Alluvial Sand

National Park^ Arizona
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Aggradation and Degradation of 

Alluvial Sand Deposits, 1965 to 1986, 

Colorado River, Grand Canyon 

National Park, Arizona

By JOHN C. SCHMIDT and JULIA B. GRAF

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1493

Prepared in cooperation with the 

U.S. Bureau of Reclamation

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1990
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names in this publication

is for descriptive purposes only and does not imply endorsement

by the U.S. Government

Library of Congress Cataloging in Publication Data

Schmidt, John C., 1950-

Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, 

Arizona / by John C. Schmidt and Julia B. Graf.

p. cm. (U.S. Geological Survey professional paper ; 1493)

Includes bibliographical references.

Supt. of Docs, no.: I 19.16:1493

1. Sand Arizona Grand Canyon National Park. 2. Sedimentation and deposition Arizona Grand Canyon National 

Park. 3. Alluvium Arizona Grand Canyon National Park. I. Graf, Julia B. II. Title. III. Series.

QE471.2.S351989 551.3'53'-dc20 89-600263

CIP

For sale by the Books and Open-File Reports Section, U.S. Geological Survey, 

Federal Center, Box 25425, Denver, CO 80225
CONTENTS

Introduction 1

Background 1

Purpose and scope 3

Acknowledgments 4

Terminology 4

Methods of analysis 4

Background 7

Physical and hydraulic characteristics of the channel 7

History of flow and sediment transport 9

Characteristics and classification of alluvial sand deposits 11

Separation deposits 14

Reattachment deposits 19

Upper-pool deposits 21

Channel-margin deposits 23

Distribution of deposits 23

Aggradation and degradation at Eighteen Mile Wash,

1965-86 25 

Hydraulic conditions 25

Aggradation and degradation at Eighteen Mile Wash,

1965-86 Continued

Topographic changes of the separation deposit 27

Bathymetric surveys 31

Aggradation and degradation of alluvial deposits, 1965-86 40

Changes in alluvial sand deposits, 1973-84 40

Flow characteristics 40

Changes in deposits 42

Changes in alluvial sand deposits, high flows, May 1985 43

Flow characteristics 43

Changes in deposits 43

Changes of alluvial sand deposits during strongly

fluctuating flow, October 1985 to January 1986 43

Flow characteristics 43

Changes in deposits 43

Comparison of changes in alluvial sand deposits 46

Summary 47

References cited 48

Appendix A Comparison of river mile inventories of 1973 and

1983 from Lees Ferry to Stone Creek 67

ILLUSTRATIONS

FIGURE l.Map showing study area and location of study sites 2

2. Graph showing instantaneous discharge at Lees Ferry gage, January 8-11, 1986, typical of fluctuating flows between

1965 and 1982 3

3. Diagrams showing flow patterns and configuration of bed deposits in a typical recirculation zone 5

4. Map showing reaches within the study area 8

5. Map showing surficial geology and hydraulic features at Badger Creek Rapid 10 

6-9. Graphs showing:

6. Change in length of recirculation zone with discharge at six sites 11

7. Typical particle-size distributions for samples of suspended sediment, bedload, and bed material from the

Colorado River near Grand Canyon at river mile 87 and for two alluvial sand deposits 12

8. Daily mean discharge of the Colorado River at Lees Ferry, 1957 13

9. Daily mean discharge of the Colorado River at Lees Ferry, 1982 to February 1986 13

10. Photograph showing separation deposits downstream from Badger Creek Rapid, July 30, 1985 14

11. Map showing surficial geology and hydraulic features near Eighteen Mile Wash 15

12. Map showing topography of a separation deposit at Eighteen Mile Wash in 1975 and at selected times in 1985 16

13. Cross section showing topography and sedimentology associated with upstream advancement of slipface, May 22, 1985,

and August 2, 1985, at Eighteen Mile Wash 18

14. Aerial photograph and map showing surficial geology and hydraulic features at Eminence Break Camp 20

15. Maps showing bathymetric contours within the recirculation zone at Eminence Break Camp 22

16. Graphs showing bed-surface profiles of a recirculation zone at Eminence Break Camp 24

17. Aerial photograph and map showing surficial geology, hydraulic features, area of sand inundated at different discharges, and

sediment-sampling sites at Saddle Canyon 26

18. Photograph showing reattachment deposit at Eminence Break Camp, October 12, 1985, discharge 3,000 ft3/s 28

19. Sketch showing reattachment deposit at low discharge 29

20. Sketch showing response of a reattachment deposit to decreasing discharge 29

in
IV CONTENTS

Page

FIGURE 21. Sketch showing area of bathymetric surveys and hydraulic features at Blacktail Rapid 29

22. Sketch showing bathymetric contours within a recirculation zone below Blacktail Rapid 30

23. Graphs showing bed-surface profiles of a recirculation zone below Blacktail Rapid 31

24. Sketch showing sedimentology exposed in a trench through the reattachment deposit at the site Above

Cathedral Wash 32

25. Graphs showing variation with river mile in number of alluvial deposits identified in 1983 as campsites 33

26. Aerial photographs showing Colorado River near Eighteen Mile Wash 34

27. Sketch showing topography along profile 2 at Eighteen Mile Wash 35

28. Graph showing discharge and stage during recession of high flows at Eighteen Mile Wash 36

29. Graph showing net-elevation change of separation deposit at Eighteen Mile Wash, 1965 to January 1986,

along profile 2 37

30. Aerial photograph and map showing area of bathymetric survey, surficial geology, and hydraulic features at

National Rapid 38

31. Maps showing bathymetric contours within a recirculation zone below National Rapid 39

32. Graphs showing bed-surface profiles of a recirculation zone below National Rapid 41

33. Graph showing vertical change along profile lines at 13 separation deposits between October 1985 and January 1986 44

34. Graphs and map showing surficial geology and topography along two profiles at Twenty-Nine Mile Rapid 45

TABLES

TABLE 1. Summary of study sites and types of data collected 51

2. Characteristics of the reaches within the study area 55

3. Channel geometry and hydraulic characteristics for selected sites 56

4. Detailed study sites in relation to reaches 58

5. Particle-size characteristics of alluvial sand deposits between Lees Ferry at river mile 0 and Bright Angel Creek at river

mile 87.5 58

6. Summary statistics of particle-size characteristics 60

7. Areas of alluvial sand deposits at low discharge in selected reaches, October 1984 60

8. Summary of changes between bathymetric surveys 61

9. Number of separation and reattachment deposits in recirculation zones between river miles 0 and 118, 1973 and 1984 62

10. Areas of major alluvial sand deposits in selected reaches, 1973 and 1984 62

11. Number of deposits that underwent change, 1973-84 63

12. Classification of deposits studied by Howard (1975) and Beus and others (1985) 63

13. Summary of measured changes at 20 sites during fluctuating flow, October 1985 to mid-January 1986 64

14. Areas of exposed sand at detailed study sites, 1965, 1973, and 1984 66

CONVERSION FACTORS

For readers who wish to convert measurements from the inch-pound system 

of units to the metric system of units, the conversion factors are listed below:

Multiply inch-pound unit By To obtain metric unit

foot (ft)

mile (mi)

square foot (ft2)

cubic foot per second (ft3/s)

ton (short)

0.3048

1.609

0.0929

0.02832

0.9072

meter (m)

kilometer (km)

square meter (m2)

cubic meter per second (m3/s)

megagram (Mg)

SEA LEVEL

In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 

(NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order 

level nets of both the United States and Canada, formerly called "Sea Level Datum of 

1929."
AGGRADATION AND DEGRADATION OF ALLUVIAL SAND DEPOSITS, 

1965 TO 1986, COLORADO RIVER, GRAND CANYON NATIONAL PARK,

ARIZONA

By JOHN C. SCHMIDT and JULIA B. GRAF

ABSTRACT

Alluvial sand deposits along the Colorado River in Grand Canyon 

National Park are used as campsites and are substrate for vegetation. 

The largest and most numerous of these deposits are formed in zones of 

recirculating current that are created downstream from where the 

channel is constricted by debris fans at tributary mouths. Alluvial sand 

deposits are classified by location and form. Separation and reattachment deposits are downstream from constrictions within recirculation 

zones. Separation deposits are near the point of flow separation and 

typically mantle large debris fans. Reattachment deposits are near the 

point of flow reattachment and project upstream beneath much of the 

zone of recirculating current. Upper-pool deposits are upstream from a 

constriction and are associated with backwaters. Channel-margin 

deposits line the channel and have the form of terraces. Some are 

created in small recirculation zones.

Reattachment and channel-margin deposits are largest and most 

numerous in wide reaches, although small channel-margin deposits are 

used as campsites in the narrow Muav Gorge. Separation deposits are 

more uniformly distributed throughout Grand Canyon National Park 

than are other types of deposits. In some narrow reaches where the 

number of alluvial sand deposits used as campsites is small, separation 

deposits are a high percentage of the total.

During high flows, both separation and reattachment deposits are 

initially scoured but are subsequently redeposited during flow recession. Sand is also exchanged between the main channel and recirculation 

zones. The rate of recession of high flows can affect the elevation of 

alluvial deposits that are left exposed after a flood has passed. 

Fluctuating flows that follow a period of steady discharge cause initial 

erosion of separation and reattachment deposits. A part of this eroded 

sand is transported to the main channel. Therefore, sand is exchanged 

between the main channel and recirculation zones and redistributed 

within recirculation zones over a broad range of discharges.

Comparison of aerial photographs and reinterpretation of published 

data concerning changes of alluvial sand deposits following recession of 

high flows in 1983 and 1984 indicate that sand was eroded from 

recirculation zones in narrow reaches. In wide reaches, however, 

aggradation in recirculation zones may have occurred. In narrow 

reaches, the decrease of reattachment deposits was greater than that of 

separation deposits. In all reaches, the percentage of separation 

deposits that maintained a constant area was greater than for other 

deposits. Separation deposits, therefore, appear to be the most stable 

of the deposit types.

Fluctuating flows between October 1985 and January 1986, which 

followed the higher and steadier flows of 1983 to 1985, caused erosion 

throughout the park. For separation deposits, erosion was greatest at 

those sites where deposition from the 1983 high flows had been 

greatest. The existing pattern of low campsite availability in narrow 

reaches and high campsite availability in wide reaches was thus 

accentuated by the sequence of flows between 1983 and 1985.

INTRODUCTION

BACKGROUND

Alluvial sand deposits are used as campsites by backpackers and by about 15,000 persons who float the 

Colorado River in boats or rafts through Grand Canyon 

National Park each year. Sand deposits also are substrate for riparian vegetation. Flow in the Colorado 

River through Grand Canyon National Park has been 

regulated by Glen Canyon Dam since its completion in 

1963 (fig. 1). From 1963 to 1982, regulation greatly 

decreased the range of discharges that occurred in any 

given year but greatly increased the range that occurred 

in a given day.

The mean annual peak discharge of the Colorado River 

before flow regulation (1921-62) was 93,400 ft3/s (cubic 

feet per second); this decreased to about 29,200 ft3/s after 

regulation (1963-82). For most of 1965 through 1982, flow 

was regulated in direct response to electrical power 

demand. During a typical 24-hour period, the discharge 

range was large because power demand is high during 

daylight hours and low at night (fig. 2). Although flow 

through the powerplant at the dam could range from 

1,000 to 31,500 ft3/s, discharge rarely varied over this 

entire range in a given day. A daily discharge range of 

10,000 to 20,000 ft3/s was typical of the period. Unusually 

large releases of water that bypass the powerplant using 

river outlet works or both outlet works and spillways 

occurred in 1983,1984, and 1985. In 1983, peak discharge 

at Lees Ferry (station 09380000, Colorado River at Lees 

Ferry, fig. 1) was 97,300 ft3/s. In 1984 and 1985, peak 

discharges at Lees Ferry were 58,200 and 47,900 ft3/s, 

respectively.

Before construction of Glen Canyon Dam, the Colorado 

River carried a large suspended-sediment load through 

Grand Canyon National Park. All the sediment from the 

drainage area above the dam is now trapped in Lake 

Powell formed behind Glen Canyon Dam. Suspendedsediment samples collected at the gaging station at Lees 

Ferry between 1928 and 1959 commonly had concentrations that exceeded 10,000 ppm (parts per million). In
AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

contrast, samples collected since dam construction typically have concentrations less than 200 ppm.

Concern was first raised in the mid-1970's that the 

combination of large daily discharge ranges typical of 

regulated flow and the loss of sediment supplied from 

areas upstream from the dam would cause a decrease in 

the size and number of alluvial sand deposits within the 

park. Laursen and others (1976) estimated both the 

capacity of the regulated river to transport sand and the 

amount of sediment supplied by tributaries below the 

dam. They predicted that sand deposits would eventually 

be depleted because transport capacity exceeded supply 

under regulated flow. Although Dolan and others (1974) 

suggested that widespread degradation of sand deposits 

might result from operations of the dam, Howard and 

Dolan (1981) found that sand deposits had "suffered only 

a very slight erosion." Howard and Dolan (1981) estimated that alluvial sand deposits had reached equilibrium 

by the late 1970's, and they predicted little net change in 

the future. They stated, however, that erosion might 

occur if the characteristic pattern of dam releases of the 

1970's were changed.

On the basis of an inventory made after the high 

releases in 1983, Brian and Thomas (1984) concluded that 

a net loss of sand deposits large enough for use as 

campsites had taken place in the first 173 mi below Lees 

Ferry. They also concluded that a net increase in the 

same type of sand deposits had taken place farther 

downstream. Beus and others (1985) evaluated the history of change of 20 major sand deposits between 1974 

and 1984 by repeating topographic surveys first begun by 

Howard (1975). Beus and others (1985) concluded, "a 

substantial net gain of sand [due to high flows in 1983] 

* * * more than compensated for the previous 8-year loss."

113° UTAH 

ARIZONA

112°

EXP1ANATION

ig station and abb 

Study site listed in table

Gaging station and abbreviated number

FIGURE 1. Study area and location of study sites.
INTRODUCTION

PURPOSE AND SCOPE

The present study of alluvial sand deposits along the 

Colorado River began in 1984 in cooperation with the 

U.S. Bureau of Reclamation as one phase of a comprehensive investigation of the effects of flow regulation on 

sediment transport in Grand Canyon National Park. The 

investigation was initiated in response to a U.S. Bureau 

of Reclamation proposal to increase peak powerplant 

discharges from 31,500 to 33,100 ft3/s. High discharges 

between 1983 and 1985 also provided an opportunity to 

investigate the effects of discharges that exceed powerplant capacity. Other phases of the overall study include:

1. Collection and analysis of flow and sediment-transport data at gaging stations (Graf, 1986; Pemberton 

and Randle, 1986);

2. Analysis of historical data from gaging stations 

(Burkham, 1986);

3. Mapping of channel-bed materials (Wilson, 1986);

4. Development and application of a sediment-transport 

model in the main channel (Orvis and Randle, 1986; 

Randle and Pemberton, 1987); and

5. Evaluation of sediment contributions from ungaged 

tributaries by debris flows (Webb and others, 1987).

The results of this study will be integrated with results 

of other phases to determine the effect of flow regulation 

on sediment transport and storage in the Colorado River 

in Grand Canyon National Park.

The study involved the evaluation of existing data and 

the collection of new data. Existing data consist mainly of 

aerial and ground photography (Laursen and Silverston, 

1976; National Park Service, unpublished 1975 photographs on file at Grand Canyon National Park; Turner 

and Karpiscak, 1980) and topographic surveys of deposits 

begun in 1974 (Howard, 1975; Beus and others, 1985;

25,000

January 8 Januarys January 10 January 11

1986

FIGURE 2. Instantaneous discharge at Lees Ferry gage, January 

8-11, 1986, typical of fluctuating flows between 1965 and 1982.

Ferrari, 1987). Data for this study were collected from 

May 1984 to February 1986. These data included measurements of flow velocity, scour-and-fill of sand deposits, 

topographic and bathymetric surveys, mapping surfaceflow patterns, water-surface slope surveys, sedimentological analysis of some sand deposits, and replication of 

photographs.

The study area extends from the gaging station (Colorado River at Lees Ferry) at river mile 0 to the gaging 

station (station 09404200, Colorado River above Diamond 

Creek, at Peach Springs) at river mile 225 (fig. 1). Most 

of the fieldwork was done on raft trips beginning at Lees 

Ferry and ending at either Diamond Creek (river mile 

225) or on Lake Mead (river mile 280). A helicopter was 

used to reach some sites on December 7 and 8, 1985, and 

on January 8 and 13, 1986.

Forty-one study sites were selected as a representative sample of different types of alluvial sand deposits 

used as campsites in most major reaches of the Colorado 

River corridor. The 41 sites and the types of data 

collected at them are summarized in table 1. The results 

of topographic and bathymetric surveys at 21 of these 

sites, referred to as detailed study sites, are discussed in 

this report.

Bathymetric surveys were limited to reaches where a 

raft could be safely maneuvered and instruments could 

receive signals. In spite of the limitations, bathymetric 

surveys permitted mapping of large areas not otherwise 

accessible. Topographic surveying was limited to areas of 

safe wading; however, at low stages, large areas at some 

study sites could be mapped. Surface-current patterns 

and shorelines were mapped at two or more discharges. 

Surface velocities were estimated by timing floating 

objects and by using current meters. Bathymetric surveys were made at discharges between about 15,000 and 

25,000 ft3/s (table 1). Other observations and surveys 

were made at discharges between about 3,000 and 45,000 

ft3/s.

The purpose of this report is' (1) to present a classification of alluvial sand deposits in the Colorado River, (2) 

to describe significant characteristics of these deposits, 

(3) to describe changes in these deposits between June 

1983 and January 1986, and (4) to relate these changes to 

those occurring since completion of the dam. The classification of alluvial sand deposits and identification of 11 

reaches within Grand Canyon National Park are presented to provide a framework within which to evaluate 

changes in deposits. Description of the characteristics of 

alluvial sand deposits is included to substantiate the 

classification and to provide a basis for understanding 

change in spatial distribution of sand. Changes in alluvial 

deposits were identified by topographic and bathymetric 

surveys between April 1985 and January 1986 and by 

analysis of aerial photographs.
AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

ACKNOWLEDGMENTS

The fieldwork accomplished in this project was the 

direct result of the work of many individuals. Volunteers 

with the U.S. National Park Service or the U.S. Geological Survey included Bernard 0. Bauer, James Harris, 

Robert Jacobsen, Catherine Hooper, Barbara Rusmore, 

and John Rusmore. Thanks go to them all as well as to the 

other field assistants. Dave Steinke made modifications 

to the equipment used for bathymetric surveys that made 

those surveys possible. Martha Hahn of the National 

Park Service arranged for the appointment of volunteers 

for the National Park Service and obtained unpublished 

data for our use. Boatmen for the raft trips were Jon 

Stoner, Stuart Reeder, Bob Grusy, and Owen Baynham; 

their skilled navigation and professionalism made all our 

work possible.

TERMINOLOGY

Flow separation and associated secondary circulations 

are characteristic hydraulic conditions in the Grand 

Canyon that determine sand-deposit location and extent 

of change. The phenomenon of flow separation at abrupt 

channel expansions or contractions is described in basic 

fluid mechanics texts. When flow separation occurs, the 

main downstream current becomes separated from the 

channel banks, and areas of recirculating flow exist 

between the downstream current and the banks (fig. 3). 

These recirculation zones are composed of one or more 

eddies, a term denoting "any rotating fluid motion which 

possesses continuity so long as the flow pattern which 

creates it continues to prevail" (Matthes, 1947). Eddies, 

as discussed in this report, have a vertical or nearly 

vertical axis of rotation. Typically, a recirculation zone 

has a primary eddy and may have a secondary eddy. 

That portion of the primary eddy where flow is directed 

upstream and toward the main downstream current is 

referred to as the primary-eddy return current. The bed 

of the recirculation zone excavated by this current is 

termed the primary-eddy return-current channel. 

Other portions of recirculation zones are not organized 

into a rotation. Currents in these low-velocity areas may 

have a preferential direction, may oscillate in several 

directions, or may be virtually stagnant.

The point at which downstream-directed flow becomes 

detached from the channel banks is called the separation 

point (fig. 3A). The point at which downstream-directed 

flow is again adjacent to the banks is called the reattachment point. The separation point is the most upstream 

point and the reattachment point the most downstream 

point of the recirculation zone. On the Colorado River, 

these points are actually zones, 5-20 ft wide, within 

which the separation or reattachment point may migrate.

A plane and its surface expression, the separation 

surface, divides the main downstream-directed flow 

from the recirculation zone.

Two types of alluvial sand deposits within recirculation 

zones are highest in elevation and are of most interest to 

whitewater boaters and campers. Separation deposits 

mantle the downstream part of debris fans and are 

located near the separation point. Reattachment deposits are located at the downstream end of recirculation 

zones, project upstream into the center of the zones, and 

are near the reattachment point (fig. 35). At places, the 

surface of separation and reattachment deposits merge 

and the deposits cannot be distinguished solely on the 

basis of location, although they each have distinctive 

sedimentary characteristics. At other places, one or the 

other may not be found in a particular recirculation zone.

Alluvial sand deposits are also typically located upstream from constrictions. At least the lower part of 

many of these upper-pool deposits is a reattachment 

deposit associated with small recirculation zones. The 

higher parts of these same deposits, however, resemble 

terraces. Where the origin of alluvial deposits could not 

be determined on the basis of planimetric shape or 

location, they are called channel-margin deposits. 

Point-bar deposits, which are characteristic of alluvial 

meandering rivers, are uncommon in the park and are not 

discussed.

Abrupt changes in flow area cause flow separation. In 

the Grand Canyon, the channel is typically more narrow 

and shallow around obstructing debris fans, and this 

short reach is called the constriction. Downstream from 

the debris fan, a short reach is wider than the average 

channel width and is called the expansion. Downstream 

from the expansion, the channel typically resumes the 

dimensions characteristic of the reach upstream from the 

constriction. The separation point typically is located 

near the transition from constriction to expansion. Recirculation zones occur in the expansion.

The ratio of channel width at the constriction to 

average width of the upstream channel is termed the 

constriction ratio. The ratio of channel width at the 

expansion to channel width at the constriction is termed 

the expansion ratio. The term elevation used in this 

report refers to the distance above or below either an 

arbitrary local datum or sea level.

METHODS OF ANALYSIS

Between April 1985 and February 1986, sand-deposit 

change was measured by repeated topographic and 

bathymetric surveys. These surveys, as well as photographs taken between April and February, were compared with similar types of data collected between 1965
METHODS OF ANALYSIS

Reattachment point

CONSTRICTION EXPANSION

Primary-eddy 

return-current 

channel

Reattachment deposit

Channel-margin 

deposit

FIGURE 3.-Flow patterns and configuration of bed deposits in a typical recirculation zone. A, Flow patterns. B, Configuration of bed deposits.
6 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

and 1984 in order to measure change over longer time 

periods. Reference marks established by Howard (1975), 

Laursen and Silverston (1976), or Ferrari (1987) were 

used. At new study sites, networks of reference marks 

were established.

A theodolite distance meter and standard techniques 

were used for most topographic surveys. About 25 

percent of the topographic surveys were made using a 

hand level and tape. Surveys were made along profile 

lines, and topographic maps of most sites were made.

Resurveys of reference-mark networks generally differed by less than 0.10 ft from survey to survey. 

Surveying data were initially plotted in plan view to 

ensure that repeated surveys matched. Where they did 

not match, surveying data were adjusted for differences 

in position on the basis of surveying data of surrounding 

topography. This technique resulted in accurate depiction of topographic change along specific profile lines. 

Differences in elevation exceeding 0.25 ft are considered 

to be significant in this study.

Bathymetric surveys were made from a raft about 35 ft 

long by using a recording echo-depth sounder and a local 

microwave positioning system. The positioning system 

consisted of two remote units mounted on tripods on 

shore, a master unit mounted on a mast on the raft, and 

the electronics that control their operation. The distance 

between the master and each remote is determined by 

the traveltime of microwaves. The position of the remotes in the local coordinate system was determined by 

their location in relation to fixed reference marks, and the 

position of the raft at any time was computed from the 

known distances between the master unit and each 

remote. Data from the positioning system and the depth 

sounder were recorded along with time on a data logger 

as the raft moved about the study area. The time interval 

for recording could be changed but generally was 2 

seconds. Depths were converted to elevation by reference to elevation of the water surface during the survey. 

Maps of the data were plotted and contours were drawn 

by use of a computer-contouring system.

Precision of the recording echo-depth sounder used is 

0.1 ft, and accuracy is 0.5 percent of the measured depth 

or about 0.25 ft at a depth of 50 ft. Although maximum 

depth was 70 to 80 ft at a few study sites, maximum depth 

was less than 50 ft at most sites. Water-surface elevation 

during each survey was monitored either by a temporary 

recording-stage gage or by periodic reading of a staff 

gage on shore. Water-surface elevation changed with 

time during surveys and at a given time was different in 

different parts of the surveyed area. Change with time 

was caused primarily by discharge fluctuations or surface 

waves. During the bathymetric survey, the edge of water 

was mapped using standard surveying techniques. Depth 

changes in excess of 0.5 ft are considered significant.

Spurious depths were recorded when air entrained in 

the water column caused the signal to reflect within the 

water column rather than off the channel bottom. Spurious numbers in the data set, which were identified by 

comparing the stored numbers with depths recorded 

graphically, generally showed shallower depths than 

preceding or following measurements. In some places, 

entrained air severely limited the area that could be 

surveyed, especially downstream from rapids.

Uncertainty of the distance measurement by each 

microwave unit is about 3 ft. Uncertainty of the raft 

position computed from the two distances depends 

mainly on the uncertainty of the distance measurement 

and on the relative positions of the master and remote 

units. Highest position accuracy (about 4.3 ft) is obtained 

when the master and remotes form a 90° angle. The 

accuracy decreases as the angle increases or decreases 

from 90° and is about 11.7 ft at angles of 30° and 150°. 

Remotes were located near the center of the recirculation 

zone or channel in such a way as to maintain a line of sight 

and to give as close to a 90° angle as possible over the 

survey area. The uncertainty of position ranges from the 

minimum of about 4.3 ft to about 20 ft.

Data points from the positioning system were used to 

generate a grid of equally spaced values that were in turn 

used in graphical fitting of contours for computer plotting. Error of the grid was determined by computing the 

elevation at data locations by linear interpolation from 

the values at the grid nodes and comparing the calculated 

value with the measured value. The method of grid 

generation was selected to minimize interpolation error 

while maintaining a reasonable amount of smoothing of 

the data. Uncertainty in the position of contours also 

depended on the spatial distribution of data points. 

Where data points were sparse, contour position was 

extremely uncertain even though the interpolation error 

was low.

The resulting uncertainty in the bathymetric maps is 

the sum of errors in microwave system location, computer contouring, and data-point density. The most 

significant of these is the uncertainty in raft position 

caused by poor geometry of the master and remote units 

and sparse distribution of data points. Although no 

quantitative measure of the map uncertainty was developed, a qualitative judgment was made for each map, and 

areas judged to have uncertainty too great for meaningful analysis were omitted.

Analysis of sand-deposit change at 13 detailed-study 

sites since 1965 relied mainly on photographic comparisons. Aerial photography is available for 1965 (U.S. 

Geological Survey, scale about 1:15,000), 1973 (U.S. 

Geological Survey, scale about 1:7,200), and 1984 (U.S. 

Bureau of Reclamation, scale about 1:3,000). Daily mean 

discharge ranged from 23,100 to 41,200 ft3/s during the
BACKGROUND

photographic survey of 1965, from 5,930 to 12,100 ft3/s 

during the survey of 1973, and from 5,220 to 5,810 ft3/s 

during the survey of 1984. Topographic changes at study 

sites were determined by measuring the area of exposed 

sand above the stage corresponding to a discharge of 

about 25,000 ft3/s. The area of exposed sand was directly 

measured in the photographs of 1965 for study sites 

where discharge was about 25,000 ft3/s. Estimates of the 

shoreline corresponding to a discharge of about 25,000 

ft3/s, however, had to be made for the 1973 photography. 

The upper limit of unvegetated sand on the photographs 

of 1973 was determined to be associated with a stage of 

approximately 25,000 ft3/s by comparing topographic 

surveys and stage-discharge relations at Eighteen Mile 

Wash and opposite Nineteen Mile Canyon. Below this 

stage, sand was swept clean by daily fluctuations. The 

location of the shoreline at discharges of approximately 

25,000 ft3/s was mapped in the field in August 1985 and 

drawn on 1984 photographs. A zoom transfer scope was 

used to adjust for differing scales of each aerial photograph survey. A planimeter was used to measure areas 

for different years, and differences in area of more than 

10 percent were considered significant.

Measurements of exposed sand deposits at a discharge 

of about 6,000 ft3/s were also made for 1973 and 1984 at 

about 180 sites. Measurements were made directly on 

aerial photographs. Accuracy of comparisons of exposed 

sand area is limited by the different scales of different 

aerial photographs as well as by the changing scale of 

each particular year's flight. For example, the ratio of 

scale difference between a unit area on the 1973 and 1984 

photographs varied between 5.0 and 7.7, depending on 

location. In order to compensate for the errors resulting 

from varying scale, scale ratios were measured at about 

1-mile intervals. Areas of deposits in 1973 were estimated by multiplying the area measured on the aerial 

photographs by the scale ratio so that comparison could 

be made with areas measured on the 1984 photographs. 

Areas in 1973 were estimated to be within a range 

determined by the highest and lowest scale ratios within 

about 10 mi of the measured site. Areas on 1984 aerial 

photographs were considered to be accurate to ±10 

percent. Significant change was considered to have 

occurred if the estimated 1973 area was entirely beyond 

the range of the 1984 area estimate.

An inventory of the presence or absence of different 

types of alluvial sand deposits in 399 recirculation zones 

was also conducted between river miles 0 and 118 using 

1973 and 1984 photography. Criteria used in this inventory are described in the section entitled "Changes in 

alluvial sand deposits, 1973-^84."

Other methods used to interpret or document topographic changes or hydraulic conditions included scour 

chains, sedimentologic descriptions, water-surface slope

surveys, and mapping of surface currents. Chains 2 ft 

long and having links of about 0.1 ft were inserted 

vertically into sand deposits along lines that were 

roughly perpendicular to shore. A metal detector was 

used to recover the chains; recovery was about 90 

percent. Trenches were dug into sand deposits to reveal 

sedimentary structures. The size of trenches was limited 

by the time and equipment available. The largest trench 

was 80 ft long and 4 ft deep at Fern Glen Rapid.

Surveys of water-surface slope were obtained by 

measuring the water-surface elevation at the edge of 

water. A staff gage was installed before each measurement, and observed fluctuations in stage were recorded. 

All surveyed points were located on aerial photographs 

along with the survey time. The water-surface survey 

was adjusted to compensate for measured stage changes. 

In order to decrease the length of time of the survey and 

therefore the stage changes during the survey, two rod 

persons usually were used.

The direction of surface currents and location of 

shorelines were observed from the shore and mapped on 

aerial photographs. Uncertainty in position of features 

near the center of the channel is estimated to be about 5 

percent of local river width. Noted features such as the 

location of separation and reattachment points along the 

shoreline are accurate to within 10 ft.

BACKGROUND

PHYSICAL AND HYDRAULIC CHARACTERISTICS OF THE 

CHANNEL

The Colorado River channel is in bedrock or bordered 

by large talus blocks for most of the 225 mi from Lees 

Ferry to Diamond Creek. Geomorphic characteristics of 

the river channel are controlled by bedrock type and 

structure (Dolan and others, 1978). Channel width and 

depth, presence of midchannel gravel bars, and the 

distribution of tributary debris fans are all related to the 

bedrock geology (Howard and Dolan, 1981).

Eleven reaches of the Colorado River were defined on 

the basis of type of bedrock exposed at river level, 

average channel top width, average channel widthto-depth ratio, reach slope, and relation to major tributaries (table 2; fig. 4). The narrow reaches are Upper 

Granite Gorge, Aisles, Middle Granite Gorge, Muav 

Gorge, Supai Gorge, Redwall Gorge, and Lower Granite 

Gorge. The wide reaches are the Permian Section, Lower 

Marble Canyon, Furnace Flats, and Lower Canyon.

The elevation of the river decreases about 1,780 ft 

between Lees Ferry and Diamond Creek. The descent 

takes place primarily in short steep reaches, many of 

which are the famous rapids of the Grand Canyon. In the 

first 150 mi downstream from Lees Ferry, 50 percent of
AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

the total decrease in elevation takes place in only about 9 

percent of the distance (Leopold, 1969). Although the 

average gradient between Lees Ferry and Diamond 

Creek is 0.0015, the gradient of many short reaches 

exceeds 0.01.

Water-surface slope is low in reaches between rapids, 

and many reaches have a gradient of less than 0.0005

(Birdseye, 1923). Water-surface slope flattens in pools 

upstream from most major rapids, and mean velocity 

commonly is less than 3 ft/s. A deep scour hole is present 

immediately below most rapids (Leopold, 1969; Howard 

and Dolan, 1981; Wilson, 1986).

Rapids are commonly located where the channel has 

been constricted by alluvial fans formed by debris-flow

EXPLANATION

) Permian Section

(2) Supai Gorge

(3) Redwall Gorge

(*) Lower Marble Canyon

(5) Furnace Flats

T) Aisles

Middle Granite Gorge 

9) Muav Gorge

Lower Canyon 

vj) Lower Granite Gorge

Upper Granite Gorge ^380o Gaging station and abbreviated number 

FIGURE 4. Reaches within the study area.
BACKGROUND 9

deposits at the mouths of short, steep tributaries (fig. 3). 

Debris from these flows also increases local bed elevation 

of the channel. Kieffer (1985) determined constriction 

ratios at 54 debris fans in the Grand Canyon, using 1973 

aerial photography. She found that the ratio ranged from 

about 0.3 to about 0.7, and averaged about 0.5. Because 

discharge in the 1973 photographs ranged from about 

4,000 to 15,000 ft3/s and constriction ratio might vary 

with discharge and stage, constriction ratios were recomputed from 1984 photography. The mean constriction 

ratio at the same debris fans measured by Kieffer (1985) 

was 0.49, indicating that while individual sites might 

vary in relation to stage and method of measurement, 

when averaged over a number of sites, the effect of stage 

on constriction ratios is not significant. Because alluvial 

deposits large enough to be used as campsites are 

associated with small debris fans as well as the large fans 

measured by Kieffer (1985), constriction ratios were 

computed from 1984 photographs for 70 debris fans 

associated with alluvial deposits inventoried as campsites 

(Brian and Thomas, 1984) between river miles 0 and 61. 

The mean constriction ratio of these sites was 0.54, 

somewhat greater than that of the sample population of 

Kieffer (1985). The expansion ratio at the 70 sites ranged 

from 1.3 to 7.3, with a mean of 2.9. At 59 of these sites 

where channel-depth data (Wilson, 1986) are available, 

channel depth at the constriction decreased to as much as 

0.30 of the upstream depth and increased in the expansion to as much as nine times the constriction depth.

At most constrictions, recirculation zones exist at 

discharges between 4,000 and 45,000 ft3/s, but their sizes 

are not constant. At most sites, recirculation zones 

increase in length with increasing discharge at least to 

45,000 ft3/s (Schmidt, 1986). At Badger Creek Rapid, the 

separation point is farther upstream and the reattachment point farther downstream at a discharge of 44,000 

ft3/s than at a discharge of 5,600 ft3/s (fig. 5). At 

extremely low flow, many recirculation zones are greatly 

reduced in size, and the bed of the recirculation zone may 

be completely exposed. For example, at Soap Creek 

Rapid, flow separation does not occur at discharges less 

than about 5,000 ft3/s.

At each constriction, the debris fan is overtopped if the 

discharge is sufficiently high. As discharge increases 

above this overtopping discharge, the separation point 

does not migrate farther upstream. For example, overtopping occurs at the low fan at Eighteen Mile Wash 

between 28,000 and 44,000 ft3/s (fig. 6). At most sites, the 

downstream migration of the reattachment point is 

controlled by the geometry of the channel. Lengthening 

of the recirculation zone in the downstream direction is 

ultimately restricted where the downstream-migrating 

reattachment point encounters another riffle or debris 

fan farther downstream. An upper limit, therefore,

exists on the length of recirculation zones, but the limit is 

different at different sites.

Sand is stored primarily in main-channel pools and 

within recirculation zones (Wilson, 1986). Most sand 

deposits used as campsites are associated with recirculation zones and are formed at discharges typically 

exceeding 30,000 ft3/s. Sand stored within recirculation 

zones typically is very well sorted and fine to very fine 

grained (fig. 7, curve 7, 8), whereas sand in channel pools 

is typically medium grained (fig. 7, curve 5, 6),

Channel geometry and hydraulic data based on field 

mapping of shorelines and currents at various discharges, 

water-surface slope surveys, and depth-sounder records 

were collected at 21 detailed study sites (table 3). The 

mean constriction ratio of these sites is 0.49 and is the 

same as the mean constriction ratio of the debris fans 

measured by Kieffer (1985) and less than the mean of 70 

fans between river miles 0 and 61 discussed above. The 21 

sites, therefore, are representative of more narrow 

constrictions than are associated with most campsites in 

the Grand Canyon.

Study sites were concentrated in upstream reaches 

where the effects of dam operations were initially considered to be most significant. Detailed study sites were 

located in seven reaches (table 4). Study sites in each of 

these reaches included the dominant types of deposits 

used for camping (table 2).

HISTORY OF FLOW AND SEDIMENT TRANSPORT

Two gaging stations provide long-term information on 

flow and sediment transport. The gage at Lees Ferry 

(fig. 1) was established in 1895, and in 1922, a gage 

(station 09402500, Colorado River near Grand Canyon) 

was established at river mile 87, just above Bright Angel 

Creek (fig. 1). Suspended-sediment samples were collected at the gage at Lees Ferry during the periods 

1929-33, 1942-44, and 1947-65 and near Grand Canyon 

from 1925 to 1972. Sediment data also were collected at 

these two gages from June to December 1983 and from 

October 1985 through January 1986. Three additional 

gages were operated during the latter two periods. These 

short-term gages were at river mile 61, just above the 

confluence with the Little Colorado River (station 

09383100, Colorado River above the Little Colorado 

River, near Desert View); at river mile 166, just above 

National Rapid (station 09404120, Colorado River above 

National Canyon, near Supai); and at river mile 225, just 

above Diamond Creek Rapid (fig. 1).

Before closure of Glen Canyon Dam in March 1963, 

discharge at Lees Ferry typically reached its annual peak 

in June in response to snowmelt runoff from the upper 

basin. Smaller peaks occurred during the late summer 

and fall in response to rain in tributary watersheds
10 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

downstream from Lees Ferry (fig. 8). Suspended-sediment concentrations tended to be highest during these 

periods of tributary flow, and suspended sediment was 

dominated by silt- and clay-sized material (fig. 7, curve 2).

Daily mean discharge of water for 1982 (fig. 9) was 

typical of the period 1965-82. During that period, shortterm discharge fluctuations dominated, and discharge 

exceeded powerplant capacity of 31,500 ft3/s only in

Badger Creek

Base from uncorrected aerial 

photography taken October 21, 1984

500

I I i

1000 FEET

150 300 METERS

Jackass Creek 

EXPLANATION

RIVER-DEPOSITED OR REWORKED 

VERY FINE TO MEDIUM SAND 

(October 21, 1984)

EOLIAN SAND OR TERRACE DEPOSITS Silt and fine sand, well sorted

TRIBUTARY DEBRIS FAN Boulders, 

cobbles, gravel, sand, poorly sorted; 

boulders cover more than 50 percent 

of surface area except in tributary 

streambed

COBBLES AND GRAVEL 

TALUS AND BEDROCK

ADDITIONAL RIVER-DEPOSITED 

SAND (1973)

EDGE OF WATER

Low flow, October 5, 1985, 5,600 

cubic feet per second

High flow, May 20,1985,44,000 cubic 

feet per second

SEPARATION SURFACE 

Low flow 

High flow

GENERALIZED SURFACE-FLOW DIRECTION IN RECIRCULATION 

ZONES

Low flow 

High flow 

Surface-flow direction of main current

LIMIT OF BREAKING WAVES (WHITE 

WATER) AT LOW FLOW At high 

flow, breaking waves in main current 

extend downstream to a point opposite center of recirculation zones

DENSE STANDS OF TAMARISK 

SEPARATION POINT 

REATTACHMENT POINT

) LOCATION OF PROFILE LINES (Number refers to table 13)

< PHOTOGRAPH SITE Figure 10

SP 

RP

FIGURE 5. Surficial geology and hydraulic features at Badger Creek Rapid.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 11

April, May, and June 1965 and for a very short period in 

late June and early July 1980. Maximum instantaneous 

discharge at Lees Ferry was 60,200 ft3/s in 1965 and 

44,800 ft3/s in 1980. Annual suspended-sediment load 

past Lees Ferry decreased from 76.3xl06 tons/yr in the 

period just before construction of the dam (1948 to 1958) 

to 8.6xl06 tons/yr just after dam completion (1963 to 

1965) (Laursen and others, 1976), which is a decrease of 

almost 90 percent. For the same periods, volume of water 

passing Lees Ferry decreased about 55 percent (Anderson and White, 1979).

The present study was planned and initiated in 1982 

and early 1983, when flows such as those illustrated in 

figure 2 had prevailed for nearly 20 years. An exceptional 

combination of weather conditions and management 

decisions during the winter of 1982-83, however, caused 

subsequent flows to deviate from the previous regime 

(fig. 9). A record post-dam high instantaneous discharge 

of 97,300 ft3/s passed Lees Ferry on June 29,1983. From 

June 1983 until October 1, 1985, discharges were higher 

and steadier than ever experienced since closure of the 

dam. Discharges of as much as 46,000 ft3/s can be 

released without using the spillways; 31,500 ft3/s can be 

released through the powerplant and 14,500 ft3/s through 

river outlet works (David Wegner, U.S. Bureau of 

Reclamation, oral commun., 1986). The flat-topped hydrographs of the summers of 1984 and 1985 (fig. 9)

2000

1800

1600

fc

uf 1400

Z 

I 

<5 1200

1000

800

o

g 600

400

200

addle CanV??

Blacktail Rapid 

Eighteen Mile Wash

0 10 20 30 40 50 

DISCHARGE , IN THOUSANDS OF CUBIC FEET PER SECOND

FIGURE 6. Change in length of recirculation zone with discharge at six

sites.

resulted from maximum releases through the river outlet 

works and powerplant. Discharges in June 1983 exceeded 

powerplant and outlet work capacity, and spillways were 

used. Only during a special fluctuating-flow study period October 1, 1985, to January 15, 1986 did releases 

resemble those characteristic of the 1965-82 period. The 

special fluctuating-flow study was planned and carried 

out for the purpose of providing a period in which to 

investigate the response of the river to typical powerplant releases.

CHARACTERISTICS AND CLASSIFICATION OF 

ALLUVIAL SAND DEPOSITS

Fine-grained sediments are stored in channel pools, in 

recirculation zones, and in deposits that continuously line 

the wider sections of the river. Except for the widest 

reaches, most alluvial deposits are associated with the 

recirculation zones caused by minor bedrock or talus 

abutments or by large debris fans. In parts of the widest 

reaches of the Grand Canyon, terracelike deposits exist. 

Deposits associated with large recirculation zones are the 

most numerous and extensive alluvial sand deposits in 

Grand Canyon National Park.

Side-scan sonar surveys, recording depth-sounder surveys (Wilson, 1986), and photography taken at low river 

stage demonstrate that the average bed elevation of 

recirculation zones is much higher than that of the 

adjacent channel. A pool or scour hole occurs immediately downstream from the constriction. Adjacent to and 

downstream from this scour hole, the channel rises to the 

higher surface of a sandy alluvial deposit (fig. 3B). The 

upper surface of the sandy deposit typically has relief of 

10 to 50 ft. The difference between the average bed 

elevation within a recirculation zone and the elevation of 

the adjacent thalweg varies from site to site. For 

example, at Blacktail Rapid, the elevation difference 

exceeds 80 ft, and at National Rapid and Eminence Break 

Camp, the elevation difference exceeds 40 ft.

The separation and reattachment deposits associated 

with recirculation zones are composed primarily of medium to very fine sand. Between Lees Ferry and Bright 

Angel Creek, 22 deposits created since 1983 were sampled (table 5). Of the 55 samples taken at these deposits, 

only 4 contained less than 90 percent sand, and none of 

these samples contained more than 1 percent very coarse 

sand (greater than 1 mm).

All samples of deposits between Lees Ferry and Bright 

Angel Creek that were inundated in 1983 or more 

recently have graphic means (Folk, 1968) between 0.095 

and 0.39 mm. Of the 33 samples of deposits created by the 

discharges of 1983, 25 are fine sand and most are 

moderately well sorted. Fewer samples were collected of 

sediments deposited in 1984 and 1985, and half of these 

samples are medium sand between 0.25 and 0.50 mm.
12 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

WENTWORTH SIZE CLASS

Silt

99.9

99.8

99.5

99.0

98.0

95.0

N 90.0

CO

Q

O

Q

Z

Very 

fine 

sand

Fine 

sand

Medium 

sand

Coarse 

sand

Very

coarse

sand

Granule Pebble

50.0

cc

LU

Z

LU

O

ccffi 10.0

5.0

1.0 -

01

\ ,'\ I

I I I \ 111 I I I

0.01 0.1 1.0

PARTICLE DIAMETER, IN MILLIMETERS 

EXPLANATION

10.0

Curve

1

2

3

4

5

6

7

Date

June 13, 1957

October 18, 1957

October 22, 1983

October 2, 1983

October 27, 1983

December 18, 1985

August 13, 1985

Description

Pre-dam, snowmelt runoff

Pre-dam, tributary flow

Post-dam, no tributary flow

Post-dam, tributary flow

Bed material

Bedload

1983, reattachment deposit,

Discharge, 

in cubic feet 

per second

123,000

15,600

23,800

31,400

Concentration, 

in milligrams 

per liter

7,980

17,000

409

16,600

8 August 3, 1985

Saddle Canyon

1985, separation deposit, 

Eighteen Mile Wash

FIGURE 7. Typical particle-size distributions for samples of suspended sediment, bedload, and bed material from the Colorado River near Grand

Canyon at river mile 87 and for two alluvial sand deposits.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 13

140

O 120 

o

LLJ

o

CD

o 

o

D 

O

I

100

80

60

40

LU

o 

cc

<

o 20

C/3 

O

JAN FEB MAR APR MAY JUNE JULY 

1957

AUG SEPT OCT NOV DEC

FIGURE 8. Daily mean discharge of the Colorado River at Lees Ferry, 1957.

Q 100

JFMAMJJASONDJFMAMJJ ASOND

1982 1983

J FMAMJJ ASDNDlj FMAMJ JASON D|jF

1984 1985 1986

FIGURE 9. Daily mean discharge of the Colorado River at Lees Ferry, 1982 to February 1986.
14 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

SEPARATION DEPOSITS

Separation deposits mantle and typically extend downstream from a debris fan. A zone of interspersed sand and 

boulders separates the separation deposit from the debris-flow deposits located upstream (fig. 10). The separation deposit generally forms one continuous gradual 

slope from crest to water's edge, but discrete terracelike 

levels may exist.

The most upstream part of most of these deposits 

commonly does not border the low-flow river channel; 

boulders are found between the sand deposit and the 

water's edge (fig. 5). Downstream migration of separation points with decreasing discharge probably causes 

erosion of sand in the upstream low-elevation portion of 

the separation deposit, resulting in this depositional 

pattern.

Separation deposits form in low-velocity areas and in 

secondary eddies upstream from the primary-eddy return-current channel. At some sites, a bar forms in a 

secondary eddy and the upstream-facing slipface of this 

deposit migrates upstream and eventually becomes attached to the debris fan. This process was observed at 

Eighteen Mile Wash, where a separation deposit (fig. 11) 

formed in a secondary eddy at a discharge of 45,000 fts/s. 

At this discharge, the downstream part of the Eighteen 

Mile Wash debris fan was inundated. Velocity of this 

secondary eddy was much less than that of the main 

channel. Surface velocity through the riffle, at a discharge of 45,000 ft3/s on May 22, 1985, was measured to 

be about 16 ft/s on the basis of timing drifting boats. Mean 

velocities over the deposit in the low-velocity area at the 

same time did not exceed 1.5 ft/s (fig. \2E). Discharge 

over the deposit was about 160 ft8/s, which was only 0.4 

percent of the main-channel discharge. The measured 

mean velocities at Eighteen Mile Wash are characteristics of velocities in low-velocity areas measured elsewhere.

Sand transport in the low-velocity area at 45,000 ft3/s 

was upstream, away from the primary-eddy return 

current. Comparison of topographic surveys shows that 

approximately 13,000 ft8 of very fine and fine sand was 

deposited between May 22 and the recession of high flows 

33 days later. Aggradation occurred by upstream migraFIGURE 10. Separation deposits downstream from Badger Creek Rapid, July 30, 1985. Separation deposits mantle Badger Creek 

debris fan in foreground and Jackass Creek debris fan on opposite bank. Photograph site shown on figure 5.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 15

tion of the slipface (fig. 13) and by deposition on the 

downstream-facing slope. Sedimentary structures within 

the deposit consisted mainly of climbing ripples in the 

downstream part and planar foreset beds of the advancing slipface in the upstream part. If the measured volume 

change resulted from continuous deposition over the 33 

days when the deposit was submerged, then the rate of 

deposition was about 390 ft3/d or about 0.03 vertical ft/d. 

It is possible, however, that deposition occurred more 

rapidly in only a small percentage of the total inundation 

period. The low discharge across the deposit and the fact 

that climbing ripples do not have supercritical angles of 

climb, however, suggest that the deposition was at a slow 

rate. Supercritically climbing ripples, in which all parts of

the ripple surface are preserved, are associated with high 

sedimentation rates (Hunter, 1977).

Comparison of currents at Eminence Break Camp (fig. 

14) and bathymetric maps (fig. 15) and bed-surface 

profiles (fig. 16) for the high-elevation part of profile 2 

between April and September 1985 also shows aggradation in areas upstream from the primary-eddy returncurrent channel. The area was inundated by a secondary 

eddy and low-velocity area during the bathymetric surveys made at 26,000 and 27,200 ft3/s and during the high 

flows of May and June 1985.

Separation deposits typically have a spit near the 

junction between the shoreline that faces the main 

current and the shoreline that faces the recirculation

EXPLANATION

RIVER-DEPOSITED OR REWORKED VERY 

FINE TO MEDIUM SAND (October 21, 

1984)

TRIBUTARY DEBRIS FAN Boulders, 

cobbles, gravel, sand, poorly sorted; 

boulders cover more than 50 percent of 

surface area except in tributary streambed

//// TALUS AND BEDROCK

(a) LOCATION OF SEPARATION POINT, 

45,000 CUBIC FEET PER SECOND, 

MAY 22, 1985

© LOCATION OF SEPARATION POINT, 

28,000 CUBIC FEET PER SECOND, 

AUGUST 2, 1985

© LOCATION OF SEPARATION POINT, 

4,200 CUBIC FEET PER SECOND, 

OCTOBER 9, 1985

(d) LOCATION OF REATTACHMENT POINT, 

28,000 CUBIC FEET PER SECOND, 

AUGUST 2, 1985

LOCATION OF REATTACHMENT POINT, 

4,200 CUBIC FEET PER SECOND, 

OCTOBER 9, 1985

PATH OF MOVEMENT OF SEPARATION 

OR REATTACHMENT POINTS

GENERALIZED SURFACE-FLOW DIRECTION IN RECIRCULATION ZONES, 

4,200 CUBIC FEET PER SECOND

SURFACE-FLOW DIRECTION OF MAIN 

CURRENT, 4,200 CUBIC FEET PER 

SECOND

 APPROXIMATE LOCATION OF SEPARATION SURFACES, 4,200 CUBIC FEET 

PER SECOND

Profilel LOCATION OF PROFILE; SEE TABLE 13 

Profiles 1 and 2 shown in figure 12

FIGURE 11. Surficial geology and hydraulic features near Eighteen Mile Wash.
16 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

A

Bedrock

3 20

1

3

40

1

1 

10

60 80 FEET

I I

I 

20 METERS

EXPLANATION

95-

1.1

RIVER-DEPOSITED OR REWORKED VERY 

FINE TO MEDIUM SAND

TOPOGRAPHIC CONTOUR Elevations 

related to arbitrary datum. Interval 1 foot

DIRECTION AND MAGNITUDE (IN FEET 

PER SECOND) OF MEAN VELOCITY

GENERALIZED SURFACE-FLOW DIRECTION IN RECIRCULATION ZONES A A1

SURFACE-FLOW DIRECTION OF MAIN 

CURRENT

SLIPPAGE OF RIPPLE 

SEPARATION SURFACE

REFERENCE POINT FOR ARBITRARY 

DATUM Elevation, 100 feet

LINE OF SECTION SHOWN IN FIGURE 13

FIGURE 12. Topography of a separation deposit at Eighteen Mile Wash in 1975 and at selected times in 1985. A, July 

7,1975, on the basis of cross-section surveys (Howard, 1975) and ground photography. B, May 22,1985, discharge 

45,000 ft3/s. C, August 2, 1985, discharge 30,000 ft3/s. D, October 9, 1985, discharge 4,100 ft3/s.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 17

Bedrock

D

FIGURE 12. Continued
18 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

zone, such as the spit at Eminence Break Camp (fig. 14). 

Observations at National Rapid in June 1985 suggest that 

these spits form where sediment transported by a 

primary or secondary eddy is rapidly deposited into a 

low-velocity area.

Separation deposits are not found downstream from all 

debris fans. For separation deposits to form, a stagedischarge relation and local topography must result in the 

existence of a low-velocity area and (or) secondary eddies 

upstream from the primary-eddy return current at some 

discharges. Debris fans with steep, high slopes do not 

typically have separation deposits because no discharges 

occur at which a low-velocity area or secondary eddy 

exists. At the study site Above Cathedral Wash, only 

discharges much greater than 100,000 fte/s would overtop 

the constricting fan. Some fine sediments exist on the 

talus at elevations associated with floods in excess of 

100,000 fte/s. No low-elevation part of the separation 

deposit projects downstream, however, because the

DOWNSTREAM

A 

100 H

JUJ >- "-£

2<

O 95-

UJ UJ

O

90

Elevation of water surface. 

May 22,1985

primary-eddy return current is adjacent to the talus at 

discharges less than 100,000 ft3/s. In contrast, at Eminence Break Camp, a large low-velocity area exists 

between the debris fan and the primary-eddy return 

current at discharges between 21,000 and at least 44,000 

ft3/s (fig. 14, bottom). Mean velocities in this area at 

Eminence Break Camp were always less than 1.0 ft/s. At 

Saddle Canyon, separation deposits mantle the upper 

surface of the debris fan but do not project offshore. 

Low-velocity areas are present upstream from the primary-eddy return current only at discharges above about 

31,500 fte/s, and the separation deposit is confined to a 

small high-elevation area (fig. 17).

Separation deposits may be subjected to significant 

wave action, particularly near steep rapids such as 

Nevills Rapid at river mile 75.5 and Granite Rapid at 

river mile 93.5. Howard and Dolan (1981) found that 

alluvial deposits had been reworked during approximately 10 years of operation of Glen Canyon Dam.

UPSTREAM 

A'

Trench

20i

0 10 METERS 

EXPLANATION

WINDBLOWN SAND

FINE TO VERY FINE SAND Ripple crosslamination in wash, some planar lamination

VERY FINE SAND Complex ripple crosslaminae and dimbing ripples, grade offsbpe into organic-rich 

sand

FINE SAND Steep foresets, disturbed upper surface, distinct avalanche laminae below, grades into 

"structureless" sand in wash below organic-rich sand of unit 4

FINE TO VERY FINE SAND Planar foreset laminae and irregular distorted crosslaminae in sets 

FINE TO VERY FINE SAND Highly truncated ripple crosslaminae with organic lenses 

RED SANDY GRAVEL 1984(?) flash flood deposit

FIGURE 13. Topography and sedimentology associated with upstream advancement of slipface, May 22,1985, and August 2,1985, at Eighteen 

Mite Wash. Location of section shown in figure 12. Descriptions by J.N. Moore, University of Montana, August 2, 1985. Vertical 

exaggeration 5x.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 19

Adjustment to the different intensities of current and 

wave action that exist at different sites had occurred. For 

example, they found that where nearshore currents 

exceeded 1 ft/s or where swash runup exceeded 3 ft, parts 

of the deposit within the zone of fluctuating discharges 

had low gradients (approximately 3° to 9°) and were 

composed of medium sand (0.19 mm median grain size). 

Where nearshore currents and swash were less intense, 

the median grain size was less than 0.14 mm and 

gradients exceeded 10°. Sampling of deposits formed in 

1983 or later does not demonstrate this kind of sorting. 

For example, some of the coarsest deposits reported by 

Lojko (1985) are at low-energy sites and some of the 

finest are at high-energy sites. The lack of sorting 

observed in deposits formed since 1983 is due to the fact 

that these primary fluvial deposits had not yet been 

subjected to fluctuating flows when they were sampled. 

Separation deposits may be finer grained than reattachment deposits. Graphic means ^Folk, 1968) were 

calculated for each of 67 samples collected at 22 sites 

between Lees Ferry and Bright Angel Creek (table 6). 

The mean value of the graphic means of each of 12 

samples of 7 separation deposits deposited after 1983 was 

0.17 mm. A similar mean value was computed for 10 

samples of 2 reattachment deposits; the sample mean was 

0.25 mm. In terms of the total number of samples of these 

two deposits, the two sample means differ significantly at 

the 95-percent confidence level. The small number of 

sample sites, however, precludes definitive statistical 

conclusions. This difference between grain size of separation and reattachment deposits is spatially illustrated 

at Saddle Canyon. Three samples of separation deposits 

at elevations associated with discharges in excess of 

45,000 ft3/s had graphic means between 0.10 and 0.13 mm 

(fig. 17). Samples of reattachment deposits associated 

with discharges exceeding 25,000 ft3/s were all equal to or 

coarser than 0.15 mm. The grain-size difference between 

separation and reattachment deposits is related to the 

lower mean velocities associated with low-velocity areas, 

which are the depositional environment of separation 

deposits, in contrast with the higher mean velocities of 

reattachment point areas.

REATTACHMENT DEPOSITS

Reattachment deposits occur at the downstream end of 

many recirculation zones and project upstream as spits 

(fig. 3). A slipface typically exists along the shoreward 

side of the spit (fig. 18). The form of these deposits is well 

displayed in aerial photographs (fig. 14) taken at low 

discharges of about 6,000 ft3/s. These deposits were 

directly observed during clear-water flows at discharges 

of 30,000 and 45,000 ft3/s and were mapped during 

bathymetric surveys at discharges of 15,000 to 25,000

ft3/s. Although the deposits tend to move and adjust to 

changing discharge, the basic shape remains the same.

Reattachment deposits form in primary eddies and 

build upstream from the reattachment point. Direct 

observations of surface-current patterns, migrating bedforms, and bedform-migration directions exposed in 

trenches show that sand transport over most of these 

deposits is away from and perpendicular to the main 

current direction. Sand is transported across the top of 

the deposit, cascades down the slipface, and is swept 

upstream by the primary-eddy return current.

Reattachment deposits fill recirculation zones to a 

varying extent. The low flows of October 1984 (fig. 9) 

exposed much of the bed of the recirculation zone at some 

locations (fig. 17), whereas at other locations, only a part 

of the deposit was exposed. Comparison of the area of 

reattachment deposit exposed at low discharge in 1973 

with the area exposed in 1984 for selected sites shows 

that at sites where exposed area decreased, the decrease 

occurred in the upstream part of the deposit (fig. 19). 

Topographic and side-scan sonar data indicate that the 

decrease in exposed area is due to (1) loss of sand from 

recirculation zones and (2) redistribution of the same 

mass into a smaller area of higher relief.

The topography of a typical reattachment deposit 

consists of a mound of sand or crest near the center of the 

deposit and a lower elevation extension of the crest 

downstream and onshore (fig. 18). A third area of higher 

elevation formed by high discharges may exist farther 

downstream.

The higher parts of reattachment deposits typically 

extend the farthest downstream. This pattern is related 

to the hydraulic changes in recirculation zones that occur 

with decreasing discharge. Reattachment points typically migrate downstream with increasing discharge and 

migrate upstream as discharge subsequently decreases 

(fig. 5). Therefore, alluvial deposits created at the 

highest discharges near the high-discharge reattachment 

point are abandoned by the recirculation zone as it 

decreases in size. Any downstream part of the sand 

deposit is subjected to downstream-directed flow, and 

eroded sand from these high banks is deposited in the 

main channel and not in the recirculation zone (fig. 20). 

Erosion or redistribution of sand upstream from the 

migrating reattachment point results in redistribution of 

sand within the recirculation zone and upstream migration of the slipface. Fluctuating flows may result in 

further redistribution of sand within recirculation zones. 

The crest of a reattachment deposit formed under steady 

flows may be changed to a gently sloping continuous 

surface under fluctuating flows, such as occurred at 

Blacktail Rapid (figs. 21, 22, and 23). The farthest 

downstream part of the reattachment deposit nearly 

always degrades during fluctuating flows. For example,
20 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

Aerial photograph by

U.S. Bureau of Reclamation

October 21.1984

100 200 300 400 FEET 

i ij

I 

100 METERS

Reattachmenr\v 

deposit

Separation deposit

FIGURE 14. Surficial geology and hydraulic features at Eminence Break Camp. North is toward the top.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 21

surveys at Blacktail Rapid (fig. 23, profile 1) and One 

Hundred and Twenty-Two Mile Creek showed significant 

bank retreat in this area between October 1985 and 

January 1986.

The effect of flow recession and recirculation zones that 

decrease in length on erosion of downstream parts of 

reattachment deposits was observed at Stone Creek 

where a steady discharge of about 40,000 ft3/s decreased 

to about 35,000 ft3/s in June 1985. Overnight, a cutbank 

downstream from the new reattachment point retreated 

2.75 to 3.5 ft and degraded about 1 ft. Two months later, 

the entire bar had been uniformly degraded to a new 

lower level.

Substantial reworking of reattachment deposits may 

occur at high discharges. At the site Above Cathedral 

Wash, a truncated pre-1983 deposit was exposed in a 

trench, indicating that sand close to the river channel had 

been transported and redeposited since deposition of the 

older buried surface (fig. 24). Opposite Nineteen Mile 

Canyon, a similar buried pre-1983 surface was eroded but 

not entirely truncated. The existence of major truncation 

surfaces within reattachment deposits and the evidence 

that some reattachment deposits were significantly

EXPLANATION

SP

RP

Profile

RIVER-DEPOSITED OR REWORKED 

VERY FINE TO MEDIUM SAND 

(October 21, 1984)

EOLIAN SAND OR TERRACE DEPOSITS Silt and fine sand, well sorted

TRIBUTARY DEBRIS FAN Boulders, 

cobbles, gravel, sand, poorly sorted; 

boulders cover more than 50 percent 

of surface area except in tributary 

streambed

COBBLES AND GRAVEL 

TALUS AND BEDROCK

EDGE OF WATER May 25, 1985, 

41,000 cubic feet per second

SEPARATION SURFACE-42,000 cubic 

feet per second

GENERALIZED SURFACE-FLOW DIRECTION IN RECIRCULATION ZONES41,000 cubic feet per second

SURFACE-FLOW DIRECTION OF MAIN 

CURRENT

SEPARATION POINT 

REATTACHMENT POINT

1- LOCATION OF PROFILE LINES (Numbers 

refer to table 13)

FIGURE 14. Continued

eroded by the 1983 high flows (see section entitled 

"Aggradation and Degradation of Alluvial Sand Deposits, 

1965-86") indicate that much of the sand in reattachment 

deposits is scoured, transported, and redeposited by high 

discharges. The form and sedimentology of reattachment 

deposits demonstrate that the final form is determined 

during flow recession. The discharge and sedimenttransport characteristics of that recession, therefore, are 

important in determining the form and extent of the 

resulting deposit.

Bedload samples were collected using a wading-type 

Helley-Smith sampler (Helley and Smith, 1971) in recirculation zones below Kwagunt Rapid (river mile 56) and 

above the confluence with the Little Colorado River 

(river mile 60) (table 5). These sites generally are 

representative of recirculation zones at moderate discharges of about 28,000 ft3/s. Mean velocities probably 

were less than 2 ft/s where samples were collected. At 

both sites, the samples collected were well-sorted medium sand (mean value of samples 0.30 mm). Coarser 

sand, therefore, was in transport at a discharge of 28,000 

ft3/s in the recirculation zones than is found in typical 

separation or reattachment deposits. This comparison 

suggests that separation and reattachment deposits can 

be redistributed in at least some recirculation zones at 

moderate discharges.

Reattachment deposits tend to be coarser than separation deposits (table 6). Reattachment deposits may also 

coarsen with decreasing elevation at a site, such as at 

Saddle Canyon (fig. 17). Three samples of 1983 deposits 

at that site are fine sand (table 5, JCS-10, JCS-11, 

JBG-18) or medium sand (JBG-17). Samples from areas 

inundated by flows less than 25,000 ft3/s (table 5, JCS-6, 

JCS-7, JCS-8, JCS-9) are medium sand except for one 

sample (JCS-5) of a rippled veneer of very fine sand. This 

latter deposit is representative of mainstem deposition 

when tributaries are contributing sediment to the Colorado River.

UPPER-POOL DEPOSITS

Upper-pool deposits line the channel banks upstream 

from many debris-fan constrictions. The deposits are 

used as campsites where vegetation has been cleared or 

where tamarisk trees do not densely cover an area, such 

as above North Canyon Rapid at river mile 20.3 and 

above Crystal Rapid at river mile 98.0. In plan view, 

these deposits are linear and parallel to the channel, 

consist of different terrace levels, and typically have a 

low-elevation spit that projects into the channel in an 

upstream direction. Where spits exist, they are associated with small recirculation zones upstream from a rapid 

and are formed by the same processes that form reattachment deposits.
22 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

High-elevation parts of upper-pool deposits probably 

are created by low-velocity downstream-directed overbank flows. An example of an upper-pool deposit is the 

campsite upstream from Granite Rapid. This deposit is 

adjacent to the pool above the rapid. The plan-view form

of the deposit exposed at low flow includes a spit 

projecting upstream into the channel with a slipface on 

the shoreward side. At about 25,000 ft3/s this deposit is 

located at the downstream end of a recirculation zone. 

Higher exposures of sediment deposited during 1983

B

FIGURE 15. Bathymetric contours within the recirculation zone at Eminence Break Camp. A, April 16,1985, discharge 26,100 fts/s. B, September

2, 1985, discharge 27,200 fts/s. C, January 16, 1986, discharge 23,600 fts/s.
CHARACTERISTICS AND CLASSIFICATION OF ALLUVIAL SAND DEPOSITS 23

show that at least a part of the deposit was created by 

upstream-directed flows, which indicates that this recirculation zone was larger at higher discharges.

Upper-pool deposits may be subjected to erosive 

downstream-directed currents when the downstream 

constriction is overtopped. In August 1985, upper-pool 

deposits at Cathedral Wash at river mile 2.3 and Six Mile 

Wash at river mile 5.7 were examined briefly to determine the effects of discharges of about 45,000 ft3/s. At 

each site, the upper-pool deposits had been eroded.

CHANNEL-MARGIN DEPOSITS

In some reaches, particularly where the channel is 

wide, sand deposits line the channel from a few hundred 

feet to nearly a mile. Channel-margin deposits are 

deposits that either lack the characteristic form of 

separation or reattachment deposits, or whose location in 

relation to recirculation zones was not known. Few

channel-margin deposits were investigated in detail; 

however, sedimentary structures within three such deposits (left bank beneath the U.S. Geological Survey 

cableway above the Little Colorado River confluence, 

Above Grapevine Rapid at river mile 81.1, and Pumpkin 

Springs at river mile 212) indicate that the deposits were 

formed by recirculating currents. Typically, these deposits mantle bedrock or talus. At low discharges, bedrock 

or talus may exist between the deposit and the water's 

edge. At other locations, parts of the channel-margin 

deposit have the form of a reattachment deposit. At low 

discharge, these deposits are adjacent to the water's 

edge.

DISTRIBUTION OF DEPOSITS

Alluvial deposits large enough for use as campsites are 

most numerous between river miles 45 and 75, 115 and 

140 (fig. 25), and 160 and 225. These areas are within

40

J_I

100 FEET

70

\ \ T \

0 30 METERS

EXPLANATION

BATHYMETRIC CONTOUR Hachures indicate 

depression. Elevations are related to an 

arbitrary local datum. Interval 10 and 2 feet

PROFILE LINE

FIGURE 15. Continued.
24 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

3

cc

00

cc

111

o

03

Ill 

111

150 0 50 100 

DISTANCE FROM POINT OF ORIGIN, IN FEET

EXPLANATION

__» April 16, 1985

September 2, 1985 

January 16, 1986

DISTANCE FROM POINT OF ORIGIN, IN FEET 

FIGURE 16. Bed-surface profiles (see figure 15 for locations) of a recirculation zone at Eminence Break Camp.
AGGRADATION AND DEGRADATION ATEIGHTEEN MILE WASH, 1965-86 25

Lower Marble Canyon, Furnace Flats, Aisles, Middle 

Granite Gorge, and the Lower Canyon. These reaches 

include all those designated as wide (table 2) except the 

Permian Section, where availability of campsites is 

limited by dense tamarisk tree groves and not by small 

alluvial sand deposits. Although the Aisles and Middle 

Granite Gorge reaches are designated narrow, there is 

great variability in channel width in these reaches, and 

campsites are located in parts of the reaches with wide 

channels or large expansions. Measurements of the area 

of major alluvial sand deposits in seven reaches show that 

average deposit size is also largest in the widest reaches 

(table 7). At a discharge of 5,600 ft3/s, average campsite 

size was 60,000 ft2 in Lower Marble Canyon but 8,200 ft2 

in the Muav Gorge. The smallest campsites are associated with reaches where channel-margin deposits are the 

main type (table 2). The largest campsites in Lower 

Marble Canyon are large reattachment deposits exposed 

at low discharge. Channel-margin and separation deposits are large in this reach as well.

Campsites noted on figure 25 are those inventoried by 

Brian and Thomas (1984) and are listed in appendix A. 

The type of each deposit was determined by locating 

campsites on aerial photographs and comparing their 

form with the characteristic shapes of different types of 

deposits as described in this section. Observations of 

surface-current patterns at these sites aided in classifying some sites.

The number of separation deposits ranges between 0.2 

and 1.0 deposits per mile throughout most of the river 

(table 2). The number of separation deposits used as 

campsites does not increase in wide reaches, although 

total number of campsites increases (fig. 25). Average 

area of major separation deposits is greater in wide 

reaches and varies in seven reaches between 14,500 and 

57,000 ft2. As described above, local topography of debris 

fans is the most important determinant in the occurrence 

of separation deposits. These deposits form wherever 

local site conditions permit, regardless of reach characteristics.

Channel-margin deposits are common in Lower Marble 

Canyon, Furnace Flats, and the Muav Gorge. At low 

discharges, these deposits have an average area of 73,000 

ft2 in Lower Marble Canyon but only 7,500 ft2 in the 

Muav Gorge (table 7). The largest channel-margin deposit in the Muav Gorge is 23,000 ft2 (river mile 140.2). 

Campsites in Furnace Flats are similar in size to those of 

Lower Marble Canyon. Large campsites are typically 

associated with reattachment deposits and may be 

formed by similar processes. In Muav Gorge, channelmargin deposits typically mantle talus or bedrock in small 

reentrants. Reattachment deposits large enough to be 

used as campsites are numerous only between river miles 

45 and 60 and between river miles 115 and 125.

AGGRADATION AND DEGRADATION AT 

EIGHTEEN MILE WASH, 1965-86

At some sites, we have enough data to develop a 

history of aggradation and degradation from 1965 to 

1986. The interpretation of data in the following section 

is illustrative of the interpretation of changes at other 

sites summarized in the section entitled "Aggradation 

and Degradation of Alluvial Sand Deposits, 1965-86."

HYDRAULIC CONDITIONS

A small separation deposit mantles the downstream 

part of a low debris fan at the mouth of Eighteen Mile 

Wash about 18.1 river miles downstream from Lees 

Ferry (fig. 11). About 15,000 ft2 of sand was exposed at 

5,600 ft8/s and covered about 30 percent of the Eighteen 

Mile Wash debris fan in October 1984. Boulders exposed 

along the edge of water at the base of much of the sand 

deposit at 2,500 ft8/s in October 1985 demonstrate that 

the sand deposit mantles the debris fan.

The Colorado River flows through a riffle of only 

slightly steepened water slope as it flows around the 

debris fan. A slope of 0.002 to 0.003 over a 600- to 700-ft 

reach exists at discharges between 4,000 and 45,000 ft8/s. 

The reach has a total elevation drop of about 3 ft or about 

one-fifth the drop of major Grand Canyon rapids. A large, 

deep recirculation zone exists on the left side of the 

channel immediately below the riffle. Bathymetric surveys at a discharge of about 30,000 ft8/s indicated average 

water depths of 20 ft and a maximum depth of 37 ft in this 

zone. The deepest part of the nearby main channel is 

about 50 ft. The recirculation zone exists at all discharges 

between at least 2,500 and 45,000 ft8/s and extends in 

length by 35 percent as discharges increase from 3,000 to 

45,000 ft8/s (fig. 6). Over this discharge range, the 

separation point is located on the downstream margin of 

the exposed boulder deposit and migrates downstream 

along the slope of the separation deposit as the discharges 

decrease below about 25,000 ft8/s (fig. 11). The location of 

the upstream part of the primary-eddy return current 

changes little with discharge.

Stage changes are significant in this reach where the 

channel width-to-depth ratio is less than 10. Between 

5,000 and 45,000 ft8/s, stage rises 20 ft; within the normal 

fluctuating flow range of 5,000 to 30,000 ft8/s, stage 

changes are about 14 ft. At the highest observed discharges (45,000 ft8/s), most of the Eighteen Mile Wash 

fan and the entire sand bar are submerged (fig. 125). On 

May 22, 1985, at a discharge of 45,000 ft8/s, the entire 

deposit was submerged by a low-velocity area, as described in the previous section. Current directions and 

bedform migration at this discharge show that flow and 

sediment transport over the deposit was upstream. A
26 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

Aerial photograph by 

U.S. Bureau of Reclamation 

October 21,1984

FIGURE 17. Surficial geology, hydraulic features, area of sand inundated at different discharges, and sediment-sampling sites at Saddle

Canyon.
AGGRADATION AND DEGRADATION ATEIGHTEEN MILE WASH, 1965-86 27

channel existed upstream from the slipface where flow 

was directed toward the main current.

In August 1985, conditions in the recirculation zone 

were observed at a discharge of about 28,000 ft3/s. The 

primary eddy was in approximately the same location; 

however, the entire surface of the deposit was exposed 

(fig. 12C). A small secondary eddy existed offshore from 

the downstream part of the deposit, and the mean 

velocities in this eddy did not exceed 1.2 ft/s. Elsewhere 

along the deposit face, measured mean velocities did not 

exceed 1 ft/s.

TOPOGRAPHIC CHANGES OF THE SEPARATION DEPOSIT

The first available aerial photograph showing topography of the deposit (fig. 26A) was taken May 14, 1965, at 

a daily mean discharge of about 26,700 ft3/s and at a stage 

of about 91 ft. Elevation of stage was estimated by 

comparison of shorelines in the 1965 photograph with 

mapping of the shoreline in 1985 at various discharges.

EXPLANATION

RIVER-DEPOSITED OR REWORKED FINE TO MEDIUM 

SAND Inundated by discharges less than 22,000 

cubic feet per second

RIVER-DEPOSITED OR REWORKED VERY FINE TO 

MEDIUM SAND Inundated by discharges between 

22,000 and 48,500 cubic feet per second

RIVER-DEPOSITED OR REWORKED VERY FINE TO 

FINE SAND Inundated by discharges between 

48,500 and 97,300 cubic feet per second

EOLIAN SAND OR TERRACE DEPOSITS Silt to fine 

sand, well sorted

TRIBUTARY DEBRIS FAN Boulders, cobbles, gravel, 

sand, poorly sorted; boulders cover more than 50 

percent of surface area except in tributary streambed

TALUS AND BEDROCK

EDGE OF WATER May 15,1986, 48,500 cubic feet per 

second

 SEPARATION SURFACE 48,500 cubic feet per second

YZA

- 

GENERALIZED SURFACE-FLOW DIRECTION IN RECIRCULATION ZONES-^8,500 cubic feet per 

second

SURFACE-FLOW DIRECTION OF MAIN CURRENT 

SEDIMENT SAMPLE SITE, TABLE 5

1-JCS-13

2-JCS-14

3-JCS-15

4-JCS-05,-06,-07

5-JCS-08,-09

6-JCS-10

7-JBG-17,-18

8-JCS-ll

9-JCS-12 

10-JBG-16

FIGURE 17. Continued

The shoreline along bedrock, talus, and the debris fan are 

very similar to the shoreline mapped in August 1985 at a 

discharge of about 28,000 ft3/s. River stage in the 

photograph of 1965 was estimated by referring to the 

surveyed elevation of the water surface in August 1985. 

Sand exposed in the photograph of 1965 exceeds the 

elevation of the observed water surface and thus must be 

higher than 91 ft (fig. 27).

In 1965, the deposit had an L-shape and bedrock was 

exposed between the deposit and water's edge at the 

downstream end. The part protruding toward the opposite bank may actually have been smaller than in 1985. A 

low area between the exposed debris fan and the sand 

deposit is believed to be a remnant return-flow channel.

Better topographic control exists for the data of the 

mid-1970's. An aerial photograph was taken on June 16, 

1973, at a discharge of about 4,500 ft3/s (fig. 265). River 

stage was estimated to be about 78 ft. In the same year, 

photographs were taken from nearby cliffs accessible 

from the river, and on July 7, 1975, Howard (1975) 

surveyed the topography of the deposit along two profiles.

A topographic map of the deposit as it existed in 1975 

was constructed from these data (fig. 12A). The exposed 

fan and separation deposit in a photograph taken October 

21,1984, at a discharge of 5,600 ft3/s (fig. 26C) are similar 

in plan view to these deposits in 1973 and 1975. Data from 

the topographic survey of 1975, however, show that the 

shoreward part of the deposit was about 87 ft in elevation 

and that the sand surface rose to about 98 ft in elevation 

near the bedrock wall (fig. 27). A substantial part of this 

deposit, therefore, degraded at least 4.5 ft between 1965 

and 1973. If the assumption is made that no change 

occurred in the estimated stage-to-discharge relation, 

this surface would be just overtopped by a discharge of 

18,000 ft3/s. Between 1965 and 1973, maximum powerplant flows were about 24,000 ft3/s (Howard, 1975) or a 

stage of 89.5 ft, which is sufficient to inundate the main 

surface to a depth of about 2.5 ft. The air and ground 

photographs of the mid-1970's also document tamarisk 

trees at approximately a stage associated with flows of 

24,000 ft3/s. The deposit was armored on all sides in 1973 

(fig. 26B).

After the flood of 1983, a resurvey of the deposit on 

September 13, 1983 (Beus and others, 1985), showed 

aggradation of about 6.5 ft on the stream side and about 

4 ft of erosion of the high sand bank that had existed along 

the bedrock cliff (fig. 27). The elevation of the crest of the 

deposit was about 94 ft. Comparison of the discharge 

record of 1983 and the stage-to-discharge relation shows 

that the lowest discharge immediately before exposure of 

the deposit on August 10 was about 36,000 ft8/s (stage, 94 

ft). This discharge had existed for about 8 days (fig. 28A). 

At that time, the separation deposit was within 1 ft of this
28 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

stage. The river had been receding from its peak discharge of 97,300 fts/s, which had occurred on June 29, 

1983.

A survey of the deposit on August 1, 1984 (Beus and 

others, 1985) (fig. 27), documented further aggradation of 

about 2 ft on the main surface to an elevation of about 96 

ft. On the basis of the hydrograph of that year (fig. 9) and 

the local stage-to-discharge relation, the only flows that 

could have caused this aggradation were the high releases of May to July 1984, when daily mean discharge 

was about 45,000 fts/s and stage was about 98 ft (fig. 

285). The bar aggraded to within 2 ft of the water 

surface. Although data are not available to date this 

aggradation more precisely, data collected in 1985 provide an insight into deposit response during high flows.

A resurvey of the deposit on May 22,1985, showed that 

the deposit was much smaller than in 1984 (figs. 12B and 

27). The river had been flowing between 38,000 and 

46,000 ft3/s since May 17,1985 (fig. 9). Aside from a 6-day 

period when daily mean discharge was about 30,000 fts/s, 

discharges exceeding 40,000 fts/s continued until June 25 

(fig. 28C). On the basis of the stage-to-discharge relation, 

the deposit would have been exposed on June 28 when

discharges receded below 40,000 fts/s. Resurveying on 

August 2, 1985 (figs. 12C and 27) showed that at least 

2,900 ft3 of sand, and more likely 13,000 ft8 , had been 

deposited since the survey of May 22 despite the fact that 

the crest of the deposit had not increased in elevation. 

The latter estimate is based (1) on projection of surveyed 

slopes for unsurveyed areas by assuming the angle of 

repose and (2) on extension to known debris-fan deposits 

at depth.

Analysis of sedimentary structures within this deposit 

showed that aggradation generally was consistent with 

directions of the current as measured in May. Steep 

planar foreset crossbeds document the upstream migration of the deposit (fig. 13); however, the deposit also 

aggraded on its downstream-facing slope (fig. 27).

Comparison of the surveys of August 1984 and May 

1985, therefore, suggests that degradation is associated 

with the initial rise of discharge. This interpretation is 

reasonable despite the fact that from August 11 until 

August 15, 1984, spillway tests were run at Glen Canyon 

Dam and instantaneous peak discharges reached 56,600 

fts/s (fig. 9). Daily mean discharges exceeded 40,000 ft3/s 

on three days. The extent of aggradation or degradation

FIGURE 18. Reattachment deposit at Eminence Break Camp, October 12, 1985, discharge 3,000 ft3/s.
AGGRADATION AND DEGRADATION AT EIGHTEEN MILE WASH, 1965-86 29

on these days of high flow is not precisely known. 

However, the high flows likely resulted in only minor 

erosion at this site, because aerial photography for 

October 21,1984 (fig. 26C) shows a deposit similar to that 

mapped earlier in 1984.

The exposed deposit surveyed on August 2, 1985, was 

slightly smaller than at the time of the survey of August 

1984 (fig. 27). The deposit may have been larger immediately after recession of the flows of 1984 than the same

^Jn°O ca ° «. <J ^%%r^»

teSfesesSiga^&Ss'fi ^ .a° -/fjour; ° ocs*^.^ : ^"^^ Oocfiaa-c?«^vH=?*^.»««r ^°<de?S-^a9f^ o^'o^^S^

,c?

-*5fer

EXPLANATION

REATTACHMENT DEPOSIT

DIRECTION OF FLOW NEAR REATTACHMENT DEPOSIT Proportioned to volume of flow; largest 

arrows, greatest volume of flow

FIGURE 19. Reattachment deposit at low discharge. A and B, Pattern 

typical of the mid-1970's. C, Typical pattern following recession of 

high flows in 1984 and 1985; smaller area of exposed sand may be of 

higher elevation than larger exposed areas of the mid-1970's.

deposit immediately after recession of the flows of 1985; 

however, erosion may have occurred in 1985 between the 

day of initial exposure, June 25, and the date of the 

survey, August 2. Thus, despite substantial scour of the

¥:i'<7o°".<?'l*J-.-?>rfa-fe,pi<i.

isport to slipface-,^ °n& v<7 'i^> ° * <^^ ,'U"f>o o^(/n ^y "

^°->&(10<}<^VttO> -^0 a "o"{telo' 

P °-o'U-''«C> 0"A;??o&r

Slipface migration into 

recirculation zone

«,'

RPH

RPL

EXPLANATION

SURFACE-FLOW DIRECTION, HIGH FLOW 

REATTACHMENT POINT, HIGH FLOW 

SURFACE-FLOW DIRECTION, LOW FLOW 

REATTACHMENT POINT, LOW FLOW 

EDGE OF REATTACHMENT DEPOSIT

FIGURE 20. Response of a reattachment deposit to decreasing discharge.

oS* &^

__^>

Rapid

-N-.(S?

: \: -':^

 v.si---.

: ----: ;-\-

v^

r r- : -^ W^.'--.

 : -- . ' .*

^ -.-'. ' 

>S : -' .- - .

 . ,:-.-X-

^^,

r/ 

s

r.

/

"?-; ,

l^:

y-

?< 

^V:-.v>t^*

.:-:^ :.'4

;;Avi ^\,s

0 100 200 300 400 FEET

I ' ' H '

0 100 METERS

EXPLANATION

LOCATION OF SEPARATION SURFACE, 20,000 

 ~~ CUBIC FEET PER SECOND, AUGUST 12, 1985

GENERALIZED SURFACE-FLOW DIRECTION IN 

RECIRCULATION ZONE, 20,000 CUBIC FEET 

PER SECOND

 .' / ;: .' ': ': : AREA OF BATHYMETRIC SURVEYS

FIGURE 21. Area of bathymetric surveys and hydraulic features at 

Blacktail Rapid.
30 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

deposit during the 1985 flood, the deposit likely never 

aggraded higher than 1 to 2 ft below the water surface in 

1984 or 1985. Each year, the deposit was reestablished in 

approximately its same shape. In each of these years, the

2070

906° V

B

30 METERS

EXPLANATION

 2086 BATHYMETRIC CONTOUR Hachures indicate depression. 

Elevations are related to National Geodetic Vertical Datum 

of 1929. Interval 10 and 2 feet

PROFILE LINE

FIGURE 22. Bathymetric contours within a recirculation zone below 

Blacktail Rapid. A, September 7, 1985, discharge 22,600 ft3/s. B, 

January 24, 1986, discharge 20,100 ft3/s.

flow receded in a similar pattern. In 1983, aggradation 

was well documented, but the resulting deposit was of 

lower elevation. The deposit was reworked by flows of 

36,000 ft3/s during flow recession. At that discharge, the 

deposit would also have been about 1 ft below water 

surface. The level to which the deposit typically restabilizes after initial scour may be a direct function of the rate 

of decrease in discharge during flow recession.

Net aggradation between 1983 and 1984 probably does 

not reflect greater sediment transport during the latter 

event, although sediment-transport data are not available to document main-channel conditions. Local geometry of the Eighteen Mile Wash debris fan is such that 

between 36,000 and 28,000 ft3/s, flow is diverted away 

from the separation deposit. Therefore, in 1984, separation-deposit elevation was related to the 45,000 ft3/s 

discharge, but in 1983 the deposit continued to be 

reworked until discharge dropped from 36,000 to 25,000 

ft3/s. In each case, equilibrium conditions limit aggradation to about 1-2 ft below the water surface in the 

low-velocity area.

After October 1, 1985, discharge never exceeded 

20,000 ft3/s or a stage of 88 ft during this study. Stage was 

sometimes as low as 76 ft. During this time, the downstream part of the deposit eroded rapidly (fig. 27). In 

January 1986, after 3 months of fluctuating flow, a 

3-ft-high cutbank still existed. It had retreated horizontally 15 to 25 ft between August and early January. All 

erosion between October and January can be attributed 

to strongly fluctuating flow, and at least part of the 

erosion from August to October probably is associated 

with the first few days of fluctuating flows before the 

survey in October. The base of the cutbank developed at 

the approximate elevation of the highest discharge of the 

fluctuations from October to midnjanuary. Most of the 

retreat, therefore, was caused by bank collapse from 

saturation and undermining of the well-sorted fine sand. 

Nearshore velocities did not exceed about 1 ft/s. Waves 

were not present at this site. Degradation of the slope 

below the cutbank, subject to daily discharge fluctuations, was at a lower rate than degradation of the high 

exposed cutbank.

Aggradation caused by the high releases of 1983 more 

than compensated for the erosion that had occurred 

between 1965 and 1975 (fig. 29). Data are not available for 

1975-83. Howard and Dolan (1981), however, observed 

that alluvial deposits had stabilized by the late 1970's. 

The alternating pattern of aggradation and degradation 

between June 1983 and May 1985 related to annual high 

flows is estimated on the basis of measured erosion and 

deposition during high releases in 1985 described above. 

The amount of degradation between August 1985 and 

January 1986 is similar to the net change between 1965 

and 1975. The rate of change measured in 1985 and 1986
BATHYMETRIC SURVEYS 31

far exceeds the average rate for the earlier period. The 

existence of a cutbank at the end of the special fluctuating-flow period suggests that erosion would have continued if strong fluctuations had continued beyond midJanuary. Therefore, at this site, newly aggraded deposits 

formed and reworked by flows in 1983, 1984, and 1985 

were unstable under strongly fluctuating discharge. 

Upslope projection of the lower part of the January 1986 

profile gives a likely minimum erosion that would have 

occurred if fluctuations had continued. A likely maximum 

extent of erosion would be degradation to the profile 

surveyed in 1975.

BATHYMETRIC SURVEYS

Short-term topographic changes in recirculation zones 

were measured by repetitive bathymetric surveys. The 

time of day and discharge during each survey are listed 

in table 1. Because these surveys are primarily of the 

lower elevation parts of recirculation zones, surveyed 

areas are not used as campsites; however, they are the 

major sand storage sites in recirculation zones.

The recirculation zone at river mile 120.1 just below 

Blacktail Rapid was surveyed with 710 data points in 

September 1985 and January 1986 (table 1). The zone is 

nearly circular in plan view (fig. 21). The primary eddy 

covers most of the area, although small secondary eddies 

were observed along the banks during both surveys. The 

zone has an excellent geometry for bathymetric surveying. Uncertainty in position is less than 5 ft over most of 

the area but reaches almost 18 ft at the extreme 

downstream end of the surveyed area.

The bathymetric map of September (fig. 22A) illustrates the characteristic shape of the sand deposit within 

the recirculation zone. The sand deposit had a relatively 

level upper surface and a steep slope into the main 

channel. A reattachment deposit and primary-eddy return-current channel were present on the upper surface. 

A small separation deposit was present at the upper end 

of the zone upstream from the return-current channel but 

was a minor part of the total zone. A bathymetric map 

based on the January survey shows that considerable 

changes had taken place in these features (fig. 225). 

Volume changes estimated for this recirculation zone by 

comparison of bathymetric maps represent change in

2090

2080

2070

? 2060

z 

o

I

a

2090

2080

Profile 1

150 100 50

2070

Profile 8

2090

2080 -

2070 -

2060 -

2050

2040 -

2030

September 7, 1985 

January 24, 1986

300 250 200 150 100 50 

DISTANCE FROM POINT OF ORIGIN, IN FEET

200 150 100 50 0 

DISTANCE FROM POINT OF ORIGIN, IN FEET

FIGURE 23. Bed-surface profiles (see figure 22 for locations) of a recirculation zone below Blacktail Rapid.
32 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

volume of sand below the stage corresponding to the 

discharge at the time of the surveys. Discharge was 

strongly fluctuating for most of the period between the 

surveys, but fluctuated less strongly (15,000-21,000 ft3/s) 

for the eight days before the January survey. Therefore, 

the observed changes may not be solely related to the 

effects of strongly fluctuating flow.

The return-current channel was shallower and less well 

developed during both surveys at this site than in other

surveyed recirculation zones, and it was shallower and 

less distinct in January than in September. The elevation 

of much of the reattachment deposit was 2-4 ft lower in 

January than in September, and the slope had flattened 

and moved toward the channel thalweg. Profiles drawn 

from bathymetric maps illustrate and quantify these 

changes (fig. 23). Profiles 1, 4, and 8 show how changes 

varied over the zone. The extreme downstream end of 

the zone (profile 1, fig. 23) and most of the crest of the

75

I

5 70 

cc

m 

cc

>65

CD

UJ 

U_

Discharge at

indicated stage,

in cubic feet

per second

44,000

60

UJ 

UJ

55 I

10 15 20 25 

DISTANCE FROM INITIAL POINT, IN FEET

30 35

EXPLANATION

5 Ffffli TO MEDIUM SAND Current ripples that migrate upstream on foresets that dip toward 

river, amplitude of current ripples decreases upsiope

4 FINE SAND Current ripples, current direction upstream away from main channel

3 1NTERBEDDED Fff^E SAND AND SILT Unit dips at low angle away from main channel or in 

downstream direction. Entire unit grades upward into unit 4

2 FINE SAND Generally massive with abundant roots and organic debris, includes an organic-rich 

lens that dips toward main channel. Laminae above the lens is contorted. Entire unit grades 

upward into unit 3 and pinches out 17 feet from initial point

1 BLACK AND GRAY CLAYEY AND SILTY FINE SAND Layers of sand define irregular bedding, 

upper contact is erosional and includes a vertical cutbank 33 feet from initial point. 

Interpreted to be pre-1983 deposit

FIGURE 24. Sedimentology exposed in a trench through the reattachment deposit at the site Above Cathedral Wash. Descriptions by T.R.

Clifton, University of California, Santa Cruz, January 9,1986.
BATHYMETRIC SURVEYS

reattachment deposit degraded, whereas the slope into 

the main channel aggraded (profile 4, fig. 23). At the 

upstream end, aggradation on the downstream side of the 

return-current channel caused the channel to shift toward the bank and to become shallower (profile 8, fig. 

23). On all profiles, the point of zero change is roughly 

coincident with the break in slope between the upper 

surface of the sand deposit and the slope into the main 

channel. In January the sand deposit sloped uniformly 

and gently toward the main channel and did not have a

distinct reattachment-deposit crest and primary-eddy 

return-current channel.

The amount of change between the two surveys was 

estimated by measuring the area between profile lines for 

successive surveys (fig. 23, table 8). Along all profiles, 

degradation totaled 1,100 ft2 and aggradation totaled 

3,010 ft2. Net change was 1,910 ft2 of aggradation. 

Vertical change along profiles was estimated by dividing 

the area of change by the length of the profile. An 

average of 1-2 ft of degradation occurred over the upper

cc

LU

E 

o

CJ

o

z

z

I

WIDE NARROW I

CHARACTERISTIC WIDTH OF REACH 

WIDE I NARROW

15

10

n i r n i i i i i i 

EXPLANATION

0.-... 0 Reattachment deposits 

X X Channel-margin deposits

i i r

O

Q_

LU

.

O 

tr

HI 

CD

B

75 

RIVER MILE

125 150 160

FIGURE 25. Variation with river mile in number of alluvial deposits identified in 1983 (Brian and Thomas, 1984) as campsites. A, Total number 

of deposits and number of separation deposits. B, Number of reattachment deposits and channel-margin deposits between Lees Ferry and 

National Rapid.
34 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

FIGURE 26. Colorado River 

near Eighteen Mile Wash. A, 

May 14, 1965, discharge 

26,700 ft3/s. B, June 16,1973, 

discharge 4,500 ft3/s. C, October 21, 1984, discharge 

5,600 ft3/s (U.S. Bureau of 

Reclamation photograph). 

Surficial geology is shown on 

figure 11.
BATHYMETRIC SURVEYS 35

surface of the deposit, and aggradation of 3-6 ft occurred 

along the slope into the main channel.

Areas of change along profile lines were used to 

estimate volume of change over the mapped area by

assuming that changes computed at profile lines took 

place over half the distance between a profile line and the 

adjacent line. For profiles 1 and 8 at the upstream and 

downstream ends of the area, only the area on the side of

100

Upper limit of river

outlet works and power

plant discharge

Upper limit of

power plant

discharge

20 40 60 

DISTANCE FROM BASELINE, IN FEET

120

EXPIANATION

1965 Minimum elevation estimated from aerial photograph

July 7, 1975 (Howard, 1975)

September 13, 1983 (Beus and others, 1985)

August 1, 1984, (Beus and others, 1985)

May 22, 1985

August 2, 1985

October 9, 1985

December 7, 1985

January 13, 1986

FIGURE 27. Topography along profile 2 (see figure 11 for location) at Eighteen Mile Wash.
36 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

50

45

40

35

30

Elevation of exposed deposit 

after recession

100

98

96

94

92

a

z 

o u

UJ 

DC 

ff

UJ 

UJ

u. 

o

CD

O 

U.

O

O

w 

O

- I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I MVI I I I I I 90

20 25 31 5 10 15 20 25 31

JULY AUGUST

4O

40

35

30

25

1 1

i 1

10

I I I D

Elevation of exposed deposit 

after recession

I I I

15

i j

i 1

M 

I

1 1 1

20

JULY

-

-

. i I : I ! 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

25 31 5 10 1

so 

96

94

92

90 

5

AUGUST

50

45 -

40

35

30

25

Elevation of exposed deposit 

after recession

UJ 

UJ

100

98

96

92

90

20 25 30 

JUNE

10 15 20 25 

JULY

31

FIGURE 28. Discharge and stage during recession of high flows at Eighteen Mile Wash. A, 1983. B, 1984. C, 1985.
BATHYMETRIC SURVEYS 37

the profile line toward the recirculation zone was used in 

the computation. The net volume of change is +122,000 ft3.

Aggradation of the slope between recirculation zone 

and thalweg cannot be attributed solely to degradation of 

the upper surface. Estimates of total volume change on 

the upper surface and on the slope indicate that four to 

five times more sediment aggraded on the slope than 

degraded from the upper surface.

The recirculation zone at Eminence Break Camp, at 

river mile 44.2, is almost twice as long as it is wide (fig. 

14). Bathymetric maps were made from surveys in April 

1985, September 1985, and January 1986 using 1,055, 

753, and 984 data points, respectively (fig. 15). Only the 

area of the recirculation zone inundated by a discharge of 

about 20,000 ft3/s was surveyed. Less than 5 percent of 

the reattachment deposit projects above the stage corresponding to 20,000 ft3/s. A large separation deposit 

mantles the upstream debris fan (fig. 14) and extends 

upslope above the area of bathymetric maps. The primary-eddy return-current channel, the reattachment 

deposit, and the slope into the main channel are similar to 

those at Blacktail Rapid. The return-current channel,

however, is more clearly defined and deeper at this site 

than at Blacktail Rapid, and the reattachment-deposit 

crest is more distinct (fig. 18). Data are sparse over the 

slope into the main channel, and uncertainty in position of 

the contours defining the slope is much greater than at 

Blacktail Rapid. Estimates of change on the slope, 

therefore, have not been made. The position uncertainty 

is least over the central part of the zone (4.3 ft) and 

greatest at the upper end (14.5 ft).

Comparison of maps for April and September shows 

that most of the zone degraded considerably. This period 

includes 2 months of releases through river outlet works 

(fig. 9). The upper end of the zone shoreward from the 

return-current channel aggraded. The slope into the main 

channel appears to have aggraded, but the amount is 

unknown because of uncertainty in the contours. Between September and January (fig. 15) during fluctuating 

flow, the crest of the reattachment deposit aggraded, 

whereas most of the upper surface of the deposit degraded. Profiles illustrate these changes (fig. 16). Along 

profile 2, at the upstream end of the zone, little change 

took place between April and September, but degradation occurred along the profile between September and

T 1 I I T 1 I T

i\

fc ui 

u.

Z

o

Z

1°

o

Z

\

\

-2

-3

\

\

-4 

1965

I l

\

I I I l I I I l l l l l l l I I I

1970 1975 

YEAR

1980 1985 1987

FIGURE 29. Net-elevation change of a separation deposit at Eighteen Mile Wash, 1965 to January 1986, along profile

2 (see figure 11 for location).
38 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

Reattachment deposit "I

Separation deposit

EXPLANATION

\ZL

RIVER-DEPOSITED OR REWORKED VERY FINE TO ~ - - 

MEDIUM SAND (October 21, 1984)

TRIBUTARY DEBRIS FAN Boulders, cobbles, gravel, 

sand, poorly sorted; boulders cover more than 

50 percent of surface area except in tributary 

streambed **~

COBBLES AND GRAVEL 

TALUS AND BEDROCK 

EDGE OF WATER

October 21, 1984, discharge about 5,600 cubic 

feet per second

August 15, 1985, discharge about 22,000 cubic 

feet per second

SEPARATION SURFACE, 22,000 CUBIC FEET PER 

SECOND

GENERALIZED SURFACE-FLOW DIRECTION IN 

RECIRCULATION ZONES, 22,000 CUBIC 

FEET PER SECOND

SURFACE-FLOW DIRECTION OF MAIN CURRENT

Profile 1 LOCATION OF PROFILE LINES (Numbers refer to 

table 13)

FIGURE 30. Area of bathymetric survey, surficial geology, and hydraulic features at National Rapid.
BATHYMETRIC SURVEYS 39

January. Deposition along the end of profile 7 nearest the 

bank caused the return-current channel to move toward 

the main channel between April and September (fig. 16). 

The crest of the reattachment deposit decreased in 

elevation and moved toward the main channel. The 

January profile shows that the reattachment deposit 

aggraded slightly between September and January but 

was still lower in elevation than in April. The deposit 

crest and return-current channel had returned to the 

positions of April. At the lower end of the recirculation 

zone, degradation occurred between April and September and aggradation occurred between September and 

January (profile 13, fig. 16). Like profile 7, profile 16 

shows that the surface in January was still lower than 

that in April in spite of aggradation.

Changes in area along profile lines at Eminence Break 

Camp are summarized in table 8. Because of uncertainty 

in the position of contours near the main channel, only 

areas of the upper-deposit surface were measured. Between April and September, total aggradation along 

profile lines was 1,670 ft2 , total degradation was 3,070 ft2, 

and net change was -2,400 ft2. Average vertical changes 

along profile lines ranged from +2.6 ft to -4.2 ft for April 

to September and from +2.3 to -5.4 ft for September to 

January (table 9). Between September and January, 

aggradation was 890 ft2 , degradation was 2,030 ft2, and 

net change was -1,140 ft2 . The net change for April to 

January was -3,540 ft2. Estimated volume change was 

-148,000 ft3 for April to September, -79,200 ft3 for 

September to January, and -227,000 ft3 for the entire 

period.

The recirculation zone just below National Rapid (fig. 

30) at river mile 166.6 is similar in shape to that at 

Eminence Break Camp. Data points for surveys in April 

1985, September 1985, and January 1986, which number 

768, 432, and 368, respectively, are evenly distributed 

over the zone. The bottom configuration at National 

Rapid (fig. 31) is also similar to that at Eminence Break 

Camp, having a well-defined return-current channel and 

reattachment-deposit crest. At this site, however, the 

reattachment-deposit crest is separated from the bank at 

the lower end of the recirculation zone by the returncurrent channel. A second recirculation zone was present 

downstream from the mapped area during all surveys, 

and the two zones may have joined at some discharges. 

Position uncertainty at this site varied from trip to trip 

because remote locations were different for each trip. In 

April and September, uncertainty was greatest at the 

upper and lower ends of the zone (10-11 ft) and least over 

the central part (4.3 ft). For the survey of January 1986, 

the uncertainty in position ranged from 4.3 ft at the upper 

edge near the bank to 8 ft at the edge toward the main 

channel near the center of the zone. A large separation 

deposit mantles the National Canyon debris fan. Most of

this deposit is higher in elevation than the stage during 

bathymetric surveying. No part of the reattachment 

deposit lies above the stage at which bathymetric surveys were made.

The shape of the primary-eddy return-current channel 

and reattachment deposit was similar during all three 

surveys (fig. 31). Although the elevation of the deposit 

crest remained about the same for all three surveys 

(about 1,736 ft), the position of the crest and returncurrent channel changed considerably. Between April 

and September, the side of the deposit nearest the bank

100 FEET

30 METERS

EXPLANATION

 7730 BATHYMETRIC CONTOUR Hachures indicate depression. Elevations are related to National Geodetic Vertical 

Datum of 1929. Interval 10 and 2 feet

(2] 'PROFILE LINE See figure 32 for bed-surface profile

FIGURE 31. Bathymetric contours within a recirculation zone below 

National Rapid. A, April 25,1985. B, September 10,1985. C, January 

28, 1986.
40 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

degraded and the side toward the main channel aggraded, resulting in movement of the deposit crest 

toward the main channel. The upstream end of the 

deposit aggraded, and the return-current channel moved 

upstream. By January, the return-current channel had 

migrated back to the position of April, and the shape and 

position of the reattachment deposit were also similar to 

those of April. Most of the slope into the main channel 

was not mapped at this site because air entrained in the 

water column at National Rapid interfered with the 

depth-sounder signal. The slope was mapped at the upper 

end of the recirculation zone, however, and the maps 

show that the slope aggraded between April and September and degraded between September and January. 

Six profiles across the mapped areas illustrate these 

changes (fig. 32). Profile 6 shows that at the downstream 

end of the deposit, downstream from the return-current 

channel, aggradation took place between April and September and degradation between September and January.

Aggradation between April and September was 879 

ft2 , degradation was 161 ft2 , and net change was +718 ft2 

(table 8). Between September and January, aggradation 

was 198 ft2 , degradation was 945 ft2 , and net change was

-747 ft2. Net change for the entire period was -29 ft2. 

Average vertical change along profiles ranged from 0 to 

+ 1.4 ft from April to December and from -0.2 to -1.8 ft 

from September to January (table 8). Estimated volume 

change was +39,400 ft3 between April and September,

-37,900 ft3 between September and January, and +1,500 

ft3 over the entire period.

A recirculation zone just below Nautiloid Canyon at 

river mile 34.8 was mapped on January 14, 1986, at 

discharges of 2,360 and 15,900 ft3/s to determine the 

magnitude of short-term changes in the sand deposits. 

Low-flow and high-flow maps were drawn from 836 and 

903 data points, respectively. The recirculation zone is 

more elongated than at Blacktail Rapid or Eminence 

Break Camp. The reattachment-deposit crest and returncurrent channel are the prominent features. A low area is 

present in the center of the deposit, and the deposit crest 

rises slightly as did the crest at Eminence Break Camp. 

The position uncertainty ranged from 4.5 ft at the upper 

and lower edges and toward the bank to 11.4 ft at the 

extreme edge toward the main channel. Although slight 

differences between the maps can be seen, the bottom 

configurations are almost identical. The differences are 

probably within the uncertainty caused by position uncertainty and that introduced by drawing contours from 

point data.

Bathymetric measurements document net degradation 

of the upper surface of recirculation zones at the three 

study sites where fluctuating flows were evaluated. 

Local aggradation of small areas did occur; however, net

change at Eminence Break Camp, Blacktail Rapid, and 

National Rapid was degradational. The slope into the 

main channel aggraded at Blacktail Rapid. Randle and 

Pemberton (1987) predicted that a change from high 

steady flow to fluctuating flow would cause decreased 

sand transport in the main channel, which would in turn 

cause main-channel aggradation. Aggradation along the 

slope at Blacktail Rapid, therefore, may be related to 

decreased main-channel sediment-transport capacity as 

well as delivery of sand from the upper surface of the 

recirculation zone. Behavior of recirculation zones between April and September differed at Eminence Break 

Camp and National Rapid. Measured changes, however, 

indicate that sediment was exchanged between the main 

channel and the recirculation zone during this period of 

high steady flows.

Sand-storage changes of the upper surface and at 

edges of recirculation zones are not indicative of those in 

the nearby main channel. Bathymetric surveys also show 

that the volume of aggradation and degradation of 

reattachment deposits far exceeds that of a typical 

separation deposit suchyas Eighteen Mile Wash. Bathymetric surveys cover rabst of the recirculation zones, and 

measured volume changes indicate that sand is exchanged between recirculation zones and the main channel as well as redistributed within recirculation zones. 

Although analyses of data from only a few sites (table 1) 

are presented, preliminary analysis of data from other 

sites indicates that the changes are representative of 

changes throughout the study reach.

AGGRADATION AND DEGRADATION OF 

ALLUVIAL SAND DEPOSITS, 1965-86

CHANGES IN ALLUVIAL SAND DEPOSITS, 1973-84

FLOW CHARACTERISTICS

Between June 1973 and May 1983, daily discharge 

generally fluctuated to meet hydroelectric needs (fig. 2). 

During this period, the average daily fluctuation range 

was 13,000 to 15,000 ft3/s. The average daily range is 

defined as the difference between the average monthly 

maximum and average monthly minimum release from 

Glen Canyon Dam. Except for 1980, instantaneous peak 

discharge at Lees Ferry was less than 31,000 ft3/s. In 

1980, mean daily discharge exceeded 30,000 ft3/s on 8 

days and peak discharge was 44,800 fte/s. Discharge 

dramatically increased in June 1983 and then receded in 

August to steady discharges of about 28,000 ft3/s. In May 

1984, discharge increased to about 45,000 ft3/s and then 

decreased to steady discharges of about 28,000 ft3/s in 

July (fig. 9). Between October 21 and 23, 1984, flow 

decreased to about 5,600 fte/s.
AGGRADATION AND DEGRADATION OF ALLUVIAL SAND DEPOSITS, 1965^86 41

1740

1730 -

1720 -

O 1710

1740

1730 -

5

LU

O

O 

O

LU

O

c 1720 -

LU

O 

CO

uj 1710

z 

o

ILU

1740

1730<>

1720 -

1710

150

150

200

200

Profile 6

100 150

EXPLANATION

-* April 25, 1985

September 10, 1985 

January 28, 1986

50 100 0 50 100 

DISTANCE FROM POINT OF ORIGIN, IN FEET 

FIGURE 32. Bed-surface profiles (see figure 31 for locations) of a recirculation zone below National Rapid.

200

200
42 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

CHANGES IN DEPOSITS

Large-scale changes in storage of sand in recirculation 

zones were evaluated by comparing inventories of exposed separation and reattachment deposits in 399 recirculation zones between river miles 0 and 118 (table 9). 

Because stage was very different in the two aerial 

photograph series in some reaches, only the presence or 

absence of sand was noted and the area of sand was not 

measured. Also, high flows scour and redistribute sand 

within recirculation zones. A decrease in area of sand 

may be the result of redistribution of sand within a 

recirculation zone and not represent net change in sand 

storage (fig. 19). Because comparison of inventories only 

indicates changes in presence of sand within recirculation 

zones, differences in inventories represent large-scale 

volume changes.

On the basis of this inventory, we conclude that sand 

was eroded from reattachment deposits between river 

miles 0 and 36 and 77 and 118. These included the 

narrowest reaches inventoried. The total number of 

separation deposits in these four reaches changed less 

than the number of reattachment deposits. Aggradation 

of reattachment deposits and minor aggradation of separation deposits occurred between river miles 36 and 77.

The most significant changes took place in the narrowest and steepest reaches as well as in those closest to Glen 

Canyon Dam (table 2). The change in reattachment 

deposits was slightly greater than the change in separation deposits. None of the deposits involved in these 

changes, however, had been inventoried as a campsite in 

1973 or 1983. The deposits that did increase or decrease 

in number were at too low an elevation to be considered 

as campsites.

Changes in area of major alluvial sand deposits during 

this period were measured for reaches between river 

miles 0 and 35.9 and river miles 122 and 150, where 

discharge in the 1973 and 1984 aerial photographs was 

approximately the same (fig. 4 and table 10). Major 

alluvial deposits were defined as those inventoried as 

campsites in 1973 or 1984 (appendix A) and other alluvial 

deposits in the same recirculation zones. If a separation 

deposit had been inventoried as a campsite and a reattachment deposit existed in the same zone, its area was 

also measured. Area changes were measured at less than 

45 percent of the total number of recirculation zones 

where presence or absence of deposits was determined.

Changes in area of reattachment deposits do not 

necessarily reflect changes in volume of stored sand in 

recirculation zones, because smaller deposits may be of 

higher elevation. As illustrated at Eighteen Mile Wash, 

the volume at a separation deposit changed where the 

area of deposit exposed at low discharge did not change. 

However, where area of separation or channel-margin

deposits changed, net aggradation or degradation probably also occurred. Changes in area do indicate the extent 

of reworking of different types of deposits, and area 

changes are directly related to the size of campsites. 

Measured areas were those exposed at low discharges, 

and smaller areas of these deposits are available as 

campsites at higher discharges, particularly at reattachment deposits.

No significant change in total area of deposits was 

measured in any reach except between river miles 0 and 

11.3. All the change measured in that segment was due to 

significant erosion of one point-bar deposit at river mile 

1.9; the total area of separation or reattachment deposits 

showed no significant change. Two categories of reach 

and deposit type, however, significantly decreased in 

area: separation deposits in Muav Gorge and reattachment deposits in Supai Gorge. Erosion of separation 

deposits in Muav Gorge is likely due to the low elevation 

of debris fans in this reach. Low-elevation debris fans 

were substantially overtopped by the high discharges of 

1983. The decrease in area of reattachment deposits in 

Supai Gorge is consistent with a decrease in number of 

reattachment deposits in the same segment (table 10). 

Therefore, a decrease in area in this segment probably 

reflects degradation of the deposits. The area of channelmargin deposits increased.

Although on an aggregate basis, major alluvial deposits in most reaches did not change significantly in total 

exposed area, 70 percent of all deposits either increased 

or decreased in area (table 11). About half of these 

increased and half decreased in area. More than 40 

percent of separation and upper-pool deposits did not 

change in area. In contrast, about 20 percent of reattachment and channel-margin deposits did not change. The 

dominant pattern of change of reattachment deposits was 

toward a decrease in area, and that of channel-margin 

deposits was toward an increase in area. Decreases in 

area of reattachment deposits were concentrated in Supai 

Gorge, and increases in area of channel-margin deposits 

were concentrated in Muav Gorge (table 11).

These conclusions refine the conclusion of Beus and 

others (1985) that aggradation of alluvial sand deposits 

had occurred throughout the river corridor. The sample 

of alluvial sand deposits studied by Beus and others 

(1985) included a large proportion of separation and 

channel-margin deposits, which in this study are shown 

to be stable or aggrading sites (table 12). Six separation 

deposits studied by Beus and others (1985) had net 

vertical aggradation and minor bank erosion. The general 

pattern of change at Eighteen Mile Wash during this 

period (fig. 29) was representative of other sites.

Ten study sites of Beus and others (1985) were 

channel-margin deposits. Erosion of deposits was measured in the narrow reaches of Supai Gorge, Upper
AGGRADATION AND DEGRADATION OF ALLUVIAL SAND DEPOSITS, 1965^86 43

Granite Gorge, and Muav Gorge. Eroded sites were 

typically small deposits mantling bedrock or talus and 

were associated with small recirculation zones. Larger 

channel-margin deposits in all reaches such as Lower 

Nankoweap Rapid, above Grapevine Rapid, and Granite 

Park Camp underwent vertical aggradation and some 

bank erosion. Only two reattachment deposits were 

surveyed, and aggradation of the upper surface of each 

deposit was measured.

CHANGES IN ALLUVIAL SAND DEPOSITS, HIGH FLOWS, 

MAY 1985

FLOW CHARACTERISTICS

On May 17, 1985, discharge at Lees Ferry increased 

from 26,000 ft3/s at 9:00 a.m. to 45,800 ft3/s at 5:30 p.m. 

Except for a 6-day period when mean daily discharge was 

about 30,000 ft3/s, discharges that exceeded 40,000 ft3/s 

continued until June 25. Discharge then decreased to less 

than 30,000 ft3/s (fig. 28). The resulting hydrograph is 

similar to those of 1984 and 1986.

CHANGES IN DEPOSITS

Separation deposits were surveyed at Badger Creek 

Rapid, Eighteen Mile Wash, Twenty Mile Camp, Eminence Break Camp, and National Rapid soon after the 

onset of high flows in May 1985 (table 1). These sites were 

also surveyed after recession of high flows in August. In 

all cases, net aggradation occurred in small areas associated with low-velocity areas upstream from the primaryeddy return current.

Data collected at Eighteen Mile Wash (discussed in the 

section entitled "Aggradation and Degradation at Eighteen Mile Wash, 1965-86") show that aggradation followed degradation. Aggradation caused the deposit to 

regain its approximate former shape and size.

At Badger Creek Rapid in May 1985, a wave-cut scarp 

developed as 0.5-ft-amplitude waves impinged on the 

deposit face during the increase in discharge. Aggradation of about 0.5 ft, however, was measured between May 

and August. This aggradation resulted in a beach profile 

parallel to the slope that was measured below the eroding 

scarp in May.

The reattachment deposit at Opposite Nineteen Mile 

Canyon was surveyed during high flows in 1985. Surveys 

indicated that the deposit was at approximately the same 

elevation as that of the previous summer, although it was 

probably smaller in area. The crest of the deposit was 

within about 1 ft of the water surface. After the recession 

of the flood of 1985, however, the crest lowered approximately 3 ft, although it retained its general shape. These 

changes indicate that the shape of the deposit changed

with onset of high flows and then readjusted during 

recession of the high flows. Comparisons of bathymetric 

surveys at Eminence Break Camp and National Rapid 

indicate that these reattachment deposits degraded between April and September despite retaining their overall shape. These observations suggest that reattachment 

deposits were entrained during these high flows.

CHANGES OF ALLUVIAL SAND DEPOSITS DURING

STRONGLY FLUCTUATING FLOW, OCTOBER 1985 TO

JANUARY 1986

FLOW CHARACTERISTICS

Between October 1, 1985, and January 15, 1986, 

releases from Glen Canyon Dam fluctuated widely (fig. 

2). Average monthly peak release during this time was 

between 19,300 and 20,300 ft3/s, and average monthly low 

release was between 1,800 and 5,500 ft3/s. Monthly mean 

discharge decreased from between 23,400 and 28,500 ft3/s 

for the period July to September 1985 to less than 12,000 

ft3/s during this special fluctuating-flow study period. 

The last previous month when monthly mean discharge 

was less than 12,000 ft3/s was March 1983. The average 

daily range of fluctuations was 15,100 ft3/s in October, 

14,000 ft3/s in November, and 18,500 ft3/s in December 

1985. During the 1976 to 1983 period, 41 percent of all 

months had average fluctuations less than 14,000 ft3/s. 

During this same period, 21 percent of all months had 

fluctuations between 14,000 and 16,000 ft3/s. Average 

fluctuations were 18,000 ft3/s or more in 9 percent of all 

months. Therefore, the fluctuation range of October and 

November 1985 was representative of a median range of 

fluctuations during the 1976 to 1983 period, and the range 

in December 1985 was representative of a less frequent 

operations regime. Except for the period immediately 

following official closure of Glen Canyon Dam in 1963, 

however, no precedent existed for the occurrence of 

widely fluctuating flows preceded by a lengthy period of 

steady flow.

CHANGES IN DEPOSITS

Although surveys along some profiles documented 

aggradation between October 1,1985, and January 1986, 

most measurements documented degradation (table 13). 

Of 41 profile lines at the 13 study sites that are separation 

deposits, about one-quarter of the lines showed net 

aggradation and about two-thirds showed net degradation (fig. 33). The mean net change along these profile 

lines was -0.65 ft. A part of every separation deposit 

degraded, and at seven sites, no areas of aggradation
44 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

were measured. Erosion in excess of 1 ft was measured 

at profiles at six widely spaced sites. Erosion associated 

with the special fluctuating-flow study period, therefore, 

was typical of sites throughout the Grand Canyon. At the 

end of the period, cutbanks existed at many sites, which 

indicated that profiles were not yet stable.

Channel-geometry characteristics of these study sites 

were compared. Five of the six sites where significant 

erosion was measured are located in narrow reaches 

where stage changes during fluctuating discharge are 

greatest. Significant erosion was not related to slope of 

the water surface through the constriction or constriction 

ratio of the site.

Locations of significant erosion were not related to 

locations of highest velocities in recirculation zones. In 

some cases, erosion occurred where nearshore currents 

were less than 1 ft/s, such as at Eighteen Mile Wash. At 

these sites, saturation of the lower part of a highelevation separation deposit is sufficient to cause bank 

failure. Failure occurred even where waves were absent. 

At each site, the amount of erosion increased with 

distance downstream from the separation point. For 

example, at Twenty-Nine Mile Rapid, the deposit degraded slightly at a profile 100 ft downstream from the 

separation point (fig. 34, profile 1), but degraded about 

2.8 ft along a profile 140 ft farther downstream (fig. 34, 

profile 2). Also, downstream migration of the separation 

point at that point exposed low-elevation areas of the 

upstream part of the separation deposit to downstreamdirected currents, as also occurred at Badger Creek 

Rapid (fig. 5) and at Eighteen Mile Wash. Where 

underlying debris-fan materials were exposed, degradation in the upstream part was restricted. These trends 

indicate that erosion tended to eliminate unarmored 

parts of separation deposits, especially where they 

project downstream from the debris-fan deposit.

WIDE | NARROW WIDE

CHARACTERISTIC WIDTH OF REACH 

| NARROW WIDE

LU 

Lit 

11.

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Lit

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-2

-3

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EXPLANATION

Range of value at a site

Value of vertical change at a profile

Range of value at a site

I

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100 

DISTANCE, IN RIVER MILES

FIGURE 33. Vertical change along profile lines at 13 separation deposits between October 1985 and January 1986.

200

U.S. GOVERNMENT PRINTING OFFICE: 1990 785-046/3036
AGGRADATION AND DEGRADATION OF ALLUVIAL SAND DEPOSITS, 1965-86 45

108

106

104

102

100

98

96

94

92

90

88

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LLJ S 84

^ 100

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94

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EXPLANATION

 August 4, 1985

-O October 11,1985

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-£ January 15, 1986

Profile 1

EXPLANATION

-* August 4, 1985

-O October 11,1985

-o December?, 1985

-A January 15, 1986

Profile 2

10 20 30 40 50 60 70 80 90 100 110 120 130 140

DISTANCE FROM INITIAL POINT, IN FEET 

100 200 300 400 FEET

FIGURE 34. Surficial geology and topography along two profiles at Twenty-Nine Mile Rapid. Mapped on

October 21, 1986; discharge, 5,600 ft3/s.
46 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

The upper surface of most surveyed reattachment 

deposits degraded during fluctuating flow. These 

changes were documented by bathymetric surveys at 

Eminence Break Camp, Blacktail Rapid, and National 

Rapid (table 8) and topographic surveys at Opposite 

Nineteen Mile Canyon, Saddle Canyon, and Hundred 

Twenty-Two Mile Creek (table 14). Only the deposit at 

the site Above Cathedral Wash aggraded. At this site, 

increase in volume occurred by vertical aggradation of 

about 0.5 ft as well as by upstream slipface migration of 

10-20 ft. Parts of the reattachment-deposit crest aggraded at Eminence Break Camp.

At the site Above Cathedral Wash, constriction-ratio 

and reach-segment characteristics are similar to other 

sites, and variations in these parameters do not explain 

the apparently unique behavior of the site. Proximity to 

the Paria River, which contributes a large amount of 

sediment, may be important. Twenty percent of the 

aggradation at the site was caused by sediment delivered 

by the Paria River on October 10 and 11. Between river 

miles 0 and 5, sediment finer than boulders covered 75 

percent of the bed, a large amount for the Colorado River 

in the park, and aggradation may have resulted from 

greater local availability of sand-size bed material.

As described in the section entitled "Bathymetric 

Surveys," aggradation occurred on the slope extending 

from the crest of the reattachment deposit to the thalweg 

at Blacktail Rapid. Decreased sediment transport was 

predicted by Randle and Pemberton (1987) throughout 

the river corridor, and aggradation along this slope 

probably occurred at other sites.

COMPARISON OF CHANGES IN ALLUVIAL SAND DEPOSITS

Aggradation and degradation occurred throughout the 

river corridor between 1983 and 1986. At some campsites, vertical aggradation of several feet occurred. 

Analysis of change in sand storage in all recirculation 

zones, however, shows that the number of reattachment 

deposits decreased 10 to 25 percent in the narrow reaches 

of Supai Gorge, Redwall Gorge, and Upper Granite 

Gorge (table 9). In Supai Gorge, major reattachment 

deposits also significantly decreased in area (table 10). In 

Muav Gorge, separation deposits inventoried as campsites decreased in area. In contrast, the number of 

deposits possibly increased in the wide reaches of Lower 

Marble Canyon and Furnace Flats (table 9). Area 

changes in these same reaches were not determined.

Separation deposits were more stable than other types 

of deposits. Analysis of volume changes at Eighteen Mile 

Wash shows that vertical aggradation can occur without 

change in area exposed at low flow. Erosion of separation 

deposits in Muav Gorge probably is related to lowelevation debris fans in this reach (table 10). Reattachment deposits are more susceptible to change during high 

flow, as indicated by the percentage of deposits that have 

changed in number (table 9) or area (table 11).

The response of channel-margin deposits is uncertain. 

Only in Muav Gorge was a significant change in total area 

measured. More than 50 percent of deposits increased in 

area. Classification of study sites evaluated by Beus and 

others (1985) suggests that small channel-margin deposits in narrow reaches were eroded, although vertical 

aggradation occurred at other sites.

These results indicate less change in major deposits 

due to high discharge in 1983-84 than that reported by 

Brian and Thomas (1984). Brian and Thomas (1984) 

inventoried campsites after recession of high flows in 

1983 and recognized many new or enlarged alluvial sand 

deposits. They also reported that about 10 percent of the 

preexisting campsites had been significantly eroded. 

Their inventory, however, was made at a discharge of 

about 25,000 ft3/s. The difference in results suggests that 

changes in high-elevation parts of alluvial deposits were 

more significant than changes in low-elevation parts.

Changes in area of high- and low-elevation parts of 

alluvial sand deposits were determined to evaluate topographic changes above and below an approximate stage 

corresponding to a discharge of 25,000 fts/s (table 14). At 

most sites, the area of the high-elevation part of the 

deposit above this stage increased or did not change 

between 1973 and 1984, whereas the low-elevation part 

typically decreased in size or did not change. These 

results show that although high-elevation parts of deposits aggraded, low-elevation parts either degraded or did 

not change. Patterns of change determined for highelevation parts are not necessarily consistent with 

changes in low-elevation parts.

The onset of strongly fluctuating flows in October 1985 

caused widespread erosion, especially in narrow reaches. 

Erosion of separation deposits occurred at sites as far as 

167 mi downstream from Lees Ferry (fig. 33). Erosion 

was typically of the sand that had been deposited in 

1983-85. Comparison of table 14 with figure 33 indicates 

that sites that eroded significantly between October 1985 

and January 1986 also had eroded significantly from 1965 

to 1973 and then had aggraded significantly during the 

1983 high flows. For example, at Eighteen Mile Wash, 

Twenty-Nine Mile Rapid, and Fern Glen Rapid, significant erosion was measured between October 1985 and 

January 1986. These sites had eroded significantly between 1965 and 1973 and aggraded in 1983. Significant 

aggradation was not followed by significant degradation 

in narrow reaches where a high separation deposit was 

armored from further erosion by exposed debris-fan 

deposits, as at Nautiloid Canyon.

The high flows of 1983 and 1984, therefore, redistributed much sand and removed sand from 10 to 25 percent
SUMMARY 47

of recirculation zones in at least those narrow reaches 

within 160 mi of Lees Ferry. Significant aggradation, 

however, occurred at many major campsites. Aggradation may have occurred in recirculation zones in wide 

reaches. Many new alluvial sand deposits eroded rapidly 

when exposed to strongly fluctuating discharges, which 

suggests that most of the gain in sand resulting from high 

flows was of short duration.

SUMMARY

This report has presented a classification of alluvial 

sand deposits, described some characteristics of these 

deposits, and described changes that have occurred in 

these deposits since completion of Glen Canyon Dam. The 

classification of alluvial sand deposits and the designation 

of reaches within the Grand Canyon were used to 

distinguish styles of change in narrow and wide reaches. 

Measurement of topographic changes in alluvial deposits 

were based on topographic and bathymetric surveys and 

analysis of aerial photographs.

The largest and most numerous alluvial sand deposits 

along the Colorado River in Grand Canyon National Park 

are formed in zones of recirculating current. Recirculation zones are caused by large debris fans that partially 

block the channel and by minor bedrock or talus abutments. Alluvial sand deposits can be classified by form 

and location. Separation deposits are located near the 

point of flow separation, mantle debris fans, and extend 

to the edge of the primary-eddy return-current channel. 

Reattachment deposits are located near the point of flow 

reattachment and project upstream beneath the primary 

eddy. Channel-margin deposits are terracelike in form 

and may fill re-entrants or extend continuously along the 

channel in wide reaches for lengths of 1 mi. Channelmargin deposits probably are formed in recirculation 

zones.

The Colorado River corridor in Grand Canyon National 

Park was divided into 11 reaches. Separation deposits 

large enough to be used as campsites are common 

throughout the river corridor in narrow and wide 

reaches. Reattachment and channel-margin deposits 

large enough to be used as campsites are common only in 

wide reaches except in the Muav Gorge, where channelmargin deposits are common.

The form and sedimentology of alluvial sand deposits 

reflect the hydraulic and sediment-transport conditions 

existing during reworking and deposition of the deposit. 

Separation deposits form in lower velocity parts of the 

river than reattachment deposits and may be composed 

of slightly finer sand. At sufficiently high discharge, both 

separation and reattachment deposits are reworked, and 

sand is redistributed within the recirculation zone and

between the recirculation zone and the main channel. 

This response to high flow is documented by repeated 

topographic surveys and sedimentologic analysis of study 

sites Above Cathedral Wash, at Eighteen Mile Wash, 

and Opposite Nineteen Mile Canyon and by repeated 

bathymetric mapping at Eminence Break Camp, Blacktail Rapid, and National Rapid.

During recession from high flows, redistribution of 

sand within recirculation zones may result in degradation 

of the deposit. The high flows of 1983 and 1984 removed 

sand from recirculation zones in narrow reaches within 

118 mi of Lees Ferry. When the rate of recession is great 

enough, topographic conditions at some sites cause flow 

to be directed away from a sand deposit and leave it 

exposed, such as at Eighteen Mile Wash. At other sites, 

especially reattachment deposits, redistribution of sand 

may continue even during a rapid recession. At many 

reattachment deposits, the result is erosion of downstream areas and loss of sand to the main channel and 

redistribution of sand in other parts of the deposit within 

the recirculation zone. Higher rates of recession allow 

less time for this distribution and therefore may result in 

exposure of larger areas of alluvial sand deposits after 

recession at some sites.

Fluctuating flows following high steady flows during 

the study period resulted in significant erosion. Fluctuating flows typically redistributed sand within recirculation zones and may deposit sand along the slope from the 

reattachment-deposit crest to the thalweg. Although 

erosion was significant throughout the park with the 

onset of fluctuating flow, results of topographic surveys 

by other investigators in the late 1970's indicate that 

equilibrium was reached after a few years. Topographic 

surveys between October 1985 and January 1986 indicate 

that such stability was not reached within 3-1/2 months 

of strongly fluctuating flow. Redistribution of sand can 

affect significant parts of alluvial sand deposits.

Bathymetric surveying at three sites shows that net 

volume changes can occur in recirculation zones at a 

broad range of discharges. At each site, net volume 

changes indicate that large volumes of sand may be 

exchanged between recirculation zones and the main 

channel even at moderate or fluctuating discharges.

The high flows of 1983 and 1984 eroded sand from 

recirculation zones in narrow reaches. The high flows 

may have resulted in aggradation of all types of alluvial 

sand deposits in wide reaches. Limited evidence suggests 

that high flows in 1985 caused further erosion of reattachment deposits in narrow reaches.

Alluvial sand deposits used as campsites, whatever 

their type, are more stable than the smaller, lowerelevation deposits of the same type not used as campsites. Many campsites aggraded significantly during high 

flows in 1983. Fluctuating flows in 1985 and 1986 caused
48 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

rapid erosion of many deposits of all types throughout the 

Grand Canyon. The greatest erosion typically occurred at 

sites where significant deposition had occurred in 1983. 

The increase in sand at campsites from high flow therefore is of limited duration if strongly fluctuating flows 

follow. During these same high flows, sand was removed 

from other recirculation zones in narrow reaches. Separation deposits are more stable than reattachment deposits, although erosion can occur in reaches where 

separation deposits are of low elevation such as Muav 

Gorge. An inventory of campsites in 1983 showed that 

narrow reaches generally have few campsites. The high 

flows of 1983-85 followed by strongly fluctuating flows in 

1985 resulted in accentuating the difference between 

campsite availability in narrow and wide reaches.

REFERENCES CITED

Anderson, T.W., and White, N.D., 1979, Statistical summaries of 

Arizona streamflow data: U.S. Geological Survey Water-Resour-

/ ces Investigations 79-5, 416 p.

43eus, S.S., Carothers, S.W., and Avery, C.C., 1985, Topographic 

j: changes in fluvial terrace deposits used as campsite beaches along 

- ,... the Colorado River in Grand Canyon: Journal of the ArizonaNevada Academy of Science, v. 20, p. 111-120.

Birdseye, C.H., 1923, Plan and profile of Colorado River from Lees 

Ferry, Arizona to Black Canyon, Arizona-Nevada: U.S. Geological 

Survey topographic maps, 21 sheets, scale 1:31,680.

Brian, N.J., and Thomas, J.R., 1984, 1983 Colorado River beach 

campsite inventory, Grand Canyon National Park, Arizona: Division of Resources Management, Grand Canyon National Park 

report, 56 p.

Burkham, D.E., 1986, Trends in selected hydraulic variables for the 

Colorado River at Lees Ferry and near Grand Canyon, Arizona, 

1922-84: U.S. Bureau of Reclamation, Glen Canyon Environmental Studies Report, 51 p.

Dolan, Robert, Howard, Alan, and Gallenson, Arthur, 1974, Man's 

impact on the Colorado River in the Grand Canyon: American 

Scientist, v. 62, p. 393-401.

Dolan, Robert, Howard, Alan, and Trimble, David, 1978, Structural 

control of the rapids and pools of the Colorado River in the Grand 

Canyon: Science, v. 202, p. 629-631.

Ferrari, Ronald, 1987, Sandy beach area survey along the Colorado 

River in the Grand Canyon National Park: U.S. Bureau of 

Reclamation, Glen Canyon Environmental Studies Report, 23 p.

Folk, R.L., 1968, Petrology of sedimentary rocks: Austin, Texas, 

Hemphill, 170 p.

Graf, J.B., 1986, Sediment transport under regulated flow, Colorado 

River, Grand Canyon National Park, Arizona: Eos, American 

Geophysical Union Transactions, v. 67, no. 44, p. 950.

Grand Canyon Natural History Association, 1976, Geologic map of the 

Grand Canyon National Park, Arizona: Grand Canyon, Arizona, 

Grand Canyon Natural History Association, scale 1:62,500.

Helley, E.J., and Smith, W., 1971, Development and calibration of a 

pressure-difference bedload sampler: U.S. Geological Survey 

open-file report, 18 p.

Howard, A.D., 1975, Establishment of benchmark study sites along the

Colorado River in Grand Canyon National Park for monitoring of 

beach erosion caused by natural forces and human impact: 

University of Virginia Grand Canyon Study, Technical Report no. 

1, 182 p.

Howard, A.D., and Dolan, Robert, 1979, Changes in the fluvial deposits 

of the Colorado River in the Grand Canyon caused by Glen Canyon 

Dam, in Lin, R.M., ed., First Conference on Scientific Research 

in the National Parks, v. 2, New Orleans, Louisiana, November 

9-12, 1976, Proceedings: National Park Service Transactions and 

Proceedings Series, no. 5, p. 845-851.

 1981, Geomorphology of the Colorado River in the Grand 

Canyon: Journal of Geology, v. 89, no. 3, p. 269-298.

Hunter, R.E., 1977, Terminology of cross-stratified sedimentary layers 

and climbing-ripple structures: Journal of Sedimentary Petrology, 

v. 47, no. 2, p. 697-706.

Kieffer,S.W., 1985, The 1983 hydraulic jump in Crystal Rapid Implications for river-running and geomorphic evolution in the Grand 

Canyon: Journal of Geology, v. 93, no. 4, p. 385-406.

Laursen, E.M., Ince, Simon, and Pollack, Jack, 1976, On sediment 

transport through Grand Canyon: Third Federal Interagency 

Sedimentation Conference Proceedings, p. 4-76 to 4-87.

Laursen, E.M., and Silverston, E., 1976, Camera stations along the 

Colorado River through the Grand Canyon Supplement to the 

final report on the hydrology and sedimentology of the Colorado 

River: Division of Resource Management, Grand Canyon National 

Park, 150 p. [Unpublished report to the National Park Service.]

Leopold, L.B., 1969, The rapids and the pools Grand Canyon, in The 

Colorado River region and John Wesley Powell: U.S. Geological 

Survey Professional Paper 669, p. 131-145.

Lojko, F.B., 1985, Beach sand grain size on the Colorado River in the 

Grand Canyon, in House, D.A., ed., Colorado River investigations III: Flagstaff, Northern Arizona University, p. 85-93.

Matthes, G.H., 1947, Macroturbulence in natural streamflow: Transactions of the American Geophysical Union, v. 28, no. 2, p. 

255-262.

Orvis, C.J., and Randle, T.J., 1986, Sediment transport and river 

simulation model: Fourth Federal Interagency Sedimentation 

Conference, v. 2, Las Vegas, Nevada, March 24-27, 1986, 

Proceedings, p. 6-65 to 6-74.

Pemberton, E.L., and Randle, T.J., 1986, Colorado River sediment 

transport in Grand Canyon: Fourth Federal Interagency Sedimentation Conference, v. 2, Las Vegas, Nevada, March 24-27, 1986, 

Proceedings, p. 4-120 to 4-130.

Randle, T.J., and Pemberton, E.L., 1987, Results and analysis of 

STARS modeling efforts of the Colorado River in Grand Canyon: 

U.S. Bureau of Reclamation, Glen Canyon Environmental Studies 

Report, 41 p.

Schmidt, J.C., 1986, Controls on flow separation and sedimentation in 

a bedrock river, Colorado River, Grand Canyon, Arizona: Geological Society of America Abstracts with Programs, v. 18, p. 741.

Turner, R.M., and Karpiscak, M.M., 1980, Recent vegetation changes 

along the Colorado River between Glen Canyon Dam and Lake 

Mead, Arizona: U.S. Geological Survey Professional Paper 1132, 

125 p.

Webb, R.H., Pringle, P.T., and Rink, G.R., 1987, Debris flows in 

tributaries of the Colorado River, Grand Canyon National Park, 

Arizona: U.S. Geological Survey Open-File Report 87-118, 64 p.

Wilson, R.P., 1986, Sonar patterns of Colorado riverbed, Grand 

Canyon: Fourth Federal Interagency Sedimentation Conference, 

v. 2, Las Vegas, Nevada, March 24-27, 1986, Proceedings, p. 

5-133 to 5-142.
TABLES 1-14; 

APPENDIX A

TABLES 1-14 51

TABLE 1. Summary of study sites and types of data collected

[X, indicates data were collected; dashes indicate no data collected; (DSS), detailed study site; N.A., not available. Time of study is that of bathymetric survey. 

Discharges were estimated during bathymetric surveys or taken from nearest gaging station during day of work. Multiple bathymetric surveys indicated by 

number in parentheses]

Date and 

River Site time of 

mile number study

Discharge, 

in cubic feet 

per second

Bathymetric 

survey

SurfaceTopographic Photographic flow 

survey replications pattern

Watersurface Scour 

slope chains

Sedimentology

(DSS) Above Cathedral Wash (original surveys)

2.5 1 05-18-85 

07-29-85 

08-29-85(1530) 

10-04-85 

12-07-85 

01-09-86 (1600) 

05-13-86

44,700 

26,000-29,000 

27,100 

4,000-19,000 

2,600 

16,300 

48,500

X 

X

X 

X 

X

X 

X 

X 

X

X

X 

X

X

X 

X

X 

X X

X 

X

(DSS) Badger Creek Rapid (original surveys)

7.9 2 04-13-85 (1400) 

05-19 to 05-21-85 

07-30 to 07-3 1-85 

08-30-85 (1500) 

10-05 to 10-06-85 

12-07-85 

01-11-86 (1730)

17,900 

40,000-45,000 

25,000-31,000 

29,800 

3,000-17,000 

-3,000 

2,870-21,500

X 

X

X(2)

X 

X

X 

X 

X

X 

X

X 

X

X

X

X 

X

X

x

X 

X

X 

X

(DSS) Soap Creek Rapid (initial survey, Ferrari, 1987)

11.4 3 05-21 to 05-22-85 

08-01-85 

10-07-85 

01-12-86

44,000-45,000 

25,000-31,000 

4,000-18,000 

2,000-21,000

... X 

X 

X

X 

X 

X 

X

X 

X 

X 

X

X 

X 

X X 

X

X

(DSS) Below Salt Water Wash (original survey)

12.2 4 05-21 to 05-22-85 

08-01-85 

10-08-85 

01-13-86

44,000-45,000 

25,000-31,000 

4,000-15,000 

2,000-21,000

... X 

X

X 

X 

X

X 

X 

X 

X

X 

X

X 

X

(DSS) Eighteen Mile Wash (initial survey, Howard, 1975)

18.1 5 05-22-85 

08-02-85 

10-09-85 

12-07-85 

01-13-86

45,000 

28,000-30,000 

4,000-20,000 

-5,000 

2,000-21,000

...

X

X 

X 

X 

X

X 

X 

X

X

X 

X 

X

X

X 

X 

X

X

X

Below Eighteen Mile Wash

18.2 6 08-02-85 

10-09-85

28,000-30,000 

4,000-20,000

... ... X 

X

X 

X ...

...

(DSS) Opposite Nineteen Mile Canyon (initial survey, Howard, 1975)

19.0 7 05-23-85 

08-03-85 

10-09 to 10-11-85 

12-07-85 

01-14-86

42,000-45,000 

24,000-29,000 

4,000-20,000 

-5,000 

2,000-21,000

...

X

X 

X 

X 

X

X 

X 

X

X

X 

X 

X

X

X 

X X

X 

X

(DSS) Twenty MUe Camp (initial survey, Ferrari, 1987)

19.8 8 08-03-85 

10-11-85 

01-14-86

24,000-29,000 

4,000-15,000 

2,000-21,000 E

X 

X 

X X

X 

X X

...

(DSS) Twenty-Nine Mile Rapid (original survey)

29.2 9 05-24-85 

08-04-85 

10-11-85 

12-07-85 

01-15-86

44,000 

23,000-29,000 

4,000-15,000 

-5,000 

3,000-22,000

X 

X 

X 

X

X 

X 

X

X

X 

X 

X

X X

X
52 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE 1. Summary of study sites and types of data collected Continued

River 

mile

Date and 

Site time of 

number study

Discharge, Surface- Waterin cubic feet Bathymetric Topographic Photographic flow surface Scour 

per second survey survey replications pattern slope chains

Sedimentology

(DSS)Nauttloid Canyon (initial survey, Howard, 1975)

34.7 10 05-24-85 

08-04-85 

09-01-85 (0945) 

10-12-85 

01-14 to 01-15-86

44,000-48,000 X X 

23,000-29,000 X X 

27,600 X 

3,000-15,000 X X 

2,360; 15,900 X(2) X X

X X

x 

x

X X

...

Tatahateo Wash (initial survey, Ferrari, 1987)

37.3 11 08-04-85 

10-12-85

23,000-29,000 X X 

3,000-15,000 X

...

(DSS) Eminence Break Camp (original survey)

44.2 12 04-16-85 (0630) 

04-17-85 (0645) 

05-25-85 

08-05-85 

09-02-85 (0910) 

10-12-85 

01-16-86 (0915)

26,100 X 

26,000 X 

40,000-47,000 X X 

25,000-31,000 X X 

27,200 X 

3,000-15,000 X X 

23,600 XXX

x

X X 

X X

X X 

X X X

(DSS) Saddle Canyon (initial survey, Ferrari, 1987)

47.2 13 01-18-86 

05-14-86

13,000-24,000 X 

48,500

X X

x

...

Kwagunt Rapid (initial survey, Ferrari, 1987)

56.3 14 08-06-86 

10-13-86

26,000-30,000 X X 

3,000-12,000 X

x

...

Little Colorado River confluence (original survey)

61.1 15 04-19-85 (1240) 

05-27-85 

08-06-85 

09-03-85 (1105) 

09-04-85 (0840) 

01-17-86(1535) 

01-18-86

24,000 X 

40,000-47,000 X 

26,000-30,000 X X 

29,200 X 

26,500 X 

19,600 X 

13,000-26,000 X X

X X

x 

x

...

Below Little Colorado River confluence (initial survey, Howard, 1975)

61.7 16 01-20-86 12,000-21,000 X ... ...

Above Unkar Rapid (initial survey, Ferrari, 1987)

72.5 17 01-19-86(1400) 

01-20-86

N.A. X 

12,000-21,000 X

...

...

NeviDs Rapid (original survey)

75.6 18 08-07-85 

01-20-86

17,000-24,000 X X 

12,000-21,000 X X

x

X X ...

(DSS) Above Grapevine Rapid (initial survey, Howard, 1975)

81.1 19 05-29-85 

08-07-85 

10-15-85 

01-21-86

44,000-46,000 X X 

17,000-24,000 X X 

N.A. X X 

12,000-18,000 X X

x 

x 

x 

x

...

Cremation Camp (initial survey, Howard, 1975)

87.1 20 04-21-85 

05-30-85 

09-05-S5 (1355) 

01-20-86 (1440) 

01-21-86 (1150)

23,800-26,300 X(2) 

45,000-47,000 

29,300 X 

17,800 X 

15,300 X

!.. x
TABLES 1-14 53

TABLE 1. Summary of study sites and types of data collected Continued

River 

mile

Date and 

Site time of 

number study

Discharge, Surface- Waterin cubic feet Bathymetric Topographic Photographic flow surface Scour 

per second survey survey replications pattern slope chains

Sedimentology

(DSS) Ninety-One Mile Creek (original survey)

91.0 21 08-08-85 

10-15-85 

01-22-86

19,000-24,000 X X 

N.A. X X 

13,000-22,000 X X X X

...

Trinity Creek

91.4 22 08-08-85 

01-22-86

19,000-24,000 X 

13,000-22,000 X

...

(DSS) Granite Rapid (initial survey, Howard, 1975; Ferrari, 1987)

93.1, 

93.4

23 05-31 to 06-01-85

08-09-85 

01-22-86

42,000-47,000 X X X

18,000-22,000 X X 

13,000-22,000 X X

...

Ninety-Six Mile Camp

96.0 24 06-01-85 

08-09-85 

10-16-85

42,000-47,000 X 

18,000-22,000 X 

N.A. X ...

(DSS) Boucher Rapid (original survey)

96.6 25 08-09-85 

10-16-85 

01-23-86

18,000-22,000 X XXX 

N.A. ... X XXX 

15,000-22,000 X XX

...

Upper Crystal Rapid

98.0 26 01-22-86 (1610) N.A. X ...

Elves Chasm (original survey)

116.0 27 10-17-85 

01-24-86

N.A. ... x XX

15,000-23,000 X XXX

(DSS) One Hundred Twenty Mile Camp (initial survey Ferrari, 1987)

119.7 28 08-11-85 

10-17-85 

12-08-85 

01-08-86

19,000-23,000 X 

N.A. X X 

6,000 X 

N.A. X

X

(DSS) Lower Bbcktafl Rapid (original survey)

120.1 29 06-02 to 06-03-85 

08-12-85 

09-07-85 (0805) 

10-18-85 

12-08-85 

01-13-86 

01-24-86 (1435)

45,000-47,000 ... X XXX 

16,000-22,000 XXX 

22JSOO X 

N.A. X X X X X 

6,000 X 

N.A. X --- X 

20,100 X X

...

One Hundred Twenty-Two Mile Rapid

121.6 30 06-05-85 

08-13-85 

10-18-85 

01-26-86

44,000-46,000 X X 

19,000-23,000 X X 

N.A. X X 

21,000-25,000 X

...

(DSS) One Hundred Twenty-Two Mile Creek (original survey)

122.0 31 06-05-85 

08-13-85 

10-20-85 

12-08-85 

01-13-86 

01-25-86

44,000-46,000 X X 

19,000-23,000 X XXX 

7,000-13,000 X XXX 

6,000 X 

N.A. X 

18,000-26,000 X XXX

X 

X

X
54 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE I. Summary of study sites and types of data collected Continued

River 

mile

Site 

number

Date and 

time of 

study

Discharge, 

in cubic feet 

per second

Bathymetric Topographic 

survey survey

Photographic 

replications

Surfaceflow 

pattern

Watersurface Scour Sedimentology 

slope chains

TheCutbank

122.3 32 06-06-85 

08-14-85

40,000-42,000 

19,000-23,000 ...

X 

X ...

x

Forster Rapid

122.6 33 06-06-85 

08-14-85

40,000-12,000 

19,000-23,000

...

X ...

x

Enfilade Point (initial survey, Ferrari, 1987)

123.5 34 06-06-85 

08-14-85 

10-20-85 

01-27-86

40,000-42,000 

19,000-23,000 

7,000-13,000 

23,000-26,000 X

X 

X 

X 

X

X 

X 

X 

X

...

Stone Creek

131.8 35 06-08-85 

08-15-85 

10-20-85

30,000-35,000 

20,000-24,000

N.A.

... X 

X 

X

...

...

Opposite Deer Creek Falls

136.2 36 08-15-85 20,000-24,000 ... X ... ...

(DSS) National Rapid (original survey)

166.5 37 04-25-85 

06-09 to 06-11-85 

08-15-85 

09-09-85 (1010) 

09-10-85 (1000) 

10-21 to 10-22-85 

12-08-85 

01-08-86 

01-27-86(1255) 

01-28-86(1615)

16,800-20,800 

30,000 

20,000-24,000 

22,200 

21,200 

8,000-17,000 

6,000 

N.A. 

21,100 

23,100

X(3) 

X 

X 

X 

X 

X 

X 

X 

X 

X(2) X

X 

X

X 

X

X 

X 

X

X 

X

x

X X

x

(DSS) Fern Glen Rapid (Ferrari, 1987)

168.0 38 01-08-86 

01-30-86

N.A. 

16,000-23,000

X 

X ... X X X

One Hundred Eighty-Six Mile

185.8 39 04-27-85 (1410) 

06-12-85 

09-11-85 (1040) 

09-12-85 (0825) 

01-29-86(1545)

22,300 

30,000 

26,000 

26,000 

19,400

X

X 

X 

X

...

X x

(DSS) Pumpkin Springs (original survey)

212.9 40 04-29-85 (0835) 

06-13-85 

08-16-85 

09-13-85 (0915) 

10-23-85 

01-30-86(1545) 

01-31-86 (0915)

26,200 

30,000-35,000 

20,000-22,000 

25,200 

7,000-16,000 

25,900 

21,400

X 

X 

X 

X 

X 

X 

X X

X 

X

X 

X

X 

X

X 

X

X X 

X X

X X

Diamond Creek

225.2 41 09-14-85 (1100) 

02-02-86 (1005)

25,000 

23,700

X 

X

... ... ...
TABLES 1-14 55

TABLE 2. Characteristics of the reaches within the study area

Reach 

(river 

miles)

0-11.3

11.0-22.5

22.6-35.9

40.0-61.5

61.6-77.4

77.5-117.8

117.9-125.5

125.6-139.9

140-159.9

1£A O1 O Q 1OO Zlo.o

Local name 

of reach

Permian 

section

Supai Gorge

Redwall Gorge

Lower Marble 

Canyon

Furnace Flats

Upper Granite 

Gorge

Aisles

Middle Granite 

Gorge

Muav Gorge 

Lower Canyon

Lower Granite

Gorge

Major geologic 

units at river level

Kaibab Limestone 

Toroweap Formation 

Coconino Sandstone 

Hermit Shale

Supai Group

Redwall Limestone

Muav Limestone 

Bright Angel Shale 

Tapeats Sandstone

Tapeats Sandstone 

Unkar Group

Zoroaster Plutonic 

Complex 

Trinity and Elves 

Chasm Gneisses 

Vishnu Schist

Tapeats Sandstone 

Vishnu Schist

Tapeats Sandstone 

Unkar Group 

Vishnu Schist

Muav Limestone

ttaealf JOaocLlif

Muav Limestone 

Bright Angel Shale

Vishnu Schist

Description 

of reach 

width

Wide

Narrow

Narrow

Wide

Wide

Narrow

Narrow

Narrow

Narrow 

Wide

^J arrow

Average 

ratio of 

top width 

to mean 

depth2

11.7

7.7

9.0

19.1

26.6

7

11

8.2

7.9

Q i O.I

Average 

channel 

width, 

in feet2

280

210

220

350

390

190

230

210

180

OlU Q1A

240

Type of 

alluvial 

Number of sand deposit 

Channel campsites typically vised 

slope per mile as campsites

0.00099 0.4 Separation

.0014 .9 Separation

.0015 .9 Separation

.0010 2.6 Separation; 

reattachment

.0021 2.5 Channel margin

.0023 .6 Separation; 

channel margin

.0017 3.9 Reattachment; 

channel margin; 

separation

.0020 2.3 Channel margin

.0012 1.1 Channel margin 

0013 24 *

Modified from Grand Canyon Natural History Association, 1976.

2At 24,000 ft3/s, average based on cross-section data firom Handle and Pemberton (1987); cross sections at about 1-mfle intervals.

3Based on predicted water-surface elevations at 24,000 ft3/s (Randle and Pemberton, 1987).

4Campsit 8 inventoried by Brian and Thomas (1984).
TABLE 3. Channel geometry and hydraulic characteristics for selected sites 

[Dashes indicate no data]

Water-surface slope

Site number and name

1 Above Cathedral Wash 

2 Badger Creek Rapid 

3 Soap Creek Rapid 

4 Below Salt Water Wash 

5 Eighteen Mile Wash 

7 Opposite Nineteen Mile 

Canyon 

8 Twenty Mile Camp 

9 Twenty-Nine Mile Rapid 

10 Nautiloid Canyon 

12 Eminence Break Camp 

13 Saddle Canyon 

19 Above Grapevine Rapid 

21 Ninety-One Mile Creek 

23 Granite Rapid 

25 Boucher Rapid 

28 One Hundred Twenty 

Mile Camp 

29 Lower Blacktail Rapid 

31 One Hundred TwentyTwo Mile Creek 

37 National Rapid 

38 Fern Glen Rapid 

40 Pumpkin Springs

River 

mile

2.5 

7.9 

11.4 

12.2 

18.1

19.0 

19.8 

29.2 

34.7 

44.2 

47.2 

81.1 

91.0 

93.4 

96.6

119.7 

120.1

122.0 

166.5 

168.0 

212.9

1923 1

0.0008 

.0162 

.0096 

.0021 

.0009

.0004 

.0001 

.0106 

.0074 

.0012 

.0007 

.0009 

.0009 

.0082 

.0092

.0006 

.0108

.0007 

.0066 

.0088 

.0008

1985-862

0.0003 

.0200 

.0286

.0037

.0004 

.0183 

.0011 

.0011 

.0007

.0017

.0012

.0023 

.0062

o

Discharge, 

in cubic feet 

per second

16,400 

26,500 

26,700

27,900

4,500 

5,000 

3,300 

3,620 

22,800

21,000

5,000

5,000 

29,700

o

Constriction ratio

40,000 

cubic 

feet per 

second

0.58 

.65 

.71 

.55 

.93

1.00 

.84 

.78 

.71 

.58 

.54 

.71

1.00

.78 

.74

.70 

1.00 

.93 

.69

25,000

cubic 

feet per 

second

0.57 

.63 

.59 

.48 

.70

.79 

.81 

.79 

.52 

.48 

.39 

.68

.71 

.64

.79 

.58

.55 

.70 

.66 

.52

5,000 

cubic 

feet per 

second

0.44 

.49 

.43 

.35 

.45

.63 

.58 

.51 

.18 

.42 

.36 

.53 

.70 

.45 

.81

.85 

.53

.47 

.40 

.47 

.33

Chann

constr

40,000 

cubic 

feet per 

second

290 

210 

260 

160 

300

290 

230 

200 

220 

275 

220 

170

290

190 

270

270 

310 

330 

250
TABLE 3. Channel geometry and hydraulic characteristics for selected sites Continued

Expansion ratio4

Site number and name

1 Above Cathedral Wash

2 Badger Creek Rapid

3 Soap Creek Rapid

4 Below Salt Water Wash

5 Eighteen Mile Wash

7 Opposite Nineteen Mile

Canyon

8 Twenty Mile Camp

9 Twenty-Nine Mile Rapid

10 Nautiloid Canyon

12 Eminence Break Camp

13 Saddle Canyon

19 Above Grapevine Rapid

21 Ninety-One Mile Creek

23 Granite Rapid

25 Boucher Rapid

28 One Hundred Twenty

Mile Camp

29 Lower Blacktail Rapid

31 One Hundred TwentyTwo Mile Creek

37 National Rapid

38 Fern Glen Rapid

40 Pumpkin Springs

River

mile

2.5

7.9

11.4

12.2

18.1

19.0

19.8

29.2

34.7

44.2

47.2

81.1

91.0

93.4

96.6

119.7

120.1

122.0

166.5

168.0

212.9

40,000

cubic

feet per

second

1.5

1.8

1.9

2.1

1.4

1.42

1.3

1.6

2.0

1.9

2.6

2.0

1.8

2.1

2.3

1.2

1.6

2.2

25,000

cubic

feet per

second

1.6

1.9

2.1

2.4

2.0

1.80

1.4

1.7

2.8

2.1

3.3

1.7

2.7

1.3

1.5

3.0

3.2

2.0

2.0

3.8

5,000

cubic

feet per

second

1.8

2.1

2.1

2.9

3.9

2.3

1.9

2.7

8.6

2.4

1.9

2.1

1.9

4.9

1.4

1.5

2.6

2.3

2.7

3.6

6.1

Channel depth, in feet, 

along thalweg at discharge 

of -28,000 cubic feet per second5

Upstream

from rapid

17

25

32

18

49

33

60

31

20

30

18

30

30

32

32

35

20

49

23

20

30

Constriction

15

8

12

16

22

33

28

14

16

17

12

12

15

12

11

25

14

12

12

14

22

Expansion

49

21

32

60

60

69

50

45

62

44

55

60

49

44

48

27

60

46

35

44

85

Fan

shape

ratio6

4.90

8.70

9.80

4.10

3.80

3.20

4.90

3.50

2.70

4.00

2.80

5.00

4.13

3.64

7.17

10.00

3.60

3.68

6.40

4.83

4.14

Divergenc

40,000

cubic

feet per

second

65

29

12

36

100

...

33

29

29

49

78

56

...

1

...

22

84

90

13

43

36

1Birdaeye(1923).

2Steepest survey measured in 1985-1986, at indicated discharge.

"*Average channel width at constriction divided by average channel width upstream.

^Average channel width in expansion divided by average channel width in constriction.

''Depth upstream, in constriction, and in expansion along approximate thalweg at -28,000 cubic feet per second (Wilson, 1986).

6Distance along debris fan parallel to channel at low flow divided by distance perpendicular to channel.

^Angle between main-channel flow and channel banks in degrees at expansion for two discharges.
58 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE 4. Detailed study sites in relation to reaches

Types of deposits

Reach segment Separation Reattachment Channel-margin

Permian section 

Supai Gorge

Redwall Gorge 

Lower Marble Canyon 

Upper Granite Gorge

Aisles

Lower Canyon

Badger Creek Rapid

Soap Creek Rapid 

Below Salt Water Wash 

Eighteen Mile Wash 

Twenty Mile Camp

Twenty-Nine Mile Rapid 

Nautiloid Canyon

Eminence Break Camp

Ninety-One Mile Creek 

Granite Rapid 

Boucher Rapid

National Rapid 

Fern Glen Rapid

Opposite Nineteen Mile 

Canyon

Nautiloid Canyon

Eminence Break Camp 

Saddle Canyon

Lower Blacktail Rapid 

One Hundred TwentyTwo Mile Creek

National Rapid

Above Grapevine Rapid

One Hundred Twenty 

Mile Camp

Pumpkin Springs

TABLE 5. Particle-size characteristics of alluvial sand deposits between Lees Ferry at river mile 0 and Bright Angel Creek at river mile

87.5

[mm, millimeter; <t>, -Iog2 (millimeter)]

River 

mile

0.0

0.0

0.0

2.0

2.0

5.7

11.4

11.4

18.1

18.1

19.0

31.5

32.0

47.2

47.2

47.2

47.3

47.3

47.3

47.3

47.3

47.3

47.3

47.3

47.3

Sample 

number

JCS-03

JCS-01

JCS-02

JBG-06

JBG-07

JBG-08

JBG-09

JBG-10

JCS-85-01

JC&85-02

JCS-04

JBG-13

JBG-15

JCS-13

JCS-14

JCS-15

JBG-16

JBG-17

JBG-18

JCS-05

JCS-06

JCS-07

JC&08

JC&09

JCS-10

Time of 

deposition

Pre-dam

1983

1983

Pre-dam

Pre-dam

1983

Pre-dam

Pre-dam

1985

1985

1984

1983

1983

Pre-dam

1983

1984

Pre-dam

1983

1983

1984

1984

1984

1984

1984

1983

Deposit 

type

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Separation

Separation

Separation

Separation

Separation

Reattachment

Separation

Channel margin

Separation

Separation

Separation

Reattachment

Reattachment

Reattachment

Reattachment

Reattachment

Reattachment

Reattachment

Reattachment

Reattachment

Graphic 

mean 

size 

(mm)

0.041

.14

.14

.072

.041

23

.14

.16

.12

.17

3d

27

23

.12

.13

.10

.074

28

23

.15

29

27

27

29

.19

Graphic 

standard 

deviation 

(4>)

1.7

.6

J5

&

3

J5

JS

.7

J5

&

A

A5

£

.58

J5

5

as

A

.48

.6

.4

.4

.4

.36

£9

Description

Poorly sorted silt

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately sorted very fine sand

Moderately sorted silt

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately well sorted very fine sand

Moderately sorted fine sand

Well-sorted medium sand

Well-sorted medium sand

Moderately well sorted fine sand

Moderately well sorted very fine sand

Well-sorted fine sand

Well-sorted very fine sand

Moderately sorted very fine sand

Well-sorted medium sand

Well-sorted fine sand

Moderately well sorted fine sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Moderately sorted fine sand
TABLES 1-14 59

TABLE 5. Particle-size characteristics of alluvial sand deposits between Lees Ferry at river mile 0 and Bright Angel Creek at river mile

87.5 Continued

River 

mile

47.3

47.3

52.3

53.0

53.2

56.0

56.0

56.3

56.3

56.3

56.3

56.3

60.6

60.6

60.6

61.1

61.1

61.1

61.1

61.7

61.7

62.5

65.5

71.3

71.3

71.3

71.3

71.3

71.3

71.3

71.3

71.3

71.3

71.3

72.9

75.6

75.6

81.1

81.1

81.1

81.1

81.1

Sample 

number

JCS-11

JCS-12

JBG-21

JCS-16

JCS-17

JBG-23

JBG-24

JCS-85-03

JCS-85-04

JCS-85-05

JCS-85-10

JCS-85-11

JCS-85-12

JCS-85-13

JCS-85-14

JCS-18

JCS-19

JCS-20

JBG-25

JCS-21

JCS-22

JBG-26

JBG-29

JBG-31

JBG-32

JBG-34

JBG-35

JBG-36

JCS-23

JCS-24

JCS-25

JCS-26

JCS-27

JCS-28

JBG-37

JBG-38

JBG-39

JCS-29

JCS-30

JBG-40

JBG41

JBG-42

Time of 

deposition

1983

Pre-dam

1983

1984

1984

1983

1983

1985

1985

1985

1985

1985

1985

1985

1985

1983

1983

1983

1983

1984

1983

1983

1983

1983

Pre-dam

1983

1983

Pre-dam

1983

Pre-dam

Pre-dam

1983

1983

1983

1983

1983

1983

1983

1983

1983

1983

1983

Deposit 

type

Reattachment

Reattachment

Channel margin

Channel bar

Channel margin

Separation

Separation

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Recirculation

zone bedload

Channel margin

Channel margin

Channel margin

Channel margin

Separation

Separation

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Separation

Separation

Channel margin

Channel margin

Channel margin

Channel margin

Channel margin

Graphic 

mean 

size 

(mm)

0.15

.13

.22

33

.17

50

50

29

29

29

27

27

.33

33

.32

.15

2Q

.18

.18

.19

.15

27

.10

.15

.035

.095

.13

.095

.14

.10

.09

.13

.19

.17

.15

.12

.10

29

.13

23

.15

.13

Graphic 

standard 

deviation <*>

0.5

.48

.44

.47

.50

27

.5

.47

.41

.45

.43

.38

.38

.38

.4

.52

.51

.55

.50

.57

.49

.42

&

J5

1.5

.6

.47

.5

J5

JS8

JS8

.45

J5

A

J5

.5

.6

.5

.6

.9

.6

.6

Description

Well-sorted fine sand

Well-sorted fine sand and very fine sand

Well-sorted fine sand

Well-sorted medium sand

Well-sorted fine sand

Very well sorted fine sand

Well-sorted fine sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Well-sorted medium sand

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately well sorted fine sand

Well-sorted fine sand

Moderately well sorted fine sand

Well-sorted fine sand

Well-sorted fine sand

Moderately sorted very fine sand

Well-sorted fine sand

Poorly sorted silt

Moderately well sorted very fine sand

Well-sorted very fine sand

Well-sorted very fine sand

Well-sorted fine sand

Moderately well sorted very fine sand

Moderately well sorted very fine sand

Well-sorted fine sand

Well-sorted fine sand

Well-sorted fine sand

Well-sorted fine sand

Well-sorted very fine sand

Moderately well sorted very fine sand

Moderately well sorted medium sand

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately well sorted fine sand

Moderately well sorted fine sand

1Ba8ed on Wentworth size classes and sorting classification (Folk, 1968, p.46).
60 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE 6. Summary statistics of particle-size characteristics

Time 

of 

deposition

Deposit 

type

Pre-dam Separation 

Post 1983 Separation 

Pre-dam Reattachment 

Post 1983 Reattachment 

Pre-dam Channel margin 

Post 1983 Channel margin 

1985 Recirculation zone bedload

Number 

of 

samples

3 

12 

2 

10 

7 

24 

8

Mean 

graphic 

means 

value, in 

millimeters

0.140 

.165 

.102 

.251 

.068 

.169 

.299

Standard 

deviation 

of graphic 

means, in 

millimeters

0.020 

.054 

.040 

.073 

.028 

.050 

.025

Ninety-five 

percent 

confidence 

interval, in 

millimeters

0.117-0.162 

.134-.196 

.047-.157 

.206-.296 

.057-.079 

.149-.189 

.282-.316

Small sample sizes restrict statistical significance of data in some categories. Statistics are reported for descriptive purposes.

TABLE 7. Areas of alluvial sand deposits at low discharge in selected reaches, October 1984 

[All deposit values are in thousands of square feet]

Reach 

segment

0-11.3

11.4-22.5

22.6-35.9

40.9-61.5

117.9-125.5

125.6-139.9

140-159.9

Description 

of reach

width

Wide

Narrow

Narrow

Wide

Narrow

Narrow

Narrow

Total

410

510

540

4,700

920

900

240

Average

51

23

25

60

25

22

8.2

Area

per

mile

36

46

41

180

120

63

12

Sepsration

Total

230

390

290

1^00

130

240

100

Average

57

30

21

49

26

17

14.5

Reattachment

Total

93

96

190

1,900

350

140

2.3

Average

31

16

47

87

35

34

2.3

Area by type of deposit

Channel margin

Total

0

0

0

1,300

330

410

130

Average

0

0

0

73

22

20

7.5

Point bar

Total

92

0

0

37

0

0

0

Average

92

0

0

37

0

0

0

Upper pool

Total Average

0

23

54

270

0

97

5.7

0

7.6

IS

21

0

32

5.7
TABLE 8. Summary of changes between bathymetric surveys

[Aggradation and degradation were computed as the difference in area between profile lines for successive surveys. Average vertical change was computed by d

change along profile lines by the length of the line. Dashes, no data]

April-September 1985

Profile Aggradation, 

in square feet

Degradation, 

in square feet

Net change 

in area, 

in square feet

Average vertical 

change in upper 

surface of deposit, Aggradation, 

in feet in square feet

September 1985-January 1986

Degradation, 

in square feet

Net change 

in area, 

in square feet

Upp

of 

i

Eminence Break Camp

1

2

3

4

5

6

7

8

9

10

11

12

13

164

41

197

37

4

142

62

0

0

0

0

14

15

0

2

0

418

386

401

202

246

421

282

132

270

305

+164

+39

+197

-381

-382

-259

-140

-246

-421

-282

-132

-256

-290

+2.6

+0.6

-1.7

-2.9

-3.1

-1.6

-0.9

-1.6

-2.6

-1.8

-1.1

-1.9

-4.2

0

0

11

142

100

96

99

113

102

0

0

54

169

341

235

260

67

45

321

101

122

112

276

78

68

6

-341

-235

-249

+75

+55

-225

-2

-9

-10

-276

-78

-14

+163

Lower Blacktail Rapid

1

2

3

4

5

6

7

8

....

 

....

 

 

 

....

....

_

....

....

...£

....

....

....

0

537

444

721

574

173

428

83

186

8

105

223

220

228

125

0

-186

+529

+339

+498

+354

-55

+303

+83

National Rapid

1

2

3

4

5

6

268

230

189

103

13

76

37

10

36

69

9

0

+231

+220

+153

+34

+4

+76

+1.4

+1.6

+0.9

+0.3

0

+1.1

116

0

66

0

16

0

414

219

95

122

29

66

-298

-219

-29

-122

-13

-66
62 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE 9. Number of separation and reattachment deposits in recirculation zones between river miles 0 and 118,1973 and

1984

Reach 

segment

0-11.3 

11.4-22.5 

22.6-35.9 

40-61.5 

61.6-77.4 

77.5-117.8 

Total

Total number Width 

of recirculation of 

zones surveyed reach

33 Wide 

40 Narrow 

60 Narrow 

115 Wide 

37 Wide 

111 Narrow

399

Deposit type

Bias 

of Reattachment Separation

analysis 

1973

Decrease 31 

Decrease 27 

No bias 37.5 

Increase 96.5 

Increase 28 

Increase 78.5

298.5

1984 1973

28 18.5 

20.5 26 

34 38.5 

100.5 49.5 

32 23.5 

68.5 28.5

283.5 184.5

1984

19.5 

26 

29.5 

50 

25 

27.5

177.5

^Change in number of deposits from 1973 to 1984 caused by difference in stage.

TABLE 10. Areas of major alluvial sand deposits in selected reaches, 1973 and 1984 

[Values are in thousands of square feet]

Types of deposits

Reach

1973

0-11.3 460-610 

11.4-22.5 540-670 

22.6-35.9 480-620 

122-125.5 300-380 

125.6-139.9 840-920 

140-150 128-150

Total Separation

1984 Change 1973

370^50 (*) 210-270 

460-560 (2) 350-430 

490^590 (2) 280-360

810-990 (2) 200-220 

120-150 (2) 73-86

1984 Change 1973

210-250 (2) 100-130 

350-430 (2) 170-200 

260-320 (2) 150-200

CT C*7

220-260 (2) 120-130 

55-67 f 1) 0

Reattachment

1984 Change

84-100 (2) 

86-110 (!) 

170-210 (2) 

59-72 (2) 

130-150 (2) 

2

Channel margin

1973 1984 Change

112-140 140-180 (2) 

410-440 370-450 (2) 

50-59 64-78 (2)

Erosion.

o

No change.
Reach 

segment

TABLES 1-14

TABLE 11. Number of deposits that underwent change, 1973-84

Types of deposits

Separation Reattachment Channel margin Upper pool

0-11.3

11.4-22.5

22.5-35.9

122-125.5

125.6-139.9

140-150

Total

Percent

Gain

1

4

2

1

6

0

14

23

Loss

0

3

6

1

3

2

15

30

No 

change

3

6

6

0

5

1

21

42

Gain

2

0

1

2

2

1

8

33

Loss

2

6

1

0

2

0

11

46

No 

change

1

1

2

1

0

0

5

21

Gain

0

0

0

7

7

7

21

55

Loss

0

0

0

2

9

0

11

29

No 

change

0

0

0

0

4

2

6

16

Gain

0

0

0

1

0

0

1

9

Loss

0

2

1

0

1

0

4

36

No 

change

0

1

2

1

2

0

6

55

TABLE 12. Classification of deposits studied by Howard (1975) and Beus and others (1985)

[Study site names are those of Beus and others (1985). River mile in brackets is river mile used in appendix A of this report. L, left side of river; R, right

side of river]

Types of deposits and river-mile position

Separation Reattachment Channel margin Upper pool

Eighteen Mile Wash

Nautiloid Canyon

(34.7) [34.7L] 

Below Little Colorado

River confluence

(61.8) [61.7R] 

Tanner Mine

(65.5) [65.6L] 

Unkar Indian Village

(72.2) [72.5R] 

Bedrock Rapids

Nineteen Mile Wash^

(19.3) [19.0L] 

One Hundred Ninety Mile

(190.2)

Nineteen Mile Wash*

(19.3) [19.0L] 

Lower Nankoweap

(53)[53.2R] 

Grapevine

(81.1) [81.1L] 

One Hundred Nine Mile

(109.4) 

Walthenberg Canyon

(112.2) 

Upper 124.5 Mile Canyon

(124.3) 

The Ledges

(151.6) [151.6R] 

National Canyon

(165.5) [166.4L] 

Lower Lava (180.9) 

Granite Park (208.8)

Upper Granite Rapid

(93.2)[93.1L] 

Blacktail Canyon

(120.1) [120.0R]

^Nineteen Mile Wash had one profile line across reattachment deposit and one profile line across channel-margin deposit
64 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA 

TABLE 13. Summary of measured changes at 20 sites during fluctuating flow, October 1985 to mid-January 1986

River 

mile

Deposit 

type

Date

Length 

of Average 

Profile section, vertical 

in feet change

Description

Above Cathedral Wash

2.5 Reattachment 10-04-85 

to 

01-09-86

1 57 +0.6 

2 45 -0.1

Profile 1 across crest; profile 

downstream of reattachment

2 

point

Badger Creek Rapid

79 Separation 10X)535 

to 

01-11-86

1 54 +0.1 

2 85 -0.7 

3 90 +2.0

Figure 5

Soap Creek Rapid

11.4 Separation 09-21-85 

to 

01-1256

1 87 -0.1 

2 83 -0.3 

3 53 -0.6 

4 35 -0.7 

5 39 -0.7 

6 37 -0.3

Separation point migrates 

downstream through 

all cross sections

Below Salt Water Wash

122 Separation 10-0835 

to 

01-1336

1 16 +0.4 

2 57 -0.2 

3 45 +0.1

Low-velocity area

Eighteen Mile Wash

18.1 Separation 1(W)935 

to 

01-1336

1 20 -0.0 

2 90 -22 

3 10 -2.72

Figure 12

Opposite Nineteen Mile Canyon

19.0 Reattachment 10-10-85 

to 

01-14-86

1 57 -0.3 

2 30 -0.3

Profile 1 across bar crest; profile 

2 downstream from reattachment 

point

Twenty Mile Camp

193 Separation 10-11-85 

to 

01-1436

1 17 -0.5 About 120 feet downstream from 

separation point

Twenty-Nine Mile Rapid

292 Separation 10-11-85 

to 

01-1536

1 43 -0.1 

2 42 -28 

3 47 -3.5

Figure 34

Nautiloid Canyon

34.7 Separation 10-1235 

to 

01-1436

1 9 -0.6 

2 17 +0.2 

3 20 +0.6 

4 20 -L2

Profiles located progressively 

farther downstream

Eminence Break Camp

442 Separation 10-1285 

to 

01-1636

1 18 -0.1 

2 TO +0.0 

3 29 -LO

Figure 14
TABLES 1-14 65

TABLE 13. Summary of measured changes at 20 sites during fluctuating flow, October 1985 to mid-January 1986-

Continued

River 

mile

Deposit Date 

type

Length 

of Average 

Profile section vertical 

in feet1 change2

Description

Saddle Canyon3

472 Reattachment 09-24-85 

to 

01-1&S6

1 60 -02 

2 89 -0.1 

3 68 -02 

4 20 -L2 

5 25 -L2 

6 16 -L4

Figure 17

Above Grapevine Rapid3

8L1 Channel 10-15-85 

to 

01-21-86

1 21 -LO 

2 22 -LI

Profile 1 between separation and 

reattachment points; profile 2 near 

reattachment point

Ninety-One Mile Creek3

9LO Separation 10-15-85 

to 

01-2286

1 15 -L3 

2 3 -LI

Profile 1 near separation point; 

profile 2 primary-eddy current

National Rapid

166.5 Separation 10-21-85 

to 

01-08S6

1 66 -0.4 

2 32 +0.3 

3 - 0.0

Figure 30

Fern Glen Rapid

168.0 Separation 10-01-85 

to 

01-0&86 

USER

1 3 +O.7 

2 15 +2.8 

3 72 +1.7 

4 - -0.0 

5 10 -05

Profiles located progressively 

farther downstream

Pumpkin Springs3

212.9 Channel margin; 10-23-85 

reattachment to 

01-31-86

1 18 -72 

2 25 -L8

Profile 1 near reattachment point; 

profile 2 downstream from 

reattachment point

Length of section is that portion of cross section over which survey comparisons could be made and which were 

both affected by fluctuating flows; actual cross sections are longer.

Average vertical change equals cross-section area divided by horizontal length of cross section.

Surveys in January 1986 after conclusion of special fluctuating-flow study period; some change may be due to 

resumption of higher flows beginning January 17, 1986.
66 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA

TABLE 14. Areas of exposed sand at detailed study sites, 1965, 1973, and 1984 

[Area is in thousands of square feet]

Area of exposed sand

Site2 Deposit3

2.5L

7.9L

11.4R

12.2L

18. 1L

19.0L

19.8L

29.2L

34.7L

44.2L

93.4L

96.6L

168.0R

R

S

R

S

S

S

R

S

S

S

R

S

R

S

S

S

R

Site name

Above Cathedral Wash

Badger Creek Rapid

Badger Creek Rapid

Soap Creek Rapid

Below Salt Water Wash

Eighteen Mile Wash

Opposite Nineteen Mile Canyon

Twenty Mile Camp

Twenty-Nine Mile Rapid

Nautiloid Canyon

Nautiloid Canyon

Eminence Break Camp

Eminence Break Camp

Granite Rapid

Boucher Rapid

Fern Glen Rapid

Fern Glen Rapid

1965

35

43

7.9

85

17

11

29

21

23

34

0

62

17

5

22

97

5.0

High 

elevation

1973

IS

35

0

86

10

4.0

16

20

19

30

0

81

13

0

23

54

0

Low 

elevation

1984

17

29

0

90

17

6.9

14

21

25

18

0

76

3.5

6.1

27

70

0

1973

64

42

17

110

31

15

57

33

51

41

32

100

63

NA

NA

95

19

1984

59

55

0

99

35

15

25

30

53

33

66

92

43

NA

NA

100

12

Change 1

High 

elevation

1965-73

.

-

-

NC

-

-

-

NC

-

-

NC

+

-

-

NC

-

-

1973-84

NC

-

NC

NC

+

+

NC

NC

+

+

NC

NC

-

+

+

+

NC

Low 

elevation

1973-85

NC

+

-

NC

-

NC

-

NC

NC

-

+

NC

-

NA

NA

NC

-

NC, no change; minus sign, loss of area; plus sign, gain in area; NA, not applicable. 

River mile. L, left side of river; R, right side of river. 

R, reattachment; S, separation.

Area exposed at discharge of about 25,000 cubic feet per second. 

5Area exposed at discharge of about 6,000 cubic feet per second.
APPENDIX A

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek

River mile 

inventory Side

1 °f 

1923 * river

0.0 

1.9 

2.5 

2.7 

5.7 

7.9 

7.9 

10.3 

11.4 

12.0 

12.2 

16.5 

17.0 

18.1 

18.9 

19.0

19.8 

20.2 

20.3

20.4 

21.3 

21.6 

21.7 

22.5 

22.7

23.4 

24.5 

24.8 

25.0

26.2 

26.4 

26.7 

28.7 

28.9

29.2 

30.3

30.4 

31.5 

33.5 

33.7 

34.7 

35.1 

36.0 

37.2 

37.3 

37.6 

38.0

Left 

Left 

Right 

Right 

Right 

Left 

Left 

Right 

Left 

Left 

Left 

Right 

Left 

Right 

Left

Left 

Left 

Right

Right 

Left 

Left 

Right 

Left 

Right

Left 

Left 

Left 

Left

Left 

Left 

Left 

Right 

Right

Left 

Right

Right 

Right 

Left 

Left 

Left 

Left 

Left 

Right 

Left 

Left 

Left

Site

Lees Ferry 

Unnamed site 

Above Cathedral Wash 

Cathedral Wash 

Six Mile Wash 

Badger Creek Rapid 

Badger Creek Rapid 

Below Ten Mile Rock 

Soap Creek Rapid 

Salt Water Wash 

Below Salt Water Wash 

Hot Ha Ha Wash 

House Rock Rapid 

Eighteen Mile Wash 

Nineteen Mile Canyon 

Opposite Nineteen Mile 

Canyon 

Twenty Mile Camp 

Unnamed site 

Above North Canyon 

Rapid 

North Canyon Rapid 

Twenty-Two Mile Wash 

Unnamed site 

Unnamed site 

Unnamed site 

Above Indian Dick 

Rapid 

Twenty-Three and OneHalf Mile Rapid 

Above Twenty-Four and 

One-Half Mile Rapid 

Twenty-Four and OneHalf Mile Rapid 

Twenty-Five Mile Rapid

Unnamed site 

Above Tiger Wash Rapid 

Tiger Wash Rapid 

Unnamed site 

Unnamed site

Twenty-Nine Mile Rapid 

Unnamed site

Unnamed 

South Canyon 

Little Redwall Camp 

Unnamed site 

Hautiloid Canyon 

Unnamed site 

Thirty-Six Mile Rapid 

Unnamed site 

Tatahatso Wash 

Below Tatahatso Wash 

Unnamed site

Aerial 

photograph 

number

1-141 

1-144 

1-145 

1-173 

1-193 

1-193 

1-211 

1-219 

1-223 

1-226 

2-3 

2-6 

2-15 

2-21 

2-22

2-28 

2-29 

2-32

2-32

2-38 

2-40 

2-41 

2-45 

2-47

2-50 

2-57 

2-58 

2-60

2-68 

2-70 

2-72 

2-86 

2-86

2-87 

2-94

2-95 

2-102 

2-114 

2-116 

2-123 

2-132 

2-138 

2-147 

2-148 

2-150 

2-154

River mile 

inventory

1973

1.9

2.7 

5.8 

7.fl 

7.9

12.2 

16.5 

17.1 

18.2

19.3

20.0 

20.2

21.5 

21.5 

21.8 

22.3 

22.6

23.2

24.9 

26.2

26.7 

28.8 

29.0

29.2 

30.3

31.5 

33.5 

33.9 

34.7 

35.1 

36.0 

37.2 

37.3 

37.6

1983

2.0

3.0

8.0 

8.0 

10.2 

11.5 

12.0 

12.4 

16.5

18.2 

19.0 

19.2

20.0

20.5

20.5 

21.5 

21.5

22.8 

22.7

24.5 

24.7

26.5

29.3 

30.3

30.4 

31.5 

33.7 

33.8 

34.8

37.5 

38.4

Deposit 

type 3

Point bar 

Reattacbment 

Separation 

Separation 

Separation 

Separation 

Reattacbment 

Separation 

Separation 

Separation 

Separation 

Separation 

Separation 

Upper pool 

Reattacbment

Separation 

Separation 

Upper pool

Separation 

Separation 

Separation 

Reattacbment 

Separation 

Separation

Separation 

Upper pool 

Separation

Reattacbment ; 

upper pool 

Separation 

Separation 

Separation 

Separation 

Separation ; 

reattachment 

Separation 

Reattachment; 

upper pool 

Reattacbment 

Separation 

Separation 

Separation 

Separation 

Separation 

Separation 

Reattachment; 

Upper pool 

Upper pool 

Separation; 

reattachment

See footnotes at end of table.

67
68 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

River mile

inventory

1923 l

38.5

39.9

40.2

40.9

41.0

41.3

41.5

42.0

42.2

42.8

43.1

43.5

44.2

44.6

44.8

44.9

45.3

45.9

46.7

46.8

47.0

47.2

47.3

47.5

47.5

47.7

48.0

48.3

49.5

49.8

49.8

49.9

50.3

50.7

51.1

51.2

51.3

51.5

51.9

52.1

52.3

52.5

53.0

Side

of

river

Left

Left

Left

Right

Right

Right

Right

Left

Left

Left

Left

Left

Left

Left

Left

Left

Right

Left

Right

Right

Right

Right

Right

Left

Right

Left

Left

Right

Left

Left

Right

Right

Left

Left

Right

Left

Right

Left

Right

Right

Right

Right

Right

Site

Unnamed site

Unnamed site

Unnamed site

Upper Buckf arm Canyon

Lower Buckf arm Canyon

Bert Loper Canyon

Royal Arches

Unnamed site

Unnamed site

Unnamed site

Unnamed site

President Barding Rapid

Eminence Break Camp

Unnamed site

Unnamed site

Unnamed site

Above Triple Alcoves

Camp

Unnamed site

Triple Alcoves

Unnamed site

Lower Triple Alcoves

Camp

Saddle Canyon

Below Saddle Canyon

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Fifty Mile Camp

Dinosaur Camp

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Unnamed site

Little Nankoweap Creek

Unnamed site

Above Nankoweap Rapid

Nankoweap Rapid

Nankoweap Rapid

Aerial

photograph

number

2-157

2-166

2-168

2-173

2-173

2-205

2-206

2-177

2-178

2-181

2-183

2-184

2-187

2-191

2-192

2-193

2-195

2-198

2-203

2-204

2-211

2-213

2-214

2-215

2-215

2-216

2-217

2-219

2-225

2-226

2-227

2-227

2-229

2-232

2-235

2-236

2-236

2-237

3-1

3-2

3-3

3-4

3-7

River

invent

1973

38.6

39.8

40.1

40.9

41.0

41.3

41.5

41.9

42.1

43.2

43.4

44.2

44.5

44.7

45.0

45.8

46.8

Marsh

47.1

48.3

49.5

50.0

50.6

Marsh

Marsh

51.9

52.0

52.5

mile

:ory

1983

38.8

40.9

41.0

42.3

42.9

43.3

44.6

44.8

45.3

46.0

46.5

Marsh

46.6

47.2

47.3

47.5

47.8

47.8

48.0

49.7

49.9

49.9

50.0

50.2

50.6

51.0

51.5

51.4

51.8

52.3

52.5

52.7

Deposit

type 3

Channel margin;

reattachment

Separation

Channel margin;

Reattachment;

upper pool

Separation

Separation

Reattachment

Channel margin

Channel margin

Channel margin

Separation;

Separation

Separation

Separation

Reattachment;

upper pool

Separation

Channel margin;

reattachment

Upper pool

Reattachment ;

upper pool

Reattachment

Separation

Separation

Reattachment

Separation

Separation;

reattachment

Reattachment

Reattachment

Reattachment ;

upper pool

Reattachment;

upper pool

Reattachment ;

separation

Upper pool

Separation

Channel margin;

reattachment

Reattachmet

Separation

Reattachment

Reattachment

Reattachment

Reattachment;

upper pool

Separation

Channel margin

Channel margin

Channel margin;

reattachment

See footnotes at end of table.
APPENDIX A 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

69

River mile 

inventory Side 

of 

1923 l river

53.2

53.2 

53.4 

53.7

53.7 

53.8

53.8 

54.1 

54.2 

54.3

54.4 

54.5 

54.6 

54.7 

55.0

55.1 

55.3 

55.6 

56.3 

56.4 

56.5

56.8 

57.0 

57.5 

57.6 

58.2 

58.6 

58.9 

59.0 

59.5 

59.8 

60.2

60.6 

61.1

61.4 

61.7

62.3 

63.3 

64.0 

64.7 

65.4

65.6 

66.0 

66.4

Right

Left 

Right 

Left

Right 

Right

Left 

Left 

Right 

Right

Right 

Left 

Left 

Left 

Left

Left 

Left 

Right 

Right 

Right 

Right

Left 

Left 

Right 

Left 

Right 

Left 

Right 

Left 

Right 

Right 

Left

Right 

Right

Left 

Right

Right 

Right 

Left 

Right 

Right

Left 

Left 

Left

Site

Below Nankoweap Rapid

Unnamed site 

Below Nankoweap Rapid 

Unnamed site

Unnamed site 

Unnamed site

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site

Unnamed site 

Unnamed site 

Unnamed site 

Kwagunt Rapid 

Below Kwagunt Rapid 

Unnamed site

Unnamed site 

Unnamed site 

Malagosa Canyon 

Unnamed site 

Awatubi Canyon 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Sixty Mile Rapid 

Unnamed site

Unnamed site 

Unnamed site

Island Camp

Below Little Colorado 

River confluence 

Unnamed site 

Unnamed site 

Unnamed site 

Carbon Creek 

Lava Canyon Rapid

Palisades Creek 

Unnamed site 

Unnamed site

Aerial 

photo* 

graph 

number

3-9

3-9,10 

3-10 

3-12

3-12 

3-13

3-13 

3-14 

3-15 

3-16

3-17 

3-17 

3-18 

3-19 

3-21

3-21 

3-22 

3-24

3-28

3-29 

3-30 

3-33 

3-34 

3-37 

3-39 

3-40 

3-41 

3-44 

3-45 

3-48

3-51 

3-53

3-56 

3-58

3-61 

3-68 

3-71 

3-75 

3-79

3-82 

3-84 

3-86

River mile 

inventory

1973

53.0 

53.1

53.3

53.6 

53.7

53.8

54.2

54.5 

Marsh

Marsh 

Marsh

56.6 

56.8

57.4 

57.7

58.5

59.0

62.4 

63.3 

63.9 

64.5 

65.5

65.5 

66.1 

66.4

1983

53.0

53.0 

53.2 

53.4

53.4

53.8 

54.0 

54.0 

54.2

54.4 

54.6 

54.7 

55.0

55.2

55.4

56.2 

56.4 

56.5

56.8 

57.0 

57.5 

57.5 

58.2 

58.7 

58.5 

59.0 

59.5 

59.8 

60.0

60.5 

61.2

61.8 

61.9 

62.3

64.5 

65.5

65.6

66.5

Deposit 

type 3

Channel margin; 

reattachment 

Point bar 

Separation 

Channel margin; 

reattachment 

Separation 

Channel margin; 

reattachment 

Channel margin 

Separation 

Separation 

Reattachment; 

upper pool 

Reattachment 

Upper pool 

Channel margin 

Reattachment 

Upper pool;, 

reattachment 

Separation 

Reattachment 

Reattachment 

Reattachment 

Channel margin 

Channel margin; 

reattachment 

Channel margin 

Separation 

Separation 

Reattachment 

Separation 

Separation 

Upper pool 

Reattachment; 

Channel margin 

Separation 

Reattachment; 

upper pool 

Separation 

Reattachment; 

upper pool 

Separation; 

reattachment 

Separation

Upper pool 

Separation 

Reattachament 

Separation 

Reattachment; 

upper pool 

Separation 

Channel margin 

Reattachment; 

channel margin

See footnotes at end of table.
70 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

River mile 

inventory

1923 l

Side

of 

river

Site

Aerial 

photograph f 

number''

River mile 

inventory

1973 1983

Deposit 

type 3

66.8

67.3

67.7

67.8

68.0

68.2

68.6

68.7

69.3

69.4

69.8

69.9

70.2

70.3

70.5

70.9

71.3

71.4

71.7

71.9

72.1

72.5

72.6

72.7

73.1

73.4

73.7

73.7

73.9

74.0

74.2

74.3

74.3

74.7

74.7

74.9

75.0

75.6

75.8

76.5

76.6

77.2

78.8

81.1

82.6

84.0

84.4

85.7

87.1

87.2

88.0

Left Espejo Creek 3-90

Left Comanche Creek 3-92

Left Unnamed site 3-94

Right Unnamed site 3-94

Right Upper Tanner 3-96

Right Unnamed site 3-97

Left Tanner 3-101

Left Tanner 3-101

Left Below Tanner 3-111

Right Upper Basalt Rapid 3-112

Right Lower Basalt Rapid 3-113

Left Unnamed site 3-114

Left Unnamed site 3-116

Right Unnamed site 3-117

Right Unnamed site 3-117

Left Unnamed site 3-120

Left Cardenas Creek 3-121

Left Unnamed site 3-121

Left Unnamed site 3-124

Right Unnamed site 3-126

Left Unnamed site 3-128

Right Above Unkar Rapid 3-129

Right Middle Unkar Rapid 3-130

Left Unnamed site 3-132

Right Lower Unkar Rapid 3-133

Left Unnamed site 3-135

Left Unnamed site 3-137

Right Granary Camp 3-137

Right Unnamed site 3-138

Right Unnamed site 3-138

Left Unnamed site 3-140

Left Unnamed site 3-142

Right Unnamed site 3-142

Left Unnamed site 3-144

Right Unnamed site 3-144

Left Escalante Creek 3-145

Right Unnamed site 3-145

Left Nevills Rapid 3-148

Right Opposite Papago Creek 3-152

Right Unnamed site 3-156

Left Above Hance Rapid 3-156

Left Unnamed site 3-161

Left Sockdolager Rapid 3-168

Left Above Grapevine Rapid 3-181

Right Eighty-Two and One- 3-189

	Half Mile 

Right Clear Creek 3-197

Left Above Zoroaster Rapid 3-201

Left Cremation Creek 3-207

Left Cremation Camp 3-215

Right Roys Beach Camp 3-216

Left Unnamed site 3-220

66.9 66.8 Channel margin;

	separation

67.3 Channel margin

67.7 Channel margin

 67.8 Channel margin

68.0 68.0 Point bar

68.1 68.2 Point bar

68.7 68.6 Channel margin

68.8 Point bar

69.5 69.0 Point bar

69.5 69.6 Channel margin

 69.8 Channel margin

69.9 Channel margin

70.2 Channel margin

 70.3 Channel margin

 70.5 Channel margin 

Marsh Channel margin; 

	reattachment

 71.3 Separation

Marsh Reattachment

 71.7 Channel margin

 Separation

72.1 72.1 Point bar

 72.5 Channel margin

 72.6 Channel margin

 72.7 Channel margin

 73.1 Channel margin

73.4 73.3 Channel margin

73.7 Channel margin

 73.7 Channel margin

73.9 Channel margin

74.0 Separation

74.2 Channel margin

74.3 74.4 Channel margin

74.3 Separation

74.7 74.7 Channel margin

 74.6 Channel margin

74.9 74.8 Upper pool

 75.0 Channel margin

75.5 75.5 Separation

 75.8 Reattachment

76.4 Channel margin

76.5 76.4 Reattachment;

	upper pool

77.1 Channel margin

78.8 Upper pool

81.1 81.3 Channel margin;

	reattachment 

82.6 Channel margin

84.0 Separation;

	reattachment

84.4 Separation

85.7 Channel margin

87.1 87.1 Separation

 87.1 Channel margin

88.0 Channel margin

See footnotes at end of table.
APPENDIX A 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

71

River mile

inventory

1923 x

89.3

90.9

91.0

91.4

92.2

93.1

93.4

94.2

94.2

94.9

95.8

96.0

96.6

98.0

98.2

99.0

99.1

99.5

102.7

103.1

105.6

106.8

107.0

107.3

107.4

107.6

107.8

108.1

112.6

114.0

114.4

114.6

115.6

115.7

115.8

117.0

117.3

117.7

118.0

118.3

118.5

118.7

118.9

119.1

119.2

Side

of

river

Right

Left

Right

Right

Left

Left

Left

Left

Right

Left

Left

Left

Left

Right

Right

Left

Right

Left

Right

Right

Right

Right

Right

Left

Right

Right

Right

Right

Right

Right

Right

Right

Left

Right

Right

Left

Left

Left

Right

Right

Left

Right

Left

Right

Left

Site

Aerial

photograph

number

Below Pipe Springs Rapid 3-228

Unnamed site

Ninety-One Mile Creek

Trinity Creek

Unnamed site

Upper Granite Rapid

Granite Rapid

Unnamed site

Ninety-Four Mile Creek

Hermit Rapid

Old Dune Camp

Ninety-Six Mile Camp

Boucher Rapid

Upper Crystal Rapid

Crystal Rapid

Tuna Creek Above Rapid

Tuna Creek Rapid

Unnamed site

Below Turquoise Rapid

Shady Grove; One

Hundred-Three Mile

One Hundred-Four

Mile Rapid

One Hundred-Five and

One-Half Mile

One Hundred-Seven

Mile

Above Bass Rapid

Bass Canyon

Bass Rapid

Unnamed site

Lower Bass Camp

Shinumo Rapid

Unnamed site

Unnamed site

Upper Garnet Canyon

Lower Garnet Camp

Royal Arch Trail Camp

Unnamed site

Monument Fold Camp

Below Elves Chasm

Unnamed site

Stephen Aisle

Unnamed site

Unnamed site

Apache Terrace

Unnamed site

Unnamed site

One Hundred Nineteen

Mile Camp

Unnamed site

3-239

2-240

3-242

3-246

4-7

4-7

4-12

4-12

4-15

4-22

4-23

4-27

4-36

4-37

4-41

4-42

4-43

4-67

4-68

-73

4-83

4-93

4-95

4-96

4-97

4-99

4-101

4-103

4-132

4-141

4-144

4-145

4-153

4-154

4-155

4-161

4-163

4-165

4-167

4-169

4-170

4-171

4-172

4-173

4-174

River mile

inventory

1973

89.3

91.1

91.2

91.5

92.2

93.2

93.3

93.9

95.8

95.9

96.5

99.1

99.1

99.5

102.9

103.1

103.8

105.6

106.8

107.5

107.7

107.9

108.2

108.3

112.5

114.3

114.5

115.4

115.7

117.0

117.4

117.7

118.5

118.7

118.8

119.2

119.2

1983

89.5

90.8

91.2

92.1

93.4

93.6

94.3

94.7

95.6

96.7

98.1

98.3

103.8

107.7

108.0

108.2

108.6

114.0

114.5

115.4

115.5

115.6

116.8

117.2

118.1

118.6

188.6

118.8

119.0

119.1

Deposit

type 3

Channel margin

Separation

Separation

Separation

Channel margin

Reatt achment ;

upper pool

Separation

Separation

Separation

Upper pool

Channel margin;

reattachment

Channel margin

Separation

Upper pool

Separation

Channel margin;

reattachment

Upper pool

Point Bar

Channel margin

Channel margin

Upper pool;

reattachment

Upper pool;

reattachment

Channel margin

Channel margin

Channel margin

Channel margin

Reattachment

Channel margin

Channel margin

Separation

Channel margin

Separation

Channel margin

Channel margin

Separation

Reattachment ;

separation

Separation

Channel margin

Channel margin

Upper pool

Reattachment

Channel margin

Reattachment

Channel margin

Reattachment

Separation

See footnotes at end of table.
72 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

River mile 

inventory

1923 *

Side

of 

river

Site

Aerial 

photograph f 

number'

River mile 

inventory

1973 1983

Deposit 

type3

119.4

119.4

119.7

119.8

120.0

120.0

120.1

120.2

120.5

121.5

121.6

121.8

122.0

122.2

122.3

122.6

122.7

122.9

123.2

123.5

123.8

124.2

124.3

124.6

125.2

125.2

125.4

125.5

126.1

126.3

127.7

131.0

131.1

131.4

131.8

132.0

133.0

133.1

133.4

133.7

133.8

133.8

134.1

134.5

Right Unnamed site 4-175

Left Unnamed site 4-175

Left One Hundred Twenty 4-176

	Mile Camp

Right Unnamed site 4-177

Left Unnamed site 4-178

Right Upper Blacktail Rapid 4-178

Right Lower Blacktail Rapid 4-178

Left Opposite Blacktail Rapid 4-179

Left Below Blacktail Rapid 4-181

Left Unnamed site 4-186

Left One Hundred-Twenty- 4-187

	Two Mile Rapid

Left Unnamed site 4-188

Right One Hundred Twenty- 4-189

	Two Mile Creek

Left Unnamed site 4-190

Left The Cutbank 4-191

Left Forster Rapid 4-192

Left Unnamed site 4-193

Left Unnamed site 4-194

Left Upper Enfilade Point 4-197

	Camp

Left Enfilade Point 4-198

Right Unnamed site 4-200

Left Unnamed site 4-202

Left Unnamed site 4-202

Left Fossil Rapid 4-205

Left Below Fossil Rapid 4-207

Right Unnamed site 4-207

Left One Hundred Twenty-Six 4-208

	Mile Camp 

Left Unnamed site 4-209

Left Unnamed site 4-213

Right Randy's Rock 4-215

Left Below bedrock 4-224

Right Above Dubby 4-244

Right Unnamed site 4-246

Right Just above Dubby 4-247

Right Stone Creek 4-249

Left Unnamed site 5-4

Left Opposite One Hundred 5-11

	Thirty-Three Mile

	Creek

Left Racetrack 5-11

Right Upper Tapeats 5-13

Right Tapeats Creek Mouth 5-14

Right Unnamed site 5-15

Right Lower Tapeats Rapid 5-15

Left Unnamed site 5-17

Left Unnamed site 5-20

 119.3 Channel margin

 119.4 Reattachment 

119.7 119.8 Channel margin; 

	reattachment

 119.8 Reattachment

119.9 Channel margin

120.1 120.0 Upper pool

 120.2 Separation

120.5 120.5 Channel margin

120.5 120.5 Separation

121.6 Upper pool

121.7 121.8 Separation

121.9 Channel margin

122.0 122.2 Reatt achment;

upper pool 

122.2 Channel margin

 122.2 Reattachment

122.7 122.6 Reattachment; 

upper pool

122.8 Channel margin

 123.0 Reattachment

 Channel margin

123.5 123.2 Separation

 124.0 Channel margin

 124.6 Channel margin 

124.4 124.8 Separation

 124.9 Channel margin 

125.2 Channel margin

 125.2 Channel margin

125.4 125.8 Channel margin; 

reattachment

125.5 125.8 Channel margin 

reattachment

126.2 126.0 Separation

126.3 126.5 Upper pool 

127.7 Separation 

131.0 131.0 Separagion

 131.3 Channel margin 

131.6 131.8 Upper pool;

channel margin 

131.9 132.0 Separation;

reattachment

132.1 Channel margin 

133.1 133.0 Separation

133.9

134.2

134.5

133.1

133.7

133.8

133.9

133.9

134.1

134.5

Reattachment 

Channel margin 

Channel margin 

Channel margin 

Channel margin 

Channel margin 

Separation; 

reattachment

See footnotes at end of table.
APPENDIX A 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

73

River mile 

inventory

1923 1

Side

of

river

Site

Aerial 

photograph f 

number'

River mile 

inventory

1973 1983

Deposit 

type 3

137.0

137.0

137.1

137.4

137.3

134.8 Left Owl Eyes Camp 5-22

134.7 Right One Hundred Thirty- 5-21 

Five Mile Rapid

134.8 Right Above Granite Narrows 5-21 

Camp

136.1 Left Granite Narrows Camp 5-29

136.2 Left Opposite Deer Creek 5-31 

Falls

136.4 Left Lower Deer Creek Camp 5-32

136.5 Left Unnamed site 5-32

136.6 Left Unnamed site 5-33

136.7 Left Above Poncho's Kitchen 5-34

	Camp

Left Poncho's Kitchen Camp 5-36

Left Lower Poncho's Camp 5-36

Left Below Poncho's Camp 5-37

Left Unnamed site 5-39

Right Unnamed site 5-39

Right Unnamed site 5-39 

Left One Hundred Thirty- 5-40

Seven and One-Half

Mile Rapid

Left Unnamed site 5-42 

Left Unnamed site 5-44 

Left Unnamed site 5-45 

Right Unnamed site 5-46 

Right Fishtail Rapid 5-48 

Left Unnamed site 5-51 

Right Unnamed site 5-51 

Left One Hundred Forty 5-53

Mile Canyon

Left Unnamed site 5-54 

Left Unnamed site 5-56 

Left Unnamed site 5-60

Left Unnamed site 5-62

Right Unnamed site 5-69

Left Above Kanab Rapid 5-74

Right Unnamed site 5-74

Right Mouth of Kanab Creek 5-75

Left Unnamed site 5-84

Left Olo Canyon 5-88

Right Spring Above 5-102

	Matkatamiba Rapid

147.9 Right Matkatamiba Rapid 5-103

148.5 Left Lower Matkatamiba Rapid 5-106

149.7 Right Upset Rapids 5-114

151.6 Right Ledges Camp 5-122

152.3 Left Unnamed site 5-128

153.6 Right Sinyala Rapid 5-133

153.8 Left Sinyala Ledges Camp 5-135

154.9 Right Rockfall Lower Ledges 5-140

155.7 Right Last Chance Camp 5-146 

See footnotes at end of table.

137.5

137.6

137.9

138.2

138.4

138.6

138.9

139.3

139.3

139.7

139.9

140.2

141.0

141.4

142.4

143.4

143.1

143.5

145.0

145.6

147.7

134.8

134.8

Channel margin 

Channel margin

134.9 Channel margin

136.0

136.2 136.2

Channel margin 

Channel margin

136.4 136.5 Separation

136.5 136.6 Channel margin; 

	reattachment

 136.7 Channel margin; 

	reattachment

 136.8 Separation;

137.0 Separation

137.1 Reattachment;

 Separation

 137.3 Channel margin

 Separation;

	reattachment

 137.3 Channel margin

137.7 137.5 Channel margin

137.9 137.8 Separation

138.3 138.0 Separation

138.5 Channel margin

 138.7 Reattachment

138.9 139.0 Upper pool

139.4 139.5 Channel margin

139.4 Channel margin

139.7 139.8 Reattachment;

	upper pool 

139.9 Separation

 140.3 Channel margin

 141.0 Separation;

	Reattachment

 141.4 Channel margin

 142.5 Channel margin

143.3 143.4 Channel margin

 143.0 Channel margin

 143.5 Channel margin

 145.1 Channel margin

145.4 145.5 Separation

 147.7 Channel margin

 147.8 Channel margin

148.3 148.4 Channel margin

149.8 149.7 Separation

151.6 151.8 Rock

152.3 Separation

 153.5 Separation

153.8 Rock

 155.0 Channel margin

	reattachment 

155.6 155.7 Upper pool
74 AGGRADATION AND DEGRADATION OF SAND DEPOSITS, GRAND CANYON NATIONAL PARK, ARIZONA 

Comparison of river mile inventories of 1973 and 1983 from Lees Ferry to Stone Creek Continued

River mile 

inventory Side 

of 

1923 l river

155.8 

156.3 

156.6 

157.8 

158.0 

158.3 

158.7 

159.4 

159.9 

160.4 

160.7 

161.6 

162.0 

162.1 

162.4 

162.8

163.1

163.3 

163.9 

164.5

164.9 

165.0 

165.1 

165.7 

165.8 

165.9 

165.9 

166.3

166.4 

166.5

Right 

Right 

Left 

Right 

Left 

Right 

Right 

Right 

Left 

Left 

Right 

Right 

Left 

Left 

Left

Right

Left 

Left 

Right

Right 

Left 

Right 

Left 

Left 

Left 

Left 

Left

Left 

Left

Site

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site

Unnamed site

Unnamed site 

Unnamed site 

One Hundred Sixty-Four 

Mile Rapid 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Unnamed site 

Above Upper National 

Rapid 

Upper National Rapid

National Rapid

Aerial 

photograph 

number2

5-146 

5-150 

5-151 

5-158 

5-159 

5-159 

5-161 

5-167 

5-170 

5-172 

5-175 

5-180 

5-182 

5-182 

5-184 

5-187

5-189

5-190 

5-193 

5-199

5-202 

5-202 

5-203 

5-206 

5-207 

5-207 

5-208 

5-210

5-211 

5-211

River mile 

inventory

1973 1983

 156.5

 157.7 

 157.8

JL.JW . Jk

158.6 158.5

JL^0 . d

159.8 

 160.4

160.7 

 162.0

 163.5 

163.9 163.9 

164.5 164.5

 165.0 

 165.0 

 165.2 

 165.7 

 165.8 

 166.0

166.5 166.5 

166.6 166.6

Deposit 

type 3

Separation 

Channel margin 

Channel margin 

Channel margin 

Channel margin 

Channel margin 

Channel margin 

Separation 

Channel margin 

Channel margin 

Separation 

Channel margin 

Separation 

Channel margin 

Channel margin 

Upper pool; 

Reattachment 

Separation; 

Reattachment 

Channel margin 

Channel margin 

Separation

Channel margin 

Reattachment 

Reattachment 

Reattachment 

Channel margin 

Separation 

Channel margin 

Channel margin

Channel margin 

Reattachment 

Separation

Hliver mile located to nearest 0.1 mile based on 1923 survey (Birdseye, 1923) as 

plotted on 1984 aerial photographs.

%umber of aerial photographs on which site is located (U.S. Bureau of Reclamation, 

1984 series).

^Largest deposit type listed first.

U.S. GOVERNMENT PRINTING OFFICE: 1990 785-046/3036


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