Full text of "FWS/0BS"
FWS/OBS-80/0J
Biological Services Program
FWS/OBS-80/08
June 1980
Gravel Removal Studies in Arctic
And Subarctic Floodplains in Alaska
NORTHERN INTERIOR
Interagency Energy-Environment Research and Development Program
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
and
Fish and Wildlife Service
SOUTHERN INTERIOR
U.S. Department of the Interior
The Biological Services Program was established within the U.S. Fish
and Wildlife Service to supply scientific information and methodologies on
key environmental issues that impact fish and wildlife resources and their
supporting ecosystems.
Projects have been initiated in the following areas: coal extraction and
conversion; power plants; mineral development; water resource analysis,
including stream alterations and western water allocation; coastal
ecosystems and Outer Continental Shelf development; National Wetland
Inventory; habitat classification and evaluation; inventory and data manage-
ment systems; and information management.
The Biological Services Program consists of the Office of Biological
Services in Washington, D.C., which is responsible for overall planning and
management; National Teams, which provide the Program's central scien-
tific and technical expertise and arrange for development of information
and technology by contracting with States, universities, consulting firms,
and others; Regional Teams, which provide local expertise and are an
important link between the National Teams and the problems at the
operating level; and staff at certain Fish and Wildlife Service research
facilities, who conduct in-house research studies.
W H 0 I
DOCUMENT
COLLECTION
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FWS/OBS-80/08
June 1980
GRAVEL REMOVAL STUDIES IN ARCTIC
AND SUBARCTIC FLOODPLAINS IN ALASKA
Technical Report
by
Woodward-Clyde Consultants
4791 Business Park Blvd., Suite 1, Anchorage, Alaska 99503
Contract Number
FWS- 14- 16-0008-970
Nerval Netsch, FWS Project Officer
Water Resources Analysis Project
Biological Services Program
U.S. Fisfi and Wildlife Service
1011 E. Tudor Drive
Anchorage, AK 99503
Tfiis study was funded
in part by tfie
Interagency Energy-Environment
Researcfi and Development Program
Office of Researcfi and Development
U.S. Environmental Protection Agency
Performed for tfie
Water Resources Analysis Project
Office of Biological Services
U.S. Department of tfie Interior
Wasfiington, DC 20240
DISCLAIMER
The opinions, findings, conclusions,
or recoinmendations expressed in this
report are those of the authors and
do not reflect the views of the Office
of Biological Services, Fish and Wild-
life Service or the Office of Research
and Development, U.S. Environmental
Protection Agency.
EXECUTIVE SUMMARY
A 5-year gravel removal study was initiated in mid-1975 to evaluate the
effects of gravel removal from arctic and subarctic floodplains in Alaska.
The primary purpose of the project was to provide information that will
assist resource managers in minimizing detrimental environmental effects
resulting from floodplain gravel mining. To achieve this objective 25 ma-
terial sites were studied by a team of scientists and engineers. Two major
products of the project are a Technical Report which synthesizes and eval-
uates the data collected at the sites, and a Guidelines Manual that aids
the user in developing plans and operating material sites to minimize envi-
ronmental effects.
Data from the 25 study sites were collected and analyzed by the follow-
ing six d i sc i p I i nes :
• River Hydrology and Hydraulics
• Aquat i c Biology
• Terrestrial Ecology
• Water Qual i ty
• Aesthet i cs
• Geotechnical Engineering
Data Analysis compared the Physical Site Characteristics (drainage basin
size, channel width, channel configuration, channel slope, and stream ori-
gin) and the Gravel Removal Area Characteristics (type of gravel removal
method, location of gravel removal, and age of the gravel removal site) with
the measured effects of mining activities.
The general conclusion reached was that proper site selection and
project design facilitate gravel mining with minimal effects on the habi-
tats and fauna of floodplains. The key to the successful mitigation of
potential detrimental effects is to carefully match the material site design
and operation (site location, configuration, profile, schedule, and rehabil-
itation) with the Physical Site Characteristics of the selected floodplain.
VARIABLES INFLUENCING MINING EFFECTS
Physical Site Characteristics
Among the Physical Site Characteristics, channel configuration was
the most important. Potential floodplain change is least for a braided river
and greatest for a straight river. Size of channel is an important factor,
with the least change to be expected in a large system and the greatest in a
small system (assuming equally-sized material sites). Combining these two
variables (channel configuration and size), gravel removal operations can be
expected to have the least effect on large braided rivers and the greatest
effect on small straight rivers.
Other influencing Physical Site Characteristics, which are related to
configuration and size, are the availability and size of unvegetated gravel
bars, floodplain width, and the distance that can be maintained between the
mining site and the active channel. For example, in a small straight river
system the floodplain is narrow and gravel bars are neither plentiful nor
large. Thus, to extract gravel, either a significant length of active flood-
plain or the adjacent inactive floodplain and terrace must be disturbed. In
the latter case the narrowness of the floodplain forces the operation to
closely encroach upon the active channel. In large river systems these
problems can be less significant because gravel bars are larger and, if the
inactive floodplain or terrace are used, the wider floodplain allows mainten-
ance of a broader undisturbed buffer zone between the material site and
act i ve f I oodp lain.
IV
Gravel Removal Area Characteristics
All of the Gravel Removal Area Characteristics were found to signifi-
cantly influence the effects of gravel mining. The location of the material
site relative to the active channel is considered to be the most important
factor. Whether a material site is scraped or pit-excavated is important,
but often pits are located away from an active channel, avoiding the types
of changes that can be associated with scraping in active floodplains.
The major effects of pit sites located in inactive floodplains and
terraces are the loss of vegetated habitat, the possibility for the occur-
rence of fish entrapment, a change in the appearance of the floodplain, and
long-term delay in the re-establishment of predi sturbance conditions. Where
pit sites are situated close to active channels, particularly on the inside
bends in meandering systems, the possibility exists for diversion of the
channel through the pit, eventually forming a channel cutoff in the meander.
This highlights the importance of providing a buffer between the material
site and the active channel. Where pit sites are of suitable size, of suffi-
cient depth, and have contoured perimeters, they can increase local habitat
diversity and provide conditions suitable for fish and various species of
terrestrial fauna.
Scraped material sites in active floodplains have minimal effects
on the floodplain environment when only exposed gravel bars are excavated
above the water level, and when slope and contours are maintained (resem-
bling those of natural bars). Removal of vegetated areas or banks, which
resu I ts in decreased I atera I stab i I i ty of act i ve channel s or a I lows water to
spread over a large area, is not desirable. Decreased water depth and veloc-
ity increases sedimentation rates, alters water temperature, and alters
dissolved oxygen levels. These changes in aquatic habitat usually affect the
local distribution and community structure of benthos and fish.
The effects of scraping in vegetated areas of inactive floodplains
and terraces can be similar to those described for pits. However, long-term
changes typically are minimal because the lack of standing water in the
closed site will facilitate re-estab I i stiment of pre-mining vegetation con-
di t ions.
If material sites are located and operated to prevent or greatly mini-
mize effects on channel hydraulics, and to utilize only exposed gravel
bars, the probability of major localized changes to a floodplain generally
is greatly reduced. Where exposed gravel bars are not available or are
inadequate, a tradeoff decision between sites must be made that weighs the
potential effects of aquatic disturbances against terrestrial disturbances.
In these cases, minimization of hydraulic change to active channels should
be important in the decision — major hydraulic changes can have a greater
long-term effect on terrestrial systems than the controlled disturbances
associated with a site located in a vegetated inactive floodplain or ter-
race.
RECOMMENDED FUTURE STUDIES
During the present study a number of subject areas were identified
that should be investigated.
1. Evaluation of gravel mining from coastal and upland sources; and,
preparation of guidelines for users of these sources. These alternatives to
sources have not been studied.
2. Evaluation of the effects of multiple sites on one river system.
Such an investigation should be aimed at determining the critical, spatial,
and temporal relationships of multiple sites. Gravel replenishment rate
predictions should be an integral part of this investigation.
3. Several floodplain gravel removal sites should be investigated
before, during, and after mining to assess the adequacy of the Guidelines
Manua I .
4. Several topics of the Guidelines Manual should be studied in detail
to assess their adequacy, (i.e., buffers, pit design, and active channel
dredging) .
VI
This report was submitted in fulfillment of Contract Number 14-16-
0008-970 by Woodward-Clyde Consultants, Anchorage, Alaska, under sponsor-
ship of the Office of Biological Services, U.S. Fish and Wildlife Service.
Work was completed as of June 1980.
VI I
TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY
LIST OF FIGURES
LIST OF TABLES
ACKNOWLEDGMENTS
INTRODUCTION, E. H, Follmann
BACKGROUND
PHILOSOPHY
PROJECT DESCRIPTION
REFERENCES
APPROACH AND METHODOLOGY, E. H. Follmann ....
SITE SELECTION
DATA REVIEW
FIELD STUDY OF SELECTED MATERIAL SITES
DATA BASE
TECHNICAL REPORT
GUIDELINES MANUAL
REFERENCES
DESCRIPTION OF STUDY RIVERS, L. L. Moulton, Ed.
SEWARD PENINSULA
NORTH SLOPE
NORTHERN INTERIOR
SOUTHERN INTERIOR
REFERENCES
EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND
HYDRAULICS, L. A. Rundquist
INTRODUCTION
METHODS OF DATA COLLECTION
METHODS OF DATA ANALYSIS
HYDROLOGY
HYDRAULICS
QUANTIFICATION OF CHANGES
RESULTS AND DISCUSSION
CHANNEL CONFIGURATION AND PROCESS
HYDRAULICS
SEDIMENTATION
ICE CHARACTERISTICS
HYDROLOGY
SUMMARY AND CONCLUSIONS
CHANNEL CONFIGURATION AND PROCESS
HYDRAULICS
SEDIMENTATION
ICE CHARACTERISTICS
HYDROLOGY
RECOMMENDATIONS
REFERENCES
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Page
EFFECTS OF GRAVEL REMOVAL ON AQUATIC BIOTA,
L. L. Moulton 141
INTRODUCTION 141
METHODS OF DATA COLLECTION 144
METHODS OF DATA ANALYSIS 145
RESULTS AND DISCUSSION 148
MAJOR GRAVEL REMOVAL HABITAT ALTERATION 148
EFFECTS OF HABITAT ALTERATION ON FISH POPULATIONS .... 167
EFFECTS OF HABITAT ALTERATION ON AQUATIC
MACRO INVERTEBRATES 198
SUMMARY AND CONCLUSIONS 209
EFFECTS OF GRAVEL SCRAPING ON RIVERINE HABITATS 209
EFFECTS OF INUNDATED PIT FORMATION ON THE
ASSOCIATED RIVER BIOTA 211
RECOMMENDATIONS 213
REFERENCES 214
EFFECTS OF GRAVEL REMOVAL ON TERRESTRIAL BIOTA,
M. R. Joyce 215
INTRODUCTION 215
METHODS OF DATA COLLECTION 218
METHODS OF DATA ANALYSIS 220
RESULTS AND DISCUSSION 222
VEGETATIVE COMMUNITIES OF STUDY AREA FLOODPLAINS .... 222
VEGETATIVE COMMUNITY CHANGES AT GRAVEL REMOVAL
SITES 225
FACTORS AFFECTING VEGETATIVE RECOVERY RATE 241
FAUNAL COMMUNITY CHANGES AT GRAVEL REMOVAL SITES .... 248
FACTORS AFFECTING RECOVERY RATE OF FAUNAL COMMUNITIES . . 253
PERMANENTLY PONDED SITES 254
SIMILARITIES OF RESPONSE BETWEEN BIOTA AND STUDY
SITE PARAMETERS 259
SUMMARY AND CONCLUSIONS 268
VEGETATIVE REMOVAL 268
MINING DEPTH AND LOCATION 268
OVERBURDEN 269
PERMANENTLY PONDED HABITATS 269
RECOMMENDATIONS 270
REFERENCES 271
EFFECTS OF GRAVEL REMOVAL ON WATER QUALITY,
L. L. Moulton 273
INTRODUCTION 273
RESULTS AND DISCUSSION 276
POST-MINING EFFECTS OF GRAVEL REMOVAL OPERATIONS .... 276
SUMMARY AND CONCLUSIONS 284
REFERENCES 285
IX
Page
EFFECTS OF GRAVEL REMOVAL ON AESTHETICS,
D. K. Hardinger 287
INTRODUCTION 287
SCENIC QUALITY 289
VISUAL SENSITIVITY 289
DEGREE OF VISIBILITY 290
APPROACH 291
THE VISUAL RESOURCES OF THE STUDY REGIONS 292
SEWARD PENINSULA 292
NORTH SLOPE 295
NORTHERN INTERIOR 297
SOUTHERN INTERIOR 300
EFFECTS OF GRAVEL REMOVAL ON VISUAL RESOURCES . 304
SEWARD PENINSULA 504
NORTH SLOPE 305
NORTHERN INTERIOR 306
SOUTHERN INTERIOR 306
SUMMARY 308
GEOTECHNICAL ENGINEERING CONSIDERATIONS OF GRAVEL
REMOVAL, H. P. Thomas and R. G. Tart, Jr 311
INTRODUCTION 311
APPROACH 314
SITE SELECTION AND INVESTIGATION 315
PRELIMINARY SITE SELECTION 315
SITE INVESTIGATION 317
FINAL SITE SELECTION 318
MINING PLAN PREPARATION 319
SITE PREPARATION 321
ACCESS 321
OVERBURDEN REMOVAL 324
CHANNEL DIVERSION 324
SETTLING PONDS 325
SITE OPERATION 326
EXCAVATION 326
TRANSPORTATION AND STOCKPILING 327
PROCESSING 328
SITE REHABILITATION 329
REFERENCES 330
INTERDISCIPLINARY OVERVIEW OF GRAVEL REMOVAL,
E. H. Follmann 331
INTRODUCTION 331
PHYSICAL SITE CHARACTERISTICS 333
CHANNEL CONFIGURATION 333
DRAINAGE BASIN SIZE (CHANNEL WIDTH) 348
CHANNEL SLOPE AND STREAM ORIGIN 350
GRAVEL REMOVAL AREA CHARACTERISTICS 354
TYPE OF GRAVEL REMOVAL 354
LOCATION OF GRAVEL REMOVAL 565
DIKES AND STOCKPILES 576
Page
SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS 379
SUMMARY 379
RECOMMENDATIONS 382
RECOMMENDED FUTURE STUDIES 384
APPENDICES
A. SCIENTIFIC NAMES 385
B. GLOSSARY 395
XI
L 1ST OF FIGURES
Number Page
1 Location of the 25 gravel removal study
sites in Alaska 13
2 Typical Seward Peninsula terrain 37
3 Arctic Coastal Plain wetlands 43
4 Northern portion of the Arctic Foothills ...... 44
5 Typical view of the White Hills section
of the Arctic Foothi I Is 44
6 M. F. Koyukuk River valley looking upstream .... 52
7 Typical terrain of the Kokr i ne-Hodzana Highlands . . 53
8 Typical terrain in the Yukon-Tanana Upland Section . 59
9 G I ac i of I uv i a I deposits in Dry Creek floodplain ... 60
10 Typical view of Alaska Range section 61
11 Aerial photograph showing the two gravel
removal locations at Sinuk River considered
separately in the hydrology/hydraulics analysis . . 75
12 Aerial photograph of Washington Creek showing
the upper and lower gravel removal areas 77
13 Aerial photograph of Oregon Creek showing
the upper and lower gravel removal areas 78
14 Aerial photograph of Aufeis Creek showing
upper and lower gravel removal areas 79
15 Aerial photograph of Middle Fork Koyukuk River-
Upstream showing upper and lower gravel removal
areas 80
16 Schematic diagram of the plan view and cross
section of a typical braided river 83
17 Maximum depths and corresponding top widths of
undisturbed major, side, and high-water chan-
nels at four braided study sites 84
Number Page
18 Schematic diagram of the plan view and cross
section of a typical split channel river 85
19 Maximum depths and corresponding top widths of
undisturbed major, side, and high-water channels
at four split channel study sites 86
20 Schematic diagram of the plan view and two
cross sections of a typical meandering river 87
21 Maximum depths and corresponding top widths of
undisturbed major, side, and high-water channels
at 15 study sites with meandering, sinuous, and
straight configurations 88
22 Schematic diagram of the plan view and cross
section of a typical sinuous river 90
23 Schematic diagram of the plan view and cross
section of a typical straight river 90
24 Schematic diagram of an al I uv i a I fan 91
25 Comparative aerial photography of the Nome
River showing change in channel configuration
resulting from gravel removal activities 96
26 Aerial photograph of the Ugnuravik River pit
site showing the insufficient buffer zone 98
27 Aerial photograph of the Tanana R i ver-Upstream
site with substantial buffer zone separating
the pit from the active side channel 100
28 Aerial photograph of the Prospect Creek pit
showing wide buffer zone separating the pit
from the active channel 101
29 Schematic diagram illustrating definitions of
channel geometric and hyraulic variables 102
50 Average hydraulic geometry of river channels
expressed by relations of width, depth, and veloc-
ity to discharge at two locations along a river
(modified from Leopold, Wolman, and Miller 1964) . . . 104
31 Schematic diagram showing change in water
surface slope in response to a change in
water discharge 105
XIII
Number Page
32 Schematic diagram illustrating the effects
of a flow obstruction on the local hydraulics .... 107
33 Comparative aerial photography of the Penny
River showing change in hydraulic character-
istics resulting from gravel removal activities ... 113
34 Schematic diagram illustrating an example of
a change in local water surface slope result-
ing from an in-channel gravel removal operation ... 114
35 Schematic diagram showing degradation process .... 116
36 Upstream view of thermal and fluvial erosion
in the access road at Ugnuravik River, acting
as a long-term sediment source to the river 123
37 View of erosion of a diversion dam which acts
as a long-term sediment source to Skeetercake
Creek. Dunes in foreground are atypical of the
undisturbed river 123
38 Large area of aufeis at the upper gravel
removal area at Washington Creek as it
appeared in early June 125
39 Aerial photographs of Washington Creek (top) and
Aufeis Creek (bottom) showing material site loca-
tions and approximate channel locations before
the disturbance 133
40 Siltation resulting from extensive aufeis
field at Oregon Creek mined study area,
20 June 1977 14-9
41 Removal of bank cover at Oregon Creek as
observed on 24 June 1977 152
42 Removal of bank cover at Skeetercake Creek
as observed on 18 June 1977 153
43 Washington Creek upstream and mined area on
9 September 1977 showing reduction of instream
cover due to gravel removal operation (flow
level [O. I I mVsec] = 20 percent of mean
annual flow). Other habitat alterations include
increased braiding, siltation, and intergravel
f I ow I 54
X IV
Number
Page
44 Reduction of instream cover as provided by
boulders at Sagavanirktok River, 3 August 1978
(flow level, 60 mVsec, = 155% of estimated
mean annual flow) 155
45 Increased braiding at Sagavanirktok River study
site caused by mining mid-channel gravel bars
and a vegetated island in the active channel
(mining operation conducted during the winter
of 1974-1975) 157
46 Response of cross-sectional wetted perimeters
to percentage of mean annual flow and percent-
age of cross sections comprised of selected
depth intervals at mean annual flow at three
gravel removal study sites 158
47 Low velocity backwaters formed by gravel removal
at Dietrich River-Downstream (13 July 1978) and
Middle Fork Koyukuk R i ver-Upstream (18 July 1978),
note extensive silt deposition in both cases .... 159
48 Creation of low velocity side channels and
inundated pit following gravel extraction 160
49 Sequence of aerial photographs showing effects
of overmining the inside of a meander bend
at Middle Fork Koyukuk Ri ver-Upstream. Immedi-
ately following mining (b) there was an increase
in backwater areas. The next year (c) the
meander was partially cut off, creating a vari-
ety of low velocity habitats 163
50 Temperature and dissolved oxygen profiles at
four deep gravel pit study sites 165
51 Ponded area at Kuparuk River study site where
three seine hauls captured 61 Arctic grayling
and 2 slimy sculpin, 9 August 1978 (pool I in
Table 21 ) 179
52 Ponded area at Middle Fork Koyukuk-Upstream
study site where one seine haul captured 28
Arctic grayling, 3 round whitefish and 3 slimy
sculpin, 18 July 1978 (pool 2 in Table 21) 179
53 Potential migration blockages, aufeis fields
at Washington Creek and Oregon Creek, June 1977 . . 182
54 Region where Aufeis Creek went subsurface
creating migration blockage due to lack of
surface f low 183
XV
Number Page
55 Prospect Creek study site - shallow pond habitat
supporting Arctic grayling, Chinook salmon juven-
iles, round whitefish, northern pike, burbot,
and slimy sculpin, 12 August 1978 188
56 West Fork Tolovana River study site - deep pond
with extensive shallows providing northern pike
and Arctic grayling habitat, 29 July 1978 188
57 Tanana Ri ver-Upstream upper pit showing exten-
sive vegetation beds, 18 August 1978. Note
difference in the extent of vegetative develop-
ment in this 13-year old pit as compared to the
2 and 3-year old pits in Figures 55 and 56 190
58 Potential overwintering area at Willow Creek.
This spring-fed tributary, open throughout the
winter, had previously entered Penny River
at a deep pool 192
59 Creation of a potential overwintering area at
West Fork Tolovana River downstream from pit 196
60 Densities of selected aquatic macroi nver tebrates
at Aufeis Creek study areas during 1977 sampling
trips 206
61 Penny River undisturbed floodplain showing typical
North Slope and Seward Peninsula floodplain charac-
teristics of sinuous channel bordered with dense
shrub thickets with incised outside meander bank,
and narrow gravel point bar on inside meander .... 224
62 West Fork Tolovana River showing typical South-
ern and Northern Interior medium river flood-
plain characteristics with shrub thickets and
white spruce-paper birch stands along the
riparian zone 224
63 West Fork Tolovana River showing permanently
flooded pit excavated adjacent to the active
floodplain with a downstream connection 226
64 A view of Oregon Creek looking downstream
through the mined area showing site conditions
that remain 13 years after gravel removal 229
65 Penny River mined area looking upstream. Note
the flooded conditions within the disturbed
area, and the overburden piles in the center
of the site 230
XVI
Number Page
66 Close-up view of an overburden pile in the Penny
River mined area. Note the development of herbace-
ous and woody vegetation during the II years
fol lowing gravel removal 234
67 Washington Creek mined area showing vegetative
recovery only present on the overburden pile
13 years after gravel removal 234
68 Woody revegetation occurring through develop-
ment of adventitious stems 235
69 Distribution of woody slash debris and other
organics over the ground on the edge of the
gravel removal area at Aufeis Creek 236
70 View of the upper pit at Tanana Ri ver-Upstream
showing diversity of shoreline configuration
and development of woody and herbaceous vegeta-
tion 13 years after gravel removal 237
71 View of the Ivishak River floodplain looking
downstream showing typical braided channel
characteristics with extensive gravel bars and
isolated, vegetated islands 239
72 View of both undisturbed (background) and mined
(foreground) reaches of the Shaviovik River.
Note that gravel removal maintained natural
point bar contours and shapes and did not
disturb riparian vegetative zones 240
73 Compacted surface gravels in an access road
leading to the Dietrich River-Downstream site .... 244
74 Inorganic overburden piled on the edge of the
Oregon Creek site which supported no vegetation
13 years after gravel removal 244
75 Close-up of dense and diverse vegetative devel-
opment in an area of surface broadcast of woody
slash and organics. Note the willow adventi-
tious stem development 246
76 Distant view of a large silt depositional
area at the Sagavan irktok River study site 247
77 A silt depositional area of the Kavik River
supporting a well-developed pioneer vegetative
community 247
XVI
Number Page
78 Close-up of a concentration of willow seedlings
at the shoreline of the Jim River ponded area .... 248
79 Vegetated organic mats that were washed down-
stream and grounded during high water on Toolik
River floodplain gravel bars 249
80 Tanana Ri ver-Upstream showing shoreline diver-
sity and vegetative development in the upper pit . . . 256
81 Undisturbed buffer along the original stream
channel at Aufeis Creek (downstream disturbed
area only) 264
82 Gravel fill ramp used to protect the incised
bank at the Sagavan irktok River study site 266
83 Thermal and hydraulic erosion of permafrost
induced by multiple passes of a tracked vehicle
across an unprotected incised floodplain
bank and adjacent tundra 267
84 Armored bank protecting the West Fork Tolovana
River pit from a channel diversion into the
mined site 267
85 Typical Seward Peninsula landform at Penny River . . . 293
86 Typical view of an Arctic Coastal Plain floodplain . . 295
87 Dietrich River valley 298
88 Lower Middle Fork Koyukuk River valley 298
89 McManus Creek val ley 501
90 Phelan Creek valley 302
91 Gravel ramp at Shaviovik River site providing
access over a permafrost river bank 322
92 Thermal erosion near Ugnuravik River resulting
from compaction and destruction of the vegeta-
tive mat overlying ice-rich permafrost soils . . . 323
93 Configurations of study rivers 335
XV I I
LIST OF TABLES
Number Page
1 Major Variable Matrix 15
2 Methods Used for Measuring Water Quality Parameters with
the Number of Replicates Taken per Study Area 21
3 Aquatic Biology Sampling Methods Used at Each Study Site. 24
4 Size and Quantity Values of the 25 Study Sites 36
5 Quantification Ratings of Change in Channel Configuration
Characteristics Resulting from the Gravel Removal
Operation at Each of the 25 Sites 93
6 Values of Exponents for Hydraulic Geometry Power Relations 106
7 Quantification of Change in Hydraulic Variables Resulting
from the Gravel Removal Operation at Each of the 25
Sites 109
8 Quantification Ratings of Change in Sedimentation
Characteristics Resulting from the Gravel Removal
Operation at Each of the 25 Sites 119
9 Quantification Ratings of Change in Aufeis Potential
that Resulted from the Gravel Removal Operation at Each
of the 25 Sites 126
10 Mean Annua! Flow Estimates at Each of the 25 Study Sites. 129
11 Calculated Discharges in m /s Corresponding to Selected
Recurrence Intervals for Each of the 25 Study Sites . . 130
12 Quantification Ratings of Change in Quantity of
Intergravel Flow Resulting from the Gravel Removal
Operation at Each of the 25 Sites 131
13 Major Habitat Alterations Observed at Sites Mined by
Scraping 150
14 Percent of Pit Area Composed of Selected Depth Intervals. 164
15 Effects of Cumulative Habitat Alterations on Fish
Populations in the Mined Area of Study Sites Mined
by Scraping 168
X I X
Number Page
16 Estimated Densities and Blomass of Arctic Char and Slimy
Sculpin at Washington Creek Study Site Based on
Repeated E lectroshock i ng of Blocked Sections of Stream
21-23 June 1977 172
17 Estimated Densities and Biomass of Arctic Ctiar and Arctic
Grayling at Kavik River Study Site Based on Repeated
E I ectroshock i ng of Blocked Sections of Stream, 1976 . . 174
18 Comparison of Fish Densities in Wined and Undisturbed
Areas as Determined by E I ectroshock ing Blocked
Sections of Stream at Kavik River Study Site, 1976 . . 175
19 Catch of Arctic Grayling per Angler Hour at Kavik
River Study Areas During Summer 1976 Sampling Trips . . 176
20 Change in Catch per Effort and Percent Composition of
Indicator Species at Selected Study Sites 177
21 Summary of Catch from Ponded Water Areas Isolated from
Active Channels at Two Study Sites 181
22 Mean Fork Lengths of Coho Salmon Caught by Minnow Trap at
the Penny River Study Site During 1977 186
23 Differences of Coho Salmon Mean Fork Length Between Sample
Areas and Associated Significance Levels, Penny River
Study Site During 1977 187
24 Physical Conditions at Pits Visited During Winter .... 193
25 Response of Aquatic Riffle Macro i nvertebrate Taxa to
Habitat Alterations Observed at Selected Study Sites . 199
26 Changes in Aquatic Macro i nvertebrate Densities at Sites
Exhibiting Type I and 2 Substrate Alterations 203
27 Densities of Aquatic Macro i nvertebrates Collected at
Inundated Pit Sites, 1976-1978 208
28 Quantitative Changes in Selected Terrestrial Biological
Parameters at Gravel Removal Study Sites 223
29 Location, Response Time, and Community Characteristics of
Vegetative Recovery at Selected Study Sites 232
30 Quantification of Change in Selected Hydrology Parameters
Which Were Impeding Vegetative Recovery at Study Sites 243
31 Qualitative Evaluation of Habitat Quality and Fauna Use at
Permanently Ponded Gravel Removal Sites 255
XX
Number Page
32 Bird Observations by Habitat Type Within the Control and
Disturbed Areas at Tanana R i ver-Upstream 3-7 June, 1978.
Numbers Indicate Minimum Individuals Known to Occur
in Each Habitat Type 257
33 Bird Observations by Habitat Type Within the Control and
Disturbed Stations at West Fork Tolovana River 9-11 June,
1978, Numbers Indicate Total Individuals Known to Occur
in Each Habitat Type 258
34 Two Way Coincidence Table Displaying a Hierarchial Clus-
tering of Similar Sites and Similar Biotic Parameters . 260
35 Selected Alaska Water Quality Standards 274
36 Water Quality Parameters Measured at Gravel Removal Sites
Which Exceeded Alaska Water Quality Standards 275
37 Changes in Turbidity and Suspended Solids Between Sample
Areas at Selected Study Sites 278
38 Relative Change of Water Quality Parameters Between Up-
stream and Downstream Sample Areas at Selected Study
Sites 281
39 Average Measured Values of Selected Water Quality Param-
eters at Study Sites with Inundated Pits 283
40 Interdisciplinary Rating of Cumulative Effect of Scraping,
Using Various Indices of Change on Study Sites Visited
from 1976 to 1978 338
4! Interdisciplinary Rating of Effects of Pits on Associated
Floodplains at Selected Study Sites Visited from 1976
to 1978 Using Various Indices of Change 359
A-l Vegetation Identified in the Text 386
A-2 Mammals Identified in the Text 387
A-3 Birds Identified in the Text 388
A-4 Fish Species Reported and Caught or Observed in Major
Geographical Areas Represented by the Twenty-Five
Sites 390
A-5 Aquatic Macro i nvertebrates Caught at Study Sites
During 1976-1978 Field Sampling 392
XXI
ACKNOWLEDGWENTS
Woodward-Clyde Consultants appreciates the contributions of a number of
scientists and engineers.
Dr. A. 0. Ott, now with the Alaska State Pipeline Coordinator's Office,
conceived the aquatic biology field program and was responsible for much
of its implementation. He also served as a principal investigator on the
study for one and one half years of the field phase.
Brent Drage, now with R & M Consultants, was responsible for early imple-
mentation of the hydrology field program.
Other scientists whose contributions have benefited the study are, James
A. Glaspell of the Alaska Department of Fish and Game; Michael A. Scott of the
U. S. Bureau of Land Management; and Dr. Keshavan Nair, Dr. Ulrich Luscher and
Robert Pitt of Woodward-Clyde Consultants.
A number of Woodward-Clyde personnel assisted in the field at various
times, including Donald 0. McKay (now with the U. S. Fish and Wildlife
Service), Kenneth E. Tarbox, Jonathan Isaacs, and Jerry P. Borstad.
Thanks are also due to Alyeska Pipeline Service Company and the Alaska
Department of Transportation for use of their photographs of some mining
sites and the use of their mining plans.
We are also grateful to Susan Ogle for graphics production and Marn ie
Isaacs for editorial review. And finally, we are deeply indebted to Jean
Borstad and Jayne Voorhis for report production.
The U. S. Fish and Wildlife Service Project Officer appreciates the tech-
nical and administrative assistance provided by Summer Dole throughout the
project and to Dr. Norman Benson for technical advice during the data collec-
tion and analysis phases. We thank the following individuals who reviewed and
commented on some portions or all of the report in draft form: Bob Bowker ,
Hank Hosking, Ronald Kinnuner, Jim Lewis, Lou Pamp I i n, John Stout and Jera I d
Stroeble, all with the U. S. Fish and Wildlife Service, various stations; Bill
Gabriel and Earl Boone with the Bureau of Land Management, Anchorage, Alaska;
Joe Childers and Bob Madison with U. S. Geological Survey, Anchorage, Alaska;
Dr. Alvin Ott with the State Pipeline Coordinators Office, Fairbanks, Alaska;
Bruce Barrett and Carl Yanagawa with the Alaska Department of Fish and Game,
Anchorage, Alaska; Brien Winkley, U. S. Army Corps of Engineers, Vicksburg,
Mississippi; and W. P. Metz and A. W. Schwarz with ARCO Oil and Gas Company,
Anchorage, Alaska.
XXIII
INTRODUCTION
E. H. Follmann
This Technical Report and the accompanying Gravel Removal Guidelines
Manual for Arctic and Subarctic Floodplains (Guidelines Manual) present data
analyses and conclusions resulting from a 5-year study of 25 floodplain
material sites in arctic and subarctic Alaska, and provide guidelines to
insure minimal environmental degradation when siting, operating, and closing
floodplain material sites. This study, its results and conclusions, and
these reports directly relate only to floodplains, although several aspects
may also be applicable in nonf I oodp I a i n locations.
BACKGROUND
A common denominator in all resource and industrial development is
the need for granular material; gravel is used worldwide for construction
projects and transportation routes. In the arctic and subarctic, however,
the presence of permafrost creates special construction problems that place
additional demands on the supply of gravel.
Even slight alterations in the permafrost thermal regime caused by
surface disturbances can cause thawing, thermokarst formation, subsidence,
and erosional problems. Maintenance of the thermal regime is essential
when building or operating in permafrost areas, but especially in regions
characterized by fine grained soils with high water content. These latter
areas are highly susceptible to subsidence when surface disturbance alters
E. H. Follmann is presently associated with the Institute of Arctic
Biology of the University of Alaska.
the thermal regime. In these cases, the thawed ground becomes a morass in
which vehicle passage can be impossible and maintenance of structural sta-
bility of facilities becomes difficult.
The current major solution for eliminating or greatly reducing perma-
frost thaw is to use gravel as either pads for structures or as roadways.
Although these demands exist elsewhere, the thickness of gravel required
in permafrost areas is far greater than in nonpermafrost areas. The gravel
pad in permafrost areas replaces the insulative function of the vegetative
mat that was removed or compressed by the gravel fill. Since the insulative
quality of the vegetative mat is greater than that of an equivalent thick-
ness of gravel, a gravel pad must be considerably thicker to maintain an
equivalent thermal regime. Under these circumstances the most important
considerations for determining pad or road thickness are: climatic factors,
soil surface temperatures, permafrost temperatures, and subgrade soil proper-
ties (McPhail et al. 1975). The objective is to establish the freeze front
in or slightly below the fill (McPhail et al. 1975). Where this is accom-
plished, potential thaw problems can be greatly diminished.
Arctic and subarctic regions have been the focus of attention during
the past several decades because of the wealth of natural resources known
or thought to occur in these regions. The discovery of oil and gas on Naval
Petroleum Reserve No. 4 (now the National Petroleum Reserve-Alaska) in
the I940's, at Prudhoe Bay in 1968, and in northern Canada has stimulated
this interest and expanded it to include metallic minerals and coal. Expan-
sion of exploration activities can be expected to continue.
As resource development in remote arctic and subarctic areas becomes
more economically feasible the region's resources will be utilized to meet
society's energy and material needs. These future projects will require
increased quantities of gravel to facilitate construction and to provide
stable substrates for various permanent and temporary facilities. For ex-
ample, the gravel requirement for the Trans-Alaska Pipeline System was about
49 mill ion cubic meters (m ) (Michael Baker, Inc. 1977) . Sma I ler projects
requiring gravel, such as exploratory well drill pads and associated camps.
typically use up to 75,000 m . If, tiowever, airstrips and roads are associ-
ated with ttiese sites, quantities can increase to several hundred thousand
cubic meters. Based on experience constructing the Yukon River to Prudhoe
Bay Haul Road (Haul Road), approximately 31,000 m of gravel are required
per kilometer of road construction, and maintenance requirements average
about 700 m per kilometer (km) per year for about the first 5 years (Alson
personal communication). Alyeska Pipeline Service Company requested about
1.5 million m of gravel for maintenance of their project over a 5 year
period. The figures presented above for the large pipeline projects repre-
sent gravel needs from both upland and floodplain sites. About half of the
gravel used on the oil pipeline was from floodplains.
Alluvial deposits found in broad floodplains offer one of the prime
sources of gravel in northern areas. Individual material sites vary consider-
ably in size, as indicated by the range of those considered for study in
this project: 7,738 to 631,000 m of material removed. Several different
sites may be necessary to supply material meeting the required project
specifications because one site may not contain all types of material
needed. For example, not al I potential sites wi I I have material suitable for
topping. Also, since road and pipeline construction projects need materials
throughout their lengths, one site or a series of sites in one area will
not satisfy the demands of these projects. A haul distance of 6.5 km or
less has been estimated to be economically efficient for construction in
Alaska, and haul distances of 13 to 16 km or less are planned for mainten-
ance of the Trans-Alaska Pipeline System (Alson personal communication).
Therefore, material sites for these types of projects necessarily must be
located at regular intervals due to economic considerations.
To protect an environment from unacceptable disturbance, the elements
comprising the environment must be known, the various elements of the pro-
posed activity must be known, and the effects of the activity on the environ-
mental elements separately and as a whole must be known. Where this infor-
mation is available, guidelines to conduct the proposed activity with a
minimum of environmental perturbation can be developed. Where information on
one or more of these elements is lacking or is only partly understood, any
guidelines that are developed are based on estimates and assumptions whose
validity is dependent on the experience and predictive powers of those
developing the guidelines. The latter condition is the rule in most cases
where environmental impacts are concerned. Impacts from resource exploration
and development have not been studied as much as is necessary to make intel-
ligent decisions regarding environmental impacts. This lack of research is
particularly true in arctic and subarctic regions. The remoteness of the
area and the high cost of conducting research have not facilitated an ade-
quate description of the environmental elements. Studies of the environ-
mental effects of development have been similarly hindered.
Extensive literature review revealed that the specific impacts of
gravel removal had seldom been studied and, therefore, were poorly under-
stood. Description of impact had been attempted in only a few cases (Bull
and Scott 1974, Federal Water Pollution Control Administration 1968,
Forshage and Carter 1975, Sheridan 1967); and these studies dealt specif-
ically with only one aspect, e.g., fisheries. LaBelle (1973) reviewed gravel
and sand availability in the Barrow area of the National Petroleum Reserve-
Alaska and made recommendations on gravel extraction and evaluations of
potential environmental impact. Northern Engineering Services Company
Limited and Aquatic Environments Limited (1975) evaluated the material sites
associated with the Trans-Alaska Pipeline System with reference to aquatic
habitat. In addition, several reports identified problems associated with
gravel extraction as one of many sources of environmental perturbations that
could be expected from new and continued exploration and development in the
north (Bliss and Peterson 1973, Klein 1973, Weeden and Klein 1971, West
1976). None of these latter reports presented results of any material site
studi es.
There have been few studies on the environmental effects resulting
from construction of the Trans-Alaska Pipeline System. The Joint State/
Federal Fish and Wildlife Advisory Team (JFWAT) prepared a report on surveil-
lance experience with gravel mining recommendations (Burger and Swenson
1977). The JFWAT also produced a series of reports dealing with experiences
on the pipeline, including environmental effects studies. However, the major
responsib i I i f-y of the majority of JFWAT staff was environmental surveillance
of construction, not research on environmental effects.
Weeden and Klein (1971:481) stated: "As with so many other problems
of tundra management, the design of criteria for mining operations in gravel
lags far behind present need because detailed knowledge of fish populations
— where they are, when they migrate, where they spawn, their vulnerability
to added silt loadings of river waters, etc. — is lacking". By early 1975,
the state of knowledge had not progressed or expanded greatly. This fact,
coupled with the dependence on gravel for arctic and subarctic construc-
tion, stimulated the U.S. Fish and Wildlife Service to initiate a project
to investigate the effects of gravel removal on floodplain systems. The
project objective was to provide a comprehensive information review and data
synthesis to form the basis for future mining of river and floodplain
gravels. The purpose of the project is to provide an information base that
will assist resource managers to formulate recommendations concerning oper-
ations that will minimize detrimental environmental effects of gravel re-
moval from arctic and subarctic streams.
PHILOSOPHY
Little is known about the natural changes which occur in riverine
systems in arctic and subarctic regions. Therefore, determining the effects
of resource exploitation in these regions is often difficult because of the
interplay of natural changes and man-induced disturbances. The basis for
this study was the assumption that gravel removal operations in a floodplain
cause change, the magnitude of change depending primarily on the floodplain
characteristics, the location of the site, and the method of gravel extrac-
tion. Since almost all riverine systems in arctic and subarctic regions have
evolved to the present through natural change and without man-induced dis-
turbances, all changes due to gravel removal identified in this study were
considered undesirable. To maintain a river system in its natural or near-
natural state was considered the essence of guidelines development and
provided the best conceptual base from which to minimize environmental
degradation. However, it is recognized that there may be situations where
resource managers may wish to exercise other options. Any site character-
istics or methods that facilitated rapid recovery to pred i sturbance con-
ditions were considered for implementation as guidelines.
The presupposition that all changes due to gravel removal are undesir-
able does not, by necessity, cause the data analyses and recommendations
to be impractical. It is a foregone conclusion that changes will occur
when gravel is removed from a floodplain. To note that changes from the
natural state were less at one site than another suggests that the former
site was operated more consistently with characteristics of the system
than the latter, thereby reducing the magnitude of change. The floodplain
and gravel removal characteristics at sites that produced these minor
changes formed the primary basis for development of constructive guidelines
to minimize change. Conversely, the floodplain and gravel removal character-
istics at sites with major changes supported development of guidelines
primarily of a precautionary nature.
The analyses in succeeding chapters treat the changes that were meas-
ured at individual study sites. There are sites, for example, where species
diversity increased as a result of site disturbance. In some contexts,
this increased diversity would be considered a beneficial effect of gravel
removal. However, in the context of this project, this effect initially was
evaluated equal to one which caused an equivalent decrease in species diver-
sity because it reflected a change from the naturally evolved condition.
This project treats al I changes consistently and objectively as a
change from the natural, and special interest perspectives are neither
recommended nor encouraged. However, it is recognized that a resource man-
ager in certain circumstances may be greatly influenced by the need to
consider a site from a multiple or optimal use standpoint. For example,
subsequent to gravel removal a deeply dug site might be considered as a
water source in areas where winter supplies of water are minimal. Several
study sites were deep pits that contained water throughout the year. For-
mation of a pit represents a major change from the natural situation and the
site will not revert back to a natural situation for many years, if at all.
In the context of this project, pits represent a major divergence from the
natural. However, when considered from the standpoint of multiple use or
habitat diversification, a resource manager may elect to recommend or ap-
prove a permit for this form of gravel removal. In these situations the
resource manager will be able to predict the results of such an operation by
review of the following sections in this report.
PROJECT DESCRIPTION
A 5-year gravel removal study was initiated in mid-1975 to evaluate
the effects of gravel removal from arctic and subarctic streams in Alaska.
The primary purpose of the project was to provide an information base that
will assist resource managers in formulating recommendations for minimizing
detrimental environmental effects of removing gravel from arctic and sub-
arctic streams. To achieve this the following objectives were met:
• A comprehensive literature review and synthesis was conducted to
evaluate known and conjectured effects of gravel removal and other
similar disturbances on floodplain environments.
• Physical, chemical, and biological characteristics of seven sites
inhabited by fish after gravel removal were evaluated in moderate
detail on a short-term basis.
• Physical, chemical, and biological characteristics of 18 sites that
reflected various removal methods, stream types, and times since
completion of operations were determined in gross detail and on a
short-term basis,
• Relationships between parameters related to gravel removal operations,
geomorphic characteristics of streams, water quality, and biota were
eva I uated.
The study of three sites prior to, during, and immediately after gravel
removal was an original project objective that was eliminated due to a lack
of suitable sites meeting project schedules.
A thorough and broad-spectrum evaluation of the impacts gravel removal
can have in floodplains requires assessment from a number of disciplines.
To look at only one element could lead to conclusions and recommendations
that might cause major changes to a riverine system on a long-term basis.
Therefore, the approach taken in this study included analyses in the follow-
ing six d i sc i p I i nes :
River Hydrology and Hydraulics
Aquat i c Biol ogy
Terrestrial Ecology
Water Qua I i ty
Aesthet i cs
Geotechnical Engineering
This approach not only allowed analysis by individual discipline, but per-
mitted consideration of the i nterdi sc i p I i ne trade-offs inherent in evalu-
ations of disturbances to natural environments. For example, gravel mining
techniques that would avoid effects on aquatic biota could require removal
of important floodplain habitat used by terrestrial fauna or be impractical
from geotechnical considerations.
These disciplines were selected for the study because they were be-
lieved to cover the various impacts that were known or surmized to be associ-
ated with gravel removal. Due to a paucity of background information, it
was not possible to be assured that al I significant impacts were addressed
by these disciplines.
Although the main purpose of this gravel removal study was to provide
an information base for recommendations to be made by resource managers,
another important contribution is to provide a base for subsequent long-
term studies. For example, a problem needing extensive study is the effect
of removing gravel from many sites in one river system, as occurs along
highways and pipelines when they parallel floodplains for routing or geo-
technical reasons. This problem is not treated in the present study and,
in fact, was consciously avoided when sites were selected.
REFERENCES
Bliss, L. C, and E. B. Peterson. 1973. The ecological impact of northern
petroleum development. Fifth International Congress. Arctic Oil and
Gas: Problems and Possibilities. Le Havre. 26 pp.
Bui I, B., and K. M. Scott. 1974. Impact of mining gravel from urban stream
beds in the southwestern United States. Geology 2(4) : I 7 I- I 74.
Burger, C. , and L. Swenson. 1977. Environmental Surveillance of Gravel Re-
moval on the Trans-Alaska Pipeline System with Recommendations for
Future Gravel Mining. Joint State/Federal Fish and Wildlife Adivsory
Team Special Report No. 13. Anchorage, Alaska. 35 pp.
Federal Water Pollution Control Administration. 1968. Sand and Gravel
Waste Evaluation Study, South Platte River Basin, Colorado.
Forschage, A., and N. E. Carter. 1973. Effects of Gravel Dredging on the
Brazos River. Texas Parks and Wildlife Department, Inland Fisheries
Research .
Klein, D. R. 1973. The impact of oil development in the northern environ-
ment. Proceedings I n terpetro I eum Congress 3:109-121. Rome, Italy.
LaBelle, J. C. 1973. Fill Materials and Aggregate Near Barrow Naval Petro-
leum Reserve No. 4, Alaska. The Arctic Institute of North America
for the Office of Naval Petroleum and Oil Shale Reserves. Washington,
D. C. 146 pp.
McPhail, J. F., W. B. McMullen, and A. W. Murfitt. 1975. Design and con-
struction of roads on muskeg in arctic and sub-arctic regions. Six-
teenth Annual Muskeg Research Conference. Montreal, Quebec, Canada.
51 pp.
Michael Baker, Inc. 1977. Accounting of sale/free use permit materials.
Prepared for Alyeska Pipeline Service Company. Anchorage, Alaska.
Northern Engineering Services Company, Ltd. and Aquatic Environments, Ltd.
1975. Reconnaissance of the Alyeska Pipeline-Material Source Borrow
Methods and an Evaluation of These Methods with Respect to Aquatic
Habitats. Canadian Arctic Gas Study, Ltd. Calgary, Alberta, Canada.
Sheridan, W. L. 1967. Effects of Gravel Removal on a Salmon Spawning
Stream. U. S. Department of Agriculture, Forest Service. 26 pp.
Weeden, R. B. , and D. R. Klein. 1971. Wildlife and oil: a survey of cri-
tical issues in Alaska. The Polar Record 1 5(9) :479-494.
West, G. C. 1976. Environmental problems associated with arctic develop-
ment especially in Alaska. Environ. Conserv, 5 ( 3 ) :2 I 8-224.
APPROACH AND METHODOLOGY
E. H. Follmann
SITE SELECTION
The site selection process began in July 1975 and initial work in-
volved contacting various agencies and groups to locate potential study
sites. Among those contacted, the main sources of information were the
Bureau of Land Management, the Alaska Pipeline Office, the Alaska Division
of Lands, and the State Pipeline Coordinator's Office. In addition, the
Alaska Department of Highways (now Alaska Department of Transportation and
Public Facilities) provided a considerable amount of information.
A total of 575 potential sites were identified and subdivided into
three areas north of Latitude 66 — the North Slope, the Yukon River Basin,
and the Seward Peninsula — to obtain representative sites throughout arctic
and subarctic Alaska. Later in the project the Yukon River Basin sites
were separated into Northern Interior and Southern Interior sites. Following
identification of these sites, field reconnaissance was initiated to assess
the suitability of the sites for the study and to characterize those sites
considered potential candidates for the study. Sixty-four sites remained
as candidates following field reconnaissance.
To augment the drainage and material site descriptions developed in
the field for the 64 sites, additional information on gravel removal activi-
ties and watershed characteristics was obtained from various agencies.
E. H. Follmann is presently associated with the Institute of Arctic
Biology of the University of Alaska.
I I
topographic maps, and other data sources. Based on more complete site des-
criptions, preliminary variables were established with which to compare and
se I ect s i tes.
Site comparisons were restricted to sites within the same region to
insure adequate representation of the North Slope, the Northern Interior,
Southern Interior, and the Seward Peninsula. Six sites were selected to
represent the Seward Peninsula, eight for the North Slope, six for the
Northern Interior, and five for the Southern Interior (Figure I). The sites
were categorized by the presence or absence of fish on the basis of field
observation and reliable background information. The sites that were known
to contain fish after gravel removal were compared to determine which should
receive additional study.
All sites were previously mined. As stated earlier, sites could not be
identified which would allow studies (within project schedules) before,
during, and after gravel removal operations. All sites were named in ac-
cordance with the U.S. Board of Geographic Names. However, two sites oc-
curred on unnamed streams and were assigned project names of Skeetercake
Creek (unnamed tributary to the Too I i k River) and Aufeis Creek (unnamed
tributary to the Kuparuk River). When two study sites occurred on the same
river, they were designated upstream and downstream respective to their
locat i ons.
Major Variable Matrix
Following site selection the preliminary variables used to compare
sites were reviewed to determine which should be considered major variables.
Initial ly, nine major variables identified as either site characteristics or
mining characteristics were selected to describe each of the 25 sites
(Woodward-Clyde Consultants 1976). These parameters were chosen because
they were thought to be important from the standpoint of assessing gravel
removal effects, they best described the sites, and they allowed selection
of sites which exhibited the greatest variety of variables. The variety was
especially important because it insured that sites were different, thus
12
NORTHERN INTERIOR
SOUTHERN INTERIOR
Figure 1. Location of the 25 gravel removal study sites in Alaska
13
permitting assessment of the effects of various gravel removal procedures on
sites with different physical and biological characteristics.
The major variables were again reviewed following the field inves-
tigation, when detailed site characteristics were available to determine
which were still suitable for comparing the 25 material sites. The seven
variables selected for the final Major Variables Matrix included:
• Drainage basin size,
• Channe I > width,
• Channel configuration,
• Channel slope,
• Stream origin,
• Type of gravel removal, and
• Location of gravel removal.
These parameters were categorized as either Physical Site Characteristics
or Gravel Removal Area Characteristics. Each of the sites was characterized
according to these variables (Table I). Definitions of these variables
are included in the Glossary.
Physical Site Characteristics. Drainage basin size and channel width
are significant because the impact of gravel removal could differ depending
on the amount of disturbance in proportion to the size of stream and flood-
plain. Also, systems having greater discharge and bed load movement could
be expected to regenerate a material site more rapidly than a system with
sma I ler discharge and less bed load movement assuming the amount of mining
disturbance is proportionate in the two streams. Categories used were small,
medium, and large based on the drainage area above the site and sma I I,
medium, and large based on the channel top width within the study reach
at mean annual flow. Although from a hydrological standpoint categorization
only according to drainage basin area would have been sufficient, we con-
sidered it important to include channel width because width is a tangible
measurement that can be observed at a site location.
14
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Channel configurations vary from straight mountain streams to braided
rivers. Factors associated with various types of streams such as bed load
movement, bank erosion, and water fluctuation were considered important.
Configurations included in this study were braided, split, meandering,
sinuous, and straight.
Channel slope, along with other variables, is a major factor governing
water velocity, discharge, and sediment transport. Therefore, streams with
s I opes categor i zed as mild, moderate, and steep were included.
Stream origin was considered because it governs aspects of stream
hydrology. Stream origin also influences the amount of bed load material
available for transport, thereby indicating the regenerative capacity of
a stream, and the availability of suspended sediment that could deposit
in a gravel removal area. Categories used were mountain, foothill, coastal
plain, and g I ac i a I .
Other factors such as stream bed material, bank vegetation, and water-
shed characteristics are important, but were not considered as major vari-
ables. To a large extent these factors are accounted for by the major vari-
ables and the physiographic provinces occurring within the regions.
Gravel Removal Area Characteristics. Two major types of gravel removal
operations used in floodplain areas are pits and scrapes, distinguished
primarily by depth of excavation and permanent inundation by water after
site closure. During site visits it was apparent that pits were either
connected or not connected to an active stream channel. Because magnitude
of change to a system could be greatly influenced by this factor, pits
were characterized as either connected or not connected.
Location of gravel removal sites within a floodplain influences the
degree of impact and the regenerative potential of a site. Therefore, dis-
tinctions were made between sites located in a channel, adjoining a channel,
and separated from a channel.
16
To determine the impact of gravel removal over time and the regenera-
tive capacity of various types of streams, it was necessary to observe
sites that were active during different years. Information was not available
for sites associated with construction activity early in this century,
but was for sites ranging back to the late I950's.
Specific descriptions of the regional characteristics, physical site
characteristics, and characteristics of the gravel removal operation at
the 25 study sites occur in a subsequent section.
DATA REVIEW
Available information regarding the effects of gravel removal and
other similar disturbances in floodplains was reviewed. Information was
solicited from many Federal and most State agencies, from various Canadian
groups, and from literature sources. Due to a minimum of information on
the effects of gravel removal, particularly in arctic and subarctic re-
gions, some of the processes involved had to be discussed from a theoretical
standpoi nt .
The results of this work were included in a Preliminary Report prepared
in 1976 (Woodward-Clyde Consultants 1976). This report should be referred to
if a review of available literature is desired.
FIELD STUDY OF SELECTED MATERIAL SITES
Preparation for the field program began in Spring 1976 and the last
site was visited in March 1979. Site visits were split over three summers
with 7 sites studied in 1976, 10 sites in 1977, and 8 sites in 1978. In
addition, seven sites were visited during the winters of 1977-1978 and
1978-1979 to determine the presence or absence of fish, to record water
quality parameters, and to describe the occurrence of icing conditions.
During the 1976 field program field teams representing River Hydrology
and Hydraulics, Aquatic Biology, and Terrestrial Ecology worked each site
17
simultaneously. The Aquatic Biology team also collected water quality data.
Simultaneous effort of field teams was considered advantageous during the
first field season to insure coordination of work where necessary. In ad-
dition, simultaneous work permitted on-site discussion of methodology
changes by all disciplines, thus further insuring coordination and co-
operation. During subsequent field seasons, some of the sites were visited
by individual field teams, but all teams visited the sites during the same
summer. These individual visits allowed each team to visit sites during peak
events for parameters associated with their discipline. Data and sample
collection areas were flagged to facilitate collection of data at the same
sites during subsequent visits by either the same or different teams. In
addition, the hydrology and hydraulics and terrestrial teams placed semi-
permanent posts at each site from which to initiate surveys for future
studies.
The following section includes a review of the field and laboratory
programs conducted during the field effort. Programs are described only
for River Hydrology and Hydraulics, Water Quality, Aquatic Biology, and
Terrestrial Ecology because these were the only disciplines for which data
were specifically collected. Geotechnical Engineering and Aesthetics relied
completely on field information collected by other groups.
River Hydrology and Hydraulics
Introduction. Emphasis of the field program was on describing local
fluvial geomorphic processes, obtaining evidence of past flood histories,
measuring river hydraulic parameters, investigating sediment transport
properties of the channels, describing river processes, and investigating
specific effects of gravel removal on these factors. Photographs were taken
for documentation of significant features. Hydraulic and hydrological data
collection were coordinated with the water quality, aquatic biology, and
terrestrial ecology studies.
Hydrological and geomorpho I og i ca I literature pertaining to each site
and its drainage basin, e.g., hydrological records, surficial geology.
18
and aerial photographic interpretations were also used in the analysis
of each site.
Geology and Geomorpho I ogy . Using topographic maps, stereo aerial photo-
graphy, and surficial geology maps, a brief analysis of each drainage basin
was made to evaluate the geomorpho I ogy of the river val ley, the river ter-
races, and the present and past regime of the river. The morphological fea-
tures pertaining to the general area around the material site were verified
in the field.
Hydrology. The U.S. Geological Survey Water Resources Records were
reviewed for flow measurements within a study site's drainage basin. Where
flow measurements were representative, various key discharges with the
respective stages were estimated and documented. In the field, evidences
of floods were investigated. Where sufficient data could be obtained at
the study site or near vicinity, a stage-discharge relationship and flood
frequency analysis were included in the data package. For the rivers that
had no past flow records, the hydrology was synthesized using a regional
flow analysis (Lamke 1979).
Hydrau I i cs. Hydraulic parameters for each river channel and f I oodp I a i n
were measured in the field. At each study site cross sections were surveyed
upstream from, within, and downstream from the area of gravel removal (in
conjunction with the aquatic ecology program) to measure the following
hydraulic parameters: width, depth, and area. All cross section locations
were documented and elevations referenced to temporary benchmarks. The
longitudinal slope of the water surface and, where possible, the bed were
surveyed. All surveys used standard surveying techniques. The discharge at
the time of the survey was measured using standard techniques (Buchanan and
Somers 1969).
Materials and Sediment. Representative samples of the river's flood-
plain surface material were obtained upstream and downstream from the gravel
removal area using the photographic-grid method (Kellerhals 1971). These
were considered to be representative of the channel bed material. The size
19
distribution was determined by the f requency-by-number method. In addition,
the underlying material was measured using hydraulic sieves and the size
distribution determined by percentage-by-weight.
The river bank materials were described at cross section locations
based on a subjective evaluation and photographed for documentation. Ma-
terial gradation samples of river bank materials were not obtained.
Channel Processes. The fluvial morphology at each site was assessed
using comparative aerial photography. In the field, fluvial morphological
features were verified and documented in more detail, e.g., gravel bar
types, bed formations, scour holes, and sediment deposition. Degradation
and/or aggradation upstream from, and downstream from the gravel removal
site were investigated.
River Ice. In the field, evidences of ice processes (breakup jams,
ice scour, gouging, and aufeis) were documented to help evaluate the role
of ice on the river morphology.
Water Qua I i ty
Water quality parameters measured were temperature ( C), dissolved
2
oxygen (ppm), conductivity (m i cromhos/cm ), turbidity (JTU), suspended
solids (mg/S,), oxidation-reduction potential (MV), and pH (Table 2). Water
quality measurements were taken at the aquatic macro i nvertebrate sample
sites. Usually the measurements were taken along a transect across the river
or pit with the number of replicates within a site adjusted to the size of
the water body. The measurements were normal ly within 30 cm of the water
surface, although depth profiles were taken in pits.
Aquat i c Biol ogy
Introduction. Field emphasis was placed on aquatic Invertebrates,
changes in fish distribution in relation to the gravel mined area, and
potential fish spawning and rearing habitat during the ice-free period.
20
Table 2. Methods Used for Measuring Water Quality Parameters with the
Number of Replicates Taken per Study Area
Parameter
Method of
determi nat i on
Rep I icates
per study
area
Dissolved oxygen
Temperature
Conduct i V i t y
Tur b i d i ty
Suspended so I ids
Oxidation-reduction
potent i a I
pH
YSI Model 57 DO meter
YSI Model 57 DO meter
Hach Model 2510 conductivity meter
Hach Model 2I00A turbidimeter
Millipore filter procedure
(5 pm f i I ter )
Delta Scientific I 2 I 2-P2 ORP
meter
Delta Scientific 1212 pH meter
Hach pH kit
3-15
3-15
3-15
2-11
I - 3
2-5
I - 5
Additional visits were conducted to specific sites if potential over-
wintering habitat or suspected spawning areas were present within the mined
area.
Study sites were categorized into two groups. Eighteen sites were
visited once during the open water season. Seven sites with known fish
utilization in the mined area were subject to additional field study. These
seven sites were visited on three separate occasions during open water
conditions of I calendar year. In addition, seven pit sites where winter
utilization by fish was suspected were visited to document overwintering.
The 18 sites subject to a less intensive field program were visited
only once.
Selection of Sample Areas. Three sample areas were selected at all
sites: upstream, within the mined area, and downstream. Selection of up-
stream and downstream sample areas was based on similarity to the aquatic
and terrestrial characteristics exhibited in the mined area prior to gravel
removal. Selection of sample areas was made so that substrate, depth, width,
velocity, and poohriffle ratio were similar at the upstream and downstream
I ocat i ons.
The upstream area was typical ly located at least 400 m above the mined
area and the downstream area was between 400 and 800 m below the mined
area. Selection of the 400 m criteria was based on the assumption that
the hydrological effect of gravel removal would be minimal that far up-
stream. Selection of a downstream area between 400 and 800 m below the
mined area was based on the probability that changes occurred in this area
either during or immediately after gravel removal.
At sites with more than one mined area, additional sample areas were
selected to assess effects. Similar selection criteria were used.
Selection of Sample Gear. Fish and aquatic macrolnver tebrate sampling
gear were selected relative to the types of habitat present. Features such
22
as width, depth, stream velocity, shoreline configuration, stream bank
vegetation, obstructions, channel substrate, and presence of pits affected
the gear selection process. Sample gear used at each study site is listed
i n Tab I e 3.
Sample Program. Information recorded in the field included stream
name, sample location and description, description of the disturbed area,
and the date, time, and existing weather conditions. Visual surveys were
conducted within sampling areas to describe habitat and to record the pres-
ence of fish.
Sample Collection, Disposition, and Analysis. A variety of seines with
square mesh (3.2 mm), 6 to 10 m long and 1.8 m deep, were used. Seines
were extended across the stream from bank to bank and pulled downstream
in narrow streams. In larger streams and pits the quarter-haul technique
was used. Experimental, multifilament gill nets 15 x 1.8 m, with panels of
12.7, 25.4, 38.1, 50.8, and 76.2 mm square mesh, were anchor-set in pits,
and, in one case, in the deep, slow-moving section of a large river.
A backpack shocker, one of the least selective of all active fishing
methods, was used in appropriate watercourses. Stream width permitting,
a preselected length of stream was blocked with seines and the enclosed
area shocked repeatedly until fish were no longer captured or observed.
The area of the shocked section was usual ly measured to al low for density
est ima t i on .
Winnow traps selective for juvenile and small adult fishes were used
to sample aquatic habitats. Traps were located in pools, riffles, and pits
and were baited with salmon eggs. Traps were usually fished from 12 to
24 hours.
A dip net was used at one site to capture juvenile fishes for identi-
fication. Visual surveys were made at each site to record distribution
and unusual events or critical habitats, such as spawning areas.
23
Table 5. Aquatic Biology Sampling Methods Used at Each Study Site
Macro invertebr ate
sampling gear ^
Surber Ponar Minnow Gi I I Electro- Hook & Set
sampler g''ab trap Seine net shocker line line
Study site
F i sh samp I i ng gear
Seward Peninsula
Gold Run Creek
S i nuk R i ver
Washington Creek
Oregon Creek
Penny River
Nome River
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
North Slope
Ugnuravik River
Aufeis Creek
Kuparuk River
Skeetercake Creek
Sagavan irk tok River
Ivishak River
Shaviovik River
Kav i k R i ver
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Nor ther n I nter i or
Dietrich River-US
Dietrich River-DS
M.F. Koyukuk River-US
M.F. Koyukuk River-DS
Jim R i ver
Prospect Creek
Southern I nter i or
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
W.F. Tolovana River
McManus Creek
Tanana River-DS
Tanana River-US
Phelan Creek
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
24
Captured fishes were identified, measured (fork length), weighed,
and released except when preserved for reference. Data collected were used
to determine species composition, size distribution, and relative abundance;
estimates of density were made. These evaluations were compared within
and between gravel removal sites.
Macro! nvertebrates. A 30-cm square Surber sampler was used to collect
macroi nvertebrates in riffle areas. Sampling areas were stratified by depth,
bottom type, current velocity, and other variables that may have been corre-
lated with benthic distribution. At most study areas three sampling sites
were selected and five replicate samples were collected at each sampling
site. Two sampling sites were selected in a few cases where there were
multiple mined areas or where the river was not directly affected by gravel
removal, e.g., a pit site away from the stream channel, with five replicates
taken per site.
A Ponar grab was used to collect macro i nvertebrates in pits. Single
grabs were taken at several stations spaced to cover the main depth regions
within the pits. Ponar grab samples were cleaned, separated (the slurry
passed through a U.S. Standard No. 30 sieve), and placed in labeled con-
t ai ners.
Samples co I I ected wi th the Surber sampler were placed directly into
labeled containers. Al I sample containers were f i I led with 70 percent al-
cohol to preserve specimens for later examination. Samples were picked
and sorted in the laboratory. Organisms were sorted into major categories
and placed into labeled vials containing 70 percent alcohol. Identification
was to the lowest practical taxonomic level.
Data from quantitative samples were used to obtain total and individual
taxon density. Data on standing crop and number of taxa were evaluated;
comparisons were made within and between sample sites.
Pit Sampling Program. Four pits were visited during March 1978 to
assess the potential for fish entrapment and overwintering. During the
25
following summer these pits, plus three additional ones, were visited to
assess if fish were present. The pits were then revisited during the 1978-79
winter to assess if fish remained in the pit after freezeup or moved into
the river. If fish remained in the pit, subsequent visits were made to
determine if fish could survive the winter. Sampling was conducted with
a variety of gear types including minnow traps, set lines, gill nets, hook
and line, and observation. In addition, an underwater television system
was used for surveillance under the ice at two pits. Dissolved oxygen and
temperature were measured when water was present. Ice thickness, presence or
absence of flowing or open water, or both, and formation of aufeis by over-
flow were recorded.
Terrestrial Ecology
Introduction. The terrestrial field program identified habitats af-
fected by gravel removal operations and assessed the impact of habitat
modification on associated wildlife. Qualitative and quantitative surveys
were conducted during a 3-day field effort to characterize the plant com-
munities and serai stages present on disturbed and undisturbed areas. Wild-
life utilization of these habitats also was evaluated. The undisturbed
sites encompassed serai stages likely to develop with time on the disturbed
site, and were believed to be most representative of the disturbed areas
prior to gravel removal.
The program was expanded to 5 days at one representative study site
(regional representative site) in each of five geographical areas: Arctic
Coastal Plain (North Slope), Arctic Foothills (North Slope), Seward Penin-
sula, Northern Interior, and Southern Interior. The increased time at these
study sites allowed for additional sampling efforts using the same sampling
procedures.
Soils. Soil sampling was conducted within each habitat on disturbed
and undisturbed sites to evaluate the growing conditions and the potential
for revegetat i on. Within each habitat or definable soil unit, the character
of the upper horizon, depth of organic layer, surface drainage, and domi-
26
nant vegetation were recorded. Approximately 15 subsamples were collected
with a soil auger-tube sampler from the ground-cover rooting zone (approxi-
mately the upper 20 cm). These subsamples were combined to form one compos-
ite sample for each soil unit. Composite samples were air dried and ana-
lyzed for pH, percent organic matter, and percent nitrogen, phosphorus,
and potassium. A particle size distribution analysis was conducted to deter-
mine the percent sand, silt, and clay in the composite sample.
Vegetation. Vegetation surveys delineated the major cover types with-
in the study area. Within each habitat, the serai stage of development
was noted and the plant species were recorded.
Qualitative site descriptions were augmented by limited use of quan-
titative sampling methods that employed a systematic, nested plot design
(James 1978). Strand or patch habitats required "spot" location of nested
plots or qualitative description only.
Description of the overstory vegetation included the following param-
eters: dominant and subordinate tree species, average height and DBH (diam-
eter at breast height) of the stand and stand components, and representative
ages by species and height class. A limited number of circular plots (0.04
ha) were used to quantitatively sample each habitat. Forester's calipers
or a diameter tape, or both, were used to determine tree DBH; tree height
was estimated and an increment borer or cross-sectioning method was employed
to determine the age of woody plants. Increment cores and cross sections
were returned to the laboratory for staining and age determination when
necessary.
Shrub growth within each habitat was described by identifying species
composition and relative density, average height by species, and representa-
tive ages by species and height class. Stem and clump density counts were
conducted on a limited number of systematically located, 0.004-ha circular
plots. Selected shrubs were aged by cross-sectioning above the root collar.
Evidence of herbivore browsing was noted.
27
Ground cover sampling identified species composition within each habi-
tat and provided an estimate of percent surface coverage for each taxon.
Percent surface coverage was visually estimated in systematically located,
0.0004-ha plots. Percent surface coverage was estimated as follows: if
only one plant of a given taxon was present and its coverage was very
sparse, it was rated at I percent coverage; if more than one plant of a
given taxon was present, but its coverage was less than 10 percent of the
plot's surface area it was rated at 5 percent coverage; the percent coverage
of al I other taxa was estimated in increments of 10.
Wildlife. Evidence of wildlife use of disturbed and undisturbed areas
was recorded at each site. Direct observations and evidence of use (tracks,
trails, nests, dens, runways, food caches, and scats) were keyed to their
presence in specific serai stages. Historical use of a cover type was noted
(i.e., hedged growth form of preferred browse species) and serai stages
critical to certain life history stages of wildlife were inspected. The
disturbed area was examined for the presence of special attractants or deter-
rents to wildlife use of the site.
An avian census was conducted in disturbed and undisturbed habitats
at al I study sites; attempts were made to visit the five intensive study
sites during the peak avian activity period. The census in homogeneous
habitats employed a Modified Strip Plot technique for three consecutive morn-
ings (five mornings at the intensive sites) to obtain data on the species
present and habitat utilized. Sma II, isolated habitatswere qualitatively
surveyed to ascertain avian species occurrence. Waterfowl, shorebirds, and
game birds were inventoried by total counts when areas of concentration were
clearly visible.
Sma I I mammals (shrews, voles, and lemmings) were inventoried at al I
sites in disturbed and undisturbed habitats using a trap and removal tech-
nique. A "line" or "spot" trapping configuration was used in all cover
types. Trapping was conducted for two nights at nonintensive sites and four
nights at regional representative sites with the traps checked, baited,
and reset each day. The species, sex, age, and weight of captured specimens
were recorded to assess occurrence and characteristics by habitat.
28
Collection of terrestrial invertebrates was conducted at all fish
intensive sites and at the regional representative sites. Collections were
made adjacent to the watercourse at the disturbed site and near the upstream
aquatic sampling station to assess the availability of potential food
sources for the aquatic environment. Sweep nets were used to collect inverte-
brates. Specimens were preserved in 40 percent alcohol and returned to
the laboratory for identification.
DATA BASE
The data base, the third end product of the gravel removal study,
(the Technical Report and Guidelines Manual are the first two end products)
consists essentially of all information collected during site selection and
field data collection. Information for each of the 25 study sites includes:
• Case history information including mining plans and permits, if avail-
able;
• Biological, hydro I ogica I , and water quality field data;
• Geotechnical evaluations;
• Tabulation of data summations;
• Computer printouts for aquatic ecology and hydrology and hydraulics;
• Draft site description reports;
• Site photographs, including both ground and aerial;
• Topographic maps showing site location; and
• Depiction of actual data collection areas within each site.
29
The information is in a form to allow any professional to evaluate where
the data was collected, what data was collected, and the general conclusions
of the original investigator.
This data base is on file with the U. S. Fish and Wildlife Service.
It will not be distributed routinely with the Technical Report and Guide-
lines Manual. Due to the mass of information available, a specific need
will have to be identified before the data relevant to that need can be
provi ded.
TECHNICAL REPORT
Analyses of field data, beyond the immediate data reduction after
site visits, began in winter 1977-78. This initial effort prepared descrip-
tions of each of the study sites visited in previous summers and analyzed
data specific to each site. Brief summaries of essential information rele-
vant to each of the 25 material sites studied during this project are in-
cluded in the subsequent chapter. These are included to orient the reader
for the discussions that follow in the individual discipline chapters.
Data syntheses for all sites did not begin until after the 1978 field
season. Analyses of combined site data are contained totally in this report.
Each of the six disciplines included in the project, (River Hydrology and
Hydraulics, Aquatic Biology, Terrestrial Ecology, Water Quality, Aesthetics,
and Geotechnical Engineering), is discussed in separate chapters. These
chapters include some integration with other disciplines. For example,
Aquatic Biology is dependent, for some of its data interpretation, on the
Water Quality parameters measured, and on the physical changes that are
described in the River Hydrology and Hydraulics section.
An interdisciplinary overview of the effects of gravel removal follows
the discipline chapters. This chapter reviews the analyses of the six disci-
plines in terms of the similarities and differences that are evident. An
important aspect of this chapter is discussion of the tradeoffs and com-
parisons between disciplines that must occur with respect to the siting.
30
operation, and closing of material sites. Where possible, the similarities
in approach of the various disciplines to minimize disturbance from gravel
removal are emphasized because these conditions maximize protection of
floodplain environments.
GUIDELINES MANUAL
The Guidelines Manual (printed separately) is based on the evaluations
and recommendations contained in the Technical Report, on the preliminary
guidelines developed in an earlier phase of this project (Woodward-Clyde
Consultants 1976), and on stipulations and recommendations used by certain
resource agencies when reviewing material site applications and projects.
The guidelines are intended to provide guidance to the persons respon-
sible for writing material site permits and for planning resource or indus-
trial development in localized areas. The guidelines also are helpful to
potential applicants for material site permits because they will help in
planning a project characterized by minimal environmental perturbations.
The guidelines are not designed as stipulations to be attached to
each permit granted. If used in this manner contradictions in siting, opera-
tional, and rehabilitation procedures could occur, thus negating the value
of the guidelines. It is intended that the guidelines user evaluate the
proposed project within the context of the guidelines, and the proposed
area for the material site, to insure that it will develop in an environmen-
tally acceptable manner.
The guidelines were developed for use by personnel with some background
in an environmental science. Ease of use was considered necessary because,
at least on large projects such as pipelines and roads, permit agencies
can be inundated with applications requiring quick consideration. A set of
guidelines that are cumbersome and inefficient to use, under these circum-
stances, could foster disregard of the guidelines or their misuse e.g.,
attaching the guidelines as stipulations to a permit.
31
The guidelines, as mentioned, were developed with the assumption that
the potential user has some experience with environmental problems and
issues and, thus, appreciates the potential complexities associated with
a material removal project. It is strongly recommended that the user read
the Technical Report and understand why and how the guidelines were devel-
oped. A comprehension of the total project is considered necessary for
intelligent, efficient, and expeditious use of the guidelines. Without this
understanding, the guidelines could be viewed out of context and used inap-
propr i ate I y .
32
REFERENCES
Buchanan, T, J., and Somers, W. P. 1969. Discharge Measurements at Gaging
Stations. Book 3, Chapter A8. Techniques of Water-Resources Investi-
gations of the U.S. Geological Survey. 65 pp.
James, F. C. 1978. On understanding quantitative surveys of vegetation.
Am. Birds 52 ( I ) : 18-21 .
Kellerhals, R. 1971. Sampling procedures for coarse fluvial sediments.
J. Hydraulics Div. ASCE 97 ( HY8 ) : I I 65- I 180.
Lamke, R. D. 1979. Flood Characteristics of Alaskan Streams. U.S. Geolog-
ical Survey Water Resources Investigations 78-129. Anchorage, Alaska
61 pp.
Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska. U. S. Fish
and Wildlife Service. FWS/OBS 76/21. Wash. D. C. 127 pp.
33
DESCRIPTION OF STUDY RIVERS
L. L. Moulton, Ed.
As previously mentioned, 25 sites were selected for study. These sites
occurred in four geographical regions of Alaska and include a wide variety
of Physical Site Characteristics and Gravel Removal Area Characteristics
(Table I). Site locations are shown on Figure I. Table 4 summarizes dis-
turbed area size, volume of gravel removal, and period of activity at each
site.
SEWARD PENINSULA
General Description of Region
The region of Seward Peninsula containing the six study sites is in
the foothills of the Kigluaik Mountains, characterized by broad rounded
hills with elevations of 250 to 700 m (Figure 2). The surficial geology at
Sinuk River, Washington Creek, and Nome River is dominated by remnants of
highly modified moraines and associated drift resulting from Pleistocene
glaciation. Gold Run Creek however, is just outside the northern edge of
glacial influence and the surficial geology is fine-grained alluvial and
colluvial deposits with rare bedrock exposures. At Oregon Creek and Penny
River the surficial geology is characterized by coarse and f i ned-grai ned
deposits of alluvium and co I I uv i um associated with moderate to steep-sloped
mountains and hills. Bedrock exposures are common on the upper slopes and
crests. The region is general ly underlain with permafrost of variable thick-
ness. Normal temperatures range from 3 to 13 C in the summer and -23 to
-13 C in the winter. The annual precipitation of the region is about 30-40
cm, including approximately 130 cm as snow.
35
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56
Figure 2. Typical Seward Peninsula terrain.
Vegetation within ttie floodplains consists of dense mature willow
thickets interspersed with less advanced mixed woody-herbaceous communities.
The val ley wa I Is contain occasional wi I low and alder thickets in the moist
ravines and pockets, and shrub-tussock tundra on the slopes. The river
systems contain both anadromous and resident fish species. Typical anad-
romous species include Arctic char, pink, chum, coho, and sockeye salmon and
various whitefish species. Typical resident species include Arctic grayling,
resident Arctic char, northern pike, Alaska blackfish, and slimy sculpin.
Description of Study Rivers - Location and Gravel Removal Area
Character i st i cs
Gold Run Creek. Gold Run Creek is a small, sinuous river which origi-
nates in the foothills of the Kigluaik Mountains at an elevation of 427 m
and flows through rolling hills for 23 km to its confluence with the Blue-
stone River. The study site is approximately 7 km from the mouth at an
37
elevation of 100 m. Gravel was removed from this site for construction of
the Nome-Tel I er Highway. Gravel removal occurred by shal low scraping over
approximately 3.5 ha between 1963 and 1965 with 7,738 m of material ex-
tracted. Scraping occurred in the active channel, on mid-channel and lateral
bars, and on a vegetated island between the active channel and a high-water
channel. Approximately I ha of riparian willow thickets and an accompanying
0.5-m layer of overburden were removed prior to gravel removal. This organic
overburden was placed in a stockpile on the edge of the scraped area along
the right (northern) f I oodp I a i n bank downstream from the highway bridge. An
additional overburden pile, composed primarily of sand, was located at the
downstream limit of the scraped area. Both stockpiles still remained during
the site visit. A 50-m long gravel access road also was present leading from
the highway to the scraped area located upstream from the highway bridge.
The floodplain bank at the floodplain end of this access road was incised
and approximately I m high. Rehabilitative measures were not conducted
after completion of gravel mining activities.
S i nuk R i ver . The Sinuk River is a medium, split river which originates
in the Kigluaik Mountains at an elevation of 425 m. It flows through a
narrow, steep-wal led val ley before entering a broad val ley containing the
study reach. The lower section flows across a relatively flat coastal plain
for 26 km before discharging into Norton Sound. The study site is approxi-
mately 19 km from the mouth at an elevation of 30 m.
Between I960 and 1966, 174,221 m of gravel were extracted for high-
way construction by shallow scraping within the active floodplain and adjoin-
ing the active channel of the Sinuk River. Access to the floodplain was
gained via two short (about 30 m) gravel roads leading from the highway.
Scraping extended approximately 1,500 m upstream and downstream from the
Sinuk River bridge and encompassed 88 ha.
Material within the Sinuk River floodplain was described from highway
department analyses as stream-deposited sandy gravel with less than 25
percent greater than 50 mm in size (coarse gravel) and about 2 percent
exceeding 250 mm (boulders). Several (three or four) islands were removed
38
during the mining operation. These islands were heavily vegetated with
willow thickets averaging 1.2 m in height. These islands comprised approx-
imately 35 ha of the site. Stripping of 0.15 m of overburden was necessary
in these vegetated areas. In addition, approximately 150 m of incised flood-
plain bank and 1.2 to 1.6 ha of adjacent tundra were removed from the north-
east side of the floodplain to expose gravel deposits. Also, within the
active floodplain, debris and soil from vegetated islands were pushed into a
long narrow overburden pile (approximately 450 m in length) in the middle of
the material site to expose underlying gravel deposits. The water table was
encountered at about 0.75 m below vegetated sand bars with seasonal frost
present in the floodplain and permafrost encountered at depths of 0.9 to
2.4 m in adjacent terraces. It does not appear that this material site was
shaped, contoured, or rehabilitated in any way following gravel removal.
Various aspects of this site are shown in Figures 2 and II.
Washington Creek. Washington Creek is a small, sinuous creek which
originates in the foothills of the Kigluaik Mountains at an elevation of
about 265 m and flows through a wide, V-shaped val ley for about 15-km before
entering the Sinuk River. The study site is approximately 5 km from the
mouth at an elevation of about 105 m.
This study site consists of two gravel removal areas approximately
1,000 m apart on Washington Creek. Both areas were developed between I960
and 1963 during construction of the Nome-Teller Highway. The lower site
was still being used in 1978 to supply gravel for road maintenance.
Gravel at both sites was removed by scraping the Washington Creek
floodplain and the alluvial fan deposits formed near the confluences of
two unnamed tributaries of Washington Creek. A reported 8,000 m of ma-
terials were removed from I ha in the upstream site, while 41,000 m had
been removed from 2 ha in the downstream site.
Clearing of large amounts of overburden was required for the devel-
opment of both sites. Overburden was not removed from the material sites
but was collected into large mounds which were still present at the time
39
of our visit. Large stockpiles of clean gravel were also seen at both sites.
Efforts to rehabilitate the floodpla
of the channel were not observed dur
were constructed in the downstream m
main channel in its pre-mining locat
shown in Figures 12, 38, 39, 43, 53a
n or to maintain the natural character
ng the field study. Dikes, however,
ned area to maintain the course of the
on. Various aspects of this site are
53b, and 67.
Oregon Creek. Oregon Creek is a small, straight river which originates
in the foothills of the Kigluaik Mountains at an elevation of 380 m and
flows approximately 7 km through a V-shaped valley to a confluence with
Cripple River. The valley walls are steeply sloped over the upper half of
its length; the lower half is flanked by moderately sloped hills. The Crip-
ple River headwaters lie at an elevation of about 300 m and the river flows
in a broad V-shaped val ley for 40 km before discharging into Norton Sound.
The Oregon Creek confluence occurs 15 km downstream from the headwaters of
Cripple River at an elevation of 80 m.
The material site was developed by scraping gravel bars within and
adjoining the active channel near the Oregon Creek-Cripple River conflu-
ence. Scraping of angular gravel and cobbles was conducted west of the
Nome-Teller Highway in Oregon Creek from I960 to 1963 when 20,500 m of
material were removed from approximately 5.5 ha. Vegetation was removed from
4 ha at the downstream end of this site. Mounds of vegetated overburden
along the banks of the broadened channel and stockpiled gravel within the
active floodplain were observed during site inspection. Between June and
September 1965, 6,000 m of gravel were excavated from I ha in the Cripple
River immediately downstream from the highway bridge. Various aspects of
this site are shown in Figures 13, 40, 41, 53c, 64, and 74.
Penny River. The Penny River is a small, sinuous river which originates
in the foothills of the Kigluaik Mountains at an elevation of 230 m and
flows approximately 23 km before discharging into Norton Sound. In its
upper reaches, the Penny River flows in a narrow V-shaped valley. The valley
broadens downstream and the valley floor typically reaches widths of 350 m
40
between moderately sloping hills in the vicinity of the study reach. The
study reach is approximately 8 km upstream from the mouth at an elevation of
28 m.
The material site was developed by scraping within the active flood-
plain and excavation of a pit adjacent to the main channel of the river.
Material removed from the 15-ha site was primarily sand and gravel alluvium
with some colluvial debris along the southeast edge of the working limits.
Rock types were quartz mica schist, limestone, and quartz; rock fragments
were subangular to rounded with 3 to 10 percent greater than 50 mm in size
and less than I percent greater than 250 mm.
Clearing and stripping were necessary to remove the dense willow (that
covered approximately 12 ha) and an average 0.6 m of overburden. The water
table varied from 0.8 m to more than 1.5 m deep with no permafrost encounter-
ed up to a depth of 2.1 m. Scraping was conducted during 1960-63 when
3,646 m were removed and during August and September, 1965 when 47,054 m
were extracted. The 1965 operation yielded some select materials, indicating
that a processing plant probably operated within the site. A small 0.6-ha
pit was excavated in the southeast corner of the material site during the
1965 operation. This pit averaged I to 1.5 m in depth during the site visits
and was directly connected to the ma in channel. Sma II stockpileswere pres-
ent within the disturbed area during field inspection. The site was not
shaped, contoured, or rehabilitated in any way following gravel removal.
Thus, many shal low depressions, which are not sloped to drain toward the
river, collect standing water. In addition to the 0.6-ha pit, scraping
occurred to below the water table in several small isolated pockets, and
these areas were covered with standing water during site visits. Four or-
ganic overburden piles and the gravel access road remain on the site. Var-
ious aspects of this site are shown in Figures 33, 58, 61, 65, 66, and 85.
Nome River. The Nome River is a medium, sinuous river which originates
in the Kigluaik Mountains at an elevation of about 230 m and flows through
a broad val ley for about 57 km to its mouth at Norton Sound. The Nome River
drainage basin is long and narrow, with an average width of about 8 km. The
study site lies about 37 km from the mouth at an elevation of about 58 m.
41
This material site was developed by scraping 1.5 ha across the entire
floodplain width. Scraping apparently occurred in the active channel and on
adjacent mid-channel and lateral bars. Vegetative and overburden clearing
was not necessary because the site was sparsely vegetated prior to gravel
removal. Mining was conducted at this location in the late I950's during
construction of the Nome-Taylor Highway. Access was via a short 60-m gravel
road leading from the highway. A gravel fill ramp protected the I . 5-m in-
cised floodplain bank. There was no evidence of site rehabilitation; the
access road remains and its end has been eroded by the river. Material
stockpiles and overburden berms were not observed in the floodplain. Various
aspects of this site are shown in Figure 25.
NORTH SLOPE
General Description of Region
Eight gravel removal sites from two North Slope physiographic prov-
inces, the Arctic Coastal Plain (ACP) and Arctic Foothills (AFH), were
included in this study (Wahrhaftig 1965). Both provinces are underlain
by continuous permafrost. The study sites at Ugnuravik River and Kuparuk
River are in the Teshekpuk Section of the ACP wh i le the Skeetercake Creek
site is in the White Hills Section. Aufeis Creek, Sagavan i rk tok River, and
Kavik River sites are in the Northern Section of the Arctic Foothills Prov-
ince while the Ivishak River and Shaviovik River sites are near the border
between the two provinces. The Teshekpuk Section of the ACP Province is flat
and poorly drained, being very marshy in the summer (Figure 3). The poor
drainage results in part from a continuous permafrost layer from 0.2 to
1.2 m beneath the surface. Ice wedge polygons, beaded streams, and elongated
thaw lakes are common in this area. Pingos and incised river channels pro-
vide the only relief to the flat terrain. The study sites in this section
are in an area of coastal delta deposits of i nterstrat i f i ed alluvial and
marine sediments with some local glacial drift deposits.
In the White Hills Section of the ACP Province, the surficial geology
contains areas of undifferentiated alluvium and colluvium consisting of
42
Figure 5. Arctic Coastal Plain wetlands.
fine-grained deposits associated witti greatly sloping hills. Bedrock out-
crops are rare in this area. The Northern Section of the AFH Province is
characterized in its northern area by gently rolling terrain with occasional
isolated hills and in its southern area by rolling plateaus and low linear
mountains with broad east-trending ridges (Figure 4). The surficial geology
of the AFH is more complex than that in the ACP Province. The Aufeis Creek
study site is near a geologic contact between eolian silt deposits and
undifferentiated alluvial and co I I uv i a I deposits while the Kavik River and
Sagavan irktok River sites are flanked by remnants of moraines and associated
drift. The topography surrounding the Ivishak River site, near the border of
the ACP and AFH Provinces, is more typical of that of the White Hills Sec-
tion (Figure 5) while the Shaviovik River site is right at the interface of
the two provinces. The area to the south and west of the Shaviovik River
site is flat while that to the north and east is predominated by mildly
sloping hi I Is up to 360 m.
43
1
|s«;!fiaB-
Figure 4. Northern portion of the Arctic Foothills.
Figure 5. Typical view of the White Hills Section of
the Arct i c Footh ills.
44
The climate of the North Slope is characterized by long winters, cold
temperatures, and frequent winds. Normal temperature ranges are from 2
to I5°C in the summer and -30 to -22 C in the winter. Annual precipitation
along the Arctic Coastal Plain is approximately 13-15 cm, which includes
30-120 cm as snow, while in the Arctic Foothills, the annual precipitation
is about 25 cm, including 140 cm as snow.
The Teshekpuk Section of the ACP Province is characterized by flat
topography, wet tundra, and numerous lakes and ponds. All plants, including
woody forms such as wi I low and heath, are low growing. In most areas tundra
vegetation occurs up to the stream banks and woody thickets are not pres-
ent. The vegetation of the Northern Section of the AFH Province consists
of tundra species with small stands of taller riparian shrub thickets (2-5 m
in height) along the river systems.
Small river systems of the North Slope contain primarily resident
fish species, such as Arctic grayling, resident Arctic char, round white-
fish, burbot, and slimy sculpin, with estuarine species, such as fourhorn
sculpin, ninespine stickleback, and possibly whitefish species, entering
lower reaches. Larger river systems, such as the Sagavan i rk tok- I v i shak
drainage, also contain anadromous species, including Arctic char, chum
and pink salmon, broad whitefish, humpback whitefish, least cisco, and
Arctic Cisco, as well as the resident species.
Description of Study Rivers - Location and Gravel Removal Area
Character i st i cs
Ugnuravik River. Ugnuravlk River is a medium, sinuous river which
originates on the Arctic Coastal Plain at an elevation of 100 m and flows
across coastal plain tundra for 65 km before emptying into the Beaufort
Sea. It is primarily confined to a single channel except for a few short
beaded sections in the upper reaches. The study site is approximately 6 km
from the mouth at an elevation of 2 m.
45
The study site was developed by pit excavation and scraping approxi-
mately I ha within and adjoining the active channel of the Ugnuravik River.
Grave! removal was conducted during the winter from 26 March to I April 1969
with an unknown quantity of sand and gravel extracted from the site. Twenty-
three thousand cubic meters had been approved for removal, but the permittee
found that the gravel was only a veneer and not in sufficient quantities for
their needs. During this short period of operation, gravel was removed from
below the water table. Silt accumulation was noted in the gravel removal
area; overburden had been stripped and piled along both banks of the river;
and backhoe teeth were observed near the working limits. Various aspects of
this site are shown in Figures 26, 36, 83, and 92.
Aufeis Creek. Aufeis Creek is a medium, meandering river originat-
ing in the foothills near the Imnavait Mountains at an elevation of 670 m
and flows approximately 100 km before joining the Kuparuk River. The study
site lies at an elevation of 275 m approximately 60 km upstream from the
confluence with the Kuparuk River.
Material removed from this site was used for the construction of facil-
ities associated with oil exploration. Facilities constructed include a
l,34l-m airstrip, a camp work and storage pad, and access roads of approx-
imately 7 km in length connecting the stream with the airstrip and camp
pad. An estimated 288,000 m of material were removed during the winter of
1972.
There are two large and distinct gravel removal areas separated by
approximately 3,130 m of undisturbed stream. The upstream gravel removal
area covers 46 ha along a 2,260 m reach of the stream. The entire flood-
plain was scraped, including the channel bed itself. Clearing and removal of
approximately 20 ha of vegetation and overburden were required. There is no
evidence of rehabilitation following mining.
Mining at the downstream gravel removal area was less extensive and
included scraping the inactive floodplain, and in some areas, the adjacent
terraces along a 600 m reach of the stream. Deep and shal low scraping, as
46
well as pit excavation, were utilized to remove gravels. The main channel
of the creek was apparently not disturbed at the downstream area. Clearing
and removal of vegetation and overburden were required in the downstream
area. Dikes were also constructed, possibly to protect the integrity of
the main channel and prevent its spreading into the mined area. Various
aspects of this site are shown in Figures 14, 39, 54, 68a, 68b, 69, 75, and
81.
Kuparuk River. The Kuparuk River is a large, braided river which origi-
nates in the Brooks Range foothills and crosses the Arctic Coastal Plain
before discharging into the Beaufort Sea. The study site is located approxi-
mately 9 km upstream from the mouth of the Kuparuk River at an elevation of
less than 10 m.
The material site was developed by scraping unvegetated mid-channel
and lateral bars within the active floodplain of the Kuparuk River. Approx-
imately 41,300 m of gravel was removed from 14 ha between April and August
1969 to provide material for drill site pads, roadways, and airstrips near
the site. The site was scraped to within or slightly below the existing
water table. The 5-m incised floodplain bank was protected with a gravel
fill ramp. Sma II mounds of stockpiled material were noted within the materi-
al site. Various aspects of this site are shown in Figure 51.
Skeetercake Creek. Skeetercake Creek is a small, meandering stream
which originates in the northern edge of the foothi I Is of the Brooks Range
at an elevation of about 300 m and flows approximately 40 km to its conflu-
ence with the Toolik River. The study area lies at an elevation of about
160 m, approximately 15 km upstream from the confluence.
Material removed from Skeetercake Creek was used for oil drilling
operations. Gravel extraction at the site was accomplished during December
1965 by scraping 10 ha of floodplain deposits on three consecutive meanders.
Approximately 38,000 m of gravel were reportedly removed, much of which
apparently was not used; the unused material was pushed into large stock-
piles which still remain in the upstream gravel removal area.
47
Vegetative clearing, overburden removal, and berm construction were
conducted at each of the three gravel removal areas. At the upstream area
the overburden was formed into an earthen dike, the purpose of which is
unclear. The gravel removal areas were not rehabilitated following distur-
bance. Various aspects of this site are shown in Figures 37, 42, and 48a.
Sagavan irk tok River. The Sagavan ir k tok River is a large, sinuous river
(at the study site) which originates in the Philip Smith Mountains of the
Brooks Range at an elevation of approximately 1,500 m and flows through
mountains, foothills, and coastal plains approximately 300 km before enter-
ing the Beaufort Sea. The study site, at an elevation of 335 m, is located
about II km downstream from Pump Station Number 3 on the Trans-Alaska Pipe-
line, 16 km downstream from the mouth of Ribdon River, and 21 km upstream
from the mouth of Lupine River.
Gravel removal occurred in 1974 and 1975 by scraping vegetated and
unvegetated gravel bars totaling approximately 35 ha. About 15 ha had been
vegetated with mature riparian willow thickets. The original mining plan
cal led for scraping to an average of 1.5m in depth with an average of 15 cm
of overburden removal required prior to gravel extraction. Approximately
283,000 m and 148,000 m of gravel were removed from the upstream and
downstream gravel removal areas, respectively. Access to the f I oodp I a i n was
gained via a gravel ramp which protected the floodplain incised bank.
Prior to site abandonment in 1976, existing stockpiles and berms were
leveled and contoured, and the gravel fill ramp protecting the bank was to
be removed. Various aspects of this site are shown in Figures 44, 45, 76,
and 82.
Ivishak River. The Ivishak River is a large, braided river which origi-
nates in the Philip Smith Mountains at an elevation of 1,829 m and flows
80 km through the mountains and 45 km through the foothills before entering
the Sagavan irktok River. The study site lies II km upstream from the conflu-
ence of the Sagavan irktok River.
46
Ma1-erial removed from the Ivishak River was used for the construc-
tion of facilities associated with oil exploration. Gravel extraction was
accomplished by scraping unvegetated, mid-channel gravel bars within the
active floodplain of the Ivishak River. Two separate winter gravel removal
operations were conducted at this location with 115,000 m extracted during
March and April 1972 and 3,800 m extracted during November and December
1974. Information pertaining to the size of the gravel removal area is not
available because removal occurred on randomly located gravel bars within
the permit area; however, the average depth of excavation planned for the
1972 operation would require approximately 40 ha of exposed material.
Three separate gravel removal areas were observed in the field. The
upper area is located upstream from the airstrip in the left quarter of
the active floodplain. The middle area lies in the middle of the flood-
plain covering an area equivalent to the upstream one-third of the air-
strip. The lower area lies about one-third of the way across the flood-
plain from the left bank, just downstream of the downstream end of the
a irstr i p.
Vegetative clearing, overburden removal, or dike construction were
not necessary at the site. Gravel ramps were used for access to the flood-
plain over the river bank at most points of entry, however, at the down-
stream access point the 2-m incised bank was cut instead of protected by
gravel fill. Two gravel haul roads 90 to 150 m long connect the airstrip
to the material site. During 1972 and 1974 dozers were used to rip and
stockpile material for front-end loader transfer to scrapers and trucks.
Maximum excavation depth was to the existing water level at the time of
the gravel removal operation.
Rehabilitation measures used in 1972 and 1974 were similar: depres-
sions were filled, stockpiles were leveled and gravel ramps were removed
prior to breakup. Various aspects of this site are shown in Figure 71.
Shaviovik River. The Shaviovik River is a medium, sinuous river which
originates in the Brooks Range at an elevation of 909 m and flows for 95 km
49
before emptying into the Beaufort Sea. The study area is 95 km from the
mouth at an elevation of 230 m.
Gravel was scraped from unvegetated gravel bars within the active
floodplain. The gravel was used in construction of oil exploration facil-
ities including a drilling pad, campsite, supply pads, and landing strip.
The proposed extraction area encompasssed approximately 2.4 km of flood-
plain. Gravel removal was conducted during the winter of 1972 with
I 16,000 m extracted between March and spring breakup. Vegetative clearing
and overburden removal were not necessary before gravel removal. Material
was stockpiled with a dozer and loaded into dump trucks with a front-end
loader. Excavation below the water table was not permitted under the provi-
sions of the mining plan. Access over the river bank to the mined area was
by gravel ramp.
Upon completion of gravel removal al I excavated sites were to be
smoothed by back-blading with a dozer and the gravel access ramp over the
stream bank was to be removed. At the time of site inspection the gravel
ramp was still present and essentially intact. Various aspects of this site
are shown in Figures 4, 72, and 91.
Kav i k R i ver . The Kavik River is a medium river flowing in split channel
configuration. It originates in the Brooks Range at an elevation of 1,200 m
and flows 125 km to its confluence with the Shaviovik River. The study site
is 60 km from the confluence with the Shaviovik River at an elevation of
180 m. Downstream from the study reach the floodplain widens and takes on a
braided configuration.
Approximately 40 ha were mined by scraping mid-channel and lateral
gravel bars within the active floodplain of the Kavik River. Gravel was
used for construction of an airstrip and road, and for development of four
oil well pads. Approximately 196,000 m were removed in 1968-1969 with
another 50,000 m extracted in 1973-1974. The initial gravel removal activ-
ity at this site was a trespass action and a mining plan is not available.
Gravel removal was conducted during the winter with scrapers and belly
50
dumps; gravel removal was completed prior to breakup. Most disturbed gravel
bars contained sparse vegetative cover consisting of herbaceous plants and
scattered young willows; however, one 2-ha island vegetated with a mature
willow thicket was removed. The overburden and slash from this island were
piled within the gravel removal area.
Diversion dikes were constructed to direct flow from the gravel removal
area, and a 2-ha gravel stockpile was located on the edge of the floodplain.
The 2-m incised floodplain bank was cut in five locations to gain access to
the floodplain or to reach underlying gravel deposits. Approximately 375 m
of bank were disturbed. Rehabilitative measures were not employed following
the activity, hence all dikes, stockpiles, overburden piles, and cut banks
remained during the site visit. Various aspects of this site are shown in
Figures 5 and 77.
NORTHERN INTERIOR
General Description of Region
All six study sites in this region are located in the Koyukuk River
watershed. Four sites, Dietrich R i ver-Upstream, Dietrich River-Downstream,
Middle Fork Koyukuk R i ver-Upstream, and Middle Fork Koyukuk River-Down-
stream, are in the Central and Eastern Brooks Range Section of the Arctic
Mountains Physiographic Province, while Jim River and Prospect Creek, are in
the Kokr i ne-Hodzana Highlands Section of the Northern Plateau Physiographic
Province (Wahrhaftig 1965). The Central and Eastern Brooks Range Section is
characterized by flat-floored glacial valleys and east-trending ridges that
rise to elevations of approximately 1,800 m (Figure 6). Minor tributaries
typically flow east and west, parallel to the structure imposed by the belts
of sedimentary and volcanic rocks. Valley walls are dominantly coarse rubble
deposits associated with steep sloped mountains which have a high percentage
of bedrock exposures. The valley bottom in the vicinity of the Middle Fork
Koyukuk River study sites consists of unmodified moraines and associated
drift. The area is underlain by continuous permafrost. The Jim River and
Prospect Creek sites, in the Kokr i ne-Hodzana Highlands, are in an area of
51
Figure 6. M.F. Koyukuk River valley looking upstream.
coarse and fine-grained deposits associated with moderate to steep sloped
mountains and hills; bedrock exposures are limited to upper slopes and
crestlines (Figure 7). The area is underlain by discontinuous permafrost.
Normal temperature ranges in the Northern Interior are from 2 to 20 C
in the summer and -30 to -8 C in the winter. The annual precipitation is
about 28-38 cm, which includes 190-210 cm as snow.
The valleys in the Dietrich River-Middle Fork Koyukuk River region
are heavily wooded with both steep, timbered slopes and gently sloping
terraces adjacent to the river. The slopes are vegetated primarily with
stands of white spruce and paper birch. In the Jim River-Prospect Creek
area, the valleys are heavily wooded with white spruce and paper birch
and a thick understory. Resident fish species found in the Koyukuk River
system include burbot, Dolly Varden or Arctic char, Arctic grayling, long-
nose sucker, northern pike, slimy sculpin, round whitefish, inconnu, and
52
'^'^^^^Si
Figure 7. Typical terrain of the Kokr i ne-Hodzana Higti-
I ands.
ottier whitefish species. Anadromous species include ctium and Chinook salmon
and possibly anadromous whitefish species.
Description of Study Rivers - Locations and Gravel Removal Area
Character i st i cs
Dietrich River - Upstream and Downstream. The Dietrich River is a
medium, braided river which originates in the Endicott Mountains of the
Brooks Range at an elevation of approximately 1,500 m and flows southward
through mountainous terrain for 110 km, joining the Settles River to form
the Middle Fork Koyukuk River.
The upstream study site is located approximately 4 km, 14 km, and
25 km upstream from the confluence with Big Jim Creek, Snowdon Creek, and
Bettles River, respectively. The downstream site is located 17 km and 6 km
53
upstream from the confluence with the Settles River and Snowdon Creek,
respectively, and 8 km from the upstream site.
The upstream site was excavated in an al luvial gravel deposit within
the active f I oodp I a i n of the Dietrich River. Between late summer 1974 and
early 1977, 631,000 m of gravel was removed from the 35-ha site for con-
struction of the Trans-Alaska Pipeline. A dike was constructed across an
intermittent channel north of the gravel removal area to divert active flow
or seasonal ly high water away from the material site.
Two methods were used to remove gravel. Most of the site was scraped
to an average depth of 3 m while a pit was excavated by dragline in the
southern end of the work area. This pit is approximately 240 x 90 m and
was excavated to an average depth of an additional 2 m below the scraped
portion of the gravel removal area. Within this pit two deeper holes approxi-
mately 9 m deep were excavated. Ground springs were encountered during the
scraping operation. The ground springs have been diverted through two chan-
nels into the deep pit. Aufeis formation was a natural occurrence in this
area before gravel removal and was observed downstream from the pit drainage
channel during the first winter following excavation.
A screening-crushing operation was used to produce pipeline padding and
bedding material; stockpiled processed material also was stored at this
location. The material site was utilized as a concrete fabrication area
in August 1975 to produce cement castings of pipeline weights.
In the summer of 1977 the area was sloped and contoured to drain water
into the gathering channels leading to the deep pit. The southern and north-
ern portions were then reseeded with annual grasses. The central portion was
left open for access to stockpiled maintenance and operation gravel for the
Trans-Alaska Pipeline.
The Dietrich River-Downstream site was worked by shallow excavation
of a gravel deposit within the active floodplain of the Dietrich River.
Gravel was removed from the 7.5-ha site with 128,590 m of material ex-
54
tracted during 1975 for conslruct i on of the Trans-Alaska Pipeline. Over-
burden within the working limits required disposition and stabilization
outside the active floodplain. Permit provisions required a 90-m undis-
turbed buffer between the working limits of the material site and active
channels of the Dietrich River. Braided channels that flowed east of the
material site were diverted west of the site by an upstream dike to pre-
vent active flow during excavation. Fine to coarse gravel with sand and a
trace of silt was excavated to a 0.9 m depth. Rehabilitation measures conduc-
ted after mining included sloping of all aliquots to the southwest. Various
aspects of this site are shown in Figures 47a and 73.
Middle Fork Koyukuk River - Upstream and Downstream. The Middle Fork
Koyukuk River is a large, sinuous river which originates in the Brooks Range
at the confluence of the Dietrich and Settles Rivers and flows 116 km before
joining the North Fork Koyukuk to form the Koyukuk River. The Middle Fork
Koyukuk River flows in inconsistently spaced reaches of braided and single
channel patterns.
The upstream study site is located about 92 km from the confluence of
the Middle Fork Koyukuk and North Fork Koyukuk Rivers at an elevation of
365 m. The downstream study site is 45 km from the confluence with the North
Fork Koyukuk River and 47 km downstream from the upstream study site at an
e I evat i on of 282 m.
At the upstream study site gravel extraction was accomplished by shal-
low excavation of sparsely vegetated gravel bars associated with the active
channel and excavation to the same elevation in the contiguous, vegetated
al I uv i a I terrace. From August to November 1974, 135,000 m of gravel was
removed from about 20 ha.
The material site is comprised of two parcels; the upper area encom-
passes a high-water channel while the lower area is situated on the inside
bend of the next meander downstream. The upper area was unvegetated prior
to gravel removal. Scattered stands of shrub thickets occurred within the
active floodplain portion of the lower area and the adjacent alluvial ter-
'i'i
race had to be cleared of mature white spruce and balsam poplar prior to
gravel removal. Overburden was not present on the active floodplain area,
however, 15 cm of organic silt were stripped from the alluvial terrace and
disposed of southeast of the lower area.
An undisturbed 30-m buffer was maintained between the active chan-
nel and the working limits of the lower area; natural depressions and minor
channels through the buffer were augmented by construction of perimeter
dikes not exceeding 0.3 m above the natural buffer elevation. Caterpillar
tractors with rippers and self-loading bottom dump scrapers were used to
excavate to depths of 0.9 m in the active floodplain and 3.0 m in the adja-
cent al I uv i a I terrace area. The upper area was scraped to a depth of 0.9 m.
Material extracted from the active floodplain was seasonal ly frozen,
sandy, fine to coarse rounded gravel. The al I uv i a I terrace provided frozen,
interlayered silty and sandy gravel to the water table. Screening and stock-
piling of select material was conducted on the floodplain. Permit provisions
required that unused material of silt size and finer be disposed of outside
the active floodplain; unused coarse material from the screening process
could be evenly spread in the gravel removal area.
During site rehabilitation the disturbed area was graded to an even
bottom with cut faces no steeper than 2:1, stockpiles were removed, and
outlet channels were constructed at the downstream end to allow high-water
drainage. Revegetation within the active floodplain was not attempted due
to the likelihood of periodic flooding. Various aspects of this site are
shown in Figures 15, 47b, 49, 52, and 88.
The Middle Fork Koyukuk River-Downstream site was developed by shal-
low scraping of a sparsely vegetated lateral gravel bar within the active
floodplain. The gravel removal operation was conducted during the winters of
1975 and 1976 with 215,000 m of material removed from 28 ha. Permit pro-
visions required overburden encountered within the working limits to be
disposed of and stabilized outside the active floodplain.
56
A material site investigation conducted prior to removing gravel report-
ed we I l-rounded gravel with some seams of fine sand and an absence of perma-
frost in test pits. Approximately 38,000 m of select material was produced
from a screening operation and stockpiled outside the material site working
limits. Rehabilitation of the site following completion of the gravel remov-
al activity did not include seeding or revegetation of the leveled gravel
due to the likelihood of periodic flooding. Various aspects of this site are
shown in Figure 6.
Jim River. The Jim River is a medium, sinuous river which originates
at an elevation of 880 m and flows about 96 km before emptying into the
South Fork of the Koyukuk River. The study area is located 37 km from the
mouth at an elevation of 275 m.
Material removed from this site was used for the construction of facili-
ties associated with the Trans-Alaska Pipeline. An access road (90 m in
length) was constructed connecting the site to the Haul Road. Vegetative
cover and underlying organics were removed. Gravel extraction was accom-
plished by scraping about II ha, yielding an estimated 200,000 m of gravel.
The site was worked during winter to a level below the water table. As a
result, the site was inundated during summer, leaving, at the time of the
survey, a shal low pit consisting of two ponded segments, approximately 5 and
I ha in size with a maximum water depth of 1.2 m. The former high-water
channel now flows continuously through the site thus connecting the pit area
with the main Jim River.
Restoration began during the fal I of 1976. The site was contoured,
including sloping the banks on the south, north, and west sides of the
site, and revegetated. The excavated depression was filled in restricting
water to the east side of the gravel removal area and reducing the inun-
dated pit area to I ha by 1978. Various aspects of this site are shown in
Figures 7, 48b, and 78.
Prospect Creek. Prospect Creek is a medium, meandering stream which
originates at an elevation of about 600 m and flows 40 km to its conflu-
57
ence with the Jim River. The study site lies at an elevation of 270 m approx-
imately 5 km from the mouth of Prospect Creek. The site was worked by scrap-
ing surface gravel deposits over 6 ha of gently sloping terrain adjacent to
Prospect Creek. In addition, a l-ha pit was excavated on the northern edge
(lowest point) of the gravel removal area to act as a sediment catch basin.
Gravel removal was conducted intermittently from April 1974 through April
1975 with 63,636 m of gravel removed for construction of the Trans-Alaska
Pipeline System. A 45-m wide buffer was maintained between Prospect Creek
and the gravel removal area, however, a 90-m wide swath was cleared through
this buffer zone on 22 May 1974.
Gravel removal was accomplished by ripping frozen material prior to
conventional loading and hauling methods. Material varied from clean to
silty fine to coarse gravel. An average working depth of 2.7 m was planned
for the catch basin pit with additional excavation permitted if suitable
material was present below this level. A screening operation to produce
select material was conducted in the pit.
The pit has filled with water as a result of intergravel flow during
the summer months. During the site visit, this ponded water averaged approxi-
mately I m in depth. The pit does not have an inlet, however, an outlet
leading to Prospect Creek from the northwest corner was constructed during
site rehabilitation activities to allow unimpeded fish passage into and out
of the pit.
Additional rehabilitation measures included grading the material site
to I percent downslope, ensuring that al I cut slope faces were no steeper
than 2:1, and leveling of temporary stockpiles to blend with the natural
terrain. Various aspects of this site are shown in Figures 28 and 55.
SOUTHERN INTERIOR
General Description of Region
All five study sites in the Southern Interior were located in the
Tanana River drainage, which empties into the Yukon River. The study sites
58
are located in three physiographic provinces - the Yukon-Tanana Upland
Section of the Northern Plateaus Province (West Fork Tolovana River and
McManus Creek), the Tanana-Kuskokwim Lowland Section of the Western Alaska
Province (two Tanana River sites), and the eastern portion of the Alaska
Range Section of the Alaska-Aleutian Province (Phelan Creek) (Wahrhaftig
1965).
The Yukon-Tanana Upland Section is characterized by rounded ridges
and flat, alluvium floored valleys (Figure 8). Surface deposits tend to
<^;k . Ai
Figure 8. Typical terrain in the Yukon-Tanana Upland
Sect i on.
coarse and fine-grained alluvium and colluvium. Bedrock exposures are gen-
erally limited to upper slopes and ridges. The area is underlain by discon-
tinuous permafrost and is subject to extreme temperature ranges, from -45 C
in the winter to 32 C in the summer. The average annual precipitation is
33-35 cm, which includes 130-150 cm as snow.
59
The Tanana-Kuskokwim Lowland Section in the vicinity of the Tanana
River study sites is characterized by extensive g I aciof I uv i a I deposits
and large alluvial fans (Figure 9). The area is immediately south of the
l**!nfi35iJ
^^^
Figure 9. G I ac i of I uv i a I deposits in Dry Creek floodplain,
Yukon-Tanana Upland section. The Tanana River basin lies in an area of
discontinuous permafrost. The climate is typified by cold, dry winters and
warm, relatively moist summers with an annual precipitation of around 32 cm,
including about 90 cm as snow.
The Alaska Range Section is characterzed by glaciated ridges between
mountains to 2,900 m (Figure 10). Unmodified moraines and associated drifts
dominate the surficial geology. The area is underlain by discontinuous
permafrost. Normal temperatures range from 2 to 17 C in the summer and -33
to l°C in the winter. An annual precipitation of 43 cm includes 275 cm as
snow.
60
^^•M^
w- ,'.
'"•■i.
■!.%T-
Figure 10. Typical view of Alaska Range Section.
The vegetation at the Southern interior study sites varied because
of differences in climate, elevation, and geology of the three physiographic
provinces. The West Fork Tolovana River site is in a valley heavily wooded
with white spruce and paper birch with a thick understory, particularly
along the river. At McManus Creek, the surrounding hillsides have thin
stands of white spruce with dense underbrush. The floodplain areas devoid of
white spruce are covered with willow thickets with woody and herbaceous
groundcover. At the two Tanana River sites the adjoining hillsides are
covered with dense stands of aspen and paper birch with scattered white
spruce while islands in the fl oodp lain are covered by 10 to 20 m tall stands
of white spruce with scattered paper birch. The vegetation surrounding the
Phelan Creek site consists of subalpine tundra, upland thickets associated
with the drainages, and scattered, open stands of white spruce.
Resident fish species found in the Tanana River system include Arctic
grayling, northern pike, burbot, longnose sucker, slimy sculpin, various
6!
whitefish species, and scattered Dolly Varden populations. Anadromous spe-
cies include coho, chum and Chinook salmon, and various whitefish species.
Species of whitefish found in the drainage include Bering cisco, broad
whitefish, humpback whitefish, least cisco, round whitefish, and inconnu.
Most of these species show substantial movements within the Yukon River
drainage and distribution and anadromy has not been well documented for many
of the species.
Description of Study Rivers - Location and Gravel Removal Area
Character ist i cs
West Fork Tolovana River. The West Fork Tolovana River is a medium,
meandering river originating in the foothills of the White Mountains in
the Yukon-Tanana Upland Section at an elevation of 915 m. The confluence
of the West Fork Tolovana River and Tolovana River, a tributary to the
Tanana River, lies 6 km downstream from the study site. The material site
is located on the east side of the river with an undisturbed 60-m buffer
strip between the site and the river. The mining occurred in an abandoned
channel with the upstream end of the channel plugged to prevent water flow
through the site. The outlet, however, is open to a backwater area of the
river. The 8-ha site was worked in 1975 by a dragline with 101,500 m of
material removed, stockpiled, and screened to produce the required quanti-
ties of select materials. The pit filled with groundwater and has depths
in excess of 6 m. The unflooded portions of the gravel removal area were
contoured and sloped to drain toward the pit in 1976. Most of these areas
were also reseeded by Alyeska Pipeline Service Company with annual grasses.
Various aspects of this site are shown in Figures 48c, 56, 59, 62, 63, and
84.
McManus Creek. McManus Creek is a small, sinuous stream which origi-
nates in foothills at an elevation of I ,000 m and f I ows 25 km to its conflu-
ence with Smith Creek, forming the Chatanika River. The study site lies at
an elevation of 675 m, approximately 20 km from its confluence with Smith
Creek. During the course of its development, McManus Creek has tended to
migrate lateral ly southward, causing a si ightly steeper val ley wa I I on the
left than on the r i gh t .
62
The material site was developed during construction of the Steese
Highway by scraping gravel deposits within and adjoining the main channel of
McManus Creek. A small gravel pit was also dug along the northwest boundary
of the site, in an area where the floodplain meets the valley wall. During
gravel removal operations, it was necessary to clear and remove the dense
vegetation at the 3-ha site. An estimated 75,000 m of gravel were made
available for use by these efforts, although a considerably smaller amount
is thought to have actually been removed. Large mounds of removed overburden
and unused gravels were left within the site. Site rehabilitation was not
performed following mining activities. The revegetation that has occurred is
attributed to natural reinvasion. Various aspects of this site are shown in
F i gure 89.
Tanana River - Downstream and Upstream. The Tanana River is a large,
braided river fed by many glaciers in the Alaska Range. The Tanana River-
Downstream study site is adjacent to the Richardson Highway approximately
57 km downstream from the Tanana River and Delta River confluence at an
elevation of 260 m. The site was developed by pit excavation of the central
portion of a vegetated island located within the active floodplain of the
Tanana River. Excavation was conducted after March 1971 with approximately
510,000 m of material removed from within the 8-ha working limits. Cleared
and stripped surface materials were disposed of in waste areas along the
borders of the pit. Permit stipulations required a minimum 91 m buffer along
the highway and a minimum 50-m undisturbed buffer along adjacent side-
channels of the Tanana River. Maximum depth of excavation in this uncon-
nected, water-filled pit was approximately 9.4 m. The site was not reha-
b i I i fated.
The Tanana R i ver-Upstream study site is adjacent to the Richardson
Highway approximately 9 km downstream from the Tanana River and Delta River
confluence at an elevation of 290 m. The gravel removal area was developed
by pit excavation of a vegetated gravel deposit adjacent to an active side
channel of the Tanana River. The pit was excavated in two parcels herein
cal led the upper and lower pits, which are segregated from the river by a 30
to 40-m wide vegetated buffer. A single channel at the downstream end of the
63
lower pit connects the excavated area to the Tanana River. Mining operations
were conducted between 1962 and 1965 during reconstruction of the Richardson
Highway between Shaw Creek and Delta Junction. The actual amount of gravel
removed is unknown but 133,600 m w^re approved for removal at this loca-
tion. The upper and lower pits total about 7.5 ha. Access to the site was
via a lOO-m gravel road from the Richardson Highway.
Clearing of dense willow and alder and scattered white spruce and
paper birch was necessary before stripping of 0.6 to 0.9 m of brown silt,
fine sand, and organic material. Coarse gravel was present below the over-
burden with 10 to 15 percent oversized material. Small stockpiles of gravel
were noted along the south edge of the pit. In the upper pit the excavation
occurred in an irregular pattern over about 3.5 ha, creating numerous is-
lands and spits. The lower pit on the other hand was mined contiguously over
4 ha, is of greater average depth, and contains no major elevated land forms
within its main boundaries. It did not appear that the site was rehabil-
itated following gravel removal. Various aspects of this site are shown in
Figures 27, 57, 70, and 80.
Phelan Creek. Phelan Creek is a small, braided river which originates
at an elevation above 1,200 m at the Gulkana Glacier and flows 19 km through
the mountainous terrain of the Alaska Range before joining the Delta River.
The study site is located approximately 3 km upstream from the Richardson
Highway crossing of Phelan Creek and 9 km downstream from the terminous of
the Gu I kana G I acier .
The material site was worked by scraping unvegetated exposed deposits
in the active floodplain of Phelan Creek during construction of the Trans-
Alaska Pipeline System. Approximately 152,000 m were removed from the 25-ha
original work area between July and October 1975; a 70-ha upstream expansion
was approved in late October and yielded an additional 423,000 m .
Several high-water channels traversed both the original work limits and
the area encompassed by planned expansion to the east. The major active
channels of Phelan Creek flowed through the original working area at the
t ime of the survey .
64
Vegetative clearing and overburden removal were not necessary for
the removal of the sandy gravel with some cobbles and boulders. A I 5-m
buffer was maintained between the work area and main channel of Phelan
Creek; this natural buffer was augmented by dikes across depressions and
minor channels. A dike was constructed at the upstream end of the site to
divert intermittent channel flow and an outlet channel was provided at the
downstream end of the gravel removal area to facilitate drainage. Material
was removed to a 0.9-m working depth with conventional loading and hauling
methods; permafrost was not present but ripping with dozers was necessary
for excavation of seasonally frozen ground. Similar working depths, excava-
tion methods, and diversion/buffer procedures were used during development
of the upstream expansion.
The site apparently was not rehabilitated, because several dikes and
one stockpile remained during the time of the site visit in 1978. Various
aspects of this site are shown in Figure 90.
65
REFERENCE
*ahrhaftig, C. 1965. Physiographic Divisions of Alaska. U. S. Geological
Survey. Prof. Paper 482. 52 pp.
66
EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS
L. A. Rundquist
INTRODUCTION
The purpose of the hydrology and hydraulics study was to evaluate
the effects of floodplain gravel removal on the river configuration, hy-
draulics, sedimentation, ice characteristics, and hydrology at the 25 study
sites. The locations of these sites are shown in Figure I. The characteris-
tics describing the physical aspects of the site and the gravel removal
methods are listed in Table I. General descriptions of the sites are pro-
vided in DESCRIPTION OF STUDY RIVERS.
Previous studies of gravel removal from river floodplains are limited
in number. A preliminary report for this project (Woodward-Clyde Consultants
1976a) reviewed literature on gravel removal up to that time. Significant
results of that review are included and expanded upon in this section. Other
pertinent literature identified since 1976 are included in this section.
A few general statements (from Woodward-Clyde Consultants 1976a) con-
cerning the behavior of rivers are given in the following paragraphs to
provide a basis for the information presented in subsequent sections.
A river continually changes its position and shape as a consequence of
hydraulic forces acting on its bed and banks. These changes reflect the
dynamic condition of the natural environment; they may be slow, gradual
processes or sudden morphological changes resulting from an extreme flood
event. A river system always strives toward a state of equilibrium in order
to convey the water and sediment delivered to it.
67
Similarly, when a stream is altered locally, the change often causes
modification of the channel characteristics for considerable distances both
upstream and downstream. The river response to changes is quite complex, but
all rivers are governed by the same basic forces. From a review of available
literature on river response to alterations, some general statements can be
made on the basis of past research results (Karaki et al. 1974).
• Depth is directly proportional to water discharge and inversely
proportional to sediment discharge.
• Channel width is directly proportional to water discharge and to
sediment discharge.
• Channel shape (width:depth ratio) is directly related to sediment
d i scharge.
• Meander wave length is directly proportional to water discharge
and to sediment discharge.
• River slope is inversely proportional to water discharge and directly
proportional to sediment discharge and grain size.
• Sinuosity is proportional to valley slope and inversely proportional
to sediment discharge.
Although these relationships cannot be used to predict the exact re-
sponse of a river to alterations, they do reveal the i n terdependency of the
river parameters.
Local modifications to a river can induce short-term and long-term
responses. During excavation, channel morphology and sedimentation charac-
teristics may be changed. After the operation has ceased, the river will
tend to readjust to the geometry and pattern that it had previously; if the
magnitude of the modification is large enough, the readjustment may take
many decades to complete. The short-term responses are usually observable
68
and may be measurable; however, the long-term response may be so gradual
that the changes will not be noticeable for decades.
In addition to these general statements pertaining to all rivers,
a few characteristics of arctic and subarctic rivers are introduced below.
Flow stops in many rivers for much of the winter. Those rivers that continue
to flow in the channel beneath the ice or in the gravel beneath the channel
have the potential to develop auf ei s, which is ice that forms upon itself by
a series of overflows. The remaining flow is considered vital to fish over-
wintering areas.
At breakup, the water levels of large snowmelt floods are often in-
creased by ice jamming or aufeis in the channel. After the snowmelt flood,
flow may decrease significantly for the rest of the summer except for a few
short duration events in response to summer storms. Very low summer flow is
especially common on the North Slope, which is semiarid, receiving only
150 mm of precipitation annual ly.
In subarctic Alaska, glaciers feed many rivers, resulting in generally
more uniform flows through the summer. Diurnal fluctuations are evident in
these rivers near their headwaters. Associated with glaciers are glacier
dammed lakes that can empty rapidly causing extensive flooding downstream.
69
METHODS OF DATA COLLECTION
The hydrology and hydraulics field program was conducted to provide
information for the evaluation of gravel removal impacts on the physical
characteristics of the river within the study reach. Three consecutive
days were available at each of the 25 study sites for collection of these
data. The site visit was during the summer when the water level was rela-
tively low so that the channels could be more easily crossed. Details on
the procedures used can be found in APPROACH AND METHODOLOGY.
70
METHODS OF DATA ANALYSIS
The evaluat-ion of changes resulting from gravel removal operations
at the 25 study sites was based primarily on subjective judgement. A few
hydrologic and hydraulic analyses were performed to enhance the data base
for making further evaluations and biological analyses. A table was prepared
that listed quantitative values for the subjective evaluation of changes,
and was used to compare sites and, thereby, to evaluate the relative change.
The following subsections describe briefly the methods used in th« analys«s.
HYDROLOGY
Mean annual flows and flood frequency curves were developed for the
25 study sites. There were no U. S. Geological Survey gaging stations ^t
the study sites. Nine sites were near enough to gaging stations to use
the gaging station data, although none of the station records exceeded
12 years in length. Standard regional regression techniques were difficult
to use because of the sparse gaging station network in arctic and subarctic
Alaska. The hydrologic analyses thus include a significant amount of judge-
ment; thus, the results should be considered as rough estimates.
Mean Annual Flow
The mean annual flows at six U. S. Geological Survey gaging stations
were used as a basis for the analysis. The unit mean annual flow (mean
annual flow per square kilometer of drainage basin) was computed for these
stations. Nine of the study sites were near enough to the stations to use
the station's unit mean annual flow. At the remaining 16 sites, the unit
mean annual flow from the nearest gaging station was modified after con-
sidering the difference in mean annual precipitation of the drainage basins
for the gaged river and the study site.
71
Flood Frequency Analysis
Flood frequency curves for each of the study sites were generated
by applying a regional analysis technique described by Lamke (1979).
Discharges for the I. 25-, 2-, 5-, I0-, 25-, 50-, and 100-year recur-
rence intervals were computed. In order to improve these estimates,
flood frequency data based on the application of the Log Pearson Type
III distribution were requested from the U.S. Geological Survey for 17
gaging stations on or in the general area of the study sites. The re-
gression equations presented by Lamke were also used on these gaged
rivers and the ratio of the Log Pearson Type III discharges to the
discharges calculated from the regression equations were computed.
These ratios were then applied to the study sites if the sites were (I)
on the same river but upstream or downstream from the gaging site, (2)
a similar size to that of the gaged river, and (3) if the drainage
basin characteristics such as headwaters location, aspect, and drainage
basin shape were similar. The resulting discharges were used to develop
flood frequency curves for each of the study sites.
HYDRAUL ICS
Three analyses were included in the hydraulic investigation: back-
water analysis, uniform flow analysis, and hydraulic geometry analysis.
Each of these are discussed in the following separate subsections.
Backwater Analysis
A backwater analysis was performed for most of the rivers included
in the study using the standard step method (Chow 1959). Input data to
the program included a selected discharge, a corresponding water sur-
face elevation at the control section, cross-sectional geometry of each
cross section in the study reach, distances between cross sections, and
roughness coefficients for each subsection of each cross section.
72
Uniform Flow Analysis
In addition to the flood flow computations performed in the backwater
analysis, values of some geometric and hydraulic parameters at low flows
were computed in order to relate these parameters to the corresponding
discharge and to provide data for the aquatic habitat evaluation. Use of the
backwater program was not appropriate for low flows because of the small
number and wide spacing of cross sections in the study reaches. The flows at
the surveyed cross sections were assumed to be uniform and computations were
made using the Manning equation (Chow 1959).
The input data to the uniform flow program included the cross-sectional
coordinates, roughness coefficients, energy slopes, selected discharges, and
initial estimates of stage. The surveyed water surface slope was used as an
estimate of the energy slope because most surveys took place when rivers
were carrying flow similar in magnitude to the mean annual flow. Similarly,
the roughness coefficient was calculated from the measured discharge and
geometry rather than from estimates used in the backwater analysis. This
calculation technique was used because roughness would likely be greater at
low flows than that at flood flows due to the greater influence of the bed
roughness at sma I I depths.
Hydraulic Geometry Analysis
Values of the coefficients and exponents in the power relations for the
hydraulic geometry (including mean velocity) at a cross section were com-
puted for disturbed and undisturbed cross sections at five selected study
sites. Power curve fitting was completed for the geometric and corresponding
discharge data which were determined by the hydraulic analyses discussed in
the previous subsections. The resulting coefficients and exponents were
compared with the values obtained for other rivers in Alaska and other parts
of the United States. In addition to this quantitative comparison, a quali-
tative comparison of power relation coefficients and exponents for disturbed
and undisturbed cross sections was made based on plots of the power curves
for each cross section of other sites having insufficient data range for a
quantitative analysis.
73
QUANTIFICATION OF CHANGES
At each of 1"he 25 study sites an attempt was made to quantitatively
rate the degree of change of selected river characteristics due to the
gravel removal operations. When quantifying changes, the selected charac-
teristic should be compared before and after the gravel removal operation
under similar flow conditions. Whenever possible, this was done using aerial
photographs. Aerial photographs often did not provide the necessary detail,
or the lack of information concerning flow conditions in the photographs
made such comparisons less meaningful. Thus, the upstream sample area was
assumed to represent the undisturbed condition for many of the comparisons.
After comparisons were made, a rating scale was applied to establish the
relative degree of change occurring in physical characteristics at the
various sites.
A scale was selected ranging in value from 0 to 10, with 0 being a
very large decrease in the quantity of a characteristic, 5 indicating no
change, and 10 being a very large increase in the quantity of a character-
istic. Intermediate values reflect various degrees of change between the
extreme values. More specific meanings of the degree of change for each
characteristic are given in the following RESULTS AND DISCUSSION section.
All sites were rated using the rating scales. Sites with more than
one physical response to the gravel removal activity were given more than
one rating. These sites included Sinuk River, Washington Creek, Oregon
Creek, Aufeis Creek, and Middle Fork Koyukuk R i ver-Upstream. At all other
sites, the physical changes resulting from the gravel removal operation were
similar throughout the site. The gravel removal areas for all sites are dis-
cussed in general in the previous section (DESCRIPTION OF STUDY RIVERS). The
separation of the gravel removal areas for the hydrologic and hydraulic
analyses at selected sites is described in the following paragraphs.
At Sinuk River, different responses to gravel removal were observed for
two gravel removal locations. These locations are shown in Figure I I . An
island that split the channel upstream of the highway bridge was completely
74
Scale in Meters
3
17 June 1973
381
Figure II. Aerial photograph showing the two gravel removal locations
at Sinuk River considered separately in the hydro I ogy /hydrau I i cs
analysis.
75
removed (this area is designated Area A). The other location (Area B), in
and adjacent to high-water channels upstream and downstream from the highway
bridge, was separated from the main channel.
At Washington Creek, two grave! removal areas were separated by approxi-
mately I km of undisturbed river (Figure 12). The upper (upstream) and lower
(downstream) gravel removal areas are designated A and B, respectively.
At Oregon Creek the major area of disturbance was immediately upstream
of its confluence with Cripple River (Figure 13, Area A). The unvegetated
gravel bar (Area B) immediately downstream from the highway bridge was also
used for gravel extraction.
At the Aufeis Creek site, the two major gravel removal areas were
separated by over 3 km of r i.ver channel (Figure 14). The upper and lower
sites are designated A and B, respectively.
Gravel removal at the Middle Fork Koyukuk R i ver-Upstream site was
located in a high-water channel and on a point bar (Figure 15). The upper
and lower sites are designated areas A and B, respectively.
76
AREA B
(Lower Gravel
Removal Area)
Scale in Meters
I I 1
17 June 1973
254
Figure 12. Aerial photograph of Washington Creek showing the upper and
lower gravel remove I areas.
77
^:^ii^
^<
OlV-.
^ijjti'^-J^^
o.
I
-AREA A
(U|^r Gravel Removal i
-AREA B
( Lower Grav(
Removal Art
Scale in Meters
I i:
1
^7
18 July 1977
Figure 15. Aerial photograph of Oregon Creek showing the upper and
lower gravel removal areas.
78
Scale in Meters
I 1-
7July1977
305
Figure 14. Aerial photograph of Aufeis Creek showing upper and lower
gravel removal areas.
79
(upper Graver
Removal Area)
AREA B
(Lower Gravel
Removal Area)
Scale in Meters
I I
11july1977
305
Figure 15. Aerial photograph of Middle Fork Koyukuk Ri ver-Upstream
showing upper and lower gravel removal areas.
80
RESULTS AND DISCUSSION
The following subsections present and discuss the results of the data
analysis for the 25 study sites. The five subsections represent five cate-
gories of river characteristics which exhibited changes resulting from
gravel removal operations. These include:
• Channel configuration and process,
• Hydrau I i cs,
• Sedimentation,
• Ice characteristics, and
• Hydrology.
Each subsection includes background information that provides the reader
with a knowledge of selected characteristics of undisturbed rivers and a
description of changes which occurred in these river characteristics as a
result of gravel removal operations.
CHANNEL CONFIGURATION AND PROCESS
The channel configuration of a river is the shape of the river chan-
nel (s) when looking vertically down at the river. Configurations represented
by the 25 study sites include braided, split, meandering, sinuous, and
straight. A sixth configuration, beaded, is unique to northern environments,
but was not investigated during this study; beaded systems are typically
very small and are not likely to contain much gravel. Associated with the
channel configurations are processes of sediment erosion and deposition
which form features characteristic of the configuration. The five channel
configurations that were used to describe the studied sites are described
in subsequent paragraphs.
81
The channel configuration is a function of river stage (water level);
the optimum stage for defining the channel configuration is at low flow.
The channel configuration is also a function of location along the river;
a river could conceivably exhibit all channel configurations between its
headwaters and its mouth. The channel configurations describing the 25
study sites are those only through the reach studied. Configuration combi-
nations, local spatial variations, and variations over time complicate
channel configuration selection.
Undisturbed Condition
Braided Configuration. A braided river typically contains two or more
interconnecting channels separated by unvegetated or sparsely vegetated
gravel bars (Figure 16). Its active floodplain is typically wide and
sparsely vegetated, and contains numerous high-water channels and occasional
vegetated islands. Active channels are typically wide and shallow and carry
large quantities of sediment at high flows. Bars separating the channels are
usually low, gravel surfaced, and easily erodible. The lateral stability of
the channels is quite low; channels shift by bank erosion and/or by channel
diversion into what was previously a high-water channel. The lateral activ-
ity of channels within the active floodplain of a braided river that carries
large quantities of bed load, is expected to be high because gravel deposits
may partially or fully block channels, thereby forcing flow out of the
channel. Maximum depths and corresponding top widths of undisturbed major,
side, and high-water channels, at four braided study sites, are plotted in
F i gure I 7.
Split Configuration. A split channel river has numerous stable islands
which divide the flow into two channels (Figure 18). The banks of the chan-
nels are typically vegetated and stable. The split river floodplain is
typical ly narrow relative to the channel width. There are usual ly no more
than two channels in a given reach and other reaches are single channel. One
of the two channels in a split reach may be dry during periods of low flow.
The channel cross section is narrower and deeper than a braided river with
similar flow characteristics. Maximum depths and corresponding top widths of
82
PLAN VIEW
SECTION A-A
Figure 16. Schematic diagram of the plan view and cross section of a
typical braided river.
83
1 0-
9-
E 6-
I ^-
O. 4-
Ul
a
z
K 2-
z
<
I
O
LEGEND
•Active Channel _
• ■
AHigh-Water Channel %
A ^
■ Side Channel " gA
^ - -A V-^
AA/s
A A * ■ A'
A
A ^ A A '^ b'A A^^gS
OC A A ^Cap^ A A
aa a 4P Ah
aaa a^ a aa a a
A ^ (^ A
A A 0[^ O^ A
■ ■ AAAA A
AA A
■ A A
1 I 1—1 — n — I — TT 1 1 III — I — I — t—
2 3 4 5 6 7 8 9 10 20 30 60 90 120 150 180210
CHANNEL FULL TOP WIDTH (m)
Figure 17. Maximum depths and corresponding top widths of undisturbed
major, side, and high-water channels at four braided study sites.
84
^:^^^^
PLAN VIEW
SECTION A-A
Figure 18. Schematic diagram of the plan view and cross section of a typical
sp li t channe I r i ver .
undisturbed major, side, and high-water channels, at four split channel
study sites, are plotted in Figure 19. Sediment discharge is typically less
than that of a braided river. Bed load is deposited at low flow to form
gravel bars along the sides or in the middle of the channels. These bars are
typically more erodible than the banks. The bars, rather than the banks, are
■
eroded during subsequent floods, resulting in a laterally stable channel.
Meandering Configuration. A meandering river winds back and forth
within the floodplain (Figure 20). The ratio of the channel length to the
downvalley distance is called the sinuosity ratio, or sinuosity. Meandering
rivers have a sinuosity greater than 1.5. Flow is contained in a single
85
o
S .3
3
S
X
< 2
s
<
X
u
LEGEND
•Active Channel
AHigh-Waler Channel ^
•
V,
■ Side Channel
A A'
A •
A
\
A
A
A A
A A A
A
A A
A
-I 1 1 1 — Al I I I 1 1 1 1 1 1 I I
2 i 4 5 6 7 8 9 10 20 30 60 90 120 150 180210
CHANNEL FULL TOP WIDTH (m)
Figure 19. Maximum depths and corresponding top widths of undisturbed major,
side, and high-water channels at four split channel study sites.
86
PLAN VIEW
SECTION A-A
High-Water Channel
Point Bar
Pool
SECTION B-B
Figure 20. Schematic diagram of the plan view and two cross sections of a
typical meandering river.
87
channel, with very few islands. At each bend, the typical cross section
contains a point bar on the inside of the bend and a pool on the outside
of the bend, resulting in a triangular shaped cross section. Point bars
are the primary area of sediment deposition in a meandering river. Between
the bends is a crossing, which typical ly has a wide and shal low cross sec-
tion similar to that of a single braided channel. Since the width of the
channel in the crossing is simi lar to that in the bend, the average veloc-
ity is often greater through the crossing. Maximum depths and corresponding
top widths of undisturbed major, side, and high-water channels at 15 study
sites with meandering, sinuous, and straight configurations are plotted
in Figure 21. A meandering river shifts in the downvalley direction by
1.0
.9
a -^
Z
S 2
=> 1 -
Z
Z
<
X
u
LEGEND
• Active Channel
•
•
AHigh-Waler Channe
•
a.
• • •
■Side Channel
•
A
•
A .•
A
A
A 8
A A
AA
^ \
-.*i-^
• •
AA ^ _%
A (f
A
^^ AA^
.s
A
£■
C, A
D AA
A
A
A imd
T — TTTTTTT ;^ Y
CHANNEL FULL TOP WIDTH (m)
120 1 50 180210
Figure 21. Maximum depths and corresponding top widths of undisturbed major, side,
and high-water channels at 15 study sites with meandering, sinuous, and straight
conf i gurat i ons.
88
a continuous process of erosion and deposition; erosion takes place on
the outside bank, downstream from the midpoint of the meander bend and
deposition occurs on the downstream end of the next point bar downstream.
The rate of downvalley shifting varies from one river to another. The rate
and direction of shifting is much more predictable than the lateral shifting
of braided channels. A result of nonuniform shifting is channel cutoffs.
The floodplain width of a meandering river is often roughly equal
to the meander belt width, which is the average width from the outside
of one meander bend to the outside of the next opposite meander bend (Figure
20). High-water channels on the inside of point bars are typical on meander-
ing rivers. Sediment transport in meandering rivers is typically moderate.
Sinuous Configuration. A sinuous river is similar in plan view to
a meandering river except that its sinuosity is between I.I and 1.5 (Figure
22). In sinuous rivers, point bars are smaller and downvalley shifting
is generally less than that of a comparable-size meandering river. Other
than the greater stability, sinuous rivers are quite similar in form and
hydraulic characteristics to meandering rivers.
Straight Configuration. A straight river flows in a single channel
with a sinuosity less than I.I (Figure 25). The thalweg, or deepest part
of the channel, typically wanders back and forth within the channel with
alternate ground bars formed by sediment deposition opposite those locations
where the thalweg approaches the side of the channel. The alternate bars
may or may not be exposed at low flows. Rivers with a long reach of straight
channel pattern are much less common than rivers with other configurations.
Banks of straight channels are expected to be relatively stable. Sediment
transport is likely to be light to moderate in these systems.
Other Processes. Rivers with any configuration may be found in narrow
mountain valleys and on alluvial fans. Rivers in these locations have dif-
ferent processes of erosion and deposition than those described for the'
typical river with the same configuration. Channel configurations of moun-
tainous rivers are typically not controlled by alluvial processes, but
89
PLAN VIEW
SECTION A-A
Figure 22. Schematic diagram of the plan view and cross section of a typica
sinuous river.
PLAN VIEW
SECTION A-A
Figure 23. Schematic diagram of the plan view and cross section of a typical
stra i gh t r i ver .
90
rather are controlled by geological and morphological features of the val-
ley. Mountainous rivers commonly have very little or no floodplain and
consequently, have small quantities of gravel. Alluvial fans develop when
a steep gradient stream flows onto a substantially less steep terrain; its
sediment transport capacity is significantly reduced causing sediments to be
deposited. This deposition fills the channel, thus forcing the flow to
develop a new channel. This may occur by a gradual migration process or by a
rapid abandonment of one channel to develop a new channel. Such processes
develop a partial cone-shaped deposit of gravels with the apex being near
the end of the steep gradient river val ley (Figure 24). The fan may or may
not be vegetated; denser vegetation implies greater stability.
Changes Due to Gravel Removal
The most common change to the channel configuration resulting from
gravel removal was a shift towards a more braided configuration as indi-
cated, in part, by an increase in the number of channels. A decrease in
lateral stability of the channels was often associated with changes to
more numerous channels. These changes were mos1- prevalent in scraped sites
and most prominent in single channel sites. Gravel removal at many scraped
and pit excavated sites caused a diversion or a high potential for diversion
of flow through the gravel removal site. These observed channel config-
uration changes were given quantitative ratings for comparative purposes
(Table 5). These changes in channel configuration are discussed in more
detail in the following sections.
Braiding Characteristics. The two braiding characteristics considered
were the number and stability of the channels. The most significant changes
in these characteristics resulted from scraping operations in straight, sin-
uous, split, and meandering rivers with lesser changes observed in scraped
braided rivers. This difference was expected, because braided rivers had
such characteristics prior to gravel removal, thus, any change was compara-
tively less significant. The locations of the gravel removal operations that
caused the most significant change in the braiding characteristics were
those which disturbed the bars adjacent to active channels or those which
caused diversion of flow into the material site.
Disturbance of the bars adjacent to active channels can hypotheti-
cal ly reduce the flow within the channel during fl oods because flow spreads
out through the mined area. The reduced flow within the channel would reduce
the ability to transport sediments; sediment deposition within the channel
may result. This deposition would potential ly aggravate the problem by
further reducing the cross-sectional area available to the flow. This pro-
cess can result in widening the channel and the development of mid-channel
bars. Although the potential for this hypothetical process exists, it was
not observed at the study sites.
Braiding characteristics increased at many sites due to the diversion
of flow through the site and the lack of a well-defined channel to confine
the flow. The flow thus spread through the material site and likely did
not have sufficient scour potential to develop a new channel. Thus, numerous
poorly-defined channels flowed through the site.
92
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Table 5. Footnotes
Number of channels ratings:
Number of active channels in the mined area
R Number of active channels upstream from the mined area
10 3 < B^
9 2.5 < B„ £ 3
8 2 < B_, £ 2.5
7 I .5 < B^ < 2
K
6 1 < B < 1.5 or other B values if they are within normal
variation ranges of the river
5 B = I of i f other data indicate no change
K
4 0.67 < B < I or other B values if they are within normal
variation ranges of the river
0-3 Not used
Channel stability ratings:
6-10 Not used
5 No change in channel stability
4 Slight decrease in stability, but within natural stability vari-
ation of the r i ver
3 Moderate decrease in channel stability due to gravel removal
2 Large decrease in channel stability due to gravel removal
I Substantial decrease in channel stability due to gravel removal
0 Very substantial decrease in channel stability due to gravel
remova I
Flow diversion ratings:
10 High potential for river to divert all its flow permanently
through the site
9 Diversion of a significant quantity of flow through the site oc-
curred within several years
8 Moderate potential for river to di vert all of its f I ow permanent I y
through the site
7 Moderate to high potential for some of the river flow to divert
permanently through the site or for flow diversion through the
site during flood events
6 Low potential for river diversion through the site
0-5 Not used
94
Ten sites had more than twice as many channels in the material site
as were upstream. At four of these sites, Washington Creek, Nome River,
Sagavanirktok River, and Middle Fork Koyukuk R i ver-Upstream, the numbers of
channels increased more than three times due to gravel removal operations.
Most sites (7 of 10) with large increases in numbers of channels also had a
very substantial apparent decrease in the lateral stability of those chan-
nels. Lateral stability evaluations were based on subjective judgements of
stability indicators. Lateral stability indicators included the height and
erodibility of the gravel bars at the edge of the active channels, the bed
load transport characteristics evident at the time of the site visit, and
the channel configuration.
The Nome River is an example of a material site with increased braided
characteristics (Figure 25). In this sinuous river, single channel flow
was prevalent prior to the gravel removal operation; exceptions to this
are the split in the channel immediately downstream from the material site
location and two high-water or sma I I active side channels adjacent to the
material site location. Approximately 20 years after the gravel was removed,
the river was flowing in numerous, poorly-defined channels through the
material site. The river apparently diverted into the scraped area soon
after the operation was completed and has attempted to develop a well-
defined channel since it diverted. The state of equilibrium between erosion
and deposition in the Nome River was disturbed by the gravel removal opera-
tion. To restore equilibrium it will probably take several decades from
the time of the initial disturbance.
Flow Diversion Through Site. Gravel removal operations caused flow
diversion or a high potential for flow diversion at 12 of the 25 study
sites. Sites with a high potential for the diversion of all of the flow
permanently through the site included upper Washington Creek, Penny River,
Nome River, upper Aufeis Creek, Skeetercake Creek, lower Middle Fork Koyukuk
Ri ver-Upstream, and Phelan Creek. At most of these sites, all of the flow
had already diverted when the site was visited. All of these sites were
scraped and the lower Middle Fork Koyukuk R i ver-Upstream site was the only
site where a buffer was known to have been used to separate the site from
95
August 1950
July 1977
Scale in Meters
' I
130
Figure 25. Comparative aerial photography of the Nome River showing change in
channel configuration resulting from gravel removal activities.
96
the active channel. The vegetated buffer was approximately 30 m wide and
roughly I m in height; vegetation was missing in and adjacent to a high-
water channel which crossed the buffer. Low (0.3 m) dikes were used to
block off this high-water channel. Flow began to divert through the material
site during the first breakup following the removal of gravel. The buffer
breached, apparently caused by overtopping and subsequent erosion of the top
and downstream face during the flood. At the time of the site visit in 1978,
32 years after the mining took place, 85 percent of the flow was going
through the material site. Scraped sites with a large amount, but not all,
of the flow diverted through the material site by the time the site was
visited included Sinuk River (in-channel site), upper Oregon Creek,
Ugnuravik River, Sagavan i rk tok River, and Kavik River. None of these sites
had a vegetated buffer.
A major consequence of flow diversion through scraped sites was the
development of braiding characteristics, as was discussed in the previous
section. Another consequence was that flow in the former main channel (s)
was eliminated or significantly reduced, thus affecting their hydraulics
and their regime. Flow through scraped sites that had the potential to
aid the replenishment of gravel within the site occurred at Sinuk River
(in-channel site), Washington Creek, Oregon Creek, Ugnuravik River, Aufeis
Creek, Kavik River, and Phelan Creek. At other sites, such as Penny River
and Middle Fork Koyukuk R i ver-Upstream, flow through the site was probably
eroding more sediments than it was depositing.
Most (6 of 7) pit excavated sites had vegetated buffers separating
the material site from the active channel (s). The exception is Ugnuravik
River (Figure 26), which had only a 5- to I 0-m wide gravel bar separating
the material site from the active channel. Therefore, the potential for
flow diversion through this pit is high; flow has diverted through the
site during floods, but the diversion has not yet been permanent.
The two pit excavated sites on the Tanana River were judged to have
moderate to high potential for some of the flow diverted permanently through
the site within several decades following site closure. Both sites had
97
Scale in Meters
I I 1
0 76
7 July 1977
Figure 26. Aerial photograph of the Ugnuravik River pit site showing the in-
sufficient buffer zone.
98
approximately 30 m to 40 m wide vegetated buffers. The main ctiannel of
the Tanana River has the capability to erode through such a buffer in less
than a year. The side channel at the Tanana R i ver-Upstream site (Figure
27) eroded 3 m of the widest part of the buffer between early June and
mid-September of 1978. At either of the Tanana River sites, it could take
several years or several decades for the river to breach the buffer and
flow through the pit, the length of time depending on the lateral direction
of travel of the main channels.
The Prospect Creek and West Fork Tolovana River sites were judged
to have a moderate potential for all of the flow to divert through the
pits. Both sites had vegetated buffers that included portions of abandoned
channels. The upstream end of the abandoned channel, in both cases, causes
a zone of weakness in the buffer. Even though, at both sites, the width
and height of the buffers were likely sufficient to prevent breaching for
several decades, zones of weakness in the buffers at the abandoned channels
and channel aufeis development in the active channel may cause earlier
flow diversion and buffer breaching. At the West Fork Tolovana River site,
the upstream end was diked off and heavily riprapped; however, in spring
of 1979, flow apparently overtopped the dike and scoured the channel lead-
ing into the pit, leaving a large delta gravel deposit in the pit. Flood
stage was probably high because of aufeis development in the channel.
Channel aufeis development also influenced the Prospect Creek site (Figure
28). Aufeis developed in the channel reach upstream from the material site,
reducing the channel capacity during the snowme I t runoff period. The runoff
thus flowed directly down the valley, rather than following the ice-filled
channel. The water flowed through the pit causing headcutting of the up-
stream edge. The edge was subsequently riprapped to prevent further head-
cutting. Doyle and Childers (1976) documented this April 1976 occurrence.
HYDRAULICS
Hydraulics, as used in this investigation, is the study of those param-
eters which influence the mechanics of water flow through the study reach.
The hydraulic parameters which were considered include hydraulic geometry.
99
Scale in Meters
1 1 1
0 168
/;
t .. '
y>
J'
11 July 1977
Figure 27. Aerial photograph of the Tanana R i ver-Upstream site with substan-
tial buffer zone separating the pit from the active side channel.
100
Scale in Meiers
I I I
0 145
11July1977
Figure 28. Aerial photograph of the Prospect Creek pit showing wide buffer
zone separating the pit from the active channel.
101
channel slope, and local flow characteristics at flow obstructions. Hy-
draulic geometry is defined as the geometric and hydraulic variables at a
cross section that vary with changes in discharge. The hydraulic geometry
variables discussed are top width, hydraulic depth, and mean velocity. Chan-
nel slope (gradient) is the reduction of the water surface elevation in the
downstream direction. A general discussion of these hydraulic parameters is
presented in the following subsection, followed by a description of the
effects on these parameters due to gravel removal.
Undisturbed Condition
The hydraulic geometry parameters considered herein are top width,
hydraulic depth, and mean velocity. The top width is the width of the water
surface at a given cross section and a given discharge (Figure 29). The
Water Discharge ( Q )
Mean Velocity (V= x)
Hydraulic Depth (d=:^)
Cross- Sectional Area (A)
Figure 29. Schematic diagram illustrating definitions of channel geometric
and hydraulic variables.
hydraulic depth is defined as the cross-sectional area of flow divided by
the top width. The mean velocity is defined as the ratio of discharge to
cross-sectional area of flow. An estimate of the carrying capacity of the
channel is the conveyance, which is defined by:
102
K = CAR^ (I)
where K = conveyance
C = a coefficient related to ttie roughness of the channel
A = cross sectional area of flow
R = hydraulic radius
X = a fractional exponent
The discharge is directly proportional to the conveyance with the proportion-
ality constant being the energy slope to a fractional power, usually i.
The variation in the hydraulic geometry as a function of discharge
at a river cross section is an indicator of the shape of the channel cross
section. The shape primarily reflects the magnitude of the bank-full dis-
charge which typically has sufficient sediment carrying capacity to shape a
channel and occurs frequently enough to maintain the resulting shape. The
top width, hydraulic depth, and mean velocity at a cross section are often
expressed as a function of discharge in the form of power relations:
W = a Q^ (2)
D = c Q^ (3)
V = k q"^ (4)
where W = top width
D = hydr au I i c depth
V = mean ve I oci ty
Q = di scharge
a , c, k = coef f i c ients
b, f , m = exponents
Typical relations for a hypothetical river are shown in Figure 30. Sub-
stituting the power relations for the hydraulic geometry variables into the
flow continuity equation illustrates the interdependence of the variables:
Q=AV=WDV (5)
= (a Q^) (c Q^ (k q"^)
, > n 'b + f + m) ,^,
= ( a c k ) Q (6)
103
Thus, for continuity.
and
a X c X k =
b + f + m = I
(7)
Discharge
^^^
Note All Scales Are Logarithmic
Figure 30. Average hydraulic geometry of river channels expressed
by relations of width, depth, and velocity to discharge at two
locations along a river (modified from Leopold, Wolman, and Miller
1 964 ) .
if a coefficient or exponent for one hydraulic geometry variable changes due
to the gravel removal operation, at least one of the other variables must
104
also change to maintain continuity of flow. Generally speaking, if a channel
is widened, it often satisfies continuity by becoming shallower. Similarly,
if a channel slope, or gradient, is increased, thus increasing velocity,
continuity is commonly satisfied by a reduction in depth. Exponent values
for selected study sites and other rivers are given in Table 6. The ex-
ponents exhibit a wide range of variability for different rivers; Rundquist
(1975) found that the exponents and the coefficients can be expressed as
functions of the bank-full discharge. The coefficient c and exponent f in
the power relation for hydraulic depth were found in addition to be a func-
tion of the median bed material size. The exponents in the power relations
may change at a given site for discharges above bank-full because of the
typically abrupt change in bank slope at bank-full conditions.
The slope of the water surface profile for a typical river generally
will parallel the bed slope at low f low, often producing a -sequence of r i f-
fles and pools. At flood flows, the pool-riffle sequence is not apparent
in the water surface profile (Figure 31).
Flood Flow Water Surface Profile
Low Flow Water Surface Profile
m^^^}}^=
Bed Profile
Figure 31. Schematic diagram showing change in water surface slope in
response to a change in water discharge.
Naturally occurring flow obstructions in rivers can include vegetation,
rock or snow avalanches, aufeis, and boulders. The effect of an obstruction
on the hydraulics is to cause a local increase in velocity which often
105
Table 6. Values of Exponents for Hydraulic Geometry Power Relations
Undisturbed Disturbed
areas areas
R i ver b f m b f m
Kuparuk River 0.45 0.28 0.29 0.48 0.28 0.24
Sagavanirktok River 0.25 0.40 0.55 0.32 0.42 0.26
Shaviovik River 0.40 0.55 0.27 0.52 0.29 0.19
Middle Fork Koyukuk R i ver-Upstream 0.29 0.44 0.27 0.44 0.55 0.25
Middle Fork Koyukuk River-Downstream 0.54 0.28 0.18 0.57 0.29 0.54
Average values, midwestern
United States'^ 0.26 0.40 0.54
Brandywine Creek, Pennsylvania 0.04 0.41 0.55
Ephemeral streams in semiarid
United States^ 0.29 0.56 0.54
Average of 158 gaging stations
in United States'^ 0.12 0.45 0.45
10 gaging stations on Rhine River 0.13 0.41 0.45
Average of 17 stations in
Southcentral Alaska^ 0.19 0.59 0.42
Average of 50 stations in Upper
Salmon River area, Idaho 0.14 0.40 0.46
' W = a qJ
D = c Q
V= k Q^
Compiled by Leopold, et al. > 1 964 )
'^Emmett (1972)
'^Emmett (1975)
106
results in erosion of the obstruction or bed scour adjacent to the obstruc-
tion (Figure 32). Complete channel relocation is also a potential response
to flow obstructions blocking a high percentage of the channel's cross-
sectional area.
Close Flow Line
Spacing Indicates
High Velocities
Probable Scour
Figure 32. Schematic diagram illustrating the effects of a flow obstruction on
the local hydrau I ics.
Changes Due to Gravel Removal
Substantial changes in hydraulic geometry, slope, and flow obstructions
resulted from gravel removal operations at roughly 60 percent of the sites.
Typical hydraulic geometry changes in the mined area included increased
channel top width, reduced hydraulic depth, reduced mean velocity, and
increased conveyance. Changes in slope due to gravel removal operations took
107
the form of increases through the mined reach resulting from channel cutoffs
and local slope redistributions affecting the pool-riffle sequence. Flow
obstructions in the forms of material stockpiles, diversion dikes, and
overburden piles have the potential for causing local scour, ice jam forma-
tion, and si I tat i on.
Hydraulic Geometry. Gravel removal operations caused changes in the
natural cross-sectional shape of the active channels of approximately half
of the rivers included in the study. The backwater analysis was not complete
enough at some sites to confirm the hydraulic geometry change evaluation.
A comparison of power equation exponents for cross sections in disturbed
and undisturbed areas (Table 6) indicated a varied response to gravel re-
moval. The coefficients in the power equations must also be considered
to understand the effects of gravel removal. For example, at the Middle
Fork Koyukuk River-Downstream site, the top width increased at a slower
rate within the gravel removal area than outside of it. However, the coef-
ficients in the power relations were greater for the disturbed than the
undisturbed cross sections indicating that the top widths were larger at
low flows in the disturbed areas than the undisturbed areas and were similar
in both locations at higher flows. A qualitative evaluation of this effect
can be made by comparing the relative channel widths in the material site
at low flow and flood flow (Channel width and Flooded area. Table 7).
The coefficient in the power equation for the top width was greater
for the disturbed cross section than the undisturbed cross sections at
eight of the sites; this difference resulted from a consistently greater top
width at all discharges considered in the hydraulic analysis. The sites at
which this occurred were Gold Run Creek, Washington Creek, Nome River,
Aufeis Creek, Skeetercake Creek, Sagavan irktok River, and both sites on the
Middle Fork Koyukuk River. At Sinuk River the exponent of the power relation
for the top width was observed to be greater at the disturbed cross section
than at the undisturbed cross section. This difference indicates that the
gravel removal area had smaller top widths at low flows, but larger top
width at high flows, than the undisturbed cross section.
108
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Table 7. Footnotes
Width and area ratings:
_ Parameter in the mined area
R Parameter upstream from the mined area
where the parameter is:
• top width of the channel Is) during the survey period for Channel Width
• top width of the channel (si during floods of approximately Dank-full
flood magnitude for Flooded Area
• area of ponded water, excluding pits, for Ponded Area.
* Wr,
2.5 < Wpj < 3
< Wp < 2.5
I . 5 < Wp < 2
6 I ^ *□ 1 '-5 or ether W values if they are within the natural
range of variation of the river
5 W • I or i f other data indicates no change
4 0.67 1 W < I or other W values if they are within the natural
range of variation of the river
5 0.50 ^ Wr '^ 0.67
0-2 Not used
Overal I slope ratings:
_ Length of disturped reach after gravel removal
R ~ Length of disturbed reach before gravel removal
10
9
8
7
6
5
/L
R
.2 < S„
Lr ^°-^'
0.71 < L^
0.77
I .3 or 0.77 < L„ < 0.83
K — — R
I < S„ < I .2 or 0.83 < L„ < 0.91
.0 < S^ < I.I
or 0.91 < Lp
.0
Sr^Lr
I or i f other data indicate no change
0-4 Not used
"Local slope redistribution ratings:
10 Very steep slope followed by a very long pool
9 Steep slope followed by a long pool
8 Moderate slope followed by slightly longer than average pool
7 Slope and pool length slightly more than that in the undisturbed
areas
6 Some local slope redistribution detected or likely to have occurred
but not likely that of the natural river
5 No local slope redistribution
0-4 Not used
Flow obstruction ratings:
10 Obstructions in an active low-water channel such that flow is
di verted
9 Obstructions adjacent to an active low-water channel
8 Obstructions in or adjacent to high-water channels
7 Obstructions in the floodplain but away from any developed channels
6 Small obstructions not much different in size from those occurring
naturally in the floodplain
5 No obstruct ions
0-4 Not used
110
Associated with the trend towards larger top widths in the gravel
removal areas, the hydraulic depth in seven of these areas decreased. Sites
with smaller hydraulic depths, in the mined area, for all discharges in-
cluded Washington Creek, Nome River, Aufeis Creek, Skeetercake Creek,
Sagavan irktok River, and both sites on the Middle Fork Koyukuk River.
The mean velocity was consistently less at the disturbed cross section
than at the undisturbed cross section at nine of the sites for the range of
discharges included in the backwater analysis. These sites included Gold Run
Creek, Washington Creek, Ugnuravik River, Aufeis Creek, Skeetercake Creek,
Sagavan irktok River, Dietrich River-Downstream, and both of the Middle Fork
Koyukuk River sites. At two sites, the rate of increase of velocity with
discharge was different in the disturbed area than in the undisturbed area.
At Sinuk River, the velocity increased at a lesser rate at the disturbed
cross section than at the undisturbed cross section. At Middle Fork Koyukuk
River-Downstream, the reverse was found.
The conveyance, or carrying capacity of the channel, was consistently
greater in the gravel removal area of eight sites compared with conveyances
at undisturbed cross sections. These sites were Gold Run Creek, Sinuk River,
Washington Creek, Aufeis Creek, Sagavan i rktok River, Kavik River, Dietrich
River-Downstream, and Middle Fork Koyukuk R i ver-Upstream. The Sinuk River
had a larger exponent or, equ i va I ent I y , a more rapid increase in conveyance
with discharge than cross sections which were not disturbed by the gravel
removal operation. Conversely, the conveyance at the downstream site on
the Middle Fork Koyukuk River increased with discharge at a slower rate
than did the conveyance of the undisturbed cross sections.
Significant changes in hydraulic geometry were observed primarily
at sites which were scraped, although not all scraped sites showed a signif-
icant increase. Most of the significant changes were observed at meandering,
sinuous, and straight rivers. Although no single gravel removal location
caused a significantly greater change in hydraulic geometry than others,
most of the sites that had significant change were those sites that were
excavated by scraping in-channel and immediately adjacent-to-channe I loca-
t ions.
I N
The area of ponded water, which includes those low-lying areas which
accumulate water but are not effective in the conveyance of flow, was in-
creased at roughly half of the study sites. This ponding indicated that
the site was not smoothed during restoration, was excavated too deeply,
or was not properly drained. Table 7 lists the relative effect of this
parameter at the 25 study sites. The impact of the ponding to the hydraulics
of the systems was not great. However, it was a concern to aesthetics and
fish entrapment evaluations.
Channel Slope. Channel slope changes took the form of an overall in-
crease in slope or a local redistribution of slope. An overal I increase
in slope was commonly due to the formation of a meander cutoff. A redistri-
bution of slope without changing the overall slope occurred when the slope
was increased leading into the gravel removal area and decreased through
the gravel removal area. Table 7 indicates those sites which had slope
changes.
Study sites exhibiting an overal I increase in slope due to gravel
removal were generally in small, nonbraided river systems that were exca-
vated by scraping techniques. The location of gravel removal was an impor-
tant factor affecting the overall slope of the system. Sites such as upper
Washington Creek, Penny River, Skeetercake Creek, and lower Middle Fork
Koyukuk R i ver-Upstream, that were excavated on the inside of bends, mean-
ders, and islands most significantly affected the overall slope of the river
system. This influence was expected because significant increases in slope
are most likely to result from the development of a meander cutoff (reducing
channel length and increasing slope).
The Penny River gravel removal operation caused a significant increase
in overall slope (Figure 33). The photograph of the site after the gravel
was removed shows that the main channel flows in a relatively straight
course along the inside of two broad meanders that were cut off in the
excavation process. The channel length was reduced by a factor of two in the
process, equivalent to doubling the overall slope through that reach.
Doubling the slope has the effect of increasing the mean velocity by roughly
40 percent.
12
Scale in Meters
I I I
August 1950
July 1977
191
Figure 33. Comparative aerial photography of the Penny River showing change in
hydraulic characteristics resulting from gravel removal activities.
I 13
Gravel removal from active and high-water channels generally caused
local slope redistribution. Removing gravel from bars and banks immediately
adjacent to channels also appeared to cause a local redistribution of the
water surface slope. An example of a local slope redistribution, which is
similar to the situation at the Dietrich River-Downstream site, is schemat-
ically illustrated in Figure 34.
loodplain
•Water Surface
, Bed
— Floodplain
Water Surface
Bed
After Gravel Removal
Figure 34. Schematic diagram illustrating an example of a change In local
water surface slope that resulted from an in-channel gravel removal
operat i on.
Flow Obstructions. Flow obstructions in the form of material stock-
piles, diversion dikes, and overburden piles had a larger potential for
hydraulic disturbance on small rivers than those on medium and large rivers.
This larger potential exists because the flow obstructions would have to be
placed closer to the active channel due to the typically smaller floodplain
width. There were no significant hydraulic impacts observed due to flow
14
obstructions, but the potential exists for bed scour at the base of the
obstruction, erosion of the obstruction, and ice jamming at the obstruction.
Erosion of a dike at Skeetercake Creek increased siltation as discussed in
the following section.
SEDIMENTATION
Sedimentation includes the processes of erosion, transportation, and
deposition of sediment. These are complex processes related to sediment
and water flow properties. Attempts to quantify these processes provide,
at best, estimates of the quantity. A very brief discussion of sediment
size distribution, channel erosion, and sediment transport are given in
the following section. Changes to these sedimentation characteristics due
to gravel removal are then briefly discussed.
Undisturbed Condition
Sediment Size Distribution. An important factor influencing most sedi-
mentation problems is the size distribution of the sediments. The typical
descriptors of the size distribution of sediment are the median diameter and
graduation coefficient of the material. Natural sediment distribution tends
to be log-normal, which is a two parameter distribution. The median diameter
of a distribution has 50 percent of the material sma I ler by weight and 50
percent of the material larger by weight. The second parameter, the grada-
tion coefficient, gives the slope of the straight line resulting from plot-
ting the distribution on log-probability paper. It is defined as
a =
1
r^5o . vi
2
.^16 ^^50]
(9)
where a is the gradation coefficient and D is the particle diameter for
which X percent of the material is finer. The gradation coefficient is
related to the standard deviation of the material. The material can be
described as uniform if its gradation is less than 1.3 or graded if its
gradation Is greater than 1.5.
115
The median sedimenl" size in the floodplain generally decreases in
the downstream direction along a river. Thus, the median size may be cobbles
in the headwaters and fine gravel near the mouth. However, the median size
can significantly vary around this general average within a sma I I area
at a specified point along the river. This variation is a consequence of
the variation in hydraulic forces from one point in the floodplain to an-
other.
Channel Erosion. Channel erosion in rivers is generally considered
to be either local erosion (scour) or degradation. Both result from an
increase in the sediment transport capacity, or a decrease in the sedi-
ment load entering the area, or both.
Local scour is most commonly a result of local increases in velocity
due to flow obstructions or contractions. The increased velocity increases
sediment transport capacity. Degradation can result if the channel bed
is steepened in a short reach by, for example, a meander cutoff. The sedi-
ment transport capacity would be increased through this reach causing ero-
sion and a general upstream progression of the steepened slope (Figure 35).
Upstream Progression of Steepened Slope
Steepened Slope
Figure 35. Schematic diagram showing degradation process.
The progressive erosion continues upstream until equilibrium is reached. In
theory, equilibrium is reached when the slope is equal to the slope prior to
the occurrence of the cutoff, which would require the steepened slope to
migrate to the headwaters. In practice, the steepened slope is reduced
116
during its upstream migration and gradually reaches an equilibrium con-
dition. However, the degradation may extend over a long reach before equili-
brium is ach i eved.
Sediment Transport. Sediment transport is the movement of sediments
past a specific cross section of a river. The sediment may be transported
as suspended load or bed load. Suspended load is sediment that is trans-
ported long distances suspended in the water column. Bed load is sediment
that is transported by saltation (bouncing), or by rolling or sliding along
the river bed. The sediment size distinction between bed load and suspended
load varies with variations in discharge. At low flows, assuming the sedi-
ments were available, silts and clays may be transported in suspension
and sands and gravels transported as bed load. During floods, suspended
load may include clays, silts, sands, and gravels, with cobbles and boulders
transported as bed load. Often, the suspended load is assumed to include
clays, silts, and sands and the bed load includes gravels, cobbles, and
bou I ders.
Changes Due to Gravel Removal
Very little sediment data were collected at the study sites. Direct
measurements or observations of bed or suspended transport were not made
because site visits were scheduled during periods of low flow when the sites
would be most workable. Because the sedimentation characteristics prior to
gravel removal were also unknown, the upstream cross section was usually
used as the undisturbed cross section. The effects of gravel removal were
evaluated by comparing sedimentation features in the gravel removal area to
those in the undisturbed upstream area.
At six sites, a decrease in the median size of the surface layer,
or armor layer, was observed in the mined area as compared with the undis-
turbed area. Similarly, an increase or decrease was observed in the median
diameter of the material underlying the armor layer at eight sites. In many
cases it was difficult to evaluate whether the variation in median diameter
was a result of the gravel removal operation or simply a result of the
I 17
natural variation of the median diameter at a site. Degradation was also ob-
served at a few sites although at other sites only causative evidence was
available to indicate that this process can occur. Sediment transport
changes were suggested at several sites where there were observations of
bedforms in or downstream from the gravel removal area, observations of
changes in the bed material size, computations of changes in shear stress,
or observations of sediment sources which remained from the gravel removal
operation. The effects of gravel removal activity on these sedimentation
characteristics were evaluated and given quantitative ratings for com-
parative purposes (Table 8).
Sediment Size Distribution. The most common significant change in
sediment size distribution resulting from gravel removal was a decrease
in the size caused by fine material deposition in the material site. This
change was reflected in the surface material at six sites and the subsurface
material at six sites. Oregon Creek, Penny River, and Ugnuravik River had
significant changes in both surface and subsurface material sizes. At Sinuk
River, fine and medium sized gravels were nearly missing from the subsurface
samples in the material site, causing an increase in the median size. The
explanation for this is unknown. At Washington Creek, the subsurface ma-
terial size was larger in the material site even though fine material depo-
sition in the site reduced the median size of the armor layer.
A pattern of correlation was not evident between increases or decreases
in armor layer median diameter resulting from gravel removal and physical
site or gravel removal area characteristics. One reason for this lack of
correlation is that armor layer development is a complex function of several
interrelated factors including degree of development of undisturbed armor
layer, flooding history since gravel was removed, and flow characteristics
in the gravel removal area. If the undisturbed size distribution of the
armor layer was not significantly different from that of the material under-
lying it, the relative change due to gravel removal would have been less and
the time required for recovery to the undisturbed condition would also be
less. The time for recovery is also a function of the floods during the
recovery period; one large recurrence interval flood may be sufficient to
118
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I 19
Table 8. Footnotes
D
_ Wedian size in the gravel removal area
R ~ median size upstream from ttie gravel removal area
10 10 <_ 0- (due to gravel removal activity)
9 2 < D < 10 (due to gravel removal activity)
8 1.2 < 0 < 2 (due to gravel removal activity)
7 1.2 £ D (cause uncertain!
6 I < Op < 1.2
5 D^: I
4 0.8 < Dp £ I
3 D„ £ 0.8 (cause uncertain)
2 0.5 < 0 < 0.8 (due to gravel removal activity)
I 0.2 < D < 0.5 (due to gravel removal activity)
0 D < 0.2 (due to gravel removal activity
Channel degradation ratings:
10 Very substantial degradation upstream of ttie disturbed area
9 Substantial degradation upstream of the disturbed area
8 Large amount of degradation upstream of the disturbed area
7 A noticeable amount of degradation upstream of the disturbed area,
but not unl ilie degradation which could occur naturally
6 Slight degradation upstream of disturbed area observed or implied;
may not be a result of gravel removal
5 No degradation, observed or implied by the data
0-4 Not used
Bed load ratings:
10 Substantial increase in bed load by erosion In the gravel removal
area
9 Large increase in bed load oy erosion in the gravel removal area
e Increase in bed load by erosion in the gravel removal area
7 Bed load increase due to gravel removal activity expected but not
verified by direct evidence
6 Slight bed load increase potentially due to gravel rerroval activity
5 No bed load change evident
4 Slight bed load decrease by deposition in the gravel removal area
3 Moderate bed load decrease by deposition in the gravel retroval area
0-2 Not used
Suspended load ratings:
9-10 Not Lsed
8 Large temporary and/or moderate long term increase in suspended
load
7 Temporary increase in suspended load as a result of disturbance
of armor coat
6 Potential slight increase In suspended lead resulting from gravel
r emova I act I v i ty
5 No apparent change in suspenreO iced
4 Potential slight decrease In suspended lead resulting fronr deposition
3 tfoderate amount of deposition of suspended ir.atcrlal
C-2 Not used
120
develop an armor layer comparable to that in ttie undisturbed area. Ttie
development of an armor layer in the gravel removal area is also greatly
dependent on the location of the area relative to the active channel and the
resulting flow characteristics through the site. The location and extent
of gravel removal may be such that an armor layer may not develop until
the area fills in sufficiently to have appropriate hydraulic character-
istics for armor layer development.
Channel Erosion. Channel erosion in the form of local scour was not
observed at any of the study sites. The potential exists for local scour to
develop as a result of flow obstructions in the form of material stockpiles,
overburden piles, and diversion dikes. This potential was discussed in the
previous section discussing hydraulics.
Channel degradation was observed at four sites and may have been devel-
oping at three other sites. At Washington and McManus Creeks, obvious degra-
dation had occurred upstream from the site in the main channel. At the two
Dietrich River sites, degradation was occurring in high-water channels; at
the downstream site, one of the high-water channels developed into an active
side channel after work completion. Channel degradation resulting from
gravel removal activity has been documented elsewhere (Woodward-Clyde
Consultants 1976b, Li and Simons 1979). Li and Simons (1979) suggest that
the installation of check dams can restrict upstream degradation. Sheridan
(1976) discusses in-channel gravel removal, noting that the pits filled in
with sediment; a similar situation occurred on Sinuk River with no apparent
degr adat i on .
Sediment Transport. Changes in sediment transport due to gravel removal
were difficult to evaluate. The ratings given in Table 8 are thus highly
subjective. A few possible changes which were suggested by the sedimentary
features in and around the material sites are discussed below. It is likely
that most scraped sites exhibited an increase in suspended load during the
first flood event and possibly during one or two subsequent events as the
material in the gravel removal area was washed clean of the fine grain
sizes. This increase was thus likely a temporary increase common at most
121
scraped sites. Long-term increases in suspended load were implied at sites
with disturbed areas which contributed fine materials to the flow. Examples
of such long-term increases were the access road degradation at Ugnuravik
River (Figure 36), the diversion dam at Skeetercake Creek (Figure 37), and
several sites with overburden piles or berms containing fine-grained ma-
terials. Similar increases in suspended load could occur from accelerated
bank erosion at the site. Deposition of fine-grained sediments in several of
the gravel removal areas was also observed. Sites with changes in suspended
load showed no pattern with the physical site or gravel removal area charac-
teristics.
Apparent changes in bed load were observed at some sites in the form of
gravel dunes or loose gravel deposits in and downstream from the gravel
removal area. When these deposits occur in the gravel removal area, they
could indicate the inability of the flow through the area to carry the
sediment load delivered to it or generated within it. Deposition occurring
downstream from the gravel removal area would imply that the flow through
the area is sufficient to erode the loose gravel from the gravel removal
area. It is possible that when these gravels reach the main channel they are
transported in the form of another bed form or possibly in suspension. Bed
load changes occurred most often at scraped sites in active and high-water
channels, and in locations immediately adjacent to such channels.
ICE CHARACTERISTICS
Undisturbed Condition
Ice jamming can occur during breakup when ice floes moving down the
river are blocked, thereby blocking subsequent ice floes and eventually
creating a surface dam to the flow of ice. Ice jams can cause scour due to
increased velocity beneath the ice dam; they can also cause the water level
to rise, resulting in increased flooding. Ice jams are normally caused by a
constriction in the channel width or depth, a reduction in flow velocity, or
manmade structures in the floodplain.
122
Figure 36. Upstream view of thermal and fluvial erosion in
the access road at Ugnuravik River, acting as a long-term
sediment source to the river.
■^i
*^«>-..-
iL
Figure 37. View of erosion of a diversion dam which acts as
a long-term sediment source to Skeetercake Creek. Dunes in
foreground are atypical of the undisturbed river.
123
Aufeis is defined as areas of ice which have developed by a sequence of
events of overflowing water on top of the previous ice surface. The general
mechanism for the growth of aufeis involves an increase in the hydrostatic
pressure due to a reduced flow area; when the pressure exceeds the elevation
of the ice surface, overflow onto this surface results and subsequently
freezes. The overflow causes the pressure to decrease and ice surface ele-
vation to increase. This sequence continues to repeat until the source water
cannot produce sufficient pressure to exceed the elevation of the ice sur-
face. Three requirements for the formation of aufeis are given by Carey
(1973); (I) significant ground water or under-ice flow, (2) growth of ice to
the channel bed or near the bed, and (3) subsurface constriction such as
bedrock, less pervious soil, or permafrost.
Changes Due to Gravel Removal
An organized program of winter and spring observations of aufeis and
breakup were not included in this study. Therefore, much of the following
discussion is based on observations of auf e is and ice jamming potential,
rather than of actual aufeis and ice jams. However, at two sites, Washington
Creek (Figure 38) and Oregon Creek, large areas of aufe is were observed in
early June. Incidental winter observations at a few other sites documented
the existence of aufeis.
Ice jams could be caused by several aspects of floodplain gravel re-
moval. In rivers which are increased in width and depth by the gravel re-
moval, such as by in-channel mining, the velocity would decrease causing the
ice floes to gather. At the downstream end of the gravel removal area these
floes could jam where the channels constrict back to the natural width. This
ice jam could cause flooding in and upstream from the gravel removal area
and possible bed scour beneath the ice jam. River channels which are widened
causing shallower depths, such as by removing bars adjacent to the channel,
could cause ice jamming by grounding the ice floes. Another potential mechan-
ism for ice jam formation resulting from a gravel removal operation is the
blocking of ice floes by flow obstructions in the form of overburden piles,
stockpiles, or dikes.
124
Figure 58. Large area of aufei s at the upper gravel removal
area at Washington Creek as it appeared in early June.
In evaluating the potential for aufeis development at each of the
study sites, it was assumed that wide, shallow channels were more likely to
develop aufeis than narrow, deep channels. This assumption is probably valid
because shallow channels are more likely to freeze to their bed and to have
a shallow talik (unfrozen zone) than deep channels carrying equivalent flow.
The results of this evaluation of aufeis potential are listed in Table 9,
along with the identification of those rivers with aufe is activity or po-
tential aufeis activity prior to the gravel removal operation.
Most of the observations of increases or potential increases in aufe i s
activity were associated with mining activities in straight and sinuous
rivers, although some activities in braided, split, and meandering rivers
also caused potential increases. Increases in aufeis activity were associ-
ated with scraping operations. Increased aufeis activity or potential aufeis
activity often occurred at those sites where the gravel removal operation
was located in active or high-water channels and in locations immediately
125
Table 9. Quantification Ratings of Change in Aufe i s Potential that Resulted
from the Gravel Removal Operation at Each of the 25 Sites
Gravel
removal Au f e i s
River area potential
Gold Run Creek 6
Sinuk River A 5
B 6
Washington Creek A 10
B 6
Oregon Creek A 10
B 5
Penny River 6
Nome R i ver 6
Ugnuravik River 6jj
Aufeis Creek A 6.
Kuparuk River °
Skeetercake Creek 5
Sagavan irktok River 6^
Ivishak River 6
Shaviovik River 5^^
Kavik River 6jj
Dietrich Ri ver-Upstream 7
Dietrich River-Downstream 5
Middle Fork Koyukuk Ri ver-Upstream A 5
Middle Fork Koyukuk River-Downstream 8
J im Ri ver ^^
Prospect Creek 5
West Fork Tolovana River 5
McManus Creek 6
Tanana River-Downstream 5
Tanana Ri ver-Upstream 5
Phelan Creek 5
Aufe is potential ratings:
10 Large aufeis development observed in the disturbed area where no aufeis
was previously recorded
9 Moderate sized aufeis development observed in the disturbed area where
no aufeis was previously recorded
8 SmaTT aufe is development observed or a strong potential for aufe is occur-
rence is inferred
7 Relocation of an existing aufe i s area by gravel removal activity
6 Potential increase in aufeis activity resulting from gravel removal
act i v i t y
5 No change in aufe is characteristics
0-4 Not used
''Rivers with a high potential tor icing activity prior to the gravel removal
operat ion.
126
adjacent to the channels. Such locations, when excavated for gravel, tend to
increase channel width, decrease depth, and allow for freezing down to the
channel bed.
As noted earlier, large areas of aufeis were observed in the Washington
Creek and Oregon Creek study sites. Both of these sites had been extensively
scraped and that caused numerous channels to form and loss of surface flow
to intergravel flow because of loosely compacted gravels. The aufeis may be
retarding the recovery of the surface flow by protecting the loose gravels
from the flood flows during the snowmelt runoff period. At both sites, the
channels flowing during the survey were not flowing where the channel had
previously been; it is thus likely that the talik was not as deep beneath
the newly formed channels, thereby providing the auf e i s requirement of a
subsurface constriction. The shallow channels would likely freeze to the
bed, thereby satisfying another requirement for aufeis formation. The third
requirement, a water source, was already available. Thus, at these two
sites the gravel removal operation changed the channel location and cross
section sufficiently to provide two of the three requirements for aufeis
format i on .
HYDROLOGY
Hydrology is the study of the origin, distribution, and properties
of water during the time it is at or near the earth's surface. Of concern
in this section is the distribution of the water. More specif ical ly, this
section discusses briefly the quantity of water that can be expected at
the 25 material sites during low flow and flood flow conditions and poten-
tial effects on the quantity due to the removal of gravel.
Undisturbed Condition
The mean annual flow of a river at a specific point is, as the term
implies, the mean flow during any 12 month period. It is an indication
of total annual runoff and may also be used as an approximation of the
typical low summer flow. Estimates of mean annual flow for the 25 study
127
sites are listed in Table 10. They range from 0.09 m /s at McManus Creek
to 540 m /s at Tanana River-Downstream.
Flood frequency curves show the expected frequency of occurrence of
different magnitude floods at a specific point on a river. The frequency of
occurrence is commonly referred to by the recurrence interval of the flood,
which is the average number of years between floods of that magnitude. The
reciprocal of the recurrence interval is the probability of occurrence of a
given magnitude flood in any year. Flood frequency curves were developed for
each of the study sites. Discharge values corresponding to selected fre-
quencies of occurrence are shown in Table II.
Changes Due to Gravel Mining
Hydrologic characteristics are, to a large extent, governed by basin-
wide parameters such as climate and geology. Gravel removal operations did
not have a significant effect on these characteristics. However, local
changes in the ratio between surface flow and subsurface flow occurred at
several sites. The local changes were not measured; quantitative ratings
shown in Table 12 were assigned based on a subjective evaluation. A local
reduction in mean annual flow occurred at the upper Washington Creek and
upper Aufeis Creek sites as a result of a loss of surface flow to inter-
gravel flow. At Washington Creek, the flow entered the gravel removal area
and spread out through loose, uncompacted gravel; a large percentage reduc-
tion in surface flow resulted at low flows. This intergravel flow component
was sti I I evident in the site 13 years after the site was worked. The rela-
tive effect of the loss of surface flow during flood events was likely
minimal. At Aufeis Creek, surface flow appeared to cease entirely for a
period of 2 years, although continuous surveillance was not available to
verify this. Thus, the mean annual flow of Aufeis Creek in this local region
was reduced to near zero for 2 years. The effect on flood flows was unknown.
Two other sites, the upper Oregon Creek and Penny River sites, had
a potential for a similar, but not as extensive, decrease of surface flow
lost to intergravel flow. No observations or measurements were available
128
Table 10. Mean Annual Flow Estimates at Each of the 25 Study Sites
River
Gold Run Creek
S i nuk R i ver
Washington Creek
Oregon Creek
Penny River
Nome River
Ugnuravik River
Aufeis Creek
Kuparuk River
Skeetercake Creek
Sagavanirktok River
I V i shak R i ver
Shavi ov i k R i ver
Kavik River
Dietrich Ri ver-Upstream
Dietrich River-Downstream
Middle Fork Koyukuk Ri ver-Upstream
Middle Fork Koyukuk River-Downstream
J im R i ver
Prospect Creek
West Fork Tolovana River
McManus Creek
Tanana River-Downstream
Tanana Ri ver-Upstream
Phelan Creek
Unit mean
annua 1 f 1 ow
3 2
(m /s/km )
Mean annual
(m^/s)
f low
0.013
0.9
0,033
18.0
0.018
0.5
0.023
0.7
0.023
1 .4
0.033
4.3
0.0023
0.6
0.0044
1 . 1
0.0045
38
0.0035
0.3
0.0083
39
0.0066
24
0.0040
1 .6
0.0062
5.5
0.006
3, 1
0.006
4.0
0.0054
13
0.0054
22
0.010
7. 1
0.010
2.6
0.0062
4.7
0.0062
0.09
0.012
559
0.012
468
0.063
5.2
129
Table II. Calculated Discharges in m /s Corresponding to Selected
Recurrence Intervals for Each of the 25 Study Sites
Recurrence interval
( years )
River
1 .25
2
5
10
25
50
100
Gold Run Creek
1 1 .2
19.2
32. 1
42.8
53.6
70.2
91 .0
S i nuk R i ver
1 13
171
256
323
391
481
589
Washington Creek
2.58
5.63
10.7
16.6
28. 1
39.5
54.9
Oregon Creek
6.21
1 1 . 1
19.4
26.3
33.5
44.8
59.3
Penny River
18.2
23.7
31.7
37.0
43.7
50.2
57.0
Nome River
32.4
53.3
86.3
1 14
142
182
232
Ugnuravik River
31.4
46. 1
71 .5
92. 1
121
149
180
Auf ei s Creek
39.2
56.8
89.3
1 16
160
196
235
Kuparuk River
905
1355
2165
2848
3906
4840
5912
Skeetercake Creek
10.6
16.7
28.4
38.4
54.6
69.8
87.0
Sagavan irktok River
376
462
592
665
785
863
970
1 V i shak R i ver
267
333
432
489
579
641
726
Shaviovik River
35.8
59.6
98. 1
130
164
212
272
Kavik River
108
171
27 1
353
444
559
701
Dietrich River-Upsti
-eam
35.6
58.6
102
140
195
253
322
Dietrich River-Downstream
46.9
75.9
131
178
247
318
402
Middle Fork Koyukuk
R-
-US
126
189
302
396
534
661
808
Middle Fork Koyukuk
R-
-DS
190
276
428
552
736
896
1079
J im Ri ver
101
125
156
178
204
228
25 1
Prospect Creek
33.3
43.6
57.6
67.3
78.5
90.4
102
West Fork Tolovana
R i ver
63.9
89.2
130
159
203
242
282
McManus Creek
1 .65
3.32
7.48
12.0
20.6
29.8
42. 1
Tanana River-Downst
ream
1562
1752
1992
2120
2356
2460
26 19
Tanana R i ver-Upstream
1341
1518
1738
1857
2069
2169
23 18
Phelan Creek
49.3
65.3
92.8
1 14
146
171
197
130
Table 12. Quantification Ratings of Change in Quantity of
Intergravel Flow Resulting from the Gravel Removal
Operation at Each of the 25 Sites
River Gravel removal area Intergravel flow
Go I d Run Creek 5
S i nuk R i ver A 5
B 5
Washington Creek A 9
B 5
Oregon Creek A 7
B 5
Penny River 7
Nome River 5
Ugnuravik River 5
Aufeis Creek A 10
B 5
Kuparuk River 5
Skeetercake Creek 5
Sagavan ir k tok River 5
I V i shak R i ver 5
Shaviovik River 5
Kavik River 5
Dietrich R i ver-Upstream 3
Dietrich River-Downstream 5
Middle Fork Koyukuk R i ver-Upstream A 5
B 5
Middle Fork Koyukuk River-Downstream 5
Jim R i ver 5
Prospect Creek 5
West Fork Tolovana River 5
McManus Creek 5
Tanana River-Downstream 4
Tanana R i ver-Upstream 4
Phe I an Creek 5
a
ntergravel flow ratings:
10 All surface flow converted to intergravel flow for one summer or more
9 Substantial long-term loss of surface flow to intergravel flow
8 Moderate long-term loss of surface flow to intergravel flow
7 Implied long-term loss of surface flow to intergravel flow
6 Small quantities of surface flow lost to intergravel flow
5 No apparent change
4 Implied increase of surface flow and decrease of intergravel flow
3 Known increase of surface flow and decrease of intergravel flow
0-2 Not used
131
to estimate the magnitude of the decrease. The location of the gravel re-
moval area may provide an explanation for the significant intergravel flow
at Washington Creek and Aufeis Creek. At these two sites the scraping occur-
red near the downstream end of a sharp meander bend (Figure 39). It appeared
that the scraping in this location caused most of the flow to leave the
confinement of the channel. The lack of a well defined channel caused the
flow to spread over the gravels in the material site and deposit the sedi-
ment load that it was carrying. These deposits were quite loose and un-
stable, and thus were very conducive to intergravel flow. Other sites having
a similar specific location of scraping were slightly different in configur-
ation from that shown in Figure 39; either the bend upstream from the
scraped area at these sites was not as sharp or the scraping occurred fur-
ther downstream on the bend, thus allowing some of the flow and likely
much of the bed load to be retained in the original channel.
Three possible explanations for the continued loss of surface flow
at Washington Creek are (I) that the suspended load is not sufficient to
fill the openings in the gravel, (2) the presence of aufeis in the site
protects the gravels from the significant snowmelt floods, and 13) water
freezes in the gravel, expanding and separating the gravels in the process.
Pit sites, such as Dietrich Ri ver-Upstream and the two Tanana River
sites, had a potential to locally increase the mean annual flow as a result
of intercepting intergravel flow and allowing it to surface at the pit.
However, the percentage increase in the mean annual flow at these sites
is probably quite small.
132
Sr«!*'Active Channel Prior
; to Gravel Removal
High-Water Channel Prior
to Gravei Removal
Scale in Molers
17Junlf73
7 July 1977
Figure 39. Aerial photographs of Washington Creek (top) and Aufeis Creek
(bottom) showing material site locations and approximate channel locations
before the disturbance.
t35
SUMMARY AND CONCLUSIONS
Various physical characteristics of arctic and subarctic rivers were
affected by gravel removal operations. These characteristics were divided
into five categories:
1. Channel configuration and process,
2. Hydrau I ics ,
3. Sedi mentat i on ,
4. Ice characteristics, and
5. Hydrology.
One or more characteristics from these categories were observed to have
changed as a result of removing gravel from the 25 floodplain study sites.
CHANNEL CONFIGURATION AND PROCESS
Channel configuration and process characteristics that changed as
a result of gravel removal operations included braiding characteristics,
such as increase in the number of channels and decrease in lateral stabil-
ity of the channels, and the potential for diversion of flow through the
gravel removal area. The greatest changes in braiding characteristics
occurred at 10 study sites and resulted from gravel removal operations
that disturbed the bars adjacent to active channels or that diverted flow
through the material site. Flow diversion through the mined site resulted
from having insufficient buffers or no buffers at all. Gravel removal
operations caused flow diversion or a high potential for flow diversion
at 12 of the 25 study sites.
134
HYDRAUL ICS
Hydraulic characteristics exhibiting changes as a result of gravel
removal operations included the hydraulic geometry (including width, depth,
velocity, and conveyance), overall channel slope, local slope redistri-
bution, flow obstructions, and area of ponded water. Increases in channel
width, conveyance, overall slope, flow obstructions, and ponded water
were typical responses to gravel removal, as were decreases in channel
depth and velocity. One or more of these effects from gravel removal were
observed at al I of the sites except those pit excavated sites that were
separated from the active channels by a buffer. Sma I I river systems typ-
ical ly had sma I ler f loodplains which forced the gravel removal operation
closer to active or high-water channels, causing hydraulic changes.
SEDIMENTATION
Sedimentation characteristics which appeared to have changed as a
result of gravel removal operations included armor layer and subsurface
material site distributions, channel degradation, and suspended and bed
loads. The most common significant change in sediment size distribution
resulting from gravel removal was a decrease in the size caused by fine
material deposition in the material site. This change was reflected in
the surface material at six sites and the subsurface material at six sites,
three of which were different from those with surface material changes.
Channel degradation was observed at four sites and may have been develop-
ing at three other sites. Changes in sediment transport due to gravel
removal apparently took the form of increases as we I I as decreases, with
apparent changes occurring at II sites. Most changes in the sediment char-
acteristics resulting from gravel removal operations occurred at scraped
sites in or immediately adjacent to active and high-water channels and
at those sites where fine sediment sources were left in the floodplain
near the channe I .
135
ICE CHARACTERISTICS
Two ice characteristics were identified as potentially being increased
as a result of gravel removal activity. They are ice jamming and auf e i s
formation. These can be affected by a widening of the channel followed
by a rapid reduction in width, a reduction in depth, obstructions in the
floodplain, and relocating the channel through an area which was previously
dry. Aufeis formation was observed at four study sites.
HYDROLOGY
The only characteristic related to the hydrology of the river which
was identified as potentially changing as a result of gravel removal opera-
tions was a change from surface flow to groundwater flow or vice versa.
This change, although relatively minor at most sites, can have a local
effect on the mean annual flow, flow duration curve, and potentially,
on the flood frequency curve. Significant reduction of surface flow occur-
red at two study sites.
RECOMMENDATIONS
Listed below are several recommendations concerning gravel removal
operations, the purpose of which is to reduce the number or magnitude
of changes to the physical characteristics of rivers:
1. Small rivers should not be considered as gravel sources.
2. Braided rivers should be considered as primary gravel sources;
other river configurations, listed in order or likelihood of caus-
ing the least physical change, are split, meandering, sinuous,
and s tr ai gh t .
3. Pit excavations should be located on terraces or possibly inactive
floodplains and should be separated from the active floodplain
by a buffer designed to maintain this separation for two or more
decades .
136
4. Material sites within the active f I oodp I a i n should:
• Not disturb the edge of the active channel (s);
• Maintain a high-water channel shape, within the material site,
similar to that which enters and leaves the site;
• Not increase the bed slope of active or high-water channels
local ly to more than that of natural ly occurring slopes;
• Form new high-water channels through the site if flow is expected
through the site;
• Be shaped and contoured to provide proper drainage;
• Have material stockpiles, overburden piles, and dikes removed
from near active channels unless they have a specific purpose for
being there and are designed to withstand the hydraulic forces;
and
• Be protected from low flow channels until the occurrence of the
first flood after the site is completed.
157
REFERENCES
Carey, K. L. 1973. Icings Developed from Surface Water and Groundwater,
U.S. Army Cold Regions Research and Engineering Laboratory. Mono-
graph I I I-D3. 71 pp.
Chow, V. T. 1959. Open-Channel Hydraulics. McGraw-Hill Book Company,
New York, 680 pp.
Doyle, P. P., and J. M. Childers. 1976. Channel Erosion Surveys Along
TAPS Route, Alaska, 1976. U.S. Geological Survey Open-Pile Report.
89 pp.
;ams
Emmett, W. W. 1972. The Hydraulic Geometry of Some Alaskan Strec
South of the Yukon River. U.S. Geological Survey Open-File Report.
Anchorage. July. 102 pp.
Emmett, W. W. 1975. The Channels and Waters of the Upper Salmon River
Area, Idaho. U.S. Geological Survey Professional Paper B70-A. 116 pp.
Karaki, S., K. Mahmood, E. V. Richardson, D. B. Simons, and M. A.
Stevens. 1974. Highways in the River Environment - Hydraulic and
Environmental Design Considerations. Prepared for Federal Highway
Administration by Civil Engineering Department. Colorado State
University. Fort Collins, Colorado. 453 pp.
Lamke, R. D. 1979. Flood Characteristics of Alaskan Streams. U.S. Geo-
logical Survey Water Resources Investigations 78-129. 61 pp.
Leopold, L. B., M. G. Wolman, and J. P. Miller. 1964. Fluvial Processes
in Geomorpho logy . W. H. Freeman and Company, San Francisco, Cali-
fornia. 522 pp.
Li, R. M. , and D. B. Simons. 1979. Mathematical modeling of erosion and
sedimentation associated with instream gravel mining, pp. 420-429.
In Conservation and Utilization of Water and Energy Resources. ASCE
Hydraulics/ Energy Division Conference. San Francisco. 8-11 August.
Rundquist, L. A. 1975. A Classification and Analysis of Natural Rivers.
Dissertation. Colorado State University. Fort Collins, Colorado.
377 pp.
Sheridan, W. L. 1976. Effects of Gravel Removal on a Salmon Spawning
Stream. U.S. Department of Agriculture. Forest Service. 26 pp.
138
I
Woodward-Clyde Consultants. 1976a. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-arctic Streams in Alaska. U.S.
Fisti and Wildlife Service. FWS/OBS 76/21. Wasti. D. C. 127 pp.
Woodward-Clyde Consultants. 1976b. Aggregate Extraction Management
Study, County of Yolo California. Prepared for the County of Yolo.
Planning Department. Aggregate Resources Management Committee.
128 pp.
139
EFFECTS OF GRAVEL REMOVAL ON AQUATIC BIOTA
L. L. Moulton
INTRODUCTION
Populations of organisms are conlTolled by physical and chemical fac-
tors, often termed their environment, and by biological factors, including
predation and competition. Environmental constraints on a particular species
determine the usable habitat available to that population and the size of
the population is often restricted by the amount of usable habitat. After
the maximum number of individuals a particular habitat can support (termed
the carrying capacity) has been reached, the population cannot increase with-
out an increase in usable habitat. Predation and competition can act on a
population to limit numbers below the carrying capacity, thus undisturbed
populations are not necessarily fully utilizing the available habitat.
Alterations to the habitat can alter the quality of the habitat, lead-
ing to direct changes in the carrying capacity, and consequently, to reduc-
tions in the affected populations. Decreases in habitat diversity may reduce
the carrying capacity for one species while leaving that for another un-
changed. If the two species were in competition, the reduction or removal of
one may al low the other species to increase. General ly, decreases in habitat
diversity will result in an increased carrying capacity of one species which
is able to efficiently utilize the more uniform habitat. Conversely, in-
creases in habitat diversity general ly cause increases in the number of
species or life history stages present as new habitat types are added. These
species increases are often accompanied by decreases in the populations
which had formerly been utilizing the more uniform, less diverse, habitat.
141
The decreases may be due either to less available habitat or to competition
from species which more efficiently utilize the newly created habitats.
The types of habitats present in a river are determined by the loca-
tion, size, configuration, and water quality characteristics of the river.
Features which define specific habitats include depth, velocity, substrate,
and cover. Alterations to a river which affect any of these features will
also affect the habitat available in the river and may impact habitats
downstream from the alterations. Habitat alterations may affect the quality
or diversity of the habitat, or both. Reduced habitat quality makes the area
less desirable to the species present prior to alteration, while altered
habitat diversity may favor one species or life history stage over another.
Reduced habitat quality implies alteration of a single habitat type whereas
reduced habitat diversity implies reduction in the number of available
habitats but the two responses are not independent.
Several types of habitats may be used in the life cycle or even sea-
sonal cycle of an organism, and there is often a critical habitat which
controls the size of the population. In the arctic and subarctic environ-
ment, the critical habitat for fish populations is often the amount of
overwintering habitat. Other critical habitats often controlling fish popu-
lations are spawning and rearing areas. Critical habitats vary from stream
to stream and species to species depending on the characteristics of the
streams and the life cycle requirements of the species.
Recent studies have been aimed at quantifying the effects of habitat
alteration on stream populations (Stalnaker and Arnette 1976, Bovee and
Cochnauer 1977, Binns and Eiserman 1979). Two of the basic requirements of
these efforts are detailed measurements of appropriate habitat parameters
and an intimate knowledge of the habitat requirements of the species in ques-
tion. The emphasis of the present study was on a multiple-disciplinary
survey of the effects of floodplain gravel removal on a broad geographical
scale. Because of the limited data on many species and complete lack of data
on many of the river systems studied, a detailed habitat analysis was not
possible. The 3 to 4 day surveys at each site allowed for gathering of basic
142
physical and biological data but not the type of detail required for sophis-
ticated correlation analysis. For these reasons the present analysis was
confined to analysis of trends and subjective evaluations of habitat alter-
ations and their effects on aquatic organisms.
The material sites were visited 2 to 20 years after mining was com-
plete, thus the immediate effects of grave> removal operations were not
studied. The changes evaluated during the present study were those which
persist over a number of years rather than those affecting the biota during
the year of disturbance. A literature review of impacts at the time of
actual gravel removal was presented by Woodward-Clyde Consultants (1976).
143
METHODS OF DATA COLLECTION
As detailed in APPROACH AND METHODOLOGY a variety of standard sampling
methods were utilized at each study site with the specific methods used
dependent on the type of river system and habitat being studied.
144
METHODS OF DATA ANALYSIS
The data from each of the 25 sites were first analyzed on a site-
by-site basis to determine the effect of gravel removal operations on the
aquatic environment at each study site. These individual site evaluations
provided the basis for further analysis to identify trends and correlations
relating to major site variables (Table I, Major Variable Matrix). These
individual site evaluations are not included because of space limitations
but are part of the permanent data base maintained by the U. S. Fish and
Wi I d I i f e Service.
The various physical and biological parameters measured at the dif-
ferent sites varied greatly in magnitude and the variation made the direct
comparison of data among sites impractical. The various parameters recorded
at the study sites were standardized on a scale of 0 to 10 to obtain a
relative measure of the degree of change. A rating of 5 indicates that a
parameter measured in the mined area had not changed from the same parameter
in the upstream area; ratings of 0-4 and 6-10 indicate decreased and in-
creased parameter values in the mined area relative to the upstream area.
The rating was determined by calculating the percentage change in the mined
area relative to the upstream area for each site and subjectively assigning
rating values to various percentage intervals such that all or most of the
0-10 scale was utilized for those sites at which the parameter was evalu-
ated. Data from study sites with similar ratings were examined for similar
alterations that might lead to a similar parameter response.
The analysis of habitat alteration was based on field notes from the
site surveys, ground and aerial photographs, direct measurement of habitat
parameters, results of hydraulic analysis, and visual observations. Habitat
parameters considered in the analysis included changes in substrate type.
145
substrate porosity, configuration of adjoining banks, bank and instream
cover, number of channels, pool-riffle frequency, depth, velocity, and
wetted perimeters at different flow levels. Additional habitat alterations
were noted where appropriate, such as excessive siltation, auf e i s formation
and creation of new aquatic habitats. Much of the analysis was subjective
because many habitat parameters were difficult to quantify, consequently,
the analysis was kept conservative. The results of hydraulic analysis, as
described in the EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND
HYDRAULICS, allowed for a certain amount of habitat parameter quantification
and these results supported the subjective evaluations whenever comparisons
were available, indicating that subjectivity was not a major source of
error.
Analysis of changes in fish populations was accomplished by evalu-
ating the types of habitat alterations occurring in the mined area relative
to the upstream area. Then the measured parameters that appeared to be
most important at the particular site were examined to determine if there
had been a change in fish distribution, as indicated by a difference in
catch rate between the upstream and mined areas. In this manner the combi-
nations of habitat alteration could be evaluated for their cumulative effect
on the population of fish present during the site visit. Additional effects
were postulated based on known life history requirements of the various
spec i es.
The large number of benthic sample replicates obtained at each study
site during the field surveys allowed for an analysis of variance to de-
termine if significant differences existed in the densities among sample
areas within a study reach. All Surber sample data were computer coded and
the densities were subjected to an analysis of variance and multiple classi-
fication analysis (Nie et al. 1975). A nonpar ameter i c procedure, the Mann-
Whitney U-test (Zar 1974), was also used to evaluate differences in density.
The results of the two tests were compared and, where the results of the two
tests differed, the more conservative nonparametr i c test was used. Addi-
tional computer analysis included the calculation of various indices of
diversity and similarity, such as the Bray-Curtis and Raabe similarity
146
indices, and Shannon-Weaver and Simpson density indices. The indices respond
differently to changes in density and diversity and were used primarily to
search for changes in the aquatic macro i nvertebrate assemblages vulnerable
to Surber samplers.
Because the level of identification was to the generic level at best
and often only to family or order, the indices were applicable only to the
present study. Comparison with results of other studies and extensive anal-
ysis of the data are not justified. Often multiple species within a genus
were recognizable but the absence of suitable taxonomic aids for arctic
aquatic macro i nvertebrates inhibited identification. A list of collected
taxonomic groups by phyletic classification, with associated common names,
is included in Appendix A.
147
RESULTS AND DISCUSSION
MAJOR GRAVEL REMOVAL HABITAT ALTERATIONS
Habi tat Qual i ty
Alterations of habitat quality observed at many of the sites consisted
primarily of substrate alteration and removal of both instream and bank
cover. Siltation, commonly associated with instream disturbances, was ob-
served at a few sites, but was not a major factor because most of the sites
were visited several years after mining had been completed. At three sites
where siltation was observed it was caused by eroding berms (Kavik River)
or melting aufeis fields (Washington Creek, Oregon Creek) (Figure 40).
Two types of substrate alteration were observed: (I) a shift from a
moderately compacted gravel substrate to a very loose, unconsolidated sand-
gravel substrate, usually with considerable intergravel flow and (2) a
shift from a smooth, paved substrate which produced near laminar flow to a
more porous, irregular substrate producing turbulent flow. Most of the
substrate alterations recorded were Type I alterations with only two Type 2
alterations observed. Type I alterations occurred at four of the eight sites
where scraping was conducted in an active channel (Washington Creek, Oregon
Creek, Penny River, McManus Creek) and at four where flow subsequently
increased or diverted to inundate a scraped area (Sinuk River, Kuparuk
River, Sagavan irktok River, Ivishak River) (Table 13). The effects of this
type of alteration appear to be long-term, because this alteration was
noticeable at McManus Creek 16 years after mining. The effect on the sub-
strate was caused by removal of the armor layer, loosening of the gravels,
and subsequent washing out of fine materials. Formation of ice in the mined
areas appeared to prolong the recovery time of this type of alteration.
148
a) Sediment being released by melting aufeis.
b) Silt deposited in substrate downstream from aufeis field.
Figure 40. Siltation resulting from extensive aufeis field at
Oregon Creek mined study area, 20 June 1977.
149
Table 13. Major Habitat Alterations Observed at Sites Mined by Scraping
(5 = No Change, 6-10 = Trend Towards Parameter, 0-4 = Trend Away From
Parameter )
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Seward Peninsula
Gold Run Creek
S i nuk Ri ver
Washington Creek
Oregon Creek
Penny River
Nome River
a
5
5
8
5
6
5
7
5
8
-
6
9
8
10
5
10
10
10
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10
5
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5
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5
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North Slope
Ugnuravik River
Aufeis Creek
Kuparuk River
Skeetercake Creek
Sagavan ir ktok River
I V i shak R i ver
Shav i ov i k R i ver
Kavik River
9
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Northern Interior
Dietrich Ri ver-Upstream
Dietrich River-Downstream
M.F. Koyukuk River-US
M.F. Koyukuk River-DS
5
5
5
5
5
5
5
5
5
5
5
6
7
7
5
5
10
5
10
9
9
5
5
5
5
8
10
7
Southern I nter i or
McManus Creek
Phelan Creek
7
5
5
4-
10
2
Dash means parameter not evaluated at this site.
150
Type 2 substrate alterations were documented at two locations, both on
medium size North Slope rivers (Table 15). In one case, Ugnuravik River,
the upstream area showed near laminar flow that was changed to turbulent
flow while in the other case, Shaviovik River, the reverse occurred - the
upstream flow was turbulent whereas the flow through the mined area was
laminar. Such changes would be expected naturally where localized substrate
or slope differences alter flow characteristics.
Bank cover is provided by structures on or features of the stream
bank that provide shelter from surface predation and reduce visibility. Ex-
amples of bank cover include overhanging vegetation and incised or undercut
banks, thus bank cover was eliminated when mining removed these features
(Figures 41 and 42). These types of bank cover were typically present in
straight, sinuous, meandering or split channel rivers, but were less common
in braided rivers. Significant bank cover loss was observed at 6 of the 21
scraped sites, Sinuk River, Washington Creek, Oregon Creek, and Penny River
sites on the Seward Peninsula, at the Skeetercake Creek site on the North
Slope, and at the Middle Fork Koyukuk R i ver-Upstream in the Northern In-
terior (Table 13).
Instream cover is created by obstructions, such as boulders or logs,
that provide slack water where fish can hold position with minimal energy
expenditure and reduce predation from above by being less visible. Water
depth can also function as cover, because deep pools and runs offer more
overhead protection and often lower velocities than shal low riffles. Certain
species, such as Arctic char and Arctic grayling, are often associated with
instream cover. Instream cover was reduced at five sites, Washington Creek,
Oregon Creek, Penny River, Kavik River, and Sagavan ir k tok River, as a result
of directly removing boulders and large cobbles or altering flow such that
new channels did not possess this habitat (Figures 43 and 44). At six sites.
Gold Run Creek, Washington Creek, Oregon Creek, Aufeis Creek, Skeetercake
Creek, and Sagavan i rk tok River, the channel configuration was altered so
that the channel was wider and shallower in the mined areas, thus the in-
stream cover provided by depth was reduced by lowering the ratio of pools to
r i f f I es.
151
a) Undercut vegetated bank typical of Oregon Creek upstream
study area.
b) Oregon Creek mined study area
mu 1 1 i p ie channel s.
- notice lack of bank cover,
Figure 41. Removal of bank cover at Oregon Creek as observed
on 24 June 1977.
152
a) Skeetercake Creek upstream study area - note undercut
vegetated bank.
b) Skeetercake Creek mined study area - bank cover absent,
flow spread over wide, shallow area.
Figure 42. Removal of bank cover at Skeetercake Creek as
observed on 18 June 1977.
153
a) Washington Creek upstream study area showing predominance
of boulders.
b) Washington Creek upper mined study area, note spread of
flow, multiple channels, lack of surface water.
Figure 43. Washington Creek upstream and mined area on 9
September 1977 showing reduction of i nstream^cover due to
gravel removal operation (flow level [O. II m /sec] = 20 per-
cent of mean annual flow). Other habitat alterations include
increased braiding, siltation, and intergravel flow.
154
Sagavan i rk tok River upstream study area, note predominance
of bou I ders.
b) Sagavan i rk tok River mined study area showing extensive
sedimentation and backwaters.
Figure 44. Reduction of instream cover as provided by
boulders at Sagavan i rk tok River, 3 August 1978 (flow level,
60 m /sec, = 155% of estimated mean annual flow).
155
Hab i tat D i vers! ty
The result of decreasing habitat diversity, that is, creating uniform
habitats by gravel removal operations, was to favor certain species or life
history stages over others. One of the main indicators of reduced habitat
diversity was increased braiding in the mined area caused where gravel
deposits were scraped to below the water line or where flow subsequently
increased to inundate the mined area. This type of habitat alteration oc-
curred at 10 study sites (Washington Creek, Oregon Creek, Penny River, Nome
River, Aufeis Creek, Kuparuk River, Sagavan irktok River, Ivishak River,
Kavik River, and Middle Fork Koyukuk River-Downstream) (Figures 43 and 45,
Table 13). The channels in a braided area usually have a uniform depth,
velocity, and substrate with minimal bank cover. The areas were general ly
characterized by increased wetted perimeter, reduction in channel depth, and
reduced mean velocities (Figure 46). At Washington Creek (Figure 46a), for
example, the cross section in the upper mined area (Cross Section 3) had the
greatest wetted perimeter at al I flow levels, but most of this was in shal-
low open channels with little cover. Similarly, at Oregon Creek (Figure
46b) the wetted perimeter at cross sections in the mined area (Cross Section
2 and 3) was considerably greater than that in the upstream area and ap-
proached or exceeded that of the Cripple River cross sections, a river
with greater than three times the estimated mean annual flow of Oregon
Creek. Again, the Oregon Creek mined area channels were wide and shallow,
providing low quality and low diversity habitat. The final example,
Sagavan i rktok River (Figure 46c), showed a similar pattern with the mined
area cross sections having a greater wetted perimeter, but a shallower depth
profile than cross sections in undisturbed areas.
Habitat diversity was increased in some other mined areas by the crea-
tion of new habitats. Three types of new habitats were usually found: (I)
low velocity backwater areas, (2) a side channel off the main river, and (3)
a flooded pit forming a pond habitat (Figures 47 and 48). Low velocity back-
water areas were found at five sites (Sinuk River, Skeetercake Creek,
Sagavan irktok River, Dietrich River-Downstream, and Middle Fork Koyukuk
Ri ver-Upstream) ; side channel formation occurred at three sites (Skeetercake
156
f- «p
^
a) 27 July 1973 - pre-mining
b) 2 August 1976 - post mining
Figure 45. Increased braiding at Sagavan i rk tok River study site caused by
mining mid-channel gravel bars and a vegetated island in the active channel
(mining operation conducted during the winter of 1974-1975).
157
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Derimeters to
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158
a) Dietrich River-Downstream - inundated mined study area.
b) Middle Fork Koyukuk R i ver-Upstream - backwater in lower
m i ned area .
Figure 47. Low velocity backwaters formed by gravel removal
at Dietricti River-Downstream (13 July 1978) and Middle Fork
Koyukuk R i ver-Upstream (18 July 1978), note extensive silt
deposition in both cases.
159
Cut-off
channel
created
by mining
Original
channel
a) Skeetercake Creek showing cut-off channel, 4 September 1975.
b) Jim River showing side channel created by mining in a high-
water channel, 12 August 1978.
c) West Fork Tolovana River pit created by deep excavating in
an abandoned channel, 29 July 1978.
Figure 48. Creation of low velocity side channels and inundated
pit following gravel extraction.
160
Creek, Middle Fork Koyukuk R i ver-Upstream and Jim River); and flooded pits
were created at seven sites (Penny River, Ugnuravik River, Dietrich R i ver-
Upstream, Prospect Creek, West Fork Tolovana River, Tanana River-Downstream,
and Tanana R i ver-Upstream) .
The changes in habitat diversity were determined by the location of
mining and, to some extent, the type of mining. Braiding (decreasing habitat
diversity) occurred where the majority of flow went through a mined area,
such as where a meander was eliminated (two sites: Penny River, Middle Fork
Koyukuk River-Downstream), an inchannel island or gravel bar was removed
(five sites: Washington Creek, Kuparuk River, Sagavan irk tok River, Ivishak
River, Kavik River) or where excavation occurred in an active channel (five
sites: Washington Creek, Oregon Creek, Penny River, Nome River, Aufeis
Creek). Removal of gravel in active channels created braided areas in what
had previously been pool-riffle habitats, thus, in these cases there was
often a loss of instream and bank cover, substrate alteration, depth alter-
ation, spreading of flow combined with decreased velocity, and loss of pools
and riffles. Habitat diversity increased at two sites with incomplete
meander cutoffs forming backwater and ponded areas or side channels
(Skeetercake Creek, Middle Fork Koyukuk R i ver-Upstream) and with gravel
removal in a high-water channel to below the water table such that it con-
tained ponded water (Sinuk River) or annual flowing water (Jim River).
Habitat diversity also increased at three sites where recent gravel
extraction or channel changes created low velocity backwater areas and
braided characteristics were not well established ( Sagavan irk tok River,
Dietrich River-Downstream, Middle Fork Koyukuk R i ver-Upstream) . Ponded areas
or low velocity backwaters were characterized by a sand to silt substrate.
The low velocity with associated clear water often allowed increased growth
of filamentous algae. Water temperatures were usually increased over those
in the active channel because of the dark substrate and poor circulation.
Similar effects, although not as great in magnitude, were observed where
side channels were formed at Jim River and Middle Fork Koyukuk River-
Upstream. Water velocities were reduced and increased silt deposition was
observed in the main channel.
161
The three sites with increased habitat diversity due to recent flow
were 3 to 4 years old and, in two cases (Dietrich River-Downstream and
Middle Fork Koyukuk R i ver-Upstream) , flow had only entered the site within a
year or two of the site study (Figure 49). The habitat diversity in these
areas will probably decrease within a few years as meander cutoffs are
completed and braiding characteristics are established.
Inundated pits were formed when gravel removal was conducted away
from the active channel and the depression, usually deeper than I m, filled
with water either by direct connection to the river or through intergravel
flow. These areas developed characteristics typical of pond habitats, i.e.,
mud bottom, rooted aquatic vegetation around shorelines, high density plank-
ton communities, and macroi nvertebrates typically associated with a lentic
environment. Two types of pits were included in the study: shallow (< 2 m)
and deep (> 2 m) pits (Table 14). Shallow pits (Penny River, Ugnuravik
River, Prospect Creek) normal ly froze to the bottom in the winter wh I le
deep pits (Dietrich R I ver-Upstream, West Fork Tolovana River, Tanana River-
Downstream, Tanana R I ver-Upstream) contained water year-round.
Two of the deep pits (West Fork Tolovana River, Tanana R i ver-Upstream)
showed dissolved oxygen and temperature stratification in the summer of
study while the other two (Dietrich R i ver-Upstream, Tanana River-Downstream)
did not (Figure 50). The time at which stratification would be most pro-
nounced was missed at Dietrich Ri ver-Upstream and Tanana River-Downstream
and it is possible that there was some stratification mid-SLimmer; however,
the Tanana R i ver-Upstream and West Fork Tolovana River were thermally strati-
fied from early June to mid-September. Al I pits except the Tanana River-
Downstream pit were connected to the associated rivers. The Tanana River-
Downstream pit was on a vegetated island and connection to the river was
inundated only during annual high water events. This pit had clear water
(bottom visible to deeper than 5 m) , very little mud or silt even In the
deepest area, and virtually no thermal stratification. Aquatic vegetation
was absent except along the shoreline, despite the extreme water clarity.
Four of the five deep pits had extensive shal low areas, with over 25 percent
of the area less than I m deep. Only at the Tanana River-Downstream was a
majority of the area deeper than 2 m (Table 14).
162
vf
a ) 16 Sep t ember I 972
b) 2 August 1976
Figure 49. Sequence of aerial photographs showing effects of overmining
the inside of a meander bend at Middle Fork Koyukuk R i ver-Upstream.
Immediately following mining (b) there was an increase in backwater
areas. The next year (c) the meander was partially cut off, creating a
variety of low velocity habitats.
163
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T and DO
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a. Dietrich - Upstream. 10 July 1978
b.West ForkTolovana,13 Sept 1978
1
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d.Tanana — Upstream, 19 Aug 1978
X' — X Temperature (°C)
• • Dissolved Oxygen (mg/t)
Figure 50. Temperature and dissolved oxygen profilesat four deep gravel pit
study sites.
165
Water Qua I i ty
Water quality measurements reflected habitat alterations in several
ways. First, dissolved oxygen and temperature responded in a predictable
fashion to increased braiding. The spreading and shallowing of flow and loss
of cover led to an increased rate of heat exhange, with the temperature, and
therefore dissolved oxygen, responding more quickly to ambient air tem-
peratures in the mined area than in the upstream area. Similarly, areas with
ponded water showed increased temperatures and reduced dissolved oxygen
(Skeetercake Creek, Dietrich River-Downstream). An increase in dissolved
oxygen and decrease in temperature which was not caused by flow alteration
was recorded at Dietrich Ri ver-Upstream where a spring was uncovered during
gravel removal operations. As mentioned, inundated pits functioned as pond
habitats with corresponding water quality characteristics. These included
higher temperature and lower dissolved oxygen than the associated rivers and
in some cases, thermal and oxygen stratifications.
A second type of water quality change was a change in conductivity
between the upstream and mined areas. A change in conductivity may indicate
the existence of a spring water source near or exposed by the gravel removal
operation. Such changes were recorded at Aufeis Creek, Skeetercake Creek,
Dietrich Ri ver-Upstream and Penny River. As already mentioned, the Dietrich
R i ver-Upstream was an identified spring exposure. The Penny River had a
spring-fed tributary entering the floodplain in the mined area. Springs were
not recorded at Aufeis Creek or Skeetercake Creek, but the conductivity
changes may indicate their existence.
A third type of water quality change was alteration in turbidity or
suspended solids, or both, in the mined area compared to the upstream area.
These changes probably indicate erosional or depositional characteristics of
the mined area, but the sampling was insufficient to reach definite conclu-
sions on an individual site basis.
166
EFFECTS OF HABITAT ALTERATION ON FISH POPULATIONS
Observed Alteration of Summer Distributions or Densities
Several types of changes in summer fish distribution were observed
in the mined areas; specific types of distributional changes were related to
certain types of habitat alterations caused by gravel removal. These changes
included: (I) reduction in the numbers of all fishes in a disturbed area,
(2) replacement of one species by another species, (3) replacement of one
age group by another age group, and (4) increase in the number of fish or
species, or both (Table 15). A list of all species caught during the study
and their scientific names is included in Appendix A.
Density Reductions. Reductions in numbers of all fish populations
occurred at Washington Creek, Aufeis Creek, and Kavik River sites. The
habitat in the upper mined area of Washington Creek was altered in several
ways, reducing habitat quality and diversity to an extent that few organisms
could utilize the newly created habitat. The density and biomass of Arctic
char was significantly reduced downstream of the upstream sample area (Table
16). The slimy sculpin density and biomass was also reduced in the upper
mined area, but increased in the lower sample areas to densities exceeding
those in the upstream area. The sculpin biomass remained low, indicating the
slimy sculpin captured below the mined area were smaller than those captured
above. Thus, there was a replacement of Arctic char habitat by a habitat
more suitable for slimy sculpin in the lower three sample areas. The spe-
cific habitat alterations that led to a loss of Arctic char habitat were
removal of bank and instream cover and possibly reduced water quality (i.e.,
increased turbidity) caused by siltation from the melting aufeis field.
At the Aufeis Creek site, there was only one life history stage of
Arctic grayling present during each sampling trip, thus any changes would
have to be density reductions rather than species or age-group shifts.
Density reductions were recorded in the upper mined area during the first
trip and al I disturbed areas in the second trip. Specific habitat altera-
tions that led to reductions in Arctic grayling habitat were: (I) the reduc-
167
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172
tion of the pool-riffle frequency, and (2) increased braiding characteris-
tics with the associated loss of bank cover and altered flow regime.
At the Kavik River site, habitat quality was altered by the erosion of
berms left in and along active channels, channelizing one section of the
river, and creation of a more braided configuration. The densities of Arctic
char and Arctic grayling for each study area were estimated by repeated
shocking of blocked channels (Table 17). Total fish densities in the mined
area were reduced by a factor of three or greater when compared to the
undisturbed areas (Table 18). The catch of adult Arctic grayling, as de-
termined by angling, was also lower in the mined area (Table 19). The den-
sity reductions occurred in both Arctic grayling and Arctic char with
neither species apparently favored by the habitat alteration. Removal of
instream cover appeared to be a major habitat alteration affecting reduction
of fish densities because a channel that contained boulders adjacent to the
mined area supported densities of both species comparable to those in un-
disturbed areas.
Species and Age Group Alteration. Species shifts were observed at nine
sites (Washington Creek, Oregon Creek, Penny River, Kuparuk River,
Sagavan i r k tok River, Ivishak River, Dietrich River-Downstream, Middle Fork
Koyukuk R i ver-Upstream, and Middle Fork Koyukuk River-Downstream) because
alterations in the type of habitat allowed other species to populate an area
(Table 20). A similar response is a change in the age structure of fish
inhabiting a reach of river, as was observed at Kuparuk River, Skeetercake
Creek, and Middle Fork Koyukuk Ri ver-Upstream. In these areas newly created
habitats favored or excluded certain age groups in the areas affected by
gravel removal operations. On Kuparuk River, the mined area had a more
uniform habitat than the upstream area and numerous small channels of simi-
lar velocity. Age-0 and age-l Arctic grayling and several age groups of
slimy sculpin were present in the upstream area while only age-l Arctic
grayling were captured in the mined area. At the Sagavan i rk tok River, Arctic
grayling juveniles were confined almost exclusively to the mined area, while
the upstream area catch was dominated by round whitefish and an unmined
channel adjacent to the mined area contained adult (-300 mm) Arctic gray-
ling. Again, the mined area was changed from a large single channel to an
173
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175
Table 19. Catch of Arctic Grayling per Angler Hour at Kavik River Study
Areas During Summer 1976 Sampling Trips
Area
Per i ods
of
f i sh i ng
Total
hours of
effort
Average number
of f i sh per
^ a
angler hour
22 - 24 July
Upstream
M i ned
Downstream
4-8 August
Upstream
Mined
Downstream
28 - 31 August
Upstream
Mi ned
Downstream
4.7
7.9
5.6
4.5
2.2
2.6
6.0
3.0
0
3.4
1 .8-4.
5)
2.6
1.3-3.
,6)
4.8
2.2-6.
,0)
; 2. 25-4. 9)
2.3
3. I
I .7
0
Value in parentheses is range of estimated values.
76
TabI* 20. Chang* in Catcn par Effort and Pareant Compealtion of Indicator Spacias
at Salactaa Study Sitaa (Salactad on Basis of Suitabia Sampla Siza)
Rivar
Obaarvao cotcn par affort
Samp la Minnow trap
arae ( f i sh/ trap )
Sai na
( r isn/haul i
Elactroshock
2
I f ish/ 1 00m >
Spacias composition
% Char % Gray l i nq
Minnow Eiactro- All Major spacies
trap
shock gaar typas lost/gainac
Washington Ck
U
UM
BM
L*
D
I .3
0.7
0.0
0.2
2.2
26
5
12
22
26
100
100
55
il
u
9
I I
•'SS
♦ss
*ss
♦ss
Or agon Ck - J una
22
I I
56
93
-SS
August
4.6
2.7
137
164
93
78
68
65
*SS
Saptampar u
1 .7
2.9
14
30
100
85
36
45
»SSI«IIT1
-SSIESI
Penny R • Jung
0.06
0.20
0.50
0
33
3
♦SS
♦CS. ♦SS
August U
W
P
D
15.2
40.5
7.4
24.8
71
64
4
85
♦CS
♦CS
-CS
Saptatnber U
W
P
0
ie.2
9.8
12.6
1.3
42
34
0
67
♦CS
♦CS
-CS
Kuparuk R
U
M
6. J
12.8
1.0
43
94
75
-SS
-SS
Segavanirktok R U
Hi
D
0.56
1.12
0. 14
10
61
0
ivisnak R u
W
0
3.1
3.3
1.9
80
87
87
17
8
5
♦AC
♦AC
Dietrich R-Oownstraam u
M
0
1.65
0.65
1.50
54
79
48
-SS
♦RWP
Miodla Fork Ksyukuk
River-Opstraam U
UM
LM
OC
0
4.2
1.9
4.4
1.8
3.1
64
44
♦RWF
59
♦RWF.^LNS
55
♦RWF
25
♦SS, ♦RWF
Middle Fork koyukuk
Ri var-Downstraam u
M
D
1.3
2.7
25
38
♦SS, ♦RWF
♦SS, ♦awF
U ■ upstream
UW « upper mi ned
BM
LM * lowe*- mined
P « pit
OC
* « increased feiative to upstream
CS » coho salmon RwF » round whitefish
AC
between mined D ■ downstream
or iginai channel
decreased relative to upstream SS
Arctic char LNS
S [ imy SCu I p in
longnose sucker
177
area criss-crossed with numerous shallow small channels. At Skeetercake
Creek, gravel removal in the upper mined area created an extensive backwater
which was utilized by adult Arctic grayling; at the middle mined area, bank
cover and pools were removed and this led to a reduction in the population
density of Arctic grayling. At the lower mined area of the Middle Fork
Koyukuk Ri ver-Upstream site, the single-channel sinuous configuration of the
river was changed to a split channel with extensive backwater areas. The
catch and species present were similar between mined and undisturbed areas,
but the age structure was more complex in the areas affected by gravel
removal. Age-0, age- I , and age-2+ Arctic grayling, age-0 round whitefish,
and age-l and adult longnose sucker were captured in the mined areas while
the species caught in undisturbed areas were primarily represented by a
single age group. Only round whitefish exhibited a more diverse age struc-
ture in the undisturbed areas. Similarly, at the Middle Fork Koyukuk River-
Downstream site the river was changed from a single channel to a multiple
channel braided system with numerous backwater areas. Arctic grayling domi-
nated the catch at the upstream area, but were replaced in the mined area by
round whitefish and slimy sculpin.
Potential for Entrapment. Gravel removal in active floodplains created
areas of ponded water which were isolated from the active channel. Typically
these ponded areas were inundated during high water and became isolated as
the water level receded (Figures 51 and 52). Fish often entered these ponded
areas during high water and became stranded as the water level dropped. The
mortality rate of these fish was assumed to be high because they were sub-
jected to increased temperature, decreased dissolved oxygen, greater vulner-
ability to surface predation, desiccation if the area dried completely, and
freezing. There were 15 scraped areas at which ponded areas were observed:
Sinuk River, Washington Creek, Oregon Creek, Penny River, Nome River,
Ugnuravik River, Aufeis Creek, Kuparuk River, Skeetercake Creek,
Sagavan irktok River, Dietrich River-Downstream, Middle Fork Koyukuk River-
Upstream, and Middle Fork Koyukuk River-Downstream (Table 13). Sampling in
these ponded areas revealed significant entrapment at some sites. At Sinuk
River the mined area was not heavily utilized by fish. Pink and chum salmon
spawn in the river and considerable numbers of chum salmon fry were captured
78
Figure 51. Ponded area at Kuparuk River study site where
three seine hauls captured 61 Arctic grayling and 2 slimy
sculpin, 9 August 1978 (pool I in Table 21).
Figure 52. Ponded area at Middle Fork Koyukuk-Upstream study
site where one seine haul captured 28 Arctic grayl ing, 3
round whitefish and 3 slimy sculpin, 18 July 1978 (pool 2 in
Table 2 1).
179
above and below the mined area. Pink and chum salmon are often associated
with low velocity water and there was high potential for entrapment of
downstream migrants of these two species. The same two species, plus coho
salmon, were vulnerable to entrapment at the Penny River site. At Washington
Creek, Oregon Creek, and Penny River, the dominant species, Arctic char, are
probably not greatly affected by entrapment because they are generally
associated with high velocity water and instream cover and would tend to
avoid the type of areas which are prone to ponding. At the Kuparuk River
site, a natural ponded area, apparently enlarged by gravel excavation,
contained a high density of age-l Arctic grayling (Table 21, Figure 51). At
the latter site both natural and ponded areas created by gravel removal were
present in the study reach. At the Middle Fork Koyukuk R i ver-Upstream,
considerable stranding was documented when several isolated pools were
sampled (Table 21, Figure 52). The primary species subjected to entrapment
in the Middle Fork Koyukuk River system was Arctic grayling.
Migration Blockage. Two types of potential mi n i ng- i nduced migration
blockages were observed during the study: (I) blockage due to aufeis for-
mation, and (2) blockage due to lack of surface flow. Possible temporary
migration blockage due to aufeis formation may have occurred at the Wash-
ington Creek and Oregon Creek sites (Figure 53). The principal migrations
that could be affected in these particular systems would be upstream and
downstream movements of juvenile Arctic char and juvenile coho salmon moving
from overwintering areas to feeding areas and downstream migrations of adult
Arctic char returning to the sea from upstream overwintering areas, if
present. A short-term delay in these migrations may not have a critical
effect on these particular species, but a similar blockage for another
species, such as an upstream spawning migration of Arctic grayling, may have
a great effect on the population in the river. A blockage due to lack of
surface flow can occur where flow is spread over a wide area and there is
considerable intergravel flow. Under such conditions, all surface flow may
cease. Such a condition occurred at the Aufeis Creek site (Woodward-Clyde
Consultants 1976) (Figure 54) and possibly could occur at the Nome River
site (K. Tarbox, personal communication). The potential for such a blockage
180
Table 21. Summary of Catch from Ponded Water Areas Isolated
From Active Channels at Two Study Sites
Locat i on
Catch per hau I
Pool
No. of
seine Arctic Slimy Round Longnose
hauls grayling sculpin whitefish sucker
Kuparuk River
20.3
0.7
Middle Fork
2
28
3
3
0
Koyukuk River-
3
20
1
0
•j
Upstream
4
0
0
0
0
5
0
0
0
0
6
2
0
0
0
7
2
9
0.
5
0
5
181
a) Washington Creek aufeis field, 21 June 1977.
b) Washington Creek aufeis field, 21 June 1977. Note
sediment layer on ice inside cavern.
c) Oregon Creek aufeis field, 7 June 1977. Note sediment
layer on melting ice in foreground.
Figure 53. Potential migration blockages, aufe is fields at
Washington Creek and Oregon Creek, June 1977.
182
"^*Tr*"
■
a) Aerial view of Aufels Creek middle mined study area, 21
July 1977.
b) Aufeis Creek upper study area where surface flow disap-
peared for three years, 22 July 1977.
Figure 54. Region where Aufeis Creek went subsurface creating
migration blockage due to lack of surface flow.
183
existed at several additional sites, such as Washington Creek, Oregon Creek,
Penny River, and Skeetercake Creek, but a specific blockage was not ob-
served.
Creation of New Habitats
New aquatic habitat was created at eight sites where mined areas sep-
arated from the active channel were flooded subsequent to site closure.
These include the Dietrich River-Downstream and Jim River sites as well
as the pit sites at Penny River, Dietrich R i ver-Upstream, Prospect Creek,
West Fork Tolovana River, Tanana River-Downstream, and Tanana River-
Upstream. At the Dietrich River-Downstream site, a wide shallow backwater
was created in the spring immediately prior to the site survey, 3 years
after mining, and was quickly utilized by round whitefish and Arctic gray-
ling. Less mobile species, such as slimy sculpin, had not moved into the
area by the time of the survey (12-13 July) but would probably immigrate
into the mined area over the summer period. In the river, the most abundant
species was juvenile Arctic grayling; the second and third most abundant
were slimy sculpin and round whitefish. Removing gravel in an abandoned
channel at the Jim River site created a large pool habitat that contained a
high density of adult Arctic grayling during the summer. Other species
captured included juvenile Chinook salmon, burbot, and slimy sculpin. In the
main river, the catch was dominated by Arctic grayling.
The present configuration of the Penny River apparently resulted from
two separate periods of mining. Originally, the floodplain was scraped
adjacent to the channel. The channel subsequently diverted through the
scraped site and gravel was removed from the original channel, leaving a
shallow pit. During the site visit the present Penny River channel, formed
by flow diversion through the original scraped area, was heavily utilized by
Arctic char juveniles. The pit, created by excavating in the original chan-
nel, provided rearing area for coho salmon juveniles and spawning and rear-
ing areas for Alaska blackfish and ninespine stickleback. The catch in undis-
turbed areas was dominated by Arctic char and coho salmon with Arctic char
dominant in the spring and coho salmon dominant in the fall. The occurrence
184
of both species in undisturbed areas, compared to the single species dom-
inance in the mined areas, again reflects the reduced habitat diversity in
areas disturbed by gravel removal.
The Penny River pit provided coho salmon rearing habitat, which was lim-
ited in the river. Arctic char appeared to be more suited to the river
environment than coho salmon, and avoided the pit. The pit thus provided
ideal rearing conditions for coho with little competition from Arctic char.
There was a significant difference in size of coho using the pit as compared
to those using the river possibly indicating increased growth rate by those
in the pit (Tables 22 and 23). During the winter the coho left the pit and
moved to other areas where they possibly would be in direct competition with
char for space. If overwintering space is limiting in this river system, the
increased number of larger coho could lead to displacement and subsequent
reduction in the numbers of char. The Prospect Creek pit, a shallow pond
habitat previously not present in the immediate area, was used as a rearing
area by Arctic grayling, round whitefish, Chinook salmon, burbot, and slimy
sculpin, and also provided a feeding area for adult northern pike (Figure
55). In the upstream area of Prospect Creek the catch in 1977 was dominated
by round whitefish, Arctic grayling, and slimy sculpin listed in diminishing
order of abundance. In 1978 juvenile Chinook salmon appeared to dominate the
fish populations in the creek.
The Dietrich R i ver-Upstream pit and associated channels provided a
deep-water, spring-fed system utilized principally by adult Arctic grayling
and Arctic char while the main river contained juvenile Arctic grayling,
slimy sculpin, and round whitefish.
The West Fork Tolovana River pit contained extensive vegetated shallow
water areas which sloped off rapidly to deep water areas up to 6 m deep,
thus creating excellent spawning, rearing, and feeding areas for northern
pike and feeding areas for adult Arctic grayling (Figure 56). Arctic gray-
ling were the only species captured in the river during three sampling
trips, while northern pike were abundant in the pit. The only Arctic gray-
ling captured in the pit were adults longer than 225 mm; smaller Arctic
185
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187
Figure 55. Prospect Creek study site - shallow pond habitat
supporting Arctic grayling, Chinook salmon juveniles, round
whitefish, northern pike, burbot, slimy sculpin, 12
August 1978.
Figure 56. West Fork Tolovana River study site - deep pond
with extensive shallows providing northern pike and Arctic
grayling habitat, 29 July 1978.
188
grayling either were not entering the pit or were consumed by pike soon
after entering. Northern pike were apparently spawning in the pit because
many age-0 pike were caught or observed in the shallows throughout the
summer. During September, age-0 pike were observed in the river in a large
pool opposite the pit outlet, apparently moving from the pit to the river.
Thus, the pit may be increasing the number of pike in the river system in
general and, given the high density of age-0 and age-l Arctic grayling
observed in the river near the pit, may lead to a localized increase in the
density of river-dwelling northern pike near the pit. Studies by Alt (1970)
and Cheney (1972) indicate that movements of northern pike in the rivers of
the nearby Minto Flats region may not be extensive. On a small river, such
as the West Fork Tolovana River, a local increase in the northern pike
population may lead to local reductions in the Arctic grayling population.
The upper pit at the Tanana Ri ver-Upstream site had a similar habitat
and also provided a spawning, rearing, and feeding area for northern pike as
well as a feeding area for least c i sco and humpback whitefish (Figure 57).
On a large river, as at the Tanana Ri ver-Upstream pit, the effects of the
increased numbers of northern pike must be minimal when compared to the
river population. The main effect of a deep pit on this type of river system
is providing a clear water feeding area that increases the availability of
desirable species to sport fishing. The lower pit was a more uniform depth
with minimal littoral area and was used as a spawning and feeding area by
I ongnose sucker. The connection between the two pits, a shal low (8 cm deep)
stream, was used by longnose sucker fry, lake chub, and juvenile chum salmon
as a rearing area. The lower pit was also utilized as a feeding area by
humpback whitefish, least cisco, northern pike, and burbot.
The Tanana River-Downstream pit was a deep (maximum depth = 9.4 m)
Clearwater pit with apparently very low productivity. Fish species captured
in the pit were longnose sucker, Bering Cisco, and Chinook salmon. There
was no connection to the river, thus, the fish apparently immigrated during
high water and became trapped after the water level dropped.
189
a) Upper Tanana Ri ver-Upstream Pit, note extensive shallow
areas.
w
b) Upper Tanana R i ver-Upstream Pit
p i ke dens i t y .
- area of high northern
Figure 57. Tanana R i ver-Upstream upper pit showing extensive
vegetation beds, 18 August 1978. Note difference in the
extent of vegetative development in this 15-year old pit as
compared to the 2 and 3-year old pits in Figures 55 and 56.
190
Effects on Overwintering Areas
Possible effects of gravel removal on fish overwintering areas were
observed at several of the study areas. Potential overwintering areas were
created at the deep pit sites — Dietrich R i ver-Upstream, West Fork Tolovana
River, Tanana River-Downstream, and Tanana R i ver-Upstream — by the pits
themselves. The Dietrich R i ver-Upstream pit has been reported as an over-
wintering area (W. Anderson, personal communication to A. Ott). In addition,
outflow from the West Fork Tolovana River pit created a potential overwinter-
ing area approximately 50 m downstream from the outlet where a deep natural
pool with a 1-2 cm ice cover existed into March 1979. A possible overwinter-
ing area on the Penny River was altered as a spring-fed tributary; Willow
Creek, that had previously entered the main channel at a deep pool, now
entered the river through the scraped area in a series of shal low braided
channels (Figure 58).
The pattern of freezing observed during winter studies on six of the
pit sites indicated that fish entrapment was not a problem during the 1978-
1979 winter (Table 24). In those pits studied, the outlet remained open
well intowinter with outlet flow velocities increasing as the still water
at the edges of the pit froze, reducing the volume of the pit. Fish appeared
to move to the open water found at the outlet areas and the increased veloc-
ities may have induced the fish to move downstream to areas of reduced
velocity. If fish were holding at an outlet pool and the outlet closed
downstream from the holding fish, entrapment could occur. The outlet area in
the pits examined was general ly quite sma I I. However, the number of fish
affected compared to the numbers using the pit in the summer would be mini-
ma I .
The outlets of the Prospect Creek and Jim River sites remained open at
least until late January and possibly into early February, thus fish had
ample opportunity to emigrate as flow decreased during freeze-up. Fish were
present (caught and observed) at both sites in early November but were not
evident in late January. Both sites were frozen to the bottom in March. At
the Penny River pit site, fish were caught in the pit in late December and
ORIGINAL CHANNEL
WILLOW CREEK -
a) Willow Creek, a tributary of Penny River, stiowing flow diversion following
gravel removal operations, September 1975.
b) Willow Creek as it entered Penny River on 20 March J979.
Figure 58. Potential overwintering area at Willow Creek. Tti i s
spring-fed tributary, open throughout the winter, had pre-
viously entered Penny River at a deep pool.
192
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the outlet was flowing at that time. By March all flow in the pit had ceased
and the pit and outlet were frozen to the bottom. The spring-fed tributary,
Willow Creek, however, remained open and flowing into March, but fish were
not detected either in the tributary or in the Penny River downstream from
where the tributary entered the mined area. At West Fork Tolovana River, the
outlet was blocked at the time of the first winter visit, 29 November 1979,
because the deep, low velocity arm connecting the pit to the river was
frozen and the other arm flowed through a beaver dam. Flow out of the pit
through the beaver dam persisted through March (Figure 59). Fish were not
detected during any of the winter visits. There was sufficient water and
dissolved oxygen to support overwintering fish in mid-March 1979 and the
persisting outflow through the beaver dam indicates the pit may be receiving
some intergravel flow from the river.
The Tanana River-Downstream pit was visited only on 6-7 March 1979;
fish were not captured but as emigration after the previous September visit
was not possible, fish were probably present. The dissolved oxygen should
not have been depleted because of the depth, limited phy top I ank ton pro-
duction, and absence of littoral vegetation, and, in fact, was 6.0 mg/d- in
March (Table 24). At the two Tanana R i ver-Upstream pits, a more dynamic
pattern of freezing was observed. On 27-28 November 1978, the connection
between the two pits was frozen solid, thus isolating the upper pit. The
surface of the ice in the upper pit was approximately 1.5 m higher than the
surface of the lower pit. A burbot and possible lamprey were observed with
an underwater television system. The outlet of the lower pit was open to the
Tanana River with a school of juvenile salmon and two species of whitefish
holding in the outlet current. Burbot were captured by setline in the lower
pit. On 6-7 March 1979, the ice surface of the lower pit had risen to the
level of the upper pit and the connection between the two pits was open,
approximately 30 cm deep and flowing at about 0.1 m/sec into the lower pit.
The outlet to the lower pit was frozen solid. Dissolved oxygen at the upper
pit had increased from 3.4 to 6.0 ppm between November and March. Fish were
not detected in either pit in March.
195
•^
V
a) Flow out of beaver dam at pit outlet, 29 November 1978.
HjB™ V ■
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b) Deep pool (>l m) witti thin ice cover approximately 50 m
downstream from beaver dam, 15 March 1979.
Figure 59. Creation of a potential overwintering area at West
Fork Tolovana River downstream from pit.
196
The above observat i ons indicate that after November the outlet froze,
then the side channel of the Tanana River adjacent to the pit started flow-
ing through gravel into the upper pit, opened the connection between the two
pits and flowed back into the side channel through an intergravel pathway.
The raising of the surface of the lower pit appeared to have been caused by
overflow on top of the existing ice and snow. Oxygen depletion was a poten-
tial problem at the upper pit because of the dense stands of aquatic vege-
tation (the March 1978 dissolved oxygen was 3.2 ppm) but these were absent
in the lower pit and the dissolved oxygen was consistently higher than that
of the upper pit. The net effect was the creation of one and possibly two
overwintering areas, depending on the minimum winter oxygen levels at the
upper pit.
Assuming an adequate water depth, the main factor determining the
suitability of a pit as an overwintering area is an adequate level of dis-
solved oxygen through the winter. A pit with sufficient depth for over-
wintering but with an extensive, heavily-vegetated littoral area may ex-
perience an anoxic period following the initial snow cover. Barcia and
Mathias (1979) found that winterkill in eutrophic prairie lakes was closely
correlated to the mean depth of a lake and developed a method to estimate
the potential for winterkill based on the initial oxygen storage, rate of
oxygen depletion and the mean depth. The critical mean depth for the lakes
studied was approximately 2.0-2.5 m. Lakes with an average depth less than
2.0 m experienced regular winterkill, lakes 2.0-2.5 m experienced occasional
winterkill, and lakes with an average depth greater than 2.5 m generally did
not experience winterkill. The indications were that a productive pit with
an average depth of less than 2.5 m may have marginal uti I ity as an over-
wintering area, especially during years of early heavy snowfall.
The upper Tanana R i ver-Upstream and West Fork Tolovana River pits had
the characteristics to fit this type of pit (Table 14). The 6 m deep area in
the latter pit may have provided sufficient volume to maintain a suitable
dissolved oxygen level, but both of these pits should be considered marginal
overwintering areas. Intergravel flow from the adjoining river, however,
adding a continual supply of oxygenated water, could maintain sufficient
197
oxygen levels throughout the winter. The lower Tanana R i ver-Upstream pit did
not contain a great average depth, 1.7 m, but the lack of littoral vege-
tation reduced the probability of oxygen depletion. The water in the pit was
turbid during the summer, limiting production of aquatic vegetation. The
lower pit maintained higher dissolved oxygen than the upper pit during the
winter (Table 24). The Dietrich R i ver-Upstream and Tanana River-Downstream
pits both contained deep, clear water regions and did not have well-devel-
oped littoral vegetation. Oxygen levels probably remained high through-
out the year. The depth and lack of productivity combined to make these two
pits excellent overwintering areas; the same features limited their value as
rearing areas.
There are other possible effects of grave! removal on overwintering
areas, but they are difficult to assess because of the absence of data on
the study sites before gravel removal. A primary effect is the loss of
overwintering areas due to diversion of flow from an original channel, as
occurred at four sites (Penny River, Dietrich River-Downstream, Middle Fork
Koyukuk R i ver-Upstream, and Middle Fork Koyukuk River-Downstream). In these
cases, complete or partial diversion of flow could lead to loss or reduction
of overwintering habitat. Another effect is the loss of overwintering hab-
itat due to increased braiding and the associated changes — loss of pool-
riffle sequence and reductions in depth and velocity which promote rapid
freezing. In some areas, gravel removal created or aggravated the formation
of aufeis fields, thus leading to a reduction in water available for over-
wintering downstream (Washington Creek, Oregon Creek, McManus Creek, pos-
sibly some of the North Slope sites).
EFFECTS OF HABITAT ALTERATION ON AQUATIC MACRO I NVERTEBRATES
Observed Effects on Density and Species Assemblage
Habitat alterations expected to affect assemblages of riffle macro-
invertebrates would be changes in velocity, substrate, depth, and water
quality. During the present study, habitat alterations resulting in a change
of each of these parameters were accompanied by changes in the riffle com-
mun i ty (Tab I e 25 ) .
198
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201
Response to Substrate Alteration. The two types of substrate alter-
ations observed during the study (a shift to unstable substrate and change
from laminar to turbulent flow) significantly affected the total numerical
densities of aquatic macro i nver tebrates in the mined area as compared to
undisturbed areas (Table 26). At Washington Creek, Oregon Creek (June and
August), al I Penny River, Kuparuk River, and McManus Creek (May) site
visits, macro i nver tebr ate densities in mined areas were significantly less
than those in the upstream area. At al I five sites there was a shift from a
moderately compacted gravel substrate to a very loose, unconsolidated sand-
gravel substrate (Table 25). A similar habitat change at the Sagavan i rk tok
River and Ivishak River sites resulted in a significant increase in the
density of aquatic macro i nver tebr ates. In five of the eight cases in which
there were total density decreases, there were density reductions in the
ephemeropt eran genus Cinygmula while in seven of the eight cases, there were
reductions in the dipteran family Ch i ronomi dae. The density increases at the
Sagavan irk tok River and Ivishak River sites both contained density increases
in the ephemeropt eran subfamily Baetinae and dipteran family Ch i ronomi dae,
as we I I as some other taxa.
At two sites there was a change from laminar flow to turbulent flow
caused by substrate alteration. At both Ugnuravik River and Shaviovik River
sites, there was a significant decrease in total macro i nver tebr ate density,
primarily because of a decrease in Simuliidae densities. At Ugnuravik River,
the laminar flow was in the upstream (control) area, while at Shaviovik
River, laminar flow occurred in the mined area.
At three of the five sites where there were decreased densities in the
mined area (Washington Creek, Oregon Creek, McManus Creek) there were also
aufeis fields associated with the mined area (Table 25). All three sites
were visited early in the summer so that any aufeis effects would have been
measured at their greatest magnitude. Later visits at two of the sites
(Oregon Creek, McManus Creek) indicated that densities in the mined area
increased to levels similar to those in the upstream areas. At Oregon Creek,
the summer recovery from aufeis effects was not complete for population
densities of Nemoura and Cinygmula, which remained below the densities
202
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reached by the same genera in the upstream area. The August and September
population densities of Capnia and Baetinae, however, exceeded those re-
corded in the upstream area.
At McManus Creek, the mined area densities of Oligochaeta and
Rhyacophila did not reach those recorded in the upstream area; the mined
area densities of Alloperia, Ch ironom i dae, and Tipulidae exceeded the up-
stream area densities on each of the two succeeding trips. The failure of
the mined area densities of some taxa to reach upstream densities, while
those of other species exceeded the upstream densities, indicated that there
was a long-term habitat alteration which has led to an alteration in species
composition of the mined area. Another site which showed a similar response,
but where an aufeis field was not identified, was the Penny River site,
where mined area densities of Oligochaeta, Nemoura, C i nygmu I a, Ch i ronomi dae,
and others were general ly lower than upstream densities. In the Penny River
mined area, population densities of Tipulidae and, at times Capnia,
Baetinae, Ephemerella, and Athericidae were higher than those in the up-
stream area. The shift in taxa at the above sites appeared to be related to
the occurrence of unstable substrate possibly aggravated by an aufeis field.
Other sites with a similar substrate alteration (Washington Creek,
Kuparuk River) also showed density reductions of most organisms but the site
was only visited once and this precluded any analysis of recovery or sea-
sonal patterns. At Kuparuk River, densities of al I species were lower in the
mined area than in the upstream area while at the Washington Creek upper
mined area, only Tipulidae densities exceeded those in the upstream area. In
summary, certain taxa, primarily Oligochaeta, Nemoura, Cinygmula, and
Chironomidae were reduced in areas of unstable substrate while others,
primarily Tipulidae, but also Capnia and Baetinae, showed increased den-
sities.
Response to Increased Braiding. Aquatic macro i nvertebr ate responses to
these alterations were colonization by taxa which are more suited to lower
velocity waters with higher organics. Clinging ephemeropt erans, as found in
the family Hept agen i i dae (Cinygmula, Epeorus), were replaced by sprawlers
204
and climbers, e.g., Baetidae. Tr i chopferans often increased in these areas
and the dipteran family Tipuliidae was often associated with the finer
sediments found in mined areas. At two sites on large rivers showing in-
creased braiding as well as altered substrate ( Sagavan i rk tok River and
Ivishak River) there was an increase in the density of virtual ly al I taxa in
the mined area as compared to the upstream area (Table 24). The riffles in
the mined area in these two cases were in sma I I shal low channels with exten-
sive riffle area while the riffles in the upstream area were in large chan-
nels, were less extensive, and composed of a more coarse material. The
riffles in the mined area had greater detrital accumulation, and the de-
creased depth and velocity associated with the braided areas may have
allowed greater periphyton production. Such a situation would increase the
quality of the habitat for most of the species unless a critical parameter,
such as velocity, had been lost or altered. The increased braiding at other
sites, such as Oregon Creek and Penny River, may have contributed in a
similar manner to the altered species composition.
The increased braiding at many of the sites led to changes in the water
temperature and dissolved oxygen in the mined area. An examination of the
seasonal variation in the riffle macro i nvertebrates at Aufeis Creek revealed
a pattern of density changes which indicated a possible effect of the al-
tered temperature and dissolved oxygen regime on the apparent densities of
certain macro i nvertebrates (Figure 60). In the ephemeropt eran taxa, Baetinae
and C i nygmu I a, the densities in the upstream area increased from the July to
August trip while those in and below the mined area decreased. Simuliidae
densities decreased between the two trips in the upstream area with simu-
liids absent in and below the mined area in August. The temperature at the
area between the two mined areas was 2.8 C (July) and 1.2 C (August) higher
than that in the upstream area. The immature stages of the three taxa ap-
parently emerged earlier in the areas affected by gravel removal than in the
unaffected upstream area. The altered water quality parameters may have
altered the emergence times of these three taxa because temperature and
dissolved oxygen can affect developmental rates (Hynes 1972).
205
5000
1000
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100
E 50
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Shaded - Upstream Area
Half- Shaded - Upper Mined Area
Open — Between Mined Area
July
August
Figure 60. Densities of selected aquatic macroi nver tebrates at Aufeis Creek
study areas during 1977 sampling trips.
206
An indication of a similar effect was seen at McManus Creek where
Alloperia nymphs were present in the upstream area in densities exceeding
those in the mined and downstream areas. An emergence of adult plecopterans
was occurring in the mined area during the site visit, however, and this
probably caused the reduced densities of nymphs. Thus, the low nymphal
densities of Alloperia in the mined and downstream areas may have resulted
from an earlier emergence time rather than a lack of suitable habitat. The
observed density differences between upstream and mined areas, at sites
which were only sampled once, must be viewed with caution because of the
possibility that emergence periods were altered due to an altered thermal
regime. A major period of emergence may have occurred in one area just prior
to the site visit, thus leaving the area with low densities relative to an
area with a later emergence period. At present there is not enough infor-
mation on the natural emergence patterns, and the effects of temperature and
dissolved oxygen on those patterns, to predict how the arctic macro i nver te-
brate species would respond to changes in these habitat parameters.
Creation of Pond Habitat. The creation of pond habitats al lowed aquatic
macro i nver tebrates typically found in a lentic habitat to colonize these
areas (Table 27). In these cases the change was from terrestrial to aquatic
habitat so there was not a direct effect on river communities. Indirect
effects could be enrichment of downstream communities by phy top I ank ton and
nutrients being carried out of the pit. The Southern Interior deep pits
(West Fork Tolovana River, Tanana River-Downstream, Tanana R i ver-Upstream)
had a higher diversity of organisms than the pits in other regions, probably
reflecting a more stable habitat. The age of the pit did not seem to exert
much effect because the West Fork Tolovana River and upper Tanana River-
Upstream pit both had similar configuration and similar fauna and density
but the former was 10 years newer than the latter. The low productivity of
the Tanana River-Downstream pit was evident; the density of chironomids at
the Tanana R i ver-Upstream pits, about 50 km upstream, was 5 to 20 times
greater than those at the downstream pit at a similar time of year.
207
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SUMMARY AND CONCLUSIONS
EFFECTS OF GRAVEL SCRAPING ON RIVERINE HABITATS
Gravel removal by scraping in floodplains resulted in a number of
alterations to aquatic habitats with the biota showing a variety of re-
sponses to these habitat alterations. Important habitat alterations in-
cluded: (I) the creation of braided channel areas with associated changes in
various habitat parameters, (2) removal of bank and instream cover, (3)
increased habitat diversity, (4) creation of potential migration blockages,
and (5) creation of potential entrapment areas.
Increased Braiding Characteristics
This habitat alteration occurred at 15 study sites where active channel
deposits were scraped to below the water line or where flow subsequently
increased to inundate the mined area. The main effect of braiding on spe-
cific habitat parameters was to reduce velocity and depth by spreading flow
over a wider area. The populations of both aquatic macro i nvertebrates and
fish utilizing these areas were altered with shifts in species and life
history stages. The reduction in velocity led to increased detrital accum-
ulation, deposition of fine materials, and often altered the temperature and
dissolved oxygen regime. The altered temperature regime led to altered
emergence periods of aquatic insects; the effect of this alteration on
reproductive success and overall population stability is unknown.
Fish populations responded to increased braiding in a number of ways,
but the general pattern was a reduction in the diversity of the fish com-
munity. The number of species and age groups usually decreased in the braid-
ed areas.
209
The increased braiding also increased the probability of aufeis forma-
tion in the mined areas. This effect was documented at Washington Creek and
Oregon Creek and was indicated at McManus Creek and Penny River. There may
have been additional ice formation at some of the North Slope sites, such as
Kuparuk River, Sagavan i rk tok River, and Ivishak River. The formation of
aufeis fields seemed to prolong the recovery of the site as the channels and
substrate remained unstable and siltation persisted during the melting
process. In addition, the water needed to create the aufeis field became
unavailable downstream, thus reducing water available for overwintering,
often the factor limiting fish populations in arctic rivers.
Removal of Bank and Instream Cover
Reduction of bank cover occurred whenever a portion of incised or
undercut bank was removed. At sites with this habitat alteration, the bank
was scraped to remove overburden in order to access underlying gravel de-
posits. The former bank with cover was changed to a gravel bar following
removal operations. Certain species, such as Arctic char and Arctic grayling
were strongly associated with bank cover and the loss of this cover led
to reduced population densities in the mined areas. Similarly, loss of
instream cover led to reduced densities in mined areas.
Increased Habitat Diversity
Habitat diversity increases were documented at three scraped sites, but
these were viewed as temporary increases at newly inundated sites. The
habitat diversity will decrease as braiding characteristics are established,
the channel cutoffs are completed, and the habitats become more uniform.
Migration Blockages
The combination of increased wetted perimeter and decreased depth
in mined areas created a situation that could lead to migration blockages
during periods of low flow. Such a situation occurred at the Aufeis Creek
site and possibly could occur at the Nome River site. The potential for
210
migration blockage was present at sites, including Oregon Creek and
Washington Creek, where the entire active channel was scraped. Because of
the known complexity of fish movements throughout arctic watersheds, migra-
tion blockages can have a significant, but as yet unstudied, effect on
popu I at i ons.
Potential Entrapment Areas
The potential for fish entrapment was high at areas with extensive
backwater, as was found at newly inundated areas (Dietrich River-Downstream,
Middle Fork Koyukuk R i ver-Ups tream) and areas with increased braiding (many
sites, including Sinuk River, Kuparuk River, Sagavan i rktok River, Ivishak
River, and Middle Fork Koyukuk River-Downstream). At these sites, areas of
ponded water became isolated from the active channel as the water level
dropped, trapping fish and invertebrates that had moved or been carried into
these depressions during the high water. Mortality of stranded fish and
invertebrates is assumed to be high because they are subjected to high
summer water temperatures, low dissolved oxygen, increased predation from
terrestrial predators, winter freezing, and total loss of aquatic habi-
tat as the isolated pools often dry up if the river continues to drop.
EFFECTS OF INUNDATED PIT FORMATION ON THE ASSOCIATED RIVER BIOTA
The direct effects of pit excavation on the river biota were difficult
to assess because the river habitat was not directly affected; inundated
pits were created from previously terrestrial habitat. Because of this, the
pits represented a new habitat and the fauna inhabiting the pits was con-
siderably different from that inhabiting the associated river.
Summer Utilization by F i sh
Two of the pits, Dietrich Ri ver-Upstream and Tanana River-Downstream,
were deep clear water pits with low productivity and fish utilization. At
Tanana River-Downstream this low utilization was easily explained because
there was no connection to the river and immigration into the pit occurred
21
only at infrequent h i gti water levels. The Dietrich Ri ver-Upstream pit,
however, was connected to the active channels but fish were apparently not
utilizing the pit for feeding. Benthic macro! nvertebrate densities in both
these pits were low when compared, to those of other pits. The spring-fed
channels upstream from the Dietrich River pit were utilized by adult Arctic
grayling and the pit itself was reported to be an overwintering area. All
other pits were highly productive and heavily utilized by fish as summer
rearing areas. The shallow pits. Penny River, Prospect Creek, and Jim River
side channel (this site had some characteristics of a pit) supported high
densities of juvenile salmon (coho in the Penny River, chinook in the latter
two) as well as some species associated with both a lacustrine environment
(Alaska blackfish, burbot, northern pike) and stream environment (round
whitefish, Arctic grayling, slimy sculpin). The productive Southern Interior
deep pits. West Fork Tolovana River and two Tanana R i ver-Upstream, contained
a more lacustrine fish fauna with northern pike dominating the fauna and
humpback whitefish, least cisco, and burbot also present in the Tanana
R i ver-Upstream complex.
Potential for Winter Mortality and Winter Survival Areas
The creation of shallow pits and subsequent heavy summer usage by fish
created the possibility for entrapment during freezeup and subsequent winter
mortality when the pit freezes solid or decay of vegetation consumes the
dissolved oxygen. The pattern of freezing observed during winter studies
indicated that during the year of observation, entrapment was minimal and
probably not a significant problem.
The creation of deep pits connected to the river could create over-
wintering areas; this was documented or suggested at several study sites.
All pits studied, with the exception of Tanana River-Downstream, however,
had a mean depth insufficient to preclude winter mortality. Intergravel flow
appeared to maintain the ability of some pits to support winter fish sur-
vival, but this is an unpredictable factor in the design of pits.
212
RECOMMENDATIONS
I. It is recommended that mining practices leading to an increased braided
configuration be avoided. This is best achieved by avoiding active channels
and by mining above the water table.
2. Undercut and incised vegetated banks should not be altered.
3. Critical habitats, such as spawning and overwintering areas should be
avo i ded.
4. Formation of isolated ponded areas that cause entrapment should be
avoided by contouring and sloping to provide drainage.
5. Pits should be excavated to a sufficient depth to preclude winter mor-
tality. Generally, a mean depth of at least 2.5 m should ensure winter sur-
vival .
213
REFERENCES
Alt, K. T. 1970. Sheefish and pike investigations of the upper Yukon
and Kuskokwim drainages with emphasis on Minto Flats drainages. Alaska
Dept. of Fish and Game. Fed. Aid in Fish Restoration, Annu. Prog. Rept.
1969-1970, Proj. F-9-2, 11:32 1-330.
Barcia, J., and J. A. Mathias. 1979. Oxygen depletion and winterkill
risk in small prairie lakes under extended ice cover. J. Fish, Res. Bd.
Canada 36(8) :980-986.
Binns, N. A., and F. M. Eiserman. 1979. Quantification of fluvial trout
habitat in Wyoming. Trans. Am. Fish. Soc. 108 ( 3 ): 2 I 5-228.
Bovee, K. D., and T. Cochnauer. 1977. Development and Evaluation of
Weighted Criteria, Probab i I i ty-of-Use Curves for Instream Flow Assess-
ments: Fisheries. Instream Flow Information Paper I^o. 3. Coop. Instream
Flow Serv. Group, Fort Collins, Colorado. 39 pp.
Cheney, W. L. 1972. Life history investigations of northern pike in Tanana
River drainages. Alaska Dept. of Fish and Game. Fed. Aid in Fish Res-
toration. Annu. Prog. Rept. 1971-1972, Proj. F-9-4, 13:1-30.
Hynes, H. B. N. 1972. The Ecology of Running Waters. University of Toronto
Press, Toronto, Canada. 555 pp.
Nie, N. H., C. H, Hull, J. G. Jenkins, K. Ste i nbrenner , and D. H. Bent.
1975. Statistical Package for the Social Sciences. Second Edition.
McGraw-Hill, Inc. 675 pp.
Stalnaker, C. B., and J. L. Arnette (eds.) 1976. Methodologies for the
Determination of Stream Resource Flow Requirements: An Assessment. Utah
St. Univ., Logan, Utah. 199 pp.
Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska. U. S. Fish
and Wildlife Service. FWS/OBS 76/21. Wash. D. C. 127 pp.
Zar, J. H. 1974. Biostatical Analysis. Prent i s-Ha I I , Inc. Englewood
Cliffs, N. J. 620 pp.
214
EFFECTS OF GRAVEL REMOVAL ON TERRESTRIAL BIOTA
M. R. Joyce
INTRODUCTION
The ecological importance of floodplain and riparian terrestrial habi-
tats in temperate regions has been well documented in the ecological litera-
ture. These habitats, particularly the riparian zones, have high primary and
secondary biological productivity and typically support a diverse and abun-
dant flora and fauna. These biotic zones frequently provide temporary and
permanent refuge for many of our rare and endangered species. The signifi-
cance of these floodplain and riparian habitats has recently been recognized
and incorporated into the management plans of several Federal agencies
(Johnson and Jones 1977; U.S. Army Corps of Engineers 1979).
Arctic and subarctic floodplain and riparian habitats are no less
significant in their importance and ecological value. The riparian zones
develop dense shrub thickets dominated by willows and alder in all four
study regions. Overstory forest dominated by white spruce and paper birch
also frequently inhabit the riparian zones of the Northern and Southern
Interior regions. (Scientific nommenc I a t ure for terrestrial flora and fauna
is presented in Appendix A.) High primary productivity in these zones pro-
vides optimum feeding, nesting, and cover habitat for a diverse fauna usu-
ally dominated by small mammals and passerines. These riparian habitats in
interior Alaska frequently support over 100 birds per 40 ha during the
nesting season (Spindler and Kessel 1979). Some birds, such as the yellow
warbler and northern waterthrush, very seldom nest in habitats other than
riparian shrub thickets. These zones also are preferred habitats for tundra
voles and singing voles. The more dense riparian shrub thickets provide
critical feeding and cover habitats for moose and ptarmigan during winter.
215
The unvegetated and sparsely vegetated areas within arctic and sub-
arctic floodplains provide equally valuable habitat for a different segment
of fauna. Many of the major floodplains provide key migratory corridors for
large numbers of waterfowl, shorebirds, and caribou moving to and from
wintering zones and summer nesting and calving territories. Unvegetated
areas of larger floodplains are used as prime nesting and feeding habitat by
numerous shorebirds, gulls, terns, and waterfowl. The delta areas of larger
rivers also are prime Juvenal rearing habitats for shorebirds and waterfowl.
Along coastal regions, these river deltas also are key nesting sanctuaries
for geese, brant, swans, gulls, terns, and shorebirds, and during late
summer and early fal I they provide protected habitat for large concentra-
tions of molting waterfowl. Due to the high secondary productivity of these
areas, predators including bears, wolves, eagles and jaegers also frequently
concentrate their feeding activities along floodplains.
Unfortunately, from a biological viewpoint, floodplains also provide
easily accessible gravels that are available in large quantities and fre-
quently close to development sites. As previously noted, arctic and sub-
arctic conditions, primarily associated with the presence of permafrost,
place large demands upon gravel resources by all development projects.
During the construction of the Trans-Alaska Pipeline System, over 3,300
ha of unvegetated floodplain habitat and approximately 1,000 ha of riparian
habitat were affected by gravel removal operations (Pamplin 1979). The
proposed construction of a gas pipeline through Alaska, depending upon final
route selection and the degree of use of existing construction facilities,
could require similar gravel supplies. Other development projects are expec-
ted to increase the future demand upon gravel resources.
Previous to this study, natural resource managers had little indepth
knowledge, relative to arctic and subarctic terrestrial floodplain eco-
systems, of how to best mitigate the use of floodplains as gravel removal
sites. The short-term effects of gravel removal operations were believed to
be associated with reduction of habitat, probable decrease in local fauna
population sizes, and potential indirect effects through reduced habitat
quality in adjacent and downstream habitats. However, the variations in the
216
levels of influence and the durations of influence between differing grave!
removal sites and methods of operation were not completely known. Also,
there were no data on long-term effects in the arctic or subarctic. Factors
such as the size and location of the site, and the characteristics of the
stream and floodplain were believed to be influencing parameters, but their
relationships to short-term and long-term detrimental effects were not
understood.
To help answer these questions, a terrestrial study was incorporated
into this project. The study was designed to be compatible with the hydrol-
ogy and aquatic biology programs and organized to provide answers on: (I)
the degree of flora and fauna change resulting from gravel removal opera-
tions; (2) the rate of habitat recovery at disturbed sites respective to the
characteristics of the gravel removal operation and the characteristics of
the river and floodplain system; and (3) how the detrimental affects of
gravel removal operations could best be mitigated.
217
METHODS OF DATA COLLECTION
As previously described in APPROACH AND METHODOLOGY, terrestrial data
were collected at all 25 study sites, with individual site visits occur-
ring either during the summer of 1976, 1977, or 1978. Standard procedures
were used to collect field data on flora, soils, birds, and mammals.
Site locations are identified on Figure I. Sites occurred on the Seward
Peninsula, North Slope (in both the coastal plain and Arctic foothills).
Northern Interior (between the Brooks Mountain Range and Yukon River), and
Southern Interior (between the Alaska Mountain Range and the Yukon River).
One study site, selected as being most representative with respect to river
type and biological conditions in each regional study area, was sampled
during a 5-day visit. We attempted to coincide this visit with the peak of
the avian nesting season. All other sites were surveyed during a 3-day
visit. Within each region, the 3-day visits were spaced throughout the
spring, summer, and fall to measure seasonal fluctuations in species compo-
sition and abundance.
The selected approach to meet the objectives of this project was to
document the presence and establish the habitat relationships of the flora
and fauna of the disturbed area and compare these to pred isturbance flora
and fauna populations and habitat affinities. A control area which was most
representative with respect to physical site characteristics (i.e., inside
or outside meander) and habitat characteristics (i.e., dense riparian shrub
thickets, or unvegetated f I oodp I a i n ) was selected to establish pre-gravel
removal biological conditions and flora-fauna relationships. In addition,
surveys were conducted in floristic serai stages representative of the
disturbed area during the time of the field visit, and in serai stages
representative of anticipated future disturbed-area vegetative development.
218
These areas were surveyed to identify flora-fauna re I at i onsti i ps during
various site recovery stages.
The Major Variable Matrix Table (Table I) identifies the variety of
sites studied. Study sites varied from large braided rivers to small,
single-channel streams located in four major geographical regions of Alaska.
Selected sites were studied from 2 to 20 years after disturbance, allowing
data gathering on short-term and long-term response and recovery by the
terrestrial biota. Characteristics of gravel removal areas included: scrap-
ing operations of surface gravels within and adjacent to active channels;
scraping in areas separated from the active channels; and pit excavations
separated from active channels. This range of sites allowed comparison of
the effects of different techniques and site locations on terrestrial biota.
219
METHODS OF DATA ANALYSIS
Data analysis initially resulted in the identification of the degree of
change in measured parameters at each study site. A numerical rating ranging
from 0 to 10 was assigned to indicate an increase (ratings 10 through 6), no
change (rating of 5) or a decrease (ratings 4 through 0). These ratings
indicate the degree of change at the time of the site visit between the
pre-gravel removal conditions (i.e., extent of shrub thicket cover, or
number of passerines present) and the post-gravel removal conditions. Each
numerical unit increase (6 through 10) or decrease (4 throijgh 0) approxi-
mates an alteration similar to a 20 percent level of change in that param-
eter.
Each site was analyzed to determine how measured parameters (vege-
tation, soils, birds, and mammals) interacted, and how they responded as a
whole to the Physical Site Characteristics (such as river size and config-
uration) and Gravel Removal Area Characteristics (such as type and location
of gravel removal). After individual site analysis, all sites were compared
to evaluate similarities and differences in the degrees of change in biolog-
ical parameters.
Fauna directly respond to the presence (and type) or absence of vegeta-
tive development, consequently, the degree of change and the rate of re-
covery at the gravel removal sites received major emphasis in the vegetative
data analysis. Factors that influence vegetative recovery (e.g., soil con-
ditions and aufeis development), also were thoroughly reviewed.
Selected biological data were subjected to a computerized hierarchical
clustering routine to identify similar responses in a measured biological
220
parameter between rivers. This analysis grouped similar sites and similar
responses (increase or decrease) by biological parameters.
All data were thoroughly reviewed to identify any correlations between
Physical Site Characteristics, Gravel Removal Area Characteristics, degree
of change by the terrestrial biota, and short-term and long-term recovery
rates. The following sections include the results of data collection and
analysis.
221
RESULTS AND DISCUSSION
Changes in selected terrestrial parameters ttiat were induced by gravel
removal are identified in Table 28. These changes were based upon measured
levels of variation in each parameter at each site. In general, the degree
of both short-term and long-term changes in local faunal communities strong-
ly reflected the extent of disturbance to floodplain and riparian vegetative
commun i t i es.
VEGETATIVE COMMUNITIES OF STUDY AREA FLOODPLAINS
Vegetative communities of floodplain and riparian zones at the study
sites were typical of those occurring throughout arctic and subarctic
regions. In general, the Seward Peninsula rivers and the smaller North Slope
rivers usually were meandering or sinuous in configuration with well-defined
(incised) outside meander banks (Figure 61). This configuration and profile
created a relatively narrow floodplain (30 to 60 m) and al lowed extensive
development of mature shrub thickets adjacent to single channel rivers.
These shrub thickets usual ly were dominated by Sa I ix a I axensi s. On Inside
meanders (point bars) and in more active portions of floodplains (lateral
and mid-channel bars) herbaceous, woody pioneer and early willow communities
occurred adjacent to unvegetated gravels bordering the river.
Meandering and sinuous rivers of the Northern and Southern Interior
were similar in pattern and were characterized by extensive shrub thickets
with dense stands of advanced and mature successional stage boreal forest
communities at the edges of active floodplains (Figure 62). White spruce
usually dominated these stands, but paper birch and balsam poplar also were
common. Similar pioneer and early shrub successional stage communities
occupied point bars and edges of lateral and mid-channel gravel bars.
222
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223
Figure 61. Penny River undisturbed floodplain showing typi-
cal North Slope and Seward Peninsula floodplain character-
istics of sinuous channel bordered with dense shrub thick-
ets with incised outside meander bank, and narrow gravel
point bar on inside meander.
Figure 62. West Fork Tolovana River showing typical South-
ern and Northern Interior medium river floodplain character-
istics with shrub thickets and white spruce-paper birch
stands along the riparian zone.
224
The larger rivers within all four regions typically flowed in braided
or split channel configurations. These floodplains were more hydr au I i ca I I y
dynamic, with much wider active areas, and contained advanced serai stage
vegetative communities only along floodplain borders and on isolated mid-
channel islands. Much of the floodplain in these large, braided rivers
contained expansive areas of unvegetated gravels or were sparsely vegetated
with herbaceous and woody pioneer or early shrub thicket communities.
This very briefly describes In general terms the normal vegetative
patterns of floodplains in the area of study. For a more detailed descrip-
tion of normal patterns, refer to the "Preliminary Report Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska" (Woodward-Clyde
Consultants 1976) and for a detailed description of the vegetative structure
which occurred at each study site refer to the Project Data Base.
VEGETATIVE COMMUNITY CHANGES AT GRAVEL REMOVAL SITES
The observed changes in vegetative communities of the study sites
varied from no significant change to long-term loss of habitat. Habitat loss
and alteration (both short-term and long-term) repeatedly resulted in signif-
icant secondary changes within the bird and mammal populations that inhab-
ited study area floodplains. These faunal responses are discussed in a
fo I lowi ng sect i on.
Significant areas of existing floodplain vegetative cover were removed
at 18 of the 25 sites (Table 28). Lost vegetative habitats usually consisted
of mature shrub thickets on the Seward Peninsula and North Slope sites, and
a mixture of shrub thickets and advanced successional stages of boreal
forest floodplain communities in Northern and Southern Interior regions. At
all sites these habitats supported a diverse and abundant fauna dominated by
passerines and sma I I mammals prior to clearing and gravel removal activ-
ities. Refer to the Project Data Base for a complete listing of recorded
flora and fauna at each study site.
Vegetative habitat removed at these 18 sites averaged 10 ha and ranged
from approximately I ha at Gold Run Creek to 35 ha at Dietrich River-
Upstream (Tab le 28) .
225
In general, sites separated from the active floodplain frequently
disturbed the most vegetative habitat as a percentage of the total disturbed
area. For example, Table 28 identifies seven sites that were entirely (100%)
vegetated prior to gravel removal and all were separated from the active
floodplain. At all seven sites vegetative cover and associated organic
overburden were completely cleared prior to gravel removal.
Long-Term Loss of Vegetative Habitats
Long-term loss of terrestrial habitat occurred at those sites where:
(I) the gravel extraction method (either pit excavation or deep scraping)
removed gravel to depths that resulted in permanent flooding; or (2) the
specific site location and material site characteristics resulted in river
hydraulic changes which annually affected the site.
Permanently Flooded Material Sites. Eight of the study sites were
excavated pits, either totally or in part (Figure 63). Pits varied from an
Figure 63. West Fork Tolovana River showing permanently
flooded pit excavated adjacent to the active floodplain
with a downstream connection.
226
average of 1.5-m in depth at the Penny River to over 7 m deep at the
Dietrich Ri ver-Upstream, West Forl< Tolovana River, and Tanana River-
Downstream sites. The pits were either connected or unconnected to adjacent
active river channels, however, in all cases they were permanently filled
with ponded water (Figure 63). Surface areas ranged from 7.5 ha at Tanana
Ri ver-Upstream to 0.1 ha at Ugnuravik River. Six of the eight sites were
separated from the active floodplain and were completely vegetated with
mature white spruce-paper birch and/or willow and alder shrub thickets prior
to excavation. At these sites the depth and subsequent flooding created
aquatic habitats that led to long-term loss of terrestrial habitats. At the
two other pit sites, the excavations occurred in unvegetated point bars
(Ugnuravik River) and unvegetated lateral bars (Kavik River). Thus, no
vegetated habitat disturbance occurred.
Excavation of deep pits, however, was not the only gravel removal
method that led to development of permanently ponded water and consequently
the long-term loss of terrestrial habitats. The combined gravel removal and
site location characteristics at the Jim River and Dietrich River-Downstream
sites also led to permanent ponding.
At the Jim River, gravel was scraped from within and immediately adja-
cent to a high-water channel. The resulting profile at the completion of the
scraping operation resulted in an almost circular depression in the middle
of the worked area. The high-water channel traversed this depression. Since
this channel carries summer flow, it consequently had formed an annually
ponded area of approximately 4.5 ha over this centrally depressed portion of
the II ha site. Before clearing and gravel removal, with the exception of
the approximately lO-m wide high-water channel, this site contained a di-
verse complex of mature and intermediate-aged white spruce-paper birch
stands with scattered willow and alder thickets.
The Dietrich River-Downstream site was scraped to an average depth of
I to 1.5 m in a rectangular shaped 7.5 ha. The area was separated from the
active floodplain by approximately 150 m prior to the activity. However, the
depth of excavation was the probable cause of a permanent channel change by
a major side channel of the Dietrich River. This channel entered the pre-
227
viously dry site during the second spring breakup following the activity.
This channel change caused flooding of approximately 90 percent of the
material site. This condition will remain as long as this side channel flows
through the site.
Thus, at both the Jim River and Dietrich River-Downstream sites, mining
depth and site location characteristics also created permanently ponded
aquatic habitats which will lead to long-term loss of terrestrial habitats.
Annual Hydraulic Stress. In addition to the creation of permanently
ponded sites, long-term loss and alteration of habitat occurred at sites
where the gravel removal operation resulted in significant changes in river
hydraulics. Examples of such changes include shifted channels, annually
flooded sites, and aufeis development within the material site.
On the Seward Peninsula, the Penny River and Oregon and Washington
Creeks are small rivers with relatively narrow, densely vegetated flood-
plains. Penny River and Washington Creek flowed in a sinuous configuration,
while Oregon Creek flowed in a straight configuration. The portion of the
total disturbed area which was vegetated by dense, mature shrub thickets
prior to disturbance at each site was extensive (Oregon Creek 65 percent;
Penny River 80 percent; and Washington Creek 85 percent) (Table 28). At all
three sites, the working area (which was scraped to a level equal to or
slightly below normal water levels) extended across the entire floodplain
and at Washington and Oregon Creeks the disturbed area extended approxi-
mately 9 to 15 m beyond the floodplain banks and into the adjacent shrub-
tussock tundra. The resulting effect of these scraping operations created:
an unvegetated, flat floodplain which was 2 to 3 times wider than upstream
or downstream reaches; a floodplain that was equal to, or only slightly
higher in elevation (10 to 20 cm on the average) than normal summer flows;
and a wider channel with increased braiding, straighter configuration and
shallower flow (Figure 64).
The effects of these induced hydraulic changes created direct impedi-
ments to vegetative recovery and thus they also resulted in long-term altera-
tion of the habitat structure of the disturbed reach in these floodplains.
228
Figure 64. A view of Oregon Creek looking downstream
through the mined area showing site conditions that remain
13 years after gravel removal.
The specific changes that retarded vegetative recovery and development at
these sites were related to induced aufeis development and increased annual
high-water stresses.
At Washington and Oregon Creeks, extensive aufeis fields annually
developed within the material sites. This ice, which is known to last until
late June throughout the disturbed areas, severely impeded vegetative recov-
ery at these sites. No significant vegetative communities had developed
within the disturbed areas of either site during the 13 years following the
gravel removal operations.
There is no evidence of aufeis development at the Penny River site.
However, the area was scraped in an irregular surface pattern over 15 ha to
a depth equal to or slightly below normal summer flow levels (Figure 65).
The site was visited II years after gravel was removed. As a result of the
depth of scraping, much of the site contained either small pools of ponded
229
Figure 65. Penny River mined area looking upstream. Note
the flooded conditions within the disturbed area, and
the overburden piles in the center of the site (circled
on photograph ) .
water or water saturated soils. A small 0.6 ha, 1.5 m deep pit was dug in
the southeast corner of the site. The hydraulic analysis shows that the
Penny River site is flooded for short durations during higher flows on an
annual and possibly semiannual basis. Flows of only approximately 150 per-
cent of mean annual flow begin to flood the material site.
During the II growing seasons following the disturbance, only sparse,
scattered pioneer and early willow floodplain communities had developed
within the scraped portions of the Penny River site. These early succes-
sional habitats were not present in the undisturbed floodplain reach which,
as previously stated, consisted almost entirely of mature shrub thickets.
Thus, the structure of the vegetative community within the mined site
changed for the long-term from one dominated by dense mature shrub thicket
habitats to one dominated by scattered and low-density immature herbaceous
and woody species that are adapted to wet soil conditions. Repeated stress
from annual or semiannual high water, combined with the continuously
230
water-saturated soils over much of the Penny River site, were probably the
key factors impeding vegetative recovery (especially by woody species).
Another example of gravel removal and site location characteristics
which resulted in known short-term (the site was visited 3 years after
disturbance), and probably long-term annual hydraulic stress occurred at the
Sagavan irktok River study site. At this site 20 ha of a complex mixture of
mature and advanced, seral-stage shrub thickets was removed and the under-
lying gravels excavated to an average depth of 1.5 m. This area was located
between a high-water channel and the main river channel. The Sagavan irktok
River was a large river with moderate channel slope that flowed in a sinuous
conf i gur at i on .
This gravel removal operation resulted in a permanent shift of much of
the main channel through the material site. Hydraulic analysis at this
site shows that extensive flooding is expected to occur on an annual basis
with water potentially influencing the site for up to 70 days each year.
The site was visited during the third growing season after disturbance,
and no vegetative recovery had occurred. As long as the river continues to
flow through and annually flood the material site, it is not expected that
significant vegetative recovery will occur in the long-term.
Short-Term Alteration of Vegetative Habitat Structure
Short-term alterations, in the types of vegetative habitats present
within disturbed areas, occurred at those sites where vegetation was re-
moved, but where some natural vegetative recovery began within I or 2 years
post-mining and continued thereafter unimpeded. At no instance did an entire
disturbed area naturally revegetate over the short-term. However, in por-
tions of 13 sites pioneering communities became we I I estabi ished within I or
2 years (Table 29). This development most frequently occurred in those
portions of the disturbed areas which: were not influenced by normal or high
water flows; had a plentiful seed source or contained root stocks and other
woody slash; and/or consisted of well drained but moist soils with high silt
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232
and sand content. The results of soil sample analysis indicated soil nutri-
ents were not limiting factors influencing vegetative recovery at any of
ttie 25 study sites.
The initial reco I on i zat i on of these disturbed areas most frequently oc-
curred by seed development; at several locations, however, willows had
reinvaded through development of adventitious stems and roots from old woody
slash and root stocks. Adventitious stem development occurred most often in
overburden piles where woody slash was placed. All overburden piles occurred
in sites developed before 1971. More recent regulation of gravel removal
activities require overburden and woody cover to be removed completely from
f I oodp lain s i tes .
In general, herbaceous species dominated in those pioneer communities
which were developing from seed. However, Salix alaxensis was a frequent
member of these communities in all four geographic regions, and seedling
Betu I a papyr i f er a and Popu I us balsamifera commonly occurred in pioneer
communities at several Northern Interior sites. Taxa that most often were
dominant in these invading communities included Epilobium latifolium, Salix
a I axens i s , Sa I i x spp., Equisetum variegatum, Stellaria spp., Hedysarum
Mackenz i i , Astr aga I us spp., Oxytropis spp., Juncus spp., Carex spp., Eriopho-
rum spp., Ca I amagrost i s spp., and Poa spp. In soils that were less moist and
more coarse, Ar temis i a spp., Crepis nana. Aster sibiricus, and Erigeron spp.
frequently occurred as initial invaders.
Overburden was piled either within the disturbed area or at its edge at
many of the older sites. At the Penny River and Washington and McManus
Creeks these overburden piles contained many organics and woody slash, root
stocks, and debris. At Penny River, three piles of material were located
within the 15-ha site (Figure 65). At Washington Creek, one pile was placed
in the middle of the 3-ha site and one on its edge, and at McManus Creek the
organic overburden was all piled on the edge of the 4-ha disturbed area.
These piles averaged I to 2 m in height, however, a few were 5 to 7 m
( F i gure 66 ) .
At all three sites, herbaceous and woody vegetation were well estab-
lished on the overburden piles within I year after disturbance. Development
233
-'^fJm^;
Figure 66. Close-up view of an overburden pile in the
Penny River mined area. Note the development of herbaceous
and woody vegetation during the II years following gravel
remova I .
on these piles preceded other disturbed area revegetation at Penny River and
McManus Creek by approximately 6 to 7 years. At Washington Creek, which was
visited 13 years after disturbance, the only significant revegetation of the
site occurred on overburden piles (Figure 67). At all sites, the initial
^
Figure 67. Washington Creek mined area showing vegetative
recovery only present on the overburden pile 13 years
after gravel removal.
234
shrub development was through adventitious stems (Figure 68). Willows,
primarily S. a I axensis, most frequently developed from old slash and root
stocks .
a. View of broadcast slash and 2-year-old stems.
b. View of old root stock with new stem.
Figure 68. Woody revegetation occurring through develop-
ment of adventitious stems.
235
Similar rapid development of woody shrubs through adventitious stem
development occurred in I- to 2-ha areas at both Middle Fork Koyukuk River-
Downstream and Aufeis Creek study sites. However, at these sites the slash
and woody debris were not piled, but were spread over the ground at the
edge of the disturbed areas (Figure 69).
Figure 69. Distribution of woody slash debris and other
organics over the ground on the edge of the gravel removal
area at Aufeis Creek.
At the Tanana River-Downstream site overburden from the 5-ha pit was
placed in contoured banks surrounding the flooded pit. These overburden
piles were approximately 2 to 3 m deep inversely piled (top material covered
by bottom material), and consequently contained no organics or woody remains
near the surface. However, an early shrub community dominated by Popu I us
balsamifera, S. alaxensis, and AInus crispa, with a density of 230 stems
per 0.004 ha, was present during the fourth growing season following gravel
removal. This shrub community developed from seed and invaded in mass during
the first growing season. The shrubs occurred in uniform density over approx-
imately 60 percent of the gently-sloped, 20 to 25 m wide overburden banks
surrounding the pit.
Rapid natural reco I on i zat i on of disturbed areas was not always limited
to overburden piles. At the Jim River, West Fork Tolovana River, and
Prospect Creek, pioneer communities were well developed at the end of the
236
first full growing season following di sfurbance. At these sites the com-
munities were developing on the contoured side slopes of the permanently
ponded areas. An average of 13 species, with a range of 7 to 21 species,
occurred in 0.0004-ha sample plots located in these habitats during the
second (Jim River and Prospect Creek) and third (West Fork Tolovana River)
growing seasons following disturbance. Willows, alders, birch, and spruce
occurred with the herbaceous taxa in these habitats at all three sites.
Although these sites have not been inspected since 1978, the pioneer com-
munities will probably develop unimpeded and quickly lead to early and
advanced serai stage shrub communities.
The Tanana R i ver-Upstream site was very similar to the West Fork
Tolovana River site with respect to Physical Site Characteristics and Gravel
Removal Area Characteristics. The mined site was 10 years old during site
inspection, and 15 years old at the time of data collection (summer 1978).
Shrub thickets dominated by Sal ix arbuscu loi des and A I nus tenui folia had
developed surrounding much of the pit and on spits and islands which remain-
ed above the water level of the upper pit (Figure 70). These communities had
Figure 70. View of the upper pit at Tanana Ri ver-Upstream
showing diversity of shoreline configuration and develop-
ment of woody and herbaceous vegetation 13 years after
gravel removal .
237
reached an advanced shrub stage with densities as high as 990 stems per
0.004 ha by the 13th year. Thickets averaged 2 to 3 m in height. During site
inspection these thickets most likely were equally as dense and practically
as tall.
At most above mentioned sites, following rapid invasion and development
of pioneer communities (both by seed and adventitious stems), early shrub
communities usual ly were wel I estabi ished in 3 to 5 years. The majority of
these areas were small (0.5 to 2 ha) and were usually scattered throughout
the scraped sites or surrounding the flooded sites. Usually only one to
three isolated patches of early shrub communities occurred in the scraped
sites. Those sites that were of sufficient age (including Penny River,
Oregon Creek, Washington Creek, Sinuk River, McManus Creek, and Tanana
Ri ver-Upstream) began to provide sufficient cover for nesting and feeding
passerines and summer and winter cover for sma I I mammals about 10 years
after initial disturbance.
Thus, at sites that provide areas (of various sizes) for revegetative
growth without severe stresses from flooding or aufeis scour, habitats that
provided food and cover for passerines and sma I I mammals (primary shrub
thicket occupants) were naturally replaced about 10 years after completion
of gravel removal activities.
No Significant Change in Vegetative Habitats
Contrasted to long-term loss of habitat and short-term alteration of
habitat structure are gravel removal operations that resulted in no measur-
able change in the vegetative structure of the study areas.
Gravel mining did not affect vegetation at 5 of the 25 study sites,
either because of the disturbance location, or the floodplain character-
istics, or both (Table 28). At two additional sites, the Nome River and
Kavik River, only slight reductions in vegetative cover were observed.
Three of the five sites with no vegetative disturbance were large flood-
plains with large- and medium-width channels flowing in braided patterns. At
238
all three sites large quantities of gravel were removed by shallow scraping
surface layers over a broad area. Specifics on these sites are:
Study site
Scraped surface area
Quant i t y of grave I
removed
Ivishak River
Kuparuk River
Phelan Creek
40 ha
14 ha
70 ha
120,000 m'
42,000 m^
575,000 m'
Although Phelan Creek was a wide (approximately 1,000 m) unvegetated
floodplain, and the Ivishak and Kuparuk Rivers also had extensive unvege-
tated gravel bars, the latter two sites also contained numerous islands with
densely vegetated shrub thicket stands (Figure 71). At the Ivishak River and
Figure 71. View of the Ivishak River floodplain looking
downstream showing typical braided channel characteristics
with extensive gravel bars and isolated, vegetated islands.
Kuparuk River sites, operators conformed the configuration of their gravel
removal areas to avoid the vegetated islands. At the Phelan Creek site,
gravel was scraped from a uniformly shaped and contiguous area, because the
floodplain was entirely unvegetated within the work area.
239
The best example of avoiding disturbance to vegetated areas on a mean-
dering or sinuous river occurred at the Shaviovik River study site (Figure
72). This river flowed in a medium width, single channel and in a sinuous
*™i^^^^3cr
Figure 72, View of both undisturbed (background) and mined
(foreground) reaches of the Shaviovik River. Note that
gravel removal maintained natural point bar contours and
shapes and did not disturb riparian vegetative zones.
configuration. With these characteristics the floodplain consisted of broad
(averaging approximately 40 to 50 m in width) unvegetated point bars at
every inside bend and numerous unvegetated lateral bars located between
point bars. Gravel removal consisted of shallow scraping on every point bar
and lateral bar over a distance of several river kilometers. Small quan-
tities were taken from each location, however, a total of 116,000 m was
removed.
The actual scraping of unvegetated gravel deposits throughout most
of the Shaviovik River site was conducted in a manner that caused minimal,
or no biological disturbance. Gravel bars were scraped only in their unvege-
tated portions and riparian shrub thickets were not disturbed. Also, the
mining operation maintained natural contours and shapes on gravel bars and
240
did not mine adjacent to the river. Thus, the Shaviovik River has maintained
its natural channel and configuration.
FACTORS AFFECTING VEGETATIVE RECOVERY RATE
Several factors found to be influencing vegetative recovery already
have been discussed. The composition of fauna! communities using disturbed
areas was directly related to the habitat types available, thus, an under-
standing of how factors at the study sites influenced the rate of natural
vegetative recovery warrants further discussion. Overburden piles, woody
slash, and debris, an abundant seed source, and displaced organic mats
enhanced recovery rate. Hydraulic stress such as aufeis development, perman-
ent ponding, actual channel shifts, and increased flooding impeded develop-
ment. Soil conditions and growing season, depending upon site specific
characteristics, either enhanced or impeded vegetative recovery.
Imped iment s
Among the factors believed to be impeding vegetative recovery, hydrau-
lic stress influenced most sites and had the strongest and most long-term
effect. These stresses resulted from changes induced by gravel removal
in floodplain elevations, dimensions, and configurations. They included:
• Permanent or annual flooding,
• Increased frequency and duration of temporary flooding,
• Long-term channel changes (increased braiding and channel width and
decreased channel stability), and
• New or increased aufeis development.
The specific known causes for these induced hydraulic changes are
presented in detail in EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND
HYDRAULICS. In general, they most frequently resulted because sites were
excavated too deeply (excluding pit sites) without maintaining buffers or
stable channel banks, or because the gravel removal method and character-
istics were not correct for the chosen location.
241
At 13 sites the gravel removal method led to significant hydraulic
changes that secondarily impeded the vegetative recovery rate (Table 30).
Permanently ponded water and aufeis development caused the most significant
impediment. Permanently ponded water occurred at those sites where the
mining plan called for excavated pits, but also at sites where depressions
were scraped below summer water levels. The latter occurred at sites that
were directly connected to an active channel (Jim River); at sites that were
not directly connected to an active channel (Penny River); and at sites that
were originally not connected, but where gravel extraction caused an active
channel to reroute through the deep depression (Dietrich River-Downstream).
Aufeis impeded vegetative recovery at four sites (Washington Creek,
Oregon Creek, Middle Fork Koyukuk River-Downstream, and Jim River), all of
which were directly connected to active channels. Aufeis development is
believed to occur annually at all sites, and affects the entire disturbed
area at Washington Creek and Oregon Creek and most likely affects much of
the disturbed areas at Jim River and Middle Fork Koyukuk River-Downstream.
Two additional factors were impediments to vegetative recovery under
certain conditions: soil condition and length of growing season. Vegetative
recovery was occurring to some degree under a wide variety of soil type,
texture, nutrient, and moisture levels. Differences in the degree of develop-
ment and the species composition reflected the wide range of xeric and mesic
soil conditions. Soil nutrients were not found to be limiting factors at any
site regardless of its age, original condition, or final condition. However,
vegetative invasion was restricted by very compacted surface layers at
several of the more recent sites. These areas most frequently were associ-
ated with access routes over gravel surfaces leading to and from the mined
sites. At Dietrich River-Downstream, heavy equipment compacted the flood-
plain gravels approximately 25 cm adjacent to the gravel removal area
(Figure 73). This site was visited 3 years after completion and vegetation
had not invaded this access road although the unflooded banks of the materi-
al site were supporting pioneer communities.
Another soil condition which restricted vegetative development 13 years
after site work, occurred at Oregon Creek. Inorganic materials were scraped
242
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243
Figure 73. Compacted surface gravels in an access road
leading to the Dietrich River-Downstream site.
from the site and placed in piles along the northern boundary of the mined
area (Figure 74). Piles of this material supported no growth, while adjacent
Figure 74. Inorganic overburden piled on the edge of
the Oregon Creek site which supported no vegetation 13
years after gravel removal.
244
piles of organics, silts and sands supported advanced serai stage shrub
thickets. The undesirable material was of unknown substance, but appeared to
be a mica-like material.
The average growing season varies from approximately 130 to 150 days in
the Souther Interior, from 100 to 120 days on the Seward Peninsula, and
from 75 to 95 days on the North Slope (Mitchel personal communication). This
factor was believed to be strongly influencing the rate of vegetative recov-
ery at the two most northern study sites (Ugnuravik and Kuparuk Rivers).
Both sites were only 6 km inland from the Arctic Ocean and at both sites
vegetative recovery in nonflooded areas was progressing very slowly even
when compared to similarly aged North Slope sites (7 and 9 years) located 80
to 90 km inland.
Enhancements
Several factors were found to enhance vegetative recovery, the most
significant of which appeared to be the presence of organic soil with woody
slash and debris. This material was most effective when placed in piles that
were higher than frequent flood levels, or broadcast in those portions of
the disturbed site where it would not get washed downstream or frequently
flooded by high water.
Overburden piles occurred at I I of the 25 study sites, however, only at
those sites where this overburden contained organics with fine textured
soils (silts and sands) and woody slash and debris, was vegetative recovery
most enhanced. Instead of being placed in piles, this material was broadcast
over the surface at two additional sites (Aufeis Creek and Middle Fork
Koyukuk River-Downstream). At both sites, this material was placed in areas
where it was not stressed by high water levels. At both sites these 2- to
4-ha areas were the first to begin natural revegetation and supported the
most diverse and most developed communities. Revegetation began the first
growing season following completion of gravel removal at both sites. Develop-
ment of adventitious stems was the prime method of revegetation by willow
(F igure 75 ) .
245
Figure 75. Close-up of dense and diverse vegetatfve devel-
opment in an area of surface broadcast of woody slash
and organics. Note the willow adventitious stem
development.
Other factors that enhanced vegetative recovery were the presence of
silt deposits, an abundant seed source, and the deposition or grounding of
displaced organic vegetative mats.
At several sites (including Kavik River, Skeetercake Creek, Kuparuk
River, Sagavan irktok River, and Dietrich River-Downstream) the deposition of
pockets of silt in low depressions within the disturbed areas quickly led to
the development of a pioneer community dominated by wetland plants adapted
to wet and silty soils. These areas frequently were dominated by Carex spp.,
Juncus spp., Eriophorum spp., Equisetum spp., and Salix spp. (Figures 76 and
77). Their size was highly variable and dependent upon river characteristics
(suspended load) and site characteristics (disturbed area profiles and
shapes ) .
At several of the permanently ponded sites (Jim River, Prospect Creek
and West Fork Tolovana River) the development of herbaceous and woody plants
was found to be frequently most concentrated at old and recent high water
246
Figure 76. Distant view of a large silt depos i t i ona I
area at the Sagavan irktok River study site.
:-^0^
f
Figure 77. A silt depositional area of the Kavik River
supporting a well-developed pioneer vegetative community.
247
lines (Figure 78). These water bodies concentrated available seeds on their
surfaces and then deposited them along the shoreline.
rr..4^
^U^^i^^^X^r-:,::
'y •*
^^i
?i^'
^'
;i^':i
■'Vi
-4-5
Figure 78. Close-up of a concentration of willow seedlings
at the shoreline of the Jim River ponded area.
The erosion, downstream transport, and subsequent deposition of large,
intact vegetated organic mats also was found to initiate vegetative recovery
of gravel mined sites (Figure 79). However, this process was not overall
significant because it most often occurred on a small scale and was not
widespread. It most frequently occurred in the larger more dynamic rivers.
Most observations of this occurrence were of mats that were believed to have
been deposited I or 2 years prior to site visits. In the type of river where
they most frequently occurred, they were vulnerable to continued downstream
movement during floods. However, in a few locations the root systems of
woody species had penetrated the underlying gravels and these mats appeared
to be firmly established.
FAUNAL COMMUNITY CHANGES AT GRAVEL REMOVAL SITES
Terrestrial fauna either displayed no response to gravel removal opera-
tions or displayed one of four different reactions depending upon fauna
248
mtix»'«:!^MSM
Figure 79. Vegetated organic mats that were washed down-
stream and grounded during high water on Too I i k River
floodplain gravel bars.
type, habitat preferences, and home range size. Most responses were directly
related to the removal of floodplain vegetation. A response was recorded at
19 of the 25 study sites (Table 28). In all cases where no differences in
populations (particularly birds and small mammals) were recorded, vegetation
was either not removed (Kuparuk, Ivishak, and Shaviovik Rivers and Phelan
Creek) or only very sparse vegetative cover was removed (Ugnuravik River and
Middle Fork Koyukuk River-Downstream).
At those sites where significant quantities of floodplain vegetation
were removed, faunal responses basically consisted of four different
react i ons :
• Population Reductions - passerines and small mammals responded to
the loss of vegetative habitats.
• Population Increases - water birds and ground squirrels responded to
the removal of heavy vegetative cover, and, in the case of ground
squirrels, also to the presence of overburden piles.
249
• Altered Distribution - overwintering moose and ptarmigan most likely
responded to the reduction of food and cover habitat provided by
floodplain thickets, by either increasing their winter reliance upon
adjacent undisturbed thickets, or by shifting their local winter
distribution and movement patterns.
• No Apparent Response - large mammals (such as caribou, bears, and
wolves) showed no significant response to floodplain alterations
created by gravel removal operations.
Population Reductions
At 18 of the 25 study sites significant areas of vegetated habitat were
removed prior to gravel mining. These habitats usually were of advanced or
mature vegetative stages and were dominated by a diverse and abundant passer-
ine and small mammal community in all four regions. In Southern and Northern
Interior regions red squirrels also were dominant members of these commu-
nities at sites that contained stands of mature spruce, or mixed spruce and
b irch.
On the North Slope and Seward Peninsula, the passerine populations
inhabiting riparian shrub thickets most frequently were dominated by yellow
warblers, Wilson's warblers, orange-crowned warblers, white-crowned spar-
rows, fox sparrows, tree sparrows, gray-cheeked thrush, American robins,
common redpol Is, and ye I low wagtai Is. Although population sizes were not
estimated, at sites with extensive development of riparian shrub thickets as
many as 50 individual birds of 13 species were present in an area of approxi-
mately 3.5 ha (Penny River). In Southern and Northern Interior sites, many
of the above passerines were joined by ye I I ow-r umped warblers, gray jays,
black-capped chickadees, dark-eyed juncos, and alder flycatchers.
At many sites small mammals also were common to abundant in heavily
vegetated habitats. Tundra voles were the most frequently captured species,
and were recorded in all four regions. They were captured in a wide variety
of vegetated habitats and appeared to be more tolerant than other small
mammals of the low-lying habitats which frequently contained water saturated
250
soils. Singing voles and red-backed voles also were commonly captured in all
regions. Most singing voles were captured in habitats that were more removed
from the active portions of the floodplains, while red-backed voles were
most abundant in the mature spruce-birch forest of the Interior sites.
The most important aspect of clearing advanced and mature shrub thick-
ets and spruce-birch stands was the loss of feeding, nesting, and cover
habitats for passerines and smal I mammals. No sma I I mammals were observed or
captured in unvegetated or sparsely vegetated portions of disturbed areas at
any of the 25 study sites. Also, passerines displayed no direct association
with these areas, and only were observed on a few occasions feeding or
drinking in these habitats. As identified in previous sections, character-
istics of the gravel removal operations and subsequent hydraulic changes
most frequently resulted in long-term loss of terrestrial habitats. Thus,
the local passerine and smal I mammal populations, primari ly at the larger
sites, most likely were significantly reduced as a result of lost habitat.
Population Increases
At some sites the gravel removal operation created habitats that were
more desirable to some species than pr ed i sturbance habitat conditions.
Population levels of water birds (including waterfowl, shorebirds, gulls,
and terns) increased within the disturbed area at 12 sites (Table 28). These
sites included those where mining resulted in permanently ponded areas (such
as Jim River, West Fork Tolovana River, or Tanana R i ver-Upstream) and where
mining removed dense vegetation creating ponded water or backwater areas
and/or mud flat and gravel bar habitats (Penny River and Aufeis Creek).
These habitats provided the preferred feeding and nesting areas for these
birds.
Many of the most significant increases occurred at sites where the
adjacent upstream and downstream floodplain was heavily vegetated, and the
gravel excavation provided habitats that were not readily available in the
immediate floodplain vicinity (Penny River, West Fork Tolovana River, and
Tanana R i ver-Upstream) . Birds that were most frequently associated with
gravel and mud flat habitats in material sites included semipalmated
25 1
plovers, Arctic terns, western sandpipers, ruddy turnstones, spotted sand-
pipers, glaucous gulls, northern phaiaropes, and semipalmated sandpipers. At
sites that provided desirable conditions, primarily abundant food supplies,
the disturbed areas supported abundant shorebird populations. At the Penny
River, 56 individuals of 8 species of water birds were using the 15-ha mined
site during the nesting season, while at Aufeis Creek 100 individuals of 13
species of water birds were present within the site during the post-nesting
period. At both study sites, these numbers were a several factor increase
over the numbers of individuals and species present in the undisturbed
reaches of these floodplains.
Flooded pits provided feeding and/or nesting habitat for waterfowl
(most frequently green-winged teal, mallard, red-breasted merganser, pin-
tail, bufflehead, and Barrow's goldeneye). Tree, violet-green, and bank
swallows, Arctic terns, mew gulls, and herring gulls also were frequent ly
observed feeding in these pits.
At seven sites ground squirrels were found to be more abundant within
the disturbed areas than within adjacent undisturbed zones (Table 28). At
six of the seven sites this response was directly related to the presence of
overburden piles located within or at the edge of the material sites. These
piles provided denning sites, convenient observation posts, and the first
available food source (through vegetative development) within the mined
site. At several sites (Washington Creek, Penny River, and Skeetercake
Creek) the only ground squirrels observed were in the mined site.
In addition, at West Fork Tolovana River, Tanana River-Downstream, and
Tanana R i ver-Upstream, beaver were actively using the ponded waters in these
pits. Muskrat also were encountered at the Tanana R i ver-Upstream pit.
Altered Distribution
Moose and ptarmigan concentrate many of their winter activities in
dense floodplain thickets. Evidence of their past presence was recorded at
most sites and in all four regions. These animals normally move throughout
large areas, hence the localized removal of vegetated habitat was not be-
252
lieved to have significantly affected their population levels. However, at
sites where large areas of vegetation were removed (including Dietrich
R i ver-Upstream, Sinuk River, Sagavan i rk tok River, Penny River, and Jim
River) the loss of habitat may influence the winter distribution and move-
ment patterns of these animals.
No Apparent Response
Mammals that have large home ranges (including bears, caribou, wolves,
and foxes) generally displayed no apparent attraction to or avoidance of the
disturbed f I oodp I a i n areas. Hence, the only apparent effects of gravel
removal on these animals would be those associated with reducing their cover
and food supplies (vegetation, small mammals, passerines, and fish) or
increasing their cover and food supplies (water birds, ground squirrels, and
f ish) .
An exception to this pattern was recorded at a few of the sites located
along the Trans-Alaska Pipeline corridor. At these sites (Jim River,
Dietrich Ri ver-Upstream, West Fork Tolovana River, and Middle Fork Koyukuk
River-Downstream) individual bears and wolves have become attracted to these
areas by associating them with discarded food and garbage.
FACTORS AFFECTING RECOVERY RATE OF FAUNAL COMMUNITIES
For species whose populations were reduced as a result of gravel min-
ing, specifically passerines and small mammals, the rate at which they began
to recolonize disturbed areas was directly related to redevelopment of vege-
tative habitats. Vegetative recovery was most directly influenced by hydrau-
lic parameters as discussed in previous sections.
At sites that were of sufficient age and contained sufficient vegeta-
tive recovery, passerines did not begin to again use the disturbed areas as
nesting and feeding habitat until shrub thickets of an intermediate stage
with densities approaching 200 to 500 stems per 0.004 ha and 1.0 to 1.5 m in
height were present. In addition, small mammals did not begin to use vege-
tated areas as primary habitats until the ground cover developed to a multi-
layered cover with densities of at least 60 to 70 percent surface coverage.
255
As stated in discussions of vegetative recovery, some sites began to
provide habitat of this level in portions of the disturbed areas approxi-
mately 10 years after disturbance. Most frequently this occurred in over-
burden piles. At four sites (Sinuk River, Washington Creek, Penny River, and
Kavik River), the only significant use of the disturbed area by passerines
and small mammals occurred at the overburden piles even though these sites
averaged over 10 years in age. Thus, at sites where gravel removal created a
site subject to frequent hydraulic stresses, overburden piles not only
provided areas for rapid vegetative recovery, but frequently provided the
first useable nesting, feeding, and cover habitat for passerines and small
mammals. All vegetated overburden piles were found to be of sufficient
size to support at least one pair of nesting passerines and one resident
sma I I mamma I . The sma llest overburden pile sampled was approximately 9 m x
15 m, while the largest was approximately 15 m x 100 m. As was anticipated,
the larger piles supported the larger populations.
PERMANENTLY PONDED SITES
Many gravel removal operations resulted in significant long-term loss
and reductions in vegetative habitats and associated passerine and small
mammal populations. However, one gravel removal method frequently led to an
increase in local habitat diversity, even though it resulted in a permanent
change from original habitat conditions. This increased habitat diversity
also frequently led to increased fauna diversity. This method created perman-
ent aquatic habitat either by excavating a pit separated from the active
floodplain or by scraping a deep depression adjacent to an active channel.
Eight sites provided this lacustrine habitat. (Note: the Kavik River and
Ugnuravik River pits were not considered in this evaluation; the Kavik River
pit had filled in prior to the site visit and the Ugnuravik pit was very
small (10 to 15 m in di ameter ) and primarily covered with ma in channel flow.)
Several parameters at pit sites were qualitatively evaluated (Table
31). Increased fauna use was associated with those ponded waters that had
high border cover, irregular pit shape, vegetated or graveled islands, high
food availability, and a diversity of water depths. Also, pit size appar-
ently was a limiting factor, because both Penny River and Prospect Creek
254
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appeared to provide adequate habitat with sufficient food supplies but both
received low fauna use. They were both 1.0 ha or less in size.
The Tanana R i ver-Upstream pit, which was 13 years old, provided the
most desirable lacustrine habitat. This 7.5-ha pit had a very irregular
shoreline with heavy vegetative cover; contained numerous shrub-thicket
vegetated islands in its southern half (upper pit) and graveled islands in
its northern half (lower pit); had an abundant food supply dominated by fish
and macroinver tebrates; and had a variety of deep and shallow water zones
(Figure 80). During the site visit 147 individual birds of 39 species were
Figure 80. Tanana Ri ver-Upstream showing shoreline diver-
sity and vegatative development in the upper pit.
recorded in the entire study area and four individual beaver, at least two
muskrats, and three moose were observed using the pits. The avifauna observ-
ed are identified in Table 32.
The West Fork Tolovana River pit was smaller (4.5 ha) and not as old (5
years) but otherwise was similar to the Tanana R i ver-Upstream pit. Avifauna
observed at this site are identified in Table 33. Due to the young age and
sparse vegetative cover, the avifauna in the disturbed area included few
256
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258
passerines. However, vegetative recovery had become well established on the
gravel islands and shoreline and it is believed this site will soon provide
the same quality of habitat as the Tanana R i ver-Upstream. One colony of
beaver also were using the West Fork Tolovana River pit.
Permanently ponded material sites of sufficient size (at least larger
than I to 2 ha) will provide a high quality habitat if they have:
• A diversity of shoreline configuration and water depth,
• Dense border cover,
• Islands or peninsulas or both, and
• An abundant fish and macro i nvertebrate food supply.
SIMILARITIES OF RESPONSE BETWEEN B I OT I C AND STUDY SITE PARAMETERS
A computer analysis for similarities in response between terrestrial
biotic parameters and study site characteristics was conducted (Table 34).
Ten biotic parameters were selected for analysis. The analysis demonstrated
that responses of biotic parameters could be categorized into three groups.
Each parameter within each group displayed a similar reaction to specific
gravel removal operations. When comparing the responses of the biotic param-
eter groups for al I 25 sites, 5 site response combinations were found (Table
34). After these analyses, the material site characteristics were compared
for each site response group.
Biotic Parameters
The biotic parameters reacted in three groups of similar response to
gravel removal induced changes. Group I included passerines, shrub thickets,
moose habitat, and ptarmigan habitat; Group II included soil nutrients,
ground squirrels, early shrub communities, and small mammals; and Group III
included soil texture and water birds.
259
Table 34. Two Way Coincidence Table Displaying a Hierarchical Clustering
of Similar Sites and Similar Biotic Parameters
Biotic parameters
Group I Group I I Group I I I
£) ^ *-
Site
response
group
Shaviovik R
Ptielan Ck
Ugnuravik R
Kuparuk R
Ivishak R
M.F. Koyukuk R-DS
Nome R
Dietrich R-DS
Kavik R
WcManus Ck
M.F. Koyukuk R-DS
Tanana R-OS
Oregon Ck
Dietrich R-US
W.F. Tolovana R
Sagavan irk tok R
J im R
Prospect Ck
Aufei s Ck
Tanana R-US
Penny R
Gold Run Ck
Washington Ck
Sinuk R
Skeetercake Ck
Symbols used for computer analysis were adapted from quantification
of change ratings ITable T- I ) as follows: (0,11 equals =; (2,31 equals
-; (4,5,61 equals b; (7,81 equals +; and 19,10) equals *. Note: all b's
(no response or weak response) were eliminated from this table to remove
c I utter.
Responses by group were:
A - essential ly no response.
B - minor decreases in biotic parameter Group I; minor increases in
biotic parameter Groups II and III.
C - significant decrease in biotic Group I; minor decrease in biotic
Group II; increase in biotic Group IM.
D - significant decrease in biotic Group I; increase in biotic Group
11; significant Increase in biotic Group III.
E - decrease in biotic Group I; Increase in biotic Groups II and III.
260
In general. Group I parameters either stiowed no response, or displayed
a significant decrease resulting from gravel removal induced changes. This
was directly related to clearing of significant quantities of vegetation
which passerines, moose, and ptarmigan used as primary habitat.
Group II parameters displayed no response at sites where vegetative
habitats were not disturbed. However, all parameters except soil nutrients
decreased at sites that were subjected to permanent or frequent hydraulic
stresses (aufeis, ponding, and flooding) and did not contain overburden
piles. At sites that were subjected to hydraulic stress but which contained
overburden piles, small mammals, ground squirrels, and early shrubs increas-
ed. Soil nutrients basically displayed no response.
Group III parameters either displayed no response at sites where the
floodplain character was not significantly disturbed, or they increased.
Both parameter responses were once again directly related to removal of
extensive vegetative cover. Water birds increased in response to the in-
crease in aquatic, gravel bar, and mud flat habitats, while soil texture
increased due to the removal of organic, silt, and sand overburdens and the
exposure and deposition of coarse gravels and cobbles.
Physical Site Characteristics
The Physical Site Characteristics that were analyzed are those identi-
fied in the Major Variable Matrix Table (Table I). They included: drainage
basin size, channel width, channel configuration, channel slope, and stream
or i g i n .
Responses of biotic parameter groups at the 25 study sites displayed
five basic combinations. These are labeled Site Response Group A through E
on Table 34. Eight sites occurred in Group A, where no significant responses
were measured in any of the biotic parameter groups. These sites were mostly
of medium to large channel widths, of braided or sinuous configuration, and
of mountain or foothill origin. However, these site characteristics were not
considered to have significantly contributed to the minimal disturbance at
these sites. Of greatest significance was the minimal vegetative disturbance
which occurred during the gravel removal operations.
26 1
Site Response Groups B through E did not display any apparent similar
Physical Site Characteristics. Thus, it was judged that drainage basin size,
channel width, channel configuration, channel slope, or stream origin were
not significant factors in governing the responses of terrestrial biota.
Gravel Removal Area Characteristics
The most significant similarities in Gravel Removal Area Character-
istics were those that led to permanent or frequent hydraulic influence
within the disturbed area. This annual stress led to a significant and often
long-term impediment of site vegetative recovery. Two similar Gravel Removal
Area Characteristics were observed that produced this result. They were:
scraping within the active channel at any location along the river coarse;
and scraping adjacent to an active channel primarily on an inside bend, and
without an adequate buffer along the channel.
Scraping Within the Active Channel. Wherever gravel was scraped from
within the active channel, the scraping also extended beyond the original
channel to adjacent gravel bars. In these areas gravel was scraped to depths
equal to or slightly below normal water levels. This characteristic produced
a long-term decrease in Biotic Group I (primarily shrub thickets and passer-
ines). The hydraulic changes that occurred in these areas were the prime
factor found to be influencing site vegetative recovery. These changes are
discussed in further detail in EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY
AND HYDRAUL ICS.
Scraping Adjoining the Active Channel on an Inside Bend. At seven sites
gravel removal occurred on a point bar or inside meander but did not extend
into the adjacent active channels. All sites were of sinuous or meandering
configuration and were scraped on sharp inside bends. At five of these sites
(Penny River, Ugnuravik River, Skeetercake Creek, Middle Fork Koyukuk R i ver-
Upstream, and Middle Fork Koyukuk River-Downstream) the scraping occurred to
within or below the water level. Except at Middle Fork Koyukuk River-
Upstream, no buffer was maintained between the scraped area and the main
river channel. At the Middle Fork Koyukuk R i ver-Upstream site a 30-m wide
vegetated buffer was maintained. However, within a few years the rivers had
formed cut-off channels through the scraped areas at all five sites.
262
Thus, scraped sites located on sharp inside bends led to the formation
of cut-off channels unless extensive vegetated buffers (Jim River) or natur-
ally contoured channel slopes (Shaviovik River) were maintained during the
gravel removal operation. These cut-off channels subjected the mined areas
to frequent or permanent ponding and flooding which impeded vegetative
recovery .
Additional Similarities. Overburden piles, as previously discussed,
were a positive addition at sites annually subjected to ponding, flooding,
and aufe i s deve I opment . At sites where piles occurred, Biotic Group II
(primarily small mammals, ground squirrels, and early shrub communities)
increased (Site Response Group B, D, and E, Table 34). However, at sites
where overburden piles did not occur, but the site received annual hydraulic
stress of flooding, permanent ponding, or aufeis development, Biotic Group
II decreased (Site Response Group C).
Overburden piles occurred in a variety of shapes and sizes and were
placed in various locations within the material site. From a revegetative
viewpoint the most effective pile compositions were those with a mixture of
silts, organics, woody slash, root stocks, and debris. These piles only
occurred at the older sites and all were at least I to 1.5 m above normal
water levels. It is not known if additional piles of lower height originally
occurred and had been eroded and removed by flood waters. Also, all piles
that were within the central portions of the mined areas were either not
directly in the path of main currents or were placed in windrows oriented
parallel to the current. Overburden piles that remained in the middle of
large scraped sites were judged to be of more overal I benefit than those
placed on the edge of the disturbed areas. These piles provided immediate
denning habitat for ground squirrels and, within several years, began to
provide cover and nesting habitat for small mammals and passerines within
the central portions of large mined areas.
The effectiveness of natural buffers was related to their location and
dimensions in relation to river size and configuration. Twelve of the 25
study sites included some use of buffers. Two types were employed:
263
• Undisturbed gravel bars separating scraped sites in active flood-
plains from active channels, and
• Incised banks and associated riparian zones separating scraped and
pit sites located in inactive floodplains and terraces from active
f I oodp I a i ns.
The level of understanding that was obtained regarding the effective-
ness of these buffers does not allow conclusions to be drawn. Accurate data
describing original buffer characteristics (such as width, height, veget-
ative structure, and soil composition) were not available for many sites,
however, several trends were observed.
At sma I ler rivers of sinuous and meandering configuration, buffers
(primarily incised banks and associated riparian zones) of widths in the
range of 10 to 15 m were effective in containing active channels at sites
that were 5 to 16 years old (Figure 81).
Figure 81. Undisturbed buffer along the original stream
channel at Aufeis Creek (downstream disturbed area only)
264
In larger rivers, most natural buffers that were maintained to protect
scraped sites in active floodplains failed within a couple years. At Middle
Fork Koyukuk R i ver-Upstr earn a 30-m wide, I- to I . 5-m high heavily vegetated
buffer protecting an inside meander site was breached in I year; at Sagavan-
irktok River, a 30-m wide, 0.5-m high gravel buffer protecting a mid-channel
site was breached in I year; and at Dietrich River-Downstream a 50-m wide
and 0.5- to I -m high gravel and sparsely vegetated buffer protecting a site
on the edge of the active floodplain of a braided river was breached in 2
years. These buffer failures have all created permanent channel changes
through the mined areas of these sites.
At pit sites located in inactive floodplains and terraces, buffers
composed of incised banks and heavily vegetated riparian zones ranging from
50 to 90 m in width were sufficient in protecting the pits from active
channel diversion at sites up to 13 years old. However, most of these sites
(three of five) are located on sma I ler rivers with relatively stable chan-
nels and are on the inactive side of the floodplain. On the other hand, at
the oldest pit site (Tanana River-Downstream) a 50-m wide buffer separated
the pit from an erosional zone of a side-channel of this braided river.
During 1977 and 1978 this buffer was being actively eroded. It is not known
how wide the buffer was at the completion of the mining activity.
One mining method (pits) and one site location (separated from the
active floodplain) frequently led to the creation of high quality habitat
that resulted in an increase of water birds (Biotic Group III). As previous-
ly discussed, this method created a habitat type that frequently was not
readily available in adjacent floodplain reaches. The quality of this habi-
tat was related to its size, shoreline diversity (configuration), water
depth diversity, shoreline cover, presence of islands, and food
ava i I ab i I i t y .
Other characteristics occurred that were not directly related to the
location or operation of the material site but that reduced detrimental
impacts to the terrestrial biota. At those sites where access to the flood-
plain had to pass an incised bank, gravel fill ramps (Figure 82) reduced the
overal I impact. At sites where incised banks were cut for access severe
265
^
:;ai;uPifi^*.
Figure 82. Gravel fill ramp used to protect ttie incised
bank at ttie Sagavanirktok River study site.
erosion frequently resulted. In permafrost areas both thermal and hydraulic
erosion induced by surface travel on unprotected banks can, and at the
Ugnuravik River site did, create uncontrollable problems (Figure 83). At
sites separated from active channels by buffers, a heavy layer of rip rap on
the buffers significantly increased their effectiveness (Figure 84).
266
Figure 83. Thermal and hydraulic erosion of permafrost
induced by multiple passes of a tracked vehicle across
an unprotected incised floodplain bank and adjacent tundra.
IK'
Figure 84. Armored bank protecting the West Fork Tolovana
River pit from a channel diversion into the mined site.
267
SUMMARY AND CONCLUSIONS
Overall, gravel removal from floodplalns frequently had a detrimental
long-term effect upon local terrestrial biota. Specific site locations
coupled with the depth of scraping proved to be the most influencing fac-
tors.
VEGETATIVE REMOVAL
At 18 of the 25 study sites gravel removal operations cleared signif-
icant quantities of riparian vegetated habitat. This loss most significantly
affected passerines and small mammals which rely upon these riparian zones
for primary feeding, nesting and cover habitats. At most of these sites this
habitat reduction led to long-term changes in fauna utilization and com-
mun i t y structure.
At 4 of the 25 sites, gravel removal operations did not alter existing
vegetative communities, and consequently did not lead to changes in local
faunal communities. Three of these sites were located in floodplains with
large and medium width channels that flowed in a braided pattern. At all
three sites large quantities of gravel were removed by shal low scraping of
surface layers over a broad area. The fourth occurred on a sinuous to mean-
dering river. At this site a large quantity of gravel also was removed by
shallow scraping unvegetated portions of lateral bars and point bars. This
scraping maintained natural point bar profiles and subsequently did not
induce any channel changes.
MINING DEPTH AND LOCATION
Gravel removal operations that scraped to within or slightly below the
water table and that occurred at inside bends or immediately adjacent to, or
268
within the active channel also produced a long-term negative response (de-
crease in numbers) from terrestrial biota. At 13 of the 25 study sites
gravel removal operations with these characteristics caused hydraulic
changes (such as permanent channel shifts, aufeis development, or increased
flooding) that impeded subsequent vegetative recovery of the disturbed
areas. However, at those sites where gravel removal created permanently
ponded areas, or extensive gravel and mud flat habitats with pockets of
ponded water or backwater areas, water birds (including waterfowl, shore-
birds, gulls, and terns) frequently increased utilization of the area.
OVERBURDEN
Overburden piles containing silts, organics, and woody slash and debris
facilitated rapid and continued vegetative recovery within the mined site.
These areas provided islands of useable passerine and small mammal habitat
within a relatively short-term period. At many sites overburden piles were
providing vegetated habitats that were being used by these species within 10
years after gravel removal. Ground squirrel populations frequently showed
immediate response to available denning habitat provided by overburden
piles. At most sites where piles occurred these animals were significantly
more abundant within the mined site than in adjacent floodplain reaches.
When this overburden material was broadcast over the ground in areas
where it would not be washed downstream it was equally effective in facil-
itating rapid vegetative recovery and development.
PERMANENTLY PONDED HABITATS
At eight sites the gravel removal operation (primarily through pit exca-
vation) created permanently ponded habitats. Although this operation led to
a long-term change from natural terrestrial conditions, at several sites
this mining result led to the development of a diverse habitat that provided
high quality feeding, nesting, and cover areas for passerines, small mam-
mals, water birds, and furbearers. Factors that were found to influence the
fauna response to these areas were: shoreline configuration, shoreline
vegetative cover, water depth profiles, presence of islands, pit size.
269
availability of food, and connection to an active ctiannel. Fauna utilization
of the area significantly increased at several sites with a high diversity
of these factors.
RECOMMENDATIONS
Gravel removal operations in floodplains should attempt to incorporate
the following recommendations into site selection and site operation de-
cisions in order to minimize long-term disturbance to terrestrial flora and
fauna :
1. Whenever possible, avoid vegetated habitats.
2. When scraping in active or inactive floodplains, maintain buffers
that will contain active channels to their original locations and
conf i gurat i ons .
3. When small quantities are required (approximately 50,000 m ),
select sites that will scrape only unvegetated gravel deposits.
4. When large quantities are required (approximately in excess of
50,000 m ), select large rivers containing sufficient gravel in
unvegetated areas, or select terrace locations on the inactive side
of the floodplain and mine by pit excavation.
5. If pit mining, design a configuration with high shoreline and water
depth diversity and provide islands.
6. If mining in vegetated areas, save al I overburden and vegetative
slash and debris to use during site rehabilitation to facilitate
vegetative recovery. This material should be piled or broadcast in
a manner so it wi I I not be washed downstream.
Detailed elaboration and expansions of these recommendations are pre-
sented in the Guidelines Manual.
270
REFERENCES
Johnson, R. R., and D. A. Jones, (tech. coord.) 1977. Importance,
preservation and management of riparian habitat: A symposium.
Tucson, Arizona. July 9, 1977. USDA For. Serv. Gen. Tech. Rep.
RiV\-43, 217 pp.
Pamplin, W. L., Jr. 1979. Construction-related Impacts of the Trans-
Alaska Pipeline System on Terrestrial Wildlife Habitats. Joint
State/Federal Fish and Wildlife Advisory Team. Special Report
No. 24. 132 pp.
Spindler, M. A., and B. Kessel. 1979. Forty-second breeding bird
census: Census 167. American Birds 33( I ) :99- 100.
United States Army, Corps of Engineers. 1979. Wetland Values: Con-
cepts and Methods for Wetlands Evaluation. Research Report 79-R I .
109 pp.
Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska. U. S.
Fish and Wildlife Service. FWS/OBS 76/21. Wash., D.C. 127 pp.
271
EFFECTS OF GRAVEL REMOVAL ON WATER QUALITY
L. L. Moulton
INTRODUCTION
Water quality parameters were measured in conjunction with the aquatic
biological studies at the 25 gravel removal sites. Since the sites were visit-
ed from 2 to 20 years after gravel removal had been completed, the results of
the monitoring program reflect only long-term effects on water quality con-
ditions. The sites selected for study represented a broad range of Physical
Site Characteristics and Gravel Removal Area Characteristics, which are des-
cribed in the Major Variable Matrix (Table I). Instruments and procedures
used are described in APPROACH AND METHODOLOGY. Changes in water quality
during gravel extraction were not measured because active gravel removal sites
were not available for study. A review of available information on this aspect
was included in an earlier report (Woodward-Clyde Consultants 1976).
273
Table 35. Selected Alaska Water Quality Standards
Beneficial use
Parameter Water supply Aquatic life Recreation
Dissolved oxygen >75% saturation >7 mg/ft >5 mg/S-
(mg/il) or >5 mg/H
Temperature <I8''C over <2.2 °C over
(°C) natural, no changes
if natural ly <I8''C
Dissolved solids <500 mg/X. Avoid chronic
(mg/d or )imhos/cm) (=800 nmhos/cm) toxicity
specific conductance)
Turbidity <5 JTU <25 JTU except <25 JTU except
(JTU) when natural when natural
degradation degradation
Suspended solids 80 mg/d
(mg/S,)
Not an Alaska Standard, but 80 mg/)l is considered potentially hazardous;
25-80 mg/i!. also has potentially detrimental effect on aquatic life
(National Academy of Sciences 1973).
274
Table 36. Water Quality Parameters Measured at Gravel Removal Sites Whicti
Exceeded Alaska Water Quality Standards (Values are the Average
of Two to Eight Measurements)
Study s i te
Area
Specific Suspended
conductance Turbidity solids
(ymhos/cm) (JTU) (mg/S-)
Dietrich -Upstream
8 July 1978
Dietr i ch-Downstream
II July 1978
MF Koyukuk-Downstream
20 August 1976
Phelan Ck
21 August 1978
Upstream
275
Mined
365
Downstream
342
Upstream
324
Mined
340
Downstream
330
Upstream
320
Mi ned
300
Downstream
300
Upstream
77
Mined
79
Downstream
56
6.30.
5.20'
2.60
56.0
56.0
I 1.0
29.0
18.0
154. 0_
270.0.
186.0'
a
Value exceeds Alaska water quality standard for a defined beneficial
use (see Tab le 35) .
May have some effect on aquatic life (see Table 35).
275
RESULTS AND DISCUSSION
POST-MINING EFFECTS OF GRAVEL REMOVAL OPERATIONS
General Water Quality Conditions
Temperature, dissolved oxygen, specific conductance, turbidity, suspend-
ed solids, oxidation-reduction potential lORP), and pH were measured up-
stream, downstream, and within the gravel removal area at most sites.
Measurements were taken in conjunction with the aquatic biological surveys.
Temperature, specific conductance, turbidity, and suspended solids values
varied substantially among the different sites. However, dissolved oxygen,
ORP, and pH values were relatively similar at all sites. The parameter
values measured at each study site were compared to the Alaska Water Quality
Standards (Table 55). The water quality standards were established to pro-
tect various beneficial uses of receiving waters. The most important bene-
ficial uses associated with arctic and subarctic streams include water
supply, aquatic life, and recreation. At the 25 study sites, aquatic life
was the most common beneficial use being supported. Alaska does not have a
water quality standard for suspended solids, but a value of approximately 80
mg/i suspended solids is usually considered potentially hazardous for
aquatic life. Waters containing 25-80 rng/H suspended solids have been shown
to have a lower yield of fish than water with less than 25 mg/S, (National
Academy of Sciences 1973).
Water quality standards were exceeded for turbidity, and suspended
solids at a few river sites (Table 36) while temperature, dissolved oxygen,
specific conductance, and pH criteria were not exceeded. The high suspended
solids value at Phelan Creek was due to the glacial origin of the creek; the
276
sample site was approximately 9 km downstream from the foot of the glacier.
Other high suspended solids and turbidity values were recorded at the
Dietrich and Middle Fork Koyukuk River sites.
Turbidity measurements recorded at the Middle Fork Koyukuk River-
Downstream site exceeded water quality criteria for water supply. The only
other beneficial use standard exceeded was the aquatic life standard for
turbidity at Phelan Creek. This parameter was exceeded by approximately 340
percent during August. Phelan Creek water should still be considered con-
sumable, depending on other (unmeasured) parameters. Most values exceeding
the Alaska Water Quality Standards reflected a natural situation with only
suspended solids at Dietrich River-Downstream possibly induced by gravel
remova I .
The pH and ORP values measured at all sites reflected a basic condition
that was neither oxidizing nor reducing. The ORP values were relatively high
because of the high dissolved oxygen concentrations. The pH and ORP values
showed that there were very little organics in the monitored waters and that
most of the heavy metals would be insoluble. Some of the pH values were
slightly high (i.e., at Tanana R i ver-Upstream, pH = 8.5-9.0 in the two pits)
and may be associated with some heavy metal solubilities.
Water Quality Changes at Gravel Removal Sites. Most of the water
quality changes observed as the receiving waters passed through the aban-
doned gravel removal sites can be associated with physical changes in the
stream. A major change was reduced water velocity within the mined area
promoting sedimentation, warming of the water, and stratification. At other
sites physical changes affecting water quality conditions include a steep-
ening of the bottom gradient through the mined site, which would increase
the velocity of the water and increase the scour of the bottom sediments.
Turbidity and suspended solids changes were observed between the up-
stream and mined, mined and downstream, and upstream and downstream study
areas at 19 of the sites (Table 37). The changes are expressed as the per-
centage change occurring from the upstream samples to the downstream
277
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279
samples. Negative values signify a decrease in the parameter while a posi-
tive value indicates an increase. The column entitled "upstream to down-
stream" for each parameter indicates the net affect of the mined site on the
water quality during the site visit. There was significant seasonal vari-
ation, as indicated by the results from Oregon Creek, Penny River, Kavik
River, and McManus Creek, which makes complete analysis of the data of
questionable value. There appeared to be some sedimentation associated with
remnant instream depressions and this sediment was subject to scour during
high f I ow .
Changes in other parameters were observed with temperature and dis-
solved oxygen showing the greatest frequency of change (Table 38). The
temperature and dissolved oxygen changes resulted from the reduction of
velocity and spreading of flow over the mined area, a situation which occur-
red at many of the study sites. The ORP values did not change significantly,
indicating the absence of heavy organic loading. Conductivity values changed
in the mined area at several study sites, possibly indicating the exposure
of a spring. The differences, judging by the age of the mined areas (i.e., 2
to II years), were probably not caused by the dissolving or precipitation of
substances in the mined area. Spring sources were identified at Penny River
and Dietrich River- Upstream, both of which showed altered conductivity. A
spring source may be indicated at the Aufeis Creek and Skeetercake Creek
mined areas, but the conductivity change at McManus Creek may have been a
meter malfunction because the change was not observed during the other two
site visits.
The water qual ity parameters in inundated pits were general ly quite
different from those in the associated river (Table 59). Summer temperatures
were normally higher and dissolved oxygen levels lower in the pits. An excep-
tion was the Dietrich R i ver-Upstream pit where spring flow kept the water
temperature low throughout the summer. Thermal and oxygen stratification
were evident at the West Fork Tolovana River and Tanana R i ver-Upstream pits.
280
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282
Table 39. Average Measured Vatues of Selected Water Quality
Parameters at Study Sites with inundated Pits
Act i ve
Parameter
Inundated pit
channel
Sfudy si te
(unl tsl
surface
bottom
1 upstream)
Fenny R
T ("C."
2.0
„
4.0
6 June 1977
00 (mg/ll"^
Cond Ipmhos/cm)
12.8
—
12.0
UO
—
65
8 August 1977
T (°C)
12.1
._
10.6
DO Img/i)
9.8
—
11.6
Cond (pmhos/cml
510
—
250
Dietr i ch-Upstream
T ;°ci
4.5
4.2
(5.
.8ml
14.1
8-11 July 1978
00 (mg/l)
10.6
9.7
15.
.8ml
8.5
Cond Ipmhos/cml
400
—
275
J im River
T (°C,
13.2
_«
9.1
5-5 July 1977
00 (mg/ll
9.8
10.2
Cond (umhos/cm)
60
—
55
Prospect CK
T (°Ct
16.7
«_
11.5
7 July 1977
00 Img/tl
8.4
—
M.9
Cond lumhos/cml
70
—
55
WF Tolovana R
T <°CI
17.8
7.1
(4.
,3m)
7.5
8-12 June 1978
DO (mg/l)
—
_
11.4
Cond (iimhos/cinl
320
—
225
11-13 Sept. 1978
T (°C)
10.4
7.5
(4,
.3ml
8.0
DO Img/ll
9.3
0.2
(4.
.3ml
10.2
Cond l|iinhos/cml
185
—
235
Tanana R-Oownstream
T (°C)
13.0
12.9
(7,
.2ml
7.0
9-10 Sept. 1976
DO (mg/tl
10.2
9.9
(7,
.2ml
12.7
Cond (umhos/cml
280
—
85
Tanana R-Upstream
T (°C)
17.2
14.0
(2,
.7ml
._
4 June 1978
DO Img/l)
10.7
9.8
(2,
.7ml
—
Cond (iimhos/cm)
286
~
—
18 August 1978
T l°C)
15.2
8.2
(2,
.7ml
_.
DO Img/ll
9.4
5.6
12.
.7ml
—
18 Sept. 1978
T ("o
9.0
6.2
( 1.
.4ml
.»_
DO (mg/H
10.0
4.6
(1.
.4ml
—
Cond (umhos/cml
280
-—
•""
Sample sizes and variance estimates omitted to simplify Table.
T = temperature.
00
dissolved oxygen.
Cond = conductivity.
283
SUMMARY AND CONCLUSIONS
Few changes in water quality parameters were measured that could be
attributed to gravel removal; most of the observed changes were within the
range of that expected by natural variation. The major reason for a lack
of measurable effects was the age of the sites, as most were visited several
years after mining had ceased. The few changes that were observed were
related to physical changes in the rivers, generally due to a reduction in
velocity and spreading of flow.
284
REFERENCES
National Academy of Sciences. 1973. Water Quality Criteria 1972. Environ-
mental Studies Board, National Academy of Engineering, Wash. D. C.
594 pp.
Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska. U. S. Fish
and Wildlife Services. FWS/OBS 76/21. Wash. D. C. 127 pp.
285
EFFECTS OF GRAVEL REMOVAL ON AESTHETICS
D. K. Hardinger
INTRODUCTION
Aesthetics pertains to manmade modifications of natural landscape fea-
tures to a degree that public concern may be expressed. Aesthetic concerns
of State and Federal government include maintenance of visual resource values
by minimizing undesirable modifications to natural landscapes.
Visual resource values of natural landscapes are the particular physical
components of an area that have been identified as having high value based
on any number of measurable criteria. These could include unique cultural,
historical, recreational, geological, or biological significance. Typically
the management objectives of an agency having statutory powers for maintaining
visual resource values are to protect land areas identified as having high
aesthetic values. The agencies may do this by diverting proposed construction
to less valued locations, modifying the construction plan, or requiring the
application of mitigating measures where construction-related visual impact
proves unavoidable.
Maintenance of visual resource values has become increasingly important
to the American people. Federal legislation has recognized this concern by
establishing the visual resource as an integral and coequal resource under
the multiple-use concept of land management. At the same time, there is an
increasing demand for other resource developments that may not be compatible
This section was reviewed and input was provided by B. Sharky of Land Design
North.
287
with the management of visual resources. In order to resolve potential con-
flicts, it has become necessary to develop a system than can identify visual
resources and provide measurable management standards that are practical to
imp I ement .
Numerous systems for identifying visual resource values and evaluating
visual impact have been developed. The systems vary considerably both in
procedures followed and criteria applied. On Federal lands there are two
principal visual resource management (VRM) systems in use today. One was
developed by the U.S. Forest Service and the other by the U.S. Bureau of
Land Management (BLM). Both systems have the capability to:
• Identify areas of significant visual resource value;
• Establish land units with each unit having measurable, homogeneous
qua I i t i es; and
• Prioritize the land units through establishment of units of low visual
quality, hence requiring minimal management protection, and units
having high visual quality requiring maximum management protection.
The major components of each system involve a systematic field inventory
including (I) scenic quality or visual variety, (2) visual sensitivity, and
(3) degree of visibility. Generally, the field inventories are conducted
from an on-t he-ground perspective. Visibility from the air is generally not
considered except under specialized circumstances.
Definitions of the three key VRM inventory components of scenic quality,
visual sensitivity, and degree of visibility follow. Inventoried systemat-
ically using the BLM system, these components yield a land unit rating system
divided into five classes. Each class provides various degrees of resource
management control over prospective resource development proposals, including
gravel removal operations from arctic and subarctic floodplains.
288
SCENIC QUALITY
Establishing a scenic quality rating begins by using physiographic prov-
inces to distinguish landscape character units having common visual qualities
and to provide a regional context for the specific area being evaluated.
Within each major landscape unit there may be areas having significant visual
differences. These differences might include variations of typical landforms
that would be classified as character rating units. Each rating unit is fur-
ther classified according to the degree of scenic quality or variety as being
distinctive, common, or minimal. Generally any landscape has recognizable
parts that can be described in terms of form, line, color, and texture. These
basic visual elements exert various degrees of influence and their composition
will determine the scenic quality of a given landscape unit. The premise
is that landscapes with the most variety or diversity have the greatest po-
tential for high scenic value.
Several key factors are inventoried in determining the scenic quality
of the landscape and are used to delineate VRM land classes.
• Land form.
• Vegetat i on .
• Water.
• Co I or .
• The influence of adjacent scenery.
• Scarcity (distinctive features) or uniqueness.
VISUAL SENSITIVITY
Visual sensitivity levels measure the public concern for the scenic
quality of the landscape and for the changes that may alter the existing
landscape character. The degree of sensitivity is determined by user attitude
and use demand (volume). User attitude can be measured by a survey of private
citizens and public officials, or indirectly by public documents such as
recreation plans, trail systems, scenic highways, and other items. These
documents indicate areas of general concern. Use volume identifies areas of
pedestrian and motorized vehicular use and rates them high, medium, or low
289
based upon frequency and duration of use. User attitude and use demand are
frequently combined in a matrix to determine final sensitivity levels.
DEGREE OF VISIBILITY
A distance zone is ttie area that can be seen from a sensitivity area, and
is described as foreground, middleground, background, or seldom seen. Distance
zones are delineated on the premise that the ability to perceive change or
detail in the landscape is a function of distance.
Specific site information (Scenic Quality, Visual Sensitivity, and Degree
of Visibility) is initially displayed on separate topographic maps. A hier-
archy of importance is established and the maps are combined. The resulting
classifications are the basis for defining minimum management objectives
and the degree of acceptable alteration for each landscape classification.
The determination of the degree of acceptable alteration for each landscape
unit is defined utilizing a numerical rating system that enables a decision
maker to see exactly what feature (landform, water, vegetation, structures)
is being af fee ted and to what extent. This method a I lows some flexibility in
determining appropriate mitigation measures.
290
APPROACH
The aesthetic analysis of gravel removal from the 25 project study sites
utilized the premises and criteria of the VRM system developed by the Bureau
of Land Management. However, an actual VRM inventory and classification was
conducted on a site by site basis rather than on a regional basis as would
normally occur. Each project study site was analyzed for scenic quality,
visual sensitivity, and degree of visibility. Project aerial and on-site
ground photography, USGS togography maps, and project site descriptions were
the primary data source for the scenic quality and degree of visibility anal-
ysis. Visual sensitivity data sources are limited in Alaska; therefore, user
attitude and use volume were interpreted from the public documents cited in
the bibliography and by communications with persons familiar with the loca-
tions under study. After the sites in each general region were inventoried for
existing visual resources, a contrast evaluation was conducted. The contrast
evaluation outlines specific visual effects of gravel removal according to
BLM def i n i t i ons.
291
THE VISUAL RESOURCES OF THE STUDY REGIONS
Characteristic landscape descriptions are needed in order to assess
the degree of change or contrast that is created by floodplain gravel removal.
The following section describes the physical characteristics of each region
or site location in terms of the basic visual elements of form, line, color,
and texture. Although site specific physical descriptions are found else-
where in this text, the purpose here is to create an overal I impression of
the landscape quality in the vicinity of the study sites. When available,
information documenting public concern and use (or visual sensitivity) in
each region is also included in this section.
SEWARD PENINSULA
Seen i c Qua I i ty
Seward Peninsula sites include Gold Run Creek, Sinuk River, Washington
Creek, Oregon Creek, Penny River, and Nome River. The typical landform in
the vicinity of all sites is characterized by broad, smooth textured, rolling
hills with moderate to gentle slopes (Figure 85). The hills are separated by
sharp V-shaped valleys near stream headwaters; these valleys become wider
near the coast. Al I study sites on the Seward Peninsula are located in narrow
val leys or at the point where a narrow val ley opens into a broad val ley. The
panorama at these sites includes both gentle and moderately steep slopes.
Angular, rugged mountains are visible in the distance from al I Seward Penin-
sula sites, but do not significantly influence or enhance the local scenic
qua 11 ty.
The study site rivers on the Seward Peninsula usually flow in sinuous
configuration with moderate to swift currents. The Sinuk River is the largest
292
""^'aariifiir "
^4^
Figure 85. Typical Seward Peninsula landform at Penny River.
river and it flows in braided pattern through the study reach. The other
rivers have a single well-defined active channel with occasional side channels
or islands. The presence of occasional reaches of steeply eroded river bank do
not create strong, visibly apparent vertical lines. Some river edges are of
coarse texture with cobbles and boulders. All river systems enhance the scenic
quality of the immediate surroundings, but they are not the most dominant
element in the large scale landscape.
In the Seward Peninsula, riparian vegetation grows in various densities
and heights. In most cases low-growing shrubs (1-2 m) are interspersed with
other ground cover species (herbaceous and woody). Islands frequently are
vegetated with similar vegetative communities. The Penny River in particular
has extensive, wide bands of tall (2 to 3 m) riparian willow. The greener
shrub thicket vegetation also extends up adjacent val leys providing a sharp
color and texture contrast with the matted brown tundra on the surrounding
hillsides. Dense shrub thickets also are a common feature along old diversion
ditches, seeps, and other water sources; these create contrasting bands and
clumps of dense green color across the brown hillsides.
293
The predominant summer colors of the region are provided by the vege-
tative patterns. Common patterns include: bright green near water sources and
dull green or brown on the hillsides. During fall the floodplains turn bright
yellow, while red and golden yellow colors dominate the hillsides. Ridges
of nearby hills are barren and appear gray in color with occasional dark
brown rock outcrops.
Cultural modifications are visible from every site in the Seward Penin-
sula. The Nome-Teller Highway intersects and/or parallels five of the region's
study sites, and the Nome-Taylor Highway parallels the Nome River near the
sixth study site in this region. The roadways are the most visible cultural
modifications, but the lines they create generally blend into the lines of
surrounding landscape. Several streams are crossed by bridges of varied de-
sign. These bridges create vertical and horizontal lines that are not fre-
quently found in these landscapes. Access roads frequently lead from main
highways to river floodplains. Drainage ditches constructed during early gold
mining periods frequently can be seen as they follow the contours of adjacent
hillsides. These ditches were constructed to collect and provide water at
upland gold mining sites. Several trails traverse the local terrain and are
visually disruptive. Some cabins are situated within sight of roadways, but
none are noticeable from within the study sites. There also is evidence of
other gravel removal and gold mining sites throughout the region.
Visual Sensitivity and Degree of Visibility
The Seward Peninsula study sites are located within immediate or fore-
ground view of the Nome-Teller and Nome-Taylor Highways. There are only three
established highways for vehicle travel on the Seward Peninsula and all radi-
ate from Nome, the largest population center on the peninsula. All of the
study sites are within a 40 km radius of Nome. There is an established BLM
campground about 24 km north of the Nome River study site. This campground and
the historical gold mining districts near Nome attract additional summer
tourist travel along these routes. Commercial tours of the peninsula usually
begin in Nome and branch out along these roadways. Any changes or alterations
of the landscape that occur in the foreground along these roadways would be
294
highly visible. However, lower use volume than in other parts of the State,
and less resource agency concern for the quality of this landscape (no wild-
life refuges, wild and scenic rivers, etc.), give the study areas only a
moderate visual sensitivity.
NORTH SLOPE
Scenic Qua I i ty
North Slope study sites include the Ugnuravik River, Aufeis Creek,
Kuparuk River, Skeetercake Creek, Sagavanirktok River, Ivishak River,
Shaviovik River, and the Kavik River. The Kuparuk River and the Ugnuravik
River sites are located on the Arctic Coastal Plain which is characteris-
tically flat to slightly rolling. The steeply incised river banks accentuate
the strong horizontal line of the coastal plain and also provide vertical
relief (Figure 86). The remaining sites are located in the Arctic Foothills
Figure 86. Typical view of an Arctic Coastal Plain
f loodp lain.
which is a transition area between the coastal plain and the Brooks Mountain
Range. Gentle, undulating slopes with occasional isolated, round and rolling
295
hills characterize the landform of the foothills (refer to Figures 4 and 5 in
DESCRIPTION OF STUDY RIVERS). Incised river banks or terrace banks establish
horizontal lines that contrast with the characteristic undulating terrain. The
landform features appear to be smooth with few surface rock outcrops.
Rivers, tributaries, lakes, and ponds are common features of the North
Slope landscape. On the coastal plain the abundance of these water features
comprise approximately 75 percent of the land's surface. However, no single
landform or water feature stands out or is visual ly significant. The braided
river systems with their islands create variations in line, texture, and
color that contrast with the surrounding homogeneous landscape. The rivers
of foothill region study sites are more visually significant elements in the
landscape due to the diminishing frequency of other water features and their
prominent, focal location traversing foothi I I val ley floors.
The vegetation of the North Slope study sites is relatively rich in
color and texture. Riparian vegetation usual ly consists of low-growing com-
munities of dense willow thicket interspersed with herbaceous and woody ground
cover species. These riparian communities develop irregular outlines created
by irregular channel patterns and uneven texture. Occasionally there are
concentrated stands of tal ler, more mature wi I low that become a visual focus
due to the contrast in height with surrounding low-growing vegetation.
The color variation of the North Slope landscape is varied particularly
in the fall. The most significant color contrast exists between the greens
of the riparian shrub thickets and the tans and browns of unvegetated flood-
plains.
Some form of cultural modification is evident near all North Slope sites.
Most modifications are the result of oil and gas exploration. Several gravel
access roads parallel and intersect the floodplains near many of the study
sites. Gravel drill pads, camp pads, and airstrips are adjacent to several
sites. These surface materials with various buildings sharply contrast the
form, line, color, and texture of the surrounding undisturbed landscape.
296
In addition, the Trans-Alaska Pipeline and Haul Road are within II km and
1.5 km, respectively, of the Ivishak and Sagavan i rk tok River sites. These
features are visible from the floodplain banks at both sites. The dominant
visual feature of elevated sections of the Trans-Alaska Pipeline consists of
the vertical pipe supports and the horizontal pipe. The rigid lines of both
elements contrast sharply with surrounding undulating landscape.
The North Slope scenery is unusual and intriguing. This vast landscape
with its subtle variety provides a sustaining viewer interest and, therefore,
yields a fairly high scenic quality rating.
Visual Sensitivity and Degree of Visibility
At the present time, there is little visitor or public use near the
North Slope study areas. However, several sites are located within or adjacent
to areas identified by various groups as lands of national interest. The
Ivishak River, for instance, has been recommended as a wild and scenic river.
These designations do not guarantee increased public use, but they are an
expression of public concern for preservation of scenic quality. Increased
use could result if and when the Haul Road is opened for public access. Mater-
ial sites within view of the Haul Road would have increased degree of visi-
bility and therefore higher visual sensitivity.
NORTHERN INTERIOR
Seen i c Qua I i t y
The landscape of the Northern Interior is among the most spectacular
scenery in Alaska. It includes the Dietrich River (two study sites). Middle
Fork Koyukuk River (two study sites), Jim River, and Prospect Creek. The
sites on the Dietrich River and Middle Fork Koyukuk R i ver-Ups tream are located
in flat glaciated val leys surrounded by steep, rugged mountainous terrain
(Figure 87). The steep angular mountain walls are often crested with massive
light colored rock outcrop and cut by jagged ravines. Near the Middle Fork
Koyukuk River-Downstream site and the Jim River and Prospect Creek sites
297
Figure 87. Dietrich River valley.
the val ley widths fluctuate and mountainous features diminish in visual domi-
nance (Figure 88). The slopes are more gentle and the surrounding mountains
are more rounded in form.
'■:*i:.
Figure 88. Lower Middle Fork Koyukuk River valley.
298
River systems of the Northern Interior exert varying degrees of influence
on overall scenic quality. The large, active f I oodp I a i n of the Dietrich River
covers nearly one half of the valley floor. This river flows in braided pat-
tern over much of its length. Numerous light colored unvegetated gravel bars
in the active floodplain sharply contrast with the remaining vegetated valley
f loor and val ley wa I Is. The Middle Fork Koyukuk River varies from a large,
sinuous single channel to a braided system with a large main channel. Through-
out, there are many abandoned channels, vegetated islands, and terraces. Both
Jim River and Prospect Creek are smaller, sinuous to meandering and less
dominant in local scenic quality than the Dietrich and Middle Fork Koyukuk
Rivers. AM Northern Interior study sites are in an enclosed landscape where
the rivers become a focal point given their prominent and central location.
The vegetation along the floodplains and hillsides is a diverse mixture
of coniferous and deciduous trees of varying ages and densities. Dark-green
white spruce trees contrast with the rounded, lighter green deciduous trees
and willow thickets. High-water and abandoned river channels have created
broken patterns in the vegetation throughout the floodplain. A rich, complex
visual texture has developed because of the variable heights and colors of the
vegetative communities.
Color variety is further enhanced by the gravel deposits in the flood-
plains, local patterns of vegetation, and in some areas extensive rock out-
crops. During fall, vegetative changes introduce another dimension of color
variety with the seasonal colors of red, orange, and ye I low added to the land-
scape.
The most noticeable cultural modifications in the Northern Interior are
those associated with the Trans-Alaska Pipeline System. Facilities adjacent to
the study sites include construction and maintenance camps, airstrips, ma-
terial and disposal sites, and elevated and buried pipeline. Spur dikes have
been built into the floodplain in several locations along the Dietrich and
Middle Fork Koyukuk Rivers. The light colored gravel materials used to con-
struct the pipeline work pad, Haul Road, and camp facilities sharply contrast
299
with the rich natural color variety of this region. The pipeline and Haul Road
often create contrasting lines in the natural landscape.
The scenic quality of the Dietrich and Middle Fork Koyukuk Rivers can
be characterized as a region of high diversity. This diversity is a result
of a rich and complex texture of color, landform, and contrasts. The degree
of diversity provides the region with a somewhat unique capability of accom-
modating limited manmade encroachments in comparison with the North Slope
landscape where manmade structures would produce highly visible results.
Although the scenic quality is not as distinctive, Jim River and Prospect
Creek have greater recreation potential than the Dietrich and Middle Fork
Koyukuk Rivers. This recreation potential may have an overriding influence
on the final outcome of the visual analysis.
Visual Sensitivity and Degree of Visibility
The Northern Interior (at the time of this evaluation) is accessible
to the recreation and tourist oriented public only by air or by foot; hence,
public use is limited at the present time. The Bureau of Land Management has
several proposals that would affect the use patterns in this region if the
Haul Road is opened to the public. Most development would be restricted to
presently disturbed areas with an emphasis on maintaining scenic quality. Not
all study sites are easily visible from the Haul Road because of screening
qualities of the natural vegetation. However, current and proposed river
recreation use would increase the amount of visible area. In addition, lands
of national and State interest are adjacent to the Trans-Alaska Pipeline
System Utility Corridor (proposed "d-2" lands). Hence, there is strong public
interest in maintaining the scenic quality of this region.
SOUTHERN INTERIOR
Seen i c Qua I i ty
Most study sites of this region (West Fork Tolovana River, McManus Creek,
and Tanana River) have some similar landform characteristics. Rounded foot-
300
hills with moderately steep slopes surround the flat-bottomed West Fork
Tolovana River valley and the narrow McManus Creek valley (Figure 89). Lower,
gently rolling hills border one side of the Tanana River, while the opposite
Figure 89. McManus Creek valley.
side consists of a broad, flat plain. Rock outcrops and barren soil are usual-
ly confined to the tops of the higher foothills surrounding these sites.
Pheian Creek, however, is located in a mountainous river valley (Figure
90). The valley walls are steep and angular with rugged ridges of rock out-
crop. Mountain glaciers provide added visual interest to the surrounding
landscape.
The Tanana River and Pheian Creek flow in braided configuration. The
Tanana River has numerous gravel bars and vegetated islands in the active
floodplain that contrast with each other in visual appearance. On the other
hand, Pheian Creek has a gravel floodplain with little contrasting vegetation.
The contiguous gray-white color sharply defines the Pheian Creek valley floor.
301
Figure 90. Phelan Creek valley.
The West Fork Tolovana River and McManus Creek flow in sinuous configuration
through heavily vegetated, more narrow floodplains and do not strongly domi-
nate the surrounding landscape.
The vegetation at most Southern Interior locations is a diverse mixture
of deciduous-coniferous forest and riparian shrub thickets. The rounded decid-
uous shrubs and trees contrast with the dark, slender white spruce. The West
Fork Tolovana River and Tanana River floodplains have a particularly lush
understory that increases the variety of texture patterns. The valley walls
near most Southern Interior sites are less obviously patterned with a more
sparse understory except near drainages. However, contrasting patches of dark
and light green can still be seen in most locations.
The color variety near the Southern Interior sites includes a complex
mixture of greens, browns, grays, and tans with fall vegetative foliage adding
reds, oranges, and yellows.
302
The Southern Interior sites are in the vicinity of many manmade modifi-
cations. The Trans-Alaska Pipeline System is near the West Fork Tolovana River
and Phelan Creek sites, with State highways, rural communities, and recrea-
tional facilities present in the vicinity of all Southern Interior sites.
These facilities, with their modifications of landform and vegetation pat-
terns, detract from the overall scenic quality of the surrounding natural
I andscape.
Southern Interior sites, with the exception of Phelan Creek, have minimum
or common scenic qualities because landforms are not unique and there are a
relatively high number of cultural intrusions. Phelan Creek has more landform
variety and in some sections is highly distinctive.
Visual Sensitivity and Degree of Visibility
The Southern Interior sites are located in the vicinity of some of the
most heavily used recreation, tourist, and scenic areas in Alaska. In addi-
tion, most sites are close to major Alaskan highways connecting the largest
population centers in the state. Increasing recreational use of rivers (lead-
ing to increased view area) is facilitated by convenient road access. Nearby
campgrounds and waysides increase the viewing time in the landscape. All
of these factors contribute to high visual sensitivity in the Southern
I n ter i or .
303
EFFECTS OF GRAVEL REMOVAL ON VISUAL RESOURCES
Gravel removal activities caused alterations in the landscape that in
many cases were not visual ly harmonious with the surrounding landscapes.
These alterations are discussed in this section in terms of contrast. Contrast
is determined by the change in the form, line, color, and texture of character-
istic landscape features such as landform, water, vegetation, and structures.
The degree of contrast can vary widely; however, the significance of each
contrast will depend upon the scenic quality and visual sensitivity of the
characteristic landscape. The contrasts presented in the following sections
generally denote a negative effect unless otherwise stated. Similar contrasts
frequently exist at separate study sites in each region, hence discussions
have been grouped by region with exceptions noted.
SEWARD PENINSULA
Gravel removal activities in the Seward Peninsula created the most signif-
icant contrasts in local landform and water features of all study areas.
The uneven texture or angular lines, or both, of gravel stockpiles and over-
burden piles present at most Seward Peninsula sites, visually disrupt the
existing smooth lines of the surrounding homogeneous landscape.
Scraping and pit excavation have left contrasting rigid, rectangular
lines at several site locations. The presence of water located throughout
much of the gravel removal areas in unnatural shapes and configurations ac-
centuates this contrast. The construction of access roads has introduced
an additional contrasting form and line in this landscape. These features are
particularly disruptive if there are several at one site (Nome River, Oregon
Creek). Landform contrasts are more evident in this region because the vegeta-
tion is relatively low growing and cannot effectively screen gravel removal
304
activities. The overall color contrast has been increased at all sites by
removing riparian vegetation. However, gravel removal has not created signif-
icant overall contrasts with the form, line, and texture of the existing
vegetation patterns except at Penny River where the vegetation is much taller.
Rigid blocks of vegetation now define some borders of the gravel removal area
at Penny River, thus producing a contrast with the existing random pattern and
height variations of the natural vegetation.
NORTH SLOPE
Very few significant contrasts are visible on the braided rivers of
the North Slope. The rivers are large enough to visually absorb the changes
in cnannel and island configuration. The banks, however, are a strong visual
focus in many places and are more visual ly sensitive to change. The height
of incisea banks necessitated the use of gravel fill ramps in many locations.
Some ramps were partial ly removed after mining was completed and the remnants
are still visible. In either case, the ramps produce a moderate contrast
with the form and line of the river bank. The Kavik River is an example of
strong contrast in the form and line of the I andf orm-water feature. Large
portions of the bank were altered at this site. In addition, a large rectangu-
lar scraped area adjoins the river. These lines are not unlike those of the
nearby airstrip, but in this case they disrupt the visual linear flow of
the river's edge. The removal of vegetation and overburden in this area has
produced a color contrast that accentuates the unnatural rectangular lines
of the disturbed area.
Gravel removal created stronger contrasts along the smaller and/or single
channel rivers in the North Slope region. The creation of additional warer
channels and/or ponds at the Aufeis Creek and Skeetercake Creek has signifi-
cantly disrupted the natural lines of each system. Removal of vegetated over-
burden and stockpiling of gravel created additional contrasts in color and
texture. The resulting broken textures and configurations at these sites
contrast sharply with the existing natural landform and vegetation patterns.
305
NORTHERN INTERIOR
The Northern Interior sites are general ly located in areas where patterns
of manmade activity already exist and are visibly apparent. Gravel removal
sites in vegetated floodplains developed the most significant visual con-
trasts. Rectangular excavation boundaries contrast with the curvilinear shape
of naturally vegetated floodplains.
The removal of vegetation and overburden created color contrast at the
Dietrich R i ver-Upstream, Middle Fork Koyukuk R i ver-Upstream, Jim River, and
Prospect Creek. This contrast distinguishes the rectangular lines of the
disturbed areas from the surroundings. Color contrast would not be as signif-
icant at these sites if the disturbed area boundaries were developed in config-
uration to reflect surrounding landform and vegetative patterns.
Sites that have filled with water (Prospect Creek, Jim River, Dietrich
Ri ver-Upstream, and Dietrich River-Downstream) have produced line and form
contrasts because ponding is not a common element in the floodplains of this
region. Angular diversion channels at Dietrich River-Upstream were equally
contrasting with natural channel patterns. The abrupt and block-like shape of
existing gravel stockpiles at Dietrich River-Upstream sharply contrasted with
the flat terrain of Northern Interior river valleys.
SOUTHERN INTERIOR
The presence of tall white spruce-paper birch stands associated with
specific site locations make the study sites of this region less visible
from public roadways than sites studied in other regions. However, the
Southern Interior is a high recreational use area and natural screens between
roads and gravel removal areas are not total ly sufficient to keep the dis-
turbed areas from public view.
Landform contrast is the most obvious change in visual quality resulting
from gravel mining at the Southern Interior sites. The West Fork Tolovana
River, Tanana River-Upstream, and Tanana River-Downstream sites have rectan-
306
gular, flooded pits with steeply sloped banks. The angle of bank slope and pit
shape contrast with the natural flat floodplain form and the curvilinear lines
of the river systems. Where gravel stockpiles remain within the visible por-
tions of the study site (such as at Phelan Creek) they create a contrasting
unnatural form.
307
SUMMARY
After studying the effects of gravel removal on visual resources at
specific sites, some overall generalizations can be made. Certain landscape
features or conditions will be similarly effected by gravel remova I i n a I I
regions. The deciding factor in determining total impact will be the relative
public sensitivity to the specific landscape. The same impact in two different
areas may be judged differently depending upon public priority. Theoretically,
the landscapes that are highly visible and highly regarded by the public will
be more seriously affected than landscapes of lesser priority. The following
summarizes the effect of gravel removal on generalized landscape features
and briefly discusses public priority.
Small, single channel rivers bordered with low-growing vegetation experi-
enced the most dramatic visual impact. The location of gravel deposits on
these rivers usually requires the removal of riparian vegetation and over-
burden along incised banks. Along meandering and sinuous systems this pro-
cedure frequently results in significantly altered river configuration. The
vegetation removal causes a color change that clearly brings attention to
the disturbed area. The remaining low-growing shrub vegetation is not of
sufficient height to screen the disturbed area.
Braided rivers with or without vegetated islands usual ly can visual ly
absorb mining induced changes 'if the gravel removal occurs between the flood-
plain banks. Any changes to the banks create noticeable visual contrasts.
The most frequently observed contrast to river banks result from access roads
and fill-ramps, cut banks, and mined banks.
Tall, dense vegetation buffers surrounding the work area often screen
many mining sites from public view at ground level. However, the removal of
308
vegetation from buffer areas at most study sites has caused unnatural line
and color contrasts that draw attention to the disturbed areas. Color con-
trasts are more visible from an elevated position where a viewer is looking
down onto the site.
Rectangular, water-filled excavation pits, due to their unnatural shape,
generally create significant contrasts in all floodplain landscapes. The
contrast is accentuated when the vegetation bordering the pit is tall and
conforms to the rectangular shape.
Sites that can be viewed from above, where the viewer is able to look
down onto a site, generally results in high visibility potential particularly
in areas of sparse or low-growing vegetation.
Access roads also have resulted in significant contrasts in many study
sites. Access roads frequently create a high degree of visual prominence
and contrast where they traverse perpendicularly across existing slope con-
tours. This contrast is more disruptive in regions of rolling or steep ter-
rain, having sparse or low-growing vegetation, as exists on the Seward Penin-
sula and North Slope. The presence of more than one access road can produce a
multiplying effect with respect to increasing visual prominence.
The presence of stockpiled gravel and overburden piles often increase
visual prominence to a site. Often due to their height or linear shape, or
both, the piled material tends to attract the viewer's attention to a site
even though the site itself may not be clearly visible. Large stockpiles are
detractive in most landscapes although less noticeable in broad floodplains
surrounded by tall, highly patterned, mixed stands of vegetation. Tall vege-
tation and terrain features can provide a visual screening effect particularly
where the viewing location is at ground level.
Areas having more or less homogeneous vegetation and terrain generally
are more highly visible than those areas that are more diverse. The diverse
landscape character types general ly can accommodate gravel removal partic-
ularly at locations where the potential viewer is at a substantial distance
309
from the site or is at a similar elevation (ground level with respect to the
site) .
Visual prominence of a site tends to increase where vegetative clearing
occurs along straight, long lines. This pattern is generally true in regions
of both high and low landscape character diversity. Less visual contrast
results where irregular clearing patterns have been accomplished. Site visi-
bility is further reduced where natural vegetative recovery has occurred on
sites cleared on irregular patterns.
Four different regions of Alaska were included in this study and each
region evokes a different public response to visual resources. The regions
that appear to be the most publicly sensitive to change are the Northern
and Southern Interior regions because of exceptional scenic quality or inten-
sive public use. The visual effect of gravel mining activities is expected
to be more scrutinized by the public in those areas. Visual standards for
gravel removal areas should recognize this public sensitivity.
310
GEOTECHNICAL ENGINEERING CONSIDERATIONS OF GRAVEL REMOVAL
H. P. Thomas and R. G. Tart, Jr.
INTRODUCTION
The initial geotechnical effort on ttie project consisted of a litera-
ture review and evaluation of questionnaires sent to highway departments
around the United States. Results of this effort were presented in a prelim-
inary report (Woodward-Clyde Consultants 1976). This section presents the
findings of a geotechnical review that consisted of an office evaluation of
the limited data from the 25 study sites made available to the project
geotechnical engineers. This section identifies general geotechnical consid-
erations that should be considered in gravel removal projects. The major
data sources were: the mining plans that varied greatly in detail from site
to site (for some sites no mining plans are available); aerial photography
that varied from site to site in scale, coverage (both historical and
areal), and quality; and site photographs collected during biological and
hydrological field inspections. This section is, in many cases, generic and
general in its treatment because of the limitations of the available data.
The objectives of this evaluation were to identify:
1) Engineering techniques that led to efficient development and opera-
tion of gravel removal areas;
2) Engineering techniques that mitigated environmental disturbance; and
3) Engineering techniques that could have been used in various condi-
tions that would have led to more efficient operation with less
environmental disturbance.
3! I
Volumes of gravel removed from each site ranged from approximately
8,000 m to 630,000 m , with the largest volumes removed from Dietrich
Ri ver-Upstream, Phelan Creek, Aufeis Creek, and Sagavan irk tok River. Refer
to Table 4. Scraping was the most common removal method used, but four sites
were operated as pits and another four sites were operated as combinations
of scrapes and pits. Nine of the sites were developed in connection with
construction of the Trans-Alaska Pipeline System. Most North Slope sites
were opened in connection with oil exploration and drilling activities,
wh i le al I Seward Peninsula and most Southern Interior sites were developed
in connection with local highway projects. More detailed information on site
use is presented in DESCRIPTION OF STUDY RIVERS.
Permafrost conditions at most of the study sites are unknown. There
normal ly is a thaw bulb associated with rivers in permafrost areas. In
continuous permafrost, the thaw bulb may be a transitory feature present
only during summer flows. However, in discontinuous permafrost and for large
rivers in continuous permafrost, the thaw bulb persists year-round although
it may shrink considerably in winter. A 1969 study on the Sagavan i rk tok
River I I km south of Prudhoe Bay (Sherman 1973) showed that in summer the
thaw bulb associated with the main channel was 12 m deep and had a cross-
2 2
sectional area of 762 m . In winter, this thaw bulb shrank to 167 m with a
maximum 7 m depth. Depending especially on whether underflow occurs, thaw
bulbs may or may not be present outside the main channel.
A major gravel use in arctic and subarctic Alaska is directly related
to the need to provide a gravel overlay sufficient to carry traffic and to
prevent permafrost degradation (progressive thawing). The minimum overlay
thickness to prevent thawing can be calculated as a function of the local
thawing index. The thickness is 1.5 m at Prudhoe Bay and increases as one
moves southward (e.g., it is 2.1 m at Galbraith Lake and in Fairbanks it
would approach 6m). A 1.5 m gravel overlay has generally been used for
roads, drillpads, airstrips, and other permanent facilities at Prudhoe Bay.
However, it has been shown that a 60-cm thick gravel overlay with 5 to 10 cm
of polystyrene insulation is thermally equivalent to 1.5 to 2.1 m of gravel.
This represents a 60 percent reduction in gravel thickness and a 64 percent
312
reduction in gravel quantity, considering a typical gravel pad with 1^:1
side slopes and a crest width of 10 m. Gravel needs during construction of
the Trans-Alaska Pipeline System were reduced by using this solution for
110 km of the pipeline workpad on the North Slope. Depending upon relative
costs of gravel and insulation, synthet i ca I I y- i nsu I ated embankments may or
may not be less costly than their all-gravel counterparts (Wellman et al.
1976).
313
APPROACH
The main factors considered in the geotechnical evaluation were site
selection, access, operation, and rehabilitation. Primary information re-
viewed for each site included mining plan information from permitting agen-
cies, aerial photographs, ground photographs, and field notes taken by
the project hydro I og i sts.
Early in the review effort, a geotechnical fact sheet and evaluation
form were developed and filled out for each site. The purpose of these
forms was to assemble relevant information, to draw out observations of
project personnel who had visited the sites, and to general ly focus the
review effort. Although the geotechnical data base was very limited at
a number of the study sites, it was bel ieved to be sufficient overal I to
allow certain meaningful judgments to be drawn.
The following sections contain geotechnical discussions related to
gravel removal during principal stages in the life of a material site.
314
SITE SELECTION AND INVESTIGATION
Selection of a gravel removal site often begins with a comparison
of candidate floodplain and/or upland sites in the immediate use area.
Upland sites are beyond the scope of this report and will not be further
considered. The site selection process includes preliminary selection, site
investigation, final selection, and mining plan preparation.
PRELIMINARY SITE SELECTION
Preliminary selection of one or more candidate sites results from
assembling and reviewing available information followed by implementation
of an appropriate selection procedure.
Sources of Information
Primary sources of information used in preliminary site selection
are topographic maps, sur f i c i a I geologic maps, and aerial photographs.
Topographic maps of 1:250,000 and 1:63,360 scale are available from the
U.S. Geological Survey (USGS). Similar topographic maps are also available
for Canadian arctic and subarctic regions. From these maps, one can obtain
a general impression of the size and type of river, potential gravel availa-
bility, desirable access routes, and proximity to the use area.
The only currently available surficial geologic map of Alaska is the
1964 USGS map entitled "Surficial Geology of Alaska". With a scale of
1:1,584,000, this map does not show much detail. However, USGS recently
published a potentially useful set of maps which cover the Trans-Alaska
Pipeline route from'Prudhoe Bay to Valdez.
315
Aerial photographs frequently are the most useful sources of informa-
tion. Stereo pairs are needed to show relief (e.g., height of banks) and a
scale of not more than 1:12,000 is preferred. Color photographs are avail-
able for some areas of the State, and black and white photography is avail-
able for most areas of the State. For some areas, pre-existing aerial photo
coverage can be purchased from local aerial survey companies. However, it is
frequently worthwhile to have the area in question flown and photographed in
order to obtain the needed coverage. From adequate aerial photographs, one
can normally distinguish such features as the physical characteristics of
the floodplain (e.g., channel configurations, flow regime, gravel availa-
bility, vegetation patterns) and can select potential access routes and
f ac i I i ty locat i ons.
Preliminary Selection Procedure
The procedure for selecting a gravel removal site usually involves
identifying two or three alternative sources that appear to have sufficient
quantities of gravel. These alternates are then compared either in an in-
formal basis (usually minimizing haul distance) or in a more formal pro-
cedure involving establishing criteria, evaluating significant factors, and
ranking sites. The criteria would be specific to the situation, however,
factors that may be considered include physical properties of the material
available, haul distance, material site size and configuration needed to
produce desired quantities, equipment available and equipment needed, re-
quired site preparation (e.g., ramps, berms, dikes, overburden), river
hydraulics, and floodplain access from nearest point. At this stage the
anticipated life-span of the material site also should be considered. If it
is desired to use the site for several consecutive years, or for two or more
periods separated by inactive periods, the potential bed-load replenishment
rate should be incorporated into site selection. It is generally assumed
(See EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS) that
rivers of glacial and mountain origin, particularly near their headwaters,
have greater potential for gravel replenishment than streams of foothill or
coastal plain origin. Non-engineering aspects of site selection are dis-
cussed in other sections of this report.
316
SITE INVESTIGATION
The import-ance of an adequate on-the-ground site investigation cannot
be overemphasized. At the Ugnuravik River site, the investigation stopped
with an interpretation of aerial photographs. Subsequent site operations
discovered that the gravel was merely a veneer and not present in sufficient
quantities to meet project needs. In contrast, before construction of the
Trans-Alaska Pipeline System rather extensive site investigations were
conducted which significantly increased the knowledge of site gravel quan-
tity and qua I i t y .
Types of Data
Several different types of data need to be obtained in a material
site i nvest i gat i on.
Aerial Extent and Depth of Deposit. Estimating the volume of material
available depends on establishment of the aerial extent and depth of the
deposit in question. If this volume is less than the needed volume, the site
will be inadequate to satisfy the material needs. Hence, this is one of the
most important types of data to be obtained.
Thickness and Aerial Extent of Overburden. Gravel sites frequently have
a covering of silt or organic material, over all or part of the site, which
must be removed in order to expose underlying gravel. Mining may not be
economical if more than about I m of overburden is present over most of the
site.
Homogeneity of Deposit. A deposit which appears suitable on the surface
may be unsuitable at depth. This change in deposit quality frequently is a
result of fluvial processes involving channel shifting, alternating erosion
and deposition, and overbank flows associated with periodic flooding. Test
pits or borings from several locations within the site should be analyzed to
determine deposit quality.
317
Groundwater Table. It is important to establish the depth to the ground-
water table together with spatial and temporal variations in this parameter.
Groundwater conditions may vary widely throughout the year in response
to changing river levels, thus, several measurements are preferable. The
date of measurements should be carefully recorded.
Extent of Permafrost. Although permafrost occurrence in the vicinity of
rivers and streams can be highly erratic, it should be anticipated in arctic
and subarctic regions. The presence or absence of permafrost can be an
important factor in developing a gravel removal site.
Field Techn i ques
Both borings and test pits can be used for geotechnical exploration.
Test pits are generally preferred in granular soils because of the diffi-
culties of drilling and sampling in sma I I -d i ameter borings. However, borings
can provide a good indication of overburden thickness, water table, perma-
frost conditions, and presence and extent of unacceptable (e.g., silty)
materials. These borings or test pits should extend to the depth of the
anticipated gravel removal. The number of pits or borings would depend upon
the size and variability of the site.
Laboratory Testing
The required laboratory testing effort varies. Sieve analyses are
needed, as a minimum, to classify the material and establish its suitability
for its intended use. For these tests, rather large (50 to 100 kg) bulk
samples are desirable. Other tests that may be needed include hydrometer
tests (if frost-susceptibility is a concern) and compaction tests if the
gravel will be used to support structures.
FINAL SITE SELECTION
The final site selection is based upon the criteria analysis of the
alternative sites. This analysis compares the characteristics of the ma-
318
terials found at the available sites to the needs of the project. A major
portion of this analysis is the cost-benefit trade off of the options devel-
oped during the site investigation process. Sites further from where the
material is needed may have gravel that requires less processing; the re-
duced processing cost may lower total costs despite the added cost of trans-
port and road construction. In another case a more distant site may have an
existing access road which would, on a cost basis, justify use of the more
distant site rather than a closer site. In some instances, such as pipeline
bedding and padding, rounded well-graded gravel might be preferable. Spe-
cific gradation requirements may be necessary for subsurface drains. Uni-
formly graded angular gravel may be a requirement for asphalt pavement
aggregate. In final site selection the engineer makes trade offs to choose
the site that will provide the required material at the least cost.
This engineering analysis is then reviewed and biological resources,
hydraulic factors, and aesthetic concerns are considered before the final
site se I ect i on.
MINING PLAN PREPARATION
The agency having jurisdiction will generally require preparation and
submittal of a mining plan. Minimum elements of the mining plan are:
• Planned use of gravel,
• Basis for determination of material quality and quantity (e.g., bor-
ings, test pits, laboratory tests.)
• Site configuration and depth,
• Quant i t y limits,
• Project schedules,
• Overburden presence,
• Access to site,
• Buf f er I ocat i ons,
• Operation plan, and
• Rehabilitation plan.
319
Specifically, the mining plans should include at least the following
i nf orma t i on :
• A site sketch drawn to scale showing:
project I ocat i on
cross-sections of borrow areas,
gravel source locations,
existing or planned haul road locations,
test pit or boring locations (if any);
• An estimate of the volume of material that is needed;
• An estimate of the volume of material that is anticipated at the
ava liable s i tes;
• An estimate of the properties of the material required;
• An estimate of the properties of the in-situ materials;
• An estimate of the type and amount of processing that will be required;
• Project schedules for al I major activities;
• Preliminary design features of any required support structures, such
as access roads, processing plants, culverts, and bridges; and
• Description of operational and rehab i I i t at i ona I aspects of site use.
Plans prepared as described above should provide sufficient information
to evaluate the appropriateness of the planned development of the gravel
sources.
Mining plans were prepared and submitted to the appropriate government
agency for most of the 25 study sites. However, no mining plan information
was found for the Washington Creek, Nome River, or Skeetercake Creek sites.
The mining was apparently a trespass action at the upstream Aufeis Creek
site and for initial gravel removal at the Kavik River site. Only results of
a very limited site investigation were found for the Penny River site; only
some correspondence was found for the Ugnuravik River site; and only a
right-of-way permit was found for the McManus Creek site. Mining plan infor-
mation reviewed ranged from sketchy (for the Seward Peninsula sites) to
quite detailed (in the case of the Trans-Alaska Pipeline System sites).
320
SITE PREPARATION
Having selected and gained approval to develop a gravel removal site,
site preparation activities can begin. These activities may include construc-
tion of access roads, removal of overburden, and construction of channel
diversions and settling ponds.
ACCESS
As a part of most floodplain gravel removal operations, haul roads must
be built to connect the site to the use location or existing roads. This
construction poses no special engineering problems in non-permafrost areas
or in areas where the permafrost is thaw-stable. However, in areas of ice-
rich permafrost, protection of the tundra is of vital importance. From an
engineering standpoint, t undr a- i nsu I a ted permafrost, as long as it remains
frozen, is an excellent base or foundation for structures whether they be
drill pads, roadways, pipelines, or other structures. When the permafrost
begins to thaw two critical things happen. First, there is a tremendous loss
in strength, and second, the thawing process is very difficult to stop.
Thus, after the tundra is disturbed enough to allow the permafrost to begin
this progressive thawing, the same area that formerly was an excellent base
for structures becomes a very difficult, if not impossible, foundation
problem for any engineering purpose. Drainage and other related problems
also begin to develop and these can have significant adverse impacts on
engineered structures.
Access roads traversed ice-rich permafrost at several of the study
sites with varying degrees of success. In general, where at least 0.5 m of
gravel depth was used, permafrost integrity was maintained. However, at
several sites (Ugnuravik River, Aufeis Creek, Skeetercake Creek, and Kuparuk
321
River) the access roads were less than 0.5 m in depth and subsidence fre-
quent I y occurred.
Access roads to a given site should be limited in number and confined
to prepared surfaces. Both season of operation and long-term effects need to
be considered in planning. Access to most of the study sites seemed to be
appropriate and usually consisted of short gravel ramps and haul roads,
sometimes including gravel bars within the river floodplain.
The practice of constructing temporary gravel ramps, as at the Kuparuk,
Sagavanirktok, Ivishak, and Shaviovik Rivers sites to provide access over
incised permafrost river banks, reduces bank disturbance (Figure 91). How-
Figure 91. Gravel ramp at Shaviovik River site providing
access over a permafrost river bank.
ever, cutting into permafrost banks, as was done at the Kavik River, can
lead to severe thermal erosion and is not recommended.
322
Winter-Only Access
Winter access to a floodplain site is generally easier than summer
access because the surrounding terrain is frozen and river levels are low.
However, even frozen organic mats need to be protected from mechanical
crushing and ripping created from multiple passes over an unprotected access
road while building snow or ice roads.
The Ugnuravik River site provides an example of adverse long-term
effects: access to the site was via a temporary winter trail across the
frozen North Slope tundra. As far as is known, the trail was used only
during the last week of March 1969. However, as was commonly done, the
tussocks may have been bladed off to provide a smoother riding surface.
Compaction and destruction of the vegetative mat started an irreversible
process of thermal erosion. When the site was visited in summer, 1977, the
road had eroded to a depth of 1.5 to 2.5 m over a distance of 90 to 120 m.
Erosion was continuing, and a permanent scar had been created on the land-
scape (Figure 92; also refer to Figure 83). Based on the current state of
Figure 92. Thermal erosion near Ugnuravik River resulting
from compaction and destruction of the vegetative mat over-
lying ice-rich permafrost soils.
523
knowledge, a better solution would have been to construct a snow or ice road
(Adam 1978).
Year-Round Access
A substantial gravel 11-3 m thickness) overlay is required where year-
round access to a site is needed over ice-rich permafrost. However, place-
ment of insulation beneath the gravel would reduce the thickness of overlay
required. Year-round access roads must also be above flood stage of the
river, which may require placement of culverts at high-water channels
crossed by the road.
OVERBURDEN REMOVAL
The stripping of overburden involves the removal of any material cover-
ing the gravel deposit. The overburden material, usually topsoil and or-
ganics, is normally removed from the site and either stockpiled for later
use in site rehabilitation or hauled to approved disposal sites. Stripping
is normal ly done with graders, scrapers, or dozers. Overburden depths were
not recorded at all of the study sites. However, where information was
available, the depths ranged from a thin veneer (at six of the sites) to
0.9 m (at one of the sites) and the average was 0.3 m.
CHANNEL DIVERSION
For efficient gravel removal at some floodplain sites, it may be desir-
able to divert river flows, especially those associated with subchannels,
away from the area from which gravel is to be removed. This diversion is
normally done by constructing earthen dikes or levees upstream from the
site. Armoring of the upstream face and outer end of these structures may be
necessary to provide erosion resistance. Erosion prevention is discussed
further in EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS.
324
SETTL ING PONDS
It is necessary to wash gravel if the mined material has an appreciable
silt content. When gravel is washed, it is essential that settling ponds be
provided to allow silt to settle out before the wash water re-enters the
river. These ponds should be of sufficient capacity to handle the daily
volume of wash water or stream flow, or both, considering the settling
velocity of the entrained silt particles. Design considerations for settling
ponds can be found in Appendix F of the Guidelines Manual.
325
SITE OPERATION
The basic elements of a gravel removal operation are excavation, trans-
portation, and material processing. The details of equipment selection,
scheduling, and operation procedures are dependent on the composition of the
gravel, the season of operation, the topography, the haul distance, and the
environmental characteristics of the site.
EXCAVATION
The two basic gravel removal techniques used at the 25 study sites were
scraping and pit excavation. Table I identifies the technique used at the
respect i ve si tes.
R i pp i ng and Blast i ng
Frequently, site operators prefer removing gravel in winter because
water levels are low and access is easier. However, winter mining means
excavating gravel in a frozen, possibly ice-saturated condition. At the
study sites, if the gravel deposits were well above water levels and were
low in frozen moisture, excavation by scraper was normally not difficult.
Ripping frozen gravel was required at at least three of the sites (Middle
Fork Koyukuk Ri ver-Upstream, Prospect Creek, and Phelan Creek). It is not
known if blasting was utilized to remove gravel at any of the sites.
Scrap i ng
Scraping at larger sites is usual ly done with be! ly-dump scrapers. At
smaller sites or remote sites, or both, D-9 or smaller caterpillar tractors
326
are frequently used. Scraped sites are usually dry when worked, however,
caterpillar tractors can work in shal low water (possibly up to 0.5m).
P i t Excavat i on
Pit excavation is generally done with draglines or backhoes. Dewatering
may or may not be necessary. At the study sites some of the more shal low
pits were dewatered, but deeper pits, e.g., Dietrich R i ver-Upstream, West
Fork Tolovana River, and Tanana River-Downstream were excavated underwater.
Comparison of Techniques
Some engineering and economic advantages and disadvantages of removing
gravel via pits versus scraping are listed below.
Advantages of Pits Versus Scraping
• Greater quantity from sma I ler area.
• Can work within confined property limits (if necessary).
• Less clearing required.
• Less stripping required.
• Can provide silt trap.
Disadvantages of Pits Versus Scraping
• Dewatering or underwater excavation required.
• May provide less gravel per unit time than scraper operation.
• Cannot be restored as closely to original condition.
TRANSPORTATION AND STOCKPILING
Transportation of gravel from the material site to the stockpile or
processing plant may be done with scrapers or front-end loaders and dump
trucks. Stockpiling gravel removal operations greatly reduces scheduling
problems. It is possible to load trucks directly for long-haul transport to
ultimate-use areas without stockpiling, but a great deal of coordination is
327
required between the excavating and transporting activities. It is advan-
tageous to maintain a stockpl le of at least moderate size to serve as a
buffer between excavating and transporting. Gravel stockpiles remained on or
immediately adjacent to nine of the study sites, however, only Dietrich
R i ver-Upstream, Jim River, and Phelan Creek stockpi les were sti I I being
used.
PROCESSING
Gravel processing can involve screening, washing, crushing, mixing, or
combinations of these. Materials of the study sites frequently were fairly
uniform, subrounded to well-rounded, hard gravels with varying amounts of
sand and cobbles. Such materials are suitable for road embankments with
little or no processing. However, silt content should be limited to approxi-
mately 10 percent to minimize frost susceptibility. Processing apparently
was only conducted at those study sites used for construction of the Trans-
Alaska Pipeline System where screening and some crushing were done to pro-
duce bedding and padding material for the below-ground pipeline.
328
SITE REHAB I L I TAT I ON
Engineering concerns contribute to rehabilitation mainly if future site
development (e.g., erecting of structures) is planned. In this situation,
long-term integrity of structures is the primary concern of site rehabilita-
tion. Otherwise, the primary purpose of site rehabilitation is erosion
control. The main function of erosion control is to prevent degradation of
disturbed and adjacent areas.
Some rehabilitation was done at all study sites worked s i nee 1972.
There was no evidence of rehabilitation having been done at any of the older
sites. Where final site grading was conducted, it typically included sloping
or flattening of stockpiles and overburden piles to blend with the terrain,
contouring the site to a maximum 2: I slope, and removal of gravel ramps (not
done at the Ivishak and Shaviovik Rivers).
329
REFERENCES
Adam, K. M. 1978. Winter Road Construction Techniques, pp. 429-440. In
Proceedings of ASCE Conference on Applied Techniques for Cold Environ-
ments. Vol. I. Anchorage, Alaska.
Sherman, R. G. 1973. A Groundwater Supply for an Oil Camp near Prudhoe
Bay, Arctic Alaska, pp. 469-472. In Proceedings of the Second Inter-
national Conference on Permafrost. Yakutsk, USSR.
Wellman, J. H., Clarke, E. S., and Condo, A. C. 1976. Design and Construc-
tion of Synthetically Insulated Gravel Pads in the Alaskan Arctic, pp.
62-85. In Proceedings of Second International Symposium on Cold Regions
Engineering. Fairbanks, Alaska.
Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal
Studies in Selected Arctic and Sub-Arctic Streams in Alaska. U. S. Fish
and Wildlife Service. FWS/OBS 76/21. Wash. D. C. 127 pp.
550
INTERDISCIPLINARY OVERVIEW OF GRAVEL REMOVAL
E. H. Follmann^
INTRODUCTION
This chapter presents a general overview of the effects of gravel
removal in contrast to the preceding disciplinary chapters that rely more
heavily on analytical treatments of data collected at the 25 study sites.
Each of the Major Variables identified in the Matrix (Table I) is discussed
relative to its influence on the effects of a gravel removal operation.
These characteristics directed the early phases of the study, including the
site investigations, and form, for the most part, the framework of the
gravel removal guidelines. The disciplinary chapters on gravel removal
effects did not necessarily treat each of these characteristics because some
were not relevant or they did not influence the evaluations or syntheses
sufficiently to warrant individual attention. Thus, this overview chapter
constitutes the functional bridge between the Guidelines Manual and the
Technical Report.
Few problems were encountered in the discussion of the Physical Site
Characteristics and their interaction with gravel removal projects because
the categories are mutual ly discrete, i.e., a river cannot be both meander-
ing and straight within the study reach. The categories under each of the
Gravel Removal Area Characteristics, however, are not mutually exclusive
and, thus, cause difficulty in the development of that discussion. The sites
selected encompassed at least several individual locations from which gravel
E. H. Follmann is presently associated with the Institute of Arctic
Biology of the University of Alaska.
331
was removed. Sites such as Aufeis Creek on the North Slope and Penny River
on the Seward Peninsula each included 8 of the 12 specific site locations
that were possible (Table I). This complexity made it difficult to identify
any specific floodplain changes with specific gravel removal locations. For
these sites, the overall effect on the floodplain resulted from the total
gravel removal operation and specific effects were masked. The problem of
sites with multiple Gravel Removal Area Characteristics was unavoidable
because almost all of the over 500 sites originally considered reflected the
same situation. The major result is that, in some cases, generalities are
discussed with little or no reference to specific material sites. If none of
the sites clearly exhibited the relationship being discussed, none were
cited as examples. However, the generalities discussed are considered ac-
curate because of the analyses and conclusions reached in the preceding
disciplinary chapters.
332
PHYSICAL SITE CHARACTERISTICS
The Physical Site Characteristics considered in this project were:
drainage basin size, channel width, channel configuration, channel slope,
and stream origin (Table I). Following study of the 25 material sites and
analyses of data, it was established that channel configuration was the most
important floodplain characteristic affecting environmental change when
combined with gravel removal activities. Drainage basin size (channel width)
was found to be less significant, and channel slope and stream origin were
found to have little influence on the effects of gravel removal. The follow-
ing discussion is subdivided according to these categories.
CHANNEL CONFIGURATION
The channel configuration or pattern of a river is the shape of the
river channel (s) as seen from the air. The channel configurations considered
in this study were braided, split, meandering, sinuous, and straight.
Bra i ded
A river with a braided channel pattern typical ly contains two or more
interconnecting channels separated by unvegetated gravel bars, sparsely vege-
tated islands and, occasionally, heavily vegetated islands. Its floodplain
is typically wide and sparsely vegetated and contains numerous high-water
channels. The lateral stability of these systems is quite low within the
boundaries of the active floodplain.
Four braided systems used for material sites were studied. Ivishak
River on the North Slope, Dietrich River in the Northern Interior, and
Tanana River and Phelan Creek in the Southern Interior. These systems usu-
333
ally contain large quantities of gravel and, therefore, are often utilized
as gravel sources (Figure 93). The bed load carrying capacity of these
rivers is large, thus facilitating the replenishment of extracted gravels
after site closure.
Braided river systems are dynamic and lateral shifting of channels from
year-to-year is common, therefore, any channel shifting resulting from lower-
ing bars through gravel removal would be similar to the natural processes.
For example, any diversion of a channel through an area that was lowered by
the removal of gravel possibly would have occurred naturally sometime in the
future. Material sites in these areas typically are scraped because required
quantities of gravel usually can be obtained over large areal extents and it
Is more efficient to work a site above the existing water level. Due to the
bed load carrying capacity of these systems, the typical shal low scraped
sites are subject to sedimentation rates similar to natural depressions
occurring in these floodplains. Therefore, the minded sites can return
relatively quickly to near natural conditions. This recovery is particularly
true if the site is located near the active channel. An example of rapid
recovery is the Ivishak River site, which was shallow scraped over a large
area of unvegetated gravel bars. After several years the only evidence of
gravel mining is the presence of access roads and fill ramps that connected
the material site with an airstrip and drill pad.
Long-term effects of gravel removal on water quality were not evident
at the four sites located in braided systems. Due to the relative insta-
bility of channels in a braided river system, any channels routed through an
abandoned material site probably would be affected in a manner similar to a
channel being rerouted due to natural hydraulic processes. An exception
would be where an aliquot of a material site was used as a settling pond
during a gravel removal operation. The accumulated fines could be suspended
during subsequent high flows if this material was not armored and was left
in the depression during site closure. None of these situations was en-
countered at the study sites, however, the possibility would exist in simi-
lar site conditions.
334
Stra i gh t
Figure 93. Configurations of study rivers.
335
The aquatic organisms in braided systems are adapted to the seasonal
dynamics of the channels and, therefore, any channel changes resulting from
gravel removal operations provide situations for which the organisms are
already adapted. An exception to this generalization occurs where a pit is
separated from the active channel (Tanana River-Downstream) or is within the
floodplain (Dietrich R i ver-Upstream) and connected to an active channel. In
these cases, organisms that are more adapted to lentic environments become
established. Also, certain fish species may use the calmer waters of these
pits for spawning, rearing, and feeding areas. These pit sites are the excep-
tion, because scraping is the usual procedure selected to excavate sites in
braided systems. Excavating aspects are discussed further in the following
section on Types of Gravel Removal.
Terrestrial species that utilize braided river systems similarly are
little affected by the usual scraping operation. Since non-vegetated bars
are favored gravel removal sites, few sma I I mammals or passerines are af-
fected. The water-associated birds that use the various channels and back-
waters for feeding are also little affected by the material sites because
the usual result of these operations is to provide habitats already present.
Due to the dependence of sma I I mammals and passerines on vegetated
islands, gravel bars, and banks present in braided systems, any removal of
vegetation to expose a gravel deposit would total ly displace birds and
eliminate small mammals from the disturbed site. Similarly, these areas,
which often have associated dense shrub thickets, are used by moose and
ptarmigan, especially during winter. Loss of this habitat would cause lo-
calized displacement of these animals.
Maintenance of the scenic quality of an area can be achieved by de-
signing a material site to complement the natural setting. Material sites in
braided systems did not detract from the visual quality of the floodplain
where gravel removal was restricted to unvegetated gravel bars. The ex-
pansive floodplains typical of these systems are somewhat uniform in ap-
pearance, yet the numerous channels and gravel bars endow these areas with a
complexity that permits material sites to be located with little effect.
336
The usual mining technique for these sites is to scrape unvegetated gravel
bars rather than to excavate deeply, thus, any rearrangement of channels
through an abandoned site would closely resemble the natural annual pro-
cesses of lateral channel migration.
In summary, braided river floodplains can be desirable locations for
extracting gravels (Table 40). The abundance of well graded materials and
the potentially small effect on the physical, biological, and aesthetic char-
acteristics suggest the desirability of these areas for material sites. Th i s
conclusion assumes that the procedures of shallow scraping of unvegetated
gravel bars with minimal disturbance to active channels, banks, and vege-
tated areas, and complete rehabilitation of sites during site closure, are
adhered to.
Sp I i t Channe I
A river with a split channel pattern has numerous islands dividing
the flow into two channels. The islands and banks are usually heavily vege-
tated and stable (Figure 93). The channels tend to be narrower and deeper
and the floodplain narrower than in a braided system. Four split channel
rivers were included in this study: the Kavik, Kuparuk, and Sagavan irktok
Rivers on the North Slope and the Sinuk River on the Seward Peninsula.
Although the bed load carrying capacity of split channel rivers is
less than for braided systems, they often have a greater carrying capacity
than equivalently sized meandering or sinuous rivers. The narrower flood-
plains and lack of numerous gravel bars restrict the extent of potential
gravel removal areas. Channels, islands, and banks are often used for extrac-
tion, as was the case at the four sites studied. Islands and banks typically
are vegetated and relatively stable, consequently, there is a direct effect
on small mammals, passerines, ptarmigan, and moose utilizing these areas.
The long-term terrestrial disturbance is directly related to the extent of
vegetation removal and the rehabilitation practices used during site clo-
sure.
337
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336
Lowering islands and banks by removing gravel, even if maintained
above the existing water level, can result in reduced stability of channels
during high water. Material sites will then be inundated at least tempo-
rarily. Spreading water over a broader area reduces its velocity, causing
deposition of suspended and bed load materials. Some of this reduced vel-
ocity may function to replenish materials in the abandoned material site but
this process would probably require a longer period than would be expected
in a braided system.
Spreading of water and reduction of velocity is conducive to changing
water temperatures during the open water season. Altered water temperatures
may influence the abundance and diversity of aquatic biota by altering the
amount of usable habitat for particular species.
The reduced stability of the channels that could occur after site
closure could be detrimental to the establishment of permanent biotic popu-
lations, in particular, benthic organisms. In addition, entrapment of fish
in pockets and pools in the disturbed site may occur as water recedes into
the active channels following high-water conditions.
The increased deposition of both suspended and bed load materials
could be detrimental to the establishment of benthic communities. Fine
materials would likely be deposited in these areas, thus changes in the
structure of benthic communities could be expected. These changes would be
from organisms adapted to coarse substrate to those able to exist on finer
less stable substrate.
Changing channel configuration by removing islands, removing gravel
deposits from banks, and locally widening the active f I oodp I a i n will affect
the scenic quality of an area. This aesthetic effect was quite noticeable at
the Sinuk and Kavik River sites where care was not taken to preserve natural
contours and channel configurations. In addition, stockpiles and remnants of
diversion berms were left in place. The net effect of these conditions was
to form a major contrast with the natural conditions occurring both upstream
and downstream of the site.
339
In summary, the split channel system is one that contains a relatively
large quantity of gravel material, but its narrow floodplain with stable
islands and banks restricts the areal extent where gravel can be easily
obtained. Use of vegetated areas will directly affect terrestrial organisms
by either complete removal or displacement to undisturbed areas. Similarly,
the tendency for localized widening of the floodplain will reduce lateral
stability of channels, facilitate the possible formation of a braided chan-
nel pattern, decrease water velocity, increase sedimentation rates and,
perhaps, increase water temperature. These changes will affect aquatic
organisms by increasing secondary productivity, by changing benthic com-
munity structure, by providing rearing areas for some species of fish, and
perhaps by affording situations conducive to fish entrapment (Table 40).
Meander i ng
A meandering river winds back and forth within the floodplain. The
meandering channel shifts downval ley by a regular pattern of erosion and
deposition. Few islands are found in this type of river and gravel deposits
typical ly are found on the point bars at the insides of meanders
(Figure 95). Sediment transport in meandering systems is usually less than
for braided and split-channel river systems of equivalent size.
The size of individual gravel deposits in a meandering river depends
on the size of the river. On a large river, point bars can be quite ex-
tensive wh i le on sma I ler rivers the point bars are char acter i st i ca I ly smal-
ler. The areal extent of these gravel bars determines, to a large extent,
the degree of change which gravel extraction has on a meandering system. For
example, if a large point bar is used to supply gravel for a sma I I project,
the operation of a material site may cause little change to the river sys-
tem. However, when projects with large gravel requirements are situated
close to a sma I I meandering river or where the gravel requirements exceed
that available on a large point bar, potential effects to the river system
increase greatly. The alternative mining procedures are to completely remove
the point bar, use several point bars, or remove vegetated deposits back
from the channel. In al I cases, varying degrees of impact can be expected,
but all will depend on the manner in which the gravel is extracted.
340
Four material sites on meandering systems were studied on this project
(Table I). Two were dug as pits and two were scraped.
Pit Sites. The material sites at Prospect Creek and West Fork Tolovana
River were dug in abandoned channels. In neither case was there a change in
the lateral stability of the active channel. There was loss of terrestrial
vegetation and associated fauna because the material sites were located back
from the active channels. Aquatic fauna in the active channel apparently did
not change. Change, if any, was due to the presence of an adjacent flood-
ed pit. Similarly, water quality did not change in the active river channels
but, as expected, water quality in the pit was different from that in the
active channel. These differences and changes are discussed in the section
on Type of Gravel Removal because they were not unique to meandering sys-
t ems .
Formation of a permanently flooded pit within a floodplain, that other-
wise contains few ponds or lakes, changes the appearance of the area by in-
creasing the diversity of physical features. These pits are quite visible
when seen from the air or from a high terrestrial vantage point. Ta I I vege-
tation in the areas of these two material sites contributed greatly to
blocking view of the sites.
Many meandering river floodplains contain a multitude of oxbow lakes
that are formed by channel cutoffs. In these cases, a pit could blend easily
into the natural landscape, thus greatly reducing the visual effect of
gravel removal operations. However, most pits are dug with angular perim-
eters which create a visual contrast in the floodplain. This contrast is a
generic problem and will be discussed further under Type of Gravel Removal.
Scraped Sites. The material sites on Aufeis Creek and Skeetercake Creek
were scraped. The environmental changes were quite different at the two
sites resulting principally from differences in their locations relative to
the channel (Table 4-0). The gravel at Aufeis Creek was scraped from across
the entire channel, which changed the channel from a single to a braided
configuration. The short-term influence was so severe that surface flow was
341
nonexistent the year following site closure but, over 3 years surface flow
v^jas re-established. Although the site was not studied when surface flow was
absent, the effect on fish would have been to prohibit passage. Epibenthic
communities would have been reduced due to the lack of surface water. Fol-
lowing re-establishment of surface flow, benthic communities characteristic
of riffle zones would be most common due to channel spread and reduced water
depth.
The change from a single channel to a braided channel can significantly
affect the local distribution of aquatic organisms. The altered community
would be similar to that typically found in a naturally braided system.
Reduced water velocity enhances sediment deposition and can alter water
temperatures. During the study, changes in water temperature were noted
between the upstream and disturbed sample areas, but a difference in sus-
pended solids was not found.
The impact on the terrestrial environment frequently entails removal of
vegetation and other habitats along the bank. Little change to the ter-
restrial environment would be expected when gravel is mined only on unvege-
tated gravel bars, unless the hydraulic characteristics of the channel are
changed significantly following site closure. Also, little change would be
expected in the scenic quality of an area as a result of gravel removal,
unless vegetation is removed. At Aufeis Creek, changes in both the ter-
restrial environment and scenic quality resulted from the gravel removal
operation because of the area disturbed, the site location, and operating
procedures that were used, none of which complemented the floodplain char-
acter i st i cs.
At Skeetercake Creek the hydraulic changes were somewhat different.
The exposed gravel deposits were limited because this was a small river.
Thus, gravel was mined from vegetated areas in the floodplain, with concom-
itant effects on the terrestrial fauna. The gravel removal activity affected
channel stability by facilitating a channel cutoff, however, the channel did
not braid due, at least in part, to the restricted floodplain. The cutoff
formed an oxbow lake in the abandoned site. The floodplain in this reach of
342
the river had few oxbow cutoffs, consequently, mining changed the appearance
of the area. However, the presence of overburden and gravel stockpiles
detracted far more than the altered channel.
Aquatic habitat changes at Skeetercake Creek were not as great as would
be expected if the channel had become braided. The narrowness of the natural
channel imparted a greater significance to the value of bank vegetation.
Loss of this cover can change the distribution of fishes. The change from an
incised channel to a shallow riffle area through the abandoned site caused
the water temperature, during the study, to be higher in the disturbed area
than upstream. However, changes in suspended solids were not noted.
Summary. Scraping point bars can have little environmental effect
assuming that the operation is conducted in a manner that minimizes changes
to the hydraulic characteristics of the channel and adjacent vegetated
areas. If change is minimized, the effects on aquatic and terrestrial biota,
and water and scenic quality are greatly minimized.
Meandering rivers provide usable deposits of gravel from point bars, in
inactive floodplains, and terraces. The potential effects on such a system
vary depending on whether only point bars are used or whether the adjacent
inactive f I oodp I a i n and terrace also are mined. Sites in inactive flood-
plains and terraces often are dug as pits while point bars in active flood-
plains are scraped.
Pit sites remote from the active channel have caused some problems
during spring breakup at sites visited during site selection, but not
studied as primary sites in this project (unpublished data). When channels
are blocked with ice, melt water must flow over the ice and may overflow the
bank and spread across the entire floodplain. Pits located in these flood-
plains are then subject to filling which can facilitate diversion of flow
through the site. This diversion is particularly possible where pits are dug
within the inside of a meander. Depending on the size and inherent stability
of the undisturbed buffer between the pit and channel, the flow may cut
343
through the buffer zone and permanently divert flow. Ultimately, the meander
will be cut off through sediment deposition and form an oxbow lake.
Other effects can be anticipated when pits are dug in the f I oodp I a i n of
meandering systems, however, they are characteristic of pit mining. There-
fore, these aspects are discussed under Type of Gravel Removal.
S i nuous
Sinuous channels are similar to meandering channels except that the
winding pattern is less pronounced. The channel may contain smaller point
bars and have less tendency for downval ley shifting. Also, the channels are
more stable with respect to lateral shifting.
Ten of the sites studied on this project were on sinuous rivers (Figure
95). Their similarity to meandering channels suggests that the effects from
gravel extraction are also similar, with the major influence determined
primarily by the site location and the removal method. Due to this simi-
larity only a few characteristics of mining gravel at sinuous channels are
d i scussed .
The sma I ler point bars in sinuous rivers, as compared to meandering
rivers, limit the quantity of exposed gravel that is locally available for
removal. This limitation can magnify the need for using multiple point bars
or vegetated areas back from the channel to fulfill the gravel requirements
of larger projects.
Floodplain areas adjacent to the channel contain gravel deposits that
are typically overgrown with vegetation. Floodplain width usually is roughly
equivalent to the meander belt width, thus, the floodplain of a sinuous
river tends to be narrower than in a meandering system. Therefore, the area
in the floodplain that is available for gravel extraction is more limited.
This places restrictions on the areal extent of potential gravel resources,
and may require that a greater length of floodplain be used to extract
grave I .
344
The potential effects of removing gravel from sinuous ctiannel rivers
are increased because of these limitations. If point bars are scraped too
deeply, or if incised banks and the adjacent floodplains are disturbed, the
potential for decreasing channel stability is greatly enhanced. The initial
disturbance from site clearing, and the changes resulting from a poorly
located and operated site, will have multiple effects.
The decreased channel stability and tendency for braiding will affect
both benthos and fish by altering aquatic habitats. Benthic communities
adapted to riffles, fine sediment bottoms, and a relatively unstable bottom,
will become established. Loss of bank cover and potentially reduced current
in the disturbed site will affect fish distribution and perhaps species
composition. In addition, reducing water depth and velocity could change
water temperatures and affect the level of dissolved oxygen. Fish could
become trapped in the disturbed site when water recedes following high
f I ows.
Terrestrial vegetated habitat will be destroyed when the floodplain
adjacent to the channel is used as a material site. This destruction of
vegetation will cause either elimination or displacement of terrestrial
fauna. If the stream banks are affected the decreased hydraulic stability in
the area could reduce the potential for re-establishment of vegetative com-
munities, thus creating a long-term rehabilitation problem.
Gravel removal from a sinuous river will have effects on the scenic
quality similar to those discussed for a meandering system. The degree of
effect is fully dependent on the diversity of landforms in the area of the
site and the amount of disturbance. Single channel river systems are scen-
ically more sensitive than multiple channel systems particularly those
single channel rivers located in areas with low growing vegetation, such as
on the North Slope.
In summary, the amount of environmental change that can be anticipated
in a sinuous river system is largely dependent on the location of the ma-
terial site and the methods of operation. Anticipated effects are similar to
345
those for a meandering system but, because floodplains generally are more
narrow and contain smaller point bars, the potential for permanent altera-
tion is generally greater (Table 40). Proper placement of the material site
and operational procedures can minimize permanent change and these should be
selected to prevent or minimize changes to the hydraulic characteristics of
the channel .
Stra i ght
Straight channel patterns are less common than other types. The thalweg
of a straight river typically winds back and forth within the channel.
Gravel bars form opposite where the thalweg approaches the side of the
channel (Figure 93). These gravel bars may not be exposed during high flow.
Banks of straight systems typically are stable and floodplains are usually
narrow. These river systems are considered to be an unusual configuration in
transition to some other configuration. Only the material site studied at
Oregon Creek was situated on a straight channel system.
As with other types of single channel systems the major potential
effect from scraping floodplain gravels is decreased stability of the chan-
nel and a tendency to develop a braided configuration. These are probable
occurrences because of the typically narrow floodplains and the limited
number of exposed bars available. Often the adjacent floodplain will have to
be disturbed, or even the channel itself, because of the limited area avail-
able. The Oregon Creek site typified the extensive long-term changes that
can occur when gravel is removed from within the channel and the adjacent
floodplain (Table 40). The channel stability was greatly reduced and the
channel had become braided within the confines of the abandoned site. These
conditions exist 13 years after the site was closed and probably will remain
in that condition for many more years.
The change from a single to a braided channel alters water quality
parameters and aquatic biota as discussed in previous sections on sinuous
and meandering systems. These alterations include the potential for changing
water temperature and increasing sedimentation in the disturbed site where
34-6
the water fans out and becomes shal lower and slower in velocity. Dissolved
oxygen and conductivity levels can also be altered. Benthic communities may
change from a community associated with the relatively stable channel of
a straight river to one that is better adapted to the less stable substrate
characteristic of braided areas. Removal or alteration of vegetated banks
and changes in pool:riffle ratios can alter the distribution of fish within
the immediate vicinity of the disturbance. Fish passage is obstructed if the
spreading of water sufficiently reduce its depth.
The disturbances at the Oregon Creek site provided a situation con-
ducive to the formation of aufeis. Aufeis could have direct effects on fish
by eliminating or greatly reducing the flow downstream from the ice field,
thus threatening overwintering areas and spawning beds. Similarly, during
breakup, delayed thawing of the ice field could obstruct fish passage.
Benthic communities would be later in establishing at the disturbed site due
to the delayed melt of the ice field.
The terrestrial environment will almost always be subject to distur-
bance for any site situated on a straight channel river. This vulnerability
is due to the rarity of large exposed gravel bars in the channel which
necessitates mining the adjacent vegetated f I oodp I a i n banks or terrace. At
the Oregon Creek site the vegetated overburden was removed and placed in a
row at the edge of the terrace. The gravel was removed from the exposed area
and from within the channel causing extensive spreading of the flow through
the exposed floodplain. Inundation of this area during high flow and the
build-up of an auf e is field greatly minimized the potential for stabili-
zation and revegetation of the disturbed area. This stabilization and revege-
tation had not occurred after 13 years, thus the likelihood of the site
revegetating in the near future is remote.
The appearance of the floodplain was greatly affected at the Oregon
Creek site. This altered appearance will exist for a long time and will only
diminish when the channel begins to narrow and when adjacent areas revege-
tate. The potential for major changes in the appearance of a straight chan-
nel floodplain, that is mined, is great because of the limited availability
347
of exposed gravels, which necessitates the disturbance of adjacent vegetated
areas. The magnitude of effect increases with a decrease in river size.
In general, the rarity of straight channel rivers probably is fortunate
from the standpoint of gravel requirements. The relatively few exposed
gravel deposits and the narrow floodplains suggest the major problems that
can result from gravel removal operations in these systems. Major distur-
bances probably will occur in any river of this type unless precautions are
taken to protect the area. When mining is restricted to exposed gravel
deposits a major length of floodplain will be disturbed if gravel require-
ments are large. The latter problem can be prevented by restricting mining
to the adjacent vegetated floodplain. Straight channel systems should be
avoided where it is possible to select alternate areas to mine.
DRAINAGE BASIN SIZE (CHANNEL WIDTH)
Drainage basin size and channel width are closely related from a hydro-
logical standpoint and analysis of only the former would be sufficient
for assessing change from gravel removal activities. However, channel width
was included in the Major Variable Matrix (Table I) because it is a measure-
ment easily obtainable in the field while drainage basin must often be
estimated from topographical maps. Because of the close relationship between
these two parameters, the following discussion applies to both.
Drainage basin size (channel width) was considered to be the second
most important Physical Site Characteristic influencing the amount of change
in a floodplain from gravel removal activities. In general, the effects
of mining were considerably greater on sma I I rivers than on large ones. The
determining factor is the amount of exposed gravel material available within
the floodplain. In larger systems, gravel deposits can be numerous and any
given deposit usually contains a large quantity of material. The situation
is the opposite in a sma I I river - the few exposed deposits general ly do not
contain much material.
348
In large rivers, a given amount of gravel can be removed from exposed
deposits with relatively less effect on the floodplain than at a small
river. If gravel requirements are very large, the alternatives are to use
multiple gravel deposits along the channel, or to expand the areal extent of
one site to include adjacent vegetated areas. In a small river system, there
are no real options. Gravel has to be removed from adjacent vegetated areas,
or from the active channel, or both. This solution was the case for seven of
the small rivers studied. The Gold Run Creek site exhibited less change than
the other small river systems (except for the site at Phelan Creek where
vegetation was not removed). At Gold Run Creek the gravel removal operation
was restricted principal ly to gravel bars and an island in the channel. A
bank was removed but the degree of floodplain disturbance was less than for
the sites on Washington, Oregon, and McManus Creeks, and Penny River. At
these latter sites, extensive adjacent floodplain disturbances tended to
either greatly expand the channel width or divert the channel.
Phelan Creek is a braided system and has a small drainage basin above
the material site. Although the site is situated near the headwaters, the
channel is of medium width because of flow carried in the summer during
glacial melt. In this case the large exposed gravel deposits were scraped
and the material site included neither vegetated areas nor channels carrying
flow. Even though this is a small river system, the long-term effects are
minimal because of other overriding factors. Minimal effects are usually not
the case, however, on small rivers.
Location of the material site is most critical on small river systems
because of the limited availability of exposed gravel deposits and the rela-
tively narrow floodplain. Extensive damage can occur to the entire flood-
plain reach being mined in these systems, while on large rivers the effects
are not as great because the material sites cover a sma I ler proportion of
the floodplain. Location of sites and potential effects are discussed in a
subsequent section.
349
CHANNEL SLOPE AND STREAM ORIGIN
Neither of these Physical Site Characteristics was found to greatly
influence the effects of gravel removal in f I oodp I a i n environments. Both
channel slope and stream origin are closely related to such factors as
drainage basin size and channel configuration, therefore, their influence on
the effects of gravel removal are dependent on these factors. The Physical
Site Characteristics are discussed separately because of specific impli-
cat i ons i nvo I ved.
Channel Slope. Removal of gravel from a channel wi I I affect the channel
slope within the site and, perhaps, immediately upstream and downstream.
Usually this effect entails increasing the slope, which can have localized
effects on the floodplain. The main effect is to increase water velocity.
Localized changes that can be expected due to the relationship of
increased velocity and increased slope are scour and alterations of aquatic
communities. Increased scour in a disturbed site can increase downstream
deposition of bed load materials where the water slows to the velocity
characteristic of the undisturbed channel. The greater scour potential in
the disturbed site decreases the stability of bed materials thus affecting
habitat for benthic organisms.
Increased water velocity can directly affect benthic organisms by
displacing those not adapted to higher velocities and favoring those adapted
to these conditions. Similarly, fish may become redistributed locally be-
cause of water velocity changes. Those fish species or age groups preferring
lower velocities may displace to areas upstream or downstream.
Altered velocity is not expected to change the terrestrial environment
or the scenic quality of an area. Indirectly, an effect might occur to water-
associated birds that are dependent on benthic organisms as a food source.
Any alterations to benthic communities could alter feeding sites for these
b irds.
350
Significant changes in slope most often reflect changes in channel
length. If a channel is shortened by mining then the slope is increased; if
the channel is lengthened, the slope is decreased. At all study sites the
slope was either unchanged or it increased. The likelihood of decreasing
channel slope by lengthening the channel is slight because water tends to
flow downvalley over the shortest distance. However, if channel lengthening
should occur by diversion through a site, then the effects would reflect
reduced velocities.
Stream Origin. The origin of the stream was found to have little or no
relationship to the effects of gravel removal activities. Origin can in-
fluence, at least in part, other characteristics of a river system, e.g.,
channel configuration and shape. Therefore, the preceding discussions are
indirectly related to this characteristic. The origin of a stream determines
greatly the quality and quantity of gravel materials available in downstream
areas.
The original purpose for including stream origin in the study was
to maximize diversification of the types of sites to be studied. The origins
of streams included were mountain, foothill, coastal plain, and glacial.
Twelve of the sites studied were of mountain origin, 9 were of foothill
origin, and only 4 were of glacial or coastal plain origin.
The availability of gravels in streams of coastal plain origin is
general ly low and the materials are finer in texture than those found in
other systems. Within the geographical limits of our study, only the Seward
Peninsula and North Slope have coastal plains. The coastal plain of the
Seward Peninsula is so narrow it precludes the existence of such river
systems. On the North Slope material sites were located on the Sakonowyak,
Putuligayuk, and Ugnuravik Rivers, but only the latter was studied. Gener-
al ly, these sites are not favored and are only used if alternative sites are
not aval lable. The lack of rock in the headwaters and the low mean annual
discharges are the reasons that gravel materials are only minimally avail-
able in coastal plain streams. If these sites are utilized, the potential
for replacement of gravel sources is very low even over extended time
351
periods. The minimal areal extent- of exposed gravel bars also generally
leads to extensive damage to the river system either by use of extended
lengths of river channel or by disturbing vegetated floodplains.
Glacial origin streams are not common in the area of study; only three
sites situated on this type of river were studied. These were on Phelan
Creek and the Tanana River. Because these systems are of mountain origin,
the availability of weathered parent materials is not limiting and usually
large quantities are available. The Phelan Creek site was situated near the
glacier and gravel was abundant across a wide area. The proximity of the
site to the glacier strongly influenced the seasonal fluctuations in dis-
charge. During winter, water flow from the glacier is greatly reduced and is
supplemented by that from associated springs. This reduced flow exposes vast
expanses of gravel for extraction.
The Tanana River sites are well downstream from the river origin, there-
fore, water flows throughout the year because of the numerous spring- and
groundwater-f ed tributaries entering the river. Affects include those associ-
ated with braided channels that flow in winter. In these systems, however,
ice cover on channels is more of a factor than on a system like Phelan
Creek, near its origin.
The availability of gravels in glacial origin rivers makes them a
viable source of materials even when needed in large quantities. This is
basically true for systems of all sizes although on smaller rivers the
localized deposits are more restricted.
Most rivers in northern and interior Alaska are of mountain or foothill
origin. The weathered parent material in the headwaters provides large
quantities of gravels, particularly in the mountain systems. These rivers
are fed by springs, melt water, and runoff and, therefore, discharge fluc-
tuates seasonally. Spring-fed systems can be expected to have at least
Intergravel flow in winter. Moderate to steep channel slopes are normal
in the headwaters but these slopes are influenced by the length of the river
and the topography through which it flows. Bed load movements are usually
552
higher than in rivers with mild slopes. These rivers generally have large
quantities of gravel available even near the mouth. The size of the system
and other hydrological and hydraulic factors also influence availability of
gravel. The abundance of mountain and foothill origin rivers and the fre-
quent availability of suitable gravel materials generally combine to favor
the location of material sites in these systems. The geographical location
of these rivers, and the topography through which they flow, directly affect
the type of channel configuration, a factor discussed in a previous section.
353
GRAVEL REMOVAL AREA CHARACTERISTICS
In the preceding section on Physical Site Characteristics it was ap-
parent that not all characteristics were important in evaluating the po-
tential floodplain change caused by gravel removal activities. In contrast,
all of the factors discussed in this section were found to greatly influence
the amount of change to a river system. The three main features discussed
are type of gravel removal (pit or scrape), location of the material site
relative to the active channel (s), and the occurrence of dikes and stock-
piles. Singularly and in combination these factors caused varying degrees of
change at the 25 study sites, in some cases, irrespective of the specific
physical site characteristics.
TYPE OF GRAVEL REMOVAL
There are two basic types of material sites: pits and scrapes. Pits
are dug deeply, usually with draglines or backhoes, and are flooded year-
round after site closure. In many cases pits are flooded during gravel
extraction unless water is pumped out to keep the site relatively dry. Eight
pit sites were studied and they represented two types, those connected
to an active channel and those completely separated from an active channel
by a buffer zone. Pits usually are situated away from an active channel.
In a scraping operation, gravel deposits are removed with bulldozers
or scrapers in active and inactive floodplains and terraces. Gravel is
extracted by successive removal of thin layers, and scraping depths usually
are sufficiently shallow to minimize the occurrence of surface water. At
certain study sites, gravel was extracted below the water table, thus water
ponded in the site. This situation is not conducive to a scraping operation
and, therefore, is usually avoided unless it is required for other reasons.
354
Pits
Pits are usually excavated away from an active channel and cause little
or no change to the natural hydraulic processes of the channel. Where pits
are connected to a channel, either year-round or seasonally, some change to
the hydraulics of a river can occur. The most obvious alteration occurs when
spring breakup or other high water flows spread throughout the floodplain;
much of the water can flow out of the channel because it is often filled
with ice. A pit in the floodplain probably would fill during high flows and
then, through erosional processes at the upper and lower ends, function as a
channel. The inlets or outlets (or both) connecting the pit to the channel
could enlarge significantly and reroute flow through the excavated pit.
Depending on site conditions this could be only temporary, for example,
where a pit is adjacent to a relatively straight reach of channel. In this
case, following high breakup flows, the water would again flow down the
original channel because the downvalley distance is shorter than if the
water flowed through the channel formed by the pit.
A permanent alteration to flow is more likely to occur where a pit is
located on the inside bend of a meandering stream. Even with undisturbed
buffer zones separating the pit from the channel, spring breakup flows can
overflow the pit and exit into the downstream reach of the meander surround-
ing the pit. If the stability of the buffer zone is low, erosion can breach
the buffer zone, thus, connecting the pit to the active channel. The down-
val ley distance is shorter through the pit, consequently, there would be a
tendency for permanent redirection of flow through the pit and eventual cut
off of the meandering channel.
Excavation of a pit separate from the channel does not affect the water
quality of the active channel. As would be expected, however, the water qual-
ity is different in a flooded pit than in the channel. In comparison to
channel waters, pit waters typically have higher temperatures during ice
free conditions, the dissolved oxygen levels are lower, and sometimes there
is stratification of both temperature and dissolved oxygen. Differences in
water quality parameters could be less in situations where channel flow is
355
through a pit. This difference depends on the size of the pit and the amount
of mixing. A pit could facilitate deposition of suspended and bed load ma-
terials if flows are through a pit and velocity is decreased.
The aquatic biota of pits differ depending on whether there is an
opportunity for exchange between the pit and the active channel. Those pits
that are separated (e.g., Tanana River-Downstream) or have little potential
for exchange (Dietrich R i ver-Upstream) typically are unproductive. The
Tanana River-Downstream pit is situated in the middle of an island and is
completely surrounded by a broad undisturbed (except for an access road)
timbered buffer zone. The likelihood for injection of nutrients and organ-
isms into this pit is remote, except during high flows. The aquatic surveys
reflected this. The occurrence of a few fish suggests that overflow may
occur at irregular intervals. The Dietrich R i ver-Upstream pit, on the other
hand, is connected by its outlet to the channel. A spring, exposed during
excavation, floods the pit and exits through a channel. The pit system has
been used by overwintering fish but the pit itself is relatively unpro-
duct i ve.
All other pits studied were highly productive and the diversity of the
fish community was usually increased over that in the river channel. All of
these pits were connected to the river channel through either inlets or
outlets and thus exchange was possible between the two systems. The still
waters in the pit, which are warmer than the river water, provided con-
ditions more suitable for primary and secondary productivity. Fish such as
Arctic grayling entered presumably to utilize the pit as a feeding area.
This situation is particularly good for feeding by fish of younger age
classes because of the greater supply of food available and the lack of a
current.
Fish we I I suited to a sti I I water environment, such as northern pike
and burbot, also did we I I in some of these pits and, being piscivorous, had
an abundance of young age classes of other fish to feed upon as they entered
the pits to feed and rear. Northern pike also utilized two of the pits as
spawning areas. The potential for the pits to provide a more diversified
556
fish community in the river also exists because of the connection between
the two systems. This increased community diversity may be restricted to the
area of the channel in the immediate vicinity of the pit.
Pit depths are important to fish utilization. Obstructions to movement
are not a factor during open water periods if either an inlet or outlet are
available for fish movement between the river and the pit. A potential for
fish entrapment exists, however, during winter when ice cover is present on
the river, the pit, and the interconnecting channel. In the latter situation
the pit must be sufficiently deep so it does not freeze to the bottom and
decomposition of aquatic vegetation does not decrease the oxygen content of
the water below that necessary for fish survival.
The creation of a pit in a floodplain constitutes a major change to the
local terrestrial environment. Pits are usually situated on vegetated flood-
plains, consequently, terrestrial habitat is almost always destroyed. The
depth of excavation and the permanent inundation that results also greatly
retards or prevents on the long-term, the re-establishment of pred i sturbance
conditions. What most frequently occurs, however, is the creation of a more
diverse habitat with concomitant changes in faunal communities.
The creation of a pit in meandering river floodplains, that contain
oxbow lakes, merely adds to the habitat diversity in a localized area. Where
pits are located in floodplains lacking natural lakes and ponds, the effect
is again principally local, but has implications that affect a much larger
system. In these cases, the newly formed body of water can attract migrant
waterfowl and shorebirds and perhaps even provide habitat suitable for
nesting and rearing that did not previously exist. The higher aquatic produc-
tivity of many of these ponds could afford a significant food source for
those species adapted to feeding in pond and lake environments.
The effect of creation of a pit, on the scenic quality of an area,
is totally dependent on the diversity of the floodplain environment. A pit
will have less effect where lakes and ponds occur naturally than where
these types of aquatic systems do not occur. Where lakes and ponds do not
357
occur location should be selected so that view of the site is blocked from
vantage points. For example, the Tanana River-Downstream pit, which is large
and contains very clear water, is in a floodplain where the river channels
are highly turbid, thus, offering a dramatic visual contrast. However, the
site is situated on an island completely surrounded by a heavily wooded
buffer zone which blocks view of the site from the Richardson Highway. The
pit is visible only from the air.
Pits are often excavated with angular perimeters that ignore natural
land contour. Since angularity is not characteristic of naturally formed
aquatic systems the usual pit site offers some contrast even in areas where
lakes and ponds occur natural ly. Excavating these sites with perimeters that
blend with natural land contours, such as in abandoned river channels, de-
creases the visual diversity that will result from development of pit sites.
The West Fork Tolovana River and Tanana R i ver-Upstream sites are excellent
examples of this management technique (refer to Figures 63 and 70).
Pit sites require considerably less area to obtain a given amount of
gravel than do areas that are surface scraped. Because of the depths nor-
mal ly required, subsurface waters are exposed, usual ly fill ing the pit
during site operation. This water poses problems for the efficient extrac-
tion of materials but, since draglines or backhoes are usually used for
excavation, the presence of water does not prevent the removal of gravels.
Pumping is the only method used to eliminate the water but even this is
impossible in some systems because of the volume of subsurface flow through
floodplain gravels. During mining, the water in a pit is usually highly
turbid and should not be pumped into adjacent channels.
In summary, there is little doubt that the excavation of a pit materi-
al site creates significant change in a floodplain environment (Table 41).
If situated and operated properly, the hydraulics of the river system are
little affected whereas significant changes occur to the terrestrial system
and the scenic quality of the area. Differences in water quality and aquatic
biota can be expected between a pit and the adjacent channel regardless of
whether they are connected. The increase in both aquatic and terrestrial
358
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359
habitat diversity is reflected in a more diverse faunal community. Pit sites
are a viable alternative for material extraction in areas where changes to
the river hydraulics can be avoided or greatly minimized. When major hy-
draulic changes occur the effects on the environment can be damaging from
many standpoints.
Scraped Si tes
Scraped sites can occur essentially anywhere in a floodplain from
within the active channel to vegetated areas in the inactive floodplain and
terrace. Location of the site greatly affects the potential impacts that can
be expected from a scraped site. Although scraping implies that material
sites are operated by shallow removal of gravel, certain sites studied on
this project were excavated below the water table and thus resulted in
permanent flooding. These sites, however, were worked with scrapers or
bulldozers and not draglines or backhoes as might be implied by depth of
excavat i on .
Scraped sites have several operational advantages; usually the sites
are dry, providing better working conditions and more efficient gravel
extraction. Additionally, excavated materials require less handling when
using scrapers to remove the gravel because only one machine is normally
used to excavate, transport, and deposit at the construction site. This is
not feasible using a bulldozer on a scrape or when digging pits with drag-
I i nes or backhoes.
Given the same gravel requirement, the scraped site will generally
disturb a larger area than a pit site because the excavation is more shal-
low. In the study sites, the large area affected was often the greatest
problem of scrape-mining because there were few restrictions regarding
avoidance of channels and areas adjacent to channels. Locations of extrac-
tion sites are discussed in the subsequent section.
Scrapes are generally situated in active floodplains adjacent to active
or high-water channels. Lowering these areas spreads water flow, at least
560
during high flows, and in some cases forms a braided configuration through
the disturbed site. When this occurs on unvegetated gravel bars in braided
systems, the effect on the f I oodp I a i n is relatively minor because the ef-
fects are similar to natural hydraulic processes. After site closure, unless
stockpiles or dikes are present, the disturbed site can return to a rather
natural configuration within a maximum of a few years. This, however, is not
the case where lateral bars are excavated to include removal of adjacent
banks. Bank removal is discussed in the subsequent section.
The potential for causing braiding from scraping operations within the
active floodplain, is usually insignificant in a river system that already
has a braided channel configuration. However, in split channel and single
channel systems braiding constitutes a significant change to the aquatic
environment and alters the aquatic biota; species which benefit are those
better adapted to riffle areas, to less stable substrates and, perhaps, to
substrates less granular than those found in the natural system. These
habitat changes primarily affect the distribution of organisms. This study
general ly found a local decreased diversity of the fish community as a
result of braiding. There is a potential of blockage to fish passage, at
least during low flow conditions, as occurred at the Aufeis Creek site
because the water flows over a wider area than in the undisturbed channel.
Blockage is most severe if the entire active floodplain is disturbed, not
just the lateral bars. Entrapment of fish, in depressions created by scrap-
ing, is also possible during periods when water is receding from high flows.
Effects on the terrestrial environment depend greatly on the river type
involved and on the location of the work area within the floodplain. In
braided systems mined in the active floodplain, there essentially is no
effect. However, on split and single channel systems, braiding caused by
gravel mining can provide feeding habitat for shorebirds that utilize ben-
thic organisms. Destruction of banks with associated vegetation removes
habitat used by terrestrial fauna; the effects are the same as removal of
vegetation for pit sites.
361
The potential for re-establishment of natural configurations and flow
patterns after site closure are totally dependent on the degree of change
to the hydraulic processes characteristic of the river system. Long-term
effects can be expected where major changes to the stability of channels
occur. The major terrestrial effect of scraping resulted where deep scrapes
occurred in areas immediately adjacent to the channel. Channel flow often
diverted through these depressions and caused year-round ponding which
retarded the re-establishment of vegetation. These deep scrapes usually were
inadequate as quality habitat for waterfowl and shorebirds and unsuitable
for fish. To minimize short- and long-term effects, scraped sites should not
be excavated beyond certain depth limits. These restrictions are discussed
in the Guidelines Manual.
The effects of scraping operations on the scenic quality of a braided
floodplain can be minimal if the material sites are restricted to the active
floodplain. Where banks and vegetated areas are altered, significant effects
can be anticipated. In split and single channel systems the establishment of
a braided configuration in the disturbed area produces an unnatural condi-
tion in the floodplain, thus affording a visual contrast. Properly located
scraping operations that avoided or minimized disturbances to the hydraulic
characteristics of a river, minimized long-term environmental change. How-
ever, where sites were poorly located and caused significant changes to the
channel hydraulics, major long-term effects were evident on the scenic
qua I i ty of the area.
In summary, scraping operations typically occurred in both active and
inactive floodplains. Both vegetated and unvegetated areas were used but
the fewest long-term disturbances occurred where only exposed gravel de-
posits were scraped. The potential for broadening or diverting channel flow
in split and single channel systems is great if depths of excavation are
excessive and locations of sites are poor. The potential for braiding in
these situations was increased with concomitant changes in aquatic biota.
Terrestrial effects were greatest when the depth of excavation was excessive
and led to permanent ponding which retarded recovery to predi sturbance
562
conditions. Visual effects of scraping operations depend greatly on the type
of river system, the location of the site, and the areal extent of the site
within the f I oodp lain.
LOCATION OF GRAVEL REMOVAL
Location of a gravel removal operation in relation to the channel of a
river was found to be the most important aspect influencing long-term change
to a floodplain environment. Whether a pit or scrape, in general, the loca-
tion of the site was a more important consideration than the type of site.
Site location in this section is discussed with minimal reference to the
type of site although the latter is a factor influencing the extent of
change.
In-Channel Locations
As used in this project, in-channel gravel removal includes areas in
the active channel, high-water channels, and abandoned channels. Fourteen of
the sites studied on this project were situated in high-water channels and 7
of the 8 sites located in the active channel also included areas in high-
water channels. From hydraulic and hydrological standpoints, material sites
in active and high-water channels caused the greatest long-term change to
the floodplain environment.
Active Channel. Gravel removal operations in the bed of an active
channel cause a series of changes all basically related to changes in the
depth and location of the thalweg. The degree of change depends on the type
of channel configuration, principally whether it is a braided or a single
channel. In a braided system the channels generally shift throughout the
active floodplain on an annual basis. This is due to the lateral instability
of the individual channels. In these systems removal of gravel has the
effect of perhaps causing greater instability in the area of the distur-
bance. Changes occurring in a single channel river caused by removing bed
material are unknown because all seven sites with this mining location had
substantial alteration to adjacent deposits or banks.
363
Removing gravel from within the channel is accomplished either by
dredging or by scraping the bed after flow has been diverted. Either method
can result in a deepening of the thalweg and, if the edges of adjacent
gravel bars or banks are removed, a widening of the channel. Depending on
the location of the material site, this operation could alter the pool:
riffle ratio in the river.
Where the channel is dredged, turbidity in and downstream of the site
will increase greatly during mining. Turbidity should reduce quickly after
the operation has ceased. If the channel is diverted during mining, the
effects on water quality entail suspension of the fines exposed during
mining when water is diverted back through the site. This suspension will
result in a temporary increase in turbidity.
Reduction in the velocity of water entering the excavated hole will
cause sedimentation of both bed load and suspended materials. This will aid
in rapid replenishment of the gravel materials removed from the site. Being
in the active channel, the replenishment rate is considered high compared to
other areas in the f I oodp I a i n .
Excavation of the channel bed can remove spawning areas. During a
dredging operation fish probably will redistribute to less turbid waters.
Benthic organisms adapted to silt-laden areas will establish following
excavation and remain until the natural gravel bed becomes established.
Assuming that the disturbances resulting from gravel removal are re-
stricted to the channel, and do not include the banks or edges of gravel
bars, little long-term effect on the terrestrial environment is expected.
Changes could occur if hydraulic changes in the channel affect adjacent
banks.
Aesthetically, the in-channel material site has little or no effect.
Hydraulic changes resulting from in-channel disturbance that affects banks
can cause some effect.
364
High-Water Channel. High-water channels flow only during high-water
periods. The hydraulic effects of removing gravel from high-water channels
are not as great as they are in the active channel where the disturbed area
is subjected to flow throughout the year. The changes that can be expected
are similar to those described for the active channel although they occur
only during the period when the site is subjected to flow.
Effects on water quality are only evident during the high-flow period.
Localized widening or deepening of the high-water channel would slow the
water velocity and thus facilitate deposition of both bed load and suspended
materials. Depending on the degree of change to the channel this deposition
would reduce the time required to re-establish near-natural conditions in
the area. Also, any fines exposed during mining would be available for
suspension during high flows.
Removing gravel from a high-water channel could trap fish and benthic
organisms in the depressions of the disturbed areas as flow recedes. Many
benthic organisms that are adapted to a riffle community and most fish
species would not be able to survive in such a habitat.
Since high-water channels are subjected to less flow than active chan-
nels, they tend to be more stable and are usually bordered by established
terrestrial vegetation. Any disturbance to these channels causing lateral
instability during high flows could facilitate erosion of adjacent banks and
thus serve to reduce the areal extent of vegetated areas. Loss of habitat
would cause localized elimination of small mammals and displacement of birds
and larger mammals. Having water pooled in the high-water channel during
low-flow periods could attract shorebirds, particularly where a benthic
fauna has become established to serve as a potential food source.
The most serious effect from a gravel removal operation in a high-water
channel is bank destruction which often occurs with this type of operation.
This aspect is discussed in a subsequent section on removing gravel from
banks .
365
The effect of mining gravel from a high-water channel on the scenic
quality of an area is minimal if the disturbance is restricted to the chan-
nel. If banks are destroyed the effect would be more significant. Since the
high-water channel is active only part of the year re-establishment of
pre-existing conditions will require a longer time. Formation of pits in
high-water channels would have effects similar to those described in the
section on Type of Gravel Removal.
Abandoned Channel. Abandoned channels carry water only during major
flood events. Normally, these channels are considered to be dry during most
years. Since they represent old river channels they usually contain reason-
ably large quantities of gravel, depending on the type of river with which
they are associated. Only two of the sites studied were located on an aban-
doned channel. Prospect Creek and West Fork Tolovana River, both in meander-
ing systems. Abandoned channels are common in this type of floodplain be-
cause of the formation of cutoffs that result from the fluvial processes
of meandering channels.
Location of material sites in abandoned channels causes little problem
with regard to changes in river hydrology and hydraulics because the sites
are separated from active flow. Where pits are dug in abandoned channels and
are connected to the active channel, flow can be diverted through the site
during high flows. The magnitude and duration of this change is dependent on
the nature of the connection between the material site and the channel and
the integrity of the undisturbed buffer zone separating the site from the
active channel. Where the once-abandoned channel carries water annually
during high-flow stages, the effects to the floodplain would be similar to
those described for sites in high-water channels.
Where an abandoned channel is scraped and the water table is not
reached, water quality does not become a problem. Where pits become flooded,
the water quality would be different than that occurring in the active
channel, as is discussed in the section on pits.
366
Aquatic biota will not be affected in a scrape operation located in an
abandoned channel, however, if a pit is dug, aquatic biota could become
established. In these cases the effect depends on whether the gravel removal
operation alters the site sufficiently to cause it to be subjected to annual
high flow or whether it is connected to the active channel. In the former
case, there is potential for entrapment of fish during high flow as was
discussed for high-water channels. In the case of a site connected to a
channel, the effects are those discussed in the section on pits.
The effects of removing gravel on the terrestrial environment can be
greater in an abandoned channel than in other in-channel locations. Aban-
doned channels are rarely subjected to hydraulic forces, consequently,
vegetation usually is established, and the stage of succession is dependent
on the time since the channel ceased to carry flow. Thus, vegetation must be
removed from these sites to expose gravel deposits. Removal of this habitat
results in a loss of feeding, nesting, and cover habitat for those sma I I
mammals and passerines that utilize riparian shrub thickets. Larger mammals,
being more mobile, are displaced to adjoining areas.
If the abandoned channel is scraped above the water table, the dis-
turbed site will initiate primary plant succession following site closure.
The time required to reach the pr ed i stur bance stage of vegetational succes-
sion is dependent on the geographical region and the vegetative charac-
teristics of the area. This process is the same as occurs in other recently
abandoned high-water channels and entails the same vegetational and faunal
communities. If the site is a pit that is permanently flooded, the site
would not return to a terrestrial environment in a relatively short time.
However, overall habitat diversity is increased. Further discussion of these
aspects is included in the section on pits.
The effects of siting a gravel removal operation in an abandoned chan-
nel, on the scenic quality of an area, reflect the changes occurring to the
terrestrial vegetation. The short-term effect is to expose an area that was
previously vegetated. The long-term effect in a scraped site depends on the
rate of revegetation of the disturbed area. Where a pit is dug the altera-
367
tion is long-term but, in fact, could blend more with the i nterspers i on of
cutoffs and lakes occurring naturally in the floodplain.
Adjoining Channel Locations
The Major Variable Matrix (Table I) includes four subdivisions under
adjoining channel locations. These are: point bar, lateral bar, mid-channel
bar, and bank. To thoroughly characterize the 25 study sites it was neces-
sary to utilize all of these subdivisions but the gravel removal effects are
similar for some. Therefore, the following discussion combines the three bar
locations and discusses banks separately. Remember, at a given material site
these bars and banks are associated with one of the three channel types
discussed in the previous section.
Point, Lateral, and Mid-Channel Bars. This discussion only considers
removing gravel from unvegetated bars with exposed gravel deposits. All
three gravel bars are usually numerous in braided systems but, in single
channel systems, usually only point and lateral bars are found.
The effect of removing gravel from a bar is to lower the elevation of
the bar thus allowing flow to inundate an area that was previously above
the low-flow water line. These sites are usually scraped. Maintenance of the
integrity and conformation of the bar will cause little permanent change to
channel hydraulics and will facilitate replenishment of the gravel during
subsequent high flows. Changes in the active channels can and probably will
occur where bar integrity is not maintained. In a braided river system this
change will be similar to the natural processes and the long-term effects
will be minimal. In a single-channel system redistributing flow by removing
bars can have long-term effects by changing the local hydraulics of the
channel. This hydraulic change could either decrease the lateral stability
of the channel or widen or deepen the flow because the cross-sectional area
is larger. Where the banks are stable, the river eventually will equilibrate
itself by reforming gravel bars as upstream bed load materials become avail-
able during subsequent high flows. Where banks are less stable it is pos-
368
sible that subsequent high flows will cause erosion due to the hydraulic
forces acting on the once protected banks. This could significantly alter
the local reach of a river.
This effect is less likely to occur in straight and perhaps sinuous
river systems because the flow is relatively unidirectional down the flood-
plain and direct hydraulic forces on the banks would be less than in a
meandering system. The effect on a meandering river could be to facilitate
the formation of cutoffs by increasing the hydraulic force on the inside
bank at the upstream end of a meander.
Removal or lowering of gravel bars will facilitate the spreading of
river flow when water levels are higher than during the gravel removal opera-
tion. This flow spread has the effect of reducing the depth and velocity of
the water and will increase sedimentation rates of both bed load and suspen-
ded materials. Additional ly, water temperature and dissolved oxygen contents
could change. Benthic communities would develop that are adapted to riffles
and less stable substrate. Fish would become redistributed with younger age
classes perhaps being attracted to the disturbed site where currents would
be less.
The effects to the terrestrial environment, of removing gravel from a
bar, are minimal if the integrity of the bar is basically maintained. The
only changes that could be expected are if the hydraulic regime of the river
channel is altered, thus, causing changes in adjacent vegetated areas. The
spreading of flow between the banks when bars are removed might attract
shorebirds for purposes of feeding. These effects would only be expected in
single-channel systems.
Removing gravel from isolated material sites using accepted mining
techniques from bars in braided river systems would have little or no effect
on the scenic quality of a floodplain. The lateral instability of the chan-
nels that characterize these systems would cause any changes resulting from
gravel removal to blend in with natural processes. Removal of bars in a
single channel system wi I I local ly affect the appearance of the river sys-
369
tern, the magnitude of effect depending completely on the degree to which the
bar was disturbed. Any significant changes to the hydraulic geometry of the
reach causing subsequent disturbance to adjacent vegetated areas will lo-
cally alter the appearance of the floodplain.
Banks. Probably the most consistent long-term changes to a floodplain
occurred when banks were destroyed or greatly modified during a gravel
removal operation. In these cases significant changes to the hydraulic
geometry of the river occurred. Banks typical ly are stable and function to
restrict the flow of the river to the channel except during high flows. When
these are removed or disturbed the river is no longer contained and it
begins to wander and erode the adjacent floodplain. This wandering results
from the hydraulic forces of the river impinging on newly exposed bank ma-
terial. Where banks are made of stable materials the degree of erosion
should not be greater on the newly exposed bank than what occurred natural ly
before the site disturbance. Where the newly exposed bank materials are not
stable erosion will occur at a rate faster than occurred previously. Also,
if the newly exposed bank is situated at an angle to the flow different than
what occurred natural ly in that reach of the river, erosion could be aggra-
vated because of the increased hydraulic force on the bank.
Generally, channel width increases with bank destruction. Previous
discussion identified that increased channel width can result in reduced
water velocity, reduced water depth, changes in water temperature, and
dissolved oxygen, and increased sedimentation. Aquatic biota would reflect
these altered habitat conditions by changes in benthic communities to those
that are adapted to riffle areas with unstable substrate and changes in
distribution of fish in the reach affected by the disturbance. Undercut and
vegetated banks are heavily utilized by fish as cover and removal of this
habitat can greatly reduce the local abundance of certain species.
The effects on the terrestrial environment include destruction of
riparian habitat during site clearing with resultant effects on faunal
distribution. The decreased lateral stability of the channel can cause more
destruction after site closure if hydraulic forces erode newly exposed
370
areas. In addition, even if the newly exposed banks are stable the hydraulic
forces occurring over the disturbed site would retard the re-establishment
of terrestrial floodplain habitat.
The effect on the scenic quality of the area will reflect the changes
occurring to the terrestrial environment and to the hydraulic geometry of
the river channel. Major changes to these aspects will greatly alter the
appearance of the floodplain in the affected reach.
Locations Separated From Active Channel
The five specific site locations identified in the Major Variables
Matrix (Table I) that are separated from the active channel are not mutually
discrete locations. That is, a site can exhibit a combination of these
locations by for example, being located near the channel on the outside of a
meander. Hence it is more difficult to assess the potential impact for these
locations than for those previously discussed. The following discussion has
been separated into two sections: inside and outside of meanders, and
islands. These then are discussed from the standpoint of whether a material
site is near or distant from the active channel.
The essential factor with sites in all of these locations is whether
diversion of the water out of the active channel and through the site is
possible. The distance between the material site and the active channel is
of major concern, but the height of the intervening bank certainly would be
a necessary consideration in this evaluation.
Inside and Outside of Meanders. The location of a site on the outside
of a meander is possible on any sized river system regardless of the areal
extent of the material site. This, however, is not the case on the inside
of meanders. In small river systems the areal extent of the floodplain or
terrace circumscribed by the meander can be quite small. In cases where
these were used for material sites, the surrounding areas, including the
channel, were often disturbed by the gravel removal operation. Therefore, to
371
limit activities to the inside of a meander and maintain undisturbed buffers
the site must be located on at least a medium sized river.
Any activity inside a meander, that would reduce the integrity of the
banks or weaken the cross-sectional area, could lead to premature cut off of
the meander. In many Alaskan rivers during breakup, water often flows over
the ice in the channel and, if sufficiently high, over the banks and down
the floodplain. A depression resulting from a material site located near the
channel on the inside of the meander would aid in channeling the water
through the site. Depending on the erodability of the soil separating the
material site from the channel, a channel could erode at both the upstream
and downstream portion of the meander and thus eventually establish a cut-
off. The erodability of the soil would govern the length of time required
for this natural event to occur. When a pit material site is connected to
the active channel, the probability of a cutoff occurring could be enhanced
greatly, even in a very short time. Such an event occurred at Skeetercake
Creek on the North Slope. The inside of a meander of this sma I I river was
mined for gravel and when the site was studied II years after site closure,
a cutoff had occurred. The time required for this event to occur is unknown.
A pit visited during site selection, but not studied in this project,
that showed a potential for channel diversion, was located at Hess Creek in
the Southern Interior region. The buffer strip was breached during the
first spring breakup following site opening while the site was being op-
erated. The initial breach was temporary and the water remained in the
active channel when the flow receded.
The key point of concern when mining in the inside of a meander is
maintenance of a sufficiently wide undisturbed buffer zone between the
active channel and the perimeter of the material site. The size will depend
greatly on factors such as the discharge of the river, flood frequency, and
soil erodability and must, therefore, be determined on a site-specific
basis. In order to maintain the integrity of the channel over the long-term
it may be necessary to dig deeper to obtain needed gravel volumes, rather
than decrease the buffer width.
372
Buffer zones are similarly important to separate the active channel
from material sites located on the outside of meanders. A breach occurring
in this situation would lengthen the meander. This breach probably would be
a temporary event during high flow periods and the river would maintain its
main flow through the active channel during lower water levels because of
the shorter downval ley distance. Periodic and aggravated damage to the area
between the material site and the active channel and perhaps the creation of
a backwater area in the material site, would occur from an outside meander
breach.
It is obvious that the closer a material site is to the active channel
the greater the probability of a permanent breach occurring in a short time.
Placement of a material site either on the inside or outside of a
meander has no effect on water quality, regardless of the distance sep-
arating the site from the channel. However, if water is ponded the water in
the pit would differ from that in the channel, as described in the section
on pits. Changes in water quality could result if a breach occurs. These
also are discussed in the section on pits.
Change will not occur to aquatic biota when material sites are located
away from the active channel. However, if high flow conditions reach a
material site, and cause either temporary or permanent ponding, fish could
become trapped in the site when the water recedes. Effects similar to those
described for connected pits could occur where the buffer is breached and a
pit site becomes connected to the active channel.
In general, locating material sites back from the active channel will
necessarily entail destruction of vegetative habitat. This will result in
local ized loss of sma I I mammals and displacement of birds and larger mam-
mals. If the area is scraped and does not become flooded during high water
the site eventually will return to the pr ed i sturbance condition through
processes of primary and secondary plant succession. The length of time
required will depend on the regional characteristics. If the site is flooded
373
because it was dug as a pit, or because depressions are at least temporarily
flooded, vegetative re-establishment will be retarded.
Because of the soil binding characteristics of vegetation, maintenance
of the vegetation on the buffer zone between the material site and the
active channel is important. The wider this zone the less the likelihood of
a breach. If a buffer breaches, the progressive erosion of soils and loss of
overlying vegetation will result in prolonged impact to the terrestrial
environment. Concern for maintenance of the natural hydraulic geometry in
the floodplain while selecting a material site location, and while operating
the site, will limit terrestrial change to the area of the disturbance.
The usual need to remove vegetation to operate a site away from the
active channel will affect the scenic quality of the floodplain environment.
The magnitude of effect will depend much on the shape of the site, whether
it conforms to natural land forms, and what the vegetative structure is in
the area. If the site is not visible from a road or other accessible vantage
point, the overal I impact wi I I occur only from the air. The distance of the
site from the active channel would not necessarily be related to the mag-
nitude of impact on the scenic qual ity but this would be determined on a
site-specific basis.
Islands. Material sites located on islands require the removal of
vegetation. The distance between the perimeter of the material site and the
active channel is the major consideration in the development of these sites.
Islands are situated in the active channel most of the time, thus, the
maintenance of buffer zone intregity is of greatest concern. If buffer zones
are removed or greatly disturbed the net long-term effect could be the loss
of the island, perhaps changing the hydraulic geometry significantly enough
to cause other changes within the floodplain.
Sites that have been located on islands where the banks were disturbed
or eliminated have had greater effect on the floodplain t-han those where
the site was developed total ly separate from the channel (e.g., Tanana
River-Downstream). In the latter case there was no change detectable to the
374
hydraulic regime of the channel. In the other cases, induced erosion of the
disturbed banks has had more prolonged effects than where this erosion has
not occurred. Again, of prime concern with material sites on islands, as
with other sites separated from the channel, is maintenance of the natural
hydraulic geometry of the river channel. If natural hydraulic forces erode
islands in a given reach of a river, the presence of a material site,
whether a pit or scrape, wi I I weaken the integrity of the island after
natural bank erosion reaches the perimeter of the site.
Development of material sites on islands where the perimeters of the
sites are separated from the channel, will have little effect on water
quality and aquatic biota. If the material site is flooded because it was
deeply dug, the contained water will be different than the water in the
active channel, as discussed under pit sites. If the site is flooded regu-
larly during high-flow conditions there is a potential for fish entrapment
as the water recedes. The long-term effect on aquatic biota depends on
whether the site is permanently flooded and the depth of the water. If the
site becomes connected to the active channel by breaching of the buffer
zone, the effect may be development of a braided section with the accom-
panying changes. Flooding of depressions in the disturbed area could cause
fish entrapment before the establishment of a braided pattern.
Terrestrially, the loss of vegetated habitat would result in loss of
both small mammals and perhaps some larger ones. Loss would depend on the
size relationship of the material site to the island, but would occur regu-
larly where a large proportion of the island is disturbed for the material
site. The mortality would occur as a result of animals not being able to
cross the river channel (s) to adjacent floodplain habitat.
The loss of vegetation on an island reduces the amount of bird nesting
habitat. This could affect the total productivity of an area more than if an
equivalent amount of vegetation were removed along the edges of the flood-
plain. This assumes that the island provides some protection from mammalian
predators unable to cross the intervening channels. Otherwise, the mobility
375
of birds allows them to redistribute in the floodplain just as large mammals
do that are dependent on floodplain habitat.
Material sites on islands will affect the scenic quality of the flood-
plain, but the type of vegetation characteristic of the area would determine
the long-term visibility of the site. Where stands of timber block view of
the site except from the air, as with the Tanana River-Downstream site,
little change would occur. Where such timber is not present the material
site could be quite conspicuous and affect the appearance of the floodplain
environment more than if the site was located along the edge of the flood-
plain. In either case, maintenance of an undisturbed buffer zone between the
material site and the active channel reduces the induced disturbances that
could further detract from the natural appearance of the floodplain.
Summary. The problems associated with material sites located separate
from the active channel are essential ly dependent upon maintenance of the
integrity of intervening buffer zones. Where this is maintained, and the
hydraulic geometry of the river is not affected, very little or no change
would be expected relative to hydrology-hydraulics, water quality, and
aquatic biota. The terrestrial system and scenic quality of the floodplain
will be affected because usual ly vegetation must be removed to expose under-
lying gravel deposits. Generally, sites located back from the channel are
favored from a practical standpoint because they can be operated in a dry
condition making for a more efficient and easier operation. Excavating a pit
would be an exception because the depths of excavation would normally be
below the water table.
DIKES AND STOCKPILES
The location of certain material sites and the gravel removal opera-
tions require the construction of a protective structure and/or the stock-
piling of overburden and gravel in or near the material site. Protective
structures prevent water from entering the material site and include channel
plugs and diversion dikes. Overburden piles consisting of brush, slash,
groundcover, and organic soil are located either permanently or temporarily.
376
usual ly at the edges of sites. Gravel stockpi les are considered to be tem-
porary and are located within the material site. Dikes and stockpiles of
unused gravel were sometimes left intact when the site was abandoned, thus,
contributing to the long-term effect of the gravel removal operation.
Any dikes or stockpiles deflecting or otherwise modifying flow patterns
could aggravate the long-term hydraulic effects of the material site. Flow
alterations could significantly modify the hydraulic forces in the local
reach of the affected floodplain and cause other damage. Alterations to
natural flow patterns in the winter could induce or aggravate auf e i s forma-
tion.
The water quality of an area could be affected by the location of these
structures in the floodplain. Any erosion of overburden piles by active flow
could introduce large quantities of organic materials for suspension and
eventual downstream deposition. Also, any structures that would impound
waters, after high flows have receded, would result in differences in the
water quality between the active channel and impounded waters.
Aquatic biota could be affected by the presence of obstructions. Fish
could become entrapped behind any structures that impound water. The suspen-
sion of fines in the water column as a result of erosion could cause redis-
tribution of fish and reduction of riffle invertebrates.
Overburden piles provided a nucleus for revegetation of abandoned
material sites. The organics, and particularly the root stocks and slash,
facilitated re-establishment of vegetation in localized areas of the site.
Overburden piles were used for denning by ground squirrels and, because they
were vegetated, provided habitat for small mammals and nesting passerine
birds. Abandoned stockpiles of gravel were less prone to provide these
cond i t i ons.
In the long-term, any alterations of flow patterns that resulted from
abandoned structures probably would be detrimental to vegetative recovery
377
on the site. Revegetation in these cases would only occur on the area above
the h i gh f I ow I eve I s.
Abandoned structures in most cases further detract from the already af-
fected scenic quality of a floodplain. Where the site is hidden from view
except from the air abandoned structures would not alter the overall impact.
However, in places characterized by tundra and low riparian vegetation,
these abandoned structures can attract attention to the floodplain site.
378
SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS
SUMMARY
Not al I of the major variables used to characterize the 25 material
sites were significant determinants of gravel removal effects.
Among the Physical Site Characteristics, channel configuration was the
most important. Potential floodplain change is least for a braided river and
greatest for a straight river. Size of channel is a significant factor, with
the least change to be expected in a large system and the greatest in a
small system. This assumes equally sized material sites. Combining these two
variables, (channel configuration and size) gravel removal operations can be
expected to have the least effect on large braided rivers and the greatest
effect on small straight rivers.
Influencing Physical Site Characteristics related to configuration and
size are the availability and size of unvegetated gravel bars, floodplain
width, and the distance that can be maintained between the mining site and
active channel. For example, in a small straight river system the floodplain
is narrow and gravel bars are neither plentiful nor large. Thus, to extract
gravel, either a significant length of active floodplain or the adjacent
inactive floodplain and terrace must be disturbed. In the latter case the
narrowness of the floodplain forces the operation to closely encroach upon
the active channel. In large river systems these problems can be less signif-
icant because gravel bars are larger and, if the inactive floodplain or
terrace are used, the wider floodplain al lows maintenance of a broader
undisturbed buffer zone between the material site and active floodplain.
379
In the present study, channel slope and stream origin did not correlate
with changes resulting from gravel mining. However, channel slope influences
the bed load carrying capacity of a stream — steeper slopes indicate
greater carrying capacity. This relationship is useful in evaluating po-
tential replenishment rates in a disturbed site after mining. Also, stream
origin has an influence because rivers of mountain and glacial origin charac-
teristically have larger quantities of gravel available than do rivers of
coastal plain or i g i n.
All of the Gravel Removal Area Characteristics were found to signifi-
cantly influence the effects of gravel mining. The location of the material
site relative to the active channel is considered to be the most important
factor. Whether a material site is scraped or pit-excavated is important,
but often pits are located away from an active channel, avoiding the types
of changes that can be associated with scraping in active floodplains.
The major effects of pit sites located in inactive floodplains and
terraces are the loss of vegetated habitat, the possibility for fish entrap-
ment, a change in the appearance of the floodplain, and long-term delay
in the re-establishment of pr ed i sturbance conditions. Where pit sites are
situated well away from active channels they have little effect on the
active channel and, there is little chance of contributing to channel diver-
sion. When situated close to active channels, particularly on the inside
bends in meandering systems, the possibility exists for diversion of the
channel through the pit, eventual ly forming a channel cutoff in the meander.
This problem highlights the importance of providing a buffer between the
material site and the active channel. Where pit sites are of suitable size,
of sufficient depth, and have contoured perimeters, they can increase local
habitat diversity and provide conditions suitable for fish and various
species of terrestrial fauna.
Scraped material sites in active floodplains have minimal effects on
the floodplain environment when exposed gravel bars are only excavated above
the water level and slope and contours are maintained resembling those
of natural bars. Removal of vegetated areas or banks, which results in
380
decreased lateral stability of active channels, or allows water to spread
over a large area, is not desirable. Decreased water depth and velocity
increases sedimentation rates, alters water temperature, and alters dis-
solved oxygen levels. These chan9,es in aquatic habitat usually affect the
local distribution and community structure of benthos and fish.
The effects of scraping in vegetated areas of inactive floodplains and
terraces can be similar to those described for pits. However, long-term
changes typically are minimal because the lack of standing water in the
closed site will facilitate re-establi shment of pre-mi ning vegetation con-
d i t i ons.
In-channel locations that are dredged have the potential for causing
the least change to channel hydraulics, terrestrial biota, and aesthetics;
however, they can have the greatest effect on water quality and aquatic
biota. Gravel replenishment rates are highest in this location. Mining
exposed gravel bars in active floodplains potentially has the least effect
on terrestrial systems. Sites in inactive floodplains and terraces affect
the terrestrial biota and scenic quality most, but potentially have no
affect on the aquatic system. In general, the farther a material site is
located from a channel the greater the potential effect on the terrestrial
biota and scenic quality and the smaller the effect on the channel
hydrology-hydraulics, aquatic biota, and water quality. This relationship
constitutes the major tradeoff consideration in locating material sites in
f I oodp I a i ns.
If material sites are located and operated to prevent or greatly mini-
mize effects on channel hydraulics, and to utilize only exposed gravel bars,
the probability of major localized changes to a floodplain is generally
greatly reduced. Where exposed gravel bars are not available or are inade-
quate, a tradeoff decision between sites must be made that weighs the poten-
tial effects of aquatic disturbances against terrestrial disturbances. In
these cases, minimization of hydraulic change to active channels should be
important in the decision — major hydraulic changes can have a greater
long-term effect on terrestrial systems than the controlled disturbances
38 1
associated with a site located in a vegetated inactive floodplain or ter-
race.
Dikes and stockpiles of gravel and/or overburden left in a material
site after closure, have potential effects on the floodplain. These struc-
tures can alter channel hydraulics locally if they are subject to high
flows. During high water the fines and organic debris may be introduced
into the water and result in downstream sedimentation. Depending on their
position and orientation relative to flow, dikes and stockpiles can also
cause fish entrapment. Where overburden piles are above high-water levels,
they can facilitate the establishment of vegetation after site closure. This
vegetation provides habitat for small mammals and passerine birds. In some
cases, revegetation at a site was found only on such overburden piles. This
observation suggests that, as long as the piles are situated where they are
not subject to inundation or hydraulic erosion, they can provide a source
for revegetation of the site. Overburden piles may detract from the scenic
quality of a floodplain.
RECOMMENDATIONS
The recommendations developed for each of the disciplines are generally
in agreement, with several exceptions. All recommendations are generally
designed to minimize change to the floodplain and to enhance re-
establishment of pred i sturbance conditions.
I. River types that should be used in order of decreasing preference are:
braided, split, meandering, sinuous, and straight. The major consideration
in this preference is the availability of gravel from exposed bars. The
largest volumes are available from braided systems and the least from
straight systems. An additional factor is the decreasing floodplain width of
the configuration series identified above. If areas adjacent to the channel
must be used for gravel mining, greater overall change will result in
straight systems.
582
2. River sizes that should be used in order of decreasing preference are:
large, medium, and small. The rationale is the availability of gravels and
width of floodplain. Larger systems have more gravel. The proportionally
smaller disturbance in large systems will reduce the overall effect of
grave I r emova I .
3. Mining gravel from active channels should be avoided to reduce detrimen-
tal effects on water quality, aquatic habitat, and biota. However, if hy-
draulic changes can be minimized, in-channel sites will replenish more
rapidly than other areas and effects on the terrestrial biota and scenic
quality of the floodplain will be avoided or greatly minimized.
4. Changes to channel hydraulics should be avoided in all cases, es-
pecially the establishment of a braided configuration in the disturbed site.
5. When possible, exposed gravel bars in large active floodplains should
be considered for mining. A properly operated material site in these areas
can minimize changes to channel hydraulics during low-flow periods, minimize
changes to water quality and aquatic biota, minimize or eliminate affects on
terrestrial biota, and maintain the scenic quality of the floodplain. In
addition, the probability of gravel replenishment is increased.
6. Although pits reflect a major change from predi sturbance conditions,
they can increase local habitat diversity if suitably located and developed.
They should be located to minimize the probability of channel diversion
through the site. Adequate undisturbed buffers should be maintained between
the material site and the active channel.
7. Organic debris and overburden should be spread over or piled in the
abandoned site to promote revegetation and establishment of predi sturbance
conditions. This procedure must be conducted only in situations where there
is a low likelihood of this material being eroded into active channels.
383
RECOMMENDED FUTURE STUDIES
During the present study a number of subject areas were identified that
should be investigated.
1. Evaluation of gravel mining from coastal and upland sources; and,
preparation of guidelines for users of these sources. These alternatives to
floodplain sources have not been studied.
2. Evaluation of the effects of multiple sites on one river system.
Such an investigation should be aimed at determining the critical, spatial,
and temporal relationships of multiple sites. Gravel replenishment rate pre-
dictions should be an integral part of this investigation.
3. Several floodplain gravel removal sites should be investigated
before, during, and after mining to assess the adequacy of the Guidelines
Manua I .
4. Several specific topics of the Guidelines Manual should be studied
in detail to assess their adequacy, i.e., buffers, pit design, and active
channel dredging.
384
APPENDIX A
Scientific names of flora and fauna identified in the text are presented
in Tables A- I through A-5. References are:
Herbaceous Vegetation - Hulten, E. 1968. Flora of Alaska and Neighboring
Terr i tor ies. Stanford Univ. Press. 1,008 pp.
Woody Vegetat ion - Viereck, L. A., and E. L. Little, Jr. 1972. Alaska Trees
and Shrubs. U.S. Dept. Agric. Handbook 410. 265 pp.
Mammals - Hall, R. H., and K. R. Kelson. 1959. The Mammals of North America,
Ronald Press Co., New York. 2 vols.
Birds - American Ornithologists' Union. 1957. Check-list of North American
Birds. Port City Press, Inc., Baltimore. 69 1 pp.
American Ornithologists' Union. 1976. Thirty-third supplement to the
AOU check-list of North American Birds. Auk 93(41:875-879.
Fish - Alaska Department of Fish and Game. 1978. Alaska's Fisheries Atlas.
Vol. I and II. Alaska Dept. Fish and Game, Juneau, Alaska. 83 pp. +
maps .
Bailey, R. M. , J. E. Fitch, E. S. Herald, E. A. Lachner, C. C. Lindsey,
C. R. Robins, and W. B. Scott. 1970. List of Common and Scientific
Names of Fishes from the United States and Canada. Third edition.
American Fisheries Soc. Spec. Publ. No. 6. 150 pp.
McPhail, J. D., and C. C. Lindsey. 1970. Freshwater Fishes of North-
western Canada and Alaska. Fish. Res. Bd. Canada. Bull. No. 173. 381 pp.
Morrow, J. E. 1974. Freshwater Fishes of Alaska. Alaska Northwest
Publishing Co., Anchorage, Alaska. 78 pp.
385
Table A- I . Vegetation Identified in the Text
Common Name
Her set a i I
Reed Bent Grass
Poa
Cotton Grass
Sedge
Rush
Ba I sam Pop I ar
Pel t leaf Wi I low
Littletree Willow
Paper Birch
American Green Alder
Th i n I eaf Al der
Ch i ckweed
Mi Ik Vetch
Oxy trope
Sweet Pea
Dwarf Fireweed
S iber i an Aster
F I eabane
Wormwood
Hawk's Beard
Sc i ent i f i c Name
Equisetum variegatum
Ca I amagrost i s spp.
Poa spp.
Er iophor urn spp .
Carex spp.
Juncus spp.
Populus balsamifera
Sa
1 ix
a 1 axens i s
Sa
1 ix
tule
nus
arbuscu
1 oi des
Be
a papyr i \
Fera
Al
cr i spa
Al
nus
tenu i f 0
1 ia
Ste I I ar i a spp.
Astragalus spp.
Oxytropis spp.
Hedysarum Mackenzii
Epilobium latifolium
Aster s ib ir icus
Erigeron spp.
Artemisia spp.
Crepis nana
386
Table A-2. Mammals IdenHfied in the Text
Common Name
Sc ient i f i c Name
Arctic Ground Squirrel
Red Squirrel
Beaver
Tundra Vole
S ing i ng Vo I e
Muskrat
Gray Wo I f
Black Bear
Grizzly Bear
Moose
Car i bou
Spermoph i I us undulatus
Tamiasciurus hudsonicus
Castor canadensis
M
icrotus
icrotus
ndatra .
oeconomus
M
Ol
mi urus
z ibeth icus
Can i s I upus
Ursus
amer icanus
Ursus
horr ib i 1 is
A 1 ces
Alces
Rang i f er tarandus
387
jable A-3. Birds Identified in the Text
Common Name
Wh i st I i ng Swan
Trumpeter Swan
Canada Goose
Black Brant
Mai lard
P intai I
Green-winged Teal
Common Goldeneye
Barrow's Goldeneye
Buff lehead
Red-breasted Merganser
Semipalmated Plover
Ruddy Turnstone
Semipalmated Sandpiper
Western Sandpiper
Spotted Sandpiper
Northern Phalarope
Gl aucous Gu I I
Herr i ng Gu II
Mew Gull
Arctic Tern
Alder Flycatcher
Tree Swal low
Violet-green Swal low
Bank Swa I I ow
Gray Jay
Black-capped Chickadee
American Robin
Sc i en
t i
f ic Name
01 or
col umb i anus
01 or
bucci nator
Brant
a
a
canadensi s
Brant
Anas
n i gr i cans
1 atyrhynchos
Anas acuta
Anas caro I i nens i s
Bucephala c I angu I a
Bucephala i s I and i ca
Bucephala a I beol a
Mergus serrator
Charadrius semi pha Imatus
Arenaria i nterpres
Caldr
Caldr
Act it
i s
i s
is
= s
h'
pusi 1 1 us
maur i
macu 1 ar i a
Lob ipi
lobatus
Larus
yperboreus
Larus
argent at us
Larus
canus
Sterna par adi saea
Empidonax ainorum
Ir i doprocne b i co I or
Tachyci neta tha I assi na
Ripar i a r ipar i a
Perisoreus canadens i s
Parus atr icap i I I us
Turdus mi grator i us
cont i nued
388
Table A-3.
[ Cone I uded )
Common Name
Sc i ent i f i c Name
Gray-cheeked Thrush
Ye I I ow Wagt a i I
Orange-crowned Warbler
Ye I low Warbler
Ye I I ow-r umped Warbler
Northern Waterthrush
Wi I son ' s Warb ler
Common Redpo I I
Dark-eyed Junco
Tree Sparrow
White-crowned Sparrow
Fox Sparrow
Catharus minima
Motaci 1 1 a
f 1 ava
Vermi vor a
ce 1 ata
Dendroica
petech i a
Dendroica
coronata
Seiurus novebor acens i s
Wi I son i a pus i I I a
Acanth is f I ammea
Junco hyema I i s
Sp i ze I la arborea
Zonotrichia leucophrys
Passere I I a i I i aca
389
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39 1
Table A-5. Aquatic Macro i nvertebrates Caught at Study Sites During
1976-1978 Field Samp I ing
Taxon
Common name
Nematoda
01 i gochaeta
P I ecoptera
A I I oper I a
Arcynopter yx
Capn i a
Di ura
Hastaper I a
I sogenus
I soper I a
Nemour a
Par aper I a
Ephemeroptera
Ame I etus
Baet i nae
Caeni s
Ca I I ibaet i s
Centropt i I um
Ci nygmu I a
Epeorus
Ephemere I I a
Heptagen i a
Rh i throgena
S i ph I onur us
Odonata
Ena I I agma
I schnur a
L i be I I u I i dae
Tr i choptera
Apatan i a
Arctopsyche
Brachycentrus
Ecc I i somy i a
G I ossosoma
Homophy I ax
Hydatophy I ax
Lep i dostoma
Leptoce I I a
L i mneph i I us
round worms
ear thworms
stonef I ies
may f I i es
dragonflies and damsel flies
caddl sf I i es
Cont i nued
592
Table A-5.
I Cone I uded )
Taxon
Common name
Oecet is
Onocosmoecus
Phryganea
P 1 atycentropus
Pol ycentropus
Pseudostenophylax
Psychog 1 ypha
Rhyacoph i I a
Hemi ptera
Cor i X i dae
Col eoptera
Dy t i sc i dae
Hal i p I i dae
D iptera
Ather i c i dae
Ceratopogon i dae
Ch i ronomi dae
Eph i d i dae
Emp I d i dae
Psychod i dae
S imu I i i dae
T i pu I i dae
Hydracar i na
Mol I usca
Lymnaea
Physi dae
P i s i d i um
P I anorb i dae
Va I vata
Amph i poda
Gammar i dae
water bugs
waterboatman
beet I es
diving beet I e
f I i es
biting mi dge
mi dge
b I ackf I y
crane f I y
mi tes
mo I I uses
snai I
snai I
f i ngerna i I c I am
snai I
snai I
amph i pods
393
APPENDIX B
GLOSSARY
abandoned channel — A channel that was once an active or high-water chan-
nel, but currently flows only during infrequent floods.
active channel — A channel that contains flowing water during the ice-free
season.
active floodplain — The portion of a floodplain that is flooded frequently;
it contains flowing channels, high-water channels, and adjacent bars,
usually containing little or no vegetation.
aesthetics — An enjoyable sensation or a pleasurable state of mind, which
has been instigated by the stimulus of an outside object, or it may
be viewed as including action which will achieve the state of mind de-
sired. This concept has a basic psychological element of individual
learned response and a basic social element of conditioned social atti-
tudes. Also, there can be ecological conditioning experience because
the physical environment also affects the learning process of attitudes.
algae — Primitive plants, one or many-celled, usually aquatic and capable
of elaborating the foodstuffs by photosynthesis.
aliquot — A portion of a gravel removal area that is worked independently,
often sequentially, from the other portions of the area.
alluvial river — A river which has formed its channel by the process of
aggradation, and the sediment by which it carries (except for the wash
load) is similar to that in the bed.
arctic — The north polar region bounded on the south by the boreal forest.
armor layer — A layer of sediment that is coarse relative to the material
underlying it and is erosion resistant to frequently occurring floods;
it may form naturally by the erosion of finer sediment, leaving coarser
sediment in place or it may be placed by man to prevent erosion.
auf ei s — An ice feature that is formed by water overflowing onto a surface,
such as river ice or gravel deposits, and freezing, with subsequent
layers formed by water overflowing onto the ice surface itself and
f reez i ng .
395
backwater analysis — A hydraulic analysis, the purpose of which is to
compute the water surface profile in a reach of channel with varying
bed slope or cross-sectional shape, or both.
bank — A comparatively steep side of a channel or floodplain formed by an
erosional process; its top is often vegetated.
bank-full discharge — Discharge corresponding to the stage at which the
overflow plain begins to be flooded.
bar — An al I uv i a I deposit or bank of sand, gravel, or other material, at
the mouth of a stream or at any point in the stream flow.
beaded stream — A sma I I stream containing a series of deep pools intercon-
nected by very small channels, located in areas underlain by permafrost.
bed — The bottom of a watercourse.
bed load — Sand, silt, gravel or soil and rock detritus carried by a stream
on, or immediately above its bed.
bed load material — That part of the sediment load of a stream which is
composed of particle sizes found in appreciable quantities in the shift-
ing portions of the stream bed.
bed, movable — A stream bed made up of materials readily transportable by
the stream flow.
bed, stream — The bottom of a stream below the low summer flow.
braided river — A river containing two or more interconnecting channels
separated by unvegetated gravel bars, sparsely vegetated islands, and,
occasionally, heavily vegetated islands. Its floodplain is typically
wide and sparsely vegetated, and contains numerous high-water channels.
The lateral stability of these systems is quite low within the boun-
daries of the active floodplain.
carrying capacity, biological — The maximum average number of a given organ-
ism that can be maintained indefinitely, by the habitat, under a given
regime (in this case, flow).
carrying capacity, discharge — The maximum rate of flow that a channel is
capab I e of pass i ng .
channel — A natural or artificial waterway of perceptible extent which
periodically or continuously contains moving water. It has a definite
bed and banks which serve to confine the water.
configuration — The pattern of a river channel (s) as it would appear by
looking vertical ly down at the water.
contour — A line of equal elevation above a specified datum.
596
cover, bank — Areas associated with or adjacent to a stream or river that
provide resting shelter and protection from predators - e.g., undercut
banks, overhanging vegetation, accumulated debris, and others.
cover, fish — A more specific type of instream cover, e.g., pools,
boulders, water depths, surface turbulence, and others.
cover, instream — Areas of shelter in a stream channel that provide aquatic
organisms protection from predators or a place in which to rest, or
both, and conserve energy due to a reduction in the force of the cur-
rent .
cross section area — The area of a stream, channel, or waterway opening,
usually taken perpendicular to the stream centerline.
current — The flowing of water, or other fluid. That portion of a stream
of water which is moving with a velocity much greater than the average
or in which the progress of the water is principally concentrated (not
to be confused with a unit of measure, see velocity).
datum — Any numerical or geometrical quantity or set of such quantities
which may serve as a reference or base for other quantities. An agreed
standard point or plane of stated elevation, noted by permanent bench
marks on some solid immovable structure, from which elevations are meas-
ured, or to which they are referred.
dewater — The draining or removal of water from an enclosure or channel.
discharge — The rate of flow, or volume of water flowing in a given stream
at a given place and within a given period of time, expressed as cu
ft per sec.
drainage area — The entire area drained by a river or system of connecting
streams such that all stream flow originating in the area is discharged
through a single outlet.
dredge — Any method of removing gravel from active channels.
drift, invertebrate — The aquatic or terrestrial invertebrates which have
been released from (behavioral drift), or have been swept from (catas-
trophic drift) the substrate, or have fallen into the stream and move
or float with the current.
duration curve — A curve which expresses the relation of al I the units of
some item such as head and flow, arranged in order of magnitude along
the ordinate, and time, frequently expressed in percentage, along the
abscissa; a graphical representation of the number of times given
quantities are equaled or exceeded during a certain period of record.
erosion, stream bed — The scouring of material from the water channel and
the cutting of the banks by running water. The cutting of the banks
is also known as stream bank erosion.
397
fines — The finer grained particles of a mass of soil, sand, or gravel. The
material, in hydraulic sluicing, that settles last to the bottom of
a mass of water.
f lood — Any flowwhich exceeds the bank-full capacity of a stream or chan-
nel and flows out on the floodplain; greater than bank-full discharge.
floodplain — The relatively level land composed of primarily unconsolidated
river deposits that is located adjacent to a river and is subject to
flooding; it contains an active floodplain and sometimes contains an
inactive floodplain or terrace(s), or both.
flood probability — The probability of a flood of a given size being
equaled or exceeded in a given period; a probability of I percent would
be a 100-year flood, a probability of 10 percent would be a 10-year
f lood.
flow — The movement of a stream of water or other mobile substances, or
both, from place to place; discharge; total quantity carried by a
stream.
flow, base — That portion of the stream discharge which is derived from
natural storage - i.e., groundwater outflow and the draining of large
lakes and swamps or other sources outside the net rainfall which
creates the surface runoff; discharge sustained in a stream channel,
not a result of direct runoff and without the effects of regulation,
diversion, or other works of man. Also called sustaining flow.
flow, laminar — That type of flow in a stream of water in which each par-
ticle moves in a direction parallel to every other particle.
flow, low — The lowest discharge recorded over a specified period of time.
flow, low summer — The lowest flow during a typical open-water season.
flow, uniform — A flow in which the velocities are the same in both magni-
tude and direction from point to point. Uniform flow is possible only
in a channel of constant cross section.
flow, varied — Flow occurring in streams having a variable cross section
or slope. When the discharge is constant, the velocity changes with
each change of cross section and slope.
fork length — The length of a fish measured from the tip of the nose to the
fork in the tail.
freeze front — A surface that may be stationary, which has a temperature
of 0 C and is warmer on one side of the surface and colder on the
other.
frequency curve — A curve of the frequency of occurrence of specific
events. The event that occurs most frequently is termed the mode.
398
gage — A device for indicating or registering magnitude or position in spe-
cific units, e.g., the elevation of a water surface or the velocity
of flowing water. A staff graduated to indicate the elevation of a
water surface.
geomorphology — The study of the- form and development of landscape fea-
tures.
habitat — The place where a population of animals lives and its sur-
roundings, both living and nonliving; includes the provision of life
requirements such as food and shelter.
high-water channel — A channel that is dry most of the ice-free season,
but contains flowing water during floods.
hydraulics — The science dealing with the mechanical properties of fluids
and their application to engineering; river hydraulics deals with
mechanics of the conveyance of water in a natural watercourse.
hydraulic depth — The average depth of water in a stream channel. It is
equal to the cross-sectional area divided by the surface width.
hydraulic geometry — Those measures of channel configuration, including
depth, width, velocity, discharge, slope, and others.
hydraulic radius — The cross-sectional area of a stream of water divided
by the length of that part of its periphery in contact with its contain-
ing channel; the ratio of area to wetted perimeter.
hydrograph — A graph showing, for a given point on a stream, the discharge,
stage, velocity, or another property of water with respect to time.
hydrology — The study of the origin, distribution, and properties of water
on or near the surface of the earth.
ice-rich material — Permafrost material with a high water content in the
form of ice, often taking the shape of a vertical wedge or a horizontal
lens.
impervious — A term applied to a material through which water cannot pass
or through which water passes with great difficulty.
inactive f I oodp I a i n — The portion of a floodplain that is flooded infre-
quently; it may contain high-water and abandoned channels and is
usually lightly to heavily vegetated.
island — A heavily vegetated sediment deposit located between two channels.
2
large river — A river with a drainage area greater than 1,000 km and a
mean annual flow channel top width greater than 100 m.
lateral bar — An unvegetated or lightly vegetated sediment deposit located
adjacent to a channel that is not associated with a meander.
399
Manning's equation — In current usage, an empirical formula for the calcula-
tion of discharge in a channel. The formula is usually written
Q = l^R 2/3 31/2 ^_
n
mean flow — The average discharge at a given stream location computed for
the period of record by dividing the total volume of flow by the number
of days, months, or years in the specified period.
mean water velocity — The average velocity of water in a stream channel,
which is equal to the discharge in cubic feet per second divided by
the cross-sectional area in square feet. For a specific point location,
it is the velocity measured at 0.6 of the depth of the average of the
velocities as measured at 0.2 and 0.8 of the depth.
meander wave length — The average downvalley distance of two meanders.
meandering river — A river winding back and forth within the floodplain.
The meandering channel shifts downvalley by a regular pattern of ero-
sion and deposition. Few islands are found in this type of river and
gravel deosits typically are found on the point bars at the insides of
meanders.
2
medium river — A river with a drainage area greater than 100 km but less
than 1,000 km and a mean annual flow channel top width greater than
15 m but less than 100 m.
microhabitat — Localized and more specialized areas within a community or
habitat type, utilized by organisms for specific purposes or events, or
both. Expresses the more specific and functional aspects of habitat and
cover that allows the effective use of larger areas (aquatic and ter-
restrial) in maximizing the productive capacity of the habitat. (See
cover types, habitat).
mid-channel bar — An unvegetated or lightly vegetated sediment deposit lo-
cated between two channels.
parameter — A variable in a mathematical function which, for each of its
particular values, defines other variables in the function.
permafrost — Perennially frozen ground.
pit excavation — A method of removing gravel, frequently from below over-
burden, in a manner that results in a permanently flooded area. Gravels
are usually extracted using draglines or backhoes.
point bar — An unvegetated sediment deposit located adjacent to the inside
edge of a channel in a meander bend.
pool — A body of water or portion of a stream that is deep and quiet rela-
tive to the main current.
400
pool, plunge — A pool, basin, or hole scoured out by falling water at the
base of a water fa I I .
profile — In open channel hydraulics, it is the water or bed surface ele-
vation graphed aganist channel distance.
reach — A comparatively short length of a stream, channel, or shore.
regional analysis — A hydrologic analysis, the purpose of which is to esti-
mate hydrologic parameters of a river by use of measured values of the
same parameters at other rivers within a selected region.
riffle — A shal low rapids in an open stream, where the water surface is
broken into waves by obstructions wholly or partly submerged.
riparian — Pertaining to anything connected with or adjacent to the banks
of a stream or other body of water.
riparian vegetation — Vegetation bordering floodplains and occurring within
f I oodp I a i ns.
riprap - Large sediments or angular rock used as an artificial armor layer.
river regime — A state of equilibrium attained by a river in response to
the average water and sediment loads it receives.
run — A stretch of relatively deep fast flowing water, with the surface
essentially nont urbu I ent .
scour — The removal of sediments by running water, usual ly associated with
removal from the channel bed or floodplain surface.
scrape - A method of removing floodplain gravels from surface deposits using
tractors or scrapers.
sediment discharge — The volumetric rate of sediment transfer past a spe-
cific river cross section.
sinuous river — Sinuous channels are similar to meandering channels with
a less pronounced winding pattern. The channel may contain smaller
point bars and have less tendency for downvalley shifting. The channels
are more stable with respect to lateral shifting.
sinuousity — A measure of the amount of winding of a river within its flood-
plain; expressed as a ratio of the river channel length to the corres-
ponding valley length.
slope — The inclination or gradient from the horizontal of a line or sur-
face. The degree of inclination is usually expressed as a ratio, such
as 1:25, indicating one unit rise in 25 units of horizontal distance.
401
2
sma I I river - A river with a drainage area less than 100 km and a mean
annual flow channel top width of less than 15 m.
split river — A river having numerous islands dividing the flow into two
channels. The islands and banks are usually heavily vegetated and
stable. The channels tend to be narrower and deeper and the f I oodp I a i n
narrower than for a braided system.
stage — The elevation of a water surface above or below an established
datum or reference.
standing crop — The abundance or total weight of organisms existing In an
area at a given time.
straight river — The thalweg of a straight river typically winds back and
forth within the channel. Gravel bars form opposite where the thalweg
approaches the side of the channel. These gravel bars may not be ex-
posed during low flow. Banks of straight systems typically are stable
and f loodplains are usual ly narrow. These river systems are considered
to be an unusual configuration in transition to some other configura-
tion.
subarctic — The boreal forest region.
suspended load — The portion of stream load moving in suspension and made
up of particles having such density of grain size as to permit movement
far above and for a long distance out of contact with the stream bed.
The particles are held in suspension by the upward components of turbu-
lent currents or by colloidal suspension.
talik — A zone of unfrozen material within an area of permafrost.
terrace — An abandoned floodplain formed as a result of stream degradation
and that is expected to be inundated only by infrequent flood events.
thalweg — The line following the lowest part of a valley, whether under
water or not; also usually the line following the deepest part or
middle of the bed or channel of a river or stream.
thermokarst — Landforms that appear as depressions in the ground surface
or cavities beneath the ground surface which result from the thaw of
ice-rich permafrost material.
top width — The width of the effective area of flow across a stream chan-
ne I .
velocity — The time rate of motion; the distance traveled divided by the
time required to travel that distance.
wash load — In a stream system, the relatively fine material in near-perman-
ent suspension, which is transported entirely through the system,
without deposition. That part of the sediment load of a stream which is
composed of particle sizes smaller than those found in appreciable
quantities in the shifting portions of the stream bed.
402
water quality — A term used to describe the chemical, physical, and biolog-
ical characteristics of water in reference to its suitability for a
par t i cu I ar use.
wetted perimeter — The length of the wetted contact between the stream of
flowing water and its containing channel, measured in a plane at right
angles to the direction of flow.
wildlife — All living things that are neither human nor domesticated; most
often restricted to wildlife species other than fish and invertebrates.
403
50272-101
REPORT DOCUWENTATrON.
PAOC
1. REPORT NO.
FWS/08S-80/08
3. Recipient's Accession No.
4. Title and Subtitle
GRAVEL REMOVAL STUDIES IN ARCTIC AND SUBARCTIC FLOODPLAINS
IN ALASKA - TECHNICAL REPORT
5. Report Date
June 1980, Pub. date
7. Author(s)
8. Performing Organization Rept. No.
WOODWARD-CLYDE CONSULTANTS
9. Performing Organization Name and Address
Woodward-Clyde Consultants
4971 Business Park Blvd., Suite #1
Anchorage, Alaska 99503
10. Project/Tssk/Work Unit No.
II. Contract(C) or Grant(G) No.
(C)FWS 14-16-0008-970
(G)
12. Sponsoring Organization Name and Address
U. S. Fish and Wildlife Service
1011 East Tudor Road
Anchorage, Alaska 99503
13. Type of Report & Period Covered
Final Report
1975 - 1980
14.
IS. Supplementary Notes
This report is part of Interagency Energy - Environment Research and Development Program
of the Office of Research and Development, U.S. Environmental Protection Agency
16. Abstract (Limit: 200 words)
A 5-year investigation
and biological charact
is described. Twenty-f
sites were selected su
a wide range of river
covered the major disc
quality, and terrestri
tics site reviews were
biological changes wer
observed at some sites
hydraulics, sedimentat
macroi nvertebrates, fi
mammal usage.
of the effects of f
er ist ics of r i ver sy
ive sites were studi
ch that within each
and mining character
iplines of hydrology
al biology. In addit
conducted. A wide r
e observed in respon
, whereas other site
ion, ice regime, aqu
sh ut i I izat ion , vege
loodplain gravel mining on th
stems in arctic and subarctic
ed within four geographic reg
of the regions the group of s
istics. The field data col lee
/hydraulics, aquatic biology,
ion, geotechnical engineering
ange of magnitude and type of
se to mining activity. Little
s exhibited changes in channe
atic habitat, water quality,
tation, soil characteristics.
e physical
Alaska
ions. The
ites exhibited
tion program
water
, and aesthe-
physical and
change was
I morphology,
benth ic
and bird and
Two major products of the project are a Technical Report which synthesizes and
evaluates the data collected at the sites, and a Guidelines Manual that aids the
user in developing plans and operating material sites to minimize environmental
ef fects.
17. Document Analysis a. Descriptors
Gravel Removal, Alaska, Arctic, Subarctic, Floodplains, Streams, Scraping, Pit
Excavation, Environmental Impacts, Hydrology-Hydraulics, Aquatic Biology, Terrestrial
Ecology, Water Quality, Aesthetics, Geotechnical Engineering, Site Selection, Site
Design.
b. IdentlFiers/Open-Ended Terms
c. COSATI Field/Group
18. Availability Statement
Release un I imi ted
19. Security Class (This Report)
Unci assi f ied
20. Security Class (This Page)
Unci assi f ied
21. No. of Pages
403
22. Price
(See ANSI-Z39.18)
See /nsfructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
<i U S GOVERNMENT PRINTING OFFICE I
REGIONAL OFFICE BIOLOGICAL SERVICES TEAMS
Region 1
Team Leader
U.S. Fish and Wildlife Service
Lloyd 500 Building, Suite 1692
500 N.E. Multnomah Street
Portland, Oregon 97232
FTS: 429-6154
COMM: (503)231-6154
Region 2
Team Leader
U.S. Fish and Wildlife Service
P.O. Box 1306
Albuquerque, New Mexico 87103
FTS: 474-2971
COMM: (505) 766-1914
Region 4
Team Leader
U.S. Fish and Wildlife Service
17 Executive Park Drive, N.W.
P.O. Box 95067
Atlanta, Georgia 30347
FTS: 257-4457
COMM: (404)881-4457
Region 5
Team Leader
U.S. Fish and Wildlife Service
One Gateway Center
Suite 700
Newton Corner, Massachusetts 02158
FTS: 829-9217
COMM:(617)965-5100, Ext. 217
Region 3
Team Leader
U.S. Fish and Wildlife Service
Federal Building, FortSnelling
Twin Cities, Minnesota 551 11
FTS: 725-3593
COMM; (612) 725-3510
Region 6
Team Leader
U.S. Fish and Wildlife Service
P.O. Box 25486
Denver Federal Center
Denver, Colorado 80225
FTS: 234-5586
COMM: (303) 234-5586
Alaslo Area Office
Team Leader
U.S. Fish and Wildlife Service
1011 E.Tudor Road
Anchorage, Alaska 99503
FTS: 399-0150 ask for
COMM: (907)276-3800
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