Sediment-Trapping Characteristics 

of the Helley-Smith 

Bedload Sampler

- _

•--*—— -*-

/ver, Wyomingupstream afbethoad-tramport researcti facility

A Field Calibration of the 

Sediment-Trapping Characteristics 

of the Helley-Smith 

Bedload Sampler

By WILLIAM W. EMMETT

GEOLOGICAL SURVEY PROFESSIONAL PAPER 1139

Studies of bedload transport 

in river channels

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1980
UNITED STATES DEPARTMENT OF THE INTERIOR 

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY 

H. William Menard, Director

Library of Congress Cataloging in Publication Data

Emmett, William W.

A field calibration of the sediment-trapping characteristics of the

Helley-Smith bedload sampler.

(Geological Survey professional paper ; 1139)

Bibliography: P. 29-30.

Supt.ofDocs.no.: 119.16:1139

1. Bedload Measurement. 2. Hydrology Instruments. I. Title. 

II. Title: Helley-Smith bedload sampler. III. Series: United 

States. Geological Survey. Professional paper ; 1139.

GB850.E45 551.3'03'028 80-607050

For sale by the Superintendent of Documents, U.S. Government Printing Office

Washington, D.C. 20402
CONTENTS

Abstract _____________________________________________________ 1

Introduction__________________________________________ 1

Bedload________________________________________________ 1

Helley-Smith bedload sampler _____________________________ 2

Description of field-test facility __________________________________ 3

East Fork River __________________________________________ 3

Conveyor-belt bedload trap _____________________________________ 4

Sampling techniques with Helley-Smith bedload sampler_______________________ 8

Results of field-calibration tests ________________________________ 9

Bedload-transport rates by individual particle-size categories, basic data ________ 10

Comparison of Helley-Smith results to conveyor-belt results, basic data _________ 14

Modifications to the basic data ____________________________ 19

Summary and recommendations __________________________________ 27

Acknowledgments ________________________________________ 27

References cited _____________________________________________ 27

ILLUSTRATIONS

Page

FIGURE 1. Sketch of the Helley-Smith bedload sampler ____________________________________________ 2

2. Plan and side-elevation drawings of 7.62-cm Helley-Smith bedload sampler________——_—— ————————— —— 2

3. Graph showing vertical-velocity profiles upstream of sampler, and in sampler orifice of 7.62-cm Helley-Smith bedload

sampler _________________________________________________________ 3

4. Map of East Fork River drainage area upstream of the project site______________________-__—_-- 3

5. Planimetric map of East Fork River in vicinity of bedload trap, showing median diameter of bed material at sections

along river____________________________________________________—_____ 5

6. Cross section of the East Fork River at the bedload trap_________________________———______ —————— _ 5

7. Photographs of the East Fork River and conveyor-belt bedload sampler.__________________—————————— 6

8. Graph of hydraulic-geometry relations for the East Fork River at the bedload trap _______________———————— 7

9. Photogaphs showing use of the Helley-Smith sampler at the bedload trap ______—___——_ ——— ___- — ————— _ 9

10-18. Graphs showing relation of bedload-transport rate in individual-size category as function of total bedload-transport rate 

for Helley-Smith sampler and conveyor-belt sampler:

10. 0.06-0.12 mm size class________________________________________________________ 11

11. 0.12-0.25 mm size class ________________________________________________________ 11

12. 0.25-0.50 mm size class________________________________________________———_ 12

13. 0.50-1.00 mm size class ______________________________________________________ 12

14. 1.00-2.00 mm size class________________________________________________________ 13

15. 2.00-4.00 mm size class ______________________________________________—-—————— 13

16. 4.00-8.00 mm size class _______________________________________________——————— 14

17. 8.00-16.0 mm size class ____________________________________________________-__ 14

18. 16.0-32.0 mm size class________________________________________________________ 15 

19-27. Graphs showing comparison of bedload-transport rate by individual particle-size category for Helley-Smith sampler and 

conveyor-belt sampler:

19. 0.06-0.12 mm size class______________________________________________________ 16

20. 0.12-0.25 mm size class___________________________________________________——_ 16

21. 0.25-0.50 mm size class_______________________________________________________ 16

22. 0.50-1.00 mm size class_____________________________________________——————— 16

23. 1.00-2.00 mm size class ______________________________________________________ 17

24. 2.00-4.00 mm size class________________________________________________________ 17

25. 4.00-8.00 mm size class___________________________________________________——- 17

26. 8.00-16.0 mm size class________________________________________________—————— 17

27. 16.0-32.0 mm size class____________________________________________________--__ 18

ill
IV CONTENTS

FIGURES 28- 39. Graphs showing comparison of total bedload-transport rate: Pase

28. Helley-Smith sampler and conveyor-belt sampler; conveyor-belt sampler designated as independent

variable _____________________________________________________________________________________ 20

29. Helley-Smith sampler and conveyor-belt sampler; Helley-Smith sampler designated as independent

variable ___________________________________________________ ——— ________— 20

30. Helley-Smith sampler and conveyor-belt sampler corrected to condition of stream-wide slot; conveyorbelt sampler designated as independent variable _____-____________________________________ 21

31. Helley-Smith sampler and conveyor-belt sampler corrected to condition of stream-wide slot; HelleySmith sampler designated as independent variable _________________________________________ 21

32. Helley-Smith sampler corrected for stage difference and conveyor-belt sampler corrected for condition of

stream-wide slot _______________________________________________ 21

33. Helley-Smith sampler corrected for stage difference and conveyor-belt sampler corrected for condition of 

stream-wide slot; relation corrected for variance of the independent variable in the least-squares 

regression ___________________________________________________________ 22

34. Sediment particles larger than 0.25 mm; Helley-Smith sampler and conveyor-belt sampler corrected for

condition of stream-wide slot _______________________________________________ 22

35. Sediment particles larger than 0.50 mm; Helley-Smith sampler and conveyor-belt sampler corrected for

condition of stream-wide slot _________________________________________-____ 23

36. Sediment particles larger than 0.50 mm; Helley-Smith sampler and conveyor-belt sampler corrected for 

condition of stream-wide slot; relation corrected for variance of the independent variable in the 

least-squares regression ___________________________________________ 23

37. Sediment particles larger than 0.25 mm; Helley-Smith sampler corrected for stage difference and

conveyor-belt sampler corrected for condition of stream-wide slot_____________________ 23

38. Sediment particles larger than 0.50 mm; Helley-Smith sampler corrected for stage difference and

conveyor-belt sampler corrected for condition of stream-wide slot________________________________ 24

39. Sediment particles larger than 0.50 mm; Helley-Smith sampler corrected for stage difference and 

conveyor-belt sampler corrected for condition of stream-wide slot; relation corrected for variance of

the independent variable in the least-squares regression ______________________________ 24

40-48. Graphs showing comparison of bedload-transport rate by individual particle-size category, Helley-Smith 

sampler and conveyor-belt sampler corrected for condition of stream-wide slot:

40. 0.06-0.12 mm size class________________________________ ______________________ 25

41. 0.12-0.25 mm size class____________________________________________________________ 25

42. 0.25-0.50 mm size class______________________________________________________ 25

43. 0.50-1.00 mm size class______________________________________________________ 25

44. 1.00-2.00 mm size class_____________________________________________________________________ 26

45. 2.00-4.00 mm size class_____________________________________________________ 26

46. 4.00-8.00 mm size class______________________________________________________ 26

47. 8.00-16.0 mm size class___________. __________________________________________ 26

48. 16.0-32.0 mm size class _______________________________________________________ 27

TABLES

Page

TABLE 1. Size distribution of composited bed material, East Fork River, Wyoming, at bedload-transport research project ____ 7

2. Size distribution of transport-weighted composite bedload (1976 conveyor belt), East Fork River, Wyoming, at bedloadtransport research project __________________________________________________ 7

3. Comparison of bed material and bedload particle sizes _ ___________________________________________ 7

4. Summary data of river hydraulics and bedload transport, conveyor-belt sampler ________________________ 30

5. Particle-size distribution of bedload sediment, conveyor-belt sampler __________________________________ 32

6. Summary data of river hydraulics and bedload transport, Helley-Smith sampler _________________________ 36

7. Particle-size distribution of bedload sediment, Helley-Smith sampler ______________________________ 38

8. Summary of statistical data: log-transformed linear regression of transport rate by particle-size class versus total

transport rate, conveyor-belt sampler ____________________________________________ 41
CONTENTS

TABLE 9. Summary of statistical data: log-transformed linear regression of transport rate by particle-size class versus total

transport rate, Helley-Smith sampler _________________________________________________ 41

10. Listing of comparable data sets used in direct comparison of results from conveyor-belt sampler with results

from Helley-Smith sampler _________________________________________________________ 41

11. Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler versus

conveyor-belt sampler (basic data) ___________________________________________________ 43

12. Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler versus

conveyor-belt sampler (comparison of various modifications to the basic data) _________________________ 43

13. Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler versus

conveyor-belt sampler (conveyor-belt data corrected for conditions of stream-wide slot) _____________ ——— _ 44

SYMBOLS

A, A' Coefficient in regression equation.

B, B' Exponent in regression equation.

CB Reference to conveyor-belt sampler.

d Sediment-particle size, in millimeters.

D Mean depth of effective discharge, in meters.

HS Reference to Helley-Smith sampler.

jb Unit transport rate of sediment in dry weight per

second, in kilograms per second per meter. 

P Probability distribution.

Q Complete river discharge, in cubic meters per second. 

Q' Discharge over 14.6-m width of bedload trap; includes

all flow over active width of the streambed, in

cubic meters per second.

r

SD 

SE 

V

W 

X 

Y

2 °"'2

Correlation coefficient.

Standard deviation.

Standard error.

Mean velocity of effective discharge, in meters per

second.

Effective width of channel, = 14.6 m. 

Independent variable. 

Dependent variable.

Variance of the error in the independent variable. 

Variance of independent variable. 

Summation, 

(superscript) reference to mean value of parameter.

A FIELD CALIBRATION OF THE SEDIMENT-TRAPPING 

CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

BY WILLIAM W. EMMETT

ABSTRACT

For sediment particle sizes between 0.50 and 16 millimeters, the 

Helley-Smith bedload sampler has a near-perfect sediment-trapping 

efficiency. For particle sizes smaller than 0.50 millimeters, the 

Helley-Smith sampler has a high bedload sediment-trapping efficiency because part of the sediment retained by the sampler has been 

transported in suspension and cannot be quantified separately from 

the bedload. For particle sizes larger than about 16 millimeters, the 

Helley-Smith sampler has a low sediment-trapping efficiency, but 

this may be related to the paucity of coarse particles in transport in 

the calibration tests, rather than a reflection of an actual low trap 

efficiency for large-size particles.

INTRODUCTION

Schoklitsch (1950), in reference to bedload transport, 

stated "there is not too much known about it." His 

statement was not without reason; the problems associated with measurement of bedload transport in alluvial channels are significant. Hubbell (1964) has 

described many of the problems encountered with 

measurement of bedload and also provided a current 

(at that time) state-of-the-art report on apparatus and 

techniques for measuring bedload. The reader is referred to the discussion by Hubbell for an overview of 

various bedload-sampling devices and the merits and 

shortcomings of each device.

Bedload samplers of the direct-measuring type are 

simplest and most widely used. A direct-measuring 

bedload sampler intercepts sediment that is in 

transport over a small incremental width of streambed 

and accumulates the sediment in a chamber within the 

sampler. The sampling efficiency of a bedload sampler 

is defined (Hubbell, 1964) as the ratio of the weight of 

bedload collected during a sampling time to the weight 

of bedload that would have passed through the sampler 

width in the same time had the sampler not been there. 

Ideally, the ratio is 1.0, and the weight of every 

particle-size fraction in the collected sample is in the 

same proportion as in the true bedload discharge.

This report presents information on a field calibration of the sediment-trapping efficiency of the HelleySmith bedload sampler, developed since the Hubbell 

report. Because the Helley-Smith bedload sampler

presently is in widespread use (probably in excess of 

over 200 samplers worldwide), the data of this report 

are of particular significance. However, test conditions 

for field calibration during this study were limited, and 

thus results are certain not to be applicable to all situations in which the Helley-Smith bedload sampler is 

being used or being proposed for use.

BEDLOAD

Bedload is that sediment carried down a river by 

rolling and saltation on or near the streambed. Though 

bedload may best be defined as that part of the sediment load supported by frequent solid contact with the 

unmoving bed, in practice it is the sediment moving on 

or near the streambed rather than in the bulk of the 

flowing water.

In the sediment-transport process, individual bedmaterial particles are lifted from the streambed and 

set into motion. If the motion includes frequent contact 

of a particle with the streambed, the particle constitutes part of the bedload. If the motion includes no 

contact with the streambed, the particle is literally a 

part of the suspended load, regardless of how close to 

the streambed the motion occurs and whether or not 

the particle is capable of being sampled by existing 

suspended-sediment sampling equipment. Depending 

on the hydraulics of flow in various reaches of a channel, particles may alternate between being a part of the 

bedload or a part of the suspended load. Likewise at a 

given cross section of channel, particles that are a part 

of the bedload at one stage may be a part of the suspended load at another stage. Any particle in motion 

may come to rest, and for bedload, the downstream 

progress is likely to be a succession of movements and 

rest periods. Particles at rest are part of the bed material. Obviously, there is an intimate relation between 

the bed material, bedload, and suspended load.

Owing to the somewhat nebulous definition of bedload, it becomes an exceedingly difficult task to build 

measuring equipment which samples only bedload. 

Any device which rests on the streambed is perilously 

close to sampling bed material, and any device which
SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

protrudes upwards from the streambed, or by necessity 

is raised or lowered through the flow, may sample some 

part of the suspended load.

This paper utilizes the practical definition of bedload; that is, bedload is the sediment moving on or near 

the streambed. A sampler used to measure the transport 

rate of bedload, by the practical definition, is designated 

a bedload sampler. This designation does not preempt 

the fact that some amount of suspended load also may be 

measured. This possibility and its implications are discussed in a later section of this report.

HELLEY-SMITH BEDLOAD SAMPLER

Helley and Smith (1971) introduced a pressuredifference bedload sampler that is a structurally 

modified version of the Arnhem sampler (Hubbell, 

1964). The Helley-Smith bedload sampler has an expanding nozzle, sample bag, and frame (fig. 1). The 

sampler was designed to be used in flows with mean 

velocities to 3 m/s and sediment sizes from 2 to 10 mm. 

The sampler has a square 7.62-cm entrance nozzle and 

a 46 cm-long sample bag constructed of 0.2-mm mesh 

polyester, though more recently it has become standard practice to use a sample bag of 0.25-mm mesh 

polyester. The standard sample bag has a surface area 

of approximately 1,900 cm2 . Details of the sampler nozzle and frame assembly are shown in figure 2.

The original design included a brass nozzle, 

aluminum-tubing frame weighted with poured molten 

lead to a total weight of 30 kg, aluminum tail fins, and 

bolted construction. More recent versions of the sampler have stainless-steel nozzles for greater durability, 

steel-plate tail fins, solid-steel round-stock bar frame 

selected to maintain a 30-kg total weight, and allwelded construction. The sample bag attaches to the

Sample bag

Nozzle

FIGURE 1.—Sketch of the Helley-Smith bedload sampler.

All dimensions in centimeters

40.64

25.40

FIGURE 2.—Plan and side elevation drawings of 7.62-cm HelleySmith bedload sampler nozzle (above) and sampler (below).

rear of the nozzle with a rubber "O" ring. A sliding 

bracket on the top frame member allows for cablesuspended lowering and raising of the sampler. Position of the bracket along the frame controls the sampler attitude; normal attitude is a slightly tail-heavy 

position (about 15-degree angle).

Since this original design, several structurally different versions of the sampler have been built to adapt 

the sampler to various field uses. One version, developed by the author, has been scaled up from the 7.62- 

cm sampler. The orifice is twice scale (15.24 cm), and 

the frame is one and one-half scale. The larger frame 

assembly allows for greater weighting; total weight of 

the larger sampler has generally been either 45 kg or 

75 kg, but one sampler constructed for use on the Amazon River weighs 250 kg. The large-nozzle sampler is 

generally used to sample larger sediment sizes, and the 

heavier samplers become necessary as deeper and 

swifter rivers are sampled.

Perhaps the most extensively used version of the 

sampler is the 7.62-cm nozzle adapted to a wading rod,
DESCRIPTION OF FIELD-TEST FACILITY

rather than having a frame and tail-fin assembly. To 

minimize weight and to facilitate use of this model, the 

nozzle is generally of cast aluminum and equipped 

with a sectionalized tubular aluminum Wading rod.

A laboratory hydraulic calibration of the HelleySmith bedload sampler has been conducted (Druffel 

and others, 1976). Hydraulic efficiency of a bedload 

sampler has been defined (Hubbell, 1964) as the ratio 

of the mean velocity of water discharge through the 

sampler to the mean velocity of the water discharge 

which would have occurred through the area occupied 

by the opening in the sampler nozzle had the sampler 

not been there. In the laboratory study, velocity profiles were measured in the sampler nozzle and at various locations upstream from the sampler. Typical velocity profiles are illustrated in figure 3. The results of 

this study showed the hydraulic efficiency of the 7.62- 

cm and the 15.24-cm Helley-Smith bedload sampler is 

approximately 1.54. This value of hydraulic efficiency 

was found to be constant for the range of flow conditions in the experiments, a range applicable to many 

natural streamflow conditions.

The study, along with other observations by the author, indicates the sample bag can be filled to 40 percent capacity with sediment larger than the mesh size 

(0.2-0.25 mm) of the bag without reduction in hydraulic efficiency. However, sediment with diameters close 

to the mesh size of the sample bag both plugs the sample bag and escapes through the mesh, causing an unpredictable decrease in hydraulic efficiency and loss of 

the sample.

Data on the hydraulic characteristics of the sampler 

provide qualitative information about probable performance, but such data cannot be used directly to

EXPLANATION 

Undisturbed velocity 

profile

Velocity profi le 

7.6 cm upstream 

of orifice

Velocity profile 

in orifice

20 40 60 80 100 120 

VELOCITY (V), IN CENTIMETERS PER SECOND

FIGURE 3.—Vertical-velocity profiles upstream of sampler and in 

sampler orifice of 7.62-cm Helley-Smith bedload sampler.

evaluate the sediment-trap efficiency of the unit. Controlled experiments are still needed to define 

sediment-trap efficiency; this report describes the results of one such field calibration of the sampler.

DESCRIPTION OF FIELD-TEST FACILITY

An open slot in the streambed of the East Fork River, 

Wyoming, continually excavated of trapped debris by a 

conveyor belt, provided a bedload trap and direct quantitative measurement of bedload-transport rates for 

comparison with bedload-transport rates measured 

with the Helley-Smith bedload sampler. The following 

sections describe the test stream, conveyor-belt bedload trap, and procedures followed in using the 

Helley-Smith bedload sampler.

EAST FORK RIVER

The East Fork River heads in the Wind River Range 

of Wyoming west of the Continental Divide and east 

and south of Mt. Bonneville (fig. 4). From a series of 

small alpine lakes and an altitude of approximately

WYOMING

Mount 

Bonnevi lle-f- .c\

.' Drainage boundary

10 15 KILOMETERS

FIGURE 4.—Map of East Fork River drainage area upstream of the 

project site.
SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

3,400 m, the East Fork River descends about 1,250 m 

in 50 river km to the project site described in this report. Downstream from the study reach, it continues 

another 50 km to its confluence with the New Fork 

River, tributary to the Green River.

The project site is at lat 42°40'23" N., long 

109°34'16"W. The drainage area of the East Fork River 

at the project site is 466 km2 . About half of this basin 

area lies within the Wind River Mountains and is 

underlain by granitic and metamorphic rocks, mostly 

of Precambrian age; the other half of the basin area is 

provided by a major tributary, Muddy Creek, that enters the East Fork River about 5 km upstream of the 

project and drains an upland of rolling hills underlain 

by lower Tertiary sandstone and shale of the Wasatch 

Formation. Much of the sand portion of the sediment 

load for the East Fork River comes from the Muddy 

Creek basin, but most of the water during high flow 

comes from melting snow of the mountain area. The 

high-flow season is generally late May to mid-June, 

and little bedload movement occurs at other times in 

the year.

In the vicinity of the project, the East Fork River 

meanders in a flood plain averaging 120 m in width, 

which, in turn, is confined within a glacial outwash 

terrace of sand and gravel, the tread or surface of 

which is some 5 m above the flood plain. This terrace 

and outcrops of the Wasatch are sources of fresh sand 

and gravel debris wherever the river impinges laterally against them.

The level of the flood plain corresponds with the 

bankfull stage of the river, at which the water has an 

average depth of about 1.2m. The bankfull discharge is 

about 20 m3/s, which, in the annual flood series, has a 

recurrence interval of about 1.5 years. The watersurface slope in the vicinity of the project area is 

0.0007, averaged over 1.5 km of river length.

Composition of the streambed of the East Fork River 

at the project site is predominantly sand, but in the 

5-km reach of river from Muddy Creek to the project, 

gravel bars are spaced at regular intervals of about five 

to seven channel widths. Eight bed-material samples 

were collected at each of 29 sections along approximately a 200-m reach upstream and downstream of the 

bedload trap. Data of the composite size distribution of 

the 232 samples (about 200 kg) are included in table 1 

and indicate a median bed-material particle size of 1.25 

mm. The median bed-material particle sizes at each of 

the 29 sections are shown on the planimetric map of 

figure 5. The occurrence and location of gravel bars is 

apparent, as median particle sizes vary from 0.6 to 25 

mm and indicate a large range of particle sizes available for transport. However, the majority of median 

particle-size data indicate an overwhelming abundance of medium to coarse sand available for transport.

Only limited information is available describing bedforms and their characteristics. At low flows when bedload is negligible, ripples exist over the sandy portions 

of the streambed. Isolated sediment particles may be in 

motion, but generally the ripples are stationary. From 

intermediate flows to the highest discharges observed, 

the bed is either flat or has long, low dunes and is fairly 

resistant to local scour around a foreign object placed 

on the bed. The better defined bedforms, as recorded on 

sonar tracings, indicate an amplitude of about 10 cm, a 

wave length of about 10 m, and a period of about 30 

minutes. These characteristics of the dunes are substantiated by cyclic trends in measured bedloadtransport rates. However, the measured bedloadtransport rates cannot be used to quantitatively 

describe bedforms, because dune fronts traveled diagonally to the flow, whereas bedload measurements 

were taken orthogonally to the flow and integrated the 

passage of bedforms over time.

CONVEYOR-BELT BEDLOAD TRAP

Across the East Fork River, a concrete trough was 

constructed in the bed, orthogonal to the flow direction, 

that would constitute an open slot into which would 

fall any sediment moving near or on the streambed. 

The trough is 0.4 m wide and 0.6 m deep; the level of 

the lip or top surface corresponds to the natural bed, 

lower in elevation at the thalweg than near the banks. 

Figure 6 is a cross section at the bedload trap; although 

at the trap the entire wetted perimeter is bounded by 

concrete construction, only at the definite angles at 

changes in boundary projections is the cross section 

different than the preconstruction cross section.

Along the bottom of the concrete trough passes an 

endless belt of rubber, 0.3 m wide; it is threaded around 

some drive and guidance cylinders, then returns overhead, where it is supported by a suspension bridge 

across the river. Thus, sediment falling into the open 

slot drops on the moving belt, then is carried laterally 

to a sump constructed in the riverbank, where it is 

scraped off the belt. From the sump, sediment is excavated by a series of perforated buckets on an endless 

belt. The buckets lift the sediment to an elevation 3 m 

above the riverbank and dump the load into a weighing 

hopper. When the hopper is periodically evacuated by 

opening a bottom door, accumulated sediment falls on 

a horizontal endless belt that carries it in a 

downstream direction 12 m and dumps the load on a 

transverse endless belt, which, in turn, carries the debris toward the river and dumps it into the flowing 

water, to be carried downstream in a normal manner. 

In this way, trapped sediment is collected, weighed 

continuously, and returned to the river. Figure 7 provides some general views of the river and the bedload 

trap.
DESCRIPTION OF FIELD-TEST FACILITY

Channel stationing, in meters

-Median bed material 

particle size, in millimeters

»- N

FIGURE 5.—Map of East Fork River in vicinity of bedload trap;

oo 

cc LLJ

UJ

2.5

2.0

1.5

2 1-0

<

£o.B

1 o 

I

8-0.5

-1.0

Gate numbers

-20 2 4 6 8 10 12 14 16 18 20 

DISTANCE FROM LEFT BANK ABUTMENT, IN METERS

FIGURE 6. — Cross section of the East Fork River at the bedload

trap.

The concrete slot across the riverbed may be closed 

by a series of eight gates, each 1.83 m in length. The 

gated length of the slot is thus 14.6 m, constituting the 

full width of the bed active in bedload transport. The 

gates are actuated hydraulically and may be opened or

Bedload trap

data show median diameter of bed material at sections along river, 

closed individually. When the gates are open, the open 

slot or trap is 0.25 m wide. At low and moderate discharges, all gates are open so that the load accumulated in the weighing hopper represents the total for 

the river. At high discharges, gates are opened individually, and the transport rate for the whole river is 

computed by adding the rates recorded in the eight 

gates individually opened. The hopper collecting the 

debris stands on a large scale that may be read 

visually. The belt-and-bucket-transport system can accommodate a load received at a rate as great as 100 

kg/min. The weight of the trapped load is recorded each 

minute as it accumulates in the hopper, so the weights 

represent a wet sample. Numerous comparisons of the 

weight of samples when wet and after drying give a 

consistent ratio of dry/wet weight of 0.85. Mean 

transport rates are determined by averaging the 

1-minute recordings over a sampling duration of 30 

minutes to several hours.

Samples of the trapped sediment for size analysis are 

scooped from the endless belt as the weighing hopper is 

periodically emptied. Samples were collected every 

time the hopper was emptied; each sample retained 

weighed about 2 kg. These samples were taken to the 

laboratory where they were dried, sieved, and weighed
SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

FIGURE 7.—Conveyor-belt bedload sampler, East Fork River, Wyoming. A, View across river showing suspension bridge and drive 

mechanism of conveyor-belt bedload sampler; flow is relatively 

low. B, View downstream at suspension bridge; flow is relatively

by size fractions. For small samples (single emptying of 

the hopper), the entire sample was used in the sieve 

analysis. For large samples (multiple emptying of the 

hopper), the entire sample was sieved for gravel-size 

sediment (>2.0 mm) and the remainder split to about 1 

kg for sieving of the material smaller than 2.0 mm. In 

all instances, the sample retained was large enough to 

be representative of all sizes of material collected, and 

the sieving procedure maintained this accuracy 

throughout the analysis. For comparison with the 

bed-material size data in table 1, table 2 lists a 

transport-weighted particle-size distribution for the 

whole of bedload sampled in 1976. The median particle 

size of bedload is 1.13 mm, compared to 1.25 mm for 

bed material.

Although the median particle size of bedload and bed 

material is nearly the same, the bed material consists

high. C, Bedload trap on streambed is visible below suspension 

bridge; gates are in closed position. D, Vertical-lift assembly, 

weighing hopper, and conveyor belt for return of sampled sediment 

to stream.

of some larger particles that are rarely moved. For bedload and bed material, table 3 lists particle size at 

given particle-size categories (given percentage, by 

weight, finer than values). Table 3 clearly indicates 

that some bed-material particle sizes are seldom involved in the sediment-transport process.

Discharge measurements by current meter are made 

nearly every day during the sampling season from the 

suspension bridge at the project site. At low flow, all 

discharge, Q, is within the 14.6-m width of the gated 

slot; at bankfull (Q—20 m3/s) discharge, the water 

spreads over the full 19-m width of channel, but only 5 

percent of this discharge is in the near-bank zones beyond the 14.6-m wide bedload trap; at maximum discharge (45 m3/s), about 8 percent of the discharge is 

beyond the ends of the bedload trap. Though overbank 

flow onto the flood plain occurs in other reaches of the
DESCRIPTION OF FIELD-TEST FACILITY

TABLE 1. — Size distribution of composited bed material, East Fork 

River, Wyoming, at bedload-transport research project

Sieve 

diameter 

(mm)

Pan __

0.062 

.088 

.125 

.177 

.250 

.350 _

.500 _

.710 

1.00 _.

1.40 ._

2.00 __

2.80 __

4.00 _.

5.60 __

8.00 __

11.3 __

16.0 _.

22.6 __

32.0 _.

45.0 __

64.0 __.

Percentage, by weight, 

retained on sieve

_ .__ __ _ __0.3

_ _ _ __ .1

__ ________ __.4

______________1.0

_______ _____2.4

______________6.6

____ _ _____ 12.0

_____________13.5

_ __ _____ __9.1

___ ___ ___ _7.4

_______ ______6.1

______________4.7

______________4.3

______________3.6

___________ __3.6

______________3.6

__________ __4.3

4 1

______________5.1

________._____5.2

__________^___2.8

0

Percentage, by weight, 

finer than sieve

0.0 

.3 

.4 

.8 

1.8 

4.2 

10.8 

22.8 

36.2 

45.3 

52.7 

58.8 

63.5 

67.8 

71.4 

75.0 

78.5 

82.8 

86.9 

92.0 

97.2 

100.0

TABLE 2. — Size distribution of transport-weighted composite bedload 

(1976 conveyor belt), East Fork River, Wyoming, at bedloadtransport research project

Sieve 

diameter

(mm)

Pan __

0.062 

.088 

.125 

.177 

.250 

.350.

.500 

.710 

1.00 _

1.40 _

2.00-

2.80 __

4.00 _.

5.60 __

8.00 _.

11.3 _.

16.0 _„

22.6 __.

32.0 __

45.0

TABLE 3—

Percentage, by weight, 

retained on sieve

______________0.3

1

_________________ 2

. __ __ __ _ __ .4

______________1.0

______________5.3

_____________11.8

____________.15.1

118

_____________11.9

_ ____ _____12.0

______________9.9

_ ___ _ ___ _7.4

_____.________5.5

_ _ ___ ___ __3.4

____ ___ __ __1.8

______________1.0

.5

.4

________________.2

_______ __ _ _ .0

-Comparison of bed material and

Percentage, by weight, 

finer than sieve

0.0 

.3 

.4 

.6 

1.0 

1.9 

7.2 

19.0 

34.1 

45.9 

57.8 

69.9 

79.8 

87.2 

92.7 

96.1 

97.9 

98.9 

99.4 

99.8 

100.0

bedload particle sizes

Particle-size category Particle size (mm )

(d , MTMu«

£"ifi

dK

d35

C?50 

^65

d75

dM

rf«5

f fin-r than]' Bed material

______ _ __ _______0.27

___________ _________.42

____________ ____.53

_____ _____.________.69

__ _ _____ _ _ ___ 1.25

__________ _____^___3.20

________ _ ________8.00

_ ________ __________ 17.6

____________________37.6

Bedload

0.32 

.47 

.58 

.73 

1.13 

1.73 

2.37 

3.42 

7.01

river, at the project site a high natural bank on the 

right side and a short embankment on the left prevent 

any overbank flow. Essentially, all bedload is accounted for, and all the flow passes through the 19-m 

width of channel at the measuring section. 

The hydraulic-geometry relations for the East Fork 

River at the bedload trap are shown in figure 8. In 

reality, the concrete trough and abutments of the bedload trap force small "kinks" in the hydraulicgeometry relations; the relations shown in figure 8 

have been smoothed and reflect the hydraulic characteristics of the river if the bedload trap were not installed. For interpretative studies of bedload transport, 

the hydraulic conditions above the 14.6-m width of bedload trap are more significant than the whole-channel 

hydraulic conditions. These hydraulic conditions will 

be termed "effective hydraulics," and it is the effective 

hydraulic parameters that are listed in subsequent 

tabulations of data in this report. The reader may obtain corresponding stream-wide conditions by reference to figure 8. 

The bedload trap was installed in fall and spring, 

1972-73. Robert M. Myrick was project engineer for 

construction of the trap and is due much of the credit 

for subsequent successful operation of the installation. 

Data collection began in the spring of 1973 and has 

continued during spring months since then. The datacollection program for the conveyor-belt bedload sampling was initially under the direction of Luna B. 

Leopold but gradually has drifted toward co-direction 

by Leopold and the writer. Basic data for the bedload

Q~Z.

o

o

LU 

CO

LJ_ ^ 1 1 Illllll 1 I'lllll ^J\J rvLU Pn Q_ UJ

cc ' ^r ~ ^ 

LU 2 - carfare width ^X"^ ——— - 20 a:

L. ~^^^ - J

s ; ^^^ i

I0 -5 : ^^^ - 5 1

co - vc>£<5x^^ - co

CC W>^ DC 1 1 1 ^ 1 1 1

ili 0.2 - - 2 ti 

^ ^

^_ -^

0.1 ———————— ' ———— ' ——— ' 1 1 1 1 II ———————— " ————— 1 ——— ' 1 1 1 M 1 -rf= 1 2 5 10 20 50 100 f= 

g DISCHARGE, IN CUBIC METERS PER SECOND g

FIGURE 8. — Hydraulic-geometry relations for the East Fork River 

at the bedload trap.
8 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

trap have been previously published (Leopold and 

Emmett, 1976, 1977), and the same authors are presently preparing an interpretative report utilizing these 

data. Some of the data have been incorporated into a 

report (Mahoney and others, 1976) which compiled information necessary for calibrating unsteady-flow 

sediment-transport models. This latter report principally contains data of cross-sectional changes (scour 

and fill) at a number of sections in the 5-km reach of 

channel upstream of the bedload trap. Two doctoral 

dissertations (Lisle, 1976; Andrews, 1977) provide additional information about the fluvial characteristics of 

the East Fork River in the vicinity of the bedload trap. 

Use of the conveyor-belt facility for field calibration of 

the Helley-Smith bedload sampler covered the period 

1973-76, but principal data collection for the fieldcalibration purpose was May-June, 1975. The writer 

had sole responsibility for the Helley-Smith bedloadsampling program.

SAMPLING TECHNIQUES WITH 

HELLEY-SMITH BEDLOAD SAMPLER

Although the Helley-Smith bedload sampler is in 

widespread use by the U.S. Geological Survey and 

other Federal and State agencies, and by university 

and private organizations, it has not been officially 

sanctioned by the Federal Inter-Agency Sedimentation 

Committee (Water Resources Council) nor certified for 

its technical performance by the U.S. Geological Survey. This certification is awaiting completion of rigorous laboratory testing of the sediment-trapping 

characteristics of the sampler under direction of the 

U.S. Geological Survey and the Federal Inter-Agency 

Sedimentation Committee. Although laboratory testing is now underway, it appears that the early 1980's is 

a reasonable target date for completion of testing and 

certification (or possible rejection) of the sampler.

Widespread use of the sampler, but lack of certification, combine to create some confusion with sampling 

procedures. No formal technique manual for use of the 

sampler exists, and instructions for its use are generally passed on by word of mouth from user to newcomer. Even on an interim basis, this procedure is acceptable only if the user passes along instructions 

based on reliable past use of the sampler.

The writer has collected more than 10,000 individual 

bedload samples with the Helley-Smith sampler. This 

experience, combined with gained insight of temporal 

and spatial variabilities in bedload-transport rates, 

has enabled him to establish a sampling procedure for 

the Helley-Smith sampler which gives consistent results.

The spatial or cross-channel variations in bedloadtransport rates are significant. Frequently, all or most

of bedload transport occurs in a narrow part of the total 

width of channel. Though this narrow width of 

significant transport is generally stationary, it can 

shift laterally with changes in hydraulic conditions or 

sediment characteristics. Therefore, knowledge of 

where maximum or all bed load transport had occurred 

previously is not a criterion for eliminating a portion of 

channel width from the sampling program. At least 20 

equally spaced, cross-channel sampling stations are 

necessary to insure that zones of both maximum and 

minimum transport are adequately sampled. (For 

large rivers and small rivers, the technique may be 

modified so that sections are not spaced greater than 15 

m apart, nor is there apparent need for spacing sections 

closer than 0.5 m.)

Temporal variations in bedload-transport rates may 

also be large. This variation with time is obvious for 

the stream channel with movement of dunes, but even 

in gravel-bed rivers with no apparent dunes or migrating bedform, bedload transport may occur in slugs of 

sediment and show distinct cyclic trends with time. 

The frequency of the cyclic trend is dependent on the 

velocity and wavelength of the bedform or slug of sediment. Obviously, a precise procedure would be to sample at each cross-channel station until a reliable mean 

transport rate was established at each cross-channel 

location, but time requirements prohibit this detail.

The adopted procedure, a compromise between effort 

expended and idealized precision (in reality, little precision is lost), is to conduct two traverses of the stream 

and to sample at least 20 sections on each traverse. The 

spatial factor is covered by the 20 sections; the temporal factor is covered both because of the time expended during a single traverse of the stream and the 

time lag at each section as the second traverse is conducted. A comparison of values of mean transport rate, 

determined by multiple traverses of the stream, shows 

little change in the mean value by the addition of more 

than two traverses. Further, because of changes in the 

river hydraulics with time, and with each traverse of 

the river being time consuming, it is often impossible 

to conduct more than two traverses of the river and 

have the data considered as instantaneous or existing 

simultaneously. Each sample collected with the 

Helley-Smith bedload sampler requires about 2 to 3 

minutes for lowering, sampling, raising, emptying, and 

moving to a new cross-channel location. A typical 

traverse thus requires about 1 hour; two traverses require about 2 hours. The time required to complete the 

double traverse generally allows a minimum of several 

cycles to be sampled in the cyclic trend of transport; 

this appears adequate to average temporal variations 

in transport.

For the East Fork River sampling program, all bed-
RESULTS OF FIELD-CALIBRATION TESTS

load occurs over the 14.6-m length of the gated slot in 

the streambed. Eight gates constitute this width; bedload sampling with the Helley-Smith sampler was 

made at the 1/6, 1/2, and 5/6 points of each gate (centroid of each third of gate length). Thus, 24 crosschannel sections constituted the cross-channel frequency of sampling for the East Fork River. Two 

traverses of the stream total to 48 individual HelleySmith type samples, which are averaged to give a 

mean bedload-transport rate and used in the comparison with a mean bedload-transport rate for the 

conveyor-belt sampler.

The suspension bridge across the East Fork River at 

the bedload trap provided access across the river. The 

Helley-Smith sampler was lowered by cable to the 

streambed, timed for a duration of 30 seconds, and retrieved. By lowering the sampler from the upstream 

side of the bridge and placing the sampler on the 

streambed just upstream from the conveyor belt, simultaneous collections of data could be made with both 

sampling devices. Though efforts were made to have 

simultaneity in sampling, in reality, varying lengths of 

time were required to complete data collection by the 

two sampling methods. A slightly different mean stage 

or discharge may be recorded for the time period of 

Helley-Smith type sampling versus that for the 

conveyor-belt sampling. The differences were not consistent in biasing one method of sampling and were 

always minor. A later section of this report shows the 

results of corrections made to the measured bedload 

data to compensate for slight mean-discharge differences for data sets that were designed to be contemporary.

Generally, each Helley-Smith type bedload sample 

was individually bagged and later air dried, sieved, 

and weighed. Data thus collected could be later 

analyzed for cross-channel variability in transport rate 

and particle size or composited by gate length or 

whole-stream width for a comparison with the 

conveyor-belt data. Although many data are available 

for a gate-by-gate comparison of the conveyor-belt and 

Helley-Smith sampling methods, all data of this report 

are for stream-wide mean values. Thus, each point of 

comparison involves 48 Helley-Smith bedload samples 

and, generally, several hours of conveyor-belt operation. Totally, 100 runs were made with the conveyor 

belt, and 83 runs were made with the Helley-Smith 

sampler. All data are useful in separate analyses of 

percentage of total load in each particle-size class, and 

these analyses may be compared by method of collection. In addition, concurrent runs by the two methods 

can be compared directly. Comparison of total 

bedload-transport rates as measured by the two methods does not require knowledge of particle-size distribution. In this instance, there are 74 matched sets of 

data available for direct comparison. For a comparison 

on a given particle size basis, various runs combine to 

give 61 simultaneous or matched data sets. Both the 

separate analyses and the direct comparisons are the 

results described in the next section.

Figure 9 illustrates some of the techniques and procedures involved with use of the Helley-Smith bedload 

sampler.

RESULTS OF FIELD-CALIBRATION TESTS

All basic data of the study are summarized in tables 

4-7. Measured and computed river hydraulic data and 

measured bedload-transport rates are listed in tables 4 

and 6 for the conveyor-belt sampler and Helley-Smith 

sampler, respectively. Particle-size distributions of 

bedload for the transport rates listed in tables 4 and 6 

are given in tables 5 and 7 for the conveyor-belt samFIGURE 9.—Bedload sampling with the Helley-Smith bedload sampler. A, Preparing to lower sampler at relatively high flow rate. B, 

Preparing to empty sampler.
10 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

pier and the Helley-Smith sampler, respectively. For 

all analyses of this report, transport rates for given 

particle-size classes were obtained by multiplying total 

bedload-transport rate (tables 4 and 6) times the percent retained, by weight, in each particle-size class 

(from tables 5 and 7). This voluminous set of data was 

stored in computer memory during analysis of data, 

but since it can be easily duplicated, tabulations of it 

are not reproduced in this report. Although sieve 

analyses were conducted by half-phi increments (factor 

of V2), transport rates by particle-size class were 

analyzed by whole-phi increments (factor of two). This 

gave nine particle-size classes ranging in particle size 

from 0.06 mm to 32 mm; for the conveyor-belt sampler, 

several particles larger than 32 mm were measured, 

but these did not constitute a large enough sample to 

establish a reliable data set.

BEDLOAD-TRANSPORT RATES BY INDIVIDUAL 

PARTICLE-SIZE CATEGORIES, BASIC DATA

Relations of the bedload-transport rate in each 

particle-size class as functions of total bedloadtransport rate were determined for both methods of 

sampling. The statistical procedure utilized was a 

least-squares linear regression of log-transformed 

data, giving a power equation of the form:

Y = AXB , 

or more specifically:

jb (size class) = A/6 (total)8 ,

where jb is the dry weight unit bedload-transport rate 

in kilograms per meter-second.

Data of the statistical analyses are presented in tables 8 and 9 for the conveyor-belt sampler and the 

Helley-Smith sampler, respectively. Graphs of basic 

data and statistical analyses are illustrated in figures 

10-18 for various particle-size classes; for each method 

of sampling, graphs show the least-squares fit to the 

data and, superimposed, the least-squares fit to the 

data of the alternate method of sampling.

Of special interest is the percentage of total bedload 

occurring in each particle-size class. Utilizing mean 

values of X and Y data and summarizing from tables 8 

and 9:

Particle-size clas

(mm)

Mean percentage of total bedload 

in particle-size class (Y/X)

0.06- 0.12 ____ _

.12- .25 ____ _

.25- .50 _ __ _

.50- 1.00 ____ _

1.00- 2.00 ____ _

2.00- 4.00 ____ _

4.00- 8.00 ___ __

8.00-16.00

16.00-32.00 _ ___ _

Helley-Smith

.__ ______ 0.35

__________ 3.24

. _ __ 22.89

. _ _ __26.84

._.________20.07

. _____ 10.61

. __ ___ 3.45

___________ .89

_ ______ .65

Conveyor-belt

0.32

1.74

18.49

27.89

21.89

13.87

5.56

1.49

.74

Mean percentages in the above table do not add to 100, 

because the mean value of total bedload is variable. 

That is, larger particles move only during higher 

transport rates, and the mean value of total bedload 

transport is, obviously, greater during those instances. 

The effect is to decrease the apparent mean percentage 

of total bedload in the larger particle-size classes; the 

adequacy in sampling of large particles will be discussed subsequently.

Before continued discussion, it is also of interest to 

note the rate of change in the above percentages as the 

actual bedload-transport rate increases or decreases. 

This rate of change is described by the exponent of the 

regression equations, B. Summarizing from tables 8 

and 9:

Particle-size class

(mm)

Rate of change in percentage of total bedload 

in particle-size class (B)

0.06- 0.12 _________

.12- .25 _____ .

.25- .50 _ __ .

.50- 1.00 _____ .

1.00- 2.00 _____ .

2.00- 4.00 ______

4.00- 8.00 _________

8.00-16.00 _____ .

16.00-32.00 _____ .

Helley-Smith

0727

. ________ .599

.___ _ ___ _ .698

_ _____ _ 1.050

_ _______ _ 1.213

1.344

_ __ __ __ 1.193

______________ .867

_ _ _ ___ .387

Conveyor belt

0.663

.553

.742

1.000

1.173

1.278

1.211

.995

.926

Because the mesh size of the sample-collection bag 

used on the Helley-Smith sampler was 0.20 mm, data 

of the first two particle-size categories tabulated above 

should be disregarded. Probably quite by coincidence, 

the amount of 0.06 to 0.12 mm size sediment trapped 

by the conveyor-belt sampler (insignificantly at 0.3 

percent) is nearly identical to the amount of same-size 

material that was trapped in, rather than washed 

through, the Helley-Smith sample-collection bag.

The Helley-Smith sampler collects nearly twice as 

much sediment in the 0.12 to 0.25 mm size class as the 

conveyor-belt sampler. However, not only is the catch 

in the Helley-Smith sampler not valid because of the 

mesh size of the collection bag, but also analysis of 

suspended-sediment size data indicates this particlesize class represents the dominant particle sizes of suspended sand. Thus, the Helley-Smith sampler, which 

protrudes into the flow, is receiving an abundance of 

this size suspended sediment, some of which is trapped 

but the majority of which is washed through the sample bag.

For sediment in the 0.25 to 0.50 mm particle-size 

class, both samplers must retain all sediment which is 

supplied to them. The Helley-Smith sampler shows a 

greater mean percentage of total bedload in this size 

class than does the conveyor-belt sampler, but again, 

analyses of suspended-sediment data show appreciable 

quantities of this size sediment in suspension. Certainly the collection of some suspended sediment by the
BEDLOAD-TRANSPORT RATES BY INDIVIDUAL PARTICLE-SIZE CATEGORIES, BASIC DATA 11

0.001

35 i °- 0001 

'. O

0.00001

2- 8s $5

z o

0.1

0.001

0.0001

0.00001

(A) HELLEY - SMITH SAMPLER

(0.06-0.12 MM SIZE CLASS)

EXPLANATION

• 1973

D 1 974

• 1 975

O 1 976

Least From (B) be|ow

(B) CONVEYOR- BELT SAMPLER

( 0.06 - 0.12 MM SIZE CLASS )

EXPLANATION

• 1973

D 1 974

• 1975

O 1 976

From (A)

0.00001 0.0001 0.001 0.01 0.1 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER - SECOND

1.0

FIGURE 10.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 0.06-0.12 

mm size class.

Helley-Smith sampler is an explanation for its greater 

mean percentage in this size category, but a quantitative description of how much of it is attributable to this 

effect is not possible. It is most important to recognize 

that the Helley-Smith sampler does receive suspended 

sediment, and the absolute quantites of it are dependent on the sizes of sediment in transport and hydraulic characteristics of the flow—factors which are different for every stream and thus cannot be calibrated.

Complete analysis of suspended-sediment size data 

for the East Fork River shows no significant quantity 

of suspended sediment larger than 0.50 mm, For material capable of being moved in suspension (<0.50 mm), 

its significance as bedload decreases as bedload0.01

0.001

- ° 0.0001 oo Z

> O

LU CJ

O t/5

< LU 0.00001

(A) HELLEY- SMITH SAMPLER

(0.12- 0.25 MM SIZE CLASS)

EXPLANATION

• 1973

D 1974

• 1975

O 1976

Least

(B) below

0.001

0.0001

0.00001

(B) CONVEYOR-BELT SAMPLER

(0.12- 0.25 MM SIZE CLASS)

EXPLANATION

• 1973

D 1974

• 1975

O 1976

From (A) above

Least squares

0.00001 0.0001 0.001 0.01 0.1 1.0 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER- SECOND

FIGURE 11.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 0.12-0.25 

mm size class.

transport rate increases. This is reflected in the rate of 

change values (exponents) tabulated above. The values for suspended-sediment size particles are less than 

unity, indicating that as total bedload-transport rate 

increases, the percentages of sediment in those size 

classes decrease.

For sediment in the four particle-size classes ranging 

in size from 0.50 to 8.0 mm, significant bedload 

transport occurs, and the significance increases as the 

total bedload-transport rate increases. The dominant 

particle-size class of bedload is 0.50 to 1.0 mm and accounts for a little over one-fourth of the total bedload 

(recall also the size distribution of composited bedload, 

table 2). The greatest rate of change in percentage of
12 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

1.0

0.01

0.001

0.0001

i O ui o

< iu 0.00001 °- i—

UJ at- UJ

< a.

O QE

I O

1.0

0.1

0.01

0.001

0.0001

0.00001

(A) HELLEY-SMITH SAMPLER

( 0.25 - 0.50 MM SIZE CLASS )

EXPLANATION

• 1973

D 1 974

• 1975

O 1976

Least squares

From (B) below

(B) CONVEYOR - BELT SAMPLER

( 0.25 - 0.50 MM SIZE CLASS )

EXPLANATION

• 1973 

D

• 

O

From (A) abov

Least squares

0.00001 0.0001 0.001 0.01 0.1 1.0 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER-SECOND

FIGURE 12.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 0.25-0.50 

mm size class.

total bedload in a given particle-size class occurs for 

particles in the size class of 2.0 to 4.0 mm, followed by 

size classes 1.0 to 2.0 mm and 4.0 to 8.0 mm. These 

rates of change values combine with the mean percentage values such that at high bedload-transport rates 

the percentage of total bedload is actually greatest in 

particle-size categories of 1.0 to 2.0 mm and 2.0 to 4.0 

mm, This leads to a median particle size of composited 

bedload being 1.13 mm (table 3).

For sediment sizes greater than 8.0 mm, only about 

V2-2 percent of the total bedload occurs in the particlesize categories of 8 to 16 mm and 16 to 32 mm. The 

mean transport rate for these size particles is about

0.001

0.0001

0.00001

1.0

(A) HELLEY- SMITH SAMPLER

(0.50- 1 .00 MM SIZE CLASS)

EXPLANATION

• 1973

D 1 974

• 1975

O 1976

From (B) below//1

// Least squares

0.1 -

0.01 -

0.001

0.0001

0.00001

(B) CONVEYOR - BELT SAMPLER

( 0.50 -1.00 MM SIZE CLASS )

EXPLANATION

From (A) above

Least squares

0.00001 0.0001 0.001 0.01 0.1 1.0 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER-SECOND

FIGURE 13.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 0.50-1.00 

size class.

0.0004 kg/m-s (tables 8 and 9). The average 32-mm 

particle weighs about 55 grams, and the average 

16-mm particle weighs about 6.8 grams. These numbers can be manipulated to show that, streamwide, 

only about three 32-mm particles and twenty-five 

16-mm particles pass down river every 30 seconds, the 

duration of sampling with the Helley-Smith sampler. 

Since the Helley-Smith sampler covers only about 0.5 

percent of the stream width (76.2 mm nozzle/14.62 m 

wide), the Helley-Smith sampler has somewhat less 

than a 2 percent chance of collecting a 32-mm particle 

and about a 15 percent chance to collect a 16-mm particle. This is additionally reflected in the number of ob-
1.0

0.1

0.01

0.001 -

0.0001 -

BEDLOAD-TRANSPORT RATES BY INDIVIDUAL PARTICLE-SIZE CATEGORIES, BASIC DATA

i.o

13

(A) HELLEY - SMITH SAMPLER

(1 .00 - 2.00 MM SIZE CLASS )

EXPLANATION

squares

From (B) below/

0.00001

1.0

0.1

0.01

0.001

0.0001 -

0.00001

(B) CONVEYOR- BELT SAMPLER

( 1 .00-2.00 MM SIZE CLASS I

EXPLANATION

From (A) above

Least squares 

o,

0.00001 0.0001 0.001 0.01 0.1 1.0 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER- SECOND

FIGURE 14.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 1.00-2.00 

mm size class.

servations recorded in tables 8 and 9. While nearly 50 

percent of the runs with the conveyor-belt sampler included trapping a particle of size 16-32 mm, fewer 

than 25 percent of the runs with the Helley-Smith 

sampler included trapping a particle of that size. Thus, 

the transport rate for large particles in the East Fork 

River was too minimal to allow reliable calibration for 

particles larger than about 8 mm, perhaps to 16 mm. 

It should also be pointed out that the rate-of-change 

data for the two coarsest size categories are misleading. Since the largest particles move only at high 

transport rates, many low transport runs are not included in the analysis for these size particles. By this

0.1

0.01

0.001

0.0001

cc I

< £ 0.00001

(A) HELLEY-SMITH SAMPLER

(2.00-4.00 MM SIZE CLASS)

EXPLANATION

• 1973

D 1974

• 1975

O 1 976

From (B) below/

/ / Least squares

f < Q. 1.0

0.1

0.01

0.001 -

0.0001 -

0.00001

0.00001

(B) CONVEYOR- BELT SAMPLER

(2.00-4.00 MM SIZE CLASS)

EXPLANATION

• 1973

Q 1 974

• 1975

O 1 976

0.0001 0.001 0.01 0.1 1.0 

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER-SECOND

FIGURE 15.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 2.00-4.00 

mm size class.

fact alone, large particles begin their significance at 

high transport rates and increase from there. Because 

zero values cannot be used in log-transformed regressions, values of rate of change (slope of the regression equation) comparable to the smaller particle-size 

categories cannot be quantitatively determined.

This section of the results has concentrated on 

analysis of bedload-transport rates by individual 

particle-size categories as functions of total bedloadtransport rate. Its primary purpose is to place reliability limits on the comparability of data collected and 

was used to show that for particle sizes less than 0.50 

mm, the influence of suspended sediment casts doubts
14 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

1.0

0.1

0.01

0.001

0 0.0001

UJ o

rt "j O to £ I

<• Su 0.00001

1.0

o S

8s §

z o

< d 0.1 

CC i£

Q 

O 

Q

jy 0.01

0.001

0.0001

0.00001

0.00001

(A) HELLEY- SMITH SAMPLER

(4.00- 8.00 MM SIZE CLASS)

EXPLANATION

• 1973 

D 1974

• 1975 

O 1976

From (B) below

//Least squares

(B) CONVEYOR - BELT SAMPLER

( 4.00 - 8.00 MM SIZE CLASS )

EXPLANATION

• 1973 

D 1974

• 1975 

O 1976

Least squares

/From (A) above

0.0001 0.001 0.01 0.1 1.0

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER- SECOND

FIGURE 16.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 4.00-8.00 

mm size class.

on comparability (not reliability) of data collected with 

the Helley-Smith sampler. For particle sizes less than 

0.20 mm (mesh size of the bag), data collected with the 

Helley-Smith sampler should be discarded. For particle 

sizes larger than 8.0 to 16 mm, paucity of individual 

particles moving probably prohibits the Helley-Smith 

sampler from collecting a representative sample, and 

data should be treated with caution.

The above analyses and discussion are not applicable 

to a direct comparison between the Helley-Smith sampler and the conveyor-belt sampler, because the 

analysis utilized all available data rather than 

matched data sets. For example, many data collected at

1.0

o.i

0.01

0.001

^ o 0.0001

? z

LU O

-J O

O LIJ

< cc 0.00001

1.0

(A) HELLEY- SMITH SAMPLER

(8.00-16.00 MM SIZE CLASS)

EXPLANATION

• 1973

D 1974

• 1975

O 1976

From (B) below.

Least - 

squares

0.1

0.01

(B) CONVEYOR - BELT SAMPLER

(8.00-16.00 MM SIZE CLASS)

EXPLANATION

• 1973

D 1974

• 1975

O 1976

0.001 -

0.0001 -

0.0001 0.001 0.01 0.1 1.0

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER- SECOND

FIGURE 17.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 8.00-16.0 

mm size class.

low transport rates in 1976 with the conveyor-belt 

sampler were not obtained with the Helley-Smith 

sampler; this created a data base with a mean 

transport rate that is different between the two 

methods of sampling. The next section discusses a direct comparison of the two methods of sampling.

COMPARISON OF HELLEY-SMITH RESULTS WITH 

CONVEYOR-BELT RESULTS, BASIC DATA

Data collected concurrently with both the HelleySmith sampler and the conveyor-belt sampler may be 

compared directly one against the other; a total of 74
COMPARISON OF HELLEY-SMITH RESULTS TO CONVEYOR-BELT RESULTS, BASIC DATA 15

i.o

0.1

0.01

E o.ooi

</J in

< —i 

CJ

s i °-oo°1

^ 8

0.00001

(A) HELLEY- SMITH SAMPLER

(16.00-32.00 MM SIZE CLASS

EXPLANATION

• 1973

D 1974

• 1975

O 1976

Least s qua r&s

From (B) below

(B) CONVEYOR - BELT SAMPLER

16.00 - 32.00 MM SIZE CLASS

EXPLANATION

• 1973 

1974

• 1975 

O 1 976

From (A) above

0.00001

0.00001

TOTAL BEDLOAD TRANSPORT RATE,IN 

KILOGRAMS PER METER- SECOND 

O

FIGURE 18.—Relation of bedload-transport rate in individual-size 

category as function of total bedload-transport rate; 16.0-32.0 

mm size class.

such matched sets of data exists. Some of these data 

sets are composed of a single run with the conveyorbelt sampler and two runs during the same time with 

the Helley-Smith sampler, thus giving two points of 

comparison. Of the 74 data sets, some runs with the 

conveyor-belt sampler are lacking particle-size 

analyses. For comparisons made at given particle-size 

classes, 61 matched sets of data are available. Table 10 

lists matching of data sets as used in the present and 

next sections of this report.

Comparisons of the bedload-transport rate in each 

particle-size class were made with the Helley-Smith

sampler results expressed as functions of the 

conveyor-belt sampler results. As in the previous section of this report, the statistical procedure utilized 

was a least-squares linear regression of logtransformed data, giving a power equation of the form:

y = AXB ,

or, for this analysis:

7& (Helley-Smith) = A/6 (conveyor belt)B , 

where 7s is the dry-weight unit bedload-transport rate 

in kilograms per meter-second.

Results of the statistical analysis are presented in 

table 11. The sample means of the log-transformed 

transport rates (log Y and log X] and the standard deviations of the transformed values (SZXlog Y) and 

SD(log X) ) are given in table 11 (top) for each 

particle-size class; also given are the computed intercept (log A) and slope (B) for the transformed data, the 

estimated variances for these parameters (see Draper 

and Smith, 1966, section 1.4), and the values of the 

multiple correlation coefficient, r2 , for the regressions. 

Table 11 (bottom) lists the means_for the transport 

rates before the log transformation (Y and X), the ratio 

YfX, and the values of A and SE(A) (computed by taking the antilogs of log A and SE(\og A), respectively). 

The quantities SE(log A) and SE(A) should be interpreted as follows: a confidence interval for the intercept log A can be constructed by taking the lower limit 

of the interval to be log A - constant (SE(\og A)) and 

the upper limit to be log A + constant (SE(log A)). The 

limits of the corresponding interval for A are obtained 

by taking A -=- (SE(A)) constant and A x (SE(A)) constant. For a 95-percent confidence interval, the value of 

the constant is 1.96.

Graphs of basic data and statistical analyses are illustrated in figures 19-27 for various particle-size 

categories. Graphs show the least-squares fit to the 

data and, superimposed, the line of perfect agreement. 

Summarized below are salient data of table 11, utilizing the mean values of the regression statistics.

Particle-size 

class 

(mm)

0.06- 0.12 _ ____

.12- .25 __ _

.25- .50 _ ___

.50- 1.00 _____

1.00- 2.00 _ _

2.00- 4.00 _____

4.00- 8.00 _____

8.00-16.00 ____

16.00-32.00 _____

Mean ratio in transport rate; 

Helley-Smith:conveyor belt 

(F/^, in percent)

__ __ _ __ 123.08

___________211.66

___________149.98

__ __ ___ 98.70

___________ 89.36

__ ___ ___ 86.43

_ _ ___ 93.81

__ _____ _ 93.58

___________ 55.67

Rate of change in ratio 

of transport

(B)

0.928

.751

.802

.934

.868

.803

.739

.747

.501

If values of the exponents were equal to 1.0, regression relations would be linear. To test the hypothesis
16 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

oe*

UJ

at 

S 0.1

Ms a 1 CO 

UJ 1

-J oe 0.01

uj £

co oe

m UJ i- a.

2 !| 0.001

•— 5

oe oe E C3

0

co y

5 =

£E 0.0001

o

o

o 

w 0.00001

1 1 1 1

/

J

EXPLANATION x

• 1973 ' ~

D 1974 / 

• 1975 '

O 1976 /

/Perfect agreement

/

rf ^^

Least tlfm^'

squares ° )jW*

\-qrtflL*

\jCTD

&jf

>*• •

y

/+ 0.06 -0.1 2 MM

oe*

LU

OL 

<

«« 0.1

M5 O to 2

1 CO

S3 I

^ oe 0.01

X £

co ce

LU UJ

I- 0-

ce ^ 0.001

i— 4

ce oe 

O C5

OL 0 

CO j

< ^

"£ 0.0001

Q

0

O

M 0.00001

1 1 1 1 X-

/

v

EXPLANATION /

• 1973 y

D 1974 /

O 1976 Sj|«

S[jf^ ir^

Least squares ^ji f

^ ^

y1^ 

'

/

/Perfect agreement

~

y 0.25 -0.50 MM

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 19.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 0.06-0.12 mm size class.

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 21.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 0.25-0.50 mm size class.

Z ..u

ce

UJ

OL

5

1/5 « °- 1

I §

^ 0

*a1 CO

S3 I =S 55 °- 01 UJ UJ

X LU ^ s

co ce

££

2 ^ 0.001

oe ce

OL O

CO ~j

M

"£ o.oooi

Q

<C 

O

_j

O 

M 0.00001

1 1 1 1 r

EXPLANATION '

• 1973 /

D 1974 ,

• 1975 /

O 1976 y

s/

aB^C

i-|H4 jUa

- Least $$

s q ua resJfjC1^

^

/

/Perfect agreement

/

x 0.1 2 -0.25 MM

z

oe

LU

OL

S

CO

X

i

§

X

CO

LU

ce

i— 

ce 

0

QL

^

cei—

Q

<C

g

o

S

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 20. — Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 0.12-0.25 mm size class.

that the slope = 1.0 at the 5 percent level of 

significance, a 95-percent confidence interval is constructed by taking

B ± 1.96

and the hypothesis is rejected if 1.0 does not lie in the 

interval. The upper limit of the interval attained

1.0

0.1

n nn1 0.001

0.0001

0.00001

Perfect agreement/^

EXPLANATION

• 1973 

D 1 974

• 1975 

O 1976

Least squares

D D

0.50- 1.00 MM

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 22.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 0.50-1.00 mm size class.

values ranging from 0.85 to 1.07. Although several regression equations had values of slope =1.0 within the 

interval, and all values of slope indicated relations approaching linearity, the hypothesis that regression relations are linear must be rejected. Implications of the 

nonlinearity will be discussed in a later part of this 

section of the report.
COMPARISON OF HELLEY-SMITH RESULTS TO CONVEYOR-BELT RESULTS, BASIC DATA 17

x E

^ s

CO (£ 

QJ LU

< to

oc s

II

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973

D 1974

• 1 975

O 1976

Perfect / 

agreement '

Least squares

1 .00-2.00 MM

o.ooooi 0.0001 0.001 0.01 o.i 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 23.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 1.00-2.00 mm size class.

H tr

uj £

x £

< to

«= S

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

 1973 

D 1974

• 1975 

O 1976

Perfect 

agreement /

Least squar

2.00 -4.00 MM

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 24.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 2.00-4.00 mm size class.

For particle sizes less than 0.50 mm, the effect of the 

Helley-Smith sampler catching suspended sediment is 

apparent. Sampling efficiency as determined for particle sizes less than 0.25 mm should be discounted because of mesh-size limitations of the sample-collection 

bag. Data show that for sediment in the particle-size 

class of 0.25 to 0.50 mm, the Helley-Smith sampler is

< </>

Is

x E

s- 5

co cc

mi LU i— °-

°= 5

i- <

oc oc

O O

& O

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973

D 1974

• 1975

O 1976

Perfect y 

agreement/

Least squares

4,00-8.00 MM

0.00001 0.0001 o.ooi o.oi 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 25.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 4.00-8.00 mm size class.

^ s

CO CC

I- <

oc oc

O O

H

i.O

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973

D 1974

• 1975

O 1976

Perfect / 

agreement s

Least squares

8.00-16.0 MM

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN

KILOGRAMS PER METER - SECOND

FIGURE 26.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 8.00-16.0 mm size class.

about 150 percent efficient; this efficiency factor is 

valid only for the East Fork River and is dependent on 

the particular ratio of suspended load to bedload.

For particle sizes between 0.50 and 16 mm, the 

Helley-Smith sampler traps approximately the same 

amount of sediment as the conveyor-belt sampler. Average sampling efficiency for particle-size classes be-
18 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

18

cc cc

O C3

ir\ a. o*~

1.0

o.i

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1 973 

O 1974

• 1975 

O 1976

Perfect agreement

Least squares

16.0-32.0 MM

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BV CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 27.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler; 16.0-32.0 mm size class.

tween 0.50 and 16.0 mm (2Y/2X, from table 11) is 92.6 

percent. The slopes of the regression equations indicate 

a decrease in the sediment-trapping efficiency of the 

Helley-Smith sampler as the bedload-transport ate increases. Reduction in trap efficiency appears modest, 

but if extrapolation is made beyond the range of measured data, the consequences may be great.

For particle sizes greater than 16 mm, the HelleySmith sampler traps only about 50 percent of the sediment trapped by the conveyor-belt sampler. This decreased efficiency is probably related more to the paucity of large particles moving (as explained in the previous section) than to the characteristics of the sampler. The effect of a decreasing number of particles 

moving as particle size increases is also reflected in the 

decrease away from unity in values of the rate of 

change (slope of regression equations) tabulated above.

The adequacy of the above statistical treatment of 

the data has been discussed by M. deVries (oral communications, 1978) on the basis of work by deVries and 

his colleagues at the Delft Hydraulics Laboratory, 

Delft, The Netherlands. Whereas the author, thus far, 

has expressed results of regression equations with the 

conveyor-belt data as the independent variable,

jb (Helley-Smith) = A j'6 (conveyor belt)3 ,

deVries indicates that the regression should be expressed

j'6 (conveyor belt) = A' jb (Helley-SmithV.

Mathematically, the above equations express the same 

relation, but as far as the statistical analysis is concerned, they differ. DeVries points out that in practice 

the calibration curve is used to compute the actual 

transport rate from the measured rate obtained using 

the Helley-Smith sampler. This would suggest that the 

second relation above should be used. The author 

agrees that an end product might be a curve enabling 

determination of real transport rate from a sampling of 

transport rate obtained with a Helley-Smith bedload 

sampler. On the other hand, the purpose of the present 

study is an evaluation of the agreement that data collected with the Helley-Smith sampler have with data 

collected with the conveyor-belt sampler. As such, correct experimental and analytical procedures would 

demand that data collected with the conveyor belt be 

treated as the independent variable. Assumptions or 

statements of fact relating measurements with the 

conveyor-belt apparatus to real transport rates may 

then be used to imply the relation to true transport 

rates that exists with measurements obtained with the 

Helley-Smith sampler. It was implied in an earlier section of this report that the conveyor-belt apparatus 

measured the true bedload-transport rate; still, statistical analysis of the present data involves a comparison 

of the Helley-Smith bedload sampler to the conveyorbelt sampler. A later section of this report discusses 

both some shortcomings in data collected with the conveyor belt and the statistical significance in reversing 

the dependence and independence of the variables.

DeVries also points out that calibration of bedload 

samplers implies that the reading from the sampler is 

compared to the real value. Calibration, as in this investigation, usually consists of comparing average 

values of the observations, jb (Helley-Smith), with average values of the real transport, jb (conveyor belt), 

the latter being assumed to be the real transport. But, 

if a nonlinear relation exists between the measured 

transport and the actual transport, average values 

cannot be used (as deVries points out, in the same way 

log x / log x). Instantaneous measured transport 

should be compared to actual transport; however, it is 

impossible to measure actual momentary transport at 

the location of the sampler.

The Delft Hydraulics Laboratory (DHL, 1969) has 

circumvented this problem by means of a probability 

distribution of bedload-transport rate. Hamamori 

(1962), with deVries, developed a probability distribution of the ratio of instantaneous to average transport 

rates:

l+log

where P indicates the probability of a value
MODIFICATIONS TO THE BASIC DATA 19

This probability distribution is characterized by the 

largest instantaneous sample being 4 times the mean 

and 60 percent of the samples being smaller than the 

mean. It is not unlike probability distributions commonly used for meteorological data (e.g., rainfall), hydrological data (e.g., daily streamflows), or any other 

data sets where minimum values are zero and 

maximum values may be greater than twice the mean. 

That is, one large value may compensate for several 

small values so that the majority of values are smaller 

than the mean. Hamamori developed the probability 

distribution for the case of primary dunes with faster 

secondary ripples on top. DeVries reported to the 

writer that field data collected with the Arnhem sampler in the Pannerden Channel (a branch of the Rhine 

River in The Netherlands) showed good agreement 

with the probability distribution; D. W. Hubbell (oral 

communication, 1978) reported good agreement of the 

probability distribution with data collected by Einstein 

during calibration tests for the Nesper bedload sampler; and significantly, there is good agreement with 

the minute-by-minute recordings of transport as 

measured with the conveyor-belt apparatus on the 

East Fork River, Wyoming.

If the instantaneous transport rates obey the relation

7& (Helley-Smith> = A '^(conveyor belt)6 '

and the average transport rates obey this relation with 

A' and B' replaced by A and B, it can be shown that

A 1 2B

and

B' = B,

when the above probability distribution holds for the 

instantaneous rates. The effect on statistical data as 

presented in table 11 is summarized below.

Particle-size

class 

(mml

0.06- 0.12__ ___ .

.12- .25 _____ .

.25- .50 _____ .

.50- 1.00- - -

1.00- 2.00 _____ .

2.00- 4.00- ___ .

4.00- 8.00 _____ .

8.00-16.00 _____ .

16.00-32.00____.__.

A

. ____ 0.654

. ___ __ .348

.___—__ .566

.__—__ .743

. __ ___ .498

.__— .329

. __ ___ .192

________ .143

-__ ____ .016

B

0.928

.751

.802

.934

.868

.803

.739

.747

.501

A'

0.674

.390

.618

.763

.527

.359

.217

.161

.022

A '/A

1.030

1.122

1.092

1.027

1.057

1.091

1.129

1.124

1.332

Y/X 

(percent

126.77

234.48

163:78

101.36

94.45

94.30

105.91

105.18

74.15

The average effect is to increase the value of the 

coefficient by about 8 percent. The net effect, weighted

by transport rate for particle-size classes between 0.50 

and 16.0 mm is to increase the average sampling efficiency, 2Y72X, from 92.6 percent to 97.9 percent.

The brief discussion in this section has been based on 

a direct comparison of sediment trapped by the 

Helley-Smith sampler to sediment trapped by the 

conveyor-belt sampler using only basic data as collected. Two comparisons were made: one based on average values of transport as collected, and a second 

based on a conversion to real instantaneous transport. 

Certain modifications to the basic data can also be 

made; the modifications reflect refinements to the basic 

data and are based on auxiliary analyses designed to 

make the data sets more systematic and to allow for 

additional deficiencies in analytical procedures. These 

modifications are discussed in the next section; their 

influence and importance (or lack of it) will be reflected 

in the recommendations. Incorporation of modifications has been preceded by presentation of basic data in 

this and the previous section to allow more objective 

reasoning to what might be called subjective refinements.

MODIFICATIONS TO THE BASIC DATA

Rather than test the influence of various refinements 

to basic data on a particle-size class basis, testing was 

done on comparisons of total bedload as trapped by the 

two methods of sampling. Twelve refinements or combinations of refinements were attempted; statistical 

data of these attempts are included in table 12. For 

convenience, these data are summarized below and 

subsequently discussed individually.

Refinement

(see subsequent

discussion for detail)

Mean ratio in total bedloadtransport rate

HellexJ3rpith:conveyor belt

(Y/X, in percent)

Rate of change in 

ratio of transport

(B)

(1)None, basic data _____109.14

(2) Helley-Smith

independent, (1) ___109.14

(3) Conveyor-belt

corrected _______-124.49

(4) (2), (3) ___________124.49

(5) Helley-Smith

corrected, (3) ______123.01

(6) Variance corrected,

(3), (5) __________123.01

(7) Excludes d<0.25 mm,

(3) _____________122.63

(8) Excludes d<0.50 mm,

(3) ____________-109.22

(9) (3), (6), (8) _________109.22 

(10X3), (5), (7) _-___-_122.02

(11)(3), (5), (8) _________108.58

(12)(3), (5), (6), (8) --_____108.58

0.790

1.013

.856

1.102

.867

.927

.885

.916

.979

.896

.927

.991

Item (1) above includes no modification to the data 

but is an expression of the regression equation for total 

bedload. Using abbreviations of HS for the Helley-
20 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

Smith sampler and CB for the conveyor-belt sampler, 

the relation is obtained:

HS = 0.55 CB( (1)

with a mean sediment-trapping efficiency for the 

Helley-Smith sampler of 109 percent. This relation is 

graphed in figure 28.

To the eye, the least-squares relation shown in figure 

28 is not overwhelmingly a better fit to the data than is 

the line of perfect agreement. This fact led to modification (2) which reverses the independent and dependent 

variables (or simply minimizes the squares along the 

abscissa rather than the ordinate). This leads to a relation:

HS = 1.15 OB 1 - 01 , (2)

which is quite different from relation (1) but utilizes 

the same statistical procedures. By necessity, the mean 

sediment-trapping efficiency for the Helley-Smith 

sampler remains at 109 percent. A graphing of this 

relation is shown in figure 29.

Leopold and Emmett (1976, 1977) have published 

more detailed information of the conveyor-belt data 

than is reproduced in this report. For the voluminous 

data of 1976, they showed in the 1977 publication the 

gate-by-gate transport data as well as stream-wide 

values obtained either by accumulating the gate-bygate data or by operating the conveyor-belt with all 

gates open. For a number of the conveyor-belt runs, 

stream-wide data were collected utilizing both techniques of operation and representing approximately 

the same hydraulic conditions of flow. Analysis of these 

data shows that the sum-of-the-gates determination of 

stream-wide bedload was higher than the corresponding determination by operating with all gates open simultaneously and indicates an end effect at the gates 

when the gates were individually opened. The effect 

was not only consistent, involving every instance of 

data collection, but was significant. The overregistration by the individual gate method was a factor of 1.3 

and was constant over the range of transport rates investigated.

Modification (3) involves dividing by the factor of 1.3 

the conveyor-belt data which were collected by the individual gate method to correct the data for the equivalent stream-wide condition. Table 10 indicates which of 

th data were so corrected. This correction led to a regression equation:

HS = 0.76 CBC (3)

and a mean sediment-trapping efficiency of 124 percent. A graph of the data and least-squares relation is 

shown in figure 30.

% o

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973 

O 1974

• 1975 

O 1 976

Least 

squares

TOTAL BEDLOAD

o.ooooi 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 28.—Comparison of total bedload-transport rate; HelleySmith sampler (dependent variable) versus conveyor-belt sampler (independent variable).

u. ~=

CO <

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973 

D 1 974

• 1975 

O 1 976

Least squares'

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY HELLEY-SMITH SAMPLER,IN 

KILOGRAMS PER METER - SECOND

FIGURE 29.—Comparison of total bedload-transport rate; 

conveyor-belt sampler (dependent variable) versus Helley-Smith 

sampler (independent variable).

Modification (4) utilizes the data of modification (3) 

but reverses the independence of the axes as in 

modification (2). This yields a regression equation:

HS = 1.59 (4)

and retains a mean sediment-trapping efficiency of 124 

percent. This is illustrated in figure 31.
MODIFICATIONS TO THE BASIC DATA 21

1.0

= o

2 I

O CJ3

i^

°'01

0.001

0.0001

0.00001 |X_

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 30.—Comparison of total bedload-transport rate; HelleySmith sampler (dependent variable) versus conveyor-belt sampler corrected to condition of stream-wide slot (independent variable).

the mean river stage, or discharge, during the period of 

operating the Helley-Smith sampler was often, but 

only slightly, different than the mean discharge during 

the operation of the conveyor-belt sampler. Regression 

of the conveyor-belt-determined transport rates

against effective discharge (data of table 4) shows that 

bedload-transport rate is approximately proportional 

to the square of effective discharge. An appropriate 

correction factor to transpose the Helley-Smith transport data to the same hydraulic base as the conveyorbelt data would be

CB Q'HS

Values of this correction factor along with HelleySmith-determined transport data, both unaltered and 

modified by the correction factor, are listed in table 10. 

Modification (5) involves regressing corrected 

Helley-Smith data as just described against conveyorbelt data as modified in (3) above. The regression equation determined is

HS = 0.78 CB( (5)

I.U

Z

h- " 

_1 

LLJ

00 0.1

0 Q 2 z

LU 0 

> 0

Z LLJ

o 7

i! L 0.01 

>: LLJ CO £

£ ^

* S5

J- Qo £ °-°°1 

a- ^ 

% 2 < &

cc 0

h- — i

Q ^ 

< 0.0001 

0

Q 

LLJ 

03

0.00001 

0.0(

1 ' ' ' X 

/ 

EXPLANATION M Z 

• 1973 • jDfT 

D 1974 AMiT

• 1975 * S& 

O 1 976 _ jjf*

•M%J*W^ ~

Q&*

Least squares^ ••

/••

/ 

/

' Perfect agreement 

/

/ 

/ 

/

/ 

/

' TOTAL BEDLOAD

001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY HELLEY-SMITH SAMPLER, IN

KILOGRAMS PER METER -SECOND

FIGURE 31. — Comparison of total bedload-transport rate; 

conveyor-belt sampler corrected to condition of stream-wide slot 

(dependent variable) versus Helley-Smith sampler (independent 

variable).

Tt was notpd in an parlipr sprtirvn nf this rpnnrt that

ables 

inad( 

the { 

techi

pend 

with

z

FH SAMPLER,! 

MD

H §

I CO >- 1

LLJ 1

-J ee

LLJ £

I £

^ s

CO CC 

UJ LLJ 

1— °-

< CO

cc s

.OAD TRANSPORT 

KILOGRAI

Q

LLJ 

CO

and indicates a mean sediment-trapping efficiency of 

123 percent. The graph of these results is shown in 

figure 32.

Reversal of the dependent and independent varias in modifications (2) and (4), shows some 

inadequacies of a least-squares statistical procedure in 

the analysis of some data sets. Use of least-squares 

techniques usually implies that data used as the independent variable are free of error. This is not the case 

with the present data, for, indeed, the data collected

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973

n 1974

• 1975

0 1976 Least

squares

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 32.—Comparison of total bedload-transport rate; HelleySmith sampler corrected for stage difference versus conveyorbelt sampler corrected for condition of stream-wide slot.
22 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

with the conveyor belt are subject to some of the same 

variability as are data collected with the Helley-Smith 

sampler. When the independent data have an error associated with them, the least-squares technique will 

invariably yield a relation which has underestimated 

the exponent or slope value of the relation. There does 

exist, however, a statistical procedure for adjusting 

slope value by a correction factor:

or

where a, 2 is the variance of the error in the independent variable and cr.r 2 is the variance of the independent variable (see Snedecor and Cochran, 1967, p. 165).

Variance of the error in the conveyor-belt data can 

be obtained for those runs in which all gates were 

opened simultaneously and a minute-by-minute record 

was kept of the bedload-transport rate being measured. 

Necessary basic data for this determination can be 

found for conveyor-belt data collected in 1976 by reference to Leopold and Emmett (1977). Variance of the 

conveyor-belt data is obtained as part of the leastsquares regression of the present analysis. A mean 

value of the least-squares correction factor, as obtained, is 1.069. This correction factor is based on 

measured total bedload; its uniform applicability to all 

particle-size classes is not known.

Modification (6) applies this correction factor to the 

regression of modification (5) and results in

HS = 0.96 CB° - 93 , (6)

and the mean sediment-trapping efficiency remains at 

123 percent. This is graphed in figure 33.

It was earlier shown that collection of suspended sediment influences trap efficiency of small-size particles 

for the Helley-Smith sampler. Modification (7) uses the 

corrected conveyor-belt data of (2) but excludes sediment particles smaller than 0.25 mm. The resulting 

regression is

HS = 0.85 C5°- 89 (7)

and indicates a mean sediment-trapping efficiency of 

123 percent. The graphic relation is shown in figure 34. 

Modification (8) is identical to modification (7) except 

that it excludes all sediment particles smaller than 

0.50 mm, the upper limit of particle sizes associated 

with suspended sediment. The new regression equation 

is

HS = 0.82 Cfi 0 - 92 , (8)

and a resulting mean sediment-trapping efficiency is 

109 percent. The relation is graphed in figure 35.

1.0

<

CO

II

£j I 0.01

.001

0.0001

0.00001

EXPLANATION

• 1973 

D 1 974

• 1 975

O 1 976 Least

squares

.Perfect agreement

TOTAL BEDLOAD

0.00001 0.0001 0.001 0.01 0.1 1.0

BEOLOAO TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER- SECOND

FIGURE 33.—Comparison of total bedload-transport rate; HelleySmith sampler corrected for stage difference versus conveyorbelt sampler corrected for condition of stream-wide slot; relation 

corrected for variance of the independent variable in the leastsquares regression.

o CD fc Q

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973 

D 1974

• 1 975 squares 

O 1976

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 34.—Comparison of total bedload-transport rate for sediment particles larger than 0.25 mm; Helley-Smith sampler versus conveyor-belt sampler corrected for condition of stream-wide 

slot.

Modification (9) is similar to modification (8) except 

that it also includes correction for variance of the independent variable. The new result is

HS = 1.02 C5" 98 , (9)
MODIFICATIONS TO THE BASIC DATA 23

18

00 CC

< to

I- <

cc cc

O C3

5s 5

1.0

0.1

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973 

D 1 974

• 1975 

O 1976

Least squares

'Perfect agreement

TOTAL BEDLOAD

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 35.—Comparison of total bedload-transport rate for sediment particles larger than 0.50 mm; Helley-Smith sampler versus conveyor-belt sampler corrected for condition of stream-wide 

slot.

and the mean trap efficiency remains at 109 percent. 

Figure 36 illustrates this regression.

Modification (10) involves regressing corrected 

Helley-Smith data against corrected conveyor-belt 

data (5) but also excludes sediment particles smaller 

than 0.25 mm. The relation determined is

HS = 0.87 CB°- 90 (10)

and includes a mean sediment-trapping efficiency of 

122 percent. The relation is illustrated in figure 37.

Modification (11) is similar to (10) except that it excludes sediment particles smaller than 0.50 mm. The 

regression is

HS = 0.84 CB°- 93 (11)

and yields a mean sediment-trapping efficiency of 109 

percent. This relation is illustrated in figure 38.

Modification (12) utilizes the regression of (11) and 

further includes correction for the variance of the independent variable. This regression yields a comparison 

of the Helley-Smith sampler to the conveyor-belt sampler of

HS = 1.05 CB°•" (12)

and gives a mean sediment-trapping efficiency of the 

Helley-Smith sampler of 109 percent. The relation is 

illustrated in figure 39.

The 12 modifications to the basic data give some regression equations that are quite different from some

fc O

1.0

0.1

0.01

0.001

0.0001

0.00001 /

EXPLANATION

• 1973 

D 1974

• 1975 

O 1 976

Least squares

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 36.—Comparison of total bedload-transport rate for sediment particles larger than 0.50 mm; Helley-Smith sampler versus conveyor-belt sampler corrected for condition of stream-wide 

slot; relation corrected for variance of the independent variable 

in the least-squares regression.

0.01

0.001

0.0001

0.00001

EXPLANATION

• 1973 

D 1974

• 1975 

O 1976

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 37.—Comparison of total bedload-transport rate for sediment particles larger than 0.25 mm; Helley-Smith sampler corrected for stage difference versus conveyor-belt sampler corrected for condition of stream-wide slot.

of the others, though reference to figures 28-39 indicates that throughout the measured range of transport 

rates, the variation is not as large as might be imagined. The real importance lies in extrapolation of relations some distance from the range of measured data,
24 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

CO

X §

i§I co

S I

CC CC

O O

ft; O

i.o

0.1

0.01

0.001

0.0001

0.00001

~7\

EXPLANATION

• 1973

D 1 974

• 1975

O 1 976

Least squares

Perfect agreement

TOTAL BEDLOAD

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BV CONVEVOR BELT, IN 

KILOGRAMS PER METER- SECOND

FIGURE 38.—Comparison of total bedload-transport rate for sediment particles larger than 0.50 mm; Helley-Smith sampler corrected for stage difference versus conveyor-belt sampler corrected for condition of stream-wide slot.

§

< CO 0= &

h- <

CC CC

1.0

0.1

0.01

0.001

0.0001

0.00001

~7

EXPLANATION

• 1 973 

D 1 974

• 1 975 

O 1 976

Least squares

/Perfect agreement

TOTAL BEDLOAD

0.00001 0.0001 0.001 0.01 0.1 1.0

BEDLOAD TRANSPORT RATE BV CONVEVOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 39.—Comparison of total bedload-transport rate for sediment particles greater than 0.50 mm; Helley-Smith sampler corrected for stage difference versus conveyor-belt sampler corrected for condition of stream-wide slot; relation corrected for 

variance of the independent variable in the least-squares regresbecause the difference in relations (1) to (12) generally 

increases in significance as the transport rate increases 

or decreases from the mean transport rate as determined in the study. It becomes a decision as to which

modifications to the basic data should be employed, and 

the reasoning for their use.

The writer believes all of the modifications are objective and relevant, but, lest a reader disagrees, this is 

the reason the basic data are presented first. Though 

all of the modifications may be relevant, it is apparent 

in the comparison of equations (5) to (3), (10) to (7), and 

(11) to (8) that the effect of correcting the Helley-Smith 

results to accommodate the slight differences in river 

stage is very modest and may be neglected. The correction for excluding suspended-sediment size particles 

(<0.50 mm) has no bearing on a comparison of the two 

methods of sampling on a particle-size class basis, 

when particle sizes are greater than 0.50 mm. Thus 

these two corrections need not be further considered.

The correction for error in the independent variable 

affects slope value of the relation only; it does not influence the value of mean sediment-trapping efficiency. 

It is not known with certainty if the slope correction 

factor can be applied equally to all particle-size classes; 

it thus becomes subjective in its application. This dilemma may be solved by not using the correction factor, utilizing mean sediment-trapping efficiency as determined, and recognizing that the rate of change in 

trap efficiency (exponent value of the regression equation) should be increased by an amount less than 10 

percent of its value.

This leaves only the correction applied to some of the 

conveyor-belt data (table 10) to normalize these data to 

the condition of a continuous stream-wide open slot. 

Utilizing only this modification to the data, table 13 

lists a summary of the statistical data generated when 

regressing the Helley-Smith sampler data against the 

conveyor-belt sampler data on a particle-size class 

basis. Graphings of data and least-squares relations 

are shown in figures 40-48.

A summary of the pertinent statistics from table 13 

are listed below.

Particle-size 1 

class 

(mm)

0.06- 0.12 _ _ __ _

.12- .25 __ ____ _.

.25- .50 __________

.50- 1.00 __________

1.00- 2.00 __________

2.00- 4.00 _ _

4.00- 8.00 __________

8.00-16.00 __ ____ _

16.00-32.00 _________

Vtean ratio in transport rate 

Helle£.Smith:conveyor-belt 

(Y/X, in percent)

^___143.03

.______246.00

.___ ,174.34

._ ___ 114.74

.___ _ 103.88

___100.47

._ - _109.06

.___ _ 109.04

_______ 72.38

Rate of change in ratio 

of transport 

(Si

1.030

.868

.914

1,016

.923

.848

.775

.788

.501

Information on particle-size classes 0.06 to 0.12 mm 

and 0.12 to 0.25 mm is discarded. These are particle 

sizes nominally in suspension; further, the mesh collection bag for the Helley-Smith sampler cannot accommodate these sizes of sediment.
MODIFICATIONS TO THE BASIC DATA 25

*

oc

LLJ

_l 

Q_

co 0.1

T O

*"" ^5

co LLJ

\ CO £] i H ee 0.01 —— * Ml

T ^ 

X UJ s s

00 OC

LLJ LLJ

1- °-

2 ig 0.001

t— < 

oc oc

O O

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Is°=. 0.0001

a

<t

0

*

03 0.00001

I 1 1 1 /

EXPLANATION /

• 1 973 /

D 1974 / -

• 1975 / 

O 1 976 /

/

/

/Perfect agreement

/

/

\& /

Least rSf}'

squares tySfSh

\ ^Ja^

- \ nJV~

\rnLm jffy^^ Q

^^b

/f 0.06-0. 12 MM

z

oc

LLJ

Q.

to 0.1

l|

1 CO

UJ 1

^ ee 0.01

>• ^

oa ce

UJ LLJ

2 ^ 0.001

1- <

oc oc

O O OB ^D CO ~j

5 =

£E 0.0001

0

g

o

M 0.00001

i i i i /

/

EXPLANATION

• 1973 / -

0 1974 /

O 1976 SwP

Jjvv

»|W»

Least squares/iy

<D /

/

/Perfect agreement

~

,

/

/

/ 0.25 -0.50 MM

0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 40.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 0.06- 

0.12 mm size class.

tr\ 58^^

0.01 -

O CJ & o

0.00001

0.001 -

0.0001 -

0.00001 0.0001 0.001 0.01

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 41.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 0.12- 

0.25 mm size class.

For sediment in the particle-size class of 0.25 to 0.50 

mm, the Helley-Smith sampler has a sedimenttrapping efficiency of about 175 percent. Much of this 

overregistration is due to collection of suspended sediment, but no separate quantification can be made of 

the bedload sediment-trapping efficiency. The particu0.00001 0.0001 0.001 0.01 0.1 1.0 

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 42.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 0.25- 

0.50 mm size class.

1.0

0.1

I CO

Lu I

i E

as ce

0.001

0.0001

0.00001

EXPLANATION

• 1 973 

D 1974

• 1975 

O 1 976

Least 

squares

0.00001 0.0001 0.001 0.01 0.1 i.o

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 43.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 0.50- 

1.00 mm size class.

lar value of 175 percent is related to the proportion of 

bedload to suspended load in this particle-size class and 

may be a number unique to hydraulic and sediment 

characteristics of the East Fork River. It is not unreasonable, though purely speculative, that sedimenttrapping efficiency for this particle-size class may be
26 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

O C3

EXPLANATION

• 1973 

D 1 974

• 1 975 

O 1976

0.0001 -

0.00001 </ 

0.00001 0.0001 0.001 0.01

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 44.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 1.00- 

2.00 mm size class.

0.1 -

1 §

O C3

0.001

0.0001

0.00001 /

EXPLANATION

• 1973

a 1

0.00001 0.0001 0.001 0.1 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 45.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 2.00- 

4.00 mm size class.

near ideal for conditions involving no suspendedsediment transport.

For particle-size classes between 0.50 mm and about 

16 mm, there is good agreement between the transport 

rate measured with the Helley-Smith sampler and that 

measured with the conveyor-belt sampler. Exponent

CO CC

OJ %> I- °-

< if)

h- <

cc cc

O C3

1.0

0.1

0.01

0.001

0.0001 -

0.00001

EXPLANATION

• 1973 

D 1974

• 1975 

O 1976

Perfect 

agreement

°O ^^^ Least squares

8.00- 16.0MM

0.00001 0.0001 0.001 0.01 1.0

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 46.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 4.00- 

8.00 mm size class.

1.0

0.1

I §

EXPLANATION

• 1973 

D 1 974

• 1975 

O 1976

. 0= 5

O C3 

ft; Q

0.001

0.0001

0.00001

Least 

squares

0.00001 0.0001 0.001 0.01

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER-SECOND

FIGURE 47.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 8.00- 

16.0 mm size class.

values of the regression equations indicate that trap 

efficiency of the Helley-Smith sampler decreases 

somewhat as transport rate increases, but correction 

for the error in the independent variable makes the 

actual decrease less than the apparent decrease in trap 

efficiency. Considering all factors involved in the ex-
REFERENCES CITED 27

n

I.W

0.1

0.01

0.001

0.0001

0.00001 

0.0

EXPLANATION /

" 1973 Perfect / 

D 1 974 agreement /

• 1975 / 

O 1 976 /

/

^'^l.easl squares

/ °** °

f 16.0-32.0 MM

D001 0.0001 0.001 0.01 0.1 1.

BEDLOAD TRANSPORT RATE BY CONVEYOR BELT, IN 

KILOGRAMS PER METER - SECOND

FIGURE 48.—Comparison of bedload-transport rate by individual 

particle-size category, Helley-Smith sampler versus conveyorbelt sampler corrected for condition of stream-wide slot; 16.0- 

32.0 mm size class.

perimental arrangement, the Helley-Smith bedload 

sampler may be considered as perfect a bedload sampler for these sizes of particles as is the conveyor-belt 

apparatus.

For particle sizes greater than about 16 mm, the 

Helley-Smith bedload sampler yields an apparent low 

sediment-trapping efficiency. This low trap efficiency is 

related to the paucity of large particles moving as bedload in the calibration stream and does not necessarily 

reflect an actual low trap efficiency for large particles.

SUMMARY AND RECOMMENDATIONS

The sediment-trapping characteristics of the 

Helley-Smith bedload sampler were studied by comparing sediment-transport rates as measured with the 

Helley-Smith sampler with those measured utilizing 

an open slot constructed across a streambed. The 

number of data sets used in the comparison is large, 

and range in measured transport rates is nearly 1,000- 

fold.

Unaltered basic data indicate the Helley-Smith bedload sampler, for the majority of sediment sizes available in the study, is 90 to 100 percent efficient, but efficiency decreases somewhat with increases in transport 

rate. Modifications of the basic data to normalize the 

data sets and correct for statistical procedures indicate 

trap efficiency is 100 to 110 percent and varies little 

with changes in transport rate.

Based on all analyses of this report, the following 

recommendations are made relative to the sedimenttrapping characteristics of the Helley-Smith bedload 

sampler:

(1) The Helley-Smith bedload sampler should not be 

used for sediment particles smaller than 

0.25 mm.

(2) The Helley-Smith bedload sampler should not be 

used for measuring bedload-transport rates for 

sediment of particle sizes which also are 

transported as suspended sediment.

(3) The trap efficiency for sediment in the particle-size 

class of 0.25 to 0.50 mm was indeterminate, 

being 175 percent in the test stream; 100 percent 

is recommended for the condition of no 

suspended-sediment transport.

(4) For sediment of particle-sizes larger than 0.50 mm 

and smaller than 16 mm, sediment-trapping efficiency of the Helley-Smith bedload sampler may 

be assumed as 100 percent, with no change in 

efficiency with changes in transport rate.

(5) Trap efficiency for sediment particles larger than 

16 mm was indeterminate, being about 70 percent in the test stream; reduction in efficiency 

was related to the small number of large particles moving; actual efficiency may increase with 

an increase in the transport rate of particles 

larger than 16 mm. Obviously, trap efficiency 

goes to zero when particle size exceeds nozzle 

opening; no data are available to define trap efficiency as particle sizes approach nozzle dimensions.

ACKNOWLEDGMENTS

In addition to principal assistance in project activities that have been noted previously in appropriate 

sections of the text, I would like to thank Steve Parsons 

for the laborious task of sieving the samples; Holly 

Mahoney, Shirley Stewart, and Brent Troutman for assistance in data analysis and manuscript preparation; 

and Verne Schneider, William Curtis, Tom Lisle, Paul 

Benedict, Michael Foley, and especially M. deVries for 

their review of the draft manuscript. The field site is 

located on the property of Howard Routh. Henry Yake, 

Harvey Taylor, and Wilfrid Edwards are local businessmen who provided services and materials essential 

to successful maintenance of the research installation.

REFERENCES CITED

Andrews, E. D., 1977, Hydraulic adjustment of an alluvial stream 

channel to the supply of sediment, and, scour and fill in an alluvial stream channel: Unpublished Ph.D. dissertation, University of California, Berkeley, California, 152 p.

Draper, H. R., and Smith, H., 1966, Applied Regression Analysis: 

New York, John Wiley and Sons, Inc., 407 p.
28 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

Druffell, L., Emmett, W. W., Schneider, V. R., and Skinner, J. V., 

1976, Laboratory calibration of the Helley-Smith bedload sediment sampler: U.S. Geological Survey Open-File Report 76-752, 

63 p.

DHL, 1969, Calibration of bedload transport samplers (in Dutch): 

Delft Hydraulics Laboratory report M601-III.

Hamamori, A., 1962, A theoretical investigation on the fluctuation of 

bedload transport: Delft Hydraulics Laboratory report R4.

Helley, E. J., and Smith, W., 1971, Development and calibration of a 

pressure-difference bedload sampler: U.S. Geological Survey 

open-file report, 18 p.

Hubbell, D. W., 1964, Apparatus and techniques for measuring bedload: U.S. Geological Survey Water-Supply Paper 1748, 74 p.

Leopold, L. B., and Emmett, W. W., 1976, Bedload measurements, 

East Fork River, Wyoming: National Academy of Science Proceedings, v. 73, no. 4, p. 1000-1004.

———— 1977, 1976 bedload measurements, East Fork River, Wyoming: National Academy of Science Proceedings, v. 74, no. 7, p. 

2644-2648.

Lisle, T. E., 1976, Components of flow resistance in a natural channel: Unpublished Ph.D. dissertation, University of California, 

Berkeley, California, 60 p.

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 sediment-transport models, East Fork 

River, Wyoming, 1975: U.S. Geological Survey Open-File Report 

76-22, 293 p.

Schoklitsch, A., 1950, Handbuch des Wasserbaues [2nd ed.]: 

Springer, Vienna, English translation by S. Shulits.

Snedecor, G. W., and Cochran, W. G., 1967, Statistical Methods: 

Ames, Iowa State University Press, 593 p.
TABLES 4-13
30 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

TABLE 4.—Summary data of river hydraulics and bedload transport, conveyor-belt sampler

River discharge

Date 1

5-26-73 

5-28-73 

5-29-73 

6-01-73 

6-02-73

6-03-73 

6-06-73 

6-07-73 

6-08-73 

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 

5-27-75 

5-30-75 

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 

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 

5-18-76 

5-19-76

5-20-76 

5-20-76 

5-21-76 

5-22-76 

5-26-76

Total, 2 

Q

(m3/s)

__ _____ _ 17.0

_ ____ __ _6.66

_______ _ -7.50

_ __ _______17.0

___________ -18.8

——————17.5

-— __ —11.8

__———____16.7

——————20.3

_ _ _ 5.44

——————10.3

_________ _22.9

_______ __ -32.0

_______ _ 45.0

——————34.6

— _ .24.4

25.9

_ __ ____ ___27.2

_ __ _ -31.9

— _ — - —29.9

___ _ ——28.3

9 44

_ _ ___ _2.04

———————5.98

——————_9.52

___ --10.5

— — _ —11.2

_ ———-21.3

———————26.6

_ __ ———27.5

_ -—————26.2

— ______ 15.3

— __ —— -10.6

_ _ —————16.7

— __ ———27.6

———————31.4

— __ _ ——32.8

——————23.8

____ -13.5

_______ _ -10.5

—— __ ——7.48

_——————7.25 

_ —————8.55

— ————— 11.3

—— ——— _23.2

- ___ ———13.8

_ _ ___ 24.8

________ ____23.0

___ ________ _10.4

___ ___ 15.7

— _________ 20.3

—————21.0

_______ —24.0

- _ ————18.6

_________ _ 10.3

Effective,3 Q'

(m3/sl

16.1 

6.50 

7.30 

16.1 

17.8

16.6 

11.3 

15.9 

19.2 

5.34

9.92 

21.5 

29.8 

41.5 

32.2

22.9 

24.3 

25.5 

29.7 

27.9

26.5

2.44 

2.04 

5.82 

9.13

10.0 

10.7 

20.0 

24.8 

25.6

24.3 

14.4 

10.1 

15.8 

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 

9.87 

14.8

18.9 

19.6 

22.4 

17.5 

9.77

Mean 

depth/ 

D

(ml

1.04 

.55 

.59 

1.04 

1.11

1.06 

.81 

1.03 

1.17 

.48

.74 

1.27 

1.60 

2.01 

1.68

1.33 

1.38 

1.43 

1.59 

1.52

1.47 

.28 

.24 

.51 

.70

.74 

.78 

1.21 

1.40 

1.44

1.38 

.96 

.75 

1.02 

1.44

1.57 

1.62 

1.30

.88 

.75

.59

.58 

.65

.78 

1.28

.90 

1.34 

1.27 

.78 

1.01

1.19 

1.22 

1.33 

1.13

.77

Mean 

velocity,5 

V

(m/s)

1.06

.81 

.84 

1.06 

1.09

1.07 

.96 

1.06 

1.19 

.76

.92 

1.15 

1.28 

1.41 

1.31

1.18 

1.20 

1.22 

1.27 

1.25

1.23 

.61 

.57 

.78 

.90

.92 

.94 

1.13 

1.21 

1.22

1.20 

1.03 

.92 

1.06 

1.22

1.27 

1.28 

1.17 

.99 

.92

.84 

.83 

.87 

.94 

1.16-

1.00 

1.18 

1.16 

.87 

1.00

1.09 

1.10 

1.15 

1.06

.87

Unit 

bedloadtransport 

rate,6

(kg/m-s)

0.0122 

.0009 

.0011 

.0190 

.0235

.0240 

.0133 

.0260 

.0218 

.0056

.0822 

.1758 

.2255 

.2912 

.0786

.0647 

.0206 

.0130 

.0172 

.0285

.0305 

.0021 

.0016 

.0484 

.0791

.0812 

.0972 

.3114 

.2069 

.1733

.0833 

.0348 

.0110 

.0277 

.0926

.1190 

.1190 

.0796 

.0106 

.0097

.0032 

.0047 

.0062 

.0194 

.0838

.0396 

.2159 

.0317 

.0838 

.1359

.1163 

.1295 

.1769 

.0754 

.0130

Bedload size, 7 

rfso 

(mm)

1.35

.74

~~~98 

.54

.59 

1.03 

1.40 

1.52 

1.51

1.40 

.94 

.99 

.88 

.92

.81

.74

1.16 

1.26 

1.36 

1.28 

1.41

1.35

.50 

1.27

1.05 

1.19 

1.36

.73

.70 

.64 

.77 

.98 

1.10

.99 

1.63 

.91

.98 

1.04

.96

1.04 

1.52 

1.56 

.71
TABLES 4-13 31

TABLE 4.—Summary data of river hydraulics and bedload transport, conveyor-belt sampler—Continued

River discharge

Date 1

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 ______

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 __ ___

Total, 2

Q

(m-Vsl

— _ 15.2

_ _ -14.5

20 1

——21.2

.22.0

__ __22.4

17 7

16 8

__ __ 15.2

19 1

_____ _19.0

__—_23.2

_____ 23.4

_ __ 24.0

_ _-_24.2

-26.5

______ 22.7

_ -.20.1

19 5

14 6

——— 15.4

16 1

-__ .15.3

______ 13.9

— — 11.8

______ 11.0

_____ 10.1

______ 8.89

_____ 6.80

______ 5.13

______ 4.79

___— 3.96

_ _ _ 3.51

______ 5.13

______ 3.99

_____ 4.30

______ 4.70

_ ——— 10.0

Effective, 1 Q'

(mVs)

14.3 

13.7 

13.0 

18.8 

19.8

20.5 

20.9 

20.9 

16.6 

15.8

14.3 

13.9 

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

Mean depth, 1 D

(ml

.99 

.96 

.93 

1.18 

1.23

1.25 

1.27 

1.27 

1.09 

1.06

.99 

.97 

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

Mean 

velocity, 5 

V

(m/s)

.99 

.97 

.96 

1.08 

1.10

1.12 

1.12 

1.12 

1.04 

1.02

.99 

.98 

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

Unit 

bedloadtransport 

rate,6

(kg/m-s)

.0232 

.0301 

.0233 

.0437 

.0454

.0712 

.0618 

.0774 

.0621 

.0405

.0361 

.0325 

.0576 

.0463 

.0834

.0871 

.0918 

.0784 

.0908 

.0869

.0570 

.0513 

.0346 

.0290 

.0253

.0289 

.0280 

.0629 

.0236 

.0181

.0169 

.0162 

.0145 

.0106 

.0084

.0028 

.0022 

.0020 

.0003 

.0004

.0009 

.0006 

.0009 

.0023 

.0181

Bedload

size, 7

(mm)

.59 

.61

.77 

.95 

1.11

1.30 

1.67 

1.29 

1.09 

.98

.81 

.80 

.94 

1.04 

1.18

1.40 

1.76 

1.51 

1.30 

1.35

1.24 

1.03 

1.08 

1.06 

.84

1.05 

1.02 

1.07 

.79 

.81

.77 

.81 

.82 

.82

.77

.49 

.41 

.53 

.66

.88

.50 

.42 

.44 

.43 

.68

'Dates correspond to dates listed in table 5. 

2Complete river discharge including overbank flow. 

3Discharge over 14.6-m width of bedload trap; includes all flow over the active width of the streambed.

'Mean depth over effective width W; D = . 

5Mean velocity of effective discharge;

VW

V =.

WD 14.6D

"Unit transport rate of solids in dry weight per second, over 14.6-m width of bedload trap. 

7 dv, is median diameter of grams; complete grain-size data are given in table 5.
32 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

TABLE 5.—Particle-size distribution of bedload sediment, conveyor-belt sampler

5-26-73

16.1 

0.0122

5-28-73

6.50 

0.0009

5-29-73

7.30 

0.0011

6-01-73

16.1 

0.0190

6-02-73

17.8 

0.0235

6-03-73

16.6 

0.0240

6-06-73 6-07-73

11.3 15.9

0.0133 0.0260

6-08-73

19.2 

0.0218

5-25-74

5.34 

0.0056

5-26-74

9.92 

0.0822

5-27-74

21.5

0.1758

5-28-74

29.8 

0.2255

5-29-74

41.5 

0.2912

Percent by weight finer than sieve size (mm) indicated

09 3

.12____ _ .4 

.18_____ 7

.25 1 3 

.35______ 3.7 

.50 ___ _ 9.9 

.71 22.1 

1.00 36.8 

1.41______ 52.0 

2.00 ___ _ 67.6 

2.83______ 80.0

4.00 88.8

5.66 ... 95.7

8.00 __ _ 98.2 

11.3 ______ 99.4

32 0

45 0

( .7 

1.3

2.6 

7.4 

22.1 

48.2 

62.6 

73.0 

83.3 

90.9

96.2

98.4

99.7 

100.0

l 0.1 0.3 0.2 __ _

.3 .5 .5 0.1 ______ 0.1

.4 1.1 1.0 .3 0.1 .1 

1.0 2.8 2.1 .6 .1 .3

1.9 8.9 4.3 1.4 5 .5 

4.8 27.0 13.0 4.6 1.9 1.4 

13.8 46.2 38.3 15.6 6.9 5.6 

34.0 63.8 62.6 32.4 18.8 17.3 

51.2 75.9 75.3 48.8 34.1 33.5 

65.6 85.1 83.5 62.3 50.4 47.4 

77.9 92.3 90.8 75.7 66.8 59.4 

87.9 96 1 95.8 85.5 78.8 69.0

94.9 98.2 98.7 92.2 88.2 76.5

98.1 99.2 99.5 95.1 93.2 81.0

99.5 99.7 99.8 96.5 96.1 83.6 

100.0 100.0 100.0 97.2 97.7 85.7

97.7 98.5 86.5

98.2 99.4 87.5

_ ___ _ 100.0 100.0 87.9

. __ 89.2

____ 100.0

Particle size (mm) at given percent finer

d-, __

d, K -

d-,-

<--„, - 

eta - 

dM - 

dr, __

Date 1 Q' 2 -

j. 3 ---

-__ 0.39 

__ ___ .61

_______ .96

______.1.35

_--__-_1.88 

_-_____3.27 

_______5.38

_ 5-30-74 

___ _ 32.2 

___ _ 0.0786

(

( 

( 

( 

i 

( 

( 

(

0.31 ( ( 

.44 ( 

.60 ( 

.74 ( 

1.08 ( 

206 ( 

3.61 (

______( 

______( 

______( 

____! 

__ __ ( 

__ ___( 

__ _ _(

0.36 

.52 

.72 

.98 

1.39 

2.44 

4.03

5-31-74 6-01-74 6-02-74 6-03-74 6-04-74 6-05-74 5-27-75 5-30-75 

22.9 24.3 25.5 29.7 27.9 26.5 2.44 2.04 

0.0647 0.0206 0.0130 0.0172 0.0285 00305 0.0021 0.0016

0.21 

.29 

.41 

.54 

.73 

1.36 

2.51

6-02-75 

5.82 

0.0484

0.26 

.37 

.48 

.59 

.75 

1.45 

2.63

6-03-75 

9.13 

0.0791

0.36 

.50 

.75 

1.03 

1.51 

2.67 

5.57

6-04-75 

10.0 

0.0812

0.45 

.66 

1.02 

1.40 

1.92 

3.39 

6.89

6-05-75 

10.7 

0.0972

0.48 

.69 

1.04 

1.52 

2.44 

8.71 

48.9

6-06-75 

20.0 

0.3114

Percent by weight finer than sieve size (mm) indicated

0.06 . .... 0.1 

.09 ... . 1 

.12 ... .3

.18 ..... .6 

.25. .___ 12

.35 — — 2.6

.50 7.6

.7i______ 182 

100.. . _.. 32.3 

1.41 _ _ . 47.1 

2 00 . 63.0 

2.83 76.3 

4 00 86.4

5.66 ______ 92.6

8.00 .._. 965 

11.3 ____ 98.3

32.0 ___ __

45 0

64.0 _____________

0.1

.3 

1.1

4.0

10.0

22.3 

36.4 

49.6 

64.2 

77.3 

88.0

935

97.0 

98.7 

99 4

0.1 

.2 

.4

.8 

2.5

9.8

23.3

37.2 

52.6 

65.3 

77.3 

86.1 

92.5

96.5

98.3 

99.4

0.2 

.4 

.9

1.5 

3.5

11.5

26.1

38.5 

50.4 

60.7 

71.1 

80.4 

88.0

92.8

95.4 

97.6 

98 5

0.1 

.3

1.2 

3.2

43.3 

54.2 

63.7 

73.3 

81.9 

90.1

98.5 

1000

0.1 

.2

.8 

1.9

38.8 

53.4 

65.8 

774 

85.7 

91.9

97.9 

99.6

0.2 

.4

1.0 

2.2

45.0 

58.3 

69.3 

80.0 

879 

937

96 9

99.0 

100.0

i

( 

(

0.5 ( 

.7 ( 

1.1 (

1.9 

4.3

14.2

30.8

48.1 

60.8 

73.7 

85.7 

92.2 

96.5

99.0

99.8 

100.0

0.2 

.3

.8 

1.6

48

14.4

29.1 

43.1 

59.0 

76.7 

89.4 

96.5

99.7 

99.8 

100.0

0.2 

.3

.4

.6 

1.0

3.2

10.4

24.2 

38.6 

55.5 

73.5 

86.9 

95.4

98.6

99.5

99.8 

100.0

0.2 

.2 

.3

.4

.8

2.3

8.2

21.9 

36.1 

51.7 

69.3 

82.6 

91.6

95.8

97.9 

98.8 

99.6

100.0

Particle size (mm) at given percent finer

d, ... _ ___

£.,„ _________ 

dr, ____ _

d-M _________

rf,r, —— —— -

f/M ——— ——— ———

di

.67 

1.07

2.10 

3.66 

6.83

.60

.97

2.04 

3.47 

6.40

0 29

.42 

.67 

94

1.40 

2.59

8.84

0 27

.40 

64 

99

1.62 

331 

7.52

.37 

.56

1.48 

307 

566

0 31

43 

65 

92

1.38 

263 

523

.40 

.56

1.23 

2.36 

4.50

i

'

,

.37 ( 

.55 (

1.11 ( 

1.90 ( 

3.45 (

0.36

.52

.82

1.58 

2.40 

3.61

0.40 0.43

.59 .62 

.92 .98

1.68 1.83 

2.60 2.97 

3.90 5.21
TABLES 4-13 33

TABLE 5.—Particle-size distribution ofbedload sediment, conveyor-belt sampler—Continued

Date' _

Q'2 ___ i3 -

6-07-75

24.8 

0.2069

6-08-75

25.6 

0.1733

6-09-75

24.3 

0.0833

6-10-75

14.4 

0.0348

6-11-75

10.1 

0.0110

6-13-75

15.8 

0.0277

6-14-75

25.7 

0.0926

6-15-75

29.0 

0.1190

6-16-75

30.3 

0.1190

6-17-75

22.2 

0.0796

6-18-75

12.8 

0.0106

6-19-75

10.1 

0.0097

6-21-75

7.23 

0.0032

6-22-75

7.01

0.0047

Percent by weight finer than sieve size (mm) indicated

0.06 __ 0.2

.09 __ .3

.12 __ .4

.18 __ .5

.25 _ .9

.35 __ 2.3

.50 __ 8.1

.71 __ 22.9

1.00 __ 38.8

1.41 __ 54.8

2.00 _ 70.8

2.83 82.3

4.00 __ 90.4

5.66 __ 94.5

8.00 _ 97.1

11.3 __ 98.6

16.0 _ _ 99.6

22.6_ _100.0

32.0 _ __ __

45.0——— -__

64.0

0.2

.3

.5

.9

1.8

4.0

8.4

19.5

32.9

50.0

68.0

81.6

91.0

95.4

98.0

99.2

99.7

100.0

0.2 ( 4

.3 ('

.4 < 4

.6 ( 4

1.5 ( 4

4.7 ('

9.8 C

21.5 ( 4

36.0 ('

52.1 (<

68.2 ("

80.8 ( 4

89.6 ( 4

94.2 ( 4

97.3 ('

98.9 < 4

99.8 < 4

100.0 ( 4 < 4

_ - ( 4

,i

( 4

( 4

('

('

<j

( 4

('

( '

(-»

( 4

( 4

(j

(i

( 4

(

('

I '

('

,4

0.4

.5

.8

1.7

5.9

28.7

50.2

68.2

77.7

84.6

90.8

95.5

98.6

99.6

100.0

0.3

.4

.6

.9

2.0

5.7

14.4

27.8

40.8

54.3

68.0

79.6

88.3

93.6

96.8

99.1

99.7

100.0

0.2

.2

.4

.6

1.3

5.5

13.8

30.4

47.8

62.0

74.7

84.4

91.8

94.9

97.3

98.6

99.5

100.0

0.2

.3

.4

.7

1.4

5.1

14.0

28.2

43.9

56.2

69.3

80.5

89.7

94.2

97.1

98.5

99.3

100.0

0.2 ( 4

.2 ( 4

.2 ( 4

.3 ( 4

.9 ( 4

4.5 ( 4

11.8 ( 4

24.0 ( 4

36.9 ( 4

51.8 ( 4

68.4 ( 4

81.2 ( 4

90.7 ( 4

95.8 ( 4

98.2 ( 4

99.4 ( 4

100.0 ( 4

( 4

(*

( 4

( 4

0.2

.4

.6

1.2

3.5

16.6

30.0

48.9

63.1

76.4

87.4

93.8

97.3

98.9

99.6

100.0

0.6

.9

1.6

2.9

7.0

20.6

35.0

50.2

63.8

74.7

83.7

90.5

95.4

97.3

99.0

100.0

0.5

.6

1.1

2.4

7.0

22.9

39.0

54.9

68.6

78.7

86.7

92.2

96.2

98.1

99.0

99.5

100.0

Particle size (mm) at given percent finer

d, ______

dTM ""IIII

dm ______

d

Date 1 _

_ __ _ 0.43

_______ .62

____ .93 

, ___ 1.28

_______ 1.75

— ____ 3.02

_______ 5.97

6-23-75 

8.24 

0.0062

0.39 

.64 

1.05 

1.41 

1.88 

3.06 

5.43

6-24-75 

10.8 

0.0194

036 (' 

.61 ( 4 

.78 ( 4 

1.35 (' 

1.86 (' 

3.17 ( 4 

6.07 ( 4

( 4 ) 0.24 

( 4 ) .30 

(') .39 

t 4 ) .50 

( 4 I .66 

( 4 i 1.38 

( 4 i 2.70

6-25-75 6-26-75 7-01-75 7-08-75 

21.7 13.1 23.1 21.5 

0.0838 0.0396 0.2159 0.0317

0.34 0.34 

.52 .53 

.86 .78 

1.27 1.05 

1.85 1.53 

3.29 2.80 

6.44 5.72

5-18-76 5-19-76 

9.87 14.8 

0.0838 0.1359

0.35 

.53 

.83 

1.19 

1.78 

3.19 

6.12

5-20-76 

18.9 

0.1163

0.37 

.57 

.95 

1.36 

1.86 

3.10 

5.27

5-20-76 

19.6 

0.1295

( 4

/4

( 4 

f

0.27 

.35 

.55 

.73 

1.05 

1.78 

3.11

5-21-76 5-22-76 

22.4 17.5 

0.1769 0.0754

0.22 

.32 

.50 

.70 

1.04 

2.04 

3.85

5-26-76 

9.77 

0.0130

0.22 

.31 

.46 

.64 

.91 

1.77 

3.53

5-27-76 

14.3 

0.0232

Percent by weight finer than sieve size (mm) indicated

0.06 _ 0.4

.09_- .7

.12___ 1.0

.18__ 1.7

.25 __ 4.1

.35___ 15.5

.50— 29.8

.71___ 45.7

1.00___ 61.9

1.41 ___ 75.0

2.00 _ 85.1

2.83 ___ 92.1

4.00 _ 96.6

5.66 __ 98.5

8.00 ___ 99.3

11.3 ___ 99.8

16.0 __ 100.0

22.6 _______

32.0 ________

45.0 _______

64.0 ____ __

0.6

.7

1.0

1.5

3.2

12.7

24.2

36.4

50.7

64.1

77.6

88.1

94.9

98.2

99.8

100.0

0.4

.4

.4

.7

1.5

5.9

17.8

33.5

46.5

58.7

70.6

80.7

89.0

93.5

96.9

98.7

99.8

100.0

0.4

.5

.7

1.1

1.8

5.5

15.6

32.1

49.4

66.9

82.5

92.4

97.6

99.1

99.7

100.0

0.2

.3

.5

.8

1.7

6.2

11.7

20.3

30.7

43.6

59.1

73.2

85.4

92.3

96.5

98.3

99.0

99.2

100.0

0.2

.3

.5

.8

2.2

10.3

24.1

40.2

53.5

66.6

76.7

84.6

91.0

94.2

96.5

97.9

98.6

99.2

100.0

0.5

.7

.9

1.3

2.2

7.8

22.0

38.0

50.7

64.4

78.3

88.3

94.2

97.3

98.7

98.7

99.5

100.0

Particle size (mm) at given

d5 _ ___ ___ 0.26

d, b _ ---— .36

d,, _ __ __ .56

d,,, - _ ——— .77

d«, _ _—— _ 1.08

d K4 ________ 1.92

do, __________ 3.44

0.28 

.39

.68

.98

1.44

2.44

4.03

0.34 

.48

.74

1.10

1.69

3.22

6.43

0.34 

.50

.75

99

1.36

2 09

3.24

0.33 

60

1.13

1.63

9 i.OU^n

3.83

689

0.30 

'.64 42

91

1 35

2'. 76

6 5>8

0.31 

.44

.67

."OQO 

1 43

2 40

4 9.3

0.3 0.3

.5 .4

.7 .5

1.0 .9

1.8 1.7

5.7 5.8

18.3 18.5

34.9 37.1

48.3 51.9

62.3 66.9

75.9 80.2

86.1 88.8

92.4 93.7

96.4 96.5

98.5 98.0

99.0 98.6

99 0 99 2

99.4 99.9

100.0 100.0

percent finer

0.34 0.34 

.48 .47

.71 .68

1.04 .96

1.51 1.35

2.61 2.31

4 89 4 60

0.3

.4

.6

.9

1.6

4.9

15.3

33.4

48.3

63.0

76.6

86.3

91.8

95.2

97.1

97.9

98 1

98^4

99 9

100.0

0.36 

.51

73

L04

1.48

2 59

5 53

0.3

.3

.4

.7

1.1

3.8

11.1

22.9

33.9

46.8

61.5

73.8

82.0

87.6

90.3

94.3

Qfi yo.oft 

97.5

100.0

0.38

CO .oy

1.03

1 52

2 20

4 51

12 23

1.4

1.5

1.6

1.9

2.6

5.8

12.5

22.9

33.2

45.8

60.4

73.9

84.6

92.6

97.0

98.8

99 4

lOO'.O

0.33 

.57

1.05

1.56

2 24

3^93

6.63

0.3 0.5

.4 .7

.6 .9

.9 1.7

2.6 4.7

12.0 19.8

31.6 42.0

50.1 58.3

61.0 67.4

70.9 75.3

80.9 82.9

88.7 89.2

94.1 94.0

97.3 97.8

97.3 99.4

98.6 100.0

100.0

0.29 0.25 

.39 .33

.53 .45

.71 .59

1.14 .91

2.28 2.12

4.31 4.27
34 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

TABLE 5.—Particle-size distribution ofbedload sediment, conveyor-belt sampler—Continued

Date' -- Q' 2 — - 

Jb 3 ——— -

5-27-76 

13.7 

0.0301

5-27-76 

13.0 

0.0233

5-28-76 

18.8 

0.0437

5-28-76 

19.8 

0.0454

5-29-76 5-29-76 5-30-76 5-31-76 5-31-76 

20.5 20.9 20.9 16.6 15.8 

0.0712 0.0618 0.0774 0.0621 0.0405

6-01-76 

14.3 

0.0361

6-01-76 

13.9 

0.0325

6-02-76 

17.9 

0.0576

6-02-76 

17.8 

0.0463

6-03-76 

21.6 

0.0834

Percent by weight finer than sieve size (mm) indicated

0.06--

.09 — 

.12 —

.18 —

.25 —

.35 —

.50 — 

.71 —

1.00 — 

1.41 —

2.00 —

2.83 — 

4.00 —

5.66 —

113 —

16.0 — 

22.6 —

45.0 —

64.0 —

d, --- 

d,B -----

d-M ——

d

d^ --- 

dM --- 

dai ---

Date 1 — Q'2 ....

_--- 0.4

-_-- .5

-_— .7

__ - 1.4

_-___ 4.4

-_-_- 19.5

-_--_ 40.8 

-__-_ 56.3

___-- 65.8 

----- 74.5

----_ 83.0

____- 89.6 

__ -_ 94.3

_-__- 97.2 

_-__- 98.7

-- _ 99.2

_-__- 99.6 

-----100.0

----- 0.26

._ _ _ _ .33

— _ - _- .39

— ——— .61

— —— _ .97 

- --- 2.11 

.__-_____ 4.27

6-04-76 

21.8 

0.0871

0.3 

.5 

.5 

1.0 

3.3 

13.2 

30.7 

47.5 

58.4 

68.7 

78.8 

87.2 

92.8 

96.8 

98.6 

100.0

0.3 

.4 

.6 

1.2 

3.5 

13.6 

29.0 

42.5 

51.4 

60.2 

69.8 

78.2 

85.8 

91.6 

95.8 

97.3 

97.8 

100.0

_--__-

0.27 0.27 

.39 .38 

.55 .59 

.77 .95 

1.24 1.67 

2.46 3.68 

4.71 7.35

6-05-76 

21.4 

0.0918

6-05-76 

22.4 

0.0784

0.3 

.4 

.6 

1.0 

2.3 

8.5 

20.3 

34.7 

46.3 

58.5 

71.2 

81.6 

89.6 

94.8 

97.9 

98.8 

100.0

0.30 

.45 

.71 

1.11 

1.68 

3.11 

5.74

6-06-76 

22.6 

0.0908

0.6 0.3 0.2 

.7 .4 .3 

.9 .5 .4 

2.2 .9 .6 

2.8 1.8 1.3 

8.1 6.1 5.6 

19.1 14.6 16.5 

32.3 24.8 30.1 

42.2 33.7 41.3 

52.6 43.9 53.1 

64.3 56.6 65.9 

75.5 70.1 77.5 

85.1 81.7 86.8 

92.2 90.3 93.5 

96.2 94.3 97.5 

98.0 95.8 98.8 

99.1 96.9 99.7 

99.7 98.2 100.0 

100.0 100.0 _-_--

Particle size (mm) at given

0.30 0.33 0.34 

.46 .53 .49 

.78 1.05 .83 

1.30 1.67 1.29 

2.04 2.47 1.95 

3.84 4.35 3.58 

7.07 9.38 6.24

0.2 0.2 

.3 .3 

.4 .4 

.9 .6 

7.6 6.0 

21.1 19.0 

36.7 36.5 

47.5 49.3 

58.0 61.6 

68.8 73.5 

78.2 83.1 

86.1 90.4 

92.4 95.6 

96.4 98.4 

98.2 99.1 

99.1 100.0 

99.5 -_-_- 

99.8 ______

percent finer

0.32 0.34 

.45 .47 

.68 .69 

1.09 .98 

1.76 1.55 

3.64 2.95 

6.91 5.37

6-07-76 6-08-76 6-09-76 6-09-76 6-10-76 

24.6 21.1 18.8 18.9 18.2 

0.0869 0.0570 0.0513 0.0346 0.0290

0.2 

.3 

.6 

1.1 

11.7 

27.3 

45.3 

57.0 

67.5 

77.5 

85.6 

91.8 

95.5 

97.9 

98.9 

99.6 

100.0

0.28 

.40 

.58 

.81 

1.30 

2.63 

5.37

6-11-76 

13.8 

0.0253

0.2 

.3 

.5 

.8 

10.0 

25.5 

45.1 

58.2 

69.3 

79.2 

87.3 

93.0 

96.6 

98.8 

99.7 

100.0

0.30 

.41 

.60 

.80 

1.23 

2.44 

4.73

6-11-76 

14.5 

0.0289

0.2 

.3 

.4 

.8 

9.6 

23.4 

40.4 

52.3 

63.1 

74.0 

83.4 

91.3 

96.1 

98.9 

99.5 

100.0

0.30 

.42 

.64 

.94 

1.50 

2.90 

5.11

6-11-76

15.7 

0.0280

0.2 

.3 

.4 

.6 

6.4 

18.2 

36.1 

48.8 

59.8 

69.6 

78.5 

86.3 

91.5 

95.2 

96.5 

98.3 

99.8 

100.0

0.33 

.48 

.69 

1.04 

1.69 

3.59 

7.81

6-11-76 

15.2 

0.0629

1.0 

1.1 

1.2 

1.5 

8.2 

19.4 

33.6 

44.6 

55.9 

67.5 

76.9 

83.9 

89.1 

92.9 

95.1 

95.9 

95.9 

97.2 

100.0

0.30 

.46 

.74 

1.18 

1.85 

4.06 

11.03

6-11-76 

14.4 

0.0236

Percent by weight finer than sieve size (mm) indicated

0.06 — 

.09 — 

.12—_ 

.18 -- 

.25 — 

.35 — 

.50 — 

.71 — 

1.00 — 

1.41 — 

2.00___ 

2.83 — 

4.00 — 

5.66 — 

8.00 — 

11.3 — 

16.0 -- 

22.6 — 

32.0 — 

45.0 - 

64.0 _.

_- 0.2 

- .3 

.6 

.8 

__ 14 

-- 5.4 

-_ 14 1 

-- 27.5 

- 38.9 

- 50.3 

_- 61.3 

-_ 70.3 

_ 77.6 

-_ 87.1 

_- 93.4 

_- 96.5 

-- 98.2 

-_ 99.0 

-- 995 

--100.0

0.2 

.2 

.4 

.6 

1.2 

46 

12.3 

23.3 

33.1 

43.2 

53.9 

64.2 

73.8 

83.2 

92.0 

97.3 

99.4 

100.0

0.2 

.2 

.3 

.5 

1.1 

4.4 

13.7 

25.8 

36.4 

47.8 

59.5 

69.4 

77.9 

86.0 

92.4 

96.1 

99.0 

100.0

0.2 

.2 

.3 

.6 

1.2 

5.3 

16.9 

30.1 

40.9 

52.8 

65.1 

75.3 

83.0 

89.6 

94.6 

97.5 

98.9 

99.2 

99.5 

100.0

0.2 0.2 0.3 

.3 .3 .4 

.4 .4 .5 

.7 .6 .8 

1.3 1.2 1.8 

5.9 4.9 7.5 

18.6 14.9 19.9 

33.3 29.7 36.3 

42.6 42.1 48.8 

51.2 55.0 61.0 

60.3 68.0 73.2 

69.3 78.6 83.6 

77.8 87.1 90.8 

85.3 92.4 96.1 

92.0 95.6 98.8 

96.5 97.6 99.7 

98.6 99.9 100.0 

100.0 100.0 ---_-_

0.2 0.2 

.3 .3 

.5 .4 

.7 .7 

1.6 1.6 

6.7 7.5 

17.5 19.0 

33.5 35.3 

47.0 47.8 

60.3 59.9 

72.5 72.0 

82.2 82.3 

89.2 90.0 

94.2 95.0 

97.1 98.1 

98.2 99.0 

100.0 99.6 

-_-___ 100.0

0.3 

.4 

.6 

.8 

1.7 

7 1 

21.3 

42.5 

57.7 

70.5 

812 

88.8 

93.8 

97.3 

98.9 

100.0

0.3 

.4 

.5 

.7 

1.7 

6.8 

17.6 

34.2 

48.1 

61.6 

75.0 

86.6 

84.4 

98.5 

99.8 

100.0

0.3 

.4 

.5 

.8 

1.7 

6.7 

17.6 

34.9 

49.1 

62.3 

75.0 

85.4 

92.1 

96.8 

99.3 

100.0

0.2 

.3 

.4 

.7 

2.0 

9.3 

22.1 

37.0 

47.8 

58.5 

71.7 

81.6 

89.8 

95.4 

98.2 

99.3 

100.0

0.3 

.5 

.7 

1.1 

2.5 

10.6 

26.5 

45.5 

59.2 

71.0 

81.5 

89.3 

94.6 

98.2 

99.4 

100.0

Particle size (mm) at given percent finer

rf, -_—

rf,B 

rf-H -----

dv , - — - 

<4 - --

rf«4 ——— -

rf,., __—

___ 0.34 

— .53 

__- .89

_- 1.40 

— - 2.30 

_-_ 5.01 

- 9.33

0.36 

.57 

1.07 

1.76 

2.91 

5.83 

9.35

0.37 

.54 

.96 

1.51 

2.41 

5.18 

9.97

0.35 

.49 

.83 

1.30 

1.99 

4.22 

8.31

0.34 0.36 0.32 

.47 .51 .46 

.75 .82 .69 

1.35 1.24 1.03 

239 1.84 1.58 

5.33 3.50 2.89 

983 7.42 5.16

0.33 0.32 

.48 .46 

.74 .70 

1.08 1.06 

1.61 1.63 

3.08 3.03 

6.08 5.65

0.32 

.45 

.63 

.84 

1.21 

2.25 

4.40

0.33 

.48 

.72 

1.05 

1.54 

2.59 

4.14

0.33 

.48 

.71 

1.02 

1.51 

2.69 

4.81

0.30 

.43 

.68 

1.07 

1.67 

3.10 

5.49

0.29 

.41 

.59 

.79 

1.18 

2.22 

4.10
TABLES 4-13 

TABLE 5.—Particle-size distribution of bedload sediment, conveyor-belt sampler—Continued

35

Date1 __ 6-12-76 

Q' 2 --- 13.1

6-12-76 

12.5 

0.0169

6-12-76 

11.2 

0.0162

6-12-76 

10.5 

0.0145

6-12-76 

9.64 

00106

6-12-76 

8.50 

0.0084

6-13-76 6-14-76 

6.53 4.97 

0.0028 0.0022

Percent by weight finer than

006 __- - 0.3 

.09____-__ .5

.12— — - .6 

.18 _______ 1.0 

.25 _______ 2.4 

.35—-— 9.8 

.50 ______ 25.3 

71 44.7

1.00- _____ 58.6

1.41 __ _ __ 70.2

2.00 — _- 80.3

2.83_ __- 87.9 

4.00- — 93.7 

5.66 _-—— 97.8

O r\r\ QQ K.

11.3 ______ 100.0

16.0 _ _ ________ 

22.6 — — _—— . oo n

d, _ __ _ 0.30

d, h - _ __ .42

d t, -___— .60

d,,, _- _-_ .81

d« __--__ 1.21

dM . — -__ 2.35

d,, — _ 4.34

0.4 

.5 

.7 

1.1 

2.6 

11.1 

27.5 

46.9 

60.2 

71.6 

81.7 

89.8 

94.9 

97.6 

99.0 

99.3 

100.0

0.29 

.40 

.58 

.77 

1.15 

2.19 

4.02

0.2 

.3 

.4 

.8 

2.1 

9.5 

24.2 

44.3 

59.4 

72.6 

83.6 

91.2 

95.8 

98.4 

99.4 

100.0

0.30 

.42 

.61 

.81 

1.15 

2.04 

3.71

0.2 

.3 

.5 

.9 

2.4 

10.0 

24.8 

43.7 

58.9 

72.1 

83.3 

91.2 

96.7 

98.7 

100.0

0.30 

.42 

.61 

.82 

1.17 

2.06 

3.48

0.3 

.4 

.6 

.9 

2.3 

8.9 

22.9 

43.0 

58.8 

72.2 

82.7 

89.5 

94.5 

97.6 

97.6 

98.5 

100.0

0.30 

.43 

.62 

.82 

1.17 

2.13 

4.17

0.2 

.3 

.6 

1.1 

2.7 

10.3 

26.0 

46.4 

61.8 

74.9 

85.4 

92.8 

97.0 

99.3 

99.8

100.0

Particle

0.29 

.41 

.59 

.77 

1.08 

1.90 

3.30

°-8 2.3 1.2 o 7

1 - 8 59

in.! 1°'3

28'2 20' 7 

28-2 41.2 

01. z g2 2

72.0 1717 Q 83.4 n-s

90.8 fgl 

95.4 San 

97.9 HI 

99.3 ^

100.0 |1'|

. _ __ 100.0

6-14-76 

4.65 

0.0020

5-15-76 6-15-76 

3.87 3.44 

0.0003 0.0004

6-16-76

4.97 

0.0009

6-18-76 

3.90 

0.0006

6-19-76 

4.20 

0.0009

6-20-76 6-21-76 

4.57 9.53 

0.0023 0.0181

sieve size (mm) indicated

1.7 

2.7 

4.6 

7.8 

14.2 

28.6 

46.9 

63.7 

72.5 

78.5 

83.3 

87.4 

91.3 

95.0 

97.9 

99.2 

100.0

0.4 

.6 

1.2 

2.7 

7.2 

20.1 

37.5 

53.5 

63.0 

70.6 

76.9 

81.6 

85.2 

87.8 

91.1 

94.3 

98.2 

100.0

0.2 

.4 

.8 

1.8 

5.1 

14.7 

29.6 

44.1 

53.5 

61.1 

68.6 

74.8 

80.3 

85.5 

90.4 

94.3 

96.2 

100.0

0.4 

.7 

1.2 

3.5 

8.7 

26.4 

50.3 

70.0 

80.6 

87.3 

91.3 

93.0 

94.0 

94.9 

96.3 

96.6 

100.0

1.0 

1.5 

2.4 

5.4 

13.5 

37.8 

61.9 

77.7 

85.0 

89.7 

92.4 

93.6 

94.3 

94.8 

95.6 

96.5 

98.2 

100.0

0.5 

.8 

1.3 

3.8 

10.5 

34.3 

60.4 

75.2 

81.4 

85.4 

88.0 

89.3 

90.1 

90.6 

91.9 

93.4 

100.0

0.6 0.3 

.8 .5 

1.3 .7 

4.6 1.9 

10.9 3.6 

35.9 17.4 

62.1 37.7 

77.0 51.4 

84.1 60.0 

89.2 68.6 

92.8 77.6 

94.8 85.2 

95.3 91.1 

95.6 95.7 

96.9 98.5 

98.0 99.3 

98.7 100.0 

100.0 ______

size (mm) at given percent finer

0.19 0.11 

.28 .22 

.39 .32 

.49 .41 

.63 .53 

1.03 .94 

1.92 2.77

0.13 

.26 

.40 

.53 

.74 

2.14 

5.65

0.22 

.32 

.48 

.66 

1.09 

3.58 

11.78

0.25 

.37 

.57 

.88 

1.69 

5.13 

12.65

0.20 

.30 

.40 

.50 

.64 

1.19 

5.83

0.17 

.26 

.34 

.42 

.53 

.96 

6.18

0.19 

.28 

.36 

.44 

.55 

1.26 

11.67

0.18 0.27 

.27 .35 

.35 .48 

.43 .68 

.53 1.22 

1.00 2.68 

3.14 5.31

'Dates correspond to dates listed in table 4.

"Discharge over 14.6-m width of bedload trap; includes all flow over the active width of the streambed. 

'Unit transport rate of solids in dry weight per second, over 14.6-m width of bedload trap. 

^Indicates sieve analysis not available.
36 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER 

TABLE 6.—Summary data of river hydraulics and bedload transport, Helley-Smith sampler

River discharge

Date 1

6-01-73 ———

6-02-73 ----

6-03-73— -

6-06-73 _ _ _

6-07-73

6-08-73 --_ _

6-09-73 —

6-09-73 ———

5-24-74 ____

5-25-74 ——

5-26-74———.

5-26-74_ ____

5-27-74 ———

5-28-74 ———

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 __ __.

5-25-75 _ __ _

5-25-75 —— .

5-26-75 ---_

5-26-75 -__

5-27-75

5-27-75 ____.

6-01-75 _ ___

6-01-75 ——

6-02-75 --_.

6-02-75

6-03-75 __ __ . 6-04-75— —

6-05-75 ———

6-05-75 ---_.

6-06-75 ———

6-06-75 —-

6-07-75 —--

6-07-75 ----

6-07-75 _ __.

6-07-75 _ __ .

6-08-75 __ _.

6-08-75 -_ _ .

6-09-75 _- _ .

6-09-75— —

6-10-75 _ __.

6-10-75---.

6-11-75 ———

6-11-75- — -.

6-12-75— —

6-12-75 ———

6-13-75--- -

6-13-75

6-17-75 _ __.

6-17-75— —

6-18-75— —

6-18-75---.

6-19-75 ___--

Total,2

Q

(rrvVsl

— ___ 16.6

_____ _ -18.5

—— ___ 18.0

____ _ 16.4

- ——— 19.7

--—28.3

__ — _ 27.6

__ —2.95

__ ______ 5.44

———— 10.8

- ——— 10.1

__ — __23.3

————29.7

__ __ _32.6

————45.3

————36.4

————25.1

———25.8

———27.5

————31.9

————30.0

————28.3

_____ _2.35

_____ — 2.35

— _——2.41

____——2.38

—————2.44

— _ __2.44

—————3.26

—————3.26

———— _5.38

___ _ __-5.35

—————9.06

_ _ — 10.1

———— 10.6

———— 10.5

_ _ —20.9

———26.9

———— 26.6

__ ——26.4

---___27.4

_ — -_27.5

„_ _ -27.1

_ _ —27.1

__ __ _17.0

—— — 16.7

- ——— 10.9

—— — 10.8

———— 10.7

„___ _ 10.6

—— — 16.7

____ _ 16.7

————24.5

———24.5

——— — 13.7

__ ——13.7

_____ 10.9

Effective,3 Q'

(nr'Vs)

15.8 

17.5 

17.0 

11.4 

15.6

18.6 

26.4 

25.8 

2.95 

5.34

10.4 

9.73 

21.9 

27.7 

30.3

41.8 

33.8 

23.5 

24.2 

25.7

29.7 

28.0 

26.4 

2.35 

2.35

2.41 

2.38 

2.44 

2.44 

3.25

3.25

5.28 

5.25

8.75 

9.73

10.2 

10.1 

19.7 

20.1 

25.2

25.3 

24.9 

24.7 

25.6

25.7

25.4 

25.4 

16.1 

15.9 

10.5

10.4 

10.3 

10.2 

15.9 

15.9

23.0 

23.0 

13.1 

13.1 

10.5

Mean depth,4 

D

(m)

1.02 

1.10 

1.08 

.81 

1.02

1.15 

1.47 

1.45 

.31

.48

.76 

.73 

1.29 

1.52 

1.62

2.03 

1.74 

1.35 

1.38 

1.44

1.60 

1.53 

1.47 

.27 

.27

.27 

.27 

.28 

.28 

.34

.34

.47 

.47 

.68 

.73

.75 

.75 

1.20 

1.21 

1.42

1.43 

1.41 

1.40 

1.44 

1.44

1.43 

1.43 

1.04 

1.03

.77

.76 

.76 

.75 

1.03 

1.03

1.33 

1.33 

.90 

.90

.77

Mean 

velocity,5 

V

(m/s)

1.06 

1.09 

1.08 

.96 

1.06

1.11 

1.23 

1.23 

.64

.77

.94 

.92 

1.17 

1.25 

1.29

1.42 

1.33 

1.19 

1.20 

1.23

1.28 

1.26 

1.23 

.60 

.60

.60 

.60 

.61 

.61 

.66

.66 

.76 

.76 

.89 

.92

.93 

.93 

1.13 

1.14 

1.22

1.22 

1.21 

1.21 

1.22 

1.23

1.22 

1.22 

1.07 

1.06 

.94

.94 

.93 

.93 

1.06 

1.06

1.19 

1.19 

1.00 

1.00 

.94

Unit 

bedloadtransport 

rate, 6

(kg/m-s)

0.0065 

.0277 

.0425 

.0074 

.0383

.0059 

.1106 

.1624 

.0015 

.0046

.0451 

.0583 

.1702 

.1532 

.2533

.3025 

.1227 

.0768 

.0200 

.0106

.0233 

.0307 

.0447 

.0061 

.0024

.0050 

.0075 

.0034 

.0062 

.0080

.0086 

.0649 

.0749 

.0093 

.0983

.0512 

.0829 

.1076 

.0860 

.1262

.0474 

.2168 

.1896 

.2027 

.1025

.1185 

.1054 

.0674 

.0298 

.0210

.0225 

.0112 

.0125 

.0337 

.0252

.0879 

.1052 

.0265 

.0195 

.0163

Bedload 

size, 7

(mm)

0.45 

.58 

.71 

.56 

.60

.42 

1.53 

1.13 

1.22 

.41

.50 

.65 

.98 

1.07 

1.15

1.14 

1.76 

1.14 

.68 

.40

.49 

.59

.70 

.82

.48

.74 

.57 

.70 

.49 

.49

.61 

.64

.87 

.78 

.99

1.06 

1.05 

.90 

.97 

.95

.68 

.93 

1.27 

1.24 

1.28

.82 

1.50 

1.11 

1.41 

1.15

1.02 

.49

.48 

.70 

.44

1.58 

1.38 

.57 

.59 

.70
TABLES 4-13 

TABLE 6.—Summary data of river hydraulics and bedload transport, Helley-Smith sampler—Continued

37

River discharge

Date1

6-19-75 

6-20-75 

6-20-75 

6-21-75 

6-21-75

6-22-75 

6-22-75 

6-23-75 

6-23-75 

6-24-75

6-24-75 

6-25-75 

6-25-75 

6-25-75 

6-25-75

6-26-75 

6-26-75 

6-26-75 

6-26-75 

5-28-76

5-28-76 

5-29-76 

5-29-76

Total,2

(MVs)

____________10.9

____________7.14

____________7.14

____________7.70

____________7.70

_________ _7.48

________ ___7.48

____________8.44

_ __ _ _ 8.44

______ ____11.3

_________ ___11.3

_____ ______21.5

_________ .21.7

_________ _23.3

__ ________23.3

__________ 15.9

____________15.7

____________11.8

______ ____11.6 

__ _________21.4

________ __21.1

___________ 22.4

________ ___22.4

Effective,3

(nrVs)

10.5 

6.95 

6.95

7.48 

7.48

7.27 

7.27 

8.17 

8.17 

10.9

10.9 

20.3 

20.4 

21.9 

21.9

15.1 

14.9 

11.3 

11.1 

20.1

19.9 

21.0 

21.0

depth,4

(m)

.77

.57 

.57 

.61 

.61

.59 

.59 

.64 

.64 

.79

.79 

1.22 

1.23 

1.29 

1.29

.99 

.98 

.81 

.80 

1.23

1.23 

1.27 

1.27

Mean 

velocity,5 

V

(mis)

.94 

.83 

.83 

.85 

.85

.84 

.84 

.87 

.87 

.95

.95 

1.14 

1.14 

1.17 

1.17

1.05 

1.04 

.96 

.95 

1.11

1.11 

1.13 

1.13

Unit 

Bedloadtransport 

rate,6

, A (kg/m-s)

.0114 

.0040 

.0045 

.0039 

.0051

.0075 

.0099 

.0096 

.0154 

.0254

.0183 

.0926 

.0814 

.0912 

.0725

.0684 

.0976 

.0513 

.0683 

.0390

.0822 

.1205 

.0977

Bedload size," 

dv, 

(mm)

.65 

.55 

.50 

.52 

.65

.81 

.56 

.92 

1.08 

.82

.78 

.88 

.99 

1.19 

1.56

.82 

.76 

1.04 

1.03 

.65

.64 

1.14 

.56

'Dates correspond to dates listed in table 7.

•"Complete river discharge including overbank flow.

•'Discharge over 14.6-m width of bedload trap; includes all flow over the active width of the 

streambed. Q. 

4Mean depth over effective width W\ D = ^

VW

'Mean velocity of effective discharge; V = ^ = "

WD 14.60

••Unit transport rate of solids in dry weight per second, over 14 6-m width of bedload trap. 

'£/,„ is median diameter of grains; complete grain-size data are given in table 7.
38 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER 

TABLE 7.—Particle size distribution of bedload sediment, Helley-Smith sampler

Date 1 Q" -

ij -—

— 6-01-73 

___ 15.8 

_ 0.0065

6-02-73 

17.5 

0.0277

6-03-73 

17.0 

0.0425

6-06-73 

11.4 

0.0074

6-07-73 6-08-73 6-09-73 6-09-73 

15.6 18.6 26.4 25.8 

0.0383 0.0059 0.1106 0.1624

5-24-74 

2.95 

0.0015

5-25-74 

5.34 

0.0046

5-26-74 

10.4 

0.0451

5-26-74 

9.73 

0.0583

5-27-74 

21.9 

0.1702

5-28-74 

27.7 

0.1532

Percent by weight finer than sieve size (mm) indicated

0.06 

.09 

.12 

.18 

.25 

.35 

.50 

.71 

1.00 

1.41 

2.00 

2.83 

4.00 

5.66 

8.00 

11.3 

16.0

320

A& fl

64.0-

_ __ 0.1 

_____ .4 

1.1 

____ 3.1 

_ _ _ 9.6 

_____ 30.7 

— __ 57.7 

— _ 71.6 

— — 77.9 

____ 83.0 

_____ 87.9 

— __ 92.2 

_____ 95.9 

_____ 98.2 

- _ _ 99.4 

99 4

_ __100.0

0.3 

.5 

.8 

1.8 

5.2 

17.5 

41.1 

62.7 

73.1 

81.3 

88.5 

93.8 

97.5 

98.8 

99.6 

99.8 

100.0

0.2 

.3 

.5 

1.1 

3.2 

10.3 

26.7 

50.1 

65.4 

77.3 

86.9 

93.2 

97.4 

99.1 

99.8 

100.0

0.1 

.3 

.6 

1.7 

7.5 

26.3 

44.4 

62.0 

70.6 

77.7 

84.1 

89.0 

92.7 

95.2 

97.6 

99.5 

100.0

0.3 0.4 0.1 0.1 

.4 .8 .1 .2 

.7 1.2 .2 .3 

1.5 2.4 .4 .6 

4.7 10.0 1.1 1.7 

16.4 35.7 3.1 4.6 

40.1 65.7 7.6 12.3 

58.3 82.6 17.4 31.7 

67.4 88.0 29.5 45.7 

76.6 91.3 45.2 57.9 

86.5 94.0 66.1 71.1 

94.1 96.1 83.2 82.4 

97.9 97.5 93.1 91.6 

99.3 98.6 96.8 96.2 

99.8 99.2 98.9 98.6 

100.0 100.0 99.7 99.5

0.1 

.2 

.7 

1.6 

6.9 

16.5 

27.1 

37.8 

46.2 

52.9 

61.1 

71.4 

78.4 

83.9 

87.0 

88.3 

100.0

0.5 

1.1 

2.2 

4.1 

15.7 

42.1 

60.7 

72.5 

80.9 

87.2 

92.2 

95.7 

97.5 

98.5 

99.4 

100.0

0.3 

.5 

.9 

1.7 

5.1 

19.3 

49.5 

69.4 

79.4 

87.2 

93.5 

96.9 

98.7 

99.5 

99.8 

100.0

0.0 

0.0 

.5 

1.0 

4.0 

12.9 

33.8 

53.9 

66.7 

77.6 

88.6 

94.7 

98.0 

99.3 

100.0

0.1 

.2 

.4 

.7 

1.6 

4.5 

14.4 

31.4 

51.2 

66.7 

80.3 

89.7 

95.2 

97.9 

99.2 

100.0

0.1 

.2 

.3 

.6 

1.9 

5.3 

14.7 

30.2 

46.9 

61.8 

74.9 

85.6 

95.1 

98.0 

99.1 

99.5 

99.8 

100.0

Particle size (mm) at given percent finer

d, - 

rf..

R.R.a.R.

d;* -

Date1 Q" _

ia —

— - 0.20 

_____ .29

_____ .38 

_____ .45 

.60 

_ ___ 1.52

_ __ 3.61

_ 5-28-74 

30.3 

_ 0.2533

0.25 

.34 

.46 

.58 

.76 

1.60 

3.09

5-29-74 

41.8 

0.3025

0.28 

.41 

.57 

.71 

.99 

1.79 

3.18

5-30-74 

33.8 

0.1227

0.23 

.30 

.42 

.56 

.80 

2.00 

5.47

5-31-74 

23.5 

0.0768

0.25 0.21 0.42 0.36 

.35 .28 .68 54 

.47 .35 1.14 .77 

.60 .42 1.53 1.13 

.91 .50 1.96 1.69 

1.82 .77 2.90 2.98 

3.00 2.32 4.66 5.05

6-01-74 6-02-74 6-03-74 6-04-74 

24.2 25.7 29.7 28.0 

0.0200 0.0106 0.0233 0.0307

0.23 

.35 

.65 

1.22 

2.27 

5.80 

12.3

6-05-74 

26.4 

0.0447

0.18 

.25 

.33 

.41 

.56 

1.18 

2.60

5-25-75 

2.35 

0.0061

0.25 

.33 

.43 

.50 

.65 

1.22 

2.26

5-25-74 

2.35 

0.0024

0.27 

.37 

.50 

.65 

.94 

1.65 

3.30

5-26-75 

2.41 

0.0050

0.36 

.52 

.76 

.98 

1.36 

2.26 

3.93

5-26-75 

2.38 

0.0075

0.35 

.52 

.79 

1.07 

1.53 

2.68 

3.98

5-27-75 

2.44 

0.0034

Percent by weight finer than sieve (mm) indicated

0.06 

.09 

.12 

.18 

.25 

.35 

.50 

.71 

1.00 

1.41 

2.00 

2.83 

4.00 

5.66 

8.00 

11.3 

16.0 

22.6 

32.0 

45.0 

64.0

_ __ 0.1 

_--__ .2 

_— - .3 

___ .5 

___ 1.3 

__ _ 4.0 

_____ 11.7 

_ __ 26.3 

_____ 43.1 

_____ 59.7 

_ __ 74.2 

_____ 84.8 

_____ 91.8

_____ 97.6 

_____ 98.6 

_____ 99.3

_ __ 100.0

__________

0.2 

.3 

.4 

.6 

1.3 

4.1 

11.8 

26.1 

44.5 

59.0 

71.7 

81.5 

88.5 

93.6 

96.8 

98.4 

99.3 

99.8 

100.0

0.1 

.1 

.2 

.4 

1.2 

2.9 

6.6 

14.3 

26.0 

40.6 

55.4 

69.2 

81.5 

89.6 

95.2 

98.0 

99.6 

100.0

0.1 

.2 

.3 

.6 

2.3 

8.6 

15.1 

25.9 

45.3 

58.0 

71.3 

82.1 

70.4 

94.9 

97.7 

99.0 

99.8 

100.0

0.2 0.3 0.3 0.2 

.5 .7 .6 .4 

1.0 1.3 1.1 .7 

1.7 2.2 1.8 1.6 

8.6 10.7 6.9 6.3 

30.0 41.1 29.2 21.5 

42.6 66.7 49.4 42.6 

49.4 72.3 62.7 59.0 

56.5 75.8 72.1 70.9 

63.9 79.3 78.4 78.3 

72.1 83.2 83.8 84.8 

79.6 87.1 88.1 89.8 

86.3 91.0 92.8 93.6 

90.9 94.1 94.9 96.0 

94.5 96.9 97.2 97.6 

96.7 98.6 98.5 98.7 

98.0 99.3 99.2 99.4 

99.4 100.0 99.4 99.7 

100.0 ___ 100.0 100.0

0.2 

.4 

.7 

1.1 

2.9 

11.3 

32.0 

51.0 

64.4 

75.2 

85.0 

91.6 

95.7 

97.6 

99.0 

99.5 

100.0

0.3 

.6 

.6 

.9 

3.0 

12.0 

28.7 

45.5 

56.0 

70.4 

87.1 

98.5 

99.7 

100.0

0.8 

8 

.8 

1.5 

4.6 

19.8 

54.2 

81.7 

92.4 

96.9 

99.2 

100.0

0.7 

.7 

1.1 

1.5 

3.6 

12.0 

28.8 

47.8 

64.6 

81.8 

94.5 

98.2 

99.3 

99.6 

100.0

0.5 

.7 

1.0 

1.2 

4.2 

15.2 

39.6 

66.3 

85.3 

94.6 

98.5 

99.5 

99.8 

100.0

0.5 

1.1 

1.1 

1.6 

3.8 

11.4 

27.7 

50.5 

72.8 

91.8 

98.9 

99.5 

100.0

Particle size (mm) at given percent finer

d- 038

rf lk _ __ .56 

dn ___- _ .85 

d,(l _ 1.15 

dm ___ 1.59 

dM __ 2.76 

rf,, _ _ 5.29

0.38 

.56 

.84 

1.14 

1.66 

3.18 

6.44

0.44 

.75 

1.25 

1.76 

2.53 

4.42 

7.86

0.30 

.51 

.84 

1.14 

1.69 

3.04 

5.71

0.22 0.21 0.23 0.23 

.29 .27 .30 .32 

.41 .33 .39 .45 

.68 .40 .49 .59 

1.48 .49 .77 .84 

3.54 2.16 2.05 1.92 

8.56 6.21 5.73 4.82

0.28 

.39 

.53 

.70 

1.02 

1.93 

3.72

0.28 

.39 

.57 

.82 

1.24 

1.85 

2.37

0.25 

.33 

.42 

.48 

.56 

.75 

1.19

0.27 

.39 

.56 

.74 

1.01 

1.48 

2.07

0.26 

.36 

.47 

.57 

.69 

.97 

1.45

0.27 

.40 

.56 

.70 

.88 

1.19 

1.56
TABLES 4=^ 13 39

TABLE 7.—Particle size distribution of bedload sediment, Helley-Smith sampler—Continued

Date1 

Q" -

_ 5-27-75 

2.44 

— 0.0062

6-01-75 

3.25 

0.0080

6-01-75 

3.25 

0.0086

6-02-75 

5.28 

0.0649

6-02-75 &-03-75 6-04-75 6-05-75 6-05-75 

5.25 8.76 9.73 10.2 10.1 

0.0749 0.0093 0.0983 0.0512 0.0829

6-06-75 

19.7 

0.1076

6-06-75 

20.1 

0.0860

6-07-75 

25.2 

0.1262

6-07-75 

25.3 

0.0474

6-07-75 

24.9 

0.2168

Percent by weight finer than sieve size (mm) indicated

0.06 

.09 

.12 

.18 

.25 

.35 

.50 

.71 

1.00 

1.41 

2.00 

2.83 

4.00 

5.66 

8.00 

11.3 

16.0 

22.6 

32.0 

45.0 

64.0

___ 0.6 

.9 

_____ 1.2 

--_-_ 1.5 

__ __ 4.1 

___ 19.4 

_____ 53.2 

83.8 

__ __ 95.0 

_____ 98.8 

_ __ 99.4 

___ 99.7 

-___100.0

0.7 

.9 

1.4 

2.7 

12.6 

31.1 

51.1 

69.4 

81.1 

89.3 

93.6 

96.1 

97.3 

97.7 

98.6 

99.3 

100.0

04 

.6 

.8 

1.7 

8.1 

20.2 

39.1 

58.4 

72.8 

80.9 

85.1 

87.0 

88.1 

89.0 

89.8 

90.9 

93.8 

100.0

0.4 

.5 

.7 

1.1 

3.9 

18.0 

36.7 

55.6 

68.7 

80.8 

90.8 

96.3 

98.6 

99.5 

99.8 

100.0

0.4 0.9 0.3 0.5 0.3 

.4 1.3 .3 .7 .4 

.6 1.7 .5 .9 .6 

1.0 2.7 .7 1.4 .9 

2.8 6.4 1.6 3.0 2.0 

12.1 16.5 4.7 7.9 5.5 

26.8 32.6 13.8 17.5 14.6 

42.4 46.6 32.0 33.1 31.7 

55.2 58.8 50.4 47.6 47.6 

69.1 70.6 65.0 63.0 63.3 

83.6 82.4 78.7 79.2 78.9 

92.9 91.7 89.2 90.6 89.9 

97.9 97.3 96.3 96.9 96.8 

99.1 98.5 98.8 99.0 99.0 

99.7 99.5 99.7 99.8 99.8 

100.0 99.5 100.0 100.0 100.0 

______ 100.0 ______ ______ ______

0.4 

.6 

.8 

13 

3.2 

9.0 

21.8 

39.9 

54.6 

67.5 

79.0 

87.8 

94.2 

97.1 

98.6 

99.4 

99.6 

100.0

0.5 

.7 

.9 

1.4 

3.8 

9.5 

21.5 

37.4 

51.1 

63.1 

75.0 

85.2 

92.8 

96.3 

98.4 

99.3 

100.0

0.5 

.5 

.7 

1.2 

3.5 

8.8 

21.1 

38.7 

52.2 

64.5 

76.0 

85.3 

92.7 

96.0 

98.0 

99.1 

99.5 

100.0

0.6 

.7 

1.1 

1.7 

5.3 

13.4 

29.6 

52.3 

70.4 

84.0 

92.9 

96.9 

98.7 

99.5 

100.0

0.3 

.3 

.5 

.7 

1.9 

4.7 

14.4 

34.8 

54.4 

69.8 

81.8 

89.4 

94.1 

96.5 

98.2 

99.2 

100.0

-- —

Particle size (mm) at given percent finer

ds 

d, 6

d.,, __

d*,-

d« - 

dM __ 

dm -

Date' 

Q' 2 __

_ ___ 0.26 

__ _ .33

-__- .42

______ .49

___— .56

______ .71 

1 nn

__ 6-07-75 

24.7 

- 0.1896

0.20 

.27 

.38 

.49 

.65 

1.12 

2.39

6-08-75 

25.6 

0.2027

0.22 

.32 

.47 

.61 

.82 

1.84 

16.4

6-08-75 

25.7 

0.1025

0.26 

.34 

.49 

.64 

.90 

1.56 

2.54

6-09-75 

25.4 

0 1185

0.28 0.23 0.36 0.30 0.34 

.39 .35 .53 .48 .52 

.60 .53 .75 .74 .76 

.87 .78 .99 1.06 1.05 

1.27 1.19 1.41 1.47 1.46 

2.03 2.11 2.35 2.27 2.31 

3.15 3.34 3.66 3.48 3.53

6-09-75 6-10-75 6-10-75 6-11-75 6-11-75 

25.4 16.1 15.9 10.5 10.4 

0.1054 0.0674 0.0298 0.0210 0.0225

0.29 

.44 

.65 

.90 

1.32 

2.41 

4.32

6-12-75 

10.3 

0.0112

0.28 

.43 

.67 

.97 

1.49 

2.71 

4.87

6-12-75 

10.2 

0.0125

0.28 

.44 

.66 

.95 

1.43 

2.69 

5.00

6-13-75 

15.9 

0.0337

0.25 

.38 

.55 

.68 

.90 

1.42 

2.33

6-13-75 

15.9 

0.0252

0.36 

.52 

.71 

.93 

1.26 

2.20 

4.48

6-17-75 

23.0 

0.0879

Percent by weight finer than sieve size (mm) indicated

0.06 

.09 

.12 

.18 

.25 

35 

.50 

.71 

1.00 

1.41 

2.00 

2.83 

4.00 

5.66 

8.00 

11.3 

16.0 

22.6 

32.0 

45.0 

64.0

_ ___ 0.3 

_ __ .3 

.5 

.7 

_____ 1.6 

3.3 

_ ___ 8.8 

_____ 22.7 

__ _ 39.1 

_____ 55.2 

_____ 71.0 

_____ 83.4 

_____ 91.8 

_____ 96.0 

___ _ 98.2 

_ __ 99.4 

__ -100.0

0.2 

.4 

.5 

.7 

2.0 

4.9 

9.9 

22.7 

39.1 

56.8 

73.8 

85.8 

93.3 

97.1 

98.9 

99.7 

100.0

0.5 

.6 

.8 

1.1 

3.3 

7.9 

14.1 

25.3 

37.9 

54.9 

72.4 

82.7 

91.0 

94.8 

98.0 

99.6 

99.8 

100.0

0.4 

.5 

.8 

1.1 

3.5 

13.9 

25.6 

43.5 

58.7 

71.2 

81.4 

88.9 

94.4 

97.2 

99.2 

100.0

______

0.3 0.4 0.4 0.7 0.5 

.3 .5 .5 .9 .7 

.5 .7 .7 1.1 1.0 

.6 1.0 1.0 1.6 1.4 

2.8 2.5 3.9 5.3 5.1 

9.9 7.7 10.4 16.1 15.9 

16.4 15.0 15.7 24.0 25.0 

24.1 27.2 23.6 34.2 35.6 

34.0 44.1 34.3 45.1 49.0 

47.2 63.1 50.2 57.6 64.0 

62.9 80.1 69.8 71.4 79.2 

76.9 91.5 85.1 828 90.2 

89.0 97.2 94.3 91.8 96.8 

94.2 99.1 983 96.7 98.8 

97.6 99.8 99.8 99.0 99.7 

99.2 100.0 100.0 99.6 99.8 

100.0 ___ _ ______ 100.0 100.0

1.0 

1.3 

1.6 

2.3 

10.5 

35.5 

49.5 

61.1 

68.3 

74.7 

80.7 

87.4 

93.8 

97.9 

99.5 

100.0

0.9 

1.2 

1.5 

2.2 

9.5 

34.9 

52.0 

69.1 

83.4 

90.9 

94.6 

96.5 

98.1 

99.1 

100.0

0.6 

.8 

1.1 

1.8 

7.2 

24.8 

37.4 

49.7 

59.8 

70.0 

80.8 

89.7 

95.6 

98.4 

99.5 

10.0

0.8 

1.1 

1.5 

2.3 

9.4 

37.9 

58.3 

70.0 

75.9 

80.6 

84.8 

88.6 

92.0 

96.4 

99.7 

100.0

0.3 

.4 

.5 

.7 

1.8 

6.2 

10.7 

18.1 

27.9 

43.3 

63.8 

80.0 

90.6 

96.0 

98.8 

99.8 

100.0

Particle size (mm) at given percent finer

d, 

d, 6 - 

d,,

dw -

d«, 

dM 

d,,

_ ._ 0.41

_____ .61 

_____ .92

- _ 1.27

- __ 1.74 

_ ___ 2.90 

_____ 5.11

0.36 

.60 

.92 

1.24 

1.66 

2.67 

4.55

0.29 

.53 

.93 

1.28 

1.71 

2.97 

5.75

0.27 

.38 

.60 

.82 

1.18 

2.24 

4.25

0.29 0.31 0.27 0.25 0.25 

.49 .52 .50 .35 .35 

1.03 .84 1.02 .73 .69 

1.50 1.11 1.41 1.15 1.02 

2.10 1.46 1.83 1.69 1.44 

3.41 2.21 2.75 2.95 2.29 

6.02 3.37 4.17 4.87 3.52

0.21 

.28 

.35 

.49 

.85 

2.36 

4.31

0.21 

.28 

.35 

.48 

.65 

1.03 

2.13

0.23 

.31 

.47 

.70 

1.19 

2.24 

3.81

0.21 

.28 

.34 

.44 

.61 

1.89 

4.94

0.23 

.64 

1.18 

1.58 

2.05 

3.17 

5.20
40 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER 

TABLE 7.—Particle size distribution of bedload sediment, Helley-Smith sampler—Continued

Date 1 -_ Q'2 ——

6-17-75 

23.0 

0.1052

6-18-75 

13.1 

0.0265

6-18-75 

13.1 

0.0195

6-19-75 

10.5 

0.0163

6-19-75 6-20-75 6-20-75 6-21-75 6-21-75 6-22-75 6-22-75 6-23-75 6-23-75 6-24-75 

10.5 6.95 6.95 7.48 7.48 7.27 7.27 8.17 8.17 10.9 

0.0114 0.0040 0.0045 0.0039 0.0051 0.0075 0.0099 0.0096 0.0154 0.0254

Percent by weight finer than sieve

0.06 — 

.09 — - 

.12 — . 

.18 —— 

.25 —— 

.35 —— 

.50 -_- 

.71 —— 

1.00 —— 

1.41 —— 

2.00 —— 

2.83 

4.00- 

5.66 —— 

8.00--- 

11.3 —— 

16.0 __-_ 

22.6—- 

32.0 _ -

5.0 ——

64.0 —— .

_ 0.4 

.5 

.6 

.9 

- 2.2 

_ 8.4 

- 17.3 

- 29.2 

- 39.1 

- 50.8 

- 65.5 

_ 78.7 

_ 89.1 

. 95.1 

_ 98.1 

_ 99.3 

._ 100.0

0.5 

.7 

.8 

1.2 

4.2 

22.2 

42.4 

61.5 

78.5 

88.9 

94.2 

96.7 

98.4 

99.1 

99.3 

99.7 

100.0

0.7 

.8 

1.0 

1.5 

4.9 

24.4 

42.3 

58.8 

74.3 

86.1 

93.5 

97.1 

99.0 

99.5 

100.0

0.4 

.7 

.8 

1.2 

4.8 

19.7 

33.1 

50.7 

67.4 

81.2 

90.2 

94.4 

96.9 

98.3 

99.6 

100.0

0.3 0.5 0.4 

.6 .5 .4 

.8 .9 .8 

1.1 1.4 1.2 

5.8 9.0 7.8 

23.8 30.8 29.4 

39.1 47.1 49.8 

53.7 58.4 67.3 

65.8 68.3 77.1 

78.3 74.7 84.5 

89.1 80.1 90.2 

95.0 84.6 93.9 

97.8 89.6 96.3 

99.0 92.8 97.6 

100.0 97.3 100.0 

_--___ 98.6 - _ -

size (mm) indicated

0.9 0.7 0.5 

.9 .7 .5 

1.4 1.1 .7 

2.3 1.8 1.2 

11.1 11.5 5.8 

33.3 30.9 20.8 

48.6 43.5 34.6 

60.6 52.2 46.0 

68.5 59.4 56.7 

74.5 66.5 70.7 

80.1 74.1 86.4 

85.2 82.4 95.4 

89.4 89.2 98.8 

92.6 93.2 99.5 

97.7 97.5 100.0 

100.0 100.0 ___

0.4 

.4 

.7 

.9 

6.5 

27.1 

45.9 

59.2 

68.5 

76.0 

83.9 

92.3 

96.1 

98.2 

99.4 

100.0

0.6 

.8 

1.0 

1.5 

6.1 

21.0 

32.1 

42.2 

52.7 

64.7 

77.1 

87.0 

92.4 

94.8 

97.5 

98.7 

100.0

0.4 

.5 

.7 

1.1 

4.5 

16.5 

26.9 

35.8 

47.0 

61.0 

76.2 

88.2 

95.5 

99.1 

100.0

0.4 

.6 

.8 

1.2 

4.0 

17.0 

33.5 

46.2 

55.1 

65.1 

77.7 

88.8 

95.4 

98.8 

99.8 

100.0

Particle size (mm) at given percent finer

d, ——— 

rf.B

rf,,

dw -- — 

dm — —

dM _ -

rf« ———

Date 1 __

£.::::

_-- 0.31

__ .48

__ .87 

1.38 

— 1.98 

-. 3.33

-- 5.61

6-24-75 

10.9 

0.0183

0.26 

.33 

.45 

.57 

.75 

1.18 

2.20

6-25-75 

20.3 

0.0926

0.25 

.32 

.44 

.59 

.81 

1.32 

2.25

6-25-75 

20.4 

0.0814

0.25 

.33 

.52 

.70 

.95 

1.56 

3.03

6-25-75 

21.9 

0.0912

0.24 0.22 0.23 

.31 .29 .30 

.46 .39 .39 

.65 .55 .50 

.98 .89 .67 

1.67 2.72 1.39 

2.83 6.49 3.26

6-25-75 6-26-75 6-26-75 

21.9 15.1 14.9 

0.0725 0.0684 0.0976

Percent by weight finer than sieve

0.06- 

.09- 

.12- 

.18- 

.25- 

.35- 

.50- 

.71- 

1.00 — 

1.41- 

2.00- 

2.83- 

4.00- 

5.66- 

8.00- 

11.3 ._

22.6 _-

32.0 ___

45.0 -__ 

64.0 —

d,

d, K 

d,, - -

dv> - —

d«. - — 

d»4 ----- 

dm - —

0.5 

7 

.9 

_- 1.4 

4.9 

— 18.5 

_ _ 34.7 

— 47.3 

— 57.5 

— 67.0 

_ - 78.3 

-_. 89.6 

— 96.0 

.--, 98.4 

_ _ 99.5 

— 100.0

--- .34 

— .50 

__- .78

—— 1.31 

--- 2.34 

—— 3.71

0.4 

.4 

.6 

1.0 

3.1 

12.3 

28.8 

43.6 

53.8 

64.5 

77.0 

87.0 

93.7 

97.3 

99.1 

99.7 

100.0

0.28 

.39 

.58 

.88 

1.43 

2.53 

4.42

0.3 

.4 

.6 

1.0 

3.0 

11.4 

26.2 

40.2 

50.4 

61.1 

71.9 

80.3 

88.5 

91.6 

97.3 

99.4 

100.0

0.28 

.40 

.63 

.99 

1.60 

3.28 

6.69

0.4 

.5 

.7 

1.1 

3.2 

9.3 

19.1 

31.1 

43.0 

56.9 

71.6 

82.0 

89.3 

93.7 

96.5 

97.8 

98.8 

98.8 

98.8 

100.0

0.29 

.45 

.80 

1.19 

1.70 

3.09 

6.51

0.4 0.4 0.4 

.5 .5 .5 

.6 .7 .6 

.9 1.0 .9 

2.7 2.8 2.4 

7.8 9.6 9.0 

15.3 22.8 22.8 

23.8 41.3 45.1 

34.9 61.8 68.2 

46.6 77.1 82.4 

58.8 88.1 90.8 

70.1 94.9 95.5 

79.9 98.5 98.2 

89.9 99.5 99.4 

95.6 99.8 99.8 

98.3 100.0 99.8 

99.3 —— -_ 99.8 

100.0 ___ 100.0

Particle size (mm) at given

0.30 0.29 0.30 

.51 .43 .43 

1.00 .63 .61 

1.56 .82 .76 

2.41 1.07 .95 

4.55 1.73 1.50 

7.61 2.85 2.70

0.21 0.21 

.28 .28 

.37 .40 

.52 .65 

.85 1.31 

2.62 3.06 

6.41 6.34

6-26-75 6-26-75 

11.3 11.1 

0.0513 0.0683

size (mm) indicated

0.3 0.1 

.4 .2 

.4 .3 

.7 .5 

1.8 1.0 

5.6 2.9 

15.3 9.4 

31.9 24.5 

48.3 48.4 

64.1 69.4 

78.5 84.3 

89.0 93.0 

95.2 97.8 

98.3 99.1 

99.7 99.8 

100.0 100.0

percent finer

0.34 0.41 

.51 .60 

.76 .83 

1.04 1.03 

1.44 1.31 

2.36 1.99 

3.94 3.15

0.24 

.32 

.51 

.81 

1.22 

1.88 

2.76

5-28-76 

20.1 

0.0390

0.4 

.6 

.9 

1.5 

8.7 

25.8 

41.9 

52.6 

58.5 

63.4 

68.0 

72.0 

75.5 

79.6 

82.7 

84.9 

90.4 

92.6 

100.0

0.22 

.30 

.43 

.65 

1.59 

10.0 

23.6

0.24 

.30 

.41 

.56 

.87 

2.02 

3.55

5-28-76 

19.9 

0.0822

0.2 

.3 

.5 

.8 

3.7 

14.4 

35.1 

55.5 

66.3 

74.9 

83.1 

89.5 

93.6 

96.3 

97.9 

98.5 

98.9 

99.4 

100.0

0.28 

.37 

.50 

.64 

.96 

2.10 

4.67

0.24 

.32 

.55 

.92 

1.43 

2.52 

5.77

5-29-76 

21.0 

0.1205

0.3 

.4 

.5 

.8 

3.0 

10.2 

22.0 

35.2 

45.6 

57.3 

71.2 

83.6 

91.5 

96.5 

98.8 

100.0

0.29 

.43 

.70 

1.14 

1.70 

2.89 

4.95

0.26 

.35 

.69 

1.08 

1.54 

2.47 

3.86

5-29-76 

21.0 

0.0977

0.4 

.5 

.8 

1.2 

4.9 

19.7 

42.9 

63.5 

73.6 

80.9 

86.9 

91.5 

94.9 

97.5 

99.2 

99.7 

99.8 

100.0

0.25 

.33 

.45 

.56 

.74 

1.69 

4.03

0.26 

.35 

.52 

.82 

1.41 

2.40 

3.88

'Dates correspond to dates listed in table 6.

-Discharge over 14.6-m width of bedload trap; includes all flow over the active width of the streambed.

''Unit transport rate of solids in dry weight per second, over 14.6-m width of bedload trap.
TABLES 4-13 41

TABLE 8.—Summary of statistical data: log-transformed linear regression of transport rate by particle-size class versus

total transport rate, conveyor-belt sampler 1

Particlesize 

class 

(mm)

(size class) = Ajh (total)8 [Y = AXB ]

Number 

of data 

points

Y

(kg/m-s)

X

(kg/m-s)

Correlation 

coefficient, YIX 

(percent)

0.06-

.12-

.25-

.50-

1.00-

2.00-

4.00-

0.12

.25

.50

1.00

2.00

4.00

8.00

8.00-16.0 

16.0 -32.0 

32.0 -64.0

__86

__86 

__43

0.000092

.000520

.005519

.008326

.006535

.004139

.001659

.000460

.000379

.000800

0.029164

.029855

.029855

.029855

.029855

.029855

.029855

.030946

.049484

.107516

0.000961

.003627

.074800

.278676

.401883

.368044

.116466

.014618

.006132

.653752

0.663

.553

.742

1.000

1.173

1.278

1.211

.995

.926

3.007

0.912

.890

.954

.994

.992

.985

.957

.808

.875

.760

0.32

1.74

18.49

27.89

21.89

13.87

5.56

1.49

.77

.74

'Basic data as collected.

TABLE 9.—Summary of statistical data: log-transformed linear regression of transport rate by particle-size class versus

total transport rate, Helley-Smith sampler1

Particlesize 

class 

(mm)

Number 

of data 

points

jt, (size class) = A jt, (total)8 [Y = AXB ]

Y

(kg/m-sl

X

(kg/m-s)

Correlation 

coefficient, YIX 

(percent)

0.06-

.12-

.25-

.50- 

1.00- 

2.00- 4.00 

4.00- 8.00 

8.00-16.0 

16.0 -32.0

0.12

.25

.50

1.00

2.00

_.82 

__83 

__83

-83

-83 

__83 

__80

-68

0.000116

.001027

.007254

.008510

.006360

.003362

.001185

.000356

.000421

0.032706

.031693

.031693

.031693

.031693

.031693

.034352

.039981

.065133

0.001390

.008111

.080705

.319448

.419373

.348418

.066206

.005802

.001210

0.727

.599

.698

1.050

1.213

1.344

1.193

.867

.387

0.913

.858

.912

.978

.973

.939

.870

.714

.385

0.35

3.24

22.89

26.84

20.07

10.61

3.45

.89

.65

'Basic data as collected.

TABLE 10.—Listing of comparable data sets used in direct comparison of results from conveyor-belt sampler with results

from Helley-Smith sampler

Date

Effective discharge,' 

Q' (m3/s»

Conveyor 

belt

HelleySmith

Discharge

ratio 

squared,-

Unit bedload transport rate,3

jt, (kg/m-s)

Conveyor belt Helley-Smith

6-01-73__-_____________16.1 15.8 1.04 0.0190 0.0190 0.0065 0.0067

6-02-73———_____________17.8 17.5 1.03 .0235 .0235 .0277 .0287

6-03-73___-____________16.6 17.0 .95 .0240 .0240 .0425 .0405

6-06-73_________________11.3 11.4 .98 .0133 .0133 .0074 .0073

6-07-73 —————__________15.9 15.6 1.04 .0260 .0260 .0383 .0398

6-08-73————___________19.2 18.6 1.07 .0218 .0218 .0059 .0063

5-25-74 ___________ ___.5.34 5.34 1.00 .0056 .0056 .0046 .0046

5-26-74 ________________9.92 10.4 .91 .0822 .0632 .0451 .0410

5-26-74 ____________________9.92 9.73 1.04 .0822 .0632 .0583 .0606

5-27-74_....__________—21.5 21.9 .96 .1758 .1352 .1702 .1640

5-28-74____ —— ____________29.8 27.7 1.16 .2255 .1735 .1532 .1773

5-28-74_____________——29.8 30.3 .97 .2255 .1735 .2533 .2450

5-29-74__________________41.5 41.8 .99 .2912 .2240 .3025 .2982

__________—______32.2 33.8 .91 .0786 .0605 .1227 .1114

__________________22.9 23.5 .95 .0647 .0498 .0768 .0729

6-01-74_________________24.3 24.2 1.01 .0206 .0206 .0200 .0202

6-02-74_________________25.5 25.7 .98 .0130 .0130 .0106 .0104

6-03-74________________29.7 29.7 1.00 .0172 .0172 .0233 .0233

6-04-74—_________________27.9 28.0 .99 .0285 .0285 .0307 .0305

6-05-74_________________26.5 26.4 1.01 .0305 .0305 .0447 .0450

5-27-75 ————————————————2.44 2.44 1.00 .0021 .0021 .0034 .0034

5-27-75 ________________—2.44 2.44 1.00 .0021 .0021 .0062 .0062

6-02-75 ________________5.82 5.28 1.22 .0484 .0372 .0649 .0789

6-02-75 __________________5.82 5.25 1.23 .0484 .0372 .0749 .0920

6-03-75 _ ___-_________9.13 8.75 1.09 .0791 .0608 .0093 .0101
42 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

TABLE 10.—Listing of comparable data sets used in direct comparison of results from conveyor-belt sampler with results from

Helley-Smith sampler—Continued

Date

Effective discharge,' 

Q' <m:Vs)

Conveyor 

belt

HelleySmith

Discharge

ratio 

squared,2

Unit bedload transport rate,3 

jt, (kg/m-si

Conveyor belt Helley-Smith

6-04-75 - _ ____________10.0 9.73 1.06 .0812 .0625 .0983 .1038

6-05-75 —_____ — — —— — — 10.7 10.2 1.10 .0972 .0748 .0512 .0563

6-05-75_ ___________— 10.7 10.1 1.12 .0972 .0748 .0829 .0930

6-06-75 ———————————— _-20.0 19.7 1.03 .3114 .2395 .1076 .1109

6-06-75________________20.0 20.1 .99 .3114 .2395 .0860 .0851

6-07-75 _______-___________24.8 25.2 .97 .2069 .1592 .1262 .1222

6-07-75- _ _ ———————24.8 25.3 .96 .2069 .1592 .0474 .0455

6-07-75______________________24.8 24.9 .99 .2069 .1592 .2168 .2151

6-07-75- _ ___ .__________24.8 24.7 1.01 .2069 .1592 .1896 .1911

6-08-75_________________25.6 25.6 1.00 .1733 .1333 .2027 .2027

6-08-75-_- - __ __ ___ _______25.6 25.7 .99 .1733 .1333 .1025 .1017

6-09-75 _ ____________ 24.3 25.4 .92 .0838 .0722 .1185 .1085

6-09-75————— ——— — ————24.3 25.4 .92 .0838 .0722 .1054 .0965

6-10-75— ___ - _——______14.4 16.1 .80 .0348 .0268 .0674 .0539

6-10-75—___-______-_ — 14.4 15.9 .82 .0348 .0268 .0298 .0244

6-11-75— _ __—_---—-10.1 10.5 .93 .0110 .0110 .0210 .0194

6-11-75--- _____-____——— 10.1 10.4 .94 .0110 .0110 .0225 .0212

6-13-75— ———— ——— — — —— 15.8 15.9 .99 .0277 .0213 .0337 .0333

6-13-75 ——— ———— ———— 15.8 15.9 .99 .0277 .0213 .0252 .0249

6-17-75——___—____________22.2 23.0 .93 .0796 .0612 .0879 .0819

6-17-75 _ __________ _ 22.2 23.0 .93 .0796 .0612 .1052 .0980

6-18-75 ————————__-__ __12.8 13.1 .95 .0106 .0106 .0265 .0253

6-18-75 __________________-12.8 13.1 .95 .0106 .0106 .0195 .0186

6-19-75 ————— — — — —— — -.10.1 10.5 .93 .0097 .0097 .0163 .0151

6-19-75 ———— — ——— —— _—10.1 10.5 .93 .0097 .0097 .0114 .0106

6-21-75 - ————— ————— ———— 7.23 7.48 .93 .0032 .0032 .0039 .0036

6-21-75 _ ______________7.23 7.48 .93 .0032 .0032 .0051 .0048

6-22-75 ________________________7.01 7.27 .93 .0047 .0047 .0075 .0070

6-22-75 _ ___________ -7.01 7.27 .93 .0047 .0047 .0099 .0092

6-23-75 _____________________8.24 8.17 1.02 .0062 .0062 .0096 .0098

6-23-75 ______________________ __8.24 8.17 1.02 .0062 .0062 .0154 .0157

6-24-75—— __———————____lt).8 10.9 .98 .0194 .0194 .0254 .0249

6-24-75.- ——— ———— ———— 10.8 10.9 .98 .0194 .0194 .0183 .0180

6-25-75.- —————————————21.7 20.3 1.14 .0838 .0645 .0926 .1058

6-25-75 ———————————___-21.7 20.4 1.13 .0838 .0645 .0814 .0921

6-25-75_______ __ _———21.7 21.9 .98 .0838 .0645 .0912 .0895

6-25-75-----_______————21.7 21.9 .98 .0838 .0645 .0725 .0712

6-26-75---- - ____ _________13.1 15.1 .75 .0396 .0396 .0684 .0515

6-26-75.- - __ ——— — ——— 13.1 14.9 .77 .0396 .0396 .0976 .0754

6-26-75 ———————_____ — 13.1 11.3 1.34 .0396 .0396 .0513 .0689

6-26-75-________________ - _ _13.1 11.1 1.39 .0396 .0396 .0683 .0951

5_28-76- __________________ 18.8 20.1 .87 .0437 .0336 .0390 .0341

5-28-76.- - _ —____________18.8 19.9 .89 .0437 .0336 .0822 .0734

5-28-76____________________-19.8 20.1 .97 .0454 .0454 .0390 .0378

5-28-76__————————— ———— 19.8 19.9 .99 .0454 .0454 .0822 .0814

5-29-76--.-_-__________————20.5 21.0 .95 .0712 .0548 .1205 .1148

5-29-76———— — — — — __---20.5 21.0 .95 .0712 .0548 .0977 .0931

5-29-76———————— ————20.9 21.0 .99 .0618 .0618 .1205 .1194

5-29-76______________—--20.9 21.0 .99 .0618 .0618 .0977 .0968

'Discharge over 14.6-m width of bedload trap; includes all flow over the active width of the streambed.

'^Regression of transport data from table 4 indicates the transport rate is proportional to the square of the effective discharge. To correct for stage (discharge) 

differences between otherwise comparable conveyor-belt and Helley-Smith data sets, the appropriate correction applied to Helley-Smith transport data is the 

factor (QVfl/Q'y/s->2 .

3Umt transport rate of solids in dry weight per second, over 14.6-m width of bedload trap.

4Basic data as collected.

5Conveyor-belt data corrected to conditions of stream-wide slot.

G Helley-Smith data corrected for stage difference with conveyor-belt data; see note 2.
TABLES 4-13 43

TABLE 11.—Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler versus conveyor-belt

sampler (basic data)

Particle- Number 

size class of data 

(mm) points

0.06- 0.12 _ _ __ _61

.12- .25 _ _ __ ____61

.25- .50 __ _ _ ____61 

.50- 1.00 _________ _ 61

2.00- 4.00 _______ __ _61 

4.00- 8.00 ____ __ ____61 

8.00-16.0 ___ __ _____53 

16.0 -32.0 __ _14

Particlesize class 

(mm)

0.06- 0.12 ___________________

.12- .25 _ ______________

.25- .50 ___________________

.50- 1.00 ___________ ___ _ _

1.00- 2.00 ___________________

2.00- 4.00 ___________________

4.00- 8.00 _____ __ __________

8.00-16.0 __________________

16.0 -32.0 _________________

jb (Helley-Smith) = A jb (conveyor-belt)8 [y = AX"]

Logy

-3.713838 

-2.821671 

-1.961669 

-1.882042 

-1.975948 

-2.189868 

-2.668660 

-3.248296 

-3.330789

Number 

of data 

points

61

61

61

61

61

61

61

.____ _53

LogX SD(logy)

-3.804032 0.430278 

-3.147199 .280158 

-2.137697 .342941 

-1.876378 .540334 

-1.927100 .584104 

-2.126512 .584247 

-2.640915 .589985 

-3.219476 .632180 

-3.076402 .481029

y

(kg/m-s)

0.000193 

.001508 

.010923 

.013121 

.010569 

.006459 

.002145 

.000565 

.000467

SDdogX) Log A

0.389728 

.299980 

.361216 

.509253 

.584409 

.623490 

.682776 

.761091 

.458405

Jb

X

(kg/m — s I

0.000157 

.000713 

.007283 

.013293 

.011828 

.007473 

.002286 

.000603 

.000839

-0.1841 

-.4586 

-.2473 

-.1289 

3024

-.4831 

-.7161 

-.8438 

-1.7910

(Helley-Smith)

~YIX~ 

(percent)

123.08 

211.66 

149.98 

98.70 

89.36 

89.43 

93.81 

93.58 

55.67

B

0.928 

.751 

.802 

.934 

.868 

.803 

.739 

.747 

.501

r'2 Var (log (A))

0.7394 

.6463 

.7135 

.7755 

.7550 

.7336 

.7331 

.8085 

.2275

0.078713 

.052254 

.020564 

.016175 

.016799 

.019445 

.025106 

.028324 

.684715

SE (log(A))

0.280558 

.228591 

.143400 

.127180 

.129610 

.139445 

.158450 

.168298 

.827475

Var (B)

0.005384 

.005229 

.004377 

.004284 

.014148 

.003965 

.003378 

.002591 

.070886

= Ajb (conveyor-belt)8 [y = AXB ]

A

0.654 

.348 

.566 

.743 

.498 

.329 

.192 

.143 

.016

SE (A)

1.91 

1.70 

1.39 

1.34 

1.35 

1.38 

1.44 

1.47 

8.54

B

0.928 

.751 

.802 

.934 

.868 

.803 

.739 

.747 

.501

SE (B)

0.073 

.072 

.066 

.065 

.064 

.070 

.058 

.051 

.266

TABLE 12.—Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler 

versus conveyor-belt sampler (comparison of various modifications to the basic data) 1

Conditions 

applied 

to the 

regression 

statistics 

(see notes)

(2 )

(2,3)

( 4 ) 

(3,4)

(4, 5) 

(4, 5, 8) 

(4,7) 

(4,8) 

(4, 6, 8) 

(4, 5, 7) 

(4, 5, 8) 

(4, 5, 6, 8)

jt, (Helley-Smith) = A jb (conveyor-belt)8 [Y = AXB ]

Number 

of data 

points

74 

74 

74 

74 

74 

74 

61 

61 

61 

61 

61 

61

y

(kg/m-s)

0.041516 

.041516 

.041516 

.041516 

.041023 

.041023 

.048285 

.034967 

.034967 

.048045 

.034763 

.034763

X

(kg/m-s)

0.038041 

.038041 

.033349 

.033349 

.033349 

.033349 

.039375 

.032015 

.032015 

.039375 

.032015 

.032015

A

0.550 

1.150 

.762 

1.594 

.784 

.960 

.846 

.819 

1.016 

.873 

.843 

1.053

B

0.790 

1.013 

.856 

1.102 

.867 

.927 

.885 

.916 

.979 

.896 

.927 

.991

Correlation 

coefficient, 

r

0.881 

.881 

.881 

.881 

.887

.906 

.891

.908 

.893

YIX 

(percent)

109.14 

109.14 

124.49 

124.49 

123.01 

123.01 

122.63 

109.22 

109.22 

122.02 

108.58 

108.58

'Total bedload.

2Basic data as collected.

3Regression treats Helley-Smith data as independent variable.

^Conveyor-belt data corrected to conditions of stream-wide slot.

5Helley-Smith data corrected for stage difference with conveyor-belt data.

"Includes correction for variance of independent variable in least-squares regression.

'Excludes sediment particles smaller than 0.25 mm.

"Excludes sediment particles smaller than 0.50 mm.
44 SEDIMENT-TRAPPING CHARACTERISTICS OF THE HELLEY-SMITH BEDLOAD SAMPLER

TABLE 13.—Summary of statistical data: log-transformed linear regression of transport rate, Helley-Smith sampler versus conveyor-belt

sampler (conveyer-belt data corrected for conditions of stream-wide slot)

Particle- Numbe 

size class of date 

(mm) points

0.06- 0.12 ___________ 61

12- .25 __ ________ 61

.25- .50 ____________61 

.50- 1.00 ____________61

4.00- 8.00 _____ ___61

8.00-16.0 _______ ___ 53 

16.0 -32.0 _ _ ___ __ 14

Particlesize class 

(mm)

0.06- 0.12 __________________

.12- .25— — — — — —

.25- .50 ____________

1.00- 2.00 __________________

2.00- 4.00 ____________

4.00- 8.00 ____________

8.00-16.0 _ __ _ ______ _

16.0 -32.0 ________________

i

LogF

-3.713838 

-2.821671 

-1.961669 

-1.882042 

-1.975948 

-2.189868 

-2.669660 

-3.248296 

-3.330789

Number 

of data 

Points

61

61

61

— -61

61

61

__ 53

jb (Helley-Smith) =Ajh (conveyor-belt)8 [Y

LogX SDdogY) SDdogX)

-3.869253 C 

-3.212598 

-2.263078 

-1.941755 

1 992475

9 1 Q1 QQ9

-2.706331 

-3.285883 

-3.190414

X430278 

.280158 

.342941 

.540334 

.584104 

.584247 

.589595 

.632180 

.481029

0.356737 

.258133 

.319925 

.468626 

.545829 

.584976 

.645916 

.722824 

.458413

Log A

0.2701 

-.0341 

.0527 

.0899 

-.1372 

-.3323 

-.5720 

-.6607 

-1.7338

jb (Helley-Smith)

Y

(kg/m— s)

0.000193 

.001508 

.010923 

.013121 

.010569 

.006459 

.002145 

.000565 

.000467

X

(kg/m-s)

0.000135 

.000613 

.006265 

.011435 

.010175 

.006428 

.001966 

.000518 

.000645

~YIX 

(percent)

143.03 

246.00 

174.34 

114.74 

103.88 

100.47 

109.06 

109.04 

72.38

B

1.030 

.868 

.914 

1.016 

.923 

.848 

.775 

.788 

.501

= AXB ]

r2

0.7287 

.6392 

.7275 

.7758 

.7437 

.7200 

.7204 

.8107 

.2275

= Ajt, (conveyor-belt)8 [Y

A

1.863 

.924 

1.129 

1.230 

.729 

.465 

.268 

.218 

.018

Var 

(logCA))

0.100988 

.074816 

.025758 

.020139 

.021207 

.025468 

.030541 

.032110 

.735338

SE 

(logCA))

0.317786 

.273525 

.160494 

.141912 

.145626 

.189586 

.174759 

.179194 

.857518

Var(B)

0.006690 

.007203 

.005307 

.005052 

.004975 

.004734 

.003949 

.002839 

.070884

= AXB]

SE (A}

2.08 

1.88 

1.45 

1.39 

1.40 

1.44 

1.50 

1.51 

7?,0

B

1.030 

.868 

.914 

1.016 

.923 

.848 

.775 

.788 

.501

SE (B)

0.082 

.085 

.073 

.071 

.071 

.069 

.063 

.053 

.266