THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA DAVIS 'm I STATE OF CALIFORNIA DEPARTMENT OF PUBLIC WORKS DIVISION OF WATER RESOURCES CULBERT L. OLSON, Governor FRANK W. CLARK. Director of Public Works EDWARD HYATT, State Engineer BULLETIN No. 50 USE OF WATER BY NATIVE VEGETATION 1942 TABLE OF CONTENTS Page LETTER OF TRANSMITTAL x ACKNOVLEDGriENT xi ORGANIZATION, STATE DEPARTMENT OF PUBLIC WORKS xii ORGANIZATION, UNITED STATES DEPARTMENT 07 AGRICULTURE xiii INTRODUCTION CHAPTER 1 CHAPTER 2 RELATION OF PLANT COMMUNITIES TO MOISTURE SUPPLY 5 Drought-resistant plants 7 Indicator value of ground-water plants 10 Marsh vegetation 14 CHAPTER 3 METHODS OF DETERMINING CONSUMPTIVE USE l6 Tank measurements l8 The Mariotte tank 19 Float valves 22 Factors affecting the use of water by vegetation grown in tanks 23 Soil-moisture studies 28 Stream-flow studies 30 Water-table fluctuations 3^ CHAPTER 4 im^STIGATIONS OP THE DIVISION OF IRRIGATION 59 Basis and scope of studies 39 Santa Ana Valley, California 39 Saltgrass 41 Wire rush 43 Willow 43 Bermuda grass 46 Tules and cattails 48 Brush ^5 Grass and weeds 59 Mojave Valley, California 39 Tules 39 Adjustment factors for large areas 62 Temescal Creek, California 66 Canyon-bottom vegetation 66 Supporting tank data 70 Probable limits to the losses along stream channels 71 Coldwater Canyon, California 74 Canyon-bottom vegetation 74 Stream losses by evaporation and transpiration 79 Studies in the Sacramento-San Joaquin Delta, California 85 Tules and cattails 83 ueeds 85 Northern Colorado studies 88 iii CHAPTER 4 (Continued) Pace Studies of Upper Rio Grande Basin 09 San Luis Valley, Colorado 89 Tules and grasses 89 Middle Rio Grande Valley, New Mexico 91 Cattails 94 Sedge 94 Saltgrass 95 Willows 95 Mesilla Valley, New Mexico 97 Cattails 97 Saltgrass 98 CHAPTER 5 OTHER INVESTIGATIONS 101 South-Central Oregon 101 Marsh grass IO5 Native meadow 105 Sugar grass IO6 Uire rush IO6 Mud Lake, Idaho IO6 Tules 106 Escalante Valley, Utah IO8 Saltgrass IO9 Greasewood 110 San Luis Valley, Colorado 110 Saltgrass 110 Northeastern Colorado 114 Weeds 114 Middle Rio Grande Valley, New Mexico II5 Saltgrass II5 Tules 117 Owens Valley, California II9 Closed basins II9 Saltgrass 120 Estimated water supplies 120 Santa Ana River Valley, California 122 River-bottom vegetation 122 Smmnaries of consumptive use data 125 CHAJ'TER 6 RELATION BETWEEN CONSUMPTIVE USE AND DEPTH TO WATER TABLE 129 CHAPTER 7 RELATION OF CONSUMPTIVE USE TO EVAPORATION 132 CHAPTER 8 SUMMARY 143 LITERATURE CITED 147 OTHER PUBLICATIONS 152 PUBLICATIONS OF THE DIVISION OF WATER RESOURCES I56 iv LIST OF TABLES Table Page 1. Relation of temperature and precipitation to some prevailing types of southwestern desert vegetation -- 9 2. Meteorological data at Santa Ana station, Santa Ana, Calif., 1929-32 40 3. Consumptive use of water by saltgrass in tanks at Santa Ana, Calif., 1929-32 kk U. Consumptive use of water by wire rush in tank at Santa Ana, Calif., 1930-32 45 5. Consiimptive use of water by willows in tank at Santa Ana, Calif., 1930-31 46 6. Meteorological data at San Bernardino station, San Ber- nardino, Calif., 1929-32 49 7. Consumptive use of water by Bermuda grass in tanks at San Bernardino, Calif., 1929-31 50 8. Consumptive use of water by tules and cattails in tanks in southern California, 1929-32 52 9. Consumptive use of water by native brush in southern California, 1927-30 57 10. Consumptive use of water by native grass and weeds in southern California, 1927-30 58 11. Consumptive use of water by tules in tanks, evaporation, and meteorological data at Victorville, Calif., 1931 and 1932 61 12. Estimated consumptive use of water by tules in swamps in southern California, based on tank experiments 63 13. Estimated annual consumptive use of water by native vegetation under field conditions in southern California 65 14. Consumptive use of water by moist-land vegetation as indicated by stream losses in Temescal Creek, Calif., 1929 68 15. Consumptive use of water by swamp vegetation in tanks at Temescal Creek and at Ontario, Calif., 1929-30 70 16. Vegetative classification in Coldwater Canyon near San Bernardino, Calif. 76 17. Consumptive use of water by canyon-bottom vegetation as indicated by stream losses in Coldwater Canyon near San Bernardino, Calif., 1931-32 81 18. Consumptive use of water by canyon-bottom vegetation as indicated by stream losses in Coldwater Canyon near San Bernardino, Calif., 1932 82 19. Consumptive use of water by cattails and tules in ex- posed tanks at Clarksburg, Calif., 1929-30 84 20. Consumptive use of water by cattails and tules in tanks set in swamp on King Island, Sacramento -San Joaquin Delta, Calif., 1930-32 86 21. Consumptive use of water by weeds grown in tanks at King Island, Calif., 1932-33 87 22. Consumptive use of water by grasses, aquatic plants, and weeds at Fort Collins, Colo., 1929-32 88 Table Page 23. Consiimptive use of water by tules and native meadow grass in tanks, evaporation, and meteorological data at Parma station, San Luis Valley, Colo., 1936 92 24. Consumptive use of water by cattails, sedge, saltgrass, and willow in tanks, evaporation and meteorological data at Isleta, Middle Rio Grande Valley, N. Mex. , 1936-37 93 25. Consumptive use of water by cattails and saltgrass in tanks, and meteorological data, at Mesilla Dam, in Mesilla Valley, N. Mex., 1936-37 99 26. Consumptive use of water by marsh grass in the Chev/aucan Valley, Greg. 102 27. Consumptive use of water by natural meadow in Chewaucan and Harney Valleys, Greg. 103 28. Consumptive use of water by sugar grass in the Chewaucan Valley and the Klamath Basin, Greg. 104 29. Consumptive use of water by v/ire rush grown in the Klamath Basin, Greg. 104 30. Consumptive use of water by tules in tanks, and meteoro- logical data at Mud Lake, Idaho, 1921-23 1G7 31. Consumptive use of water by saltgrass and greasewood in tanks in Escalante Valley, Utah, 1926-27 111 32. Consumptive use of water by saltgrass in tanks at Garnett, San Luis Valley, Colo., 1927, 1928, 193G, and 1931 113 33. "Weight of water absorbed by weeds during the growth period related to weight of dry matter harvested, Akron, Colo., 1911-17. After Shantz and Piemeisel -- II6 34. Consumptive use of water by saltgrass and tules in tanks, evaporation, and meteorological data at Los Griegos, near Albuquerque, N. Mex., 1926-28 118 35. Consumptive use of water by saltgrass in tanks in Gwens Valley, Calif., 1911 121 36. Estimated consumptive use of water by saltgrass and alkali lands in the Gwens Valley, Calif. , 19II. (Based upon tank investigations.) 122 37- Classification of vegetative cover, Santa Ana River, Calif. 123 38. Estimated natural losses between Riverside Narrows and Prado gaging station, Santa Ana River, Calif., I93G-3I and 1931-32 124 39. Mean annual or seasonal consumptive use of water by saltgrass grown in tanks, and pertinent meteorological data 126 40. Mean annual or seasonal consumptive use of water by tules and cattails growing in water in tanks, and pertinent meteorological data 127 41. Mean annual or seasonal cons\imptive use of water by some native vegetation, and pertinent meteorological data 128 42. Relation of consumptive use of water by tules and cat- tails in their natural environment to evaporation from an adjacent Weather Bureau pan 134 Table Page 43. Relation of consumptive use of water by saltgrass in tanks to evaporation from an adjacent Weather Bureau pan 136 44. Relation of consumptive use of water by Bermuda grass, wire rush, willow, sedge, native meadow grass, and greasewood, in tanks, to evaporation from an adja- cent Weather Bureau pan 138 LIST OF PLATES Plate Page I. A. Screw jack working against anchored cable, forcing soil tank 6 feet into the ground to capture un- disturbed soil 21+ B. Soil sampling equipment: compressor unit (on truck), pneumatic driving hammer (in operator's hands), ordinary soil tube hammer (on ground) and soil tube jack 24 II. A. Willows 6 to 7 feet high growing in 6-foot diameter tank at Santa Ana, Calif. 47 B. Alders in Coldwater Canyon between middle and lower controls 47 III. A. Flow recorder installation in Coldwater Canyon: above, 7-d.ay chart on clock-driven drum; below, spiral cam which permits a direct record on the chart in units of discharge 78 B. Site of experimental station at Isleta, N. Mex. , showing type of surroiinding vegetation. Consump- tive use of water by sedge was determined in the small area fenced at the extreme right 78 IV. A. Cattails in tank surrounded by similar growth at Isleta, Middle Rio Grande Valley, N. Mex. 96 B. Dense growth of water-loving shrubs and trees along the Santa Ana River, near Prado, Calif. Studies have shown this vegetation uses not less than 50 acre-inches per acre of water 96 V. A. Dense growth of bank vegetfation using water from an irrigation canal in Imperial Valley, Calif. 139 B. Wild sunflower plant in California. Sunflowers are remarkably thrifty for long periods in very dry places 139 C. Mesquite in the Coachella Valley, Calif., illustrat- ing size of bush. This is found in areas where ground water is within reach of root systems. The size is an indication of depth to water table; high ground water results in tall, dense growth-- 139 VI. A. Tall, dense Cottonwood and willow growth along dry bed of San Luis Rey River, San Diego County, Calif. Much of the surface flow sinks into the gravels and is absorbed by vegetation 140 B. Typical swamp area. Tules used large amoimts of t water 140 C. Tules 6 to 8 feet high, growing in open water 140 VII. A. Creosote bush and other vegetation in the desert illustrating the habit of wide spacing between plants owing to the scarcity of moisture in the soil 141 B. Eucalyptus grove on eroded bank, illustrating depth of rainfall penetration at about 7 feet as indi- cated by dark shadowy line below the light color- ed gravel strata. Note tree roots extending through the gravel into finer soil 141 VIII. A. Chaparral, illustrating extensive root system ex- posed by flood 142 B. Johnson grass (Sorghum halepense) growing in young orange grove, Calif., where soil was unusually moist 142 viii LIST OF FIGURES Figure Page 1. Marietta tank connected to soil tank to maintain a constant water level in the soil and supply water evaporated or transpired. Santa Ana station, 1929-32 20 2. Diurnal fluctuations in southern California streams (after Troxell) 32 3. Combination flume for measurement of water at both high and low stages 34 4. Representative ground-water curve, showing effect of the daily cycle of transpiration by overlying vege- tation (after Troxell) 37 5. Plan of evaporation station near Santa Ana, Calif. 42 6. Hourly rate of use of water by tules, evaporation from stajidard Weather Bureau pan, and air and water tem- peratures, at Prado station 53 7. Plan of Victorville station 60 8. Stream flow, consumptive use by moist-land vegetation, and comparison of rate of consumptive use by tank vegetation with air temperatures at Temescal Creek - 69 9. Flow at middle Coldwater Canyon control 79 10. Plan of Parma station, San Luis Valley, Colo. 90 11. Plan of Isleta station, N. Mex. , 1936 94 12. Sketch of water supply lay-out at Isleta station 95 13. Plan of Mesilla Dam station 98 14. Examples of recorder charts showing ground-water fluc- tuations due to daily transpiration losses by various species of native vegetation (after White) - 109 15. Relation of consumptive use of water by saltgrass in tanks to depth to water table 129 16. Comparison of consumptive use of water by tules in swamps and evaporation from a Weather Bureau pan 133 17. Comparison of consumptive use of water by saltgrass where approximate depth to ground water is 24 inches, and evaporation from a Weather Bureau pan 137 iz LETTER OF TRANSWITTAl Mr. Edward Hyatt, State Engineer, Sacramento, California. Dear Sir: Transmitted herewith for publication is a cooperative report "Use of Water by Native Vegetation," The report, prepared by Arthur A. Young and Harry F. Blaney, is a comprehensive presentation of available research data dealing with the consumptive use of water by various non- crop plants native to California and the Southwest in general. Its analyses are of economic and practical importance in shap- ing the effective conservation and use of water in this wide region. The greater part of the Investigations on which the report is largely based was supported, and the report was pre- pared, under cooperative agreement between the Division of Vater Resources of the California State Department of Public Works and the Division of Irrigation of the Soil Conservation Service, United States Department of Agriculture. Respectfully submitted, Chief, Division of Irrigation, Soil Conservation Service, United States Department of Agriculture Berkeley, California, July 31, 1942. ACKMO\JLEDGMENT The authors acknov/ledge the assistance rendered by members of the Division of Irrigation of the Soil Conser- vation Service, United States Department of Agriculture, especially Paul A. Ewing, Irrigation Economist, who edited the manuscript. The advice and assistance of Harold ConJiling, Deputy State Engineer, is recognized. Credit for specific data is indicated at appropriate places throughout the report to individual investigators or agencies, the results of whose investi^tions were pertinent to the authors' analyses. li ORGANIZATION STATE DEPARTMENT OF PUBLIC WORKS DIVISION OF WATER RESOURCES Frank W. Clark Director of Public Works Edward Hyatt State Engineer Results of cooperative research as to evapo-transpiration losses in California summarized herein v/ere a part of general inves- gations on water supply and utilization conducted by the State of California under the direct supervision of Harold Conkling Deputy State Engineer xii ORGANIZATION UNITED STATES DEPARTMENT OF AGRICULTURE SOIL CONSERVATION SERVICE DIVISION OF IRRIGATION Cooperating in Studies on Use of Vater in Irrigation H. H. Bennett Chief of Service M. L. Nichols Assistant Chief of Service, Research W. W. McLaughlin Chief of Division This report was prepared by Arthur A. Young, Associate Irrigation Engineer and Harry F. Blaney, Irrigation Engineer xiii USE OF WATER BY NATIVE VEGETATION By Arthur A. Young — ' and -, / Harry F. Blaney — ^ CHAPTER 1 INTRODUCTION The purpose of this bulletin is to bring together con- veniently in a single report the results of studies of consumptive use of water by a number of species of native vegetation, as determined by the Division of Irrigation for various western climatic conditions, and some of the results of similar investi- gations by other agencies. Such studies have been carried on for many years. It is not the intention of the authors to minimize the value of vegetation as its growth on mountain watersheds, as elsewhere, constitutes a very necessary protection to the soil. Water consumed by most native vegetation is used beneficially and is not considered as wasted. The moisture requirements of the natural ground cover are satisfied before water becomes available for other purposes. In considering the water supply of a region, therefore, the difference between precipitation and run-off plus deep percolation constitutes the consumptive use by the native growth. It is for those concerned with the natural resources of soil and water that these data on use of water by native vegeta- tion are presented. The usefulness of such data are recognized by administra- tors and investigators in regions where water rights are in dis- pute locally, or where interstate water supply and water use are not in balance. Valley or basin investigations to determine a 17 Associate Irrigation Engineer and Irrigation Engineer, respectively, Division of Irrigation, Soil Conservation Service, U. S. Department of Agriculture. proper division of the supply between contending uses need first of all a knowledge of the amounts consumed by crops and native vegetation; without such data there is little likelihood that re- sults of investigations can be final. Moreover, in planning new irrigation projects, consideration must often be given to differ- ences in amounts of water used by irrigated crops and those used by the native vegetation replaced by the crops. These differences largely determine the extent of the available water supply and show how much must be obtained from other sources. By "Use of Water," the title of this report, "consumptive use" is principally intended. Consumptive use, sometimes called "evapo-transpiration, " is the sum of the volumes of water used by the vegetative growth of a given area in transpiration or building of plant tissue and that evaporated from adjacent soil, snow, or intercepted precipitation on the area in any specified time. If the unit of time is small, such as a day or week, the consumptive use may be expressed in acre-inches per acre or depth in inches; whereas, if the unit of time is large, such as a crop-growing season or a 12-month year, the consumptive use may be expressed in acre-feet or depth in feet. Such terms as "irrigation require- ment" and "water requirement," sometimes used to designate, respectively, the quantity of irrigation water applied to crops, or the total quantity including rainfall required for their normal and profitable production under field conditions, include some unavoidable losses by deep percolation. Such losses are not in- cluded in the definition of consumptive use, which designates only the \inrecoverable portion of the water supply. Investigations by which consumptive use is ascertained do not involve the determination of amounts of water "evaporated from adjacent soil, snow, or intercepted precipitation on the -area," since such evaporation is difficult -- often impossible -- to ascertain and of no particular interest as a separate element in the total unrecoverable portion of the water supply. On the other hand, the relation of consumptive use to evaporation from water in a Weather Bureau pan is of some significance, as both are influ- enced by the same factors of temperature, wind, and hiimidity; and whereas consumptive use determinations are available to represent a strictly limited number of localities, evaporation records are available for many and can be established quite readily for more. When estimates of consumptive use are needed for localities where determinations have not been made, available evaporation results are therefore useful if both evaporation records and consumptive use results are also available from other areas having comparable characteristics. A discussion of such opportunities is found in the chapter headed "Relation of Cons\imptive Use to Evaporation." Extensive work in regard to native vegetation has been carried on hy the Division of Irrigation, United States Depart- ment of Agriculture, in cooperation with the Division of Water Resources, Department of Public Works, State of California, and most of the results of the investigations have been published in previous reports of the latter office. In this bulletin these previously published data are assembled and analyzed in associa- tion with the results of similar studies by the Division of Irri- gation — ' in other sections of the West. These studies specifi- cally included those undertaken by the Division of Irrigation in the Upper Rio Grande Basin in cooperation with the States of Colorado, New Mexico, and Texas under an agreement with the National Resources Committee. In Colorado, the Division cooper- ated with the Colorado Agricultural Experiment Station with regard to grasses, sedge, sweetclover, tules, sunflowers, and weeds. Likewise , it cooperated with the Oregon Agricultural Experiment Station in determination of water consumed by grasses and native meadow lands in south-central Oregon. The cooperative field work in southern California had been carried on under the general supervision of Harry F. Blaney, by 17 The Soil Conservation Service on July 1, 1939 took over most of the irrigation investigations formerly conducted by the Bureau of Agricultural Engineering. Colin A. Taylor and Arthur A. Young, assisted by Dean W. Blood- good, Dean C. Muckel , and Harry G. Nickle. In the Sacramento- San Joaquin Delta, field work was under the supervision of the late 0. V. P. Stout, assisted by Lloyd N. Brown. Obviously, it has been possible to study only a few of the many species native to the West, partly on account of the diffi- culties of transplanting or growing the larger types in tanks. There are, however, a number of western moist-land species about which a great deal has been learned, especially with regard to their water habits and the quantity of water each will consume under specified conditions. Plants growing in unusually moist soil consume annually more than an average amount of water. In desert areas, on the other hand, typical vegetation is adapted to an extreme economy in its use of water. Between these two types are many species that consume variable quantities depending upon the supply available. It is apparent that there is seldom a definite water requirement for most native vegetation. CHAPTER 2 RELATION OF PLANT GOI'IMUNITIES TO MOISTURE SUPPLY The relation of plant communities to moisture supply is one of the outstanding characteristics of the growth of natural vegetation. While individual species are largely restricted to favorable physical environments, the principal condition that governs the distribution of vegetative groups is the amount of available moisture. Each species responds to individual water conditions for its most favorable growth and its widest distri- bution. As expressed by Shantz (25), "One of the most success- ful correlations yet attempted is that between plant associations and the water content of the soil. This correlation has been accepted and modified by leading ecologists and has proved one of the most useful generalizations in the study of vegetation.'' Temperatures, moisture, and the chemical and physical properties of the soil are contributing factors in the distribu- tion of natural vegetation. However, the quantity of water avail- able for plant use and the effect of plant gro'/rth on supply, are of great interest to the hydrologist. Soil texture and salinity, as well as moisture content, have been correlated with distribu- tion of native growth as indicators of the adaptability of un- cropped land to agricultural possibilities; but to those interest- ed in water supplies, rather than soil, the consumptive use of water by natural vegetation and the residual water available for recovery are of greater economic importance than other character- istics. Bowman (6) has said: "It is found that each species of plant requires its own specific water supply for most favorable condition of growth and that the quantity of water in the soil has a greater influence than any other condition on the distribu- tion of plant species." In the absence of ground water, then, the 1/ Numbers in parentheses refer to Literature Cited, p. 147. distribution of the great regional types of desert vegetation is determined by the limited amount of precipitation which falls in a given region. The effect of environment on the distribution of plants is well recognized, those best adapted to resist the unfavorable con- ditions of a region being the most successful in surviving. As stated by Weaver (37) "The natural vegetation, for many centuries, has been sorted out by climate as well as by soil in the process of development. The various species of plants have usually in- habited a region so long that they are now quite definitely dis- tributed with relation to the environmental complex, species well adapted to a given environment now occurring in abundance. Thus, the growth of native vegetation becomes a measure of the effects of all the conditions which are favorable or unfavorable for plant production." This is particularly true in arid regions where high rates of evaporation and transpiration, and a very limited water supply, have reduced vegetation to a veritable struggle for exis- tence . Again, according to Warming (36), "No other influence ex- presses its mark to such a degree upon the internal and external structures of the plant as does the amount of water present in the air and soil." It appears, then, that authorities are in accord on the soil-moisture plant distribution relation. Contributing factors, as temperature, altitude, humidity, and evaporation also must be considered, but these are so interrelated with water supply that the effects are not always discernible. Natural vegetation grows under moisture conditions that are always changing. Plants that do not subsist on ground water but depend upon moisture held by the soil particles may have an abun- dant supply at one time and suffer a scarcity at another. Ground water fluctuates and roots in contact with it are alternately wet and dry. Soil moisture is dependent upon precipitation, but evap- oration, transpiration, percolation, and run-off cause its uneven distribution in the soil. In arid areas moisture is retained in the upper soil hori- zon, and the vegetation is confined to those species which are adapted to extreme economy of water. In areas of greater precipi- tation, deeper penetration results in plant roots drawing upon a greater volume of soil moisture. In low places a concentration of moisture takes place and ground-water areas support those plants which use more water than dry-land plants. Finally the water- loving plants, living with their roots in water, are large con- sumers of water. DROUGHT -RESISTANT PLANTS Certain plants are qualified to inhabit desert areas where temperatures are high and precipitation is low. These plants have guarded themselves against excessive transpiration in order that they may conserve the limited supply of moisture available. .. This economy is accomplished, in part, by reducing the area of the transpiring surface through size of the leaf or in limiting the amount of foliage. In some instances the plant lives through the dormant season by storage of moisture in succulent tissues. In others, modifications, as hairs on the leaves, waxy surfaces, or closing or concealing of stomata are employed to prevent ex- cessive transpiration. Investigations of desert growth by Cannon (9), have shown three different systems of roots developed by perennials in their struggle for survival under arid conditions. First, the spreading type of lateral roots which are common to many cacti; second, the long tap root which not only helps to anchor the plant against winds, but draws moisture from depths below the surface; and third, a generalized type which combines the other two, enabling the plant to take advantage of all the moisture in the soil to a depth of several feet. The creosote bush (Covillea glutinosa) is an ex- ample of the generalized systems which probably accounts for its rather wide distribution under varying conditions of moisture. Desert growth includes many plants having varying water 8 requirements, but generally one doainant species is best adapted to the prevailing conditions of rainfall. Generally these species will be found in widely scattered regions where much the same con- dition of rainfall exists. In other areas, the dominant species may be in association with others which in turn will dominate as moisture conditions become more favorable to their growth. Changes such as these are shown in Table 1, which indicates the relation of temperatures and rainfall to some of the prevailing types. Although rainfall is a matter of record in most localities, but little is known regarding the limits of soil moisture upon which the flora of the desert survive. Statements of the moisture percentages in a given soil are of little value unless the physi- cal properties of the soil are likewise known, as the percentage alone does not indicate the quantity of water available for plant use. For this purpose moisture in excess of the wilting percent- age is a better indicator of the quantity that the plant may ex- tract from the soil. "Permanent wilting percentage" has been defined by Veihmeyer and Hendrickson (35) as "the lower limit of readily available soil moisture." In agriculture this is the soil-moisture condition that limits the activities of plants. In the case of desert growth, the plant survives, but remains dor- mant during long periods of deficiency and resumes growth when new moisture is received. Limited investigations in the Coachella Valley, Calif. , (26) found creosote bush, chamiso ( Atriplex canescens ) and desert sage growing in areas having extremely little available moisture. In the spring, moisture in the soil ranged from 2.2 per cent below the wilting point to 3-5 per cent above, but by the following autumn these amounts had decreased to as much as 8.0 per cent below the wilting point. In the Gila Valley, Ariz., (26) much the same conditions were observed. Investigations in the Tooele Valley, Utah, (15) showed big sagebrush (Artemisia tridentata), shadscale (Atriplex confertif olia) , kochia (Kochia vestita) , and TABLE 1 RELATION OF TEMPERATURE AND PRECIPITATION TO SOME PREVAILING TYPES OF SOUTHWESTERN DESERT VEGETATIONi/ Prevailing type of natural vegetation Desert sage (Atriplex polycarpaj Desert sage and creosote bush (Atriplex polycarpa and Covillea gluti- nosal Creosote bush (Covillea glutinosa) Desert grass and creosote bush (Covillea glutinosa) Creosote bush and Yucca-cactus (Covillea glutinosa and Yucca mohavensis Ferocactus and Opuntia bigelovii) Desert grass Short grass Chaparral Locality Death Valley, Calif, Indio, Calif. Calexico, Calif. Mecca, Calif. Salton, Calif. Mohawk, Ariz. Las Vegas, Nev. Bagdad, Calif. Yuma, Ariz. Barstow, Calif. Sentinel, Ariz. Aztec, Ariz. Gila Bend, Ariz. Casa Grande, Ariz. Maricopa, Ariz. Phoenix, Ariz. Mesa, Ariz. Tempe , Ariz. Needles, Calif. Mojave, Calif. Parker, Ariz. Logandale , Nev. Lone Pine, Calif. El Paso, Tex. Sierra Blanca, Tex. Lordsburg, N. Mex. Deming, N. Mex. Socorro, N. Max. Alamogordo, N. Mex. V/illcox, Ariz. Carlsbad, N, Mex. Douglas, Ariz. Florence, Ariz, Tucson, Ariz. Wickenburg, Ariz, Congress, Ariz. Cabazon, Calif. Mean annual Annual Eleva- temper- precipi- tion2/ ature tation 3/ Feet °F. Inches -178 75 1.45 - 20 73 3.00 0 71 3.18 -185 71 3.27 -263 -- 3.36 538 74 3.57 2033 64 4.51 78/f 72 2.28 141 72 3.33 2105 63 4.10 685 71 4.57 492 70 4.81 737 72 5.90 1400 72 6.89 1186 71 7.03 1108 70 7.43 1245 68 8.65 1165 67 9.31 477 72 4.45 2751 64 4.84 350 69 5.07 1400 65 5.42 3728 56 5.69 3778 64 9.05 4512 __ 9.45 4245 61 9.54 4331 60 9.66 4600 57 10.13 4250 61 10.92 4200 60 11.21 3120 63 13.03 3939 62 13.71 1500 69 10.04 2423 67 11.50 2072 65 10.55 3688 67 13.55 1779 -- 10.96 17 After Shantz and Piemeisel (26). 2/ Minus sign denotes below sea level. 3/ Rainfall taken from Climatic Summaries of the United States containing climatic data from the establishment of stations to 1930, inclusive. 10 big greasewood (Sarcobatus vermiculatus ) growing under similar conditions . The extensive primitive grassland communities of the Great Plains did not support a uniform vegetation. The rainfall of the eastern portion moistens the ground to a depth of several feet, promoting a distinctive cover of prairie grasses 1 to 5 feet in height. Characteristic of the region, as listed by Weaver (37), are the bluestem grasses (Andropogon) which supply the bulk of the wild prairie hay, the tall panic grass (Panicum virgatum) , tall marsh grass (Spartina michauziana) which also furnishes an abundant foliage, and other plants. There is likewise a distinction between ground-water plants that feed upon fresh water and those that are tolerant of water slightly alkaline. Plants of this type are more or less salt- resistant. Saltgrass (Distichlis spicata) is an important unit in this group. It is found often in areas of shallow water table, the limit of depth from which the roots may draw moisture depend- ing upon soil type. Being a salt-resistant plant it is not an excessive user of water, and unless the water table is within 24 to 30 inches of the ground surface the water transpired will prob- ably be less than that required by most cultivated crops. In many localities succulents are identified with alkaline conditions resulting from areas of high ground water. Riparian vegetation, as alders, sycamores, and cottonwoods, growing in canyon bottoms where the roots are fed by percolation from the stream bed, uses large amounts of water. Seepage from irrigation canals often feeds the roots of willows, cottonwoods, sweetclover (Melilotus sp . ) , and other ditchbank vegetation. Such growth is sometimes troublesome in canal management. INDICATOR VALUE 0? GROUND-WATER PLANTS The value of many species of arid land vegetation as indi- cators of ground water has long been recognized in the geological and botanical investigations of southwestern desert areas, yet 11 literature on the subject deals inadequately with the problems of plant growth, root systems, transpiration losses, soil types, al- kali conditions, and their relation to underground waters. Such literature as exists is fragmentary and treats of these subjects, if at all, more or less individually. Me Inzer (19) and other in- vestigators, however, have assembled from various sources much information in relation to ground-water plants and the depths at which they seek moisture. Many desert plants have been listed by them as indicators of ground water. The opportunity for such growth to send its roots to water is naturally limited, as ground water in the desert is usually beyond the reach of the root systems of plants. Nevertheless, certain areas exist where it may be found. These are mostly in the vicinity of surface lakes or desert playas {dry lakes) where water is reasonably close to the surface. Because of soil evapo- ration, areas overlying high ground water are likely to be strong- ly alkaline and the vegetation which they support is of the salt- resistant type. Ground-water areas are generally in the lowest portion of a region. As the terrain rises towards the surrounding hills and distance to water table increases, vegetation changes from the salt-resistant succulents to the more bushy and woody types which have roots developed for obtaining water from greater depths. This arrangement inevitably results in irregular zones of vegeta- tion arranged in the order of the ability of the roots to reach the ground-water levels. Exceptions occur, however, where perco- lating water from springs or occasional flows in normally dry channels furnish a somewhat inadequate water supply for a precar- ious growth. In the absence of comprehensive field studies relating to the subject, a complete catalog of ground-water plants and the depths to which their roots may go to secure water becomes im- possible. Nevertheless, the relation of certain plant species to water levels in the soil have been more or less adequately 12- determined in various localities and for different soils. For a more complete description of these the reader is referred to the various publications relating to this subject. Only a generaliz- ed list is here possible as the complete range of depth to which roots extend has not been sufficiently determined, the same species having more extensive root systems under some soil and moisture conditions than under others. The texture of soil, its capacity for capillary moisture, its permeability to rainfall as affected by soil type, slope, and surface conditions (12) in addi- tion to the amount of precipitation, are important factors in determining the limits of depth to which roots may extend. Studies of the relation of mesquite (Prosopls) to ground water, by Brown (8) and others, have definitely placed it as a ground-water plant that grows within a wide range of depth limits. The normal habitat of mesquite growth is the lowlands of south- western deserts, but it grows well also in other regions having altitudes of from 2,000 to 3,500 feet. It is sometimes found in upland draws at some distance from the lowland areas where the water table is not too far below the surface. Mesquite thickets occupy the lowest valleys where ground water is most readily available and such conditions may produce trees from 10 to UO feet in height. As depth to water increases the mesquite gradually diminishes in size until usually it ceases to exist where depth to ground water exceeds 40 to 50 feet. Such depths are unusual for ground-water plants. Of it, as a desert plant, Spalding has written: (28) "It (the mesquite) is commonly armed with spines, and its coriaceous leaves are well protected against excessive transpiration. It is a plant requiring a better water supply than many of its associates, yet well adapted to the low relative humidity of the desert air, and its occurrence beyond its own special area, corresponds with this peculiarity. Thus it is, in a sense, a desert plant, yet one of high water re- quirement -- characteristics which it shares with various other species. " 13 Saltgrass is another plant found in many regions where it is recognized as evidence of shallow depth to water table. In light sandy soils saltgrass grows where the depth to water does not exceed 6 feet and in heavier soils 11 feet. It is sometimes found in pure communities but more often in association with other ground-water vegetation. Investigations in the Owens Valley, Calif., by Lee (16) showed the first scanty appearance of salt- grass to be where the depth to ground water was 8 feet, with more luxuriant growths in areas of shallower depths. Vhite (38) re- ports saltgrass meadows in the Escalante Valley, Utah, where water is within 4 feet of the surface; the growth is thin and in associ- ation with greasewood, rabbitbrush ( Chrysothamnus graveolens) or pickleweed where the depth ranges between 4 and 10 feet. In the Santa Ana Valley, Calif., it grows where the ground water is from 3 to 12 feet below the surface, depending upon soil type aud drain- age conditions. The distribution of saltgrass depends not only upon ade- quate soil moisture reasonably near the surface but also upon soil conditions favorable to its growth. It is seldom observed where the soil does not contain a moderate amount of alkali. Where the salts become excessive, however, white spots appear in what are otherwise saltgrass meadows, the grass being killed by salt accumu- lation. The plant spreads by means of a thick creeping rootstalk within the upper few inches of soil, from which finer roots extend downward in search of moisture. The stiff, light green leaves rise from each joint of the rootstalk and often spread to form a dense sod. The grass has a distinctly salty taste although it is often used for pasturage of stock or dairy cattle. The growing period in southern California is from February to December, and although the grass dies or becomes dormant during the other months there is some discharge from the water table throughout the year. Saltgrass is not an excessive user of water, as its habit of growth in alkali soils has caused it to protect itself against the 14 toxic effects of alkali by a decreased rate of transpiration. While the alkali condition of the soil which supports saltgrass is sometimes excessive, nevertheless drainage has reclaimed numerous areas which it formerly covered. The big greasewood found on subirrigated lands from the Canadian to the Mexican borders is also recognized as an indi- cator of ground water. As with other ground-water plants, the more luxuriant growth occurs where the zone of saturation is within a few feet of the surface, but according to Me Inzer (19) it is, like the mesquite, sometimes able through its large deeply penetrating taproot, to extract moisture from the soil to depths of 40 feet or more. It is an indicator also of alkali in the soil, but under proper systems of irrigation and drainage greasewood areas have good possibilities of becoming agricultural districts. Mesquite, saltgrass, and greasewood are but a few of the many ground-water plants common to western regions, and it is neither necessary nor possible to describe all such growth within the limits of this report. Data on the relation of plants to ground water have been listed by Meinzer (19) as a basis for fur- ther investigation, realizing, however, that such generalizations may be questioned. Marsh Vegetation Chief of this group are plants, the roots of which ordin- arily grow in water or in very wet soil. Typical examples are the cattail (Typha sp . ) , tule (Scirpus acutus ) , and sedges (Carex sp . ) which belong to that group of water-loving plants known as hydro- phytes. These and others of similar habits, through transpiration, dispose of large quantities of water from the surfaces of ponds, lakes, marshes, and running streams, and probably have a greater effect upon the water supply of streams than any other group of plants of equal area. Both tules and cattails are common in many regions. Prior 15 to the reclamation of the delta lands of the Sacramento and San Joaquin Rivers in California there were approximately 180,000 acres of tules, cattails, and sedges growing in dense formation and transpiring heavily. Much of this area is now farmed, and the remaining growth is chiefly along stream channels and in other unreclaimed places. Tules also are products of undrained agricultural districts which have developed swamp areas through overirrigation. They soon appear in the shallow water of marshy places, and are par- ticularly iindesirable in drainage ditches. However, it has been learned by investigation (U) that large areas of tules do not use as much water per unit of area as those in the relatively narrow ribbons of growth along ditches and other stream channels. Ditchbank vegetation is subject to exposure from sun and wind with little protection from surrounding growth and tran- spires freely. It is well known that such vegetation is of the water-loving type, the use of water by a few species having been investigated. Where such studies have been undertaken, individual plants or groups of plants have been gro'/m in tanks and the water requirements measured. Attempts have been made also to determine the quantity of water consumed by mixed growths of willows, tules, cottonwoods , and other wet-land vegetation growing under natural conditions, but these have been limited in scope. 16 CHAPTER 3 METHODS OF DETERMINING CONSUMPTIVE USE Limited investigations of the use of water by natural vegetation have been made by various methods. Vegetative types, ranging from grasses to trees, have been studied, but owing to the inherent differences in aerial and root growth, different methods of approach are necessary. The source of water consumed by the vegetation, whether from a high water table or from rain- fall and soil moisture, is an additional factor influencing the selection. The principal methods used are: (1) by tank investiga- tions; (2) soil-moisture studies; (3) stream-flow measurements ; , and (4) interpretations of water-table fluctuations. (1) Tank investigations are conducted under artificial conditions. The growth in the tanks may be the original product of an undisturbed soil although more often perennial shrubs or grasses are transplanted into the tanks before water measurements are begun. With annuals, seed must be planted each year and new root systems developed. Artificial conditions are caused by the limitations of soil, size and depth of tank, or regulation of water supply, and by the very important factor of environment. In ck3nsequence , the resulting tank growth lives under conditions somewhat different from those affecting similar plants in their native habitat, and it is usually necessary to apply correction factors to tank results. The natural vegetation most often grown in tanks is of two classes: plants which grow with their roots in water, and those which use capillary moisture. Although a number of tank investi- gations have been made in recent years, the plants occupying the tanks have been limited to a few species. Of these, cattails and tules grow in water, while saltgrass, greasewood, sweetclover, and red willow ( Salix laevigata) draw moisture from a water table be- low the ground surface. In tank experiments the amounts of water 17 used are determined by quantitative measurements. The principal tank investigations of natural vegetation have been made in California, Colorado, Idaho, New Mexico, Oregon, and Utah. (2) Soil-moisture studies are generally conducted in areas where the water table is some distance below the root zone. The amount of precipitation retained in the soil is measured by means of soil samples taken from definite depths, before and after each rainstorm, and the moisture content of the sample is determined. In clay, loam, or sandy soils the soil tube is used in collecting the samples, but in rocky or gravelly places sam- ples are taken from open pits. This method is suitable for areas of deep-rooted natural vegetation. It may be used for weeds, native brush and grass, trees, and agricultural crops. The principal soil-moisture in- vestigations of native growth have been in California. (3) Consumptive use of v/ater by alders, cottonwoods, sycamores, and other riparian gro\irth common to small streams has been found by measurement of the stream flov; at two or more con- trol points where the underflow is forced to the surface, the decrease in flow between controls representing use of water by the vegetation affected. The danger of nonmeasurable inflow to the stream from the canyon sides is a factor not to be overlooked, and this difficulty makes many canyons undesirable for such in- vestigation. However, where conditions appeared stable, this method has been used by the Division of Irrigation in southern California. Literature, with a few exceptions, (2, 4) appears to have given the subject little attention, yet there is a field for this type of study in many localities. (U) Approximate measurements of ground-water discharge by plant growth may be made by translating the daily rise and fall of the water table into inches of depth of water consumed by the overlying vegetation. This requires a knowledge of the specific yield of the soil from which the water is withdrawn, specific yield being the amount of water which will drain from 18 a previously saturated soil by gravity, measured as a percentage of the total volume. Fluctuations of the water table, caused by transpiration losses, show a decline by day when transpiration is greatest, and a recovery by night when it is least. Measurement of the fluctuations by continuous recorders provides a basis for calculating the consumptive use. Investigations have shown that the daily fluctuations usually do not occur \inless there is vege- tative discharge. They respond directly to weather conditions, increasing in amplitude with sunshine, temperature, and a clear sky, and decreasing with lower temperature, greater humidity, and increasing cloudiness. This method was first proposed by Dr. G. E. P. Smith of the University of Arizona in an unpublished paper read before the Geological Society of Washington, November 22, 1922. It has been successfully used by White (38) in the Escalante Valley, Utah, and by Troxell (33) in the Santa Ana Valley, Calif. It is an ingenious method of translating a natural phenomenon into vegetative discharge, having the distinct advantages of using soil that has never been disturbed and of measuring consumptive use by vegetation in its native habitat. On the other hand it involves the obvious difficulty of obtaining average specific yield of a large noniiniform soil mass underlying a given basin. TANK MEASUREMENTS Metal tanks have been used extensively in plant investiga- tions for many years. Those best adapted for consumptive use of water studies are of the double type having an annular space for water between the inner and outer walls, with perforations through the inner wall to insure a thorough distribution of water throughout the soil mass. Tanks of this design usually are from 24 to 36 inches in diameter by 4 to 6 feet deep. They should be of heavy galvanized iron to withstand corrosion. In acid or alkali soils the metal should be treated with a protective coating. 19 The Mariotte Tank It is often desirable to make investigations in which the water table in the soil tank does not fluctuate with the demands of the plants. For this purpose the Mariotte supply tank is of practical use. Inverted bottles having connections to the water surface have been used on occasion, but more elaborate arrange- ments embodying the same principles, have been designed by the Division of Irrigation (2, 20, 21). This equipment has given general satisfaction by maintaining a fixed water level in the annular space and in the soil, as well as providing a means of measuring the daily rate of extraction of moisture by the plants. In the Santa Ana, Calif,, (2) investigations a battery of Mariotte tanks was used. The following description indicates the relation of supply tank to soil tank and outlines the theory under which operation proceeds: The Mariotte tank, a 12- by 36- inch galvanized-iron range boiler, was chosen because of its solid construction, the rigidity of its connections, and the practicability of keeping it airtight (fig, 1). Mounted on the side of the tank is a vertical length of glass tubing, each end of which is fitted with a rubber stopper perforated to admit a small connecting pipe. The lower pipe connects with the supply pipe between the Mariotte tank and the soil tank, while the upper pipe connects with the top of the supply tank. A graduated scale moiinted beside the glass tube shows the depth of water in the supply tank. A valve in the connecting pipe makes it possible to shut off the flow of water when the supply tank is refilled, A waste pipe in the connecting pipe discharges excess water from the soil tank into a receiving vessel. The lip of the waste pipe is set at the level of the water in the soil tank, A small vent tube passes through the rubber stopper at the top of the glass gage. This tube is open at both ends (the lower end in water and the upper in air) and the level of the soil water is determined by the elevation of the bottom end of the vent. In 20 J^ Supply tank ■ Glass tube -Meter stick Trench 4 Galvanized iron pipe To be at same level 12-0 '^ W^sV-'VW^c7jl-V<'^x-7/'/c.'-"W, Soil tank V Water surface mn FIGURE l.--Mariotte tanlc connected to soil tank to maintain a constant water level in the soil and supply water evapo- rated or transpired. Santa Ana station, 1929-32. Figure 1 the water table in the soil tank is at such a depth that it is necessary to extend the vent tube downward into a well be- low the level of the connecting pipe. Experience has determined that variations in temperature cause changes in vapor pressure in the Mariotte tank, resulting in fluctuations of the water level. Thorough insulation is there- fore necessary. Tanks at Santa Ana were completely buried in the ground except for a small entrance provided with a narrow doorway which opened upon the graduated scale. Protection against changes in soil moisture around the tanks due to rainfall was provided by a section of roof which excluded precipitation while permitting a 21 free circulation of air above the tanks. The vent tube provides the Mariotte control feature which maintains a constant water level in the connected soil tank. In operation, the Mariotte tank is filled and the valve in the con- necting pipe is opened, admitting water to the soil tank. As the water level drops in the supply tank a partial vacuum is formed above the water surface and the water drops in the vent tube from the original level to a point the position of which depends upon the degree of vacuum established. This point is determined by the difference in the pressure heads due to atmos- _ pheric pressure and the partial vacuum in the supply tank. Water will continue to fall in the vent tube, but at a greater rate than in the Mariotte tank, until the pressure head corresponding to the atmospheric pressure, minus the pressure head caused by the partial vacuum, is balanced by a column of water equal to the difference in elevati9n between the water surface in the Mariotte tank and the bottom of the vent. Water will then stand in the vent at the bottom of the tube with the pressure at this point atmospheric. If the water continues to flow, air will enter the glass gage through the vent tube, bubbling upward through the water and into the top of the supply tank. Water will continue to rise in the soil tank to the level of the lower end of the vent, at which point the atmospheric pressure in the soil tank and in the bottom of the vent tube is the same. As there is no difference in pres- sure and both points are at the same level, there is no head to cause further flow and bubbling will cease. When the water table in the soil falls below the bottom of the vent, the balance of pressures is again disturbed and flow will once more start from the Mariotte tank, replacing the quantity of water used. As a partial vacuum must be maintained at all times, pipe connections must be airtight. Air leaks through the many joints of the system disturb the balance of pressure necessary for full automatic control. Thorough insulation against temperature 22 changes has been mentioned. Such changes may cause expansion or contraction of the tank itself, of the water in the tank, and of the air in the chamber above the water. The combined result is change in the vapor pressure with consequent influence upon effective regulation. Water in the glass tube will fall with an increase in tem- perature within the Mariotte tank, and readings on the scale, taken at this time, will be erroneous. A test of the effect of temperature on scale readings showed that an increase of 30 F. in outside air temperature caused a drop of 1 centimeter of the water level in the glass gage. As the temperature returned to the starting point, water in the gage came back to its initial position. Early morning is a better time for observations than later in the day when temperatures are higher. Float Valves A simple device for maintaining a definite depth of water above the soil surface in tule tanks is an ordinary float valve connected by a feed pipe to a supply tank. The float valve is adjusted to operate at the required water surface. As the water is used the float drops to open a needle valve and admit water from the supply tank. A gage on the side of the tank permits readings of water levels, and the quantity of water released be- tween observations is equal to the consumptive use by tank growth. This equipment has the advantages of fitting into a small space and of maintaining a constant depth of water. It is easily in- stalled and gives satisfactory results. A water-stage recorder with float in the supply tank may be attached to obtain contin- uous records of consumptive use. 23 FACTORS AFFECTING THE USE OF WATER BY VEGETATION GROM IN TANKS It has already been stated (page 16) that the use of water by tank crops varies in some degree from natural field use, and this difference must be compensated for by applying a reduction factor to tank records. A knowledge of the influencing factors and an effort to carry on an investigation under the most natural conditions will go far to equalize the use of water between tank grov/th and natural fields. The factors affecting tank investiga- tions are many and are related to soil, water, plants, and envi- ronment . Methods of placing the soil in the tank, density of vege- tation, unnatural environment of growth, injury to root systems, limitation of the amount of soil as affecting root growth and soil fertility, aerial spread of foliage, and entrance of rain water, act upon the growth of tank vegetation or the amount of water it consumes. Each of these factors is important, as esti- mates of field consumptive use by natural cover will be in pro- portion to the accuracy of the tank determinations. Experience with the Santa Ana investigation (2) has demonstrated a satisfactory method of filling soil tanks without soil disturbance. The recommended practice is to force the open- bottom inner shell of the double cylinder tank down over a core of undisturbed soil, cutting off the soil column by jacking the bottom plate into place when the shell is filled. (Plate I-A. ) This requires an excavation around the tank as the work proceeds. Once the plate is bolted in place the filled tank may be hoisted above ground with tripod and chain-block and lowered into the outer tank previously set in the location selected. This pro- cedure leaves the soil in the tank in its original condition and has the advantage of sometimes capturing a growing crop without serious disturbance to its root system. The relation of density of tank growth to natural field growth is a contributing factor in determining the reduction 24 PLATE I L. A. Screw jack working against anchored cable, forcing soil tank 6 feet into the ground to capture undisturbed soil, Soil sampling equipment: compressor unit (on truck), pne\imatic driving hammer (in operator's hands), ordinary soil tube hammer (on ground) and soil tube jack. 25 coefficient which must be applied to tank results. Grasses, particularly the original crop of an undisturbed soil, are most likely to have the same density of growth as under field condi- tions, and the use of water by the tank crop will be approximate- ly the same as by grass in the open field. For native shrubs it is difficult to obtain the same density of growth as under natu- ral conditions, since this tj'pe of vegetation does not grow in an orderly manner. The wide spacing of some shrubs and the close growth of others make the correct unit area per plant a matter of conjecture . Aquatic plants, as tules and cattails, may grow with the same approximate density in tanks as in swamps, although the plants around the edges are more stunted than in the center, owing apparently to greater exposure to sun and wind. The n\imber of stems per unit area is likely to vary in different tanks. A comparison of the density of tules in the Santa Ana investigation (4), showed a tank 6 feet in diameter to have a density of 57 stems per square foot of area and to use 12.43 acre-inches of water in September, while a 2-foot tank having 87 stems per foot used 19.37 acre-inches. Both tanks had the same exposure. Carry- ing the comparison further, the consumptive use of v/ater per indi- vidual stalk was the same regardless of density of growth or the size of tank in which it grew. However, the tank growth was stunted in comparison with normal swamp growth. The limitations of tank groiirth, as affected by environment, are extremely important in determining the quantity of water used. It is emphasized that tanks containing vegetation must be sur- rounded by the same tjrpe of growth; otherwise there can be no true comparison of the amount of water used by the tank vegetation and similar growth in the field. The injury to roots caused by transplanting vegetation into soil tanks, or through cutting the roots, temporarily limits the plant growth and temporarily affects the amount of water consumed. Plants with running roots (saltgrass or brush for example) are 26 subject to shock when their roots are disturbed or partly removed. The size of tanks is a limiting factor in the root distribution of tank growth, especially roots of the spreading tjrpe. It has been observed that roots of tules growing in tanks of small diam- eter become greatly crowded after the first year, and the plant growth becomes more or less stunted as the investigation proceeds. Limitation of the amount of soil as affecting fertility is likewise important in determining the use of water by tank crops. Investigations running over extended periods in which the rela- tively small volume of soil is used continuously are likely to result in a stunted growth. The effect of continued cropping of tank soil has been noticed in cotton investigations extending over a 3-year period. Beckett and Dunshee (1) say: "A comparison of the size of plants grown in the tanks with those grown in the field plots under similar irrigation treatments, showed that smaller plants were produced in the tanks each year than were obtained in the plots. These smaller plants, however, used from 40 to 53 per cent more water than the plants growing in the field. This increased use of water might be explained by the probable root concentration in the limited soil mass of the tanks, a higher soil temperature in the tanks, and the higher temperatures and lower humidities surrounding the individual plants in the tanks." Crop overhang of tank growth also presents a serious ques- tion in tank Investigations. The aerial portions of som.e crops, such as tules and cattails, grow naturally stiff and erect and occupy approximately the same horizontal area as the tank. In other growth, such as sweetclover, the stems droop over a much greater area than that occupied by the tank. The interception of insolation under such conditions is greater than the tank intercept, and it is incorrect to compute the water loss on a basis of tank area. Protection of soil tanks during periods of precipitation to prevent entrance of rain water into the soil has been generally condenuied, yet for some purposes prevention of rainfall on the 27 tank surface has advantages. Investigations involving use of water by plants under natural conditions where the ground water fluctuates from day to day and from season to season undoubtedly require that rain be allowed to enter the tank soil. On the other hand, in those investigations which are carried on with a fixed water table, the entrance of rain water into the soil dis- turbs the normal distribution of capillary moisture. In its natural distribution the largest percentage is immediately above the water table and the least at the ground surface. If rainfall is allowed on the tank, the entire soil mass becomes filled to field capacity, and conditions relative to a fixed water table no longer exist. In a series of soil tanks having different depths to water table, each with overflow pipes to drain off excess soil water, the soil moisture varies with the depth to the water table. For instance, if the water table is near the surface and rainfall is heavy there will be much overflow from the waste pipe, as the shallow soil is unable to hold all the excess; but if the water table is deep in the tank there will be little overflow as the greater volume of soil holds more rain. Thus all the rain might be retained in a deep tank while but a small portion would be held where the water table was near the surface. Under these conditions the changed moisture distribution resulting from rain- fall penetration is different for each tank or for each depth to water table. Hence, while the treatment of a series of tanks may be uniform as regards soil moisture during the dry season, it is far from uniform during the wet season. It is evident, therefore, that the procedure to be followed for tank protection will depend largely on the object in view. 28 SOIL -MOISTURE STUDIES It has been shown that the limitations of soil tanks make them inadequate for some types of consumptive use investigations. Tanks are suited to areas of high ground water where studies are to be made with definite water levels but studies in other areas where the water table is beyond reach of root systems may best be carried on through soil sampling. The Division of Irrigation and various agricultural experiment stations have employed soil sam- pling for agricultural crops and to some extent for natural vege- tation. Soil-moisture studies require systematic collection of many soil samples taken to depth beyond the reach of plant roots. This is done through use of soil tubes of different lengths driven into the soil to known depths. The samples obtained are dried in an electric oven at a temperature of 110 C. Standard laboratory practices are followed. Collection of soil samples is a laborious process, as the manual effort of driving soil tubes by hand, especially for depths beyond a few feet, is extremely arduous. To lessen the labor and expedite the work a compressed air unit developed by the Division of Irrigation (3) drives the soil tube mechanically. The entire equipment, shown in Plate I-B, consists of an air compressor, a soil tube, and a soil tube jack. The air unit includes a com- pressor mounted on a truck, a light air hammer, and an air hose. It provides a pressure of 100 pounds per square inch, delivering 2,250 blows per minute to the soil tube. The soil tubes are of l6-gage seamless steel tubing, from 5 to 2$ feet in length, fitted with a suitable driving head and a cutting point. The point is of case-hardened nickel steel with a choke bore to overcome friction within the tube. A very efficient, light-weight jack shown in the foreground in Plate I^B has been perfected by the Division of Irrigation (31) to draw the soil tube from the ground under difficult conditions. 29 Withdrawal from depths as great as 25 feet is practicable with this eauipment in soil which is neither too wet nor too coarse. In wet clay the soil sticks to the tube and is difficult to dis- lodge, while saturated soil slips from the tube and is lost be- fore it can be drawn to the surface. Samples of coarse material greater than the diameter of the tube cannot be obtained with this equipment. Most of the valley lands may be sampled with the soil tube, but alluvial fans, gravel areas, and other coarse and rocky places require pits, shafts, or tiinnels. Samples of soil obtained through use of the soil tube weigh 150 to 200 grams, but in rocky soil large samples of the material are more representative. Accordingly, from pits or shafts, 4,000-gram samples are obtained without reference to size of particles. After they have dried, the rocky portions are screened out and classified as rock. The equivalent depth of water in soil samples may be found PVd from the equation D = Yoo'' ^^ which D is the equivalent depth in inches; P, percentage of moisture in the sample; V, apparent spe- cific gravity of the soil in place; and d, depth of soil sample in inches. The depth to which soil samples are taken depends upon the depth to which roots go in search of moisture. As previously shown, some vegetation is deep-rooted while other species have roots relatively close to the surface. Moisture may percolate to depths beyond the root zone, but root extraction determines the depth to which it is necessary to take soil samples. Beyond this depth percolating water contributes to the underground -water sup- ply. Thus, by sampling, to determine the use of water by deep- rooted shrubs it might sometimes be necessary to drive soil tubes to depths of 25 feet or more, whereas for shallow-rooted grasses 4 to 6 feet would be sufficient. 30 STREAM- FLOW STUDIES Because of the increasing scarcity of small water supplies in some parts of the West and the opportunity of obtaining them by diverting canyon streams, there is need to know what happens to the adjacent vegetation when the greater portion of its mois- ture supply is taken away. For many water-loving trees and shrubs, stream diversion often proves destructive. In addition to the usual factors of climate affecting the water requirement of canyon-bottom growth there are the environ- mental factors of type, density and distribution of adjacent vege- tation, slope and depth of the soil mantle supporting the vegeta- tive cover, and axial direction and general slope of the canyon bottom as affecting its exposure to sunlight. The density of growth affects the degree of shade and the amount of transpira- tion, especially that of the under story cover. Slope and depth of the soil mantle control, to a considerable extent, moisture held in the side slopes of the canyon wall. The cardinal direction of the canyon axis is likewise important, as is also the direction of slope of the mountain side of which the canyon is a unit. In general a canyon stream extend- ing in a northerly and southerly direction has greater exposure to the sun, and its vegetation has greater transpiration opportunity, than one running east and west. This is especially true of the deeper canyons. Likewise the general direction of the mountain slope influ- ences not only such climatic factors as humidity, rainfall, temper- ature, wind movement, hours of sunlight, and melting or retarding of snow cover, but also to some extent the variety and density of the vegetation itself. Such differences, on opposite sides of easterly and westerly mountain ranges, are commonly understood. On the southerly side longer and more intense exposure to the sun increases transpiration losses, snow melts more rapidly, and stream flow decreases or dries up at an earlier date than on northerly 31 protected slopes. Canyon-bottom growth is usually water-loving. It may be a meadow, a swamp, alders, willows, the larger sycamores, cotton- woods or cedars, or a mixture of them. Under certain conditions the use of water by vegetation in any selected section of a given canyon may be determined by the difference in stream measurements at its upper and lower boundaries, particular care being taken to force the underflow to the surface at points of measurement. In some instances natural rock barriers to underflow exist and the stream flows naturally over them, but in other cases artificial controls, such as submerged dams, may be necessary to bring the ground water to the surface. Before an investigation is under- taken, the canyon and its surrounding area should be examined to determine the possibility of stream-bed losses through rock fis- sures. Where fissures occur or accurate measurements are impossi- ble, the investigation is not feasible. The possibility of side inflow from canyon walls also should be examined. The Division of Irrigation used the method referred to above in determining the consumptive use of water by canyon-bottom vegetation in south- ern California (see p. 66). (2, 4). The diurnal fluctuation of flowing streams is of importance as an indicator of the daily withdrawal of water from the soil by plants. It has long been observed that stream flow decreases by day and recovers by night, the plotted daily discharge curves showing a series of alternate low and high points which occur at approximately the same time each day. The daily decline is the result of the action of plants in withdrawing water from the satu- rated zone, and recovery is due to the nighttime decrease of transpiration. Therefore, as the daily fluctuations of the stream surface depend upon transpiration from plants, the same factors which affect transpiration likewise affect flowing water, but in a reverse order. That is, when bright sunshine, warm weather, or hot winds cause high rates of transpiration the corresponding stream flow will be low: but it will increase in volume when 32 transpiration is low through cloudiness, cool weather, or high humidity. The use of water-stage recorders at control points pro- vides hydrographic charts that indicate the effect of transpira- tion upon the flowing stream. The effect may be too small to be visible in the stream itself except in springs and small streams which disappear in the sand by day and flow in the channel by night. Evidence of these daily fluctuations is afforded, however, in Figure 2 which was developed by Troxell (34) to show short- 1 1 \ 1 1 1 1 MILL CREEK POWER CANAL I El. 2950ft. Area 43 sq.m;. CAJON CREEK El. 2620 ft. Area 40.9 sq.mi. LITTLE SANTA ANITA CREEK El. 2200ft. Area 1.9 sq.ml. WATERMAN CANYON CREEK El.2l25ft Area 4.6sq.m;. SANTA MARGARITA RIVER at Ys;dora , CaHf. El. 15ft. Area 740 sq.mi. FIGURE 2. — Diurnal fluctuations in southern California streams (after Troiell). 33 period records of the flow of eight California streams. These were selected to represent a variety of drainage basins varying in length and width as well as in altitude. It will be noted that each hydrograph shows a well-defined daily cycle with rise and fall at approximately the same time each day although not in the same degree of amplitude. Evaporation from a water surface is an expression of the combined climatic influences affecting both evaporation and tran- spiration, yet because of the volume of water in an evaporation pan, the solar energy necessary to cause evaporation is greater than that which causes transpiration from plants, and thus evap- oration lags behind transpiration. To obtain a more sensitive record of transpiration opport\inity , an evaporimeter was designed by Taylor (4). This consisted of a shallow, black pan attached to the weighing mechanism of a recording rain gage. The depth of water in the pan is limited to the maximum evaporation for a sin- gle day. The chart scale is exaggerated 9 to 1, making possible the reading of very small amounts of evaporation. With this equipment it is feasible to determine exact hourly evaporation losses. The exposed shallow pan, resting on a sensitive balance, responds readily to wind movement and the resulting pan movements on the chart also record the times of greater wind movement and its relative intensity. A measuring device much used in California investigations is the Parshall flume (22). The difficulty of measuring, in a single device, both low and high water flows, has been met in a combination Parshall flume and connected V-notch weir or by two connected Parshall flumes of different throat widths, arranged by Taylor (4) to pass the maximum and minimum flows respectively. The difficulty of accurate measurements of low water flow in a flume intended for peak flow is obvious. Design for a double Parshall flume is shown in Figure 3- It should be noted that the combination flume requires two water-stage recorders. In using the Parshall flume it should be remembered that 34 ELEVATION FIG-UHE 3. --Combination flume for measurement of water at both high and low stages. 35 this device was designed for irrigation canals carrying water at a relatively low velocity and that it should be used in mountain areas with some caution. WATER-TABLE FLUCTUATIONS The three methods of measuring consumptive use of water by vegetation previously discussed - tank, soil moisture, and stream- flow investigations - are applicable to somewhat limited soil- moisture conditions or types of growth. The tank method is suit- able for the smaller vegetation, but it is evident that it cannot economically be used for studies of consumptive use of water by large trees. Extensive soil-moisture investigations generally are not undertaken in areas of high ground water, and it is evi- dent also that canyon-bottom investigations are limited. Observa- tions .of daily ground-water fluctuation in relation to vegetative discharge has been little used. Beyond its application in Arizona by Smith and in California (33) and Utah (38), it apparently has not received much attention, largely because of the difficulty of determining the specific yield of large areas of soil in place. Water-table fluctuations provide a basis of estimating the con- sumptive use of water by overlying vegetation but present diffi- culties in arriving at precise measurements of quantity. During the early spring, as vegetation is beginning its growth, the daily fluctuations of the water table do not reach the same degree of amplitude that occurs during periods of maxi- mum growth; and conversely, in the fall, as vegetation is matur- ing and transpiration decreases, the daily fluctuations become progressively smaller. Fluctuations do not occur where there are bare lands or plowed fields under which the ground water is below the reach of plant roots, nor during winter months when plants are either dead or dormant. Lower temperatures, cloudiness, or rain- fall decrease the size of the fluctuations; warm sunshine, low humidity, or hot winds increase them. In short, any cause affect- ing transpiration influences also the diurnal changes of the water 36 table. Fluctuations begin approximately at the same time each day, the surface lowering as the transpiration increases, although the result of the increased transpiration is not immediately ap- parent and there is a noticeable lag between cause and effect. During the growing season, when demand is greatest, the dajrtime draw-down generally exceeds the nighttime recovery. The result is a steadily falling water table which continues \intil transpi- ration ceases. When plants become dormant the normal recharge of the basin increases ground storage until a resumption of the vege- tal demand occurs in the following spring. Because the water usage of some plants is greater than that of others, the draft of the different species on the ground- water supply varies with the type as well as with density of the natural cover, so that the amplitude of the fluctuations varies with the vegetation. The fluctuations are widest where water- loving vegetation constitutes the dominant growth and are least where drought-resistant or salt-resistant plants occupy the great- est area. Not only does the type and density of plant growth affect the quantity of water withdravm, but the depth to water affects the total consumed, as is evident from the stunted growth found where the water is at considerable depth. Interpretation of the ground-water fluctuations in inches of depth of v/ater consumed by vegetation is accomplished by the following method: First, ground-water wells are equipped with water-stage recorders which provide continuous records of changes in water levels. Second, the specific yield of the soil near the wells is determined by driving metal cylinders over columns of undisturbed soil. Third, the ground -water discharge in inches of depth is computed by means of the formula Q, = ^(24r + s_) where ^ is the consumptive use of water, ^ the specific yield of the soil for the area investigated, and r the hourly rate of recharge of the water table during the hours of least transpiration demand. This period is between midnight and 4 a.m. The factor s_ is the net difference in the height of the water table in 24 hours. 37 The curve of ground-water fluctuations has the general characteristics of the curve of daily stream fluctuations; that is, there are both a maxinmm and a minimum period in each 24 hours. These periods do not necessarily occur at the same time. For the purpose of discussion, a representative ground-water curve is shown in Figure 4. It v/ill be shown that this type of curve establishes the daily relation of consumptive use of water to ground-water discharge and recharge. 0 / i ^ / / / 3^ \ V t 1. / d c VI h y s ; 6 A.M. 6 P.M. NOON 6 A.M. 6 P.M. NOON FIGURE 4.-- Representative ground-water curve, showing effect of the daily cycle of tran- spiration by overlying vegetation (after Troxell) . Assuming that the ground water rises during the night when transpiration is at a minimum, there will approach a time during the morning hours, with increasing transpiration, v;hen the demand of vegetation just balances the inflow. This point is indicated at the top of the daily ground-water curve "a" where the water table starts to fall. On the other hand, at the bottom of the curve "b" in the late afternoon, transpiration losses have decreased to such an extent that they are balanced by the daily recharge and the water table begins to rise. At some point 38 between these two extremes vegetation is not only using all the inflow into the basin, but is also making its maximum demand upon the water held in storage in the soil. This point is indicated by the steepest slope on the falling side at the point "c" be- tween the top and bottom of the curve and represents the maximum daily transpiration. Likewise, the rising side of the curve indi- cates less transpiration than inflow and consequently an increase in ground-water storage. The steepest slope on the rising side "d" , then indicates the point of minimum or no transpiration, and the time of this occurrence lies between the hours of midnight and k a.m. At this point, the hourly rate of rise represents the hourly rate of recharge. Evidence has been advanced by Troxell (34), however, to show that the rate of recharge "r" is not constant throughout the transpiration period, but changes as the rate increases, becoming a maximum at the height of the transpiration season. There is little evidence to show how seriously this will affect estimates of consumptive use. It is not claimed that water-table fluctua- tions provide a basis for precise measurements; rather, they are considered a foundation for approximate estimates. 39 CHAPTER 4 INVESTIGATIONS OF THE DIVISION OF IRRIGATION BASIS AND SCOPE OF STUDIES Consumptive use of water by noncrop plants has been the subject of investigations by the Division of Irrigation in cooper- ation with the Division of Water Resources, Department of Public Works, State of California, and other agencies for a number of years. Few native plants have been studied, however, as they are far too numerous for all species to be included in these investi- gations. Grasses, small shrubs, and swamp vegetation may be grown in tanks, but larger shrubs and trees present problems in consump- tive-use measurements that are seldom studied. As an adjunct of such investigations, records of tempera- ture, precipitation, evaporation, and wind movement are of value. Such records for the Santa Ana station, Calif. , appear in Table 2. Knowledge of consumptive use of water by native growth is most needed for moist areas containing potential water supplies. In closed basins water that may be recoverable amounts to a con- siderable portion of the annual evaporation and transpiration losses. The natural growth of such areas is usually limited to grasses and water-loving shrubs and trees. Saltgrass, found on moist land, has been grown by the Division of Irrigation and other investigators in tanks having both fixed and fluctuating water tables. Santa Ana Valley, California — ' In 1929, the Division of Irrigation in cooperation with the State Division of Water Resources undertook an investigation in the Santa Ana River Valley to measure the consumptive use of 17 Field investigations at the Santa Ana, Prado, and San Bernar- dino stations were made by Arthur A. Young, Associate Irrigation Engineer, Division of Irrigation in cooperation with the Division of Water Resources, Department of Public Works, State of Calif or- lia. 40 TABLE 2 METEOROLOGICAL DATA AT SANTA ANA STATION, SANTA ANA, CALIF. 1929-32 Temperature Evapora- Wind movement Mean Mean tion from Month and maxi- mini- Precipi- a Weather year mum mum Mean tation Bureau pan Total Average Miles 1929 °F. °F. °F. Inches Inches Miles per hour May- Ik 51 62 0.03 8.39 -- -- June 76 53 64 .11 8.23 -- -- July 81 60 70 — 8.89 — — August 85 60 72 -- 8.90 -- -- September 79 58 68 .35 5.65 1695 2.4 October 80 52 66 -- 6.06 1745 2.3 November 77 41 59 -- 5.26 1806 2.5 December 72 41 56 -- 3.44 1547 2.1 1930 January 62 40 51 5.55 2.28 1743 2.3 February 66 44 55 .55 2.87 1682 2.5 March 68 46 57 2.99 4.48 2212 3.0 April 72 47 60 .80 6.05 1970 2.7 May 70 48 59 1.23 6.79 2228 3.0 June 75 55 65 .02 6.95 1871 2.6 July 81 57 69 -- 8.54 1671 2.2 August 82 59 70 -- 7.39 I518 2.0 September 77 54 66 .02 5.83 1381 1.9 October 80 47 64 .07 5.50 1322 1.8 November 77 43 60 1.47 4.26 1534 2.1 December 70 36 53 -- 3.31 1389 1.9 Year 73 48 60 12.70 64.25 20521 2.3 1931 January 68 40 54 3.82 2.89 1382 1.9 February 68 45 56 2.28 2.74 1378 2.0 March 76 42 59 .03 5.78 1830 2.5 April 76 49 62 2.68 6.02 1736 2.4 May 77 56 66 .67 6.89 1781 2.4 June 81 56 68 .07 8.05 1670 2.3 July 85 64 74 — 8.90 1656 2.2 August 84 62 73 .43 7.46 1415 1.9 September 84 55 70 .29 6.21 1201 1.7 October 79 50 64 .09 4.70 1121 1.5 November 68 42 55 1.69 3.09 1223 1.7 December 63 37 50 4.70 1.99 1136 1.5 Year 76 50 63 16.75 64.72 17529 2.0 1932 January 61 37 49 2.04 2.38 1335 1.8 February 62 40 51 4.53 2.73 1371 2.0 March 69 41 55 -- 4.98 1510 2.0 April 72 42 57 .35 5.86 1659 2.3 41 water by saltgrass, wire rush, willow, Bermuda grass, tules, and cattails grown in tanks with different depths to ground water. Study of soils and soil-moisture conditions in the lower Santa Ana River Valley led to selection of a plot in a level 10-acre field 4 miles west of Santa Ana and about 7 miles inland from the Pacific coast. The field was free of windbreaks and shade, and was generally suitable for consumptive-use studies. Soil was of alluvial origin, classified as a fine, sandy loam, grading into a coarse, yellow sand at a depth of 6 to 7 feet. It lacked humus and contained a small amount of alkali. An ample supply of good water for use in the experiment tanks was found at a depth of a few feet. The climatic conditions at this point are representative of the coastal climate of southern California. Summers are warm and dry and winters are moderate and wet. Coast- al fogs are frequent, tending to modify evaporation from water surfaces and transpiration by plants. Figure 5 is a sketch of the station showing arrangement of tanks. Saltgrass. --In all saltgrass tanks water tables were held at definite predetermined depths by means of Mariotte supply tanks. A general outline of the tank set-up is shown in Figure 1, and a description of the Mariotte apparatus is given on page 19- Fif- teen soil tanks of the double-shell type, each 23 inches in diame- ter and 6 feet deep, were filled with a fine sandy loam soil. In 12 tanks the soil was captured in place undisturbed, but in three others it was loosely settled in water. Six tanks of undisturbed soil had an original crop of saltgrass on the soil column with root systems fully developed. Later in the investigation salt- grass was transplanted into all other tanks so that eventually all tanks supported saltgrass growth. To reduce the hazard of inaccuracies which might occur in a single tank the entire group was divided into sets of three, each set having a different depth to water. In four sets consumptive- use measurements were made with water tables at depths of 1 , 2, 3, and 4 feet respectively. A summary of the data obtained from the 42 y 50 Feet 12'— Tool Shed '^■•ifc.=--i^^^' iThermometer 2 0"-0=--------^ I ShiBlter 4 o=-0---------0 0=^^--0""0 13 X North 5 0---C1^=^-------0 0-= ---"0=014 « 6 a----a=------- ---O O — ---0----0 15 *- 7 0----0^ ^o o. o. \ 21 0 220 Gage • o 2 9 0--O-----------O I 0 0--^ar^3=^:.0 1 1 o=o-^=^--0 1 6 O 23" Evaporation Tank 17 O Ok 220^ 23 V . Tules I80 Oil Tests Well 19 WiMows Evaporation Pans 025 J3 © Wire Rush Anemometer X X-— — X X X 50 Feet FIGURE 5.-- Plan of evaporation station near Santa Ana, Calif, 43 four sets appears in the following tabulation, which, represents the 3 years 1929-30 to 1931-32: Average depth to water table Vater used Inches Inches 12 42.76 24 1/35.31 36 i/23.79 48 13.37 Saltgrass is an indicator of ground water, but this inves- tigation has demonstrated that its consumptive use is not exces- sive when compared with water requirements of many other plants. As the depth to water increases consumptive use decreases. Thus, at a depth of 1 foot the quantity of water used in 1 year equalled 42.76 inches; at 2 feet, 35.31 inches; and at 4 feet, 13.37 inches. The depth-use ratio plots almost as a straight line. In most saltgrass areas in the Santa Ana basin the depth to water table exceeds 4 feet and the average seasonal draft on the ground water is not excessive. Monthly and seasonal data on use of water by saltgrass in the Santa Ana River basin are given in Table 3. Wire rush. --Wire rush ( June us balticus) was transplanted into a tank in which the water level was held at a depth of 2 feet. With a plentiful water supply close to the roots, growth became dense and the demand for water increased in the second year to a total of 13.75 inches for the month of July. For the 12-month period ending November 30, 1931, the annual consumptive use of water by wire rush was 93.58 inches. Wire rush thus used more than 2.5 times the saltgrass requirement. Monthly use of water by wire rush is shown in Table 4. Willow. --Investigation of the consumptive use of water by red willow was begun at the Santa Ana station in 1930 and contin- ued for two seasons. During much of the second year, however, the willow was in poor condition and early in the season became partly defoliated. For this period consumptive use data are 17 For 11 months only; May omitted. 44 ( C\) C\i (V CM f\J C\i CM rH CVJ I CM CVi rH O O -:fr^r^ r^ \CO c^ O O to 00 to C-~OJ vO n-\nAr^ r^ -t n-\ CM ^5) CM CM ^^ r^ I O O ^O r r^ CO p-> O O OrH 1-^ \0 f*M/\0 O CM C^ C^ r^ n-Nt^CM CV t^rH c^CM r^ r^ p^ c^ ^*^ r^ f*>r^r»^ r^ -J- f^N _^ f'Nr^ r^ f^ \0 u^^D vjD -*tO r -d-J-r to r-l] XI ^ O 1-5 0 o ^~-,^^o CM CM iH CM a, o -p ^ ® -p cd (0 Q S -P r^ (H CM f^ r^ ^ r^ r^ ^ 45 TABLE 4 CONSUMPTIVE USE OF WATER BY WIRE RUSH IN TANK AT SANTA ANA, CALIF., 1930-32 Year Month 1930 1931 1932 Inches Inches Inches January- __ 2.65 -- February — 2.96 1.58 March — 6.78 4.11 April — 7.76 8.55 May- — 8.62 -- June — 10.30 -- July — 13.75 -- August 5.74 12.70 -- September 5.43 10.73 -- October 5.68 8.25 -- November 5.03 4.85 — December 4.23 — — unreliable and are omitted from present consideration. The transplanted bush consisted of a single clump of 20 stems, each from 1/2 to 1 1/4 inches in diameter, growing from the same root. Their average height was 7 feet. The tank in which the bush was transplanted was 6 feet in diameter by 3 feet deep. Water table was constant at a depth of 2 feet. The drip line was approximately the same as the tank perimeter and consump- tive use was computed on this basis. The general appearance of the bush is shown in Plate II-A. Willow is a user of relatively pure water and normally does not grow where alkali salts are in high concentration. Neverthe- less, some salts were present in the willow tank soil. Regardless of this, the willow bush produced a thrifty growth which consumed 52.70 acre-inches of water in 11 months, as represented in Table 5. The relation of consumptive use to evaporation from water surfaces in the Santa Ana Valley (Table 44) indicates that water consumed by willows grown in isolated tanks exceeds evaporation from a Weather Bureau pan in but a single month of the year and averages 92 per cent of the total evaporation from June to October, 46 TABLE 5 CONSUMPTIVE USE OF WATER BY WILLOWS IN TANK AT SANTA ANA, CALIF., 1930-31 Year 1930 1931 Inches Inches 2.00 — 3.92 -- 5.72 3.28 4.76 4.99 4.48 7.34 -- 7.80 __ 6.63 — 5.36 -- 3.54 — 2.12 — Month January February March April May J\me July August September October November December inclusive. Since these measurements were made in the open, away from other brush or similar growth, this average probably is greater than would be obtained under normal growth conditions. For the 11 months, indicated loss of water from the Weather Bureau pan was 63.11 inches, which is the equivalent of 44.2 inches of evaporation from a broad water surface. It appears, therefore, that tank-grown willows under these conditions consume a greater quantity of water than is lost from an equal area of water surface by evaporation. Bermuda grass . --Bermuda grass (Cynodon dactyl on) is a per- ennial with long creeping jointed stolons, often several feet in length. It spreads largely by both stolons and rootstocks, al- though it also seeds abundantly. It is found in many localities in exposed places but not in shade. Bermuda grass is not neces- sarily an indicator of ground water as is saltgrass, but like other plants it makes better growth with increased moisture. It is frequently used for pasture and makes good feed for stock. For investigation of consumptive use of water by Bermuda grass an experimental station was established 1 mile east of San Bernardino, in the upper Santa Ana River valley, about 50 miles 47 PLATE II iP^ A. Willows 6 to 7 feet high growing in 6-foot diameter tank at Santa Ana, Calif. B. Alders in Coldwater Canyon between middle and lower controls, kS above the Santa Ana station. The plot was in a level field at some distance from buildings and had good exposure. Climatic conditions represent those of the interior portion of southern California. Summers are long and hot. Winter temperatures are lower than in the valley at Santa Ana, and rainfall is greater. Records of temperature, wind, and rainfall are shown in Table 6. Soil in the experimental tanks, classified as Chino silt loam, was taken from the station grounds. Ground water was with- in a few feet of the surface, yet there was no indication of al- kali in the tanks after 2 years of operation. The station re- ceived artesian water from the city supply. Tanks in which Ber- muda grass was grown were set in a large field of the same growth to provide normal surroundings. As a part of the Santa Ana investigation, four tanks at San Bernardino were filled with undisturbed soil in which was growing a good Bermuda grass cover with fully developed root systems. In two tanks, the water table was maintained at a depth of 2 feet and in the other two at 3 feet, the water table being regulated by Mariotte apparatus. Grass growth was dense and several inches high. The average annual depth of water used by the Bermuda grass having water table 2 feet from the tank surface was 34.37 inches, while those having table at 3 feet used 28.19 inches, which does not differ greatly from the water used by saltgrass. Monthly data on consumptive use of water by Bermuda grass are given in Table 7. Tules and cattails. --The round-stem tule or common bulrush is a perennial plant with a round dark green stem growing to heights of 6 to 10 feet. It grows densely in shallow water along stream channels, in swamps, and drainage ditches. The triangular bulrush (Scirpus olneyi) is also an aquatic plant. Its stems are three-cornered and grow often to heights of 6 feet or more. Cat- tail, sometimes classed with tules and of similar height, is a perennial marsh plant with flat leaves and cylindrical head which is filled with thousands of small cottony seeds. 49 TABLE 6 METEOROLOGICAL DATA AT SAN BERNARDINO STATION, SAN BERNARDINO, CALIF., 1929-32 Temperature Mean Mean Evapora- tion from Wind : movement Month and maxi- mini- Precipi- a Weather year mum mum Mean tation Bureau pan Total Average Miles 1929 °F. °F. °F. Inches Inches Miles per hour May- 82 47 64 -- 7.78 -- -- June 88 50 69 0.12 8.89 -- -- July 95 57 76 — 9.78 -- — August 98 60 79 -- 8.81 -- -- September 88 55 72 .53 5.69 1012 1.4 October 85 46 66 -- 5.58 1183 1.6 November 80 34 57 — 4.98 1589 2.2 December 75 33 54 — 3.82 1255 1.7 1930 January 61 36 48 4.71 2.32 1434 1.9 February Ik 38 56 1.06 3.46 1357 2.0 March 70 41 56 3.99 5.02 1864 2.5 April 77 45 61 1.33 5.38 1143 1.6 May 74 43 58 1.76 5.50 947 1.3 June 86 52 69 -- 6.59 900 • 1.2 July 96 54 75 — 8.08 679 .9 August 95 57 76 -- 7.54 879 1.2 September 84 50 67 -- 5.47 895 1.2 October 82 44 63 1.24 5.21 1086 1.5 November 77 39 58 2.08 3.77 1257 1.7 December 72 27 50 -- 2.63 — — Year 79 44 61 16.17 60.97 1931 January 68 35 52 2.15 3.10 -- -- February 66 40 53 3.73 3.06 -- -- March 76 37 56 .60 5.77 -- -- April 79 44 62 2.73 4.89 -- -- Ifey 83 52 68 .89 6.79 — -- June 86 53 70 .06 7.38 748 1.0 July 98 62 80 — 8.92 798 1.1 August 95 61 78 1.57 8.06 890 1.2 September 89 51 70 .24 5.81 816 1.1 October 81 47 64 1.14 4.81 797 1.1 November 69 37 53 3.17 3.48 1177 1.6 December -- -- -- 3.59 2.10 1013 1.4 Tear 81 47 64 19.87 64.17 1932 January _- — — 2.61 3.13 902 1.2 February — -- — 5.99 3.13 1168 1.7 March -- -- -- .20 5.24 1391 1.9 April -- -- — .72 6.28 1391 1.9 50 u CO Q> si ^ ^-1 +^ s O o 0 rvvD to o rv :^ rH CO trl (U +^ x; C) o H C M CO X3 () o s d M a X3 U (D ■P 0) rH Oi O 4J ^ 0) +J cd cfl Q S -P CO +J a> Q ^ 0) o cn (=1 M CD • 0) b( x! ;3 o = 0 rH ^ ::l o *^ S H CO a) Q) ri -d ;^ o Ho 0 M vO t>-OsO -d-O rH to 1 r^ r^ CV C\i CNJ (>i C\i r-{ CNi r\j to -;}■[> -4- -ct-tO rHtO to r^ r^fM r^ .H r^r^r^r^ vD Lf> ^r^u^ t^ L/^vO^£) vO MD O r^ r^ r^ CV\0 C\J 0^ r^ -J- O M ' a O cd S Eh O O rH rH rr\ r^ pr>j poj rH O O rH rH oA oA r^ (-^ ooo o O^ CTv O O r-i r-i r-{ ,-t ON o rH ooo o rA r-{ r-\ <-\ o o Pi H H . 0) qJ o ■51 CI a O > W H a o Eh I m •pI (d (1) o It s O CV OJ rH rH rH 1-1 C-^tX) rH ,H to r^tO >JD u-\ to vO -d- CO ^^ irM/\ ^0^0 rH <^ CNJ r^ rH ^ -* O Oi Oi sO ir\ O t^ r^O t^ I I r^O -4- ON • ••11.. . . rH to r^ uMr\ vO rH f^ cv CO ^o i/N c\j Lr\ u^\o r^ i^> to to rv -4- C^ r^ c^ r^ CM^ O CV t^ CNJ vr\-d- r^-J- (Nior^u^^Dco cv r^ r^i^ r^r^ O^OOrHrHOrH 0,H C\i r^ r^ r^ r^ r»> f^ r^ n^ J^ O rH m a +J (11 (ji CI ^ CO a) o a rt -p 4-> •H (0 (D u a crt (D -H (U j:^ ■« (h p u CO O (d ct (1) <-\ U (-1 ^ crt iH (D a o (D W •p J3 O +j 0) cl di rH •H ^ 03 S) Oi +3 O c^ a •H fl) iH u e Di ) OJ +J m (I) (b 0) xi Q e^EH r-ilcvV^ 53 protected swamp areas. They are often found directly exposed to sun and wind in narrow ribbons along stream channels and drainage ditches where exposure is nearly similar to that in isolated tanks. Under such conditions it is reasonable to expect that consumptive use of water is somewhat less than from exposed tanks, but considerably more than from larger swamps. Midway between Santa Ana and San Bernardino, consumptive use of water by tules was ascertained in connection with a study by the United States Geological Survey of the flow of the Santa Ana River. As the station was isolated and daily visits were not practicable, recording devices were attached to both tule tank and Weather Bureau evaporation pan. From the records, hourly rates of consumptive use and evaporation were obtained. Samples of these are plotted in Figure 6, showing also air and water tem- peratures. t. u: •2 j; .10 120 100 80 60 A.M. P.M. 1 1 1 1 1 I //\ //'\ A //"\\ / ^%\ A f\ i^ "/'' > 1/ \j/ \ kj-' ^ ^jL-'Water' 0 \ •~ / ^- ^ L 1 ^Pan ^L ^ jfc J^l . Au August FIGURE 6.-- Hourly rate of use of water by tules, evaporation from standard Weather Bureau pan, and air and water tempera- tures, at Prado station. There were periods during the early morning hours when the loss of water was too small to be recorded and evaporation or transpiration during these hours is shown as zero. Characteristic of both evaporation and transpiration is the daily increase or 54 decrease with rising or falling temperature. The minimum rate occurs near sunrise and the maximum in the afternoon. Consumptive use, in the exposed tank, is greater than evaporation and responds more readily to sunlight and changes in temperature. The rate of evaporation increases slowly until the water in the pan has been warmed by the sun, while consumptive use increases more rapidly, comes to a peak sooner, and declines more quickly. In other words the plant is more sensitive to the factors causing water loss than is the water in the evaporation pan. On the morning of August 28 temperature was less than normal, and a light rain occurred shortly after noon. The effect of the rain in deferring the morning increase in consumptive use and in evaporation until about 2 p.m. is noticeable. The precip- itation caused a small decrease in the rate of evaporation until its effect was overcome by rising temperature. In general, the highest air temperature occurred at about 1 p.m. to 2 p.m., while the highest water temperature occurred about 2 hours later. The same interval also is noticeable in minimum temperatures. Obser- vations elsewhere have shovm the highest consumptive use of water by tules occurs approximately at the time of highest air tempera- tures, although such is not the case in this instance. Coastal winds at the Prado station, in combination with high temperatures, are responsible for a continued increase in both evaporation and consumptive use until midafternoon and a higher rate of loss than at Santa Ana. The observed annual loss from the exposed tule tank reached a total of 251.3 inches or 325 per cent of the evaporation for the same period. The maximum daily loss was 3.6 inches. Excessive rates of consumptive use of water by tules in an isolated tank were found also at the San Bernardino station. This tank was set in a Bermuda grass field. Vhile the tule growth was stunted by exposure, the water consumed amounted to 170.88 inches in 11 months. In southern California records are taken for each month of the year; although tule and cattail stems die in the 55 winter months, evaporation from the soil and water in the tank continues in small amounts. Monthly records of consumptive use are given in Table 8. It is again emphasized that none of the tule tank records is applicable to field conditions without ad- justment . The excessive use of water by aquatic plants growing otherwise than in their native habitat led to investigations in the Mojave Valley to determine the difference in consumptive use by tules growing naturally in swamp areas and other tules trans- planted into exposed tanks removed from the swamp influence, and to establish a relation between consumptive use by natural swamp growth and evaporation from water. Both objectives are important if tank data are to have value, particularly if estimates of con- sumptive use are desired in other nearby localities where only evaporation data exist. With the relation once established, it is possible to apply it elsewhere within the same climatic area. Discussion of the Mojave Valley investigation appears on page 59. Brush. —/--In arid and semiarid regions practically all moisture from precipitation is held in the top few feet of soil where it is available for use by plants. This is the condition in the foothill area of the Santa Ana Valley. Vegetation on out- wash slopes may be divided roughly into two groups: perennials having a woody structure, such as brush and shrubs; and annuals, as weeds and grasses. In this region precipitation occurs during the winter months, and the summers are long and dry. Contribu- tion to underground water is limited to periods of heavy rainfall when the soil is moistened to field capacity below the root zone (field capacity being the amount of water retained in the soil after excess mobile water has drained away and the rate of down- ward movement has materially decreased following an application 17 Field investigations with dry-land brush and grass and weeds in the Santa Ana River Valley and with tules in the Mojave River Valley were conducted by Colin A. Taylor, Associate Irrigation Engineer, Division of Irrigation, in cooperation with the Division of Water Resources, Department of Public Works, State of Califor- nia. 56 of water from rain or irrigation). This condition seldom occurs, so that most of the moisture received is absorbed by plant life. Without replenishment during the summer, soil moisture is de- pleted by plant use until there is a deficiency at the beginning of each rainy season. In connection with rainfall penetration studies initiated in southern California in 1927, various shafts, tunnels, and special plots were prepared for soil-moisture investigations from which it was possible to determine the water consumed by native brush and by various weeds and grasses. Soil samples were taken to depths below the limits of root activity, and the moisture content was determined by standard practices. The limit of rain- fall penetration, depth of root activity, amount of moisture con- tribution to underground -water supplies and evaporation-transpi- ration losses chargeable to consumptive use were determined for various soil types. A 3-year investigation of natural brush plots on outwash slopes indicated that about 19 inches of rain fell before any material moisture passed beyond the limits of the root zone. The brush varied with location but included chamiso, sage, squaw berry, scrub oak, cactus, and yucca -- all capable of existing on a small water supply. During the 3-year period rainfall at the various plots ranged from 12.66 inches to 20.90 inches, practi- cally all of which was used by the brush cover. During this period soil moisture within the root zones was often below field capacity. Under these conditions rainfall and consumptive use are equal, assuming no run-off. In years of greater rainfall, however, or of rains falling upon soil filled to field capacity, some water passes beyond the roots to the underground basin. Under the latter condition consumptive use might increase because of in- creased transpiration opportunity. Results of brush-cover inves- tigations, shown in Table 9, indicate that all precipitation in this area is consiimed by the dry-land brush and that with this amount of rainfall there is no penetration to the underground 57 U > ^ >-P 3 cd (D (P +j a bD a m •H (B a & o H o cd (D tn C! -H f34 ■H t:* t>j ;3 0) O H +j o +3 -p m ^ •H rH SU M d d iH 0) -M o qn O M td -H o o o ■in o a ^ 1=> 1 t^to ON Ovo CO r- o o to 1 •H PI en a o 0) •rH -H n O -P o (D Cd i=! fH-P M tin rv?lcN?l a •H o -o •H fH ■P Cd Cd 0 o fM C) Q) h-1 pq O O OvO o o o Lf^ UMJ-\ O O rH iH CV C\i C\i ON On to CO O CNJ O O CO o CM -d-o i>-nd toco r^CV CV H rH H iH s H cd ^ o d rH Ti •H d u >> cd Oi t3 CO CO s=l rt cd ro >. >> CO o H X3 H H >^ (D t:! M >^ > (P o cd cd +J o H U d « O O i • (B dH O Qt !>> a, H a 7i (D cd CO (=: o o a a d Pi 3 o •H H O EH >i XJ •H -H d tn t> +J -p cd (d (D Cd d o d p -p o tn CO CO :3 H S O to oo (V CV r^ to ON 00 On Oi Ol Oi C^ CO ONO C\i CM r^ O CO O Oi CM cd +J u C0 ON CV CV C\J OnOOn 1>-00 I>-CO C\i CV Oi CNJ On ON ON ON C^CO ON CV CM CM OnQnOn CM CJN o-to CM CM CJNCJN 58 -d 0)0)1:) CO > CJ CO :d -H nj CO 0 -P t:) Jd fH cd 01 (D o 0) ri W (D rt +J cd ^ H cd !>5 f^ 13 X) bD 1 CC 0) 0) CO t>- •rH 0) rt s o 0) UA O O u^ OJ ft ft-H o Nl ^ t^ O O C\i O •H +J rH o r^ o (=1 td 0 p> a o cv 0) O fH ^ o M ^„^ " ^( -H +J o c^l ^1 ^ Ph +J ^1 o F-H H 1 ^ rH I5h -r-l 0) ■p rH O CO 0) fH d •rH CO •H-c) !>> ;3 0) o 0) o ^ +J O -P -p m iH 1 1 1 pq •H rH c! CO d o sO pT-T a rH 0) -H O . > d 0 TiJ Tl a o d d d u p> •H cd (d O en pq CO CO O d d •H o XJ •H fH +J Cd cd td Cd d M M o fH d 0 o o d o 0 o ■H •H •H o ^^ CQ a 0 fH fH 01 ^ Cd CO Cd d o CO +^ +3 o cd ;:< d d d 0 CO o ^ o o o to oo C\i f\J r^ I I I {XO CJN (M cv cv cr^a^c^ r- [> o t> >. fH • crt d :=< C) u !>> JCJ d 0 (Ti • (i< O CO (i) M.H =< d •H H •H > cd T=! 0 > d w 0) T) U 0 m o +J Ti (H fH ^ a o H-> •H o :3 4J Pi CO M rHiCVM 59 water table. Grass and weeds. -^--On grass and weed plots some penetra- tion beyond the area of root activity may be expected on the coarser soil types when precipitation exceeds 10 to 12 inches. Here again the distribution of seasonal rainfall is an important factor in deep penetration. A contributing factor also is the density of growth. No run-off occurred from either brush or grass plots. In a majority of plots consumptive use by grass and weeds equalled the precipitation. Use of water by grass and weeds under similar conditions is slightly less than by brush and ranges from 12.58 to 15.49 acre-inches per acre. The factor of rainfall likewise limits these values. A summary of the grass and weed studies is shown in Table 10. Mo jave Valley, California — ' Tules . --Studies on the Mojave River at Victorville, Calif, were undertaken in 1930 with triangular-stem tules transplanted into 2 tanks set deep in a tule swamp and in a third tank nearby which was exposed to surrounding desert conditions. Evaporation from a Weather Bureau pan and meteorological data were obtained. Tule tank No. 1, 2 feet in diameter by 3 feet deep, was set in the ground in an open space removed from the swamp influence to which other tanks were subjected. Tanks Nos. 2 and 3, surrounded by dense swamp growth, were 2 and 6 feet in diameter respectively by 3 feet deep. Figure 7 shows a sketch plan of the Victorville station and the general arrangement of supply tanks and soil tanks . Under such conditions data obtained from the swamp tanks represent actual swamp consumptive use, and it is possible to establish a relation with exposed and isolated tule growth and also with evaporation from a Weather Bureau pan. The investiga- tion continued through 1931 and 1932. TJ See footnote 1, p. 55"^ 60 Tank 3 ^^^Top of bonk ' V ^__-y '»-»■- § Thermometer Supply tanks □ Anemometer Evaporation ^ pan Rain gage Q Supply we I'O Sfrefc Edge of swomp \ \^"PP'y ^^"^ Q Ground water ^rs. well Tank I 61-0"- FIGURE 7. — Plan of Victorville station. The highest consumptive use occurred during July, averag- ing 14.13 inches in depth for the 6-foot tank protected by sur- rounding swamp vegetation as compared with 63-38 inches by the exposed 2-foot tank. No material difference in the use of water was found between tanks of different size in the swamp. The larger tank is preferred as providing greater opportunity for root expansion and maintenance of soil fertility. A condensed summary of evaporation, consumptive use of water, and meteorolog- ical data for the 2-year period is presented in Table 11. For this period the average annual depth of water used by tules in the 6-foot tank in the swamp was 78.45 inches as against 272.24 inches by the exposed tank, clearly demonstrating the ef- fect of unnatural exposure upon consumptive use. The second ob- jective of the investigation was to determine the relation of consumptive use to evaporation from a Weather Bureau pan. During the 2 years of study the average annual consumptive use was 78.45 inches, or 95 per cent of the evaporation. This relation is not constant but varies throughout the year from a maximum of 122 per cent in September to a minimum of 57 per cent in March. The conditions of evaporation from a Weather Bureau pan and from a lake or reservoir are so dissimilar that a reduction 61 -ON O M re! E-i Pi Pi O rH fL, (^ 0 u f^ m 3 01 0) o U nH j:5 (1) •H > ?: «H <: 0 qJ rH CO 01 (D +J rH o •H tH S s a a I (=: -H 01 « a (D CO P s a a 0 0 ti< CVHOJCVCviiHrHrHrHnHrHnH tX)OOtOsOMDi^^-:tOC--0 LrNOCOrH-±ON-4-rH-^C\iOCV -4-CVNOCOt>r^C\JrHOOtOrH piM vOOO-J-CVnO-cJ- f^MD xO vO C^ O I C\i OJ r^ r^ ^ -^ iTNiTN -J- r^ c\i Cvi pt| (M u^ O -4- ,H MD [> -4- to \0 vO CV O I uAU-\^-C-^tO to OM3NtO C^vO "^ C\irHC-iJ^CO-fV C^vO uAsO tOOrH.HCVO\Dl>- 10 tn ;=! 0 O a 0 ffl Ci<-H O ^ 0 01 -p l^ -p tH > cC -ocvtocvtocv-4-r\JO CVf-f>\£)i>-ONO (M O ta ir\r^(M , . u a 0 -p H +i 0 ro 0 0 ^ a-tOrHr^OCO-*-J- O iHr^r^iJ^tOO-^-CNiOuACNiM -d-tO\0^ ^ rH [>-[>-t>.H UACV r^oc^ir^r^cvf^co^Hf^o^H Hr^Lr\tOnH-d--4-OE>--^f^CV rH rH rH rH-4-rH^CVI>-tO-J-tOtOrHUA tOUAMDCNisO-jT'^uM^cVvOr^ cNi r>; ^ r^ C-- 1^ r^owo itn-j- c\i rH r^sO >^-4-C\i >> 0 tK tl >i U ^ M 0 0 f-t ol 4J a 0 J3 JD ta 0 Si r-i tQ0x>aa 3fHO-H 0t>);J+3O00 !3X)fH^i>>c!rHtlD Qa4^ > O 010010,01:3:1(30000 i-o(x-3'-^ 0) O fH o OiC ID O O CO (D tH fn-H ^ cn (D 0,-P O 3 fl^ (D CO CO (D a I p cd •■-( CO 0 o: d o ■H O -iH p f^ O -p m o W 1-1 P >! cd £1 :3 u I a CO (u :3 o o £1 (d a-H a p (D c CO P O CO fn cd > CO Sh (B ;3 o. Cq fH (in :3 m bi - D CO CO > &X (D H o d X) D tH CO o n UA vO sO sO ^O s 0) a CO CO cO (0 CO CO cO cO P> P p P fl rt C CJ cO cd cO cO CO CO CO CO p> :3 P ^ p> :3 CO p> CD p CD -p tn a fH a fH a CO (D CO 0 CO 0) nH P> rH p ^ p 3 m :3 rH CO :3 CO bO M-H M Pi T) a CO X) a Td CO a CO p a CO rt •iH d -H p 0 •H ;3 ^H O fH Cd o fH o EH a Eh O « EH a !l! rH o Cd •H fH p 0 tt) ■P M Cd •H 0 p (0 fH 0) 0) > TZ) d rt •rH :3 0 9< r-i a r-i cd •H & > CO t-l o f3 p> •rH O •rH rd > Q) CO 03 (d >^ •H a p> •H . cd t:) fH CO 0 O (D p Q p -H (D p >» 00 ■f-H ^ 0) o (D (D P CO 03 d ^ 3 03 O 0 03 > > U •rH -H 03 P P> Q, Q, a cd o o 'Ki Ti >, cd •H fH ;3 a 03 P a CO ^ O X3 03 O O |iH rHlcvlr^l 64 of the sun by surrounding grass. Crop tanks in bare fields may have a somewhat higher rate of water use, but data bearing out such a conclusion are lacking. No definite figure is available for use as an adjustment factor for willow or other brush grown in tanks. In dense growths of brush the effect of sunlight and wind is modified by surround- ing vegetation and consumptive use under such conditions will be less than by isolated growth in field or tank. Considering dif- ferences in willow distribution it is evident that an adjustment factor is not a constant, applicable to all conditions, but a variable depending upon density and size of brush area. Owing to present lack of evidence, any factor selected must be only an es- timate. For willow growth in the Santa Ana Valley, where such growth is partly in solid blocks of brush and partly scattered, it is estimated that consumptive use varies from 75 to 100 per cent of consumptive use by willows grown in exposed tanks. A tentative factor of 85 per cent is adopted. Use of water by wire rush grown in a tank at the Santa Ana station exceeds that of any other growth except tules and cattails. While the tank was not set in a field of similar growth, it was surrounded by grass and weeds. It is possible, since the wire rush did not grow in its natural moist-land habitat, that change of environment was responsible for the high use of water, but it seemB more probable that an ample water supply close to the sur- face and an unusually heavy growth were the direct causes. A summary of tank investigations showing estimated adjust- ment factors and consumptive use of water in moist areas is pre- sented in Table 13. 65 Td m (0 1 -cf 03 +J t>5 to iH 0 cd ^ +j a d W -H ^ 1 -p +J tH c (0+3 0 0 3 Cl +^ o •■-5 0 0 ■o 0 cd tK <; iH 0 FM o o o o o o o o rH (H ,H ,H O O O O 1 CO iH >5 CO >J 03 (0 ^ +0 d a 0 3 0 O cO xi C 0 tsD-H +J o d m 0 +:> a cd 13 > a M •H ^ 0 U)£i u 0 m 03 +J 0 rH 0 tn p, O +J ^ ^ 0 0 -P CO ttJ o > t:) & -P a O M 413 +j -d m +J o tn si t(0 o c 0 ^1 Pi 0 ba ^ o Ti m a r-i CO -H cd 03 +3 0 +J rH 03 ;3 o EH o >. fl t:) 0 •H drH -O 03 -H tn 03 03 03 > •3 0 0 > m 03 03 +J -^ a a o «i 03 s CO CO 0 tH > o 03 +J •'-5 O O 03 Si-i -C) +.5 d d 03 0 03 +J d 03 oJ 'd ■P 03 d 03 0 CO Si E-i d 03 03 ^ -P § 0 ■p Q •H :3 03 03 ■P 03 +J 0 03 a O -d d d 3 o3 -P f-t o ^^ 03 rH (in ■P TS 0 Tj •H rH 0 rH > XI +J rH -H 03 03 03 t:) E-i a d O U Xi a-p O 03 +3 Hh ■o d 03 0 & tjD 0 :3 03 0 d o t-i 0 -H a 0 ^( 03 3 03 03 XI rH OrH 0 +J 03 (h o 03 g 03 d -H 03 03 O +J 03 ■p -d d 03 0 03 t:) tS o 0 d T=) 0 03 Ph 3 03 0 0 03 Q( O XI >. d H 0 O M r-i -J- \a3 Vi\ h1> ooi) 66 Temescal Creek, California — ' The effect of moist-land vegetation on depletion of stream flow is well known to hydrologists , despite a scarcity of publish- ed data. Engineers have long observed diurnal changes in stream- flow records which are attributable principally to consumptive use of water by vegetation on adjoining lands. It can be shown that these fluctuations may be correlated not only with transpiration and evaporation but also with air and water temperatures, and that minimiim flow follows maximum transpiration. Canyon- bottom vegetation. --A brief opportunity for this type of investigation was presented in a section of Temescal Creek, near Corona, Calif., in April and May 1929. A reach of creek bottom, 2,100 feet In length, was selected. The total area was 12.8 acres of coarse gravelly soil supporting a dense growth of brush and trees and other moist-land vegetation. Of the total area, approximately two-thirds was classified as wet land (that is, land with water at or above the surface) , while the remainder had ground water from 2 to 6 feet below. The investigation was limit- ed to a few weeks in the spring because prior to April water was pumped from the area and late in May the stream became dry. At this time of year there was no appreciable precipitation and no side inflow occurred from the adjoining hillsides. At the upper end of the 2,100-foot section the remains of a small masonry dam brought the underflow to the surface where measurement was made through a Parshall flume. At the lower end the abutments of a small highway bridge forced the creek into a narrow section where it was measured by a second Parshall flume. Water-stage recorders were maintained at both controls. At the lower end, the coarse soil permitted some underflow which was estimated as follows: By means of recorder charts at the upper XT The field investigation was made by Colin A. Taylor, Associ- ate Irrigation Engineer, Division of Irrigation, in cooperation with the Division of Water Resources, Department of Public Works, State of California. 67 and lower controls differences in flow between these points were computed for 2-hour intervals during a 10-day period when cloudy- weather, with traces of rain, caused periods of minimum evapora- tion and transpiration. On April 19 and again on April 20, evaporation from a Weather Bureau pan at Ontario, approximately 20 miles distant, was but 0.04 inch or the equivalent of 0.028 inch of lake evaporation. With this low loss from evaporation the consumptive use of water by vegetation in the early morning hours of the same period must have been exceedingly small. With evaporation and transpiration so low as to be negligible the dif- ference in amount of inflow and outflow from the area must neces- sarily be attributed to underflov/ past the lower control, which was thus estimated to be 0.14 cubic foot per second. All remain- ing differences above 0.14 second-foot can be charged to consump- tive use of water by the vegetation. A summary of results, given in Table 14, indicates a total loss of 12.9 acre-inches per acre for the 30-day period April 28 to May 27, 1929- This was three times the loss from a lake sur- face as indicated by Weather Bureau pan records at Ontario. Figure 8 shows the daily fluctuations in stream flow and the loss of flow due to consumptive use of water by vegetation be- tween the upper and lower controls. The effect of the advancing season in increasing the consumptive use is shown by the diver- gence of the lines representing stream flow at each point of measurement. Comparison of plotted temperature and rate of con- sumptive use by tank vegetation is likewise shown. TABLE 14 CONSUMPTIVE USE OF WATER BY MOIST -LAND VEGETATION AS INDICATED BY STREAM LOSSES IN TEMESCAL CREEK, CALIF. , 1929 1/ Rate of loss Loss of flow in Date Temescal Creek Day- Acre inches Week 1 Acre inches 1929 Second-feet Acre-inches per acre per acre April 16 0.010 0.24 0.02 April 17 .035 .83 .06 __ April 18 .026 .62 .05 __ April 19 .011 .26 .02 __ April 20 .024 .57 .04 -- April 21 .042 1.00 .08 __ April 22 .043 1.02 .08 0.35 April 23 .052 1.24 .10 April 24 .070 1.67 .13 -- April 25 .078 1.86 .14 __ April 26 .080 1.90 .15 __ April 27 .079 1.88 .15 __ April 28 .094 2.24 .18 -- April : 29 .105 2.50 .20 1.05 April 30 .118 2.81 .22 May 1 .132 3.14 .24 -_ May 2 .162 3.86 .30 — May 3 .156 3.71 .29 -- May 4 .163 3.88 .30 -- May 5 .154 3.66 .29 -- May 6 .152 3.62 .28 1.92 May 7 .150 3.57 .28 -- May 8 .176 4.19 .33 — May 9 .178 4.24 .33 -- May 10 .188 4.48 .35 -- May 11 .220 5.24 .41 — May 12 .234 5.57 .44 — May 13 .259 6.16 .48 2.62 May 14 .290 6.90 .54 -- May 15 .298 7.09 .55 — May 16 .298 7.09 .55 — May 17 .307 7.31 .57 -- May 18 .278 6.62 .52 — May 19 .268 6.38 .50 -- May 20 .267 6.36 .50 3.73 May 21 .297 7.07 .55 -- May 22 .298 7.09 .55 — May 23 .318 7.57 .59 — May 24 .330 7.86 .61 — May 2 5 .353 8.40 .66 — May 26 .347 8.26 .64 -- May 27 .343 8.16 .64 4.24 \J Area involved equals 12.8 acres. 69 k 0.8 1 1 1 1 control ^^^^'^ 11 ^:\/^^^^ VO-A-^^ 0.5 V \' 0.0 \ ^J ^ ^ a ^J % ^ \ r\ v/ \ r\ \ \ \ A . Lower A 1 - ' centre 1 \j I \ a "^ ^ ./' 0.3 0.2 0.1 _,^^v^^\/^^^''' /\JV^^ / / / ^/^i.J^i/^^^ ^ 15 16 17 18 19 Apr 20 21 il 22 23 24- 18 19 20 21 22 23 24 25 26 May 27 L-Tank shielded from sun 9> Q o /v A » . 1 \ rt A A A A H A A I /\ ^A .\AA y\i JvAJ \JU\ AjtjvjvsnEn A 120 80 60 ■ * 40 1 J A A A A A A A A A A rt A 1^ 1 A A /I /I A A A A ft A A ;\ I'l A A A A A \ J n i^ A A A /A V }\ i\ '\ Water in tank 1 CM 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 August FIGURE 8.-- Stream flow, consumptive use by moist-land vegetation, and comparison of rate of consumptive use by tank vegetation with air temperatures at Temescal Creek. 70 SUPPORTING TANK DATA The general data secured by measurement of consumptive use of water by stream-bottom vegetation led to further study of sim- ilar vegetation grown in tanks. Two tanks, each about 2 feet in diameter by 3 feet deep, were set in the ground near the upper control where surrounding vegetation was nearly representative of that in the entire area. Tank A was planted to tules and reeds, while small willow shoots were set in tank B. Measurements of use of water by the tank growth were carried on from October 1929 to June 1930 at this location. In June, tank B was moved 20 miles to Ontario and fitted with a sensitive automatic device for sup- plying water to the tank as it was consumed by the vegetation, and with a recorder for obtaining continuous hourly records of these losses. The willow shoots in tank B were not representative of normal willow growth because of their small size. In fact, they failed to survive the winter months and were gradully supplanted by swamp grass and weeds. Water was maintained at about 3 inches above the ground surface. The monthly use by vegetation in the tanks is shown in Table 15. TABLE 15 CONSUMPTIVE USE OF WATER BY SWAMP VEGETATION IN TANKS AT TEMESGAL CREEK AND AT ONTARIO, CALIF., 1929-30 Month and year Locat; Lon 1929 October Temescal Creek November Temescal Creek December Temescal Creek 1930 January Temescal Creek February Temescal Creek March Temescal Creek April Temescal Creek May Temescal Creek June Ontario July Ontario August Ontario Water used Tank A Tules Inches Tank B Willow shoots swamp gra s s , and weeds Inches 16.79 6.64 9-15 5.52 4.83 3.81 3.91 4.23 2.74 2.95 4.82 4.61 11.53 9.19 14.33 1/14.37 f/18.45 i//29.60 i/30.67 __ _- — 17 Not applicable to large areas without adjustment, 71 It will be observed that tank consumptive use of 14.3 in- ches for May does not differ greatly from the average swamp use of 12.9 acre-inches. The larger use should be expected on ac- count of the artificial conditions in the tanks. Moving tank B to Ontario in June placed this tank under conditions radically different from those inherent in swamp areas, and the consumptive- use records for June, July, and August are neither applicable to field conditions nor comparable with previous records at Temescal Creek. Their value lies in the chart records obtained and the opportunity presented for comparing the rate of consumptive use- of -water curves with the daily temperature curves shown in Figure 8. The maxima and minima of these curves occur respectively about the same time of day. The effect of consumptive use on ground-water levels is apparent on the stream-flow chart. Under normal conditions the draft on the water table following the peak of transpiration is shown by the falling side of the curve representing daily stream flow. At this time consumptive use exceeds the recharge of the basin and the water table is dropping. At the bottom of the curve, consumptive use and recharge are balanced and the water table begins to rise. During periods of maximum consumptive use, the recharge may not equal the daily loss, and under these condi- tions the dropping water table is reflected in lower stream flow. As sunlight and temperature so greatly affect transpiration and consumptive use by plants, the following discussion by Taylor (2) on the effects of insolation is applicable: PROBABLE LIMITS TO THE LOSSES ALONG STRE/Jl CHANNELS "The indicated loss of 12.9 inches in 30 days at Temescal Creek, together with still higher rates of loss from small isolat- ed tanks of swamp grovrth, has led to a consideration as to what the probable limits for losses in moist areas along stream chan- nels might be. The radiant energy received from the sun, or 72 insolation as it is termed, suggests certain upper limits to the amount of water that may be vaporized over large swamp areas. Average daily records of insolation are published in the Monthly Weather Review for stations at La Jolla, Pasadena and Fresno. The equivalent water of vaporization for the insolation received at Pasadena and Fresno for the calendar year 1929 is as follows: Equivalent water of vaporization Total annual-, / at 68 degrees Station insolation —' Fahrenheit Gram calories per Depth square centimeter in feet Pasadena l65,4l6 9.27 Fresno 169,691 9-51 Average -- 9-39 "This suggests that, if all of the radiant energy received from the sun were used in vaporizing water, it would be possible to lose 9-39 acre-feet per acre annually, as an average for the two stations, as the result of insolation. "Using the Fresno records for the period April 28 to May 27, 1929, we have the insolation as 20,467 gram calories per square centimeter and the equivalent water of vaporization at 68 degrees Fahrenheit as 13. 8 inches. This is for the same per- iod that the indicated loss from the swamp on Temescal Creek was 12.9 inches. It is likely, then, that the rate of loss was ap- proaching its probable maximum when the tests on Temescal Creek ceased, due to a failing water supply late in May. There is some additional supply of heat to the swamp area from the s\irrounding rocky canyon walls and from the strong draft of air flowing through the canyon. On the other hand, not all of the insolation received directly on the swamp area is used in vaporization. Some of the radiant energy is stored in combination within the plant tissues, some is reflected from the plant surfaces and part goes into heat storage and in part is again radiated back to the sky. 17 Direct plus diffuse received on a horizontal surface. 73 "The discussion of the receipt of energy, other than the vertical component from the sun, leads to a consideration of what the effect might be on very small patches of swamp growth. The extreme case may well be considered as an isolated tank of swamp growth two feet in diameter set in otherwise barren ground. The radiant energy intercepted by the plant growth in the tank must necessarily be a greater amount than the same area of growth in a swamp would receive because the isolated tank growth has a side exposure that in a swamp would be protected by surrounding plants, The analogy that might be drawn is that of a lens focusing the sun's rays on the restricted area of the tank. "Take the case of the two-foot tank used at Ontario in studying the correlation between air temperature and transpira- tion. The loss for the month of August, 1930, from the Ontario willow and reed tank was 30.6? inches depth. This is about two and one-half times the depth of water that could be vaporized by the insolation falling on the horizontal area of the tank. A partial explanation is that the tall growth in the isolated tank intercepts a much larger amount of insolation than the same area of growth would receive in a swamp. But in the case of the small tank, the heat energy brought to the growth in the tank by air movement also is relatively large. An experiment investigating this point was performed at Ontario on August 22, 1930. On this date, the willow and reed tank was shielded from the direct rays of the sun by a corrugated iron roof, eight by ten feet, placed just high enough to clear the plants and allow free lateral wind movement. The record of water loss is shown in Figure 8 (this bulletin) . The full line on August 22 is the actual loss with the tank shielded. The dotted line is the average of August 21 and 23. The values are: Loss August 21 1.296 Inches Loss August 23 1.274 inches Average loss for August 21 and 23 1.285 inches Loss August 22 0.778 inch (with tank shielded) 74 "The heat supply for vaporizing this 0.778 inch of water on August 22 must have come almost entirely from the moving air currents passing through the growth in the tank. "However, when a large swamp area is considered, there must be a rapid drop in temperature of the air as it passes through the swamp growth if it is to give up its heat supply at the rate indicated by the above experiment. As soon as the air is cooled to the same temperature as the plants there can be no further transfer of heat from the air to the plants. When this condition is reached, the energy for vaporization must come solely from insolation. "It may be expected, then, that small isolated patches of swamp growth will show rates of loss per unit area higher than that accounted for by insolation alone, but it also is probable that the loss from an extensive swamp area is limited to a value not widely variant from that indicated by insolation. "The inference is that in conducting tank work to gain data for use in estimating losses from field areas, that the tank should be set in a field of growth similar to that in the tank and the outside growth must completely surround the tank so the exposure of the growth in the tank is normal." Coldwater Canyon, California —' Canyon-bottom vegetation. --The mountain slopes of southern California support a growth of dry-land chaparral which must de- pend upon the immediate precipitation for moisture, but vegetation adjacent to small canyon streams is of a more water-loving nature. This includes such broadleaf trees and shrubs as alders, willows, sycamores, and California laurels, changing at times to coniferous types at higher altitudes. As evidence of their water-loving character these species are seldom found away from a dependable 17 The field investigation was made by Colin A. Taylor, Associate Irrigation Engineer and Harry G. Nickle, Assistant Irrigation Engineer, Division of Irrigation, in cooperation with the Division of Water Resources, Department of Public Works, State of California, 75 water supply. The effect of such vegetation on depletion of flow- ing streams becomes increasingly important as water becomes scar- cer and more valuable. Lack of data on consumptive use of water by canyon-bottom growth led in 1931 to an investigation in selected sections of Coldwater Canyon, near San Bernardino, Calif., to determine stream losses chargeable to this type of vegetation. The initial investigation covered a section of canyon 2,090 feet in length between elevations 2,300 and 2,500 feet, the average bottom width being 49 feet. The area comprised 2.36 acres of typical canyon- bottom growth. Within this area vegetation depended for water entirely upon the flow of Coldwater Canyon. Beyond the influence of the stream the vegetation changed rapidly from alders and sycamores to dry-land chaparral. During the second year studies were extended upstream to include also an upper canyon section immediately adjacent to the lower section. This lay between ele- vations 2,500 and 3,100 feet; it averaged 44 feet in width and was 5,875 feet in length. Thus in the second year the investiga- tion included nearly 8,000 feet of canyon bottom. The area of the upper section covered 5.89 acres of growth nearly similar in type to that of the lower section. A vegetative classification of both upper and lower sections, shown in Table 16, gives alder as predominating, with California laurel showing the next highest percentage of total growth. The under story consisted of scatter- ed grapevine, blackberry, poison oak, and fern bracken. Plate II- B shows alders growing between the lower and middle controls. Bedrock controls at the upper and lower ends of each sec- tion insured complete measurement of all water in the canyon. Parshall flumes were installed with water-stage recorders for the earlier records, but for greater convenience these were later changed to direct flow recorders. The small flow in dry seasons made necessary a modification of the Parshall flume that would measure accurately low flows in summer as well as maximum flows during spring floods. For this purpose the Division of Irrigation 76 +J 1 Oh d tH O iH (D O cd o a< d -p o o o u ^1 -H +D (D Ph -p Mh fH a -4--dT^f\iO oc\i-j--trvjvO-4-ooo (-^ r^ iH iH rvi r^ -J- -4" rH ^OrHrH-4-r<^tiOON^ tOsO O to r^vO r^ CAi ,H O-rH CV ■p 1 "iH d fH OrH CD o Cd o o< d +^ o o o fH fH -H -P 0 Ph +J (U u & CD CO 3 +^ CD a rH c^lPk r^UN CV r-i >> rH!>jCti-HcdcdOcDa(0 0.2I in. rain I 1 L ^^-^x ^^ \ A jTi A A \/ ^ \ / ^/ ^\( r V / \/ 1/ w 1/ 1 Vi 1 V 1 1 1 12 August FIGURE 9.-- Flow at middle Coldwater Canyon control. 80 sudden rise of the stream surface. The 13th and l^th were cool and cloudy, transpiration was low and there was little fluctuation. The 15th was again warm, transpiration increased, and the stream surface dropped. The daily loss of water from the stream in both upper and lower sections of canyon bottom is shown in Tables 17 and 18. These data are arranged to present also the average daily losses for each section of canyon and the average loss per day per 1,000 feet of stream bed. There was considerable difference in losses in the two growing seasons. In both years there was outflow at the lower control, hence never a shortage of water for the trees. The summer of 1931 had some light rain and cloudy weather, whereas in 1932 the weather was clear. On the other hand, in 1931 temper- atures were higher than during 1932, which would tend to offset the effect of cloudy periods. On the whole, there seems to be no reason why consumptive use should be greater in one season than in another. It will be observed also that consumptive use by trees in the upper stream section is less than in the lower section. This cannot be accounted for by density of growth as there are more trees per acre in the upper section. In the lower canyon, however, alders account for 81.9 per cent of all trees and shrubs whereas in the upper canyon they are 47.9 per cent of the total. In the upper section there is an increase in California laurel from 4.1 per cent to 26.1 per cent. It appears probable that the fewer alders in the upper section account for the smaller consumptive use. The consumptive use by canyon-bottom trees and shrubs from June to October commands attention. This is the period of maximum use, not only by natural growth but by irrigated crops as well. In estimating water supplies for irrigation a knowledge of the effect of consumptive use of water by alders, willows, and other stream-fed vegetation on depletion of stream flow is important to engineers. The study shows a maximum use of 13.7 acre-inches per 81 TABLE 17 CONSUMPTIVE USE OF WATER BY CANYON-BOTTOM VEGETATION AS INDICATED BY STREAM LOSSES IN COLDWATER CANYON NEAR SAN BERNARDINO, CALIF., 1931-32 1/ Loss of water from stream between middle and lower controls Day 1931 1932 of month Aug. Sept . Oct. June July Auf;. Sept. Oct. Nov. Acre- Acre- Acre- Acre- Acre- Acre- Acre- Acre- Acre- inches inches inches inches inches inches inches inches inches 1 ^0.55 ^.23 -- -_ 0.85 1.10 1.07 0.64 0.40 2 .76 0.22 -- .75 1.11 .97 .48 ..12 3 .60 — .31 -- .66 1.15 .95 .60 -_ 4 .78 -_ .42 -- .64 1.21 1.12 .70 -_ 5 .76 — .39 -- .68 1.20 1.01 1.00 -_ 6 .57 .74 2/. 34 ^.19 -- 1.07 1.27 1.03 .76 — 7 .65 .62 -- .83 1.22 1.28 .51 -_ 8 .73 .49 -- -_ 1.02 1.19 1.44 .64 -_ 9 .66 .40 .01 -- .96 .92 1.19 — — 10 .56 .37 .08 -- .92 .76 .91 .92 -- 11 .49 .55 .02 -- .96 .91 .86 .96 — 12 -- .57 .15 -- .83 1.01 1.01 .82 — 13 — .63 .31 — .61 .92 .97 .58 — 14 -- .22 .30 -- .94 .86 1.01 .85 -_ 15 -- .27 .35 — 1.05 .95 .95 1.01 — 16 2/:87 .47 ^.17 -- 1.09 1.08 .78 .76 _- 17 .42 _- 1.15 1.31 .61 .44 -_ 18 .97 .65 -- — .98 1.38 — .58 -- 19 .87 .25 -- -- .91 1.41 -- .69 -- 20 .93 -- — -- 1.05 1.29 -_ .54 -_ 21 .88 -- -- -_ 1.16 1.25 _- .45 -- 22 .91 — -- -- 1.17 1.28 .83 .33 — 23 1,04 -- -- -- 1.33 1.15 .94 .29 -- 24 .99 -- -- -- 1.32 1.18 .94 .31 _- 25 .96 -- -- 0.70 1.26 1.15 .81 .44 -- 26 1.00 .29 -- .72 1.20 .99 .68 .54 -_ 27 -- .32 — .76 1.07 .71 .58 .58 -- 28 -- .25 -- .82 .91 .60 .42 .48 -- 29 .38 /.08 ^.20 — 1.04 1.04 .58 .83 .42 -- 30 .47 -- .95 1.04 .50 .54 .43 -- 31 .56 -- -- -- 1.07 .69 .52 -- Mean .75 .42 .25 .83 .98 1.04 .91 .61 — Mean per day 1/ .36 .20 .12 .40 .47 .50 .44 .29 — 1/ Length of stream, 2,090 feet between middle and lower controls, 2/ For portion of day only and not included in mean. 3/ Per 1,000 feet of canyon bottom. 82 TABLE 18 CONSUMPTIVE USE OF WATER BY CANYON-BOTTOM VEGETATION AS INDICATED BY STREAM LOSSES IN COLDWATER CANYON NEAR SAN BERNARDINO, CALIF., 1932 1/ Loss of water from stream between Day upper and middle controls of month July August Septembe iT October November Acre- Acre- Acre- Acre- Acre- inches incties inches inches inches 1 -- 2.04 _- 0.98 0.73 2 -- 2.12 2.08 .60 .16 3 -- 2.23 2.28 .75 __ 4 — 2.25 2.43 1.65 -- 5 -- 2.53 2.50 1.91 __ 6 — 2.36 2.52 1.64 -- 7 -- 2.23 2.73 .14 __ 8 — 2.13 2.81 .47 -_ 9 -- 2.09 2.54 -- __ 10 — 1.53 1.88 .89 __ 11 -- 1.76 -- 1.53 _- 12 -- 1.79 -- 1.38 -- 13 -- 1.62 _- 1.14 __ 14 — 1.66 -- 1.36 __ 15 1.90 1.70 _- 1.71 __ 16 1.80 2.11 1.99 1.64 __ 17 1.93 2.29 1.89 .95 __ 18 1.41 2.55 -- 1.00 -_ 19 1.00 2.32 -- 1.22 -- 20 1.74 2.40 -- 1.30 __ 21 1.96 2.43 -- 1.36 -_ 22 2.11 2.51 1.70 1.30 __ 23 1.96 2.67 1.97 1.31 -- 24 1.77 2.54 2.12 1.58 -_ 25 2.05 2.67 1.96 1.38 _- 26 2.10 2.15 __ 1.44 __ 27 1.96 1.47 -- 1.30 — 28 2.05 1.11 -- 1.03 __ 29 2.24 1.38 -- .88 _- 30 2.18 .75 — .77 -- 31 2.29 -- -- 1.02 -- Mean 1.91 2.05 2.23 1.19 -- Mean per day 2/ .32 .35 .38 .20 -- 1/ Length of stream, 5,875 feet between upper and middle controls. 2/ Per 1,000 feet of canyon bottom. 83 acre of canyon bottom in August and a total of 47 acre-inches per acre in the period July to October, inclusive. This amount ex- ceeds water used by tules in a swamp at Victorville and is about 2 1/2 times the amount required by either saltgrass or Bermuda grass where the water table was but 2 feet from the surface. Studies in Sacramento-San Joaquin Delta, Calif orn iai/ The Sacramento-San Joaquin Delta area in California differs from the southern portion of the State in the comparative ease with which water is secured for crop use. In the southern portion water is scarce and ground water is found at depths beyond the reach of plant roots. In the Delta, especially in the peat lands, water is close to the surface, even invading the root zone, and open water areas are numerous. Under these conditions tule and cattail growth is encouraged and many areas, now considerably de- creased in size by reclamation, support aquatic plants. Weeds likewise are prolific because of high ground water and the oppor- tunity of obtaining an ample water supply. In addition, a long growing season and high summer temperatures increase transpiration rates. As a result of these conditions wild growth often extracts from the soil large quantities of water. Tules and cattails . --As in other sections of the State, investigations have been carried on by the Division of Irrigation in cooperation with the California State Division of Water Re- sources to determine monthly and annual use of water by aquatic and weed growth. Data on quantities of water consumed by tules and cattails grown in exposed tanks at Clarksburg are given in Table 19. The excessive monthly rate and the high annual total should not be taken as actual consumptive use under normal condi- tions of growth. Previous discussion has shown the fallacy of attempting to determine consumptive use of water by plants grown ij Field work was conducted under the supervision of the late 0. V. P. Stout, Irrigation Engineer, Division of Irrigation, in cooperation with Division of Water Resources, Department of Public Works, State of California. 84 I I I I I I I I I I I C^r^O-O-d- rH CV O .-H to to :^ I I I I I I -t -4- •-:^ r^ -d- -4- r^ -J- -4- -4- -J- rH 1-^ ^/^ rH -4 to oto ir\to ocor-totor- tovotooo i/^or-toto-^ -pI 0) (bI o OJ to 0-4- "^ -^J, '-^-4•r^r^cv u^ur^-4■_;t■\0 ifN I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I LTNcvvONOa^ i/> o to to t~^ -4 sO"^^Ox£>C^ OJC^tOO^OsO cs m d CD t3 +j si I I I I I cvoicVrHCV rvic\icvojojcv i/N -4 ltn i/N -^ ir\ u> ufN _4- Lpi u^ (DCNil X3 a 1-3 od (S O +:> t3 ■H O ^ CI -H O O^ ON CT^ O^ ON CT^ C7^ CTn O^ O ooooo oooooo f^r^r^r^r^ r^ r^ r^ r^ r^ r^ ON On On On ON On On On On On On •P 4J t-l o cd o i^loJV^ under unnatural conditions, without adjustment. Because of the high rate of consumptive use in exposed tank's, other investigations were undertaken at King Island in the Delta, with similar growth in tanks set in natural swamp areas. Under these conditions, recorded consumptive use more nearly approximates actual swamp use without the necessity of applying a modifying factor. Data from this investigation, shown in Table 20, while not as complete as in the previous table, indi- cate that actual swamp use of water by aquatic growth in this region is about 46 per cent of amounts indicated by exposed tank data. This indication closely agrees with the average of approx- imately 40 per cent resulting from the southern California inves- tigations. From incomplete data, Lee (18) has estimated that a factor of 50 per cent applied to consumptive use by tules and cattails grown in exposed tanks will closely approximate actual swamp consumptive use of water. It seems that a value between 40 or 50 per cent may be used with safety. It will be seen that aquatic growth uses large quantities of water. Weeds. --The measure of encroachment of weeds on the water supplies of irrigated crops has also been given consideration. The results warrant the statement that weeds are likely to use more water, in proportion to the ground actually occupied, than the general run of crops. A heavy stand of what is known locally in the Delta as smartweed (Polygonum acre ) is likely to use two to three times as much water as is required for the proper irrigation of alfalfa. Curly dock may use as much as 100 inches in depth during a single season where there is an ample water supply v/ithin easy reach of the plant roots. Results of weed investigations in the high ground-water Delta area are shown in Table 21. According to Stout (30) nearly 300,000 acre-feet of water, or 24 per cent of the annual consumptive use in the Delta, goes to sustain plants serving little or no useful purpose. He estimates that about five parts go to crops and such weeds as grow in the field with them, and two parts to noncrop plants of all kinds which grow apart from 86 ^ ^Hl a E-l 03 vO O UA o 1 1 1 1 (-^ O o o O CO -d-t» r^-^O -4- O to <^rH O O OJ r^-J- Oi ^-d- vO Oi to Oi rH OtO "A O ^ \0 to Lr^[^tO LTN o^o O to J-'X) to Ov£> rH o -J- -d-r^ (\i UA vO n£) o ~+ 1 1 1 1 o III) cv ^^ :?! ^ to cd cd n n 00 ID ■p -p a> cu 0 +0 +J -P .H rH rH +J cd CO 3 P 3 f-{ •H f) OJ a :3 •H .H r^ O - • U OvO OJ 4J ti O cH 3 • T3 ra (D tH d > tn M-H O O o liH •P Oi CO rH m m t3 t3 (D (D t( ^( rH r-l o O X3 J3 o O (0 CO 0 a> +J •p tl u tH u o o © CD (-^ OA+J ■P OM> od (d rH rH 53 rHloTHwl TABLE 21 CONSUMPTIVE USE OF WATER BY WEEDS GROWN IN TANKS AT KING ISLAND, CALIF., 1932-33 87 Type of vegetation Average depth to water table Period of record Inches 18 Cocicleburs (Xanthium canadense) 24 30 36 42 Apr. 13, Nov. 8, 1932 to . 1932 Nettles 18 Apr. 6, Dec. 30, , 1932 to . 1932 Smart weed {Polygonum acre) 24 30 36 42 18 Apr. 12, Oct. 6, , 1932 to 1932 Prickly lettuce (Lactuca scariola) 24 30 36 42 16 Apr. 20, Sept. i: , 1932 to i-28, 193: Kelp (Polygonum amphibiuml 20 22 31 36 30 Nov. 16, Nov. 10, , 1932 to 1933 Lambsquarters (Chenopodium album) 30 30 30 May 11, 1933 to Sept. 20, 1933 30 Nut grass (Cyperus esculentus) 18 18 24 24 June 3 , Nov. 8, 1933 to 1933 Curly dock (Rumex crispus) 18 24 Feb. 13, Nov. 10, 1933 to 1933 Goldenrod (Solidago occidentalis) 30 30 May 31, Nov. 10, 1933 to 1933 Yield per acre (air dried) Water used Tons Inches 7.98 4.98 6.57 5.72 8.16 86.88 55.32 62.52 57.84 62.52 1.88 1.97 2.55 48.00 49.68 61.80 20.52 23.62 19.90 18.59 18.01 127.80 118.08 120.48 101.88 113.76 4.45 6.07 7.30 8.66 12.88 43.20 55.32 70.44 72.00 99.72 5.18 4.04 3.23 3.14 4.35 105.72 87.48 64.08 50.88 73.44 6.64 4.52 6.11 7.15 6.68 52.92 52.44 46.08 51.84 54.84 2.29 5.19 3.37 3.60 49.20 49.92 43.56 43.20 13.70 13.75 100.20 95.04 8.88 5.62 96.48 69.00 88 the crops. It is not known that similar estimates have been made for other irrigated regions. Probably in only a few of them would the figures be as impressive as in the Sacramento-San Joaquin Delta where ground water is near the surface and subirrigation is practiced. Northern Colorado Studies Grasses, aquatic plants, and weeds. --The Division of Irri- gation, cooperating with the Colorado Agricultural Experiment Station, carried on investigations of use of water by grasses, aquatic plants, and weeds growing in tanks at Fort Collins, Colo., during the growing season of 1929, 1930, 1931, and 1932 (23). A brief summary of the results of the investigation is given in Table 22. TABLE 22 CONSUMPTIVE USE OF WATER BY GRASSES, AQUATIC PLANTS, AND WEEDS AT FORT COLLINS, COLO., 1929-32 Average depth to Water used July 1 to May 20 to July 1 to May 3 to Plants water table Inches Oct. 21, 1929 Oct. 14, 1930 Oct. 21, 1931 Sept. 27, 1932 Inches Inches Inches Inches Bluegrass 6 12 18 31.10 30.64 23.99 41.00 36.73 36.57 Sedge grass 6 12 18 50.49 44.16 41.54 / 60.2>^ 46.19 \ 53.63 . — — Cattails 1 — — 52.50 77.00 Rushes 1 — — 52.59 86.60 Sweet clover 1/ 12 18 — — 158.11 196.73 179.76 138.84 Sunflowers 12 18 — __ 39.42 51.18 — Russian thistle 12 18 -- — — 22.88 26.06 Redroot (pigweed) 18 -- -- -- 31.69 1/ Consumptive use by sweetclover is excessive due to spread or overhang beyond confines of tank area. 89 An examination of the data suggests that caution be used in extending certain measured losses to wider areas. All tanks were grouped at a central station, but it is extremely doubtful that consumptive use as determined represents field consumptive use of all crops. Crop overhang of vegetation spreading beyond the tank area, as in the sweetclover tanks, without doubt induces the drawing of erroneous conclusions. Likewise, the vertical intercept of insolation varies, and consumptive use is increased for those plants which normally protect themselves by dense growth. Studies of Upper Rio Grande Basin — ' At the request of the National Resources Committee, the Division of Irrigation in 1936 undertook investigations in the upper Rio Grande Basin in Colorado, New Mexico, and western Texas to determine, among other things, the quantity of water consumed by various species of native vegetation (5). The Division began investigations at Parma, 6 miles east of Monte Vista in San Luis Valley, Colo.; at Isleta, 13 miles below Albuquerque, in Middle Rio Grande Basin; and at Mesilla Dam, 5 miles below State College in Mesilla Valley. Investigations at Mesilla Dam are being con- tinued in cooperation with New Mexico Agricultural Experiment Station. San Luis Valley, Colorado Tules and grasses. --The general arrangement of the Parma station is shown in Figure 10. Tules and native meadow grasses were transplanted into ground tanks, each being surrounded by areas of similar growth. Tules in tank No. 1 and meadow grass in tank No. 2 stood in shallow water above the soil surface. Tank No. 3 was equipped with a Mariotte supply bottle to maintain a water table 8 inches below the soil level, but this was not always possible because of rains. 1/ This investigation was conducted by Harry F. Blaney, Irri^ tion Engineer, Division of Irrigation. 90 <^\'y ^\y^ i^ ^^/A ::^ ^^ @ Tank I n (+ule) Pump Native meadow Instrument shelter Tank 3 (native meadow ) Ram gage ^\i/^ v\l/^ ^^l/'^ Swamp ©Tank 2 \ ^ (native meadow) ^ I — ^ Anemometer Evaporation pan SCALE OF FEET Al^ 20 FIGUEE 10.-- Plan of Parma station, San Luis Valley, Colo. Consximptive use data for 1936 are available only for the period June to November, inclusive. Comparison of the October and November consumptive use with loss from a Weather Bureau evaporation pan indicates that all water lost by the tanks during this period was chargeable to evaporation rather than transpira- tion by plant growth. It is apparent that in the high altitudes of San Luis Valley the growing season for native vegetation ends late in September, and transpiration by plant growth is not a factor in ground-water discharge beyond that time. 91 A measure of consumptive use is available through compari- son with evaporation from a free water surface. Thus, evaporation from a Weather Bureau pan for the J\ine to November period was 30.80 inches. Application of this value indicates that consump- tive use by the tules was 126 per cent of the evaporation; by- native meadow tank No. 2, 118 per cent; and by meadow grass with a water table 8 inches below the surface, 99 per cent. It should be remembered that these percentages are for but 6 months of the year and do not represent annual values. At Victorville, Calif., as previously reported, consumptive use by tules growing under swamp conditions similar to those at Parma was 95 per cent of the evaporation from a Weather Bureau pan computed on an annual basis. For the period July to November, inclusive, this value would be 112 per cent instead of 95 per cent, showing that summer ratios exceed those for the entire year. Consumptive use by tules and meadow grass and pertinent meteorological data are shown in Table 23. Middle Rio Grande Valley, New Mexico This station was located on the east side of the Rio Grande near the pueblo of Isleta in a low moist area containing such water-loving plants as sedges, tules, cattails, saltgrass, and willows (Pl.III-B). The observations were conducted in cooperation with the Middle Rio Grande Conservancy District during 1936 and 1937. A sketch of the station is given in Figure 11. Mariotte apparatus was used to supply water to vegetation tanks and keep the water surface at constant levels, as indicated in Figure 12. To provide a natural environment, each vegetation tank was set in a surrounding growth of the same species. Tule tanks were placed in a dense swamp, grasses in meadow land, and willow growth in a willow thicket. Each species represented a large area of similar growth in the Middle Rio Grande Valley. Consumptive use of water by cattails, sedge, saltgrass, and willows, with meteorological data, are shown in Table 24. 92 ^ m CL, 1 •H a 0) P< o (D •H tH Si O +J o 0) cd a U +3 M (ii u a) 0 t)( m o crt S 0) < pj fH CO cd Q) +J r-\ O EH g Cd d a (D -rH d I d -H CO M a ^ cd P o o a ^ cd ft-H O -P 0) cd -p ^1 cd ^H W ^ :3m CO -d- to OD MD ur> \D OtOO C^CM to C-i r-{ r-f to U\ CV O vO sO -:t f^ O I -4- u^ -4- -* Cv2 rH 1*4 O OrH r~-UM» O \ tOtOtO OvO u^ ^ CV rH O CV O CO (D d Jl cd o p d M 0 rr-\ cd +5 (D rH >i t( a< O +:> ^ d • (U (U +j cd cd cd o > TO ^ +j -p a (D 5 CO CO > O 03 (D •H tO Cd rf -P Cd fH o cd (D W d sal H ^ CO O CO ^ •H TO CO o +J Cd Cd d cd 0) fn H a a tJfl CO vO-JD ^rr^rH O u^LTNtO to O^ o CO r^r^r^tio rH r-o^o to 1^ >^cv r^to rH o vO to C^Lf^r^ O u^ -J- O -4- UA O ">0 t>-t>-rH C--Ot0 [>C\i rH ^ H :^ CO C) » pJ -P O (D d rH «) CM+J > p, ^H d 13 :=) (D O O Ha ha << CO O a r^ cd > rH TO t>- • 0) 0) C^ fH -P P> 0) Cd to to ■p a 0 c^ cd -H -H ?: W+^ O 03 d fH 0) •H P4 Ph >» M Cd -p d -H - (1) •H fH P> U > ^ ' CD (D rH d > o pod ^"S^ K> 25-H rHlOJloS) 93 (D >. 1 +3 > a •H -H ^ 3 a £1 a) oi CL, ^ (T) ti W m 3 * 0) o u rH J3 0 > 51.. 0) *H (D 3 rH O OnsO -t C\J to O tX) u^ -4- <^ o +J x; ® +JrHl 0,^1 (D +3| u 01 (D s: > «! ^ 03 () (D rH x: rH O •H o 3 M ::^ -d- 1^ C^\0 ir\ o O r^ O OJ to OS CV CM O O O O O r^\|rr^ rr^jo^r^r^r^ r^ 1 CQ 03 ■iSi 03 (D r-t Cd S3 01 U o ro W d H ^ 03 O 03 r-i £! rH o H C 3 M q^ou^^-u^r^oo OtO OM/M/N\OvC r^^-* J-CV rH ^ 1 01 03 +3 03 (D rH Ot Si 01 U o :n ti d M rHl 03 1 03 (D ■P rH £l (0 -rH O O (0 c P M CO r-i ir\r^-d-CV rH l/NsOsO r-t ^> cd 0 d Oi (D -4- r-r^eo -* r^ 03 M +J a 03 ^ 03 03 XI a 03 >> 3 P O 03 fl rH M Q.P > 3 3 3 03 O O 1-3 "-s o! OT O Z t3 r^ U O • -d 03 t) O 03 -P 03 03 P Cd ti Q aj s a 03 O -H a Pi -P p tH 3 03 P^ ® d PiO >, ■H © rH rH ^ Of p o a - ti f-l 03 rH 01 r^WICl r^ 94 ^ w;iio □ Evaporation station SCALE OF FEET 10 S O 10 20 Irriqofion canal FIGUEE 11. --Plan of Isleta station, N. Mex. , 1936. Cattails. --Cattails are heavy users of water and should be prevented wherever possible from wasting an inadequate supply. Throughout the arid and semiarid West water is the controlling factor in the maintenance and increase of agriculture and popu- lation. Any waste of a natural resource is to be deplored, Tules and cattails sometimes provide preserves for wildlife, but where they serve no useful purpose they should be eliminated in the interests of water conservation (PI. IV-A) . Sedge. --Sedge is likewise a great water user, transpiring nearly as much annually as tules and cattails. The maximum monthly use of water by this species at Isleta was 16.19 acre- 95 Levee FIGURE 12. --Sketch of water supply lay-out at Isleta station, inches per acre in July 1937, equaling 157 per cent of the evaporation loss from a Weather Bureau pan. Saltgrass . --Consumptive use by saltgrass is small compared with that of cattails and sedge. In the experimental results it appeared as about half the evaporation loss from a Weather Bureau pan despite a high water table in the saltgrass tank. Records for southern California (4) show a higher consumptive use for the coastal region than for the more arid climate of central New Mex- ico, possibly due to differences in density of growth. Willows . --Measurement was also made of the quantity of water consumed by willows growing 6 to 8 feet high, in a tank 96 PLATE IV A. Cattails in tank surrounded by similar growth at Isleta, Middle Rio Grande Valley, N. Mex. B. Dense growth of water-loving shrubs and trees along the Santa Ana River, near Prado, Calif. Studies have shown this vegetation uses approximately $0 acre-inches of water per acre annually. 97 6 feet in diameter set in a thicket of the same growth. The water table in the tank fluctuated slightly throughout the season but averaged about 13 inches below the surface. Consumptive use for 12 months amounted to 30.49 inches in depth for the area of the tank. Evaporation records are not available for all this period, but for the first 6 months, June to November, inclusive, consumptive use by the willows was 47.9 per cent of the evapora- tion from a Weather Bureau pan. A similar test in southern California, involving an isolated tank unprotected by other willow growth in which depth to water was 2 feet, resulted in a consumptive use of water equalling 92.7 per cent of the evapora- tion loss from a Weather Bureau pan. Summarizing vegetative use of water at Isleta: Cattails and sedge are extravagant users of water, while saltgrass and willows use less. This conclusion is supported by similar inves- tigations elsewhere. Mesilla Valley, New Mexico The evaporation-transpiration station established at Mesilla Dam to determine consumptive use of water by cattails and saltgrass was on low ground along the west bank of the Rio Grande in an area of similar growth. The site was made available by the Bureau of Reclamation. There was exposure in all directions ex- cept to the west where the mesa rose abruptly about 15 feet some 50 yards from the station. To the south were a few scattered trees, while the river bordered the northeast side. A sketch of the station site is sho-wn in Figure 13. Cattails. --Two cattail tanks were located in a swamp com- pletely surrounded by natural gro'Arth. Tanks were 2 feet in diam- eter by 3 feet deep. Healthy broadleaf cattails were transplanted into the tanks and the water surface was maintained approximately 2 inches above the soil. Each developed a vigorous growth al- though the plants were somewhat larger in one tank than in the other. This difference is reflected in consumptive use, as will 98 Hardware cloth drain 6"of gravel - CROSS SECTION Drains connected to bottom of wells PLAN PIGURE 13.— Plan of Mesilla Dam station. be seen in Table 25 which presents all consumptive use and meteorological data. The average consumptive use of water by cattails corre- sponded closely with data obtained at Isleta for the same period. The average for both stations amounted to about 111 inches in depth for the 12-month period. Saltgrass . --Saltgrass was transplanted into a tank set in a saltgrass area of high ground water. A Mariotte control pro- vided an automatic supply, keeping the water level in the tank at a fairly constant depth of 14 inches. A thick growth of grass developed to a height of 7 to 10 inches by midsummer. As at other 99 :^ 1 CI CO o 43 nH cd -P -O CO +J nH CO CO 0 p fl •H -H 0 +J -O 0 (0 -H rH fl u 0 P 0 « J^ (i< cd a g 0 -H ^ cd 3 O O & s:i ca a a-H O +:> 0 cd td P ^^ cd fn o. > cd ivh 0 ;3 w ^ :3m o [to o Ko^ c^o «o^o cv CNJI tn 1 m 0 p tn xi ^ 03 0 td U d CO td M tn 1 CO 0 P rH xi Cd -H 0 0 cd a +3 M |i4r^ rH Oi -4trH C^ O lO CJN to ^-^O Lr^ O OvO irsr^rH OC^vO -4tH OvO CJNOJ to C^ CjNCvi ^O 0-4^ -4- CV to -:}■ rH rH rH H r^-d--4-u^\OC^tOtOr^vD-J--:l- rH CJ^ r^ O O to u^^O O vO O O rvi OJ rr\ _j- Lf^ irwO ^0 \0 -J- r^ CNJ r^O -4- r^ "^ rr\ -4- c^^O C^tO to ifNvOso c^to cj^ocj^to r^vo ua OtOC^iOO^tOtO^>^u^OO<^i r~-CN2 OrH ir\vO r^tO to -d-u^O <>i -4-^0 to iH C^OC~-^0^0 f^rH O r^ r^ OJ ^O rH C^ -4-rH rH OrH r^ I I I I I I I I I I I r-{ rH r-iC4 rr^ ^ tn 1 tn 0 ■P rH d ff) tH 0 0 Cd a +J M Tl t< a 0 t< ti 01 ^ tn 0 0 ^ vO ■p B 0 ^ ^ xi 01 (^ tn 0 ^ a a +j 0 0 >> :3 p 00 0 fl (» ,-i ,-{ t£> ap> > 0 {) 3 :3 0 0 0 0 S Ira! CO 0 a Q -4■rHC^u^^^c^^^c^c^^^c\^rH O CT^O^O LTNvO r^O OrH 0(^ C\i rr\ vO OMD rH to -tOU^ CM CV <^ OvO -d-vOC7Mr\C\irHC\iC\iC\iO rHvOOc^CV^Or^CvJOtO^O ^1 >> iU J3 fH 0 0 tn 03 p a 0 ^ ^ cdSjUrH CQ0^aa ::)tHO-H 0>i;3+3O00 d,CI fn ^1 !>»c!rH tjOO

O cd0cdP4a3P3:30OO0 l-a|b: , tn (dc-- 0 i? r^ rH :^ •H 0 rH a +3 0 ir\ tn 0 § CO X3 h> -H 0 d 0 C! tH p 0 •H -J-'^O P ^ c^ 01 0 +J 3 0 ai-3 •-{ 0 ,-{ -ci M 0 0 0 0 M u 0 cd rH +3 U 03 01 0 P p > 0 CO -tien 100 stations, a Weather Bureau evaporation pan provided data for comparison with consumptive use records. The 12-month use of water by saltgrass, approximately 40 inches in depth, was slightly more than the amount determined at Isleta in spite of greater depth to water table, and approxi- mated results obtained in southern California under similar tank conditions. Thus, in widely separated localities, consumptive use by saltgrass, growing under conditions of ground water within approximately 12 inches of the surface, appears not to exceed 40 acre-inches per acre. There are probably few extensive local- ities where such conditions exist. For this species, at least, consumptive use decreases with increasing depth to ground water, so that the annual draft on water supplies caused by saltgrass is probably less than would be required by many cultivated crops in the same area. 101 CHAPTER 5 OTHER INVESTIGATIONS Other investigations, fully as important as those by the Division of Irrigation, have been conducted by other agencies. Standard methods have been used, and the results form an impor- tant adaition to the general knov/ledge of consumptive use by native growth. These data have been collected and are presented in the following discussions. SOUTH-CENTRAL OREGON The early irrigation development of south-central Oregon was largely by wild flooding with little regard to the economical use of water. Much of the irrigated area was used for hay and pasture. The practice of flooding when water was plentiful was not only wasteful of the water supply but was also likely to in- jure the soil and reduce yields. Reports indicate that at one time 300,000 acres of marsh lands in Chewaucan and Harney Valleys and in Klamath Basin were irrigated in this manner. In 1915 investigations were undertaken under a cooperative agreement by the Oregon Experiment Station and the Division of Irrigation (24) to determine the use of water by such native marshlsind plants as were suitable for hay and pasture. Experi- ments were carried out on fields and plots and in tanks. The general plan was to apply water in three amounts: the usual irrigation by the farm operator, a larger amount as determined by the investigator, and a smaller amount. Investigations con- tinued through the seasons 1915, 1916, and 1917- Marsh grass, native meadow, sugar grass, and wire rush were grown in tanks and plots. The amounts of water used are shown in Tables 26 to 29. 102 TABLE 26 CONSUMPTIVE USE OF WATER BY MARSH GRASS IN THE CHEWAUCAN VALLEY, OREG. (24) Soil Alti- tude Area irri- gated!/ Wat .er used Year Rain and soil moisture Irri- gation Total Yield per acre Feet Inches Inches Inches Tons 1915 Silt loam 4300 Plot 5.67 3.31 3.16 27.48 .00 11.28 33.15 3.31 14.44 0.89 .57 1.03 1915 Silt loam 4300 Plot 6.50 4.32 5.04 18.12 .00 6.60 24.62 4.32 11.64 .70 .70 .73 1915 Peat 4300 Tank 13.49 18.11 9.89 26.47 4.00 13.81 39.96 22.11 23.70 -- 1917 Peaty- 4300 Tank 1.50 1.49 1.27 33.48 13.77 18.63 34.98 15.26 19.90 -- 1917 Peaty 4300 Plot 4.65 3.48 3.18 27.90 3.00 14.78 32.55 6.48 17.96 1.03 .94 .92 1/ Area of tanks - 1.39 square feet ; of pi ots - 0. 10 acre. TABLE 27 CONSUMPTIVE USE OF WATER BY NATURAL MEADOW IN CHEWAUCAN AND HARNEY VALLEYS, OREG. (24) 103 Soil Alti- tude Area irri- gatedi/ Wat er used Year Rain and soil moisture Irri- gation Total Yield per acre Feet Acres Inches Inches Inches Tons 1916 Silt loam 4120 100 12.50 10.03 14.98 21.50 0 10.75 34.00 10.03 25.73 2.18 2.18 2.18 1916 Silt loam 4120 100 6.85 6.03 9.94 24.50 0 12.25 31.35 6.03 22.19 1.96 2.61 1.96 1916 Silt loam 4120 100 11.14 12.51 10.96 28.00 0 14.00 39.14 12.51 24.96 2.83 1.96 2.83 1916^ Peaty 4400 Plot 6.96 8.64 7.91 26.50 8.50 19.20 33.46 17.14 27.11 1.47 1.24 1.94 1916^ Silt loam 4400 Plot 6.12 4.50 5.86 26.20 5.75 14.50 32.32 10.25 20.36 .60 .57 .43 1916 Silt loam 4120 Tank 6.33 6.32 7.00 11.00 3.50 6.00 17.33 9.82 13.00 1916 Silt loam 4120 Tank 5.94 5.55 6.88 11.00 4.50 6.00 16.94 10.05 12.88 1/ Area of tanks - 1.39 square feet; of plots - 0.10 acre, 2/ These tests made in Chewaucan Valley - all others in Harney Valley. 104 TABLE 28 CONSUMPTIVE USE OF WATER BY SUGAR GRASS IN THE CHEWAUCAN VALLEY AND THE KLAM/lTH BASIN, OREG. (24) Soil Alti- tude Area irri- gatedi/ Vat er used Year Rain and soil moisture Irri- gation Total Yield per acre Feet Inches Inches Inches Tons 1916^ Peaty- 4400 Tank 8.92 11.30 9.50 32.00 12.00 16.00 40.92 23.30 25.50 2.40 1.31 1.96 1918 Peaty 4100 Tank 9.09 15.72 4.80 25.00 7.00 13.00 34.09 22.72 17.80 — 1918 Peaty- 4100 Tank 9.03 16.29 9.94 25.00 7.00 13.00 34.03 23.29 22.94 -- 1/ Area of tanks - 1.39 square feet. 2/ These tests made in Chewaucan Valley - all others in Klamath Basin. TABLE 29 CONSUMPTIVE USE OF WATER BY WIRE RUSH GROWN IN THE KLAMATH BASIN, OREG. (24) Soil Alti- tude Area irri- gatedi/ Wat er used Year Rain and soil moisture Irri- gation Total Yield per acre Feet Inches Inches Inches Tons 1917 Peaty 4100 Tank 39.98 6.79 8.46 20.00 7.00 11.00 59.98 13.79 19.46 3.47 .75 1.39 1919 Peaty 4100 Tank -1.60 1.58 .47 24.00 8.00 16.00 22.40 9.58 16.47 — 1919 Peaty 4100 Tank - .48 3.65 - .48 24.00 8.00 16.00 23.52 11.65 15.52 :: \J Area of tanks - 1.39 square feet, 105 The soil moisture conditions in tanks used in the investi- gation were different from others discussed in this report. Or- dinarily tank studies are conducted in the presence of a water table under the control of the investigator. All other studies discussed here have been of this type. In tanks used for growth of marsh grasses in south-central Oregon, however, the investiga- tion was characterized by an absence of water table and the use of water is taken as the sum of rainfall and soil moisture con- siimed plus irrigation water applied. On the basis of differences between inflow and outflow, consumptive use of water by wild meadows was estimated as follows: Chewaucan Valley 1.52 acre-feet per acre; Harney Valley 1.34 acre- feet per acre; and Klamath Basin, a 5-year average, 1.30 acre-feet per acre. This method does not give the total consumptive use as neither deep percolation losses, imderflow out of the basin nor precipitation are included. Marsh grass. --From data available, there does not appear to be a close relation between quantity of water received by marsh grass and yield in tons per acre. However, the record is not com- plete. On plots of silt loam the yield varied from 0.57 to 1.03 tons per acre, while the water received for these yields varied from a minimum of 3-31 inches to a maximum of 14.44 inches for the season. On peaty soil a maximum of 32.55 inches of water produced 1.03 tons, while a minimum of 6.48 inches was sufficient for 0.94 ton. Because of the inconsistency of the use-yield relation, it does not seem improbable that the marsh grass grown in plots re- ceived quantities of ground water not included in the record. Re- cords of marsh grass grown in tanks, with weight of crop measured in grams, show a more uniform use-yield ratio. Native meadow. --Native meadow in farms, plots or tanks re- ceived a maximum water supply of 39-14 inches of depth and a mini- mum of 6.03 inches. Yields for these amounts are inconsistent. From the record it appears that water received by the crop is not a water requirement and has no relation to the amount necessary to 106 plant existence. In instances where no water was applied by irrigation and the grass received only a low rainfall the yield was equal to or greater than that produced when 21.5 inches of irrigation was applied. Sugar grass .--Water received by sugar grass (Carex aqua- tilis) grown in tanks varied from 17.80 inches to 40.92 inches. Records of yield are incomplete, but those available show the greatest yield for the most water received. Wire rush. — Use of water by wire rush in tanks varied from 9.58 inches of depth to 59.98 inches for peaty soil. Yield in tons per acre is available only for three tanks which show the largest yield for the most water received. MUD LAKE. IDAHO (29) Tules. — Additional data on consumptive use of water by tules in a tank set in a swamp area are afforded by an investi- gation of water resources of Mud Lake, Idaho, from 1921 to 1923, inclusive. Results of the investigation indicate that 162,000 acre-feet of water appeared in Mud Lake and five smaller lakes or reservoirs in the same vicinity during the year ending March 31, 1922. At that time three-fourths of the lake area and ad- joining marshes were occupied by tule growth. Stearns and Bryan (29) state that "about 49,000 acre-feet was used for the irrigation of about 13,300 acres, and about 108,000 acre-feet was discharged by evaporation and transpiration from tules and other native plants of small economic value. The data show that the natural losses were very large in proportion to the quantity used for irrigation. They at once raise the ques- tion whether the supply for irrigation can be increased by reduc- ing the natural losses." As a means of measuring losses from swamp areas a tule pan 4 feet in diameter by 4 feet deep was set in the swamp. Tules of about the same density as the surrounding growth were transplanted into the pan. The soil was generally submerged to represent swamp 107 conditions. Records of consumptive use and meteorological data for the summer months of 1921 to 1923, inclusive, are shown in Table 30. TABLE 30 CONSUMPTIVE USE OF WATER BY TULES IN TANKS, AND METEOROLOGICAL DATA AT MUD LAKE, IDAHO, 1921-23 (29) Meteorological data Water Temperature Wind movement used Mean Mean Month and by maxi- mini- Precipi- year tules mum mum Mean tation Total Average Miles per 1921 Inches i/8.85 °F. 79 °F. 50 °F. 64 Inches 0.36 Miles 4040 hour June 5.6 July 18.98 87 50 68 .62 3640 4.9 August 17.98 2/5.54 85 48 66 .23 3020 4.1 September 70 33 52 .42 4020 5.6 June to Sept, , inclus: ive 51.35 80 45 62 1.63 14720 5.0 1922 June 13.47 82 45 64 .62 3485 4.8 July 21.42 86 49 68 .63 3160 4.2 August 17.33 84 41 62 2.02 2865 3.8 Septembs 3r 10.26 80 43 62 — 2660 3.7 June to Sept. , inclus; Lve 62.48 83 44 64 3.27 12170 4.1 1923 June ^5.79 71 43 57 1.80 4060 5.6 July 11.70 88 53 70 1.40 , /3590 ^4140 , /4.8 ^5.6 August 13.38 83 47 65 1.05 September 11.06 77 40 58 .50 4275 5.9 June to Sept. , inclusive 41.93 80 46 62 4.75 16065 5.5 1/ June 13 to 30. 2/ September 1 to 23- 3/ June 12 to 30, 4/ Uncertain. The second year of record shows the highest seasonal use of water. This seems reasonable, as during the first year the plants were becoming reestablished after the shock of being trans- planted; in the third year there was danger of loss of fertility or of the roots becoming pot-bound. Seasonal consumptive use of 62.48 inches from June to September, inclusive, at Mud Lake agrees 108 closely with consumptive use by tules at Isleta, N. Mex. , but exceeds amounts at other tule stations where measurements were obtained in swamp areas as distinguished from exposed tanks. ESCALAMTE VALLEY, UTAH The general method of estimating consumptive use by native vegetation through attention to ground-water fluctuations has been previously described. White (38), using the same method in the Escalante Valley, Utah, as described by Smith in Arizona (see page 18), shows that ground-water fluctuations respond to the vegetal demand for moisture with declining water tables during hours of sunlight and rising water tables during the night. Observations were made in 1926 and 1927 to determine con- sumptive use by various species of native vegetation and to esti- mate the water resources of the valley. This is a desert region yet one in which a considerable area of native growth subsists upon ground water close to the surface. Vegetation consisted principally of saltgrass, greasewood, sagebrush, rabbitbrush, shadscale, pickleweed, and willow. To determine the effect of consumptive use by these plants, wells sunk in areas of each predominant species were equipped with water-stage recorders. With this equipment, diurnal fluctuations of the water table for each area were determined. The extent of the fluctuations varied, not only with soil type but also, and what is of greater importance, with the age, vigor, density, and type of plant growth. The maximum daily draw-down observed ranged from 1 1/2 inches for an area of greasewood to 4 1/4 inches in a field of marsh grasses. Samples of recorder charts for several vegetative species are shown in Figure 14. Ground-water fluctuations as described can only be trans- lated into depths of consumptive use through determination of the specific yield of the soil on which the vegetation grows. Obvi- ously for large areas this is difficult because of ever-changing soil conditions throughout the area. To obtain values of specific 109 10.5 10.6 ' 10.7 10.8 ^ \- \ \ fl_ \J ^/ A A i 1 : V GREASEWOOD \ \ 17 18 19 20 21 June 22 23 24 0 8.1 H- ^>. ^ ^^ _^ RABBITBRUSH \J \ A /^ /> \J \> \y 1 'Vv r^ SHADSCALE ^zs 14 15 16 17 18 19 20 21 June 3.4 3.5 3.6 n ft 1 1 y 1 Grass cut L J % l\ ill \j \j I V 1 1 1 SALTGRASS 1 1 1 V 18 19 20 21 22 23 24 25 26 27 Aug. 4.7 < 14 15 16 17 18 19 20 21 < ?- Sept. Q^ *» « -r 1 1 1 1 1 1 1 1 *' Q 9-2| \7\1 I \ \ I \ I Q 9.3 5.3 5.4 5.5 5.6 A A 1 1 j\ 1/ , «i \/ 5.7 willows" 23 24 25 26 Aug. 4.8 4.9 5.0 ^'x^- 5 ilPICKLEWEED 22 23 24 25 Sept. FIGURE 14. --Examples of recorder charts showing ground-water fluctuations due to daily transpiration losses by various species of native vegetation (after White). yield usable in the consumptive use formula £ = ^(24 r ± £), tanks were filled with undisturbed soil in the vicinity of wells where recorders were maintained. Water was added to or subtracted from the soil and the specific yield computed according to the changed level in the tank. Estimates of consxamptive use were made for a number of vegetative species by this method of obtaining specific yield values. Saltgrass . --To support some of the findings reached by means of water-table fluctuations, saltgrass and greasewood were grown in tanks supplied with measured amounts of water. Two salt- grass tanks were employed, one using transplanted sod, the other undisturbed sod and soil obtained by driving the tank into the ground. Greasewood was transplanted in the tank, but only four put of seven plants lived and for some time these grew slowly. By the end of the summer of 1926 these plants were thrifty, and were vigorous during the follov/ing season. 110 I Each tank was equipped with automatic water-supply Mariotte apparatus. In some respects these were unsatisfactory, as they were not protected against temperature changes. In periods of rising temperatures, expanding air forced water out of the bottle beyond the capacity of plant absorption, and the water table in the soil tank rose above the desired level. As air in the bottle became cooler, flow of water was retarded and transpiration oc- curred faster than water could be supplied. Water levels dropped in the soil tank. Over a considerable period of time these changes were unimportant, but they destroyed the opportunity to obtain accurate hourly records of transpiration losses. Greasewood. --Attempts were made to separate transpiration from greasewood plants and evaporation from soil. Separate soil evaporation tanks were used for this purpose. Saltgrass growing in tanks shades the ground surface so that little soil evaporation occurs, and the principal loss is caused by transpiration. In a tank of greasev/ood there would be some bare soil, and evaporation would be a factor in the total loss of water. White (38) has estimated this as approximately 25 per cent of the total. Con- sumptive use of water by saltgrass and greasewood grown in tanks in the Escalante Valley is presented in Table 31. SAN LUIS VALLEY, COLORADO Saltgrass . --Tipton and Hart, for the State Engineer of Colorado, conducted studies for several years on the use of water by saltgrass in tanks and of evaporation in the San Luis Valley, Colo. (32) . The evaporation and transpiration laboratory was established at Garnett in 1927 and continued in 1928. The station was rehabil- itated and placed in operation again in April 1930 and continued in 1931. No change was made in the apparatus or in the depth at which the water table was maintained in the various tanks. An additional saltgrass tank was installed to maintain the water table at a depth of about 40 inches, but this tank did not begin to function properly Ill ;3to P cv 2 OS 1 •H a 03 P< o (D •H -H ^ O -P o 0) cd a tn -P H Ph CD CO +^ 0 iH ft O +J ^ cu 0) +J CO cd M tn en crt 0) T-f (D +J +J (1) ^ C) en m o ei ^ 0 Pi M CO +J tH (D 0 a o -p ^ 0 tJ & +J -4-CV C\i I O O rH ^O 1 •H d CQ ft o 0 CO -H Xl a -p o CO CO n u u H EH 1 cl m CJ o 0 ft-rH si CO -P o !> CO a 0 u H O H r\2 (^ to -^hr-vo cv ~t^O O iH rH MD too O-4-tO rH -d-vO ir\-j-,H OJ -t-tr^tO to tOsO LPvtO -4--4- to C\i O O or^ -t cvl tn fH 0 0 Ti si -P 0 o (0 CO a :3 3 H CO rH sO to O rH CM CM r>-\ C\i OA -^ >0 "^CVsO -^O H rH HvO r^ to O O O f^tO Or^tO O rH rH CV LTMJ-S -4- r^ rH rH rH to u-\ r^ to sO (>i c>^ CV CV CM CNi CM vO to O rH rH CM r\i r^ -4- r^ C\i rH ^1 vO CO OJ 0 O t» r-i O TrJ CO o CO ■n 0 tJ +j 0 d ^ CO U rH ::5 ft+3 U u CO CO 0 rH 0 rH d -H •9 ^ CO J3 fH cd CO xJ +^ a 0 d o +J 0 0 d u d CQ 0 ^ o CM ro 0 Xi o H P 0 >> S +^ O CD CJs 0 >^ :3 4J o CO >> d rH M ft-P CO rH >> d rH tlO ft+J CO eg :d ;3 ;3 0 o 0 cO d 3 d 0 O 0 \\ S 1-3 i-a <; coo CO S •-3 "^ > zi +J o tH >> fl rH M Oi-P 0,(0 3 3 S> Q) O <; S ►-s '-' Ol 4h (d Fh o © T3 -P 13 S P en x: > t3 S P *"* ^ rH r^^O 00 <^0 I N^o vc r^c^vo ytOOCVOOCOOvi ^ to r^ J-^ I r~\ir\ir\\0 -d-u sO-d-COCVtOtOO-*TO <*\tOvO ^ o o o oco r-t f^c^r-oto >. Ol O ® (D O^l ^1 P > o ^1 r*^-^ r-t OOC '*|oi^c^^^^^|f^^M'^^^ r^r^^ irwO vO t^C^^D (VCSisOtOtOOJ^OOC^ t^so vo c^ c^ [^ c^so r- <-i r^ ^ to u-v (V O r^sO M/\so o c^r^ r^-^'*^cv^o.^too^^ r^-^o^osD r^r^r^r^ s|vOOCV-*OOOJO ^vOvOvi)^0 ^ooto-^totototo^o r^sO O O to CO o ^o r^ rH . ^ © CD P C P (D c o S c u u O O ^ 4h (-. • a c! d O T3 -O 13 ' 4h 4-1 4-< O O O O d c a a o 03 (0 o © © © 119 OVENS V.AT.t.f:y, CALIFORNIA Closed Basins Determination of the safe yield from closed rock basins is of considerable importance to sections of the Southwest where re- liance is placed upon ground water as the principal source of sup- ply. The recharge into the basin results from percolation from stream flow and from precipitation. The normal loss is from evap- oration from water surfaces and moist areas, transpiration from vegetation, and surface and underflow from the basin. Underflow is generally a slow movement through a limited cross section of alluvial material and may sometimes be omitted from consideration. Under natural conditions the recharge and discharge will be about evenly balanced over a long period of time. In times of drought the moist area of the basin will contract owing to lower ground water, and in periods of above-normal precipitation it will expand and there will be increased flow out of the basin. Under natural conditions the discharge by evaporation and transpiration may be considered as the theoretical yield which may be pumped from the basin without greatly changing ground-water levels. In actual practice, however, the safe yield is less than the theoretical owing to loss of water by plant use in low areas and evaporation of moisture from the soil surface. Measurement of the quantity of water which may be safely extracted from a basin of the closed alluvial type may be arrived at through estimating the natural losses resulting from evapora- tion and from consumptive use by natural vegetation. The ground- water discharge by plants applied to areas of known depth to water will provide a measure of quantities recoverable for other uses. The pioneer work of this nature by Lee (16, 1?) in deter- mining the safe yield of water in the Owens Valley, Calif. , prior to the construction of the Los Angeles aqueduct, opened the way for other investigations described elsewhere in this report. 120 Saltgrass . --Consumptive use of water by saltgrass grown artificially in large tanks in Owens Valley was determined for various depths to water table. Evaporation from water and from moist soil surfaces was likewise determined. As a result of pre- liminary investigations six tanks were used for growths of salt- grass sod. In these tanks ground water remained fairly constant at predetermined depths except where it was so near the surface that there was a high rate of consumptive use. In the tank in which the water table was theoretically about 1 foot below the surface, the grass withdrew water more rapidly than it could be supplied from the connected reservoir tank, so that the water table dropped from near the 1-foot level in the winter months to below 2 feet in the summer. The investigation disclosed a diminishing rate of consump- tive use as depth to ground water increased, in practically a straight-line ratio. Reference to Table 35 shows the monthly and annual use of water by saltgrass for various depths to water table, ranging from an annual maximum of 48.80 inches where average depth to water table was 18 inches to an annual minimum of 13.43 inches where average depth to water table was 59 inches. Observations in the Owens Valley showed little saltgrass in localities where groiind water exceeded 8 feet, indicating inability of the roots to function beyond this depth. It does not follow that this is the limit in all saltgrass fields. The maximum depth observed in southern California was 11 feet in clay soil. Estimated Water Supplies As a result of this investigation, Lee made estimates of evaporation and consumptive use of water losses for 54-59 square miles of high ground-water alkali and saltgrass lands, as shown in Table 36, and converted the consumptive use into equivalent stream flow. The average rate of discharge for the 54.59 square miles where depth to water did not exceed 8 feet was equivalent to a continuous flow of 2 cubic feet per second per square mile. 121 Ave rag depth to water table rH f-i +3 (D -^ CO 03 r-i :* ^ rH Q) Mfl ^1 (B •• td +J (D .H ■ t, a o +j ^ Ix^ (D (n +j CO to M > Td S -P H JAuA-t <^0 rHiHO (D rH ^^ Oi O +J J3 (D ® -P CO CO U CD Tj CO CO 5E ^ -:}-C\)C0OOf^rHt0(>2<^OO -4- - 1>- O rH u^sO r^O r^ rH ~J-\0 ON to U^ C\i rH (D tlOxt Jh ^ (D © +J cO (0 «; r^vO 0~t-d-tO-d--i-ONOCV-:J- (VrHOiCVJfMCVCviOJHOiCVCV tn u tJ 5 +3 -a; ono CNJ to o unno o ONr--c~~r^ rHrHrHOiOiCVir^CNiH 03 u 0) » iU £1 »-i tD tU tn CO +J a 0) £1 ^ cOS^rH O3(DXJ0Q :3tio-H (D>>3p>o®a) Cl^tHfH>,CJrHt)DD

>0 cOtDCOOicOP^dtDOOO) 122 TABLE 36 ESTIMATED CONSUMPTIVE USE OF WATER BY SALTGRASS AND ALKALI LANDS IN THE OWENS VALLEY, CALIF., 1911. (BASED UPON TANK INVESTIGATIONS.) (16 and 1?) Area Square miles 11.89 17.66 25.04 Average depth to water table Feet 2.5 3.5 5.5 Water used Enclosing contours Summer Inches 36.5 29.6 15.6 Winter Inches 5.2 4.0- .2 Total Inches 41.7 33.6 15.8 Equivalent stream flow Feet 3 3 to 4 4 to 8 Second-feet 36.6 43.7 29.1 Totals 54.59 109.4 This was the theoretical quantity of water which might be recovered for beneficial use if ground-water levels were lowered through pumping to depths beyond reach of the vegetation, and was the basis for construction of the $25,000,000 Los Angeles aqueduct. SANTA ANA RIVER VALLEY, CALIFORNIA River-bottom vegetation. --An investigation was made by Troxell (33) of the United States Geological Survey, along a 16- mile stretch of the Santa Ana River between Riverside Narrows and the Prado gaging station, California. Much of this area has rela- tively high ground water which contributes to and increases the flow of the river along its course. The river-bottom area is nar- row, probably averaging less than half a mile in width. Within this strip ground water over a considerable area is found at less than 5 feet from the surface. The vegetation was typical river-bottom growth ranging from large cottonwood trees to grass meadows. A vegetative survey showed 4,040 acres of bottom lands of which 137 acres were culti- vated and 210 acres consisted of water surface. Of the remainder, heavy tree-cover of the water-loving type grew on 1,519 acres, while there were 751 acres of meadow. Table 37 shows the vegetative 123 classification. Typical vegetative grovrth along the Santa Ana River is depicted in Plate IV-B. TABLE 37 CLASSIFICATION OF VEGETATIVE COVER, SANTA ANA RIVER, CALIF. Type of vegetation Heavy tree cover Grass Light brush cover Heavy brush cover Bare sand Swamp plants, sedges, etc, Water surface Cultivated Light tree cover Acres Per cent 1519 37.6 751 18.6 481 11.9 356 8.8 251 6.2 242 6.0 210 5.2 137 3.4 93 2.3 Totals 4040 100.0 Natural losses of the area, determined as a result of the investigation, were computed on the basis of various tests and studies rather than actual consumptive-use measurements. Evapora- tion losses, stream flow at several gaging stations, temperature, gro\ind-water fluctuations, and changes in gro\md-water storage were recorded during the summers of 1931 and 1932. Consumptive use of water was likewise estimated by means of ground-water fluc- tuations beneath a group of willows. The method of analysis of ground-water fluctuations has been previously discussed. Consumptive use during two summer seasons from July 1 to September 30 averaged 66 per cent of the evaporation from a Weather Bureau pan or approximately the amount of evaporation from a body of water of extent equal to the area involved. The loss of ground water due to transpiration and evaporation averaged nearly 20 per cent of the annual inflow into the area in a 2-year period. The percentage of loss during the summer was even greater. It was during these months, when water had the highest value for irrigation, that the entire flow of the river was diverted into canals for irrigation of citrus lands at points below the Prado 124 measurement. From May to September natural losses of the river- bottom vegetation were 55 per cent of all the water entering the channel of the Santa Ana River in a length of l6 miles. Troxell (33) estimates natural losses, combining transpiration and evapo- ration, as equal to approximately 50 inches in depth annually. As a measure of evaporation and transpiration losses, Table 38 has been compiled to show the effect of natural losses on stream flow, total monthly loss in acre-feet, and monthly con- sumptive use of water in acre-inches per acre. TABLE 38 ESTIM/ITED NATURAL LOSSES BETWEEN RIVERSIDE NARROWS AND PRADO GAGING STATION, SANTA ANA RIVER, CALIF. , 1930-31 AND 1931-32 (33) 1930-31 1931-32 Month Mean daily Second- feet Monthly Per acre Acre- feet Acre- inches Mean daily Second- feet Monthly Per acre Acre- feet Acre inches October 19.8 1220 3.62 19.5 1200 3.56 November 19.3 1150 3.42 13.1 780 2.32 December 13.7 844 2.51 9.0 555 1.65 January 14.6 895 2.66 15.2 935 2.78 February 9.7 540 1.60 9.3 535 1.59 March 20.8 1280 3.80 18.7 1150 3.42 April 22.7 1350 4.00 23.2 1380 4.10 May 28.0 1720 5.11 27.0 1660 4.93 Jim 6 33.9 2020 6.00 34.1 2030 6.03 July 41.6 2560 7.60 36.1 2220 6.59 August 35.6 2190 6.50 37.7 2320 6.89 September 28.4 1690 5.02 26.2 1560 4.63 Year 24.0 17459 51.84 22.4 16325 48.49 The results obtained agree in general with tank measure- ments conducted by the Division of Irrigation 20 miles away near Santa Ana, a general summary of which is given in Table 13. Here saltgrass growing with water near the surface used 36 to 42 in- ches annually. Tules and cattails represented an adjusted loss of 73 inches, willows used 45 inches, and wire rush 84 inches. 125 When it is considered that 1,519 acres of the Prado bottom lands had a heavy tree cover credited with being of the water-loving type, an average consumptive use of 50 inches per acre cannot be considered excessive. suMMAjiiEs OF consumptive: use data Results obtained through investigations described earlier in this report are arranged for convenience in summaries to show meteorological data and depths of water used by saltgrass, tules, cattails, and other varieties of native vegetation. They are presented as Tables 39 to 41. 126 f-;f-j-*-j-* a u OH Pi O 4^ ^ fl) +:> a] 01) OJrHO^C^ CTs f-i CO Ov ~* -J- -* -;!■ CO >0 vO 00 OJ O O t O^O-^t^tOr-f^CO r^vO CM o o I rH -*H^O O :5i rHCVOJCV.HrHrH(V.Hr- ) o-o to PMO nD ir\ oj o ^ ^ rH -J- f^ ^ ^ fv> -p a P TJ H B a! a a Q< CV OJ OJ (V 03 t^ r~^ C^ r^ r*> r^ n~, \0 O O ^O ^O ^_d■-:t-* totocototo fe OOOON CO f^ O I ~* -4- -J- -^ r^ -4 O ^/^w^ vO -4-4TOsO -4 -4«0vO -4-4t0 CO to nOnD n-»0 OnD n^O OvO f*>0 OvO^ C^ f-r^ OJ CV CV CM (V OJ fV OJ OJ CV (N OJ cv o o o c^r^r^c^ O^O^O^O^ ON ts t-i t^ tn a, a, a, i=i« -c^ c^to o ^ c^to o .H r^to O .H H r-^ On OnQ\ (^ O^ C7n On On on O on on O^ On O^ On c^t^t^to toco to OJ CV OJ OJ CVJ OJ CV O^ ON O^ O^ On On On .-{ r-i <-\ r-i r-i 434a 4J+3+34J+J4-J+J+3+J4J4J-P4-5 00 0000000000000 00 0000000000000 \ r-i OnOnOn O^On +J+J+J+J+J+^4J OD W CO CO CO CO CO QQQQP CV CM rvj OJ O o^ ONCJN C> O "H rH rH ^ rH rH >»>»>>>> a d (C (fl (0 ta :3 p CM oj c\t oj cy cv oj On CJN On <^ 0\ On On +3 4^ +J +J +3 +3 +J 0000000 a a a a a ^ 127 coeo«oflotoTO CO to aato (M CM CM Oi OJ CV OJ CM \0 'O c^cNir-oo-* 'H r- o i-H O^ (*\ Orf r-co r^ so Oi r-< Oi ^ OJ .H O f*> o -?l ^ ^ ^ ^ C\f\0 CTvtO CV fV OJ sOCO CM ^ O O O r~^ -*W-4-rH -:t -:JO OOO §d I ""^l Cl O i ^O^OnOnO^O^ ^o-o ^ h «DtOtOtX)a3«0 flO CO -J- I vOvOnO S S SI aJ< I -I « g 31 o I r~-c^[^c^c^c^ r-t^ to . >^ >^ !»>. >. IS a a a O O ID *7) i-i hj r^O^OOCT^Or^QN 3 9 s a © © <& © a ^ o o .■r< (h O O « t, a o (0 O Ci r - >.>>-r a ati a o ■rf ^ a c a -p ^ ^ ::rk5v^ 128 ^ Ol i3 O o a (OS oi 9>\ B* ■p o o cd ml d » 31 H M 0 OO C^^O li si 53 ;n^ ^^^ ^7^75v^^ l-> -< «< «< COOT OTCOOT OT m CO OT 03 dno o r- o oo CO za gS oo coco *< S ss oo ooo ooooc He- H e-< fe fe feNBti fcfk,et,fep:, §C4 b ehehh e-* e^e-t t* hh ne^ he-" fa^ 35:3 ;:^5 35 coco CO OT EOfl< C00-<03 6-« O ZS5 O h pt,(k,pc,p<(-(M&il P* g 2 X s (Q tie >>tiO U £1 Vi -1 » g D ■a w a CO a CO a E to : U -H Xi ^» 129 CHAPTER 6 RELATION BETWEEN CONSUMPTIVE USE AND DEPTH TO WATER TABLE In all investigations involving determination of consump- tive use of water by grasses in tanks in which a predetermined water table has maintained, there has been evidence of a straight- line relation between depth to water table and amount of water consumed. To show this relation graphically for those experimen- tal stations where sufficient data exist, Figure 15 has been pre- pared with saltgrass the medium of the comparison. The plotted points do not always agree with the average; occasionally one is obviously out of line, but enough records have been found consis- tent to permit a close representation. 20 30 Consumptive use of water (inches) FIGURE 15.-- Relation of consumptive use of water by saltgrass in tanks to depth to water table. 130 In an analysis of this chart there are a number of factors to consider, the principal ones probably being climate and soil. Climate regulates consumptive use and length of growing season. The fineness of the soil determines the amount and limiting height of water held by capillarity above the water table and the probable depths to which saltgrass roots extend for moisture. As these investigations were conducted under conditions varying as to length of growing season and soil, the charts for each sta- tion would not be expected to show the same relation. However, in most cases they show the same general slope. Where data are available, consumptive use is plotted for a 12-month period, although there is considerable variation as to the time each period begins. Thus the Owens Valley data begin in January and end in December; Santa Ana data are for May to April; Los Griegos from October to September; and Escalante Valley, Utah, from May to October. These differences are deemed unimportant, however, as long as a complete cycle of seasons is included. In his report of the Owens Valley study, Lee (16, 17) divided the year into summer and winter seasons and plotted the consumptive use-depth relation for each period separately. With- out discussing the benefits of such division, it is apparent that the two methods disagree when used to indicate the limiting depth to which saltgrass roots appear to function. This has been given for Owens Valley as 7.7 feet for the period April 1 to September 30, and 7-0 feet from October 1 to March 31. If consumptive-use data had been plotted for the entire year, however, the limiting depth would appear to be somewhat less. In comparison, the limiting depth for a 12-month period at Santa Ana appears to be 5.3 feet for fine sandy loam soil, and 3.8 feet at Los Griegos for clay loam soil. Consumptive -use data for Owens Valley and Santa Ana plot as parallel lines, yet the Owens Valley curve represents approximately 10 inches greater use of water for any given depth to water table. 131 Los Griegos curve also indicates a straight-line relation although it lies lower on the chart and departs from the parallel- ism of the previous curves. It indicates nearly 9 inches less consumptive use than at Santa Ana for a 24-inch depth to water and 12.5 inches less as the water table lowers to 36 inches. It is evident from these curves that for given depths to water table, saltgrass in the Owens Valley has a greater consump- tive use than at other places of investigation, with decreasing amounts at Santa Ana, Los Griegos, and in Escalante Valley. 132 CHAPTER 7 RELATION OF CONSUMPTIVE USE TO EVAPORATION Throughout this report the relation between consumptive use and evaporation, first mentioned in the Introduction, has been stressed as a basis of estimating water used by plants when only evaporation is known. The relation varies month by month, reaching a maximum in summer and a minim\im during the cooler months of the growing season. Thus, the relation for any period is an average which may have a considerable departure from the value for any single month. For the more water-loving species summer consumptive use exceeds evaporation, but for many dry-land plants it is less. Since consumptive use becomes less with in- creased depth to ground water, its relation to evaporation is partly governed by the position of the water table. Few attempts have been made to determine, by experiment, the consumptive use-evaporation relation. The Victorville, Calif, investigation with tules, previously described, is probably the most significemt and perhaps the only experiment undertaken di- rectly for this purpose (4). The results indicated, for the particular region in which the investigation was carried on, that annual use of water by tules was equal to 95 per cent of the an- nual evaporation from a standard Weather Bureau pan with monthly values ranging from 57 to 122 per cent. For other areas in the same climatic territory where evaporation records are available, use of water by tules may be computed as a percentage of the evaporation. At Los Griegos, the annual use of water by tules was as low as 83 per cent of the evaporation. A graphical comparison of monthly use of water by tules growing under natural conditions and evaporation from a Weather Bureau pern, in four southwestern localities, is shown in Figure 16. Table 42 gives the percentage relation for tules by months at various locations. 133 c ^ 1 1 ^ ^ -^ -^ "^ ^ Q» Victorville, California Consumptive Use Tot 78 ol f .45 or y inc ear hes J. 1 1 ll 1 1 I Evopor ation Tof 82 ol f .46 or > in 1 ear :he8 1 1 1 1 ll 1 1 Isleta, New Mexico Consumptive Use Tol 67 ol . 67 una inc to Nov. M. 1 1 1 1 1 1 Evaporation To 44 ol V .34 unt in( to Nov. III 1 20 20 10 10 0 I 0 10 10 0 0 II Mesilla Dam, New Mexico Consumptive Use Tot I2E alf J.I6 jr y inc ear nes 1 1 1 1 1 1 1 Evaporation | To 79 tol .15 or inc 1 ireor lies 1 1 1 1 III 1 X 10 10 0^0 ■c; 10 10 0 0 San Luis Valley, Colorado Consumptive Use To 38 ol .77 Jun« int ) to Not 1. 1 1 1 ■ Evaporation | To 30 tol .80 Jun inc 1 to hes No V. 1 1 1 1 1 X FIGURE 16. — Comparison of consumptive use of water by tules in swamps and evaporation from a Weather Bureau pan. 134 ::^ CO ■p r^ rt •iH o iM ONOOOf^-d-rHHuMXlosn-N pH rHrHOjrvJCVrH r-t p ^ m ■p .H d •H Q) cd o p p ^1 cd CD o CM 1 C~-sO u^-4- o S! „ P CQ • rt O X m 0) CQ M 0) (D o O CD S iH hJ-H ;3 fH ^( • E-i (D oa ^^ P- " C! CO • CQ 0 S o (D o R iH iH CO O 0 tl (U o H (D O«0 to O u>-d-C7\r^vO O f^vO irM/Mr\v,0^0C0rHC\iOu^u^--0 rH iH fH r^C-^rvi to vO I rH .H rH Cd tjDO CQ p> rH CI •H 0 Cd o P tH 01 cu o PM P> rt tfj 0) fl) o r-i 0 fn H 0 PM I I I \D to r^ C-- -:}• I r^ ^ nH rH rH I -4-\0 CV r^C^ I I 1 ■P U - ' d O CD Vi CO CD P fH -H CD o O r-l H .H •H -H cd 0 fH > > O iH 0 PM C^i rH C^ UA O -j-^O UA OJ to OS C\i OvO u^vO tOOrH>-lf\iOsO[> r-\ r-{ r-{ r-\ r-\ m • CD cn :3 a cd cd > O cd &p ■P o ^1 >> (D ^^ fH >> U ^ ^^ CD (D fH cd p a CD ^ £1 Qi 0 Xi ,-\ CQCD^Sa :3^otH (Dt>>:3p>0(DcD a^tHtH>>ciM5)DP

o cO(DcdP)Cd3::<3 cd < pq |X H-3 135 In considering other native plants a high percentage of consumptive use to evaporation results from a high water table. This is demonstrated for saltgrass as shown in Table 43. Also, a comparison of consumptive use of water by saltgrass and evapo- ration is shown for four localities in Figure 17. Table kk gives consumptive use-evaporation percentages for Bermuda grass, wire rush, willows, sedge, native meadow, and greasewood grown in tanks under different ground-water conditions. Plates V to VIII show typical examples of different kinds of native vegetation growing under various soil, ground water, and other conditions and environments. 136 m 4-> •* C t>> crt (D xi iH iH cd m M -p a cd t) CO > 1 W 1 ^ (h a 0 CD Ph o 1 +J fH a CD (D (-L( o 1 +3 fn 0 UJ U) tin o I CV -^ n^MD to I I I H rH -J- CV I I 1 I I I ICVr^CVCVrHI I rHr\JrHC\ir-lr^tX)tOC7NC^-4-f^ 01 X -p (1) CD S m M a m o • M W| (1) (1) •rH S Jh r1 s r/j n H-l CO •H ;3 • H^ o rH n o nJol CO - >: ■p (D -p iH m rH d (Si fH>l 01 o ^1 -4-1 1 +J u a 0) a) P4 o ^1 rt (1) 0) (^ o 1 +J 5h p! Q) fl) (^ o I -p tn c! a; Cl) (-L| o 1 ■p In a 0) a) f^ o 1 ■p u n Cl> 0 Pu o fH a 0) CI) ^i^ o 1 -p ^H d a; (1) t^H o 1 ■p U d (1) 0) Ph o v£iC\JOrviOrvivOO-<3-tXD\OiH «0iHC0-^OOC\fCVC0r^C\irH nH CV rH - c\; i/NsO \o I I ir\ C-- C-- r^ -:!• I I to (M -C^ I 1 ■p ^1 a (]) OJ l^ o 1 -p u a Cl) a) iM o 1 ■p u rt (U 0) m o (0 0) rHiHrHrH rHCNir^C^CXirHiH [>[>--d-r^ I cv to o ON CNJ cM> (>iCViHt00r^r^CNir^COrHtO [>-tO--d-0vi-4-CVuArH CNJ^r^OJ uMJA-^\o u^r^toto [>-vO\o r^ fH CO to d ^ rH :3 tH > 0 +J O (D (D Cl^tHfHl>>iZ!rHbD 0(-P > cd CD cO Oi^ d d d ^l^ ■p ^ p> a n o o ft S Td rH ::;i^ 137 0!! to Sonto Ana, Colifornio Consumptive Use Totol for yeor 36.24 inches 111 iiiii Evaporotion Total for year 63.23 inches 5 ■ 0 0 10 ^ 10 Los Griegos, New Mexico Consumptive Use Evaporotion Totol for year 80.09 inches Son Luis Valley, Colorado Consumptive Use ' Total J_ May to Oct. 18.36 inches li ' Totol 1~ May to Oct. 31 '20 inches Evaporation 0 0 0 0 Escalante Valley. Utah I Total May to Oct. ^~ 17.88 inches Consumptive Use Evaporation I Totol I May to Oct. 69.83 inches FIGURE 17.-- Comparison of consiimptive use of water by saltgrass where approximate depth to ground water is 24 inches, and evaporation from a Weather Bureau pan. 138 0 -p '■ 1 C3 >> (D cd o M ^1 cfl • Q) ^ a o > o fH rH •H Tl CO O ■P 01 FM o - I I I I I I <-^ -cj- ^ -d- CNJ I \ to r-^Oi -d-\0 I rH rH ,H I C\J -J-vO CV O I r-t •-{ r-{ r-{ ,-{ I OA to u-N CTN CNi vO tX) -j- to (^ -4- I !^\0 ONvO t^tO OrH C^tO^O (^itOC^C^"^tO-c^Or^^Oor«^ OOiHCVC\if\juAC~-C^C^ufNrH rHrHrHrHi-HrHrHrHrHrHCV tOO"^rH(VCVi-|vO-c}-:>UAO C\i Cvj rH -4- ^vO vO 1^ Lf\ C\2 CV rvj HrHCVu^i^C^r^C^vOr^rviCV O Q) u o > >> (D ti p •H >iU ^ U 03 Hi o^l P 0 fn CO +^ d t>>;3+jO0jf:!Ht5DaiP>O (Odd coa>(flP)ca:3:3dQ)ooa) 0) ^K -H HaNS«l^-l Hs 3\ 139 PLATE V ^ L. A. Dense growth of bank vege- tation using water from an irrigation canal in Imperial Valley, Calif. Wild sunflower plant in California. Sunflowers are remarkably thrifty for long periods in very dry places. Mesquite in the Coachella Valley, Calif., illustrating size of bush. This is found in areas where ground water is within reach of root systems. The size is an indication of depth to water table; high ground water results in tall, dense growth. 140 PLATE VI I A. Tall, dense cottonwood and willow growth along dry bed of San Luis Rey River, San Diego County, Calif. Much of the surface flow sinks into the gravels and is absorbed by vegetation. B. Typical swamp area. Tules use large amounts of water. 'i L ..-AJEiS^ii^^ «^?r^i V »L J^iL'^A^^^^oil^H J C. Tules 6 to 8 feet high, growing in open water. PLATE VII r mm .^^^•MMtft^^ ^ ^t^^T^ ^ ■ ■...^^yH WMmm ■j^Bj^flBk KT^^B ^m -Ar„ata and Information on the Central Valley Project and the Great Central Valley Basin of California, 1941. Auxiliary Electric Power Facilities Required for Central Valley Project, 1942. • Reports and Bulletins out of orlnt. These may be borrowed by your local library from the California State Library at Sacramento, California. 15426 8-42 2M THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW BOOKS REQUESTED BY ANOTHER BORROWER ARE SUBJECT TO IMMEDIATE RECALL II PLC ^ i ^M DEC 2 0 19«S''JUN 18 1993 PHYS SCI UBRAWB RECtlvS^^ OCT 0 '> 1993 FEB 2 6 199( ,,, ZLos, RECEIVED PJiYSICALSCSAlBRARY FEB 1^^ u^jO PHY SCI LIBRARY JW NOV 1 2 199 NOV 8 199Gh^G MAT zd 1399 RE CO ^ RECEIVED " /may 2 A 1999 RECEIVED LlBM«er,SONlVBl»H¥ OF CALIFORNIA, DAVIS Book Slip-Series 458 PHYSICAL SCIENCES LIBRARY •f1 LIBRARY UNIVERSITY OF CALIFORNIA i^ DAVIS 110990