly holocrystalline doloritic habit. 



APPENDIX II.— GEOLOGIC REPORT 



189 



Numlier 

of 
Specimen. 



lt)7 



Name. 



Hypersthene- 
basalt. 



Locality. 



Description. 



Tamborcito hills; near Rio i Megascopically : Numerous small pheiiocrysts 



San Juan; at various 
points on crest and 
sides. Residual boul- 
ders in red clay. 



169 



Basalt 
(olivine-free). 



Sarapiqui hills; top of \ 
cleared hill, 500 ft. from i 
Rio San Juan, opposite i 
mouth of the Sarapiqui. 



173 



Basalt ' Punta Petaca; N. bank | 

(olivine-free). | of Rio San Juan ; low ! 

i cleared hill. Residual , 
boulders in red clay. 



180 



Basalt (prob- 
ably olivine- 
basalt). 



Cafio Deseado; i mile 
above Camp Menocal. 
Residual boulder in red 
clay. 



182 



Hypersthene- 
basalt. 



Cafio Deseado ; Camp 
Warner Miller. Re- 
sidual boulder in red 
clay. 



185 



Enstatite- 

andesite. 



Falls of Luisa ; Cafio Des- 
eado; heavy rock ledge 
in place. 



of plagioclase and pyroxene in a compact, 
nearly black groundmass. 
Microscopically : Porphyritic structure. Pheno- 
crysts of basic labrodorite or anorthite]> 
hypersthene, in a fine groundmass of augite, 
plagioclase and iron ore, with abundant 
light brown glass. 

Megascopically: Numerous small phenocrysts 
of plagioclase in a compact dark base. 
Weathers to an ocherous yellow crust. 

Microscopical : Porphyritic structure. Pheno- 
crysts of anorthite in a groundmass of pla- 
gioclase, augite, iron ore and glass. 

Megascopically: Like 169, but more crystal- 
line. 

Microscopically : Almost holocrystalline doler- 
itic structure. Essential constituents are 
plagioclase (near by townite) > augite >• iron 
ore ]> glass. Accessory apatite. 

Megascopically: Dark and basaltic looking, 
with abundant small lath-shaped phenocrysts 
of plagioclase. Weathers to an ocherous 
crust. 

Microscopically: Porphyritic structure. Pheno- 
crysts of anorthite ]> olivine (serpentinized), 
in a groundmass of plagioclase, augite, iron 
ore, and glass. 

Megascopically : Apparently a doleritic basalt. 

Microscopically : Porphyritic structure. Phe- 
nocrysts of basic labradorite or anorthite^ 
augite ]> hypersthene, in a groundmass of 

flagioclase^ augite ]> iron ore, and glass. 
8 apparently near the andesites. 

Megascopically : Dark grey, with small pheno- 
crysts of plagioclase augite in a compact 
groundmass. 

Microscopically : Porphyritic structure. Phe- 
nocrysts of basic labradorite ^ augite ]> a 
rhombic pyroxene (enstatite ?), mostly alter- 
ed to serpentine. Groundmass is hyalopi- 
litic, consisting of plagioclase, augite, rhom- 
bic pyroxene and glass, with iron ore and 
apatite. 



190 



NICARAGUA CANAL COMMISSION 



Number 

of 
Specimen. , 



Name. 



Ix)cality. 



Description. 



194 I Olivino-basalt. i Silico lake; cut on C. & ■ Megascopically : Dark and compact, with small 



195 



P. T. Co. Ry., i mile 
east of the lake. Re- 
sidual boulders in clay. 



Olivine-basalt. Silico lake; cut on C. & 

P. T. Co. Ry., i mile 
east of lake. Residual 
I boulders in clay ; intru- 
' sive dikes in 194. 



202 



Augite- 

andesite(?). 



203 



Basaltic or an- 
desitic tuff. 



205 Dacite. 



206 Dacite. 



Menocal Route; Eastern 
Divide, core from hole 
No. 1, 137 feet below 
surface. 



Menocal Route; Eastern 
Divide, core from hole 
No. 1, 173 feet below 
surface. 

Menocal Route; Eastern 
Divide, core from hole 
No. 2, 16 feet below 
surface. 



. Menocal Route, Eastern 
Divide; core from hole 

' No. 2, 100 feet below 
surface. 



phenocrysts of plagioclase and olivine. 
Microscopically : Ordinary olivine basalt with 
olivine partly changed to iddingsite. 

Megascopically : Rather light grey, locally 
vesicular. Small phenocrysts of plagioclase 
and olivine in a dense grey groundmass. 

Microscopically : Like 194. 



Megascopically: Light grey and glassy, with 
a few minute dark phenocrysts. 

Microscopically : Structure porphyritic with 
hyalopilitic groundmass. Small phenocrysts 
of plagioclase and pseudomorphs of calcite 
(after pyroxene?) in a groundmass of feld- 
spar microlites, glass and iron ore. Rock is 
amygdaloidal and decomposed. 

Megascopically : Apparently a dark grey, de- 
composed, basic tuff. 

Microscopically: Turbid and glassy. Prob- 
ably a basaltic tuff, but may be andesitic. 

Megascopically : A light grey porphyry show- 
ing phenocrysts of feldspar and quartz in a 
grey glassy base. 

Microscopically : Porphyritic structure. Phe- 
nocrysts of quartz and andesine in a glassy, 
partly devitrified groundmass resembling the 
groundmass of many glassy rhyolites. The 
character of the groundmass and the absence 
of dark constituents give a decided rhyolitie 
aspect to the rock as seen in thin section. It 
is placed provisionally with the dacites on 
account of its relatively basic plagioclase 
and absence of sanidine. 

Megascopically: Like 205, but contains small 

inclusions of some darker rock. 
Microscopically: Very similar to 205, but 

contains included fragments of pyroxene 

andesite. 



209 Andesite-tuff(?) Menocal Route, Eastern 

' Divide, core from hole 
No. 2, 195 feet below 
surface. 



Megascopically : Fragile, grey-green material, 
apparently a glassy tuff. 

Microscopically : A fine grained augitic pla- 
gioclase tuff — probably andesitic. 



APPENDIX II.— GEOLOGIC REPORT 



191 



Numl>or 

of 
Specimen. 



Name. 



212 Limestone. 



216 Basalt or 

augite-andesite. 



217 Dacite. 



219 Olivine-basalt. 



220 Andesite-tuft'. 



223 Dacite. 



22t> Qlivine-basalt. 



Locality. 



San P^rancisco embank- 
ment; between San 
Francisco and Surprise; 
core from hole B5, 108 
feet below surface. 

Lower Ochoa dam site, 
center lino, N. bank of 
liio San Juan ; core 
from hole No. 2, 180 
feet below surface. 

Lower Ochoa dam site; 
core from hole No. 3; 
center line S. bank of 
Rio San Juan ; 33 feet 
below surface. 



Upper Ochoa dam site; 
core from hole No. 10, 
107 feet below surface ; 
top of hill at N. end of 
dam. 



D<»8crIption. 



Megascopically : Light yellow and plainly 
clastic. 

Microscopically: A very fine-grained lime- 
stone, containing a few specks of iron ore. 

Megascopically: Like 33. A decomposed 

chloritized rock. 
Microscopically: Much decomposed. May 

have been a basalt or augite andesite. 

Megascopically : Dark grey with small pheno- 
crysts of plagioclase and quartz in a compact 
base. 

Microscopically : Phenocrysts of labradorite 
(Ab, Aui) and andesine, quartz, and chlori- 
tized biotite, in a fine groundmass of plagio- 
clase microlites embedded in a feldspathio 
base which extinguishes simultaneously 
over considerable areas of the thin section 
giving a mottled or micropoikilitic eflfect 
with crossed nicols. The rock is not fresh 
and may have contained some augite. Iron 
ore and apatite are present as accessories. 

Megascopically: Ordinary appearance of a 

fine-grained olivine-basalt. 
Microscopically: Ordinary olivine-basalt, but 

contains some small brown prisms like 

those noted in No. 14. 



Upper Ochoa dam site; Megascopically: Somewhat decomposed grey 
top of hill at N. end of tuif. 

dam ; core from hole Microscopically : Apparently a fine andesitic 
No. 10, 157 feet below . tuff, 
surface. 

Upper Ochoa dam site; j Megascopically: Light grey, of rhyolitic 
center line, N. bank of aspect, carrying small dark inclusions. 
Rio San Juan ; core I Microscopically : Porphyritic structure. Phe- 
from hole D3, 56 feet' nocrysts of quartz]> plagioclase (near ande- 
below surface. ' sine) >]> green hornblende, in an abun- 

dant microlitic and partly devitrified 
streaky glass. Probably an acid dacite. 



Upper Ochoa dam site; 
top of hill S. end of 
dam ; con* from hole No. 
J>, S4 feet below surface. 



Meojascopically : (irey, nearly aphanitic, with 

an occasional small vesicle. 
Microscopically: An ordinary olivine-basalt, 

rich in olivine. 



192 



NICARAGUA CANAL COMMISSION 



Number i 

of I 

8p<Bcimen.| 



Name. 



230 



Andesitic tuif. 



235 



Basalt. 



242 



Basalt-amyg- 
daloid. 



249 



Augite- 

andesite. 



255 



Pyroxene- 

andesite. 



Locality. 



Core from hole No. 180 ; 
in channel of Rio San 
Juan, 1 mile below 
Machnca. 



Castillo; core from hole 
No. 160, head of Cas- 
tillo rapids ; S. side of 
Rio San Juan ; 8 feet 
below bed of river. 



Toro rapids; core from 
hole No. 143 ; S. side of 
channel of Rio San 
Juan ; opposite mouth 
of Rio Savalos 10 feet 
below bed of river. 

Melchorita ; core from 
hole No. 41 ; in the 
channel of the Rio San 
Juan ; 2 feet below bed 
of river. 



Rio Grande valley ; core 
from hole No. 3 ; Childs 
Route Variant II, sta- 
tion 495 ; 35 feet below 
surface. 



Description. 



Megascopically : Apparently a rather fine 

grey tuff. 
Microscopically : An andesitic tuff containing 

fragments of limestone. The limestone 

shows organic remains. 

Megascopically : Dark grey and aphanitic. 
Microscopically : Minute phenocrysts of pla- 
gioclase in a fine groundmass made up of 

J)lagioclase microlites, some serpentinized 
erromagnesian mineral, iron ore, and glass. 
The rock may possibly belong with the 
augite andesites. 

Megascopically : Weathered brick-red amyg- 
daloid. 

Microscopically: Probably an amygdaloidal 
glassy basalt, but original character is ob- 
scured by oxidation. 



Megascopically : Dark grey with small pheno- 
crysts of plagioclase and augite. 

Microscopically : Porphyritic structure. Phe- 
nocrysts of labradorite (Abg An^) ]> pale 
greenish augite, in a^groundmass of plagio- 
clase, augite, iron ore and glass. 

Megascopically : Nearly black, with small 
phenocrysts of plagioclase and augite in a 
compact groundmass. 

Microscopically : Porphyritic structure. Phe- 
nocrysts of labradorite ]> augite ]> rhombic 
pyroxene (bronzite, or iron -poor hypers- 
thene), in a microlitic, brown glassy base. 



NICARAGUA CANAL COMMISSION 



APPENDIX a. PLATE VIII 



Sections derived Trom borings aTthe 

EASTERN DIVIDE 

showing classiricaTion and character 
of matferisls. depths ofrocK decay, eTc 

EASTEBN DIVIDE EASTERN DIVIDE EASTERN DIVIDE EASTERN DIVIDE 

M° I hi°S NO 3 N°-4- 



Sta 1079 -lO 



1 



H 




STa. lO^O-rS 



*" 



i 







DRILL SECTIONS-EASTERN DIVIDE. 



NICARAGUA CANAL COMMISSION 



APPENDIX 2, PLATE XII 



Sec^OKis derived from boringa aTthe 

UPPER OCHOA DAMSITE. ■ 

showing classification and charaCTer 

of materia/s, depHos dfrocK decoy, etc 

UPPER OCHOA UPPER OCMOA UPPER OCHOA UPPER OCHOA 

NO 3 NO 4 N° a N0 10 

iNofihbaniT.SaiiJuanniw Ssutfibanx.^anJMnTiha Sojfh end i>mBrxsilB Norftiena oP OamalTte 



8/; ; 
'it: 





DRILL SECTIONS-UPPER OCHOA. 



NICARAGUA CANAL COMMISSION 



APPENDIX 2, PLATE XIH 



Sections derived from boKingg sttfie 
BOCA SAN CARLOS DAMSITEl 

showing classification and charcicTer 
ksT mSTerio\s, depths of i-ocrt decay, eTc 
Boca san carlos Boca san carlos boca 3«n carlos boca san carlos 
N° e N°3 NO 197 NO 4 



inner margin oF Otiter margin dP 

ftoodplsin nOrtKof floodp/mn nor*iof 
nJoan R.vor- Son Juan Rivwr 






Foot of RosKJual 
aJopa norrti o^ 
SanJuoi Ri*v«(- 



5- '■:- 



Souffri end of Darwsfffe 




DRILL SECTIONS-BOCA SAN CARLOS. 



NICARAGUA CANAL COMMISSION 



APPENDIX 2. PLATE XIV 



SectiOKiQ derived froion borings aft tine 
MACHUCA DAMSITt. SANTA CRUZ AND CONCHUDA. 

showing classifTcatiCi'i and character 
oTnoaterials, deptVis dT roci< decay, estc . 

SANTA CRUZ MACHUCA MACHUCA . CONCHUDA 

NO 155 NO| No-4 NOI92 



On cut-ofT abovo. 

Santa Crux, isoa**" 
from 5an Juan River 



■ - 

. 



i 






VaHoMf aM Mown 
•lav. 



>Ud •■•» wio M iad wrth 
whita; «an«a« '••m tn« 
«aaay al itelcaAia raaks, 
VfafeaMit IK part watar- 
i«M luff an« aawBlem 
aiwta , aaniaiM antaii 
fratmanla af fhnii 
«ra4aa aawawafri iiMa 



■4«a oiay HMMiatf w«i| 
pinfe an« whiw. «a- 



''"_' tfewnwara inia 



WhMa 
4an««4 aa 



tfwu l ar aiay ; 



1 



Nor^ &rtd oF Oamsihe. 



i - • 

0':- 



'.t; 



Is 



■■»■ 



1^- 

1% 



aiay, 



' - U»a «aeay af «<••*■ 



aaniaMi«« iwah «e>- 
•ania tMff a«« »]r*«ia> 



'.-,■ 

XL ^ ^ ^ 

J[7> muah nrMa , 

h^-l ' aama ra«M«ai 



• i af hafd ivaii, 



^ - 



^^ Hairi wifta aalcai 



Sooth end dT Oamsil'e 



ST 



I 



--'-, 



Ratf etoy : atiflHiy 



a l alia aa«*i«inin9 mucii 
•ala a wic matanai 



a:! 



^^ 






J'_ 



U«M vaMaw an« 
wima saHtfy aUy; «a^ 
•<«a« fram uta aaaay 
«f santfalafia eaw t atiuin 
ivNicii vataaAia tuff an4 
nrma. 



•aft whiia iMk ; 



aa<«taini«Hi mwett 
0frA»; aataraan 4- M 
TD c- antf 4' 4# many ra« 
... ai««ai aawWais at tfr4 

•;:^ an« + I& emitfa aa 
Mfttfaf tua aiamana 
7* «nU ta chatky alay. 



r: 



On cut-off' 35o^frt3m 
San Jusn River 






Valaw antf «a4 aan^ 
alay ; tfarivaa fram 
Uia daaay of W ai c awta 
>a«ka, ptahaaiy salartaM 
Wft an4 eenfiofnarata . 
•«a<aa dawnwara tnia 



^ 






B 


.» . 










1^* 


- — 




i - 


• 




a 






« 


— i "' 










• . 


• 




9 ■-- 

r a. - 




Kwa anri afawn aantfy 




m 


aiay i aaf ivc a aa aoavai 


— 




baaamaa fmnar dawn- 



J..8afi whWa raak; 
. ^' aMy waau>a*a« taiaawia I 
% ', aa«iMia«ia ; «*aathai<a4 jl Q 
* J' tuW an« aan(la«MMia. " 



i 



DRILL SECTIONS-MACHUCA, SANTA CRUZ AND CONCHUDA. 



5H( 



APPENDIX 2 PLATE XV 




lo a 



ISO 

too 




Ca 



APPENDIX 2 PLATE XVI 



BOOO 






aooo 




i 



Sombrero ff€ 
Cu9ro 




&ID| 



ma ni».ui,>iirjn.ffrf ■. t » f u.i [ij i ,^ji j^ 



o 

*^ 

c 





istmi 



I 



pi ' » ' i* 



P^^^^^^Pp'i'^^f^^^y^^^^'^^P^^jf^^^^^^f^^'^T^^ 







- . . . . j-.i 1- ^t' 





mm 




- .j.. .^1 








•-.■s^-\ 














1 • 


^s 







APPENDIX 2 PLATE XVU 
t'-^^:|-:--^ AHuviurri, Clay iilt -and Sand,' 
] Residual Cfay. 
Brito^and Machucd. fomtations. 

VolcarviCj tuff and congtoinenste. 

Dacite. 

Baeatt ^FK^ Artdeeite. 







4(3 iE3o . SO 



I*-'' 



■■■I#«*i 



^inmm 



f h 




APPENDIX III 



REPORT 



OF 



HYDROGRAPHIC INVESTIGATIONS IN NICARAGUA 



MADE FOR THE 



NICARAGUA CANAL COMMISSION 



BY 



ARTHUR P. DAVIS 

Hydrographer 



13 



CONTENTS 



PAGE 



Stream Measurements .'197 

Rio Grande 198 

Brito Station on Rio Grande 198 

Tola Station on Rio Grande 198 

Lake Nicaragua 201 

Station at Las Lajas 202 

Rio Viejo 203 

Rio Xiieva 206 

Quebrada Honda 207 

Station at Tipitapa 208 

San L^baldo and Morrito 211 

Station at Fort San Carlos 211 

Rio Frio 212 

Dry Season inflow to Lake Nicaragua 213 

Rio San Juan 217 

Sabalos Station on Rio San Juan 218 

Rio Sabalos 222 

Castillo Station 223 

Rio San Carlos 226 

Ochoa Station on Rio San Juan : 232 

Rio Machado 242 

Rio Danta ; 243 

Rio San Francisco 243 

Rio Limpio 248 

Upper Station on Rio Chanchos 250 

Lower Station on Rio Chanchos 251 

Nicholson Creek 253 

Rio Sarapiqui 254 

Rio Taura 256 

Rio Deseado 256 

Miscellaneous Stream Measurements 259 

Rainfall 262 

Daily Rainfall at Stations Maintained 264 

Miscellaneous Rainfall Records 278 



196 NICARAGUA CANAL COMMISSION 



Evaporation 



PAGE 

283 



GsNEBAL Conclusions Eeoarding Water Supply 291 

Discussion of Results 291 

Amount of Storage Necessary 292 

Spillway Capacity 294 

Value of the Estimates 296 

Lake Managua as a Storage Reservoir 298 

Sediment Observations 299 

Temperature and Relative HuMiDnY 304 



APPENDIX III 



The Hydrographic and Meteorologic informa- 
tion required by the Nicaragua Canal Commis- 
sion relates to three principal objects: 

1. The water supply for the use and leakage 
of the canal. 

2. The quantity of rainfall and volume of 
streams, considered as obstacles to construction. 

3. The volume and habit of excessive floods, 
with reference to their permanent control and 
discharge without injury to the canal or other 
property. 

The desired information therefore required 
an investigation of the discharge of all streams 
of importance which it was proposed to control 
during construction or foB which it was neces- 
sary to provide diveraion channels or spillways; 
and measurements of rainfall at points as widely 
distributed as possible throughout the basin of 
Lake Nicaragua. 

It also required an approximate determination 
of the rate of evaporation on Lake Nicaragua, 
and some investigation of the sediment carried 
l)v the larffer rivers. 

STREAil MEASUREMENTS. 

The general method used in observing the 
regimen and discharge of streams is substantially 
as follows: 

A point is selected as near as may be to the 
location at which knowledge is desired, having 
reference to the conditions of the stream itself, 
the aim being to secure high permanent banks 



on both sides of the river, a straight channel as 
uniform in depth and velocity as may be, and 
avoiding any location which is a short distance 
above an important tributary, and which for this 
reason might be affected in the matter of back 
water by floods in that tributary. A gage is 
placed in the stream near one bank, graduated 
to feet and tenths, and so situated if possible 
as to be read convenientlv from the shore. It 
is usually possible to fasten such a gage in deep 
water to the trunk of an overhanging tree and 
in a vertical position. The height of ^ater in- 
dicated by this gage is read and recorded usually 
twice every day, and the mean of the two read- 
ings taken as the mean gage height for that date. 
At various intervals, depending upon the facili- 
ties available and the change of gage height, 
measurements of discharge are made with a cur- 
rent meter. Soundings are taken at known dis- 
tances from an assumed initial point and the 
velocity measured by submerging an electric 
current meter at six-tenths of the measured 
depth, and holding it in that position for a 
length of time sufiicient to make a good deter- 
mination of the velocity at that point, usually 
100 seconds or more. This operation is repeated 
at short intervals for the entire width of the 
stream, and from these observations the discharge 
in cubic feet per second is computed for each 
section by multiplpng the depth, width and 
measured velocity together. The discharge of 
the several sections being added together form a 



198 



NICARAGUA CANAL COMMISSION 



result for the discliarge of the entire stream. At 
the beginning and end of the gaging a careful 
note is made of the stage of the water indicated 
on the river gage, and the mean of those two 
observations is taken as the mean gage height 
at the time of observation. It is the effort to 
have such observations well distributed with 
reference to the height of water in the river, in 
order to show the relation of the indications of 
the gage rod to the actual discharge of the 
stream. This relation is found to be reasonably 
definite and uniform for most of the streams, 
and by plotting the gage heights as ordinates 
and the discharge results as abscissas their gen- 
eral relation is established and a curve drawn, 
satisfying as nearly as possible all the observa- 
tions made. 

Bbito Station on Eio Grande. 

This "station was established by D. H. Bald- 
win on January 8, about 1 mile below La Flor 
dam site on Rio Grande, just below where the 
stream bends to the north. 

A cable and gaging car were put in place for 
taking measurements. The gage was driven 
in the bed of the river near the left bank, and 



the top fastened to the tagged wire. As this 
was deemed insecure, a new gage was put in 
place on January 22 about two hundred feet 
farther upstream, which was driven into the 
clay bottom, and spiked to a tree growing on the 
bank. When the old gage read 1.85 the new 
gage read 3.38. The readings are here re- 
duced to the datum of the new gage. 

The channel begins to curve a short distance 
above the station. The left bank is high and 
steep. The right may sometimes overflow at 
high water. Later operations by the surveying 
parties having shown the desirability of measure- 
ments of Rio Tola, the Rio Grande station was 
removed June 13, to a point below the mouth 
of Rio Tola, in order that both streams could 
be observed from one camp. It is about 300 
yards below the junction of the Tola and Rio 
Grande. The gage is a vertical rod divided to 
feet and tenths, and fastened to an overhanging 
tree on the left bank of the river. Xear this 
point the cable is stretched across the river, 
upon which runs a gaging car from which 
measurements are made, a tagged wire being 
stretclied alongside. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO GRANDE BELOW MOUTH 

OP THE TOLA. 



Date. 


Hydrographer. 


Meter 

niirnltPi* 


Gaffe 
heiffht 


Area of 
section 


Mean ve- 
locity (feet 


Discharge 
(second- 


Remarks. 






(feet). 


(sq. feet). 


per sec.). 


feet). 




Jan. 9 D. 


H. Baldwin. . . . 


• • • • 


3.48 


59 


1.36 


80 




" 22 A. 


P. Davis 


94 


8.44 


56 


1.11 


62 




June 4 


it 

• ••••■ 


94 


2.95 


26 


0.68 


18 




July 2 D. 


H. Baldwin 


1984 


8.18 


68 


2.35 


161 


New gage-rod reads, .85^ less. 


♦♦ 30 




1984 


6.80 


815 


4.15 


1,306 




Aug. 10 




1984 


2.40 


70 


0.92 


65 




" 21.... 




1984 


4.30 


164 


2.93 


481 




Sep. 14 




1984 


8.78 


124 


2.73 


339 




'* 21 




Float. 


11.10 


606 


4.55 


2,758 




*' 29.... 




1984 


4.00 


144 


2.94 


428 




Oct. 8 H. 


C. Hurd 


Float. 


3.60 


122 


2.38 


.285 




" 9 


• ••••• 


i( 


5.92 


275 


3.98 


1,092 




»* 10.... 


• •■••• 


i> 


5.00 


218 


3.88 


718 




- 15.... 


• ••■•• 


(i 


8.80 


474 


4.28 


2,026 




'» 27 


• ■•••• 


Meter B. & 
B. No. 1. 


4.25 


163 


4.12 


675 


Velocity taken at .5 depth. 


Nov. 28 


• ••••• 


1 


8.82 


88 


2.88 


249 


ii ti it 


Dec. 13 


• ••••• 


1 


2.99 


69 


2.50 


172 


ti ii ii 



APPENDIX III.— HYDROGRAPHIC REPORT 



199 



RATING TABLE FOR RIO GRANDE BELOW MOUTH OF THE TOLA. 
This table is applicable only from January 6, 1898, to June 13, 1898. 



Gai 



height. I>i«^»>*'-go. 



Gage 
height 



Discharge. 



h?lX "'""argo. 



helX. D'oohargc. 



Gage 
height. 



Discharge. 



Feet. 


Second-feet. 


Feet, 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


2.7 


9 


3.1 


85 


3.5 


75 


3.9 


115 


4.3 


155 


2.8 


12 


3.2 


45 


3.6 


85 


4.0 


125 


• • • 


• • • 


2.9 


17 


3.:^ 


55 


8.7 


95 


4.1 


135 


• • • 


• • • 


8.0 


25 


8.4 


05 


3.8 


105 


4.2 


145 


• • ■ 


■ • ■ 



RATING TABLE FOR RIO GRANDE BELOW MOUTH OF THE TOLA. 
This table is applicable only from June 13, 1898, to December 31, 1898. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feot. 


Second -ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


1.6 


12 


3.6 


261 


5.6 


892 


7.6 


1,575 


9.6 


2,275 


1.7 


13 


3.7 


287 


5.7 


926 


7.7 


1,610 


9.7 


2,310 


1.8 


14 


3.8 


314 


5.8 


960 


7.8 


1,.645 


9.8 


2,345 


1.9 


16 


3.9 


342 


5.9 


994 


7.9 


1,680 


9.9 


2,380 


2.0 


20 


4.0 


371 


6.0 


1,028 


8.0 


1,715 


10.0 


2,415 


2.1 


27 


4.1 


401 


6.1 


1,062 


8.1 


1,750 


10.1 


2,450 


2.2 


35 


4.2 


432 


6.2 


1,096 


8.2 


1,785 


10.2 


2,485 


2.8 


44 


4.3 


464 


6.3 


1,130 


8.3 


1,820 


10.3 


2.520 


2.4 


54 


4.4 


496 


6.4 


1,164 


8.4 


1,855 


10.4 


2,555 


2.5 


65 


4.5 


528 


6.5 


1,198 


8.5 


1,890 


10.5 


2,590 


2.6 


77 


4.6 


560 


6.6 


1,232 


8.6 


1,925 


10.6 


2,625 


2.7 


90 


4.7 


592 


6.7 


1,266 


8.7 


1,960 


10.7 


2,660 


2.8 


104 


4.8 


625 


6.8 


1,300 


8.8 


1,995 


10.8 


2,695 


2.9 


119 


4.9 


658 


6.9 


1,334 


8.9 


2,030 


10.9 


2,730 


3.0 


135 


5.0 


691 


7.0 


1,368 


9.0 


2,065 


11.0 


2,765 


8.1 


152 


5.1 


724 


7.1 


1,402 


9.1 


2,100 


11.1 


2,800 


3.2 


170 


5.2 


757 


7.2 


1,436 


9.2 


2,135 


11.2 


2,835 


8.3 


190 


5.3 


790 


7.3 


1,470 


9.3 


2,170 


11.3 


2,870 


8.4 


212 


6.4 


824 


7.4 


1,505 


9.4 


2,205 


11.4 


2,905 


8.5 


236 


5.5 


858 


7.5 


1,540 


9.5 


2;240 


• • • • 


• • • • 



ESTIMATED MONTHLY DISCHARGE OF RIO GRANDE BELOW MOUTH OF THE TOLA. 



Discharge in Second-Feet. Total in 

Month. / • V A /.«£»_ ij'*w»4. 

Maximum!. Minimum. Moan. Acre-i-oet. 

189H. 

January (6-31) ... 75 60 69 3,340 

February- 55 41 49 2,720 

March 40 25 35 2,150 

April 35 17 25 1,490 

May 85 17 28 1,720 

June 1,990 17 110 6,550 

17,970 



M.«th Disch arge in Secon d-Feet. ^otal in 

Maximum. Minimum. Mean. Acre-ueei 

1898 

Brought forward, 17,970 

July 2,030 55 121 7,440 

August 145 45 67 4,120 

September 2,975 55 ;J53 15,050 

October 2,065 260 596 36,650 

November 1,028 190 282 16,780 

December 190 97 130 7,990 

Total 106,000 



200 



NICARAGUA CANAL C0UUI8SI0M 



"3w 


r 




sss; 


Tfsr 


"J 


X 


(SS 


X, 


MPT. 
ION 


OCT. 1 NOV. 
1 » 1 .0 M 


s%\ 


































































































































































































































































































































































































































































































































1 


















































































; 


































































< 




































1 












1 


hi 


L 


, 










I 


■ 


















-. 






1. 


- 


1 


1 


I 


t 


M 


i 


A 




I 


1 


1 


1 




1 


1 



Fia. 1. Diagram of Dally Dlecbarga of Rio Qruide, 1898. 
LIST OP HBASUREMBNTS HADG ON RIO TOLA. \ MILE ABOVE ITS MOUTH. 



No. 


^- Hydrognipher. 


Meter 
number. 


s 


B.? 


'sTS 


■!»-• ».o,„.. 






Julj a....D. H. Baldwin... 


19S4 


3.31 


48.1 


1.41 


68 






Ang 10... 


" 


1984 


1.60 


39.4 


0.96 


38 






■' 31... 




1«84 


3 


80 


38.1 


3.19 


61 






" 39... 




1984 




35 


98.0 


3.83 


379 






Sept. H... 




1984 




03 


36.8 


2.80 


103 New Rod. 






" ai... 




Ftoite 




i» 


360.8 


2.B7 


TT4 






Oct. 8. . . 


H. C. Hnrd 






S5 


53.7 


3.35 


133 






U. .. 








es 

B5 


69.0 
183.7 


3.71 


187 

408 




10 


■' 17... 








3.5 


iOS.1 


2.86 


800 




11 


Not. 33... 




B. & B. 1 




14 


39.0 


4.31 


163 Velocity taken at 0. 


deptb. 


13 


" 37... 




I 




]S 


36.5 


S.73 


136 




18 


Dec. 18... 




1 




75 


36.3 


3.30 


114 






APPENDIX III.— HYDROGRAPHIC REPORT 



201 



RATING TABLE FOR RIO TOLA % MILE ABOVE ITS MOUTH. 
This table is applicable only from September 1, 1898, to November 1, 1898. 



Gai 



Gage 



heiX D'Bcharge. hegfft. Discharge 



hel^t. Dtacharge. 



hel^t. D"»o»""KO- biliSt. Discharge. 



Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft, 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


2.0 


18 


3.1 


91 


4.2 


252 


5.3 


428 


6.4 


608 


2.1 


20 


3.2 


103 


4.3 


268 


5.4 


444 


6.5 


625 


2.2 


24 


3.3 


116 


4.4 


284 


5.5 


460 


6.6 


642 


2.3 


29 


3-4 


130 


4.5 


300 


5.6 


476 


6.7 


659 


2.4 


34 


3.5 


145 


4.6 


316 


5.7 


492 


6.8 


«76 


2.5 


40 


3.6 


160 


4.7 


332 


5.8 


508 


6.9 


698 


2.6 


46 


3.7 


175 


4.8 


348 


5.9 


524 


7.0 


710 


2.7 


53 


3.8 


190 


4.9 


864 


6.0 


540 


7.1 


728 


2.8 


61 


3.9 


205 


5.0 


380 


6.1 


557 


7.2 


746 


2.9 


70 


4.0 


220 


5.1 


396 


6.2 


574 


7.8 


764 


3.0 


80 


4.1 


236 


5.2 


412 


6.3 


591 


. • . 


• • • 



RATING TABLE FOR RIO TOLA % MILE ABOVE ITS MOUTH. 
This table is applicable only from November 1, 1898, to December 31, 1898. 



Gage 
height. 


Discharge. 


hei^t. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft^ 


2.6 


65 


3.0 


108 


3.4 


168 


3.8 


228 


2.7 


78 


3.1 


123 


3.5 


183 


3.9 


244 


2.8 


83 


3.2 


138 


3.6 


198 


4.0 


260 


2.9 


95 


3.3 


153 


3.7 


213 


4.1 


276 



ESTIMATED MONTHLY DISCHARGE OF RIO TOLA % MILE ABOVE ITS MOUTH. 



Month. 
1808. 



Discharge in Second-Feet. Total in 



Maximum. Minimum. Mean. Acre-Feet. 



Month. 
1898. 



Discharge in Second- Feet. Total in 
Maximum. Minimum. Mean! Acre-Feet. 



June (9-30) 355 

July 163 

August 57 

September 364 



12 
21 
20 
39 



53 

46 

30 

113 



2,310 
2,830 
1,840 
6,660 

13,640 



October 452 

November 270 

December 100 

Total 



Brought forward, 13,640 
130 246 15,125 

100 160 9,520 

65 79 4,860 



43,145 



Lake Xicaraoua. 

Lake Nicaragua has an area of 2975 square 
miles. Its greatest length is from north-north- 
west, to south-southeast, and is about 100 miles. 
Its extreme width is about 45 miles. 

West of the center is an island occupied by 
the volcanoes Ometepe and iladera, which stand 
about 5000 feet above the lake level, adding 
greatly to the scenic beauty. 



Madera is the most southern of a line of vol- 
canoes of comparatively recent origin, which 
extends in a northwesterly direction nearly to 
the bay of Fonseca, including Ometepe, Zapa- 
tero, Mombacho, Chiltepe, Momotombo, and 
manv others. 

The prevailing easterly trade winds cause a 
moderately- heavy surf to beat almost constantly 
on the western shore, causing the formation of 



202 



NICARAGUA CANAL COMMISSION 



a decided beach on tliat side, while on the east- 
em shore aquatic vegetation grows far out into 
the water. This shore is flat and muddy, with 
no well-marked beach. 

Except in the southeastern portion the lake is 
deep, reaching in one point near the southern 
foot of Madera to a depth of 200 feet. 

Lake Nicaragua receives the waters of a large 
number of tributaries, the most important being 
Rio Frio and Rio Pisote on the southern end, 
which rise in the high mountains of Costa 
Rica and maintain their flow throughout the 
dry season, and Malacatolla and Tipitapa on the 
northern end. The latter brings the waters of 
Lake Managua, which lies to the northwest of 
Lake Nicaragua and has an area of al)out 500 
square miles. The drainage area as estimated 
from the best information obtainable, is as fol- 
lows: 

Sq. miles. 

Area of land surface draining directly 

to Lake Nicaragua 6,640 

Area of Lake Nicaragua 2,975 

Lake Managua and tributary basin. . . . 3,035 

Total 12,450 

The control of the waters of Lake Nicaragua 
is vital to the practical operation of the proposed 
ship canal and has an important bearing upon 
the cost and the plans of any project proposed. 
Careful observations of its fluctuations, of the 
maximum and minimum inflow and outflow, and 
of evaporation from its surface are therefore 
-very important. 

Las Lajas. 

A station was established on the margin of 
Lake Nicaragua, about seven miles southeast 
of Rivas, and about 3500 feet north of the 
mouth of Las Lajas, on January 19. The gage 
was placed in a long box with open ends and 
seams, which was fastened to the sunken wreck 



of a large boiler of one of the Vanderbilt 
steamers, as shown in the figure. The box and 
the boiler served to protect the gage from the 
violence of the breakers prevalent on this coast, 
but afforded entirely free access to the water. 
The gage as first placed was insecurely fastened, 
and during a storm the waves beat it down. It 
was replaced on February 7 by Mr. J. A. Bull 
in the position which it now occupies. The 
gage is inclined to the vertical to such an ex- 
tent that one foot vertical corresponds to 1.014 
foot on the rod. The 10-foot mark is .65 feet 
below bench mark No. 1, which is the highest 
point of a large cylinder nearly buried in the 
sand on shore. The 10-foot mark is 108.04 
feet above sea level by the levels of the Nica- 
ragua Canal Commission. 

The ebb and flow of the waves kept the water 
level constantly changing on the rod, and the 
readings were taken by averaging high and low 
readings occurring within a few seconds. Most 
of the time the eastern trades blew constantly, 
with considerable force, but during May were 
many calm days, and some adverse winds. 

During April the declining lake surface 
threatened to leave the gage on dry land, and 
another gage was placed in deeper water, about 
200 feet north of the first one. This was placed 
vertical and fastened to another portion of the 
wreck. On this gage the 9-foot mark is 103.19 
feet above sea level. It was observed from May 
1 to July 1 6, when the surf became too deep for 
the observer to safely read it, and observations 
were transferred to gage No. 1. 

Temperature, humidity and wind observations 
were taken at this station, and at the mouth of 
Las Lajas an evaporation pan and rain gage were 
maintained and observed. 

The elevation of Lake Nicaragua is given 
under the head of Fort San Carlos, page 211. 



APPENDIX III.— HYDHOORAPHIC REPORT 



203 



Kio ViEJO, 
This station is abotit 500 yards above the ford 
known as Paso Real on the Rio Viejo where 
the Matagalpa-Leon road crosses the Rio Viejo. 
A gage was placed at this point on February 1, 
wliich consisted of a vertical unpainted cedar 
stick, marked with nails and notches to feet and 
tenths, nailed to a tree on the right bank. A 
bench mark was established on tho right bank 



consisting of a wire nail driven in the highest 
point of a stump 66 feet west of the gage. It 
is 46.2 feet above zero of gage, A cable was 
stretched across the river a short distance above 
the gage from which measurements of floods 
were made by means of a gaging car of the 
usual pattern. Measurements at low water 
were made by wading. 



■ 



m 



Fio. 2. Diagram of Dally Dlscharse ot Rfo Vlelo, 189S. 
DAILY GAGE HEIGHT OF RIO VIEJO AT PASO REAL FOR 1898. 



Har. April. Mar. June. July. Aug. Sept. 



Oct, Nov. 







l.WS 


.84 


.71 


3.75 


7.01 S 


57 


4.30 


5.30 


3.96 


3.75 


3,41 




3.B7 


I.B7 




.71 


3.35 


6.86 ! 


45 


8.05 


4.65 


3.85 


3.74 


3.40 




3.84 


i.es 




.71 


3 95 


5.97 3 


54 


3.78 


5.85 


3.73 


3,73 


3,41 




3.83 


L99 




.71 


3.75 


■5.4S ! 


41 


4.35 


4.49 


S.S5 


3.71 


3.43 




3.30 


1.00 


.81 


.71 


3.61 


5.17 3 


H] 


9.00 


4.31 


8.61 


3.70 


3.45 




3.38 


1.B8 


.81 


.71 


3.S5 


4.91 




5.85 


4.03 


.'i.53 


3.68 


3.97 




2.25 


3.18 


.80 


.70 


3.74 


5.13 




.%.10 


3.88 


8.41 


3.75 


a.84 




3.30 


2.13 


.80 


.70 


4.0:1 


5.68 




4.50 


3.97 


3.88 


3.78 


3.79 




3.19 


3.09 




.70 


4.45 








4.95 


3,38 


3.95 


2.69 


10 


3.18 


3.00 




.70 


4.01 








4.84 


8,95 


3.94 


3.63 


11 


3.17 


3.0.5 


.78 


.70 


4.44 




30 




8.94 


S.19 


3.89 


3.59 


13 


3.1S 




.77 


.70 


3.56 


8.69 






6.40 


3.30 


3,78 


8.56 


13 


3.U 




.76 


.70 


S.15 


6.70 






«,:!3 


3,43 


3 74 


3.53 



204 



NICARAGUA CANAL COMMISSION 



DAILY GAGE HEIGHT OF RIO VIEJO AT PASO REAL FOR 1898.— Continued. 



Day 


Feb. 
1808. 


Mar. 


April. 


May. 


Juno. 


July. 


Aug. 
3,30 


Sept 
14.50 


6. .30 


Nov. 
3. ,59 


Dec. .Tan. 
IHW. 


14 


2.18 


1.98 


L74 


1.70 


2.98 


6.84 


8.71 3. .50 


15 


2.11 


1.97 


1.74 


1.70 


2.75 


5.90 


3.80 


17. .50 


6.37 


3.37 


3.69 2.49 


16 


f • • • 


1.95 


L74 


1.70 


2.65 


5.85 


• • • • 


9.50 


.5.31 


.3.13 


2.66 2.49 


17 


• • • - 


1.98 


1.74 


1.70 


2.62 


4.77 


.... 


7.75 


6.45 


.3.07 


2.63 2.48 


18 • 


2.08 


1.93 


1.78 


1.79 


8.11 


4.46 


.... 


6.35 


9.00 


.3.00 


2.00 2.48 


19 


2.08 


1.92 


1.78 


1.84 


9.90 


4.17 


- • • • 


6. ,53 


7.33 


' ,3.00 


2. .59 2.45 


20 


2.06 


1.9S 


1.'.'2 


1.80 


30.70 


3.97 


.... 


6.80 


10.89 


3.98 


2. .58 2.44 


21 


2.02 


1.91 


1.78 


1.96 


12.50 


3.83 


.... 


6.60 


8.44 


3.95 


2. .56 2.43 


23 


2.01 


1.00 


1.72 


2.81 


10.34 


3.70 


.... 


5.95 


9.07 


3.95 


3. ,50 2.35 


28 


2.05 


1.88 


1.72 


6.55 


8.63 


8.65 


.... 


5 81 


7.04 


2.91 


•»• "W .... 


24 


2.02 


1.87 


1.72 


6.60 


13.85 


8.65 


5.60 


,5.20 


5.90 


2.90 


2..56 


25 


2.01 


1.85 


1.72 


11.94 


9.90 


3.43 


4. .38 


4.75 


.5.43 


3.87 


*tm »tt .... 


26 


• • ■ 


1.88 


1.71 


6.78 


7.35 


3.38 


3.93 


5.10 


5.70 


3.84 


3.51 


27 


• car 


1.87 


1.71 


5.71 


6.40 


3.38 


3.76 


7.85 


5.37 


3.84 


3.48 


28 


• • • • 


1.85 


1.71 


5.15 


27.00 


8.50 


3.65 


6.25 


4.90 


3.83 


3.48 


29 


• • • • 


1.83 


1.71 


.5.59 


11.41 


3.78 


9.33 


.5.31 


4.75 


3.84 


O AK 

•w.t.y .... 


30 


• • • • 


1.85 


1.71 


4.31 


8.03 


3.71 


.5.55 


6.08 


4.43 


3.80 


o 44 


81 


• • • • 


1.83 


■ • • • 


4.14 


• • • • 


3.62 


3.90 


• • ■ • 


4.16 


• ■ • ■ 


3.43 




LIST OF DISCHARGE MEASUREMENTS MADE ON RIO VIEJO AT 


PASO REAL. 


Date. 




Hydrotirrapher. 




Meter 
number. 


GaKe 
beiflrht 
(feet). 




Area of 

sootion 

(square feet). 


Mean velocity 

(feet 

|)er second). 


DiM;hargo 
l8econd- 

l<HJt). 


Feb. 8. 




.F. C. G 


reen 




7 
7 


2.20 
2.08 




17.7 
14.1 




1.60 
1.40 


3S 3 


»» 18. 






30.7 


*« 28. 




iC 

ct 

tl 

(t 

G. p. PI 






7 
7 
7 
7 
7 
7 


1.99 
2.12 
1.94 
1.85 
1.79 
1.72 




12.8 
14.0 
11.4 
10.8 
9.6 
6.2 




1.30 
1..57 
1.33 
0.55 
0.44 
0.61 


1,5.3 


Mar. 8. 






33.0 


*« 18. 






14.0 


•• . 28. 






6.0 


April 8. 
•» 20. 






4.3 


tilllp... . 


•••••• 


3.8 


" 28. 




(I 






7 

7 


1.71 
1.71 




5.4 
7.3 




0.,58 
0.37 


3.3 


May 6. 






3.5 


" 14. 




It 
t( 

4( 
(i 
t4 
It 
it 
il 
i( 






7 

7 
7 
7 
7 
7 
7 
7 
7 


1.70 

3.13 

12. .53 

3.65 

3.63 

2.78 

11.63 

13.34 

4.95 




6.8 

63.4 
964.0 

74 

68 

33 
895 
976 
1.57 




0.33 
3.30 
5.06 
4.39 
4.04 
3. .54 
4.85 
4.C5 
3.91 


2.2 


»* 22. 






306 


" 25. 






4874 


Jnne 1 . 






317 


<> 8 






374 


•* 15. 






114 


»' 23. 








4.344 


♦' 29. 








4539 


July 6. 
»♦ 13. 






4.56 




it 
tt 
tt 
tt 
tl 
It 

..Fred. D 
it 

It 






7 
7 
7 

7 

■» 
i 

1 

7 
7 
7 


6. ,50 
3.97 
3.38 
3.59 
5.73 
8.33 
5.03 
.'i.OO 
9.90 




315 

83 

55 

66 

188 

460 

144 

184 

674 




3.08 
3.21 
3.78 
3.93 
4.40 
4.53 
3.36 
4.41 
4.89 


1073 


*' 20. 








266 


»' 37. 






153 


AuL^. 3. 








193 


Sep. 19 








H2S 


♦* 37. 








2,074 


Oct. 3. 




avis 




469 


'' 10. 




813 


'* 18 






3,300 








— « 



NICARAGUA CANAL COMMISSION 



APPENDIX 3, PLATE I 




APPENDIX III.— HYDROGRAPHIC REPORT 



205 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO VIEJO AT PASO REAL.— Continued. 



Date. 
1806. 


Hydrographer. ^^^^^ 


■ 


Gage 

height 

(feet). 


Area of Mean velocity 
section (feet 
(square feet). per second). 


Discharge 
(second- 
feet). 


Oct. 25. 


Fred. 


Davis . . . 




7 
7 
7 

7 
7 
7 
7 
7 
7 
7 
7 




5.41 
4.00 
3.42 
3.52 
2.95 
2.82 
2.70 
2.94 
2.68 
2.56 
2.45 


216 
81 
54 
72 
34 
85 
27.5 
45 
33.5 
28.5 
25 




4.11 
3.48 
3.42 
2.16 
2.73 
2.36 
2.74 
1.95 
1.76 
1.71 
1.59 




886 


Nov. 1. 


i 


282 


" 7. 






182 


»' 14 » 






228 


" 21 


* 






94 


" 28. 






82 


Dec. 5. 


i 

i 






75 


»« 10. 






88 


t* 15.. 4 






59 


*» 22 * 






49 


** 29. * 






39 


1899. 










Jan. 8 


* 






7 
7 
7 




2.40 
2.68 
2.49 


25.6 
34.7 
25.7 




1.28 
1.77 
1.74 




81.5 


u 9 






61.3 


" 15. 






44.9 




RATING TABLE FOR RIO VIEJO AT CROSSING OF MATAGALPA-LEON ROAD. 






This table is applicable only from May 21, 1898, to December 1, 


1898. 






Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 




Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. Seoond-feet. 


Feet. 


Second-feet. 




Feet. 


Second-feet. 


Feet 


Becond-feet. 


Feet. 


Second-feet. 


1.5 





4.6 


884 




7.7 


1,760 


10.8 


3,765 




13.9 


5,780 


1.6 


1 


4.7 


406 




7.8 


1,820 


10.9 


3,830 




14.0 


5,845 


1.7 


3 


4.8 


4?8 




7.9 


1,880 


11.0 


3,895 




14.1 


5,910 


1.8 


6 


4.9 


452 




8.0 


1,945 


11.1 


8,960 




14.2 


5,975 


1.9 


10 


5.0 


475 




8.1 


2,010 


11.2 


4,025 




14.3 


6,040 


2.0 


15 


5.1 


500 




8.2 


2,075 


11.3 


4,090 




14.4 


6,105 


2.1 


21 


5.2 


525 




8.3 


2,140 


11.4 


4,155 




14.5 


6,170 


2.2 


28 


5.3 


555 




8.4 


2,205 


11.5 


4,220 




14.6 


6,285 


2.3 


36 


5.4 


585 




8.5 


2,270 


11.6 


4,285 




14.7 


6,300 


?.4 


44 


5.5 


620 




8.6 


2,335 


11.7 


4,350 




14.8 


6,365 


2.5 


52 


5.6 


655 




8.7 


2,400 


11.8 


4,415 




14.9 


6,480 


2.6 


60 


5.7 


695 




8.8 


2,465 


11.9 


4,480 




15.0 


6,495 


2.7 


68 


5.8 


735 




8.9 


2,530 


12.0 


4,545 




15.1 


6,510 


2.8 


77 


5.9 


780 




9.0 


2,595 


12.1 


4,610 




15.2 


6,625 


2.9 


86 


6.0 


830 




9.1 


2,660 


12.3 


4,675 




15.3 


6,690 


3.0 


98 


6.1 


880 




9.2 


2,725 


12.3 


4,740 




15.4 


6,755 


3.1 


112 


6.2 


930 




9.3 


2,790 


12.4 


4,805 




15.5 


6,820 


3.2 


126 


6.3 


980 




9.4 


2,855 


12.5 


4,870 




15.6 


6,885 


3.3 


140 


6.4 


1,030 




9.5 


2,920 


12.6 


4,935 




15.7 


6,950 


3.4 


156 


6.5 


1,080 




9.6 


2,985 


12.7 


5,000 




15.8 


7,015 


3.5 


172 


6.6 


1,130 




9.7 


3,050 


12.8 


5,065 




15.9 


7,080 


3.6 


188 


6.7 


1,180 




9.8 


3,115 


12.9 


5,130 




16.0 


7,145 


3.7 


206 


6.8 


1,235 




9.9 


8,180 


13.0 


5,195 




16.1 


7,210 


3.8 


224 


6.9 


1,290 




10.0 


8,245 


13.1 


5,260 




16.2 


7,275 


3.9 


242 


7.0 


1,345 




10.1 


3,310 


13.2 


5,325 




16.3 


7,340 


4.0 


262 


7.1 


1,400 




10.2 


8,875 


13.8 


5,390 




16.4 


7,405 


4.1 


282 


7.2 


1,460 




10.8 


3,440 


13.4 


5,455 




16.5 


7,470 


4.2 


302 


7.3 


1,520 




10.4 


3,505 


13.5 


5,520 




16.6 


7,585 


4.3 


322 


7.4 


1,580 




10.5 


3,570 


13.6 


5,585 




16.7 


7,600 


4.4 


342 


7.5 


1,640 




10.6 


3,635 


13.7 


5,650 




16.8 


7,665 


4.5 


363 


7.6 


1,700 




10.7 


3,700 


13.8 


5,715 


- 


16.9 


7,730 



206 



NICARAGUA CANAL COMMISSION 



RATING TABLE FOR RIO VIEJO AT CROSSING OF MATAGALPA-LEON ROAD. 
This table is applicable only from December 1, 1898, to January 22, 1899. 



heSht. I>i8charge. 



Feet. Second-feet. 
1.9 10 

2.0 15 

2.1 20 



heiX. ^'^^^^^'' heS't. I>»»^han?f. ^J^^ Discharge. 



Feet. Second-feet. 
2.2 26 

2.8 32 

2.4 38 



Feet. Second - feet. 

2.5 45 

2.6 58 

2.7 68 



Feet. Second-feet. 

2.8 74 

2.9 86 
8.0 98 



he^^t. I>i8charge. 



Feet. Second-feet. 

3.1 112 

8.2 126 

8.3 140 



Month. 



ESTIMATED MONTHLY DISCHARGE OF RIO VIEJO AT CROSSING OF MATAGALPA- 
LEON ROAD. 



Discharge in Second-Feet. Total in 
Maximum. Minimum. M<«n. Acre-Feet. 



Month. 



Discharge in Second-Feet. 

, * , 

Maximum. Minimum. Mean. 



Total in 
A ere- Feet. 



1898. 

Fcbniary 36 

March 25 

April 5 

May 5,520 

June 15,600 

July 2,400 

August 2,750 



15 


24 


1,882 


5 


18 


800 


3 


3.0 


214 


2 


824 


19,920 


50 


2,170 


129, 120 


155 


618 


87,680 


125 


380 


20,290 






209,356 



1898. 

September 

October 

November 

December 

1899. 
January 

Total 



Brought forward, 209,856 



9,745 

8,830 

253 

92 



220 

280 

74 

39 



1,765 

965 

130 

59 



105,025 

59,340 

7,785 

3,630 



Totol for 1898 385,086 

94 35 49 8,018 

.388,099 



Rio Xueva. 
This station was established February 1, at 
the bend of Rio Nueva, where it approaches 
nearest Rio Viejo, in the neighborhood of Paso 
Real, and was intended to throw light on the 
quantity of water that might be added to the 
supply for Lake Managua by diverting this river 
into it. 



Measurements were made by wading at low 
water and by means of floats at high water. The 
stage of the river was ascertained by measuring 
downward with a tape-line from a nail driven 
in an overhanging trunk of a tree. These 
measurements were carried on by the same ob- 
server who had charge of the station at Rio 

'XT' • 

A lejo. 



Date. 

1H08. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO NUEVA NEAR RIO VIEJO. 



Hydroffraphcr. 



May 28 G. P. Philip 

27. 
June 8. 

»' 10. 
'» 17. 
«* 24. 
July 1. 
8. 
** 15. 






ii 
ti 
tt 
(t 
i( 
ii 
(i 
li 
tt 



Meter 
number. 


Gag© 
heiffht 

(feet). 


Area of 
section 

(sq. ft.). 


Mean ve- 
locity (ft 
per sec.). 


Dischai«o 
(second- 
feet.). 


Remarks. 


Floats. 


5.0 


178 


2.54 


451 




it 


4.3 


126 


2.18 


275 




7 


8.0 


50 


0.70 


35.4 




Floats. 


8.42 


71 


1.82 


9S.6 


« 


7 


.3.02 


57 


0.69 


39.5 




Floats. 


18.10 


490 


4.81 


2861 


New Gag:e-Rod. 


ti 


14.80 


280 


8.01 


698 




it 


14.70 


223 


2.79 


622 




it 


14.30 


198 


2.29 


441 




it 


18.0 


105 


1.87 


143 





APPENDIX III.— HYDROGRAPHIC REPORT 



207 



LIST OP DISCHARGE MEASUREMENTS MADE ON RIO NUEVA NEAR RIO VIEJO.— Continued. 



Date. 
1888. 


Hydrographer. 


Meter 
number. 


Gaffe 
height 
(feet). 


Area of 
section 
(sq. ft). 


Mean ve- 
locity (ft 
per sec). 


Discharge 

(second- Remarks, 
feet). 


July 29 


. .G. P. Philip 


Floats. 


13.4 


132 


2.14 


282 


" 29. . . . 


ti 


7 


13.4 


138 


2.03 


269 


Aug. 26 


ti 


Floats. 


12.5 


74 


1.86 


138 


Sept 17 


li 


ti 


15.0 


248 


2.84 


704 Approximation. 


*» 28... 


ii 


it 


15.8 


303 


2.71 


821 


Oct 3... 


...Fred. Dayls 


ti 


14.1 


181 


2.35 


425 


14... 


ti 


it 


15.2 


265 


2.83 


750 


'* 22... 


ii 


it 


16.4 


850 


8.93 


1,376 


*' 81... 


ti 


it 


14.1 


181 


2.84 


514 


Noy. 6. . . 


it 


it 


13.8 


124 


2.76' 


348 


12... 


it 


i« 


13.5 


76 


2.47 


187 


19... 


ti 


ti 


12.80 


31 


2.22 


65.5 


24... 


it 


i« 


12.V0 


80 


1.97 


60 


28... 


it 


t« 


12.70 


80 


2.17 


66 


Dec. 4. . . 


t* 


7 


12.60 


48 


1.06 


51 


8... 


it 


7 


12.50 


45 


0.99 


45 


15 .. 


it 


7 


12.80 


42.5 


1.16 


49 


*» 21... 


ti 


7 


12.21 


36. 


0.77 


28 


'* 80... 


it 


7 


12.15 


34.6 


0.60 


20.7 


1899. 














Jan. 2... 


it 


7 


12.21 


38.8 


0.78 


80.8 


9... 


it 


7 


12.30 


40.3 


1.01 


40.7 


15... 


ti 


7 


12.19 


36.2 


0.71 


25.8 



RATING TABLE FOR RIO NUEVA NEAR RIO VIEJO. 
This table is applicable only from June 24. 1898, to January 22, 1899. 



Gage 
height 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height 


Discharge. 


Feet 


Second-feet 


Feet 1 


Second-feet 


Feet 


Second-feet 


Feet 


Second-feet. 


Feet 


Second- feet 


12.3 


80 


13.5 


300 


14.7 


590 


15.9 


1,080 


17.1 


1,660 


12.4 


90 


18 6 


820 


14.8 


625 


16.0 


1,125 


17.2 


1,720 


12.5 


105 


18.7 


840 


14.9 


660 


16.1 


1,170 


17.3 


1,780 


12.6 


120 


13.8 


360 


15.0 


700 


16.2 


1,215 


17.4 


1,850 


12.7 


140 


18.9 


880 


15.1 


740 


16.3 


1,260 


17.5 


1,920 


12.8 


160 


14.0 


400 


15.2 


780 


16.4 


1,305 


17.6 


1,990 


12.9 


180 


14.1 


425 


15.3 


820 


16.5 


1,850 


17.7 


2,060 


13.0 


200 


14.2 


450 


15.4 


860 


16.6 


1,400 


17.8 


2,130 


13.1 


220 


14.3 


475 


15.5 


900 


16.7 


1,450 


17.9 


2,200 


18.2 


240 


14.4 


500 


15.6 


945 


16.8 


1,500 


18.0 


2,280 


18.3 


260 


14.5 


530 


15.7 


990 


16.9 


1,550 


• • • • 




13.4 


, 280 


14.6 


560 


15.8 


1,085 


17.0 


1,600 


• • • • 





River dry from February 13 to May 20. 



QUEBRADA Hoin)A. 

This stream is tributary to Rio Viejo about 
two miles below the station on the latter. A 
gage was placed one-half mile above the wagon 



ford on the road from Leon to Matagalpa and 
graduated to feet and tenths. At low water, 
measurements were made by wading; at high 
water, bv means of floats. 



208 



NICARAGUA CANAL COMMISSION 



LIST OF DigCHARGE MEASUREMENTS MADE ON QUEBRADA HONDA ABOVE CROSSING OF 

MAT AG ALP A- LEON ROAD. 



Date. 


Rydrographer. 


Meter 
number. 


Gage 
height 

(feet). 


Area of 
section 
(sq. ft.). 


Moan ve- 
locity (ft. 
per sec. )• 


Discharge, 
(second- 
feet). 


May 27... 


...J. G. Philips 


Floats. 


5.10 


112 


1.59 


178 


June 8... 


ti 


7 


4.10 


69 


0.27 


19 


10... 


ti 


Floats. 


4.88 


104 


1.65 


171 


17... 


n 


7 


4.22 


79 


0.32 


25 


»' 25... 


ti 


Floats. 


9.10 


276 


4.85 


1,200 


July 1... 


t( 


tl 


5.28 


109 


1.82 


198 


" 29. . . 


it 


7 


4.22 


74 


0.48 


35 


Aug. 26... 


u 


Floats. 


4.60 


88 


1.64 


145 


Sept. 28. . . 


tl 


tt 


5.68 


129 


2.18 


281 


Oct. 4... 


...Fred. Dayls 


t( 


4.68 


89 


1.61 


144 


11... 


tl 


tt 


. 4.75 


98 


1.89 


176 


•» 28... 


It 


ti 


7.05 


184 


3.23 


593 


" 80... 


It 


ti 


4.62 


89 


1.72 


153 


Nov. 6... 


tt 


It 


4.80 


76 


1.01 


76 


12... 


tt 


it 


4.21 


78 


0.71 


52 


19... 


It 


it 


4.05 


68 


0.43 


29 


" 24. . . 


It 


it 


4.00 


65 


0.87 


24.5 


'* 28... 


It 


it 


3.98 


65 


0.36 


23.5 


Dec. 4... 


It 


7 


8.90 


8.5 


1.12 


9.5 


9... 


It 


7 


8.90 


7.5 


0.80 


6.0 


•* 16 .. 


tt 


7 


3.85 


7.5 


0.84 


6.3 


*' 22... 


tl 


to 
t 


3.80 


6.2 


0.59 


3.7 


** 28... 


It 


7 


8.80 


8.9 


0.48 


1.9 



TiPITAPA. 

A gage was placed in this river about 100 
yards above Tipitapa falls, which serves both to 
register the stage of the river and the height of 
Lake Managua upon which the stage of the river 
depends. During low water the river was too 
sluggish above the falls for accurate measure- 
ments with current meter, and gagings were 
made from the bridge below the falls. As the 
river rose it became very turbulent and swift at 
the bridge, but at the same time the velocity in 
the upper river increased and good measure- 
ments were made above the falls. Observations 
of rainfall and evaporation were also made at 
this point. 

Lake Managua lies to the northwest of Lake 
Nicaragua and drains into the latter through 



Eio Tipitapa. Its area is about 438 square 
miles. 

Reports of the discharge of Tipitapa river are 
conflicting. All agree that the stream goes 
dry in the latter part of every dry season. Some 
authorities assert that it has been dry for several 
years in succession, the inflow during the rainy 
season being insufiicient to compensate for evapo- 
ration, while others maintain that there is more 
or less outflow every year in the rainy season. 
Investigations were therefore made to determine 
roughly the feasibility of diverting the Rio 
Nueva which now drains into the Rio Grande, 
into Rio Viejo and finally into Lake Managua. 
Near the station on Rio Viejo the two rivers 
approach within about a mile of each other and 
the intervening country is low and flat. The' 
river channels are 30 to 40 feet deep and a cut 



APPENDIX III.— HYDROGRAPHIC REPORT 



209 



of this depth connecting the two could be made 
to conduct the waters of Rio Xueva into liio 
Viejo, if a dam were built in Rio Xueva below 
the point of connection. There is rock on the 



bottom of Rio Xueva showing fairly good foun- 
dation for such a structure, but the excavation 
of the canal would be almost entirely in alluvial 
earth. 



DAILY GAGE HEIGHT OF RIO TIPITAPA AT TIPITAPA ABOVE FALLS FOR 1898.* 



Day. 

1808. 


Feb. 


Mar. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Doc. 


Jan. 
180U. 


1 


4.44 


8.92 


3.10 


2.65 


3.61 


5.41 


5.19 


5.72 


7.34 


8.05 


7.05 


6.20 


2 


4.89 


3.92 


3.13 


2.56 


3.61 


5.50 


5.27 


5.70 


7.34 


7.95 


7.10 


6.20 


3 


4.42 


8.92 


• • • • 


2.59 


8.59 


4.90 


5.27 


5.66 


7.30 


7.90 


7.00 


6.20 


4 


4.83 


3.89 


2.91 


2.55 


8.53 


5.39 


5.33 


5.76 


• • • • 


7.80 


6.95 


6.18 


5 


4.35 


8.81 


8.10 


2.54 


8.62 


5.36 


5.24 


5.90 


7.25 


7.80 


6.90 


6.15 


6 


4.38 


3.78 


3.12 


2.54 


8.68 


5.53 


5.27 


5.t)0 


7.25 


7.75 


6.85 


6.10 


7 


4.36 


3.78 


3.08 


2.52 


8.65 


5.68 


5.88 


5.90 


7.30 


7.75 


6.85 


6.08 


8 


4.32 


3.80 


2.99 


2.49 


8.62 


5.44 


5.37 


5.70 


7.40 


7.70 


6.80 


6.00 


1) 


4.32 


• • • • 


2.97 


2.47 


8.62 


5.36 


5.26 


5.94 


7.35 


7.65 


6.75 


5.98 


10 


4.28 


3.81 


2.93 


2.48 


3.69 


5.60 


5.20 


5.96 


7.40 


7.70 


6.75 


6.00 


11 


4.25 


3.78 


2.95 


2.49 


8.71 


5.42 


5.23 


6.14 


7.85 


7.65 


6.72 


5.90 


12 


4.23 


3.75 


2.86 


2.45 


3.91 


5.47 


5.33 


6.28 


7.35 


7.65 


6.70 


5.95 


13 


4.12 


3.78 


2.97 


2.45 


3.71 


5.49 


5.24 


6.48 


7.32 


7.70 


6.70 


5.85 


14 


4.17 


8.74 


2.98 


2.39 


3.66 


5.50 


5.31 


6.62 


7.40 


7.60 


6.65 


5.85 


15 


4.20 


8.68 


2.95 


2.42 


3.65 


5.42 


5.37 


6.78 


7.37 


7.55 


6.60 


5.90 


16 


4.18 


3.57 


2.96 


2.47 


3.67 


5.34 


5.29 


6.95 


7.50 


7.50 


6.55 


5.88 


17 


4.11 


3.52 


2.84 


2.52 


3.77 


5.48 


5.31 


6.94 


7.62 


7.40 


6.55 


5.85 


18 


4.18 


3.51 


2.91 


2.67 


3.88 


5.32 


5.28 


6.94 


7.72 


7.45 


6.50 


5.88 


19 


4.11 


8.48 


2.86 


2.82 


3.89 


5.38 


5.27 


6.95 


7.72 


7.35 


6.55 


5.80 


20 


4.16 


3.41 


2.78 


2.80 


4.03 


5.82 


5.27 


6.96 


7.87 


7.30 


6.50 


5.85 


21 


4.08 


8.41 


2.78 


2.92 


4.12 


5.86 


5.31 


7.18 


7.95 


7.30 


6.52 


5.70 


22 


4.05 


3.40 


2.77 


3.08 


4.51 


5.48 


5.31 


7.18 


7.95 


7.30 


6.50 


5.75 


28 


4.05 


3.50 


2.79 


8.18 


4.62 


5.40 


5.41 


7.18 


8.00 


7.25 


6.45 


5.72 


24 


4.01 


3.43 


2.80 


8.38 


4.76 


5.33 


5.36 


7.24 


7.92 


7.25 


6.40 


• • • • 


25 


8.94 


3.34 


2.79 


8.57 


4.86 


5.31 


5.35 


7.26 


7.95 


7.20 


6.40 


• • • • 


26 


3.93 


3.21 


2.68 


8.67 


4.95 


5.40 


5.38 


7.20 


7.95 


7.20 


6.35 


• • • ■ 


27 


8.96 


8.26 


2.62 


3.70 


4.87 


5.26 


5.42 


7.31 


8.00 


7.15 


6.80 


• • • • 


28 


8.95 


8.30 


2.65 


3.67 


5.16 


5.25 


5.64 


7.38 


8.02 


7.15 


6.30 


• • • • 


29 


• • • • 


3.28 


2.67 


3.68 


5.38 


5.26 


5.60 


7.40 


8.00 


7.10 


6.25 


• • • • 


80 


• • • • 


3.1G 


2.60 


3.58 


5.48 


5.30 


5.68 


7.34 


8.00 


7.05 


6.20 


• • • • 


81 


• • • • 


3.13 


• • • • 


3.65 


• • • • 


5.39 


5.69 


• • • • 


8.00 


• • • ■ 


6.20 


• • • • 



* This table also indicates the fluctuations of Lake Mauagua. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO TIPITAPA AT TIPITAPA. 



No. 



1 
2 
3 

4 
5 
6 



Date. 
1898 



Hydrogrrapher. 



Meter 
number. 



Gage Area oU Mean ve- Discharge 

height section locity (feet (secono- 

(feet). (square ft.), per second) feet). 



Apr. 2 G. P. Philip Ellis 

May 26 G. N. Challlce 

June 1 

»* 16 

«* 20 

** 22 *' 



4( 



(t 



(( 



8.13 
3.67 
8.58 
3.67 
4.04 
4.50 



8.2 


0.79 


4.5 


0.47 


46 


0.27 


45 


0.32 


60 


0.82 


99 


1.51 



2.6 
21 
12 
15 
49 
149 



Remarks. 



14 



210 



NICARAGUA CANAL COMMISSION 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO TIPITAPA AT TIPITAPA.— Continued. 



I 



I 



r: 



r 
II 



ii 



i: 



i; 



No. 


Dat«. 

1898. 




Hydrographer. 


Meter 
number. 


7 


June 27. . . . 


..G. 


N. Challlce 


. Ellis 


8 


July 1. . . . 




R. Wadlelgh . . . . . 

t( 


ti 


9 
10 


Aug. 18 

" 29.... 


..G. 


it 
it 


11 
12 


Sep. 5. . . . 
«* 10.... 




ti 


it 

it 


13 


** 12.... 




ti 


tt 


14 


" 13.... 




tt 


tt 


15 


»* 14.... 




it 


it 


10 


** 15.... 




tt 


it 


17 


" 16... 




tt 


it 


18 


»* 21 




tt 
it 
tt 

P. Philip . *. *. '. .' .* ! 

tt 


, it 


19 


" 26 




tt 


20 


u 28 




it 


21 
22 


Oct. 10.... 
*' 22.... 


..G. 


tt 
, tt 


28 


Nov. 2.... 




tt 


it 


24 


it 4 




tt 

tt 
tt 
ti 


tt 


25 


'* 9. . . . 




it 


26 


♦» 12 




tt 


27 


" 19.... 




tt 


28 


*' 23.... 




tt 


it 


29 


Dec. 2 




tt 


it 


80 


«* 6 




tt 

tt 


it 


81 


" 13 




tt 


32 


" 20.... 




tt 


, it 


83 


" 26.... 
1899. 




tt 


, tt 


34 


Jan. 1 




tt 


tt 


35 


" 7 




tt 


tt 


86 


** 10 




it 


tt 


37 


«* 20.... 




tt 


it 



Gage 

height 

(feet). 



Area of Mean ve- Disohargo 
section locity (feet (second- 
(square f t.). per second). feet). 



Remarks. 



4.81 


119 


5.40 


195 


5.27 


177 


5.60 


178 


5.85 


196 


5.98 


1,346 


6.23 


1,495 


6.44 


1,602 


6.58 


1,601 


6.74 


1,659 


6.94 


1,738 


7.18 


1,834 


7.18 


1,885 


7.36 


1,909 


7.40 


1,894 


7.94 


2,158 


7.92 


2,140 


7.82 


2,103 


7.69 


2,038 


7.53 


1,937 


7.42 


1,925 


7.25 


1,862 


7.08 


1,785 


6.85 


1,684 


6.70 


1,608 


6.52 


1,571 


6.38 


1,454 


6.22 


1,400 


6.08 


1,874 


6.03 


1,342 


5.75 


1,242 



1.98 


236 


8.43 


669 


3.38 


597 


4.75 


845 


6.61 


1,296 


0.84 


1,187 


0.98 


1,894 


1.11 


1,771 


1.19 


1,907 


1.27 


2,106 


1.88 


2,892 


1.55 


2,851 


1.62 


2,966 


1.71 


8,186 


1.71 


8,284 


2.40 


5,177 


2.29 


4,891 


2.25 


4,735 


2.12 


4,325 


1.85 


8,585 


1.79 


8,445 


1.66 


8,095 


1.57 


2,810 


1.46 


2,465 


1.86 


2,191 


1.24 


1,985 


1.17 


1,704 


1.07 


1,500 


1.00 


1,375 


0.98 


1,814 


0.81 


1,000 



1,500 strong wind up-stream. 

1,375 

1,814 

1,000 strong wind up-stream. 



RATING TABLE FOR RIO TIPITAPA AT TIPITAPA. 
This table is applicable only from February 1, 1898, to January 23, 1899. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. Second-feet. 


8.0 


1 




4.1 


61 


5.1 


410 


6.1 


1,860 




7.1 


2,630 


3.1 


2 




4.2 


79 


5.2 


495 


6.2 


1,470 




7.2 


2,810 


8.2 


4 




4.3 


96 


5.3 


580 


6.3 


1,580 




7.3 


3,010 


8.3 


6 




4.4 


116 


5.4 


670 


6.4 


1,690 




7.4 


8,280 


8.4 


8 




1.5 


137 


. 5.5 


760 


6.5 


1,800 




7.5 


3,500 


3.5 


10 




4.6 


162 


5.6 


850 


6.6 


1,920 




7.6 


3,800 


8.6 


13 




4.7 


195 


5.7 


950 


6.7 


2,050 




7.7 


4,130 


8.7 


18 




4.8 


230 


5.8 


1,050 


6.8 


2,180 




7.8 


4,500 


8.8 


25 




4.9 


280 


5.9 


1,150 


6.9 


2,320 




7.9 


4,900 


3.9 


84 




5.0 


340 


6.0 


1,250 


7.0 


2,470 




8.0 


5,800 


4.0 


46 


























ESTIMATED MONTHLY DISCHARGE OF RIO TIPITAPA AT TIPITAPA. 




Month. 


Discharge in Second-Feet. Total in 
Maximum. Minimum. Mean, ^^^^^^^' 


Month. 


Discharge in Second-Feet. ^ata\ in 
Maximum. Minimum. Mean. ^^"^^®®^ 


1898 














1898. 




Brought forward, 91,948 


February . 




125 


87 


77 


4,275 


September 


8,280 


910 


2,045 


121,690 


March .... 




36 


3 


16.6 


1,020 


October 


5,880 


2,910 


4,040 


248,410 


April 




4 





0.5 


29 


November 


5,500 


2,150 


3,640 


210,600 


May 




18 





3.8 


234 


December 


2,630 


1,470 


1,950 


119,900 


June 




700 


13 


121 


7,200 




1899. 


Total for 1898 








798,.548 


July 

August. . . 




922 
930 


280 
487 


662 
626 


40,700 
88,490 


January (1-23).. 


1,470 


950 


1,210 


.55,200 












91,948 




Total 








853,748 















APPENDIX m.— HYDROGRAPHIC REPORT 




Fio. 3. Diagram ot Daily Discbarge of Rio Tlpltapa, 1S98. 



Sas Ubaijm) ahd Mokbito. 
For the purpose of measuring evaporation 
and rainfall on the northeastern shore of Lake 
Xicaragua as well as recording its fluctuations, 
a station was estaWished at San Fbaldo on April 
0, 1898. This point was selected on account 
of the convenience of communication, it l>cing 
a regular stopping place for the " Victoria," a 
steamer plying between Granada and San Carlos. 
During the month of May, when adverse winds 
were frequent, the evaporation pan was fre- 
quently driven ashore, there being no means of 
protecting it at this point. This fact, together 
with the difficulty of obtaining suitable quarters 
for the obsener at this point, decided the re- 
moval of this station to Jlorrito, a native village 
about ten miles to the southeast. This removal 
was accomplished on ilay 24. The lake gage 
at San Ubaldo was connected by spirit level with 
two bench marks and with a point indicated by 
the inhabitants as being the high-water mark of 
1893, the highest stage known since the settle- 
ment at this point 



Bench mark Xo. 1 is the highest point of a 
large boulder ten feet north of the north door of 
the Bodega. It is 5.44 feet above the 9-ft, mark 
of the lake gage. 

Bench mark Xo. 2 is on top of the middle 
masonry support of tlio Bodega building. It is 
5,3 feet above tlic Oft. mark of the lake gage. 

The high-water mark of 1893 is 3,9 feet above 
the 9-ft, mark of the lake gage. Rainfall and 
evaporation obser\'ations were also taken at this 
station. 

At Jlorrito the gage was fastened to some 
stakes that had been standing in the mai^n of 
the lake for some years and were reasonably 
solid. Both it and the evai>oration pan were 
partially protected from breakers by a line of 
swamp grass growing in the lake outside of the 
water in which they stood. This station was 
discontinued on September 21. 

Station at Fort Sa\ Carlos. 

A gage was establi.ihed at this point by Lieut. 

Ilanus, r. S. N., Januarv 4, 1898. It was 



212 



NICARAGUA CANAL COMMISSION 



simply a graduated stick driven in the sand in 
shallow water and supported by two stakes in the 
form of braces. On March 13 a more substan- 
tial gage was placed in deeper water and firmly 
fastened to the iron remains of an old wreck of a 
Vandcrbilt steamer about a quarter of a mile 
north of the town of San Carlos. It was driven 
as far as possible into the mud and fastened with 
bolts and cable to the iron wreck. 

Bench mark Xo. 1 is on the highest point of 
the shore end of the stranded boiler and is 12. 



933 feet above the zero water gage last described 
and 9.78 feet above the zero of gage established 
by Lieut. Hanus. From the 8th of March, when 
a special observer was stationed at San Carlos, 
rainfall, evaporation, temperature and humidity 
observations were taken. 

On May 9th a gage was placed in Rio Frio 
about one mile above its mouth, upon which 
readings were taken every other day, and oc- 
casional measurements were made. 



DAILY ELEVATION OF LAKE NICARAGUA. 

Computed from gage-rod readings at Fort San Carlos, Jan. 4, 1898, to March 31, 1899; Las Lajas, Feb. 8, 1898, 
to March 31, 1899; Morrito, April 9, 1898, to Sept. 21, 1898; and Granada, Feb. 1, 1899, to March 31, 1899. 



18Q8. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sep. 


Oct. 


Nov. 


Doc. 


lovv. 

Jan. 


Feb. 


Mar. 


Day. 

A • • • • 


• . . « 


104.49 


103.86 


103.02 


102.29 


102.48 


103.50 


104.56 


104.96 


105.66 


106.41 


106.64 


106.31 


10.5.81 


105.13 


2... 


.... 


104.42 


103.89 


103.02 


102.24 


102.49 


108.47 


104.51 


104.97 


105.74 


106.37 


106.63 


106.30 


105.81 


105.00 


8 . . . . 


.... 


104.52 


103.82 


102.98 


102.23 


102.44 


103.55 


104.51 


104.95 


105.76 


106.31 


106.59 


106.29 


105.77 


104.99 


4.... 


104.92 


104.48 


103.86 


102.96 


102.21 


102.39 


103.70 


104.58 


104.94 


105.74 


106.26 


106.65 


106.22 


10.5.74 


105.00 


5 . . . . 


104.96 


104.51 


103.78 


102.92 


102.20 


102.42 


103.62 


104.61 


104.97 


106.75 


106.22 


106.67 


106.26 


105.71 


104.96 


6. . . . 


ia5.02 


104.48 


103.75 


102.96 


102.20 


102.45 


103.78 


104.57 


10.5.05 


105.73 


106.26 


106.62 


106.22 


10.5.72 


104.92 


7.... 


104.93 


104.43 


103.76 


102.92 


102.14 


102.52 


103.79 


104.60 


105.02 


105.75 


106.22 


106.04 


106.16 


105.70 


• • • • 


o • • • • 


104.94 


104.43 


108.78 


102.86 


102.12 


102.49 


103.82 


104.70 


105.05 


105.79 


106.19 


106.56 


106.22 


105.67 


104.95 


9. .. 


104.88 


104.42 


103.72 


102.83 


102.11 


102.48 


103.90 


104.67 


105.05 


105.73 


106.22 


106.55 


106.18 


105.63 


104.90 


10.... 


104.79 


104.32 


103.62 


102.77 


102.09 


102.48 


103.89 


104.65 


105.11 


ia5.73 


106.21 


106.68 


106.17 


105.60 


104.87 


11 


104.85 


104.30 


103.64 


102.81 


102.08 


102.48 


108.96 


104.65 


10.5.19 


105.71 


106.26 


106.57 


106.19 


105.64 


104.74 


12 


104.87 


104.81 


103.62 


102.81 


102.04 


102.54 


103.99 


104.59 


.105.29 


105.75 


106.84 


106.55 


106.15 


105.66 


104.73 


18 


104.80 


104.41 


103.61 


102.76 


101.96 


102.51 


103.98 


104.74 


105.44 


105.75 


106.46 


106.49 


106.14 


10.5.65 


104.67 


14.... 


104.76 


104.82 


103.52 


112.74 


102.03 


102.47 


10.3.98 


104.73 


105.45 


105.K4 


106.42 


106.49 


106.09 


10.5.57 


104.68 


15 


104.75 


104.29 


108.57 


102.69 


101.97 


102.48 


104.03 


104.78 


105.48 


105.. 88 


106.47 


106.47 


106.16 


105.52 


104.67 


16.... 


104.79 


104.23 


• • • • 


102.68 


102.05 


102.44 


104.07 


104.80 


10.5.. 53 


105.86 


106.50 


106..50 


106.09 


105.51 


104.70 


17 


104.78 


104.21 


• • • • 


102.68 


102.01 


102.47 


104.04 


104.83 


105.58 


105.92 


106.50 


106.44 


106.09 


105.46 


104.62 


18.... 


104.83 


104.21 


• « • • 


102.65 


102.13 


102.47 


104.07 


104.78 


105.57 


106.08 


106.57 


106.44 


106 13 


105.43 


104.61 


19.... 


104.84 


104.16 


103.26 


102.61 


102.10 


102.59 


104.10 


104.78 


10.5.57 


106.14 


106.51 


106.39 


106.13 


105.41 


104.49 


20 


104.97 


104.14 


108.30 


102.55 


102.11 


102.65 


104.25 


104.78 


105.58 


106.15 


106.44 


106.41 


106.15 


105.43 


104.65 


21 


104.90 


104.08 


103.33 


102.59 


102.15 


102.70 


104.17 


104.82 


105.65 


106.18 


106.62 


106.37 


106.06 


105.30 


104.51 


22.... 


104.82 


104.04 


108.14 


102. .56 


102.43 


102.91 


104.25 


104.83 


105.71 


106.24 


106.56 


106.82 


106.02 


105.26 


104.42 


28.... 


104.73 


104.00 


103.27 


102.53 


102.40 


102.97 


104.23 


104.77 


105.66 


106.28 


• ■ • • 


106.37 


105.96 


105.24 


104.45 


24... 


104.64 


104.08 


103.29 


102.45 


102.51 


103.01 


104.32 


104.80 


105.74 


106.36 


• • • • 


106.39 


105.92 


10.5.32 


104.37 


25 


104.71 


104.04 


103.30 


102.43 


102.57 


103.09 


104.33 


104.81 


105.72 


106.35 


• • • • 


106.85 


105.96 


105.18 


104.34 


26 


104.70 


104.06 


103. 99 


102.44 


102.. 55 


103.04 


104.35 


104.78 


105.68 


106.36 


106.54 


106.33 


105.94 


105.28 


104.82 


27 


104.69 


103.94 


103.19 


102.42 


102.59 


103.16 


104.39 


104.83 


105.63 


106.38 


106.59 


106.29 


105.89 


10.5.15 


104.25 


28 


104.07 


103.93 


103.12 


102.37 


102.56 


103.30 


104.46 


104.82 


105.74 


106.34 


106.62 


106.27 


105.86 


105.11 


104.26 


29.... 


104.52 


• • • • 


103.09 


102.33 


102.46 


103.42 


104.38 


104.94 


105.76 


106.44 


106.63 


106.38 


105.87 


• • • • 


104.25 


80 


104.64 


• • ■ • 


103.10 


102.32 


102.55 


103.47 


104.54 


104.95 


ia5.75 


106.41 


106.70 


106.37 


105.83 


• • ■ 


104.27 


31.... 


104.57 


• • • • 


102.97 


• • • • 


102.50 


• • • • 


104.51 


104.96 


• . . . 


106.38 


• • • t 


106.44 


105.85 


• • • • 


104.23 



APPENDIX III.— HYDROGRAPHIC REPORT 



213 



ESTIMATED MONTHLY FLOW INTO LAKE NICARAGUA IN EXCESS OF EVAPORATION. 

"""th- ^""^Xr"^ Ac^tcet outflow. TotaUnacn^ Inflow^.n 

189S. 

January, 4-31 Inclusive —666,400 + 1,032,400 +366,000 +6,590 

February —1,218,600 + 923,800 -2m,800 —5,310 

March -1,827,800 +863,600 —964,200 —15,680 

April —1,237,600 +724,100 —513,500 -8,630 

May +842,700 +723,300 +1,066,000 +17,340 

June +1,846,900 +841,600 +2,688,500 +45,200 

July +1,080,200 + 1,190,900 +3,171,100 +51,570 

August +856,800 +1,202,200 +2,050,000 +38,490 

September +1,504,200 + 1,313,600 +2,817,800 +47,350 

October + 1,199,500 +1,440,600 +2,640,100 +42,960 

November +609,300 +1,512,000 +2,121,300 +85,650 

December —495,000 + 1,540,000 + 1,045,000 + 16,990 

Total for 1898 + 16,202,300 

1899. 

January —1,128,400 + 1,443,100 +819,700 +5,300 

February — 1,409,000 + 1,154,600 —254,400 —4,580 

March - 1,680,500 + 1,103,700 —576,800 —9,880 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO FRIO ONE MILE ABOVE MOUTH. 



Date. Hy<In>Krapber. 


Meter 
Number. 


III 


Area of 
section 
(sq. ft). 


Moan ve- 
locity (ft. 
per. SCO.). 


Discharge, 
(second- 
feet). 


May 13 II. S. Reed 


St. 1 


2.63 


2,375 


0.51 


1,198 


'« 9 " 


1 
1 

1 
1 


2.50 
2.62 
2.93 
3.85 


2,414 
2,414 
2,519 
2,660 


0.54 
0.30 
0.74 
2.49 


1,802 


i* 15 »' 


787 


»« 21 *' 


1,871 


June 22 W. W. Schlecht 


6,626 


30.... 


1 


4.67 


2,928 


3.96 


11,600 


July 9 *' 


1 


4.90 


2,947 


3.74 


11,082 


" 23.... 


1 


5.10 


3,068 


3.84 


11,780 


" 29.... 


1 


5.20 


3,088 


2.40 


7,400 


** 23.... 


Floats. 


5.05 


3,060 


3.56 


10,885 


Aug. 6 *' 


St. 1 


5.25 


3,096 


2.48 


7,684 


" 19 '' ... 


1 


5.28 


3,096 


2.40 


7,445 


»* 31 E. P. Humphrey 


94 


5.44 


3,095 


1.36 


4,187 


Sept. 13 '' 


94 


5.80 


3,438 


1.45 


5,003 



Dry Season Inflow to Lake Nicaragua. 

For the purpose of determining the amount 
of storage necessary for maintaining the summit 
level of Lake Nicaragua at any desired point 
through the dry season, an attempt was made to 
measure the inflow to Lake Nicaragua during the 
months of April and !May 1898. This work 



was begun on April 19, and the following notes 
and measurements were made of its tributaries; 
Negro (?). — First river south of Rio Frio. 
Water black and foul. No current. Open 
water only about 300 yards above mouth. 
Above this entirely closed by grass. Width, 40 
to 200 feet; depth, 8 to 12 feet; discharge, zero. 



214 



NICARAGUA CANAL COMMISSION 



Another estuary exactly similar in all respects 
occurs one-fourth of a mile south, which may be 
another mouth of the same drainage. Both are 
almost due south of San Carlos. 

A third estuarv, wider and longer, but other- 



above mouth the channel is choked with vegeta- 
tion and becomes a swamp. 

West of this point occurred several streams 
with measurable discharge. Their character and 
volume are indicated in the following table: 



Date. 



April 19. 



April 20. 



April 21. 



May 15. 



Stream. 

Pisote, cast fork 

Pisote, west fork 

El Toro 

Las Haciendas, 1 mile up 

Oroci, near mouth 

Mena, % mile up 

Sabalo, near mouth 

Rio Pueblo, y^ mile ^P 

Tiroli, K mile up 

Sapoa, 2 miles up 

Frio, 2 miles up 

Total dry season inflow to Lake Nicaragua, southern end 



Ar<?a 
sec.-ft. 



550 
427 

78 

57 

47 

20 

2.3 

3.1 

102 

2,414 



Veloc. 
ft. i>er sec. 



Dis. 

8©C.~Xl» 



.82- 
.78 

1 oo 

.55 
.91 
1.70 
1.17 
.82 
.29 
.81 



452 
883 
No discharge. 
95 
88 
48 
84 
2.7 
1.8 
80 
737 



1,760 



wise similar, is one-half mile still farther south 
and has two branches, the southern and longer 
being two miles long. Water foul. Discharge, 
zero or nearlv so. 

Two other small estuaries were inspected 
farther south. 

CuoABACHO (?). — A wide-mouthed deep estu- 
ary about a mile southwest of the most south- 
erly described above. It has about a mile of 
open water. "So indication of current Water 
very black. Discharge, zero. 

One-half mile southwest of above occurs an 
estuary which is choked with vegetation one- 
fourth mile above its mouth. Discharge, zero. 

One-half mile southwest of above, a deep 
estuary closed with vegetation one-half mile 
above its mouth. Discharge, zero. 

Rio Arana. — Went up about one mile in 
canoe. Water deep and still. Water-lettuce and 
other plants standing on surface, not fastened, 
do not float out. Water stagnant and foul. All 
signs indicate absolutely still water. One mile 



Alligator. — Five miles north of San Carlos 
an estuaiy of stagnant water, 10 feet deep, 40 
feet wide. One-half mile above mouth it is 
choked with vegetation. Discharge, zero. 

CoNsuELO. — Large estuarj' with large delta 
and two mouths. Has about half a mile of open 
water; above this point closed by vegetation. 
Water stagnant. Discharge, zero. 

MuRiLLO. — Xorth of Point Murillo is an estu- 
arv w^hich forks about one-fourth mile above 

if 

mouth. Both forks ai'e closed by vegetation a 
short distance above their junction. Depth, 3 

to 7 feet. No measurable velocity. Total 

I.' 

discharge estimated at 10 second-feet. 

La Maria. — ^About two miles north of above 
is a short estuary of stagnant water. Discharge, 
zero. 

TuLE. — Large estuary, wide and deep. Much 
floating vegetation. No perceptible current. 
Discharge insignificant. 

Sax Miguelito. — An estuarv about a mile 
long occults two miles north of the town of San 



APPENDIX III— HYDROGRAPHIC REPORT 



215 



Migiielito, emptying into a sort of bay. It is 
shallow and has no measurable current. Dis- 
charge, zero. 

Rio Piedras. — A large deep estuary just 
north of above. It has two tributaries, one 
from the right and one from the left^ all deep 
and stagnant. Floating islands and plants in- 
dicate no current. Discharge, zero. 

Tepenaguasapa. — Large estuary with large 
delta. Depth 18 feet, width 50 feet. At time 
of inspection floating islands and other vegeta- 
tion, were moving upstream under the influence 
of wind. All indications point to stagnancy as 
in other streams. Discharge negligible. 

Ollate. — This river has a large deltaic forma- 
tion covered with aquatic vegetation, much of 
which is floating. At time of inspection it was 
choked with vegetation, there being no visible 
current. Discharge negligible. About one 
month later, on the 21st of June, a measurement 
was made about two miles above the mouth of 
the river. At this time the area of cross sec- 
tion at the point of measurement was 1079 
square feet, mean velocity 3.94 feet per second, 
discharge 4258 cubic feet per* second. 

Catabina RrvEB. — ^A large stream course ex- 
plored to a distance of about two miles. Depth 
10 to 15 feet; width about 100. No current. 
Information from natives and all indications de- 
note no discharge. 

AjocuAPA. — This river opens directly against 
the island of the Jobo group that lies nearest 
the shore. It has a large delta and is very shal- 
low. Much choked with floating vegetation. 
Discharge, zero. 



MoLLALEs. — When ascended. May 23, this 
river was stagnant from the mouth nearly to the 
point of measurement, what slight motion was 
shown being upstream. Descending it showed 
current nearlv all the wav down. This fact, 
and the rise of one-tenth foot which occurred 
at the point of measurement during inspection, 
indicate that most of the discharge is due to 
verv recent heavv rains. Measurements made 
4 miles above mouth. Total area Q^ square 
feet, mean velocity, .73, discharge, 49. 

EoBLADO. — This stream enters the lake at 
Guapinolapa. On May 24, the date of inspec- 
tion, it was choked with vegetation about 200 
feet above the point of measurement and gives 
other proofs of normal stagnancy. The dis- 
charge found is doubtless due to recent heavy 
rains. Total area of cross section, 25 square 
feet. Mean velocity, .77 feet per second; dis- 
charge, 19 second-feet. 

Xo other stream of measurable discharge was 
found flowing into the northern end of Lake 
Nicaragua. The coast bet^^^een Granada and 
Eivas was not explored. From the best informa- 
tion obtainable by inquiry it is concluded that the 
tributaries between these points contributed only 
an inconsiderable quantity of water at the close 
of the dry season. 

South of Rivas the Rio Medio was discharging 
early in May about one cubic foot per second. 

The mouth of Rio Las Lajas was closed in 
February and remained so until late in May. 
Several measurements were made in 1899, and 
are given below. 



216 



NICARAGUA CANAL COMMISSION 



LIST OF DISCHARGE MEASUREMENTS TO DETERMINE THE DRY-SEASON INFLOW TO LAKE 

NICARAGUA, 1899. 

Made by Alfred Ahrling and Fred. Davis. 



Date. 



Stream. 



Localit}'. 



Meter 
number. 



bei^t 
(ft.). 



Area of 

sec. (sq. 

ft). 



Mean ve- 
locity (ft. 
per aec.). 



Discharge 
(sec-ft.). 



Jan. 21. 
24. 
25. 
26. 
27. 
28. 
Feb. 1. 

2. 

8. 

4. 

5. 

6. 

6. 

6. 

6. 

6. 

7. 

7. 

7. 

8. 

8. 

8. 
10. 
11. 
18. 
13. 

18. 

14. 
14. 



" 15. 

" 15. 

" 18. 

'» 25. 

«• 26. 

»♦ 26. 

" 27. 

" 27. 

•» 28. 

*» 28. 

" 28. 
Mar. 1. 

•» 3. 

«» 3. 

»' 8. 



Tule 

Dilate 

Catarina 

Acoyapa 

Mollales 

Cangrejal 

Zapote 

Guacalita 

Pisote 

Haciendas .... 
MalacatoUa . . . 

Cafiitas 

Sardina 

Orocl 

Amapalo 

Tecolostate . . . 

Mena 

Sabalo 

Santa Clara . . . 

Tortuga 

Sapoa 

Poderoso 

Majaste 

Tepenaguasapa 

Camastra 

Gil Gonzales . . 

{Las Lajas * ) 
Ochomogo. / 

Cabeza 

Piedia 

Limon 

Medio 

Maria 

Murio 

Dilate 

Tule 

Zapote 

Tipitapa 

Pisote 

Haciendas .... 

Oroci 

Mena 

Sabalo 

Sapoa 

Gil Gonzalez. . 

Dchomogo 

MalacatoUa . . . 



Juan Mejia's Ranch . . 03 
Carraso^s Ranch 93 

Hate Grande 93 

Santa Rosa 7 

• • 

7 
7 
93 
7 
7 
7 



7 

7 

I • 

7 
7 



7 
Telegraph line 93 

• •••••• >• 

Station Pueblo Nueyo. 
Main Road 7 



Carraso's Ranch 93 3 

Mejia's Ranch 93 

Curameria's Ranch ... 93 5 

Under Bridge 1 4 

93 7 

Santo Tomas 93 4 

La Mina 93 

93 2 

93 2 

Pena Blanca 93 2 

bar across mou 

La Vulcan 93 

Tabacal 93 



9 



6 



8 



9 
60 



th. 



9 



661 
1246 



40 
251 

346 

115 
19.8 
12.4 
12.8 
79.6 



82.6 
66.4 

23.6 
250 

4.6 

180 



{ 



14.7 

5.8 
33.'J 

4.3 



195 

167 

245 

114 
84.7 
87.0 
23.5 

137 

85.0 
12.1 



0.40 


262 


0.18 


230 


• • • • 


00.0 


• • • • 


00.0 


0.90 


86.3 


• • • • 


00.0 


1.80 


453 


.... 


00.0 


2.04 


708 


1.63 


188 


1.81 


85.8 


0.84 


10.3 


0.72 


9.2 


1.17 


93.5 


• • • • 


00.0 


• • • • 


00.0 


1.66 


137 


1.23* 


82 


• • • • 


00.0 


0.66 


15.6 


0.49 


128 


• • • • 


00.0 


1.75 


8.0 


0.60 


109.0 


• • a • 


00.0 


0.97 


14.3 


1.27 


7.4 


1.56 


61.8 


1.00 


4.3 


• • • • 


00.0 


• • • • 


00.0 


• • • • 


00.0 


• • • • 


00.0 


• • • • 

• • • • 


00.0 


• • • • 

1.76 


342 


3.41 


569 


1.10 


270 


1.12 


127 


1.30 


45.2 


2.15 


79.7 


1.44 


33.8 


0.50 


69.4 


1.79 


62.9 


1.68 


20.2 



* This Las Lajas is a branch of the Gchomago. 



APPENDIX III.— HYDROGRAPHIC REPORT 



217 



LIST OF DISCHARGE MEASUREMENTS TO DETERMINE THE DRY-SEASON INFLOW TO LAKE 

NICARAGUA, 1899.— Continued. 



Date. 



Mar. 9. 



11. 
12. 
12. 
13. 
17. 
17. 
18. 
19. 
19. 
19. 
30, 
21. 
26. 
18. 



07 

Ml. 



April 4.» 



It 
ti 

(( 
11 

it 



7. 

8. 
11. 
13. 
15. 



Stream. 



Mollales 

Dilate 

Tepenaguasapa 

Frio 

Tule 

Zapote 

Haciendas .... 

Pisote 

Oroci 

Mena 

Sabalo 

Sapoa 

Ocbomogo .... 

Tipitapa 

Frio 

Frio 

Frio 

Malacatolla . . . 

MollaleB 

Dilate 

Tepenagaasapa 
Tule 



Locality. 



Meter 
number. 



Telegraph line 

Telegraph line 

Inocente 

Santo Tomas. . 



La Mina 

St. Emilio 

Pena Blanca 

La Vulcan 

Above Falls 

4 miles above mouth. 

5 miles above mouth 
.5 miles above mouth , 
Tabacal 



Carraso^s Ranch. 
Telegraph line . , 



c( 



t( 



93 

93 

«3 

1 

93 

93 

93 

93 

93 

93 

93 

93 

93 

93 

1 

1 

1 

93 



93 
93 



Gaffe 

height 

(ft). 



2.7 
1.1 
5.2 
0.2 
4.6 



1.2 
2.0 
1.8 
1.5 

• • • • 

4.68 
5.75 
4.75 
4.32 
0.70 



0.80 
-.30 



Area of 

sec. (sq. 

ft). 



17.0 



133.5 
2913 
42.0 
107 
107 
77.4 
25.9 
43.5 
18.5 
95.3 
36.8 
734 
2320 
1690 
1788 
18 



115 
26 



Mean ve- 
locity (ft. 
per sec). 



1.27 

• • • • 

0..52 
0.79 
0.81 
1.81 
1.10 
1.76 
1.43 
1.68 
1.68 
0.62 
1.46 
0.25 
0.79 
0.68 
0.74 
1.03 



0.45 
0.56 



DischarffQ 
(sec.-lt.). 



21.6 
00.0 
69.6 

2314 
84.1 
803 
118 
137 
37.0 
73.1 
31.1 
59.1 
53.9 
184.0 

1837 

1155 

1323 
18.6 
00.0 
00.0 
51.4 
14.6 



•Measurements from April 4 to April 15, inclusive, were made by Alfred Ahrllng and R. H. Morrln. 



Kid San Juan. 

The San Juan river is the sole outlet of Lake 
Nicaragua and its tributary drainage basin. Its 
total length from the lake to the sea is 122 miles 
and it is usually navigable for light-draught river 
steamers. It leaves the lake at Fort San Carlos 
at an altitude var^'ing from about 97 feet to 
about 110. Its course for a distance of 27 
miles is through a low swampy country relieved 
by occasional hills. Through this course the 
river is sluggish and receives several tributaries 
of small discharge, which, in the dry season, 
are practically still water. The principal of 
these are the Melchora, Medio Queso, Palo de 
Arco, and Kio Negro. The first tributary of 
importance to the San Juan river is the Rio 
Sabalos, which enters from the north and 
empties 27 miles east of Fort San Carlos. 



About half a mile below the mouth of the 
Sabalos are the first rapids, called Toro rapids. 
These rapids are caused by boulders and gravel, 
probably brought into the river by Rio Sabalos 
in former times, but do not seriously obstruct 
navigation except in times of extremely low 
water. Below this point the San Juan receives 
the waters of a few streams, the principal of 
which are the Rio Poco Sol and the Rio Santa 
Cruz. Ten miles below Toro rapids occur the 
largest rapids on the river, at Castillo Viejo. 
At this point the river falls about 5 feet in a few 
hundred feet, and steamers are seldom taken 
over the rapids except in high water. A rail- 
road about 2000 feet long is provided for the 
portage of freight and passengers on the right 
bank of the river. 

Below Castillo are the Diamond, Balas and 



218 



NICARAGUA CANAL COMMISSION 



Maclnica rapids, the latter being 12 miles from 
Castillo. All of these rapids admit the passage 
of river steamers except at extreme low water. 
Below Machiica there are no more rapids. The 
river is deep and sluggish for a distance of about 
15 miles to the point where it receives the waters 
and sediment of the Rio San Carlos. This river 
is the largest tributary of the San Juan, rising 
far to the southward in the mountains of Costa 
Rica, and bearing such a volume of sediment 
that a delta has been built up at its mouth and 
from this point to the sea the San Juan is a 
shallow stream with sandy shifting bed. Twenty- 
five miles farther down the Sarapiqui empties 
into the San Juan from Costa Rica, being the 
second tributarv in size to the San Carlos, and, 
like the latter, bearing large quantities of sedi- 
ment in times of flood. Eight miles below the 
mouth of the Sarapiqui the San Juan assumes 
decidedly the character of a deltaic stream and 
sends out a small distributary known as the San 
Juanillo, which meanders through the swamps 
to the northward and, after receiving the drain- 
age of the Deseado, re-enters the San Juan 4 
miles above its mouth. Five miles below the 
exit of the San Juanillo or 103 miles from Lake 
Nicaragua the main stream of the San Juan 
separates into two large distributaries, the 
larger, called the Rio Colorado, flowing eastv\-ard 
directly to the Caribbean, and the smaller, or 
lower San Juan, meandering to the northeast 
and finding its exit into the ocean at Greytown. 
Between the mouth of the Colorado and the 
lower San Juan another distributary, called the 
Rio Taura, finds its way from the lower San 
Juan to the sea. 

The principal obstructions to free navigation 
of light-draught river craft from Greytown to 
Fort San Carlos consist of the shoal character 



of the lower San Juan, especially in times of low 
water, and of the rapids lying between Machuca 
and the mouth of the Sabalos. For purposes of 
a ship canal the river also required deepening 
below the mouth of the San Carlos and between 
the Sabalos and Fort San Carlos. 

The only portion of the river which is suit- 
able in its present state for a ship canal is the 
part from !Machuca to a point a short distance 
above Boca San Carlos, or about 15 miles out of 
122, and even here some dredging must be done 
and two sharp bends eliminated to permit the 
safe passage of the largest ships. 

Sabalos Station ox San Juan River. 

The San Juan river is not well adapted in the 
vicinity of Fort San Carlos for making accurate 
measurements at all stages, the banks being low 
and swampy and subject to overflow at medium 
high stages. The first important tributary^ en- 
tering the river is Rio Sabalos which empties at 
the steamboat station which bears the same 
name. This is about half a mile above 
Tore rapids, which is the highest point at which 
it has even been proposed to dam the river 
to hold the lake at a high level. A gage was 
placed about half a mile above the mouth of the 
Sabalos on the 31st dav of December, 1897. It 

f 7 

consists of a vertical pine board driven into the 
river bed and spiked to a tree growing on the 
bank. The elevation of the zero of the gage 
rod is 90.85 feet above sea level. Measurements 
were made a short distance above the gage by 
means of a boat anchored in the stream, dis- 
tances being measured by stretching a tagged 
rope across the river. The discharge at this 
point is taken as being essentially the outflow 
from Lake Nicaragua. 



APPENDIX III.— HYDROGRAPHIC REPORT 



219 



DAILY GAGE HEIGHT OF SAN JUAN RIVER AT STATION SABALOS, ^ MILE ABOVE TORO 

RAPIDS, FOR 1898-9. 





























1809. 






1808. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sep. 


Oct. 


Nov. 


Dec. 


Jan. 


Feb. 


Mar. 


Day. 
1 


9.98 


9.58 


9.13 


8.56 


8.20 


8.33 


9.55 


9.84 


9.92 


10.48 


10.85 


11.28 


10.82 


10.32 


9.90 


•> 

M • . . . 


9.88 


9.52 


9.10 


8.56 


8.14 


8.39 


9.58 


9.85 


9.92 


10.59 


10.80 


11.38 


10.79 


10.31 


9.90 


3.... 


9.84 


9.49 


9.10 


8.52 


8.14 


8.38 


10.28 


9.90 


9.92 


10.47 


10.80 


11.23 


10.70 


10.29 


9.85 


4 


9.80 


9.49 


9.10 


8.55 


8.14 


8.30 


10.22 


• • • • 


9.91 


10.54 


10.75 


11.10 


10.71 


10.26 


9.85 


5 


9.80 


9.49 


9.04 


8.66 


8.08 


8.40 


9.90 


• ■ • • 


9.94 


10.53 


10.70 


11.00 


10.75 


10.22 


9.85 


6.... 


9.78 


9.49 


9.02 


8.67 


8.15 


8.41 


9.96 


• • • • 


10.10 


10.50 


10.70 


10.96 


10.75 


10.27 


9.80 


7 


9.78 


9.49 


9.00 


8.58 


8.10 


8.38 


9.62 


9.93 


10.10 


10.49 


10.65 


11.01 


10.74 


10.27 


9.75 


8 


9.78 


9.48 


8.99 


8.55 


8.16 


8.40 


9.62 


9.86 


10.13 


10.54 


10.65 


10.96 


10.71 


10.25 


9.70 


5.... 


9.78 


9.46 


9.00 


8.44 


8.11 


8.38 


9.64 


9.76 


10.14 


10.56 


10.70 


10.89 


10.73 


10.21 


9.70 


10 


9.78 


9.41 


9.00 


8.46 


8.10 


8.42 


9.74 


9.96 


10.14 


10.51 


10.80 


11.23 


10.79 


10.21 


9.65 


11 


9.79 


9.39 


9.00 


8.48 


8.11 


8.38 


9.72 


9.92 


11.19 


10.45 


10.80 


11.25 


10.77 


10.22 


9.65 


12.... 


9.80 


9.42 


9.00 


8.48 


8.15 


8.41 


9.65 


9.90 


10.68 


10.40 


11.00 


11.03 


10.83 


10.26 


9.65 


13.... 


9.80 


9.42 


9.00 


8.52 


8.04 


8.42 


9.62 


9.90 


10.78 


10.42 


11.60 


10.99 


10.84 


10.20 


9.65 


14.... 


9.74 


9.41 


8.98 


8.48 


8.10 


8.31 


9.63 


10.43 


10.52 


10.42 


11.45 


10.90 


10.76 


10.07 


9.65 


15 


9.73 


9.38 


8.96 


8.46 


8.08 


8.36 


9.60 


10.20 


10.51 


10.44 


11.10 


10.84 


10.96 


10.09 


9.60 


1(> 


9.73 


9.36 


8.90 


8.46 


8.06 


8.39 


9.50 


10.10 


11.17 


10.48 


11.30 


10.94 


10.78 


10.09 


9.60 


17.... 


9.73 


9.34 


8.81 


8.44 


8.10 


8.39 


9.50 


9.92 


10.64 


10.58 


12.10 


11.23 


10.75 


10.12 


9.55 


18 


9.73 


9.32 


8.76 


8.39 


8.36 


8.50 


9.62 


9.90 


10.44 


10.89 


11.55 


11.11 


10.71 


10.19 


9.55 


19 


9.73 


9.29 


8.74 


8.:i2 


8.39 


9.52 


10.50 


9.88 


10.38 


10.78 


11.20 


10.98 


10.64 


10.11 


9.60 


20.... 


9.73 


9.27 


8.68 


8.34 


8.31 


9.34 


10.66 


9.86 


10.40 


11.25 


11.10 


10.89 


10.59 


10.11 


9.60 


21 


9.75 


9.27 


8.75 


8.32 


8.38 


9.60 


10.16 


9.85 


10.49 


10.84 


11.00 


10.83 


10.57 


10.08 


9.55 


22.... 


9.74 


9.26 


8.74 


8.30 


8.56 


9.46 


9.96 


9.86 


10.52 


10.72 


11.00 


10.80 


10.58 


10.04 


9.55 


23.... 


9.68 


9.24 


8.68 


8.30 


8.39 


9.26 


10.04 


9.83 


10.55 


10.76 


11.00 


10.78 


10.56 


10.01 


9..50 


24 


9.62 


9.22 


8.76 


8.33 


8.50 


9.61 


9.91 


9.83 


10.51 


10.68 


10.95 


10.72 


10.54 


10.00 


9.45 


25.... 


9.62 


9.20 


8.76 


8.28 


8.50 


9.70 


9.81 


9.83 


10.48 


10.78 


11.00 


10.70 


10.50 


9.97 


9.45 


26.... 


9.60 


9.18 


8.68 


8.28 


8.58 


9.48 


9.91 


9.84 


10.43 


10.90 


11.05 


10.68 


10.45 


9.98 


9.45 


27.... 


9.60 


9.15 


8.70 


8.26 


8.57 


9.50 


9.79 


9.85 


10.65 


10. 82 


11.10 


10.63 


10.47 


9.95 


9.40 


28 


9.60 


9.14 


8.67 


8.26 


8.50 


9.34 


10.14 


9.84 


10.84 


10.75 


11.35 


10.07 


10.43 


9.90 


9.40 


29 


9.60 


• • • • 


8.62 


8.23 


8.45 


9.67 


9.96 


9.89 


10.55 


10.75 


11.45 


10.79 


10.41 


• • • • 


9.4^ 


30.... 


9.60 


• • • ■ 


8.62 


K.22 


8.46 


9.50 


10.64 


9.92 


10.55 


10.80 


11.10 


10.75 


10.39 


• • • • 


9.35 


31.... 


9.60 


• • • • 


8.55 


• • « • 


8.43 


■ • ■ • 


10.12 


9.92 


• • • • 


10.85 


• • • • 


10.81 


10.34 


• • • • 


9.40 



LIST OF DISCHARGE MEASUREMENTS MADE ON SAN JUAN RIVER AT STATION SABALOS. 



Date. 



Hydrogrrapher 



Meter 
numlK'r. 



Gage 
height 
(feet). 



Area of 
8ection 
(8<ir. ft.). 



Mean ve- 
locity (ft. 
per sec.). 



Disc*harge 
(second- 
feet). 



Remarks. 



1898. 






Jan. 21 R. 


C. Wheeler 


Feb. 2 




tt 


»' 21 




(( 


»♦ 25 




li 


Mar. 8 




t( 


8... 




11 


•» 16... 




(( 


»• 24... 


w 


. M. Barton 


•♦ 31... 




14 


April 8... 




i( 


♦' 11... 




(t 



B. &B. 1. 


9.75 


8,819 


2.16 


19,000 


Above 


Toro rapids. 




6.30 


9,417 


1.85 


17,360 


Below Toro rapids. 




9.27 


8,576 


1.92 


16,530 


Above Toro rapids. 




9.20 


9,726 


1.64 


16,000 


Above 


previous measurements 




9.10 


9,769 


1.58 


15,466 


Upper 


Station. 




9.00 


9,784 


1.51 


14,720 








8.tK) 


S),713 


1.48 


14,406 








3.70 


9,880 


1.43 


14,088 








8.60 


9,823 


1.35 


13,271 








8.60 


9,823 


1.30 


12,760 








8.50 


9,768 


1.30 


12,706 







220 



NICARAGUA CANAL COMMISSION 



LIST OF DISCHARGE MEASUREMENTS MADE ON SAN JUAN RIVER AT STATION SABALOS.— 

Continued. 



Date. 


Hydrographer. num^V 


Gage 
height 
(feet). 


Area of 

section 

(sqr. ft.). 


Mean ve- 
locity (ft 
per sec.) 


Dischaive 
. rsecond- 

feet). 


Remarks. 


1898. 














April 19... 


.W. M. Barton 1 


8.40 


9,776 


1.27 


12,466 


Upper Station. 


'* 25... 




8.80 


9,722 


1.22 


11,897 


tt 


" 29. . . 




8.20 


9,667 


1.22 


11,766 


tt 


May 10... 




8.10 


9,614 


1.20 


11,818 


it 


June 6... 




8.40 


9,776 


1.20 


11,706 


tt 


" 16... 




8.4C 


9,247 


1.23 


11,403 


tt 


" 20... 


. . ^ ' 


9.30 


9,783 


1.40 


13,660 


tt 


'* 26... 




9.50 


9,829 


1.53 


15,025 


tt 


July 18... 




9.60 


9,876 


1.72 


17,020 


tt 


Sept. 5. . . . 


.W. W. Schlecht Stk. 1 


9.92 


10,674 


1.94 


20,666 




" 11 .. 


it ^ ^ 1 


11.29 


11,273 


1.95 


21,995 


Probably back water by Sabalos. 


»» 14... 


14 ^ 1 


10.49 


10,684 


2.12 


22,678 


River falling. 


" 21.... 


.R. H. Morrin 1 


10.48 


10,720 


2.09 


22,481 


River -rising. 


Oct. 19... 


It \ 


10.79 


11,190 


2.19 


24,520 




" 26... 


it 1 


10.90 


10,975 


2.18 


23,914 




Nov. 9. . . 


tt 1^ 


10.66 


10,864 


2.20 


23,965 




♦♦ 17.... 


tt 1 


12.21 


11,816 


2.16 


25,550 




»* 28..., 


tt \ 


10.99 


11,148 


2.25 


25,110 




Dec. 3... 


tt j^ 


11.28 


11,273 


2.39 


26,700 




" 13.... 


it \ 


10.99 


10,«72 


2.82 


25,500 




" 23..., 


tt ..... 1 


10.78 


10,862 


2.28 


24,775 




1899. 














Jan. 2. . . . 


tt 1 


10.80 


10,936 


2. 13 


23,880 




" 14..., 


tt 1 


10.78 


10,979 


2.22 


24,880 




Feb. 2 


tt \ 


10.81 


10,603 


2.05 


21,714 




" 15.... 


tt 1 


10.09 


10,208 


2.00 


20,870 




»» 23. . . . 


tt \ 


10.01 


10,802 


2.02 


20,810 




Mar. 1 


8. WilBon 1 


9.90 


10,145 


1.85 


18,770 




i« 14 


ft .... . 1 


9.65 
9.47 


10,204 
10,010 


1.78 
1.76 


18,172 
17,576 




" 24 


it .... 1 











RATING TABLE FOR SAN JUAN RIVER AT STATION SABALOS. 
This table is applicable only from January 1, 1898, to March 31, 1899. 



Gage 
height. 


Discharge. 


Gage 

hel^t. 


Discharge. 


heS^t. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Feet. 


Second-foot. 


8.0 


11,130 


8.8 


18,680 


9.6 


17,890 


10.4 


22,180 


11.2 


26,870 


8.1 


11,820 


8.9 


14,180 


9.7 


18,420 


10.5 


22,660 


11.8 


26,900 


8.2 


11,580 


9.0 


14,710 


9.8 


18,950 


10.6 


23,190 


11.4 


27,480 


8.8 


11,760 


9.1 


15,240 


9.9 


19,480 


10.7 


28,720 


11.5 


27,960 


8.4 


12,040 


9.2 


15,770 


10.0 


20,010 


10.8 


24,250 


11.6 


28,490 


8.5 


12,880 


9.8 


16,800 


10.1 


20,540 


10.9 


24,780 


11.7 


29,020 


8.6 


12,760 


9.4 


16,880 


10.2 


21,070 


11.0 


25,310 


11.8 


29,550 


8.7 


18,200 


9.5 


17,360 


10.3 


21,600 


11.1 


25,840 


11.9 


80,080 



APPENDIX III.— HYDROGRAPHIC REPORT 



221 



ESTIMATED MONTHLY DISCHARGE OF SAN JUAN RIVER AT STATION SABALOS. 



Month. 



Discharge in Second- Feet. Total in 



Maximum. Minimum. Mean. '^*^"^^^®^ 



Month. 



Discharge in Second-Feet. Total In 
Maximum. Minimum. Mean. Acre-Feet. 



1898. 

January 19,900 

February 17,780 

March 15,400 

April 18,070 

May 12,680 

June 18,420 

July 23,510 

August 22,290 

September . . . 26,210 



17,890 


18,590 


1,148,055 


15,480 


16,683 


923,750 


12,570 


14,045 


868,595 


11,580 


12,169 


724,105 


11,206 


11,763 


728,275 


11,760 


14,144 


841,625 


17,860 


19,369 


1,190,985 


19,110 


19,552 


1,202,200 


19,533 


22,075 


1,818,550 



8,926,090 



1898. 

October 26,630 

November . . . 28,490 
December . . . 27,820 

Total for 1898. . . 



Brought forward, 8,926,090 
22,180 23,430 1,440,650 
28,450 25,410 1,512,000 
24,000 25,050 1,540,260 

18,419,000 



1899. 

January 25,100 

February 21,720 

March 19,480 



21,810 23,470 1,448,120 
19,480 20,790 1,154,620 
16,560 17,950 1,108,700 



ELEVATION OF LAKE NICARAGUA IF ALL WATER HAD BEEN HELD BY A DAM AT 

SABALOS, 1898-9. 



' 1898. 


Jan. 


Feb. 
105.11 


Mar. 


April. 


May. 


4 

June. 


Jul}'. 


Aug. 


Sept. 


Oct. 


Nov. 


Doc. 


Jan. 


Feb. 


Mar. 


Day. 

X . . . . 


104.94 


104.96 


104.57 


104.23 


104.79 


106.26 


107.94 


108.97 


110.37 


111.88 


112.90 


113.38 


113.64 


113.55 


2 


104.96 


105.06 


105.01 


104.59 


104.19 


104.81 


106.25 


107.91 


109.00 


110.47 


111.86 


112.92 


113.40 


113.66 


113.44 


8. . . . 


104.98 


105.18 


104.95 


104.57 


104.19 


104.77 


106.85 


107.93 


109.00 


110.52 


111.83 


112.91 


113.42 


118.64 


118.45 


4.... 


105.00 


105.15 


105.01 


104.56 


104.18 


104.78 


106.52 


108.02 


109.01 


110.52 


111.80 


113.00 


113.37 


118.63 


118.48 


5.... 


105.06 


105.20 


104.94 


104.53 


104.19 


104.78 


106.46 


108.07 


109.06 


110.55 


111.78 


118.04 


113.43 


113.68 


113.46 


6. . . . 


105.14 


105.14 


104.93 


104.59 


104.20 


104.82 


106.64 


108.05 


109.16 


110.56 


111.85 


118.02 


113.42 


113.66 


113.44 


7.... 


105.07 


105.16 


104.95 


104.56 


104.15 


104.90 


106.67 


108.10 


109.15 


110.60 


111.83 


113.07 


113.38 


113.66 


• • • • 


8.... 


105.10 


105.18 


104.94 


104.51 


104.14 


104.88 


106.72 


108.22 


109.20 


110.66 


111.82 


113.01 


113.46 


118.65 


118.51 


(T . . . . 


105.06 105.19 


104.94 


104.49 


104.14 


104.89 


106.82 


108.21 


109.22 


110.63 


111.88 


113.03 


113.45 


113.63 


113.48 


10 


105.00 


105.10 


104.86 


104.44 


104.18 


104.91 


106.88 


108.21 


109.30 


110.66 


111.90 


113.09 


113.47 


118.63 


113.47 


11 


105.08 


105.10 


104.89 


104.50 


104.14 


104.92 


106.92 


108.28 


109.41 


110.66 


111.97 


113.11 


113.51 


113.69 


113.86 


12.... 


105.11 


105.18 


104.90 


104.51 


104.11 


104.99 


106.97 


108.20 


109.54 


110.73 


112.07 


118.11 


113.50 


113.78 


113.37 


13.... 


105.06 


105.^4 


104.90 


104.48 


104.04 


104.97 


106.98 


108.37 


109.72 


110.75 


112.22 


113.08 


113.51 


113.74 


113.33 


14.... 


105.04 


105.17 


104.83 


104.47 


104.12 


104.94 


107.00 


108.88 


109.75 


110.86 


112.21 


113.11 


113.48 


113.68 


118.36 


15.... 


105.05 


105.16 


104.89 


104.43 


104.07 


104.97 


107.07 


108.45 


109.80 


110.92 


112.29 


113.11 


113.57 


113.66 


113.37 


16.... 


105.11 


105.11 


104.82 


104.44 


104.16 


104.94 


107.18 


108.49 


109.88 


110.92 


112.3$ 


113.17 


113.52 


113.67 


113.42 


17.... 


105.13 


105.11 


104.77 


104.45 


104.13 


104.98 


107.12 


108.54 


109.96 


111.01 


112.38 


113.14 


113.55 


113.64 


113.36 


18.... 


105.19 


105.13 


104.71 


104.43 


104.26 


104.99 


107.17 


108.51 


109.97 


111.20 


112.48 


113.17 


118.62 


113.63 


113.36 


19.... 


105.22 


105.10 


104.64 


104.40 


104.24 


105.13 


107.22 


108.53 


109.99 


111.28 


112.44 


113.14 


118.64 


113.63 


113.26 


20. . . . 


105.37 


105.10 


104.69 


104.35 


104.27 


105.20 


107.39 


108.55 


110.02 


111.82 


112.40 


113.19 


113.69 


113.67 


113.84 


21.... 


105.82 


105.05 


104.74 


104.41 


104.32 


105.27 


107.83 


108.61 


110.11 


111.33 


112.60 


113.17 


113.63 


113.56 


113.32 


22.... 


105.25 


105.03 


104.56 


104.39 


104.62 


105.50 


107.43 


108.64 


110.20 


111.46 


112.58 


113.14 


113.62 


113.54 


113.25 


23.... 


105.18 


105.00 


104.70 


104.37 


104.60 


105.58 


107.43 


108.60 


110.17 


111.52 


112.60 


113.22 


113.57 


113.54 


113.29 


24.... 


105.11 


105.10 


104.74 


104.30 


104.72 


105.64 


107.54 


108.65 


110.28 


111.63 


112.62 


113.26 


113.56 


113.64 


113.28 


25.... 


105.20 


105.07 


104.76 


104.29 


104.80 


105.74 


107.57 


108.68 


110.28 


111.65 


112.64 


113.24 


113.63 


113.52 


118.22 


26.... 


105.21 


105.11 


104.46 


104.32 


104.79 


105.71 


107.61 


108.67 


110.26 


111.68 


112.66 


113.25 


113.63 


113.64 


113.22 


27 


105.22 


105.01 


104.68 


104.31 


104.85 


105.85 


107.67 


108.74 


110.24 


111.72 


112.74 


113 23 


113.60 


113.53 


113.16 


US.,,, 


105.22 


105.01 


104.62 


104.27 


104.88 


106.01 


107.76 


108.75 


110.38 


111.71 


112.80 


113.23 


113.60 


113.51 


113.19 


29.... 


105.09 


• • • • 


104.60 


104.24 


104.74 


106.15 


107.70 


108.89 


110.42 


111.83 


112.84 


113.37 


113.63 


• • • • 


113.20 


80.... 


105.22 


• • • • 


104.63 


104.24 


104.84 


106. yi 


107.88 


108.92 


110.43 


111.82 


112.93 


113.38 


113.62 


• • • • 


113.28 


81.... 


105.17 


• • • • 


104.51 


. . * • 


104.80 


.... 


107.87 


108.95 


• • ■ ■ 


11L82 


• • • • 


113.48 


113.65 


• ■ • • 


118.21 



222 



NICARAGUA CANAL COMMISSION 



Rio Sabalos. 

Occasional measurements of the Sabalos river 

were made by the same observer employed upon 

the San Juan at Sabalos. A gage was placed 

in this river about three miles above its mouth, 



but at certain times the river became so slug- 
gish at this point as to be difficult to measure. 
On April 23 the rod was moved one mile farther 
up the stream. The following measurements 
were made of this stream. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO SABALOS 1% MILES ABOVE ITS MOUTH. 



Date. Hydrogrrapher. 


Meter .^Jg®. 


Area of 

section 

(sq. feet). 


Mean ve- 
locity (feet 


Discharge 
(second- 
feet). 


Remarks. 


1898. 












Jan. 24 R. C. Wheeler 


1 6.00 


1,004 


0.29 


291 




Feb. 22 •* 


1 5.60 


960 


0.16 


152 


Velocity too low for accuracy. 


"22 '* 


1 5.60 


14^ 


0.96 


186 


Taken 1 mile above gage. 


Avlsira ^ • % • • •••• 


1 5.41 


183 


0.99 


131 




•* 17 '♦ 


1 5.20 


105 


0.82 


86 




♦* 25 W. M. Barton 


1 5.12 


108 


1.34 


145 




April 1 " 


1 4.98 


81 


0.91 


74 




'» 9 •' 


1 4.85 


88 


1.42 


125 




i( A ti 

Vb««« •••• 


1 4.80 


77 


1.09 


84 




♦* 23 »» 


1 8.20 


71 


1.00 


71 


New rod 8.20=4.70. 


»» 30 »' 


1 8.10 


66 


1.11 


78 




May 6 »' .... 


1 3.07 


62 


1.05 


65 




"22.... 


1 5.15 


444 


1.88 


812 


Not the regular section. 


"27 " 


1 3.50 


82 


1.38 


118 




June 4.... " .... 


1 8.31 


67 


1.24 


88 




It 11 tt 


1 3.70 


99 


2.56 


254 




CI 1g tl 


1 3.47 


69 


1.40 


97 




"27.... " 


1 6.19 


595 


2.09 


1,246 




July 2 " 


1 6.10 


618 


1.89 


1,158 




" 14 " 


1 5.15 


448 


1.50 


669 




Sept. 7 W. W. Schlecht. . . 


Stk. 1 5.18 


426 


0.79 


338 




" 15 " 


1 6.03 


596 


1.56 


928 


River falling. 


" 23 R. H. Morrin 


1 5.71 


568 


1.26 


719 


River rising. 


Oct. 11 " 




1 5.18 
1 5.93 


476 
581 


0.44 
1.15 


213 
669 




" 27 " 






Nov. 11.... " 




1 5.81 


528 


1.09 


579 




" 15 " 




1 6.49 


622 


1.62 


1,007 




" 22 " 




1 5.92 


586 


0.95 


509 




" 29 " 




1 7.70 


731 


2.49 


1,818 




Dec. 5 " 




1 5.90 


552 


0.97 


588 




" 12 




1 6.12 


572 


1.37 


783 




" 19 " 




1 6.00 


545 


1.12 


612 




1899. 














Jan. 3 R. H. Morrin. 




1 5.69 


510 


1.05 


585 




" 19.... 




1 5.51 


467 


0.85 


896 




Feb. 4 " 




1 4.98 


386 


0.28 


95 




" 14 " 




1 4.81 


854 


0.86 


124 




" 21 




1 4.85 


340 


0.53 


181 




" 25 " 




1 4.68 


820 


0.24 


77 




Mar. « 8. Wilson. . . 




1 4.55 
1 4.80 
1 4.13 


311 

110 

173 


0.24 
0.90 
0.42 


76 

100 

76 


3 miles above mouth. 


" 21 ... . " 




4 it i( (i 


" 31.... " .... 




3 (» li u 







APPENDIX III.— HYDROGRAPHIC REPORT 



223 



Castillo Station on San Juan River. 

Two gages were placed in the San Juan 
river at Castillo, one above the falls and one 
below. The upper gage was fastened to the 
downstream support of the first building below 
the steamboat wharf above the rapids. The 
lower gage was fastened to the northeast corner 



of the wharf at the lower Bodega below the 
rapids. The zero of the upper gage is 5.65 feet 
above the zero of the lower. Mr. John S. 
Augustine, the agent at Castillo, was employed 
to read the gages, daily readings being taken of 
both. He also kept a record of rainfall. 



DAILY GAGE HEIGHT OF SAN JUAN RIVER AT CASTILLO ABOVE FALLS FOR 1898-9. 









1 


















1899. 






1896. 


Jan. 


Feb. 
3.10 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sep. 


Oct, 


Nov. 


Dec. 


Jan. 


Feb. 


Mar. 


Day. 
1 


• • • • 


2.60 


• • • • 


2.00 


2.20 


4.00 


3.60 


3.20 


3.75 


3.90 


4.50 


3.80 


3.50 


8.10 


2.... 


• • • • 


3.10 


• « • • 


• • • • 


2.00 


2.20 


3.80 


3.50 


8.20 


4.10 


3.90 


4.65 


3.80 


8.50 


3.10 


t$ • • • • 


• • • • 


• • • • 


• • * * 


• • • • 


1.95 


2.20 


5.50 


8.60 


3.20 


4.00 


3.90 


4.40 


8.80 


8.50 


8.10 


4.... 


• • • • 


• • • • 


• • • • 


2.20 


1.95 


2.00 


4.60 


3.45 


3.20 


4.00 


3.80 


4.30 


3.90 


3.50 


3.00 


o • • • • 


• * • • 


• • • • 


• • • • 


2.50 


1.95 


2.00 


4.30 


3.55 


3.25 


4.00 


3.80 


4.10 


4.00 


8.40 


3.00 


0. . . . 


• • • • 


3.15 


• • • • 


2.85 


1.95 


1.90 


3.80 


3.80 


3.30 


4.00 


3.70 


4.10 


4.30 


8.40 


8.00 


7.... 


• ■ • • 


• • • • 


2.50 


2.65 


1.95 


1.90 


3.60 


3.60 


3.80 


• • • • 


3.70 


4.10 


4.20 


8.40 


3.00 


o • • . • 


• • • « 


3.10 


2.40 


2.60 


1.90 


2.00 


3.60 


3.50 


3.10 


• • • • 


3.70 


4.10 


4.20 


3.30 


8.00 


«'•••• 


.... 


• • • « 




2.60 


1.90 


2.35 


3.80 


3.50 


3.20 


3.80 


3.60 


4.20 


4.90 


8.30 


2.90 


10 


• • • • 


• • • • 




2.40 


1.90 


2.35 


8.75 


3.50 


3.45 


3.80 


3.90 


4.20 


4.30 


8.80 


2.90 


11.... 


• • • t 


• • • • 




2.40 


2.06 


2.35 


3.70 


3.45 


5.80 


8.70 


8.90 


4.30 


4.10 


3.30 


2.90 


12 


3.20 


• • • • 




2.30 


2.03 


2.35 


3.60 


3.60 


4.30 


3.70 


4.10 


4.30 


5.00 


3.50 


2.90 


13 


3.20 


• • ■ • 




2.27 


2.00 


2.30 


3.75 


3.40 


4.45 


3.70 


5.80 


4.15 


5.00 


8.50 


2.90 


14.... 


3.20 


2.90 

• 




2.25 


2.00 


2.20 


3.60 


4.60 


4.00 


3.70 


4.80 


4.10 


4.80 


8.50 


2.90 


15.... 


3.20 


2.90 




2.20 


2.00 


2.25 


3.60 


4.00 


4.00 


3.70 


4.30 


4.00 


4.20 


3.50 


2.90 


16.... 


3.30 


■ • • • 




2.15 


2.00 


2.30 


3.45 


3.65 


5.40 


3.70 


4.30 


4.00 


4.00 


3.40 


3.80 


17 


3.30 


2.87 


2.40 


2.15 


2.00 


2.20 


3.40 


3.60 


4.30 


8.75 


6.20 


4.90 


4.10 


8.30 


3.80 


18.... 


3.30 


• • • • 




2.15 


2.00 


2.20 


3.50 


3.40 


4.20 


8.80 


5.00 


4.50 


4.00 


3.30 


8.80 


10.... 


3.30 


2.85 




2.15 


2.50 


4.10 


4.30 


3.30 


4.00 


4.80 


4.70 


4.10 


3.80 


3.80 


2.80 


20.... 


3.30 


• • • • 




2.05 


2.40 


4.15 


4.00 


3.30 


3.95 


4.60 


4.60 


4.00 


3.80 


3.20 


2.90 


21.... 


3.30 


• • • • 




2.10* 


2.25 


4.45 


4.05 


3.30 


3.95 


4.60 


4.50 


4.00 


8.70 


3.20 


2.90 


22.... 


3.30 


• • • • 




2.05 


2.60 


4.30 


4.00 


3.30 


3.90 


4.10 


4.50 


3.85 


3.70 


3.20 


2.90 


23.... 


3.20 


• • • • 




• • • • 


2.45 


3.40 


3.90 


3.30 


4.35 


4.10 


4.30 


8.85 


3.70 


3.30 


2.90 


24.... 


• • • • 


• • ■ • 




• • • • 


2.35 


4.90 


3.60 


3.30 


4.00 


4.10 


4.20 


8.80 


3.80 


3.30 


2.90 


25. . . . 


• • • • 


• • • • 




• • • • 


2.30 


4.50 


3.60 


3.30 


3.95 


4.10 


4.20 


3.70 


8.80 


3.30 


2.90 


26.... 


3.20 


• 

.... 


• • • • 


• • • • 


2.35 


3.70 


3.70 


3.30 


4.00 


4.40 


4.20 


3.70 


3.80 


3.80 


2.80 


27.... 


3.20 


• • • • 


2.40 


2.00 


2.35 


3.65 


3.55 


3.80 


4.00 


4.00 


4.20 


8.90 


8.80 


3.30 


2.80 


28.... 


3.10 


2.70 


2.40 


• • • • 


2.35 


3.50 


4.30 


8.20 


• • • • 


4.00 


4.80 


3.80 


3.70 


8.00 


2.80 


29.... 


3.10 


• • • • 


• • • • 


• • • • 


2.20 


4.10 


4.20 


8.20 


3.90 


3.90 


4.80 


4.00 


8.70 


• • • • 


2.80 


30 


3.10 


• • • • 


• • • • 


2.00 


2.20 


3.70 


4.00 


3.15 


3.85 


8.90 


4.40 


• • • • 


3.70 


• « • • 


2.80 


81 


3.10 


• • • • 


• • • • 


• • • • 


2.20 


• • • • 


4.00 


3.15 


• • • • 


3.90 


• • • 


• • • • 


8..50 


• • • • 


2.80 



224 



NICARAGUA CANAL COMMISSION 



DAILY GAGE HEIGHT OF SAN JUAN RIVER AT CASTILLO BELOW FALLS FOR 1898. 



1898. 


Jan. 


Feb. 


Mar.. 


April. 


May. 


June. 


July. 


Aug*. 


Sept. 


Oct. 


Nov. 


Dec. 


1899. 
Jan. 


Feb. 


Mar. 


Day. 




3.80 
3.80 
3.80 
3.80 
3.90 

3.90 
.1.80 
3.80 
3.80 
3.70 

3.60 
3.60 
3.40 
3.50 


3.20 
3.10 


2.45 


2.10 
2.10 
2.00 
2.00 
2.00 

2.00 
2.00 
1.75 
1.75 
1.75 

1.75 
3.03 
3.00 
1.90 
1.90 

1.90 
1.90 
2.00 
2.50 
2.80 

2.50 
2.80 
2.60 
2.55 
2.55 

2.55 
2.55 
2.55 
2.45 
2.40 
2.40 


2.40 
2.40 
2.40 
2.26 
2.20 

2.10 
2.10 
2.10 
2.70 
2.70 

2.75 
2.70 
2.60 
2.40 
2.45 

2.50 
2.40 
2.40 
5.55 
5.50 

6.10 
5.00 
4.40 
5.75 
6.28 

4.95 
4.05 
4.30 
5.10 

4.82 


4.82 
5.65 
6.00 
6.10 
5.50 

5.00 
4.80 
4.65 
6.00 
4. IK) 

4.90 
4.00 
4.80 
4.60 
4.50 

4.30 
4.40 
4.40 
5.65 
5.50 

5.65 
5.40 
5.00 
4.80 
4.60 

4.80 
4.40 
5.85 
6.60 
6.50 
6.00 


4.40 
4.30 
4.60 
4.50 
4.50 

4.90 
4.60 
4.50 
4.30 
4.30 

4.30 
4.40 
4.20 
5.55 
5.00 

4.80 
4.60 
4.40 
4.30 
4.30 

4.00 
4.20 
4.20 
4.10 
4.15 

4.05 
4.05 
4.05 
4.00 
4.00 
4.00 


4.10 
4.10 
4.10 
4.15 
4.25 

4.60 
4.50 
4.00 
4.45 
4.50 

5.60' 
6.10 
5.50 
5.80 

5.58 
5.50 
5.30 
5.30 

5.45 
5.40 
6.00 
5.40 
5.20 

5.30 
5.30 

"5.26* 
5.00 


4.90 
5.50 
5.20 
5.20 
5.10 

6.10 

5.00 
4.80 

4.70 
4.60 
4.60 
4.70 
4.70 

4.70 
4.80 
6.00 
over-all 
6.50 

6.10 
5.60 
5.60 
5.60 
5.60 

5.90 
5.40 
5.40 
5.40 
5.40 
5.40 


5.40 
6.40 
6.40 
6.80 
5.00 

5.00 
5.00 
6.00 
4.90 
6.10 

5.10 
5.60 
over-all 
6.60 
5.90 

6.00 

over-all 

over-all 

6.35 

6.30 

6.20 
6.10 
6.90 
6.70 
5.60 

5.60 
6.65 
6.70 
6.70 
5.60 


6.30 
6.50 
6.00 
5.80 
5.50 

6.30 
5.30 
5.30 
5.40 
6.40 

5.60 
6.60 
5.40 
5.30 
5.10 

5.10 
6.80 
6.30 
5.46 
6.20 

6.10 
5.05 
6.00 
5.00 
4.90 

4.90 
5.05 
6.05 
6.30 


5.00 
5.00 
5.00 
5.15 
5.25 

5.45 
5.30 
5.80 
5.60 
5.60 

5.45 
6.85 
6.30 
6.20 
6.85 

6.00 
5.40 
5.«5 
5.00 
5.00 

4.20 
4.25 
4.85 
4.80 
4.80 

4.80 
4.80 
4.76 
4.75 
4.70 
4.50 


4.60 
4.50 
4.50 
4.50 
4.40 

4.40 
4.40 
4.35 
4.35 
4.82 

4.82 
4.42 
4.60 
4.60 
4.60 

4.40 
4.36 
4.30 
4.25 
4.20 

4.20 
4.20 
4.20 
4.80 
4.80 

4.80 
4.26 
4.00 

• • • . • • 


8.90 


«6. • • • 

O ■ • • • 




3.90 
3.90 


4 








8.80 


O • • • • 


'*3*.66 


3.35 

3.50 
3.10 
3.00 
2.80 


3.80 


6 

7.... 




3.80 
8.80 
3.70 


y.... 
10 




8.70 
3.70 


11 




3.70 


12 

13 

14 

15 


4.40 
4.40 
4.10 
4.10 

4.00 
3.90 
4.00 
4.10 
4.00 

4.20 
4.30 
4.10 
4.00 
3.90 

8.90 
4.20 
4.00 
4.00 
3.90 
3.90 


2.95 
2.90 


2.70 
2.60 
2.50 
2.45 

2.35 
2.30 


8.70 
8.70 
3.70 
8.70 


16 






8.60 


17.... 

1« 

1».... 
20 


3.40 
3.35 


2.85 
2.80 


3.62 
8.50 
8.50 
3.50 


21 


3.30 






3.50 


22 




2.25 


3.60 


23.... 
24 




2.75 


3.50 
3.50 


25 








3.40 


26 








3.40 


27.... 
28 


3.20 


2.70 


2.20 


3.40 
3.45 


29. . . . 
30.... 
31.... 




2.65 
2.60 
2.60 


2.10 ' 


3.40 
8.40 
3.40 



ESTIMATED MONTHLY DISCHARGE OF SAN JUAN RIVER ABOVE THE MOUTH OF THE 

SAN CARLOS. 

This is obtained by subtracting the discharge of the San Carlos from that of the San Juan at Ochoa. 



Month. 



Discharge in Second-Feet. Total In 



Maximum. Minimum. Mean. '^*^'^^^®*- 



Month. 



Discharge in Second-Feet. Total In 
Maximum. Minimum. Meain. ^^*^^®®*^- 



1898. 

January (10-81) 23,270 19,500 21,030 

February 34,000 18,500 22,080 

March 22,000 14,600 16,850 

April 25,800 12,900 15,120 

May 19,200 11,700 14,180 

June 39,200 13,000 22,410 

July 43,100 26,200 82,720 

August 38,400 23,000 26,170 

September 41,800 22,800 29,210 



917,650 
1,226,260 
1,036,070 
899,700 
868,820 
1,383,600 
2,011,870 
1,609,130 
1,738,120 



1898. Brought forward, 11,641,120 

October 37,600 24,700 29,820 1,802,820 

November 70,500 26,800 86,460 2,169,.520 

December 41,800 26,800 81,670 1,941,160 

Total 17,554,620 

1899. 

January 38,900 26,300 31,800 1,955,300 

February 28,200 23,100 25,180 1,398,430 

March 23,100 19,600 21,540 1,324,460 



11,641,120 



APPENDIX III— HYDROGRAPHIC REPORT 



ESTIMATED MONTHLY DISCHARGE OF TRIBUTARIES TO SAN JUAN RIVER BETWEEN 

SABALOS AND SAN CARLOS RIVERS. 

Tbls Is the difference between tbe discharge ot the Saa Juan above Boca Sap Carlos and at Sabalos. 

DraloBge area T50 equare miles, approilmatcly. 



Monti. 




«»nd-Ccot. 


Total In 
Acre-feat. 


Ru 


-on. 


Maximum. Mlnlmu 


m. Mean. 


^SSf.i" 


Seooncl-f^el 
per sq. mile. 



January (10-31) — 5,100 

Febraar; 17,600 

Mtrcb 8,800 

April 12,700 

May 7,000 

June 21,000 

Jnly 21,600 

AoKiiat 18,100 

September IS.OOO 

October 11,900 

November 4B,000 

December 15,800 

Total 1898 .\.. 



1890. 

Jannaiy 14,<00 

Tebrnary 7,100 

March 4,400 



8,400 
3,600 
3,000 
3, BOO 



176,180 

146,340 


4.40 
8.86 


3.95 
8.17 


492,100 


13.31 


11.03 


830,860 


30.53 


17.80 


404,SBO 


laii 


8.77 


434,860 


10.63 


9.53 


878,000 


9.80 


8.07 


659,360 


16.47 


14.78 


402, ISO 


10.05 


8.73 


,490,340 






513,180 


13.80 


11.10 


348,810 


6.09 


5.85 



1 


"™ "to ""o" ""o tQM io" ^DJO ^^% ^0?D °"o To i °oli 


\ ■ ' \ ! 1 


^ ^t _l[.__^____ 


I 1 ^I ± — 


1 ^ _ ^_ __. 


Z'" ^ ^l||]^__^ 


I 11 'L ,^ L . 


J ^ 


Z"] -Jl^4i-1- - 


i ■■ . Ill 1 


uriiup ^1' ' 



FiQ. 4. Diagram of dally discharge of tributaries of San Juan between Sabalos and Boca San Carlos, IS98. 



NICARAGUA CANAL COMMISSION 



;|||| 



Fio. 6. Diagram ot dally discharge o( the San Juan above Boca San Carlos. 



Eio San Carlos. 
The San Carlos river is a wide, swift stream, 
heading in the high mountains of Costa Rica. 
From these mountains it obtains large quantities 
of volcanic sand, portions of which become 
ground &ae enough to be held in suspension, and 
large quantities are carried both in this way and 
rolled on the bottom of the stream, especially 
in times of great floods to whicli this river is 
subject. Ita drainage area as measured from 
the best maps obtainable is 1450 square miles, 
but this must be regarded as merely a rough 
approximation, as the country has never been 
even thoroughly explored, much less accurately 
mapped. Above the mouth of the San Carlos 
the San Juan is a stream of comparatively uni- 
form discharge, the greater portion of its water 
coming from Lake ^Nicaragua, which acta aa a 
very effective regulator upon the floods in the 
basin. From the mouth of San Carlos river to 
the foot of ilachuca rapids the San Juan is very 
deep and the current consequently sluggish. 



This portion is called the Aguas Muertas, or 
dead waters. It frequently occurs that the San 
Carlos is in flood, and the large volume of water 
affects the water surface of the Aguas Muertas, 
in proof of which a rise in the San Juan below 
!Machuca rapids has been observed, amounting 
to nearly four feet at a time when the San Carlos 
was in flood, while no rise whatever occurred 
above the rapids. The largo quantity of mate- 
rial carried by the San Carlos river has built a 
delta at its mouth so that it flows to the San 
Juan through two channels around a deltaic 
island, and from its mouth to the sea the bottom 
of the San Juan is covered with moving sands 
brought in by the San Carlos. 

Slalion on Rio San Carlos. — A station was 
established on the San Carlos river about three 
miles above its mouth, on the 10th day of Jan- 
uary', 1898. The gage consists of a pine board 
painted white and graduated to feet and tenths 
from zero to 15 feet, the reading being con- 
tinued on another board fastened to another tree 



APPENDIX III.— HTDROORAPHIC REPORT 



227 



a short diBtance downstream and higher up on 
the bank. A f-inch steel cable was placed across 
the river at this point, npon which traveled a 
gaging oar from which measurements were made. 



cord was fastened, and the other end attached to 

the meter cord JHst above the meter. This held 

the instrument from drifting downstream, and 

heavy lead sinker would carry it to any de- 



In times of high water the stream is so swift sired depth, where it could he held without 
that it is difficult to make the meter sink to the difficulty. This arrangement ia illustrated in 




Plate VII. Starting to gage a river. 



desired point in the stream, the tendency of the 
meter, in spite of heavy lead weights, being to 
drift downstream and rise to the surface, under 
the joint influence of the current and the sus- 
pending wire. To overcome this difficulty 
another and smaller cable was thrown across the 
river about 200 feet above the main cable, which 
carried a small pulley block. To this pulley a 



Plate Vm. A sediment trap was also em- 
ployed at this station, suspended from the cable 
when in operation. 

A bench mark was made by driving a spike 
into a large root of the tree used as a cable sup- 
port, which stood out from the tree like an 
abutment The bench mark is 30.74 feet above 
zero of the gage. The high water occurring 



228 



NICARAGUA CANAL COMMISSION 



from the 2d to the Sth of January scoured out 
the channel of the river somewhat, so that a sep- 
arate rating table has been made for January 
and another for the months, February, March, 



April and May; still another, somewhat different, 
is used from the 1st of June for the balance of 
the season. 



DAILY GAGE HEIGHT OF SAN CARLOS RIVER THREE MILES ABOVE ITS MOUTH FOR 1898-9. 


1898. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


AufiT. 


Sep. 


Oct. 


Nov. 


Dec. 


1809. 
Jan. 


Feb. 


■ 

Mar. 


Day. 


• • • • 


12.79 


12.35 


11.47 


11.03 


12.88 


15.30 


13.01 


13.00 


13.00 


14.20 


13.85 


11.90 


11.85 


12.40 


2.... 


• • • • 


16.21 


12.83 


11.45 


11.19 


12.30 


15.93 


13.80 


13.16 


13.15 


13.80 


13.65 


12.75 


11.85 


12.20 


o . . . . 


• • • • 


16.06 


12.58 


11.45 


11.03 


11.88 


15.31 


14.90 


12.90 


12.80 


13.50 


14.05 


14.35 


11.80 


12.15 


4 


• • • • 


17.41 


12.37 


11.43 


11.05 


11.68 


14.92 


14.05 


13.05 


12.75 


13.90 


13.75 


12.80 


11.70 


12.05 


Q • . • • 


• • • • 


19.23 


13.82 


12.93 


11.05 


11.58 


16.10 


14.87 


13.15 


12.75 


13.45 


13.65 


12.60 


11.65 


12.00 


6.... 


* * • a 


18.26 


13.43 


18.15 


11.08 


11.50 


14.97 


14.74 


13.15 


13.95 


13.35 


13.95 


12.40 


11.60 


11.85 


7 


• • • • 


16.20 


12.73 


13.29 


11.03 


12.25 


15.18 


13.94 


12.85 


13.25 


14.00 


13.50 


12.15 


12.05 


11.85 


• . . . 


• • • • 


15.92 


12.43 


13.00 


11.01 


11.98 


16.78 


13.58 


12.60 


13.10 


14.90 


13.30 


12.55 


12.00 


12.70 


«7 . . . a 


• • • • 


15.20 


12.33 


13.00 


11.00 


11.75 


18.11 


13.30 


12.45 


13.35 


16.05 


13.10 


12.50 


11.70 


12.80 


10.... 


16.00 


14.60 


12.43 


12.35 


11.01 


12.80 


19.53 


13.14 


12.48 


13.30 


16.50 


13.70 


12.35 


11.70 


12.20 


11 


15.40 


14.27 


12.40 


12.00 


11.02 


12.28 


17.13 


13.40 


13.10 


• 

13.30 


15.35 


16.75 


12.20 


11.70 


11.95 


12.... 


15.00 


13.95 


12.22 


12.05 


11.04 


11.95 


15.68 


13.52 


12.55 


13.80 


14.85 


15.05 


12.35 


11.70 


11.80 


13.... 


14.62 


18.76 


12.^8 


11.98 


11.04 


11.85 


15.25 


14.65 


14.25 


13.60 


19.10 


14.35 


13.00 


12.70 


11.75 


14... 


14.85 


13.47 


11.97 


11.86 


11.12 


12.97 


14.85 


15.51 


14.50 


13.75 


18.05 


13.95 


13.25 


14.70 


11.80 


15.... 


14.07 


13.39 


11.87 


11.71 


11.13 


12.60 


14.45 


14.38 


13.75 


13.30 


16.70 


13.55 


12.90 


13.45 


11.70 


16.... 


14.07 


13.15 


11.95 


11.60 


11.64 


13.19 


14.59 


14.09 


14.50 


14.15 


16.55 


13.35 


15.00 


13.25 


11.65 


17 


14.25 


12.95 


11.95 


11.46 


11.76 


13.49 


14.20 


13 65 


14.40 


13.75 


20.20 


13.30 


13.60 


12.70 


11.55 


18 


18.87 


12.80 


12.53 


11.48 


11.88 


13.11 


14.10 


13.42 


13.85 


16.40 


17.60 


13.15 


13.25 


12.85 


11.50 


19 


13.65 


12.85 


11.89 


11.60 


12.05 


13.78 


14.18 


13.23 


13.75 


16.90 


16.40 


13.90 


13.20 


12.95 


il.50 


20.... 


13.47 


12.71 


11.74 


11.51 


13.50 


14.38 


14.25 


13.45 


14.90 


16.10 


15.50 


12.75 


13.20 


12.85 


11.40 


21 


13.65 


12.61 


11.69* 


11.41 


12.55 


14.29 


14.12 


13.50 


13.95 


14.90 


15.05 


12.60 


12.85 


13.30 


11.40 


lit-t .... 


13.47 


12.54 


11.66 


11.29 


12.54 


13.74 


13.81 


14.58 


14.30 


14.35 


14.70 


12.50 


12.65 


12.85 


11.30 


23.... 


13.27 


12.52 


11.65 


11.40 


12.18 


13.90 


13.69 


13.86 


15.00 


14.30 


14.30 


12.40 


12.55 


13.70 


11.25 


24 ... . 


13.05 


12.36 


11.56 


11.48 


12.09 


15.98 


13.33 


13.93 


13.80 


16.30 


14.00 


12.20 


12.50 


13.20 


11.20 


25 ... . 


12.88 


12.45 


11.68 


11.41 


11.93 


15.20 


13.21 


13.70 


13.70 


15.15 


13.90 


12.20 


12.60 


12.90 


11.15 


26 


12.77 


12.45 


12.19 


11.31 


11.74 


15.15 


13.12 


13.60 


13.50 


19.30 


13.85 


12.20 


12.35 


12.55 


11.10 


27 


12.81 


13.05 


12.69 


11.84 


11.55 


17.70 


12.98 


13.90 


14.05 


16.15 


13.65 


12.20 


12.20 


12.80 


11.10 


28.... 


13.68 


13.00 


12.44 


11.33 


11.90 


18.53 


12.84 


13.80 


13.95 


15.25 


13.90 


12.10 


12.15 


12.60 


11.05 


29.... 


13.17 


• • • • 


11.98 


11.13 


12.00 


16.92 


14.14 


13.35 


13.50 


14.85 


14.00 


12.00 


12.05 


• • • • 


11.10 


30.... 


13.02 


• • • • 


11.74 


11.05 


11 85 


15.53 


13.50 


13.00 


13.30 


14.40 


14.65 


11.95 


12.00 


• • • • 


11.10 


31 


12.80 

• 


• • • • 


11.03 


• • • • 


12.60 


• • • • 


18.08 


13.10 


.... 


15.05 


• • • • 


11.95 


11.90 


• • • • 


11.05 



LIST OF DISCHARGE MEASUREMENTS MADE ON SAN CARLOS RIVER THREE MILES 

ABOVE ITS MOUTH. 



Date. 



Hydrogrraphcr. 



Meter 
number. 



Gage Area of Mean ni«oh«ra« 

height section velocity .li?. f**^ 

(ft). (sq.ft.). (ft. per sec), ^sec.-rt,). 



licmarks. 



1898. 

Jan. 27 R. Breese 

" 29 *» 

'» 31 " 

Feb. 2 *' 

(( 4 '* 

'« 5 " 

" 10 »' 

*' 11 " 



65 
65 
65 
65 
65 
65 
65 
65 



12.63 
13.17 
12.75 
16.37 
17.87 
19.00 
14.59 
14.19 



2,897 
3,529 
8,076 
5,509 
6,503 

4,880 
3,642 



3.26 
3.57 
3.37 
4.00 
4.27 

• • • • 

4.59 
3.34 



9,445 
12,602 
10,352 
22,208 
27,782 

14, 890 
12,201 



Rising. 

Rising rapidly. 
Battery failed. 



APPENDIX III.— HYDEOORAPHIC REPORT 



UST OF DISCHARGE MEASUREMENTS MADE ON SAN CARLOS RIVER THREE MILES 
ABOVE ITS MOUTH.—Contlnued. 



». 



April 6 




31 


M.J 


13 

14 


,. 


W... .'.'.'.'. 


.Innfl 


20 




23 




24 




37 




39 




30 


July 4 




8 




10 




13 




33 




28 




30 


Aat! 


2 








8 




6 




14 




33 




28 


8«P- B 




10 




14 




23 


Oct 


4 


., 


20 


Not 


U 




1» 




38 


Mfc 


IS 




19 




27 




SI 


IBM. 


.Tin 


2 




S 




13 




16 




81 


Feb 


8 




18 




14 




30 


MAr 


1 




9 




17 




20 




34 


'• 


89 



R. C. Wheeler 



13.10 
11.40 

11.03 



1,990 

3,5S7 
8,t»40 

8,360 
5,503 
7,837 
6,001 



15.48 


4,761 


13.88 


8,530 


13,20 


3,036 


13.58 


8,810 


13.04 




15.70 


4,873 


15.20 


4,409 


15.37 


4,544 


15.93 


6,114 


14.50 


3,933 


18.89 


3,579 


13.60 


3,781 


13.48 




14.47 


4,039 


14.32 


3,»40 


12.77 


3,600 


16.09 


5,473 


16,07 


5,100 


18,10 


H,B80 


80.11 


8,579 


10.43 




13.90 


3,576 


13.rs5 


3,438 


13.90 


3,875 


12.C0 


2,5H3 


12.30 


2,360 



4,139 
4,636 
6,187 
11,006 
13,156 
10,673 
30,414 
39,480 
22,009 
16,763 
12,800 
14,464 
38,606 
15,763 
10,700 
8,746 
9,844 
8,296 
17,074 
14,834 
16,113 
16,730 
12,434 
10,781 
7,857 
7,791 
12,436 
13,662 



11.90 


3,105 


2.56 


5,380 


11.78 


1,991 




.^016 


13.13 


3,869 


3.00 


8,008 


14,86 


8,980 


8.3S 


13,863 


13,90 


3,987 


2.09 




13.38 


3,860 


3.53 


U,733 


13.76 


2,947 


3.63 


7,735 


11.53 


3,193 


' 2.39 


6,245 



230 



NICARAGUA CANAL COMMISSION 



RATING TABLE FOR SAN CARLOS RIVER, AT CAMP. THREE MILES ABOVE MOUTH. 

Table good for January, 1898, only. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


8econ<l-ft. 


Feet. 


Second-ft. 


12.5 


9,000 


13.4 


13,960 


14.3 


18,820 


15.2 


23,680 


12.6 


9,540 


13.5 


14,500 


14.4 


19,360 


15.8 


24,220 


12.7 


10,180 


13.6 


15,040 


14.5 


10,900 


15.4 


24,760 


12.8 


10,720 


13.7 


15,580 


14.6 


20,440 


15.5 


25,300 


12.9 


11,260 


13.8 


16,120 


14.7 


20,980 


15.6 


25,840 


13.G 


11,800 


13.9 


16,660 


14.8 


21,520 


15.7 


26,880 


13.1 


12,840 


14.0 


17,200 


14.9 


22,060 


15.8 


26,920 


13.2 


12,880 


14.1 


17,740 


15.0 


22,600 


15.9 


27,560 


13.3 


13,420 


14.2 


18,280 


15.1 


23,140 


16.0 


28,000 



RATING TABLE FOR SAN CARLOS RIVER, AT CAMP. THREE MILES ABOVE MOUTH. 
This table is applicable only from February 1, 1898, to May 30, 1898. 



Gage 
height. 



Discharge. 



Gage 
height. 



Discharge. 



(lage 
height. 



Discharge. 



Gage 
height 



Discharge. 



Feet. 


Second-ft, 


11.0 


4,100 


11.1 


4,340 


11.2 


4,580 


11.3 


4,820 


11.4 


5,040 


11.5 


5,280 


11.6 


5,520 


11.7 


5,760 


11.8 


0,000 


11.9 


0,250 


12.0 


0,500 


12.1 


6,750 


12.2 


7,000 


12.3 


7,250 


12.4 


7,500 


12.5 


7,750 


12.6 


8,000 


12.7 


8.250 



Feet. 


Second-ft. 


12.M 


8,500 


12.9 


8,750 


13.0 


9,000 


13.1 


9,360 


13.2 


9,720 


18.3 


10,080 


13.4 


10,440 


13.5 


10,800 


13.6 


11,160 


18.7 


11,520 


18.8 


11,880 


13.9 


12,240 


14.0 


12,620 


14.1 


13,000 


14.2 


13,380 


14.3 


13,760 


14.4 


14,140 


14.5 


14,520 



Feet. 
14.6 
14.7 
14.8 
14.9 
15.0 
15.1 
15.2 
15.3 
15.4 
15.5 
15.6 
15.7 
15.8 
15.9 
16.0 
16.1 
16.2 
16.3 



Second-ft. 

14,900 
' 15,280 
15,660 
16,040 
16,420 
16,800 
17,180 
17,560 
17,940 
18,320 
18,700 
19,100 
19,500 
19,900 
20,300 
20,700 
21,100 
21,500 



5'eet. 


8?cond-ft 


16.4 


21,900 


16.5 


22,800 


16.6 


22,700 


16.7 


23,100 


16.8 


23,500 


16.9 


23,900 


17.0 


24,800 


17.1 


24,700 


17.2 


25,100 


17.3 


25,500 


17.4 


25,900 


17.5 


26,300 


17.6 


26,700 


17.7 


27,100 


17.8 


27,500 


17.9 


27,900 


18.0 


28,300 



RATING TABLE FOR SAN CARLOS RIVER, AT CAMP, THREE MILES ABOVE MOUTH. 
This table is applicable only from June 1, 1898, to November 30, 1898. 



heiX Discharge. 



SSre Discharge. 



height. 



Gage 
height. 



Discharge. 



Gage 
height. 



Discharge. 



Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 




11.0 


4,100 


11.8 


5,910 


12.6 


7,800 


13.4 


9,800 




11.1 


4,320 


11.9 


6,140 


12.7 


8,050 


13.5 


10,050 




11.2 


4,540 


12.0 


6,370 


12.8 


8,800 


13.6 


10,800 




11.3 


4,760 


12.1 


0,600 


12.9 


8,550 


13.7 


10,560 




11.4 


4,980 


12.2 


6,830 


13.0 


8,800 


13.8 


10,830 




11.5 


5,200 


12.3 


7,060 


13.1 


9,050 


13.9 


11,100 




11.6 


5,480 


12.4 


7,300 


13.2 


9,300 


14.0 


11,380 




11.7 


6,680 


12.5 


7,550 


13.3 


9,550 


14.1 


11,660 





APPENDIX III.— HYDROGRAPHIC REPORT 



231 



RATING TABLE FOR SAN CARLOS RIVER, AT CAMP. THREE MILES ABOVE MOUTH.— Continued. 



heght. ^K^bargo. 



heS^*t. Dlscharje. 



heX. DlBehaw. 



G&ge 
height 


Discbanre 


Feet. 


Second-ft. 


19,6 


34,100 


19.7 


84,700 


19.8 


85,800 


19.9 


85,900 


20.0 


86,500 


20.1 


87,100 


20.2 


87,700 


20.3 


88,800 


20.4 


88,900 


20.5 


89,500 


20. rf 


40,100 


20.7 


40,700 


20.8 


41,800 


20.9 


41,900 


21.0 

• • • • 


42,500 


• • • • 

• • • • 





Feet. 


8econd-ft 


14.2 


11,940 


14.8 


12,220 


14.4 


12,500 


14.5 


12,780 


14.6 


13,060 


14.7 


13,840 


14.8 


13,620 


14.9 


13,900 


15.0 


14,200 


15.1 


14,500 


15.2 


14,800 


15.8 


15,100 


15.4 


15,400 


15.5 


15,700 


15.6 


16,000 


15.7 


16,380 


15.8 


16,660 


15.9 


17,000 



Feet. 


Second- ft 


16.0 


17,340 


16.1 


17,680 


16.2 


18,020 


16.3 


18,360 


16.4 


18,700 


16.5 


19,050 


16.6 


19,400 


16.7 


19,750 


16.8 


20,100 


16.9 


20,500 


17.0 


21,000 


17.1 


21,500 


17.2 


22,000 


17.3 


22,500 


17.4 


23,000 


17.5 


23,500 


17.6 


24,000 


17.7 


24,500 



?"eet. 


Second- ft 


17.8 


25,000 


17.9 


25,500 


18.0 


26,000 


18.1 


26,500 


18.2 


27,000 


18.3 


27,500 


18.4 


28,000 


18.5 


28,500 


18.6 


29,000 


18.7 


29,500 


18.8 


80,000 


18.9 


30,500 


19.0 


81,000 


19.1 


31,500 


19.2 


82,000 


19.8 


82,500 


19.4 


83,000 


19.5 


33,500 



RATING TABLE FOR SAN CARLOS RIVER. THREE MILES ABOVE ITS MOUTH. 
This table is applicable only from December 1, 1898, to March 31, 1899. 



Gage 



height. i>i~>»nre. 



S,X Discharge. 



height. 



Gage 



hofg^^. Discharge. 



Feet. 

11.0 

11.1 

11.2 

11.3 

11.4 

11.5 

11.6 

11.7 

11.8 

11.9 

12.0 

12.1 

12.2 

12.3 

12.4 

12.5 

12.6 

12.7 

12.8 

12.9 

13.0 



8econd-ft. 
4,280 
4,380 
4,530 
4,680 
4,830 
4,980 
5,140 
5,820 
5,520 
5,740 
5,980 
6,240 
6,500 
6,760 
7,020 
7,280 
7,540 
7,800 
8,060 
8,320 
8,580 



Feet. 


Second-ft. 


18.1 


8,860 


13.2 


9,140 


13.3 


9,420 


18.4 


9,700 


18.5 


9,980 


13.6 


10,260 


13.7 


10,540 


13.8 


10,820 


13.9 


11,100 


14.0 


11,880 


14.1 


11,660 


14.2 


11,940 


14.3 


12,220 


14.4 


12,500 


14.5 


12,780 


14.6 


18,060 


14.7 


13,840 


14.8 


13,620 


14.9 


18,900 


15.0 


14,200 


15.1 


14,500 



Feet. 
15.2 
15.3 
15.4 
15.5 
15.6 
15.7 
15.8 
15.9 
16.0 
16.1 
16.2 
16.8 
16.4 
16.5 
16.6 
16.7 
16.8 
16.9 
17.0 
17.1 
17.2 



Second-ft, 
14,800 
15,100 
15,400 
15,700 
16,000 
16,330 
16,660 
17,000 
17,340 
17,680 
18,020 
18,860 
18,700 
19,050 
19,400 

- 19,750 
20,100 
20,500 
21,000 
21,500 
22,000 



Gage 
height. 


Discharge. 


Feet 


Second-ft 


17.3 


22,500 


17.4 


23,000 


17.5 


23,'>00 


17.6 


24,000 


17.7 


24,500 


17.8 


25,000 


17.9 


25,500 


18.0 


26,000 


18.1 


26,500 


18.2 


27,000 


18.3 


27,500 


18.4 


28,000 


18.5 


28,500 


1H.6 


29,000 


18.7 


29,500 


18.8 


30,000 


18.9 


80,500 


19.0 


31,000 



232 



NICARAGUA CANAL COMMISSION 



ESTIMATED MONTHLY DISCHARGE OF SAN CARLOS RIVER THREE MILES ABOVE ITS MOUTH. 

Drainage area» 1,450 square miles, approximately. 



Month. 



Di^charflre in Second-feet. 



Maximum. 



Minimum. 



Mean. 



Total in 
Acre-feet. 



1898. 

January (10-31) 28,000 10,560 16,055 700,582 

February 34,300 7,400 13,530 751,380 

March 11,341 5,140 7,030 432,260 

April 10,080 4,220 6,038 859,285 

May 11,880 4,100 5,560 841,870 

June 32,250 5,200 10,720 637,880 

July 41,600 8,400 14,094 866,605 

August 15,730 8,800 10,990 675,750 

September 14,200 7,420 10,319 614,023 

October 82,500 8,180 12,880 791,960 

November 32,260 9,680 15,440 918,750 

December 19,920 5,850 9,290 671,220 

Total, 1898 7,661,565 

1899. 

January 14,200 5,720 7,865 483,600 

February 13,340 4,940 7,360 408,750 

March 8,060 4,300 5,400 332,030 





Run-ofT, 


t 


Depth 
in inches, 


Second-feet 
per sq. mile. 


9.09 




11.1 


9.68 




9.3 


5.53 




4.8 


4.69 




4.2 


4.38 




8.8 


8.26 




7.4 


11.18 




9.7 


8.76 




7.6 


7.92 




7.1 


10.26 




8.9 


11.88 




10.6 


7.88 




6.4 



6.28 
5.31 
4.27 



5.4 
5.1 
3.7 



OciiOA Station on the San Juan. 

One of the most important as well as most 
disputed points regarding hydrographic knowl- 
edge in Nicaragua is the discharge of the Rio San 
Jnan at Ochoa, where it is proposed to build a 
high dam. A station. was established here on 
December 30, 1897. A vertical pine gage was 
fastened to an overhanging tree on the right 
bank, and was graduated to feet and tenths, to 
15 feet, and continued upward on another plank 
fastened to the same tree. 



A standard copper bench mark of the TT. S. 
Geological Survey was established on the right 
bank near the tree which bears the gage. It is 
a copper plate placed horizontally on top of a 
stump, with its stem driven into an auger hole 
in the stump. It is 28.10 feet above the zero 
of the gage. The channel at this point is 
straight, and the bottom is reasonably perma- 
nent. 



APPENDIX III.— HYDROGRAPHIC REPORT 



23S 




234 



NICARAGUA CANAL COMMISSION 



DAILY GAGE HEIGHT OF SAN JUAN RIVER AT OCHOA FOR 1898-9. 



iao8. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Au^. 


Sep. 


Oct, 


Nov. 


Dec. 


lovtf. 

Jan. 


Feb. 


Mar. 


Day. 

X • • • • 


14.80 


7.83 


7.50 


5.38 


4.76 


6.65 


11.30 


8.63 


7.93 


8.66 


9.65 


10.90 


8.60 


7.60 


7.22 


2.... 


14.45 


9.45 


7.20 


5.30 


4.55 


6.15 


12.38 


8.90 


7.98 


9.75 


9.18 


11.20 


9.32 


7.58 


7.12 


o . . • • 


15.83 


10.48 


7.00 


5.28 


4.56 


5.60 


12.75 


9.38 


7.88 


8.63 


9.00 


10.60 


9.85 


7.47 


7.02 


4.... 


15.60 


9.30 


6.85 


6.40 


4.53 


6.43 


12.40 


9.13 


7.93 


8.45 


9.05 


10.20 


9.30 


7.38 


6.92 


o. . . . 


13.38 


12.70 


7.60 


8.10 


4.68 


6.30 


12.35 


9.53 


8.00 


8.65 


8.96 


9.86 


9.55 


7.30 


6.88 


6. . . . 


13.55 


12.45 


7.73 


8.58 


4. .58 


6.20 


11.08 


9.76 


8.20 


8.93 


8.90 


9.75 


9.28 


7.30 


6.78 


7 


14.70 


10.63 


7.18 


7.65 


4.55 


6.48 


10.43 


9.40 


8.13 


8.75 


9.10 


9.76 


8.92 


7.50 


6.78 


8.... 


13.30 


9.78 


6.90 


7.35 


4.50 


6.03 


11.13 


9.25 


7.90 


8.73 


9.78 


9.60 


9.07 


7.45 


7.28 


9. . . . 


11.23 


9.40 


6.83 


7.10 


.4.40 


6.05 


12.95 


8.75 


7.80 


9.00 


10.98 


9.48 


8.92 


7.30 


7.40 


10.... 


10.95 


9.13 


6.75 


6.35 


4.33 


6.28 


13.85 


8.78 


7.78 


8.86 


10.88 


10.43 


9.07 


7. 25 


6.98 


11.... 


10.40 


8.78 


6.73 


6.10 


6.40 


6.08 


12.48 


8.63 


10.68 


8.68 


10.43 


12.60 


8.97 


7.25 


6.75 


12.... 


9.98 


8.55 


6.58 


6.08 


6.18 


5.73 


11.08 


8.65 


9.65 


8.85 


10.23 


11.10 


9.85 


7.45 


6.65 


13 


9.63 


8.43 


6.43 


6.95 


4.95 


5.90 


10.53 


9.30 


10.53 


8.7rf 


13.08 


10.38 


10.37 


8.38 


6.60 


14.... 


9.33 


8.10 


6.33 


5,70 


4.65 


6.13 


10.10 


11.65 


10.45 


8.88 


13.68 


9.90 


9.90 


8.98 


6.55 


15 


8.95 


7.83 


6.18 


5.50 


4.63 


6.23 


9.68 


10.45 


9.65 


8.58 


12.30 


9.53 


9.97 


8.15 


6.52 


16 


8.90 


7.68 


6.08 


5.35 


4.70 


6.28 


9.28 


9.65 


11.65 


8.80 


13.28 


9.38 


10.65 


7.98 


6.48 


17.... 


9.15 


7.50 


6.08 


5.25 


4.93 


7.08 


9.15 


8.98 


10.73 


8.88 


17.20 


11.05 


9.95 


7.90 


6.35 


18... 


• ■ • • 


7.38 


6.18 


.5.28 


5.25 


6.38 


9.05 


8.53 


9.88 


11.30 


15.03 


10.15 


9.42 


8.26 


6.30 


19.... 


• • ■ • 


7.40 


5.95 


6.;'.5 


6.40 


9.45 


10.15 


8.25 


9.53 


1 1.95 


13.15 


9.85 


9.17 


8.20 


6.28 


20. . . . 


• • • • 


7.28 


5.83 


5.15 


7.33 


10.53 


10.88 


8.20 


9.70 


11.83 


12.18 


9.08 


9.02 


8.00 


6.25 


21 


• • • • 


7.18 


5.70 


5.10 


6.53 


11.45 


10.85 


8.28 


9.60 


10.85 


11.48 


8.78 


8.75 


8.22 


6.22 


22.... 


• • • • 


7.10 


5.75 


6.05 


7.08 


10.28 


10.38 


8.85 


9.95 


10.25 


10.90 


8.60 


8.52 


7.80 


6.12 


23.... 


8.80 


7.05 


5.70 


5.10 


6.15 


9.75 


9.65 


8.60 


11.06 


10.38 


10.48 


8.63 


8.45 


8.10 


6.02 


24 ... 


8.35 


6.90 


5.65 


5.13 


5.85 


11.55 


9.10 


8.60 


9.76 


11.03 


10.10 


8 33 


8.35 


7.90 


6.00 


25. . . . 


8.13 


6.90 


5.93 


6.00 


5.78 


11.98 


9.05 


8.40 


9.45 


10.75 


10.00 


8.26 


8.35 


7.70 


5.98 


26.... 


8.10 


6.93 


6.15 


4.98 


5.63 


10.90 


8.85 


8.40 


9.65 


12.70 


10.23 


8.18 


8.15 


7.42 


5.90 


27 


8.30 


7.28 


6.38 


5.00 


5.50 


12.00 


8.63 


8.40 


9.93 


11.40 


10.70 


8.15 


8.02 


7.50 


5.82 


28.... 


8.53 


7.43 


6.20 


4.85 


5.93 


12.76 


9.18 


8.40 


10.43 


10.58 


11.85 


8.13 


7.97 


7.40 


5.80 


29 


8.30 


• • • • 


5.88 


4.78 


5.75 


12.95 


9.45 


8.18 


9.30 


10.15 


11.68 


8.30 


7.82 


• • • • 


5.80 


80.... 


8.10 


• • • • 


5.65 


4.70 


5.50 


11.18 


9.70 


8.10 


8.90 


9.75 


10.95 


8.25 


7.72 


• • • • 


5.78 


31.... 


8.03 


• • • • 


6.53 


• • • • 


6.28 


• • • • 


9.68 


7.98 


• • • • 


9.83 


• • • • 


8.30 


7.65 


• • • • 


6.70 



For purposes of current meter measuremeiits 
it was not permissible to extend a cable over the 
river at this point on account of navigation. It 
was first intended to make measurements by 
means of a boat anchored to a small cable 
stretched across the river, which should carry 
tags indicating distances from the initial point, 
and which when not in use was to be held against 
the bottom of the river by means of sinkers. 
Experience on this line, however, soon demon- 
strated that it would be difficult, if not imprac- 
ticable, to maintain a small cable in the position 
proposed on account of the large quantities of 
driftwood, leaves and brush passing down the 



river, especially in times of flood, when the 
gaging apparatus would be most in demand. 
Another project was therefore inaugurated, 
which was the anchorage of a number of buoys 
at known distances from the initial point, said 
buoys to be constructed of "balsa," a very light, 
bulky endogenous wood much used in the con- 
struction of rafts, etc. This method of marking 
distances from the initial point was successfully 
employed for several months during the season 
of low water, but as the rains increased and 
freshets began to come down the river the great 
quantity of leaves and brush carried by the 
water attached themselves to the buovs and their 



APPENDIX III.— HYDROGRAPHIC REPORT 



235 



anchorages until they were either carried be- 
neath the surface of the river or washed awav 
entirely. The method permanently adopted re- 
quired the employment of an additional instni- 



ment man to manipulate a telescope on shore and 
measure the distance of the boat during the pro- 
cess of gaging, by means of a stadia rod. 



LIST OF DISCHARGE MEASUREMENTS MADE ON SAN JUAN RIVER AT OCHOA. 



Date. 



Hydrogrraphcr. 



Meter Gage height Area of Rection Mean velocity Discharge •unmar-va 
number. (feet). (square feet), (ft.persec'd). Jsecond-ft.) "^«™a'^»^»- 



Jan. 8 
*' 12 

Feb. 8 

'* 16 

*♦ 38 

Mar. 10 

«» 19 

Apr. 1 
i* 14 

«» 27 

Mav 10 

Juu. 4 

»' 17 

♦' 23 

'' 20 

*' 28 

Jiilv 8 

♦' ' 11 

♦♦ 1(5 

♦' 19, 

'* 25, 

♦' 28 

AU!^. 1 

8, 

li ~ 

Sep. 

ii 
II 

Oct. 



< . 

3. 
12, 
1«. 
2«, 

1 
17. 
18. 

8. 
13. 
17. 
19. 
30. 



it 

Nov, 

i( 

ii 
It 

it 

Dec. 12 

" 19. 

»♦ 22. 

»♦ 28. 

'» 30. 
1899. 
Jan. 0. 

" 13. 

*♦ 21. 

♦» 26 

" 30. 
Feb. 7. 

♦» 21. 

'» 25. 

»' 28. 
Mar. 3. 

»« 7. 

»' 13. 

»» 31 . 



G. R. Wadlelgh. 



it 
it 
ti 
ti 
ti 
ti 
it 
it 
it 
it 
ti 
it 
it 



A. P. Davis 

G. R. Wadleigh, 



it 

it 
it 
(t 
ti 

it 

it 
it 



H. S. Reed 



it 
it 
it 
It 
it 
ti 
it 
it 
it 
It 
ti 
ti 
it 
(t 
tt 
ti 

ti 
it 
it 
•t 
it 
it 
ti 
it 
it 
tt 
it 
it 
it 



1985 


11.94 


13,100 


4.00 


52,400 


1985 


9.87 


11,940 


3.67 


43,880 


1985 


8.80 


9,906 


3.33 


83,050 


1985 


9.78 


10,916 


8.75 


40,913 


1985 


7.65 


8,966 


3.29 


29,458 


1985 


7.40 


8,602 


3.21 


27,600 


1985 


6.73 


8,132 


3.07 


24,974 


1985 


5.95 


7,703 


2.89 


22,270 


1985 


5.35 


7,225 


2.91 


21,017 


1985 


5.73 


7,359 


3.03 


22,327 


1985 


4.99 


6,728 


2.72 


18,290 


1985 


4.30 


5,654 


2.S6 


16,145 


1985 


5.41 


6,637 


3.08 


20,461 


1985 


6.64 


7,794 


3.84 


26,066 


1985 


9.68 


10,922 


3.88 


42,850 


1894 


11.13 


11,994 


3.88 


46,529 Falling, 


1985 


12.91 


14,462 


4.25 


61,410 »' 


1985 


11.52 


13,418 


3.86 


51,821 Rising. 


1985 


12.42 


14,438 


3.80 


55,089 


1985 


9.12 


11,211 


3.32 


87,213 


1985 


10.53 


12,586 


3.66 


46,098 


1985 


8.96 


9,782 


3.78 


36,940 


1985 


9.56 


10,506 


3.97 


39,832 


1985 


8.68 


9,826 


3.56 


35,980 


1985 


10.21 


11,094 


3.84 


42,640 


1985 


9.42 


10,359 


3.63 


37,647 


65 


7.85 


8,938 


3.68 


32,984 


65 


9.38 


10,336 


4.00 


41,199 


65 


12.02 


12,761 


4.47 


57,047 


65 


9.43 


9,895 


4.24 


41,975 


65 


8.52 


8,815 


3.97 


34,971 


65 


8.88 


9,026 


4.44 


40,087 


65 


11.79 


12,076 


4.85 


58,620 


65 


9.77 


10,800 


4.40 


47,472 


65 


14.05 


14,171 


5.59 


79,210 


65 


17.43 


19,717 


5.82 


104,930 


65 


13.00 


14,734 


4.53 


66,800 


65 


10.89 


12,057 


4.39 


52,950 


65 


11.02 


12,069 


4.23 


51,042 


65 


9.28 


10,872 


3.89 


41,904 


65 


8.60 


10,286 


3 88 


39,859 


65 


8.10 


9,.565 


8.71 


35,452 


65 


8.25 


9,767 


3.80 


37,089 


65 


9.20 


10,626 


3.90 


41,404 


65 


10.21 


12,006 


4.04 


48,580 


65 


8.75 


10,25? 


8.74 


38,846 


65 


8.12 


9,779 


3.55 


34,688 


65 


7.71 


9,176 


3.59 


32,976 


65 


7.52 


9,113 


3.52 


32,115 


65 


8.13 


9,775 • 


3.67 


85,852 


65 


7.68 


9,393 


3.56 


88,416 


65 


7.87 


8,972 


8.49 


81,314 


65 


7.01 


8,863 


3.41 


30,184 


65 


6.80 


8,954 


3.30 


29,558 


65 


6.60 


8,372 


3.35 


28,048 


65 


5.70 


7,589 


3.08 


23,369 



NICARAGUA CANAL COMMISSION 



I 


\ 


i 


r 




\ 




V 








^ 




V 




A 




\ 




\ 


! 


V 




^ 




V 




^ 




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8 


V 




^ 




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\ 




V 


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A 


S 


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APPENDIX III.— HYDROGRAPHIC REPORT 



237 



The highest measurement of discharge yet 
made at this point was on November 17, at a 
gage height of 17.43 feet, when tJbe river was 
discharging 104,928 cubic feet per second. At 
this stage the river was about 8.5 feet below the 
flood-plain at Ochoa, the formation of which 
indicates that it is sometimes overflowed. 

Dr. C. W. Hayes, geologist of the expedition, 
expresses the opinion that this flood-plain is at 
intervals of ten to thirty years covered by the 
floods of San Juan river to a depth of more 
than six inches,- but less than three feet. In 
other words, maximum gage readings of 26.5 to 
29 may be expected with moderate frequency at 
Ochoa station. The considerations on which 
this conclusion is based are outlined below : 

Physical Chabacteristics of the San Juan 
Flood-plain.— The San Juan river from the mouth 
of the San Carlos eastward flows in a vaUey which 
has recently been depressed below sea level. This 
old valley since submergence has been filled with 
sediment contributed chiefly by the San Carlos and 
Saraplqui, but in some measure also by the smaller 
tributaries. The San Juan may at one time have 
flowed into an estuary which has filled from its head 
seaward, and after the estuary had been filled a 
delta was pushed beyond into the open sea. The 
alluvial plain thus formed had from the start a slope 
dependent upon the volume of the river and the 
quantity and character of the sediment which it car- 
ried. As the mouth of the river was pushed eastward 
its bed and its entire flood-plain were raised by the 
deposit of alluvium, the seaward slope always re- 
maining the same, except as the volume of the river 
and its load may have varied. This process is still 
going on. As the length of the river increases by 
increments to its delta, its flood-plain is built up so 
as to preserve the long gradient. 

Throughout this process of alluviation the eleva- 
tion of the flood-plain above the river bed has re- 
mained practically the same, since this is dependent 
on the relative volumes of the river at extreme stages 
of high and low water and on the relative amount 
of fine and coarse sediment which it carried. It is 
important to note the entire absence of terraces on 
the San Juan. As river terraces are fossil flood- 
plains, marking a former higher flowage plain, their 
absence in a river basin may be regarded as good 



evidence that the river is not cutting down but 
building up its bed, and, at a corresponding rate, its 
flood-plain also. * 

The sediment carried by the river may be classed 
as silt and sand. The former consists of clay, vege- 
table matter and flne sand; the latter chiefly of rather 
coarse sand and flne gravel, with some pebbles up to 
an inch in diameter. The sand is transported 
chiefly by rolling along the bottom of the river bed 
and at all stages of water, although much more is 
carried at flood than at low water by reason of the 
higher velocity. By far the greater part of the sand 
is carried within a few inches of the river bed and 
very little ever reaches more than a few feet from 
the bottom. The silt, on the other hand, is carried 
by suspension in the body of the stream and varies 
in amount with its volume only because it is fur- 
nished more abundantly with flood waters and not 
because it cannot be carried J}y the slacker current 
at low water. The silt remains in suspension until 
quiet water is reached, and hence is either carried far 
out to sea or is deposited on the flood-plain when that 
is overflowed. Although the flood-plain has the same 
seaward slope as the river bed, or a slope slightly 
greater, it receives deposits of the flnest silt when 
flooded. The requisite retardation of the current is 
effected chiefly by the dense growth of vegetation 
which everywhere covers it. This vegetation not 
only checks the current, but acts as a kind of fllter 
by which the sediment is caught and held. Hence 
the deposit is more rapid on the immediate river 
bank and a natural levee is built up, back of which 
is a lower, swampy area. A subordinate reason for 
the more rapid deposition of silt on the river bank 
is that the water. covering the swamps back from the 
river is largely derived from the rainfall in the im- 
mediate vicinity, hence free from silt, and only in 
part from the overflow of silt-laden waters from the 
river. This levee is generally from one to three feet 
higher than the depressed area, though the difference 
in elevation is naturally much greater in the case of 
a wide than a narrow flood-plain. It is manifest that 
the flood-plains are undergoing continuous degrada- 
tion. This is favored by the unconsolidated character 
of the material and is retarded by the dense covering 
of vegetation and the low slopes. If the bed of the 
stream should remain for a considerable time at a 
qonstant elevation a condition of equilibrium would 
at length be reached between the forces tending to 
build up and those tending to degrade the flood- 
plains. As this condition was approached the floods 
of sufficient height to overflow the banks would be- 
come less frequent with the increased height of the 
banks, and the deposition • of silt would be corre- 
spondingly slower. Further, It Is only during the 



238 



NICARAGUA CANAL COMMISSION 



comparatively rapid building of the flood-plain that 
conditions favor the formation of the natural levee. 
On the immediate bank of the river degradation is 
most rapid, chiefly by reason of the proximity to 
steep slopes and through the process of the flattening 
of slopes. The amount of sediment deposited by 
standing water varies directly as the depth of the 
water, hence a flood which barely overtops the levee 
may fill the depressed area behind with a considerable 
depth of water, and if the majority of the floods 
which are building the plain thus barely overtop the 
levee they will tend to bring the entire surface of the 
flood-plain to a level. The fact that the flood-plains 
are still growing, as proved by the absence of ter- 
races and the existence of natural levees, may there- 
fore be regarded as good evidence that the floods 
rise to a considerable height above its surface. 

A secondary flood-plain is frequently observed. It 
is usually quite narrow and may occupy any position 
between the main flood-plain and the bars, which are 
uncovered only at the lowest stages. It is on such 
flood-plains that the most rapid deposition is taking 
place. They always occupy the concave side of the 
river, opposite which active cutting is going on. 
They serve to compensate for the lateral corrasion 
and preserve the normal river section. As their sur- 
face approaches that of the main flood-plain deposi- 
tion becomes gradually slower until they merge with 
the broader plain. 

From considerations given more fully elsewhere, it 
appears probable that the bed of the San Juan from 
the foot of the Machuca rapids to Lake Nicaragua, 
differs from that below Ochoa in that it is being 
lowered instead of raised. The lowering between the 
foot of the Machuca rapids and the head of the Toro 
rapids has probably been considerable, and a careful 
examination of this portion of the river valley should 
reveal remnants of former flood-plains in the shape 
of terraces. Above Sabalos the river has probably 
remained at a constant elevation for a long time and 
the flood-plains have perhaps reached nearly the point 
of equilibrium. Deposition of alluvium, however, is 
much slower here than farther down, since the water 
leaving the lake is practically clear and only a small 
amount of sediment is added to it by the few tribu- 
taries between the lake and Sabalos. Hence the sur- 
face of the flood-plains probably marks very nearly 
the stream height of water at the normal high floods. 

The Relation op Floods to the Flood-plain. — 
The floods of all rivers may be conveniently classed 
in three categories: (1) normal annual floods; (2) 
normal high floods; (3) exceptional high floods. The 
normal annual floods of the San Juan do not reach 
the main flood-plain, at least in the vicinity of Ochoa. 
They probably fail to overtop the banks by at least 



three to flve feet, covering only the secondary flood- 
plains mentioned above. On these they leave con- 
siderable deposits, the character of the material de- 
pending on their elevation. It varies from coarse 
sand on the bars just emerging above low water to 
flne silt where the secondary plain approaches the 
main flood-plain. 

The normal high floods undoubtedly cover the flood- 
plains. While it is impossible to make exact state- 
ments either as to the frequency of the floods or the 
depth of the water on the flood-plain, there is some 
basis for a tolerably fair estimate. From the con- 
siderations given above it is certain that these high 
floods are of sufficient frequency and of sufficient 
height so that the depth of the alluvium which they 
deposit exceeds the surface degradation in the in- 
terval from one flood to another. The two factors 
favoring rapid deposition are abundance of sediment 
and the dense vegetation of the flood-plains. The 
latter also retards the degradation by projecting the 
unconsolidated material. With these favorable con- 
ditions for deposition we should expect to find the 
flood-plains built up nearly to the limit flxed by the 
extreme normal floods. That it has not reached the 
limit appears from the presence of the natural levees, 
for these, as shown above, would disappear when the 
point of equilibrium was reached. Moreover, fre- 
quent floods which barely overtopped the banks 
would tend to obliterate the inequalities. Hence the 
presence of these levees and other inequalities in the 
flood-plain would indicate that the floods were at 
rather long intervals, but that they covered the plain 
to a considerable depth. From these considerations 
it would seem probable that at intervals of ten to 
thirty years floods may be expected in the San Juan 
of sufficient height to cover the flood-plains in the 
vicinity of Ochoa to a depth of more than six inches, 
but less than three feet. 

All large rivers are liable to exceptional high floods, 
due to a rare combination of circumstances, which 
take place at long intervals, probably measured by 
generations or centuries. Such floods are too vari- 
able in height and come at too great intervals to 
produce a flood-plain or other permanent record. 
They are liable to effect extensive changes in the 
course of the river and in its banks and in the vegeta- 
tion growing on the flood-plains, but these effects are 
all of a temporary nature and are quickly obliterated. 
The exceptional nature of these floods, however, and 
the long intervals at which they are to be expected, 
remove them from among the agents which must be 
provided against in the construction of controlling 
works. 

C. W. Hayes. 



APPENDIX III.— HYDROGRAPHIC REPORT 



239 



Plotting all observations of discharge, so far 
taken as abscissas, with corresponding gage 
heights as ordinates, we obtain a curve indicating 
the relation of gage height to discharge, showing 
that the ratio of increase of discharge to increase 
of gage height is not constant. The curve is 
concave downward, tending toward a horizontal 
position, showing that the increase of discharge 
for increase of gage height is greater at high 
stages than at low stages, but above a medium 
stage of the river the line curves but slightly, 
and though the concavity is still downward, the 
curve approaches a straight line, or in other 
words, the ratio between gage height and dis- 
charge approaches constancy. If we assume as 
constant the direction given to the line by the 
higher measurements, and continue it upward as 
a straight line, we obtain as the discharge corre- 
sponding to A gage height of 28 feet, about 
200,000 cubic feet per second. (See Plate IX.) 

If any curvature be given the extrapolated 
portion of the curve it will increase this amount. 

If the same course of reasoning be applied to 
the flood-plain on the Eio San Carlos we find 
that its maximum discharge must be about 100,- 
000 cubic feet per second. 

Similarly it may be proved by extrapolating 
the curve discharge of the Eio San Juan at Fort 
San Carlos, that at the stage of 111 feet above 
sea level the lake must have discharged nearly 
50,000 cubic feet per second. 

When the measurement of November 17 that 



gave a discharge at Ochoa of 104,928 second- 
feet was made, the Eio San Carlos was discharge 
ing only 32,265, leaving 72,663 as the amount 
coming down the San Juan proper, of which 
probably not more than 28,663 were flowing 
from the lake, leaving 44,000 to be supplied by 
the small tributaries between the lake and Boca 
San Carlos. With such an indicated discharge, 
it would not be excessive to assume a maximum 
for these tributaries of 50,000 cubic feet per 
second, and we have the maximum flood at 
Ochoa made up as follows: 

Second-feet. 

Maximum Eio San Carlos 100,000 

Maximum discharge from lake . . . 50,000 
Maximum small tributaries 50,000 

Maximum at Ochoa 200,000 

The highest observed discharge of the Sara- 
piqui is 30,000 cubic feet per second. It is 
probable that the extreme maximum is not much 
less than 60,000 cubic feet per second. The 
Machado, San Francisco, Tamborcito and San 
Juanillo, and a large number of lesser creeks, 
contribute a large aggregate in time of flood, 
so that it is probable that at rare intervals the 
increment to the waters of the San Juan below 
Ochoa may amount to 100,000 cubic feet per 
second. Such an occurrence coincident with 
extreme flood conditions above Ochoa would 
make a total of 300,000 cubic feet per second 
discharging into the Caribbean through the 
various mouths of the San Juan. 



RATING TABLE FOR SAN JUAN RIVER AT OCHOA. 
This table is applicable only from January 1, 1898, to July 9, 1898. 



Gaffe 
hel^t. 


Dischangre. 


Oa^e 
height. 


Dischargre. 


Gage 
height. 


Discharge. 


Gage 

hei^t 


Discharge. 


Feet. 
4.0 
4.1 
4.2 
4.8 
4.4 


Seoond-ft. 
15,500 
15,750 
16,000 
16,250 
10,500 


Feet. 
4.5 
4.6 
4.7 
4.8 
4.9 


Second-ft. 
16,750 
17,010 
17,290 
17,590 
17,900 


Feet 

5.0 

5.1 

5.2 

5.8 

5.4 


Second-ft. 
18,220 
18,650 
18,890 
19,240 
19,590 


Feet. 
5.5 
5.6 
5.7 

5.8 
5.9 


Second-ft. 
19,950 
20,820 
20,690 
21,070 
21,460 



NICABAQUA CANAL COMMISSION 



Page halght. Dtocharge. 
Fe«t. S«cond-rt. 

6.0 31,H60 

33,370 
S3,RS0 
33,120 

M,5T0 
34,030 
34,SO0 
25,000 
3S,530 
36,080 
2H,6S0 



RATINQ TABLE FOR SAN JUAN RIVER AT OCHOA.— ConUnued. 



37,11 



,730 



29,380 
39,930 
30,480 
31,030 
31,SM0 
33,130 
33,680 
88,380 
83,790 



Gage height- Dlaoharge. 



3T,0IM) 
37,080 

38,1 HO 



Page height. Dlaohargc, 



Gage height. Dl»ch»igB. 





8ec«»<l-tt. 




3.6 


03,880 


49,180 


3.6 


63,030 


40,730 


3.7 


63,480 


60,380 


S.H 


64,030 




8.9 


64.580 


61,880 


4.0 


65,180 


B1,B80 




66,680 




4.3 


66,330 


63,080 


4.S 


66,780 


63,580 


4.4 


67,830 




4.6 


67,880 


64,680 


4.6 


68,430 


55,230 


4.7 


68,980 




4.8 


69,530 


56,830 


4.9 


70,080 


66,880 


5.0 


70,630 


57,480 


6.1 


71,180 




5.3 


71,730 


58,630 


6.3 


73,380 


5H,080 


6.4 


K,830 




5.5 


78,780 


60,180 


6.6 


73,080 


60,730 


5.7 


74,480 



RATING TABLE FOR SAN JUAN RIVER AT OCHOA. 
ThU table la appli cable only Jrom July 9, 1898. to December 51, 1898. 

_ Gage height. Dlachargn. Gage height. Discharg e . Bage height. IHat'hatge. 



16,000 
16,2.50 
16.600 
16,760 
17,010 
17,390 
17,590 
17,900 



30,330 
30,690 
31,070 



30,480 
31,030 
31,580 
32,180 
82,680 
33,330 
33,780 



36,980 
86,630 
37,080 
37,830 



SecoDd-ft. 

.no.eoo 

51,300 

52,100 
.53,900 
63,700 

65i300 
66,160 
57,000 
57,850 
58,700 
59,550 
60,400 
61,250 
63,100 
82,1150 
68,800 
64,650 
65,500 
06,350 
67,300 
68,050 



83,100 
83,000 
83,000 
84,800 
86,700 
86,600 
87,500 
88,400 
89,300 
90,300 
91,100 
92,000 
93,900 
93,800 
94,700 
95,600 



47,100 
47,750 

48,400 



105,500 
106,400 
107,300 



NICARAGUA CANAL COMMISSION 



^...„„. ..... -..=. ..,. 


.UCU,T 


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If ^ 








' t 

J - . ..( 


"^:T"1"""""^'""::;: 


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- 1 1 Ul — Mill INN -LLLll 



DIAGRAM OF THE DAILY MEAN DISCHARGE IN CUBIC FEET 



PER SECOND OF THE RIO SAN JUANlMI 



1 






APPENDiX 3, PLATE X 












... _ _ 




r 
















1 






























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.BALOS AND AT OCHOA; ALSO OF THE RIO SAN CARLOS AT 3 MILES ABOVE ITS MOUTH, 189a-18M. 



APPENDIX 111.— HYDROGRAPHIC REPORT 



241 



RATING TABLE FOR SAN JUAN RIVER AT OCHOA. 
This table is applicable only from January 1, 1899, to March 31, 1899. 



Qage 
heignt. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second- ft. 


Feet. 


SecoDd-ft, 


Feet. 


Second-ft. 


Feet. 


Second-ft, 


6.7 


23,900 


7.6 


31,800 


9.5 


42,560 


11.4 


53,450 


5.8 


24,300 


7.7 


82,310 


9.6 


43,120 


11.5 


54,060 


6.9 


24,700 


7.8 


32 860 


9.7 


43,690 


11.6 


54,680 


6.0 


25,100 


7.9 


83,430 


9.8 


44,200 


11.7 


55,320 


6.1 


25,500 


8.0 


34,000 


9.9 


44,830 


11.8 


55,980 


6.3 


25,900 


8.1 


34,570 


10.0 


45,400 


11.9 


56,660 


6.3 


26,300 


8.2 


35,140 


10.1 


45,970 


12.0 


67,380 


6.4 


26,700 


8.3 


35,710 


10.2 


46,540 


12.1 


58,130 


6.5 


27,100 


8.4 


86,280 


10.3 


47,110 


12.2 


58,910 


6.6 


27,500 


8.5 


36,850 


10.4 


47,680 


12.3 


59,700 


6.7 


27,900 


8.6 


37,420 


10.5 


48,250 


12.4 


60,500 


6.8 


28,300 


8.7 . 


87,990 


10.6 


48,820 


12.5 


61,810 


6.9 


28,700 


8.8 


88,560 


10.7 


49,890 


12.6 


62,130 


7.0 


29,100 


8.9 


89,130 


10.8 


49,960 


12.7 


62,960 


7.1 


29,500 


9.0 


39,700 


10.9 


50,530 


12.8 


68,800 


7.2 


29,950 


9.1 


40,270 


11.0 


51,100 


12.9 


64,650 


7.8 


80,400 


9.2 


40,840 


11.1 


51,680 


13.0 


66,.500 


7.4 


30,850 


9.3 


41,410 


11.2 


52,260 






7.5 


81,300 


9.4 


41,980 


11.8 


62,850 







ESTIMATED MONTHLY DISCHARGE OF SAN JUAN RIVER AT OCHOA. 



Month. 



Discharge in Second-Feet. 



Maximum. Minimum. Mean. 



1898. 

January 76,200 32,240 

February 68,530 26,080 

March 30,650 20,140 

April 40,380 17,290 

May 34,880 16,300 

June 60,180 18,890 

July 78,050 85,540 

August 64,100 32,020 

September... 54,100 30,920 



45,250 
85,400 
23,800 
21,150 
19,640 
33,140 
46,810 
37,230 
39,530 



Total for 

Month in 

Acre- Feet, 



2,782,300 
1,966,000 
1,463,400 
1,258, ,510 
1,207,600 
1,971,970 
2,878,200 
2,289,200 
2,362,200 

18,169,380 



Month. 



Discharge in Second-Feet. 

/ • — » 

Maximum. Minimum. Mean. 



Total for 

Month in 

Acre-Feet. 



1898. 

October 67,625 

November 107,000 

December 65,000 

Total for 1898 . . 



Brought forward, 18,169,380 
84,600 42,200 ^,,594,800 
87,080 51,890 3,087,670 
32,790 40,850 2,511,770 

..26,363,620 



1899. 

January 49,100 

February 41,120 

March. 81,300 



32,000 39,666 2,438,900 
29,840 32,540 1,807,180 
28,900 26,940 1,666,480 



16 



242 



NICARAGUA CANAL COMMISSION 



Rio Machado. 

The observer at Ochoa also made occasional measurements of the discharge of the Rio Machado^ 
which are given below: 

LIST OF DISCHARGE MEASUREMENTS. 
Made on Rio Machado two miles above its mouth. 



Date. 


Hydrographer. 


Meter 
number. 


Gage 

height 

(feet). 


Area of 

section 

(sq. feet). 


Mean 
velocity (ft. 
per second). 


Discharge 
(second- 
feet). 


Remarks. 


1898. 
Mar. 3.. 


G. R. Wadlelgh.. 


1985 


5.34 


244 


0.59 


144 






«» 16.. 


** 14 


1985 


5.10 


212 


0.57 


121 






Apr. 2 . 


(( tt 


1985 


4.90 


221 


0.46 


102 






" 6.. 


(( tt 


1985 


7.87 


400 


1.28 


514 






May 27.. 


t( tt 


1985 


5.20 


229 


0.60 


187 






Jun. 8.. 


tt tt 


1985 


6.32 


293 


0.94 


276 






•* 20.. 


tt tt 


1985 


7.66 


863 


0.76 


277 






»» 30.. 


tt tt 


1985 


7.72 


258 


1.12 


284 


New Station, 1 mile 


July 9.. 
" 14.. 


It it 

it tt 


1985 
1985 


9.22 
7.11 


344 
230 


1.3^ 
1.06 


462 
244 


it 


" [above. 

it 


*» 21.. 


tt tt 


1985 


8.86 


812 


1.37 


428 


tt 


it 


Aug. 8.. 


tt tt 


1985 


7.41 


238 


1.15 


267 


tt 


it 


" 5.. 


it it 


1985 


6.88 


203 


1.02 


208 


it 


it 


♦* 13.. 


....G. H. Williams.. 


1985 


7.06 


212 


1.09 


233 


it 


tt 


" 17.. 


it tt 


1985 


6.74 


201 


1.02 


206 


tt 


ti 


" 19.. 


ft it 


1985 


6.44 


185 


0.92 


170 


tt 


tt 


Sep. 5 . . 


tt tt 


65 


5.80 


226 


0.65 


148 


Lower, 


or Old Station. 


" 24.. 


it it 


65 


6.30 


167 


1.02 


170 


Upper 


Station. 


Oct. 6.. 


it it 


65 


6.34 


163 


1.06 


172 


ft 


it 


»* 11.. 


it it 


65 


5.83 


145 


0.89 


128 


it 


it 


** 19.. 


ft it 


65 


6.08 


153 


0.87 


133 


it 


it 


Nov. 7 . . 


C. Ilayman 


65 


5.48 


132 


0.79 


104 


It 


it 


** 15.. 


it it 




65 


6.18 


160 


0.87 


139 


it 


ft 


" 21.. 


it it 




65 


6.80 


196 


1.11 


218 


it 


it 


»* 29.. 


tt tt 




65 


7.67 


250 


1.37 


343 


it 


it 


Dec. 7 . . 


tt it 




65 


7.05 


213 


1.31 


279 


it 


ft 


" 17.. 


it it 




65 


6.74 


190 


1.09 


208 


it 


tt 


" 27.. 


ft tt 




65 


5.60 


143 


0.79 


113 


it 


it 


" 31.. 
1899. 
Jan. 2 . . 


.... ** ** 
H. 8. Reed., 




65 
65 


5.73 
8.00 


146 
253 


0.87 
1.51 


127 
382 


it 
it 


it 
it 


" 10.. 


tt tt 




65 


6.75 


193 


1.14 


221 


it 


it 


" 14.. 


tt if 




65 


7.69 


246 


1.46 


361 


it 


it 


** 24.. 


.... ** ** 




65 

65 


6.57 
5.98 


189 

278 


1.02 
0.87 


192 
242 


it 
Lower 


it 


" 24.. 


it it 


Station. 


** 31.. 
Feb. 6.. 


tt it 
it it 




65 
65 


5.78 
5.52 


155 
148 


0.78 
0.68 


121 
101 


Upper Station. 

it it 


»* 14.. 


.... ** ** 




65 


5.47 


144 


0.66 


95 


it 




" 17.. 


it it 




65 


6.06 


171 


0.86 


147 


tt 




" 20.. 


tt it 




65 


6.80 


177 


0.99 


176 


tt 




" 27.. 


tt it 




65 
65 


5.40 
5.30 


140 
134 


0.67 
0.59 


93 
79 


tt 
tt 




Mar. 4 . . 


it it 




»* 21.. 


tt it 




65 


4.50 


204 


0.46 


93 


Lower Station. 


" 30.. 


. . '* " 




65 


4.25 


186 


0.42 


77 


it 


it 



APPENDIX III.— HYDROGRAPHIC REPORT 



243 



Eio Danta. 

This stream is the outlet of the Florida la- 
goon, and flows into Kio San Juan about a mile 
above the mouth of the San Francisco. Its 
channel is narrow and deep, and contains con- 
siderable fallen timber, but is not subject to 



sudden changes of cross section. The current is 
usually sluggish, and is sometimes affected by the 
stage of water in Rio San Juan. 

A gage was established on February 28, about 
IJ miles above its mouth, and the following 
measurements of discharge have been made: 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO DANTA 1% MILES 

ABOVE MOUTH. 



Bate. 



Hydroffrapher. 



it 



t( 27 

July 8 ** 

*» 19 *» 

«* 28 " 

Aug. 8 ** 

** 18 *♦ 

" 28 *♦ 

Sep. 8 ** 

44 27 ** 

Oct. 8 A. Ahrling. 



44 
«4 
44 
44 
44 
44 
44 
4i 
4i 



»« 18 " 

*« 29 ** 

Nov. 7 «» 

«* 18 ** 

i« 28 »* 

Dec. 8 ** 

«* 17 " 



44 
44 
44 
44 
44 
44 
44 



Meter Qage height 
number. (feet). 



Area of 
section 
(sq. ft). 



;^S^. 5^s»- 



1898. 

Feb. 28 W. W. Schlecht 

Mar. 8 ** *' 

" 18 *' 

*» 28 " 

Apr. 9 »» 

" 28 ** 

JuD. 15 C. Hay man, 



98 


8.98 


134 


1.03 


188 


93 


8.22 


110 


0.82 


91 


93 


2.12 


82 


0.58 


47 


98 


2.97 


102 


0.86 


88 


98 


4.23 


148 


1.07 


159 


98 


2.24 


76 


0.70 


58 


98 


3.65 


80 


1.31 


106 


98 


7.45 


803 


1.08 


828 


98 


6.17 


195 


0.82 


161 


98 


5.11 


151 


0.59 


94 


98 


5.28 


165 


0.90 


149 


98 


4.63 


■ 147 


0.80 


118 


98 


4.48 


135 


0.90 


121 


98 


4.21 


125 


0.84 


104 


93 


8.55 


94 


0.64 


60 


98 


6.08 


162 


0.60 


98 


98 


8.73 


108 


0.53 


67 


98 


5.65 


188 


0.12 


28 


98 


5.19 


156 


0.33 


52 


93 


4.01 


115 


0.86 


42 


98 


11.60 


432 


1.27 


549 


93 


7.18 


231 


0.82 


190 


93 


4.75 


142 


0.68 


82 


93 


5.99 


193 


0.87 


71 



Backwater from San Juan. 



Kio San Fbancisco. 

The Canal Company's project provides for the 
construction of large embankments across the 
valleys of the Limpio, Chanchos, Nicholson, San 
Francisco and Danta, and involves the control 
of these streams, during construction, and re- 
ceiving their discharge into the canal after com- 
pletion. Their permanent control is also nec- 



cssarv if the canal is to follow the San Juan val- 
ley. A knowledge of their volume and fluctua- 
tions, as well as of the rainfall of the region, is 
therefore neeessarv. 

The Rio San Francisco has its source on the 
southwestern slope of the range of hills known 
as the Eastern Divide, north of San Juan river. 
Its principal tributary is the Rio Chanchos, 



244 



NICARAGUA CANAL COMMISSION 



which in turn receives the waters of Rio Limpio. 
The valley of the San Francisco is crossed by the 
proposed upper line of the canal, which follows 
for a considerable distance the valleys of the 
Chanchos and Limpio. The drainage area has 
never been definitely outlined and only meager 
information exists as to its extent. It is esti- 
mated, however, at about 65 square miles. The 
maximum discharge yet observed for the San 
Francisco above the confluence of Nicholson 
creek and Eio Chanchos is 866 cubic feet per 
second. A discharge of 888 cubic feet per 
second has been obser\^ed for the Chanchos and 
100 for Nicholson creek. This would indicate 
a maximum during the time of observation of 
something less than 2000 for the San Francisco 
at its mouth. A rough tentative estimate based 
upon these figures and upon the greatest rainfall 
probable in this country would place the extreme 
maximum discharge which can occur at the 
mouth of the San Francisco at less than 4000 
cubic feet per second. The certainty that this 
figure is ample is greatly strengthened by the 
nature of the lower portion of the San Fran- 



cisco drainage basin, which includes a large area 
of perfectly flat land, which would be flooded in 
case of a discharge of 3000 cubic feet per 
second in the San Francisco, and which would act 
as a storage basin for floods exceeding that 
amount until they could be discharged through 
the channel of the river. 

San Fran4^isco Station. — On January 2 a 
station was established near the line of the pro- 
posed canal, about two miles by the river, above 
the crossing of the embankment line, and above 
the mouth of the Canon Surprise. 

On February 21 a gage rod was placed in the 
river at the crossing of the embankment line, 
and thereafter observations were taken at this 
point, which is below the mouth of Caiion Sur- 
prise. The channel is narrow and deep, is com- 
posed of hard clay and is not subject to change. 

Measurements are given below for both sta- 
tions; rating tables have been constructed, and 
daily discharges estimated for both, which are 
given below. Eainfall and hygrometer obser- 
vations have also been taken. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO SAN FRANCISCO AT CENTER 

LINE OF CANAL. 



Date. Hydrogrrapher. 


Meter 
number. 


Gage 
height 
(feet). 


Area of 

section 

(sq. feet). 


Mean 
velocity (ft. 
per second). 


Discharge 
(second- 
feet). 


Remarks. 


Jan. 19 W. W. 


Schlecht. . . 


93 


18.52 


810 


1.02 


819 


Upper 


Station. 


" 23 " 


»' 


93 


15.12 


873 


1.19 


445 


tt 




** 25 •* 


... 


93 


11.97 


228 


0.91 


208 


ti 




Feb. 3 N. P. Leary 


93 


15 . 83 


407 


1.16 


471 


{( 




♦* 10 ** 




98 


12.75 


264 


0.88 


220 


ti 




** 20 «♦ 


" 


93 


10.60 


168 


0.74 


124 


it 




Mar. 2 W. W. 


Schlecht. . . 


93 


10.86 


174 


0.74 


128 


it 




" 10 *« 




93 


11.78 


217 


0.85 


184 


it 




*« 19 »« 




93 


9.77 


180 


0.61 


80 


it 




** 29 




93 


10.26 


149 


0.68 


101 


ft 




Apr. 6 ♦' 




93 


15.90 


897 


1.54 


610 


it 




" 6 




93 


16.48 


429 


1.32 


569 


it 




" 20 " 


• i 


93 


9.82 


134 


0.60 


81 


it 




" 30 


it 

• * • 


93 


C.86 


113 


0.59 


67 


it 





APPENDIX III.— HYDROGRAPHIC REPORT 



245 



Gage 

height. 



RATING TABLE FOR RIO SAN FRANCISCO AT CENTER LINE OF CANAL. 



Discharge. 



Gage 
height 



Discharge. 



Gage 
height. 



Discharge. 



liage 
height 



Discharge. 



Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet, 


Second-ft. 


Feet. 


Second-ft. 


8.6 


40 


10.8 


138 


13.0 


378 


15.3 


455 


8.7 


48 


10.9 


183 


13.1 


386 


15.8 


464 


8.8 


46 


11.0 


138 


13.3 


394 


15.4 


473 


8.9 


49 


11.1 


144 


13.3 


303 


15.5 


483 


9.0 


53 


11.3 


150 


13.4 


810 


15.6 


491 


9.1 


55 


11.8 


156 


13.5 


818 


15.7 


500 


9.3 


58 


114 


163 


13.6 


336 


15.8 


509 


9.3 


61 


11.5 


168 


13.7 


884 


15.9 


518 


9.4 


64 


11.6 


174 


13.8 


343 


16.0 


537 


9.5 


68 


11.7 


180 


18.9 


S60 


16.1 


536 


9.6 


73 


11.8 


186 


14.0 


358 


16.3 


545 


9.7 


76 


11.9 


198 


14.1 


366 


16.8 


554 


9.8 


80 


13.0 


300 


14.3 


374 


16.4 


568 


9.9 


84 


12.1 


307 


14.8 


383 


16.5 


573 


10.0 


88 


12.3 


314 


14.4 


390 


16.6 


581 


10.1 


98 


13.8 


333 


14.5 


898 


16.7 


590 


10.2 


98 


13.4 


330 


14.6 


406 


16.8 


599 


10.8 


103 


13.5 


338 


14.7 


414 


16.9 


608 


10.4 


108 


13.6 


346 


14.8 


433 


17.0 


617 


10.5 


113 


13.7 


354 


14.9 


430 


17.1 


636 


10.6 


118 


13.8 


363 


15.0 


438 


17.3 


635 


10.7 


123 


13.9 


370 


15.1 


446 


17.3 


644 



DAILY GAGE HEIGHT OF RIO SAN FRANCISCO NEAR LINE OF EMBANKMENTS FOR 1898. 



Day. 



1. 

3 

8 



6, 
7. 
8. 
9. 
10. 

11, 
13. 
18. 
14. 
15. 



.Ian. 



15.30 
15.40 
15.85 
15.16 



13.85 
15.38 
14.35 
13.83 
14.10 

13.98 
13.83 
13.07 
11.65 



16 13.81 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

80 



13.95 
15.48 
13.53 
13.55 

13.31 
15.14 
13.55 

ii!99 

11.85 
13.05 
11.45 
11.60 
11.51 
81 1 11.20 



Feb. 



11.00 
14.91 
15.88 
15.61 
17.13 



10.51 
14.30 
14.41 
14.13 
13.75 

13.40 
12.10 
13.50 
11.70 
11.81 

11.03 
10.95 
10.84 
10.79 
10.60 

5.55 
5.44 
5.74 
5.31 
5.37 

5.88 
6.71 
8.86 



Mar. 



6.76 
6.13 
5.59 
5.41 
8.03 



8.33 
6.39 
6.07 
7.36 
7.60 

6.05 
5.00 
5.36 
5.11 
4.93 

4.83 
4.80 
4.68 
4.55 
4.47 

4.47 
4.59 
4.65 

4.48 
5.30 

6.46 
5.91 
6.35 
5.27 
4.89 
4.70 



Apr. 



4.58 
4.43 
4.29 
4.55 
10.27 



11.63 
8.05 
7.81 
6.38 
5.78 

5.61 
6.19 
5.59 
5.13 
4.91 

4.70 
4.54 
4.60 
4.80 
4.59 

4.35 
4.39 
5.76 
5.83 
4.75 

4.48 
4.79 
4.50 
4.38 
4.11 



Bfay. 



4.46 
5.66 
4.74 
4.64 

7.17 



6.54 
5.98 
5.07 
4.77 
4 63 

5.69 
6.93 
5.45 
4.96 
4.89 

5.87 
5.05 
5.56 
5.03 
8.07 

9.24 
9.79 
7.80 
6.67 
5.91 

5.45 
5.86 
5.37 
4.98 
5.48 
5.77 



Jun. 



7.34 
5.87 
5.33 
4.94 
4.73 



4.53 
4.63 
4.93 
5.06 
4.48 

4.61 
4.47 
7.04 
7.79 
6.36 

5.77 
5.33 
5.88 
8.93 
7.75 

9.83 
8.05 
7.54 
9.95 
11.63 

10.39 
11.38 
10.85 
11.83 
10.39 



July. 






9.85 
11.80 
13.43 
13.06 
12.37 



11.37 

9.46 

8.96 

10.83 

11.06 

10.95 
9.44 
8.65 
7.91 
7.48 

6.89 
6.77 
6.81 
8.60 
9.89 

11.03 

13.85 

10.37 

8.73 

9.03 

9.33 
8.49 
8.46 
8.04 
7.73 
7.65 



Aug. 



8.13 
9.75 
9.33 
8.39 

7.83 



7.50 
7.35 
8.69 
8.46 
8.63 

7.70 
8.35 
8.80 
10.83 
9.48 

8.50 
7.41 
7.31 
6.56 
6.48 

6.34 
6.38 
6.69 
7.14 
6.61 

6.70 
6.76 
6.64 
6.01 
5.77 
5.66 



Sept. 



5.96 
5.88 
5.56 
5.55 
5.29 



5.33 
5.84 
5.23 
5.36 
5.20 

8.90 

6.89 

11.44 

10.81 

8.59 

8.63 
7.70 
7.39 
6.44 
6.33 

6.49 
6.59 
11.46 
8.67 
7.47 

9.44 
7.93 
7.45 
6.56 
6.07 



Oct, 



Nov. 



6.19 
8.87 
6.88 
6.85 
6.50 



0.31 
5.i)5 
6.05 
6.47 
6.06 

5.73 
6.15 
6.96 
6.56 
5.82 

5.70 
5.68 
6.57 
9.18 
7.90 

7.40 
7.70 
7.38 
8.39 
7.50 

8.70 
8.30 
7.31 
6.60 



5.93 
5., 55 
5.34 
5.39 
5.46 



5.53 

7.15 

10.45 

8.48 

7.56 

7.33 
6.99 
8.86 
10.93 
9.65 

12.45 
15.43 
15.20 
13.47 
11.80 

10.23 
8.89 
8.16 
7.59 
7.66 

8.40 

9.55 

11.55 

11.47 



Dec. 



9.18 
9.33 
8.40 
7.86 
7.53 



7.70 
8.37 
7.40 
7.46 
9.10 

11.53 

10.65 

9.05 

7.90 

7.48 

7.03 
8.00 
7.48 
6.67 
6.35 

6.00 
5.83 
5.69 
5.50 
5.33 

5.43 
5.38 
5.84 



NoTB.— From Jannary 3 to February 30 inclnsiye, rod read above CafioD Surprise. On February 30, rod moyed to 
below the Cafion. 



NICARAGUA CANAL COMMISSION 



LIST OF DISCHAEQB MEASUEEMBNT3 MADE ON RIO SAN PRANCISCO AT UNB OF 
EMBANKMENTS. 



hei«ht 
(feet). 



Lower St&tlon. 



APPENDIX III.— HYDROGRAPHIC REPORT 



247 



RATING TABLE FOR RIO SAN FRANCISCO AT LINE OF EMBANKMENTS. 
This table is applicable only from February 24, 1898, to October 16, 1898. 



Gage height. 


Discharge. 


Gage height. 


Discharge. 


Gage height. 


Discharge. 


Gage height. 


Discharge. 


Feet 


Second-ft. 


Feet, 


Seoond-ft. 


Feet. 


Second-ft. 


Feet, 


Second-ft. 


4.0 


63 


6.5 


163 


• 9.0 


825 


11.6 


603 


4.1 


65 


6.6 


167 


9.1 


834 


11.6 


614 


4.2 


68 


6.7 


173 


9.2 


843 


11.7 


636 


4.3 


71 


6.8 


178 


9.8 


352 


11.8 


638 


4.4 


74 


6.9 


184 


9.4 


362 


11.9 


650 


4.5 


77 


7.0 


190 


9.5 


372 


12.0 


662 


4.6 


80 


7.1 


196 


9.6 


383 


12.1 


674 


4.7 


88 


7.2 


203 


9.7 


894 


12.2 


686. 


4.8 


86 


7.8 


208 


9.8 


405 


12.3 


698 


4.9 


89 


7.4 


214 


9.9 


416 


12.4 


710 


6.0 


98 


7.5 


220 


10.0 


427 


12.5 


733 


6.1 


97 


7.6 


226 


10.1 


438 


12.6 


734 


5.2 


101 


7.7 


232 


10.2 


449 


12.7 


746 


5.8 


105 


7.8 


238 


10.3 


460 


12.8 


768 


5.4 


109 


7.9 


244 


10.4 


471 


12.9 


770 


5.5 


113 


8.0 


250 


10.5 


482 


18.0 


783 


5.6 


117 


8.1 


257 


10.6 


494 


18.1 


794 


5.7 


123 


8.2 


264 


10.7 


506 


13.2 


806 


5.8 


137 


8.8 


271 


10.8 


518 


13.8 


818 


5.9 


132 


8.4 


278 


10.9 


530 


13.4 


880 


6.0 


187 


8.5 


285 


11.0 


542 


18.5 


842 


6.1 


142 


8.6 


298 


11.1 


554 


13.6 


854 


6.2 


147 


8.7 


801 


11.2 


566 


13.7 


866 


6.8 


152 


8.8 


809 


11.8 


578 






6.4 


157 


8.9 


317 


11.4 


590 







RATING TABLE FOR RIO SAN FRANCISCO AT LINE OF EMBANKMENTS. 
This table is applicable only from Oct. 16, 1898, to November 30, 1898. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Disctiarge. 


Gage 
height 


Discharge. 


Feet. 


Second-ft. 


Feet. 


Seoond-ft. 


Feet. 


Second-ft. 


Feet 


Second-ft 


5.0 


40 


7.7 


188 


10.4 


360 


18.1 


556 


6.1 


45 


7.8 


189 


10.5 


867 


13.3 


564 


6.2 


50 


7.9 


195 


10.6 


874 


18.8 


573 


6.3 


65 


8.0 


201 


10.7 


881 


13.4 


580 


5.4 


60 


8.1 


207 


10.8 


888 


13.5 


688 


5.5 


65 


8.2 


218 


10.9 


895 


18.6 


596 


5.6 


70 


8.8 


219 


11.0 


402 


18.7 


604 


5.7 


76 


8.4 


225 


11.1 


409 


18.8 


613 


5.8 


80 


8.5 


231 


11.2 


416 


18.9 


630 


5.9 


85 


8.6 


237 


11.3 


428 


14.0 


638 


6.0 


90 


8.7 


248 


11.4 


430 


14.1 


636 


6.1 


95 


8.8 


249 


11.5 


437 


14.3 


644 


6.2 


100 


8.9 


255 


11.6 


444 


14.3 


652 


6.8 


105 


9.0 


262 


11.7 


451 


14.4 


660 


6.4 


110 


9.1 


269 


11.8 


458 


14.5 


668 


6.5 


115 


9.2 


276 


11.9 


465 


14.6 


676 


6.6 


120 


9.8 


283 


12.0 


472 


14.7 


684 


6.7 


125 


9.4 


290 


12.1 


479 


14.8 


692 


6.8 


180 


9.5 


297 


13.3 


486 


14.9 


700 


6.9 


185 


9.6 


304 


13.3 


493 


15.0 


708 


7.0 


141 


9.7 


811 


13.4 


500 


15.1 


716 


7.1 


147 


9.8 


818 


12.5 


508 


15.3 


734 


7.2 


153 


9.9 


825 


12.6 


516 


15.8 


782 


7.8 


159 


10.0 


882 


12.7 


634 


15.4 


740 


7.4 


165 


10.1 


839 


12.8 


533 


15.5 


748 


7.5 


171 


10.2 


846 


12.9 


540 






7.6 


177 


10.8 


853 


13.0 


548 







248 



NICARAGUA CANAL COMMISSION 



ESTIMATED MONTHLY DISCHAROES OF RIO SAN FRANCISCO AT LINE OF EHBANKMBNTS. 



Month. _Dl;KbargelnSo™nd-F«*t.^ ^oWl in 


Month 


Dlichaive in Secirnd 


-Feet. 
Mean. 


^iSt. 



February . 

March 

April .... 

M«r 



Brought forward, 72,000 

Jnly Setl 170 407 25,035 

August 54S 120 230 14,510 

Seylember 595 103 320 13,090 

October 313 75 163 9,980 

KoTcmher 745 57 379 18,000 

December (1-3IS) . . 005 105 333 13,940 

Total 104,135 



lit 



w'fflwniii 



lliiilr 



Diagram of dally discharge ot the Rio San Francisco at Embankment Line. 



Kio LiMPlO. 

On JaDuaiy 6 a gage was placed on the left 
bank of the limpio about 200 yards above its 
mouth. It consists of a vertical plank driven in 
the bed of the stream, and spiked to a tree grow- 
ing in the bank. 

Three 60-penny nails driven into the tree to 
which the gage is fastened, and projecting about 



one inch, mark the elevation of eleven feet above 
datum. 

Current meter measurements were made from 
the trunk of a tree felled across the river. 

From January 17 daily observationa were 
taken at this point until February 20, alter 
which observations were taken two or three 
times per month. 



APPENDIX III.— HYDROGRAPHIC REPORT 



249 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO LIMPIO NEAR ITS MOUTH. 



Date. 

1868. 


Hydrographer. 


Meter 
number. 


Gage 

height 

(feet). 


Area of 
section 
(square ft.). 


Mean ve- 
locity (feet 
per second). 


Discharge 

(second- Remarks, 
feet). 


Jan. 

44 


31 

38 

3. . . . 

11 

19 

12 

23 

12 

23 

14.... 
24 

4.... 
14.... 
34. . . . 

3.... 
18.... 
38 

8.... 
13.... 
38.... 

8. . . . 
14.... 
33 

4 

18.... 
33 

3.... 
12.... 
14.... 
23.... 

3.... 
18.... 
37.... 


....H. 8. 
. . . . ** 

. . . . •* 
. . . . ** 
. . . . ** 
.... ** 

(4 
44 

.V..C. H 

14 

. . . . ** 

44 

44 

44 
44 
44 
44 
44 
44 
«4 
44 
44 

!*.*.!Aif. 

44 

. . . . ** 

44 

44 

44 
44 
44 
(4 
44 


Keed 

44 


Stk. 3 
Stk. 3 


6.20 
4.27 
9.80 
4.76 
8.88 
4.08 
8.85 
4.05 
8.94 
3.80 
3.83 
3.60 
3.72 
3.45 
7.96 
4.11 
6.29 
5.42 
5.04 
4.20 
8.49 
6.02 
7.19 
4.38 
4.17 
4.60 
3.51 
3.93 
.5.24 
4.48 
4.60 
5.22 
3.51 


76 
84 

200 
42 
22 
30 
15 
30 
31 
25 
34 
32 
21 
16 

116 
20 
42 
53 
48 
84 
19 
46 

118 
34 
33 
41 
18 
80 
48 
87 
36 
46 
18 


1.31 
0.93 
0.39 
0.94 
1.15 
0.99 
1.14 
1.08 
1.05 
0.92 
1.10 
0.95 
0.89 
0.69 
0.52 
1.08 
1.05 
0.76 
1.10 
1.44 
1.28 
0.77 
0.32 
0.51 
0.56 
0.66 
0.88 
0.73 
0.79 
0.78 
1.08 
1.02 
0.88 


100 
82 


Feb. 

44 
44 

Mar. 

44 

Apr. 

44 

May 

44 


V. Schlecht 

44 

44 

44 

44 

44 
44 

ayman 


Stk. 3 
Stk. 3 
Stk. 3 
98 
93 
98 
98 
98 


78 Backwater. 

40 

25 

80 

17 

32 

22 

23 


44 


98 


25 


■Tnne 


44 


93 


22 


44 


(4 


93 


19 


44 


i4 


98 


11 


July 

44 


44 


98 


60 


(4 


98 


23 


44 


41 


98 


44 


Aug. 

44 


44 


98 


41 


4t 


93 


48 


44 


44 


93 


51 


Sep. 

44 


44 


93 


34 


44 


93 


35 


44 


44 


93 


88 Backwater. 


Oct. 

44 


Ahrling 

44 . , . 


93 
93 


20 
18 


44 


44 .... 


98 


29 


Nov. 


4( 


93 


16 


44 


44 


93 


23 


44 


44 


98 


38 


44 


4( 


93 


29 


Dec. 


44 , , 


93 


39 


44 


44 


93 


47 


^4 


44 


93 


16 











RATING TABLE FOR RIO LIMPIO 100 YARDS ABOVE ITS MOUTH. 
This table is applicable only from January 6, 1898, to February 20, 1898. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second-ft. 


Feet. 


6econd-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


2.9 


11 


4.7 


38 


6.5 


105 


8.8 


195 


3.0 


12 


4.8 


40 


6.6 


110 


8.4 


200 


3.1 


18 


4.9 


48 


6.7 


115 


8.5 


205 


8.2 


14 


6.0 


46 


6.8 


120 


8.6 


310 


8.3 


15 


5.1 


49 


6.9 


125 


8.7 


316 


8.4 


16 


5.3 


53 


7.0 


130 


8.8 


320 


3.5 


17 


5.3 


56 


7.1 


135 


8.9 


235 


8.6 


18 


5.4 


60 


7.2 


140 


9.0 


330 


8.7 


19 


6.5 


64 


7.8 


145 


9.1 


386 


3.8 


20 


5.6 


68 


7.4 


150 


9.2 


340 


3.9 


33 


5.7 


72 


7.5 


1.55 


9.3 


346 


4.0 


34 


5.8 


76 


7.6 


160 


9.4 


350 


4.1 


36 


5.9 


80 


7.7 


165 


9.5 


255 


4.2 


38 


6.0 


84 


7.8 


170 


9.6 


260 


4.8 


80 


6.1 


88 


7.9 


175 


9.7 


265 


4.4 


S3 


6.3 


92 


8.0 


180 


9.8 


270 


4.5 


84 


6.8 


96 


8.1 


185 


9.9 


275 


4.6 


86 


6.4 


100 


8.2 


190 


10.0 


380 



250 



NICARAGUA CANAL COMMISSION 



ESTIMATED MONTHLY DISCHARGE OF RIO LIMPIO 100 YARDS ABOVE ITS MOUTH. 



Month. 


Discharge In Second-Feet. Total in 
Maximum. Minimum. Mean. '^*^^^^®®** 


Month. 


Dischargre in Second-Feet. Total In 
Maximum. Minimum. Mean. -^°'^^®®*' 


Jannaryf 1898. 
(6-31) 


168 22 56 2,775 


February, 1898. 
(1 to20incl.). 


.. 283 20 82 3,250 



Upper Station on the Rio Chanchos. 

On January 17 a gage was placed on the right 
bank of the Chanchos, about 200 yards above 
the mouth of Eio Limpio. It consists of a ver- 
tical pine board, marked in feet and tenths, 
driven into the bed of the stream and spiked to 
a tree growing in the bank. Bench mark con- 
sists of three 60-penny nails driven in the tree 



to which gage was fastened, at 13-foot mark, 
projecting about three inches. Gagings were 

made bv current meter from the trunk of a tree 

t/ 

felled across the stream. 

Daily observations were taken at this point 
until Februarv 20, after which observations were 
taken two or three times a month. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO CHANCHOS AT UPPER STATION. 

Remarks. 



Date. 

1896. 


Hydrographer. 


Meter 
number. 


Qage 
hei{?ht 
(feet). 


Area of 

section 

(sq. feet). 


Mean ve- 
locity (feet 
per sec.) 


Discharge 
(second- 
feet). 


Jan. 


21 


..H. S. 


Reed 


Stk. 2 


6.07 


245 


0.92 


226 


it 


28.... 
0. . . • 


..W. W 


ti 


Stk. 2 
Stk. 2 


2.65 
8.00 


90 
334 


0.48 
0.96 


43 


Feb. 


. Schlecht 


321 


tt 


11..-. 


It 




Stk. 2 


3.30 


115 


0.64 


74 


ti 


19.... 


it 




Stk. 2 


2.26 


70 


0.53 


37 


Mar. 


12 


tt 




93 


2.54 


80 


0.62 


49 


C( 


23.... 


tt 




93 


1.67 


50 


0.46 


23 


Apr. 


12 


it 




93 


2.48 


78 


0.60 


47 


it 


28.... 


tt 




93 


2.50 


78 


0.60 


47 


May 


14 


. . C. Havman 


93 


2.21 


66 


0.58 


38 


24.... 

4.... 

14 

24 

2.... 

13 

28 

3.... 
13.... 
28.... 

o. . . . 


tt 
ti 
it 
it 
tt 
tt 
it 
tt 
ti 
tt 
tt 


tt 


93 
93 
93 
93 
93 
93 
93 
93 
93 
93 
93 


2.34 
1.78 
2.05 
1.92 
6.68 
2.60 
3.87 
4.10 
3.56 
2.21 
1.78 


76 

46 

52 

53 

243 

73 

121 

136 

112 

64 

46 


0.64 
0.46 
0.63 
0.55 
1.22 
0.63 
0.75 
0.89 
0.69 
0.65 
0.47 


48 


June 


tt 


22 


t( 


it 


38 


it 


it 


29 


July 

tt 


tt 


297 


tt 


46 


ii 


tt 


91 


Aug. 
it 


tt 


121 


ft 


77 


it 


it 


42 


Sept. 


ti 

\,' • ' • 


23 


ti 


14. . . . 
28 

4.... 
13.... 
22. . . . 

2.... 
12. . . . 
14.... 
22.... 

8.... 
13.... 
27.... 


tt 
t( 
tt 
tt 
tt 

. . tt 
tt 
it 

, , it 
tt 
tt 
tt 


ti 


93 
93 
93 
93 
83 
93 
93 
93 
93 
93 
93 
93 


8.67 
6.05 
3.13 
2.88 
8.40 
2.00 
2.62 
3.91 
2.94 
3.12 
3.73 
1.89 


113 

230 

100 

91 

105 

55 

76 

115 

84 

92 

109 

54 


0.83 
1.13 
0.76 
0.80 
0.94 
0.50 
0.74 
0.95 
0.74 
0.86 
0.92 
0.50 


93 


it 


tt 


260 


Oct. 


tt 


76 


it 


it 


73 


it 


ft ... 


98 


Nov. 


tt ... 


28 


tt 


tt 


57 


tt 


tt 


109 


it 


tt ^ 


62 


Dec. 


tt 


79 


it 


tt 


100 


tt 


tt 


27 




APPENDIX III.— HYDROGRAPHIC REPORT 



251 



RATING TABLE FOR RIO CHANCHOS ABOVE THE LIMPIO. 
This table is applicable only from January 17, 1898, to February 21, 



1898. 



height. 



Dischargre. 



Gaffe 
leitrnl 



heigift. 



Discharge. 



Oage 
height. 



Discharge. 



Gage 
lioighl 



hoignt. 



Discharge. 



Feet. 


Second-feet. 


Feet. 


Second- feet. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


2.0 


31 


3.8 


104 


5.6 


212 


7.4 


820 


2.1 


83 


3.9 


no 


5.7 


218 


7.5 


326 


2.2 


35 


4.0 


116 


5.8 


224 


7.6 


332 


2.3 


38 


4.1 


122 


5.9 


230 


7.7 


838 


2.4 


41 


4.2 


128 


6.0 


236 


7.8 


844 


2.5 


44 


4.3 


134 


6.1 


242 


7.9 


350 


2.6 


47 


4.4 


140 


6.2 


248 


8.0 


356 


2.7 


51 


4.5 


146 


6.8 


254 


8.1 


362 


2.8 


55 


4.6 


152 


6.4 


260 


8.2 


868 


2.9 


59 


4.7 


158 


6.5 


266 


8.3 


374 


8.0 


63 


4.8 


164 


6.6 


272 


8.4 


880 


8.1 


67 


4.9 


170 


6.7 


278 


8.5 


386 


8.2 


72 


5.0 


176 


6.8 


284 


8.6 


392 


8.8 


77 


5.1 


182 


6.9 


290 


8.7 


398 


3.4 


82 


5.2 


188 


7.0 


296 


8.8 


404 


8.5 


87 


5.3 


194 


7.1 


302 


8.9 


410 


8.6 


93 


5.4 


200 


7.2 


308 






8.7 


98 


5.5 


206 


7.8 


314 









ESTIMATED MONTHLY DISCHARGE OF RIO CHANCHOS ABOVE THE LIMPIO. 




Month. 


Discharge in Second-Feet. Total In Month Discharge in Second-Feet. 
Maximum. Minimum. Meani Acre-Feet. 1»WJ. Maximum. Minimum. Mean! 


Total in 
Acre-Feet. 


January 


17-31.. 252 36 96 2,850 February 1-20 .. . 895 34 139 


5,520 



Lower Station on the Rio Chanchos. 

A gage was placed on the left bank of the 
Rio Chanchos, about one-half mile above the 
point where the telegraph line intersects the 
river. It consists of a vertical pine board driven 
in the bed of the stream, and spiked to a tree 
growing on the bank. Bench mark consists of 



two 8-penny nails driven in a notch in a tree, 25 
feet from the river bank at nearest point and 
30 feet from gage rod. Tree has one smaller 
leaning against it. 

Measurements of discharge were made from a 
huge tree trunk lying across the river one-half 
mile up stream from the gage. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO CHANCHOS AT LOWER STATION. 



Date. 
1808. 



Hydrogrraphor 



Meter 
number. 



Gage 
height 
(feet). 



Area of 
section 
(sq. ft.). 



Mean ve- 
locity (ft. 
per sec.). 



Discharge 
(second- 
feet). 



Remarkfi. 



Jan. 10 N. P. Leary . . . 

♦* 20 W. W. Schlecht 



" 27, 
Feb. 2. 

" 10. 

«* 18. 
Mar. 7. 

** 17. 

" 26. 



98 


5.98 


821 


1.26 


404 


Stk. 2 


2.55 


199 


0.67 


134 


Stk. 2 


1.82 


167 


0.54 


90 


Stk. 2 


7.28 


455 


1.48 


674 


Stk. 2 


8.19 


204 


0.80 


162 


Stk. 2 


0.92 


144 


0.83 


48 


98 


1.16 


148 


0.56 


80 


93 


0.35 


125 


0.47 


58 


98 


0.78 


189 


0.48 


67 



252 



NICARAGUA CANAL COMMISSION 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO CHANCHOS AT LOWER STATION.— Cont. 



Date. 


Hydrographer. 


Meter 
Dumber. 


Gage 
height 


Area of 
section 


Mean ve- 
locity (ft. 


Discharge 
(second- 


1806. 




(feet). 


(sq. ft.). 


per sec). 


feet). 


Apr. 7 


.W. W. Schlecht 


93 


2.15 


169 


0.65 


109 


" 16 


it 

■ • • • • • 


93 


0.16 


128 


0.37 


46 


May 7 


.C. Hayman 


93 


1.17 


124 


0.57 


71 


** 80 




93 


0.22 


115 


0.39 


45 


June 8 




98 


0.05 


94 


0.33 


32 


** 17 




93 


0.18 


107 


0.31 


33 


** 29 




95 


5.78 


264 


0.84 


228 


July 7 




93 


3.70 


201 


0.68 


188 


*» 16 , 




93 


1.51 


127 


0.40 


51 


" 27 




93 


3.01 


184 


0.70 


130 


Aug. 6 




98 


2.46 


154 


0.62 


97 


** 17 




93 


2.00 


146 


6.46 


67 


** 27 




93 


1.06 


102 


0.57 


58 


Sept. 7 




93 


0.55 


89 


0.51 


45 


»» 17 




93 


2.89 


137 


0.47 


63 


" 26 




93 


2.53 


123 


0.47 


58 


Oct. 7 


.A. Ahrling 


93 


1.03 


103 


0.50 


51 


** 10 




98 


1.15 


99 


0.53 


58 


»» 18 




93 


1.78 


111 


0.41 


46 


»» 26 




93 


8.74 


169 


0.61 


103 


Nov. 6 




93 


0.79 


95 


0.36 


84 


«* 14 




93 


5.88 


255 


0.62 


159 


*» 16 




93 


7.43 


854 


1.41 


498 


** 26 




93 


2.80 


155 


0.72 


111 


Dec. 7 




93 


3.07 


168 


0.78 


131 


»* 17 




93 


2.90 


148 


0.62 


92 


*« 28 




93 


0.83 


99 


0.47 


47 



Remarks. 



RATING TABLE FOR RIO CHANCHOS AT LINE OF EMBANKMENTS. 
This table is applicable only from January 7, 1898, to October 31, 1898. 



Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height. 


Discharge. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


Feet. 


Second-ft. 


-1.0 


9 


1.4 


72 


8.8 


170 


6.2 


448 


-0.9 


11 


1.5 


75 


3.9 


175 


6.3 


470 


-0.8 


13 


1.6 


78 


4.0 


181 


6.4 


492 


-0.7 


15 


1.7 


81 


4.1 


187 


6.5 


514 


-0.6 


18 


1.8 


84 


4.2 


198 


6.6 


536 


-0.5 


21 


1.9 


87 


4.3 


200 


6.7 


558 


-0.4 


28 


2.0 


90 


4.4 


207 


6-8 


580 


-0.8 


26 


2.1 


94 


4.5 


215 


6.9 


602 


-0.2 


28 


2.2 


98 


4.6 


223 


7.0 


624 


-0.1 


81 


2.8 


102 


4.7 


282 


7.1 


646 


0.0 


33 


2.4 


106 


4.8 


241 


7.2 


668 


0.1 


85 


2.5 


110 


4.9 


251 


7.8 


690 


0.2 


87 


2.6 


114 


5.0 


261 


7.4 


712 


0.8 


39 


2.7 


118 


5.1 


272 


7.5 


734 


0.4 


42 


2.8 


122 


5.2 


283 


7.6 


756 


0.5 


45 


2.9 


126 


5.8 


295 


7.7 


778 


0.6 


48 


8.0 


130 


5.4 


308 


7.8 


800 


0.7 


51 


3.1 


135 


5.5 


822 


7.9 


822 


0.8 


54 


8.2 


140 


5.6 


837 


8.0 


844 


0.9 


57 


8.3 


145 


5.7 


853 


8.1 


866 


1.0 


60 


3.4 


150 


5.8 


870 


8.2 


888 


1.1 


68 


8.5 


155 


5.9 


388 






1.2 


66 


8.6 


160 


6.0 


407 






1.3 


69 


3.7 


165 


6.1 


427 




• 



APPENDIX III.— HYDROGRAPHIC REPORT 



253 



ESTIMATED MONTHLY DISCHARGE OF RIO CHANCHOS AT LINE OF EMBANKMENTS. 



Discharge in Second-Feot. Total in 

Month. / • ^ Ai'T«-P«^f 

Maximum. Minimum. Mean. -^*''®^' *^^- 

1898. 

January 670 57 181 11,130 

February 624 43 188 10,440 

March 73 82 53 8,260 

April 582 26 102 6,070 

May 80 88 59 8,630 

June 370 28 101 6,010 

40,540 



DiBchargo in g econd-Feet . ^otal in 

Month. 4 » V A«i^c^l^* 

Maximum. Minimum. Mean. '^*'^^'®®^ 

1898. Brought forward, 40,540 

July 888 71 228 14,020 

August 168 46 95 5,840 

September 585 85 138 8,210 

October 145 46 88 5,410 

November 755 84 182 10,830 

December 390 40 130 7,990 

Total 92,840 



NiciioLsox Creek. 

On January 17 a gage rod was placed in Xich- 
olson creek a short distance below the telegraph 
line, and the following measurements of dis- 
charge were made, which give a fair idea of the 



size of the stream and its fluctuations. It will 
be noted that the relation between gage height 
and discharge is disturbed by back water in the 
San Francisco, but this does not affect the accu- 
racy of the measurements given. 



LIST OF DISCHARGE MEASUREMENTS MADE ON NICHOLSON CREEK BELOW 

TELEGRAPH LINE. 



Date. 

1M«. 


Hydrographer. 


Meter 
number. 


Jan. 21 . . . 


...N. P. Leary 


93 


" 28... 


(t 


93 


Feb. 15... 


{ 


( 

Schlecht 


93 


** 21... 


...W. Vi. 


93 


Mar. 6... 


• • ■ • • • < 


93 


** 15... 


• • • • • • < 


93 


»♦ 25... 




. . . « 

it 

• • • 


93 


Apr. 15... 




93 


" 25... 


it 

• • • • • • I 


93 


May 7... 


.. .0. Ilayman 


93 


** 18... 




I 




93 


" 80... 








93 


June 8. . . 








93 


*« 17... 








93 


** 29... 








98 


July 6... 


. . . ** 






93 


" 14... 








98 


»* 26... 








98 


Aug. 6 . . . 








93 


" 15... 








93 


" 25... 








98 


Sept. 5. . . 








93 


** 15... 








93 


** 24... 




1 




93 



Gage Area of Mean velocity 

height section (feet 

(feet). (square feet). per second). 



Discharge 
(second- 
feet). 



Remarks. 



8.67 
5.80 
5.64 
5.02 
6.25 
4.60 
4.70 
4.46 
4.30 
5.80 
4.64 
4.82 
4.88 
4.72 
9.52 
9. .52 
6.85 
7.50 
6.73 
8.22 
5.72 
4.91 
7.20 
8.00 



149 
57 
53 
34 
67 
17 
24 
21 
18 
35 
21 
31 
15 
22 

176 

158 
70 
87 
68 

104 
41 
21 
78 

100 



0.67 
0.56 
0.56 
0.69 
0.54 
0.81 
0.85 
0.82 
0.74 
0.66 
0.72 
0.65 
0.64 
0.63 
0.48 
0.45 
0.36 
0.49 
0.61 
0.42 
0.52 
0.54 
0.32 
0.38 



100 
32 
30 
24 
36 
14 
21 
17 
13 
24 
16 
20 
10 
13 
84 
71 
25 
43 
41 
43 
22 
11 
25 
38 



254 



NICARAGUA CANAL COMMISSION 



Rio Sarapiqui. 

The plan of canalizing the Kio San Juan, as 
sometimes proposed, involves the control of the 
waters of Eio Sarapiqui and of the sediment 
which it brings down from the mountains of 
Costa Kica. 

On July 23 a gage was placed on the left bank 
of this river about five miles above its mouth. 
It is a vertical rod, graduated to feet and tenths, 



from zero to 13 feet, and spiked to a tree which 
hangs over the river. Another rod, graduated 
from 10 to 23 feet, is fastened to a tree about 
300 yards up stream, on the same side of the 
river. At this latter place a galvanized steel 
cable is placed across the river, from which 
measurements of discharge are made with the 
use of a boat, and observations of sediment car- 
ried are also made. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO SARAPIQUI FIVE MILES ABOVE 

ITS MOUTH. 



Date. 

1806. 



Hydrographer. 



Meter 
number. 



Oage 

hei^t 

(feet). 



Area of 

section 

(square ft.). 



Mean ve- 
locity (feet 
per second). 



Discharfire 
(second- 
feet). 



Remarks. 



it 
t( 

n 

(t 
ii 
it 



May 10. 

July 12. 

** 27. 

Aug. 27. 

" 81. 

Sep. S. 

9. 

12. 

13. 

14. 

21. 

24. 

27. 
Oct. 11. 
Dec. 21. 

1899. 

Jan. 9. 

i( 

it 
it 
it 

it 
it 

Feb. 

it 

it 
it 
it 
it 
it 
it 

Mar. 
it 

it 

it 

it 

it 

it 
it 



.. .A. P. Davis, 



ti 



...G. R. Wadleigh 
. . . W. A. Smith . . 



it 



ti 



13. 
16. 
21. 
25. 
28. 
31. 

8. 

8. 
11, 
18. 
14. 
20. 
21. 
24. 

4. 

8. 
11, 
16. 
18. 
22. 
25. 
29. 



.n. W. Durham 



it 

ii 

ti 

• it 

it 
ti 
it 
it 



it 
it 
it 
it 
ti 
ti 
it 
ti 
ti 
ti 
it 
it 
it 
it 
ti 
it 
it 
it 
it 
it 
it 
it 
it 



94 

94 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 



1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1985 
1995 
1985 
1985 
1985 
1985 



8.84 

8.51 

8.11 

8.25 

7.52 

8.98 

12.99 

13.06 

8.57 

8.72 

13.02 

11.95 

8.13 



9.00 

12.58 

13.30 

8.90 

8.83 

7.80 

7.35 

7.25 

7.25 

7.04 

18.40 

1.5.20 

11.20 

8.78 

11.37 

8.35 

11.88 

7.50 

7.68 

7.38 

6.81 

6.73 

10.00 



1,046 
3,686 
2,238 
1,922 
1,765 
1,823 
1,617 
2,088 
4,294 
4,054 
1,925 
1,972 
4,181 
3,388 
1,735 



1,979 
3,445 
8,703 
2,008 
2,015 
1,646 
1,461 
1,406 
1,450 
1,399 
5,563 
4,459 
2,869 
1,938 
2,967 
1,732 
2,882 
1,462 
1,561 
1,458 
1,284 
1,230 
2,475 



2.92 
2.65 
2.85 
2.43 
2.28 
2.34 
2.10 
2.38 
3.47 
3.43 
2.37 
2.40 
8.69 
3.42 
2.34 



2.52 
3.29 
8.42 
2.45 
2.43 
2.17 
2.10 
2.04 
2.03 
1.94 
4.81 
8.79 
2.99 
2.32 
2.96 
2.31 

3.11 
2.19 
2.18 
2.09 
1.87 
1.82 
2.75 



3,050 

10,762 

5,252 

4,677 

4,014 

4,264 

3,399 

4,974 

14,914 

13,898 

4,560 

4,730 

15,241 

11, .598 

4,053 

4,987 
11,348 
12,669 
4,920 
4,905 
3,582 
3,072 
2,862 
2,943 
2,711 
26,731 
16,892 
8,582 
4,501 
8,780 
4,007 
8,972 
3,198 
3,409 
8,040 
2,313 
2,240 
6,807 



APPENDIX III.— HYDROGRAPHIC REPORT 



255 



RATING TABLE FOR RIO SARAPIQUI AT STATION FIVE MILES ABOVE ITS MOUTH. 
This table is applicable only from July 23, 1898, to January 1, 1899. 



Gage 
height. 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height. 

Feet. 


Discharge. 
Second- feet. 


Gage 

height. 

Feet. 


Discharge. 


Feet. 


Second-feet. 


Feet. 


Second-feet. 


Second-feet 


7.2 


3,140 


9.7 


7,090 


12.2 


12,590 


14.7 


18,090 


7.8 


3,210 


9.8 


7,310 


12.3 


12,810 


14.8 


18,310 


7.4 


3,280 


9.9 


7,530 


12.4 


13,080 


14.9 


18,530 


7.5 


3,3.50 


10.0 


7,750 


12.5 


13,250 


15.0 


18,750 


7.6 


3,420 


10.1 


7,970 


12.6 


13,470 


15.1 


18,970 


7.7 


3,500 


10.2 


8,190 


12.7 


13,690 


15.2 


19,190 


7.8 


3,590 


10.3 


8,410 


12.8 


13,910 


15.3 


19,410 


7.9 


3,690 


10.4 


8,630 


12.9 


14,130 


15.4 


19,630 


8.0 


3,800 


10.5 


8,850 


18.0 


14,350 


15.5 


19,850 


8.1 


3,930 


10.6 


9,070 


13.1 


14,570 


15.6 


20,070 


8.2 


4,070 


10.7 


9,290 


13.2 


14,790 


15.7 


20,290 


8.3 


4,220 


10.8 


9,510 


18.3 


15,010 


15.8 


20,510 


8.4 


4,380 


10.9 


9,730 


13.4 


15,230 


15.9 


20,730 


8.5 


4,5.50 


11.0 


9,950 


13.5 


15,450 


16.0 


20,950 


8.6 


4,730 


ll.l 


10,170 


13.6 


15,670 


16.1 


21,170 


8.7 


4,920 


11.2 


10,390 


18.7 


15,890 


16.2 


21,390 


8.8 


5,120 


11.3 


10,610 


18.8 


16,110 


16.3 


21,610 


8.9 


5,380 


11.4 


10,830 


18.9 


16,380 


16.4 


21,880 


9.0 


5,550 


11.5 


11,050 


14.0 


10,5.50 


16.5 


22,050 


9.1 


5,770 


11.6 


11,270 


14.1 


16,770 


16.6 


22,270 


9.2 


5,990 


11.7 


11,490 


14.2 


16,990 


16.7 


22,490 


9.3 


6,210 


11.8 


11,710 


14.3 


17,210 


16.8 


22,710 


9.4 


6,430 


11.9 


11,930 


14.4 


17,430 


16.9 


22,930 


9.5 


6,650 


12.0 


12,150 


14.5 


17,650 






9.6 


6,870 


12.1 


12,370 


14.6 


17,870 







RATING TABLE FOR RIO SARAPIQUI AT STATION FIVE MILES ABOVE ITS MOUTH. 
This table is applicable only from January 1. 1899. to March 31. 1899. 



Garo 
height 


Discharge. 


Gage 
height 


Discharge. 


Gage 
height. 


Discharge. 


Gage 
height 


Discharge. 


Feet 


Second-feet 


Feet 


Second-feet 


Feet 


Second-feet 


Feet 


Second-feet. 


6.5 


2,020 


8.0 


4,560 


10.7 


7,785 


12.8 


11,690 


6.6 


2,140 


8.7 


4,700 


10.8 


7,940 


12.9 


11,890 


6.7 


2,260 


8.8 


4,850 


10.9 


8,100 


18.0 


12,090 


6.8 


2,380 


8.9 


5,000 


11.0 


8,260 


18.1 


12,290 


6.9 


2,500 


9.0 


5,1.50 


11.1 


8,480 


13.2 


12,490 


7.0 


2,620 


9.1 


5,300 


11.2 


8,000 


13.3 


12,690 


7.1 


2,740 


9.2 


5,450 


11.8 


8,780 


13.4 


12,890 


7.2 


2,860 


9.3 


5,600 


11.4 


8,960 


13.5 


13,090 


7.8 


2,980 


9.4 


5,750 


11.5 


9,140 


13.6 


13,290 


7.4 


3,100 


9.5 


5, WO 


11.6 


9,330 


13.7 


13,490 


7.5 


3,220 


9.6 


ti,060 


11.7 


9,520 


13.8 


13,690 


7.6 


3,840 


9.7 


6,220 


11.8 


9,710 


13.9 


13,890 


7.7 


8,460 


9.8 


6,380 


11.9 


9,900 


14.0 


14,090 


7.8 


8,580 


9.9 


6, .540 


12.0 


10,090 


14.1 


14,290 


7.9 


8,700 


10.0 


6,700 


12.1 


10,290 


14.2 


14,.500 


8.0 


8,820 


10.1 


6,855 


12.2 


10,490 


14.3 


14,720 


8.1 


8,940 


10.2 


7,010 


12.3 


0,690 


14.4 


14,840 


8.2 


4,060 


10.3 


7.165 


12.4 


0,890 


14.5 


15,170 


8.8 


4,180 


10.4 


7,320 


12.5 


1,090 


14.6 


15,400 


8.4 


4,805 


10.5 


7,475 


12.6 


1,290 






8.5 


4,430 


10.6 


7,630 


12.7 


11,490 







256 



NICARAGUA CANAL COMMISSION 



ESTIMATED MONTHLY DISCHARGE OF RIO SARAPIQUI FIVE MILES ABOVE ITS MOUTH. 

Drainage area. 1,100 square miles, approximately. 



Month. 



Discharflre in Second-feet. 



Maximum. 



Minimum. 



Mean. 



Total for the 
month in 
acre-feet. 



Run-off. 



Depth 
in inches. 



Seoond-feet 
per sq. mile. 



1898. . 

July (33-31) 

August (1-5 and 18-31 Incl.) 

September 13,140 

October 14,570 

November 80,000 

December 21,610 

1809. 

January 18,580 

February 27,100 

March 8,960 



3,360 
4,100 
4,640 
3,150 

3,000 
2,710 
2.280 



5,890 
5,.550 
5,890 
8,240 
11,700 
6,650 

5,420 
5,300 
8,350 



841,250 
850,780 
507,500 
696,200 
408,890 

883,260 
288,800 
205,980 



5.83 
5.97 
8.65 
11.87 
6.98 

5.68 
4.93 
3.98 



5.05 
5.85 
7.50 
10.64 
6.05 

4.98 
4.78 
8.45 



Eio Tauba. 

The waters of the San Juan river have two 
principal outlets, the southern called the Rio 
Colorado, and the northern, called the lower 
San Juan. The latter stream sends out another 
distributary which empties into the ocean be- 
tween the two larger, and is called the Taura. 
It seems, however, that a portion of the course 
of the Taura is, during the season of low water, 
higher than the water in the San Juan, and be- 
comes a tributary of the latter. It was visited 
on May 6, 1898, and was at that time discharging 
25 cubic feet per second into the San Juan. On 
the same day the discharge of the San Juan 
below the Taura was 1112 cubic feet per second. 
The discharge at Ochoa on the same date was 
16,950 cubic feet per second. 

On July 13 the Taura was flowing away from 
the San Juan and its volume 200 yards below its 
exit was 2234 cubic feet per second. On this 
day the discharge of the San Juan at Ochoa was 
46,000 cubic feet per second. 

The condition in May of the Taura flowing 
toward the San Juan was apparently quite anom- 
alous, the mouth at the coast being closed by a 
dike of sand built by the waves. The normal 
condition of the Taura is that of a minor dis- 
tributary of the San Juan. 



Rio Deseado. 

This is a small stream rising in the ridge of 
hills, known in canal literature as the " Eastern 
Divide." 

According to the company's location the canal 
is to follow the valley of the Deseado for a con- 
siderable distance and the plan involves the con- 
trol and diversion of the waters of this stream. 
Three locks and several high embankments are 
to be constructed in this valley and the volume 
of the river and the amount of rainfall in this 
vicinity become important facts, an approximate 
knowledge of which is necessary to an intelligent 
discussion of plans and estimate of cost. 

On the 25th of December, 1897, a gage was 
placed in the Deseado at a point about five miles 
above its mouth, measured along the course of 
the stream; a rain gage was also established at 
this point, and observations of river height, rain- 
fall, temperature and humidity were begun by 
Mr. W. M. Barton. 

Subsequent measurements of discharge showed 
that no definite relation could be established be- 
tween gage height and discharge of the stream, 
although the channel consists of hard clay and is 
not changeable. The erratic changes in velocity 
which the stream exhibited at this point are 
doubtless due to the fact that it runs through 



APPENDIX III.— HYDROGRAPHIC REPORT 



257 



swampy country on very flat slope. Though 
there are no definite tributaries anywhere near 
the gaging station, yet heavy rains in the swamps 
serve to back the water in the Deseado, if occur- 
ring below the station, and to accelerate its ve- 
locity if occurring above. 

On March 4 observations of gage height were 



begun some distance above at " Camp No. 7 " 
near the site of the proposed Lock No. 1, and the 
following discharge measurements were made at 
that point, and from these a rating table was 
constructed and the table of discharges esti- 
mated. 



LIST OF DISCHARGE MEASUREMENTS MADE ON RIO DESEADO AT CAMP BARTON. 



Date, 
laoft 


Hydrofirrapher. 


Moter 
niiiiibf*r 


Gage 
height 


Area of 
section 


Mean ve- 
locity (ft. 


Dlschanpe 
(second- 










(feet). 


(sq. ft.). 


per sec.). 


feet). 


Peb. 


26 


.A. P. Davis 


Stk. 3 


7.85 


772 


0.63 


489 


Mar. 


8 


. W. M. Barton 


2 


8.70 


823 


0.13 


99 


tt 


15 


.L. E. Lannan 


2 


7.71 


711 


0.03 


19 


April 


5 




3 


7.69 


730 


0.63 


462 


ti 


13 




2 


8.03 


744 


0.12 


97 


tt 


21 




2 


4.85 


507 


0.06 


84 


tt 


36 




3 


5.75 


575 


0.10 


61 


May 


3 




2 


6.38 


608 


0.18 


107 


it 


7 




2 


7.13 


671 


0.14 


92 


tt 


13 




2 


6.68 


634 


0.35 


218 


it 


18 




3 


5.68 


570 


0.05 


31 


it 


24 


.J. C. Elson 


3 


6.83 


639 


0.09 


58 


it 


31 




2 


6.33 


609 


0.36 


330 


June 


3 




3 


6.80 


625 


0.06 


43 


tt 


11 




3 


4.90 


491 


0.07 


85 


it 


14 




3 


7.15 


663 


0.23 


156 


it 


16 




3 


7.38 


649 


0.15 


103 


it 


20 




3 


6.80 


636 


0.06 


48 


it 


35 




3 


10.12 


922 


0.68 


634 


it 


38 




3 


10.26 


928 


0.18 


173 


July 


8 




3 


10.80 


958 


0.22 


311 


it 


13 




2 


10.15 


919 


0.23 


319 


tt 


16 




2 


8.88 


822 


0.19 


159 


tt 


21 




3 


11.83 


1026 


0.53 


550 


Aug. 


6 




2 


10.19 


918 


0.22 


308 


it 


9 




3 


10.59 


936 


0.38 


809 


it 


13 




3 


10,51 


933 


0.14 


185 


tt 


16 




2 


10.95 


891 


0.10 


98 


it 


26 




3 


7.43 


681 


0.14 


100 


Sept. 


2 




3 


6.70 


616 


0.07 


45 


it 


10 




3 


6.15 


577 


0.05 


37 


it 


14 




3 


7.19 


657 


0.37 


343 


tt 


19 




3 


6.66 


610 


0.11 


69 


tt 


24 




3 


6.60 


601 


0.10 


63 


Oct. 


6 




2 


6.10 


560 


0.13 


71 


it 


10 




3 


6.78 


597 


0.09 


56 


it 


15 




2 


6.94 


603 


o.io 


64 


tt 


22 




2 


6.99 


633 


0.24 


151 


it 


26 




2 


8.60 


738 


0.27 


• 199 


it 


31 




2 


7.69 


668 


0.07 


46 


Nov. 


10 




2 


9.30 


788 


0.14 


111 


it 


16 




2 


11.78 


950 


0.45 


439 


tt 


Xo. . • . < 




2 


14.28 


1153 


0.50 


577 


it 


23 




2 


11.61 


940 


0.15 


144 


it 


26 




2 


11.06 


913 


0.35 


817 


it 


29 


k 4 4 


2 


12.49 


1030 


0.31 


819 


Dec. 


1 




2 


12.26 


1004 


0.36 


364 


it 


8 




3 


11.18 


936 


0.24 


339 


tt 


13 




3 


12.33 


1012 


0.23 


383 



17 



268 NICARAGUA CANAL COMMISSION 

LIST OP DISCHARGE MBASDREMBNTS MADE ON RIO DESEADO AT CAMP NO. 7. 



]^^^' Hydrograpber 



(lEt ft.). 



Mean ve- 
locity (ft 



Dlacham 
feet). 





3.% 


April 


1 

fi 


■;: 


IN 

a-i 


May 


fl 




33 

30 


jQDe 







13 




31 


Jnl, 


11 


A eg. 


Vi 




as 


Sept. 


1) 




IB 




26 


Oct. 


'^I'.'.W'.'. 




10 

IT 


Sot. 


■•9 

11 




15.... 


Dec, 


art 




13 

Ifl 




19 



APPENDIX III.— HYDROGRAPHIC REPORT 



259 



This 



RATING TABLE FOR RIO DESEADO AT CAMP NO. 7. 
table is applicable only from March 4, 1898, to December 31, 



1898. 



Gage 
height. 


Discharge. 




Gage 
height. 


Discharge. 


h?iX l^^^^arge. 


Gage 
height. 


Discharge. 


Feet. 


Second-ft. 




Feet. 


Second ft. 


Feet. Second-ft. 


Feet. 


Second-ft. 


8.0 


26 




5.6 


130 


8.2 


850 




10.8 




610 


8.1 


28 




5.7 


137 


8.3 • 


360 




10.9 




620 


8.2 


80 




5.8 


144 


8.4 


370 




11.0 




630 


8.8 


82 




5.9 


151 


8.5 


380 




11,1 




640 


8.4 


84 




6.0 


159 


8.6 


890 




11.2 




650 


8.5 


86 




6.1 


167 


8.7 


400 




11.3 




660 


8.6 


88 




6.2 


175 


8.8 


410 




11.4 




670 


8.7 


41 




6.3 


188 


8.9 


420 




11.5 




680 


3.8 


44 




6.4 


191 


9.0 


430 




11.6 




690 


8.9 


47 




6.5 


199 


9.1 


440 




11.7 




700 


4.0 


50 




6.6 


207 


9.2 


450 




11.8 




710 


4.1 


58 




6.7 


215 


9.3 


460 




11.9 




720 


4.2 


56 




6.8 


224 


9.4 


470 




12.0. 




780 


4.8 


59 




6.9 


233 


9.5 


480 




12.1 




740 


4.4 


62 




7.0 


242 


9.6 


490 




12.2 




750 


4.5 


66 




7.1 


251 


9.7 


500 




12.3 




760 


4.6 


70 




7.2 


260 


9.8 


510 




12.4 




770 


4.7 


75 




7.3 


269 


9.9 


520 




12.5 




780 


4.8 


80 




7.4 


278 


10.0 


530 




12.6 




790 


4.9 


85 




7.5 


287 


10.1 


540 




12.7 




800 


5.0 


91 




7.6 


296 


10.2 


550 




12.8 




810 


5.1 


97 




7.7 


305 


10.3 


560 




12.9 




820 


5.2 


108 




7.8 


314 


10.4 


570 




13.0 




830 


5.8 


109 




7.9 


323 


10.5 


580 




13.1 




840 


5.4 


116 




8.0 


332 


10.6 


590 




13.2 




8.50 


5.5 


123 




8.1 


841 


10.7 


600 




13.3 




860 




ESTIMATED MONTHLY DISCHARGE 


OP RIO DESEADO 


AT CAMP NO. 7. 






Month. 


Discharge in Second-feet 

r ^ 

Maximum. Minimum. Mean. 


Total for 
Month in 
Acre-feet. 


Month. 


Discharge in Second-feet. 
Maximum. Minimum. Mean. 


Total for 
Month in 
Acre-feet. 


1898. 
March 


185 

462 


68 
34 


107 
111 


6,579 
6,605 


1898. 
Autrust .... 




482 
243 


Brought tory 
70 200 

27 78 


vard, 48,388 
12,300 


April 


September . 




4,640 


May 


223 


81 


97 


5,964 


October .... 




278 


42 


99 


6,090 


June 


267 


80 


137 


8,150 


November . 




854 




322 


19,160 


July 


794 


122 


348 


21,090 

48,388 


December . . 
Total . . 




324 


90 


221 


13,. 590 
104,168 

















MISCELLANEOUS DISCHARGE MEASUREMENTS IN NICARAGUA. 

Made by A. P. Davis, 1898. 



Date. 



Stream. 



Locality. 



Meter Gage height Area of sec. Mean veloc. Discharge 
number. (feet). (sq.ft.;. (ft. per sec.). (sec-ftT). 



Jan. 18 Las Lajas. 

** 18 Guiscoyol 

«« 80 Jicoral ... 

May 12 Machuca.. 

July 9 Machuca. 

June 21 OUate 



At mouth 


94 


2 miles up. . . . 


94 


Jicoral 


94 


}4 nille up 


94 


2 miles up 


94 


8 ** «' 


94 



7.88 



2.60 



2.8 


1.46 


4.1 


6.1 


32 


2.0 


20.0 


47 


9.4 


68.0 


1. 10 


75.0 


156.0 


1.70 


266.0 


1079.0 


3.94 


4258.0 



260 



NICARAGUA CANAL COMMISSION 



RECORD OP RIVER GAGINGS FOR VELOCITY AND VOLUME. 
Taken from Appendix C of Report of Nicaragua Canal Board, 1895. 



River. 



Locality. 



ii 



ti 



(t 



it 



(( 



Colorado 
River 

Lower 
San Juan 

San Juan 

San Juan 

(i 

({ 

ii 
(i 

i< 

ii 

Colorado 

Lower 
San Juan 

San Juan 



Date. 



San Juan Fort San Carlos June 5, 1850 



Authority. 



Immediately above 

mouth of 
San Carlos River 

Immediately below 

mouth of 

San Carlos River 

Immediately above 

;nouth of 

Sarapiqui River 

Immediately below 

mouth of 

Sarapiqui River 

Immediately above 

head of 

Colorado River 



I 



Above Toro Rapids 

Below mouth of 
Poco Sound 

Above mouth of 
Santa Cruz 

Below mouth of 
Santa Cruz 

Above Mico Rapids 

Above mouth of 
San Carlos 

Above mouth of 
Sarapiqui 

Below mouth of 
Sarapiqui 



O. W. Chllds 



Between mouth of 
Sad Carlos and Ochoa 



July 15, 1850 

July 15, 1850 

Aug. 8, 1850 

Aug. 8, 1850 

Aug. 30,1850 

Aug. 30, 1850 

Aug. 30, 1850 

April 36, 1878 
April 80, 1873 

May 1, 1873 

May 3, 1873 

May 6, 1878 
May 10, 1873 

May 16, 1873 

May 16, 1873 

May 19, 1873 
May 30, 1873 



May 31 to 36, 

1888 



<i 



ii 



it 



ti 



ti 



ti 



tt 



Lull 



it 



it 



tt 



tt 



ii 



it 



it 



it 



It 



Area of 

cross see. 

(sq. ft). 



Canal Co., by 
J. H. Covode 



11,810 



Velocity 
per sec. 

(ft.). 



Discharge 
per sec. 
(cu. ft.). 



Remarks. 



11,930 Lake Nicaragua at an 
elevation 103.07, low 
stage. 



3.665 



19,300 

36,747 

39,536 

53,793 

54,880 

43,056 

13,334 

13,096 
11,390 

11,630 

13,453 

13,943 
13,306 

14,573 

16,770 

16,190 
607 

41,451 



Medium stage. 



it «« 



it 



ii 



«t u 



CC ii 



ii ti 



ti it 



Ele. of Lake Nicaragua 
Sept. 19, 1850, 105.63. 

Ele. of Lake Nicaragua, 
103.38, low stage. 



it 



it 



tt 



it 



tt 



it 



it 



tt 



tt 



it 



it 



it 



ct 



«c 



«l 



tt 



tt 



it 



Medium stage. 



APPENDIX III.— HTDROQRAPHIC REPORT 261 

RECORD OP RIVER OAOING8 FOR VELOCITY AND VOLUME.— Con Unued. 



Rivet. 


locality. 


Date. 


Authoiltf. 


Ai«aor 


Velocitr 


DiKjharsc 




8>i> Joan 


Fort Ban Carlos 


May 27, 1895 


Nic. Canal 
Board 


7,480 




9,430 


Lakeatelev. 101.07 ft., 
velocltiea meaa'd with 
floatBimmeraea5';low 


8mn Carloa 


Below mouth of 
aartplqol 

Immedlatoly abOTe 
moDtb 


June 30, 1895 

Jnly IS, 1850 

Nov. SO, 1888 
Ang. 8, 1850 


0. W. ChildB 

Canal Co. by 
J. F. LeBaroQ 
0. W. CblldB 


91,500 




3.60 


60,300 

16,447 

7,844 
18,268 


Bta^e, coefflclent, 0.0. 
UbIdu' surface velocity 
low atage, coefflclent. 

a8. 

Medium stage. 




month 


„ „ 


Duit& 


SOiy above month 


Mar. 31,188M 
Jnlj Ifl, 1B88 


Canal Co. by 
J. F. Le Baron 


87.5 
611 


0.40 
1.26 


85 

7S4 


Low Btage. 
High stage. 


San 
FnnclKo 


Below month of 

Chancboi 


Mar. aa, 1888 




390 


0.60 


174 


Using surface velocity, 
low stage. 


•• 


Camp Ban Franc lico 

200/ below Camp 
San Franclaco 


Junel4, 1895 
Janeli, 18HS 


NIC. Canal 
Board 


231 

BOB 


1.70 

i.ai 


370 
818 


„ 




Below month ot 
Cbancho* 


Jnnel6,ie95 




515 


l.SO . 


669 


" 


NlcholsoQ 


Embankment C to Ming 


Jane 14, 1865 




100 


1.70 


170 


.. 


ChKDchoi 


" 


Jane 16, 1895 




200 


1.60 


8B4 


.. 


Llmplo 


J a at below Camp 
Carmen 


Jnne 16, 1896 




45 


1.30 


68 


,. 




At Camp Carmen 


June 16,1806 




S4 


1.90 


86 


., 




Joat above Junction 
with the Lindo 


June 16, 1896 




e 


1.80 


16 


" 


Llndo 


Jnst above junction 
with Limplo 


Jnne 16. 1895 




10.4 


1,60 


17 


„ 


Deiesdo 


Sew tlte of Virginia 

Dam 


June 17, 1896 




50 


3.00 


150 




" 


laoc below Camp 
Menocal 


Jnne 18, 189B 




377 


2,30 


637 


" 


'■ 


Near Camp No. 7 


Jnne 18, 1895 


■' 


484 


1,5 


737 




" 


Near Lock No. 1 


Dec. 14, 1892 


Canal Co., by 
Boyd Ebl« 






386 


Water anrface alevatlno 
13.38, medlnm atage. 



262 



NICARAGUA CANAL COMMISSION 



Raixfall. 

Observations of rainfall were made at each 
river station, the form of gage used at most of 
the stations being a metal funnel which caught 
the rain and discharged it into a bottle, from 
which it was measured in a graduate bearing a 
known relation to the diameter of the funnel. 
The gage was always placed in a position as 
exposed as possible, but nearly always this was 
a small clearing in the forest, which was still 
well sheltered from the wind. 

One of the most remarkable characteristics of 
Nicaragua is its rainfall, and the radical and 
striking diiferences in the climate of the east 
and west coasts with reference thereto. 

The diagram (Plate XI), shows graphically 
the* contrast in the distribution of rainfall at 
Brito near the Pacific coast and on the Rio De- 
seado, a short distance inland from Greytown. 
From this it will be seen that there is no definite 
dry season on the eastern coast, but that rain 
may be expected any day in the year, and the 
expectation will seldom be disappointed. 

At Brito, on the contrary, there is no rain 
from the beginning of the record in January till 
the middle of May, when the rainv season be- 
gins, but the region is subject to violent down- 
pours during the rainy season, the precipitation 
for a single day observed at this station on the 
22d day of May being 5.6 inches. 

No less remarkable is the excessive aggregate 
of rainfall in a limited district of which the 
nucleus seems to be in the vicinity of Greytown. 
The annual rainfall at this point, as deduced 
from the mean of four years' observation, is 
about 250 inches, while that at Bluefields is 
only about 90, at Port Limon somewhat less, 
and at San Jose de Costa Rica about 68. While 
there is a slight increase of rainfall with altitude 



on the headwaters of the Deseado and Limpio, 
yet in general it may be said that the rainfall 
decreases as we pass up the San Juan, as shown 
by the diagram, Plate Xin. No definite limits 
can be assigned to this district of excessive rain- 
fall, nor is it known in what ratio the precipita- 
tion decreases to the northward and southward. 
So far as known, no satisfactory theory has yet 
been advanced to account for this local phe- 
nomenon. 

Mr. William Climie reports a rainfall of nine 
inches in nine hours at Nandaime, a small town 
south of Granada^ No such precipitation has 
been observed by this party, however, the heavi- 
est rainfalls in 1898 being as follows: 

Inches 
station. Date. Time. of Rain. 

Morrito, Sept. 14, 10 hrs. 4.65 

Ft. San Carlos, Jime 18, J hr. 1.83 

Sabalos, June 18, IJ hr. 2.32 

Sabalos, Oct 27, 2 hrs. 3.11 

Rio San Carlos, June 21, 1 hr. 1.55 

Rio San Francisco, Nov. 7, night, 3.70 

The heaviest general rain storm of the season 
began in the night following November 15, 
1898, and passed westward, a heavy precipita- 
tion being shown at all stations east of Lake 
Nicaragua. The observed quantities are as 
follows: 

Grevtown 4.85 inches fell in 24 hours. 



i( 



7.92 

Rio Deseado 6.26 

Rio San Francisco. .6.51 

Ochoa 3.60 

Sarapiqui 3.45 

Fort San Carlos . . . 1.05 



u 
ii 
(( 
u 
i( 

(6 



i6 



48 
24 
24 
one night. 



i6 



(6 



6i 



i6 



ii 



dav. 



The following records of heavy rainfalls were 
compiled by the Canal Board of 1895 and are 
published in Appendix E of their report. 



NICARAGUA CANAL COMMISSION 



JANUARY 



FEBRUARY 



MARCH 



APRIL 



MAY 



I 



r 



1 



o 





f ja MS M » i 


8 W t* 90 »S 


B Mf tS H> gS 


t Mf U »0 »S 


« M Jf J0 JSS 
















































































































































































































































/? 


/i 


y 






I 


^ i 


"> 


s 


o 


A/ 












































1 


















J 


L 










































■ 


























"^ 








































































































































■ 




















































.1. 




I 


1 








i 


1 

JE 


I 

7 A. 


i 

S 30 7, 


11 


1 

1 JO tl 


h 

1 » 


I 

9 Z 




i 




* Ji 




Jl 

If 2S I 


i 

s * 


L 

9 Ji 


( s 


tf 2, 


5 1 s i 


> i! 


1 

( to 


Jit 



JANUARY 



FEBRUARY 



MARCH 



APRIL 



MAY 



COMPARISON OF DAILY RAINFALL ON RIO 



APPENDIX 3, PLATE XI 

COST SEPTEMBER OCTOBEB NOVEMBER DECEMBER 




JULY AUGUST SePTCIDBEn OCTOBER NOVEMBER DECEMBER 

TERN COAST, AND BRITO, NEAR WESTERN COAST, 1896. 



APPENDIX III.— HYDROGRAPHIC REPORT 



263 



LARGE MONTHLY RAINFALLS AT GREYTOWN. 



Month. Inches. 

November, 1889 (in 24 days) 50.70 

December, 1889 64.39 

June, 1890 41.56 

July, 1890 52.59 

August, 1890 36.61 



Month. Inches. 

December, 1890 4 L65 

December, 1891 32.74 

May, 1892 * 50.88 

July, 1892 88.96 

November, 1892 36.98 



LARGE DAILY RAINFALLS AT GREYTOWN. 



Date. Inches. 

July 1, 1890 4.20 

July 2, 1890 4.31 

July 11, 1890 4.18 

July 12, 1890 2.19 

July 13, 1890 5.03 

July 14, 1800 4.66 

July 15, 18JK) 2.57 

September 7, 1890 4.05 

October 9, 1890 4.00 

November 5, 1890 4.10 

December 27, 1890 7.65 

January 20, 1891 4.35 

April 28, 1891 5.75 

June 5, 1891 3.88 

June 6, 1891 4.95 

Total for 2 days 8.78 

June 22, 1891 (9 hours) 4.51 

July 18, 1891 (9 hours) 8.17 

December 8, 1891 4.05 



Date. Inches. 

May 1, 1892 5.08 

May 2, 1892 4.95 

May 3, 1893 4.57 

May 4, 1892 1.63 

Mays, 1893 6.10 

May 6, 1893 5.80 

May 7, 1893 4.10 

May 8, 1892 4.20 

Total for 8 days 35.42 

July 23, 1892 5.30 

October 29, 1892 5.78 

October 80, 1892 3.50 

October 31, 1893 8.03 

Total for 8 days 17.30 

November 20, 1892 5.13 

December 5, 1892 8.95 

June 3, 1893 4.00 

June 19, 1893 r 5.00 



LARGE DAILY RAINFALLS AT CAMP No. 4. 



Date. Inches. 

July -, 1890 5.25 

July 5, 1891 7.70 



Date. 
July 6, 1891 



Inches. 
. . 6.70 



LARGE DAILY RAINFALLS AT CAMP CARAZO. 



Date. Inches. 

June 37, 1888 4.60 

December 4, 1888 4.00 

May 21, 1889 2.90 

October 20, 1889 '. 3.00 



Date. Inches. 

December 19, 1889 2.90 

December 28, 1889 3.50 

January 23, 1890 3.00 



LARGE DAILY RAINFALL AT SILICO LAKE. 



Date. 
April -, 1890 



Inches. 
. . 7.13 



264 NICARAGUA CANAL COMMISSION 



DAILY RAINFALL AT BRITO AND TOLA FOR 1898. 



Day. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 

• 


Nov. 


Dec 


1 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.54 


0.00 


0.00 


2.50 


0.00 


0.02 


2 


0.00 


0.00 


0.00' 


0.00 


0.00 


0.00 


.82 


.06 


0.00 


.06 


0.00 


0.00 


3 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.65 


.00 


0.00 


1.25 


0.00 


0.00 


4 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.13 


.01 


0.00 


.09 


0.00 


5 


0.00 
0.00 


00 
0.00 


0.00 
0.00 


.08 
0.00 


0.00 
0.00 


0.00 
0.00 


0.00 
0.00 


0.00 
.35 


.22 
.02 


.57 

.01 


0.00 
0.00 


00 


6 


0.00 


7 


0.00 


0.00 


0.00 


0.00 


0.00 


2.75 


.98 


.02 


.10 


2.13 


0.02 


0.00 


8 


0.00 


0.00 


0.00 


0.00 


0.00 


.07 


.01 


.23 


.45 


.14 


1.08 


0.00 


9 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.26 


0.01 


.02 


1.45 


.99 


.25 


10 


0.00 


0.00 


0.00 


0.00 


0.00 


.14 


.84 


.03 


1.53 


1.47 


.08 


.02 


11 


0.00 


0.00 


0.00 


0.00 


0.00 


.08 


.36 


.16 


.03 


1.59 


.12 


0.00 


12 


0.00 


0.00 


0.00 


0.00 


0.00 


.06 


.01 


0.00 


.21 


0.00 


1.24 


0.00 


13 


0.00 


0.00 


0.00 


0.00 


0.00 


.08 


.07 


.29 


.80 


.14 


1.20 


0.00 


14 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.03 


.31 


1.50 


1.58 


.02 


0.00 


15 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.01 


.01 


.34 


1.96 


.19 


0.00 


16 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


.54 


.04 


.42 


.48 


.39 


.03 


17 


0.04 


0.00 


0.00 


0.00 


0.00 


.30 


.88 


.12 


0.00 


•17 


.05 


.03 


18 


0.00 


0.00 


0.00 


0.00 


.04 


.04 


1.04 


.01 


0.00 


1.25 


.04 


.02 


19 


0.00 


0.00 


0.00 


0.00 


.02 


.55 


.09 


.01 


.02 


2.45 


.04 


0.00 


20 


0.00 


0.00 


0.00 


0.00 


.28 


0.00 


.02 


.02 


.47 


.50 


.09 


0.00 


21 


0.00 


0.00 


0.00 


0.00 


.20 


.58 


.13 


1.76 


3.54 


2.19 


0.00 


0.00 


22 


0.00 


0.00 


0.00 


0.00 


5.58 


.50 


.15 


.10 


1.00 


2.96 


.11 


0.00 


23 


0.00 


0.00 


0.00 


0.00 


2.04 


.01 


0.00 


.23 


.17 


.02 


0.00 


0.00 


24 


.15 


0.00 


.08 


0.00 


1.73 


1.40 


.58 


.08 


.79 


.05 


0.00 


0.00 


25 


0.00 


0.00 


0.00 


0.00 


.56 


.06 


.04 


.53 


.10 


.30 


.02 


0.00 


26 


.06 


0.00 


0.00 


0.00 


.41 


2.31 


.13 


.09 


1.43 


.15 


.02 


0.00 


27 


0.00 


0.00 


0.00 


0.00 


0.10 


1.76 


.15 


.61 


3.18 


.05 


.15 


.12 


28 


0.00 


0.00 


0.00 


0.00 


0.00 


4.18 


.09 


.31 


.25 


.23 


.02 


1.19 


29 


0.00 


0.00 


0.00 


0.00 


.01 


.04 


0.00 


.59 


0.00 


0.00 


.05 


.58 


oi) . ... ... 


0.00 


0.00 


0.00 


0.00 


.33 


0.00 


3.49 


.05 


0.00 


.05 


0.00 


.10 


31 


0.00 


0.00 


0.00 


• • • • 


0.00 


• • • • 


.01 


.02 


• • • • 


0.00 


• • • • 


.05 


Totals.. 


.25 


0.00 


.08 


.08 


11.30 


14.86 


11.42 


6.17 


16.60 


25.70 


6.01 


2.41 



DAILY RAINFALL AT RIVAS FOR 1898. 



Day. Jan. Feb. Mar. Apr. May. June. July. Augr. Sept. Oct. Nov. Dec. 

1 

2 

8 

4 

6 

6 

7 

8 

9 

10 



0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.09 


0.00 


0.07 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


1.42 


0.00 


0.44 


0.34 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.40 


1.00 


0.40 


1.60 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.55 


0.06 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.53 


0.00 


0.09 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.16 


0.00 


0.00 


0.00 


0.14 


0.23 


0.00 


0.00 


0.00 


0.00 


0.04 


0.00 


0.00 


0.04 


1.97 


0.80 


0.21 


0.08 


0.10 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.13 


0.00 


0.00 


0.06 


1.91 


2.76 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.15 


0.78 


0.00 


1.38 


0.80 


0.04 


0.20 


0.00 


0.00 


0.00 


0.00 


0.00 


0.40 


0.40 


0.00 


0.00 


0.63 


0.04 


0.00 



APPENDIX III.— HYDROGRAPHIC REPORT 



265 



DAILY RAINFALL AT RIVAS FOR 1898.— Continued. 



Day. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug, 


Sept. 


Oct 


Nov. 


Dec. 


11 


0.12 


0.00 


0.00 


0.00 


0.11 


0.00 


0.00 


0.20 


0.80 


0.43 


1.23 


0.00 


12 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.20 


0.00 


1.77 


0.00 


18 


0.00 


0.00 


0.00 


0.00 


0.00 


0.16 


0.00 


1.71 


0.00 


0.00 


0.69 


0.00 


14 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.80 


1.26 


1.57 


0.00 


0.00 


15 


0.00 


0.00 


0.00 


0.00 


0.60 


0.08 


0.00 


0.08 


1.77 


1.65 


0.37 


0.00 


16 


0.00 


0.00 


0.00 


JO. 00 


0.00 


0.00 


0.00 


0.00 


0.86 


2.56 


0.38 


0.08 


17 


0.15 


0.00 


0.00 


0.00 


0.00 


1.16 


1.18 


0.00 


0.59 


0.00 


0.00 


0.06 


18 


0.00 


0.00 


0.00 


0.00 


0.20 


3.98 


0.86 


0.00 


0.00 


0.30 


0.00 


0.00 


19 


0.00 


0.12 


0.00 


0.00 


3.15 


1.26 


0.18 


0.00 


0.37 


0.89 


0.13 


0.00 


20 


0.00 


0.00 


0.00 


0.00 


1.30 


1.67 


0.00 


0.00 


2.16 


1.22 


0.00 


0.00 


21 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.80 


3.15 


0.87 


1.75 


0.00 


0.00 


22 


0.00 


0.00 


0.00 


0.00 


5.33 


3.22 


0.00 


0.40 


0.43 


1.78 


0.00 


0.00 


28 


0.00 


0.00 


0.00 


0.00 


4.57 


0.40 


0.40 


0.60 


0.30 


0.00 


0.00 


0.00 


24 


0.18 


0.00 


0.00 


0.00 


0.79 


0.40 


0.00 


0.04 


0.00 


0.12 


0.00 


0.00 


25 


0.00 


0.00 


0.06 


T. 


0.90 


0.30 


0.20 


0.37 


0.00 


0.47 


0.00 


0.00 


26 


0.62 


0.00 . 


0.00 


0.00 


0.20 


0.00 


0.00 


0.00 


1.26 


0.00 


0.00 


0.00 


27 


0.00 


0.00 


0.00 


0.00 


1.07 


4.72 


0.40 


0.00 


0.90 


0.00 


0.36 


0.23 


28 


0.00 


0.00 


0.00 


0.00 


00 


1.18 


0.00 


0.40 


0.09 


0.98 


0.31 


2.15 


29 


0.00 


0.00 


0.00 


0.00 


0.79 


0.00 


0.00 


1.77 


0.00 


0.00 


0.00 


0.00 


80 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


3.86 


0.00 


0.00 


0.79 


0.00 


0.10 


81 


0.00 


• • • • 


0.00 


• • • • 


0.00 


• • • • 


0.00 


0.00 


• • • • 


0.00 


• • • • 


0.25 


Totals.. 


1.07 


0.12 


0.10 


0.00 


16.17 


18.95 


13.65 


11.85 


13.99 


20.83 


8.19 


3.14 



DAILY RAINFALL AT THE MOUTH OF RIO LAS LAJAS AT CAMP CALDERA NEAR RIVAS, 

NICARAGUA. 



Day. Jan. Feb. 
1898. 


3far. 


Apr. 


May. 


June. 


July. 


Aug, 


Sept 


Oct 


Nov. 


*.^CC« 


JanI 

■loWf. 


Feb. 


Mar. 


1 


.00 


.00 


.00 


.00 


.00 


0.33 


.00 


0.01 


0.15 


.00 


0.03 


.01 


.00 


.00 


2 


.00 


0.04 


.00 


.00 


.00 


1.23 


.00 


.00 


.05 


.00 


0.09 


.00 


.00 


.00 


8 


.00 


.00 


.00 


.00 


.00 


0.24 


.00 


.00 


1.17 


.00 


.00 


.10 


.00 


.00 


4 


.00 


.00 


.00 


.00 


.00 


.00 


0.37 


0.27 


.01 


0.17 


.00 


.02 


.00 


.00 


5 


.00 


.00 


0.12 


.00 


0.33 


.00 


.00 


.00 


.43 


.00 


.00 


.03 


.00 


.00 


6 


.00 


.00 


0.02 


0.08 


.00 


.00 


1.40 


0.08 


.00 


.00 


.00 


.00 


.00 


.00 


7 


.00 


0.01 


.00 


.00 


0.74 


0.26 


0.11 


^.01 


.96 


0.12 


.00 


.00 


.00 


.03 


8 


.00 


.00 


.00 


.00 


0.09 


.00 


0.21 


0.04 


.93 


0.07 


.00 


.00 


.00 


.00 


9 


0.05 


.00 


.00 


.00 


0.08 


0.16 


.00 


0.05 


1.07 


1.20 


0.18 


.00 


.06 


.00 


10 


.00 


.00 


.00 


.00 


0.40 


0.85 


.00 


0.46 


.58 


0.06 


.00 


.00 


.00 


.00 


11 


.00 


.00 


.00 


0.06 


0.02 


0.83 


.00 


0.03 


.12 


0.01 


.00 


.13 


.00 


.00 


12 


.00 


.00 


0.05 


.00 


0.05 


.00 


0.05 


0.02 


.00 


0.90 


.00 


.03 


.00 


.00 


18 


.00 


.00 


.00 


.00 


0.01 


0.07 


0.04 


1.06 


.29 


1.07 


0.01 


.05 


.00 


.00 


14 


.00 


.00 


.00 


.00 


.00 


0.02 


0.41 


0.62 


1.01 


.00 


.00 


.00 


.00 


.00 


15 


.00 


0.08 


.00 


0.03 


.00 


0.03 


.00 


0.10 


1.74 


.00 


.00 


.15 


.00 


.00 


16 


.00 


0.04 


.00 


0.16 


.00 


0.30 


0.01 


.00 


2.49 


0.15 


0.01 


.00 


.00 


.00 


17 


.00 


.00 


.00 


.00 


0.84 


0.67 


0.13 


.00 


.04 


0.05 


.00 


.00 


.30 


.00 


18 


.00 


.00 


.00 


0.03 


0.22 


0.62 


0.08 


.00 


.64 


.00 


0.01 


.00 


.00 


.00 


19 


.00 


.00 


.00 


0.58 


0.43 


0.26 


.00 


0.09 


.20 


0.06 


00 


.00 


.25 


.00 


20 


.00 


.00 


.00 


0.66 


0.51 


0.06 


0.01 


0.04 


.59 


0.10 


.00 


.00 


.05 


.00 



266 



NICARAGUA CANAL COMMISSION 



Day. 



DAILY RAINFALL AT THE MOUTH OP RIO LAS LAJAS AT CAMP CALDERA NEAR RIVAS. 

NICARAGUA .—Continued. 



Jan. 



Feb. 



Mar. 



Apr. May. June. July. Aug. Sept. 



Oct. 



Nov. Dec. 



Jan. 
1899. 



Feb. 



Mar. 



21 




.00 


.00 


0.05 


0.03 


1.40 


0.33 


3.61 


2.47 


1.03 


.00 


.00 


.00 


.00 


.00 


22 . 




.00 


.00 


.00 


3.99 


2.04 


0.21 


0.07 


0.04 


.18 


.00 


0.13 


.00 


.00 


.00 


23 




.00 


0.02 


.00 


1.44 


0.06 


0.40 


0.01 


0.03 


.02 


^ •N 


.00 


.01 


.00 


.00 


24 . 




.00 


1.11 


.00 


1.89 


0.85 


0.29 


.00 


0.10 


.00 


.00 


.00 


.00 


.00 


25 




.00 


.00 


.00 


0.19 


0.03 


0.06 


0.15 


0.03 


1.08 ^ 


0.20 


► .00 


.00 


.00 


.00 


26 


.06 


00 


.01 


0.03 


0.67 


0.97 


0.18 


0.10 


0.19 


0.00 




.00 


.00 


.00 


.00 


27 


.00 


.00 


.00 


.00 


0.06 


3.22 


0.07 


0.48 


0.19 


0.11 


0.06 


0.10 


.00 


.00 


.00 


28 


.00 


.00 


.00 


0.01 


.00 


1.09 


0.54 


.00 


0.86 


1.34 


0.18 


1.82 


.00 


.01 


.00 


29 


.00 


« • 


.00 


.00 


0.02 


0.10 


.00 


1.07 


.00 


0.01 


.00 


0.12 


.00 




.00 


30 . 


• • • Si 


• • 


.00 


.00 


0.70 


0.02 


3.18 


0.13 


.00 


0.00 


0.01 


0.04 


.00 


» • • 


.00 


31 


.00 


• • 


0.08 


• • • • 


0.02 


. . ■ • 


.00 


0.05 


• • • • 


0.00 


« • • • 


0.22 


.00 


» • • 


.30 


Totals 


.06 


.05 


1.34 


.28 


10.60 


13.50 


10.64 


8.44. 


6.79 


16.19 


4.41 


3.26 


0.53 0.67 


.83 



DAILY RAINFALL AT PASO REAL DEL RIO VIEJO. 



Day. Feb. Mar. 
1886. 

1 joio !oo" 

2 00 .00 

3 00 .42 

4 00 .22 

5 00 .00 

6 00 .00 

7 00 .00 

8 00 .00 

9 00 .00 

10 00 .00 

11 00 .00 

12 00 .00 

13 T. .00 

14 00 .00 

15 00 .00 

16 00 .00 

17 00 .00 

18 00 .00 

19 00 .00 

20 00 .01 

21 00 .00 

22 T. .01 

23 01 .00 

24 00 .00 

25 00 .00 

26 00 .00 

27 00 .00 

28 00 .00 

29 .00 

30 .00 

31 .00 

Totals.. !oi .66 



Apr. May. 



.00 
.00 
.00 
.00 
.00 

T. 
.00 
.00 
.00 
.00 

.00 
.00 
T. 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

• • • 

"iooT 



.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.87 
2.42 
.71 

2.51 
2.83 
1.65 
1.91 
.47 

.05 
.35 
.00 
.00 
.00 
.01 
18.78 



June. 

.00 
.00 
.00 
.00 
.00 

.00 
1.25 
.14 
.00 
.80 

.71 
.05 
.00 
.00 
.00 

.00 
.00 

3.68 
.63 

l.OO 

1.90 
.52 
.19 
.82 

.13 

.00 
.08 
3.56 
.00 
.00 

• • • 

18.45 



July. Aug. 



.00 
.16 
.00 
.00 
.00 

.81 
.18 
.00 
.30 
.70 

.70 
.87 
.00 
.05 
.18 

.00 
.00 
.00 
.00 
.13 

.00 
.00 
.08 
.00 
.00 

.00 
.03 
.62 
.03 
.38 
.03 
4.01 



.88 
.18 
.00 
.06 
.60 

.03 
.00 
.00 
.00 
.00 

.41 

.11 

.81 

1.16 

1.08 

.38 
.50 
.50 
.50 
.50 

.50 
.36 
.00 
.00 
.00 

.08 
.01 
3.78 
.83 
.07 
.00 

11.66 



Sept. 

.00 
.00 
.33 
.00 
.16 

.50 
.01 
.00 
.00 
.40 

.38 
.00 

1.40 
.00 

1.70 

.00 
.00 
.00 
1.85 
.41 

.03 
.07 
.10 
.00 
.00 

.36 
.39 
.01 
.00 
.05 

• • • 

7.38 



Oct. 

.00 
1.08 
.31 
.02 
.01 

.48 
.36 

.77 
.03 
.00 

.19 
.37 
.30 
.54 
.03 

.17 

.00 

3.31 

.83 

.87 

.08 
.07 
.03 
.00 
.01 

.39 
.00 
.00 
.16 
.01 
.00 
8.99 



Nov, 

.00 
.00 
.00 
.03 
.00 

.01 
.00 
.06 
.18 
.01 

.03 
.38 
.03 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
T. 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

• • • 



Dec. 

.00 
.00 
.00 
.16 
.00 

.00 
.00 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.00 

.00 

.0 

.00 

.00 

.00 
.01 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 
.00 

.17 



Jan. 
1890. 

.00 
,00 
.08 
00 
.00 

.01 
.00 
.00 
.00 
00 

.00 
00 
.00 
.00 
.00 

.00 
00 
.00 
.00 
.00 

.00 
.00 



0.4 



NICARAGUA CANAL COMMISSION 


^ 




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R h 








































































































































D 


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3 


-A 


SI. 


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. 
























































Rl(3 








































































































































L 


/f 


' 


3 


-/ 


S 


V 






















1 






























1 






















1, 


,11 




It M K t 






Kl 












« 






» 




yj Ji 


I M l> 







JANUARY FEBRUARY MARCH APRIL 



DIAGRAM OF THE DAILY RAI 



APPENDIX 3, PLATE XII 
UGUST 8EPTCMSER OCTOBER NOVCMBER DECCMeCR 



1. 



I; 



ik 



I 



lU 



ilJ 



m 



^ 



JUL> AUCUS-T SEPTEMBER OCTOBER 

i,T TIPITAPA AND RIO VIEJO. 1893. 



MBER ' DECEMBER 



APPENDIX III.— HYDROGRAPHIC REPORT 



267 



DAILY RAINFALL AT TIPITAPA. 



Day. 


Feb. 

lovD. 


Mai. 


Apr. 


May. 


June 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Jan. 
1899. 


1 


.00 


.00 


.00 


.00 


.00 


.80 


.23 


.87 


.00 


.00 


.00 


T. 


2 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
.00 


.26 
.00 


.16 
.04 


.37 
.45 


.00 
.10 


.00 
.00 


.12 
T. 


.00 


3 


.00 


4 


.00 
•00 


.00 
.00 


.00 
T. 


.00 
.00 


.81 
.00 


.00 
.00 


.18 
.00 


.05 
1.03 


.30 
.00 


.11 
.00 


.00 
.00 


.25 


5 


.00 


6 


.00 


.00 


.00 


.00 


.00 


.08 


.00 


.25 


.02 


.00 


.00 


.00 


7 


.00 


.00 


.00 


.00 


.73 


.00 


.81 


.56 


.00 


.00 


t. 


T. 


8 


.00 


.00 


.00 


.00 


.90 


.00 


.01 


.21 


1.72 


.00 


.00 


.00 


9 


.00 


.00 


.00 


.00 


T. 


3.30 


.14 


.15 


.68 


.03 


.00 


T. 


10 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
T. 


.26 

.78 


.19 
.20 


.06 
.40 


.48 
.87 


.02 
.52 


.00 
.01 


.00 
.00 


.00 


11 


.00 


12 


.00 
.00 
.00 


.00 
.00 
.00 


.00 
.00 
.00 


.00 
.00 
.00 


.81 
.04 
.00 


.00 
.00 
.00 


.02 
.01 
.32 


.87 

2.21 

.71 


.00 
.34 
.07 


.71 
.00 
.00 


.00 
.00 
.00 


.00 


13 


.00 


14 


.00 


15 


.00 


.00 


.00 


.00 


.00 


.00 


.00 


.02 


.09 


.00 


.00 


.00 


16 


.00 


•00 


.00 


.22 


.00 


.00 


.35 


.14 


.21 


.00 


.00 


.00 


17 


.00 


.00 


.00 


.00 


.00 


.10 


.01 


.00 


.00 


.00 


.00 


.01 


18 


.00 
.00 
.00 


.00' 

.00 

.00 


.00 
.00 
.00 


3.10 

1.22 

.12 


3.19 
.22 
.32 


.14 
.00 
.00 


.00 
.03 
.04 


.00 
.30 
.01 


.60 

.00 

1.40 


.00 

.00 

T. 


.02 
.00 
.00 


.00 


19 


.00 


20 


.00 


21 


.00 
T. 


.00 
.00 


.00 
.00 


.04 
1.08 


2.08 
.96 


.14 

.18 


.21 
T. 


1.86 
.15 


.00 
.04 


.00 
T. 


.00 
.00 


.00 


22 


.00 


as 


.00 


.26 


.00 


.52 


.00 


.00 


.81 


01. 


.00 


.07 


.00 


.00 


24 


.00 


.00 


.00 


.60 


8.17 


.00 


.09 


T. 


/• "^ 


.00 


.00 




25 


.00 


.00 


.00 


.52 


.24 


.00 


.00 


.00 




.00 


.00 




26 


.00 


.00 


.00 


.89 


.00 


.00 


.00 


.85 




.00 


.00 




27 


.00 


.00 


.00 


.12 


.86 


.12 


.03 


1.20 ^ 


1.01 


► .00 


.00 




28 


.00 


.00 


.00 


.00 


2.29 


.02 


2.10 


.13 




.00 


.00 




29 


• • • 


.00 


.00 


.00 


.00 


.07 


.75 


.00 




.00 


.00 




«0 


• • • 


.00 


.00 


.00 


.27 


.54 


.00 


.00 




.00 


.08 




81 


• • • 


.00 


• • 


.13 


• • 


.10 


1.58 


• • 


> ^ 


• • 


.00 




Total 


.00 


.26 


.00 


8.56 


16.88 


6.24 


7.82 


11.25 


7.12 


.93 


.17 


.26 



DAILY RAINFALL AT MORRITO FOR 1898. 



Day. 

1 

2 

8 

4 

5.... 

6 

7 

8.... 

9 

10. . . . 



April. 



.01 
.08 
.00 
.00 
.00 



May. 

.02 
.00 
.00 
.00 
.06 

.00 
.00 
.00 
.39 
.00 



June. 

.00 
.00 
.02 
1.17 
.22 

.00 
.18 
.00 
.67 
.46 



July. 

.50 
1.82 
.16 
.20 
.15 

.88 
.30 
.06 
.24 
.19 



Aug. 

.00 
11 
.08 
.00 
.12 

.08 
.04 
.00 
.62 
.00 



APPENDIX III.— HYDROGRAPHIC REPORT 



267 



DAILY RAINFALL AT TIPITAPA. 



Day. 


Feb. 

1898. 


Mai. 


Apr. 


May. 


June 


July. 


Aug. 


Sept, 


Oct. 


Nov. 


Dec. 


Jan. 
1899. 


1 


.00 


.00 


.00 


.00 


.00 


.80 


.23 


.37 


.00 


.00 


.00 


T. 


o 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
.00 


.26 
.00 


.16 
.04 


.37 
.45 


.00 
.10 


.00 
.00 


.13 
T. 


.00 


3 


.00 


4 


.00 
•00 

.00 
.00 


.00 
.00 

.00 
.00 


.00 
T. 

.00 
.00 


.00 
.00 

.00 
.00 


.31 
.00 

.00 
.73 


.00 
.00 

.08 
.00 


.18 
.00 

.00 
.81 


.05 
1.03 

.25 
.56 


.30 
.00 

.02 
.00 


.11 
.00 

.00 
.00 


.00 
.00 

.00 
t. 


.25 


5 


.00 


6 


.00 


7 


T. 


8 


.00 
.00 


.00 
.00 


.00 
.00 


.00 
.00 


.90 
T. 


.00 
3.30 


.01 
.14 


.21 
.15 


1.72 
.68 


.00 
.03 


.00 
.00 


.00 


9 


T. 


10 


.00 


.00 


.00 


.00 


.26 


.19 


.00 


.48 


.02 


.00 


.00 


.00 


11 


.00 


.00 


.00 


T. 


.78 


.20 


.40 


.87 


.52 


.01 


.00 


.00 


12 


.00 


.00 


.00 


.00 


.81 


.00 


.02 


.37 


.00 


.71 


.00 


.00 


13 


.00 


.00 


.00 


.00 


.04 


.00 


.01 


2.21 


.34 


.00 


.00 


.00 


14 


.00 


.00 


.00 


.00 


.00 


.00 


.32 


.71 


.07 


.00 


.00 


.00 


15 


.00 


.00 


.00 


.00 


.00 


.00 


.00 


.02 


.09 


.00 


.00 


.00 


16 


.00 


•00 


.00 


.22 


.00 


.00 


.35 


.14 


.21 


.00 


.00 


.00 


17 


.00 


.00 


.00 


.00 


.00 


.10 


.01 


.00 


.00 


.00 


.00 


.01 


18 


.00 
.00 
.00 


.00' 

.00 

.00 


.00 
.00 
.00 


3.10 

1.22 

.12 


3.19 
.22 
.32 


.14 
.00 
.00 


.00 
.03 
.04 


.00 
.30 
.01 


.60 

.00 

1.40 


.00 

.00 

T. 


.02 
.00 
.00 


.00 


19 


.00 


20 


.00 


21 


.00 
T. 


.00 
.00 


.00 
.00 


.04 
1.08 


2.08 
.96 


.14 

.18 


.21 
T. 


1.36 
.15 


.00 
.04 


.00 
T. 


.00 
.00 


.00 


22 


.00 


23 


.00 


.26 


.00 


.52 


.00 


.00 


.81 


01. 


.00 


.07 


.00 


.00 


24 


.00 
.00 


.00 
.00 


.00 
.00 


.60 
.52 


8.17 
.24 


.00 
.00 


.09 
.00 


T. 
.00 


^ ■v 


.00 
.00 


.00 
.00 




25 




26 


.00 


.00 


.00 


.89 


.00 


.00 


.00 


.35 




.00 


.00 




27 


.00 


.00 


.00 


.12 


.36 


.12 


.03 


1.20 ^ 


1.01 


► .00 


.00 




28 


.00 


.00 


.00 


.00 


2.29 


.02 


2.10 


.13 




.00 


.00 




29 


• • • 


.00 


.00 


.00 


.00 


.07 


.75 


.00 




.00 


.00 




50 


• • • 


.00 


.00 


.00 


.27 


.54 


.00 


.00 




.00 


.03 




81 


• • • 


.00 


• • 


.13 


• • 


.10 


1.53 


« • 


^ 


■ • 


.00 




Total 


.00 


.26 


.00 


8.56 


16.88 


6.24 


7.83 


11.25 


7.12 


.93 


.17 


.26 



DAILY RAINFALL AT MORRITO FOR 1898. 



Day. 

1... 

2..., 

3... 

4... 

5... 

6... 
7... 
8... 
9... 
10. . . 



April. 



.01 
.03 
.00 
.00 
.00 



May. 

.02 
.00 
.00 
.00 
.06 

.00 
.00 
.00 
.39 
.00 



June. 

.00 
.00 
.02 
1.17 
.22 

.00 
.18 
.00 
.67 
.46 



July. 

.50 
1.82 
.16 
.20 
.15 

.38 
.80 
.06 
.24 
.19 



Aug. 

.00 
11 
.03 
.00 
.12 

.08 
.04 
.00 
.62 
.00 



268 



NICARAGUA CANAL COMMISSION 



DAILY RAINFALL AT MORRITO FOR 1898.— Continued. 



Day. 

11... 
12... 
18... 
14.... 
15. . . , 

16.... 

17 

18 

19.... 
20. . . . 

21 

22.... 

23 

24 

25... 

26. . . . 
27. . . . 

28 

29. . . . 
30. . . . 
31 ... . 



April. 



May. 



June. 



July. 



Aug. 



.00 
.00 
.00 
.00 
.00 

.00 
.02 
.00 
.00 
.00 

.00 
.00 
.00 
.00 
.00 

.01 
.00 
.00 
.00 
.00 



.08 
.00 
.00 
.00 

.81 

.06 
.00 
.39 
.03 
.05 

.36 
1.58 
1.84 
2.05 

.00 

.00 
.20 
.00 
.46 
.08 
.51 



.98 
.05 
.00 
.17 
.00 

.05 

.00 

L53 

1.58 

.70 

1.38 

1.85 

.02 

.22 

.16 

.53 
.58 
.87 
.12 
.59 



.20 
.00 
.00 
.86 
.11 

.72 
.24 
.20 
8.14 
.21 

.02 
.86 
.60 
.38 
.70 

.35 
.27 
.17 
.00 
1.77 
.04 



.08 
.00 
2.95 
.00 
.05 

1.03 
.00 
.30 
.04 

0.71 

.12 
.00 
.41 
.00 

.58 

1.24 
1.17 
.07 
.37 
.08 
.00 



Totals. 



.07 



8.92 



14.05 



13.84 



10.20 



DAILY RAINFALL AT FORT SAN CARLOS. 



Day. 


Mar. 

1808. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Jan. 
1889. 


Feb. 


Mar. 


Apr. 


1 


• • 


.00 


.51 


.01 


.42 


.19 


.07 


.00 


.04 


.90 


.85 


.00 


.06 


.00 


2 


• • 


.00 


.13 


.00 


.61 


.32 


.79 


.11 


.00 


.22 


.00 


.15 


.00 


.00 


3 


• • 


.05 


.00 


.02 


1.66 


.18 


.09 


.01 


.00 


.12 


H 


.00 


.06 


.00 


4 




.05 


.02 


.00 


.57 


.00 


.05 


.48 


.65 


.10 


.10 


.00 


.00 


5 


• • 


.59 


.06 


.02 


.06 


.67 


.18 


.00 


.21 


.04 


.17 


.00 


.00 


.02 


6 


• • 


.31 


.08 


.00 


.91 


.58 


.07 


.11 


.00 


.31 


.00 


.24 


.12 


.32 


7 


■ • 


.30 


T 


.35 


.07 


.13 


.81 


.00 


.00 


.18 


.03 


.00 


.04 


.04 


8 


.22 


.00 


T 


.00 


.62 


.07 


.41 


1.23 


.69 


.04 


.06 


.00 


.21 


.09 


9 


.00 


.01 


.88 


.26 


1.05 


.97 


.11 


.04 


.27 


.19 


.88 


.00 


.00 


.29 


10 


.01 


.00 


.33 


.44 


.00 


.47 


.08 


.02 


.53 


.17 


.17 


.00 


.00 


.40 


11 


.00 


.44 


1.00 


.00 


.64 


.13 


3.64 


.02 


.67 


.10 


.05 


.00 


.00 


.22 


12 

13 


.00 
.00 


.15 
.00 


.00 
.00 


.01 
1.56 


.65 
.00 


.08 
1.80 


.68 
.22 


.05 
1.57 


ji.25; 


.07 
.08 


.47 

.05 


.54 

.08 


.04 
.00 


.10 
.00 


14 

15 


.00 
.00 


.00 
.00 


.00 
.19 


.18 
.02 


.33 
.12 


.08 
.00 


2.21 
.00 


.10 
.71 


.89 
.85 


.00 
.00 


.58 1 


.00 
.13 


.00 
.10 


.00 
.00 


16 

17 


.00 
.00 


.00 
.25 


.02 
.33 


.02 
.00 


.00 
.32 


.07 
.01 


.12 
.12 


.00 
.60 


1.05 
.91 


.56 
.44 


j .53 . 


.11 
.59 


.00 
.00 


.00 
.00 


18 


.00 


.00 


3.05 


1.96 


.18 


.00 


.17 


1.07 


.11 


.02 


.26 


.08 


.00 


.00 


19 


.00 


.00 


.26 


1.02 


.57 


.57 


.04 


.18 


.00 


.00 


.05 


.82 


.00 


.00 


20 


.22 


.01 


.87 


1.66 


.97 


.04 


.84 


.11 


.20 


.00 


.00 


.00 


.00 


.00 



APPENDIX III.— HYDROGRAPHIC REPORT 



269 



DAILY RAINFALL AT PORT SAN CARLOS.— Continued. 



Day. 


Mar. 
1898. 


April. 


May. 


June. 


JAily. 


Vug. 


Sept. 


Oct. 


Nov. 


Dec. 


Jan. 

1899. 


Feb. 


Mar. 


Apr. 


21 


.10 


.03 


.16 


3.35 


.74 


.03 


.08 


.04 


.08 


.05 


.22 


.05 


.00 


.00 


23 


.06 


.03 


.25 


.67 


.39 


.03 


.05 


.04 


.05 


.05 


.08 


.00 


.00 


.00 


23 


.04 


.30 


.34 


.08 


.27 


.67 


.19 


.00 


.00 


.00 


.05 


.05 


.00 


.00 


24 


.21 


.00 


.19 


.14 


.44 


.05 


.00 


.80 


.00 


.00 


.25 


.00 


.00 


.00 


25 


.19 


.00 


.02 


1.36 


.27 


.04 


.00 


.50 


.97 


.00 


.05 


.00 


.00 


.00 


2fi 


.00 


.43 


.00 


.58 


.99 


-.14 


.04 


.73 


.90 


.07 


.10 


.12 


.00 


.00 


27 


.00 


.00 


.00 


.88 


.09 


.35 


.05 


.26 


23 


.03 


.05 


.25 


.00 


.00 


28 


.00 


.00 


.04 


.72 


.29 


.03 


.00 


.15 


.27 


.89 


.00 


.00 


.00 


.00 


29 


.03 


.00 


.33 


.57 


.02 


.06 


.00 


.00 


.04 


.24 


.10 


• • 


.00 


.00 


30 


.00 


00 


.10 


.23 


.04 


.02 


.00 


.00 


.00 


.31 


.00 


■ • 


.00 


.00 


31 


.13 


• • 


.06 


• • 


.06 


.73 


• • 


•00 


• • 


.44 


.20 


• • 


.42 


.00 


Totals. 


1.21 


3.00 


8.22 


15.56 


13.35 


8.00 


10.56 


8.93 


9.86 


5.62 


4.99 


2.79 


1.05. 


1.48 



MEAN OF DAILY RAINFALL AT FORT SAN CARLOS (March 8 to December 31), MORRITO (April 6 

to August 31), TIPITAPA (February 1 to December 31), RIO VIEJO (February 1 to 

December 31), LAS LAJAS (February 1 to December 31), 1898. 

Day. Feb. Mar. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 

1 ^00 ^00 [OO Al M ^41 ^35 Al ^04 ^01 ^8 

2 00 .01 .00 .03 .00 .72 .15 .29 .30 .00 .11 

8 00 .14 .01 .00 .01 .41 .05 .19 .38 .00 .03 

4 00 .07 .01 .00 .30 .15 .12 .09 .20 .24 .06 

5 00 .00 .18 .03 .11 .04 .28 .34 .11 .05 .01 

6 00 .00 .07 .08 .00 .34 .42 .22 .14 .00 .08 

7 00 .00 .07 .00 .65 .16 .24 .22 .33 .03 .05 

8 00 .06 .00 .00 .24 .14 .06 .16 1.16 .21 .01 

9 02 .00 ^00 .15 .20 1.01 .85 .08 .45 .41 .09 

10 00 00 .00 .07 .37 .39 .11 .34 .14 .15 .04 

11 00 .00 .09 .22 ..50 .41 .20 1.09 .21 .18 .03 

13 00 .00 .04 .00 .19 .20 .05 .27 .11 .64 .03 

13 00 .00 .00 .00 .33 .01 1.02 1.22 .62 .43 .03 

14 00 .00 .00 .00 .07 .35 .39 .88 .43 .10 .00 

15 00 .02 .00 .21 .00 .08 .23 .46 .64 .09 .00 

16 00 .01 .00 .09 .01 .20 .35 .06 .72 .30 .14 

17 00 .00 .05 .07 .17 .27 .13 .08 .16 .24 .11 

18 00 .00 .00 1.49 2.12 .23 .17 .04 1.13 .03 .01 

19 00 .00 .00 .90 .78 .79 .23 .45 .30 .02 .00 

20 00 .06 .00 .88 .84 .27 .26 .32 .74 .08 .00 

21 00 .03 .03 .63 3.01 .35 .89 .98 .39 .03 .01 

33 00 .03 .00 1.96 1.31 .33 .09 .08 .08 .01 .05 

33 00 .08 .06 * 1.16 .06 .26 .28 .08 .01 .03 .00 

24 00 .33 .00 1.83 .94 .22 .03 .02 .33 .01 .00 

35 00 .05 .00 .24 .38 .21 .15 .01 .43 .26 .00 

26 00 .00 .09 .32 .42 .29 .31 .21 .29 .24 .03 

27 00 .00 .01 .15 .91 .11 .41 .43 .13 .07 .03 

38 00 .00 .00 .01 1.51 .33 1.00 .25 .40 .11 .55 

29 01 .00 .16 .16 .02 .51 .00 .08 .01 .09 

30 .00 .00 .18 .32 1.16 0.6 ... .03 .00 .10 

31 .04 ... .15 .04 .46 ... .03 ... .17 

.03 .93 .70 10.14 14.70 9.60 9.35 8.93 10.30 3.97 3.06 



270 



NICARAGUA CANAL COMMISSION 



MEAN OF DAILY RAINFALL.— Continued. 

At Ft. San Carlos (January 1 to March 31), Las Lajas (January 1 to March 31), Tipitapa (January 1 to 

January 23), Rio Viejo (January 1 to January 22), Granada (January 24 to March 31), 1899. 





January. 






February. 








March. 






Day. 




Day. 




Day. 




Day. 




Day. 




Day. 




1.... 


.09 


17... 


.06 


1.... 


.00 


17. . . . 


.44 


1.... 


.02 


17... 


.00 


2.... 


.00 


18... 


.06 


2.... 


.07 


18... 


.03 


2.... 


.00 


18... 


.00 


3.... 


.09 


19... 


.01 


o. . . . 


.00 


19... 


.19 


3.... 


.02 


19... 


.00 


4 


.19 


20... 


.00 


4.... 


.03 


20... 


.02 


4.... 


.00 


20... 


.00 


5.... 


.05 


21... 


.06 


5. . . . 


.00 


21... 


.02 


«).... 


.00 


21... 


.00 


6. . . . 


.00 


22. . . 


.02 


6 


.08 


22.... 


.00 


6.... 


.04 


22. . . . 


.00 


7 


.01 


28... 


.02 


7.... 


.00 


23.... 


.01 


7.... 


.04 


23. . . . 


.00 


8 


.01 


24... 


.08 


KJ , ... 


.01 


24.... 


.00 


8 . . . . 


.07 


24. . . . 


.00 


9.... 


.10 


25... 


.02 


9.... 


.02 


25. . . . 


.00 


9. . . . 


.00 


25. . . . 


.00 


10 


.04 


26... 


.03 


10.... 


.00 


26... 


.04 


10.... 


nOO 


26... 


.00 


11.... 


.04 


27. . . 


.02 


11 


.00 


27... 


.08 


11 


.00 


27... 


.00 


12.... 


.12 


28... 


.00 


12 


.18 


28... 


.00 


12 


.01 


28... 


.00 


13.... 


.03 


29... 


.03 


13.... 


.02 






13 


.00 


29... 


.00 


14 


.10 


30... 


.00 


14.... 


•00 






14 


.00 


30... 


.02 


15. . . . 


.08 


31... 


.07 


15.... 


.04 






15 


.03 


81... 


.24 


16.... 


.08 






16.... 


.04 






16 


.00 












1.51 








1.32 








0.49 



ACCUMULATED RAINFALL IN THE BASIN OF LAKE NICARAGUA. 
Obtained by taking the mean of the accumulated rainfall at Ft. San Carlos from March 8, 1898, to March 31, 1899; 
Morrito from April 6, 1898, to August 31, 1898; Tipitapa from February 7, 1898, to January 23, 1899; 
Rio Viejo from February 1, 1898, to January 22, 1899; Las Lajas from February 1, 1898, to 
March 31, 1899; Granada from January 24, 1898, to March 31, 1899. 



^ 


Feb. 


Mar. 


Apr. 


Biay. 


June. 


July. 


Augr. 


Sept. 


Oct 


Nov. 


Dec. 


Jan. 


Feb. 


Mar. 


d 


1808. 












. 










1899. 






1 


• • • • 


.02 


.94 


1.75 


11.68 


26.79 


36.23 


45.34 


54.19 


64.46 


68.65 


70.57 


72.12 


73.46 


2 


• • • • 


.08 


.94 


1.78 


11.68 


27.51 


86.38 


45.63 


54.49 


64.46 


68.76 


70.57 


72.19 


73.46 


8 


• • • • 


.17 


.95 


1.78 


11.69 


27.92 


86.43 


45.82 


54.87 


64.40 


68.79 


70.85 


72.19 


73.48 


4 


• • • • 


.24 


.96 


1.80 


11.99 


28.07 


86.55 


45.91 


55.07 


64.70 


68.85 


70.86 


72.22 


73.48 


5 


• • • • 


.24 


1.14 


1.88 


12.10 


28.11 


36.83 


46.25 


55.18 


64.75 


68.86 


70.91 


72.22 


73.48 


6 


• • • • 


.24 


1.21 


1.88 


12.10 


28.45 


37.25 


46.47 


55.82 


64.75 


68.94 


70.91 


72.80 


73.52 


7 


• • • • 


.24 


1.28 


1.88 


12.75 


28.61 


87.49 


46.69 


55.65 


64.78 


68.99 


70.92 


72.30 


73.56 


8 


• • • • 


.30 


1.28 


1.88 


12.99 


28.75 


37.55 


46.85 


56.81 


64.99 


69.00 


70.93 


72.81 


73.63 


9 


.02 


.30 


1.28 


1.98 


18.19 


29.76 


87.90 


46.93 


57.26 


65.40 


69.09 


71.02 


72.83 


73.63 


10 


.02 


.30 


1.28 


2.05 


18.56 


80.15 


38.01 


47.27 


57.40 


65.55 


69.13 


71.06 


72.33 


73.63 


11 


.02 


.30 


1.87 


2.27 


14.06 


80.56 


38.21 


48.36 


57.61 


65.73 


69.10 


71.11 


72.33 


73.63 


12 


.02 


.30 


1.41 


2.27 


14.25 


80.76 


38.26 


48.63 


57.72 


66.87 


69.18 


71.23 


72.51 


78.64 


18 


.02 


.30 


1.41 


2.27 


14.57 


80.77 


89.28 


49.85 


58.34 


66.80 


69.20 


71.25 


72.53 


73.64 


14 


.02 


.30 


1.41 


2.27 


14.64 


81.02 


39.67 


50.78 


58.77 


66.90 


69.20 


71.25 


72.53 


73.64 


15 


.02 


.32 


1.41 


2.48 


14.64 


81.10 


39.90 


51.19 


59.41 


66.99 


69.20 


71.43 


72.57 


73.67 


16 


.02 


.33 


1.41 


2.57 


14.65 


81.30 


40.25 


51.25 


60.13 


67.29 


69.34 


71.43 


72.61 


73.67 


17 


.02 


.33 


1.46 


2.64 


14.82 


81.57 


40.88 


51.28 


60.29 


67.53 


69.45 


71.49 


73.05 


73.67 


18 


.02 


.33 


1.46 


4.18 


16.94 


81.80 


40.55 


51.32 


61.42 


67.56 


69.46 


71.65 


73.08 


78.67 


19 


.02 


.33 


1.46 


5.08 


17.72 


82.59 


40.78 


51.77 


61.72 


67.58 


69.46 


71.66 


73.27 


73.67 


20 


.02 


.39 


1.46 


5.41 


18.56 


82.86 


41.04 


52.09 


62.46 


67.66 


69.46 


71.60 


73.29 


73.67 


21 


.02 


.41 


1.48 


6.08 


20.57 


88.11 


41.95 


53.07 


62.75 


67.68 


69.47 


71.71 


73.81 


73.67 


22 


.02 


.43 


1.48 


7.98 


21.78 


88.34 


42.02 


53.15 


62.83 


67.69 


69.52 


71.78 


73.81 


78.67 


23 


.02 


.51 


1.54 


9.14 


21.84 


83.60 


42.30 


53.23 


62.84 


67.72 


69.52 


71.75 


78.32 


78.07 


24 


.02 


.84 


1.54 


10.47 


22.78 


88.82 


42.38 


53.25 


68.07 


67.78 


69.52 


71.87 


73.32 


73.67 


25 


.02 


.89 


1.54 


10.71 


28.16 


84.03 


42.48 


53.26 


63.50 


67.99 


69.52 


71.90 


73.32 


73.67 


26 


.02 


.89 


1.63 


11.08 


28.58 


84.32 


42.79 


53.47 


63.79 


68.23 


69.54 


71.95 


73.36 


73.67 


27 


.02 


.89 


1.64 


11.18 


24.49 


84.43 


43.20 


53.90 


63.91 


68.30 


69.57 


71.97 


73.44 


73.67 


28 


.02 


.89 


1.64 


11.19 


26.00 


84.76 


44.20 


54.15 


64.31 


68.41 


70.12 


71.97 


73.44 


73.67 


29 


• • • • 


.90 


1.64 


11.85 


26.16 


84.78 


44.71 


54.15 


64.39 


68.42 


70.21 


72.02 


• • • • 


73.67 


80 


• • • • 


.90 


1.64 


11.58 


26.88 


85.94 


44.77 


54.15 


64.42 


68.42 


70.31 


72.02 


• • • • 


73.69 


31 


• • • • 


.94 


• • • • 


11.68 


• • • • • 


85.98 


45.23 


• • • • 


64.45 


• • • • 


70.48 


72.12 


• • • • 


78.98 



APPENDIX III.— HYDROGRAPHIC REPORT 



271 



DAILY RAINFALL AT SABALOS ABOVE TORO RAPIDS. 



Day. Feb 
1898 


Mar. 

• 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Jan. 

1899. 


Feb. 


Mar. 


1.. .. 


.00 


.13 


1.34 


.07 


1.32 


.00 


.02 


.03 


.00 


1.75 


.76 


.02 


.22 


o 


.00 


.00 


.08 


.00 


1.78 


.95 


.02 


.58 


.00 


.06 


.12 


.06 


.00 


8.. .. 


.00 


.00 


.00 


.00 


1.68 


.42 


.10 


.52 


.03 


.09 


.32 


.00 


.06 


4.. .. 


.23 


.47 


.00 


.23 


.56 


.00 


.11 


.38 


.20 


.00 


.94 


.00 


.00 


5.. .. 


.18 


2.41 


.52 


.00 


.40 


.00 


.00 


.10 


.17 


.15 


.68 


.14 


.00 


6.. .. 


.00 


.29 


.00 


.00 


.00 


1.78 


.82 


.14 


.02 


.25 


.13 


.24 . 


.02 


7.. .. 


.00 


.00 


.73 


.36 


.15 


.21 


1.07 


.04 


.10 


.47 


.42 


.00 


.85 


8.. .. 


.30 


.00 


.02 


.00 


.20 


.04 


.05 


.96 


.12 


.55 


.39 


.00 


.91 


9.. .. 


.00 


.00 


.00 


.50 


.86 


.95 


.83 


.09 


.40 


.48 


.71 


.04 


.16 


10.. .. 


• • 


.05 


.25 


1.26 


.86 


.64 


.00 


.04 


.42 


1.30 


.82 


.00 


.03 


11.. .. 


• • 


.85 


3.05 


.05 


.82 


.32 


1.52 


•02 


.12 


.01 


.17 


.08 


.07 


13.. .. 


• • 


.22 


.00 


.12 


1.45 


.15 


2.61 


.90 


1.59 


.03 


1.38 


1.54 


.08 


13.. .. 


.00 


.00 


.17 


.12 


.12 


.79 


.57 


.13 


2.74 


.12 


.22 


.01 


.14 


14.. .. 


.00 


.00 


.00 


.86 


.12 


.15 


.26 


.09 


.13 


.00 


.93 


.01 


.16 


1.5.. .. 


.00 


.00 


.42 


.06 


.00 


.45 


.39 


.21 


.23 


.00 


.36 


.27 


.00 


16.. .. 


.01 


.00 


.00 


.05 


.78 


.01 


1.67 


.01 


2.14 


l.,56 


.33 


.11 


.00 


17.. .. 


.00 


.84 


.15 


•00 


.86 


.00 


.00 


8.18 


1.30 


1.25 


.00 


.67 


.11 


18.. .. 


.00 


.00 


1.07 


2.82 


.31 


.07 


.00 


.67 


.04 


.14 


.38 


.08 


.00 


19.. .. 


.00 


.00 


.43 


.65 


.65 


.27 


.17 


.58 


.00 


.00 


.00 


.09 


.00 


20.. . 


.03 


.00 


.04 


.57 


2.22 


.30 


.04 


1.40 


.19 


.00 


.09 


.03 


.00 



21.. 


.09 


.03 


.00 


.31 


1.52 


1.23 


.58 


•83 


.00 


.20 


.03 


.12 


.04 


.00 


22 . . 


.07 


.11 


.05 


.09 


1.76 


.48 


.19 


.22 


.10 


.03 


.12 


.27 


.00 


.04 


23.. 


.77 


.28 


.27 


.35 


.43 


.00 


.57 


.33 


.11 


.00 


.00 


.05 


.00 


.00 


24.. 


.00 


.64 


.00 


.00 


.62 


.42 


.32 


.00 


.22 


.16 


.00 


.20 


.62 


.00 


25.. 


.68 


.18 


.00 


.25 


1.48 


.90 


.51 


.00 


.38 


.42 


.00 


.00 


.04 


.00 


26.. 


.23 


.00 


.27 


.00 


1.42 


.90 


.00 


.00 


.66 


.56 


.00 


.05 


.00 


.00 


27.. 


.07 


.04 


.14 


.80 


.31 


.11 


.06 


.26 


.01 


.26 


.07 


.00 


.08 


.00 


28. 


.00 


.00 


.00 


.16 


1.11 


1.73 


.00 


.03 


.04 


.57 


.13 


.00 


.16 


.00 


29.. 


• • 


.07 


.00 


1.11 


1.76 


.07 


.36 


.00 


.00 


.02 


.33 


.01 


• • 


.00 


30.. 


• • 


.00 


.01 


.00 


.00 


.27 


.87 


.00 


.25 


.01 


.87 


.00 


• • 


.00 


31.. 


• • 


.00 


• • 


.30 


• • 


.00 


.37 


• • 


.02 


• • 


.34 


.02 


• • 


.38 




1.91 


2.10 


6.00 


11.69 


17.13 


20.69 


11.33 


11.42 


11.81 


12.17 


10.20 


9.82 


4.33 


2.73 



DAILY RAINFALL AT CASTILLO. ON SAN JUAN RIVER. 



Day. 


1888. 
June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


1899. 
Jan. 


Feb. 


Mar. 


1 




1.75 


.18 


.00 


.00 


.00 


1.38 


.55 


.13 


.36 


2 




1.81 


.61 


.00 


1.83 


.00 


.58 


.46 


.01 


.00 


3 




1.45 


.18 


.00 


.00 


.00 


.02 


.40 


.05 


.07 


4 




.12 


.35 


.00 


.00 


.14 


.00 


.76 


.20 


.02 


5 




.77 


1.23 


.00 


.00 


.17 


.13 


1.19 


.07 


T. 


6 




.01 


.27 


.00 


• • • • 


.00 


.27 


.03 


.60 


.00 


7 




.00 


.27 


.36 


• • • • 


.00 


.89 


.30 


T- 


.00 


8 




.18 


.13 


1.87 


.00 


.00 


.00 


.40 


.00 


.00 


9 




1.48 


.74 


.27 


.83 


1.86 


.80 


1.15 


.01 


.41 


lu 




.20 


.57 


.13 


.15 


.13 


1.38 


.07 


.05 


.27 



272 



NICARAGUA CANAL COMMISSION 



DAILY RAINFALL AT CASTILLO. ON SAN JUAN RIVER.— Continued. 



Day. 


June. 
1896. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Deo. 


Jan. 
1899. 


Feb. 


Mar. 


11 


■ • • ■ • • 


.89 


.41 


8.78 


.00 


.07 


.27 


.55 


.05 


.00 


12 


1 • • • • • 


.05 


.84 


.08 


.00 


1.07 


.21 


1.85 


2.00 


.01 


lo 


. .40 


.13 


.18 


.21 


.00 


8.18 


.08 


.82 


.00 


T. 


14.... 


* * • • • • 


.11 


1.15 


.09 


.00 


.02 


' .00 


.59 


.01 


.19 


15 


• • • • • 


.18 


.80 


.28 


.00 


.06 


.08 


.17 


.21 


.00 


16 


• • • ■ • 


.27 


.18 


2.51 


.00 


2.80 


.40 


.27 


.98 


.18 


17 


• • • • • 


.67 


.00 


.05 


.80 


2.29 


2.85 


.21 


.82 


.16 


18 


• • • • • 


.71 


.00 


.00 


.87 


.00 


.27 


.40 


.52 


.00 


19 


. 1.25 


•1.10 


.00 


.00 


.00 


.08 


.01 


.00 


.15 


.00 


20 


. 2.18 


.89 


.86 


.11 


.85 


.10 


.00 


.21 


.08 


T. 


21 


.88 


1.68 


.70 


.88 


.01 


.15 


.02 


.08 


.00 


.02 


22 


. 1.25 


.25 


.08 


4.05 


.03 


.01 


.00 


.00 


.01 


.01 


23 


. . . . • 


.94 


.00 


.54 


.00 


.01 


.00 


.00 


.18 


.05 


24 


. 1.00 


.08 


.17 


.00 


.29 


.04 


.00 


.84 


.85 


.00 


25 


. 1.14 


.21 


.67 


.00 


.40 


.51 


.00 


.00 


.00 


.03 


26 


. .18 


.40 


.23 


1.01 


.08 


1.01 


.00 


.00 


.01 


.00 


27 


.58 


.17 


.00 


.00 


.00 


.76 


.00 


.00 


.07 


T. 


28 


. .16 


2.26 


.37 


.00 


.02 


.59 


.00 


.00 


.06 


.00 


29 


. 1.50 


.81 


.39 


.00 


.00 


.04 


.00 


.01 


• • • • 


.00 


80 


.00 


.00 


.00 


.00 


.00 


.00 


1.94 


.01 


• • • • 


.00 


81 


« • • • ■ 


.00 


.00 


• • • • 


.08 


• • • • 


.54 


T. 


« • ■ • 


.29 


Total 


B.. 10.47 


18.92 


11.46 


16.22 


4.64 


14.04 


11.57 


10.32 


6.47 


2.02 






DAILY RAINFALL AT MACHUCA, 


ON SAN JUAN RIVER. 






Day. 




July. 
1898. 


Aug. 


Sept. 


Oct 


Nov. 


Dec. 


Jan. 

1889. 


Feb. 


Mar. 


1 




• ■ • 

• • • 

• • • 


.37 

.84 
.00 


.00 
.25 
.75 


.00 
2.05 

.12 


.00 
.00 
.00 


1.83 
.00 
.00 


.84 
.65 
.74 


.00 
.22 
.00 


.00 


2 




.00 


8 




.00 


4 




• • • 

• • • 


.00 
.50 


.00 
.00 


.31 
.50 


.56 
.00 


.00 
.47 


.84 
1.74 


.00 
.00 


.00 


5 




.00 


6 




• • • 

• • • 

• • • 


.00 
.56 
.62 


.12 
.00 
.00 


.25 
.00 
.00 


.00 
.12 
.00 


.00 
.75 
.00 


.00 
.25 

.87 


.00 
.00 
.00 


.00 


7 




.00 


8 




.87 


9 




• • • 

.40 
.15 


.22 

.78 

.09 


.43 
.00 

1.18 


.37 
.00 

.00 


2.24 
.00 

.00 


.00 
2.52 

.00 


.48 
.25 

.74 


.49 
.00 

.00 


.25 


10. ... 




.00 


11 




.00 


13 




.12 
.53 
.12 


.25 
.81 
.09 


.00 

1.38 

.09 


.40 
.87 
.00 


1.24 
.87 
.00 


.00 
.00 
.00 


2.78 
.59 

.71 


1.86 
.00 
.00 


.00 


13. ... 




.00 


14 




.00 


15 




.09 

.06 
.00 
.59 
.37 


1.06 

.00 
.25 
.00 
.00 


.09 

1.27 
.06 
.09 

.28 


.00 

.00 

.00 

8.07 

1.24 


.25 

2.78 

1.55 

.06 

.00 


.00 

1.08 
.00 
.00 
.00 


.25 

.65 
.00 
.00 
.00 


.46 

.19 
.58 
.62 
.12 


.00 


16 




.22 


17 




.00 


18 




.00 


19 




.00 


20 




1.12 


.00 


.00 


.00 


.56 


.15 


.84 


.00 


.00 



APPENDIX III.— HYDROGRAPHIC REPORT 



273 



DAILY RAINFALL AT MACHUCA, ON SAN JUAN RIVER. —Continued. 



Day. 




July 
1896. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


Jan. 
1W9. 


Feb. 


Mar. 


21 




1.15 


.87 


.75 


.00 


.06 


.00 


.00, 


.00 


.00 


255 




.12 


00 


1.68 


.00 


.00 


.00 


.34 


.00 


.00 


23 


# 


.06 
.62 


.03 
.09 


1.33 
.00 


.06 
.81 


.00 
.81 


.00 
.00 


.00 
.00 


.00 
.12 


.00 


24 


.00 


26 




.47 

.09 
.00 


.40 

.25 

.00 


.00 

1.83 
1.83 


.00 

.00 
.00 


.43 

1.43 
.56 


.00 

.00 
.00 


.00 

.00 
.21 


.00 

.00 
.00 


.00 


26 


.00 


27 


.00 


28 




.12 


.00 


.00 


.03 


2.18 


• • 


.00 


.00 


.00 


29 




.28 
.06 


.09 
.00 


.00 
.00 


.00 
.25 


.50 
.00 


• • 
■ • 


.00 
.00 


• 
• • 


.00 


30 


.00 


81 




.00 


.34 


• « 


.00 


• • 


■ • 


• • 


• • 


.31 


Totals. . 




6.52 


8.51 


12.86 


9.83 


15.65 


6.75 


13.17 


4.61 


1.65 


DAILY RAINFALL ON SAN CARLOS RIVER, 1898. 


Day. 


Feb. 


Mar. 


Apr. 




May. 


June. 




July. 


Aug, 


1 






.04- 


.10 


. 


l.U 


1.17 




1.28 


.83 


2 






Trace 


.04 




.02 


.01 




1.76 


2.59 


8 






.00 


.02 




.16 


.00 




1.13 


.02 


4 






.70 


.76 




!.73 


.00 




.94 


.07 


5 






1.26 


3.63 




.45 


.00 




1.20 


54 


6 






.02 


1.80 




.06 


.08 




.01 


06 


7 






.14 


.oW 




.00 


.60 




.00 


.45 


8 






.06 


.06 




.05 


.15 




1.11 


.61 


9 






.89 


.00 




.42 


.00 




1.07 


.89 


10 






.10 


.30 




.68 


.69 




1.94 


.01 


11 






.00 


.48 




1.53 


.17 




.22 


.34 


12 






.10 


.34 




.03 


.01 




.04 


.51 


13 






.00 


.04 




.11 


2.06 




.00 


1.48 


14 






.00 


.02 




1.23 


.32 




.09 


.21 


16 






.00 


.00 




.87 


.23 




.00 


.20 


16 




)0 


.00 


.00 




.04 


.02 




.00 


.34 


17 




)2 


.04 


.00 




.05 


.00 




.00 


.45 


18 




L5 


.09 


.28 




1.18 


.60 




1.05 


.00 


19 




)0 


.00 


.39 




2.86 


1.37 




.19 


.00 


20 




12 


.24 


.00 




.56 


1.32 




1.41 


.50 


21 




)0 


.71 


.02 




1.99 


.57 




.73 


.69 


22 




S4 


.87 


.10 




.19 


1.95 




.00 


.00 


23 




)4 


.02 


.80 




.43 


2.82 




.17 


.94 


24 . 




{3 


.36 


.49 




.00 


.64 




.74 


.00 


25 




$7 


.90 


.07 




.00 


1.57 




1.09 


.00 


26 


1.) 


L4 


.48 


.33 




.06 


.61 




.36 


.82 


27 


l.( 


)2 


.87 


.10 




.18 


1.22 




.10 


.13 


2S 




)5 


.08 


.00 




.26 


1.42 




.02 


.00 


29 




■ • 


.00 


.00 




.24 


1.06 




1.59 


.00 


30 




> • 


.08 


.00 




.43 


.13 




.02 


.00 


31 




> • 


.00 


» • 




3.22 


• • 




.00 


.00 


Total . . . 


4J 


83 


7.52 


11.66 




20.12 


20.79 




18.26 


11.68 



18 



274 



NICARAGUA CANAL COMMISSION 



DAILY RAINFALL AT OCHOA, ON SAN JUAN RIVER. 



Day. 


Jhd. 
1898. 


Feb. 


Mar. 


Apr. 


Mtf>'. 


June. 


July. 


Augr. 


Sept. 


1 

Oct. 


Nov. 


Dec. 


Jim. 

1899. 


Feb. 


Mar. 


1 


.01 


.87 


,03 


.13 


1.35 


.SO 


1.07 


1.20 


.21 


1.17 


.00 


.79 


1.17 


.37 


.35 


2.... 


.05 


2.73 


.00 


.03 


.13 


.01 


3.81 




.20 


.44 


.00 


.05 


1.83 


.11 


.01 


3.... 


.28 


1.23 


.00 


.03 


.01 


.00 


.63 


.01 


.04 


.00 


.26 


.07 


.59 


.08 


.14 


4.... 


.06 


1.67 


.52 


1.91 


1.49 


.00 


1.73 


.03 


.11 


.53 


.63 


.32 


.84 


.01 


.05 


5. . . . 


.71 


.61 


1.75 


3.97 


.79 


.00 


.30 


.71 


.17 


.83 


.31 


.18 


1.31 


.18 


.00 


C. . . . 


.51 


.01 


.08 


1.80 


.13 


.15 


.01 


.04* 


.14 


.23 


.53 


.03 


.05 


.23 


.02 


7.... 


.73 


.00 


.17 


.35 


.01 


.43 


.01 


.29 


.14 


.00 


.26 


.15 


.67 


.00 


1.36 


8 


.34 


1.50 


.10 


.34 


.31 


.16 


1.03 


.54 


.13 


.01 


3.19 


.20 


.25 


.00 


2.51 


9 


1.37 


.17 


.8y 


.00 


.14 


.01 


1.11 


.89 


.12 


.09 


.13 


.63 


.17 


.11 


.06 


10.... 


1.04 


.18 


.03 


.39 


.63 


.01 


1.68 


.01 


.00 


.03 


.33 


1.83 


.33 


.17 


.00 


11.... 


.03 


.09 


.00 


.60 


1.19 


.13 


.09 


.23 


1.76 


.05 


.07 


1.00 


.54 


.08 


.05 


12.... 


.20 


.76 


.00 


.15 


.01 


.01 


.05 


.41 


1.26 


.03 


3.16 


.04 


1.38 


.99 


.03 


13.... 


.19 


.11 


.00 


.03 


.00 


3.06 


.11 


1.74 


1.61 


.19 


.78 


.31 


.34 


.49 


.35 


14 


.05 


.05 


.00 


.03 


.33 


.33 


.00 


.30 


.44 


.03 


.33 


.03 


.24 


.01 


.36 


15.... 


.51 


00 


.03 


.00 


.53 


.48 


.07 


.03 


.00 


.08 


1.38 


.01 


1.49 


.13 


.34 


16.... 


1.05 


.09 


.00 


.00 


.03 


.03 


.03 


.07 


.06 


.14 


5.10 


.33 


.80 


.58 


.09 


17.... 


1.18 


.07 


.09 


.07 


.13 


.01 


.17 


.35 


.01 


.09 


2.17 


.57 


.01 


.33 


.09 


18.... 


.42 


.00 


.00 


.47 


.36 


2.58 


.64 


.01 


.86 


.92 


.27 


.09 


.43 


.95 


.01 


19.... 


.02 


.15 


.00 


.43 


1.66 


1.39 


.19 


.01 


.14 


.11 


.02 


.01 


.16 


1.45 


.00 


20.... 


.47 


.44 


.35 


.00 


.37 


1.38 


1.84 


.03 


.00 


.00 


.07 


.08 


.22 


.37 


.00 


21.... 


2.13 


.01 


.15 


.00 


3.34 


.93 


1.21 


1.18 


1.34 


.88 


.14 


.01 


.54 


.33 


.02 


22.... 


.26 


.14 


.41 


.43 


.06 


.33 


.01 


.01 


2.25 


.15 


.01 


.00 


.44 


.09 


.00 


23.... 


.01 


.07 


.03 


1.15 


.42 


3.36 


1.00 


2.01 


.54 


1.55 


.03 


.03 


.04 


.16 


.00 


24.... 


.02 


.26 


.36 


.07 


.00 


1.12 


.59 


.29 


.00 


.09 


.34 


.00 


.34 


.06 


.00 


25.... 


.35 


.69 


1.35 


.00 


.00 


2.70 


1.62 


.05 


.23 


.39 


.49 


.00 


.03 


.05 


.00 


26.... 


.36 


.61 


.30 


.75 


.08 


.56 


2.43 


.28 


2.01 


.23 


1.11 


.73 


.04 


.06 


.00 


27.... 


.23 


.93 


1.21 


.11 


.76 


.57 


.02 


.06 


.10 


.08 


.83 


.11 


.01 


.33 


.01 


28 


.20 


.66 


.05 


.01 


.11 


.33 


.07 


.00 


.00 


.00 


.94 


.00 


.00 


.35 


.02 


29.... 


.29 


• • • • 


.08 


.03 


.12 


1.73 


1.04 


.04 


.03 


.00 


.72 


.24 


.03 


• • • • 


.00 


80.... 


.03 


• • • • 


.00 


.10 


.05 


.10 


.06 


.15 


1.23 


.15 


.02 


.40 


.00 


• • • • 


.01 


81 


.00 


• • • • 


.15 


• • • • 


1.96 


• • • • 


.00 


.29 


• • • • 


.04 


• • • • 


.17 


.05 


• • • • 


.33 




13.07 


14.08 


8.04 


13.33 


15.25 


31.47 


21.60 


12.08 


15.13 


8.02 


21.50 


8.38 


14.03 


7.90 


5.80 



DAILY RAINFALL AT STATION ON THE RIO SAN FRANCISCO, 1898. 



Day. 


Jan. 


Feb. 


Mar. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


1 


• • • • 


1.26 


.05 


.07 


1.94 


.58 


.83 


.97 


.16 


.15 


.00 


1.03 


2 


• • • • 


3.74 


.00 


.03 


.17 


.00 


3.84 


1.11 


.31 


.76 


.00 


.07 


8 


• • • • 


1.70 


.00 


.01 


.09 


.00 


1.06 


.01 


.30 


.09 


.00 


.10 


4 


• • • • 


1.66 


.57 


1.94 


1.22 


.00 


1.37 


.37 


.00 


.32 


.71 


.09 


5 


• • • • 


1.03 


1.54 


3.35 


.66 


.11 


.55 


.03 


.00 


.35 


07 


.34 


6 


.10 


.01 


.06 


.74 


.35 


.00 


.00 


.00 


.42 


.29 


.60 


.60 


7 


1.08 


.00 


.37 


.80 


.00 


.08 


.OtJ 


1.24 


.16 


.10 


.93 


.17 


8 


.28 


8.83 


.03 


.32 


.19 


.00 


.78 


.86 


.17 


.02 


4.07 


.38 


9 


2.10 


.18 


1.35 


.01 


.22 


.13 


.38 


1.02 


.18 


1.03 


.35 


.73 


10 


1.03 


.38 


.03 


.25 


.46 


.08 


1.41 


.01 


.01 


.18 


.30 


2.28 


11 


.05 


.17 


.00 


.89 


1.51 


.88 


.09 


1.48 


1.07 


.09 


.04 


1.30 


12 


.29 


.93 


.03 


.46 


.02 


.00 


.10 


.55 


2.19 


.40 


.82 


.00 


13 


.44 


.11 


.00 


.11 


.00 


2.59 


.00 


1.40 


.61 


.57 


1.64 


.84 


X^ • • • • • • • 


.18 


.03 


.00 


.15 


.00 


.29 


.19 


.27 


.88 


.06 


.66 


.02 


15 


.50 


.00 


.45 


.00 


1.26 


.45 


.08 


.09 


.17 


.05 


.78 


.16 



NICARAGUA CANAL CCMMJSSION 



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TEBBUARY 



COMPARATIVE DIAGRAMS OP RA 



APPENDIX III.— HYDROGRAPHIC REPORT 



275 



DAILY RAINFALL AT STATION ON THE RIO SAN FRANCISCO. 1898.— Continued. 



Day. 


Jan. 


Feb. 


Mar. 


April. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Xov. 


Dec. 


16 


1.11 


.16 


.25 


.00 


.03 


.01 


.08 


.00 


.00 


.07 


5.26 


.32 


17 


1.60 


.07 


.09 


.06 


.27 


.19 


.10 


.14 


.00 


.00 


1.55 


.42 


18 


1.04 


.00 


.02 


.74 


.31 


.19 


1.13 


.00 


.27 


.47 


.23 


.16 


19 


.01 


.16 


.01 


.67 


.71 


3.02 


.26 


.30 


.27 


.03 


.00 


.00 


20 


.81 


.28 


.18 


.01 


.37 


.17 


1.46 


.25 


T. 


.00 


.11 


.00 


21 


2.07 


.06 


.27 


.00 


1.45 


.17 


1.45 


.20 


1.74 


.88 


.07 


.00 


22 


.81 


.00 


.39 


.30 


.14 


1.02 


.00 


.01 


.30 


.22 


.05 


.31 


28 


.00 


.08 


.02 


.96 


.45 


.39 


.57 


1.33 


1.85 


1.58 


.09 


.10 


24 


.55 


.23 


.46 


.33 


.00 


3.01 


.82 


.17 


.04 


.25 


.27 


.00 


25 


.31 


.40 


.87 


.00 


.00 


2.04 


2.17 


.14 


.00 


.69 


.51 


.00 


26 


.70 


.86 


.24 


.26 


.19 


1.92 


.45 


.66 


.08 


.12 


.89 


.84 


27 


.08 


1.17 


1.25 


.24 


.09 


.78 


.04 


.79 


.06 


.18 


.90 


.26 


28 


.05 


.71 


.02 


.02 


.00 


.28 


.36 


.00 


.00 


.05 


1.88 


.00 


29 


.63 




.16 


.00 


.55 


.99 


.52 


.05 


.21 


.00 


.10 


• • • 


80 


.07 




.01 


.03 


.00 


.00 


.13 


.06 


.00 


.07 


.00 


• • • 


81 


T. 




.23 




1.33 




.00 


.04 




.02 




• • ■ 


Totals.. 


14.88 


18.43 


8.72 


11.35 


13.87 


18.87 


19.23 


13.45 


10.95 


9.09 


33.38 


9.80 



DAILY RAINFALL ON RIO SARAPIQUI, FIVE MILES ABOVE ITS MOUTH. 



Day. 


July 

18JW 


AuiJTiiSt. 


September. 


October. 


November. 


December. 


January. 
IWW. 


February. 


March. 


1 




.50 


.54 


.00 


.00 


.64 


.82 


.35 


.24 


2 




2.10 
.10 


.39 
.04 


.00 
.03 


.00 
.00 


.07 
.07 


1.17 
1.74 


.01 
.03 


.08 


8 


.31 


4 


. . . . 


.05 


.01 


.86 


.49 


.18 


1.17 


.00 


.03 


5 






.00 
.00 


.86 
.50 


.36 

1.07 


1.09 
.16 


.45 
.00 


.35 

.04 


.00 


6 


.01 


7 






.33 


.63 


1.18 


.06 


1.15 


.00 


1.07 


8 






.11 


.02 


2.51 


.31 


.26 


.00 


1.73 


9 






.00 


.12 


.00 


.54 


.54 


.00 


.18 


10 






.18 


.25 


.14 


1.65 


.30 


.54 


.04 


11 ■ 






.75 


1.05 


.09 


.44 


.95 


.30 


.00 


12 






.00 


.68 


.36 


.03 


- 1.66 


1.61 


.07 


13 






3.35 


.28 


.29 


.08 


1.05 


.72 


.53 


14 






.41 


.08 


.36 


.08 


.31 


.05 


.12 


15 






.30 
.01 


.04 
.15 


.76 
2.15 


.00 
.19 


1.83 
1.09 


.13 
.09 


.34 


16 


.13 


17 






.03 


.13 


3.75 


.41 


.07 


.22 


.07 


18 






1.45 


T. 


.95 


.06 


.56 


.76 


.16 


19 




.00 


.04 


.35 


.01 


.00 


.06 


.66 


.01 


20 




1.02 


.00 


.00 


.00 


.01 


.40 


.38 


.00 


21 




.01 


3.44 


.00 


.07 


.00 


.11 


.11 


.01 


22 




.00 
.19 


.00 
1.16 


1.79 
2.15 


.00 
.01 


.16 
.23 


.07 
.10 


.03 
.46 


.00 


23 


.00 


24 




.04 


.01 


.26 


1.35 


.00 


.59 


.36 


.18 


25 




.00 


.00 


.84 


.16 


.00 


.05 


.00 


.00 



276 



NICARAGUA CANAL COMMISSION 



DAILY RAINFALL ON RIO SARAPIQUI, FIVE MILES ABOVE ITS MOUTH.— Continued. 



Day. 


July. 


Auifust. 


Soptembcr. 


October. 


N<»veml)cr. 


l>eoeml)er. 


January. 

IHW. 


February. 


March. 


26 


.15 


.00 


.00 


.17 


.39 


.23 


.03 


.19 


.00 


27 


.12 


.00 


.05 


.03 


1.05 


.07 


.04 


.05 


.00 


28 


.05 


.17 


.00 


.00 


.78 


.00 


.00 


.08 


.00 


29 


.10 


.08 
.00 


.80 
.00 


.00 
.03 


.33 
.02 


.12 
.21 


.00 
.00 


.... 
.... 


.00 


80 


.93 


.01 


31 


.90 


.10 


• • • • 


.0(5 


• • • • 


.OS 


.01 


.... 


.35 






4.30 


11.19 


11.35 


18.03 


7.10 


10.57 


1. < 1 


5.07 



Day 



DAILY RAINFALL OF RIO DESEADO AT CAMP BARTON FOR 1898. 



Jan. 



Feb. 



Mar. April. 



May. 



June. 



July. 



Augr. Sept. 



Oct. 



Nov. 



Dec. 



1. 

o 

<M < 

3. 
4. 
5. 

6. 

7. 

8. 

9. 

10, 

11. 
12. 
18. 
14. 
15. 

16. 

17. 
18. 
19. 
20. 

21. 
22. 
23. 
24. 
25. 

26. 

37 

28. 

39. 

80. 

81. 



.14 
.15 
.92 
.38 
1.23 

.46 
1.91 

.45 
3.66 
1.24 

.98 
.20 
.84 
.00 
1.21 

1.91 

1.08 

.76 

.09 

.59 

1.69 
.50 
.03 
.57 
.53 

.78 
.36 
.18 
.80 
.25 
.08 



.86 
4.61 
1.70 
4.37 
1.31 

.00 
.00 
1.82 
.21 
.95 

.49 
1.13 
.32 
.08 
.00 

.18 
.40 
.00 
.28 
.81 

.10 
.88 
.68 
.26 
1-88 

1.08 
8.04 
1.29 



.03 
.08 
.00 
.26 
1.49 

oo 

. WW 

.09 

.68 

2.60 

.02 

.04 
.08 
.00 
.06 
.00 

.04 
.17 
.00 
.02 
.84 

.12 

.81 

.29 

1.05 

1.75 

.37 
.98 
.03 
.87 
.35 
.28 



.19 

.00 

.07 

1.80 

2.33 

.89 
.22 
.19 
.14 
.29 

.51 
.10 
.01 
.07 
.00 

.00 
.02 
.01 
.13 
.00 

.00 
.77 
1.06 
.18 
.00 

.73 
.17 
.00 
.01 
.00 



1.78 

.29 

.01 

1.29 

1.05 

.82 
.02 
.04 
.08 
.57 

.91 
.06 
.07 
.01 
.00 

.75 
.47 
.09 
1.44 
.07 

1.22 
.11 
.45 
.00 
.00 

.00 
.05 
.00 

1.01 
.08 

2.60 



.76 
.00 
.00 
.00 
.38 

.03 
.63 
.00 
.69 
.00 

.99 

.08 

2.48 

1.22 

.50 

.25 
.01 
.00 
.99 

.87 

.34 

.01 

2.06 

2.10 

.92 

.09 
.38 
.88 
3.04 
.13 



3.70 
2.48 
1.08 



.00 
1.06 
1.44 

.80 

.15 
.02 
.02 
.07 
.00 

.24 

.67 

.76 

1.55 

3.83 

3.69 
.08 
.81 
.18 
.77 

.37 
.90 
80 
.83 
2.02 
.00 



2.06 

1.8S 

.11 

.51 

.21 

.00 
1.77 

.94 
1.84 

.87 

.03 
1.37 
.28 
.29 
.00 

.00 
.00 
.00 
.04 
.08 

.28 
.12 
.00 
.00 
.37 

.52 
.01 
.00 
.19 
.00 
.09 



.74 
.10 
..58 
.20 
.07 

.15 
.20 
.68 
.00 
.84 

.54 
.21 
.81 
.07 
.00 

.00 
.00 
.10 
.24 
.00 

.09 
.00 
.03 
.00 
.02 

.00 
.00 
.00 
.00 
.00 



.00 
.42 
.51 
.58 
.09 

.68 

.00 

.04 

2.30 

1.07 

.97 
.03 
.28 
.30 
.44 

.18 
.00 
.00 
.80 
.00 

.03 
.03 

1.87 
..56 

1.30 

.08 
.00 
.30 
.00 
.10 
.00 



.70 
.00 
.00 
.25 



-{ 2.96 



1.11 

1.02 
.30 

2.70 
.58 

1.88 

5.80 

8.61 

.74 

.01 

.85 

.22 
.09 
.08 
.85 
.68 

2.80 

1.87 

1.44 

.30 

.00 



2.75 
.49 
.07 
.11 
.11 

.67 

.69 

.40 

1.66 

1.65 

1.88 
.02 
.21 
.00 
.28 

.91 
.45 
.02 
.00 
.00 

.10 
.44 
.01 
.00 

1S97 

1.13 

2.27 
1.35 
1.66 
1.60 
.69 



Totals 



21.92 



26.98 



11.70 



8.83 



14.84 



18.00 



26.27 



13.31 



5.23 



11.92 






21.0'; 



NICARAGUA CANAL C0MMIB8I0N 































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EBRUARY MARCH APRIL MAY JUNE 

DIAGRAM OF THE DAILY RAINFALL AT LAS 



8EPTEMBE 



APPENDIX 3, PLATE XIV 
NOVEMBER DCCCUBCH 




JULY AUGUST SEPTEMBER OCTOBER 

FT. SAN CARLOS AND RIO SAN FRANCISCO, 1898. 



APPENDIX III.— HYDROGRAPHIC REPORT 



277 



DAILY RAINFALL AT GREYTOWN, NICARAGUA. 



Day. 


Jan. 

18M8. 


Feb. 


Mar. 


Apr. 


• 

May, 


June. 


July. 


Aug, 


Sept. 


Oct. 


Xov. 
.27 


Dec. 


Jan. 
JnBli. 


Fob. 


Mar. 


Apr. 


1 


.42 


.61 


.13 


.00 


1.90 


2.17 


.00 


2.28 


.00 


.00 


2.91 


1.44 


.08 


.52 


.27 


2.... 


.12 


2.16 


.05 


03 


.04 


.92 


1.43 


2.19 


1.26 


.00 


.00 


.48 


.80 


1.00 


.00 


.03 


o . • • . 


1.11 


1.51 


.00 


.12 


.00 


.00 


1.51 


.85 


4.00 


.44 


.00 


.08 


.92 


• • ■ • 


.08 


.28 


4 ... 


1.32 


3.41 


.32 


.86 


1.00 


.45 


.42 


.88 


.00 


.16 


.52 


].83;. 


.27 


.47 


.00 


.40 


6.... 


2.72 


2.80 


1.04 


2.79 


.85 


.11 


.00 


.85 


.00 


.03 


.10 


.50 


.25 


.00 


• .30 


6. . . . 


.89 


.00 


.22 


.10 


.04 


.21 


12 


.00 


.00 


.77 


3.14 


.41 


.59 


.02 


.00 


.12 


7.... 


.45 


.00 


.27 


.33 


.00 


.62 


2.05 


3.00 


.55 


.00 


3.43 


1.14 


1.01 


.45 


1.00 


.00 


o. . . . 


.67 


1.25 


.27 


.08 


.00 


.00 


2.77 


.42 


.85 


.02 


1.80 


.29 


.67 


.00 


.45 


2.85 


V . . . . 


2.07 


.40 


1.84 


.00 


.02 


.29 


.60 


8.09 


.00 


.00 


.02 


1.50 


1.17 


.00 


.00 


1.57 


10.... 


1.05 


.34 


.00 


.25 


.23 


.27 


.83 


.00 


.00 


1.68 


1.20 


1.68 


1.91 


.02 


.08 


1.36 


11 


.54 


.00 


.35 


.67 


1.20 


1.14 


.15 


.28 


.00 


.39 


1.89 


1.75 


2.08 


.80 


.01 


.48 


13. . . . 


.43 


1.16 


.00 


.17 


.06 


.«8 


.00 


1.71 


.00 


.72 


.25 


.10 


2.46 


2.45 


.06 


1.86 


18.... 


.14 


.29 


.00 


.00 


.08 


3.20 


.00 


.32 


.00 


.26 


2.35 


.34 


.49 


.10 


1.02 


.37 


14.... 


.03 


.81 


.00 


.12 


.04 


1.40 


.14 


.00 


.15 


2.46 


.76 


.15 


.46 


.04 


.55 


.00 


15. . . . 


.60 


.00 


.00 


.00 


.07 


1.18 


.00 


.00 


• .00 


1.09 


.75 


.35 


2.50 


1.51 


.30 


.08 


16 


1.26 


.80 


.00 




1.22 


.00 


.00 


.25 


.00 


.07 


4.85 


.99 


1.32 


.45 


.05 


.00 


17.... 


.81 


.26 


.18 


OB 


.08 


.10 


.67 


.06 


.00 


.01 


8.07 


.80 


.01 


1.06 


2.19 


.00 


18.... 


1.19 


.00 


.00 


to 


.50 


.00 


.14 


.00 


.00 


.00 


.52 


.06 


2.21 


1.23 


.03 


.00 


1» 


.06 


.19 


.00 




.08 


.52 


2.42 


.00 


.42 


.02 


.04 


.00 


.19 


.87 


.00 


.05 


20... 


.29 


.27 


.00 


.08 


.00 


5.18 


.69 


.00 


.00 


.84 


.18 


.29 


.45 


.00 


.00 


21 


.06 


.07 


.40 




.00 


1.46 


.79 


.28 


.00 


.00 


.37 


.11 


.49 


.13 


.00 


.02 


22. . . . 


.18 


.24 


.38 




.78 


.00 


.26 


.00 


.00 


.10 


.31 


.22 


.19 


.00 


.00 


.00 


23.... 


.00 


.03 


.54 


.15 


.19 


.20 


.00 


.00 


.01 


1.14 


.29 


.12 


.12 


.00 


.04 


.00 


24 


.86 


.18 


2.40 


.04 


.00 


2.75 


.70 


.00 


.00 


1.12 


.91 


.02 


.56 


.38 


.25 


.00 


25. . . . 


.30 


2.50 


.78 


.08 


.00 


1.24 


.49 


.20 


.00 


1.96 


.48 


.00 


.00 


.01 


.02 


.00 


26.... 


1.52 


.82 


.32 


.83 


.00 


.09 


.60 


.20 


.00 


.05 


2.41 


.02 


.11 


.00 


.09 


.05 


27 


.36 


4.12 


.22 


.28 


.00 


.06 


.92 


.00 


.00 


.01 


• • • • 


( ) 


.00 


.23 


.08 


.00 


28.... 


.13 


1.95 


.04 


.00 


.00 


.20 


.95 


.00 


.00 


.00 


2.00 


H 


.00 


.19 


.25 


.00 


29. . . . 


.53 


• • • • 


.30 


.00 


.70 


.52 


.17 


.25 


.00 


.00 


.17 


.05 


• • • • 


.00 


.00 


30 


.30 


• • ■ • 


.04 


.00 


.12 


.00 


1.32 


.00 


.00 


.00 


.11 


1.16 


.02 


• • • • 


.00 


.00 


31.... 


.03 
19.44 


• • • • 


.07 


• * • • 


.00 


• • • • 


.00 


.13 


• • • • 


.00 


• • • • 


.42 


.06 


« • • • 


1.36 


• • • • 


Totals 


25.17 


10.16 


6.90 


9.37 


19.52 


24.63 


16.38 


7.24 


12.50 


32.85 


17.06 


28.49 


11.69 


8.83 


9.09 



MONTHLY RAINFALL OF NICARAGUA, 1898. 



Station. 



Jan. 



Feb. 



Mar. 



Apr. May. June. July. Aug. Sept. Oct. 



Nov. 



Dec. 



Total. 



Brito and Tola 


.25 


.00 


.08 


.08 


11.30 


14.86 


11.43 


6.17 


16.60 


25.70 


6.01 


2.41 


94.88 


Rivas 


1.07 


.12 


.10 


.00 


16.17 


18.95 


13.65 


11.85 


18.99 


20.83 


8.19 


8.14 


108.06 


Las Lajas . . . 


.25 


.05 


1.34 


.28 


10.60 


18.50 


10.64 


8.44 


6.79 


16.19 


4.41 


2.26 


74.75 


Rio Viejo 


• • • 


.01 


.66 


•00 


13.78 


13.45 


4.01 


11.66 


7.28 


8.99 


.61 


.17 


60.62 


Tlpitapa 


k • • • 


.00 


.26 


.00 


8.56 


16.88 


6.24 


7.82 


11.25 


7.12 


.93 


.17 


59.23 


Morrito 


• • • 


• • • • 


• • • • 


.07 


8.92 


14.05 


13.84 


10.20 


• . . • 


• • • • 


• • • • 


• • • • 


• • • • 


Ft. San Carlos. 


» • • • 


• • • • 


1.21 


3.00 


8.22 


15.56 


18.35 


8.00 


10.56 


8.93 


9.86 


5.62 


84.31 


Sabalos 


• • ■ 


• • • • 


2.10 


6.00 


11.69 


17.13 


20.69 


11.33 


11.42 


11.81 


12.17 


10.20 


114.54 


Castillo 


• • • 


• • • • 


■ • • • 


• • • • 


• • • • 


• • • • 


18.93 


11.46 


16.22 


4.64 


14.04 


11.64 


• • • • 


Machnca 


• • • 


• • • • 


• • • • 


• • • • 


• • • • 


• • • • 


.... 


6.52 


12.86 


9.88 


15.65 


6.75 


• • • • 


Rio San Carlos . 


1 • • • 


• • • • 


7.52 


11.66 


20.12 


20.79 


18.26 


11.68 


.... 


• • • • 


.... 


• • • • 


• • • • 


Ochoa 1 


3.07 


14.08 


8.04 


12.23 


15.25 


21.47 


21.60 


12.08 


15.12 


8.02 


21.50 


8.88 


170.84 


San Francisco* 1 


5.33 


18.43 


8.72 


11.25 


13.87 


18.87 


19.23 


13.45 


10.95 


9.09 


22.28 


10.61 


172.17 


Sarapiqnl 


» • • • 


• • • • 


• • • • 


• • • • 


• • • • 


• • • • 


.... 


• • • • 


11.19 


11.85 


18.63 


7.12 


• • • • 


Deseadot 2 


1.92 


26.98 


11.76 


8.83 


14.84 


18.66 


26.86 


13.31 


5.23 


11.92 


29.25 


21.07 


210.63 


Grey town 1 


9.44 


25. 1 7 


10.16 


7.82 


9.37 


19.52 


24.63 


16.38 


7.24 


12.50 


32.35 


17.06 


201.64 



* Record incomplete from Jan. 1-5 incl., and from Dec. 29-31 incl.; so the rainfall at Ochoa for those days is added, 
t Rainfall not observed from Dec. 25 to 31, 1898; so the record was completed by including the corresponding days 
of 1897. 



NICARAGUA CANAL COMMISSION 



MisoEu^iTEOus Eainfall Becokdb. 

Other records of rainfall have been fumiahed 
to this Commission through the courtesy of 
Hon. Willis L. Moore, Chief of the Weather 
Burean, as follows: 

A record of 19 years at Eivas, beginning Jan- 
uary, 1880, kept by Dr. Earl Flint, an American 
resident. 

A record at Masaya from July, 18S6, to De- 
cember, 1896, kept by ilr. Wra, Climie, an 
English Civil Engineer. In January, 1897, 
these observatiouB were transferred to Granada 



ragua Canal Company. These records are given 
below . 

The greatest fluctuation of Lake Nicaragua, 
which cannot be prevented, and which, there- 
fore, must be provided for, ia occaaicsied by the 
excess of evaporation, leakage and use over the 
inflow for limited periods, hence this important 
factor depends upon the period of least rainfall 
in the lake basin. On tho east side of the isth- 
mus the problems consist chiefly of the control 
and discharge of excessive floods, and of their 
effect upon the permanence and stability of the 



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Fio. 7. Comparative Monthly Rainfall at Oreytown, Oclioa, Ft. 3an Carlos and Tola. 



and have been continued ever since, although 
results are at hand only to the end of 1897. 

Records of rainfall in Granada in 1876 by 
Ramon Espinola, in 1877 by Dr. Flint, and in 
1883-84 by the National Institute at Granada. 

A record at Blueflelds by Hon, W. H. Jack- 
son and others, from September, 1883, through- 
out 1884 and 1885, and a portion of 1886. 

A record at Oreytown for the years 1890, 
1891, 1892, and a portion of 1893 by the Nica- 



works. For this reason we are most concerned 
with the year of maximum rainfall in this 
region. It is a somewhat remarkable fact that 
the year 1890 is the absolute minimum of the 
Rivas record, and the ma.ximuni in the Greytown 
record, and may, therefore, be taken as a typical 
illustration of the problems with which we have 
to deal. For this reason Map 1, Sheet 3,' has 



NICARAGUA CANAL COMMISSION 




MONTHLY RAINI 



APPENDIX 3, PLATE XV 




RtVAS. 1880-1898. 



APPENDIX III.— HYDROGRAPHIC REPORT 



279 



been prepared, representing as nearly as may 
be with present information the probable distri- 
bution and quantity of rainfall in the year 1890 
in southern Xicaragua and northern Costa Kiea 
in seven zones. The first, which includes the 
greater part of Lake Nicaragua and its drain- 
age basin, has rainfall of less than 30 inches, 
probably in some parts running below 20 inches. 
The second zone represents a rainfall between 
30 and 60 inches. The next has a precipitation 
ranging between 60 and 100 inches. The zone 
next further east represents a precipitation rang- 
ing between 100 and 150 inches. The next in- 
cludes that portion in which the precipitation is 
between 150 and 200 inches, the next that por- 
tion between 200 and 250 inches, while the small 
triangular area about the mouth of the San Juan 
has a rainfall exceeding 250 inches. 

The data upon which this map is made ^u^ 
the record of 19 years at Kivas, 4 years at Grey- 
town, the record for 1898 at other stations main- 
tained by the Nicaragua Canal Commission, and 
a few other records obtained through the cour- 
tesy of Prof. H. Pittier, San Jose, Costa Kica, 
and from the U. S. Weather Bureau. The 
record of Greytown includes the yecirs 1890, 
1891, 1892 and 1898, the latter being the 
record of the Nicaragua Canal Commission, ag- 
gregated 201.64. The year 1890 had a precipi- 
tation of 296.94, which exceeds that for 1898 



by 47 per cent It is assumed that this propor- 
tion between the rainfall of 1898 and 1890 exists 
for all of the country east of Lake Nicaragua, 
and 47 per cent, was therefore added to the 
obserrations at each of the stations maintained 
by the Commission to obtain the maximum for 
use in compiling this map. On the west side of 
Lake Nicaragua and at Morrito, which is affected 
by similar climatic conditions, the long record 
at Eivas was taken as the standard, and the 
rainfall for 1890 was obtained by taking 30 
per cent, of the record for 1898, this being the 
percentage indicated by the Rivas record. 
There is some indication that the co-existence 
of extreme conditions on one side, with the op- 
posite extreme on the other side is the rule. The 
year 1898 is the year of minimum precipitation 
at Greytown, so far as our record of complete 
years goes, while the record at Kivas gives for 
that year very nearly a maximum, being second 
only to the year 1897. Also the short record 
of five months for 1893 at Greytown gave a 
total for five months of 41.92, being much less 
than for the same period in any other recorded 
year at Greytown, indicating that 1893 was a 
year of low precipitation at this point, while it 
was one of the highest in the Kivas record. Of 
course these zones must be considered as only 
rough approximations. 



MONTHLY RAINFALL AT RIVAS. NICARAGUA. 

Dr. Earl Flint, Observer. 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 
0.00 


May. 
10.23 


June. 


July. 


Aug. 


Sept. • 


Oct. 


Nov. 


Dec. 
0.67 


Annual. 


1880 


0.00 


0.00 


0.00 


12.58 


3.62 


10.48 


7.95 


18.83 


5.02 


64.38 


1881 


0.00 


0.00 


0.00 


0.12 


5.20 


13.17 


8.88 


6.96 


7.42 


24.67 


10.88 


1.91 


79.21 


1883 


0.00 


0.13 


0.00 


0.00 


4.2« 


9.80 


4.04 


6.25 


7.65 


23.38 


4.20 


1.61 


61.32 


1888 


0.28 . 


0.00 


0.00 


0.14 


1.00 


8.07 


4.87 


4.34 


5.78 


18.25 


5.70 


1.34 


49.77 


1884 


0.59 


0.09 


0.00 


2.03 


2.80 


10.43 


4.98 


8.84 

• 


4.48 


15.83 


7.43 


2.24 


54.74 


1885 


0.04 


0.00 


0.00 


0.00 


1.78 


7.27 


4.81 


2.76 


5.40 


7.88 


4.36 


0.29 


34.59 


1886 


0.23 


0.20 


0.00 


0.17 


13.00 


7.87 


15.00 


20.80 


15.30 


10.40 


3.75 


0.49 


87.21 


1887 


0.90 


0.81 


0.00 


0.00 


9.17 


8.18 


4.10 


5.03 


19.42 


22.47 


2.50 


2.31 


74.89 


1888 


1.83 


0.04 


0.00 


0.00 


7.12 


8.50 


4.18 


5.00 


9.80 


16.80 


1.11 


1.13 


55.51 


1889 


0.00 


0.19 


0.07 


1.71 


11.34 


11.64 


7.48 


. 12.95 


9.80 


24.18 


3.38 


1.67 


84.36 



280 



NICARAGUA CANAL COMMISSION 



MONTHLY RAINFALL AT RIVAS. NICARAGUA.— Continued. 



Year. 


Jan. 


Feb. 


Mar. 


April. 


May. 


June. 
4.56 


July. 
4.73 


Aug, 
3.78 


Sept. 
2.77 


Oct. 


Nov. 


Deo. 


Annual. 


1890 


0.49 


0.11 


0.94 


0.00 


2.63 


9.68 


1.30 


0.82 


81.81 


1891 


0.00 


0.00 


0.00 


0.78 


0.75 


24.58 


4.38 


4.21 


12.42 


14.90 


2.34 


1.67 


66.08 


1892 


0.19 


0.00 


0.00 


0.00 


13.30 


9.80 


9.19 


7.48 


12.22 


21.26 


4.40 


0.43 


78.27 


1893 


0.06 


0.39 


0.00 


0.11 


20.03 


1>1.14 


13.22 


18.70 


14.00 


13.56 


2.44 


2.48 


106.13 


1894 


2.12 


0.24 


0.08 


0.00 


7.76 


6.32 


8.64 


4.57 


4.33 


14.62 


3.21 


0.43 


47.32 


1895 


0.00 


0.08 


0.19 


0.39 


8.11 


11.02 


5.25 


3.42 


8.01 


8.97 


2.04 


0.20 


47.68 


1896 


0.40 


0.08 


0.00 


T. 


3.26 


0.23 


7.43 


6.57 


7.40 


7.42 


8.62 


0.39 


47.80 


1897 


0.33 


T. 


1.04 


0.00 


21.30 


24.34 


0.41 


12.10 


17.63 


33.85 


5.15 


1.28 


123.43 


1898 


1.07 


0.12 


0.10 


0.00 


10.17 


18.95 


13.05 


11.85 


13.99 


20.83 


8.19 


3.14 


108.06 


Means 


0.45 


0.13 


0.13 


0.29 


8.38 


11.81 


0.83 


7.95 


9.78 


16.99 


4.52 


1.29 


68.55 



MONTHLY RAINFALL AT MASAYA, 1886-96, AND GRANADA. 1897. 

Nicaragua Observers. 





Jan. 


Feb. 


Mar. 


Apr. 


May. 


Juno. 


July. 


Aug:. 


Sept. 


Oct. 


Nov. 


Dec. 


AnnuaL 


1886. . 


» • • • • • 


• • • • 


• • • « 


« 


• • • • 


• • • • 


8.23 


15.26 


15.34 


11.19 


0.69 


0.02 


72.70 


1887. . 


.. 0.30 


0.00 


0.00 


0.00 


2.42 


10.73 


7.39 


5.74 


9.15 


23.56 


0.94 


0.99 


61.22 


1888.. 


. . 0.05 


0.14 


0.00 


0.00 


7.09 


12.09 


4.95 


9.50 


17.21 


7.67 


0.00 


0.00 


58.70 


1889. . 


. . 0.00 


0.00 


2.39 


1.18 


6.43 


17.00 


7.87 


13.43 


14.53 


13.36 


2.34 


0.25 


78.78 


1890.. 


.. 0.14 


0.00 


0.00 


0.60 


1.82 


3.00 


2.86 


2.66 


2.95 


5.89 


0.42 


0.18 


20.52 


1891... 


.. 0.19 


0.00 


0.00 


1.02 


0.48 


20.94 


4.52 


4.20 


10.40 


5.45 


2.78 


0.00 


49.98 


1892... 


. 0.00 


0.00 


0.00 


0.00 


7.30 


14.42 


8.70 


6.75 


9.64 


15 . 71 


1.66 


0.30 


64.54 


1893. . . 


. 0.00 


1.15 


0.00 


0.00 


9.26 


11.78 


11 .47 


15.82 


12.07 


6.51 


2.70 


1.50 


72.86 


1894.., 


.. 0.32 


0.50 


0.00 


0.00 


7.87 


4.77 


3.32 


4.00 


7.49 


13.42 


1.08 


0.11 


42.88 


1885.. 


.. 0.00 


0.00 


0.00 


0.41 


4.57 


4.71 


5.22 


2.90 


8.30 


14.46 


0.57 


0.06 


41.26 


1896. . . 


.. 0.23 


0.00 


0.00 


0.09 


5.62 


7.90 


7.13 


2.98 


0.62 


4.22 


4.85 


0.00 


39.64 


1897. . . 


. 0.00 


0.00 


0.97 


1.77 


16.63 


30.79 


8.88 


10.87 


10.21 


11.97 


1.25 


0.28 


93.62 


Means 


.. 0.11 


0.16 


0.31 


0.46 


6.32 


12.56 


6.71 


7.84 


10.38 


11.12 


1.61 


0.31 


58.06 



* Estimated rainfall January to June, 1880, inclusive, is 21.97 inches. 



MONTHLY RAINFALL. 



Year. 


Jan. 


Feb. 


Mar. 


Apr. May. 


June. July. 


Aug. 


Sept. Oct. 


Nov. 


Dec. 


Annual- 












Managua. 












Lat. 12° 7^ N. 


Lonj?. 80O 16^ W. 


Elevation 148 feet. 








1891.... 


.00 


.00 


.00 


.00 1.08 


14.00 5 04 


3.04 


8.43 9.64 


7.24 


0.43 


48.90 


1892 


.00 


.00 


.00 


.00 8. .58 


11.34 6.35 
San Antonio. 


7.9S 


9.24 20.55 


3.09 


• • • • 


67.13 










Lat. 12° 32^ N. 


Long. 860 59^ W. 


Elevation 00 feet. 








1895.... 


.00 


.00 


.00 


.... ( . \ff^ 


6.29 3.36 


5.07 


21.68 21.71 


3.42 


0.32 


69.83 


1896 


.00 


.00 


.00 


0.20 12.20 


10.50 7.54 


4.71 


13.39 11.22 


4.76 


0.98 


65.50 


1897.... 


.00 


.00 


1.26 


0.59 18.23 


14.53 6.81 
Valle Meniek 


13.80 


10.94 31.06 


.98 


.00 


98.26 










Lat. 11° 40/ N. 


long. 850 57^^ W. 


Elevation 492 feet. 








1880 


.00 


.00 


.00 


.00 13.48 


9.92 2.24 


9.96 


6.77 13.46 


2.72 


.00 


58.55 


1881.... 


0.55 
.00 


.00 
.00 


.00 
.00 


.00 9.94 
.00 1.93 


12.88 7.52 


8.86 
6.30 


9.10 22.68 
4.92 19.13 


9.83 
2.76 


0.98 
.00 


81.84 


1882 


12.87 


47.91 


1883 


.00 


.00 


.00 


.00 1.35 


7.44 3.94 


• • • « 


• ••• •••• 


• • • • 


• • • • 


• • • • 



NICARAGUA CANAL COMMISSION 

JANUARY PEBRUAHY 



































































D 


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APPENDIX 3, PLATE XVI 
3U8T SEPTCMBCn OCTOBER NOVEMBER DECEMBEW 










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JULV AUGUST SEPTEMBEB OCTOBER NOVEMBER OECEMBEn 

AS, 1890, 1897, 1898. 



APPENDIX III.— HYDROGRAPHIC REPORT 



281 



MONTHLY RAINFALL AT GRANADA. 



Year. 



Jan. Feb. 



Mar. 



Apr. 



May. June. 



Total 
July. Auk. Sept. Oct. Nov. Dec. Annual. 



1870 


• • 


• • 


• • 


• • 


5.77 


13.65 


26.61 


4.96 


• • 


• • 


• • 


• • 


• • 


1877. . . . 


0.00 


0.00 


0.00 


0.00 


11.57 


10.24 


10.12 


5.33 


17.36 


5.27 


0.87 


0.59 


61.34 


1883 


0.35 


0.00 


0.00 


0.i8 


0.28 


5.20 


2.66 


5.47 


9.74 


19.91 


3.64 


0.00 


47.43 


1884 


0.00 


0.00 


0.00 


0.00 


0.00 


8.25 


3.99 


3.75 


8.82 


8.63 


2.28 


0.26 


35.98 




1876. 




Observer. 


Ramon Espi 


nola. 




1877.... 


. .Observer 


.Earl Flint. 





Location, N. ll® 56', W. 85° 54'; elevation, 218 ft. 
1883-1884 Observed by National Institute; elevation, 230 ft. 







• 


RAINFALL AT GREYTOWN, NICARAGUA. 






« 






Jan. 


Fgb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


TotaL 


1890 


26.80 


6.36 


5.93 


18.11 


4.93 


46.84 


52.55 


35.72 


8.14 


34.36 


25.55 


41.65 


296.94 


1891 


20.30 


2.57 


1.95 


10.40 


13.78 


26.95 


23.57 


19.49 


14.16 


20.21 


28.15 


32.74 


214.27 


1892 


28.57 


11.38 


4.98 


18.38 


50.88 


13.42 


38.96 


23.63 


11.47 


27.95 


36.93 


24.65 


291.20 


1893 


17.70 


7.53 


3.93 


9.99 


2.77 


* • • • 


. . • « 


• • • • 


• • • • 


• • ■ • 


• • • • 


. . * • 


■ • • • 


1898 


19.44 


25.17 


10.16 


7.82» 


9.37 


19.52 


24.63 


16.38 


7.24 


12.50 


32.35 


17.06 


201.64 








RAINFALL AT BLUEFIELDS, NICARAGUA. 












Jan. 


Feb. 


Mar. 


April. 


May. 


June. 


July. 


Augr. 


Sept. 


Oct. 


Nov. 


Doc. 


Total. 


1883 


• • • 


• • 


• • 


• . 


• • 


• • 


• • 


• • 


3.42 


8.13 


12.13 


17.00 


• • 


1884 


10.25 


6.39 


3.21 


2.06 


2.67 


8.01 


17.06 


16.40 


5.82 


4.99 


9.71 


11.15 


97.72 


1885 


1.96 


1.60 


2.66 


2.87 


5.89 


13.37 


19.82 


11.75 


8.07 


2.69 


7.70 


3.15 


81.53 


1886 


7.28 


3.94 


1.63 


• • 


• • 


• • 


• • 


8.55 


* 

• • 


• • 


• • 


• • 


• • 



Day 

1 

2.... 
3.... 

4 

5.... 

6 

7 

8.... 

9 

10.... 

11 

12 

13 

14 

15 



DAILY RAINFALL FOR SAN JUAN RIVER AT SAN FRANCISCO ISLAND FOR 1888. 

By Maritime Canal Co. 



Jan 



Feb 



Mar 



Apr. 



May 



June. 



July. 


Aug. 


Sept. 


Oct. 
1.20 


Nov. 


Dec. 


2.61 


3.27 


.00 


.14 


.20 


.87 


.05 


.00 


.05 


.00 


2.15 


.17 


.53 


.00 


.10 


.00 


2.93 


.77 


1.87 


.00 


.00 


.00 


8.97 


2.77 


.43 


.34 


.17 


.35 


8.50 


.09 


.87 


.00 


.38 


.13 


.14 


.07 


1.11 


2.47 


.00 


.11 


.07 


.11 


.42 


.57 


.00 


.08 


.23 


.73 


.90 


2.30 


.00 


.03 


.05 


.68 


.00 


.00 


1.05 


.73 


.17 


1.63 


.52 


2.70 


1.27 


2.24 


.00 


.92 


.00 


2.20 


.92 


.53 


.05 


1.93 


.55 


.40 


.23 


.62 


.00 


2.42 


.13 


.00 


.07 


.73 


.00 


2.70 


.00 


.34 


1.25 


.51 


.05 



282 



NICARAGUA CANAL COMMISSION 



DAILY RAINFALL OF SAN JUAN RIVER AT SAN FRANCISCO ISLAND FOR 1888.— Continued. 



Day. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


16 




• • • 


» • • • • 






• • • • 


.«7 


.17 


1.43 


.37 


.87 


.63 


17 




• • • 


1 • • • 1 






• • • • 


.61 


1.09 


.57 


1.85 


1.94 


.00 


18 




• • • 


1 • • • • 






.23 


.17 


.13 


.27 


.63 


.37 


.05 


19 




• • • < 


• • • • 






.37 


8.07 


.73 


.31 


.69 


.28 


.77 


20 




• m • * 


• • • • 






.11 


1.97 


.64 


.67 


.99 


.50 


.69 


21 




• • • 1 


• • • • 






.07 


.23 


.00 


1.27 


.26 


.10 


.00 


22 




• • • 1 


• • • • 






.03 


.17 


.09 


.59 


1.60 


.00 


.00 


23 




• • • 4 


1 • • • • 






.00 


.32 


.07 


.00 


.14 


.14 


.00 


24 




* « • ■ 


• • • • 






.49 


1.07 


.00 


2.55 


.06 


.12 


.00 


25 




• • • 


t • • • • 






.H7 


1.12 


2.07 


.00 


.16 


.28 


.00 


26 




• • • • 


• • • • 






.21 


1.74 


.77 


.00 


.04 


.04 


.00 


27 




• • • 1 


■ • • • 






4.51 


.47 


.00 


2.09 


.05 


.00 


.02 


28 




• • • • 


• • • • 






.27 


.79 


..53 


.00 


.80 


.00 


1.10 


29 




• • • • 


• • • • 






.61 


.17 


1.22 


.24 


.76 


.00 


1.53 


30 


■ 


• • • • 


• • • • 






.21 


2.47 


.52 


1.20 


.41 


.18 


.55 


81 




• • • t 


• • • • 






• • • • 


.73 


.73 


• • • • 


.36 


• • • • 


.64 




32.06 


7.31 


7.94 


10.97 


16.19 


16.81 


.34.44 


19.41 


22.51 


15.86 


11.02 


20.08 



Total for year, 214.60 Inches. 



PRECIPITATION AT SAN JOSE, COSTA RICA. 
Latitude, 9° 56' N. Longitude, 84° 8' W. Elevation, 3750 feet. 



Year. 


Jan. 


Feb. 


Mar. 


Apr. 


May. 


June. 


July. 


Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


AnnuaL 


1866 


1.30 


0.28 


0.00 


1.14 


5.47 


4.84 


12.60 


6.14 


10.79 


9.84 


6.73 


4.80 


63.93 


1867.... 


3.86 


2.21 


0.88 


3.86 


8.23 


8.11 


8.43 


- 7.48 


12.36 


8.89 


9.61 


0.66 


73.47 


1868 


0.00 


0.00 


7.13 


0.01 


2.27 


6.91 


4.02 


5.12 


8.82 


15.47 


6.67 


0.67 


56.09 


1869 


0.28 


0.00 


0.28 


1.10 


7.95 


8.58 


6.91 


6.20 


16.47 


11.06 


3.07 


4.02 


63.93 


1870. . . . 


0.04 


0.24 


1.22 


0.67 


13.11 


10.87 


9.45 


11.18 


9.45 


10.82 


7.24 


1.80 


75.09 


1871.... 


1.10 


0.12 


0.32 


0..51 


11.42 


7.99 


14.38 


12.09 


9.66 


13.11 


4.49 


0.43 


75.56 


1872 


0.12 


0.12 


0.59 


1.97 


9.61 


10.04 


7.56 


14. 8S 


15.63 


19.84 


5.59 


0.83 


86.78 


1878 


2.52 


0.00 


0.12 


2.80 


2.. 52 


8.07 


6.71 


8.35 


15.i^t 


10.32 


4.76 


0.43 


56.84 


1874 


1.81 


0.04 


0.79 


2.36 


13.23 


6.57 


6.88 


7.18 


12.66 


7.. 52 


1.65 


0.79 


60.83 


1875 


0.00 


0.00 


0.00 


1.10 


9.92 


7.09 


8.06 


11.57 


10.98 


13.35 


0.83 


1.26 


69.76 


1876.. . 


0.55 


0.00 


0.43 


0.24 


9.72 


9.33 


6.02 


7.56 


8.11 


4.61 


2.76 


1.10 


60.48 


1877 


0.55 


0.00 


0.00 


0.00 


9.45 


6.57 


8.78 


6.26 


10.20 


8.74 


4.76 


8.11 


53. 4d 


1878 


0.00 


0.00 


1.50 


1.97 


3.59 


7.86 


8.07 


5.87 


12.99 


9.37 


8.78 


0.79 


60.29 


1879. . . . 


0.51 


0.00 


1.77 


7. .56 


8.66 


12.99 


18 11 


11.14 


13.82 


9.09 


2.40 


0.32 


86.37 


1880 


0.32 


0.00 


0.00 


0.59 


10.00 


8.27 


4.09 


17.17 


6. .50 


10.94 


3.62 


0.00 


61.50 


1884 


0.00 


0.00 


0.08 


0.32 


0.48 


2.44 


0.59 


0.67 


4.41 


1.89 


7.44 


1.22 


19.49 


1885.... 


0.00 


0.00 


0.00 


1.85 


5.98 


3.07 


7.84 


3.86 


16.59 


12.87 


16.22 


2.82 


69.60 


1886 


0.00 


0.00 


2.05 


8.98 


15.. 55 


16.85 


20.. 59 


19.61 


22.91 


28.67 


16.81 


2.28 


154.30 


1887. . . . 


0.00 


0.00 


0.67 


0.28 


9.96 


14.16 


5.61 


9.40 


11.24 


13.16 


4.93 


2.07 


71.48 


1888 


0.63 


0.71 


0.00 


0.55 


7.07 


10.24 


6.49 


6. .54 


15.71 


10.39 


2.01 


0.87 


59.21 


1889 


0.01 


0.08 


2.91 


2.41 


14.57 


8.08 


6.06 


10.76 


16.89 


20.48 


2.45 


48 


85.18 


1890. . . . 


0.87 


0.08 


0.75 


2.52 


10.08 


11.65 


15.67 


10.65 


8.36 


7.99 


2.56 


0.71 


71.78 


1891.... 


0.03 


0.01 


0.05 


0.74 


4.26 


7.74 


8.00 


9.84 


12.80 


15.48 


5.57 


1.16 


65.18 


1892 


0.00 


0.00 


0.13 


0.07 


12.17 


15.06 


8.70 


13.75 


14.84 


21.36 


5.03 


0.44 


91.55 


1893 


0.04 


0.00 


0.02 


0.47 


8.73 


15.28 


13.90 


13.76 


20.75 


14.93 


7.08 


2.94 


97.90 


1894 


0.04 


0.00 


0.00 


0.99 


8.00 


7.83 


3.90 


9.76 


12.80 


8.54 


6.82 


0,65 


58.28 


1895. . . . 


0.15 


0.35 


0.04 


0.86 


15.12 


12.36 


4.76 


9 . 92 


11. .50 


7.32 


8.35 


6.02 


76.75 


1896 


2 . 13 


0.00 


0.04 


5.20 


6.57 


6.50 


8.23 


4.88 


8.15 


7.«7 


12.16 


3.03 


64.76 


1897.... 


0.20 


0.00 


0.28 


1.54 


12.20 


8.98 


4.83 


15.75 


12.05 


14.92 


3.11 


1.61 


74.97 


1898 


0.35 


0.00 


0.28 


1.80 


8. .58 


15.59 


8.90 


18.39 


13.62 


11.69 


4.65 


0.08 


78.48 



APPENDIX III.— HTDROORAPHK REPORT 



Purl Limw 

Matima .. 

Turrialha 

Juli 

Jma r«fl<M.. 
CaTlago., 
Agtmcalim 
Trea Rios 
La Verb«t 
Shu Joif . 
SaaFranclKo 

Haredli 

La Palms uu 
the divide. 



RAINFALL IN COSTA RICA. 
N. B.— The stations in Italic are on the Caribbean side of the main cordlllera. 



1=00' 21" 
I" 05' 3B" 
I" 13' 38" 
1° B5' 00" 



± II" a! 

± B°5' 



* 




Srt 






fl 


•f 








B 


K 








Ml 


«'l,. 


41) 






2H4 


JlfW 




aa 


1,MK4 


1^ 


asH 


sai 


1U4 


1.554 


AitA 


:^SS 


■JSrt 


flSfl 


8,433 


sail 


341 


S88 


ISO 





74.18 
61. 1» 

34.77 



EVAPOKATIOS. 

The rate of evaporation in the region of Lake 
Nicaragua has an important bearing upon the 
practicability of maintaining the summit level 
of the canal imder any plan yet proposed, and 
upon the means that must be provided for the 
maintenance of suoli level. 

Observations have shown that the inflow to 
Lake Nicaragua during the dry season is very 
small and indicate that in some years it is prac- 
tically zero for a considerable period, during the 
dry season, while at the same time, evaporation is 
at its maximum. For the purpose of ascertain- 
ing the amount of this evaporation, observations 
were taken at Fort San Carlos, San Ubaldo and 
Las Lajas. For this purpose evaporation pans 
were provided, which were made of galvanized 
sheet-iron about three feet square and two feet 
deep. The pan was anchored in some protected 
body of water, filled nearly full and floated by 
means of wooden buoys, fastened to the sides, 
A scale was provided reading to five-hundredtha 



of an inch, and by estimation to single hun- 
dredths. On this the height of the water was 
read each day, which was compared with the 
reading at the same hour on the previous day. 
The rainfall was measured by means of a rain 
gage, located in the immediate vicinity and its 
result applied as a correction to the change of 
water elevation in the pan. 

The obstacles to continuous, reliable observa- 
tions of evaporation are many. The pan was 
sometimes driven aground by winds and storms 
and the water spilled. Sometimes a leak would 
be caused in this way. Other causes tended oc- 
casionally to vitiate results, an idea of which 
may be formed from the following notes taken 
from the observer's note-book: 

" Heavy sea filled the pan. 

" Evaporating pan blown on the beach with 
bottom broken. 

" Soap found in pan ; some one had been tak- 
ing a bath. 

" Sand cleaned out of pan. 



284 



NICARAGUA CANAL COMMISSION 



" Pan swamped. 

" Pan shelved. 

" Reading useless on account of waves break- 
ing into pan." 

At Las Lajas the pan was disturbed at first 
by cattle. This was remedied by anchoring it 
in water too deep for them. At San Carlos the 
pan became at times a favorite roost for birds 
and a scarecrow had to be provided to keep them 
away. However, it was usually possible to 
judge correctly as to whether the observations 
had been vitiated and care was taken to eliminate 
those with regard to which a reasonable doubt 
existed. As might be expected from the above, 
there are many breaks in the continuity of ob- 
servations, days being omitted on account of 
doubtful conditions. 

In the following tables the daily mean in each 
case represent* the mean of good observations, 
this being multiplied by the number of days in 
the month to obtain the total for the month. 

As there was usually some motion to the water 
in the pan it was not always practicable to read ' 
the scale correctly within a tenth of an inch, but 
whatever error occurs from this cause applies 
with opposite sign to results preceding and fol- 
lowing the observation and the error is thus 
eliminated. The seeming fluctuation, therefore, 
which might be inferred from the table of ob- 
servations is chiefly due to this cause and in the 
main is unavoidable, and in anv event does not 
affect results, except in a slight degree at the 
beginning and end of a series of continuous ob- 
serv^ations. 

Allowance must be made in the use of these 
results for the fact that the conditions obtaining 
on the lake cannot be duplicated in the evaporat- 
ing pan. During the dry season the trade winds 
blow stronfflv from the eastern side of the lake 
to the western. Except along the eastern shore 



the surface of the lake is blown into billows, the 
waves often attaining a considerable height and 
being crowned with whitecaps. In this way a 
large quantity of spray is thrown into the air, 
and the total water surface in contact with the 
trade wind is much greater than the level sur- 
face of the lake. More than half the area of the 
lake^ therefore, must lose by evaporation a 
greater depth of water than the pan. 

The observations taken furnish another 
method of computing the evaporation. from the 
lake. 

Records showing the height of the surface of 
the lake were kept at San Carlos, San Ubaldo 
and Las Lajas. Observations of rainfall were 
taken at all these places, and at Tipitapa, about 
ten miles northwest of the lake. A circuit of 
the lake was made in April and May, for the 
purpose of measuring the inflowing streams. 
A record of the discharge of San Juan river was 
kept at Sabalos, above Toro rapids. From April 
10 to May 10 the lake fell 8.64 inches. During 
the same time rain fell as follows: 

Inchefi. 

San Carlos 3.20 

Las Lajas 22 

San Ubaldo 50 

Tipitapa ; 00 

Sum 3.92 

iiean 98 

The measured outflow was 714,000 acre-feet, 
and the inflow is estimated to have been 120,- 
000 acre-feet, making a net decrease of 3.50 
inches in lake elevation, due to flowage. 

Assembling these facts, we have 

Evaporation = 8.64 -f .98 — 3.50 = 6.12. 

During the same time the evaporation ob- 
served was as follows: 



APPENDIX III.— HYDROGRAPHIC REPORT 



285 



Inches. 

San Carlos 4.77 

Tipitapa 6.05 

San Ubaldo 6.30 

Las Lajas 7.89 

Sum 25.01 

Mean 6.25 

This is a cloee check, and indicates that either 
method would afford a fair approximation of 
the amount of the evaporation. Being the last 
month of the dry season, it probably represents 
about the maximum for the year. The rain- 



fall records for Eivas and also for Masaya show 
that 1897 was the year of maximum rainfall so 
far as observed, and 1898, appears to be above 
the average, so that during the season under 
consideration the evaporation was probably not 
as great as it sometimes becomes, and in the 
dryest years may approach seven inches in one 
month. 

The usual dry season at Rivas is from about 
the middle of December to the middle of May. 
It doubtless begins earlier and ends later in the 
years of least rainfall, and may continue over 
six months. 



EVAPORATION, LAS LAJAS. NICARAGUA. 



Day. 



lovD. 

Mar. 



Apr. 



May. 



June. July. Aug, 



Sept. 



Oct. 



Nov. 



Dec. 



1809. 
Jan. 



Feb. 



Mar. 



1 
3. 

3. 
4. 
6. 

6 

7, 

8. 

9. 

10. 

11. 
12. 
13. 
14. 
15. 

16. 
17. 
18. 
19. 
SO. 

21. 
32. 
23. 
24. 
25. 



.10 
.20 
.07 
.18 



.30 
.31 
.84 

.28 
.28 

.21 
.24 
.35 
.31 
.27 

.23 
.33 
.30 
.24 



.17 
.24 
.21 

.28 
.26 

.27 
.28 
.39 
.23 
.20 



.24 
.26 
.24 
.27 



.27 
.23 
.27 
.32 
.29 

.24 

• • ■ • 

.21 
.28 
.10 

.19 
.25 
.16 
.16 
.04 

.13 



.14 
.20 

.13 
.22 
.20 
.21 
.19 

.14 
.24 

.17 



.04 



.15 
.07 
.17 
.10 
.07 

.18 

• • • 

.12 
.01 
.05 



04 
17 



19 
14 

17 
18 



19 
12 
09 
13 

06 
03 



11 



07 



07 



.12 
.13 



.06 
.11 
.08 
.09 

.05 
.18 
.12 
.14 
.11 

.09 
.11 
.16 
.08 
.13 



.15 
.08 
.10 



.10 
.11 
.09 

• • • 

.10 

.10 
.13 
.08 
,15 
.16 

.11 
.15 

• • • 

.02 
.10 

.10 
.11 
.04 
.09 
.11 

.04 
.11 

• • • 

.04 
.08 



05 

• • 

06 



16 

• • 

05 

07 
05 
10 
05 



14 
16 
13 
05 

13 
04 



.10 
.10 
.15 



.10 
.10 
.22 
.12 
.05 



.08 
.03 



I 



.09 
.03 

.04 
.10 

.45 



.10 
.02 
.07 
.07 
.10 

.11 
.10 
.09 
.05 
.14 



.09 
.07 
.08 
.09 
.11 

.04 
.15 
.10 
.14 
.13 



1 



.30 

.12 
.15 

.09 
.12 
.12 
.08 
.09 



.12 
.13 
.10 
.10 
.10 

.12 
.07 
.11 



.09 
.14 
.07 
.11 



.10 

.22 
.13 



{.88 { 



.82 



.12 
.80 
.10 
.20 
.08 

.09 
.09 
.11 



.10 
.12 
.18 
.18 



.20 

.25 

.28 
.12 



08 


.13 1 


• VA^ 


.10 


11 


.08 


« 


.15 


12 


.11 


.12 


.10 


10 


.10 


.18 


.17 


10 


.10 


.11 


.08 



1- 



.11 

.14 

80 
.15 

.07 
.11 



.17 



1 .27 I .22 I • 



28 



286 



NICARAGUA CANAL COMMISSION 



EVAPORATION, LAS LAJAS, NICARAGUA.— Continued. 



Day. 

26 

27 

28 

29 

30 

31 

Mean . . « 

Total . . . 



Mar. 
18JW. 



Apr. May. June. July. Aug. 



Sept. 



Oct. 



Nov. 



1-PGC» 



Jan. 

lollv. 



Feb. 



Mar. 



.18 
.22 
.32 
.15 

• • • 

.25 



.34 
.28 
.26 
.25 
.22 



.03 
.13 
.10 
.12 



• • • • 



.14 



03 


.10 


.05 


05 


.12 


• • • • 


11 


.16 


.02 


12 


• * • • 


.10 


■ • 


• • • • 


.08 



.05 



.10 
.10 
.07 



.15 

* • • 

.07 
.06 
.06 



.12 
.13 
.09 
.06 
.11 
.12 



.08 
.09 
.12 
.12 
.16 
.12 



11 
15 
11 



.33 
.04 
.05 
.17 
.13 
.13 



.186 



.271 .193 



.145 



.109 



.110 



091 



.088 0.100 



.097 



.110 



121 



.137 



5.77 8.13 



5.98 



4.35 



3.38 



3.41 



♦> 



73 



2.73 



3.00 



3.01 



3.40 



39 



4.25 



EVAPORATION, SAN UBALDO AND MORRITO, NICARAGUA, 1898. 



Day. 



April. 



May. 



June. 



July. 



AuRTUSt. 



September. 



1. 
2. 
3. 
4. 
5. 

6. 
7. 
8. 
9. 
10. 



11... 
12... 
13... 
14... 
15. .. 

16... 
17... 
18... 
19... 
20... 

21 . . . 
22... 
23... 
24... 
25... 

26... 
27. . . 
28... 
29... 
80... 
31... 

Mean. 
Total 





.22 




.15 




.30 




.20 




.19 




.17 




.23 




.'22 




.14 


.32 


.25 


.20 


.13 


.15 


.20 


.20 


.30 


.25 


.25 


.10 


.06 


.30 


.19 


.12 


.20 


.15 


.16 


.25 


• • • • 


.30 


• • • • 


.15 


• • • • 


.20 


• • • • 


.18 


• ■ • • 


.27 


• • • • 


.25 


• • • • 


.26 


• • • • 


.25 


.30 


.25 


.25 


.17 


.31 


.18 


.03 



.20 
.05 
.09 
.02 

.25 

• • • 

.17 
.32 
.36 

.08 
.21 
.13 
.14 
.20 

.20 
.15 
.18 
.23 

.15 



.22 

.17 
.26 

.13 
.28 
.02 
.20 
.14 



.214 
6.42 



.202 
6.26 



• • • • 



.173 
5.19 



.10 
.12 
.21 
.15 
.15 

.13 
.10 
.11 
.11 

.12 



.25 
.35 
.21 
.21 

.12 



.21 

.17 
.05 
.15 
.28 



.05 
.27 



• • • • 



.15 
.01 
.13 
.25 
.12 

.18 
.19 
.15 
.12 
.22 

.14 
.22 
.15 



.164 
.5.08 



.08 
.15 
.10 
.14 
.31 

.22 

.17 
.09 
.20 
.08 

.14 
.17 
.17 
.12 
.20 
.18 
.1.57 

4.87 



07 
12 
19 
28 
07 

18 
15 
11 
10 
23 



145 
35~ 



APPENDIX III.— HYDROGRAPHIC REPORT 



287 



EVAPORATION, FORT SAN CARLOS, NICARAGUA. 



Day. 


Mar. 

1808. 


Apr. 


May. 


June 




July. 




Aug. 


Sept. 


Oct. 


Nov. 


Dec. 


im Feb. 


Mar. 


Apr. 


1... 


• • • • • 


.15 


a a a • 


.11 




.19 




.06 


.22 


.20 


.14 


a a a • 


• m • • 


.15 


.11 


.15 


o 

A^ . . . 


• • • • • 


.20 


.21 


.18 




.23 




•09 


.13 


a a a a 


.20 


.12 


.15 


.15 


.15 


.15 


(5 . . • 


• • • • • 


.16 


.16 


.18 




.13 




.11 


.14 


.06 


.15 


.12 


• m • * 


.10 


.11 


a a a a 


4... 


• • • • • 


.19 


.16 


.18 




.05 




.10 


a a a a 


.13 


.20 


.15 


a • a a 


.15 


.15 


a • a • 


5. . . 


• • • • a 


.09 


.08 


.12 




.10 




.09 


.07 


a a a a 


.10 


.19 


.12 


.15 


.10 


.17 


6. . . 


• • • a • 


.01 


.20 


.10 




a a a a 




.14 


.07 


a a a a 


.10 


.11 


.15 


.14 


.12 


.12 


7... 


• • • • ■ 


• • • 


.18 


.07 




.14 




.14 


.09 


m • • • 


.15 


.18 


.13 


10 


a a a a 


a a a a 


o. . . 


• • • • a 


.17 


.15 


.21 




.12 




.18 


.06 


a a * • 


• • • a^ 


.14 


.10 


a a 


a a a • 


a a a a 


«». . • 


.12 


.19 


.22 


.11 




.10 




.11 


.06 


.11 


.07 


.14 


.08 


a a 


• a a a 


.14 


10... 


.01 


.13 


• • • a 


.20 




.11 




... 


.18 


.12 


.08 


a a a a 


.08 


.10 


• a a 


a a a a 


11... 


• • • • a 


.16 


■ a a a 


.10 




> a a a 




.11 


.20 


a a a a 


.12 


.15 


.10 


a a 


a a a a 


.10 


1*> 

X w . . . 


.12 


.18 


• • • • 


.11 




• a a a 




.11 


• 9 • • 


.13 


|.25 


.12 


.08 


11 


.14 


a • a a 


13... 


.08 


.12 


a • • • 


.16 




.18 




.11 


a a • a 


.14 


a a a a 


a a a a 


.08 


.15 


.15 


14... 


.17 


.13 


■ • • • 


.29 




.09 




.12 


m • • • 


.10 


.09 


.15 


^a a a a ■ 


15 


.10 


.10 


15... 


.06 


.17 


a a • • 


.07 




.15 




.06 


• m • • 


.09 


.05 


.15 


a a a a 


.13 


.10 


.15 


16... 


.19 


.26 


• • • • 


.09 




.13 




.10 


.12 


.15 


a a a • 


.11 


.10 


06 


.10 


.15 


17... 


.15 


.09 


a • a a 


• • a • 




.12 




.12 


.22 


a a a • 


a a a a 


.14 


.10 


.07 


.15 


.20 


18... 


.21 


.15 


.05 


.12 




.12 




.19 


.17 


a a a a 


.06 


.12 


.11 


08 


.15 


.15 


19... 


.19 


.08 


• • • a 


a • • • 




.31 




.21 


.04 


a a a a 


.10 


.15 


.15 


12 


.15 


.20 


20... 


.20 


.18 


.22 


a a a 




.07 




.14 


.09 


.11 


.10 


.10 


.10 


10 


.15 


.20 


21... 


.20 


.22 


• • • • 


• % m 9 




a a a 




.12 


.08 


a a a a 


.13 


.05 


.22 


10 


.15 


.20 


22... 


• • • • a 


.11 


a • a a 


• % • % 




.12 




.14 


.05 


.19 


• • * • 


.15 


.18 


.15 


.15 


• .20 


23... 


.14 


.16 


a • • • 


.17 




a a a 




.13. 


.06 


• • a • 


.15 


.10 


.15 


15 


.15 


.20 


24... 


.22 


.15 


a a a • 


a • a 




• • • 




.07 


.15 


a • a • 


|.15 


1 .20 


.15 


• a 


.15 


.15 


25... 


.14 


.17 


a a a • 


.12 




.10 




.00 


.15 


.14 


.10 


a a 


.20 


.15 


26... 


.28 


.11 > 


m • • • 


.11 




.12 




.11 


a a a a 


• m • • 


.10 


.17 


.10 


10 


.15 


.20 


<S 1 . . . 


.12 


.16 


m • • • 


.25 




.08 




.11 


.10 


a a a a 


.08 


.09 


.10 


10 


.15 


.15 


28... 


.15 


.18 


.07 


.12 




.05 




.14 


.15 


• a • 


.08 


.18 


.10 


15 


.15 


.20 


21> . . . 


.21 


.16 


.12 


.12 




.07 




.17 


a • • • 


.15 


.18 


.09 


.10 


• a 


.15 


.20 


30... 


• • • a • 


.15 


.12 


.07 




.11 




.11 


a a • a 


.15 


m % * • 


.06 


.15 


• • 


.20 


.25 


31... 


• • • a • 


• • • • 


.12 


a a • • 




.10 




.09 


• a a a 


.15 

a 


• 9 • • 




.09 


• a a a a a 


a a 


.10 


a a a a 


Mean 


. .153 


.164 


.147 


.140 




.124 




.119 


.118 


.132 


.113 


.130 


.121 .1 


17 


.140 


.168 


Total! 


s 4.74 


4.92 


4.56 


4.20 




3.84 




3.69 


3.54 


4.09 


3.39 


4.03 


3.75 3. 


28 


4.34 


5.04 








ESTIMATED MONTHLY EVAPORATION OF LAKE NICARAGUA. 








Mod 


th. 


Discharge in Second-Feet. 

. ^ Total for 

San Tias Ft. San month. 
Ubaldo. Lajas. Carlos. 




Month. 


Discharge in Second-F 

San Ta8 Ft 
Ubaldo. LaJas Ci 


eet. 

, San 
irlos. 


Total for 
month. 


18 


98. 


Inches. 


Inches. 


Inches. 


Mean. 




1898. 


Inches. 


Inches. In 


ches. 


Mean. 


Marcl 


I a • • • 


• • a • 


5.77 


4. 


74 




5. 


25 


( 


Dctober . . 


a a 


» • a 


2.73 4 


.09 


8. 


41 


April 




6.42 


8.13 


4. 


92 




6 


.49 




November 


■ a a 


a « 


3.00 8 


.39 


3. 


20 


May . 




6.26 


5.98 


4. 


56 




5 


.60 




December 


* • 


» • a 


3.01 4 


.03 


3. 


52 


June. 




5.19 


4.85 


4. 


20 




4 


.58 




1899. 














July . 




5.08 


8.38 


8. 


84 




4 


.10 


« 


January. . 


• • I 


• ■ 


3.40 3 


.75 


3. 


57 


An^ 


Bt . . . 


4.87 


3.41 


8. 


69 




3 


.99 


] 


February. 


• a 


» a a 


3.39 3 


.28 


3. 


34 


Septei 


mber. 


• • • a 


2.73 


3. 


54 




3 


.13 


■ 


March . . . 


a a 1 


• a 


4.25 4 


.34 


4. 


30 



NICARAGUA CANAL COMMISSION 



EVAPORATION, TIPITAPA. NICARAGUA. 



17 
30 




06 




30 




IS 




OH 





u«» 


300 


-88 OS IM ISO 44 143 36 ISB 


184 


84 


147 


Toul 


5 77 


7 IB 5.7B AM S.40 4A6 4.43 8.87 4.22 


iM 


4. S 


4..5<l 


EVAPORATION, SAN CARLOS RIVBR, NICARAGUA, 1898. 



APPENDIX III.— HYDROGRAPHIC REPORT 



289 



EVAPORATION, SAN CARLOS RIVER, NICARAGUA, 1898.— Continued. 



Day. 



March. 



April. 



May. 



Juno. 



11 


.02 


• • ■ • 


• ■ • 


• • • 


• 


12 


.06 


06 


• • 


.10 


18 


.05 
.04 


10 
11 


.21 
08 


• • • • 


14 


» • « • 


15 


• ■ ■ 1 


OS 


I • • 


.15 


16 




08 
.10 


> • • 

.10 


• « • • 


17 






18 


• • • • 1 


• • < 


09 






19 




.10 


I • • 






20 




07 


.11 






21 




.12 


.12 






22 




.04 


.13 






23 


• • ■ • 


» • ■ t 


03 








• • • • 4 


» • • 

.09 
06 


.10 
.10 

.07 






25 








27 


• • ■ • 


> • • 


.07 








• • • • 


> • . • 


» • • 






29 


.08 


> • . • 


• • • 








.13 


.10 


■ • • 






31 


• ■ • • 


» • • • 


» • • 










Mean 


.077 


090 


095 


.093 


Total 2 


.39 2 


.70 2 


.95 


2.7 


9 



EVAPORATION, OCHOA. NICARAGUA. 



Day. 


Mar. 
1898. 


Apr. 


May. 


Juno. 


July. 


Aug. 


Sopt 


Oc-t. 


Nov. 


Dec. 


Jan. 
1899. 


Feb. 


1.... 


• • • • 


.04 


.10 


.03 


.08 


.08 


.11 


.10 


.05 


.05 


• • • • 


.12 


2.... 


• • • • 


.03 


.07 


.10 


.06 


.02 


.06 


.09 


.05 


.04 


• • ■ • 


.05 


3. . . . 


> • • ■ • 


.11 


.14 


.10 


• • • • 


.06 


.04 


.07 


.05 


.08 


.10 


.10 


4.... 


.08 


• • ■ • 


.20 


.08 


.02 


.01 


.07 


.05 


.07 


.08 


.10 


.07 


5.... 


.17 


.25 


.11 


.07 


.11 


.11 


.04 


.09 


.08 


.03 


.06 


• • • • 


«.... 


.14 


.02 


.04 


.10 


» .03 


.01 


.03 


.11 • 


.12 


.09 


.08 


.08 


pa. 
< 


.18 


.09 


.20 


.09 




.06 


.03 


.01 


.04 


.09 


.06 


.05 


8... 


.18 


.09 


.16 


.07 




.03 


.09 


.11 


■ • • • 


.06 


.09 


.08 


9... 


.15 


.11 


.13 


.11 




.11 


.03 


.05 


.03 


.04 


.04 


.10 


10... 


.09 


.19 


• • • • 


.05 




.04 


• ■ • 


.07 


• • • • 


.06 


.14 


.05 


11... 


.03 


.04 


.00 


.06 




.02 


.06 


.05 


• • • • 


.08 


.06 


.07 


12... 


.05 


.11 


.12 


.16 




.06 


• • • 


.08 


.OS 


.06 


.04 


.04 


13... 


.20 


.11 


.07 


.06 




.11 


.10 


.04 


.11 


.06 


.OS 


■ • • • 


14... 


» • • ■ • 


.12 


.08 


.09 




.11 


.08 


.05 


.04 


.02 


.02 


.08 


15... 


.27 


.12 


.08 


.05 




.05 


.08 


.08 




.08 


.07 


.06 


16... 


> • • • • 


.11 


.08 


.02 




.07 


.07 


.06 




.07 


.12 


.08 


17... 


• • • • 


.10 


.09 


.05 


.... ^ 


.05 


.08 


.02 




.09 


.00 


.02 


18... 


.14 


.13 


.11 


• • • • 




.04 


.05 


.00 




.03 


• • • • 


.06 


19... 


.26 


.08 


.21 


.15 




.06 


.08 


.12 




.08 


.02 


.11 


30... 


.15 


.18 


.09 


.17 




• • • • 


.04 


.03 


.08 


.08 


.05 


.07 



19 



290 



NICARAGUA CANAL COMMISSION 



EVAPORATION, OCHOA, NICARAGUA.— Continued. 



Day. 



Mar. 

1898. 



Apr. 



May. 



June. 



July 



Au^. 



Sept. 



Oct 



Nov 



Dec. 



Jan. 



Feb. 



21... 


.04 


.13 


• • • • 


.09 






.12 


.02 


.07 


.06 


.04 


.03 


22... 


.10 


.10 


.04 


.08 






.15 


.09 


.03 


.07 


.09 


• • • • 


23... 


.12 


.06 


.02 


.07 






.03 


.09 


.04 


.09 


.05 


.08 


24... 


.10 


.11 


• • • • 


.28 






.06 


.15 


.05 


.07 


.08 


.07 


25... 


.06 


.11 


• • • • 


.13 






• • • • 


.02 


• • • • 


.04 


.08 


.03 


26... 


.17 


.15 


.09 


.12 






• • • • 


.01 


.08 


.13 


.04 


■ • • ■ 


27. . . 


.13 


.16 


.11 


.03 






.08 


.05 


.10 


.06 


.11 


.10 


28... 


.03 


.11 


.02 


.09 






.04 


.04 


.07 


.07 


.02 


.08 


29... 


.09 


.16 


.19 


.01 


.06 




.05 


.02 


.05 


.06 


.09 


• • • ■ 


30... 


.07 


.12 


.25 


.08 


.04 


.04 


.11 


• • • • 


• • • • 


.09 


.04 


• • • • 


81... 


.24 


• • • • 


.05 


. • . • 


• • • 


.03 


• • • ■ 


• • • • 


• • • • 


.06 


.05 


• • • • 


Mean 


.125 


.110 


.109 


.089 


.070 


.056 


.063 


.062 


.060 


.060 


.066 


.067 


Total 


3.88 


3.30 


3.38 


2.67 


2.17 


1.74 


1.89 


1.92 


1.80 


1.87 


2.05 


1.88 



EVAPORATION, GREYTOWN, NICARAGUA, 1898. 



Day. 


Jan. Feb. 


Mar. 


\pr. May. June. July 


AujJT Sept. Oct. Nov. Dec. 


1 


.01 


04 


.13 




.18 


■ • • ■ • • 


.24 


• • • • • 


• • • • 


.10 


o 


.21 


.08 


.25 










.25 


• • • • • 


• • • ■ 


■ • • • • • • 


3 


.38 


.04 


.10 










» • • • « 


• • • • • 


• • • • 


.03 


4 

5 


.08 


• • • 

.05 


.23 
.39 

.22 






• 




• • • • 

.20 

• • • • 


k • • • 

• • • • 

.05 


.21 

.08 

• • • • 


|.15 


6 


.06 


.11 


7 


.06 


• • • 


.37 










• • • • 


.25 


» • • • 


.14 


o . ... 


.44 


.25 


.08 










• • • • 


.10 


02 


.05 


9 


.... 


.20 


• • • • 4 




.27 






f • • • • 


• • • • 


.05 


04 


10 


.05 


.19 


• • • • « 


• • • • 


• • • • 






• • • ■ 


.10 


» • • • 


• • • • • • • 


11 


04 


.20 


.20 




.06 






• • • • 


.15 


■ • • 


.08 


12 


.03 


.27 


.35 




.35 






• • • • 


» • • • ■ 


17 


,07 


13 


.... . < 


» • • 


.30 




.18 






.27 


• • • • 


06 


.04 


14 


.13 


19 


.35 




.27 






• • • « t 


• • • ■ 1 


• • • 


.15 


15 


.09 


• • 


.40 




.10 






.10 


.10 


04 


.la 


16 


.16 


30 


.25 


.30 


.39 






.30 


.20 


• ■ • 


.09 


17 


.21 


13 


.18 


.06 


• • • • 






.01 


.15 


• • • 


.10 


18 


.05 


15 


.25 


.20 


• • ^ 






.15 


.10 


07 


.04 


19 


.06 


19 


.30 


.10 


.03 






.10 


• • • « 


12 


.15 


20 


04 


12 


.20 


.20 


.28 






.84 


.10 


10 


.OS 


21 


• • • • 


12 


.15 


.20 


.13 






.08 


.07 


02 


.11 


22 


.08 


14 


.23 


• • • 


.07 






.10 




13 


.03 


23 


.09 


28 


.19 


• • • 


.35 






.15 




12 


.07 


24 


.10 


13 


.21 


.25 


• • • • 






.15 




14 


.13 


25 


.13 


15 


.08 


.12 


.40 






.25 


... 


• • • 


.15 


26 


• • • ■ I 


18 


.27 


.10 


.05 






.30 




13 


.09 


27 

28 


.09 
.37 


• • 

15 


.17 
.30 


.05 
.39 


.05 
.05 






.05 
.10 


• • • « • 


07 

• • • 


::: {■'• 


29 


.23 


• • 


.30 


.40 


.05 






.25 


■ • • • • 


• • • 


* • • • • • • 


30 


.25 


• • 


• • • 1 


.15 


.05 






.... . 


• • • • • 


• • • 


.09 


31 


.18 


■ • 


• • • • • 


• • • 


.23 






.18 


• • • • • 


• • • 


.07 


Mean. . . 


.138 


161 


.238 


.193 


.177 






.178 


.125 


096 


.083 


Total . . . 


4.28 4. 


51 


7.38 5 


.79 S 


».49 






5.52 .^ 


{.75 2. 


98 


3.57 



APPENDIX III.— HYDROGRAPHIC REPORT 



291 



Water Supply. 

In contemplating any canal in which locks 
are to be used the first question occurring to the 
investigator is with regard to the adequacy of 
water supply; and in a country with a dry sea- 
son as definite and prolonged as that of the region 
tributary to Lake Nicaragua, storage of water 
must be provided against evaporation, leakage 
and use during the dry season. The Nicaragua 
Canal project is exceedingly fortunate in hav- 
ing at its summit level Lake Nicaragua, a mag- 
nificent 'natural reservoir, fed by an ample 
drainage basin. This reservoir is useful not 
only for storing water for use of the canal, but 
also as a regulator for the control of great floods 
that could hardly be provided for at practicable 
cost without its aid. On the other hand, the 
lake exposes its vast surface of two million acres 
of tVater to the constant action of the trade 
winds, and observations indicate that the lake 
loses about 17,000 cubic feet per second by 
evaporation during the dry season. 

All proposed plans for the canal involve the 
use of Lake Nicaragua as part of the sailing 
course, and the conversion of a portion of the 
San Jiian river and of the canal through the 
AVestem Divide cut, into arms of the lake. 
A course of about twelve miles in the present 
lake will require deepening, about thirty miles 
of river will require dredging, and nine miles of 
heavy excavation will be made on the west side 
to provide for a sufficient depth for navigation, 
below the minimum level to which the lake will 
be permitted to go. Every foot that the eleva- 
tion of the summit level is allowed to decline, 
therefore, involves a foot of excavation or dredg- 
ing through about fifty miles of canal, and the 
financial inducements are strong for holding the 
minimum as high as practicable. On the other 
hand there is an upper limit to the height that 



the lake surface niav be allowed to attain, be- 
yond which great damage will be done to the 
lands and settlements around the lake. Thus it 
is necessary to assign definite limits as narrow 
as practicable between which the lake is to be 
held. 

From evidence of the inhabitants of Granada 
it is deduced that the highest point the lake has 
reached during the past forty years is nearly 111 
feet above sea level. From evidence of citizens 
at San Ubaldo it was learned that the lake 
reached a maximum of about 107.5 in 1893. 
This is probably the highest point the lake has 
reached since the Rivas rainfall record began, 
in 1880. The year 1897 shows a rainfall of 
123 inches, as against 105 for 1893; but the 
lake did not in 1897 reach as high a point as in 
1893. The cause is to be found in the state of 
the lake at the opening of the rainy season. 
That of 1897 found the lake at the lowest point 
it had been known recently, caused by a suc- 
cession of three years with rainfalls 18 to 30 
inches below the mean, while 1893 was preceded 
by a rainfall for 1892 over ten inches above the 
mean, and for 1891 slightly below, so that the 
lake must have been somewhere about its nor- 
mal stage. The rainfall record does not indicate 
any likelihood that the lake reached any stage 
higher than that of 1893. 

It may be said, therefore, that the lake has 
been known to rise to an elevation of nearly 111, 
but that ordinary wet years it does not reach 108. 

The rise of 111 inundated considerable im- 
proved property, and submerged large areas of 
land which at present is unused except for pas- 
turage. As the water reaches that point but 
once in more than a generation or perhaps in a 
century it could not be allowed to rise so high 
every year without involving heavy damages. 
Jt is somewhat difficult to determine with present 



292 



NICARAGUA CANAL COMMISSION 



in formation just how high it would be advisable 
to allow the lake to rise everv vear, but it eer- 
tainly ought not to be higher than 110. This 
would inundate some land of value at Granada, 
and large areas along the east and south of the 
lake, which, though having no present value, are 
susceptible of cultivation and improvement, but 
it would avoid any heavy bills for damages to 
property. The construction of the canal on a 
plan contemplating inundation to 110, would not 
prevent deepening at any future time that it is 
desired to reclaim submerged land. For present 
purposes we assume the maximum limit as 110. 
In fixing the lower limit it is necessary first 
to examine the conditions of water supply. If 
there is any considerable period during which 
the inflow is less than the evaporation, water 
must be stored to compensate for the loss, to pre- 
serve the required depth for navigation. 

Amount of Storage Necessary. 

To determine the inflow, measurements were 
made during the dry season of 1898, with a re- 
sult showing that only two streams were bringing 
any considerable quantitv' of water into the lake, 
and that the total inflow was about 10 per cent, 
of the evaporation taking place at the same time. 
Nearly all the streams inspected showed evi- 
dences of having been stagnant a long time, the 
water being foul and dark-colored, with much 
vegetation growing upon it, which, not being 
rooted to the soil, would have passed out into 
the lake, had there been any considerable cur- 
rent. If this condition existed in 1898, a 
year of more than average rainfall, there must 
be several months during ordinary years which 
furnish very little water to the lake. The rainy 
season usually closes some time in December, the 
mean rainfall during that month at Rivas being 
only 1.29 inches. In 1898 the rainy season 



began about the middle of May, which is un- 
derstood, to be about the normal time. This 
is well shown, in the diagram, Plate XV. It 
may be said in general that the rainy season is 
slightly longer than the dry season, but in years 
of minimum rainfall this relation is reversed. 
The maximum evaporation in the diy season is 
over 6 inches per month; in the rainy season it 
is much less, and in the early part of the drv sea- 
son is probably less than 6 inches. It may be 
assumed that for some time after the close of 
the rainy season the inflow to the lake 'will con- 
tinue equal to or greater than the evaporation. 
It certainly would not be extravagant to assume 
that there are four months in which evaporation 
exceeds the inflow by an average of six inches 
per month. In other words, for the normal 
diy season we should provide two feet in depth 
of storage to make good the ravages of evap- 
oration,* and if 105 is to be adopted as the min- 
imum summit level to be allowed, the elevation 
of the lake at the beginning of the dry season 
should not be less than 107. 

Tliis provision against evaporation might be 
sufficient if we could be sure that in any cycle 
of twelve months the inflow to the lake was 
greater than the evaix>ration during the same 
twelve months, but unfortunatelv no such assur- 
ance can be given. AVhile the mean annual 
rainfall in the basin is much gi^eater than the 
evaporation, as proved both by the measured 
quantities of evaporation and rainfall, and by 
the fact that water is always being discharged 
through the San Juan river, there is in this 
basin, as in all other regions, a disparity in pre- 
cipitation between the dryest and the wettest 
year which forbids the consideration of averages 
in any such problem. For purposes of storage 
against evaporation we must consider the years 
of minimum inflow and maximum evaporation. 



APPENDIX III.— HYDROGRAPHIC REPORT 



293 



For purposes of computiiiia: spillway capacity we 
must coDsider vears of maximum inflow coinci- 

t 

dent with minimum evaporation. The data on 
this point consist of a series of rainfall observa- 
tions at Rivas, extending from January, 1880, 
to October, 1808, reported by Dr. Earl Flint, 
and the short records taken bv the Commission. 
The year of minimum rainfall shown by the 
record at Tfivas, is 1890, in which 31.81 inches 
fell. The rainy season in 1898 began about the 
middle of !N[ay. During May and June of this 
vear 85.12 inches of rain fell at Rivas, or 3.31 
inches in excess of the total for 1890. The 
amount of water received by Lake Nicaragua 
from May 1 5 to June 30 in excess of evaporation 
was about sufficient to raise the lake two feet. 
If the evaporation in this time be taken as 8 
inches we have a gross inflow of 2 feet and 8 
inches, as the yield of the basin for this rainfall. 
The run-off of the given precipitation is much 
greater when concentrated within the period of 
45 davs than it would have been if distributed 
over a period of six months, but on the other 
hand, if no rain had fallen during July, a con- 
siderable quantity of water w^ould doubtless have 
flowed into the lake, as the result of June pre- 
cipitation. This would probably more than 
compensate for the excess due to the concentra- 
tion of the rainfall above mentioned, and to the 
fact that 35.12 inches exceeds the rainfall of 
1890 by over three inches. Suppose we allow 
four inches depth for the July nm-off due to 
June rainfall. We have, then, as the run-off 
for the May and June rainfall sufficient water 
to raise the lake three feet, if it had been isolated 
and evaporation eliminated. The evaporation 
during a diy year could not be much below 60 
inches; this leaves a deficit of two feet, which, 
under the above assumption, the minimum year 
would have wanted of supplying sufficient water 



to compensate for evaporation. The year 1885 
shows a rainfall of 34.59 inches, so that the vear 
1890, though the minimum in the record, is not 
an especially anomalous case, and other years of 
as small or even smaller rainfall should be ex- 
])ected and provided for. 

The mean rainfall on the lake surface, taking 
the records of l^as Lajas, San Carlos, Tipitapa 
and San Ubaldo, is 23.18 inches during this 
time, made up as follows: 

San Carlos 21.08 

Las Lajas 23.93 

Tipitapa 25.44 

San Ubaldo 22.25 

Mean 23.18 

None of these records show as great a rainfall 
as that n^ported for Rivas, by about ten inches. 
This is the more remarkable as the station at 
Las Lajas is hardly seven miles from Rivas. 

The conditions at Rivas may have been local 
and anomalous, and the conclusions drawn from 
the above estimate cannot be considered as final, 
but they are sufficient to indicate that the ade- 
quacy of the annual water supply is at least 
doubtful. 

To approach the problem from the other side, 
supj)ose the mean rainfall for the basin of Lake 
Nicaragua for the minimum year to be two feet. 
This, if all held and evaporation eliminated, 
would raise the lake t\vo feet by precipitation 
<Hrectly upon it. To this should be added the 
probable run-off from the drainage area, but in 
this we should not include the drainage of Lake 
Managua. It is said that at times this lake con- 
tributes no water to Lake Nicaragua for several 
years, and there certainly must be years when its 
contribution is so low that we should not con- 
sider it in an estimate of this kind. Taking the 
area directly tributary to Lake Nicaragua as 



294 



NICARAGUA CANAL COMMISSION 



6000 square miles and the run-off for two feet 
of rainfall at 25 per cent., the lake would re- 
ceive sufficient water from its tributary area to 

ft, 

raise it one foot, which, added to that falling 
directly upon the lake, gives us three feet as the 
total yield of two feet of rainfall, which agrees 
with the estimate deduced from recorded obser- 
vations on the lake, and leaves a deficit of two 
feet. 

Since a year is likely to occur in which evap- 
oration and use exceed the inflow by two feet, 
that year must be commenced with a water level 
two feet above the minimum elevation which is 
to be permitted. As it is impossible at present, 
and will always be imiK)ssible, to predict just 
when that year of minimum inflow and maxi- 
mimi evaporation is likely to occur, the effort 
should always be to maintain the summit level 
at two feet above the minimimi. To reach a 
conclusion as to the elevation at which the lake 
surface should be held at any given time in order 
to insure against its decline below the minimum 
level, let us assume a state of climate in which 
the inflow is always greater than the evaporation 
during any twelve months. As above stated, 
the evaporation in excess of inflow in the normal 
dry season is estimated at two feet. It would 
be necessary, therefore, at the end of each rainy 
season to hold the summit level two feet above 
the minimum summit level. If this be 105 
then the nile would be to enter the drv season 
witli the level at 107, the estimate being that by 
the time rains begin in May this surplus water 
would be evaporated and the summit level would 
stand at 105. Xow suppose that in the ensuing 
year the evaporation and leakage should ex- 
ceed the inflow by two feet, the natural decline 
in summit level would bring it down to 103, 
and to avoid this state of affairs the lake should 
bo held at the opening of the drj- season not at 



107 but at 109. The indications are, therefore, 
that the minimum range within which the lake 
can be controlled, having regard to evaporation 
only, is not l(?ss than four feet. 

Spillway Capacity. 

As nearly as can be determined by the obser- 
vations at hand, the maximum rise in the lake 
in 4.^ hours, if all had been held, was about .44 
of a foot. This indicates an inflow of about 
220,000 cubic feet per second. It would be 
neithcn* necessarv' nor economical to provide a 
spillway of this capacity, but would be far 
cheaper to allow temporary storage for such 
floods as this and others somewhat greater. 
Five-tenths of a foot is therefore allowed, \vhich 
is to be subtracted at the outset from the limit 
assigned for the control of the lake in any- 
given season. 

If the limits set be 105 minimum and 110 
maximum, and w-e deduct two feet from the 
lower limit as being a permanent reserve against 
an unusually dry year, and .5 foot from the 
upper limit for sudden inflow as herein de- 
scribed, we have as a spillway problem the con- 
trol of the inflow of the year of maximum rain- 
fall between the limits of 2.5 feet 

In attempting to deduce the necessary ca- 
pacity of a spillway to discharge the surplus 
water flowing into Lake Nicaragua, we have 
recourse to the comparison of the observations 
taken in 1898 with the long record of rainfall 
at Rivas. This record indicates that the max- 
imum annual precipitation in 19 years was for 
the year 1897, 123.43 inches. Comparing the 
record at the same plac^ for 1S9S, up to October 
31, with that for the corresponding months 
of 1897 we find that the precipitation for 1808 
is 83 per cent of that for 1897. In other words, 
the precipitation for 1898 should be increased 



NICARAGUA CANAL COMMISSION 



J 


AHUABY 




F 


BR 


JARY 




h 




■10 








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IL 








MAY 




JU 


NC 




JULY 




AUG 










































































































i 
























































< 

L 


^A 


> 


^ 


'^A 




\ 






































J 


/ 
/ 


// 


3 

IL 

o 












\ 
> 


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\ 


\ 


Y 


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/ 


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A 


\ 


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\ 


\ 


V 


\ 


1 


y 


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1 
1 












loi — L 










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H 


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■ ^ 




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■^ 


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1 


1 


1 


1 


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ilki 


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FEenUARY 



APRIU MAY JUNE JULY AUG 

DIAGRAM OF THE DAILY MEAN ELEVATION OF LAKE NICi 



APPENDIX 3, PLATE XVIII 

SEPTEMBER OCTOBCR NOVEMBER DCCEMBCR JANUARY FEBRUARY MAUCH APRIL 



— — . — . y ? — 1 — 1 — r— ¥-¥ — r-f- Tj-i — 1 y f T f — . y ? f ? — i— f~HH — ; -f i ? i , •? y-y-y 

1* S3-- IB )8 


.1 \\ 








lUlililULJJiLlLii.L. iJju^j^..LLiLi.i., J _ ,,_ 



SEPTEMBER OCTOBER NOVEMBER DECEMBER 

COMPARED WITH THE SYNCHRONOUS RAINFALL IN ITS BASIN. 



FEBRUARY MARCH 



APPENDIX III.— HYDROGRAPHIC REPORT 



295 



21 per cent, to be equal to that of the maximum 
in the record. AVhile we have no conclusive 
data upon which to estimate the percentage of 
run-off to rainfall in the basin of Lake Nica- 
ragua, yet it is well established as a general rule 
that in any given basin the greater the rainfall 
in a given time, the greater the percentage of 
run-off, so that if the rainfall were increased 
21 per cent, the run-off should be increased 
somewhat more, say 25 per cent. Now the 
run-off for the basin of Lake Nicaragua has been 
measured for 1898 up to the 27th day of Octo- 
ber. From June 15 to October 27 the lake 
received in excess of evaporation 13,450,000 
acre-feet of water, 5,450,000 of which were dis- 
charged through the San Juan river and 8,000,- 
000 were stored in the lake. This is equivalent 
to a mean inflow in excess of evaporation of 
50,700 cubic feet per second. Lf this inflow be 
increased by 25 per cent, to make it correspond 
with that of the hypothetical maximum year we 
have a mean influx of 63,375 cubic feet per sec- 
ond, which if continued for 183 days would have 
contributed a total of 23,005,400 acre-feet. If 
we limit the rise in the lake during this time 
to 2.5 feet we find the required spillway capacity 
to be 49,680 cubic feet per second. It seems, 
therefore, that a spillway capacity of 50,000 
cubic feet per second would have kept the lake 
within the desired limit during the year of max- 
imum rainfall as above computed. Under the 
same conditions, the rise could have been limited 
to 1.5 by a spillway of 56,000 cubic feet ca- 
pacity. 

The question now arises whether there is any 
reason to believe that rainfall during the maxi- 
mum year is likely to be so concentrated within 
a short period as to be greater than the capacity 
of our spillway to care for. Our only recourse 
is to the rainfall observations during the maxi- 



mum year. Here we find that during October, 
1897, 33.85 inches of rain fell, which is more 
than one-fourth of the total for that vear and 
exceeds by nearly 50 per cent, the precipitation 
for any other one month in the entire record 
of 19 years. Such a rainfall coming near the 
close of the rainy season when Lake Managua 
and tributarv streams are full and the ground is 
generally saturated, might, it seems, well be 
taken as the most unfavorable condition likelv to 
occur. An examination, therefore, of the re- 
sults which would have followed such a year as 
1897, with our estimated spillway capacity un- 
der perfect control, should indicate whether or 
not our works or property on the lake would 
have been damaged in that maximum year. 

The inflow to Lake Nicaragua between May 
15 and September 30 was 12,525,000 acre-feet 
in excess of evaporation. The rainfall during' 
these months was exceeded by that in the corre- 
sponding months of 1897 by about 10 per cent. 
The coiTcsponding run-off for 1897 would, 
therefore, have exceeded that for 1898 by a 
somewhat larger percentage, say 12 per cent. 
This would give an inflow for 1897 up to the 
30th of September of 14,028,000 acre-feet. 
Tliis is equivalent to a mean inflow of about 
51,000 cubic feet per second. A spillway of 
50,000 cubic feet per second discharging all the 
time would have confined the rise to .28 foot; 
then we still have a limit of 2.2 feet which the 
lake can rise during October before reaching the 
danger line. During May and June, 1898, 
35.12 inches of rain fell at Rivas and the inflow 
was about 4,000,000 acre-feet, exclusive of evap- 
oration. The rainfall during October, 1897, 
was 33,85 inches, or 1.27 less than during May 
and June, 1898. The run-off, however, would 
have been greater owing to the fact that the rain 
for May and June fell upon dry land and was 



296 



NICARAGUA CANAL COMMISSION 



largely absorbed, and Lake ^Managua and its 
drainage area contributed practically nothing to 
Lake Nicaragua during that time, while in 1898 
Lake ^Managua contributed during October a 
total of nearly 250,000 acre-feet, and the same 
influence would have operated in a less degree 
to increase the inflow from all tributaries of 
Lake Nicaragua during October over what it 
was during ^fay and June. Making due allow- 
ance for th(^ lesser rainfall in October and the 
greater proportional run-off, it would seem that 
to allow ten per cent, increased inflow over that 
for May and June, 1898, would be sufticient, 
and this would just bring the hike to 101). 5; and 
for the spillway capacity to prevent further rise 
we must assume the inflow to be no greater than 
50,000 cubic feet per second. As the Kivas 
rainfall for November, 1897, is but 5.15 inches, 
and exceeds the mean for that month bv about 
14 per cent., this seems to be a safe assumption. 
It will be observed, however, that this pre- 
supposes the opening of the spillway to its full 
capacity throughout the seas<jn, allowing the lake 
to rise less than .3 foot. But it must be borne 

in mind that the heavv rainfall for October could 

* 

not be predicted for any specific year, and as 
it is necessary to hold the lake at 109 at the 
end of the rainy season, as above indicated, it 
would not be safe to penuit the level to remain 
so low at the end of September, unless the rain- 
fall after that date can l>e depended upon to 
supply the necessary storage, namely, 1.7 feet. 
The snialle>^t rainfall in tin* record for October, 
November and December, in any one year, is 
that for 1895, when 11.21 inches fell, which it 
seems l)y comparison with this year's record 
would have raised tlie lake about a fo<:)t. The 
run-off due to previous rainfall would have been 
considerable, at least .2 foot, so that we would 
lack .5 foi>t of having the desired reserve storage. 



and it would be necessarj' to begin October with 
a lake level not lower than 107.8. The year of 
heavy rainfall according to the above estimates, 
would have carried the level to just 110, the 
extreme limit. 

Tn view of the fact that such extreme condi- 
tions as we have been assuming occur very sel- 
dom, and that the lake has risen in past years 
above 110 from natural causes, an error of judg- 
ment in the manipulation of the spillway which 
should allow the surface to rise a few inches 
above the limit set, could not be regarded as 
doing more than repeating the results of nature. 

Value ok the Estimates. 

The data upon which the above estimates are 
necessarily made are meager, and it becomes im- 
portant to form an idea as definite as may be re- 
garding their value. 

The extensive use which is made of the record 
of Rivas rainfall involves to an important de- 
gree the question of the probable integrity and 
reliabilitv of that record. The obser\'ations were 
taken bv, or under the authoritv of, Dr. Earl 
Flint, a thoroughly competent observer, and the 
record in itself contains no indication of being 
faulty. AVhile the range between maximum 
and minimum rainfall might appear to be large, 
it is not so large in percentage as in many records 
taken in the United States. AVithout further 
evidence pro or con the record might be consid- 
ered good, at least as good as rainfall records 
usually are. A comparison of the records at 

Rivas and at ilasiiva and Granada shown in 

t. 

diagram (Fig. 8) exhibits a striking parallelism 
with no discrepancies greater than might be ex- 
pected from stations located relatively as these 
are. The somewhat sui-prising fact that the 
rainfall obser\'ed at Kivas for 1898 is much 
greater than that at any of the stations main- 



NICARAGUA CANAL COMMISSION 









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DIAGRAM OF THE DAILY MEAN INFLOW TO LAKE NICARAGUA COMPARED WITH THE MEAN RAINFALL II 

THE DOTTED LINE INDICA 



TEMBER OCTOBER NOVEMBER DECEMBER JANUAI 



APPENDIX 3, PLATE XtX 
ARY MARCH 



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M. THE CONTINUOUS LINE INDICATES THE ELEVATION OF THE LAKE IF ALL WATER HAD BEEN HELD. 
ACCUMULATED RAINFALL. 



APPENDIX III.— HTDROGRAPHIC REPORT 



297 



tained by this Commission in the vicinity, also 
appears in the diagram, which shows that it is 
also greater than that taken at Masaya and Gra- 
nada, in nearly every year of the record. The 
inference, therefore, is that from natural causes 
the rainfall at liivaa actually is greater than in 
most other parts of the basin, due probably to 
local meteorologic conditions, but these local 
conditions do not vitiate the record as a means 



assumption that the Rivas rainfall bears a fixed 
rotation to that of the entire basin, the results 
could not be relied upon within narrow limits. 
The problem presented, however, is of such a 
character that the conclusion may be relied upon 
within very much narrower limits than the prob- 
able error of individual estimates. The esti- 
mates for spillway depend upon the assumption 
that rhe relation of the rainfall for 1898, for 



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. Comparative rainfall at Rivas and Masara. 



of comparison, because, as the diagram indicates, 
they still bear a reasonably uniform relation to 
the stations of lesser rainfall. It would appear, 
therefore, from all the evidence at hanil, that 
the Eivas record may be used as safely and 
within as wide limits as any rainfall record can 
be. It must he admitted, however, that fluc- 
tuations of rainfall, local and spasmodic, occur 
in all parts of the world, and if our estimates 
depended absolutely upon the reliability of the 



which we have a measured nui-off, and the rain- 
fall for l!^9T is tlic relation indicated by the 
Rivas record. If from temporary causes the 
Rivas record for 1898 is too large, then its as- 
sumed relation to the maximum year is too large, 
and we will have greater floods than those esti- 
mated and will need either a wider limit of 
fluctuation in the lake or greater capacity of 
spillway. But under the same supposition we 
have also estimated too small a rainfall for the 



298 



NICARAGUA CANAL COMMISSION 



dry years and the provision for storage against 
such years is estimated too large. Here, then, 
we have two errors which tend to counterbalance 
each other. Conversely, if from temporary 
causes the rainfall at Rivas was abnormallv small, 
we have the reverse result in both cases, but still 
the two errors tend to counterbalance each other, 
and it is believed that the facts known are suf- 
ficient to indicate with all necessary accuracy 
the limits within which the lake can be con- 
trolled, and the spillway capacity necessary for 
the purpose. 

The conclusion, therefore, is that the lake can 
probably be controlled within limits of five feet, 
if an adjustable spillway be provided with a ca- 
pacity of 50,000 cubic feet per second. The 
excavation required, however, is such that if 
the limit could be reduced to four feet, it would 
save one foot of excavation throughout a large 
part of the summit level, and reduce the cost 
more than two million dollars. 

If a range of fluctuation be allowed greater 
than five feet, the spillway capacity may be re- 
duced and the supply for dry seasons will be 
made more se<jure. 

Lake Managua. 

It has been suggested that Lake Managua 
might be utilized as a reservoir in which to store 
a portion of the water required, at a less cost 
than it could be stored in Lake Nicaragua. This 
lake lies to the north and west of Lake Nica- 
ragua, has a surface of about 438 square miles 
and a tributary drainage area of about 2500 
square miles. Its surplus waters are discharged 
into Lake Nicaragua by way of Tipitapa river. 
One mile below the point where this river leaves 
Lake Managua, it falls over a cataract descend- 
ing about 13 feet in a horizontal distance of 500 
fet^t. It is estimated that a dam might be con- 



structed at this point, and the waters of Lake 
-Managua raised about eight feet above the sur- 
face of the rock at the falls without serious 
damage to property around the margin of the 
lake. An outlet tunnel or cut might be provided 
to draw off the water to the level of the river 
below the falls. All these works would be in- 
expensive and a storage capacity would thus be 
secured for a depth of 20 feet over the entire sur- 
face of Lake Managua, which, if drawn off in 
its entirety would raise Lake Nicaragua about 
three feet. To further test the merit of this 
proposition, measurements of rainfall and out- 
flow were made at Tipitapa and a station was 
established on Eio Viejo about 50 miles north 
of the lake for the measurement of rainfall and 
of the discharge of the principal tributary to 
Lake Managua, Eio Viejo; also to obtain data 
regarding the regimen and discharge of Rio 
Nueva. 

The cost of utilizing Lake ^Fanagua as a stor- 
age reservoir for the summit level would be 
roughly al>out as follows: 

Cost of overflow ogee dam at Tipitapa 

1600 yds. concrete at $15 $24,000 

Excavation of outlet 20,000 

Gates and gatehouse 6,000 ' 

$50,000 
Diversion of Nueva: 

750,000 cubic yards earth at 20 cents. .$150,000 

Dam 100,000 

• ^"^■~^* 

Total $300,000 

So far as works are concerned, this project is 
practicable and cheap, but the water supply is 
doubtful. It is known that entire vears some- 
times occur in which there is no outflow from the 
lake, but on the other hand, the fact that water 
does often flow out proves beyond question that 



APPENDIX III.— HYDROGRAPHIC REPORT 



299 



in the long run, the inflow exceeds the evapora- conclude that this could be done. The storage 

tion and seepage from the lake. of water in Lake Managua would also assist in 

The discharge from Lake Managua has been the control of the surplus waters by reducing 

measured for the year 1898, excepting for the the area of the watershed to be provided for. 
months of January and December. Estimatr 

ing the discharge for these two months, we have Sediment Observations. 

a total outflow for the year of something over Any proposition for a ship canal which in- 

1,100,000 acre-feet, or enough to raise Lake volves the use of the San Juan river below the 

Nicaragua .55 foot, or to raise Lake ilanagua mouth of the San Carlos requires for its intelli- 

3.8 feet, if all had been held. gent consideration some idea of the quantity of 

Had Rio Xueva been diverted into Lake Man- sediment carried by that stream, and if the San 
agiia during this year, as suggested on page 208, Juan is to be used below the mouth of the Sara- 
it would have contributed about 200,000 acre- piqui the sediment earned by that stream be- 
feet more, sufficient in all to have raised Lake comes also an important factor. To determine 
Managua about 4^ feet in excess of evaporation, these quantities samples of water were taken 
or enough to raise Lake Nicaragua eight inches, daily, allowed to settle, and the sediment meas- 
Though the precipitation and nm-off of 1898 ured. The samples were taken at not less than 
were probably above the average, still it would a dozen places in the river, the water taken ag- 
be fair to expect one or more such years in each gregating several gallons, and representing ap- 
interval between the years of drought, and to proximately the average of the various parts of 
assimie that the inflow to Lake Managua during the current. The samples were thoroughly 
the other years would on an average be equal to mixed, and one sample of 100 cubic centimeters 

SEDIMENT BY WATER-SAMPLES FROM SAN CARLOS RIVER, 1898. 

Month. Mud. Solid Matter. Remarks. 

Cubic >Tird8. Cubic yards. 

June 705,000 141,000 5 cu. yds. mud are assumed equ