U.S. Department of the Interior 

U.S. Geological Survey

Bedload and River Hydraulics—Inferences 

from the East Fork River, Wyoming

U.S. Geological Survey Professional Paper 1583

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Bedload and River Hydraulics— 

Inferences from the East Fork River, 

Wyoming

By LUNA B. LEOPOLD and WILLIAM W. EMMETT

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1583

1997
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

The use of firm, trade, and brand names in this report is for 

identification purposes only and does not constitute 

endorsement by the U.S. Government.

Library of Congress Cataloging in Publications Data

Leopold, Luna Bergere, 1915-

Bedload and river hydraulics : inferences from the East Fork River, Wyoming / by Luna B. Leopold 

and William W. Emmett,

p. cm. -- (U.S. Geological Survey professional paper ; 1583) 

Includes bibliographical references. 

Supt.ofDocs.no.: I 19.16:1583

1. Bed load-Wyoming-East Fork River. 2. Stream measurements-Wyoming-East Fork River. 

I. Emmett, William W. Title. III. Series. 

GB1299.8.W8L64 1997 

551.48'2-dc21 97-44113

CIP 

ISBN 0-607-88893-8

For sale by U.S. Geological Survey, Branch of Information Services 

Box 25286, Mail Stop 306, Federal Center 

Denver, CO 80225
CONTENTS

Page

Abstract................................................................ 1

General statement..................................................................._ 1

Research area.............................................................................................................................................................^ 2

Acknowledgments.......................................................^ 3

Geologic and geomorphic setting.......................................................................................................................................... 3

Pre-Pleistocene geology.............................................................................................................................................. 3

Glacial sequence........................................................................................................................................................^ 5

Glacial outwash terraces near the bedload project site................................................................................................ 5

Archaeology.................................................................^ 11

Characteristics of the river..................................................................................................................................................... 15

The bedload project site............................................................................................................................................... 16

Bed material and its distribution.................................................................................................................................. 17

Hydraulic geometry...................................................................................................................................................^ 23

Development and operation of the bedload trap.................................................................................................................... 24

Initial design................................................................................................................................................................ 24

Successful design......................................................................................................................................................... 24

Operation ..................................................................................................................................................................^ 26

Bedload and river hydraulics................................................................................................................................................. 31

Cross-channel variation of transport rate..................................................................................................................... 35

Hydraulic resistance.................................................................................................................................................... 36

Sediment rating curve computed from hydraulic geometry........................................................................................ 36

Scour and movement of bed material.......................................................................................................................... 37

Movement of marked rocks in relation to bed shear......................................................................................... 37

Distance moved by marked rocks...................................................................................................................... 37

Sand marked by fluorescent dye........................................................................................................................ 38

Water-surface topography............................................................................................................................................ 39

Cross-channel profile......................................................................................................................................... 39

Topography in a straight reach .......................................................................................................................... 39

Concluding statement............................................................................................................................................................ 43

Selected references..........................................................._^ 43

Bedload data and hydraulic parameters................................................................................................................................. 47

FIGURES

1. Map showing location of the bedload project site, channel cross sections, and streamflow-gaging

station 09203000, East Fork River near Big Sandy, Wyoming ............................................................................. 4

2. Diagram showing long profile of terraces along New Fork River, Boulder Creek, and Boulder Lake................. 7

3. Map showing terrace remnants in the vicinity of the bedload project site ............................................................ 8

4. Cross sections of channels and terraces at three locations along East Fork River and one location

on Muddy Creek..................................................................................................................................................... 9

5-7. Photographs showing:

5. East Fork River in the vicinity of the bedload project site............................................................................ 10

6. Wasatch beds that supply source sediment when eroded.............................................................................. 12

7. Paleo-Indian hearth in Parker-Temple Lake terrace, and crude artifacts found on surface

hillslopes of Cora Butte................................................................................................................................. 14

8. Hydrographs showing mean and median daily discharge, East Fork River near Big Sandy, Wyoming,

water years 1939-92............................................................................................................................................... 15

Contents III
Page

9-12. Graphs showing:

9. Flood-frequency curve, East Fork River near Big Sandy, Wyoming, water years 1939-92......................... 15

10. Diurnal fluctuation in discharge of East Fork River at the bedload project site........................................... 16

11. Flow-duration curve, East Fork River near Big Sandy, Wyoming, water years 1939-92 ............................ 16

12. Year-to-year variation of annual peak discharge and mean annual flow, and

relation of annual peak discharge to mean annual flow, East Fork River near Big Sandy, Wyoming,

water years 1939-92...................................................................................................................................... 17

13-15. Photographs showing:

13. Aerial view of East Fork River valley upstream from the site of the bedload trap...................................... 18

14. Research site before installation of the bedload trap.................................................................................... 19

15. Site of the bedload trap allow flow and high flow....................................................................................... 20

16. Cross section of East Fork River channel at the site of the bedload trap, prior to construction ........................... 21

17. Graph showing discharge rating curve for East Fork River at the site of the bedload trap................................... 21

18. Graphs showing size distributions of bed material in East Fork River at State Highway 353,

and of bed material and bedload at the project site............................................................................................... 21

19. Map showing distribution of bed material in the project reach, July 12, 1976..................................................... 22

20. Photographs showing the initial unsuccessful bedload trap installed at the same location where

the successful machine was constructed later....................................................................................................... 25

21. Simplified engineering drawings of mechanism for the bedload trap................................................................... 27

22. Photographs showing the bedload trap on East Fork River.................................................................................. 28

23-29. Graphs showing:

23. Typical measurements of weight of sediment accumulating in the hopper as a function of time

at a low discharge and at a higher discharge ................................................................................................ 32

24. Measured unit bedload-transport rate as a function of effective water discharge,

East Fork River at bedload trap.................................................................................................................... 33

25. Measured unit suspended-sediment transport rate as a function of discharge, East Fork River

at bedload trap (1979 data)........................................................................................................................... 33

26. Measured unit bedload-transport rate as a function of excess stream power, East Fork River

at bedload trap............................................................................................................................................... 34

27. Cross-channel distribution of bedload transport and water depth, East Fork River

at bedload trap............................................................................................................................................... 35

28. Percentage of painted rocks that moved different distances in East Fork River during a

season of snowmelt runoff, 1969 experiment and 1970 experiment............................................................ 38

29. Cross-channel profiles of the water surface, East Fork River at bedload trap, May 27, 1979 ..................... 39

30. Maps showing water-surface contours for decreasing values of discharge in a straight reach of

East Fork River about 3 kilometers upstream from the bedload trap, May and June 1979 .................................. 40

TABLES

1. Summary of Pleistocene and Holocene events ..................................................................................................... 6

2. Heights of terraces above present streambed level................................................................................................ 6

3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River,

Wyoming, 1973-79.......................................................^ 48

IV Contents
VERTICAL DATUM

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 the United States and Canada, formerly 

called Sea Level Datum of 1929.

SYMBOLS

A Cross-sectional area, in square meters (m2)

d Mean depth of flow, in meters (m)

D Grain diameter (particle size), in millimeters (mm)

D50 Median grain diameter, in millimeters (mm)

D35 Grain diameter at 35 percent finer, in millimeters (mm)

D84 Grain diameter at 84 percent finer, in millimeters (mm)

/ Darcy-Weisbach friction factor (dimensionless)

g Acceleration due to gravity, in meters per second per second (m/s )

ib Measured unit bedload-transport rate, in kilograms (mass immersed) per second per meter of width (kg/m-s)

/b' Theoretical unit bedload-transport rate, in kilograms (mass immersed) per second per meter of width (kg/m.s)

z s Measured unit suspended-sediment transport rate, in kilograms (mass immersed) per second per meter of

	width (kg/m-s)

N Newton—a unit of force, in kilograms times acceleration due to gravity (kg-m/s )

Q Water discharge, either total or effective, in cubic meters per second (m/s)

5 Water-surface slope, in meters per meter (m/m)

5S Ratio of grain density to fluid density (dimensionless)

u Mean velocity, in meters per second (m/s)

M0 Mean velocity at initial value for grain motion, in meters per second (m/s)

M* Shear velocity, in meters per second (m/s)

M/M* Friction factor (dimensionless)

w Width of flow [or width of bedload slot], in meters (m)

0 Shields threshold criterion (dimensionless)

Y Specific weight of water, 1,000 kilograms per cubic meter (1,000 kg/m3 )

p Density of water, in kilograms per cubic meter (kg/m3)

TO Shear stress at initial motion, in kilograms per square meter (kg/m )

CO Available unit stream power, in kilograms per second per meter of width (kg/m-s)

(00 Unit stream power needed for initial motion, in kilograms per second per meter of width (kg/m-s)

(0 - (00 Excess unit stream power, in kilograms per second per meter of width (kg/m-s)

Contents

Bedload and River Hydraulics— Inferences from the 

East Fork River, Wyoming

By Luna B. Leopold and William W. Emmett

ABSTRACT

During 1973-79, bedload data were collected in a sophisticated trap on a river of moderate size, the East Fork. The transport rate was 

measured most days through a full snowmelt season, and the rate was determined separately for 

eight zones across the channel width. The quantitative data are unique and unlikely to be repeated. 

Nor need they be, because as a result of this effort 

a practical bedload sampler was adequately tested 

against full river measurement.

It was shown that bedload moves sporadically and randomly on the river bed. Therefore, 

transport rate is highly variable in short periods of 

time. There is also a wide variance from day to 

day. Yet, different rivers have transport rates, 

which are functions of discharge, depth, and sediment size, that are clearly distinct.

Comparison of computed and measured 

transport rates indicates that a major problem 

remains: What grain size is representative of the 

bedload when there is a wide or heterogeneous 

particle-size distribution? Size of the bedload in 

motion may be very different from the size of bed 

material obtained from samples of the streambed.

For general computation, the river channel 

slope may be averaged, and it may be assumed 

that water-surface slope does not change materially with changing discharge. Indeed, this generality is correct, in that, compared with depth, 

velocity, and width, slope is conservative at-a-station. However, in more detail, slope changes 

importantly with discharge in short reaches of

channel, and those changes are very different in 

pool and riffle.

These local changes in slope are not merely 

an aspect of a detailed longitudinal profile but 

involve cross-channel as well as down-channel 

components. The pool and riffle sequence 

involves not only undulation of bed elevation and 

bar formation on alternate sides of the channel, 

but alternation of the zone of superovulation of 

the water surface, and changing relation of watersurface slope to discharge. These details can be 

seen only in the full topography of the water surface.

Riffles fill during high flow and scour at 

low flow. Changes in local water-surface slope 

illustrate this process. Pools are a storage zone 

for sediment in the low-flow season. Even though 

large volumes of sediment move, the distance 

moved is not large—in the East Fork River, sand 

of size 0.5-1 millimeter moved 650 meters during 

the 1979 snowmelt runoff season.

Bedload transport is greatest over or near 

bars and not in the deepest part of the channel. 

Direct observation of the locus of sediment transport indicates that this locus moves from one side 

of the channel to the other in concert with the 

occurrence of alternate bars. Separately, data 

indicate that at constant stream power, transport 

rate increases as depth decreases.

GENERAL STATEMENT

In the 80 years subsequent to the famous experiments of G.K. Gilbert (1914) on the transportation of 

debris by running water, only a few investigators have

General Statement
attempted to obtain somewhat similar data from a natural river. However useful the Gilbert data, they apply 

to a flume with fixed walls, and a flume is, after all, not 

a river. The ability to adjust the channel cross section 

to a variety of flows is one of the characteristics of a 

natural channel that is not shared by any fixed-walled 

flume. Clearly, the variety of conditions controlled in 

laboratory experimentation cannot be established in a 

natural river. The sediment in transport is determined 

by the geology and physiographic setting of the river; 

thus, the sediment is not a controllable variable. Furthermore, a principal characteristic of a natural river 

system is the variability of discharge, another parameter ordinarily held constant or controlled in flume 

experimentation.

Even with the limited ability to hold any variables constant, it would be highly desirable to have 

direct measurements of the bedload transport in a natural river and of the concomitant hydraulic characteristics of the flow. The problem has been particularly 

intractable, because no sampling device has been 

available that would provide reliable and repeatable 

measurements of the debris load moving along the bed 

of the river. If, on the other hand, sampling were not 

the procedure used, an apparatus would be needed that 

would trap the total sediment and provide measurements of the moving load through time and space 

across the river. Because of the variability through 

time, repeated measurements during successive seasonal flows would be required.

This project involved the construction of such an 

apparatus and operation of the apparatus for 7 years. 

The data from the sediment trap also allowed field calibration of a highly successful bedload sampler 

designed by Edward Helley and Winchell Smith of the 

U.S. Geological Survey (Helley and Smith, 1971). 

The development of this field sampler happened to 

coincide with the construction of a successful bedload 

trap. Thus, two methods of measuring the sediment 

moving along the streambed became available for 

simultaneous operation. The coincidence of these two 

developments allowed the bedload trap to be a field 

test of the sampler as described in detail by Emmett 

(1980a).

In the same decade, another bedload measuring 

device of sophisticated design was operated in Britain 

by lan Reid and his associates (Reid and others, 1984). 

The results reported here might well be examined in 

conjunction with that report. The East Fork device 

caught all bedload that dropped into a slot on the streambed; it was then transported by moving belt to the 

streambank, lifted to the surface for weighing and 

sampling, and returned to the river. The Reid device 

weighed the sediment as it passed over sensitive 

underwater pressure sensors. Each of the installations 

produced interesting and useful information and each 

added to the value of the other.

This report describes the bedload and hydraulics 

of the East Fork River in western Wyoming. We begin 

with a description of the geologic and geomorphic setting of the river basin. The characteristics of the East 

Fork River in the general area and at the project site 

are then described with the aim of demonstrating that 

the East Fork is like many other rivers in the region 

and that it is normal rather than unique.

The bedload trap, including the history of its 

development, is then described. The operational procedure is detailed, as is the process of analyzing the 

data. Finally, the data are introduced. They consist of 

140 sets of measurements, most taking 1 day to complete. These sets of measurements, listed at the end of 

this report, were made on 114 different days over 6 

separate years during 1973-76, 1978, and 1979. 

Because of drought conditions, no data were collected 

during 1977, but on several days during 1976 and 

1978, multiple sets of measurements were collected. 

Published data sources for bedload transport rates and 

size distributions are listed below:

Dates Data source

1973-76 Emmett (1980a); Leopold and Emmett (1976; 1977)

1978 Emmett and others (1985)

1979 Emmett and others (1980)

In 1979, a much more elaborate set of measurements was recorded at 40 cross sections spaced about 

equally along a 3.3-km reach of the river (Emmett and 

others, 1980). In 1980, a more detailed set of data was 

collected at 42 cross sections along a 1.8-km reach 

(Emmett and others, 1982). The results of these studies help explain some of the features observed at the 

bedload trap.

Research Area

Most rivers, having peak discharge resulting 

from rainstorms, pose a difficult problem for the fluvial geomorphologist and hydraulician, owing to the

Bedload and River Hydraulics—Inferences from the East Fork River
rapid rise and fall of discharge and the inability to 

forecast when the observer needs to be at the measuring site. The authors spent considerable effort measuring hydraulic variables on a perennial river in 

Maryland, but the flashiness made it nearly impossible 

to complete the desired measurements during the time 

that discharge was relatively constant. Measurement 

of water-surface slope was particularly intractable. 

Therefore, we began serious work on snowmelt rivers 

in the Rocky Mountains. A decade of such work on a 

variety of streams led us to choose those in Sublette 

County, Wyoming, as being satisfactory for a longterm study of bedload.

The river that seemed to fit the eventual objective best was the East Fork River, a tributary flowing 

westerly out of the Wind River Range, joining the 

New Fork River near the town of Boulder, Wyoming 

(fig. 1). The New Fork then flows southwest to join 

the master stream, the Green River, a tributary to the 

Colorado River. The East Fork has several characteristics that made it highly desirable for the project. It is 

a snowmelt stream with a flood season that lasts from 

mid-May to late June. At all other times of the year, 

the flow is low, and little bedload is in motion. Rainstorms contribute practically nothing to the flood discharge.

The East Fork River heads in high mountains 

consisting of igneous and metamorphic rocks relatively free of fine-grained material. The river does not 

flow through any soft sediments until it is several kilometers from the mountain front, so the material carried 

is mostly sand and gravel with practically no silt or 

clay. Thus, it offered an opportunity to measure primarily bedload with unusually small amounts in suspension.

The other characteristic of the East Fork River 

that makes it different from all other streams in the 

upper part of the Green River system is that there is no 

lake on the East Fork to trap the sediment coming 

from the source or to attenuate the flows resulting 

from snowmelt in the high country. Without exception, all other streams of its size have a lake somewhere along the length, formed by a terminal moraine 

as in the case of New Fork Lakes, Willow Lake, Fremont Lake, Half Moon Lake, and Boulder Lake 

(fig. 1; New Fork Lakes are northwest of the area 

shown in fig. 1).

Another practical consideration was that the 

project site should be near a bridge crossing the river 

in order to obtain access to the far bank. Such a location was found in the SE1/4NE1/4NW1/4 of sec. 11, 

T. 31 N., R. 107 W, where a wooden county road 

bridge crosses the East Fork near the place chosen for 

the experiment. The location of the bedload project 

site is shown in figure 1. A contract was negotiated 

with the land owner to rent a small plot of land where 

the installation was made and where we could keep 

our equipment and make the measurements.

Acknowledgments

During more than a decade of work on this river, 

especially at the bedload trap, many individuals 

observed or participated for short or long periods. The 

list is too long for individual attribution, but two were 

of special importance to the research project: Robert 

M. Myrick in construction and operation, and James F. 

Wilson, Jr. in manuscript preparation. We thank all 

contributors, but for these two individuals, we owe a 

debt of gratitude.

GEOLOGIC AND GEOMORPHIC SETTING

Pre-Pleistocene Geology

The East Fork River heads in the Wind River 

Range, a mountain range extending 190 km northnorthwest and 58 km wide, as shown in the location 

map (fig. 1). The range rises above an extensive basin; 

the elevation of the basin is about 2,100 m above sea 

level. Mount Bonneville is the highest point in the 

East Fork basin, at 3,831 m.

To the southwest of the Wind River Range are 

nearly horizontal sedimentary rocks in the Green 

River Basin. These rocks of Cenozoic age are overthrust by the Precambrian rocks of the range along a 

thrust plane that dips 30° to 35° to the northeast. "The 

Precambrian core of the uplift consists of migmatites 

at deeper levels in the center of the range and granitic 

intrusions and super crustal rocks at higher crustal levels at the southeast end. These rocks constitute some 

of the oldest Precambrian crust in the United States 

and are dated at 2.7 b.y. B.P. [billion years before 

present]." (Smithson and others, 1978).

These investigators ran a deep seismic-reflection traverse from a position about 120 km southsoutheast of Pinedale northeast to a point about 

120 km east of Pinedale—a distance of about 150 km. 

The depth to which the reflection data were considered

Geologic and Geomorphic Setting
43°00'

110°00' 50' 40' 30' 20' 109° 10'

50'

40'

42°30'

FREMONT 

COUNTY

/

^

vf

Base modified from U.S. Geological Survey digital data, 1:100,000; 1985

Albers Equal Area-Conic projection.

Standard parallels 29°30' and 45°30', central meridian -107°30'

SCALE 1:500,000

WYOMING

"MAP AREA

3 5

I

10 15 2

I i

I I

20 KILOMETERS

10 MILES

EXPLANATION

DRAINAGE BASIN OF 

EAST FORK RIVER 

ABOVE PROJECT SITE

STREAMFLOW-GAGING STATION09203000, East Fork River 

near Big Sandy, Wyoming

LOCATION OF DIAGRAMATIC 

CROSS SECTION SHOWN 

IN FIGURE 4

Figure 1. Location of the bedload project site, channel cross sections, and streamf low-gaging station 09203000, 

East Fork River near Big Sandy, Wyoming.

Bedload and River Hydraulics—Inferences from the East Fork River
good was 60 km. The sedimentary rocks under the 

southwest end of the profile range in age from Cambrian through Tertiary. The sedimentary rocks directly 

under the thrust are deformed by folding and numerous faults. The fault can be traced to a depth of at least 

24 km past the deepest possible sedimentary rocks, 

and the fault continues into the Precambrian crystalline rocks of the crust.

Glacial Sequence

More important to the present investigation are 

the results of massive glaciation during the Pleistocene 

Epoch (10,000 to 1.65 million years B.P.) studied first 

by Blackwelder (1915), the glaciation in the southwestern part of the range later reported by Holmes and 

Moss (1955), and the glaciation in the Pinedale area 

reported by Richmond (1973). At least four principal 

glacial periods are identified. The earliest wellpreserved combination of fill and outwash terrace is 

called the Buffalo by Holmes and Moss (1955) and 

presumably is related to either the Cedar Ridge or the 

Sacagawea Ridge glaciations of Richmond (1973). 

This episode is considered by Holmes and Moss 

(1955) to be pre-Wisconsin. The two main glacial 

events, Bull Lake and Pinedale, both compound and 

involving successions of advance and retreat, are 

marked by massive moraines and widespread outwash 

plains that have subsequently been trenched, leaving 

extensive dissected terraces along the main river valleys. These are tentatively considered to be correlated 

with the last phases of Wisconsin glaciation. 'The 

longest time interval between stages separates the Buffalo and Bull Lake. The interval between Bull Lake 

and Pinedale is substantial and greater than the interval between Bull Lake I and Bull Lake II or between 

any of the oscillations of the Pinedale." (Holmes and 

Moss, 1955, p. 651).

Subsequently, there was a minor advance, Temple Lake, indicated by moraines 16 to 30 km upstream 

from Pinedale moraines and a short distance below 

cirque headwalls. The outwash train forms a low terrace, Parker-Temple Lake, along some of the valleys. 

A still younger minor advance is considered contemporaneous with the Little Ice Age of late Holocene 

time (less than 10,000 years B.P). Because the main 

source of sediment carried by the East Fork and other 

rivers is the suite of terraces within the valleys, the 

glacial sequence and the associated deposits are 

important in the present context.

A summary of Pleistocene and Holocene events 

prepared by Holmes and Moss (1955) is shown in 

table 1, and the heights of those terraces above the 

local streambeds are shown in table 2. The relation of 

terraces to glacial events was determined by tracing 

terraces upstream to the moraine at which each terminates, a method first used by Bryan and Ray (1940). 

For Boulder Creek, the longitudinal and elevation 

positions of terraces and moraines are shown in 

figure 2, which indicates that Pinedale ice destroyed 

remnants of Bull Lake and higher terraces, and that the 

main Pinedale terrace abuts and begins at the main 

Pinedale moraine; the Parker-Temple Lake terrace is 

traced through that moraine. Boulder Creek is immediately north of the East Fork River, and it may be presumed that the East Fork would have similar profiles.

Glacial Outwash Terraces Near The Bedload 

Project Site

The areal extent of different terrace remnants 

and moraines was mapped in detail by Holmes and 

Moss (1955) upstream along the East Fork River to a 

point 3.2 km (2 mi) south of Fremont Butte or about 

3.7 km north (downstream) from the bedload project 

site. Using the nomenclature in table 2, we have outlined the terrace remnants in the vicinity of the project 

in figure 3. The terrace heights shown in figure 3 

closely agree with those measured by Holmes and 

Moss (1955) farther downstream from the East Fork. 

However, a considerable length of stream near the 

project is bordered by a low terrace, 1.5 m above the 

river. This terrace seldom is flooded; it is higher than 

the flood plain subject to frequent inundation. 

Although not shown in table 2 for the downstream part 

of the East Fork, the terrace is believed to correlate 

with the Parker-Temple Lake terrace. Holmes and 

Moss (1955), in listing the flood-plain height at 

0-1.5 m (0-5 ft), may have lumped the Parker terrace 

and flood plain together, because their mapping, 

encompassing 233 km2 (90 mi2), was primarily concerned with the older, more widespread units.

Our measurements and those of Andrews 

(1979a, 1979b) indicate that even at high flow little 

bedload is carried by the East Fork immediately 

upstream from its largest tributary, Muddy Creek, or 

where State Highway 353 crosses the river 10 river 

kilometers upstream from the project site (fig. 1). The 

explanation can be seen in the glacial geology.

Geologic and Geomorphic Setting
Table 1. Summary of Pleistocene and Holocene events

[Modified from Holmes and Moss, 1955; --, no information given]

Moraine 

deposition

Little Ice Age 

moraines

Temple Lake 

moraines

Recessional 

Pinedale 

moraines

Main Pinedale 

moraine

Bull Lake II 

moraine

Bull Lake I 

moraine

Buffalo till

--

Terrace 

deposition

Flood plain

Parker- Temple Lake 

terrace 1

Pinedale recessional 

terrace2

Main Pinedale terrace3

Bull Lake II terrace

Bull Lake I terrace

Faler (?) terrace 

Buffalo (?) terrace

Toboggan terrace

Frost action 

and mass 

movement

Younger talus; 

palsen

Older talus; 

felsenmeer and 

polygonboden

Periglacial frost 

action likely 

during glaciation

--

Eolian action

—

Widespread eolian 

action leeward 

of outwash

Possibly some 

eolian action in 

Eden Valley

—

-

Vegetation

Chenopods and the 

composites. 

Grass maximum

Fir

-

--

Early Man

—

Occupation, 

Finley site

--

-

-

Called Parker terrace by Holmes and Moss (1955). 

Called Lower Pinedale terrace by Holmes and Moss (1955). 

Called Upper Pinedale terrace by Holmes and Moss (1955).

Table 2. Heights of terraces above present streambed level

[Modified from Holmes and Moss, 1955; —, no data]

Terrace height 

(meters; feet in parentheses1 )

Stream system

Terrace

Flood plain 

Parker- Temple Lake3 

Pinedale recessional4 

Main Pinedale5

Bull Lake II

Bull Lake I

Faler

Buffalo

Toboggan

Boulder CreekNew Fork River

0-1.5 (0-5) 

10 (32) 

14 (45) 

20 (65)

23 (75)

31(103)

41(135)

59(195)

--

East Fork River2

0-1.5(0-5)

6(20) 

10 (33)

18 (60)

26 (85)

-

--

91 (300)

Originally published in feet.

2Holmes and Moss (1955) did not map terraces as far upstream as the bedload project 

site; heights for East Fork River are presumed to be downstream from the project 

site.

3Called Parker terrace by Holmes and Moss (1955). 

4Called Lower Pinedale terrace by Holmes and Moss (1955). 

Called Upper Pinedale terrace by Holmes and Moss (1955).

Bedload and River Hydraulics—Inferences from the East Fork River
100

Q 

LU 

CO

00 LU

Lull 50

CQZ

25

NEW FORK RIVER • BOULDER CREEK 

TOBOGGAN

BOULDER LAKE

PINEDALE RECESSIONAL 

MORAINES

_P!_NEDALE RECESSIONAL_ . 

PARKER-TEMPLE LAKE

----- -i-v

DAM

^ Boulder Creek deeply 

incised at this point

I______L_

4 6 8 10 12 14 16 18 20 

DISTANCE UPSTREAM FROM MOUTH OF EAST FORK RIVER, IN KILOMETERS

22 24

Figure 2. Long profile of terraces along New Fork River, Boulder Creek, and Boulder Lake (modified from Holmes 

and Moss, 1955).

The East Fork River heads in Precambrian rocks 

just south of Mount Bonneville (fig. 1) and flows 

southward for about 22 km on the high Fremont surface on which soils are thin, bedrock abounds, and rivers carry little sediment along the bouldery channels. 

About 10 km upstream from State Highway 353 the 

river changes to a westerly course, and flows in a canyon eroded in the main Pinedale moraine. The till is 

bouldery and well consolidated, so the rate of excavation of material must be very low. The river emerges 

from the moraine onto the unconsolidated and moderately well-sorted debris of the outwash terraces near 

the State Highway 353 bridge. The large rocks available in the moraine are seen in the channel bed for 

only a short distance downstream from the morainal 

margin. Thereafter, the streambed is much less steep 

and is composed of smaller and better sorted material.

Channel cross sections and terraces, associated 

berms and terraces, and observed bed and bank materials at three locations along the East Fork are shown 

in figure 4. Section A is near the State Highway 353 

bridge just below the main Pinedale moraine. A 

prominent sage-covered terrace stands 2.8 m above 

the streambed, with lower levels of grass, shrubs, and 

willow at 1.5 m. Streambed gradient at this location is 

0.0023; the bed material has a D5G (median particle 

size) of 90 mm. Section B of figure 4 is at the bedload 

project site, where the river slope is 0.0007, the D50 of 

bed material is 1.25 mm, and a nearby outwash terrace

is at 7 m above the streambed. Section C, near Fremont Butte, 6.4 valley kilometers downstream from 

the project site, has berms at 1, 2.8, and 4 m above the 

streambed. These levels agree in part with those identified by Holmes and Moss (1955, table 2) and with 

levels determined from areal distribution of major 

mapped terraces, but the details obtained at specific 

river cross sections add some levels not mapped in the 

smaller scale areal studies.

A similar valley cross section of Muddy Creek 

near its mouth is shown in figure 4D. Some of the terrace levels are locally expressed as straths cut on the 

(Tertiary-age) Wasatch Formation bedrock, presumably by lateral migration of the river against the valley 

side.

The assignment of a given berm or level to its 

associated glacial outwash is not self-evident. With 

the present information, it appears safe to assign a terrace remnant standing about 7 m above the East Fork 

River to the Pinedale recessional terrace and the one at 

10 to 12 m to the main Pinedale terrace. The flood 

plain that is forming presently and that is inundated 

during high flow is the level at 1 to 1.5 m above the 

streambed. The most ubiquitous low terrace along the 

East Fork is the one at 1.5 to 2.8 m; it probably is 

related to the minor glaciation called Parker or Temple 

Lake. This terrace is usually vegetated by sage and is 

not inundated. Considering the fact that little bedload 

was measured at the base of the moraine near State

Geologic and Geomorphic Setting
42°41'

109°34' 109°33'

42°40' —

1

EXPLANATION

Number in box is approximate height 

above streambed, in meters

\12 N

FLOOD PLAIN DEPOSITS 

TERRACE REMNANTS

Parker-Temple Lake

Pinedale recessional

Main Pinedale

WASATCH FORMATION (TERTIARY) 

AREA NOT MAPPED

CONTACT

42°391%

Base modified from U.S. Geological Survey 

1:24,000 quadrangle: Fremont Butte, 1964

0.5

I

1 KILOMETER

0.5 MILE

Figure 3. Terrace remnants in the vicinity of the bedload project site (modified from Leopold, 1982a, fig. 3).

8 Bedload and River Hydraulics—Inferences from the East Fork River
Grass and shrubs

n i i i r 

SURVEYED

Sage terrace

Willows and grass

iMW 

\l ®' V>" ' V'

—i——i——i——i—— 

SURVEYED

Willows and grass 

(flooded)

Grassy flat 

(not inundated)

f Outwash 

terrace -

KXjFitr^" 1 Sandy silt J

'£>'-o'.o~o- 

=>.<?••?.?: '°'3*'o- 

&°;?<£?-h Gravel

&%&:'

i i i i

ESTIMATED, NOT SURVEYED

Sage

Sandy silt'.^^L'f-IlTJ^jSfl/'Paleo-lndian '••:•':' /•r : '.-^H

Sand' :y.-. :.''.'.''\ t.\\

r '- 

Gravel

hearth

Willows and grass

l'l M 1''!','

'-" VMV.I/

,^l'i cl ^"iili^ 

»^::M:i:r

l?.: 'Glacial

'(5? outwash

Sand and 

• gravel ?-•?:

>^!l)!i^i?if si

_jfo!^i °^fi '01, o; o,' -fo"o •oy.'o.'o.o .

r r i

5\ ESTIMATED, NOT SURVEYED 4

Wasatch Formation' 

(Tertiary) Silt,

channeled 

Brown banded silt 

Limonite-stained sand

Sand

i i i i i i i i i i i i i

10 20 30 40 50 60 70 

CROSS-CHANNEL DISTANCE, IN METERS

80 90

Figure 4. Cross sections of channels and terraces. A, East Fork River 15 meters 

downstream from State Highway 353 bridge. B, East Fork River at the bedload 

project site. C, East Fork River at Fremont Butte. D, Muddy Creek near mouth. 

Views are downstream. Locations are shown in figure 1.

Geologic and Geomorphic Setting 9
Highway 353 or upstream from the mouth of Muddy 

Creek, most of the bedload carried by the river through 

the study reach is postulated to be derived from lateral 

erosion of the unconsolidated sand and gravel of the 

Parker-Temple Lake terrace, and from the places the 

river is impinging on the Pinedale recessional terrace 

shown in figure 5. These terraces can be eroded both by

Muddy Creek and by the East Fork River downstream 

from the mouth of Muddy Creek. Some bedload also is 

contributed as small alluvial fans emanating from gullies eroded into the steep slopes and walls of the 

Wasatch bedrock as shown in figure 6. All of these 

sources would produce sediment in the sand and gravel 

size range observed in the trapped bedload.

Figure 5. East Fork River in the vicinity of the bedload project site. A, Looking 

downstream, Wasatch Formation cliff at left, flood plain on right. B, Looking 

upstream, Pinedale recessional terrace on left, flood plain on right, gravelcovered streambed with central gravel bar. C, View of valley from top of Wasatch 

cliff; flow is toward left; project site in background where white trailer is located 

near road.

10 Bedload and River Hydraulics—Inferences from the East Fork River
Figures. (Continued)

Archaeology

Archaeology is an important part of geomorphic 

history. This is especially true as it relates to the history 

of alluvial terraces and the sources of bedload.

Several Paleo-Indian hearths have been exposed 

by lateral erosion of the Parker-Temple Lake terrace. 

One is shown in the section near Fremont Butte 

(fig. 7A). Three were eroded from the streambank 

within a few meters of the bedload trap. Each consisted 

of a bowl-shaped pit 23 cm deep and 75 cm across the 

top. They are lined with rounded rocks very close to 

60 mm in diameter, now completely blackened by carbonized fuel. Some of the blackened rocks show a caliche film over the carbon coating. These people 

apparently built fires in the rock-lined holes, heated the 

rocks, then placed tubers over the rocks for roasting. 

No bones of any kind were found in or near the hearths. 

The hearths found were all close to the river and were 

built in the surface 1 to 1.5 m above present streambed. 

Similar hearths found in eastern Wyoming have been 

dated at about 3,000 B.P. (Prison, 1988).

Surface finds of points and blades are not diagnostic as to stratigraphic level. One obsidian blade 

found near the bedload project site, apparently washed 

from deposits of the Parker-Temple Lake terrace, 

closely resembled those from the Finley site, but was of 

the Yuma rather than the Folsom type (Howard and 

Hack, 1943). The Finley site is in the Kilpecker dunes 

near Eden, about 100 km south of the project site.

All the hearths found along East Fork River have 

been covered subsequent to use by 10 to 20 cm of alluvium or colluvium. They are, therefore, younger than 

the end of the deposition of the Parker-Temple Lake 

outwash but are old enough to have received some depositional cover. This terrace, important as a source of 

East Fork River bedload, is thus of Holocene age but 

older than 3,000 years B.P.

More interesting anthropologically are the 

numerous flakes and cores found scattered on the 

ground surface of unglaciated Cora Butte, located about 

12 km northwest of Pinedale (fig. 1). This hill is one of 

several in the vicinity, including Mount Airy (southwest 

of Pinedale, fig. 1), that is underlain by the Wasatch 

Formation, leveled on the top and capped with 2 to 3 m

Geologic and Geomorphic Setting 11
B

Figure 6. Wasatch beds that supply source sediment when eroded. A, Small alluvial 

fan at mouth of minor gully in cliff of Wasatch Formation. B, Sloughing of Wasatch cliff. 

C, Rill and small alluvial fan on Wasatch cliff. D, High-water mark about 1.5 meters 

above water surface, showing minor bank erosion at times of high flow.

12 Bedload and River Hydraulics—Inferences from the East Fork River
Figure 6. (Continued)

Geologic and Geomorphic Setting 13
Figure 7. A Paleo-lndian hearth in Parker-Temple Lake terrace. Hearth is covered with 

about 0.5 meter of colluvium or alluvium (ruler is 15 centimeters long). B, Crude artifacts 

made of yellowish-green quartzite found on surface hillslopes of Cora Butte.

14 Bedload and River Hydraulics—Inferences from the East Fork River
of rounded river gravel. In late Tertiary or early Pleistocene time, a series of pediments were eroded by 

streams flowing south-southwest. Gravel from the 

cap, over time, was moved downslope, and is found 

scattered on the flanks of the hill. The cores and flakes 

are scattered among the rounded rocks derived from 

the hilltop. All the flakes are riven by percussion from 

cores of a distinctive yellowish or yellowish-gray, 

fine-grained, dense quartzite that is not indigenous to 

the Wind River Range. One such core and a tool of 

the same material are shown in figure 7B. The flakes 

have no desert varnish, but some have a yellowishorange surface stain. Some have lichen colonies as 

large as 1 cm in diameter. Others have some caliche 

deposit on the underside and on the edges of the top 

side.

The common occurrence on unglaciated Cora 

Butte of these crudely worked rocks is in marked contrast to their absence on any glaciofluvial terrace in the 

vicinity. The possibility that they predate these terraces is intriguing.

CHARACTERISTICS OF THE RIVER

The point chosen for installation of the bedload 

trap on the East Fork River has a drainage area of 

466 km2 (180 mi2). Approximately one-half of the 

area is drained by Muddy Creek, which joins the East 

Fork about 4 km upstream from the bedload trap. 

Muddy Creek contributes much of the sand fraction of 

the sediment load in the East Fork but little of the 

water during the spring snowmelt season. 

The U.S. Geological Survey gaging station near Big 

Sandy (station 09203000, fig. 1), having 54 years of 

record (1939-92), was located about 15 km (9 mi) 

upstream from the project site. The drainage area at 

the station is 205 km2 (79 mi2), and the mean annual 

flow for the period of record is 2.9 m3/s. Because 

most of the runoff is from elevations upstream from 

Big Sandy, that figure probably is about the same as 

the mean annual flow at the bedload project site. But 

because of irrigation diversions between the two sites, 

peak discharges during late May and June are about 

6.5 m3/s greater at the gaging station than at the 

project site. Peak flows of the East Fork River result 

from spring snowmelt; rainstorms do not cause appreciable hydrograph rises. During a typical spring runoff season, which begins in early May, the river peaks 

during the first week of June and returns to low flow 

during July, as shown in figure 8. The flood-frequency

curve for East Fork River near Big Sandy is shown in 

figure 9. Recurrence interval at bankfull stage is about 

1.2 years.

20

§ 18

CJ 

LUGO is

DC 

LU 

Q_

GO 14

cc

LU

tU 12

CJ

m 10

Z> 

CJ

CD

GO 4

I 2

0

\ \ \ \ \ \

Oct Nov Dec Jan Feb Mar Apr May June July Aug Sept

Figure 8. Mean and median daily discharge, East Fork 

River near Big Sandy, Wyoming, water years 1939-92.

1.01

100

RECURRENCE INTERVAL, IN YEARS 

1.11 1.251.5 2 5 10 25 50100

99 90 80 50 20 10 4 2 1 

ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT

Figure 9. Flood-frequency curve (annual flood series), East 

Fork River near Big Sandy, Wyoming, water years 1939-92.

Characteristics of the River 15
It was observed that bankfull stage or initial 

overflow onto the flood plain near the project site 

occurred at a discharge of about 20 m3/s, which would 

have a recurrence interval in the annual flood series of 

about 1.2 years. The corresponding 1.2-year flood at 

the gaging station upstream indicates a bankfull discharge of about 26.5 m3/s at that location (fig. 9). The 

diurnal fluctuation in discharge is exemplified in 

figure 10. Early in the season, when the flow at the 

project site was derived primarily from snowmelt at 

intermediate elevations in the mountains, the peak discharge occurred at about noon of the day following 

snowmelt and at 1400 hours later in the season. The 

length of river from the project site to the high peaks of 

the Wind River Range is about 50 km (32 mi), and the 

delay between snowmelt and arrival of peak runoff is 

about 20 hours. Thus, the speed of travel of the runoff 

wave averages about 2.5 km/hr (0.7 m/s, or 2.3 ft/s).

100 FT

i i i i i i

Rising hydrograph (1980)

20

15

10

5

Falling hydrograph (1980) 

June 22

JulyS

2400 0300 0600 0900 1200 1500 1800 2100 2400 

TIME, IN HOURS

Figure 10. Diurnal fluctuation in discharge of East Fork 

River at the bedload project site.

The flow-duration curve for the Big Sandy gaging station is shown in figure 11. Daily mean discharge at bankfull stage at the station is equaled or 

exceeded about 1 percent of the time.

The year-to-year variation in annual peak discharge and mean annual flow are shown in figure 12A. 

Note that the mean of the peak discharges is 35.8 m3/s,

0.05

0.01 0.1 1 95 99 99.999.99

PERCENT OF TIME INDICATED DISCHARGE 

WAS EQUALED OR EXCEEDED

Figure 11. Flow-duration curve, East Fork River near Big 

Sandy, Wyoming, water years 1939-92.

and one standard deviation of this mean is 9.34 m3/s. 

It also is interesting to note that the peak discharge of 

the year increases greatly as the mean flow for the year 

increases (fig. 12B). The larger the snow pack in the 

mountains, the larger the mean flow for the water year. 

The volume of the peak alters the annual peak discharge as well.

The Bedload Project Site

The East Fork River, between its exit from the 

Pinedale moraine and its junction with the New Fork 

River, flows in a meandering channel sporadically 

impinging on low and high terraces of unconsolidated 

sand and gravel. In a few places it has eroded steep 

banks of poorly consolidated bedrock of the Wasatch 

Formation. The river has moved rather freely, developing a flood plain vegetated with willow. Many 

meander scars and oxbows and much scroll topography can be seen. Only two important tributaries enter 

along this 30-km reach: Muddy Creek and Silver 

Creek. Muddy Creek heads in a broad irrigated terrace 

surface, and derives most of its flow in modern times 

from irrigation return flow. Silver Creek heads in the 

mountains and derives its flow from spring snowmelt. 

The character of the East Fork River valley and its 

relation to Muddy Creek can be seen on an aerial photograph (fig. 13).

16 Bedload and River Hydraulics—Inferences from the East Fork River
70

Q

O 60

u

50

40

y

3 30

u

LLI o OH^u

cc

<

I 10

— — +1 Standard deviation

— Mean

— -1 Standard deviation

_MEAN_A_NNUAL FLOW

70

60

^40

30

20

10

<LJJ

1935 1945 1955 1965 1975 1985 1995

WATER YEAR MEAN ANNUAL FLOW 

IN CUBIC METERS PER SECOND

Figure 12. A, Year-to-year variation of annual peak discharge and mean annual flow, and B, Relation of annual peak 

discharge to mean annual flow, East Fork River near Big Sandy, Wyoming, water years 1939-92.

An important practical necessity in the choice of 

a location for the bedload trap was a road bridge 

allowing us to cross with equipment during construction. The site chosen was about 65 m downstream 

from a small wooden bridge (fig. 14). Near the left 

bank downstream from the bridge, there always was 

some accumulation of sand where a point bar would 

naturally tend to form on the convex bank. Although 

two log bents supporting the bridge were in the water, 

the bridge seemed to have no effect on our measurements. The occurrence of a bend downstream from 

the site also had little effect, except that it tended to 

increase slightly the water-surface slope below the 

trap.

The project site at low flow and high flow is 

shown in figure 15. The natural channel cross section 

at the site where the bedload trap was built is shown in 

figure 16, and the discharge rating curve at that site is 

shown in figure 17.

Water temperature in May and June typically is 

in the range of 5 to 10°C. For example, in 1975 the 

mean daytime temperature of the water at the bedload 

trap was 7.1°C during the last week of May, 4.2°C 

during the first 2 weeks of June, and 7.5°C during the 

third week of June.

Bed Material And Its Distribution

When the bedload project site was chosen, the 

senior author thought that the river carried primarily 

fine to medium gravel, for though sand can be seen, on 

casual inspection what meets the eye are numerous 

gravel bars protruding above the water surface at low 

flow. This impression was reinforced by the profusion 

of cobbles and boulders in the channel about 10 km 

upstream from the site at State Highway 353, as shown 

by curve 1 in figure 18. There, the median particle 

size (D5Q) is 90 mm.

Sand is far more prominent in the bed material 

than had earlier been supposed; the median size at the 

bedload trap is 1.25 mm, as can be seen on curve 2, 

figure 18, with 23 percent by weight greater than 

10 mm. The actual moving bedload caught in the trap 

(curve 3) has nearly the same Z)50, 1.13 mm, but contains only about 3 percent bed material exceeding 

10mm.

The areal distribution of bed material in the 

reach near the project site is shown in figure 19. The 

actual site for the trap was specifically chosen to be 

immediately downstream from a central gravel bar 

(island) and at the head of a deep pool that characterizes the meander bend downstream.

Characteristics of the River 1 7
100 200 300 400 500 METERS

i_____i

500 1,000 1,500 FEET

Figure 13. Aerial view of East Fork River valley upstream from the site of the bedload trap. Muddy Creek enters 

from the southeast in lower part of the photograph. Project site is approximately 600 meters north of area shown 

at top of photograph.

18 Bedload and River Hydraulics—Inferences from the East Fork River
B

Figure 14. Research site before installation of the bedload trap. A, Looking southwest, showing location of site (at vehicles); flow is left to right. B, Looking upstream; 

wood bridge is 65 meters upstream from the trap site.

Characteristics of the River 19
Figure 15. Site of the bedload trap at low flow and high flow. A, Looking downstream at low flow, showing 

the low gravel bar left of center of the channel and just upstream from the trap. At far left can be seen the levee 

built to prevent the water from flowing into the diversion channel, the spoil from which rises above the flat 

lower surface. B, Looking upstream at a stage at which high flow inundates the flood plain.

20 Bedload and River Hydraulics—Inferences from the East Fork River
2.5 

2.0

Q

> 1.5

DC

DC I—CO

<LU

oz~

o

0.5 

0

-0.5

-1.0

LEFT BANK

s, sand 

g, gravel

V

RIGHT BANK

0 10 20 30 

DISTANCE. IN METERS

40 50

Figure 16. Cross section of East Fork River channel at the site of the bedload trap, prior to construction.

LLJLU

U

0.2

0.1

1 10 100 

DISCHARGE, IN CUBIC METERS PER SECOND

Figure 17. Discharge rating curve for East Fork River at the 

site of the bedload trap.

1 10 100 500 

SIEVE SIZE. IN MILLIMETERS 

EXPLANATION

1 BED MATERIAL FROM RIVER AT STATE HIGHWAY 353

2 BED MATERIAL AT PROJECT SITE-Composite of 232 samples 

collected along a 200-meter reach (Emmett, 1980a, table 1)

3 BEDLOAD AT PROJECT SITE-Weighted composite, 1976 

(Emmett,1980a, table 2)

Figure 18. Size distrioutions of bed material in East Fork 

River at State Highway 353, and of bed material and 

bedload at the project site.

Characteristics of the River 21
Gravel bar,

EXPLANATION

FINE SAND

MEDIUM SAND

MEDIUM TO COARSE SAND

MEDIUM SAND TO MEDIUM GRAVEL

FINE TO MEDIUM GRAVEL

MEDIUM TO COARSE GRAVEL BEDLOAD 

TRAP

Island bar

<c50 METERS

0 100 FEET

Figure 19. Distribution of bed material in the project reach, July 12, 1976. 

22 Bedload and River Hydraulics—Inferences from the East Fork River
The number of rocks larger than 22 mm that fell 

into the bedload trap was surprisingly small in most 

field seasons. There were a few days when some 

coarse particles were caught, but because of the paucity of data, relations of the degree of coarseness to 

stage or any other hydraulic parameter were not obvious. There was some indication of an increase in size 

as transport rate increased.

Hydraulic Geometry

In the natural channel cross section before the 

bedload trap was constructed, width increased slightly 

with increasing stage. The equations for the hydraulic 

geometry (width, w; mean depth, d; mean velocity, u\ 

cross-sectional area, A) in metric units, for water discharge, <2, in m3/s, were:

w = 14.6 Q°-06 (m),

(m),

°-37 « = 0.35<2- (m/s), and

(m2).

(1)

(2)

(3)

(4)

When the bedload trap was built, the width of 

the gated slot was constant with stage, and the flow 

above the width of the bedload trap was designated 

"effective water discharge." The equations for the 

hydraulic geometry of the effective water discharge, 

<2, became:

w = 14.6,

d = 0.18<2°-65,

u = 0.39 <2°-35, and

A = 2.6 <2a65.

(5)

(6)

(7)

(8)

The relation of slope to discharge is more complicated. The value of water-surface slope, S, is highly 

dependent on the length of the reach used for measurement, and it is not obvious over what river length 

slope should be measured for any particular computation, as will be demonstrated later. We began slope 

measurements in 1968 with a leveling survey of the 

water surface at near-bankfull stage, extending from a 

place upstream from Muddy Creek to a point downstream from the bedload project site. A slight downstream flattening of slope was measured, presumably 

associated with a decrease of bed-material size with 

little change in discharge. Downstream from Muddy 

Creek the mean slope was close to 0.0007, the value 

used for a variety of computations. Later in 1976, an 

effort was made to measure local slope of the watersurface in the vicinity of the bedload trap. These surveys confirmed the average value of 0.0007 in general, 

but indicated that slope increased somewhat with discharge. In 1978 the reach from the county road bridge 

to a place 274 m downstream was surveyed nearly 

every day. The shots made to the water surface on 

both banks were spaced at about 10 m in the critical 

subreach near the bedload trap. The 1978 survey 

extended downstream around the meander loop below 

the project site.

Values of water-surface slope in the vicinity of 

the bedload trap plotted against discharge showed 

scatter comparable to the natural variance of bedload 

data. Thus, slight changes of slope with discharge 

were insignificant. Therefore, the use of a mean value 

of 0.0007 throughout appeared justified. We discuss 

in a later section the variation of slope between pool 

and riffle, and differences in slope that arise from the 

choice of channel length over which slope is measured.

The friction factor, u/u* (u* is the shear velocity), at the bedload trap is dependent on the relation of 

velocity to depth, slope being constant. There is considerable scatter of values, but the relation for all the 

years of record shows no significant variation with discharge and can be expressed as a constant value of 

12.2. Pools and riffles have somewhat different relations of u/u* to discharge, as will be discussed later.

The upshot of these considerations may be 

stated fairly as follows. The increase of velocity with 

discharge in the East Fork is nearly the same as the 

average of many rivers (Leopold and others, 1964). 

Depth increases somewhat more with discharge than 

the average, and width increases less than the average, 

but all the exponents are within the range usually 

observed. Slope surveyed over river lengths of 

20 widths or more can be considered constant at a 

value close to 0.0007, but in shorter reaches slope varies with discharge, depending on the particular combination of pool-and-riffle sections included in the 

surveyed reach. Hydraulic resistance, or values of the 

friction factor u/u*, varied little with discharge at the 

project site.

Characteristics of the River 23
DEVELOPMENT AND OPERATION OF 

THE BEDLOAD TRAP

A bedload trap that could be disassembled and 

moved, even though laboriously, from one river to 

another would be desirable. It was with this objective in 

mind that the initial development was directed. The 

general principle chosen was to have an open slot at 

streambed level into which the moving load would fall, 

the slot sufficiently wide that particles would not be able 

to jump across the opening. The trap would have to be 

emptied periodically. Doors or gates that would close 

the slot would be necessary so that when the emptying 

mechanism was not in operation the trough would not 

immediately fill with sediment.

Initial Design

The first design of the bedload trap consisted of a 

metal tube of rectangular cross section made of units 

that could be bolted together, with enough units available to completely cross the streambed. Each unit had 

an individual gate that slid parallel to the streambed, 

and, we hoped, could be closed when the machine was 

not in operation. The emptying device was an endless 

belt that would move toward one side of the river and 

dump its sediment while going over a pulley or cylindrical roller. The returning part of the endless belt was 

protected from the sediment load by the overlying loop 

of the belt. The sediment accumulating at one end of 

the endless belt was to be lifted to the level of the streambank by another endless belt on which were attached 

a series of perforated cups. The horizontally sliding 

gates for closure of the slot were operated by a lever 

that could be moved by hand, for the lever extended 

upward well above the water surface. Anticipating that 

much of the sediment moving in the East Fork would be 

sand, but some gravel to 20 mm would be moved, we 

chose a slot width of 4 in. (10.2 cm). This choice 

implied that nearly all particles to 1-cm diameter would 

be caught, and from the authors' data, the efficiency for 

catching 2-cm rocks would be not less than 80 percent.

With the advice of Ralph A. Bagnold, the senior 

author designed and built an apparatus incorporating the 

features mentioned above. Installation was attempted 

on the East Fork River during 1967 at the same location 

later used for construction of the successful bedload 

trap. Photos of this initial trap are shown in figure 20.

After three field seasons (1967-69) of arduous 

work, the results were disappointing. The apparatus

was removed from the river. Despite the lack of success, this initial trial was fruitful, in that many lessons 

were learned that were incorporated in the final design. 

These lessons included the following.

It was impossible to get the rectangular metal 

tube deep enough to have its top surface flush with the 

original streambed. The tube was assembled in the 

river at low flow. It was to have been sunk into the 

channel bed by excavating a trough beneath it. However, after a trench was dug, the sand and gravel of the 

streambed continually filled in by sloughing of the 

trench banks, even though little water was flowing in 

the river. It became obvious that the flow had to be 

diverted by coffer dams, and a bypass channel had to be 

excavated to divert the flow around the site during construction.

Another problem was that the return loop of the 

endless belt inevitably collected some sediment that 

leaked around the overlying loop of the belt. Sediment 

falling on the part of the belt returning to the far side of 

the river consequently was dragged toward the far-side 

roller, where there was no mechanism to extract it. 

Thus, within a short time, sediment jammed that roller, 

and the friction caused the belt to stop. The only way to 

prevent this action was to have the return loop of the 

belt above the water, so that all the submerged part 

moved sediment toward the sump, from which accumulating debris could be removed. This meant that the 

return loop of the endless belt must be supported subaerially by a bridge.

Finally, gates to close the slot need to be designed 

so that during closure there are no frictional surfaces 

that can be jammed by sand. The original gates were 

operated manually. Sand caused so much friction that it 

was difficult to transmit the required mechanical energy 

to those gates between the middle and the far side of the 

river. This experience suggested tainter gates with 

curved surfaces rotating about a horizontal axis, and 

operated by hydraulic pressure, rather than a manual 

lever.

Successful Design

The successful bedload trap consisted of four 

principal parts:

1. A concrete trough constructed across the river, the 

top of which was flush with the streambed. The 

top surface of the trough had an open slot extending across the full width of the channel. The slot 

could be closed by eight tainter gates operated

24 Bedload and River Hydraulics—Inferences from the East Fork River
B

Figure 20. The initial unsuccessful bedload trap installed at the same location where the successful machine was 

constructed later. A, The long metal tube containing the endless belt could not be lowered into the streambed because 

the excavation continually sloughed. B, The metal tube did not reach all the way across the channel to the left bank.

Development and Operation of the Bedload Trap 25
separately by hydraulic pressure carried through 

flexible rubber tubes. Each of the eight gates was 

1.83 m (6.0 ft) in length. The slot opening was 

0.203 m (8 in.) wide. The width of the slot was 

guided by laboratory experiments of Poreh and 

others (1970), who had anticipated that a successful bedload trap would someday be constructed as an open slot into which sediment 

could fall. They showed that the efficiency of 

such a slot depends on the ratio of slot opening 

(width, w) to size of sediment (D). The efficiency increases as this ratio, w/D, increases, 

approaches 100 percent when the width is 

20 times the particle size, and equals 100 percent 

when the ratio is above 40, for all flow conditions 

tested.

2. An endless rubber belt 0.305 m (12 in.) wide, lying 

at the bottom of the concrete trough, threaded 

around large rollers or pulleys, installed in concrete wells on each bank of the river, and returning subaerially to the far bank on rollers 

supported by a suspension bridge.

3. An endless belt operating on a nearly vertical axis 

and carrying perforated buckets that scooped 

accumulating sediment from the bottom of the 

receiving well, lifted the sediment 3 m above the 

ground surface, and dumped it into a tapered hopper sitting on a large weighing scale. The hopper 

was periodically emptied by opening a bottom 

door.

4. A horizontal endless belt, with one end beneath the 

evacuating door of the sediment hopper, that 

moved the sediment from the hopper to a transverse endless belt 12m downstream, which in turn 

dropped the sediment into the flowing water of the 

river to be carried downstream in a normal manner.

In the winter of 1971-72, the senior author drew 

the designs for the bedload trap, chose the principal 

dimensions, and made engineering drawings of the various parts. These drawings were then taken to an architectural engineering firm for the drafting of construction 

drawings and for the preparation of engineering specifications. From these final drawings the schematic plans 

of the machine, shown in figure 21, were prepared. The 

engineering drawings are in the Leopold file in the Bancroft Library of the University of California, Berkeley.

In the summer of 1972, after the main snowmelt 

runoff ceased, construction of the redesigned bedload 

trap was begun. The construction phase was supervised

by Robert M. Myrick, appointed by the senior author as 

project construction engineer. His was not an easy job.

A bypass channel was cut across the neck of the 

river curve downstream from the trap location. A coffer 

dam was built across the river to divert the flow into the 

bypass. The ground-water table was close to streambed 

level, and though there was no flow through the construction site, when the wells were excavated preparatory to pouring concrete, water in the excavation could 

not be pumped out fast enough to keep up with inflow. 

The bottom slab of each well had to be poured under 

water. The site is far distant from any power source, so 

electrical power was generated onsite by a large propane-fueled motor-generator.

As can be seen on the river cross section before 

the trap was installed (fig. 16), the deepest part of the 

channel was near the right bank. Depth gradually 

decreased toward the left bank. When the concrete 

trough was constructed in the channel bed to hold the 

gates and the endless belt, the surface of the concrete 

tended to follow the original cross slope of the bed, and 

was set 0.4 m deeper near the right bank (gate 1) than 

near the left bank (gate 8). Photographs of various parts 

of the installation are shown in figure 22.

The concrete well on the right bank was deep 

enough that the top surface of the belt was considerably 

above the bottom of the well. Before the belt went 

around the first roller, the sediment was scraped from the 

belt and fell to the bottom of the well. The perforated 

cups on the near-vertical endless belt reached to the bottom of the well and scooped up accumulating sediment, 

lifting it above the ground and dumping it into the hopper. The weight of the sediment accumulating in the 

hopper was continually monitored. The sediment was 

allowed to accumulate to about 115 kg, then the bottom 

hatch was opened. The sediment dropped onto the 

downstream belt and, on its way, was sampled by scooping portions of the bulk in transport on the belt.

Operation

During the runoff seasons from 1973 to 1979, 

with the exception of 1977, a year of low runoff, the 

bedload trap was in operation nearly every day from late 

May to mid-June. A typical run for bedload measurement will be described.

The water-stage recorder at the left bank well was 

inspected. The motor-generator was inspected for oil 

and set in operation. In the control trailer containing the 

electrical control buttons and the levers for activating the

26 Bedload and River Hydraulics—Inferences from the East Fork River
Left bank

rframe Cable (1.9 centimeters diameter)

Right bank

A-frame

Concrete trough 

(gate assembly)

Lift belt 

(perforated buckets)

Riverbank well

Belt ' 

tension

B

Belt

^Riverbank well

PLAN VIEW

,-Belt tension

',{. Belt drive

SIDE VIEW

Figure 21. Simplified engineering drawings of mechanism for the bedload trap. A, Downstream view of suspension bridge, 

deep concrete wells on each bank, and concrete trough in streambed. B, Plan view showing location of belt-drive motor and 

lift-bucket endless belt on right bank. C, Diagram of the endless belt under water in the concrete trough, and carried 

subaerially by the suspension bridge on its return to the left bank. Details of lift belt (perforated buckets) not shown.

Development and Operation of the Bedload Trap 27
Figure 22. The bedload trap on East Fork River. A, View downstream showing suspension bridge, concrete wells 

on each bank, and control trailer on right bank. B, View from left bank at low flow. The concrete trough in the streambed is partly emergent in the foreground; the slot into which sediment falls is closed by the metal gates. C, D, E, F, 

and G, on following pages.

28 Bedload and River Hydraulics—Inferences from the East Fork River
Figure 22. The bedload trap on East Fork River (continued). C, Trough in streambed seen from left bank at low flow; 

the nearest gate is open, but all other gates are closed. D, View from right bank along the length of the suspension 

bridge. In the foreground is the main motor and in the middle ground are two of the drums that drive the endless belt. 

The belt returns to the left bank on rollers under the walkway of the bridge. E, The near-vertical endless belt with lift 

buckets; these reach into the deep well on right bank, from which they lift sediment to the hopper for weighing; the 

hopper is the tapered vertical tube in center of photograph.

Development and Operation of the Bedload Trap 29
Figure 22. The bedload trap on East Fork River (continued). F, The endless belts leading first downstream from 

the weighing hopper, and the orthogonal belt extending over the river for returning bedload to the channel. G, 

View from right bank looking upstream; the endless belt in the foreground carries sediment back to the river after 

it is weighed and sampled.

30 Bedload and River Hydraulics—Inferences from the East Fork River
hydraulically operated gates, the main belt in the 

trough of the trap was started at the lowest possible 

speed with all eight gates closed. The lift-bucket belt 

also was started. It was first necessary to assure that 

the main belt and the receiving right-bank concrete 

well were clean of sediment, so the belt was run with 

all gates closed for about half an hour.

During the run with all gates closed, the weight of 

the receiving hopper was recorded in pounds each 

minute. Some sediment may have remained in the 

receiving well or on the main belt, and this residual was 

monitored until the hopper recorded less than about 

3 Ib/min (1.4 kg/min), considered to represent a zero 

load. Then the first gate was opened, and the speed of 

the main belt was increased to its normal value of about 

0.3 m/s. At this speed, sediment from the farthest gate 

reached the receiving well in about 0.8 minute. Thereafter, for not less than 30 consecutive minutes, the 

weight of the hopper and its accumulating load were 

recorded each minute. Gage height was recorded at the 

beginning and end of the measuring period by observing the staff gage. During many runs, the incremental 

weight was plotted as a function of time to obtain a 

visual picture of the transport rate. When the hopper 

had received about 250-300 Ibs (113-136 kg), the 

downstream belt and the transverse belt were activated, 

the hopper door was opened, evacuating the load, and 

samples were scooped off the moving belt, bagged, 

tagged, and stored for later weighing while wet and for 

subsequent drying for size analysis.

The gate then was closed, and the main belt was 

operated for about half an hour until all sediment had 

been removed and the received weight had dropped 

again to about 3 Ib/min (1.4 kg/min). Next, the second 

gate was opened, and the process repeated until all 

eight gates had been used. The entire operation lasted 

about 8 hours. At low flow, when sediment transport 

was small, the eight gates were all opened, and the 

total bedload of the river was measured at one time. 

At the end of the day all gates were closed, and operation of the main belt was continued to evacuate as 

much sediment as possible from the trap.

The variation in load for a typical run at low discharge is shown in figure 23A for a time when the bed 

was clearly visible over much of the slot length and no 

dunes were visible. Transport rate for the whole river, 

all gates open, averaged about 14 kg/min at low discharge. A similar plot at higher discharge (fig. 23B) 

shows large fluctuations in transport rate, indicating

the passage of sand dunes, the peaks separated in time 

by 20 to 30 minutes.

Discharge was measured using a current meter 

each day for which the stage was not well represented 

on the discharge rating curve. During several seasons, 

a two-traverse measurement of bedload was made from 

the suspension bridge using a Helley-Smith sampler, 

each measurement consisting of 48 half-minute samples across the river, as described in detail by Emmett 

(1980a). These measurements were repeated daily, or 

more often, throughout the period of bedload-trap 

operation.

Bedload mass was measured on a large weighing 

scale that carried the weight of the hopper in which the 

moist sediment accumulated. Weight in pounds was 

recorded each minute, read visually from the scale. 

These successive accumulated weights were subtracted 

to determine the pounds of wet sediment per minute. A 

run lasted 30 minutes or more. The weights were averaged to obtain pounds (wet) per minute. It was determined experimentally that a dry sample in a plastic bag 

weighed 0.85 of the wet weight. Thus, immersed mass 

was calculated as follows:

(Immersed mass, in kg/s) = (Wet weight, in Ib/min)

x

0.85

2.205

2,640-1,000

2,640

J_ 

60

(9)

where the first term converts from wet weight in 

pounds to dry mass in kilograms, the second term converts from dry mass to immersed mass, and the third 

term converts from minutes to seconds.

To get the unit bedload-transport rate, divide by 

14.6 m, the width of the trap, to yield immersed mass 

in kg/m-s. This is the unit bedload-transport rate, zb, 

which is listed in table 3 at the back of this report.

BEDLOAD AND RIVER HYDRAULICS

The first relation, presented in figure 24, is the 

usual bedload rating defined by simultaneous values of 

measured unit bedload-transport rate (rate per meter of 

channel width) and the effective water discharge (that 

part of the total discharge that passed over the 14.6-m 

width of the bedload trap). Data are from table 3 at the 

back of this report. The unit suspended-sediment 

transport data for measurements at the bedload trap, 

typified by data from 1979 (Emmett and others, 1980),

Bedload and River Hydraulics 31
25

20

15

10'

June 6, 1973

Discharge, 11.7 cubic meters per second

55

50

10 20 30 40 50 60 70 80 90

- 45

Q

40

35

30

25

20

15

10

5

0

May 26, 1973

Discharge, 16.1 cubic meters per second

B

"10 20 30 40 50 60 70

ELAPSED TIME, IN MINUTES

80 90 100

Figure 23. Typical measurements of weight of sediment accumulating in the hopper as a function of 

time. Weights are expressed as increments during each 1 minute of time. A, River at a low discharge. 

All gates open; few or small dunes were moving. B, River at a higher discharge. All gates open; incremental 

weights fluctuate as dunes pass into the trap.

are shown in figure 25. As is true with most sediment 

ratings, points scatter widely, although the transport 

rate is extremely sensitive to discharge.

The variance observed in bedload data has 

become more understandable in the light of recent measurements and observations of movement on the streambed. Some zones or areas of the bed become active, 

whereas adjacent areas, apparently identical, are without 

motion. These areas change in an apparently random 

manner, from active to inactive. A small area of motion,

affecting one or only a few grain diameters in thickness, 

may result in a very low bedform front that might be 

described as a long flat dune having a very small amplitude, but differs from a dune in that avalanching down 

the front does not occur. A description of these "bedload sheets" is given in Drake and others (1988).

This sporadic and random motion explains part 

of the variance seen in plots of bedload data. To 

smooth this variance in data collection in a HelleySmith sampler, a large number of individual measure32 Bedload and River Hydraulics—Inferences from the East Fork River
0.5

0.1

0.05

_

O

—

< LOJ

DC 0-

Q 0.01

O o

°- 0

5 LU

< Q

O LU

_l CO

Q DC

LU LU

CO "5

0.005

0.001

0.0005

0.0001

2 points

n 1973 

+ 1974 

o 1975

• 1976

• 1978

• 1979

1 5 10

EFFECTIVE DISCHARGE, 

IN CUBIC METERS PER SECOND

50

Figure 24. Measured unit bedload-transport rate as a 

function of effective water discharge, East Fork River at 

bedload trap.

ments are needed. Having made thousands of such 

measurements, the junior author has recommended a 

reasonable compromise consisting of about 20 equally 

spaced samples across the channel. The time of collection for each sample usually is either 30 or 60 seconds. 

This process is repeated once, so that one measurement 

is the average of 40 bedload samples. The efficacy of 

this procedure was demonstrated by comparison of 

simultaneous measurements in the bedload trap and by 

the Helley-Smith sampler (Emmett, 1980a).

The next step in developing sediment rating 

curves for bedload is to compare different rivers using 

a common set of coordinates. This step may be exemplified by the relation described by Leopold and 

Emmett (1976, p. 1003), in which the data for several

0.1

0.05

0_ LU 

CO °-

II

7Z Q

, J LU

Q CO

LU OC

Q LU

z 2

LU ^

Q- ^ CO —

3 CO

CO ^

I- <

0.01

0.005

0.001

0.0005

1 5 10 50 

DISCHARGE, IN CUBIC METERS PER SECOND

Figure 25. Measured unit suspended-sediment transport 

rate as a function of discharge, East Fork River at bedload 

trap (1979 data).

rivers were expressed in the form of a plot of unit bedload-transport rate as a function of unit stream power. 

The graph consists of a family of curves delineating the 

relation for different sizes of debris. The steep slope 

and great sensitivity of the transport rate at low values 

of stream power give rise to large variability in transport rate for small changes in available stream power.

Refining this type of empirical plot, Bagnold 

(1977) showed that the extreme sensitivity of the graph 

at low values of power could be reduced by plotting on 

the abscissa GO - co0, the available power per unit width 

minus the power needed for initial motion. The same 

strategy has previously been used in bedload equations 

in which load is a function of the difference between 

shear stress available and shear stress needed for initial 

motion.

The value of co0, power at initial motion, can be 

estimated by transposition of the Shield's equation. 

The available power per unit width is

OS CD = y — = 1.000 udS (in mass units) , (10) 

w

where y is the specific weight of water.

Bedload and River Hydraulics 33
The Shields threshold criterion, G, is of grain sizes was used, Bagnold found that

for grain size (particle size),

D, where TO is shear stress at initial motion; in mass 

units, y = 1,000 kg/m3 ; Ss is the ratio of grain density 

to fluid density; (5S-1) = 1.64; depth, d, is in meters; 

and grain diameter, D, must be expressed in meters for 

consistency of units. G has a dimensionless value of 

0.04 for turbulent steady flow. Velocity at initial grain 

motion, MO, is approximated by 5.75 M* log 12 d/D, 

where in mass units, shear velocity is

.-1/2

M * ~ *o _ r 99-- 8T8Tooi I/2

p - Li.oooJ (11)

g is acceleration due to gravity, and p is the density of 

water.

In mass units, power at initial motion in kg/m-s is

co0= TO M O = (0.04 x 1640 x D) 3/2

X ——— 

98 -'•*-' 1J

. , f in X5.751og ——\2d L ^Ll

= 65.63/2 D3/2 (0.0098) 1/2 x 5.751og ——

(12)

The size, D, used is D50 (50 percent finer) of the 

transported load and must be expressed in meters. The 

measured values of unit bedload-transport rate, ib, are 

plotted against excess stream power, GO - co0, for the 

East Fork River data in figure 26.

Another source of variance in bedload data is 

the variation of transport rate at constant stream 

power. The transport rate varies both with flow depth 

and with bed grain size. These effects have been 

determined quantitatively by R.A. Bagnold. Using the 

flume data of Williams (1970), in which runs were 

made at chosen depths of flow, Bagnold (1980) found 

that at constant power,

d

,-2/3 (13)

where ib is transport rate and d, mean flow depth. 

Analyzing the Gilbert (1914) data, in which a variety

(14)

where D is expressed as the median (D50) size of the 

transported load.

0.5

0.1

0.05 -

< jDC Q

< LU 

DC D_

l- Q 0.01

< Q

O LU

_l CO

Q DC

LU LU

CO •>

0.005

0.001 -

0.0005

0.0001

D 1973 

+ 1974 

o 1975 

A 1976

• 1978

• 1979

0.1 0.5

EXCESS STREAM POWER (ft>-ft>0), IN KILOGRAMS 

PER SECOND PER METER OF WIDITH

Figure 26. Measured unit bedload-transport rate as a 

function of excess stream power, East Fork River at bedload 

trap.

Because different rivers at various discharges differ widely in depth and grain size, transport rates vary 

accordingly. This has the interesting complication that 

for a constant available power, shallowing of the river 

increases its ability to transport sediments. Thus, in a 

braided river, decrease of depth increases transport rate

34 Bedload and River Hydraulics—Inferences from the East Fork River
per unit of width. That is, more of the available power is 

used for sediment transport and less for frictional loss. 

It is desirable to find some empirical relationship 

that accounts for the effect of grain size and depth. Bagnold (1986) proposed that the data from each river be 

adjusted to account for the variance due to depth and 

grain size. Using arbitrarily chosen values for reference—a standard depth of 0.1 m and a standard particle 

size of 1.1 mm—a new theoretical transport rate, ib ' , 

could be computed by adjusting observed transport rate 

as follows:

= ib (obServed) x -- b Lo.i —- Lo.oon

1/2

(15)

Following Bagnold's original expression, particle 

sizes in equation 15 are expressed in meters. When 

average values of observed transport rates in each of 

several rivers are adjusted by the above relation, the data 

plot in an unusually straight line through a range of at 

least five orders of magnitude. This general relation of 

the adjusted transport rate (from Bagnold, 1986, fig. 1) is 

given by

= 0.28(co-co0)

3/2 (16)

The general variation of transport rate as the

^

v3-power of depth and the square root of grain size 

explains the major differences among rivers, but clearly 

does not account for day-to-day variations among 

hydraulic parameters in a given river. In the East Fork, 

day-to-day variations are shown to differ from pool to 

riffle. Unusually high transport rates are measured 

downstream from a pool on the first hydrograph rise as 

the pool is scoured. Such conditions are not dependent 

on the grain-size and depth parameters, but on sediment 

availability.

Cross-Channel Variation Of Transport Rate

The location of the bedload trap was chosen 

upstream from a channel bend to the left, downstream 

from the wooden bridge of the county road, and immediately downstream from a gravel bar, just left of the centerline of the channel (fig. 19). When the trap was 

constructed, this gravel bar was centered on gate 6. Its 

character is well illustrated in figure 15A. The channel 

deepens toward the right bank, yet the data indicate consistently that the deepest section carried the least bedload. Both visually and quantitatively, the gravel bar 

was associated with more active transport than other 

parts of the channel. Small dunes were seen to extend 

laterally from this bar and arrive downstream as if the 

dunes were moving more rapidly at a distance of 1 m 

than at a distance of 0.5 m from the bar.

The cross-channel distribution of bedload transport as measured at the eight gates, averaged for discharges of 25 to 30 m3/s, is shown in figure 27. The 

lower graph shows that the deepest water is near the 

right bank (gates 2 and 3), but the major transport is 

between gates 4 and 6. Gate 6 is at the centerline of the 

gravel bar upstream from the trap. Thus, the gravel bar 

is near a shallow zone, but it is the locus of the principal 

bedload transport at discharges near bankfull, when the 

transport rate is greatest. As an example, the highest 

transport rate recorded during the 1978 runoff season 

was at gate 6 on the day of largest discharge, approximately bankfull. Thus, the product of an overall channel 

slope and a local water depth gives only a poor indication of local bed shear stress.

25

_jcc 20 -

15 -

LU< 10 -

00

CC—I 

LUQ 

Q_LU

CO 5

Ave 

pe

A

rage d 

r secor

scharg 

d

3 = 25

•••

to 30 cubic meters

•

-

X

i—co CLO:

LULU a i0.5

1.0

1.5

2.0

Values of depths are typical for the 

discharges indicated in upper graph:

B

GATE NUMBER

0 2 4 6 8 10 12 14

DISTANCE FROM LEFT END OF TRAR 14.6 

IN METERS

Figure 27. Cross-channel distribution of: A, bedload 

transport, and B, water depth, East Fork River at bedload 

trap. As plotted, the depths simulate the channel cross 

section (see fig. 16).

Bedload and River Hydraulics 35
That bedload transport is far from uniform over 

the whole width of the channel bed was demonstrated by 

the daily bedload measurements at U.S. Forest Service 

sites in the Colorado Front Range in 1989 (U.S. Forest 

Service, Fort Collins, Colo., unpublished data). In these 

mountain streams, the beds of which were medium to 

coarse gravel, 85 percent of the total bedload occurred in 

50 percent of the channel width, and 50 percent of the 

total bedload occurred in about 29 percent of the channel 

width. This cross-channel variation is not unlike that for 

the East Fork River (see Leopold and Emmett, 1977); 

this distribution becomes important when bedload transport rate per unit width is extrapolated to estimate the 

total bedload of the river.

HYDRAULIC RESISTANCE

Bedload transport rates at the trap on the East 

Fork were measured during six runoff seasons. Each 

measurement tabulated at the back of this report (table 3) 

is the result of recording accumulated weight each 

minute during several hours. These observations demonstrate that the bedload passing a particular location 

varies rapidly through a large range with time. We demonstrated time after time, that when a sampler is placed 

on the river bed at the same location at intervals of a 

minute or two, the bedload trapped in the sampler may 

vary from zero to several thousand grams.

This great variability results from two basic 

causes. First, if the grain size is in the sand range, the 

principal mode of transport usually, but not universally, 

is by dunes. Second, where the bed material is larger 

than coarse sand, sediment may move as "bedload 

sheets" mentioned earlier. In this mode of motion, a particular location on the bed changes from no motion to 

intense movement, instantaneously and randomly.

Inspection of figure 23 indicates that bedload 

movement in the East Fork is primarily by dunes. 

Dunes, then, must provide an important part of the total 

flow resistance.

Grain resistance is also a component of total flow 

resistance. Our measurements indicate a small but 

steady increase in median size, D50, of the moving load 

with increased transport rate. The median size increased 

from 0.7 mm when the transport rate was 0.007 kg/m-s, 

to 1.4 mm when the transport rate was 0.09 kg/m-s.

The most useful measure of total flow resistance 

is the dimensionless u/u* or the ratio of mean flow velocity to shear velocity. It was shown by Leopold and Wolman (1957) that for gravel bed rivers the hydraulic 

resistance can be defined by:

Jf

(17)

which is identical to the relation

= 2.8 + 5.71og--, (18)

where/is the Darcy-Weisbach friction factor, and D84 is 

bed material size 84 percent finer. Equation 18 was later 

substantiated by Limerinos (1970), and for gravel rivers 

in England a nearly identical relation was published by 

the Hydraulic Research Station, Wallingford (1977).

Though this relation represents a satisfactory 

average, many gravel rivers deviate more or less from 

the equation for reasons that are not clear. For the East 

Fork, the values of u/u* group closely within the range of 

11 to 14, averaging 12.2. The values of u/u* decrease 

slightly with increasing transport rate if computed on a 

day-to-day basis.

The bedload grain size expressed as D84 in the 

East Fork seldom is larger than about 4 mm. If ordinary 

depths were 1.2 m, the ratio d/DM was about 300. For 

this condition, the value of 16.9 for u/u* would seem 

rather smooth for gravel rivers. Even a reach-averaged 

bed material D84 of about 15 mm gives a value of 13.6 

for u/u*, the smoother end of the range of values of u/u* 

for the East Fork River. But the amplitude of the dunes 

on the bed was estimated as 10 cm. If this were the 

roughness element, then the ratio of depth to roughness 

would be 1.2/0.1 = 12, for which a corresponding u/u* 

would be about 9.0. This suggests that when dunes are 

the dominant bed form, their size may be used as an estimate of the dominant roughness height. Conversely, the 

dominant roughness element might be surmised from 

the relation of depth to u/u*.

SEDIMENT RATING CURVE COMPUTED 

FROM HYDRAULIC GEOMETRY

The hydraulic geometry equations for at-astation data give the average value of each hydraulic 

parameter for a range of discharges. Therefore, it should 

be possible to compute a sediment rating curve by substituting these values in an expression for sediment 

transport. When a sediment rating curve has been estab36 Bedload and River Hydraulics—Inferences from the East Fork River
lished by direct field measurement, the utility of any formula for computing transport rate may be determined by 

the comparison of computed and measured sediment rating curves. The possibility of computing a sediment rating curve from a formula is attractive, but needs to be 

used with caution.

As a first approximation, at-a-station curves for 

depth and velocity can be constructed from the empirical 

formulas given in the previous discussion of hydraulic 

geometry. From these constructed at-a-station curves, 

selected values may be chosen to represent a range in 

discharge. For each, sediment load can be computed 

using one of the usual formulas.

The most consistent results in our computations 

were obtained by using the Ackers and White (1973) 

formula for total load, and the sum of bedload and suspended load measured at the same discharge for measured load. The size of sediment that gave the best result 

in that formula was the D84 of the bedload caught in the 

Helley-Smith sampler. But in all computations that were 

tried using a single grain size in the formulas, such as 

D50, the computed load was too large for small values of 

discharge and too small for large discharges. That is, the 

slope of the computed sediment rating curve was less 

than the slope of the curve representing measured sediment load. However, this general technique appears 

fruitful, and additional trials in a variety of rivers is 

highly recommended.

It is an open question: what grain size should be 

considered the effective or representative size when the 

load is heterogeneous in size? Not knowing better, we 

usually assume that D50 is the most representative. It 

may not be the effective size. In fact, the effective size 

may change with water discharge or total load. Given 

that more than one bedload formula appear to compute 

too large a load at small discharges, perhaps the effective 

size should change progressively with discharge 

(Emmett and Leopold, 1977).

Scour And Movement Of Bed Material

Movement of Marked Rocks in Relation to Bed 

Shear

In early May 1969, two groups of rocks, each 

group painted a different color for identification, were 

placed on a gravel bed 257 m upstream from the bedload 

project site. Each group consisted of 100 rocks 22 to 

45 mm in size placed as a sheet of closely spaced rocks 

about 1 diameter thick. Recovery was made July 26,

1969, after the spring runoff, the peak of which was 

May 28, 1969, at a discharge of 29.8 m3/s and a local 

maximum water depth of about 1.8m. The local slope 

at that stage was about 0.0007, which provided a bed 

shear of 12 N/m2, which according to the Shields diagram is sufficient to move a rock of about 15 mm. 

Thirty-three percent of the green rocks moved more than 

3 m, and 90 percent of the yellow rocks moved more 

than 6 m from their original position.

On May 31,1970, three groups of painted rocks 

were placed on the gravel bar 10 to 17 m upstream from 

the project site. All rocks were in the size range 16 to 

22 mm. The peak discharge occurred June 5, 1970, at 

22.6 m3/s. After the spring runoff, a search was made on 

July 1,1970. Of 60 red rocks, all but 6 moved more than

2 m, and of 100 green rocks, all but 14 moved more than

3 m. Thus, about 87 percent of the red and green rocks 

moved some distance. Maximum water depth over the 

rock groups was 1.19 m. With a local slope of 0.0007, 

that provided a bed shear of 8 N/m2, which according to 

the Shields diagram should be capable of moving a rock 

10 mm in size.

These results indicate that for rocks placed where 

the bed material is of size similar to the emplaced rocks, 

the Shields diagram gives a reasonable estimate of 

whether the rocks should move under the peak flow 

observed. But even when adequate shear occurs, not all 

those rocks will move. This is a detail about which little 

information is available. A new type of Shields diagram 

is needed that involves heterogeneous sediment and the 

percentage of any given size that will move under given 

circumstances.

Distance Moved by Marked Rocks

The following paragraphs emphasize distance that 

rocks moved, rather than bed shear. In the coarse-rock 

groups (1969 experiment), the recovery of marked rocks 

after a single snowmelt season ranged from 21 to 

91 percent (fig. 28A). In each case, the available shear 

stress at peak flow at the site of placement was just able 

to move the size of rocks placed. In all cases, the total 

distance moved during a runoff season lasting several 

weeks was surprisingly short. Recovered rocks in the 

coarse-rock groups had moved 35 m or less. In the finerock groups (1970 experiment), 22 to 53 percent of the 

rocks placed were recovered, and most of these had 

moved less than 40 m (fig. 28B).

Bedload and River Hydraulics 37
100

Size range: 22-45 millimeters 

Placement : 1969 

Recovery: July 26,1969 

Peak discharge: 

29.8 cubic meters per second

• GREEN GROUP 

A YELLOW GROUP

Size range: 16-22 millimeters 

Placement: May 31, 1970 

Recovery: July 1, 1970 

Peak discharge: 

22.6 cubic meters per second

° WHITE GROUP 

X RED GROUP 

A GREEN GROUP

20 40 60 80 

DISTANCE MOVED, IN METERS

100

Figure 28. Percentage of painted rocks that moved different 

distances in East Fork River during a season of snowmelt 

runoff. A, 1969 experiment. B, 1970, experiment.

It was our experience that after a single flood season many painted rocks could be recovered a short distance downstream from the point where they were 

placed. After a second season, a few could be found, 

and after three seasons none could be found. Thus, we 

observed that even when shear stress was available to 

move rocks of a given size, by no means were all such 

rocks moved an appreciable distance. Given time, however, all would move eventually. It seems probable that 

where a rock of gravel or cobble size moves at all, it is 

likely not to move far in a single season. It is as if individual rocks were plucked out of a group and soon 

replaced. This action is different from the action in those 

reaches where the streambed was covered with sand that 

scoured and subsequently filled during the same season.

On one cross section, scour chains were set in the 

streambed as described by Leopold and others (1966, 

p. 215), and the painted rock group was placed near the

chains to determine if scour to some depth was associated with movement of surface rocks. It was found that 

painted rocks were carried away, whereas the chains 

remained at the bed surface, indicating that removal of 

rocks was only to a depth of one rock diameter. This 

finding is in agreement with our observations of rock 

removal and replacement on the surface of a gravel bar 

on a perennial river in Maryland.

The total distance rocks moved over several seasons is indicated by the following. On May 26,1971, 

three groups of painted rocks—16, 22, and 32 mm in 

size—were placed in the East Fork River downstream 

from the mouth of Muddy Creek. Three rocks of 22 mm 

size and three of 16 mm were found August 28,1975, at 

a location 3,670 m downstream from where they had 

been placed. Thus, they moved about 3.7 km in 4 years.

These observations, combined with the relative 

dearth of medium gravel to cobble size caught in the 

bedload trap, imply that gravel movement is sporadic 

and for only short distances in a single season, although 

there are numerous gravel bars seen in the river. These 

bars must be rather stable, losing and gaining rocks a 

few at a time—a process that maintains the shape and 

position of the bar over long periods of time.

Each of the above conclusions was corroborated 

by a more extensive field measurement project in nine 

mountain streams in Colorado in the spring runoff season of 1989. Rocks chosen from the bed surface representing size D35 , D50, and DM were collected, painted, 

and placed in straight lines across the channel. A total of 

30 such lines comprising 769 rocks varying in size from 

39 to 250 mm were observed each day during the snowmelt runoff season (Leopold and Rosgen, 1991).

From this detailed program of observation, several conclusions were reached—all in general agreement 

with our results on the East Fork. It was found that 

65 percent of all the rocks moved during the season, 

even though none of the nine streams reached bankfull 

discharge. The distance moved was relatively small during any one movement, usually less than a few meters. 

Some rocks moved more than once, and a few as many 

as four times. About the same percentage of the large 

rocks, D84, moved as did the smaller, D35 , size.

Sand Marked by Fluorescent Dye

The alternate scour and fill of pool and riffle sections has been detailed by Emmett and others (1983). 

Further detail on this process is provided by our measurements of particles marked with fluorescent dye. 

Sand so marked was placed as a line source across the

38 Bedload and River Hydraulics—Inferences from the East Fork River
channel section at 3,037 m upstream from the bedload 

trap. There was surprisingly little difference in the distance moved as a function of particle size. For example, 

16 days after injection, the peak number of particles of 

various sizes was recorded at the following distances 

downstream from the point of injection:

2,156.61

Particle size 

(millimeters)

0.25 - 0.5

0.5 - 1.0

1.0-2.0

2.0-4.0

Larger than 4.0

Distance moved 

(meters)

450

350

380

260

280

In this study, the daily downstream displacement 

of the peak concentration (approximate centroid) for 

tracer particles of size 0.5 to 1.0 mm was about 30 m. 

During the full runoff season in 1979, which lasted 

22 days, the total movement of the bulk of marked particles of this size was 650 m (Ernmett and others, 1983; 

Emmett and Myrick, 1985).

Thus, the downstream speed of sediment particles 

is slow, on the order of 0.01 to 0.1 percent of the mean 

flow velocity. The volume of material scoured and 

moved is large, but because of its slow downstream 

velocity, the total distance moved is limited. These 

details have been shown quantitatively by the data collected on the East Fork, much of which has been published (see especially the references in Emmett and 

others, 1983).

Water-Surface Topography

Cross-Channel Profile

In a straight reach of river, there usually is a topographic ridge in the water surface near the centerline of 

the channel. This ridge has been observed in every survey we have made where it was possible to measure 

with sufficient accuracy to show such detail. Examples 

are shown in Leopold and others (1964, p. 283) and 

Leopold (1982b). The East Fork is another example.

Cross-channel profiles were measured from the 

suspension bridge at the bedload trap (shown in fig. 29 at 

high flow). Elevations were surveyed at the centerline of 

each gate of the trap.

LU . o nJ

U- <

o co

^ cc

O £

h: LU

.60-

.59-

.58

2,156.57

May 27, 1979 

1645 hours

May 27, 1979 

0915 hours

GATE NUMBER

2 4 6 8 10 12 14 

DISTANCE FROM LEFT END OF TRAR 14.6 

IN METERS

Figure 29. Cross-channel profiles of the water surface, East 

Fork River at bedload trap, May 27,1979. Average 

discharge for May 27 was 28.5 cubic meters per second.

The water-surface elevation was low at the left 

bank and increased 13 to 24 mm toward the right bank, 

then decreased 3 to 9 mm in the last several meters. 

Although the channel is relatively straight at the bedload 

project site, the last bend upstream from the highway 

bridge was toward the left, so the general rise of water 

surface toward the right side of the channel may be due 

to the residual superelevation from that bend upstream. 

The marked drop in elevation in the right one-quarter of 

the channel must be attributed to some other mechanism, 

overcoming the residual superelevation due to curvature.

As postulated by Gibson (1909), and elaborated 

with river measurements by Leopold (1982b), we 

believe that the topographic high is attributable to two 

circulation cells in which water at the surface converges 

near the river centerline, and water at the bed diverges. 

These two cells do not remain of equal strength, and the 

position of the topographic ridge depends on the relative 

size and strength of the two cells. In very wide rivers 

there are several cells, some being drivers and some 

being driven.

Topography in a Straight Reach

In the East Fork between Muddy Creek and the 

project site, there are two prominent straight reaches of 

channel. One is 250 m or 17 widths in length, including 

three riffles and two pools of unequal length. The plan 

view of that reach is shown in figure 30. On four occasions during the 1979 spring runoff season, leveling surBedload and River Hydraulics 39
Date: May 27,1979 

Discharge: 33 cubic meters per second 

Reference elevation: 2,158 meters above 

sea level

Date: May 28, 1979 

Discharge: 29 cubic meters per second 

Reference elevation: 2,158 meters above 

sea level

I

0 300 FEET 

(scale approximate)

EXPLANATION

—— eoo —— WATER-SURFACE CONTOUR—Shows elevation of water surface, in 

millimeters above reference elevation. Contour interval 10 millimeters.

• 2800 CHANNEL CENTERLINE-STATIONING POINT—Number indicates 

distance upstream from bedload trap, in meters

Figure 30. Water-surface contours for decreasing values of discharge in a straight reach of East Fork River about 

3 kilometers upstream from bedload trap. A, May 27, 1979. B, May 28, 1979. C, June 5, 1979. D, June 21, 1979.

40 Bedload and River Hydraulics—Inferences from the East Fork River
Date: JuneS, 1979

Discharge: 11.5 cubic meters per second 

Reference elevation: 2,158 meters above 

sea level

Date: June 21,1979 

Discharge: 4.3 cubic meters per second 

Reference elevation: 2,157 meters above 

sea level

Figure 30. (Continued)

100 METERS

_I

300 FEET

(scale approximate)

Bed load and River Hydraulics 41
veys of water surface along both right and left banks 

were made, including: high flow, flow above bankfull, 

and low flow. Elevations were read to nearest millimeter at points averaging 20 m apart. On the maps in 

figure 30, contours are drawn on the water surface 

with an interval of 10 mm. This choice of contour 

interval is larger than the precision of measured values. The variance due to random survey error, temporal stage changes, and minor local inconsistencies are 

thus not significant.

The four maps (fig. 30) show water-surface 

topography for decreasing values of discharge. The 

first obvious characteristic is the superelevation due to 

curvature, prominent between stations 3250 and 3330 

and between stations 2900 and 3000; the amount of 

superelevation is greatest at the highest discharge. A 

second characteristic is the tendency for the water surface to be steeper along the convex than along the concave bank, in agreement with the findings of other 

workers. At the highest discharge (fig. 30A), local 

steepening of water surface at station 3200 in this 

reach was caused by a pile of logs and flood debris 

against the right bank.

Note that the distance between the positions 

along the channel from superelevation on one bank to 

superelevation on the opposite bank is about eight 

channel widths. For example, the distance from station 3250 to station 3100 is 150 m, and the average 

width, bankfull, is about 19m. This is close to the 

range usually stated, 5 to 7 widths.

It has long been known, especially to the engineers associated with the maintenance of navigation 

channels on large rivers such as the Mississippi, that 

riffles, shallows, or crossings fill at high flow, while 

pools or deeps get even deeper by scour. At low flow, 

riffles or crossings scour. One could surmise that the 

reason for this scour is that the water surface becomes 

steeper as flow and depth decrease. In other words, 

the water-surf ace slope at low flow is small in the pool 

and steep over the riffle. With increasing flow, the 

slope steepens over the pool and flattens over the riffle 

until, at some high stage, the longitudinal profile 

becomes more or less straight or, in some cases, the 

pool slope may exceed that of the riffle. Measurements of this change in slope have been presented by 

Emmett and others (1983).

We were somewhat surprised when early measurements showed considerable bedload transport continuing in some locations, even when discharge had 

decreased to small values. Measurements of watersurface topography showed that the phenomenon 

described above was operative. The river at station 

3250 in figure 30A is a shallow, being the downstream 

end of a point bar. Between stations 3250 and 3300, 

the water surface is strongly superelevated against the 

concave bank, and the steepest water surface is along 

the convex bank. When the discharge had decreased 

to a low value, 4.3 m3/s, the water-surface slope in the 

vicinity of the section at station 3250 had increased 

dramatically, and this shallow (riffle) was being 

scoured and deepened at low flow (fig. 30D). The 

scoured sediment was deposited in the pool immediately downstream near the section at station 3225. 

Thus, the changing topography of the water surface 

explains and illuminates the process of deposition or 

fill in shallows at high flow followed by scour at low 

flow.

Descriptions of longitudinal profiles of water 

surfaces at various discharges are uncommon in the 

literature, and even those are insufficient to indicate 

important details of river action. Note on figure 30A 

that at high flow the superelevation against the right 

bank at station 3300 becomes zero downstream, so 

that at the succeeding riffle section at station 3100 the 

superelevation is against the left bank, even though the 

channel has no curvature to cause it. At the section at 

station 2980, the superelevation is again against the 

right bank, here explained by the curvature of the 

channel. Thus, the occurrence of bars on alternate 

sides of a channel in a straight reach seems to be associated with the rhythmic alternation of water surface 

cross-channel slope. The superelevation against one 

bank creates a cross-channel component of velocity 

near the bed away from that bank, and bed material is 

thus carried toward the bank opposite the side with 

superelevation. The bedload transport rate is then also 

greatest near the bank toward which the velocity component near the bed is directed.

The data indicate that in this manner the locus of 

bedload transport moves alternately from one side of the 

channel centerline to the other and is on the side where 

the channel is shallow; that is, the transport is greatest 

over the alternate bars rather than in the deepest part of 

the channel. This alternation of the locus of bedload 

transport has been demonstrated with measurement data 

by Leopold (1982b, figs. 13,14).

42 Bedload and River Hydraulics—Inferences from the East Fork River
CONCLUDING STATEMENT

Data from the East Fork bedload trap have been 

compiled and printed in a series of open-file reports, 

all of which are listed in the references at the end of 

this paper. The total number of numerical values tabulated and printed for this project is estimated to exceed 

1 million. All of the bedload data and corresponding 

hydraulic parameters are listed in table 3. It is our firm 

belief that publication of all the actual data from a scientific investigation of this sort is necessary if the 

results are to have long-term value to other researchers 

in the future. It is the present custom to print only 

graphs or short discussions and omit the tabulated 

data, in order to save space in the publication. But 

considering the fact that personnel, equipment, and 

field costs exceed by far the cost of printing the 

results, the present practice is short-sighted. Perhaps 

science needs fewer minor investigations and fewer 

papers, but those printed should be accompanied by 

the actual data.

The most important contribution made by the 

careful measurements on the East Fork River is that 

they provided the actual bedload amounts moving in a 

real river, against which the new Helley-Smith sampler was compared. No rating of such a device in a 

flume has the value of the comparison of total bedload 

movement in a river and simultaneous sampling by a 

sediment-sampling device. This comparison, consisting of thousands of samples and years of real bedload 

measurement, has not been equaled by any other sampler calibration.

The project has several restrictions and shortcomings. It is, first, a sample of the action of only one 

river. That river carries primarily sand, with only a 

minor amount of gravel as bedload. Therefore, the 

many things we would like to know about gravel-bed 

rivers are unanswered and may be surmised only by 

inference.

The sand carried by the river has a somewhat 

bimodal size distribution. Thus, the selection of what 

grain size might best characterize the bedload is not 

obvious. Analysis of the data indicates that the representative size probably should be dependent on the 

discharge and is not a constant that applies to all flow 

conditions. This is an important matter because in all 

formulas for computing bedload transport rate, a representative size and size distribution is either specified 

or tacitly assumed. Using the measured concurrent 

values of velocity, depth, and slope, computed values 

of bedload transport rate using a constant grain size

are too small for high discharges and too large for low 

discharges. Measured changes in slope do not account 

for this difference. We conclude that for reasons not 

clear, the representative grain size should be smaller at 

high discharges than at low discharges. This idea 

needs to be further explored in other rivers.

In the East Fork, the sediment transport was not 

concentrated in the deepest part of the channel, where 

the depth-slope product would be greatest. The greatest transport was in the shallower parts of the channel 

over or near the minor gravel bar just left of the channel centerline. The transport-rate distribution closely 

follows the distribution of local shear stress, as 

explained in detail by Dietrich and Smith (1984). 

They computed local shear stress from measurements 

of local velocity close to the bed and simultaneously 

measured transport rate with a miniature Helley-Smith 

sampler. As shown especially in their figure 16 

(p. 1369), shear stress is greatest near the convex bank 

as the water approaches the point bar and gradually 

shifts toward the concave bank at the end of the curve 

and as the crossover point is reached. Thus, the East 

Fork observations are well explained by the DietrichSmith analysis.

Finally, actual measurement data on movement 

of individual sand grains and of gravel clasts supplement heretofore meager data on distance moved in 

individual excursions and during a whole flow season. 

When the flow is competent to move a rock of a given 

size, only a few of the many available will be moved 

at one time. The fluorescent-tracer experiments 

allowed us to mark and follow individual grains of 

sand. The data indicate that downstream movement 

usually is limited to only a short distance on any individual excursion. The downstream rate of bedload 

movement is surprisingly slow as a result.

SELECTED REFERENCES

Ackers, Peter, and White, W.R., 1973, Sediment transport: 

new approach and analysis: American Society of Civil 

Engineers, Journal of the Hydraulics Division, v. 99, 

no. HY11, p. 2041-2060.

Andrews, E.D., 1979a, Scour and fill in a stream channel, 

East Fork River, western Wyoming: U.S. Geological 

Survey Professional Paper 1117, 49 p.

————1979b, Hydraulic adjustment of the East Fork River, 

Wyoming to the supply of sediment, in Rhodes, D.D., 

and Williams, G.P, eds., Adjustments of the fluvial 

system: Dubuque, Iowa, Kendall/Hunt Publishing Co., 

p. 69-94.

Concluding Statement 43
—1981, Measurement and computation of bed-material discharge in a shallow sand-bed stream, Muddy 

Creek, Wyoming: Water Resources Research, v. 17, 

no. l,p. 131-141.

—1982a, Adjustment of the East Fork River to bedload 

sediment contributed by Muddy Creek, in Leopold, 

L.B., ed., Field trip guidebook: American Geomorphological Field Group 1982 Conference, Pinedale, 

Wyo., p. 57-68. 

-1982b, Bank stability and channel width adjustment,

East Fork River, Wyoming: Water Resources 

Research, v. 18, no. 4, p. 1184-1192. 

Bagnold, R.A., 1966, An approach to the sediment transport 

problem from general physics: U.S. Geological Survey Professional Paper 422-1, p. 11-37

————1977, Bedload transport by natural rivers: Water 

Resources Research, v. 13, no. 2, p. 303-312.

————1980, An empirical correlation of bedload transport 

rates in flumes and natural rivers: Royal Society of 

London Proceedings, A, v. 372, p. 453-473. 

-1986, Transport of solids by natural water flow: evidence for a worldwide correlation: Royal Society of 

London Proceedings, A, v. 405, p. 369-374.

Blackwelder, Eliot, 1915, Post-Cretaceous history of the 

mountains of central western Wyoming: Journal of 

Geology, v. 23, p. 97-117; 193-217; 307-340.

Bryan, Kirk, and Ray. L., 1940, Geological antiquity of the 

Lindenmeier site: Smithsonian Miscellaneous Collection, v. 99, no. 2, 76 p.

Dietrich, W.E., and Smith, J.D., 1984, Bedload transport in 

a river meander: Water Resources Research, v. 20, 

no. l,p. 1355-1380.

Drake, T.G., Shreve, R.L., Dietrich, W.E., Whiting, P.J., and 

Leopold, L.B., 1988, Transport of fine gravel observed 

by motion-picture photography: Journal of Fluid 

Mechanics, v. 192, p. 193-217.

Einstein, H.A., 1950, The bedload function for sediment 

transportation in open channel flows: U.S. Department 

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Emmett, W.W, 1980a, A field calibration of the sedimenttrapping characteristics of the Helley-Smith bedload 

sampler: U.S. Geological Survey Professional 

Paper 1139,44 p.

————1980b, Bedload sampling in rivers, in Proceedings, 

[First] International Symposium on River Sedimentation, Beijing, China, March 24-29, 1980: p. 991-1017.

————1981, Measurement of bedload in rivers, in Erosion 

and sediment transport measurement: International 

Association of Hydrologic Sciences Publication 133, 

p. 3-15.

————1982a, Helley-Smith bedload sampler, in Leopold,

—1982b, Variability of bedload and some hydraulic 

characteristics along a reach of East Fork River, in 

Leopold, L.B., ed., Field trip guidebook: American 

Geomorphological Field Group 1982 Conference, 

Pinedale, Wyo., p. 49-56. 

-1984, Measurement of bedload in rivers. Chapter 5

L.B., ed., Field trip guidebook: American Geomorphological Field Group 1982 Conference, Pinedale, 

Wyo., p. 41-48.

in Hadley, R.F., and Walling, D.E., Erosion and sediment yield: Norwich, Conn., Geo Books, p. 91-110.

Emmett, W.W., and Leopold, L.B., 1977, A comparison of 

observed sediment-transport rates with rates computed 

using existing formulas (abstr.), in Doehring, D.O., 

ed., Geomorphology of arid regions: Proceedings, 

Eighth Annual Geomorphology Symposium, Binghamton, N.Y., Sept. 23-24, 1977, p. 187-188.

Emmett, W.W., Leopold, L.B., and Myrick, R.M., 1983, 

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River Sedimentation, Nanjing, China, October 11-16, 

1983: p. 730-754.

Emmett, W.W, and Myrick, R.M., 1985, Field data describing the movement and storage of sediment in the East 

Fork River, Wyoming-Part V. Bed-material tracers, 

1979 and 1980: U.S. Geological Survey Open-File 

Report 85-169, 339 p.

Emmett, W.W., Myrick, R.M., and Martinson, H.A., 1985, 

Hydraulic and sediment-transport data, East Fork 

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Field data describing the movement and storage of sediment in the East Fork River, Wyoming. Part I-River 

hydraulics and sediment transport, 1979: U.S. Geological Survey Open-File Report 80-1189, 43 p.

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Ill-River hydraulics and sediment transport, 1980: 

U.S. Geological Survey Open-File Report 82-359, 

289 p.

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American Geomorphological Field Group 1982 Conference, Pinedale, Wyo., p. 95-104.

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during Post-Clovis time on the Northwestern Plains, 

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water, based on experiments made with the assistance 

of E.G. Murphy: U.S. Geological Survey Professional 

Paper 86, 263 p.

44 Bedload and River Hydraulics—Inferences from the East Fork River
Helley, E.J., and Smith, Winchell, 1971, Development and 

calibration of a pressure-difference bedload sampler: 

U.S. Geological Survey open-file report, 18 p.

Holmes, G.W., and Moss, J.H., 1955, Pleistocene geology 

of the southwestern Wind River Mountains, Wyoming: 

Geological Society of America Bulletin, v. 66, 

p. 629-653.

Howard, E.B., and Hack, J.T., 1943, The Finley Site: 

American Antiquity, v. 8, no. 3, p. 224-295.

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Wyoming], in Leopold, L.B., ed., Field trip guidebook: American Geomorphological Field Group 1982 

Conference, Pinedale, Wyo., p. 4-13.

————1982b, Water surface topography, in Hey, R.D., ed., 

Gravel bed rivers: New York, John Wiley and Sons, 

p. 358-387.

Leopold, L.B., and Emmett, W.W., 1976, Bedload measurements, East Fork River, Wyoming: National Academy 

of Sciences Proceedings, v. 73, no. 4, p. 1000-1004.

————1977, 1976 bedload measurements, East Fork River, 

Wyoming: National Academy of Sciences Proceedings, v. 74, no. 7, p. 2644-2648.

————1982, Bedload trap, East Fork River, in Leopold,

L.B., ed., Field trip guidebook: American Geomorphological Field Group 1982 Conference, Pinedale, 

Wyo., p. 30-40.

Leopold, L.B., Emmett, W.W, and Myrick, R.M., 1966, 

Channel and hillslope processes in a semiarid area, 

New Mexico: U.S. Geological Survey Professional 

Paper 352-G, p. 193-253.

Leopold, L.B., and Rosgen, D.C., 1991, Movement of bed 

material clasts in mountain streams, in Proceedings of 

the Fifth Federal Interagency Sedimentation Conference, Las Vegas, Nevada, March 18-21, 1991: Subcommittee on Sedimentation, Interagency Advisory 

Committee on Water Data, p. 4-183 to 4-188.

Leopold, L.B., and Wolman, M.G., 1957, River channel patterns: braided, meandering, and straight: U.S. Geological Survey Professional Paper 282-B, p. 39-85.

Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial processes in geomorphology: San Francisco, 

W.H. Freeman and Company, 522 p.

Limerinos, J.T., 1970, Determination of the Manning coefficient from measured bed roughness in natural channels: U.S. Geological Survey Water-Supply 

Paperl898-B,47p.

Lisle, Thomas, 1982, Variations of hydraulic friction and 

roughness in a pool, riffle, and two bends of the East 

Fork River during a period of high runoff, in Leopold, 

L.B., ed., Field trip guidebook: American Geomorphological Field Group 1982 Conference, Pinedale, 

Wyo., p. 69-76.

Mahoney, H.A., Andrews, E.D., Emmett, W.W., Leopold, 

L.B., Meade, R.H., Myrick, R.M., and Nordin, C.F, 

1976, Data for calibrating unsteady-flow sedimenttransport models, East Fork River, Wyoming, 1975: 

U.S. Geological Survey Open-File Report 76-22, 

293 p.

Meade, R.H., Emmett, W.W., and Myrick, R.M., 1981, 

Movement and storage of bed material during 1979 in 

East Fork River, Wyoming, USA, in Erosion and sediment transport in Pacific rim steep lands: International 

Association of Hydrologic Sciences Publication 132, 

p. 225-235.

Meade, R.H., Myrick, R.M., and Emmett, W.W, 1980,

Field data describing the movement and storage of sediment in the East Fork River, Wyoming. Part II-Bed 

elevations, 1979: U.S. Geological Survey Open-File 

Report 80-1190, 172 p.

————1982, Field data describing the movement and storage of sediment in the East Fork River, Wyoming. Part 

IV-Bed elevations, 1980: U.S. Geological Survey 

Open-File Report 82-360, 197 p.

Poreh, M., Sagiv, A., and Seginer, I., 1970, Sediment sampling efficiency of slots: American Society of Civil 

Engineers, Journal of the Hydraulics Division, v. 96, 

no. HY5, p. 2065-2078.

Prestegaard, K.L., 1982, Components of flow resistance in 

the East Fork River, Wyoming, in Leopold, L.B., ed., 

Field trip guidebook: American Geomorphological 

Field Group 1982 Conference, Pinedale, Wyo., p. 77- 

85.

Reid, lan, Brayshaw, A.C., and Frostick, L.E., 1984, An 

electromagnetic device for automatic detection of bedload motion and its field applications: Sedimentology, 

v. 31, p. 269-276.

Richmond, G.M., 1973, Geologic map of the Fremont Lake 

South Quadrangle, Sublette County, Wyoming: U.S. 

Geological Survey Geologic Quadrangle 

MapGQ-1138, scale 1:24,000.

Smithson, S.B., Brewer, Jon, Kaufman, S., Oliver, Jack, and 

Hurich, Charles, 1978, Nature of the Wind River 

Thrust, Wyoming, from COCORP deep-reflection data 

and from gravity data: Geology, v. 6, p. 648-652.

Williams, G.P., 1970, Flume width and water depth effects 

in sediment-transport experiments: U.S. Geological 

Survey Professional Paper 562-H, 30 p.

Selected References 45

BEDLOAD DATA AND HYDRAULIC PARAMETERS

Bedload Data and Hydraulic Parameters 47
Table 3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River, Wyoming, 1973-79

[Q, effective water discharge; u, mean velocity; d, mean depth; £>50, median particle size; z'b, unit transport rate; co, unit stream power; (Op, stream 

power at initial motion; co-co0, excess stream power; «*, shear velocity; m3/s, cubic meters per second; m/s, meters per second; m, meters; kg/m-s, 

kilograms per second per meter of width. Water-surface slope, 5, = 0.0007. Width of flow, w, = 14.6 meters. No measurements during 1977.]

Date

Q

(m3/s)

M

(m/s)

d

(m)

#50

(m)

'b 

(kg/m-s)

CO

(kg/m-s)

<BO

(kg/m-s)

oo-a>0

(kg/m-s)

M*

(m/s)

M/M*

1973

5/26/73

6/01/73

6/02/73

6/03/73

6/06/73

6/07/73

6/08/73

16.1

16.1

17.8

16.6

11.3

15.9

19.2

1.06

1.06

1.09

1.07

.96

1.06

1.19

1.04

1.04

1.11

1.06

.81

1.03

1.17

0.00135

.00045

.00074

.00071

.00056

.00060

.00098

0.008

.012

.015

.015

.0083

.016

.014

0.772

.772

.847

.794

.544

.764

.975

0.059

.013

.026

.024

.017

.019

.039

0.712

.759

.821

.770

.527

.745

.936

0.085

.085

.087

.085

.075

.084

.090

12.5

12.5

12.5

12.5

12.9

12.6

13.3

1974

5/25/74

5/26/74

5/27/74

5/28/74

5/29/74

5/30/74

5/31/74

6/01/74

6/02/74

6/03/74

6/04/74

6/05/74

5.34

9.92

21.5

29.8

41.5

32.2

22.9

24.3

25.5

29.7

27.9

26.5

.76

.92

1.15

1.28

1.41

1.31

1.18

1.20

1.22

1.27

1.25

1.23

.48

.74

1.27

1.60

2.01

1.68

1.33

1.38

1.43

1.59

1.52

1.47

.00054

.00059

.00103

.00140

.00152

.00151

.00140

.00094

.00099

.00088

.00092

.00081

.003

.051

.110

.140

.182

.049

.040

.013

.0081

.011

.018

.019

.255

.477

1.02

1.43

1.98

1.54

1.10

1.16

1.22

1.41

1.33

1.27

.015

.018

.042

.065

.075

.073

.064

.037

.040

.034

.036

.030

.240

.458

.981

1.37

1.91

1.47

1.03

1.12

1.18

1.38

1.29

1.23

.057

.071

.093

.105

.117

.107

.096

.097

.099

.104

.102

.100

13.2

12.9

12.3

12.2

12.1

12.2

12.3

12.3

12.3

12.1

12.2

12.2

7975

5/27/75

6/02/75

6/03/75

6/04/75

6/05/75

6/06/75

6/07/75

6/08/75

6/09/75

6/10/75

6/11/75

6/13/75

2.44

5.82

9.13

10.0

10.7

20.0

24.8

25.6

24.3

14.4

10.1

15.8

.61

.78

.90

.92

.94

1.13

1.21

1.22

1.20

1.03

.92

1.06

.28

.51

.70

.74

.78

1.21

1.40

1.44

1.38

.96

.75

1.02

.00070

.00074

.00078

.00116

.00126

.00136

.00128

.00141

.00135

.00111

.00102

.00050

.0013

.030

.049

.051

.061

.195

.129

.108

.052

.022

.0069

.017

.119

.278

.441

.477

.513

.957

1.19

1.23

1.16

.692

.483

.757

.021

.024

.027

.046

.052

.061

.057

.065

.061

.045

.039

.015

.099

.255

.414

.430

.461

.896

1.13

1.16

1.10

.647

.444

.742

.044

.059

.069

.071

.073

.091

.098

.099

.097

.081

.072

.084

13.9

13.2

13.0

12.9

12.8

12.4

12.3

12.3

12.3

12.7

12.8

12.7

48 Bedload and River Hydraulics—Inferences from the East Fork River
Table 3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River, Wyoming, 

1973-79—Continued

Date

Q

(m3/s)

u 

(m/s)

d 

(m)

#50

(m)

'b 

(kg/m-s)

CO

(kg/m-sj

C00

(kg/m-s)

CO-GOo

(kg/m-s)

Uf

(m/s)

M/M*

1975— Continued

6/14/75

6/15/75

6/16/75

6/17/75

6/18/75

6/19/75

6/21/75

6/22/75

6/23/75

6/24/75

6/25/75

6/26/75

7/01/75

7/08/75

25.7

29.0

30.3

22.2

12.8

10.1

7.23

7.01

8.24

10.8

21.7

13.1

23.1

21.5

1.22

1.27

1.28

1.17

.99

.92

.84

.83

.87

.94

1.16

1.00

1.18

1.16

1.44

1.57

1.62

1.30

.88

.75

.59

.58

.65

.78

1.28

.90

1.34

1.27

0.00127

.00105

.00119

.00136

.00059

.00073

.00070

.00064

.00077

.00098

.00110

.00099

.00163

.00091

0.058

.074

.074

.050

.0066

.0060

.0020

.0029

.0039

.012

.052

.025

.135

.020

1.23

1.40

1.45

1.06

.610

.483

.347

.337

.396

.513

1.04

.63

1.11

1.03

0.057

.044

.052

.062

.018

.024

.022

.020

.026

.037

.046

.038

.079

.035

1.17

1.35

1.40

1.00

.591

.459

.325

.317

.370

.476

.994

.592

1.03

.996

0.099

.104

.105

.094

.078

.072

.064

.063

.067

.073

.094

.079

.096

.093

12.3

12.2

12.1

12.4

12.7

12.8

13.2

13.1

13.0

12.8

12.4

12.7

12.3

12.4

1976

5/18/76

5/19/76

5/20/76

5/20/76

5/21/76

5/22/76

5/26/76

5/27/76

5/27/76

5/27/76

5/28/76

5/28/76

5/29/76

5/29/76

5/30/76

5/31/76

5/31/76

6/01/76

6/01/76

9.87

14.8

18.9

19.6

22.4

17.5

9.77

14.3

13.7

13.0

18.8

19.8

20.5

20.9

20.9

16.6

15.8

14.3

13.9

.87

1.00

1.09

1.10

1.15

1.06

.87

.99

.97

.96

1.08

1.10

1.12

1.12

1.12

1.04

1.02

.99

.98

.78

1.01

1.19

1.22

1.33

1.13

.77

.99

.96

.93

1.18

1.23

1.25

1.27

1.27

1.09

1.06

.99

.97

.00098

.00104

.00096

.00104

.00152

.00156

.00071

.00059

.00061

.00077

.00095

.00111

.00130

.00167

.00129

.00109

.00098

.00081

.00080

.052

.085

.073

.080

.111

.047

.008

.014

.019

.014

.027

.028

.044

.038

.048

.039

.025

.023

.020

.475

.707

.908

.939

1.07

.84

.469

.686

.652

.625

.892

.947

.980

.996

.996

.794

.757

.686

.665

.037

.041

.037

.042

.072

.073

.024

.019

.019

.027

.037

.046

.058

.082

.057

.044

.038

.029

.028

.438

.666

.870

.897

1.00

.765

.445

.667

.632

.598

.855

.901

.922

.914

.939

.749

.719

.657

.637

.073

.083

.090

.092

.096

.088

.073

.082

.081

.080

.090

.092

.093

.093

.093

.087

.085

.082

.082

11.9

12.0

12.1

12.0

12.0

12.0

11.9

12.0

12.0

12.0

12.0

12.0

12.0

12.0

12.0

12.0

12.0

12.0

12.0

Bedload Data and Hydraulic Parameters 49
Table 3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River, Wyoming, 

1973-79—Continued

Date

Q

(m3/s)

u 

(m/s)

d 

(m)

D50 

(m)

*b 

(kg/m-s)

CD

(kg/m-sj

0>0

(kg/m-s)

CO-CDo

(kg/m-s)

u* 

(m/s)

H/W*

1976— Continued

6/02/76

6/02/76

6/03/76

6/04/76

6/05/76

6/05/76

6/06/76

6/07/76

6/08/76

6/09/76

6/09/76

6/10/76

6/11/76

6/11/76

6/11/76

6/11/76

6/11/76

6/12/76

6/12/76

6/12/76

6/12/76

6/12/76

6/12/76

6/13/76

6/14/76

6/14/76

6/15/76

6/15/76

6/16/76

6/18/76

6/19/76

6/20/76

6/21/76

17.9

17.8

21.6

21.8

21.4

22.4

22.6

24.6

21.1

18.8

18.9

18.2

13.8

14.5

15.7

15.2

14.4

13.1

12.5

11.2

10.5

9.64

8.50

6.55

4.97

4.65

3.87

3.44

4.97

3.90

4.20

4.57

9.53

1.07

1.06

1.14

1.14

1.13

1.15

1.16

1.19

1.13

1.08

1.09

1.07

.98

.99

1.02

1.01

.99

.96

.94

.91

.89

.86

.83

.76

.69

.67

.64

.61

.69

.63

.65

.67

.86

1.15

1.14

1.30

1.30

1.29

1.33

1.33

1.41

1.28

1.18

1.19

1.16

.97

1.00

1.05

1.03

.99

.93

.90

.84

.81

.76

.70

.59

.50

.47

.42

.39

.50

.42

.44

.47

.76

0.00094

.00104

.00118

.00140

.00176

.00151

.00130

.00135

.00124

.00103

.00108

.00106

.00084

.00105

.00102

.00107

.00079

.00081

.00077

.00081

.00082

.00082

.00077

.00049

.00041

.00053

.00066

.00088

.00050

.00042

.00044

.00043

.00068

0.036

.029

.052

.054

.057

.049

.057

.054

.036

.032

.021

.018

.016

.018

.017

.039

.015

.011

.010

.010

.0090

.0066

.0052

.0017

.0014

.0012

.0002

.0002

.0006

.0004

.0006

.0014

.011

0.861

.846

1.04

1.04

1.02

1.07

1.08

1.17

1.01

.892

.875

.869

.665

.693

.750

.728

.686

.625

.592

.535

.505

.458

.407

.314

.242

.220

.188

.167

.242

.185

.200

.220

.458

0.036

.030

.050

.064

.088

.071

.058

.061

.054

.041

.044

.043

.030

.042

.040

.043

.028

.029

.027

.029

.029

.029

.026

.014

.010

.015

.020

.029

.014

.011

.011

.011

.022

0.825

.607

.987

.973

.932

.999

1.02

1.11

.958

.851

.830

.826

.635

.651

.709

.685

.658

.596

.565

.507

.476

.429

.381

.300

.231

.206

.168

.137

.228

.175

.189

.209

.435

0.089

.088

.094

.094

.094

.096

.096

.098

.094

.090

.090

.089

.082

.083

.085

.084

.082

.080

.079

.076

.075

.072

.069

.064

.059

.057

.054

.052

.059

.054

.055

.057

.072

12.0

12.0

12.1

12.1

12.0

12.0

12.1

12.1

12.0

12.0

12.1

12.0

12.0

11.9

12.0

12.0

12.1

12.0

11.9

12.0

11.9

11.9

12.0

11.9

11.8

11.8

11.9

11.3

11.8

11.7

11.8

11.8

11.9

50 Bedload and River Hydraulics—Inferences from the East Fork River
Table 3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River, Wyoming, 

1973-79—Continued

Date

Q

(m3/s)

u 

(m/s)

d 

(m)

#50 

(m)

*b 

(kg/m-s)

CO

(kg/m-s)

coo 

(kg/m-s)

Cfl-CQo

(kg/m-s)

M*

(m/s)

U/U*

1978

5/24/78

5/25/78

5/26/78

5/27/78

5/28/78

5/28/78

6/07/78

6/08/78

6/09/78

6/10/78

6/14/78

6/15/78

6/16/78

6/21/78

6/24/78

6/25/78

6/25/78

6/29/78

6/29/78

6/29/78

6/30/78

6/30/78

9.21

8.38

7.47

7.52

9.07

8.65

20.5

26.3

27.8

30.7

26.8

26.5

26.0

15.4

19.6

17.6

17.9

13.5

14.1

13.7

13.7

13.9

0.84

.80

.77

.77

.83

.82

1.14

1.26

1.28

1.33

1.27

1.26

1.25

1.02

1.12

1.07

1.08

.97

.99

.98

.98

.98

0.75

.71

.67

.67

.75

.72

1.23

1.43

1.48

1.58

1.45

1.44

1.42

1.03

1.20

1.12

1.13

.95

.98

.96

.96

.97

0.00079

.00096

.00109

.00107

.00102

.00088

.00145

.00144

.00148

.00143

.00090

.00117

.00136

.00092

.00120

.00138

.00138

.00122

.00087

.00125

.00125

.00117

0.045

.058

.028

.020

.019

.014

.060

.080

.085

.082

.067

.046

.037

.015

.040

.043

.035

.012

.018

.021

.023

.021

0.441

.401

.357

.360

.434

.413

.982

1.26

1.33

1.47

1.28

1.27

1.24

.735

.939

.842

.854

.648

.679

.659

.654

.665

0.027

.035

.042

.041

.039

.031

.067

.067

.070

.067

.035

.050

.062

.035

.051

.063

.062

.051

.032

.053

.053

.048

0.414

.365

.315

.319

.395

.382

.915

1.19

1.26

1.40

1.25

1.22

1.18

.700

.888

.781

.792

.559

.647

.606

.601

.617

0.072

.070

.068

.068

.072

.070

.092

.099

.101

.104

.100

.099

.099

.084

.091

.088

.088

.081

.082

.081

.081

.082

11.7

11.6

11.4

11.4

11.6

11.7

12.4

12.7

12.7

12.8

12.7

12.7

12.7

12.1

12.3

12.2

12.3

12.0

12.1

12.1

12.1

12.0

7979

5/20/79

5/21/79

5/23/79

5/24/79

5/25/79

5/26/79

5/27/79

5/28/79

5/30/79

5/31/79

6/01/79

10.9

12.6

20.9

22.8

21.8

22.0

28.5

26.2

17.2

8.48

5.77

.87

.92

1.09

1.13

1.11

1.11

1.22

1.18

1.02

.80

.71

.85

.94

1.31

1.38

1.34

1.35

1.60

1.51

1.14

.72

.56

.00077

.00094

.00138

.00130

.00149

.00147

.00171

.00111

.00100

.00085

.00050

.052

.071

.069

.049

.048

.032

.048

.026

.013

.004

.0002

.518

.605

.999

1.09

1.04

1.05

1.37

1.25

.814

.403

.278

.027

.035

.063

.058

.070

.069

.086

.047

.039

.030

.014

.491

.570

.937

1.03

.971

.980

1.28

1.20

.774

.373

.264

.076

.080

.095

.097

.096

.096

.105

.102

.088

.070

.062

11.4

11.4

11.5

11.6

11.6

11.5

11.6

11.6

11.5

11.4

11.4

Bedload Data and Hydraulic Parameters 51
Table 3. Bedload data and hydraulic parameters measured at the bedload trap, East Fork River, Wyoming, 

1973-79—Continued

Date

Q

(m3/s)

u 

(m/s)

d 

(m)

#50

(m)

'b 

(kg/m-s)

(0

(kg/m-sj

(DO 

(kg/m-s)

tO-Wo

(kg/m-s)

u* 

(m/s)

M/M*

1979— Continued

6/04/79

6/05/79

6/06/79

6/07/79

6/08/79

6/13/79

6/14/79

6/15/79

6/16/79

6/17/79

8.42

13.0

14.8

13.0

6.95

12.2

15.5

14.0

8.26

6.71

0.80

.93

.97

.93

.75

.91

.99

.95

.80

.74

0.72

.95

1.04

.95

.63

.91

1.07

1.00

.71

.62

0.00047

.00047

.00050

.00050

.00103

.00067

.00122

.00100

.00079

.00094

0.002

.006

.009

.018

.009

.013

.026

.025

.012

.008

0.403

.618

.706

.618

.331

.580

.741

.665

.398

.321

0.013

.013

.015

.015

.039

.022

.052

.039

.038

.034

0.390

.605

.691

.603

.292

.558

.689

.626

.360

.287

0.070

.081

.084

.081

.065

.079

.085

.083

.070

.065

11.4

11.5

11.5

11.5

11.4

11.5

11.5

11.5

11.4

11.3

52 Bedload and River Hydraulics—Inferences from the East Fork River


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