U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1774

Field Evaluation of the Error Arising from Inadequate 

Time Averaging in the Standard Use of Depth-Integrating 

Suspended-Sediment Samplers
FRONT COVER: 

Collection of suspended-sediment data from the measurement cableway at 

the U.S. Geological Survey Colorado River near Grand Canyon, Arizona, gaging 

station during April 1996 using a P-61 point-integrating suspended-sediment 

sampler. View looking upstream from the Kaibab Trail Bridge (see fig. 2B).
Field Evaluation of the Error Arising from Inadequate 

Time Averaging in the Standard Use of Depth-Integrating 

Suspended-Sediment Samplers

By David J. Topping, David M. Rubin, Scott A. Wright, and Theodore S. Melis 

Professional Paper 1774

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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Suggested citation:

Topping, D.J., Rubin, D.M., Wright, S.A., and Melis, T.S., 2011, Field evaluation of the error arising from inadequate 

time averaging in the standard use of depth-integrating suspended-sediment samplers: U.S. Geological Survey 

Professional Paper 1774, 95 p. 
Contents

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

Introduction.....................................................................................................................................................1

Purpose and Scope..............................................................................................................................3

Acknowledgments................................................................................................................................3

Study Sites.............................................................................................................................................3

Theoretical Framework .......................................................................................................................5

Data................................................................................................................................................................10

Analysis .........................................................................................................................................................14

At-a-Point Error...................................................................................................................................14

Effect of Changing Flow Conditions on the Mean At-a-Point Error...........................................15

Depth-Integrated Error......................................................................................................................25

Effect of Different Durations of Time Averaging on 

Suspended-Sediment-Concentration Errors...........................................................................26

Evaluation of Spatial Correlations Between Verticals and 

Temporal Correlations at Verticals in a Cross Section..........................................................35

Combination of Temporal and Spatial Errors into an Estimate of the 

Total Uncertainty in the Time-Averaged Velocity-Weighted 

Suspended-Sediment Concentration in a Cross Section .....................................................38

Conclusions...................................................................................................................................................48

References Cited..........................................................................................................................................49

Appendix A. Suspended-Sediment Data .................................................................................................53

Appendix B. Cross-Stream Spatial Structures in Depth-Integrated Suspended-Sediment

Concentration in Noncomposited Nine-Vertical Measurements at the River-mile 30

Sediment Station and Lower Marble Canyon Gaging Station ...................................................87

Figures

1. Map of the Colorado River drainage basin showing the locations of the study sites ..................4

2. Sampling locations at the four study sites ...........................................................................................6

3. Time-averaged sand flux, absolute value of the fluctuating component of the 

sand flux, minimum sand flux, and maximum sand flux among point samples..............................9

4. Depiction of different equal-width-increment sampling designs in a 

trapezoidal cross section......................................................................................................................13

5. At-a-point error in the flux of each size class of sediment at different elevations 

above the bed..........................................................................................................................................16

6. Combined mean at-a-point error as a function of grain size for the five datasets......................25

7. Combined mean at-a-point error as a function of Rouse number for the five datasets.............25

8. Comparison of the mean depth-integrated error in the velocity-weighted depth-integrated

suspended-sediment concentration in each size class and the mean at-a-point error 

in the flux of each size class of sediment...........................................................................................27

9. Likely range in the ratio of mean depth-integrated error to mean at-a-point error 

as a function of grain size in 10 cases ................................................................................................29

 iii
10. Likely range in mean value among all 10 cases in figure 9 of the ratio of mean

depth-integrated error to mean at-a-point error plotted as a function of grain size................30

11. Mean value of the mean at-a-point error among the five point-sample datasets, 

and mean values of the mean number-of-transits errors calculated for the one-way, 

two-way, and the various synthetic multitransit depth-integrated data plotted as a 

function of grain size ...........................................................................................................................32

12. Ratios between the mean values of the mean number-of-transits-errors in figure 11 

associated with different numbers of transits plotted as a function of grain size....................34

13. Examples of stable cross-stream spatial structures in depth-integrated 

suspended-sand concentration.........................................................................................................37

14. Examples of unstable cross-stream spatial structures in depth-integrated 

suspended-silt-and-clay concentration...........................................................................................39

15. Comparison of number-of-verticals relative standard error, mean number-of-transits 

relative standard error, and relative total uncertainty in equal-discharge-increment- or

equal-width-increment-measured suspended-sand concentration in a 

simple trapezoidal channel.................................................................................................................45

16. Examples of equal-width-increment-measured suspended-sand concentrations, 

with error bars, for four different equal-width-increment sampling designs, showing key

steps in analysis of behaviors of total uncertainty and number-of-verticals error ..................46

17. Comparison of empirical and theoretical relations between nSE, best and cumulative 

probability or confidence interval for total uncertainty and number-of-verticals error ..........47

18. Evaluation of the dependence of nSE, best associated with total uncertainty and 

number-of-verticals error on the “optimal concentration of agreement” .................................48

B1–B8. Cross-stream spatial structures in depth-integrated 

suspended-sediment concentration.................................................................................................88

Tables

1. Flow and sediment-supply conditions during the collection of point 

suspended-sediment samples............................................................................................................11

2. Levels of statistical significance at which the at-a-point error in each size 

class of sediment depends on elevation above the bed................................................................20

3. Levels of statistical significance at which the at-a-point error at each elevation 

above the bed depends on grain size................................................................................................22

4. Combined mean at-a-point error in each size class ±1 standard error.......................................23

5. Combined mean at-a-point error in each Rouse-number class ±1 standard error...................24

6. Levels of statistical significance at which the mean depth-integrated error 

depends on grain size..........................................................................................................................26

7. Levels of statistical significance at which groupings of the mean value of the 

mean at-a-point error and various mean number-of-transits-errors plotted in 

figure 11 are different in each sediment size class ........................................................................33

8. Levels of statistical significance associated with correlations (1) in suspended-sediment 

concentration between adjacent verticals in one measurement and (2) in cross-stream 

spatial structures in suspended-sediment concentration between two 

noncomposited nine-vertical measurements made hours apart on the same day...................36

9. Results from random-number simulations to determine the behavior of the 

standard-error form of the multivertical mean number-of-transits error ...................................42

iv
 v

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Volume

ounce, fluid (fl. oz) 0.02957 liter (L) 

pint (pt) 0.4732 liter (L) 

quart (qt) 0.9464 liter (L) 

gallon (gal) 3.785 liter (L) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

Mass

ounce, avoirdupois (oz) 28.35 gram (g) 

SI to Inch/Pound

Multiply By To obtain

Length

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Volume

liter (L) 33.82 ounce, fluid (fl oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s) 

cubic meter per second (m3

/s) 35.31 cubic foot per second (ft3/s)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

Horizontal coordinate information is referenced to the 

North American Datum of 1983 (NAD 83).
vi

Notation

Time-averaged value of x

<x> Depth-averaged value of x

Absolute value of x

Scalar magnitude of d



z dt

Unit vector in the x-direction

Cm Instantaneous concentration of suspended sediment in size class m at a point

CmDI Velocity-weighted concentration of sediment in size class m measured at a vertical 

with a depth-integrating sampler

Instantaneous concentration of all sand-size suspended sediment at a point

Time-averaged component of concentration of suspended sediment in size class m at a 

point averaged over a time scale longer than that of fluctuations in concentration as a 

 result of turbulence

Time-averaged component of concentration of all sand-size suspended sediment at a 

point averaged over a time scale longer than that of fluctuations in concentration as a 

 result of turbulence

Component of concentration of suspended sediment in size class m at a point that 

fluctuates over time as a result of turbulence

Component of concentration of all sand-size suspended sediment at a point that 

fluctuates over time as a result of turbulence

C1 Depth-integrated concentration in a given size class of suspended sediment at a 

vertical during the first of two sequential measurements

C2 Depth-integrated concentration in a given size class of suspended sediment at a 

vertical during the second of two sequential measurements

D Grain size

D50 Median grain size

DI Path taken by a depth-integrating sampler

k von Karman’s constant

m Suspended-sediment size class

n Number of measurements or observations

nSE Number of standard errors

ntrans Number of transits at each vertical

nverts Number of verticals in an equal-discharge-increment (EDI) or 

equal-width-increment (EWI) measurement

P Probability (confidence interval)

p Level of statistical significance

pm Rouse number for suspended-sediment size class m

	

x

	

x



	

d

z dt

	

x ˆ 

Csand

	

C m

Csand

C'

m

C′

sand
 vii

Q Discharge of water

SE Standard error of the mean

s Arc length along a given path in the complex plane 

T Total time the sampler nozzle is open in the water

t Time

Instantaneous velocity of water (vector)

u Scalar magnitude of downstream velocity in right-handed Cartesian coordinates 

(positive downstream) 

Reynold’s averaged magnitude of downstream velocity averaged over a time scale 

longer than that of fluctuations in velocity as a result of turbulence 

u' Component of downstream velocity that fluctuates over time as a result of turbulence

u* Shear velocity

v Scalar magnitude of cross-stream velocity in right-handed Cartesian coordinates 

 (positive from right to left bank)

w Scalar magnitude of vertical velocity in right-handed Cartesian coordinates (positive 

from bed to water surface)

wm Settling velocity for each sediment size class m

x Downstream position in a river in a right-handed Cartesian coordinate 

system (positive downstream) 

y Cross-stream position in a river cross section in a right-handed Cartesian coordinate 

 system (positive from right to left bank)

z Elevation above bed in a river cross section in a right-handed Cartesian coordinate 

system (positive from the bed to the water surface)

z0 Nikuradse roughness parameter

z(t) Scalar value of z at time t

Vector value of z at time t

f	 Unit of grain size equal to -log2D, where D is the grain size in millimeters

g Exponent in the denominator of equations relating the MNOTE to the number of 

transits and the MNOTESE to the number of verticals 

r Density of water

s Standard deviation

tb Boundary shear stress

z Nondimensionalized elevation above the bed

y Optimal concentration of agreement among EWI sampling designs composed of 

different numbers of verticals

ymax Maximum concentration among EWI sampling designs composed of different 

 numbers of verticals

ymin Minimum concentration among EWI sampling designs composed of different 

 numbers of verticals



U

	

u 



z t( )
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Field Evaluation of the Error Arising from Inadequate 

Time Averaging in the Standard Use of Depth-Integrating 

Suspended-Sediment Samplers 

By David J. Topping, David M. Rubin, Scott A. Wright, and Theodore S. Melis 

Abstract 

Several common methods for measuring suspended-sediment concentration in rivers in the United States use depthintegrating samplers to collect a velocity-weighted suspendedsediment sample in a subsample of a river cross section. 

Because depth-integrating samplers are always moving through 

the water column as they collect a sample, and can collect only 

a limited volume of water and suspended sediment, they collect 

only minimally time averaged data. Four sources of error exist 

in the field use of these samplers: (1) bed contamination, (2) 

pressure-driven inrush, (3) inadequate sampling of the crossstream spatial structure in suspended-sediment concentration, 

and (4) inadequate time averaging. The first two of these errors 

arise from misuse of suspended-sediment samplers, and the 

third has been the subject of previous study using data collected in the sand-bedded Middle Loup River in Nebraska. Of 

these four sources of error, the least understood source of error 

arises from the fact that depth-integrating samplers collect only 

minimally time-averaged data. 

To evaluate this fourth source of error, we collected 

suspended-sediment data between 1995 and 2007 at four sites 

on the Colorado River in Utah and Arizona, using a P-61 

suspended-sediment sampler deployed in both point- and oneway depth-integrating modes, and D-96-A1 and D-77 bag-type 

depth-integrating suspended-sediment samplers. These data 

indicate that the minimal duration of time averaging during 

standard field operation of depth-integrating samplers leads to 

an error that is comparable in magnitude to that arising from 

inadequate sampling of the cross-stream spatial structure in 

suspended-sediment concentration. This random error arising 

from inadequate time averaging is positively correlated with 

grain size and does not largely depend on flow conditions 

or, for a given size class of suspended sediment, on elevation above the bed. Averaging over time scales >1 minute is 

the likely minimum duration required to result in substantial 

decreases in this error. During standard two-way depth integration, a depth-integrating suspended-sediment sampler collects 

a sample of the water-sediment mixture during two transits at 

each vertical in a cross section: one transit while moving from 

the water surface to the bed, and another transit while moving 

from the bed to the water surface. As the number of transits is 

doubled at an individual vertical, this error is reduced by ~30 

percent in each size class of suspended sediment. 

For a given size class of suspended sediment, the error 

arising from inadequate sampling of the cross-stream spatial 

structure in suspended-sediment concentration depends only 

on the number of verticals collected, whereas the error arising 

from inadequate time averaging depends on both the number of 

verticals collected and the number of transits collected at each 

vertical. Summing these two errors in quadrature yields a total 

uncertainty in an equal-discharge-increment (EDI) or equalwidth-increment (EWI) measurement of the time-averaged 

velocity-weighted suspended-sediment concentration in a river 

cross section (exclusive of any laboratory-processing errors). 

By virtue of how the number of verticals and transits influences 

the two individual errors within this total uncertainty, the error 

arising from inadequate time averaging slightly dominates that 

arising from inadequate sampling of the cross-stream spatial 

structure in suspended-sediment concentration. Adding verticals 

to an EDI or EWI measurement is slightly more effective in 

reducing the total uncertainty than adding transits only at each 

vertical, because a new vertical contributes both temporal and 

spatial information. However, because collection of depth-integrated samples at more transits at each vertical is generally easier and faster than at more verticals, addition of a combination 

of verticals and transits is likely a more practical approach to 

reducing the total uncertainty in most field situations. Therefore, 

the most practical, best EDI or EWI sampling design to minimize the total uncertainty in time-averaged velocity-weighted 

suspended-sediment concentration is to double the number of 

transits collected during standard two-way depth integration and 

thus collect four transits at as many verticals as is practical for a 

given field situation. 

Introduction

Depth-integrating samplers are the standard devices used 

by the U.S. Geological Survey (USGS) and other workers to 
2 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

(once on the downward transit1 and once on the upward transit), 

these samplers collect only minimally time-averaged data. 

Thus, the velocity-weighted suspended-sediment concentration 

measured by depth-integrating samplers is actually a composite 

of the instantaneous fluxes of suspended sediment encountered 

as the sampler passes through each elevation in each vertical. 

Owing to turbulent velocity fluctuations (as reviewed by Tennekes and Lumley, 1972; McLean, 1992) and boils shed from 

dunes on the bed (as reviewed by Best, 2005), the suspendedsediment flux at any point in a river cross section may vary 

considerably over time scales of seconds to minutes. Therefore, 

because the instantaneous fluxes of suspended sediment can 

differ substantially from the time-averaged fluxes of suspended 

sediment at each elevation in each vertical, the suspendedsediment concentration in a cross section as measured by using 

a depth-integrating sampler does not necessarily equal the 

average velocity-weighted suspended-sediment concentration 

over the time scale required to complete an EDI or EWI measurement. Thus, minimal time averaging of the instantaneous 

fluxes of suspended sediment may lead to considerable errors 

in the velocity-weighted suspended-sediment concentration as 

measured by using depth-integrating samplers.

Suspended-sediment concentration and water discharge 

can be poorly correlated. In rivers, the concentration of some 

grain-size fraction of suspended sediment is typically controlled by changes in the upstream supply of this fraction. 

These supply-driven changes in suspended-sediment concentration can vary somewhat independently of the water discharge (Colby, 1963; Guy, 1970; Dinehart, 1998; Topping and 

others, 2000a, b; Rubin and Topping, 2001, 2008). In addition, 

the occurrence of a progressive lag between suspended-sediment concentration and the kinematic discharge wave during 

a flood may also result in poor correlation between suspended-sediment concentration and water discharge (Heidel, 

1956; Dinehart, 1998). Therefore, many measurements of 

suspended-sediment concentration may be required over time 

to accurately calculate suspended-sediment loads (Porterfield, 

1972). Because of this requirement and the labor intensity and 

cost of EDI or EWI measurements of suspended-sediment 

concentration, other approaches, such as automatic pump 

samplers (for example, Edwards and Glysson, 1999), optical 

backscatter (for example, Webster and others, 2000; Schoellhamer, 2001), laser diffraction (for example, Melis and others, 

2003; Topping and others, 2004, 2006), or acoustic attenuation and backscatter (for example, Topping and others, 2004, 

2006, 2007a; Wall and others, 2006), have been used to collect 

data at a much higher temporal resolution than is practical 

with EDI or EWI measurements. Measurements of suspendedsediment concentration using these other approaches are typically calibrated to the velocity-weighted suspended-sediment 

concentration in a cross section on the basis of EDI or EWI 

1

 “One transit” is defined herein as the path a depth-integrating suspendedsediment sampler takes either from the water surface to the bed or from the 

bed to the water surface. Therefore, standard deployment of a depth-integrating 

sampler at a vertical, where the nozzle is open as the sampler is lowered to the 

bed and subsequently raised to the surface, consists of two transits.

measure suspended-sediment concentration in rivers (Edwards 

and Glysson, 1999; Nolan and others, 2005). These devices 

are deployed in a subsample of a river cross section by using 

either the equal-discharge-increment (EDI) or the equal-widthincrement (EWI) method. In the EDI method, a river cross 

section is divided into multiple increments of equal discharge, 

whereas in the EWI method, a river cross section is divided 

into multiple increments of equal width. The center of each 

increment in either method is termed a “vertical.” These verticals together compose the subsample of the river cross section 

that is assumed to be representative of the flow and suspendedsediment conditions in the entire cross section. An insufficient 

number or incorrect location of verticals will therefore result 

in an error arising from inadequate sampling of the crossstream spatial structure in suspended-sediment concentration. 

It is important to recognize, however, that, because a finite 

amount of time is required to complete EDI and EWI measurements (possibly a minimum of 15 minutes to >1 hour), the 

data obtained by either method are not a true spatial average 

because flow and sediment-supply conditions may change 

over the time interval required to complete a single measurement (resulting in substantial changes in the cross-stream 

spatial structure in suspended-sediment concentration). 

Correct deployment of a depth-integrating sampler using 

either the EDI or EWI method results in a measurement of the 

velocity-weighted concentration of each size class of suspended sediment in a cross section (over the finite time interval of the measurement). In both these methods, the mixture 

of water and suspended sediment is sampled at each vertical 

by lowering the depth-integrating sampler to the bed and then 

immediately raising the sampler to the surface at a constant 

transit rate. Depth-integrating samplers have isokinetic nozzles 

that remain open and sample at the local instantaneous flow 

velocity. Therefore, these samplers collect a velocity-weighted 

sample of the water-sediment mixture as they move through 

the water column. In the EWI method, the goal is to hold the 

sampler transit rate constant among all the verticals. Depending on the cross-stream distribution of discharge, the volumes 

of water collected at various verticals may differ substantially 

when this method is used. In the EDI method, the transit rates 

at various verticals may differ from one another, depending on 

the cross-stream distribution of discharge. If a sample collected by using the EDI method is to be composited before 

laboratory analysis, an equal volume of water must be collected at each vertical; otherwise the sample collected at each 

vertical must be analyzed separately for suspended-sediment 

concentration and grain size. In both the EWI and compositedEDI methods, the velocity-weighted suspended-sediment 

concentration in the cross section is calculated by summing 

the mass of suspended sediment collected at all the verticals 

and then dividing by the total volume of water-sediment mixture collected at all the verticals. No averaging of observations 

among the different verticals occurs in either of these methods. 

Because depth-integrating samplers are continuously moving through the water column when deployed in either method, 

and pass through any given elevation in each vertical only twice 
Introduction 3

measurements made using depth-integrating samplers. Thus, 

the errors arising from the use of depth-integrating samplers 

are additive to those associated with these other approaches 

to measuring suspended-sediment concentration. These other 

approaches, in turn, may have errors comparable to those 

associated with the field use of depth-integrating samplers 

(Topping and others, 2006). Thus, accurate calibration of any 

of these other approaches requires a detailed understanding 

of the sources, styles (that is, systematic bias or random), and 

magnitudes of the various errors associated with the field use 

of depth-integrating samplers. 

Of all these errors, the best understood are those that arise 

from bed contamination (Allen and Petersen, 1981), pressuredriven inrush on the downward transit (Edwards and Glysson, 

1999), and inadequate sampling of the cross-stream spatial 

structure in suspended-sediment concentration (Guy and Norman, 1970; Edwards and Glysson, 1999). Although bed contamination and pressure-driven inrush may lead to large positive 

and negative systematic errors (biases), respectively, these two 

errors should be negligible if a depth-integrating sampler is 

deployed properly, that is, if the sampler nozzle does not gouge 

the bed and the sampler is not operated at too high a transit rate. 

Because we took great care to deploy suspended-sediment samplers properly in this study, these two errors are assumed to be 

negligible in the analyses herein and are therefore disregarded. 

Inadequate sampling of the cross-stream spatial structure in 

suspended-silt-and-clay concentration has been estimated to 

result in negligible errors because these grain sizes are generally 

transported as washload and so are fairly uniformly distributed 

in many river cross sections (Guy and Norman, 1970; Edwards 

and Glysson, 1999). However, inadequate sampling of the crossstream spatial structure in suspended-sand concentration may 

lead to large positive or negative errors, depending on channel 

geometry and the distribution of sand on the bed upstream from 

the measurement cross section. Although this error is expressed 

as a relative standard error by Guy and Norman (1970) and 

Edwards and Glysson (1999), thus implying that it is random, it 

may be systematic over time scales longer than those required 

to complete an EDI or EWI measurement because the spatial 

cross-stream structure in suspended-sand concentration in a 

cross section is controlled by features that either are constant 

or change relatively slowly (for example, interaction between 

the flow and channel geometry, distribution of sand on the bed 

upstream from the measurement cross section, and the geometry 

and positions of dunes on the bed upstream from the measurement cross section). In this report, this error is therefore referred 

to as “quasi-systematic.” Although the error in suspended-sand 

concentration arising from subsampling a cross section with too 

few verticals may be as great as ±40 percent for highly nonuniform cross sections, it is likely less than or equal to ±4 percent 

in trapezoidal cross sections when five or more verticals are 

used (Guy and Norman, 1970, fig.25; Edwards and Glysson, 

1999, fig. 38). Among the least understood errors associated 

with the field use of depth-integrating samplers is the random 

error arising from the fact that these samplers collect only minimally time-averaged data. 

Purpose and Scope

The purpose and scope of this report are (1) to report 

on data collected to evaluate the error that arises from depthintegrating suspended-sediment samplers collecting minimally 

time-averaged data when deployed according to the standard 

methods described by Edwards and Glysson (1999) and (2) to 

analyze these data to evaluate the importance of this error and 

possible methods to reduce this error. We collected suspendedsediment data at four sites on the Colorado River in Utah 

and Arizona between 1995 and 2007, which we analyzed to 

determine the magnitude of the error arising from the minimal 

time averaging that occurs under standard field operation of 

depth-integrating samplers. We then compared the magnitude 

of this error with estimates of the error arising from inadequate 

sampling of the cross-stream spatial structure in suspendedsediment concentration. Finally, we suggest sampling protocols 

to reduce the error arising from inadequate time averaging.

Acknowledgments

This research was funded by the U.S. Department of the 

Interior’s Glen Canyon Dam Adaptive Management Program 

through the USGS Grand Canyon Monitoring and Research 

Center, USGS Water Resources Discipline, the National 

Research Program of the USGS Water Resources Discipline, 

and the Federal Interagency Sedimentation Project. Jonathan 

Nelson (USGS), Randy Parker (USGS), Dallas Childers 

(USGS), David Schoellhamer (USGS), Johnny McGregor 

(U.S. Army Corps of Engineers), Rich McDonald (USGS), 

and the first author all participated in the collection of suspended-sediment data in 1995, Joe Lyons (Bureau of Reclamation) in 1996, Les Vierra in 1998, Ron Griffiths, Robert Tusso, 

Nicholas Voichick, David Mueller, and Stuart Reeder in 2006, 

and Ron Griffiths, Tom Sabol, Nicholas Voichick, and Stuart 

Reeder in 2007. John Gray (USGS Office of Surface Water), 

Doug Glysson (USGS Office of Water Quality), Roger Kuhnle 

(U.S. Department of Agriculture’s Agricultural Research 

Service), and David Schoellhamer (USGS California Water 

Science Center) provided insightful reviews of the manuscript. 

Study Sites

The study sites for this report (fig. 1) are the USGS 

“Colorado River near Cisco, Utah,” gaging station (herein 

referred to as the Cisco gaging station); a location on the 

Colorado River at river mile 30 in Grand Canyon National 

Park (herein referred to as the River-mile 30 sediment station); 

the USGS “Colorado River above Little Colorado River near 

Desert View, Arizona,” gaging station (herein referred to as 

the Lower Marble Canyon gaging station); and the USGS 

“Colorado River near Grand Canyon, Arizona,” gaging station 

(herein referred to as the Grand Canyon gaging station). The 

geometries of the sampled cross sections at these study sites 

are similar to the simple, trapezoidal cross section geometry 
4 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

preferred by the USGS for the geometry of the measurement 

cross section at gaging stations (Rantz and others, 1982). 

Mean velocities, suspended-silt-and-clay concentrations, 

and suspended-sand concentrations measured in these cross 

sections cover most of the normal range in rivers at USGS 

gaging stations. During collection of the suspended-sediment 

samples analyzed in this study, depth-averaged flow velocities 

ranged from ~0.1 to 3 m/s, depth-integrated suspendedsilt-and clay concentrations from ~10 to 10,000 mg/L, and 

depth-integrated suspended-sand concentrations from ~20 to 

4,000 mg/L. Finally, the bed sediment at the sampled cross 

sections ranged in composition from all sand to mostly gravel, 

with intermediate compositions of various mixtures of sand 

and gravel. Therefore, the results from this study should be 

generally applicable. 

During the initial phase of this study in May 1995, 

we measured suspended-sediment concentrations from the 

upstream side of the historic wooden Dewey Bridge (destroyed 

by fire in April 2008), located 800 m downstream from the 

Cisco gaging station (figs.1, 2A). The reach between the gaging 

station and the bridge is relatively straight, with a riffle located 

~100 to 200 m upstream from the bridge serving as hydraulic 

control for the gaging station and a second riffle located ~500 

m downstream from the bridge serving as hydraulic control 

for the pool under the bridge. The cross section at the bridge is 

approximately trapezoidal to triangular, with the deepest part of 

the cross section on the right (north) side. Dunes were present 

on the bed under the bridge during measurements.

In March 1996, fieldwork shifted to the Grand Canyon 

gaging station (figs.1, 2B). The reach at the Grand Canyon 

gaging station is relatively straight, with the debris fan formed 

at the mouth of Bright Angel Creek serving as hydraulic 

control for the gaging station. Two gages are present in the 

reach, one located on the right bank (constructed in 1922) and 

one located 200 m upstream on the left bank (constructed in 

1933). Downstream from the left-bank gage, the water depth 

decreases, the high-velocity core broadens, and velocities 

become more uniform across the channel. The measurement 

cableway is located 190 m downstream from the left-bank 

gage in this region of more uniform flow; the herein-reported 

Figure 1. Colorado River drainage basin 

showing locations of study sites on the 

Colorado River at the Cisco gaging station 

(USGS Colorado River near Cisco, Utah gaging 

station, sta. number 09180500); at the Rivermile 30 sediment station; at the Lower Marble 

Canyon gaging station (USGS Colorado River 

above Little Colorado River near Desert 

View, Arizona, gaging station, sta. number 

09383100); and at the Grand Canyon gaging 

station (USGS Colorado River near Grand 

Canyon, Arizona, gaging station, sta. number 

09402500). Base modified from figure 1 of 

Smith and others (1960).

Salt

Lake 

City

Las Vegas

Denver

Cheyenne

Phoenix

Los Angeles

San Diego

NEW MEXICO

UTAH

COLORADO

WYOMING

NEVADA

CALIFORNIA

MEXICO PACIFIC OCEAN

 GULF OF

CALIFORNIA

RIVER

R

RIVER

Green

R

Paria

R

Little

R

Gila

River

ARIZONA

Lake Mead

 Reservoir

TEXAS

09402500

Hoover Dam

IDAHO

09180500

Grand Canyon National Park 

USGS gaging station with

station number

Boundary of Colorado River

drainage basin 

EXPLANATION

40

35

110 105

1000 200

MILES

KILOMETERS

COLORADO

 Glen 

 Canyon 

 Dam

COLORADO

San Juan

Dolores R

09383100

River-mile 30 sediment

station

Colorado

0 100 200
Introduction 5

suspended-sediment concentrations were measured from this 

cableway. The cross section at this cableway is trapezoidal, 

with the right (north) half tending to be slightly deeper than 

the left half. Dunes were present on the bed upstream from 

and under the cableway (Rubin and others, 2001; R. Anima, 

written commun., 2006; Topping and others, 2007b); scour 

and fill of the bed in this reach were described in detail by 

Topping and others (2000a, b). Suspended-sediment data 

were collected from the measurement cableway at this gaging 

station during March–April 1996, September 1998, and 

August 2007.

 The Lower Marble Canyon gaging station is located 

123 km downstream from Glen Canyon Dam and 41 km 

upstream from the Grand Canyon gaging station (figs. 1, 

2C). We measured suspended-sediment concentrations at this 

study site in September 1998, February 2006, August 2006, 

February 2007, and August 2007. In 1998, measurements 

were made from the measurement cableway (removed in 

June 2003), located ~100 m upstream from the now-removed 

right-bank gage; and in 2006 and 2007, measurements were 

made from a boat positioned under a tagline located at the 

former site of the measurement cableway. This measurement 

cross section is herein referred to as cross section C. The 

reach at the site is relatively straight, and the measurement 

cross section is also trapezoidal, with the right (west) half 

slightly deeper than the left half. Rotating-side-scan-sonar 

data (Rubin and others, 2001; Rubin and others, 2006) 

collected in 1998 indicated that starved dunes composed 

of sand were present on the gravel bed at the measurement 

cross section. During February 2006, August 2006, February 

2007, and August 2007, pipe dredging indicated that the bed 

consisted of sand patches on gravel (confirmed by subsequent 

underwater video transects). Additional measurements 

were made during February and August 2007 from a boat 

positioned under taglines at two other cross sections, A and B, 

located upstream from cross section C (fig. 2C). Cross section 

A is approximately triangular, with the right (west) half 

deeper than the left half; and cross section B is trapezoidal, 

with a narrow, much deeper section located adjacent to the 

left (east) bank. Underwater video transects indicated that 

the bed at these two upstream cross sections was composed 

of much more gravel than was the bed at cross section C; 

the bed at cross section A was composed almost entirely of 

boulders, whereas the bed at cross section B was composed 

largely of gravel with relatively small sand patches (mostly 

located in the deeper, left part of the cross section). Hydraulic 

controls for cross sections A, B, and C are formed by debris 

fans A, B, and C, respectively, deposited at the mouths of 

unnamed small tributaries (fig. 2C). 

The River-mile 30 sediment station is located 73 km 

downstream from Glen Canyon Dam and 91 km upstream 

from the Grand Canyon gaging station (figs. 1, 2D). We 

measured suspended-sediment concentrations at this study 

site in February 2006, August 2006, February 2007, and 

August 2007 from a boat positioned under a tagline. This 

measurement cross section is herein referred to as cross 

section B. The reach at this site is also straight, and the 

measurement cross section is trapezoidal, with the right (west) 

half slightly deeper than the left half. During February 2006, 

August 2006, February 2007, and August 2007, pipe dredging 

indicated that sand covered the bed under the tagline and that 

dunes were present (confirmed by subsequent underwater 

video transects). We measured suspended-sediment 

concentrations during February and August 2007 from a boat 

positioned under an additional tagline located at cross section 

A, 450 m upstream from cross section B (fig. 2D). Cross 

section A is trapezoidal, with the left (east) half slightly deeper 

than the right half. Underwater video transects indicated that 

the bed at this upstream cross section was composed of much 

more gravel than was the bed at cross section B; the bed at 

cross section A was composed of sand patches on gravel, 

whereas the bed at cross section B was composed almost 

entirely of sand. Hydraulic controls for cross sections A and B 

are formed by debris fans A and B, respectively, deposited at 

the mouths of unnamed small tributaries (fig. 2D).

Theoretical Framework

The instantaneous velocity of water, 

	



U , is a vector quantity (that is, it has both magnitude and direction). In a standard 

right-handed Cartesian coordinate system, 

 , (1) 

where 

	

x ˆ is the unit vector in the x-direction, 

	

y ˆ is the unit 

vector in the y-direction, 

	

z ˆ is the unit vector in the z-direction, 

u is the scalar magnitude of the velocity in the downstream 

direction, v is the scalar magnitude of the velocity in the crossstream direction, and w is the scalar magnitude of the velocity 

in the vertical direction. In a right-handed Cartesian coordinate 

system in a river cross section, x is positive in the downstream 

direction, y is positive moving from the right bank to the left 

bank (left and right banks defined when facing downstream), 

and z is positive moving from the bed to the water surface. To 

simplify the mathematics in this report as much as possible, 

we assume v and w to be zero, with u therefore becoming 

equal to the scalar magnitude of the velocity in the direction 

parallel to the nozzle orientation of a suspended-sediment 

sampler. We note that in real field settings, this simplification 

may not hold because the nozzle (that is, intake) of a suspended-sediment sampler may not point directly into the flow 

direction, especially when w is locally large. In such situations, the velocity of water entering the sampler intake may be 

less than the local flow velocity described by vector algebra. 

Given the above simplification, the instantaneous velocity 

of water at a point in time in the direction pointing into the 

nozzle of a suspended-sediment sampler can be defined as

 , (2)

where 

	

u is the Reynold’s averaged magnitude of the velocity 

averaged over a time scale longer than that of the fluctuations 

in velocity as a result of turbulence and

	

u ′	 is the component of 

the velocity that fluctuates over time as a result of turbulence. 



	



U = ux ˆ + vy ˆ + wz ˆ 

	

u = u + u ′	
6 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure 2. Sampling locations at the four study sites in the Colorado River drainage basin (fig. 1). Coordinate system in NAD 1983. A, 

P-61 point-integrating suspended-sediment sampler deployed from upstream side of the Dewey Bridge near the Cisco gaging station. B, 

Orthorectified aerial photograph of study site near the Grand Canyon gaging station, showing locations of the debris fan formed by Bright 

Angel Creek, the Kaibab Trail Bridge, left-bank (upper) gage, right-bank (lower) gage, measurement cableway, and stations at 190 ft and 290 

ft along cableway where principal two verticals described in this report were located. C, Orthorectified aerial photograph of study site near 

the Lower Marble Canyon gaging station, showing locations of three measurement cross sections (XS A, XS B, XS C) where suspendedsediment data were collected. Hydraulic controls for these three cross sections are identified as debris fans A, B, and C, respectively. 

Measurement cross section C is the site of former measurement cableway. D, Orthorectified aerial photograph of study site near the 

River-mile 30 sediment station, showing locations of two measurement cross sections (XS A, XS B) where suspended-sediment data were 

collected. The hydraulic controls for these two cross sections are identified as debris fans A and B, respectively.

A

Measurement

 cableway

 Bright Angel

 Creek fan

 Left-bank

 gage

 Right-bank

 gage

190 ft

 Flow 290 ft

 direction

112°05'30" W 112°05'20" 112°05'10"

36°

06'

10"

N

36°

06'

100 m

 Kaibab Trail

 bridge

B

XS A

XS B

XS C

Debris

 fan C

Debris

 fan B

Debris

 fan A

 Flow

 direction

200 m

111°48'20" W

36°

12'

36°

12'

20"

N

111°48'

C

100 m

111°50'50" W 111°50'40" 111°50'30"

36°

31'

30"

N

36°

31'

20"

36°

31'

10"

XS A

XS B

Debris

 fan A

Debris

 fan B

 Flow

 direction

D
Introduction 7

Likewise, the instantaneous concentration of suspended sediment in size class m at a point in time can be defined as

 

	

Cm = C m + C ′	

m , (3)

where 

	

C m is the component of concentration averaged over a 

time scale longer than that of the fluctuations in concentration as 

a result of turbulence and 

	

C ′	

m is the component of concentration 

that fluctuates over time as a result of turbulence. Using the convention in equations 2 and 3, the instantaneous flux of suspended 

sediment in size class m at a point in time is defined as

 

	

uCm = uCm + ( ) uCm

′, (4)

where 

	

uCm is the component of the flux averaged over a 

time scale longer than that of the fluctuations in velocity 

and concentration as a result of turbulence and 

	

( ) uCm

′ is the 

component of the flux that fluctuates over time as a result of 

turbulence. The instantaneous flux of suspended sediment in 

all M size classes at a point in time is therefore

 

u Cm

m =1

M

∑ = u Cm

m =1

M

∑ + u Cm

m =1

M

∑











′

. (5)

Suspended-sediment samplers cannot collect data at an 

instant in time because a finite amount of sample (that is, 

water-sediment mixture) is required for laboratory analysis. 

For the purposes of this report, therefore, the time scale associated with time-averaged components is greater than several 

minutes, and the time scale associated with fluctuating components is much less than 1 minute (that is, the minimum time 

required to collect a suspended-sediment sample at a point). 

Depth-integrating samplers can sample 

	

uCm at each 

elevation (that is, point) in each vertical2 only as they move 

through the water column. Because 

	

uCm varies over time 

at each elevation and depth-integrating samplers are always 

moving through the water column as they collect the watersediment mixture, the mathematical expression of 

	

CmDI , the 

velocity-weighted concentration of sediment in each size class 

m measured at a vertical with a depth-integrating sampler, is 

complicated. 

	

CmDI is not a depth- or time-averaged quantity. 

To be a depth-averaged quantity, 

	

CmDI would have to be the 

velocity-weighted concentration of suspended sediment in 

size class m averaged over the entire flow depth at an instant 

in time, whereas to be a time-averaged quantity, 

	

CmDI would 

have to be the velocity-weighted concentration of suspended 

sediment in size class m averaged over a suitably long time 

scale, that is, longer than that of turbulent fluctuations. 

The best approach to mathematically describe 

	

CmDI may 

be to use path integration, a type of line integration (Press and 

others, 1992; Weisstein, 2004), where DI is defined as the path 

taken by the depth-integrating sampler. There are two styles 

of depth integration: (1) one-way depth integration, where DI

is either from the water surface to the bed (with the nozzle 

2

 “Vertical” in this usage and as used throughout this report refers to 

the station at which a suspended-sediment sampler is deployed, not the 

z-direction.

closed when the sampler reaches the bed) or from the bed to 

the water surface (with the nozzle opened at the bed before the 

sampler is raised to the water surface); and (2) two-way depth 

integration, where DI is from the water surface to the bed and 

then back to the water surface. In one-way depth integration, 

DI consists of a single transit, and no time averaging occurs 

because the water-sediment mixture is sampled at each elevation only once. In two-way depth integration, DI consists of 

two transits, and only minimal time averaging occurs because 

the water-sediment mixture is sampled at each elevation twice. 

This minimal time averaging at each elevation occurs over 

different time intervals because it takes a finite amount of time 

for the sampler to move through the water column. Although 

time averaging occurs in two-way depth integration, 

	

CmDI is 

not necessarily an adequately time-averaged quantity because 

(1) even though an average can be calculated from only two 

values, such an average is not necessarily a physically meaningful time average, (2) the time scale of the average differs at 

each elevation because the sampler collects different volumes 

of water from each elevation (owing to the sampler encountering different water velocities as it moves at a constant 

transit rate through the water column), and (3) the time scale 

of the average is not necessarily longer than that of turbulent 

fluctuations.

Regardless of the style of depth integration, 

	

CmDI can be 

defined by using path integration as follows:

 , (6)

where s denotes the arc length along DI. Rearranging, making the appropriate substitutions into equation 6 for s to be a 

complex number, and defining 

	

DI :s = z(t) as the path in the 

complex plane parameterized by time t from 0 to T yields

 

CmDI = ( ) uCm 0

T

∫ dz

dt





 



 dt u 0

T

∫ dz

dt





 



 dt , (7)

where T is the total time the sampler nozzle is open in the 

water along DI.

3 z depends on time t because the elevation of 

the sampler nozzle in the flow changes over time. 

Two key assumptions are implicit in the standard field 

use of depth-integrating samplers. The first assumption is 

that the velocity-weighted concentration of each size class of 

suspended sediment in an entire cross section can be calculated from the velocity-weighted concentration of each size 

class of suspended sediment measured at the verticals composing the EDI or EWI subsample of the cross section. This 

assumption was the focus of a 1968 analysis by P.R. Jordan 

that led to the technique adopted by the USGS for determining the number of verticals needed to achieve a specified error 

(Guy and Norman, 1970; Edwards and Glysson, 1999). Jordan 

analyzed the suspended-sediment data that Hubbell and others 

3

 Note that z(t) in equation 7 is a scalar quantity only because the sampler is 

moving up and (or) down along a transit path that is parallel to the z-direction. 

In the general form of path integration, 

z(t) would be a vector quantity, and 

dz dt in equation 7 would be replaced by 

	

d

z dt , the scalar magnitude of 

d



z dt .

CmDI = ( ) uCm DI ∫ ds u ds DI ∫
8 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

(1956) collected in the sand-bedded Middle Loup River near 

Dunning, Nebraska. Jordan’s analysis was based on Colby’s 

(1964) theoretical distribution of 

	

uCm in a steady, uniform 

flow with an effectively infinite upstream supply of sediment. Therefore, his analysis may not hold for the field use of 

depth-integrating samplers because, as these samplers collect 

only minimally time-averaged data under standard field operation, 

	

uCm is never truly measured. This limitation leads to 

the second assumption that over the time interval required to 

complete an EDI or EWI measurement, the velocity-weighted 

suspended-sediment concentration measured with a depthintegrating sampler in an EDI or EWI subsample of a cross 

section approximately equals the true time-averaged velocityweighted suspended-sediment concentration in this subsample. 

Basically, the error in an EDI or EWI measurement arising 

from minimal time averaging is generally assumed to be 

much smaller than the error arising from inadequate sampling 

of the cross-stream spatial structure in suspended-sediment 

concentration.

This second assumption, however, may not be valid. For 

a given sediment size class m, the absolute value of the fluctuating component of the suspended-sediment flux,

	

( ) uCm

′ , at 

individual points in the verticals in an EDI or EWI subsample 

of a cross section may, in fact, be large relative to the timeaveraged suspended-sediment flux, 

	

uCm, at these points. This 

effect may lead to large errors, as illustrated by the following 

two cases where the size class m is set equal to all sand-size 

sediment (and the subscript m is replaced by “sand”). 

In the first case, ( ) uCsand

′ << uCsand at all points in a 

vertical (thus satisfying the condition required for the second 

assumption to be true), the error in the velocity-weighted 

suspended-sand concentration measured by a depth-integrating sampler relative to the true depth- and time-averaged 

velocity-weighted suspended-sand concentration is, in fact, 

minimal, as illustrated by point samples collected by using a 

P-61 point-integrating suspended-sediment sampler (Edwards 

and Glysson, 1999) at the Grand Canyon gaging station on 

March 28, 1996 (fig. 3A). In this case, the depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from the minimum values of uCsand measured at each elevation 

is only 5.3 percent4

 less than the time- and depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from uCsand at each elevation. Likewise, the depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from the maximum values of uCsand measured at each elevation 

is only 6.4 percent greater than the time- and depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from uCsand at each elevation. Thus, in this first case, the 

4

 Because a finite amount of time is required to collect point suspendedsediment samples, the “instantaneous” values of uCsand and ( ) uCsand

′

calculated from point samples are, in fact, averaged over seconds. Thus, the 

amplitudes of the fluctuations in fluxes calculated from the point samples are 

damped, leading to errors that are likely to be somewhat smaller than those 

that would be calculated if true instantaneous fluxes could be measured.

velocity-weighted depth-averaged suspended-sand concentration measured by a depth-integrating sampler would be within 

~5 to 6 percent of the true depth- and time-averaged velocityweighted suspended-sand concentration at this vertical.

In contrast, in a case where ( ) uCsand

′ approaches or 

is greater than uCsand at one or more points in a vertical, the 

error in the velocity-weighted suspended-sand concentration measured by a depth-integrating sampler relative to the 

true depth- and time-averaged velocity-weighted suspendedsediment concentration can be substantial, as illustrated by 

P-61 point samples collected at the Cisco gaging station 

on May 10, 1995 (fig. 3B). In this case, the depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from the minimum values of uCsand measured at each elevation is 54 percent less than the time- and depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from uCsand at each elevation. Similarly, the depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from the maximum values of uCsand measured at each elevation is 104 percent greater than the time- and depth-averaged 

velocity-weighted suspended-sand concentration calculated 

from uCsand at each elevation. Therefore, in this second case, 

the velocity-weighted suspended-sand concentration measured 

by a depth-integrating sampler would be within only 54 to 

104 percent of the true depth- and time-averaged velocityweighted suspended-sand concentration, an error potentially 8 

to 20 times larger than in the first case.

As illustrated by these two cases, an instantaneous vertical profile (similar to that sampled by a depth-integrating 

sampler) may differ considerably from a time-averaged profile 

of suspended-sediment concentration. To further illustrate this 

point, substituting the time-averaged and fluctuating-component terms from equation 4 into equation 7 yields

 . (8)

Here, for the second assumption to hold (that is, for the 

net error associated with any EDI or EWI measurement to 

be dominated by the quasi-systematic error evaluated by 

P.R. Jordan [Guy and Norman, 1970; Edwards and Glysson, 1999]), uC m

dz

dt





 



 dt >> ( ) uCm

′ dz

dt





 



 dt 0

T

∫ 0

T

∫ over 

the verticals sampled in a full EDI or EWI measurement. 

Because 

	

( ) uCm

′ fluctuates about zero over time, repeated 

sequential sampling of the same vertical would lead to 

( ) uCm

′ dz

dt





 



 dt 0

T

∫ << uC m

dz

dt





 



 dt 0

T

∫ by time averaging over 

progressively longer durations. However,

	

( ) uCm

′ dz

dt

	

		 			dt 0

T

∫

may not be substantially smaller than uC m

dz

dt





 



 dt 0

T

∫ when all 

elevations in a vertical are sampled only once (during one-way 

depth integration) or twice (during standard two-way depth 

integration). 

CmDI = uC m

dz

dt





 



 dt + ( ) uCm

′ dz

dt





 



 dt 0

T

∫ 0

T

∫





 



 u 0

T

∫ dz

dt





 



 dt
Introduction 9

Generally, there is no reason to assume identical 

sediment-transport conditions at different verticals in a cross 

section, especially in cross sections with complex bed topography or irregular distributions of sand and gravel on the 

bed. The more complex the cross section, the more verticals 

that are required to obtain an EDI or EWI measurement with 

an acceptably low error arising from inadequate sampling of 

the cross-stream spatial structure in suspended-sediment concentration, as determined by P.R. Jordan’s 1968 analysis as 

presented by Guy and Norman (1970) and Edwards and Glysson (1999). Thus, the standard procedure in conducting either 

an EDI or an EWI measurement is to collect depth-integrated 

data at the minimum number of verticals (each with potentially different sediment-transport conditions) to sample the 

cross-stream spatial structure in the time-averaged velocityweighted suspended-sediment concentration at an acceptable 

level of error. No previous work has been done to evaluate 

the relative magnitudes of this “spatial structure” error and 

the random error arising from the minimal time averaging 

that occurs during standard deployment of depth-integrating 

samplers in an EDI or EWI measurement, nor to determine 

whether the “time averaging” error is reduced as additional 

verticals are sampled or whether additional transits at each 

vertical are required to reduce this error to an acceptably low 

level. The only guaranteed way to reduce a random error is 

to conduct repeated measurements under the same conditions 

(for example, Taylor, 1997; Bevington and Robinson, 2003). 

In the case of an EDI or EWI measurement, reduction of the 

random “time averaging” error could require repeated depthintegrated measurements at each of the verticals sampled (that 

is, adding transits at each vertical). Repeated measurements at 

the same vertical would result in a reduction of the standard 

error of the mean velocity-weighted concentration at each 

vertical, and if these repeated measurements are uncorrelated 

(by not being collected too closely spaced in time), this error 

would decrease as 

	

1 n , where n is the number of repeated 

depth-integrated measurements at each vertical. Additionally, reduction in the “time averaging” error is also possible 

as additional verticals are sampled. The rate at which adding verticals reduces this random error likely depends on the 

spatial and temporal correlations between adjacent verticals. 

This study will therefore evaluate (1) the relative magnitudes 

of “spatial structure” and “time averaging” errors, (2) whether 

the greatest decrease in the “time averaging” error occurs as 

transits or verticals are added to an EDI or EWI measurement, 

and (3) the behavior of the total uncertainty (composed of 

these two errors) in an EDI or EWI measurement as transits 

and (or) verticals are added. 

Figure 3. Time-averaged sand flux uCsand , absolute value of the fluctuating component of the sand flux ( ) uCsand

′ , and minimum and 

maximum sand flux measured using a P-61 point-integrating suspended-sediment sampler at (A) the Grand Canyon gaging station (figs. 

1, 2B) at six elevations above bed at the vertical located at the station 190 ft from the right endpoint of the measurement cableway on 

March 28, 1996, and at (B) the Cisco gaging station (figs. 1, 2A) at seven elevations above bed at the vertical located at the station 385 

ft from the left-bank bridge abutment on May 10, 1995. Nondimensionalized elevation above bed is calculated by dividing measured 

elevation of each sample above bed by mean water depth at vertical. Values of uCsand at the Grand Canyon gaging station were 

calculated using three individual point samples, and those at the Cisco gaging station were calculated using five to six individual point 

samples, at each elevation. 

0.0001 0.001 0.01 0.1 1 10

0.0

0.2

0.4

0.6

0.8

1.0

uCsand

|(uCsand )'|

minimum uCsand

maximum uCsand 

0.0001 0.001 0.01 0.1 1 10

0.0

0.2

0.4

0.6

0.8

1.0

SAND FLUX, IN GRAMS PER SQUARE CENTIMETER PER SECOND

NONDIMENSIONAL ELEVATION ABOVE BED

A B
10 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Data 

To evaluate the error arising from depth-integrating samplers collecting minimally time-averaged data, we collected 

suspended-sediment samples by using a P-61 point-integrating 

suspended-sediment sampler and D-96-A1 and D-77 bag-type 

depth-integrating suspended-sediment samplers. The P-61 

suspended-sediment sampler is described by Edwards and 

Glysson (1999), the D-96-A1 suspended-sediment sampler is 

described by the Federal Interagency Sedimentation Project 

(2003), and the D-77 bag-type suspended-sediment sampler is 

described by Szalona (1982). The P-61 sampler was operated in both point-integrating and one-way depth-integrating 

modes, and the D-96-A1 and D-77 bag-type samplers were 

operated in the standard two-way depth-integrating mode. 

Data were collected by using a P-61 suspendedsediment sampler between 1995 and 2006. P-61 point data 

were collected from the Dewey Bridge near the Cisco gaging station (figs. 1, 2A) during May 10–12, 1995, at water 

discharges ranging from 342 to 374 m3

/s. Additional P-61 

depth-integrated data were collected at this site on May 

13–14, 1995, at water discharges ranging from 464 to 504 

m3/s. P-61 point and depth-integrated data were collected 

from the measurement cableway at the Grand Canyon gaging station (figs. 1, 2B) on March 28, March 30, and April 

2, 1996, at a steady water discharge of 1,280 m3/s, and on 

September 26, 1998, at a water discharge of ~589 m3/s. 

Additional P-61 depth-integrated data were collected at this 

site on March 27, March 29, March 31, and April 1, 1996, at 

a steady water discharge of 1,280 m3/s and on April 3, 1996, 

at a water discharge of ~905 m3/s. P-61 point and depth-integrated data were collected from the measurement cableway 

at the Lower Marble Canyon gaging station (figs. 1, 2C) 

on September 22, 1998, at a water discharge of ~550 m3/s. 

Additional P-61 point data were collected at the former location of the measurement cableway on February 8, 2006, at a 

water discharge of ~376 m3/s and on August 11, 2006, at a 

water discharge of ~474 m3/s. P-61 point data were collected 

under a tagline along cross section B at the River-mile 30 

sediment station (figs 1, 2D) on February 5, 2006, at a water 

discharge of ~345 m3

/s and on August 7, 2006, at a water 

discharge of ~300 m3/s. The mean discharge of water, depthand time-averaged suspended-silt-and-clay concentration, 

and depth- and time-averaged suspended-sand concentration 

during the collection of the point samples at each vertical at 

these four study sites are listed in table 1.

In addition to the P-61 data, suspended-sediment data 

were also collected by using depth-integrating samplers. 

Single-vertical D-96-A1 depth-integrated data were collected 

under a tagline along cross section B at the River-mile 30 sediment station (XS B, fig. 2D) on August 25, 2007 (at a water 

discharge of 309 m3

/s), under a tagline along cross section C 

at the Lower Marble Canyon gaging station (XS C, fig. 2C) 

on August 30, 2007 (at a water discharge of 482 m3/s), and 

from the measurement cableway at the Grand Canyon gaging 

station (fig. 2B) on August 31, 2007 (at a water discharge 

of 481 m3

/s). Noncomposited5 nine-vertical EWI data were 

collected by using D-96-A1 and D-77 bag-type suspendedsediment samplers along cross sections A and B at the Rivermile 30 sediment station (XS A, XS B, fig. 2D) on February 

24 and 25, 2007, at water discharges ranging from ~261 to 

294 m3/s, and on August 24 and 25, 2007, at water discharges 

ranging from ~276 to 364 m3/s. Noncomposited nine-vertical 

EWI data were collected by using D-96-A1 and D-77 bag-type 

suspended-sediment samplers along cross sections A, B, and C 

at the Lower Marble Canyon gaging station (XS A, XS B, XS 

C, fig. 2C) on February 27 and 28, 2007, at water discharges 

ranging from ~297 to 357 m3/s, and on August 28 and 29, 

2007, at water discharges ranging from ~376 to 469 m3/s. The 

two different types of depth-integrating samplers were used 

in this data-collection program to meet the needs of another 

study investigating systematic differences in measurements 

of suspended-sediment concentration and grain size made 

using D-77 bag-type and D-96-A1 depth-integrating samplers. Removal of biases in the measurements of suspendedsediment concentration made using the D-77 bag-type sampler 

(described below) was thus required before the D-77 bag-type 

sampler data could be used in this study.

The details (that is, time, flow depth, sample depth, 

sample duration, intake velocity, sediment concentration, and 

grain-size distribution) associated with all the suspendedsediment samples described and analyzed in this report are 

presented in appendix A. For each sample, the point or depthintegrated intake velocity was calculated by using the sample 

duration, sampled water volume, and nozzle diameter.

The point-sample data-collection program was designed 

to allow an estimation of the error associated with no time 

averaging in the flux of each size class of suspended sediment. 

This error was estimated on the basis of multiple sequential 

(back-to-back) point suspended-sediment samples collected at 

various elevations above the bed. The sampling protocol was 

such that a complete set of back-to-back point samples were 

collected at one elevation before moving to the next elevation 

in the flow. These samples were collected at each elevation 

over the shortest time scale required to obtain a sample large 

enough to be analyzed in the laboratory (ranging from 5 to 49 

seconds), and so some minimal time averaging occurred during 

sample collection. Errors in flux arising from collecting nontime-averaged data could thus be calculated by comparing the 

minimally time-averaged data from individual samples with the 

time-averaged data from the entire set of sequential samples at 

each elevation. Because these samples were collected at different sites and under different flow conditions, this point-sample 

data-collection program also allowed an evaluation of the 

dependence of these errors on flow conditions. 

On each of the 3 days at the Cisco gaging station 

(fig. 1), sequential point samples were collected at various elevations at individual verticals (fig. 2A). The sampled 

vertical was located on May 10 at the station marked 385 ft 

5

 That is, the samples collected at each vertical in the cross section were 

processed separately in the laboratory.
Data 11

from the left-bank bridge abutment, on May 11 at the station 

marked 411 ft from the left-bank bridge abutment, and on 

May 12 at the station marked 340 ft from the left-bank bridge 

abutment. The left and right edges of water were located at the 

stations marked 246 and 480 ft, respectively, from the leftbank bridge abutment. On May 10, five to six sequential point 

samples were collected at seven elevations above the bed; 

each point sample was collected for 16 seconds and each set of 

sequential point samples at each elevation required an average 

of 16 minutes to complete. On May 11, four to seven sequential point samples were collected at nine elevations above the 

bed; each point sample was collected for 14 to 23 seconds 

(most were collected for 16 seconds), and each set of sequential point samples at each elevation required an average of 13 

minutes to complete. On May 12, five to eight sequential point 

samples were collected at six elevations above the bed; each 

point sample was collected for 12 to 20 seconds (depending 

on height above the bed, with sampling time consistent at each 

elevation), and each set of sequential point samples at each 

elevation required an average of 12 minutes to complete. 

At the Grand Canyon gaging station (fig. 1), three 

sequential point samples were collected on March 28 and 30, 

1996, April 2, 1996, and September 26, 1998, at six elevations at each of two verticals (fig. 2B) located at approximately 

one-third and two-thirds of the channel width at the stations 

marked 190 and 290 ft from the right-bank end point of the 

cableway (fig. 2B). In 1996, each point sample was collected 

for 5 to 15 seconds (depending on height above the bed, with 

sampling time consistent at each elevation) and each set of 

three sequential point samples at each of the six elevations 

required an average of 6 minutes to complete; in 1998, each 

point sample was collected for 12 to 20 seconds and each set 

of three sequential point samples at each of the six elevations 

also required an average of 6 minutes to complete. 

At the Lower Marble Canyon gaging station (fig. 1), 

three sequential point samples were collected on September 

22, 1998, at six elevations at each of two verticals located at 

approximately one-third and two-thirds of the channel width 

at the stations marked 180 and 280 ft from the right-bank end 

point of the cableway; each point sample was collected for 8 

to 20 seconds and each set of three sequential point samples at 

each of the six elevations required an average of 7 minutes to 

complete. On February 8, 2006, three sequential point samples 

were collected at four elevations at a vertical located 165 ft 

from the former right-bank end point of the cableway, and 

three sequential point samples were collected at five elevations 

at a vertical located 295 ft from the former right-bank end 

point of the cableway; each point sample was collected for 25 

to 43 seconds and each set of three sequential point samples at 

each of the six elevations required an average of 6 minutes to 

complete. On August 11, 2006, three sequential point samples 

were collected at four elevations at these two verticals; each 

Table 1. Flow and sediment-supply conditions during collection of point suspended-sediment samples at the Cisco, Grand Canyon 

(GC), and Lower Marble Canyon (LMC) gaging stations and the River-mile 30 (RM30) sediment station.

Flow and sediment-supply 

conditions

Study site, month-day, year, and station of vertical

Cisco

5-10

1995

385 ft

Cisco

5-11

1995

411 ft

Cisco

5-12

1995

340 ft

GC

3-28

1996

190 ft

GC

3-28

1996

290 ft

GC

3-30

1996

190 ft

GC

3-30

1996

290 ft

GC

4-2

1996

190 ft

GC

4-2

1996

290 ft

GC

9-26

1998

190 ft

GC

9-26

1998

290 ft

Mean discharge of water 

(m3

/s) 351 342 374 1,280 1,280 1,280 1,280 1,280 1,280 583 595

Mean silt and clay concentration 

(mg/L) 618 458 525 358 363 206 211 260 176 160 179

Mean sand concentration 

(mg/L) 1,230 243 406 2,260 1,940 1,390 1,690 1,380 1,460 154 230

Flow and sediment-supply 

conditions

Study site, month-day, year, and station of vertical

LMC

9-22

1998

180 ft

LMC

9-22

1998

280 ft

LMC

2-8

2006

165 ft

LMC

2-8

2006

295 ft

LMC

8-11

2006

165 ft

LMC

8-11

2006

295 ft

RM30

2-5

2006

92 ft

RM30

2-5

2006

188 ft

RM30

8-7

2006

92 ft

RM30

8-7

2006

188 ft

Mean discharge of water 

(m3/s) 563 533 372 380 469 479 353 337 304 296

Mean silt and clay concentration 

(mg/L) 232 241 17.1 13.7 50.1 46.9 15.5 12.7 16.5 16.1

Mean sand concentration 

(mg/L) 211 156 36.1 21.7 94.0 86.2 19.3 19.2 19.8 21.0
12 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

point sample was collected for 20 to 30 seconds and each set 

of three sequential point samples at each of the six elevations 

required an average of 6 minutes to complete.

At the River-mile 30 sediment station (fig. 1), three 

sequential point samples were collected on February 5, 2006, 

at five elevations at each of two verticals located at approximately one-third and two-thirds of the channel width at the 

stations marked 92 and 188 ft from the left-bank endpoint 

of the tagline; each point sample was collected for 25 to 49 

seconds and each set of three sequential point samples at each 

of the six elevations required an average of 7 minutes to complete. On August 8, 2006, three sequential point samples were 

collected at five elevations at each of these two verticals; each 

point sample was collected for 40 to 46 seconds, and each set 

of three sequential point samples at each of the six elevations 

required an average of 8 minutes to complete. 

The at-a-point values of 

	

uCm and 

	

( ) uCm

′

 measured during each period at the Cisco, Grand Canyon, and Lower Marble 

Canyon gaging stations and at the River-mile 30 sediment 

station (fig. 1) were therefore averaged over 5 to 49 seconds, 

the time required to collect each point sample; and the at-apoint values of 

	

uCm were averaged over 6 to 16 minutes, the 

time required to collect each set of sequential point samples 

at a given elevation. Thus, the values of 

	

uCm are likely time 

averaged over time scales longer than most of the turbulent 

fluctuations, and the values of 

	

uCm and 

	

( ) uCm

′

 are minimally 

time averaged over time scales less than most of the turbulent 

fluctuations. As mentioned previously, because a short, but 

finite, amount of time is required to collect a point sample 

containing amounts of water and suspended sediment sufficient for laboratory analysis, the amplitudes of fluctuations in 

the fluxes are damped. Therefore, errors calculated from these 

point-sample data likely are somewhat smaller than the errors 

that would be calculated if true instantaneous fluxes could 

actually be measured.

The depth-integrated-sample data-collection program was 

designed to allow (1) comparison of the errors calculated from 

non-time-averaged depth-integrated data with those computed from the minimally time-averaged point-sample data 

described above; (2) evaluation of the errors associated with 

different durations of time averaging on the depth-integrated 

velocity-weighted concentration of each size class of suspended sediment; (3) evaluations of the temporal correlations 

at individual verticals in EWI measurements spaced hours 

apart and of the spatial correlations between adjacent verticals 

in the same EWI measurement; and (4) comparison of P.R. 

Jordan’s “spatial structure” error, the “time averaging” error, 

and the total uncertainty (composed of these two errors) when 

different numbers of transits and verticals are present in an 

EWI measurement. The first objective was accomplished by 

collecting one-way (upward) depth-integrated suspended-sediment samples bracketing point samples; the second objective 

was accomplished by comparing the errors calculated from 

the single-vertical collection of sequential (back-to-back) 

one-way depth-integrated suspended-sediment samples (no 

time averaging) and sequential two-way depth-integrated 

suspended-sediment samples (minimal time averaging); the 

third objective was accomplished by collecting noncomposited 

EWI data over two multiday periods at multiple cross sections; 

and the fourth objective was accomplished by comparing the 

data collected to address objectives 2 and 3.

One-way depth-integrated samples were collected 

before and after each complete set of 18 point samples (that 

is, bracketing the point samples) at the Grand Canyon gaging 

station (fig. 2B) in 1996 and 1998 and at the Lower Marble 

Canyon gaging station (fig. 2C) in 1998. These one-way depthintegrated samples were collected with a P-61 sampler by 

opening the nozzle above the bed and then raising the sampler 

to the surface at a uniform transit rate. Collection of these 

samples allowed a direct comparison of the errors estimated 

for non-time-averaged depth-integrated data with the errors 

estimated for point-sample data collected at the same vertical. 

At the Grand Canyon gaging station, these bracketing one-way 

depth-integrated samples were collected over 6 to 8 seconds 

in 1996 and over 10 to 19 seconds in 1998; in both years, the 

samples were spaced ~1 hour apart (the time required to collect 

the 18 point samples). At the Lower Marble Canyon gaging 

station, these bracketing one-way depth-integrated samples 

were collected over 11 to 17 seconds and also spaced ~1 hour 

apart. Additional one-way, upward depth-integrated samples 

(see appendix A) were also collected as part of this study at 

the Grand Canyon gaging station on March 27, 29, and 31 and 

April 1 and 3, 1996, and on September 26, 1998.

Sequential one-way, upward depth-integrated samples 

were collected with a P-61 sampler at the Cisco gaging station 

(fig. 2A) in 1995. On May 13, 1995, four sets of five sequential 

samples were collected at the vertical located at the station 

340 ft from the left-bank bridge abutment; and on May 14, 

1995, three sets of five sequential samples were collected at the 

vertical located at the station 403 ft from the left-bank bridge 

abutment. Each depth-integrated sample was collected for 10 

to 13 seconds, and the samples within each set were spaced ~2 

minutes apart. 

In 2007, sequential single-vertical two-way depthintegrated samples were collected with a D-96-A1 sampler at 

the River-mile 30 sediment station and at the Lower Marble 

Canyon and Grand Canyon gaging stations (fig. 1). On August 

25, 2007, 15 sequential depth-integrated samples were collected at the River-mile 30 sediment station in the middle of the 

river, at the vertical located at the station 138 ft from the leftbank end point of the tagline; each sample was collected for 

64 to 68 seconds, and the samples within each set were spaced 

~4 minutes apart. On August 30, 2007, 15 sequential depthintegrated samples were collected at the Lower Marble Canyon 

gaging station in the middle of the river, at the vertical located 

at the station 230 ft from the former right-bank end point of the 

cableway; each sample was collected for 33 to 35 seconds, and 

the samples within each set were spaced ~3 minutes apart. On 

August 31, 2007, 14 sequential depth-integrated samples were 

collected at the Grand Canyon gaging station in the middle 

of the river, at the vertical located at the station 258 ft from 

the right-bank end point of the cableway; each sample was 
Data 13

collected for 37 to 40 seconds, and the samples within each set 

were spaced ~2 minutes apart. 

In February and August 2007, noncomposited multitransit, 

multivertical data were collected with D-96-A1 and D-77 bagtype samplers along two cross sections (XS A and XS B, fig. 

2D) at the River-mile 30 sediment station and along three cross 

sections (XS A, XS B, and XS C, fig. 2C) at the Lower Marble 

Canyon gaging station. To accomplish objectives 3 and 4 of the 

depth-integrated-sample data-collection program, it was desirable to collect noncomposited EWI data that could be analyzed 

by using as many different numbers of verticals as possible. 

On the basis of P.R. Jordan’s analysis (Guy and Norman, 1970; 

Edwards and Glysson, 1999), five equal-width increments are 

reasonably sufficient to sample the cross-stream spatial structure 

in suspended-sand concentration in a simple trapezoidal channel 

like the Colorado River. For convenience in the analyses, it was 

preferable to design a sampling program that would allow new 

verticals to be added while keeping the positions of the verticals in the middle of these original five equal-width increments 

fixed. However, the EWI measurement with the next-highest 

cross-stream spatial resolution that keeps the positions of the 

original five verticals fixed is one composed of 15 equal-width 

increments (fig. 4), which would require adding two new verticals between each of the original five verticals and adding one 

vertical between each bank and the first and last of the original 

five verticals (with these two verticals located very close to 

the banks). This addition of 10 new verticals was impractical 

in the field for several reasons (for example, the length of time 

required to collect 15 noncomposited verticals, the large volume 

of water that would have to be collected in a 15-vertical measurement, and the shallow flow depths and extremely low velocities at the new near-bank verticals that would make deployment of depth-integrating samplers difficult). As a compromise 

design, one new vertical was added between each of the original 

five verticals, resulting in the ability to compare the five-vertical 

EWI measurement with nine- and three-vertical quasi-EWI 

measurements (figs. 4C–D). The spacing between verticals in 

the nine-vertical measurements approximately equaled the mean 

flow depth in each cross section, resulting in only two small 

triangular regions near the banks in the three- and nine-vertical 

quasi-EWI measurements that were “ignored.” Ultimately, EWI 

measurements composed of one, three, five, and nine verticals 

were compared under this sampling design.

To allow mathematical compositing6

 of the multivertical 

data as EWI measurements with different numbers of verticals, 

the sampler transit rate was held constant among the verticals 

in each cross section. The sampler transit rate in each cross 

section was highly constrained on the basis of conditions at the 

verticals near the middle of the cross section, where velocities 

and flow depths were largest, and conditions near the sides of 

the cross section, where velocities and flow depths were smallest. That is, the transit rate for the cross section had to be set 

at a rate fast enough so that the sampler did not overfill upon 

6

 These EWI measurements were mathematically composited by using the 

raw laboratory sample masses, sediment masses, and grain-size distributions.

two transits (one downward and one upward) at the verticals 

in the middle of the cross section, and slow enough that it did 

not exceed ~40 percent of the flow velocity (to avoid large 

entrance angles between the direction of flow and the nozzle; 

see Federal Interagency Sedimentation Project, 1952; Edwards 

and Glysson, 1999) at the verticals near the sides of the cross 

section. Because flow depths and velocities were small in the 

“ignored regions” adjacent to the banks in figures 4C–D, not 

sampling these regions had a negligible effect on the threeand nine-vertical quasi-EWI measurements. 

On February 24, 2007, noncomposited nine-vertical 

data were collected under this sampling design with the 

D-77 bag-type sampler at cross sections A and B and with 

the D-96-A1 sampler at cross section A at the River-mile 30 

Figure 4. Trapezoidal cross sections showing edges (green dashed 

lines) of equal-width increments and positions of verticals (arrows) 

in different equal-width-increment (EWI) sampling designs. Water 

surface in each cross section indicated by thin blue line. A, Fivevertical EWI measurement. Circled number 1 denotes position of 

vertical in center of cross section used to construct a one-vertical 

EWI measurement. B, 15-vertical EWI measurement. Black arrows 

denote positions of original five verticals in figure 4A; red arrows 

denote positions of added verticals. C, Nine-vertical quasi-EWI 

measurement. Black arrows denote positions of original five 

verticals in figure 4A; red arrows denote positions of added verticals. 

Note presence of two triangular “ignored regions” adjacent to 

the banks in this compromise sampling design. D, Three-vertical 

quasi-EWI measurement. Black and red arrows denote positions 

of three of nine verticals in figure 4C retained in construction of 

this measurement. Ignored regions adjacent to the banks in this 

compromise sampling design are the same as in figure 4C.

A

B

C

IGNORED

 REGION

IGNORED

 REGION

1

D

IGNORED

 REGION

IGNORED

 REGION
14 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

distributions of the material retained on the 0.0625-mm 

sieve were measured at 1⁄4-f increments by using a Beckman 

Coulter LS-100Q Laser Diffraction Particle Size Analyzer 

calibrated to give results identical to those obtained by dry 

sieving. Wet-sieving results in some silt and clay adhering to 

the sand retained on the 0.0625-mm sieve. This effect, which 

has been observed by using electron microscopy (Gordon and 

others, 2001), was observed in our laboratory by comparing 

the results from wet and dry sieving. In this study, the amount 

of silt and clay retained with the sand during wet sieving was 

measured by using either the visual accumulation tube or 

the LS-100Q Laser Diffraction Particle Size Analyzer. The 

suspended-silt-and-clay concentrations reported in appendix A 

were calculated by adding the weight of silt and clay retained 

on the 0.0625-mm sieve during the wet-sieving process to the 

weight of sediment passing through this sieve. Likewise, the 

suspended-sand concentrations reported in appendix A were 

calculated by subtracting the weight of silt and clay retained 

on the 0.0625-mm sieve from the weight of material retained 

on this sieve. This approach removes the negative bias in 

suspended-silt-and-clay concentration and the positive bias in 

suspended-sand concentration observed by Gordon and others 

(2001). Owing to the type of the analyses in this study (that 

use field data processed through a laboratory), laboratoryprocessing errors (typically well within 5 percent) are embedded within the errors calculated in the analyses presented here. 

These laboratory-processing errors are likely random and of 

similar small magnitude (that is, generally much less than 

about ±5 percent) and so are assumed to cancel out within 

each of the analyses conducted in this study.

Analysis

At-a-Point Error

Before quantifying the error associated with assuming that 

uC m

dz

dt





 



 dt >> ( ) uCm

′ dz

dt





 



 dt 0

T

∫ 0

T

∫ over either a singlevertical, EDI, or EWI measurement, the relative mean absolute 

error (that is, relative mean unsigned error) arising from this 

assumption must first be calculated at each point in each 

vertical. This random error in sediment flux, herein termed the 

at-a-point error (APE, in percent), is defined as

 APE = 100 u Cm

m =1

M

∑ - u Cm

m =1

M

∑ u Cm

m =1

M

∑ , (9)

which simplifies for each size class m to 

 APE = 100 ( ) uCm

′ uCm , (10) 

where 

	

( ) uCm

′ is the time-averaged absolute value of the 

fluctuating component of the flux of suspended sediment in 

size class m at a given elevation above the bed and uCm is 

sediment station (fig. 2D). On February 25, 2007, noncomposited nine-vertical data were collected with the D-96-A1 sampler 

at cross section B at the River-mile 30 sediment station. During 

the afternoon of August 24, 2007, and again during the morning of August 25, 2007, noncomposited nine-vertical data were 

collected with both the D-77 bag-type and D-96-A1 samplers 

at the two cross sections at the River-mile 30 sediment station. 

On February 27, 2007, noncomposited nine-vertical data were 

collected with the D-96-A1 sampler, and on February 28, 2007, 

noncomposited nine-vertical data were collected with the D-77 

bag-type sampler, at cross sections A, B, and C at the Lower 

Marble Canyon gaging station (fig. 2C). On August 28, 2007, 

and again on August 29, 2007, noncomposited nine-vertical 

data were collected with both the D-77 bag-type and D-96-A1 

samplers at the three cross sections at the Lower Marble Canyon 

gaging station. Samplers with 5

⁄16-in. nozzles were used during 

February 2007 and with 1⁄4-in. nozzles during August 2007. From 

two to eight transits were collected at each vertical. Depending 

on the nozzle diameter, number of transits, flow velocity, and 

flow depth, the depth-integrated sample at each vertical was 

collected over durations between 1 and 8 minutes; and depending on the conditions at each cross section, each noncomposited 

nine-vertical measurement took 17 to 94 minutes to complete. 

Recent measurements at multiple sites along the Colorado River in Grand Canyon (fig. 1) indicate that relative to 

the D-96-A1 sampler, the D-77 bag-type sampler on average 

oversamples suspended silt and clay by ~5 percent and suspended sand by ~20 percent (Sabol and others, 2010) because 

the D-77 bag-type sampler is not as isokinetic as the D-96-A1 

sampler and samples at a rate slightly lower than the instantaneous flow velocity.7

 The noncomposited nine-vertical EWI 

data were therefore processed in such a way as to prevent this 

D-77 bag-type sampler bias from affecting the analyses in this 

report. This result was achieved by normalizing the concentrations of suspended silt and clay or sand measured at each individual vertical in an EWI measurement by the mean concentration of suspended silt and clay or sand measured among the 

nine verticals in that EWI measurement. In this way, the biases 

between data collected with the D-77 bag-type and D-96-A1 

samplers were removed, and the noncomposited EWI data 

collected using the two depth-integrating suspended-sediment 

samplers could be directly compared. 

All the data collected in this study were processed for suspended-sediment concentration by using standard USGS methods, with sand-size material separated from silt- and clay-sized 

material by wet sieving through a 0.0625-mm stainless-steel 

sieve (Guy, 1969; Knott and others, 1992, 1993). For the 1996 

and 1998 data, grain-size distributions of the material retained 

on this sieve were measured at 1⁄4-f increments by using a 

visual accumulation tube (Federal Interagency Sedimentation 

Project, 1957, 1958) calibrated to give results identical to those 

obtained by dry sieving. For the 2006 and 2007 data, grain-size 

7

 See Federal Interagency Sedimentation Project (1941) for analyses of the 

effect of non-isokinetic sampling on measurements of suspended-sediment 

concentration for various size classes of sediment.
Analysis 15

the time-averaged flux of suspended sediment in size class m

at that same elevation. Statistical analyses were conducted on 

the 1995 Cisco, 1996 and 1998 Grand Canyon, 1998 and 2006 

Lower Marble Canyon, and 2006 River-mile 30 P-61 pointsample data to evaluate whether the APE depends on either 

elevation above the bed or grain size. APEs calculated from 

these point-sample data are plotted in figure 5. As previously 

noted, because a finite amount of time is required to collect point suspended-sediment samples, the APEs calculated 

from these point-sample data are not true instantaneous errors 

(for example, the type of error expected in a one-way depthintegrated sample with zero time averaging) and so likely are 

somewhat smaller than the errors that would be calculated if 

true instantaneous fluxes were measurable. 

The APE in each size class of sediment does not systematically depend on elevation above the bed. In some places, 

the point samples collected closest to the bed exhibited the 

largest values of this error, for example, at the Cisco vertical 

at station 385 ft on May 10, 1995, and at the Grand Canyon 

vertical at station 190 ft on March 28, 1996; in other places, 

the point samples collected near the surface exhibited the 

largest values of this error, for example, at the Cisco vertical 

at station 340 ft on May 12, 1995, and at the Grand Canyon 

vertical at station 290 ft on September 26, 1998. Analysis of 

variance using a standard F-test indicates that in 84.4 percent 

of the 301 cases for which data were available to calculate 

this error, no significant relation existed at the p=0.05 level 

between the elevation above the bed and the APE in each 

size class (table2). In only 14.3 percent of cases the APE 

increased, and in just 1.3 percent of the cases decreased, with 

distance above the bed. Although the APE does not systematically depend on elevation above the bed, it does ordinarily 

depend on grain size. Analysis of variance using a standard 

F-test indicates that at the p=0.05 level of significance, the 

APE was positively correlated with grain size in 84.7 percent 

of the 118 cases for which data were available to calculate 

this error (table 3). No significant relation between grain size 

and APE was observed in the remaining 15.3 percent of these 

118 cases. In no case was the APE negatively correlated with 

grain size. 

Similarity in the behavior of the APE at different elevations above the bed and at different verticals under similar 

flow conditions allows for some simplification. Because the 

APE does not systematically depend on elevation above the 

bed but does depend on grain size, the APEs in each size 

class can therefore be depth-averaged (among all sampled 

elevations above the bed) to result in a mean APE, hereafter 

referred to as the mean at-a-point error (MAPE). This depth 

averaging effectively reduces the number of datasets from 

121 (that is, the total number of sampled elevations in all 

verticals) to 21 (that is, the total number of verticals sampled 

at the four study sites). Furthermore, because of the similar 

behavior of the APE at each of the verticals sampled under 

similar flow conditions, the MAPEs associated with similar 

flow conditions at each of the study sites were combined, 

this further reducing the number of datasets from 21 to 5: (1) 

the 1995 Cisco gaging-station dataset (with water discharge 

ranging from 342 to 374 m3

/s), (2) the 1996 Grand Canyon 

gaging-station dataset (with a steady water discharge of 

1,280 m3

/s), (3) the 1998 Grand Canyon gaging-station dataset (with water discharge ranging from 583 to 595 m3

/s), (4) 

the 1998–2006 Lower Marble Canyon gaging-station dataset 

(with water discharge ranging from 372 to 563 m3

/s), and (5) 

the 2006 River-mile 30 sediment-station dataset (with water 

discharge ranging from 296 to 353 m3

/s).

The combined MAPEs at the four study sites, which 

are similar in magnitude and behavior (fig. 6; table 4), were 

calculated from the APEs at all elevations in all verticals 

except at the Grand Canyon gaging station (fig. 1), where 

the combined MAPEs for 1996 and 1998 data were computed separately because of the relatively large difference 

in flow conditions between these two datasets. The average of the combined MAPEs for silt and clay among the 

five datasets is 10±2 percent (mean ±1 standard error). For 

sand-size material, the average of the combined MAPEs 

among the five datasets is the smallest at 15±3 percent for 

the 0.105- to 0.125-mm size class (generally the median size 

of suspended sand in the Colorado River in Grand Canyon). 

For the size classes that typically dominate suspended sand 

in the Colorado River in Grand Canyon (that is, the size 

classes between 0.088 and 0.177 mm), the average of the 

combined MAPEs among the five datasets ranges from ~15 

to 20 percent, whereas for the coarser size classes of sand, 

the average of the combined MAPEs among the five datasets 

exceeds 100 percent.

Effect of Changing Flow Conditions on the 

Mean At-a-Point Error

In addition to the general positive correlation between 

grain size and combined MAPEs, the combined MAPEs in each 

size class of sand tend to be negatively correlated with flow 

conditions, likely as a result of the reduction in the z-direction 

gradient in the concentration of suspended sediment of each size 

class as the flow strength increases. An increase in the discharge of water through a cross section or in the flow strength 

at any given vertical in a cross section will generally result in 

an increase in the boundary shear stress,  b , and therefore an 

increase in the shear velocity, u

* (because u

* =  b ). This 

increase, in turn, will result in a decrease in the z-direction 

gradient (away from the bed) in the concentration of suspended 

sediment in each size class, through a reduction in the Rouse 

number (for example, McLean, 1992). By standard convention, 

the Rouse number is defined as pm = wm ku* , where wm is the 

settling velocity for each size class m and k is von Karman’s 

constant, equal to 0.408 (Long and others, 1993). Vertical mixing (arising from turbulent velocity fluctuations or boils being 

shed from dunes on the bed) across larger z-direction concentration gradients gives rise to greater temporal variation in 

suspended-sediment concentration through relatively infrequent 

larger events transporting coarser grains higher into the flow 
16 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure 5. At-a-point error (APE) in flux of each size class of suspended sediment at six to nine elevations above the bed at the Dewey 

Bridge near the Cisco gaging station (figs. 1, 2A) at vertical located at station 385 ft on May 10, 1995 (A), at station 411 ft on May 11, 1995 

(B), at station 340 ft on May, 12, 1995 (C); at six elevations above the bed along measurement cableway at the Grand Canyon gaging 

station (fig. 2B) at vertical located at station 190 ft on March 28, 1996 (D), at station 290 ft on March 28, 1996 (E), at station 190 ft on March 

30, 1996 (F ), at station 290 ft on March 30, 1996 (G), at station 190 ft on April 2, 1996 (H), at station 290 ft on April 2, 1996 (I), at station 190 

ft on September 26, 1998 (J), and at station 290 ft on September 26, 1998 (K); at six elevations above the bed along former measurement 

cableway at the Lower Marble Canyon gaging station (XS C, fig. 2C) at vertical located at station 180 ft on September 22, 1998 (L ), at 

station 280 ft on September 22, 1998 (M); at four to five elevations above the bed along tagline at cross section C at the Lower Marble 

Canyon gaging station (XS C, fig. 2C) at vertical located at station 165 ft on February 8, 2006 (N), at station 295 ft on February 8, 2006 (O), 

at station 165 ft on August 11, 2006 (P), and at station 295 ft on August 11, 2006 (Q); and at five elevations above the bed along tagline at 

cross section B at the River-mile 30 sediment station (XS B, fig. 2D) at vertical located at station 92 ft on February 5, 2006 (R), at station 188 

ft on February 5, 2006 (S), at station 92 ft on August 8, 2006 (T), and at station 188 ft on August 8, 2006 (U). ζ indicates nondimensionalized 

elevation above the bed and, as in figure 3, is calculated by dividing measured elevation of each sample above the bed by the mean water 

depth at the vertical. Numbers in parentheses next to each ζ elevation indicate its relative position above the bed (see table 3), where 

relative position 1 is closest to the bed. All silt-and-clay-sized sediment was assigned to the 0.01-mm size class; all sediment in each 1

⁄4-φ

size class of sand was assigned to the grain size at the logarithmic midpoint of each 1

⁄4-φ size class. 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.017 ζ (1)

0.065 ζ (2) 

0.11 ζ (3)

0.16 ζ (4)

0.21 ζ (5)

0.35 ζ (6)

0.54 ζ (7)

0.73 ζ (8)

0.92 ζ (9) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.016 ζ (1)

0.043 ζ (2)

0.14 ζ (3)

0.32 ζ (4)

0.61 ζ (5)

0.95 ζ (6) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.014 ζ (1)

0.090 ζ (2)

0.18 ζ (3)

0.34 ζ (4)

0.61 ζ (5)

0.96 ζ (6) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.022 ζ (1)

0.052 ζ (2)

0.11 ζ (3)

0.23 ζ (4)

0.54 ζ (5)

0.90 ζ (6) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.017 ζ (1)

0.042 ζ (2)

0.091 ζ (3)

0.14 ζ (4)

0.24 ζ (5)

0.43 ζ (6)

0.77 ζ (7) 

GRAIN SIZE, IN MILLIMETERS

APE, IN PERCENT

A B

C D

E F

0.1

1

10

100

1,000

0.01 0.10 1.00

0.064 ζ (1)

0.17 ζ (2)

0.25 ζ (3)

0.36 ζ (4)

0.60 ζ (5)

0.95 ζ (6) 
Data 17

0.1

1

10

100

1,000

0.01 0.10 1.00

0.043 ζ (1)

0.088 ζ (2)

0.18 ζ (3)

0.35 ζ (4) 

0.59 ζ (5) 

0.95 ζ (6)

GRAIN SIZE, IN MILLIMETERS

APE, IN PERCENT

G

H

I

J

K

L

0.1

1

10

100

1,000

0.01 0.10 1.00

0.038 ζ (1)

0.12 ζ (2)

0.20 ζ (3)

0.32 ζ (4) 

0.62 ζ (5)

0.95 ζ (6)

0.1

1

10

100

1,000

0.01 0.10 1.00

0.0051 ζ (1)

0.051 ζ (2)

0.16 ζ (3)

0.34 ζ (4) 

0.60 ζ (5)

0.96 ζ (6)

0.1

1

10

100

1,000

0.01 0.10 1.00

0.020 ζ (1)

0.085 ζ (2)

0.20 ζ (3)

0.40 ζ (4) 

0.63 ζ (5)

0.93 ζ (6)

0.1

1

10

100

1,000

0.01 0.10 1.00

0.032 ζ (1)

0.098 ζ (2)

0.16 ζ (3)

0.40 ζ (4) 

0.62 ζ (5)

0.95 ζ (6)

0.1

1

10

100

1,000

0.01 0.10 1.00

0.049 ζ (1)

0.097 ζ (2)

0.20 ζ (3)

0.29 ζ (4) 

0.62 ζ (5)

0.95 ζ (6)

Figure 5.—Continued
18 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

0.1

1

10

100

1,000

0.01 0.10 1.00

0.032 ζ (1) 

0.097 ζ (2)

0.19 ζ (3)

0.38 ζ (4)

0.64 ζ (5)

0.93 ζ (6) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.16 ζ (1)

0.27 ζ (2)

0.38 ζ (3)

0.57 ζ (4)

0.78 ζ (5) 

GRAIN SIZE, IN MILLIMETERS

APE, IN PERCENT

M

N

O P

Q

R

0.1

1

10

100

1,000

0.01 0.10 1.00

0.090 ζ (1)

0.19 ζ (2)

0.32 ζ (3)

0.53 ζ (4) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.11 ζ (1)

0.27 ζ (2)

0.39 ζ (3)

0.50 ζ (4)

0.74 ζ (5) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.081 ζ (1)

0.23 ζ (2)

0.39 ζ (3)

0.63 ζ (4)

0.87 ζ (5)

0.1

1

10

100

1,000

0.01 0.10 1.00

0.055 ζ (1) 

0.16 ζ (2)

0.32 ζ (3)

0.52 ζ (4)

0.81 ζ (5) 

Figure 5.—Continued
Analysis 19

0.1

1

10

100

1,000

0.01 0.10 1.00

0.13 ζ (1)

0.25 ζ (2)

0.55 ζ (3) 

0.78 ζ (4)

0.88 ζ (5)

1

10

100

1,000

10,000

0.01 0.10 1.00

0.083 ζ (1) 

0.17 ζ (2)

0.35 ζ (3)

0.66 ζ (4)

0.88 ζ (5) 

0.1

1

10

100

1,000

0.01 0.10 1.00

0.060 ζ (1)

0.17 ζ (2)

0.30 ζ (3)

0.53 ζ (4) 

0.79 ζ (5) 

GRAIN SIZE, IN MILLIMETERS

APE, IN PERCENT

S

T

U

Figure 5.—Continued

(Schmeeckle and others, 1999). A reduction in the z-direction 

suspended-sediment concentration gradient in any given size 

class will therefore result in less temporal variation in the 

suspended-sediment concentration at each elevation above 

the bed and likely cause a reduction in the MAPE. 

To further evaluate the effect of flow conditions on the 

combined MAPEs in each of the five datasets, each size class 

of sediment was converted to a Rouse-number class (fig. 7; 

table 5). To compute the Rouse number for each sediment 

size class in each of the five datasets, the settling velocity 

for each 1⁄4-f size class m was calculated, using the method 

of Dietrich (1982), for sediment with a Powers index of 3.0 

and a Corey shape factor of 0.7 (typical values for Colorado 

River sediment; Topping, 1997) and a water temperature 

of 15oC (an average value close to the water temperatures 

measured during collection of suspended-sediment data at 

the three gaging stations). The mean shear velocity for each 

of the five datasets was calculated by regressing the best-fit 

velocity profiles (using the two-part eddy viscosity of Rattray 

and Mitsuda, 1974) to the intake velocities measured with 

a P-61 sampler at each elevation in each vertical, and then 

averaging the shear velocities calculated from these regressions at all the verticals in each dataset. Each regression was 

conducted such that the shear velocity and the Nikuradse 

roughness parameter, z0, were free to vary independently of 

each other until a best fit was obtained. Because z0 values 

smaller than about 0.2 cm are physically unrealistic in the 

Colorado River (Topping and others, 2007b), regressed shear 

velocities that required z0 values <0.2 cm were precluded 

during this procedure.

When all five datasets are treated as a single dataset, 

inclusion of the effects of flow conditions in this analysis 

through conversion of grain size to Rouse number results in 

a decrease of only ~11 percent in the variance of the MAPE 

about the best-fit linear regression in figure 7 relative to that 

in figure 6. Although grain size is a reasonably good predictor of MAPE, Rouse number is only slightly better. Changes 

in flow conditions, at least over the range investigated in this 

study, therefore result in only minor changes in the MAPE. 

Grain size thus dominates over all other likely influences 

on the MAPE (that is, elevation above the bed and flow 

conditions). 
20 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Table 2. Levels of statistical significance at which the at-a-point error in each size class of sediment depends on elevation above the bed. 

[Critical level of significance is set equal to 0.05; values ≤0.05 are shown in bold type; (+) indicates significant positive correlation and (–) indicates significant 

negative correlation between elevation and at-a-point error. Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower Marble Canyon gaging 

station; RM30, River-mile 30 sediment station. n/a indicates analysis not applicable because of insufficient data in size class]

Size class

(mm)

Study site, month-day, year, and station of vertical

Cisco

5-10

1995

385 ft

Cisco

5-11

1995

411 ft

Cisco

5-12

1995

340 ft

GC

3-28

1996

190 ft

GC

3-28

1996

290 ft

GC

3-30

1996

190 ft

GC

3-30

1996

290 ft

GC

4-2

1996

190 ft

GC

4-2

1996

290 ft

GC

9-26

1998

190 ft

GC

9-26

1998

290 ft

<0.0625 0.12 0.057 0.053 0.36 0.43 0.60 0.45 0.035

(+) 0.27 0.47 0.48

0.0625–0.074 0.013

(–) 0.34 0.87 0.40 0.32 0.42 0.51 0.040(+) 0.32 0.36 0.054

0.074–0.088 0.11 0.41 0.81 0.31 0.14 0.61 0.18 0.067 0.19 0.79 0.0098

(+)

0.088–0.105 0.065 0.42 0.94 0.33 0.42 0.85 0.19 0.097 0.025

(–)

0.012

(+) 0.054

0.105–0.125 0.44 0.12 0.31 0.23 0.85 0.26 0.41 0.10 0.21 0.89 0.076

0.125–0.149 0.12 0.65 0.56 0.43 0.71 0.74 0.68 0.23 0.93 0.34 0.0049

(+)

0.149–0.177 0.64 0.045

(–) 0.69 0.19 0.22 0.31 0.31 0.54 0.86 0.30 0.0017

(+)

0.177–0.210 0.25 0.078 0.014

(+)

0.020

(–) 0.57 0.94 0.79 0.14 0.25 0.094 0.0043(+)

0.210–0.250 0.84 0.35 0.0046

(+) 0.13 0.59 0.0068(+) 0.49 0.041(+) 0.62 0.045(+)

0.0021

(+)

0.250–0.297 0.72 0.51 0.026

(+) 0.20 0.97 0.15 0.072 0.063 0.36 0.031(+) 0.31

0.297–0.354 0.68 0.44 0.16 0.0057

(+)

0.0041

(+) 0.17 0.017(+) 0.25 0.84 0.092 0.049(+)

0.354–0.420 0.94 0.63 0.037 

(+) 0.32 0.0024

(+) 0.34 0.021

(+) 0.46 0.80 0.054 0.15

0.420–0.500 0.026

(+)

0.0060

(+)

0.022 

(+) 0.50 0.90 0.64 0.52 0.51 0.51 0.33 0.076

0.500–0.595 0.051 0.041 0.35 0.11 0.57 0.37 0.20 0.16 0.57 n/a 0.58

0.595–0.707 0.025

(+) n/a n/a 0.30 0.80 0.52 0.13 0.71 0.64 n/a n/a

0.707–0.841 0.64 n/a n/a n/a n/a 0.60 n/a n/a 0.39 n/a n/a

0.841–1.00 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.00–1.19 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.19–1.41 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.41–1.68 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.68–2.00 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a
Analysis 21

Table 2. Levels of statistical significance at which the at-a-point error in each size class of sediment depends on elevation above 

the bed.—Continued

[Critical level of significance is set equal to 0.05; values ≤0.05 are shown in bold type; (+) indicates significant positive correlation and (–) indicates significant negative correlation between elevation and at-a-point error. Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower Marble 

Canyon gaging station; RM30, River-mile 30 sediment station. n/a indicates analysis not applicable because of insufficient data in size class]

Size class

(mm)

Study site, month–day, year, and station of vertical

LMC

9-22

1998

180 ft

LMC

9-22

1998

280 ft

LMC

2-8

2006

165 ft

LMC

2-8

2006

295 ft

LMC

8-11

2006

165 ft

LMC

8-11

2006

295 ft

RM30

2-5

2006

92 ft

RM30

2-5

2006

188 ft

RM30

8-8

2006

92 ft

RM30

8-8

2006

188 ft

<0.0625 0.72 0.056 0.27 0.75 0.094 0.012

(+) 0.71 0.52 0.54 0.36

0.0625–0.074 0.20 0.85 0.50 0.73 0.18 0.56 0.83 0.14 0.38 0.81

0.074–0.088 0.91 0.92 0.73 0.84 0.37 0.50 0.77 0.45 0.42 0.95

0.088–0.105 0.68 0.62 0.95 0.97 0.54 0.081 0.30 0.097 0.65 0.81

0.105–0.125 0.64 0.016

(+) 0.51 0.84 0.69 0.0089(+) 0.80 0.046(+) 0.26 0.54

0.125–0.149 0.34 0.12 0.31 0.73 0.73 0.032

(+) 0.53 0.041(+) 0.14 0.73

0.149–0.177 0.0015

(+) 0.087 0.31 0.99 0.80 0.027(+) 0.99 0.51 0.59 0.74

0.177–0.210 0.10 0.053 0.60 0.16 0.73 0.018

(+) 0.13 0.26 0.93 0.54

0.210–0.250 0.17 0.017

(+) 0.90 0.83 0.75 0.0041(+) 0.56 0.23 0.93 0.17

0.250–0.297 0.011

(+) 0.057 0.70 0.33 0.90 0.036(+) 0.49 0.24 0.77 0.056

0.297–0.354 0.038

(+) 0.11 0.37 0.010(+) 0.12 0.15 0.50 0.19 0.65 0.089

0.354–0.420 0.014

(+)

0.031

(+) 0.25 0.89 0.29 0.34 0.57 0.13 n/a 0.067

0.420–0.500 0.24 0.12 0.70 0.61 0.17 0.26 0.39 0.72 n/a 0.067

0.500–0.595 n/a n/a 0.35 0.90 0.27 0.71 0.44 0.76 n/a 0.069

0.595–0.707 n/a n/a n/a n/a 0.31 n/a 0.59 n/a n/a n/a

0.707–0.841 n/a n/a n/a n/a 0.084 n/a n/a n/a n/a n/a

0.841–1.00 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.00–1.19 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.19–1.41 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.41–1.68 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

1.68–2.00 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a
22 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Table 3. Levels of statistical significance at which the at-a-point error at each elevation above the bed depends on grain size. 

[Relative positions of each sampled elevation are numbered, where position 1 is the sampled elevation closest to the bed; see figure 3 for actual elevations associated with these relative positions. Critical level of significance is set equal to 0.05; values ≤0.05 are shown in bold; (+) indicates significant positive correlation 

and (–) significant negative correlation between grain size and at-a-point error. Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower 

Marble Canyon gaging station; RM30, River-mile 30 sediment station. n/a indicates analysis not applicable because data were not collected at this relative position above the bed]

Relative 

position

above the 

bed

Study site, month-day-year, and station of vertical

Cisco

5-10-1995

385 ft

Cisco

5-11-1995

411 ft

Cisco

5-12-1995

340 ft

GC

3-28-1996

190 ft

GC

3-28-1996

290 ft

GC

3-30-1996

190 ft

GC

3-30-1996

290 ft

GC

4-2-1996

190 ft

1 0.099 0.30 0.99 0.023(+) 0.076 <0.00001(+) 0.0015(+) <0.00001(+)

2 0.55 0.0027(+) 0.050(+) <0.00001(+) 0.00010(+) <0.00001(+) 0.00043(+) 0.00001(+)

3 0.0084(+) 0.16 0.0062(+) <0.00001(+) 0.012(+) 0.0016(+) 0.0078(+) 0.080

4 0.00084(+) 0.0050(+) 0.018(+) 0.040(+) 0.0026(+) 0.0035(+) 0.021(+) <0.00001(+)

5 0.00002(+) 0.00009(+) 0.0042(+) 0.0071(+) 0.00028(+) <0.00001(+) 0.00001(+) 0.00035(+)

6 <0.00001(+) 0.0011(+) 0.00066(+) 0.00044(+) 0.00019(+) 0.00002(+) 0.00008(+) 0.00261(+)

7 0.00002(+) 0.00030(+) n/a n/a n/a n/a n/a n/a

8 n/a 0.00035(+) n/a n/a n/a n/a n/a n/a

9 n/a 0.00005(+) n/a n/a n/a n/a n/a n/a

Relative 

position

above the 

bed

Study site, month-day-year, and station of vertical

GC

4-2-1996

290 ft

GC

9-26-1998

190 ft

GC

9-26-1998

290 ft

LMC

9-22-1998

180 ft

LMC

9-22-1998

280 ft

LMC

2-8-2006

165 ft

LMC

2-8-2006

295 ft

1 0.026(+) 0.13 0.00009(+) 0.0013(+) 0.0011(+) 0.40 0.00001(+)

2 0.0023(+) 0.099 0.0066(+) 0.0013(+) <0.00001(+) 0.11 0.00003(+)

3 0.0011(+) 0.0040(+) 0.0014(+) 0.00004(+) 0.00008(+) 0.0019(+) 0.00005(+)

4 0.00051(+) 0.00008(+) 0.00066(+) 0.00008(+) 0.00006(+) 0.0026(+) 0.054

5 0.0056(+) <0.00001(+) 0.00006(+) <0.00001(+) 0.027(+) n/a 0.00033(+)

6 <0.00001(+) 0.00044(+) 0.11 0.00005(+) 0.00021(+) n/a n/a

Relative 

position

above the 

bed

Study site, month-day-year, and station of vertical

LMC

8-11-2006

165 ft

LMC

8-11-2006

295 ft

RM30

2-5-2006

92 ft

RM30

2-5-2006

188 ft

RM30

8-8-2006

92 ft

RM30

8-8-2006

188 ft

1 0.0046(+) <0.00001(+) <0.00001(+) 0.00036(+) 0.10 <0.00001(+)

2 <0.00001(+) 0.029(+) 0.057 0.044(+) 0.0012(+) <0.00001(+)

3 <0.00001(+) <0.00001(+) 0.0023(+) <0.00001(+) 0.00012(+) 0.0011(+)

4 <0.00001(+) 0.00001(+) 0.0046(+) <0.00001(+) 0.65 0.00002(+)

5 0.15 0.00003(+) 0.28 n/a n/a n/a
Analysis 23

Table 4. Combined mean at-a-point error in each size class ±1 standard error. 

[Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower Marble Canyon gaging station; RM30, River-mile 30 sediment 

station. n/a indicates analysis not applicable because of insufficient data in size class]

Size class

(mm)

Study site, year, and range in water discharge (Q)

Cisco

1995

Q=342-374 m3/s

GC

1996

Q= 1,280 m3/s

GC

1998

Q= 583-595 m3/s

LMC

1998-2006

Q=372-563 m3/s

RM30

2006

Q=296-353 m3/s

Mean 

of five

datasets

<0.0625 11.1±2.5 8.5±1.5 5.2±1.1 9.7±2.0 17.1±3.3 10.3±2.0

0.0625–0.074 38.1±4.5 16.9±2.8 22.3±5.2 9.5±1.1 16.2±2.3 20.6±4.8

0.074–0.088 27.9±3.4 11.6±1.8 15.6±2.8 10.4±1.2 15.5±2.0 16.2±3.1

0.088–0.105 31.3±4.7 10.2±1.8 14.5±2.6 10.7±1.2 13.4±2.3 16.0±3.9

0.105–0.125 27.9±3.7 11.3±1.7 11.2±2.0 12.0±1.6 13.2±2.0 15.1±3.2

0.125–0.149 21.4±2.4 10.1±1.5 22.9±4.9 13.5±2.6 15.2±2.5 16.6±2.4

0.149–0.177 24.4±3.1 12.5±1.4 22.5±3.8 17.3±2.6 23.9±4.6 20.1±2.3

0.177–0.210 24.1±3.8 11.5±1.5 31.6±9.0 25.5±4.3 32.7±7.0 25.1±3.8

0.210–0.250 24.4±2.8 14.0±1.4 28.1±5.0 29.3±5.4 38.8±6.6 26.9±4.0

0.250–0.297 25.6±2.9 18.3±2.1 31.6±4.4 39.5±6.1 45.2±7.3 32.0±4.8

0.297–0.354 36.3±4.7 28.7±2.9 40.7±10.6 48.4±5.5 68.8±11.3 44.6±6.8

0.354–0.420 43.6±4.2 32.1±3.1 45.7±11.1 57.7±7.8 86.1±10.9 53.0±9.2

0.420–0.500 62.2±6.3 39.8±3.6 81.6±15.3 67.5±9.6 158.3±75.6 81.9±20.2

0.500–0.595 102.0±10.9 52.0±5.8 100.6±8.9 82.7±10.6 89.9±12.5 85.4±9.1

0.595–0.707 111.4±12.7 84.4±8.2 n/a 88.0±21.8 100.1±12.5 95.9±6.1

0.707–0.841 124.2±16.4 119.8±8.1 n/a 120.4±12.9 100.0 116.1±5.5

0.841–1.00 131.3±23.9 111.1±22.2 n/a 133.3± 0.0 n/a 125.3±7.1

1.00–1.19 135.0±15.0 n/a n/a n/a n/a 135.0

1.19–1.41 135.0 ±15.0 n/a n/a n/a n/a 135.0

1.41–1.68 120 n/a n/a n/a n/a 120.0

1.68–2.00 160 n/a n/a n/a n/a 160.0
24 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Table 5. Combined mean at-a-point error in each Rouse-number class ±1 standard error.

[Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower Marble Canyon gaging station; RM30, River-mile 30 sediment 

station. n/a indicates analysis not applicable because of insufficient data in Rouse-number class]

Rousenumber 

class

Study site, year, range in water discharge (Q), and mean shear velocity (u

*

)

Cisco

1995

Q=342–374 m3/s

u

*

=9.15±0.25

GC

1996

Q=1,280 m3/s

u

*

=12.49±0.46

GC

1998

Q=583–595 m3/s

u

*

=6.46±0.18

LMC

1998-2006

Q=372–563 m3/s

u

*

=6.98±0.38

RM30

2006

Q=296–353 m3/s

u

*

=4.15±0.11

Mean 

of five

datasets

<0.01 11.1±2.5 8.5±1.5 5.2±1.1 9.7±2.0 17.1±3.3 10.3±2.0

0.05–0.07 n/a 16.9±2.8 n/a n/a n/a 16.9

0.07–0.09 38.1±4.5 11.6±1.8 n/a n/a n/a 24.9±13.3

0.09–0.13 27.9±3.4 10.2±1.8 22.3±5.2 9.5±1.1 n/a 17.5±4.6

0.13–0.17 31.3±4.7 11.3±1.7 15.6±2.8 10.4±1.2 n/a 17.1±4.9

0.17–0.23 27.9±3.4 10.1±1.5 14.5±2.6 10.7±1.2 16.2±2.3 15.9±3.2

0.23–0.32 21.4±2.4 12.5±1.4 11.2±2.0 12.0±1.6 15.5±2.0 14.5±1.9

0.32–0.40 24.4±3.1 11.5±1.5 22.9±4.9 13.5±2.6 13.4±2.3 17.1±2.7

0.40–0.52 24.1±3.8 14.0±1.4 22.5±3.8 17.3±2.6 13.2±2.0 18.2±2.2

0.52–0.70 24.4±2.8 18.3±2.1 31.6±9.0 25.5±4.3 15.2±2.5 23.0±2.9

0.70–0.82 25.6±2.9 28.7±2.9 n/a 29.3±5.4 23.9±4.6 26.9±1.3

0.82–1.05 36.3±4.7 32.1±3.1 28.1±5.0 39.5±6.1 32.7±7.0 33.8±1.9

1.05–1.28 43.6±4.2 39.8±3.6 31.6±4.4 n/a n/a 38.3±3.5

1.28–1.6 62.2±6.3 52.0±5.8 40.7±10.6 48.4±5.5 38.8±6.6 48.4±4.2

1.6–2.0 102.0±10.9 84.4±8.2 45.7±11.1 57.7±7.8 45.2±7.3 67.0±11.3

2.0–2.5 111.4±12.7 119.8±8.1 81.6±15.3 67.5±9.6 68.8±11.3 89.8±10.9

2.5–3.0 124.2±16.4 111.1±22.2 100.6±8.9 82.7±10.6 86.1±10.9 100.9±7.7

3.0–3.6 131.3±23.9 n/a n/a 88.0±21.8 158.3±75.6 125.9±20.5

3.6–4.4 135.0±15.0 n/a n/a 120.4±12.9 89.9±12.5 115.1±13.3

4.4–5.0 135.0±15.0 n/a n/a 133.3±0.0 100.1±12.5 122.8±11.4

5.0–6.0 120 n/a n/a n/a n/a 120

6.0–7.0 160 n/a n/a n/a 100.0 130.0±30.0
Analysis 25

Depth-Integrated Error

The depth-integrated relative mean absolute error (DIE, 

in percent) in the velocity-weighted depth-integrated suspended-sediment concentration, arising from assuming that 

uC m

dz

dt





 



 dt >> ( ) uCm

′ dz

dt





 



 dt 0

T

∫ 0

T

∫ in a one-way depthintegrated suspended-sediment measurement at a single vertical, is defined for each size class m as

DIE =

 ,(11)

where uC dz

dt

dt u dz

dt

dt m

T T ∫ ∫ 0 0 ( ) ( ) is the velocity-weighted 

concentration in size class m measured by a depth-integrating 

100

uCm 0

T

 dz

dt





 



dt u 0

T

 dz

dt





 



dt  uCm 0

h

 dz < u > h

uCm 0

h

 dz < u > h





























Figure 6. Combined mean at-a-point error (MAPE) as a 

function of grain size for the five point-sample datasets, showing 

ranges in discharge (Q) during collection of each dataset and 

linear-regression fit to the combined data in all five datasets. 

Error bars are 1 standard error. Cisco, Cisco gaging station; 

GC, Grand Canyon gaging station; LMC, Lower Marble Canyon 

gaging station; RM30, River-mile 30 sediment station (see figure 

1 for locations).

Figure 7. Combined mean at-a-point error (MAPE) as a function 

of Rouse number for the five point-sample datasets, showing the 

mean shear velocity ( u

* ) ±1 standard error during collection of 

each dataset and linear-regression fit to the combined data in all five 

datasets. Error bars are 1 standard error. Cisco, Cisco gaging station; 

GC, Grand Canyon gaging station; LMC, Lower Marble Canyon 

gaging station; RM30, River-mile 30 sediment station (see figure 1 for 

locations).

sampler at a given vertical and uCm 0

h

∫ dz < u >h is the 

depth- and time-averaged velocity-weighted concentration 

in size class m calculated from point samples at that same 

vertical. To determine whether the DIE behaves similarly to 

the APE in the previous analysis, equation 11 was calculated 

as a function of grain size, using the 1996 and 1998 pointsample and one-way depth-integrated P-61 data collected at 

the Grand Canyon and Lower Marble Canyon gaging stations 

(figs. 1, 2B, 2C). To calculate this error, uCm 0

h

∫ dz < u >h

for each vertical sampled in 1996 and 1998 was determined 

by using the 18 point samples collected at each vertical, and 

uCm 0

T

∫ dz

dt





 



 dt u 0

T

∫ dz

dt





 



 dt was determined by using the 

one-way depth-integrated sample collected before or after 

each set of 18 point samples. The mean depth-integrated error 

(MDIE, in percent) was then calculated by averaging the DIEs 

COMBINED MAPE, IN PERCENT

1

10

100

1,000

0.01 0.10 1.00

Cisco 1995 (Q = 342-374 m3/s)

GC 1996 (Q = 1,280 m3/s)

GC 1998 (Q = 583-595 m3/s)

LMC 1998-2006 (Q = 372-563 m3/s) 

RM30 2006 (Q = 296-353 m3/s)

MAPE = 10.3 + 108.9D R2= 0.79 

GRAIN SIZE, IN MILLIMETERS

EXPLANATION

COMBINED MAPE, IN PERCENT

1

10

100

1,000

0.001 0.01 0.1 1 10

Cisco 1995 (mean u

*

 = 9.15 + 0.25) 

GC 1996 (mean u

* = 12.49 + 0.46)

GC 1998 (mean u* = 6.46 + 0.18)

LMC 1998-2006 (mean u* = 6.98 + 0.38) 

RM30 2006 (mean u

*

 = 4.15 + 0.11)

MAPE = 14.8 + 23.8pm R2= 0.81 

ROUSE NUMBER

EXPLANATION
26 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

associated with the one-way depth-integrated samples collected before and after each set of 18 point samples. Mathematically, the MDIE is expressed as 

MDIE =

 . (12)

The results of this analysis indicate that as with the 

MAPE, the MDIE also depends on grain size. Analysis of variance using a standard F-test indicates that at the p=0.05 level 

of significance, the MDIE was positively correlated with grain 

size in all 10 cases for which data were available to calculate 

this error (table 6).

Comparison of the MDIE and MAPE indicates that these 

two errors are somewhat similar at each vertical but that the 

MDIEs are generally larger than the MAPEs (figs. 8, 9). This 

difference could partly arise from the fact that the MAPEs 

are not true instantaneous errors, whereas the MDIEs are the 

instantaneous errors arising from a complete lack of time averaging (since a depth-integrating sampler passes through each 

elevation only once during a single transit). MAPEs include 

some time averaging (over time scales of seconds to <1 minute) because they are calculated by comparing the fluxes from 

individual point samples with time-averaged fluxes, whereas 

MDIEs are calculated by comparing non-time-averaged 

suspended-sediment concentrations collected by using one-way 

depth integration with depth- and time-averaged suspendedsediment concentrations calculated from point samples.

At both the Grand Canyon and Lower Marble Canyon 

gaging stations (figs. 1, 2B, 2C), the MDIEs ranged from being 

equivalent to the MAPEs to being about a factor of 3 larger 

than the MAPEs for all size classes of sediment (fig. 10). 

On average, the MDIEs were therefore a factor of ~2 larger 

100

uCm 0

T

 dz

dt





 



dt u 0

T

 dz

dt





 



dt  uCm 0

h

 dz < u > h

uCm 0

h

 dz < u > h





























than the MAPEs. In addition to the above-described effects 

of differing durations of time averaging on the MDIEs and 

MAPEs, part of this factor-of-2 difference between MDIEs 

and MAPEs could also arise from changes in sedimentsupply conditions over the 1 hour required to collect the 18 

point samples and two bracketing one-way depth-integrated 

samples at each vertical. The importance of the effect of 

changing sediment-supply conditions on suspended-sedimentconcentration errors calculated over hourly time scales is 

evaluated in more detail below. 

Effect of Different Durations of Time Averaging 

on Suspended-Sediment-Concentration Errors

To further evaluate the effect of different durations of 

time averaging on the error in the time- and depth-averaged 

velocity-weighted concentration of suspended sediment in 

any size class m, sequential one-way (non-time-averaged, 

with only one “measurement” at each elevation in the flow) 

depth-integrated samples and sequential two-way (minimally 

time-averaged, with two “measurements” at each elevation in 

the flow) depth-integrated samples were analyzed to determine 

whether this error decreases as the number of repeated transits 

at the same vertical increases. As above, “one transit” in this 

usage is defined as the path the sampler takes either from the 

bed to the water surface or from the water surface to the bed. 

For example, a standard two-way depth-integrated sample collected with a D-96-A1 sampler at a single vertical consists of 

two transits, and a one-way depth-integrated sample collected 

with a P-61 sampler at a single vertical consists of one transit. 

This analysis was accomplished by mathematically combining sequential depth-integrated samples into single samples 

(using laboratory-determined masses and grain-size distributions, not simply suspended-sediment concentrations) and then 

Table 6. Levels of statistical significance at which the mean depth-integrated error 

depends on grain size. 

[Critical level of significance is set equal to 0.05; values ≤0.05 (in this table, all) are shown in bold; (+)

indicates significant positive correlation and (–) significant negative correlation between grain size and mean 

depth-integrated error. GC, Grand Canyon gaging station; LMC, Lower Marble Canyon gaging station]

Study site, month-day-year, and cableway station of vertical

GC

3-28-1996

190 ft

GC

3-28-1996

290 ft

GC

3-30-1996

190 ft

GC

3-30-1996

290 ft

GC

4-2-1996

190 ft

0.042(+) 0.00007(+) 0.013(+) 0.016(+) 0.00001(+)

Study site, month-day-year, and station of vertical

GC

4-2-1996

290 ft

GC

9-26-1998

190 ft

GC

9-26-1998

290 ft

LMC

9-22-1998

180 ft

LMC

9-22-1998

280 ft

 0.00005(+) 0.00008(+) 0.00001(+) 0.00017(+) 0.038(+)
Analysis 27

Figure 8. Comparison of the mean depth-integrated error (MDIE) in velocity-weighted one-way depthintegrated concentration of suspended sediment in each size class and mean at-a-point error (MAPE) in 

flux of sediment in each size class at the Grand Canyon gaging station (figs. 1, 2B) at vertical located along 

measurement cableway at station 190 ft on March 28, 1996 (A), at station 290 ft on March 28, 1996 (B), at 

station 190 ft on March 30, 1996 (C), at station 290 ft on March 30, 1996 (D), at station 190 ft on April 2, 1996 

(E ), at station 290 ft on April 2, 1996 (F ), at station 190 ft on September 26, 1998 (G), and at station 290 ft on 

September 26, 1998 (H); and at the Lower Marble Canyon gaging station (fig. 2C) at vertical located along 

former measurement cableway at station 180 ft on September 22, 1998 (I), and at station 280 ft on September 

22, 1998 (J). Error bars are 1 standard error.

GRAIN SIZE, IN MILLIMETERS

MDIE OR MAPE, IN PERCENT

A B

C D

E F

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

1

10

100

1,000

10,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 
28 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure 8.—Continued

GRAIN SIZE, IN MILLIMETERS

MDIE OR MAPE, IN PERCENT

G H

I J

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

0.01 0.10 1.00

MDIE

MAPE 

0.1

1

10

100

1,000

10,000

0.01 0.10 1.00

MDIE

MAPE 
Analysis 29

Figure 9. Likely range in the ratio of mean depth-integrated error (MDIE) to mean at-a-point error (MAPE) as 

a function of grain size at the Grand Canyon gaging station (figs. 1, 2B) at vertical located along measurement 

cableway at station 190 ft on March 28, 1996 (A), at station 290 ft on March 28, 1996 (B), at station 190 ft on 

March 30, 1996 (C), at station 290 ft on March 30, 1996 (D), at station 190 ft on April 2, 1996 (E), at station 290 ft on 

April 2, 1996 (F ), at station 190 ft on September 26, 1998 (G), and at station 290 ft on September 26, 1998 (H); and 

at the Lower Marble Canyon gaging station (fig. 2C) at vertical located along former measurement cableway at 

station 180 ft on September 22, 1998 (I), and at station 280 ft on September 22, 1998 (J). For each sediment size 

class, maximum value of this ratio was calculated as (MDIE+1SE)/(MAPE-1SE), and minimum value of this ratio 

as (MDIE-1SE)/(MAPE+1SE), where SE is standard error.

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

GRAIN SIZE, IN MILLIMETERS

MDIE-TO-MAPE RATIO

A B

C D

E F
30 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure 10. Likely range in mean value among all 10 cases in 

figure 9 of the ratio of mean depth-integrated error (MDIE) to 

mean at-a-point error (MAPE) plotted as a function of grain size. 

For each sediment size class, maximum value of this mean ratio 

was calculated by averaging maximum values of the MDIEto-MAPE ratio among all 10 cases, calculated as (MDIE+1SE)/

(MAPE-1SE), and minimum values of this mean ratio among all 

10 cases, calculated as (MDIE-1SE)/(MAPE+1SE), where SE is 

standard error. 

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

0.001

0.01

0.1

1

10

100

1,000

0.01 0.10 1.00

GRAIN SIZE, IN MILLIMETERS

MDIE-TO-MAPE RATIO

G H

I J

0.01

0.1

1

10

100

0.01 0.10 1.00

MEAN

 MDIE

 TO 

MAPE

 RATIO

GRAIN SIZE, IN MILLIMETERS

MEAN MDIE-TO-MAPE RATIO

Figure 9.—Continued
Analysis 31

evaluating the effect of increasing the duration of time averaging on a modified version of the MDIE. 

The error evaluated in these analyses, which is a modified 

version of the MDIE in equation 12, is referred to as the mean 

number-of-transits error (MNOTE, in percent):

MNOTE = 

 

 

,(13)

where the depth- and time-averaged velocity-weighted 

concentration in sediment size class m, that is, the term

uCm 0

h

∫ dz < u >h in equation 12 evaluated with the pointsample data, is replaced by the “time-averaged velocityweighted concentration in sediment size class m,” calculated 

by averaging the velocity-weighted concentration in sediment 

size class m among each set of sequential depth-integrated 

samples, uCm 0

T

∫ dz

dt





 



 dt u 0

T

∫ dz

dt





 



 dt . 

The first step in this analysis was to determine whether a 

demonstrable net change in suspended-sediment concentration 

occurred over the time scale of each of these sets of sequential 

depth-integrated samples. Analyses of the sequential depthintegrated data using F-tests indicate that at the p=0.05 level 

of significance: (1) no changes in suspended-sand concentration occurred during data collection at any of the four study 

sites, (2) no changes in suspended-silt-and-clay concentration 

occurred during data collection at the River-mile 30 sediment 

station (fig. 2D) or at the Cisco and Lower Marble Canyon 

gaging stations (figs. 2A, 2C), and (3) an ~6 percent increase 

in suspended-silt-and-clay concentration occurred during data 

collection at the Grand Canyon gaging station (fig. 2B). Thus, 

the MNOTEs calculated with equation 13 cannot be demonstrated to include the effects of real changes in sand-supply 

conditions during the periods of time averaging in these analyses, nor to include the effects of substantial changes in siltand clay-supply conditions during the periods of time averaging in these analyses. As stated above, the MDIEs calculated 

in the analysis in the previous section likely include the effect 

of larger changes in sediment-supply conditions over the hour 

required to collect the 18 point samples and bracketing depthintegrated samples. Therefore, the MNOTEs calculated with 

equation 13 in this analysis are likely to be smaller and more 

accurate (that is, essentially devoid of the effects of changes in 

sediment supply) than those calculated with equation 12 in the 

previous section. 

An even number of sequential samples that could be 

combined multiple times was required for this operation. For 

example, 12 sequential samples could first be combined into 

6 samples and then subsequently combined into 3 samples. 

Therefore, the odd number of samples (seven sets of 5 samples 

at the Cisco gaging station, and one set of 15 samples at both the 

River-mile 30 sediment station and the Lower Marble Canyon 

gaging station) and the 14 samples at the Grand Canyon gaging 

100

uCm 0

T dz

dt

dt u 0

T dz

dt

dt uCm 0

T dz

dt

dt u 0

T dz

dt

dt

uCm 0

T dz

dt

dt u 0

T dz

dt

dt

station that could be combined only once (into 7 samples) were 

analyzed in two different configurations of combinations. 

Analysis of the data from the Cisco gaging station (figs. 

1, 2A) was conducted such that the first four samples of each 

set of five sequential samples were analyzed as four samples 

and then as two synthetically combined samples, and then the 

last four of each set of five sequential samples were analyzed 

in the same manner. Flow conditions have been shown to play 

only a minor role in the MAPE; the MDIE has been shown 

to be similar to the MAPE; and flow conditions were, in any 

case, similar during the 2 days of depth-integrated-sample data 

collection at the Cisco gaging station. Thus, the MNOTEs calculated for each grouping of samples were analyzed together. 

For each sediment size class m, this procedure resulted in 14 

observations of the one-transit MNOTE with no time averaging (that is, the one-transit MNOTE among each set of four 

sequential one-way depth-integrated samples) and in 14 observations of the MNOTE with minimal time averaging (that 

is, the MNOTE among each set of two sequential synthetic 

“two-transit” depth-integrated samples constructed from the 

one-way depth-integrated samples). The mean MNOTEs for 

each sediment size class m for these 14 observations of the 

MNOTE with no and minimal time averaging are plotted in 

figure 11. 

Data from the River-mile 30 sediment station and the 

Lower Marble Canyon gaging station (figs. 1, 2C, 2D) were 

analyzed such that the first 12 samples of each set of 15 

sequential samples were analyzed as 12 samples and then as 3 

synthetically combined samples, and then the last 12 of each 

set of 15 sequential samples were analyzed in the same manner. The first and last 12 of the 14 sequential samples collected 

at the Grand Canyon gaging station were then also analyzed in 

this same manner. Because flow conditions play only a minor 

role in this error and, as at the Cisco gaging station (fig. 2A), 

flow conditions were similar during collection of the two-way 

depth-integrated data at the River-mile 30 sediment station 

and the Lower Marble Canyon and Grand Canyon gaging stations, the MNOTEs calculated for each grouping of samples 

at these three sites were also analyzed together, resulting in 

six observations of the MNOTE with minimal time averaging 

(that is, the MNOTE among each set of 12 two-way depthintegrated samples) and two distributions of six observations 

of the MNOTEs with greater durations of time averaging (that 

is, the MNOTEs among each set of six sequential “synthetic 

four-transit” depth-integrated samples and each set of four 

sequential “synthetic eight-transit” depth-integrated samples 

constructed from the two-way depth-integrated samples). The 

mean MNOTEs for each sediment size class m for these three 

distributions of six observations of the MNOTE with different 

durations of time averaging are also plotted in figure 11. 

Large increases in the duration of time averaging result in 

a substantial and significant decrease in the MNOTEs, especially in the sand size classes (fig. 11; table 7). To determine the 

relative significance of the effect on the MDIE in each sediment size class of increasing the duration of time averaging, 

Student’s t-tests were conducted on appropriate groupings of 
32 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

“synthetic two-transit” MNOTEs and two-transit MNOTEs 

calculated using the data collected at the River-mile 30 sediment 

station (fig. 2D) and at the Lower Marble Canyon and Grand 

Canyon gaging stations (figs. 2B, 2C). Because the differences 

between MAPEs (arising from minimal time averaging over 

time scales of seconds to <1 minute in the point samples) and 

the one-transit MNOTEs (arising from zero time averaging in 

the one-way depth-integrated samples) are minimal, averaging 

over time scales in excess of 1 minute is likely required to result 

in substantial reductions in the MNOTE. The similarity between 

the MNOTEs in the “synthetic two-transit” Cisco P-61 data 

and the two-transit D-96-A1 data collected at the other three 

study sites indicates that differences in study-site geometry, 

flow and sediment-supply conditions, and the type of isokinetic 

suspended-sediment sampler used do not greatly influence the 

MNOTE, thus providing further support for the approach used 

in this study of analyzing data from all four study sites together. 

Although an increase in the number of transits reduces 

the MNOTE in each sediment size class, as well as the level of 

significance at which different-transit MNOTEs can be distinguished, the number of transits must be quadrupled before different-transit MNOTEs can be demonstrated to generally differ 

at the p=0.05 level of significance because the large variance in 

the “number-of-transits error” in each sediment size class makes 

it difficult to statistically distinguish between MNOTEs associated with different numbers of transits unless either the sample 

size is relatively large (that is, larger than the sample sizes of 

6 to 14 in table 7) or the difference in the number of transits 

exceeds a factor of ~4. On the basis of the median (among all 

size classes) level of significance in the difference between the 

various errors, the most different of the various cases compared 

in table 7 are (1) the one-transit and “synthetic four-transit” 

MNOTEs and (2) the two-transit and “synthetic eight-transit” 

MNOTEs. The two cases in table 7 that border on being significantly different are (1) the one-transit and “synthetic two-transit” MNOTEs and (2) the two-transit and “synthetic four-transit” MNOTEs. Therefore, the most significant difference exists 

between the errors associated with the greatest increase (that is, 

a quadrupling) in the number of transits. This result makes sense 

in that an increase from zero time averaging in the one-transit 

depth-integrated data (with each elevation in the flow sampled 

only once) to finite time averaging in the “four-transit” depthintegrated data (with each elevation in the flow sampled four 

times) is effectively an infinite increase in the duration of time 

averaging (that is, the duration of time averaging increases from 

zero to a small positive number). Thus, the greatest significant 

difference between MNOTEs should be associated with this 

“infinite” increase in the duration of time averaging.

Although quadrupling the number of transits is required 

to result in a significant decrease in the MNOTE, doubling the 

number of transits does result in a fairly consistent, ~30-percent 

reduction in the MNOTE in any given sediment size class, as 

illustrated by the ratios between the MNOTEs associated with 

different numbers of transits (fig. 12). Among all size classes of 

sediment in the analyses (silt and clay plus 16 size classes of 

sand), the mean ±1 standard-error ratio between the MNOTE 

Figure 11. Mean value of mean at-a-point error (MAPE) among 

the five point-sample datasets, and mean values of mean numberof-transits errors (MNOTEs) calculated for one-way, two-way, and 

the various synthetic multitransit depth-integrated data plotted as 

a function of grain size. Error bars are 1 standard error. Increase in 

duration of time averaging (as more transits are added) generally 

leads to a progressive decrease in mean value of MNOTE, 

especially in sand size classes. Cisco, Cisco gaging station; RM30, 

River-mile 30 sediment station (see figure 1 for locations).

the mean MAPE calculated from the five point-sample datasets 

(fig. 6; table 4) and the MNOTEs calculated with equation 13 

for the one-way, two-way, and various synthetic multitransit 

depth-integrated-sample data. For these t-tests, a Student’s 

t-test comparing the means of two groups with equal variance 

was used when an F-test indicated that the variances of the two 

groups could not be determined to differ at the p=0.05 level of 

significance, and a Student’s t-test comparing the means of two 

groups with unequal variance was used when an F-test indicated 

that the variances of the two groups differed at the p=0.05 level 

of significance. The only difference between these two tests 

was in degrees of freedom: the t-test comparing two groups 

with unequal variance had fewer degrees of freedom than the 

t-test comparing two groups of equal variance. Results from 

the t-tests listed in table 7 indicate that the most similar errors 

are (1) the MAPEs and one-transit MNOTEs and (2) the Cisco 

1

10

100

0.01 0.10 1.00

Mean MAPE among the five point-sample datasets 

Cisco mean single-transit MNOTE

Cisco mean "synthetic two-transit" MNOTE 

RM30, LMC, GC mean two-transit MNOTE

RM30, LMC, GC mean "synthetic four-transit" MNOTE

RM30, LMC, GC mean "synthetic eight-transit" MNOTE 

MAPE 

or

 MNOTE

, IN PERCENT

GRAIN SIZE, IN MILLIMETERS

EXPLANATION

MAPE 

or

 MNOTE

, IN PERCENT

MAPE 

or

, IN PERCENT

MAPE MAPE OR MNOTE, IN PERCENT or

, IN PERCENT
Analysis 33

Table 7. Levels of statistical significance at which groupings of the mean value of the mean at-a-point error (MAPE) and various mean 

number-of-transits errors (MNOTEs) plotted in figure 11 are different in each sediment size class.

[Critical level of significance is set equal to 0.05; values ≤0.05 are shown in bold; (=) indicates Student’s t-test comparing the means of two groups with equal 

variance utilized based on F-test level of significance >0.05; (≠) indicates Student’s t-test comparing the means of two groups with unequal variance utilized 

based on F-test level of significance ≤0.05. Cisco, Cisco gaging station; GC, Grand Canyon gaging station; LMC, Lower Marble Canyon gaging station; RM30, 

River-mile 30 sediment station. n/a indicates analysis not applicable because of insufficient data in size class]

Size class

(mm)

Groups compared

MAPE

among

five

datasets

(n=5)

MNOTE

Cisco

1-transit

 (n=14)

MNOTE

Cisco

1-transit

(n=14)

MNOTE

Cisco

synthetic

2-transit

(n=14)

MNOTE

Cisco

synthetic

2-transit

(n=14)

MNOTE

RM30,

LMC,

GC

2-transit

(n=6)

MNOTE

RM30,

LMC,

GC

2-transit

(n=6)

MNOTE

RM30,

LMC, 

GC

synthetic

4-transit

(n=6)

MNOTE

RM30,

LMC,

GC

synthetic

4-transit

(n=6)

MNOTE

RM30,

LMC,

GC

synthetic

8-transit

(n=6)

MNOTE

Cisco

1-transit

(n=14)

MNOTE

RM30,

LMC, 

GC

synthetic

4-transit

MNOTE

RM30,

LMC,

GC

2-transit

(n=6)

MNOTE

RM30,

LMC,

GC

synthetic

8-transit

(n=6)

< 0.0625 0.012 (≠) 0.051 (=) 0.15 (≠) 0.80 (=) 0.50 (=) 0.28 (≠) 0.48 (=)

0.0625–0.074 0.22 (=) 0.15 (=) 0.20 (≠) 0.083 (=) 0.31 (=) <0.0001 (≠) 0.015 (=)

0.074–0.088 0.13 (=) 0.00010 (=) 0.76 (=) 0.11 (=) 0.22 (=) <0.0001 (≠) 0.018 (=)

0.088–0.105 0.72 (=) 0.024 (=) 0.52 (=) 0.097 (=) 0.21 (=) 0.00019 (=) 0.0089 (=)

0.105–0.125 0.76 (=) 0.069 (=) 0.68 (≠) 0.045 (=) 0.21 (=) 0.0038 (≠) 0.0018 (=)

0.125–0.149 0.46 (=) 0.056 (=) 0.64 (≠) 0.029 (=) 0.19 (=) 0.0080 (=) 0.00060 (=)

0.149–0.177 0.12 (=) 0.054 (=) 0.78 (=) 0.059 (=) 0.19 (=) 0.0075 (=) 0.0017 (=)

0.177–0.210 0.045 (=) 0.040 (=) 0.14 (≠) 0.057 (=) 0.14 (=) 0.064 (=) 0.0015 (=)

0.210–0.250 0.30 (=) 0.23 (=) 0.89 (≠) 0.080 (=) 0.11 (=) 0.021 (≠) 0.0022 (=)

0.250–0.297 0.47 (=) 0.18 (=) 0.98 (≠) 0.027 (=) 0.061 (≠) 0.0099 (≠) 0.0026 (≠)

0.297–0.354 0.29 (=) 0.28 (=) 0.32 (≠) 0.0015 (=) 0.029 (=) 0.0047 (≠) <0.0001 (=)

0.354–0.420 0.58 (=) 0.12 (=) 0.052 (≠) 0.0010 (=) 0.13 (=) <0.0001 (≠) 0.00014 (=)

0.420–0.500 0.096 (=) 0.18 (=) 0.015 (≠) 0.021 (=) 0.023 (=) <0.0001 (≠) 0.00060 (=)

0.500–0.595 0.32 (=) 0.050 (=) 0.12 (≠) 0.010 (=) 0.031 (=) <0.0001 (≠) 0.00033 (=)

0.595–0.707 0.035 (=) 0.00073 (=) 0.00031 (≠) 0.15 (=) 0.25 (=) <0.0001 (≠) 0.040 (=)

0.707–0.841 0.018 (=) 0.00021 (≠) 0.049 (≠) 0.19 (≠) 0.075 (=) <0.0001 (≠) 0.11 (≠)

0.841–1.00 0.073 (≠) <0.0001 (=) 0.16 (≠) 0.11 (=) 0.88 (=) 0.0098 (≠) 0.81 (=)

1.00–1.19 n/a n/a n/a n/a n/a n/a n/a

1.19–1.41 n/a n/a n/a n/a n/a n/a n/a

1.41–1.68 n/a n/a n/a n/a n/a n/a n/a

1.68–2.00 n/a n/a n/a n/a n/a n/a n/a

Median

level of

significant

difference

among all 

size classes

0.27 0.087 0.20 0.059 0.19 0.0038 0.0022
34 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

associated with two transits and the MNOTE associated with 

one transit is 0.64±0.02. Similarly, the mean ratio between 

the MNOTE associated with four transits and the MNOTE 

associated with two transits is 0.67±0.02, and the mean ratio 

between the MNOTE associated with eight transits and the 

MNOTE associated with four transits is 0.71±0.02. For the 

silt-and-clay size class only, the ratio between the MNOTE 

associated with two transits and the MNOTE associated with 

one transit is 0.60, the ratio between the MNOTE associated 

with four transits to the MNOTE associated with two transits 

is 0.74, and the ratio between the MNOTE associated with 

eight transits and the MNOTE associated with four transits 

is 0.85. For sand analyzed as a single size class, the ratio 

between the MNOTE associated with two transits and the 

MNOTE associated with one transit is 0.71, the ratio between 

the MNOTE associated with four transits and the MNOTE 

associated with two transits is 0.70, and, the ratio between 

the MNOTE associated with eight transits and the MNOTE 

associated with four transits is 0.63. Associated with this 

reduction in the MNOTE is a reduction in the relative mean 

absolute error in the median grain size of suspended sand, 

herein referred to as the D50MNOTE. The ratio between the 

D50MNOTE associated with two transits and the D50MNOTE 

associated with one transit is 0.79, the ratio between the 

D50MNOTE associated with four transits and the D50MNOTE 

associated with two transits is 0.64, and the ratio between the 

D50MNOTE associated with eight transits and the D50MNOTE 

associated with four transits is 0.65. 

The previous analysis indicates that with a fair amount 

of variation, doubling the duration of time averaging through 

doubling the number of transits decreases the MNOTE or 

D50MNOTE by ~30 percent. To understand the reason for 

this style of error reduction, it is informative to compare the 

behavior of the MNOTE8 and D50MNOTE with the behavior 

of the standard error (SE) of the mean, as given by

 

SE = 

n

, (14)

where s is the sample standard deviation and n is the number 

of uncorrelated observations in the sample (as reviewed by 

Davis, 1986). Here, an increase in the number of repeated, 

uncorrelated observations will reduce the SE by a factor of 

exactly 

	

1 n0.5. In a form identical to the form of equation 14, 

a general equation to describe the observed behavior of the 

single-vertical MNOTE is

 

MNOTE = MNOTE1

ntrans

 , (15)

where MNOTE1 is the single-vertical MNOTE in a given 

sediment size class when only one transit is collected, ntrans is 

the number of transits at this vertical, and g is the exponent 

describing the behavior of the MNOTE as transits are added. 

Rearranging equation 15 into the form

8

 For review, the mean absolute error (in this case, MNOTE) is 0.8s

(calculated for n degrees of freedom) in a Gaussian normal distribution, and 

the standard error of the mean is  n . 

Figure 12. Ratios between the mean values of the mean numberof-transits-errors (MNOTEs) in figure 11 associated with different 

numbers of transits plotted as a function of grain size. Ratios of twotransit to one-transit MNOTEs (blue dots) are from data collected at 

the Cisco gaging station (fig. 1), and ratios of four-transit to twotransit MNOTEs (red triangles) and of eight-transit to four-transit 

MNOTEs (black diamonds) are from data collected at the River-mile 

30 sediment station and at the Lower Marble Canyon and Grand 

Canyon gaging stations. Light-blue line indicates ratio of two-transit 

to one-transit mean MNOTEs in total suspended-sand concentration 

at the Cisco gaging station; red line indicates ratio of four-transit to 

two-transit mean MNOTEs in total suspended-sand concentration at 

the River-mile 30 sediment station and at the Lower Marble Canyon 

and Grand Canyon gaging stations; black line indicates ratio of 

eight-transit to four-transit mean MNOTEs in total suspended-sand 

concentration at the River-mile 30 sediment station and at the Lower 

Marble Canyon and Grand Canyon gaging stations.

 

MNOTE1

MNOTE = ntrans



, (16) 

using values of the MNOTE1-to-MNOTE ratios given in 

the previous paragraph, and solving for g by logarithmically transforming the data and using least-squares linear 

regression9 yields the following g values. Use of the mean 

9 g can also be solved for explicitly by  = lognTRANS MNOTE ( 1 MNOTE)

and then computing the average g value for the MNOTE1-to-MNOTE 

ratios associated with measurements with (1 transit)/(2 transits), (1 transit)/

(4 transits), and (1 transit)/(8 transits). This approach assumes equivalent 

certainty at which each of these three ratios is known. Use of least-squares 

linear regression on the log-transformed data was deemed a more accurate 

estimator of g because (1) it deemphasized the certainty associated with any 

one of the three empirically determined values of the MNOTE1-to-MNOTE 

ratios and (2) it allowed inclusion of four values, with the addition of the 

MNOTE1-to-MNOTE ratio of 1 associated with measurements of (1 transit)/

(1 transit), instead of only three values in the calculation of g.

0.0

0.2

0.4

0.6

0.8

1.0

0.01 0.10 1.00

Two-transit to one-transit MNOTE ratio

Four-transit to two-transit MNOTE ratio

Eight-transit to four-transit MNOTE ratio 

MNOTE

 RATIO

GRAIN SIZE, IN MILLIMETERS

MNOTE RATIO
Analysis 35

MNOTE1-to-MNOTE ratios among all sediment size classes 

results in g=0.566, use of the MNOTE1-to-MNOTE ratios 

for the silt and clay size class results in g=0.468, and use of 

the MNOTE1-to-MNOTE ratios for sand analyzed as a single 

size class results in g=0.563. Use of the D50MNOTE1-toD50MNOTE ratios results in g=0.546. Given the variation, 

relatively small number of observations, and uncertainty in 

the data used to calculate the g values, it is probably best 

to conclude that g≈0.5. Thus, the observed reduction in the 

MNOTE and D50MNOTE as transits are added is identical to 

the behavior of error reduction arising from an increase in the 

number of repeated, uncorrelated observations. 

The identical behavior of the MNOTE and the SE indicates that the same level of error reduction can be achieved at 

any one vertical in an EDI or EWI measurement by (1) simply 

adding more transits or (2) conducting separate, repeated 

depth-integrated measurements. Error reduction by simply 

adding more transits to each vertical comes at the modest cost 

of only a few minutes of additional field time at each vertical. 

Error reduction through adding repeated, but separate, uncorrelated depth-integrated measurements, however, takes slightly 

longer in the field (through the addition of more bottles to a 

measurement) and results in additional laboratory sampleprocessing time (because each depth-integrated measurement at each vertical needs to be processed separately in the 

laboratory). Thus, doubling the number of transits reduces the 

MNOTE by ~30 percent and does not increase the amount of 

laboratory work, whereas doubling the number of repeated 

separate depth-integrated measurements reduces the standard 

error of the mean of these measurements by 29 percent, while 

slightly increasing the field work and doubling the required 

laboratory work. Therefore, reduction in the error arising from 

inadequate time averaging is more efficiently achieved by adding more transits to each vertical than by conducting repeated, 

separate measurements at each vertical.

Evaluation of Spatial Correlations Between 

Verticals and Temporal Correlations at Verticals 

in a Cross Section 

The best way to reduce random error in a measurement 

is through increasing the sample size of uncorrelated observations known to come from the same population (for example, 

Taylor, 1997; Bevington and Robinson, 2003). In the case of 

the random error at a single vertical arising from inadequate 

time averaging of turbulent and other short-term fluctuations 

in sediment flux, the only ways to reduce this error are to make 

repeated or, as shown above, longer-duration observations. In a 

multivertical EDI or EWI measurement, this “time averaging” 

error also can likely be reduced through the addition of verticals, especially if the correlation in depth-integrated concentration between adjacent verticals is small. In any given cross 

section, the maximum spacing at which the depth-integrated 

concentration is correlated between adjacent verticals depends 

on the sediment size class and flow conditions.This spacing 

is likely negatively correlated with grain size because the 

cross-stream spatial structure in suspended-silt-and-clay concentration is generally more uniform than that in suspendedsand concentration. Furthermore, this spacing also is likely 

negatively correlated with flow conditions because increases 

in depth, velocity, or turbulence generally reduce the crossstream spatial structure in the concentration of a given size 

class of sediment. 

This analysis was conducted by evaluating (1) whether 

the depth-integrated concentration of sediment in a given size 

class at adjacent verticals in a single EWI measurement was 

correlated at the p=0.05 level of significance and (2) whether 

the depth-integrated concentration of sediment in a given size 

class at different verticals exhibited a cross-stream spatial 

structure that persisted over time scales much longer than 

those associated with turbulent and other short-term fluctuations in sediment flux (for example, boil shedding from dunes) 

that operate over seconds to minutes. The data used in this 

analysis were the 11 total cases at cross sections A and B at the 

River-mile 30 sediment station (fig. 2D) and cross sections A, 

B, and C at the Lower Marble Canyon gaging station (fig.2C), 

where two noncomposited nine-vertical depth-integrated suspended-sediment measurements were collected ~1.5–6 hours 

apart on the same day. This analysis was conducted on two 

size classes of sediment: sand, and silt and clay. As described 

previously, to remove the effects of changes in the upstream 

sediment supply or stream flow conditions between measurements, and to remove the small biases between the data collected with the D-77 bag-type and D-96-A1 depth-integrating 

samplers, the depth-integrated concentration of suspended 

sediment in a given size class was normalized at each vertical in a measurement through division by the mean depthintegrated suspended-sediment concentration in that size class 

among the nine verticals in that measurement. F-tests were 

then conducted to determine whether a statistically significant 

(at the p=0.05 level) correlation existed (1) in the suspendedsediment concentration between adjacent verticals in the same 

EWI measurement and (2) in the suspended-sediment concentration at each vertical between the two EWI measurements 

made hours apart on the same day. 

Results from these analyses indicate that generally no 

significant correlation exists between the depth-integrated 

suspended-sand concentrations at adjacent verticals in the 

same EWI measurement, and correlation is only slightly more 

significant between the suspended-silt-and-clay concentrations 

at adjacent verticals in the same EWI measurement. Despite 

this absence of significant spatial correlation, significant crossstream spatial structures in suspended-sand and suspendedsilt-and-clay concentrations can persist over hours (table 8; see 

appendix B), that is, over time scales much longer than those 

required to complete an EDI or EWI measurement. Thus, temporal correlations (over time scales of >1 hour) in suspendedsediment concentration at individual verticals tend to dominate 

over spatial correlations in suspended-sediment concentration, 

at least at the approximate one-flow-depth spacing between 

verticals in the nine-vertical measurements. The absence of 
Table 8. Levels of statistical significance associated with correlations (1) in suspended-sediment concentration between adjacent verticals in one mcross-stream spatial structures in suspended-sediment concentration between two noncomposited nine-vertical measurements made hours apart on mile 30 (RM30) sediment station and Lower Marble Canyon (LMC) gaging station. [Critical level of significance is set equal to 0.05; values ≤0.05 are shown in bold. Cross sections (XS), dates, times, mean discharges (Q), mean suspended-sand concentrations, clay concentrations are indicated] Cross section Date (month-day- year) Time (MST) Daily measure- ment number Mean Q (m3/s) Mean suspended-sand concentration among nine verticals (mg/L) Level of signifi- cance (p ) at which suspended-sand concentration between adjacent verticals is correlated Level of significance (p) at which cross- stream spatial structure in sand concentration is correlated between two measurements Mean suspended-silt- and-clay concentration among nine verticals (mg/L) Level of significance 

which suspen

silt-and-cl

concentrat

between adja

verticals 

correlate

RM30 XS A 2-24-2007 11:33–12:43 1 268 55.2 0.42 0.76 16.8 0.63 

RM30 XS A 2-24-2007 17:10–18:41 2 286 68.9 0.0074 17.2 0.23 RM30 XS A 8-24-2007 14:02–14:37 1 276 64.5 0.26 0.013 31.2 0.22 

RM30 XS A 8-24-2007 15:44–16:18 2 290 87.9 0.20 34.7 0.59 RM30 XS A 8-25-2007 8:42–9:19 1 348 128 0.69 0.086 47.7 0.12 

RM30 XS A 8-25-2007 10:27–11:06 2 313 67.3 0.27 27.7 0.49 RM30 XS B 8-24-2007 14:48–15:25 1 279 51.1 0.62 0.37 32.8 0.65 

RM30 XS B 8-24-2007 16:23–16:55 2 305 92.8 0.48 33.6 0.34 RM30 XS B 8-25-2007 8:03–8:37 1 364 121 0.35 0.19 47.5 0.36 

RM30 XS B 8-25-2007 9:38–10:19 2 326 65.7 0.82 27.4 0.32 LMC XS A 8-28-2007 13:50–14:10 1 418 101 0.71 0.022 1,150 0.92 

LMC XS A 8-28-2007 15:51–16:24 2 384 109 0.14 793 0.11 LMC XS A 8-29-2007 8:26–8:46 1 472 239 0.44 0.015 6,590 0.00004 

LMC XS A 8-29-2007 10:03–10:23 2 457 218 0.14 9,710 0.74 LMC XS B 8-28-2007 14:18–14:42 1 410 126 0.38 0.84 1,110 0.22 

LMC XS B 8-28-2007 16:32–16:56 2 376 107 0.35 747 0.55 LMC XS B 8-29-2007 8:04–8:21 1 476 255 0.25 0.51 5,950 0.054 

LMC XS B 8-29-2007 9:41–9:59 2 461 235 0.55 8,090 0.028 LMC XS C 8-28-2007 13:02–13:24 1 430 140 0.92 0.015 1,490 0.62 

LMC XS C 8-28-2007 14:56–15:32 2 396 139 0.31 1,020 0.077

LMC XS C 8-29-2007 8:56–9:17 1 469 240 0.50

0.034 6,560 0.013 

LMC XS C 8-29-2007 10:31–10:52 2 450 211 0.83 9,630 0.077
Analysis 37

significant spatial correlation between adjacent verticals suggests that reductions in the “time averaging” error in EDI- or 

EWI-measured suspended-sediment concentration will occur 

as verticals are added to an EDI or EWI measurement.

 Stable cross-stream spatial structures in suspended-sand 

concentration were observed at three of the five cross sections 

and in 5 of the 11 total cases of paired nine-vertical measurements (fig. 13; table 8; see appendix B), and stable crossstream structures in suspended-silt-and-clay concentration 

were observed at two of the five cross sections and in 2 of the 

11 total cases (table 8; see appendix B). Although these crossstream spatial structures in suspended-sediment concentration 

can be stable between measurements spaced hours apart, they 

either evolve into different stable spatial structures or become 

unstable over longer time scales (that is, >12 hours). Thus, 

between measurements made hours apart on subsequent days 

at these cross sections, either a different stable cross-stream 

spatial structure or no stable cross-stream spatial structure 

may exist. At other cross sections, no stable cross-stream 

spatial structures in suspended-sand or suspended-silt-and-clay 

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007 

C2

 = 0.26 + 0.74C1, R2= 0.59, p = 0.015

August 29, 2007 

C2

 = 0.31 + 0.69C1, R2= 0.50, p = 0.034 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 140 mg/L

Measurement 2 (~2 hours later), 

mean concentration = 139 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 240 mg/L

Measurement 2 (~1.5 hours later), 

mean concentration = 211 mg/L

NORMALIZED SUSPENDED-SAND CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

SUSPENDED-SAND CONCENTRATION 

 AT VERTICAL

MEASUREMENT 2 NORMALIZED 

SUSPENDED-SAND CONCENTRATION  AT VERTICAL

VERTICAL

Figure 13. Examples of stable cross-stream spatial structures 

in depth-integrated suspended-sand concentration along cross 

section C at the Lower Marble Canyon gaging station (figs. 1, 2C). 

Error bars indicate mean number-of-transits error (MNOTE) at 

each vertical; see appendix A for data. Suspended-sand data from 

other cross sections are plotted in appendix B. A, Suspendedsand concentration at each of nine verticals sampled during two 

measurements on August 28, 2007; concentration at each vertical 

in each measurement normalized by mean concentration among all 

nine verticals in each measurement. Note that spatial cross-stream 

structure in suspended-sand concentration appears to be similar 

between two measurements spaced ~2 hours apart. B, Suspendedsand concentration at each of nine verticals sampled during two 

measurements made on August 29, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that spatial 

cross-stream structure in suspended-sand concentration appears 

to be similar between the two measurements spaced ~1.5 hours 

apart but differs significantly from stable spatial structure observed 

the previous day. C, Relations between normalized suspended-sand 

concentrations at each vertical sampled in measurements 1 (C1) and 

2 (C2) on August 28 and 29, 2007. Relations are significant at p=0.05 

level, indicating significant temporal correlation in suspended-sand 

concentration at each vertical over time scales of hours on each 

day. Note similarity of relations on the 2 days, even though crossstream spatial structures in suspended-sand concentration differ 

significantly between the 2 days. 
38 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

concentration were observed to persist between measurements 

spaced hours apart (table 8; see appendix B). This observation 

of an absence of stable structures at these other cross sections 

is limited by a small number of observations. Therefore, (1) 

the result that cross-stream spatial structures in suspendedsediment concentration can be stable for hours and then either 

change overnight to a different stable structure or disappear 

altogether and (2) the fact that data were collected in this 

study only on no more than 2 subsequent days and no more 

than 3 different days total (that is, the sample size is small) 

together suggest that stable cross-stream spatial structures in 

suspended-sediment concentration could exist at these other 

cross sections when observations were not made. The cases of 

cross-stream spatial structures in suspended-sediment concentration that were stable over hours but not days are assumed 

to result from the distribution of dunes or patches of sand on 

the bed upstream from the measurement cross section. The 

relatively slow rates of dune migration (for example, Rubin 

and others, 2001) or change in sand-patch geometry (processes 

that operate over many hours) could allow stable cross-stream 

structures in suspended-sediment concentration to persist over 

hours but not days.

Despite the result that stable cross-stream spatial 

structures in suspended-sediment concentration may be 

detectable over hours, the correlation in depth-integrated 

suspended-sediment concentration is generally insignificant 

between adjacent verticals in the same measurement. At the 

p=0.05 level of significance, suspended-sand concentration 

was correlated between adjacent verticals in only 1 of the 22 

nine-vertical measurements at the five cross sections, whereas 

suspended-silt-and-clay concentration was correlated between 

adjacent verticals in 3 of the 22 nine-vertical measurements 

at the five cross sections. No change is detectable in the 

significance of the correlation in suspended-sand concentration 

between adjacent verticals as suspended-sand concentration 

increases. The significance of the correlation in suspended-siltand-clay concentration between adjacent verticals, however, 

appears to improve (that is, the silt and clay becomes more 

uniformly distributed in the cross section) as suspendedsilt-and-clay concentration increases. Especially at lower 

concentrations (fig. 14, see appendix B), the cross-stream 

variation in suspended-silt-and-clay concentration between 

adjacent verticals greatly exceeds the near-zero cross-stream 

variation in suspended-silt-and-clay concentration suggested 

by P.R. Jordan’s analysis in the report by Guy and Norman 

(1970) and Edwards and Glysson (1999). The observed 

persistence of stable cross-stream structures in suspendedsilt-and-clay concentration between measurements spaced 

hours apart indicates that the greater-than-zero cross-stream 

variation in suspended-silt-and-clay concentration between 

adjacent verticals is real, and so laboratory-processing 

errors cannot entirely explain the cross-stream variation in 

suspended-silt-and-clay concentration. These observations 

together suggest that either (1) P.R. Jordan’s estimate of the 

near-zero error in suspended-silt-and-clay concentration

arising from inadequate sampling of the cross-stream spatial 

structure in suspended-sediment concentration is incorrect, 

or (2) the variation in suspended-silt-and-clay concentration 

between adjacent verticals is dominated by the error arising 

from inadequate time averaging at each vertical. As shown in 

the next section of this report, the first of these possibilities is 

the more likely reason for the large variation in suspended-siltand-clay concentration between adjacent verticals in the ninevertical measurements when the mean suspended-silt-and-clay 

concentration in the cross section is relatively low. 

Combination of Temporal and Spatial Errors 

into an Estimate of the Total Uncertainty in the 

Time-Averaged Velocity-Weighted SuspendedSediment Concentration in a Cross Section

As stated previously, much of the focus of previous 

investigations has been on the quasi-systematic error arising 

from inadequate sampling of the cross-stream spatial structure 

in the time-averaged velocity-weighted suspended-sediment 

concentration in a river cross section. As shown by P.R. 

Jordan’s analysis in the report by Edwards and Glysson (1999, 

fig. 38), this relative standard error for sand-size sediment is 

likely about ±7 percent in simple trapezoidal cross sections 

when 2 verticals are sampled, about ±3.9 percent when 

5 verticals are sampled, and about ±2.4 percent when 10 

verticals are sampled. In these simple channels, this quasisystematic “spatial structure” error (herein referred to as the 

“number-of-verticals error” or NOVE [in percent]) decreases 

by a factor of ~1 nvert

0.7 as the number of verticals, nvert, 

increases. In more complex channels, this error for sand-size 

sediment can be almost 10 times larger. Depending on the 

geometric details of the cross section, the spatial distribution 

of sand on the bed upstream from the measurement cross 

section, and the use of either the EDI or EWI method, this 

quasi-systematic error can be either positive or negative. 

Depending on the number and location of verticals, the sign 

of the NOVE at a cross section can therefore change as crossstream spatial structures in depth-integrated suspended-sand 

concentration change over time (fig. 13; see appendix B). P.R. 

Jordan’s analysis suggests, on the basis that the suspendedsilt-and-clay is uniformly distributed in a cross section, 

that the NOVE for silt and clay is negligible (essentially 

zero) regardless of the number of verticals sampled. As 

shown below, this assumption is not necessarily valid, and 

so the NOVE for silt and clay is not negligible, at least at 

low suspended-silt-and-clay concentrations, and appears to 

decrease as verticals are added. Using the results obtained by 

Edwards and Glysson (1999, fig. 38), generalization of the 

NOVE in the velocity-weighted suspended-sand concentration 

in a simple trapezoidal channel for different numbers of 

verticals yields

 

NOVE = 12.0

nvert

0.7 . (17)

As the complexity in the channel cross section increases, 

the exponent in the denominator in equation 17 remains 
Analysis 39

constant at 0.7, and only the numerator increases. Similarly, 

generalization of the NOVE in the velocity-weighted 

suspended-silt-and-clay concentration in a simple trapezoidal 

channel for different numbers of verticals yields

 

	

NOVE = 0. (18)

The fact that the exponent in the denominator in equation 17 is 0.7 and not 0.5 is important because it means that 

in the EDI or EWI methods, verticals are sampled in such a 

way that sequential observations in the resulting series are 

negatively correlated. The interaction of (1) the nonrandom 

sampling protocol for how verticals are added to an EDI 

or EWI measurement with (2) the nonrandom cross-stream 

structure in the time-averaged velocity-weighted suspendedsand concentration under steady, uniform flow conditions is 

likely responsible for the nonrandom sequence of values that 

determines the value of this exponent. As discussed previously, if the depth-integrated suspended-sand concentrations 

measured at different verticals were completely uncorrelated 

Figure 14. Examples of unstable cross-stream spatial structures 

in depth-integrated suspended-silt-and-clay concentration along 

cross section B at the River-mile 30 sediment station (figs. 1, 2D). 

Error bars indicate mean number-of-transits error (MNOTE) at each 

vertical; see appendix A for data. Suspended-silt-and-clay data 

from other cross sections are plotted in appendix B. A, Suspendedsilt-and-clay concentration at each of nine verticals sampled during 

two measurements on August 24, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that spatial 

cross-stream structure in suspended-silt-and-clay concentration is 

dissimilar between two measurements spaced ~1.5 hours apart and 

that variation in concentration between adjacent verticals is much 

larger than expected near-zero cross-stream variation based on 

P.R. Jordan’s analysis. B, Suspended-silt-and-clay concentration at 

each of nine verticals sampled during two measurements on August 

25, 2007; concentration at each vertical in each measurement 

normalized by mean concentration among all nine verticals in 

each measurement. Note that spatial cross-stream structure in 

suspended-silt-and-clay concentration is dissimilar between two 

measurements spaced ~1.5 hours apart and that both spatial crossstream structures appear to differ from those observed the previous 

day. Also note that variation in concentration between adjacent 

verticals is much larger than expected near-zero cross-stream 

variation based on P.R. Jordan’s analysis. C, Relations between 

normalized suspended-silt-and-clay concentrations at each 

vertical sampled in measurements 1 (C1) and 2 (C2) on August 24 

and 25, 2007. Relations are not significant at p=0.05 level, indicating 

no significant temporal correlation in suspended-silt-and-clay 

concentration at each vertical over time scales of hours.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 24, 2007

C2

 = 0.85 + 0.15C1, R2= 0.025, p = 0.69 

August 25, 2007

C2

 = 0.83 + 0.17C1, R2= 0.20, p = 0.23

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 47.5 mg/L

Measurement 2 (~1.5 hours later), 

mean concentration = 27.4 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 32.8 mg/L

Measurement 2 (~1.5 hours later), 

mean concentration = 33.6 mg/L

NORMALIZED SUSPENDED-SILT-AND-CLAY CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY

 CONCENTRATION AT VERTICAL

MEASUREMENT 2 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY  CONCENTRATION AT VERTICAL

VERTICAL
40 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

with the following value in the sequence, then the exponent 

in the denominator in equation 17 would be exactly 0.5 by the 

equation for the SE (equation 14). For situations where correlation exists between sequential observations, however, SE 

computed by using equation 14 is biased. By the central-limit 

theorem, the distribution of sample means about a population 

mean approaches a Gaussian normal distribution as the sample 

size increases, regardless of the shapes of these individual 

sample distributions, unless the individual sample distributions 

do not have finite means and variances (as reviewed by Davis, 

1986). The SE defined in equation 14 is the standard deviation 

of the sample means in this normal distribution. In general, 

by using equation 14, positive correlations between sequential 

observations will lead to SEs that are too low, and negative 

correlations between sequential observations will lead to SEs 

that are too high (Dunlop, 1994; Quinn and Keough, 2003).

Analysis of simulated EDI and EWI measurements in 

a hypothetical trapezoidal river cross section, using the same 

approach as that used by P.R. Jordan (Guy and Norman, 1970; 

Edwards and Glysson, 1999), confirms that the exponent 0.7 in 

the denominator in equation 17 in fact arises from the combination of the nonrandom theoretical distribution of uCsand in a 

steady, uniform flow used in P.R. Jordan’s analysis, and from 

the nonrandom protocol stipulating how verticals are added to 

an EDI or EWI measurement. In a single-vertical EDI measurement, the single vertical would be located in the discharge 

centroid; and in a single-vertical EWI measurement, the single 

vertical would be located in the center of the cross section (fig. 

4). Under assumed steady, uniform flow conditions, the positions of these single verticals would tend to be where the highest 

velocities and largest suspended-sand concentrations would 

occur in a river cross section. As verticals are added to either an 

EDI or EWI measurement, the previous locations of verticals 

are not fixed in space but are repositioned as the cross section 

is divided into more increments of equal discharge or width 

(fig. 4; Edwards and Glysson, 1999). Thus, in comparison with 

an EDI or EWI measurement with relatively few verticals, an 

EDI or EWI measurement with many verticals is likely to have 

more verticals in regions near the sides of P.R. Jordan’s steady, 

uniform flow cross section, where velocities and suspended-sand 

concentrations are lower. This method of adding and repositioning verticals in a cross section leads to a relatively rapid decrease 

in the NOVE in the time-averaged velocity-weighted suspendedsand concentration as the number of verticals increases from 

one to about three, and then to a much more gradual decrease 

in the NOVE as the number of verticals exceeds about five. 

The details of how the NOVE in the time-averaged velocityweighted suspended-sand concentration is reduced as verticals 

are added depend on whether the measurement is made using 

the EDI or EWI method. When fewer than about three verticals 

are sampled, the NOVE associated with an EWI measurement 

greatly exceeds that associated with an EDI measurement, 

whereas when more than about three verticals are sampled, the 

NOVE associated with an EWI measurement is generally equal 

to or less than that associated with an EDI measurement. Under 

steady, uniform flow conditions, the NOVE associated with 

an EDI measurement should be positive, whereas the NOVE 

associated with an EWI measurement may be either positive or 

negative when fewer than ~10 verticals are sampled. 

Further analysis of simulated EDI and EWI measurements in a hypothetical trapezoidal river cross section with 

cross-stream structures in suspended-sand concentration

much different from those expected under steady, uniform 

flow over a full sand bed suggests that the exponent in the 

denominator of equation 17 may also differ from 0.7 where 

the flow is strongly nonuniform (that is, that the flow may be 

accelerating or decelerating, with potentially poor correlation 

between depth and velocity). The exponents derived from this 

exploratory analysis ranged from slightly greater than 0 in the 

cases where the cross-stream structure in the depth- and timeaveraged suspended-sand concentration was far less peaked 

(but with a small positive amplitude) than that expected under 

steady, uniform flow conditions to almost 2 in the cases where 

the cross-stream structure in the depth- and time-averaged 

suspended-sand concentration was far more peaked than that 

expected under steady, uniform flow conditions. Thus, the 

interaction of the nonrandom sampling protocols in EDI and 

EWI measurements with different nonrandom spatial structures in the depth- and time-averaged suspended-sand concentration results in sequential observations that may be either 

positively or negatively correlated. 

The cross-stream structure in the depth- and time-averaged suspended-sand concentration also affects the numerator 

in equation 17. When the cross-stream structure has a small, 

broad peak, this numerator can be substantially smaller than 

12.0. Conversely, when the cross-stream structure has a large, 

narrow peak, this numerator can exceed 100, that is, be about 

an order of magnitude larger. Where the depth- and time-averaged suspended-sand concentration is either uniform across 

the cross section or varies linearly across the cross section, this 

numerator is 0. 

Therefore, in a river cross section where the flow is 

strongly nonuniform, the magnitude of the NOVE in the timeaveraged velocity-weighted suspended-sand concentration 

may differ greatly from that in equation 17, and the reduction in the NOVE as verticals are added may be more rapid 

or more gradual than that expected by equation 17. Because 

of these complexities, future studies are justified to improve 

understanding of the NOVE under a wider range of conditions 

than those studied by P.R. Jordan (Guy and Norman, 1970; 

Edwards and Glysson, 1999) using Hubbell and others’ (1956) 

data from the Middle Loup River near Dunning, Nebraska. 

However, because the flow is generally uniform in the types of 

trapezoidal cross sections preferred as measurement sites by 

the USGS, the NOVE in the time-averaged velocity-weighted 

suspended-sand concentration described by equation 17 is 

probably reasonable for most field situations. 

In simple, trapezoidal cross sections like those sampled in 

this study and preferred as the geometry of the measurement 

cross section at USGS gaging stations, the random error arising from inadequate time averaging, MNOTE, is comparable 

to the NOVE when only a single vertical is sampled. Among 
Analysis 41

the single-vertical two-way depth-integrated data collected 

at the River-mile 30 sediment station (figs. 1, 2D), and at the 

Lower Marble Canyon and Grand Canyon gaging stations 

(figs. 2B, 2C), the mean ±1SE MNOTE in velocity-weighted 

suspended-sand concentration is 8.7±1.2 percent when a 

standard two-way (that is, two-transit) depth-integrated sample 

is collected at an individual vertical. Because the NOVE is 

expressed as a relative SE, direct comparison between the 

MNOTE and NOVE requires conversion of the MNOTE from 

a mean absolute error to a relative SE. As reviewed above, this 

conversion is done by dividing the MNOTE by 

	

0.8 n , where 

n=nvert=1 is the number of repeated, but separate, uncorrelated measurements at an individual vertical.10 This conversion yields a single-vertical MNOTESE (where the subscript 

“SE” denotes the standard-error form of the MNOTE) in the 

velocity-weighted suspended-sand concentration of 10.9±1.5 

percent when a standard two-transit depth-integrated sample is 

collected at an individual vertical. Among the two-way depthintegrated data collected at the River-mile 30 sediment station 

and at the Lower Marble Canyon and Grand Canyon gaging 

stations, the mean ±1SE MNOTE in the velocity-weighted 

suspended-silt and clay concentration is 4.9±2.2 percent when 

a standard two-transit depth-integrated sample is collected at 

an individual vertical, equivalent to a single-vertical MNOTESE

of 6.1±2.8 percent. Among the two-way depth-integrated data 

collected at the River-mile 30 sediment station and at the Lower 

Marble Canyon and Grand Canyon gaging stations, the mean 

±1SE D50MNOTE in the velocity-weighted median grain size of 

the suspended sand is 1.4±0.1 percent when a standard two-transit depth-integrated sample is collected at an individual vertical, 

equivalent to a single-vertical D50MNOTESE of 1.8±0.1 percent. 

These MNOTESE and D50MNOTESE values are used in equation 15 to solve for the MNOTE1,SE and D50MNOTE1,SE.11

Generalization of the single-vertical MNOTESE in the velocityweighted suspended-sand concentration for different numbers 

of transits then yields

 

MNOTESE = 15.4

ntrans

0.5 . (19)

Likewise, generalization of the single-vertical MNOTESE in 

the velocity-weighted suspended-silt-and-clay concentration 

for different numbers of transits yields

 

MNOTESE = 8.6

ntrans

0.5 , (20)

and generalization of the single-vertical D50MNOTESE in the 

velocity-weighted median grain size of suspended sand for 

different numbers of transits yields

 

D50MNOTESE = 2.5

ntrans

0.5

. (21)

10 A measurement at a vertical with two or eight transits is still only one 

single-vertical measurement; setting n equal to the number of transits at each 

vertical would be an overcorrection because the MNOTE already includes the 

effect of adding transits through its decrease by a factor of 1 ntrans

0.5 .

11 These terms are the standard-error forms of the MNOTE1 and 

D50MNOTE1.

An estimate of the total uncertainty associated with an 

EDI or EWI measurement (excluding laboratory-processing 

errors) requires (1) determining the behavior of the MNOTESE

as verticals are added to a measurement and (2) combining 

the quasi-systematic NOVE and the random multivertical 

MNOTESE. Step 1 was accomplished by using randomnumber simulations of suspended-sediment concentration in 

a hypothetical river cross section conducted separately for 

sand and for silt and clay. For these two sediment size classes, 

random-number simulations were conducted as follows. 

First, the time-averaged depth-integrated suspended-sediment 

concentrations at 15 verticals were evaluated by using a randomnumber generator.12 These values were used to construct 15 

cases where the time-averaged velocity-weighted suspendedsediment concentration in hypothetical river cross sections 

could be accurately determined from the time-averaged depthintegrated suspended-sediment concentrations measured at a 

progressively increasing number of verticals (from 1 to 15). 

For example, in the first case, time-averaged depth-integrated 

suspended-sediment measurements at only a single vertical 

would accurately measure the time-averaged velocity-weighted 

suspended-sediment concentration in the cross section, whereas 

in the 15th case, time-averaged depth-integrated suspendedsediment concentrations averaged among all 15 verticals would 

be required to accurately measure the time-averaged velocityweighted suspended-sediment concentration in the cross section. 

For each of these 15 cases, the time-averaged velocity-weighted 

suspended-sediment concentration in the cross section was 

calculated by averaging the time-averaged velocity-weighted 

suspended-sediment concentrations among the required number 

of verticals. These concentrations are the “true” values used in 

calculating the multivertical MNOTESEs in the fourth step in this 

analysis (described below). Second, 2,500 random numbers were 

generated at each vertical to describe 2,500 probable suspendedsediment concentrations measured by a depth-integrating 

sampler at each vertical in an EDI or EWI measurement. These 

random numbers were generated by assuming a Gaussian 

normal distribution of depth-integrated concentrations at each 

vertical, with a mean value equal to the imposed time-averaged 

suspended-sediment concentration at that vertical and a standard 

deviation equal to the single-vertical MNOTESE associated with 

the appropriate number of transits at that vertical. This procedure 

was done for measurements with two, four, and eight transits 

at each vertical, using the appropriate MNOTESE. Third, for 

the 1- to 15-vertical cases with two, four, and eight transits at 

each vertical, 2,500 values of the velocity-weighted suspendedsediment concentration were calculated by averaging the 

random-number-generated suspended-sediment concentrations 

among the different verticals. Fourth, for each scenario 

consisting of a given number of verticals and transits, these 

2,500 velocity-weighted suspended-sediment concentrations 

were used with the previously described true time-averaged 

12 Because the multivertical MNOTESE is a relative SE, the multivertical 

MNOTESEs calculated from the random-number simulations do not depend on 

the values of the concentrations at these 15 verticals.
42 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

velocity-weighted suspended-sediment concentrations to 

calculate a relative mean absolute error in the time-averaged 

velocity-weighted suspended-sediment concentration in an 

EDI or EWI measurement consisting of 1 through 15 verticals, 

with two, four, and eight transits at each vertical. Each relative 

mean absolute error was then converted to a relative standard 

error by dividing by 

	

0.8 n , where n=1 for one EDI or EWI 

measurement. Results from these random-number simulations 

for 1- to 15-vertical EDI or EWI measurements with two, four, 

and eight transits at each vertical are listed in table 9. 

Simplification of the results listed in table 9 can be 

obtained through use of an equation similar in form to 

equation 15, where the multivertical MNOTESE is given by

 

MNOTE

MNOTE

SE

SE trans

vert

= 1

0 5

,

. n

nγ , (22)

where g is now the exponent describing the behavior of the 

MNOTESE as verticals are added. Use of the appropriate 

values of the MNOTE1,SE from the numerators in equations 

19 and 20 and then solving for g by log-transforming the 

data and using least-squares linear regression yields the following results. For the suspended-sand cases, g=0.475 with 

two transits at each vertical, g=0.458 with four transits at 

each vertical, and g=0.469 with eight transits at each vertical. Similarly, for the suspended-silt-and-clay cases, g=0.464 

with two transits at each vertical, g=0.480 with four transits at 

each vertical, and g=0.466 with eight transits at each vertical. 

Thus, for all cases, g≈0.5, indicating that the behavior of the 

MNOTESE as verticals are added is identical to the behavior 

of an SE as uncorrelated observations are added. As in the 

case of additional transits at a vertical, additional verticals also 

behave as uncorrelated observations in their influence on the 

multivertical MNOTESE. The general form of the multivertical MNOTESE to be used in estimating the total uncertainty in 

the EDI- or EWI-measured time-averaged velocity-weighted 

suspended-sediment concentration therefore becomes

 

MNOTESE = MNOTE1,SE

ntransnvert

. (23)

As reviewed by Taylor (1997), the most conservative, 

and safest, way to combine systematic and (or) random errors 

into an estimate of the total uncertainty in a measurement is 

to keep the individual errors separate. If the individual errors 

are strongly correlated, then this conservative approach is also 

likely the only valid approach. By this conservative approach, 

the EDI- or EWI-measured time-averaged velocity-weighted 

concentration of sediment in size class m, excluding laboratory-processing errors, would be reported as 

 . (24)

The cm/100 terms in equation 24 are required to convert the 

relative standard errors NOVE and MNOTESE (expressed as 

percentages) into standard errors expressed in the same units 

as cm. In this form, the EDI- or EWI-measured time-averaged 

cm ± NOVE

cm

100

± MNOTESE

cm

100

Table 9. Results from random-number simulations to determine 

the behavior of the standard-error form of the multivertical mean 

number-of-transits error (MNOTESE).

Sediment 

size class

Number of verticals required

to accurately measure timeaveraged velocity-weighted 

suspended-sediment

concentration in cross section

Number 

of transits 

at each 

vertical

MNOTESE 

(%)

sand 1 2 11.00*

sand 1 4 7.80*

sand 1 8 5.42*

sand 2 2 7.75

sand 2 4 5.48

sand 2 8 3.77

sand 3 2 6.36

sand 3 4 4.61

sand 3 8 3.06

sand 4 2 5.51

sand 4 4 3.98

sand 4 8 2.68

sand 5 2 4.95

sand 5 4 3.58

sand 5 8 2.47

sand 6 2 4.55

sand 6 4 3.29

sand 6 8 2.25

sand 7 2 4.24

sand 7 4 3.05

sand 7 8 2.17

sand 8 2 3.96

sand 8 4 2.85

sand 8 8 2.02

sand 9 2 3.83

sand 9 4 2.81

sand 9 8 1.90

sand 10 2 3.61

sand 10 4 2.65

sand 10 8 1.79

sand 11 2 3.45

sand 11 4 2.50

sand 11 8 1.71

sand 12 2 3.32

sand 12 4 2.39

sand 12 8 1.65

sand 13 2 3.17

sand 13 4 2.27

sand 13 8 1.57

sand 14 2 3.13

sand 14 4 2.40

sand 14 8 1.52

sand 15 2 3.02
Analysis 43

velocity-weighted suspended-sand concentration in a 

simple trapezoidal channel, after making the appropriate substitutions, is expressed as 

 

, (25)

and the EDI or EWI-measured time-averaged velocityweighted concentration of silt and clay in a simple trapezoidal channel, after making the appropriate substitutions, is 

expressed as

 

 

 . (26)

Another, slightly more liberal approach is to actually sum 

the individual errors in quadrature, where the relative total 

uncertainty (TU), excluding laboratory-processing errors, is 

given by

 

	

TU = ( ) NOVE 2+ ( ) MNOTESE

2

. (27)

This approach to combining systematic and random errors 

into a single TU is especially justified in situations where (1) 

the individual errors are not strongly correlated, (2) the sign 

associated with the systematic error cannot be known before a 

measurement, or (3) the systematic error is really random over 

much longer time scales than the random error, as in an EDI or 

EWI measurement (that is, the systematic error is really quasisystematic). As shown in this study, stable spatial cross-stream 

structures in suspended-sand and suspended-silt-and-clay 

concentration can persist for hours and then change overnight 

into different stable spatial structures or disappear altogether. 

Therefore, an identical number and position of verticals used 

to sample a cross section may lead to a positive NOVE on the 

first day and a negative NOVE on the next day. 

csand ± 12.0

nvert

0.7

















csand

100





 



 ± 15.4

ntransnvert

















csand

100





 





csilt-clay ± 0

nvert

0.7

















csilt-clay

100

















± 8.6

ntransnvert

















csilt-clay

100

















Table 9. Results from random-number simulations to determine 

the behavior of the standard-error form of the multivertical mean 

number-of-transits error (MNOTESE).—Continued

Sediment 

size class

Number of verticals required 

to accurately measure timeaveraged velocity-weighted 

suspended-sediment 

concentration in cross section

Number 

of transits 

at each 

vertical

MNOTESE 

(%)

sand 15 4 2.28

sand 15 8 1.48

silt and clay 1 2 6.03*

silt and clay 1 4 4.39*

silt and clay 1 8 2.96*

silt and clay 2 2 4.22

silt and clay 2 4 3.05

silt and clay 2 8 2.12

silt and clay 3 2 3.41

silt and clay 3 4 2.47

silt and clay 3 8 1.74

silt and clay 4 2 2.99

silt and clay 4 4 2.16

silt and clay 4 8 1.51

silt and clay 5 2 2.64

silt and clay 5 4 1.89

silt and clay 5 8 1.35

silt and clay 6 2 2.42

silt and clay 6 4 1.72

silt and clay 6 8 1.23

silt and clay 7 2 2.30

silt and clay 7 4 1.66

silt and clay 7 8 1.17

silt and clay 8 2 2.20

silt and clay 8 4 1.55

silt and clay 8 8 1.10

silt and clay 9 2 2.12

silt and clay 9 4 1.53

silt and clay 9 8 1.07

silt and clay 10 2 2.01

silt and clay 10 4 1.43

silt and clay 10 8 1.01

silt and clay 11 2 1.91

silt and clay 11 4 1.36

silt and clay 11 8 0.96

silt and clay 12 2 1.84

silt and clay 12 4 1.30

silt and clay 12 8 0.91

silt and clay 13 2 1.76

silt and clay 13 4 1.24

silt and clay 13 8 0.88

silt and clay 14 2 1.73

silt and clay 14 4 1.21

Table 9. Results from random-number simulations to determine 

the behavior of the standard-error form of the multivertical mean 

number-of-transits error (MNOTESE).—Continued

Sediment 

size class

Number of verticals required 

to accurately measure timeaveraged velocity-weighted 

suspended-sediment 

concentration in cross section

Number 

of transits 

at each 

vertical

MNOTESE 

(%)

silt and clay 14 8 0.86

silt and clay 15 2 1.69

silt and clay 15 4 1.15

silt and clay 15 8 0.83

*

 These values are only slightly different from the values for the single-vertical MNOTESEs computed using equations 19 and 20 that are used as input 

to the random-number simulations, indicating that the number of random 

numbers generated to describe probable concentrations at each vertical in 

these simulations is sufficient. 
44 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

The approach to combining the NOVE and MNOTESE

into a single TU is mathematically advantageous and leads to 

the following form of reporting the EDI- or EWI-measured 

time-averaged velocity-weighted concentration of sediment in 

size class m: 

 . (28)

In this form, the EDI- or EWI-measured time-averaged 

velocity-weighted suspended-sand concentration in a simple 

trapezoidal channel, after making the appropriate substitutions, 

is expressed as 

, (29)

and the EDI- or EWI-measured time-averaged velocityweighted concentration of silt and clay in a simple trapezoidal channel, after making the appropriate substitutions, is 

expressed as

 

. (30)

The relative total uncertainty (equation 27), NOVE, and 

MNOTESE in suspended-sand concentration for EDI and EWI 

measurements composed of different numbers of verticals are 

plotted in figure 15, which indicates that (1) adding verticals 

is slightly more effective in reducing the TU than is only 

adding transits at each vertical, and (2) doubling the number 

of transits at each vertical from two to four is more effective 

in reducing the TU than is doubling the number of transits at 

each vertical from four to eight. For example, the TU with 

four transits at five verticals is approximately the same as 

that with two transits at seven verticals, whereas the TU with 

eight transits at five verticals is approximately the same as 

that with four transits at six verticals. In many field situations, 

transits may be easier to add than verticals. However, the 

amount of reduction in the TU decreases progressively less 

rapidly as the number of transits increases, thus making the 

addition of verticals more desirable than the addition of many 

more transits at each vertical. As shown in the data tables for 

noncomposited nine-vertical measurements in appendix A, 

it typically takes more time to move from one vertical to the 

next in a cross section and begin sampling at that new vertical 

than to simply add transits at a vertical. Thus, adding verticals 

has the negative effect of increasing the total time required 

to complete an EDI or EWI measurement at a higher rate 

than does increasing the number of transits at each vertical. 

Therefore, the best EDI or EWI sampling design to minimize 

the TU in time-averaged velocity-weighted suspended-sand 

concentration is to collect four transits at as many verticals as 

is practical. 

To determine whether the TU formulated in equations 

29 and 30 was consistent with field observations, and whether 

the TU was better at explaining field observations than the 

NOVE (the only formulation of EDI- or EWI-measurement 

error currently used by the USGS), we conducted a final 

cm ± TU cm

100





 



 or cm ± ( ) NOVE 2

+ MNOTE ( ) SE

2 cm

100





 





csand ± 12.0

nvert

0.7

















2

+

15.4

ntransnvert

















2

csand

100





 





csilt-clay ± 0

nvert

0.7

















2

+

8.6

ntransnvert

















2

csilt-clay

100

















analysis using noncomposited EWI measurements configured 

into different sampling designs. As described previously, 

these sampling designs consisted of EWI measurements at 

one, three, five, and nine verticals (fig. 4). The data used 

to calculate the velocity-weighted suspended-sediment 

concentration under these different EWI sampling designs 

were the 30 noncomposited nine-vertical depth-integrated 

measurements made at the five cross sections at the Rivermile 30 sediment station (figs. 1, 2D) and the Lower Marble 

Canyon gaging station (fig. 2C).13 The 30 noncomposited 

nine-vertical depth-integrated measurements were not used 

in any way to calculate MNOTESE values, nor were these 

data used to place constraints on the NOVE. Therefore, 

this analysis is an independent evaluation of whether the 

behaviors of the TU and (or) NOVE are consistent with field 

observations. 

Because the MNOTESE and NOVE are derived as relative 

SEs, and the TU calculated by summing these two errors 

in quadrature is therefore also a relative SE, the confidence 

intervals associated with each of these three errors must 

behave in the same way as do those associated with any SE. 

Therefore, because of the normal distribution of sample means 

about the population mean by the central-limit theorem, the 

probability that the population mean falls within an interval 

defined by the SE (that is, the confidence interval), is 

 

, (31) 

where P is the cumulative probability, or confidence interval, 

and nSE is the number of SEs defining the width of this interval 

(after Zelen and Severo, 1964). In the general case, if we can 

measure the same quantity ψ (that is, the population mean) 

with m different sampling designs, if the formulation of the SE 

associated with these sampling designs is accurate, and if the 

number of times n (that is, sample size) all of these m different 

sampling designs are used to measure ψ is sufficiently large, 

then the empirically determined cumulative probability within 

this sufficiently large sample size n that the number of SEs at 

which all m sampling designs measure the same value of ψ

must behave similarly to that in equation 31. In this specific 

case, 30 noncomposited nine-vertical EWI measurements were 

made that could be mathematically combined into four different 

sampling designs, with one, three, five, and nine verticals. These 

30 noncomposited EWI measurements were analyzed by using 

these different sampling designs to evaluate whether the TU 

derived in this study and (or) NOVE behaved consistently with 

that expected by equation 31. For the purposes of this analysis, 

in each of the 30 cases the population mean, ψ, was set equal 

to the concentration among the four EWI sampling designs that 

agreed at the minimum SE; this concentration is referred to 

below as the “optimal concentration of agreement.”

The analysis of the 30 noncomposited nine-vertical 

depth-integrated measurements was conducted as follows. 

For each of the 30 measurements, (1) the velocity-weighted 

13 These 30 noncomposited nine-vertical measurements include the above 

analyzed 22 measurements made hours apart on the same day.

P = erf nSE

2





 




Analysis 45

concentration of suspended-sediment in two size classes 

(sand, and silt and clay) was calculated for EWI measurements composed of one, three, five, and nine verticals (figs. 4, 

16A, 16B); (2) the TU in concentration for each of these four 

EWI sampling designs was calculated by using equation 27 

(fig. 16A); (3) the NOVE in concentration for each of these four 

EWI sampling designs was calculated by using equation 1714

(fig. 16B); (4) the optimal concentration of agreement ψ (that is, 

the assumed population mean) among the four EWI sampling 

designs was defined to fall within the search domain bounded 

by the minimum and maximum concentrations (ψmin and ψmax, 

respectively) calculated among the four EWI sampling designs 

14 Because P.R. Jordan assumed that suspended silt and clay was uniformly 

distributed in a cross section, the NOVE in suspended-silt-and-clay 

concentration is always zero (equation 18) and so this analysis could not be 

conducted for silt and clay.

(figs. 16A, 16B); (5) within this search domain, a ψ value was 

obtained that minimized the number of SEs,15 nSE, best, at which 

the concentrations measured among all four EWI sampling 

designs agreed (fig. 16C); (6) the cumulative probability associated with nSE, best within the sample size of 30 measurements 

was calculated; and finally, (7) this empirical cumulative probability was compared with the theoretical cumulative probability expected by equation 31 for a given nSE, best (fig. 17). The 

most complicated part of this analysis was the determination 

of ψ in step 5, which was itself a four-step process: (1) the 

search domain bounded by ψmin and ψmax was divided into a 

continuum of extremely small increments, (2) for each of these 

small increments in concentration, the maximum nSE (that is, 

nSE, max) was determined at which the concentrations measured 

among all four EWI sampling designs agreed (figs. 16A, 16B), 

(3) nSE, best was then evaluated as the minimum nSE, max over the 

search domain (fig. 16C), and (4) the optimal concentration of 

agreement ψ was thus determined as the concentration associated with nSE, best (figs. 16A, 16B). By this approach, nSE, best

was thus the minimum number of SEs at which the concentration measured among all four EWI sampling designs agreed. 

Results from this analysis indicate that over the entire 

range of suspended-sand concentrations in this analysis, the 

TU (equation 27) provides a substantially better characterization of the error in an EWI measurement of the time-averaged 

velocity-weighted suspended-sand concentration in a cross 

section than does the NOVE (equation 17). As shown in figure 

17A, the empirical cumulative probability associated with 

the TU behaves much more like the theoretical cumulative 

probability expected by equation 31 than does the empirical 

cumulative probability associated with the NOVE. Furthermore, analysis of variance using a standard F-test indicates 

that at the p=0.05 level of significance, for neither the TU nor 

the NOVE is there significant dependence of the nSE, best values 

on suspended-sand concentration (fig. 18A). Use of the TU 

instead of the NOVE results in a mean 28-percent reduction in 

nSE, best among the 30 measurements.

The results of this analysis indicate that at moderate to 

high suspended-silt-and-clay concentrations, the TU (equation 27) reasonably captures the behavior of the error in an 

EWI measurement of the time-averaged velocity-weighted 

suspended-silt-and-clay concentration in a cross section, 

whereas the behavior of the NOVE (equation 18) is inconsistent with the behavior of this error. As derived by P.R. 

Jordan, the NOVE in suspended-silt-and-clay concentration 

is zero because he assumed that suspended silt and clay is 

uniformly distributed in a cross section (Guy and Norman, 

1970; Edwards and Glysson, 1999). However, suspended silt 

and clay was not uniformly distributed across any of the five 

cross sections at the River-mile 30 sediment station (figs. 1, 

2D) and the Lower Marble Canyon gaging station (fig. 2C) 

when the mean suspended-silt-and-clay concentration in 

the cross section was less than about 50 mg/L (fig. 14; see 

15 The number of intervals of TU calculated by equation 27 or NOVE 

calculated by equation 17.

Figure 15. Comparison of number-of-verticals relative standard 

error (NOVE), mean number-of-transits relative standard error 

(MNOTESE), and relative total uncertainty in equal-dischargeincrement (EDI)- or equal-width-increment (EWI)-measured 

suspended-sand concentration in a simple trapezoidal channel. 

Relative total uncertainties were calculated by using equation 27 

for EDI or EWI measurements with two, four, and eight transits 

at each vertical; MNOTESE was calculated only for an EDI or EWI 

measurement with two transits at each vertical.

NOVE, MNOTE

SE

, or TOTAL UNCERTAINTY, IN PERCENT NOVE, MNOTE , OR TOTAL UNCERTAINTY, SE IN PERCENT

0

5

10

15

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

NOVE

MNOTESE

Total uncertainty with two transits at each vertical

Total uncertainty with four transits at each vertical

Total uncertainty with eight transits at each vertical 

NOVE, MNOTE

SE

, or TOTAL UNCERTAINTY, IN PERCENT

NUMBER OF VERTICALS

EXPLANATION
46 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure 16. Examples of equal-width-increment (EWI)-measured suspended-sand concentrations, with error bars, for four different 

EWI sampling designs, showing key steps in analysis of behaviors of total uncertainty and number-of-verticals error (NOVE). Data points 

were calculated by using noncomposited nine-vertical measurement made along cross section B at the River-mile 30 sediment station 

between 8:03 and 8:37 a.m. on August 25, 2007. A, Error bars calculated for a total-uncertainty interval of nSE=1, using equation 27. B, 

Error bars calculated for a NOVE interval of nSE=1, using equation 17. In figures 16A and 16B, dashed horizontal lines indicate the bounds 

of the search domain for ψ defined by the minimum (ψmin) and maximum (ψmax) concentrations calculated among the four EWI sampling 

designs. Thick, solid horizontal lines indicate “optimal concentration of agreement” ψ value determined in this analysis. Values of nSE in 

red indicate the required value of nSE for each EWI sampling design to result in agreement in concentration among all four EWI sampling 

designs. Maximum of these nSE values, nSE, max, is value minimized over search domain between ψmin and ψmax to solve for ψ. C, Values of 

nSE, max among four EWI sampling designs over search domain between ψmin and ψmax. Minimum nSE, max values are nSE, best values 

(indicated in figures 16A and 16B) used to solve for ψ in figures 16A and 16B. 

100

110

120

130

140

150

0 1 2 3 4 5 6 7 8 9 10

ψ = 126.21 mg/L

n

SE

 = 0.775 n

SE

 = 0.027

n

SE, max

 = 0.776

n

SE

 = 0.266

n

SE, best

ψ max

ψ min

100

110

120

130

140

150

0 1 2 3 4 5 6 7 8 9 10

ψ = 125.83 mg/L

n

SE

 = 1.218

n

SE

 = 0.035

n

SE, max

 = 1.221

n

SE

 = 0.333

n

SE, best

ψ max

ψ min

0

1

2

3

4

5

115 120 125 130 135 140

nSE, max for total uncertainty 

nSE, max for NOVE

EWI-MEASURED 

SUSPENDED-SAND CONCENTRATION,

IN MILLIGRAMS PER LITER

c

min

c

max

n

SE, best

n

SE, best

 EWI-MEASUREDSUSPENDED-SAND CONCENTRATION, IN MILLIGRAMS PER LITER

A B

NUMBER OF VERTICALS IN EWI SAMPLING DESIGN

C

n SE, max
Analysis 47

appendixes A, B). As shown in figure 17B, the agreement 

between the empirical cumulative probability associated 

with the TU in suspended-silt-and-clay concentration and 

the theoretical cumulative probability expected by equation 

31 is poor in comparison with the good agreement between 

the empirical and theoretical cumulative probabilities in 

figure 17A for suspended-sand concentration. This relatively 

poor agreement is the result of the behavior of the TU at 

low suspended-silt-and-clay concentrations. In contrast to 

the results for the TU in suspended-sand concentration, 

analysis of variance using a standard F-test indicates that 

at the p=0.05 level of significance, the values of nSE, best

depend significantly on suspended-silt-and-clay concentration (fig. 18B). Removal of the cases from the analysis with 

suspended-silt-and-clay concentrations <50 mg/L results in 

a much better agreement between the empirical and theoretical cumulative probabilities associated with the TU in 

suspended-silt-and-clay concentration (fig. 17A) and removes 

the significant dependence of the nSE, best values associated with the TU on suspended-silt-and-clay concentration 

(fig. 18B). Importantly, the MNOTESE used to calculate the 

TU in suspended-silt-and-clay concentration was partly 

derived using data collected at the River-mile 30 sediment 

station when the suspended-silt-and-clay concentration was 

<50 mg/L. Therefore, the relatively poor characterization of 

error by the TU (equation 30) at low suspended-silt-and-clay 

concentrations likely results from incorrect parameterization 

of the NOVE and not the MNOTESE at low suspended-siltand-clay concentrations. Again, because stable cross-stream 

structures in suspended-silt-and-clay concentration have 

been observed to persist between measurements spaced hours 

apart, laboratory-processing errors cannot be used to entirely 

explain this behavior. These observations together suggest 

that at least at lower suspended-silt-and-clay concentrations, 

the NOVE should likely be a small positive number, not zero 

as assumed by P.R. Jordan. 

In summary, results from this final analysis of error 

behavior indicate that (1) the TU is a much better estimator 

than is the NOVE of the error in an EWI measurement 

of the time-averaged velocity-weighted suspended-sand 

concentration in a cross section, (2) because P.R. Jordan’s 

parameterization of the NOVE is incapable of describing 

error in suspended-silt-and-clay concentration, the TU is also 

a much better estimator than is the NOVE of the error in an 

EWI measurement of the time-averaged velocity-weighted 

suspended-silt-and-clay in a cross section, and (3) at lower 

suspended-silt-and-clay concentrations (that is, less than about 

50 mg/L), the NOVE of zero derived by P.R. Jordan may 

Figure 17. Comparison of empirical and theoretical relations between nSE, best and cumulative probability, or confidence interval, for 

total uncertainty (TU) and number-of-verticals error (NOVE). A, Cumulative probability plotted as a function of nSE, best for TU and NOVE 

in time-averaged velocity-weighted suspended-sand concentration in a cross section compared with the theoretical relation between 

nSE and cumulative probability (equation 31). B, Cumulative probability plotted as a function of nSE, best for TU in time-averaged velocityweighted suspended-silt-and-clay concentration in a cross section compared with the theoretical relation between nSE and cumulative 

probability (equation 31). Shown are the empirical relations calculated for all 30 noncomposited nine-vertical measurements and for 

only those measurements with an “optimal concentration of agreement” >50 mg/L.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 1 2 3 4 5 6 7 8 9 10

Total uncertainty, 

all 30 measurements

Total uncertainty, 

only measurements with 

concentrations > 50 mg/L 

Equation 31

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Total uncertainty 

NOVE

Equation 31

CUMULATIVE PROBABILITY OR  CONFIDENCE INTERVAL

A B

n SE, best
48 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

be incorrect. Although this analysis was conducted for EWI 

measurements, there is no physical reason why the results 

from this analysis should not also apply to EDI measurements.

Conclusions

When depth-integrating samplers are properly used in the 

field, the two most common sources of error are (1) inadequate 

sampling of the cross-stream spatial structure in suspendedsediment concentration and (2) the inability of these samplers 

to collect adequate time-averaged data during standard 

operation, when only two transits are collected at each vertical 

in a cross section. Both of these errors must be included in an 

estimate of the TU in an EDI or EWI measurement. Though 

outside the scope of this study, laboratory-processing errors 

must also be included in a completely comprehensive estimate 

of the TU in an EDI or EWI measurement. The error arising 

from inadequate time averaging (1) is positively correlated 

with grain size, (2) does not depend on elevation above the 

bed for any given size class of sediment, and (3) does not 

largely depend on flow conditions. An average of 1 minute 

is the likely minimum duration of time averaging required 

to result in substantial decreases in this error. As the number 

of transits is doubled at an individual vertical, this error is 

reduced by ~30 percent in each size class of sediment. For a 

given size class of sediment, the error arising from inadequate 

sampling of the cross-stream spatial structure in suspendedsediment concentration depends only on the number of 

verticals collected, whereas the error arising from inadequate 

time averaging depends on both the number of verticals 

collected and the number of transits collected at each vertical.

Exclusive of laboratory-processing errors (which are 

typically small), the TU in suspended-sand and suspendedsilt-and-clay concentrations is dominated by the random 

error arising from inadequate time averaging. When two 

transits are collected at five verticals in a simple trapezoidal 

channel, the TU in the EDI- or EWI-measured suspended-sand 

concentration calculated by using both the errors arising from 

(1) inadequate sampling of the cross-stream spatial structure 

Figure 18. Evaluation of the dependence of nSE, best associated with total uncertainty (TU) and number-of-verticals error (NOVE) on 

the “optimal concentration of agreement” (ψ). Values of nSE, best plotted as a function of ψ for suspended sand (A) and suspended 

silt and clay (B) in the 30 noncomposited nine-vertical depth-integrated measurements. A, Values of nSE, best associated with TU and 

NOVE, with best-fit linear regressions, plotted as a function of ψ for suspended sand. Both regressions are insignificant at the p=0.05 

level, indicating no significant dependence of nSE, best on suspended-sand concentration for either the TU or NOVE. B, Values of nSE, 

best associated with TU, with best-fit linear regression, plotted as a function of ψ for suspended silt and clay. Removal of cases with 

suspended-silt-and-clay concentrations <50 mg/L (indicated by vertical dashed line) results in an increase in the level of significance of 

this regression from p=0.0046 to p=0.77. 

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

10 100 1,000

Total uncertainty 

NOVE

OPTIMAL CONCENTRATION OF AGREEMENT, ψ, 

FOR SUSPENDED SAND

AMONG ALL FOUR EWI SAMPLING DESIGNS, 

IN MILLIGRAMS PER LITER

nSE, best = 1.0 - 0.0013ψ, R2 = 0.036, p = 0.32

nSE, best = 1.2 - 0.00022ψ, R2 = 0.00067, p = 0.89

0

1

2

3

4

5

6

7

8

9

10

10 100 1,000 10,000

Total uncertainty

OPTIMAL CONCENTRATION OF AGREEMENT, ψ,

FOR SUSPENDED SILT AND CLAY

AMONG ALL FOUR EWI SAMPLING DESIGNS, 

IN MILLIGRAMS PER LITER

nSE, best = 3.2 - 0.00038ψ, R2 = 0.25, p = 0.0046

50 mg/L

A B

n SE, best

n SE, best
References Cited 49

in suspended-sand concentration and from (2) inadequate 

time averaging at each vertical is ~6.3 percent (expressed as 

a relative SE). For comparison, the error arising only from 

inadequate sampling of the cross-stream spatial structure in 

suspended-sand concentration for this case is ~3.9 percent, 

and the error arising only from inadequate time averaging at 

each vertical in this case is ~4.9 percent. When two transits 

are collected at five verticals in a simple trapezoidal channel, 

the TU in the EDI- or EWI-measured suspended-silt-andclay concentration results almost entirely from inadequate 

time averaging at each vertical and is ~2.7 percent (at least 

at suspended-silt-and-clay concentrations in excess of about 

50 mg/L). Therefore, the error arising from inadequate 

time averaging will likely be the dominant error introduced 

during the calibration of other approaches to measuring 

suspended-sediment concentration (for example, automatic 

pump samplers, optical backscatter, laser diffraction, or 

acoustic attenuation and backscatter) if too few EDI or EWI 

measurements are used in these calibrations.

Although adding verticals to an EDI or EWI 

measurement is slightly more effective in reducing the TU 

than is only adding transits at each vertical (because additional 

verticals reduce both spatial and temporal errors), adding a 

combination of verticals and transits is likely a more practical 

approach to reducing the TU in real field situations. In many 

field situations, it may be easier to add transits than to add 

verticals because it typically takes much less time to collect 

depth-integrated samples at additional transits at a vertical 

than to collect depth-integrated samples at additional verticals 

in a cross section. However, because the reduction in the TU 

decreases progressively less rapidly as the number of transits 

increases, it does not usually make sense to collect more than 

four transits at each vertical. Therefore, the best EDI or EWI 

sampling design to minimize the TU in the time-averaged 

velocity-weighted suspended-sediment concentration is to 

double the number of transits collected during standard twoway depth integration and to collect four transits at as many 

verticals as is practical for a given field situation. 

References Cited

Allen, P.B., and Petersen, D.V., 1981, A study of the variability 

of suspended sediment measurements, in Erosion and sediment transport measurement; Proceedings of the Florence 

Symposium, June 1981: International Association of Hydrological Sciences publication 133, p. 203–211.

Best, J., 2005, The fluid mechanics of river dunes; a review 

and some future research directions: Journal of Geophysical 

Research, v. 110, F04S02, 21 p., doi:10.1029/2004JF000218

[http://www.agu.org/journals/jf/jf0504/2004JF000218/200

4JF000218.pdf].

Bevington, P., and Robinson, D.K., 2003, Data reduction and 

error analysis for the physical sciences (3d ed.): New York, 

McGraw-Hill, 320 p.

Colby, B.R., 1963, Fluvial sediments—a summary of source, 

transportation, deposition, and measurement of sediment 

discharge: U.S. Geological Survey Bulletin 1181-A, 47 p. 

[http://pubs.er.usgs.gov/usgspubs/b/b1181A].

Colby, B.R., 1964, Discharge of sands and mean-velocity 

relationships in sand-bed streams: U.S. Geological Survey 

Professional Paper 462-A, 47 p. [http://pubs.er.usgs.gov/

usgspubs/pp/pp462A]. 

Davis, J.C., 1986, Statistics and data analysis in geology (2d 

ed.): New York, John Wiley and Sons, 646 p.

Dietrich, W.E., 1982, Settling velocity of natural particles: 

Water Resources Research, v. 18, p. 1615–1626 [http://

www.agu.org/journals/wr/v018/i006/WR018i006p01615/

WR018i006p01615.pdf].

Dinehart, R.L., 1998, Sediment transport at gaging stations near 

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Appendix A 53

Appendix A. Suspended-Sediment Data
Data collected at the Cisco gaging station P-61 suspended-sediment samples collected at the Cisco gaging station on May 10, 1995; vertical located at the station 385 ft from the left-bank bridge abutment

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:30 Point 6.25 0.11 16.00 0.779 619 2,420 0.8 1.4 2.4 3.1 4.2 6.4 9.4 14.5 21.5 38.7 68.4 93.0 98.5 99.9 100.0 100.0 115:33 Point 6.25 0.11 16.00 0.422 532 921 3.0 9.0 9.8 14.7 18.7 25.1 28.0 32.0 42.6 56.3 77.0 93.3 100.0 100.0 100.0 100.0 115:40 Point 6.25 0.11 16.00 0.790 638 884 1.5 4.3 6.7 10.3 12.7 18.0 23.9 30.8 39.8 53.8 73.5 92.5 95.9 100.0 100.0 100.0 115:45 Point 6.25 0.11 16.00 0.421 659 1,930 0.2 0.5 1.0 2.2 3.5 5.8 6.8 12.4 18.7 34.7 69.2 90.9 96.5 100.0 100.0 100.0 115:50 Point 6.25 0.11 16.00 0.183 720 3,280 0.0 0.3 1.2 3.4 4.0 5.2 8.6 12.0 19.0 35.1 60.4 87.0 94.7 98.4 100.0 100.0 115:55 Point 6.25 0.26 16.00 0.121 862 9,170 0.0 1.0 1.6 2.0 2.8 4.5 4.7 7.9 11.8 20.3 41.0 77.0 93.3 97.2 100.0 100.0 116:00 Point 6.25 0.26 16.00 0.203 621 39,800 0.1 0.5 0.6 0.7 0.8 1.0 1.1 1.9 4.9 18.7 48.7 75.2 91.4 97.7 98.9 100.0 116:03 Point 6.25 0.26 16.00 0.405 675 38,200 0.0 0.1 0.1 0.1 0.2 0.6 1.2 2.1 4.9 14.4 37.5 66.1 84.9 97.3 98.7 99.0 16:07 Point 6.25 0.26 16.00 0.744 695 5,310 0.0 0.7 1.9 2.8 3.1 4.6 6.7 9.6 13.2 17.3 30.8 54.9 75.0 92.0 94.2 94.9 16:11 Point 6.25 0.26 16.00 0.559 656 3,330 0.5 0.9 1.2 2.1 3.2 6.0 9.6 14.2 21.5 31.3 49.8 78.5 95.3 99.0 100.0 100.0 116:14 Point 6.25 0.57 16.00 1.042 590 1,020 1.4 3.0 5.6 7.2 11.7 15.6 21.0 26.4 35.9 50.2 77.1 94.2 97.7 100.0 100.0 100.0 116:18 Point 6.25 0.57 16.00 1.021 648 1,320 0.7 1.5 2.7 4.2 5.9 8.4 13.7 20.4 28.4 41.8 73.1 95.7 100.0 100.0 100.0 100.0 116:22 Point 6.25 0.57 16.00 0.897 639 726 0.0 1.2 2.4 4.4 5.7 9.7 17.4 24.7 35.9 59.9 79.0 93.0 100.0 100.0 100.0 100.0 116:25 Point 6.25 0.57 16.00 0.866 600 1,120 1.9 3.4 5.5 7.0 9.7 12.7 20.6 27.3 36.3 52.6 83.3 97.1 100.0 100.0 100.0 100.0 116:29 Point 6.25 0.57 16.00 0.421 628 2,890 0.2 0.3 0.9 2.4 4.2 5.7 9.8 14.0 21.5 33.4 60.9 90.1 95.5 97.5 100.0 100.0 116:33 Point 6.25 0.87 16.00 0.801 652 413 2.2 12.0 15.5 21.6 29.9 35.5 40.5 49.2 58.2 71.8 87.5 98.5 100.0 100.0 100.0 100.0 116:36 Point 6.25 0.87 16.00 0.976 807 1,850 3.2 5.6 10.2 15.0 19.5 26.3 30.7 36.5 46.4 64.4 83.1 94.0 98.6 100.0 100.0 100.0 116:51 Point 6.25 0.87 16.00 1.025 573 535 0.6 4.3 5.7 12.2 21.4 26.9 32.9 40.1 51.7 66.4 83.4 94.8 97.8 100.0 100.0 100.0 116:55 Point 6.25 0.87 16.00 0.966 585 887 1.9 3.9 6.0 8.6 10.8 14.5 20.5 24.5 33.0 45.4 69.2 91.3 97.2 100.0 100.0 100.0 116:59 Point 6.25 0.87 16.00 0.922 618 525 1.5 5.8 10.0 11.7 17.9 21.4 28.3 34.2 40.8 53.4 73.2 91.5 95.2 95.8 100.0 100.0 117:03 Point 6.25 0.87 16.00 0.753 683 536 4.1 6.5 8.4 14.7 20.3 27.8 32.9 37.9 49.0 64.2 78.7 93.5 94.2 94.5 100.0 100.0 117:07 Point 6.25 1.48 16.00 1.205 609 240 6.2 10.9 17.1 24.7 35.0 46.1 59.1 71.3 79.0 87.2 97.2 100.0 100.0 100.0 100.0 100.0 117:10 Point 6.25 1.48 16.00 1.112 622 255 4.1 10.1 17.1 23.5 34.4 44.9 58.6 68.2 78.7 86.2 95.9 99.7 100.0 100.0 100.0 100.0 117:13 Point 6.25 1.48 16.00 1.063 594 238 4.6 9.4 17.3 24.4 36.4 45.6 57.6 68.1 75.5 84.9 94.5 95.6 97.7 100.0 100.0 100.0 117:16 Point 6.25 1.48 16.00 0.998 618 284 6.3 13.9 18.2 23.7 29.9 41.8 54.7 59.7 70.6 80.7 90.3 91.5 91.7 100.0 100.0 100.0 117:20 Point 6.25 1.48 16.00 1.043 639 332 2.2 9.5 12.2 19.2 28.3 34.7 38.5 49.7 60.5 73.7 88.7 98.4 100.0 100.0 100.0 100.0 117:42 Point 6.25 2.70 16.00 1.422 592 118 7.8 21.3 29.1 41.8 52.1 65.6 74.8 83.3 89.4 91.1 98.7 100.0 100.0 100.0 100.0 100.0 117:46 Point 6.25 2.70 16.00 1.328 616 124 12.9 19.4 28.7 38.6 50.7 60.4 71.7 80.5 89.2 92.9 94.7 100.0 100.0 100.0 100.0 100.0 117:49 Point 6.25 2.70 16.00 1.360 630 126 8.4 15.7 26.6 39.4 51.2 64.6 76.1 83.8 90.7 92.2 93.7 97.4 100.0 100.0 100.0 100.0 117:52 Point 6.25 2.70 16.00 1.404 612 134 9.0 18.1 27.1 36.6 49.2 62.8 72.3 79.6 87.7 95.6 96.4 96.6 99.5 100.0 100.0 100.0 117:55 Point 6.25 2.70 16.00 1.446 618 127 6.8 17.4 24.5 36.7 50.4 63.1 74.7 83.8 89.8 94.3 98.1 100.0 100.0 100.0 100.0 100.0 117:59 Point 6.25 4.83 16.00 1.162 598 69.5 10.4 30.0 42.2 51.2 64.2 77.4 85.1 88.4 93.6 95.2 96.5 100.0 100.0 100.0 100.0 100.0 118:02 Point 6.25 4.83 16.00 1.420 586 64.4 13.8 28.7 44.6 55.2 66.7 79.5 84.6 90.8 94.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 118:04 Point 6.25 4.83 16.00 1.408 611 48.7 14.9 24.3 41.8 49.3 60.2 73.7 80.1 88.2 92.1 95.0 100.0 100.0 100.0 100.0 100.0 100.0 118:06 Point 6.25 4.83 16.00 1.262 629 46.1 23.0 40.7 55.7 63.6 73.5 80.3 82.0 83.5 88.4 98.0 100.0 100.0 100.0 100.0 100.0 100.0 118:08 Point 6.25 4.83 16.00 1.257 540 48.6 16.8 27.8 40.2 57.6 69.2 75.4 84.0 87.5 87.6 87.7 90.5 100.0 100.0 100.0 100.0 100.0 1

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
P-61 suspended-sediment samples collected at the Cisco gaging station on May 11, 1995; vertical located at the station 411 ft from the left-bank bridge abutment

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:54 Point 6.40 0.11 16.00 0.588 551 2,000 1.6 2.9 4.2 5.8 7.3 10.5 16.1 23.7 34.1 49.2 68.0 81.8 88.8 89.5 92.5 95.9 10:58 Point 6.40 0.11 16.00 0.562 454 1,210 0.8 2.7 3.8 5.9 10.1 12.2 16.7 27.3 44.0 58.3 74.7 82.8 90.1 96.4 100.0 100.0 11:01 Point 6.40 0.11 16.00 0.681 475 814 1.5 4.5 5.7 9.8 15.4 19.5 30.7 40.9 56.4 73.4 85.8 90.6 99.8 100.0 100.0 100.0 11:05 Point 6.40 0.11 23.00 0.489 515 1,070 0.7 2.5 5.3 6.5 10.4 15.8 22.7 35.3 50.0 65.8 76.9 93.8 98.2 99.6 100.0 100.0 11:15 Point 6.40 0.41 16.00 0.725 460 1,230 2.0 3.0 3.8 4.8 6.4 8.8 14.5 23.2 33.1 48.7 73.4 90.2 94.0 96.9 99.5 100.0 11:19 Point 6.40 0.41 16.00 1.007 446 414 6.1 8.8 13.2 20.7 26.5 35.4 45.6 58.5 68.7 77.9 88.7 94.9 100.0 100.0 100.0 100.0 11:22 Point 6.40 0.41 16.00 0.824 441 753 2.9 3.8 6.1 9.1 12.7 17.3 25.1 31.7 47.8 65.6 82.4 92.2 98.2 100.0 100.0 100.0 11:26 Point 6.40 0.41 16.00 0.562 463 525 3.4 5.5 9.3 13.7 18.6 28.0 39.4 54.2 65.5 77.1 90.1 97.0 97.9 100.0 100.0 100.0 11:30 Point 6.40 0.41 16.00 0.650 467 574 0.7 1.3 2.7 7.8 14.3 19.4 29.1 41.5 57.9 72.8 83.2 100.0 100.0 100.0 100.0 100.0 11:36 Point 6.40 0.72 16.00 0.983 455 374 3.6 9.9 16.4 17.3 23.9 31.8 36.2 52.0 68.3 80.9 89.0 94.4 100.0 100.0 100.0 100.0 11:39 Point 6.40 0.72 16.00 1.242 443 324 3.9 8.4 15.5 19.5 24.6 35.1 51.6 65.1 73.5 84.8 93.4 98.4 100.0 100.0 100.0 100.0 11:42 Point 6.40 0.72 16.00 0.801 591 341 4.9 10.5 16.0 20.2 28.2 36.3 49.7 66.7 77.7 91.3 97.2 98.7 100.0 100.0 100.0 100.0 11:45 Point 6.40 0.72 16.00 1.055 468 375 1.0 5.9 9.0 10.7 18.1 22.8 27.2 51.6 70.4 79.7 87.0 96.6 100.0 100.0 100.0 100.0 11:49 Point 6.40 0.72 16.00 0.858 450 405 3.4 9.3 13.4 15.3 17.8 31.3 42.7 56.3 69.7 81.1 89.8 97.8 100.0 100.0 100.0 100.0 12:44 Point 6.40 1.02 16.00 1.167 479 256 5.1 10.2 14.3 19.1 25.6 38.6 54.4 66.1 78.1 87.0 95.7 97.7 100.0 100.0 100.0 100.0 12:49 Point 6.40 1.02 16.00 1.104 473 241 4.7 8.8 14.0 17.9 25.6 37.0 54.0 71.7 81.2 91.1 97.6 100.0 100.0 100.0 100.0 100.0 12:57 Point 6.40 1.02 16.00 0.985 479 263 5.9 11.2 17.3 24.4 32.4 39.2 55.2 69.7 83.4 90.8 99.3 100.0 100.0 100.0 100.0 100.0 13:01 Point 6.40 1.02 16.00 1.140 492 221 4.6 9.2 16.4 22.3 30.0 41.5 55.0 71.1 82.2 91.4 97.9 99.8 100.0 100.0 100.0 100.0 13:04 Point 6.40 1.02 16.00 1.073 451 234 4.1 9.0 14.1 19.1 25.7 34.5 45.0 60.6 77.0 87.9 94.7 100.0 100.0 100.0 100.0 100.0 13:08 Point 6.40 1.33 16.00 1.211 457 192 4.3 10.2 16.0 22.8 29.1 43.4 57.9 72.8 83.6 90.6 95.8 99.6 100.0 100.0 100.0 100.0 13:11 Point 6.40 1.33 16.00 1.083 475 390 2.9 3.5 6.9 9.4 14.4 20.3 28.6 40.4 62.2 74.2 88.1 96.9 100.0 100.0 100.0 100.0 13:14 Point 6.40 1.33 16.00 1.091 459 276 3.4 7.5 12.4 17.5 25.2 33.9 48.0 66.9 80.1 90.3 96.2 100.0 100.0 100.0 100.0 100.0 13:17 Point 6.40 1.33 16.00 1.204 448 234 3.2 6.6 11.8 18.0 26.6 38.5 56.1 72.4 82.9 91.0 98.3 100.0 100.0 100.0 100.0 100.0 13:22 Point 6.40 1.33 16.00 1.142 474 246 2.2 6.2 12.1 17.1 25.3 38.1 54.2 68.3 82.9 91.9 96.9 100.0 100.0 100.0 100.0 100.0 13:25 Point 6.40 2.24 16.00 1.287 448 201 3.1 8.4 17.7 20.7 27.5 35.0 48.4 68.7 84.0 93.2 99.1 100.0 100.0 100.0 100.0 100.0 13:28 Point 6.40 2.24 16.00 1.267 472 228 5.0 10.4 16.4 22.3 28.8 40.6 57.1 72.4 82.6 93.3 96.9 100.0 100.0 100.0 100.0 100.0 13:30 Point 6.40 2.24 16.00 1.322 453 256 0.6 5.1 11.6 17.9 25.0 38.7 52.8 62.1 70.9 80.0 87.9 100.0 100.0 100.0 100.0 100.0 13:33 Point 6.40 2.24 16.00 1.278 441 226 4.1 8.2 16.8 24.5 31.3 41.6 54.3 67.3 80.3 89.8 95.6 99.5 100.0 100.0 100.0 100.0 13:36 Point 6.40 2.24 16.00 1.206 468 179 5.2 12.5 18.6 27.0 34.5 48.4 65.1 78.7 88.7 95.0 99.1 100.0 100.0 100.0 100.0 100.0 13:39 Point 6.40 3.46 16.00 1.246 448 173 6.1 12.8 19.2 26.4 37.3 51.2 68.4 79.1 88.0 94.8 99.1 100.0 100.0 100.0 100.0 100.0 13:41 Point 6.40 3.46 16.00 1.351 458 149 4.8 13.7 21.5 26.6 37.7 48.4 66.2 78.1 85.7 93.2 99.9 100.0 100.0 100.0 100.0 100.0 13:44 Point 6.40 3.46 16.00 1.401 465 151 4.3 9.2 17.2 25.4 34.0 50.5 70.0 84.5 90.1 99.0 100.0 100.0 100.0 100.0 100.0 100.0 13:47 Point 6.40 3.46 16.00 1.302 457 170 3.5 14.3 18.9 26.7 35.3 48.2 65.6 79.1 87.0 94.2 96.0 99.1 100.0 100.0 100.0 100.0 13:50 Point 6.40 3.46 16.00 1.334 461 133 4.2 10.5 20.4 29.0 40.3 57.8 72.2 82.9 91.5 96.0 100.0 100.0 100.0 100.0 100.0 100.0 13:53 Point 6.40 4.68 16.00 1.463 451 123 4.4 12.7 21.3 28.1 41.1 55.2 71.6 83.7 90.9 92.9 100.0 100.0 100.0 100.0 100.0 100.0 13:55 Point 6.40 4.68 16.00 1.423 459 139 9.2 19.2 25.9 35.5 45.0 61.7 76.9 87.1 94.0 97.9 99.9 100.0 100.0 100.0 100.0 100.0 13:57 Point 6.40 4.68 16.00 1.518 455 133 8.0 16.5 25.5 34.8 44.1 58.4 73.2 84.7 89.7 95.3 98.4 100.0 100.0 100.0 100.0 100.0 13:59 Point 6.40 4.68 16.00 1.334 440 138 7.5 15.0 25.8 33.4 43.3 57.5 72.2 82.6 89.6 93.7 98.9 100.0 100.0 100.0 100.0 100.0 14:02 Point 6.40 4.68 16.00 1.484 446 157 5.6 13.7 21.8 30.3 41.3 56.4 71.2 82.3 91.3 97.5 99.1 100.0 100.0 100.0 100.0 100.0 14:04 Point 6.40 5.90 16.00 1.529 450 92.7 10.1 19.4 27.3 36.6 44.6 61.8 76.5 83.9 91.9 94.8 98.7 100.0 100.0 100.0 100.0 100.0 14:07 Point 6.40 5.90 15.00 1.641 428 91.9 10.9 22.5 33.3 43.1 57.2 71.4 86.3 92.6 97.1 99.4 100.0 100.0 100.0 100.0 100.0 100.0 14:10 Point 6.40 5.90 14.00 1.591 441 97.2 16.1 26.6 38.0 47.2 57.5 70.7 84.7 89.4 95.2 98.3 100.0 100.0 100.0 100.0 100.0 100.0 14:12 Point 6.40 5.90 14.00 1.550 453 115 12.1 18.9 24.7 34.8 43.6 55.6 69.5 82.4 86.7 91.9 95.5 97.6 100.0 100.0 100.0 100.0 14:14 Point 6.40 5.90 14.00 1.469 443 120 10.1 17.7 28.5 36.5 47.3 63.4 76.6 85.6 91.8 98.2 100.0 100.0 100.0 100.0 100.0 100.0 14:16 Point 6.40 5.90 14.00 1.413 432 127 6.3 13.2 22.4 34.4 42.4 57.3 73.5 81.4 90.0 95.7 98.3 100.0 100.0 100.0 100.0 100.0 14:18 Point 6.40 5.90 14.00 1.593 433 59.9 6.3 19.9 27.5 36.7 47.0 62.8 80.2 89.1 95.4 99.2 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
P-61 suspended-sediment samples collected at the Cisco gaging station on May 12, 1995; vertical located at the station 340 ft from the left-bank bridge abutment

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:39 Point 5.03 0.11 20.00 0.531 502 1,730 0.8 1.4 2.2 2.9 5.8 9.9 15.8 28.0 45.6 72.0 94.5 98.2 100.0 100.0 100.0 100.0 12:42 Point 5.03 0.11 20.00 0.388 541 2,450 0.3 1.2 2.2 4.5 6.5 10.3 15.3 22.7 40.1 74.6 95.1 100.0 100.0 100.0 100.0 100.0 12:45 Point 5.03 0.11 20.00 0.373 470 2,130 1.0 2.5 4.1 6.7 9.3 12.9 18.1 25.6 44.3 77.2 94.8 99.3 100.0 100.0 100.0 100.0 12:48 Point 5.03 0.11 20.00 0.324 457 2,900 0.2 1.8 2.3 4.5 7.3 10.8 16.5 26.9 44.1 75.1 95.6 99.2 100.0 100.0 100.0 100.0 12:52 Point 5.03 0.11 20.00 0.440 474 1,980 1.3 1.9 3.8 5.1 7.7 11.5 18.8 27.0 43.0 71.2 93.7 98.3 100.0 100.0 100.0 100.0 12:54 Point 5.03 0.26 20.00 0.531 504 1,740 0.2 1.9 3.3 4.8 7.4 11.4 18.8 30.0 54.1 82.9 95.8 100.0 100.0 100.0 100.0 100.0 12:57 Point 5.03 0.26 20.00 0.414 451 1,320 2.1 4.6 8.1 10.3 15.4 20.9 29.1 41.0 56.9 80.9 92.8 99.8 100.0 100.0 100.0 100.0 13:01 Point 5.03 0.26 20.00 0.541 454 1,860 1.9 3.6 4.3 6.7 9.9 13.9 20.9 32.2 47.3 78.6 97.4 98.8 99.9 100.0 100.0 100.0 13:04 Point 5.03 0.26 20.00 0.592 445 1,730 1.5 1.9 3.7 6.2 8.6 11.8 19.9 35.3 53.4 75.9 96.2 99.7 100.0 100.0 100.0 100.0 13:07 Point 5.03 0.26 20.00 0.683 457 1,590 0.8 3.0 4.2 6.6 9.1 13.6 20.7 32.6 48.1 79.4 95.8 99.9 100.0 100.0 100.0 100.0 13:09 Point 5.03 0.57 20.00 1.008 472 464 2.8 6.8 12.0 18.1 22.7 29.1 45.9 58.2 79.1 88.7 97.7 100.0 100.0 100.0 100.0 100.0 13:12 Point 5.03 0.57 20.00 1.098 452 506 3.2 6.3 10.7 16.7 21.7 27.2 36.5 48.1 67.0 84.4 93.7 98.3 99.9 100.0 100.0 100.0 13:15 Point 5.03 0.57 20.00 1.117 442 643 2.6 5.2 7.9 9.9 12.9 23.0 32.7 48.2 68.6 86.8 97.4 100.0 100.0 100.0 100.0 100.0 13:18 Point 5.03 0.57 20.00 0.913 458 564 2.0 6.5 9.7 15.4 20.3 26.2 40.6 54.6 77.0 89.3 96.5 100.0 100.0 100.0 100.0 100.0 13:20 Point 5.03 0.57 20.00 1.081 483 454 4.0 8.2 11.5 13.6 24.8 33.0 45.0 61.0 81.9 92.0 95.9 97.2 100.0 100.0 100.0 100.0 13:23 Point 5.03 1.18 20.00 1.244 485 303 1.4 6.9 12.5 20.7 29.4 37.3 49.5 59.0 73.0 84.6 92.8 98.4 100.0 100.0 100.0 100.0 13:26 Point 5.03 1.18 16.00 1.525 527 402 1.8 7.9 10.4 15.0 20.0 26.0 32.7 47.0 60.4 83.1 90.7 96.0 100.0 100.0 100.0 100.0 13:29 Point 5.03 1.18 20.00 1.214 493 408 2.2 5.8 12.4 16.3 22.1 27.8 39.9 54.5 72.8 88.2 96.2 100.0 100.0 100.0 100.0 100.0 13:32 Point 5.03 1.18 12.00 1.333 536 337 6.9 8.0 15.2 22.7 28.0 34.7 43.7 57.9 73.9 87.2 96.2 100.0 100.0 100.0 100.0 100.0 13:35 Point 5.03 1.18 12.00 1.131 521 565 1.3 5.8 9.8 12.9 17.0 23.6 31.2 47.2 60.4 79.2 90.4 97.8 100.0 100.0 100.0 100.0 13:38 Point 5.03 1.18 12.00 1.302 525 311 4.8 9.4 14.4 20.6 28.2 38.4 50.8 67.6 80.2 91.6 99.3 100.0 100.0 100.0 100.0 100.0 13:41 Point 5.03 1.18 12.00 1.114 569 363 2.0 6.3 10.5 13.4 18.1 23.3 33.2 42.9 60.5 84.9 96.6 99.6 100.0 100.0 100.0 100.0 13:44 Point 5.03 1.18 12.00 1.131 569 545 3.4 6.6 11.7 16.5 18.1 29.1 37.7 47.9 62.3 83.7 95.6 100.0 100.0 100.0 100.0 100.0 13:47 Point 5.03 2.70 12.00 1.227 543 160 3.4 11.9 21.2 32.2 43.0 56.0 73.7 85.6 91.9 97.2 98.6 100.0 100.0 100.0 100.0 100.0 13:49 Point 5.03 2.70 12.00 1.215 579 169 5.5 15.8 27.1 36.2 47.4 60.5 70.9 81.4 89.2 97.3 99.8 100.0 100.0 100.0 100.0 100.0 13:51 Point 5.03 2.70 12.00 1.273 565 203 6.2 12.8 18.5 26.1 33.0 45.3 61.3 77.8 87.0 93.0 98.6 100.0 100.0 100.0 100.0 100.0 13:53 Point 5.03 2.70 12.00 1.281 521 194 6.1 15.3 24.8 36.2 46.5 59.6 71.7 81.0 90.2 94.3 98.8 100.0 100.0 100.0 100.0 100.0 13:56 Point 5.03 2.70 12.00 1.216 565 193 5.8 10.8 18.1 25.7 31.0 45.1 61.1 75.5 85.6 92.5 97.9 99.5 100.0 100.0 100.0 100.0 13:58 Point 5.03 4.53 12.00 1.252 536 98.0 4.9 17.4 31.1 42.1 53.5 71.0 78.3 85.6 93.2 97.5 100.0 100.0 100.0 100.0 100.0 100.0 14:00 Point 5.03 4.53 12.00 1.178 536 69.8 5.7 21.5 35.5 46.2 62.1 75.1 83.8 93.4 98.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:01 Point 5.03 4.53 12.00 1.318 512 89.7 10.4 20.7 32.2 42.9 54.2 67.9 75.0 81.2 87.0 94.7 99.4 100.0 100.0 100.0 100.0 100.0 14:03 Point 5.03 4.53 12.00 1.388 505 109 6.8 16.7 28.2 41.8 55.5 65.1 76.9 86.1 92.8 96.9 99.2 100.0 100.0 100.0 100.0 100.0 14:05 Point 5.03 4.53 12.00 1.269 531 184 9.3 21.2 35.3 43.7 53.8 64.6 73.3 81.1 88.6 95.5 98.6 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
P-61 suspended-sediment samples collected at the Cisco gaging station on May 13, 1995; vertical located at the station 340 ft from the left-bank bridge abutment

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:34 Up DI 5.09 n/a 9.80 1.211 1,480 512 8.1 18.2 27.8 35.1 42.9 51.1 60.3 68.6 78.1 89.5 95.0 99.2 100.0 100.0 100.0 100.0 10:36 Up DI 5.09 n/a 11.60 0.934 1,500 631 5.0 10.9 18.2 25.5 33.1 43.3 54.6 65.4 77.0 89.9 96.5 99.8 100.0 100.0 100.0 100.0 10:38 Up DI 5.09 n/a 12.10 1.301 1,500 704 5.3 11.9 17.6 23.1 30.4 37.9 45.5 55.5 67.4 80.3 93.8 97.9 98.4 99.5 100.0 100.0 10:40 Up DI 5.09 n/a 13.00 1.208 1,470 544 6.3 15.3 24.8 33.6 44.5 54.5 65.3 76.6 86.0 93.9 97.5 99.3 100.0 100.0 100.0 100.0 10:41 Up DI 5.09 n/a 12.10 1.208 1,440 733 5.2 13.2 21.5 29.6 36.7 43.8 53.6 65.5 79.4 91.2 98.7 99.8 100.0 100.0 100.0 100.0 12:42 Up DI 5.55 n/a 11.40 1.195 1,400 604 6.8 14.8 21.5 28.1 34.9 41.1 48.7 58.9 72.9 87.0 96.4 98.8 100.0 100.0 100.0 100.0 12:44 Up DI 5.55 n/a 11.40 1.300 1,380 509 6.0 13.0 19.3 25.9 34.7 42.1 50.1 57.7 69.1 81.7 93.5 95.8 97.7 100.0 100.0 100.0 12:46 Up DI 5.55 n/a 11.10 1.432 1,380 508 6.6 14.0 21.2 29.3 36.8 46.0 58.5 69.6 78.7 87.4 95.1 98.3 100.0 100.0 100.0 100.0 12:48 Up DI 5.55 n/a 11.70 1.359 1,450 651 6.7 14.6 22.1 27.5 33.0 39.1 47.4 57.5 70.1 86.2 96.1 99.1 100.0 100.0 100.0 100.0 12:50 Up DI 5.55 n/a 11.40 1.342 1,390 626 6.2 13.8 21.5 29.0 36.2 45.2 55.7 70.5 84.2 94.4 99.3 100.0 100.0 100.0 100.0 100.0 13:54 Up DI 6.04 n/a 12.80 1.142 1,610 1,080 6.5 9.9 12.4 14.9 19.0 23.3 29.7 36.1 48.8 74.6 90.0 95.9 100.0 100.0 100.0 100.0 13:56 Up DI 6.04 n/a 13.10 1.175 1,590 978 4.3 10.3 16.6 21.9 27.9 33.8 40.7 49.3 61.0 78.9 94.0 98.6 99.8 100.0 100.0 100.0 13:58 Up DI 6.04 n/a 13.20 1.278 1,470 329 9.4 20.7 33.5 48.0 61.2 70.1 78.2 84.4 88.7 93.3 96.1 96.7 99.9 100.0 100.0 100.0 14:00 Up DI 6.04 n/a 12.60 1.404 1,520 433 8.6 20.9 31.8 43.8 55.1 65.3 73.8 80.4 86.8 92.9 96.6 97.5 98.4 98.7 100.0 100.0 14:02 Up DI 6.04 n/a 13.60 1.286 1,540 493 7.2 15.7 23.4 31.6 40.1 50.2 61.3 72.6 83.5 93.3 97.8 99.0 100.0 100.0 100.0 100.0 15:39 Up DI 5.77 n/a 11.40 1.588 1,680 471 9.9 22.1 33.2 41.6 50.0 56.6 65.7 78.5 88.8 94.7 97.8 99.2 100.0 100.0 100.0 100.0 15:41 Up DI 5.77 n/a 11.70 1.332 1,670 577 8.4 18.5 27.3 34.6 41.9 51.7 63.2 75.8 87.4 94.3 98.5 100.0 100.0 100.0 100.0 100.0 15:43 Up DI 5.77 n/a 11.90 1.536 1,650 575 7.2 14.9 22.4 30.2 39.0 49.1 60.8 75.1 85.6 93.7 97.5 98.9 100.0 100.0 100.0 100.0 15:45 Up DI 5.77 n/a 11.90 1.184 1,670 507 6.3 15.1 23.6 31.1 37.3 45.9 56.4 68.2 78.7 86.6 93.2 97.0 98.5 99.3 100.0 100.0 15:47 Up DI 5.77 n/a 12.30 1.396 1,610 343 10.2 22.9 37.1 45.6 52.9 60.4 73.4 83.5 92.4 97.4 99.0 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit),

P-61 suspended-sediment samples collected at the Cisco gaging station on May 14, 1995; vertical located at the station 403 ft from the left-bank bridge abutment

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:22 Up DI 7.86 n/a 12.00 1.454 1,360 483 1.5 4.7 9.8 13.9 19.0 23.7 29.0 35.4 43.6 53.9 69.5 83.7 90.6 96.7 100.0 100.0 10:25 Up DI 7.86 n/a 12.90 1.770 1,300 426 2.2 8.1 11.6 14.5 18.0 22.0 28.4 37.3 45.0 55.2 66.0 77.5 86.8 94.2 97.3 100.0 10:27 Up DI 7.86 n/a 11.60 1.586 1,320 407 3.9 11.6 18.4 25.5 33.9 42.5 50.7 59.6 69.2 79.1 89.4 96.5 98.6 100.0 100.0 100.0 10:30 Up DI 7.86 n/a 10.50 1.787 1,280 241 6.0 16.6 29.5 41.8 53.5 64.5 74.0 83.1 90.0 94.9 99.2 100.0 100.0 100.0 100.0 100.0 10:32 Up DI 7.86 n/a 12.00 1.787 1,260 261 5.9 13.4 22.9 29.2 37.1 50.9 64.5 76.9 87.1 95.0 98.1 100.0 100.0 100.0 100.0 100.0 12:00 Up DI 7.72 n/a 11.10 1.349 1,310 294 2.7 9.0 21.4 32.4 44.1 59.7 73.0 82.9 89.5 94.0 99.2 99.4 100.0 100.0 100.0 100.0 12:02 Up DI 7.72 n/a 11.80 1.504 1,270 258 5.0 16.4 25.9 35.3 49.0 63.8 77.6 85.6 92.5 98.3 99.6 100.0 100.0 100.0 100.0 100.0 12:03 Up DI 7.72 n/a 10.90 1.466 1,320 317 5.3 11.3 20.8 28.3 38.8 51.8 64.8 75.0 85.1 93.7 98.1 100.0 100.0 100.0 100.0 100.0 12:05 Up DI 7.72 n/a 11.50 1.632 1,210 278 4.4 13.6 21.0 29.3 36.8 50.7 63.3 74.0 83.8 91.4 98.0 99.2 100.0 100.0 100.0 100.0 12:07 Up DI 7.72 n/a 11.20 1.641 1,200 261 4.8 9.8 16.3 25.9 40.1 49.5 61.6 72.3 81.5 92.1 97.2 98.3 98.9 100.0 100.0 100.0 14:07 Up DI 7.66 n/a 11.00 1.590 1,200 257 7.2 14.4 22.8 30.4 39.7 52.2 63.8 72.7 81.4 89.7 96.2 99.2 100.0 100.0 100.0 100.0 14:10 Up DI 7.66 n/a 10.90 1.730 1,270 292 8.0 17.7 27.4 37.0 47.0 61.2 73.1 83.2 91.9 98.0 99.3 100.0 100.0 100.0 100.0 100.0 14:12 Up DI 7.66 n/a 11.00 1.316 1,210 295 5.7 15.1 22.5 30.4 39.3 51.0 62.8 73.2 81.3 88.6 94.5 97.6 100.0 100.0 100.0 100.0 14:14 Up DI 7.66 n/a 10.00 1.477 1,260 282 4.8 10.5 18.5 28.4 35.9 46.6 58.7 69.5 79.9 88.3 94.5 97.3 98.2 100.0 100.0 100.0 14:16 Up DI 7.66 n/a 10.00 1.369 1,250 331 6.1 15.2 25.3 36.1 44.8 56.0 70.0 81.1 90.0 95.6 98.1 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).
Data collected at the River-mile 30 sediment station

P-61 suspended-sediment samples collected at River-mile 30 sediment station cross section B on February 5, 2006; vertical located at the station 92 ft from the left-bank end point of the tagline

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/ L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:20 Point 7.47 0.41 25.16 0.641 16.2 45.7 5.7 14.2 27.9 44.1 59.9 71.7 84.3 94.1 98.6 99.5 99.8 100.0 100.0 100.0 100.0 100.0 9:23 Point 7.47 0.41 40.31 0.632 12.4 32.6 7.4 17.2 33.1 50.0 64.8 75.9 85.5 93.2 96.7 97.5 98.6 99.7 99.9 100.0 100.0 100.0 9:26 Point 7.47 0.41 42.25 0.614 25.2 35.9 6.6 15.7 30.4 46.3 60.9 71.9 82.5 90.3 93.9 95.6 97.5 99.6 99.9 100.0 100.0 100.0 9:30 Point 7.47 1.18 44.25 0.790 15.3 23.1 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 9:33 Point 7.47 1.18 40.32 0.709 11.5 20.3 6.8 15.8 30.4 47.1 62.5 72.0 81.9 89.1 92.7 94.4 96.8 99.4 99.8 100.0 100.0 100.0 9:36 Point 7.47 1.18 43.26 0.757 15.1 26.1 9.5 21.2 39.0 57.4 72.6 80.4 87.9 93.2 95.8 96.3 98.6 99.8 100.0 100.0 100.0 100.0 9:40 Point 7.47 2.40 39.97 0.785 17.0 19.8 8.1 19.8 37.6 55.4 69.8 79.1 87.3 91.9 93.9 94.0 94.5 99.0 99.6 100.0 100.0 100.0 9:43 Point 7.47 2.40 39.29 0.828 12.9 16.9 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 9:46 Point 7.47 2.40 39.36 0.832 12.8 18.3 7.9 19.1 37.7 58.0 74.0 82.0 89.2 93.4 95.5 95.6 96.4 99.4 99.8 100.0 100.0 100.0 9:49 Point 7.47 3.92 37.47 0.822 14.8 16.2 9.8 22.4 41.5 61.3 75.6 84.0 93.6 98.1 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:54 Point 7.47 3.92 37.34 0.794 18.9 18.7 8.3 16.8 39.2 61.1 79.2 83.0 94.2 97.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:57 Point 7.47 3.92 37.72 0.829 13.6 16.7 9.3 24.9 46.3 70.0 86.4 90.2 98.3 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

10:00 Point 7.47 6.05 37.50 0.821 15.9 18.1 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 10:02 Point 7.47 6.05 38.15 0.825 13.6 12.1 14.7 37.4 59.2 88.3 96.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:05 Point 7.47 6.05 38.78 0.800 27.5 10.9 10.3 27.6 52.4 76.8 92.8 96.3 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 

P-61 suspended-sediment samples collected at River-mile 30 sediment station cross section B on February 5, 2006; vertical located at the station 188 ft from the left-bank end point of the tagline

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:08 Point 6.86 0.41 40.03 0.558 20.9 32.2 6.0 16.9 28.4 48.6 62.0 66.3 83.4 92.3 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:11 Point 6.86 0.41 45.22 0.574 16.9 24.9 5.0 14.2 29.8 49.6 64.5 68.2 87.3 94.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:15 Point 6.86 0.41 47.59 0.644 43.2 33 4.5 11.4 23.7 38.4 52.8 65.2 77.2 87.8 93.7 96.4 98.9 99.8 100.0 100.0 100.0 100.0 10:18 Point 6.86 1.18 44.18 0.624 15.3 35.9 2.7 7.4 21.2 35.0 52.9 60.2 73.5 83.6 90.5 94.7 96.8 99.6 100.0 100.0 100.0 100.0 10:21 Point 6.86 1.18 48.37 0.606 13.8 22.8 5.7 12.1 29.5 47.6 65.4 72.8 82.2 90.4 95.1 96.6 96.9 99.7 100.0 100.0 100.0 100.0 10:22 Point 6.86 1.18 48.84 0.685 14.4 21.3 6.7 13.6 32.2 51.3 69.0 76.2 84.0 89.9 93.1 93.3 93.8 99.4 100.0 100.0 100.0 100.0 10:26 Point 6.86 2.09 45.34 0.754 11.2 25.3 4.0 12.7 28.2 45.6 61.1 70.8 81.2 89.4 93.8 96.8 98.5 99.7 99.9 100.0 100.0 100.0 10:29 Point 6.86 2.09 46.25 0.735 8.31 18.9 12.2 26.5 44.8 61.3 74.4 83.5 90.7 96.8 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:32 Point 6.86 2.09 45.31 0.618 9.43 22.9 9.0 20.0 35.1 50.9 64.3 72.8 81.1 88.7 94.8 99.2 99.8 100.0 100.0 100.0 100.0 100.0 10:35 Point 6.86 3.61 44.35 0.875 9.19 15.9 10.3 22.8 39.9 58.5 71.7 78.5 84.2 88.4 90.5 90.7 91.6 98.6 99.4 100.0 100.0 100.0 10:38 Point 6.86 3.61 41.56 0.692 8.28 8.89 11.6 25.8 45.9 64.6 79.5 86.6 95.9 98.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:41 Point 6.86 3.61 42.75 0.814 11.0 21.0 5.7 13.2 29.4 45.1 63.2 70.3 81.2 89.6 93.9 94.2 94.6 99.5 100.0 100.0 100.0 100.0 10:44 Point 6.86 5.44 40.00 0.759 13.8 13.9 12.7 24.8 58.6 71.9 92.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:46 Point 6.86 5.44 40.09 0.702 21.1 14.8 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 10:47 Point 6.86 5.44 40.13 0.839 11.8 12.7 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
P-61 suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 7, 2006; vertical located at the station 92 ft from the left-bank end point of the tagline

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:45 Point 6.86 0.57 42.13 0.613 19.4 34.8 8.4 19.1 35.8 53.4 68.7 80.7 89.3 95.8 98.6 99.2 99.7 100.0 100.0 100.0 100.0 100.0 10:48 Point 6.86 0.57 42.03 0.598 26.1 32.6 9.3 20.0 37.5 55.9 73.4 87.0 95.3 98.9 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:53 Point 6.86 0.57 45.59 0.775 15.3 51.7 6.8 15.9 31.0 47.9 63.4 76.9 86.8 94.2 97.7 98.4 99.2 99.7 99.9 100.0 100.0 100.0 10:57 Point 6.86 1.18 40.13 0.606 17.8 31.4 9.4 21.5 40.2 59.5 74.7 85.6 92.1 97.0 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:00 Point 6.86 1.18 42.09 0.814 43.3 18.4 9.1 20.3 37.6 54.9 69.3 80.2 87.1 91.8 93.8 94.2 96.4 99.4 99.8 100.0 100.0 100.0 11:06 Point 6.86 1.18 42.18 0.769 11.3 16.5 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 11:10 Point 6.86 2.39 40.25 0.775 14.1 21.3 11.4 25.8 47.5 68.2 82.9 92.1 97.2 99.3 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:14 Point 6.86 2.39 40.09 0.832 14.1 16.2 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 11:16 Point 6.86 2.39 39.68 0.813 15.2 20.6 8.7 18.5 33.4 50.1 65.7 79.3 89.3 96.6 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:19 Point 6.86 4.53 39.90 0.809 14.1 14.4 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 11:21 Point 6.86 4.53 40.00 0.823 15.1 19.0 7.2 14.7 27.2 42.8 60.0 77.7 90.8 97.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:23 Point 6.86 4.53 39.93 0.816 15.0 20.9 11.3 23.8 43.8 61.9 77.3 88.6 95.7 99.0 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:26 Point 6.86 6.05 40.28 0.793 19.2 16.8 12.2 25.0 43.0 60.1 74.5 85.8 93.4 98.1 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:33 Point 6.86 6.05 40.09 0.787 14.6 14.8 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

11.36 Point 6.86 6.05 40.00 0.811 11.9 14.4 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 

P-61 suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 7, 2006; vertical located at the station 188 ft from the left-bank end point of the tagline

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:41 Point 6.55 0.87 39.78 0.698 20.9 28.2 7.1 16.8 33.5 50.7 65.2 77.5 85.8 91.8 94.7 97.3 99.5 99.9 100.0 100.0 100.0 100.0 11:43 Point 6.55 0.87 39.83 0.593 22.2 26.8 11.1 24.3 45.0 64.8 79.9 89.9 96.0 98.9 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:46 Point 6.55 0.87 39.91 0.598 18.8 32.2 10.0 22.4 41.2 60.6 76.2 86.8 93.4 97.9 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:51 Point 6.55 1.63 40.00 0.722 18.4 22.8 12.3 25.1 44.5 64.2 80.6 91.5 96.9 99.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:54 Point 6.55 1.63 43.00 0.734 16.7 23.2 9.0 19.5 35.6 52.3 66.6 78.7 86.8 92.4 95.2 97.1 99.3 99.9 100.0 100.0 100.0 100.0 11:57 Point 6.55 1.63 40.06 0.703 17.8 19.3 10.4 23.1 42.8 61.7 76.7 87.2 94.5 98.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:03 Point 6.55 3.61 40.03 0.797 16.4 17.2 18.9 37.7 67.3 89.1 98.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:07 Point 6.55 3.61 39.97 0.746 12.5 20.4 9.9 20.9 37.5 53.3 64.8 71.7 76.1 78.9 80.2 82.5 88.8 93.3 98.3 99.2 100.0 100.0 12:11 Point 6.55 3.61 40.06 0.686 15.9 25.3 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 12:14 Point 6.55 5.14 40.16 0.730 15.0 22.5 9.6 20.1 37.2 55.2 72.0 83.7 90.6 95.1 97.0 97.6 99.3 99.9 100.0 100.0 100.0 100.0 12:17 Point 6.55 5.14 40.25 0.734 16.3 19.1 10.4 23.9 45.5 66.8 84.9 95.5 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:21 Point 6.55 5.14 40.10 0.784 13.2 16.2 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 12:26 Point 6.55 5.75 39.91 0.750 12.6 12.9 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 12:30 Point 6.55 5.75 39.90 0.797 18.2 12.5 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 12:34 Point 6.55 5.75 39.94 0.770 12.8 12.2 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section A on February 24, 2007; 

verticals 1 through 9 located respectively at stations 46, 67, 88, 109, 130, 151, 172, 193, and 214 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 25 and 235 fet from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:33- 12:43

EWI-5v n/a n/a 665 n/a 16.6 57.7 10.0 21.6 39.2 56.6 69.7 79.3 85.2 89.9 94.0 96.7 97.7 98.1 98.4 99.3 99.7 100.0 

11:40-12:37

EWI-3v n/a n/a 456 n/a 14.1 54.3 9.6 21.5 39.7 57.7 71.1 80.9 87.0 91.6 95.3 97.6 98.3 98.6 98.6 99.4 99.7 100.0 

11:33-12:43

EWI-9v n/a n/a 1300 n/a 15.4 56.9 9.4 21.0 39.1 57.1 70.6 80.4 86.5 91.2 94.9 97.3 98.4 98.9 99.1 99.6 99.8 100.0 

12:39 v1 8DI 2.74 n/a 82 0.225 24.2 42.1 9.6 22.0 41.9 61.5 75.9 85.5 90.4 93.6 95.6 96.7 97.6 98.1 98.6 99.4 99.8 100.0 12:33 v2 8DI 6.71 n/a 168 0.377 11.7 51.0 9.8 21.8 40.3 58.2 71.5 80.7 86.9 92.1 95.7 98.2 99.7 100.0 100.0 100.0 100.0 100.0 12:22 v3 8DI 7.92 n/a 202 0.426 8.58 51.2 11.9 24.0 42.0 59.5 72.3 80.8 85.5 89.1 92.5 95.0 96.4 97.0 97.8 99.0 99.6 100.0 12:12 v4 8DI 7.62 n/a 195 0.513 12.6 57.1 8.9 20.4 38.7 56.8 70.5 80.4 86.6 91.6 95.5 97.9 99.5 99.9 100.0 100.0 100.0 100.0 12:02 v5 8DI 6.86 n/a 175 0.622 15.2 55.0 10.1 22.1 39.9 57.3 70.3 79.9 86.0 90.4 94.4 97.0 97.2 97.3 97.3 98.8 99.5 100.0 11:55 v6 8DI 6.40 n/a 159 0.477 18.5 58.4 7.9 19.3 38.4 57.7 72.2 82.9 88.9 93.1 95.7 97.4 98.6 99.3 99.5 99.8 99.9 100.0 11:46 v7 8DI 6.10 n/a 152 0.415 27.0 78.4 8.3 18.7 34.9 51.4 64.4 74.7 82.0 88.2 93.6 97.3 99.1 99.6 99.9 99.9 100.0 100.0 11:40 v8 8DI 4.57 n/a 113 0.402 14.7 57.3 8.1 19.6 38.7 58.0 72.5 83.4 89.7 93.8 96.6 98.3 99.2 99.8 100.0 100.0 100.0 100.0 11:33 v9 8DI 2.29 n/a 54 0.295 18.4 46.3 9.9 23.2 44.2 64.6 79.3 89.0 94.4 98.1 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section B on February 24, 2007; 

verticals 1 through 9 located respectively at stations 44, 68, 91, 115, 138, 162, 185, 209, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 21 and 256 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:55-13:55

EWI-5v n/a n/a 532 n/a 15.6 45.8 10.2 23.1 43.4 63.1 77.1 86.6 91.4 94.2 95.7 96.7 97.8 98.5 98.9 99.5 99.8 100.0 

13:03-13:52

EWI-3v n/a n/a 337 n/a 15.1 44.4 10.6 24.2 45.7 66.1 80.4 89.5 93.8 95.9 97.0 97.9 98.7 99.2 99.4 99.8 99.9 100.0 

12:55- 13:55

EWI-9v n/a n/a 998 n/a 16.2 45.9 9.9 22.9 43.7 63.7 78.0 87.6 92.5 95.3 96.7 97.5 98.4 99.0 99.3 99.7 99.9 100.0 

13:53 v1 6DI 2.13 n/a 51 0.369

9

25.0 36.5 11.1 23.5 42.2 59.6 71.5 79.1 83.4 86.6 88.8 90.3 92.2 93.9 95.7 98.2 99.4 100.0 

13:49 v2 6DI 3.96 n/a 87 0.452 15.1 38.9 10.9 25.5 48.5 69.8 84.1 93.2 97.4 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:43 v3 6DI 6.10 n/a 140 0.480 9.88 41.1 11.0 24.9 45.9 65.5 79.2 88.3 92.8 95.2 96.3 97.1 97.8 98.5 98.9 99.5 99.8 100.0 13:35 v4 6DI 5.94 n/a 130 0.451 14.0 45.5 9.7 22.9 43.9 64.1 78.3 87.9 92.9 95.6 96.9 97.6 98.5 99.1 99.4 99.7 99.9 100.0 13:24 v5 6DI 5.79 n/a 126 0.458 16.0 45.2 11.0 24.5 45.3 65.2 78.9 87.5 91.3 93.2 94.5 95.9 97.3 98.2 98.6 99.5 99.8 100.0 13:15 v6 6DI 5.79 n/a 125 0.397 24.0 50.3 8.6 20.8 41.0 61.2 76.1 86.6 92.1 95.3 97.1 98.1 99.0 99.4 99.6 99.8 99.9 100.0 13:09 v7 6DI 5.79 n/a 124 0.346 12.3 62.1 8.4 20.2 39.6 59.4 74.6 85.8 92.0 95.5 97.5 98.4 99.1 99.5 99.7 99.8 99.9 100.0 13:03 v8 6DI 5.85 n/a 124 0.339 13.7 48.5 9.7 22.7 43.9 64.6 79.4 89.4 94.3 96.8 97.9 98.7 99.6 99.9 100.0 100.0 100.0 100.0 12:55 v9 6DI 4.27 n/a 91 0.293 27.9 38.8 9.9 22.5 42.8 62.9 77.2 86.8 91.9 95.3 96.9 97.9 99.4 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical,
D-96-A1 noncomposited multivertical suspended-sediment samples collected at River mile 30 sediment station cross section A on February 24, 2007; 

verticals 1 through 9 located respectively at stations 46, 67, 88, 109, 130, 151, 172, 193, and 214 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 25 and 235 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

17:10- 18:41

EWI-5v n/a n/a 639 n/a 14.7 67.0 9.5 22.0 41.9 61.4 75.5 85.2 90.6 94.2 96.6 98.3 99.4 99.8 99.9 100.0 100.0 100.0 

17:16-18:36

EWI-3v n/a n/a 447 n/a 19.0 67.4 9.0 21.2 40.7 59.6 73.3 82.9 88.6 92.9 96.0 98.4 99.7 99.9 100.0 100.0 100.0 100.0 

17:10-18:41

EWI-9v n/a n/a 1280 n/a 16.1 67.7 9.3 21.6 41.2 60.3 74.2 83.8 89.3 93.3 96.1 98.2 99.5 99.9 100.0 100.0 100.0 100.0 

18:39 v1 8DI 2.74 n/a 60 0.302 25.1 66.2 8.6 20.1 39.9 60.6 75.9 86.2 91.4 94.6 96.6 97.7 99.0 99.8 100.0 100.0 100.0 100.0 18:28 v2 8DI 6.71 n/a 164 0.482 17.3 63.6 8.3 20.1 39.5 58.6 72.6 82.0 87.6 92.0 95.4 98.2 99.7 100.0 100.0 100.0 100.0 100.0 18:13 v3 8DI 7.92 n/a 210 0.638 14.3 66.0 9.6 22.0 41.7 61.0 74.9 84.5 89.8 93.6 96.3 98.3 99.6 99.9 100.0 100.0 100.0 100.0 18:00 v4 8DI 7.62 n/a 198 0.820 15.0 68.5 9.7 22.5 42.6 62.0 76.0 85.5 90.7 94.2 96.7 98.4 99.5 99.9 100.0 100.0 100.0 100.0 17:45 v5 8DI 6.86 n/a 165 0.883 17.4 65.8 9.9 22.9 43.1 62.5 76.3 85.7 91.1 94.7 96.8 98.5 99.6 99.9 100.0 100.0 100.0 100.0 17:37 v6 8DI 6.40 n/a 161 0.692 16.5 67.3 9.3 21.2 40.0 58.4 71.7 81.2 87.0 91.5 95.1 97.9 99.4 99.9 100.0 100.0 100.0 100.0 17:23 v7 8DI 6.10 n/a 152 0.483 7.01 67.4 8.6 20.8 40.6 60.2 74.5 84.6 90.0 93.5 95.9 97.6 98.8 99.5 99.7 99.8 99.9 100.0 17:16 v8 8DI 4.57 n/a 118 0.536 24.9 76.0 7.9 19.2 37.1 54.7 68.3 78.2 84.6 90.2 94.9 98.4 99.7 100.0 100.0 100.0 100.0 100.0 17:10 v9 8DI 2.29 n/a 52 0.432 17.4 79.7 9.3 21.7 41.9 61.9 76.5 86.9 92.7 96.4 98.3 99.1 99.8 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at River mile 30 sediment station cross section B on February 25, 2007; 

verticals 1 through 9 located respectively at stations 44, 68, 91, 115, 138, 162, 185, 209, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 21 and 256 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:27-

10:06

EWI-5v n/a n/a 332 n/a 14.3 44.8 8.4 20.0 39.7 60.0 75.4 86.3 92.0 95.1 96.5 97.1 97.8 98.2 98.5 99.4 99.7 100.0 

9:31-

10:02

EWI-3v n/a n/a 225 n/a 16.7 43.5 8.1 18.9 37.5 57.0 72.2 83.4 89.6 93.5 95.6 96.9 98.0 98.7 99.2 99.6 99.9 100.0 

9:27- 

10:06

EWI-9v n/a n/a 642 n/a 15.0 43.7 8.1 19.4 38.9 59.4 75.1 86.2 92.0 95.2 96.7 97.6 98.4 98.8 99.1 99.6 99.8 100.0 

9:27 v1 4DI 2.43 n/a 31 0.468 21.2 53.7 7.7 18.3 36.5 55.8 70.9 81.7 87.8 91.4 92.7 92.9 92.9 92.9 93.1 97.0 98.7 100.0 9:31 v2 4DI 4.27 n/a 53 0.622 18.8 40.4 8.3 19.2 38.0 58.1 73.7 84.9 91.1 94.9 96.9 97.8 98.8 99.6 99.8 99.9 100.0 100.0 9:34 v3 4DI 6.40 n/a 81 0.608 11.3 52.0 8.0 19.4 39.2 59.9 75.9 87.5 93.5 96.6 97.9 98.5 99.4 99.8 100.0 100.0 100.0 100.0 9:40 v4 4DI 6.25 n/a 89 0.597 12.1 44.4 7.0 17.8 37.5 58.9 75.7 87.7 93.7 96.8 98.2 99.0 99.8 100.0 100.0 100.0 100.0 100.0 9:45 v5 4DI 6.10 n/a 88 0.545 13.8 45.3 7.4 18.1 36.6 56.0 71.3 82.8 89.5 93.7 96.0 97.4 98.3 99.0 99.3 99.7 99.9 100.0 9:52 v6 4DI 6.10 n/a 84 0.603 15.5 41.2 7.3 18.6 38.7 59.9 76.2 87.6 93.4 96.4 97.9 98.9 99.7 100.0 100.0 100.0 100.0 100.0 9:56 v7 4DI 6.10 n/a 78 0.515 13.4 33.9 10.6 24.8 47.7 69.8 85.1 94.4 98.2 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

10:00 v8 4DI 6.16 n/a 84 0.421 18.7 43.9 8.8 19.9 38.3 57.5 72.2 82.8 88.6 92.0 94.0 95.3 96.8 97.7 98.4 99.3 99.8 100.0 10:05 v9 4DI 15.0 n/a 54 0.405 19.7 41.4 9.3 20.8 39.6 58.9 73.2 83.1 88.1 90.7 91.5 92.0 93.1 93.7 94.9 97.8 99.1 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thr

indicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section A on August 24, 2007; 

verticals 1 through 9 located respectively at stations 78, 100, 122, 144, 165, 187, 209, 231, and 252 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 56 and 274 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L) 

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:02-14:37

EWI-5v n/a n/a 320 n/a 28.7 65.2 8.2 19.0 36.3 54.3 68.9 80.6 88.0 93.1 96.3 97.9 98.8 99.3 99.5 99.8 99.9 100.0 

14:07-14:33

EWI-3v n/a n/a 218 n/a 25.6 66.7 7.6 17.8 34.5 52.0 66.5 78.5 86.5 92.2 95.9 97.8 98.7 99.1 99.4 99.7 99.9 100.0 

14:02-14:37

EWI-9v n/a n/a 634 n/a 28.8 66.8 7.7 18.0 34.9 52.5 67.0 78.9 86.6 92.2 95.8 97.8 98.8 99.4 99.6 99.8 99.9 100.0 

14:35 v1 4DI 4.11 n/a 99 0.268 30.7 49.2 8.4 19.8 38.1 57.1 72.2 83.7 91.1 96.3 98.5 98.9 98.9 98.9 98.9 99.5 99.8 100.0 14:32 v2 2DI 7.01 n/a 88 0.569 27.8 57.9 7.7 18.3 35.7 53.9 68.7 80.9 88.9 94.6 98.1 99.6 99.9 100.0 100.0 100.0 100.0 100.0 14:27 v3 2DI 8.08 n/a 101 0.754 29.6 62.5 8.2 19.1 36.9 55.0 69.7 81.7 89.2 94.4 97.5 98.9 99.6 99.9 100.0 100.0 100.0 100.0 14:21 v4 2DI 7.77 n/a 98 0.789 29.6 62.3 7.6 18.3 36.0 54.2 69.0 80.7 87.9 92.7 95.7 97.4 98.6 99.5 99.8 99.9 100.0 100.0 14:19 v5 2DI 6.71 n/a 83 0.846 22.1 72.9 7.7 17.7 33.7 50.6 64.8 76.6 84.5 90.4 94.4 96.6 97.8 98.5 98.9 99.5 99.8 100.0 14:15 v6 2DI 6.55 n/a 81 0.742 27.8 85.8 6.4 15.2 29.7 45.4 59.0 71.3 80.3 87.7 93.2 96.4 97.9 98.9 99.4 99.7 99.9 100.0 14:12 v7 2DI 5.49 n/a 67 0.632 35.9 62.4 9.0 20.9 39.8 58.9 73.9 85.0 91.2 94.8 96.8 98.3 99.3 99.9 100.0 100.0 100.0 100.0 14:07 v8 4DI 3.96 n/a 93 0.363 33.2 66.8 7.1 17.3 34.7 53.3 68.6 81.0 88.7 94.0 97.0 98.4 99.5 99.9 100.0 100.0 100.0 100.0 14:02 v9 6DI 1.83 n/a 59 0.213 44.3 61.1 8.1 19.5 38.6 58.4 73.8 85.1 92.3 97.2 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw labora

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 24, 2007; 

verticals 1 through 9 located respectively at stations 44, 67, 91, 114, 138, 161, 185, 208, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 20 and 255 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:48- 15:25

EWI-5v n/a n/a 312 n/a 30.9 51.5 9.6 22.1 41.8 61.3 76.2 86.9 92.7 96.0 97.5 98.3 99.3 99.6 99.8 99.9 100.0 100.0 

14:52-15:20

EWI-3v n/a n/a 236 n/a 30.9 52.6 9.8 22.4 42.0 61.5 76.1 86.7 92.4 95.6 97.1 98.0 98.8 99.3 99.5 99.8 99.9 100.0 

14:48-15:25

EWI-9v n/a n/a 625 n/a 31.9 50.7 9.8 22.6 42.7 62.4 77.2 87.8 93.6 96.8 98.2 98.8 99.4 99.7 99.8 99.9 100.0 100.0 

15:22 v1 4DI 2.59 n/a 68 0.541 39.1 51.0 11.2 24.4 44.4 63.7 78.2 88.3 93.7 96.6 97.8 98.6 99.6 99.9 100.0 100.0 100.0 100.0 15:18 v2 2DI 7.32 n/a 93 0.496 30.1 50.7 8.9 20.9 40.1 59.5 74.2 84.9 90.7 94.1 95.8 96.9 98.2 99.0 99.4 99.8 99.9 100.0 15:14 v3 2DI 6.71 n/a 84 0.550 31.8 53.1 8.9 20.7 39.8 59.2 74.3 85.6 92.2 96.3 98.1 98.9 99.7 99.9 100.0 100.0 100.0 100.0 15:10 v4 2DI 6.10 n/a 77 0.716 33.9 43.8 10.5 24.1 44.9 64.8 79.3 89.7 95.7 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:05 v5 2DI 5.64 n/a 71 0.753 25.1 48.8 10.0 22.3 41.6 60.7 75.4 86.0 91.3 94.2 96.0 97.2 98.2 98.9 99.2 99.7 99.9 100.0 15:01 v6 2DI 5.79 n/a 71 0.687 28.5 48.2 10.1 23.7 44.9 65.4 80.4 90.9 96.4 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:56 v7 2DI 5.94 n/a 75 0.707 31.7 53.0 9.3 22.1 42.3 62.1 77.0 87.9 93.7 96.9 98.0 98.6 99.6 99.9 100.0 100.0 100.0 100.0 14:52 v8 2DI 5.79 n/a 72 0.524 40.2 60.1 10.6 23.9 44.5 64.4 78.9 89.4 95.4 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:48 v9 4DI 3.96 n/a 95 0.401 35.0 51.2 9.8 22.9 43.6 63.7 78.4 88.4 93.7 96.8 98.2 98.8 99.7 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw labora

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thr

indicates the number of transits at each vertical.
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section A on August 24, 2007; 

verticals 1 through 9 located respectively at stations 78, 100, 122, 144, 165, 187, 209, 231, and 252 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 56 and 274 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:44-16:18

EWI-5v n/a n/a 321 n/a 28.7 89.3 6.8 15.9 31.3 47.8 61.9 74.0 82.7 89.4 93.8 96.5 98.2 99.2 99.5 99.8 99.9 100.0 

15:48-16:13

EWI-3v n/a n/a 219 n/a 36.1 98.3 6.6 15.6 30.7 46.9 60.9 73.1 82.0 89.1 94.0 96.9 98.8 99.8 100.0 100.0 100.0 100.0 

15:44-16:18

EWI-9v n/a n/a 619 n/a 31.9 89.5 6.6 15.7 31.2 48.0 62.3 74.5 83.0 89.5 94.0 96.6 98.3 99.2 99.5 99.8 99.9 100.0 

15:44 v1 4DI 4.11 n/a 83 0.300 35.1 72.6 7.8 17.9 34.2 51.8 66.5 78.4 85.7 90.7 93.7 95.4 96.6 96.9 97.5 98.9 99.6 100.0 15:48 v2 2DI 7.01 n/a 87 0.284 44.6 84.4 7.1 17.2 34.0 51.9 66.5 78.4 86.2 92.0 95.6 97.5 99.2 99.9 100.0 100.0 100.0 100.0 15:52 v3 2DI 8.08 n/a 104 0.488 24.2 76.9 7.4 17.5 34.1 51.6 66.0 77.9 85.9 91.7 95.3 97.4 98.9 99.8 99.9 100.0 100.0 100.0 15:55 v4 2DI 7.77 n/a 84 0.463 35.0 80.5 7.0 17.0 34.1 52.7 68.3 80.8 88.2 93.0 96.1 97.9 99.2 99.8 100.0 100.0 100.0 100.0 16:00 v5 2DI 6.71 n/a 85 0.465 29.3 109 6.2 14.3 28.1 43.1 56.6 69.0 78.8 87.0 92.9 96.4 98.5 99.7 99.9 100.0 100.0 100.0 16:04 v6 2DI 6.55 n/a 81 0.569 29.0 100 5.5 13.4 27.0 42.3 55.9 68.4 77.8 85.6 91.8 95.5 97.4 98.6 99.2 99.7 99.9 100.0 16:07 v7 2DI 5.49 n/a 68 0.359 33.4 91.2 6.2 15.1 30.5 47.4 61.6 73.8 82.6 89.1 92.9 95.1 96.9 98.1 98.6 99.4 99.7 100.0 16:11 v8 4DI 3.96 n/a 93 0.197 42.3 88.1 7.7 18.3 35.8 54.4 69.6 81.4 88.6 93.4 96.2 97.9 99.4 99.9 100.0 100.0 100.0 100.0 16:15 v9 8DI 1.83 n/a 88 0.071 39.2 88.7 9.0 22.1 43.5 68.2 87.5 97.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw labora

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 24, 2007; 

verticals 1 through 9 located respectively at stations 44, 67, 91, 114, 138, 161, 185, 208, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 20 and 255 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

16:23- 16:55

EWI-5v n/a n/a 308 n/a 36.5 87.2 7.5 17.7 35.0 53.7 69.1 81.5 89.1 93.9 96.5 97.7 98.6 99.0 99.2 99.7 99.9 100.0 

16:26-16:51

EWI-3v n/a n/a 234 n/a 33.4 93.0 7.2 17.3 34.7 54.0 70.3 83.2 90.6 95.2 97.6 98.7 99.5 99.9 100.0 100.0 100.0 100.0 

16:23-16:55

EWI-9v n/a n/a 620 n/a 33.2 93.5 7.5 17.8 35.3 54.0 69.5 82.0 89.6 94.4 96.9 98.1 99.0 99.4 99.6 99.8 99.9 100.0 

16:23 v1 4DI 2.44 n/a 59 0.318 31.5 87.3 7.6 17.5 34.3 53.0 68.8 81.3 88.9 93.7 96.2 97.7 99.4 99.9 100.0 100.0 100.0 100.0 16:26 v2 2DI 7.32 n/a 93 0.336 30.6 70.5 7.9 19.1 38.1 58.4 74.5 86.2 92.3 95.7 97.2 98.2 99.3 99.9 100.0 100.0 100.0 100.0 16:30 v3 2DI 6.71 n/a 84 0.350 40.9 91.2 7.3 17.1 33.3 51.0 66.1 78.8 87.2 92.9 96.0 97.5 98.6 99.1 99.3 99.7 99.9 100.0 16:34 v4 2DI 6.10 n/a 77 0.452 31.3 65.7 8.1 20.0 40.3 61.1 76.9 88.8 95.7 99.0 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:38 v5 2DI 5.64 n/a 70 0.332 35.5 91.0 7.6 18.1 36.1 55.8 72.5 85.5 92.6 96.9 99.2 99.9 100.0 100.0 100.0 100.0 100.0 100.0 16:41 v6 2DI 5.79 n/a 71 0.460 25.1 144 7.7 17.9 34.6 52.2 66.8 79.3 87.4 93.0 96.2 97.9 98.9 99.7 99.9 100.0 100.0 100.0 16:45 v7 2DI 5.94 n/a 77 0.434 33.1 83.7 6.9 16.8 33.7 52.0 67.2 79.5 87.0 91.8 94.5 95.9 96.9 97.4 97.9 99.1 99.7 100.0 16:49 v8 2DI 5.79 n/a 71 0.381 34.7 121 6.6 15.6 31.6 49.9 66.1 79.7 88.2 93.7 96.7 98.2 99.2 99.8 100.0 100.0 100.0 100.0 16:53 v9 4DI 3.96 n/a 95 0.319 40.0 81.0 8.9 21.0 40.5 59.9 74.5 85.4 91.9 95.9 97.4 98.1 99.3 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw labora

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
Single-vertical D-96-A1 suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 25, 2007; vertical located at the station 138 ft from the left-bank end point of the t

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

6:17 DI 6.86 n/a 67.01 0.912 44.2 119 9.0 20.8 39.2 57.5 71.8 83.0 89.8 94.2 96.9 98.4 99.3 99.8 100.0 100.0 100.0 100.0 6:21 DI 6.86 n/a 68.02 0.871 51.5 143 7.5 18.1 35.4 53.5 68.3 80.6 88.3 93.4 96.3 97.8 98.7 99.4 99.6 99.8 99.9 100.0 6:25 DI 6.86 n/a 67.01 0.919 43.0 133 7.7 18.5 36.0 54.0 68.6 80.4 87.7 92.7 95.7 97.3 98.3 99.1 99.5 99.8 99.9 100.0 6:29 DI 6.86 n/a 68.02 0.842 41.9 135 7.3 17.7 34.6 52.0 66.6 78.7 86.5 92.1 95.6 97.6 98.9 99.7 99.9 100.0 100.0 100.0 6:31 DI 6.55 n/a 66.04 0.928 46.3 134 7.5 18.2 35.5 53.5 68.2 80.3 88.1 93.4 96.5 98.1 99.1 99.5 99.8 99.9 100.0 100.0 6:35 DI 6.55 n/a 67.05 0.860 59.5 131 7.0 16.7 32.5 48.9 62.6 74.5 82.7 89.1 93.8 96.7 98.3 99.3 99.7 99.9 100.0 100.0 6:38 DI 6.55 n/a 67.05 0.935 45.8 134 6.8 16.7 33.4 51.1 65.9 78.5 86.6 92.3 95.9 97.8 99.0 99.8 99.9 100.0 100.0 100.0 6:42 DI 6.55 n/a 67.05 0.782 43.9 119 9.2 20.6 38.9 56.4 69.7 80.7 87.6 92.4 95.7 97.7 98.8 99.5 99.8 99.9 100.0 100.0 6:46 DI 6.55 n/a 65.02 0.941 41.5 141 7.6 18.0 34.7 51.8 66.1 78.2 86.3 92.1 95.9 97.9 99.0 99.7 99.9 100.0 100.0 100.0 6:50 DI 6.55 n/a 65.02 0.929 37.1 126 7.8 18.4 35.2 52.4 66.7 78.8 86.8 92.4 96.0 97.8 98.8 99.5 99.7 99.9 100.0 100.0 6:53 DI 6.55 n/a 64.01 0.907 40.4 132 7.9 18.5 35.5 53.1 67.5 79.4 87.1 92.4 95.8 97.7 98.8 99.6 99.8 100.0 100.0 100.0 6:57 DI 6.55 n/a 64.01 0.902 39.0 127 7.8 18.7 36.2 54.2 68.8 80.7 88.2 93.3 96.5 98.3 99.2 99.8 100.0 100.0 100.0 100.0 7:01 DI 6.55 n/a 64.01 0.927 61.9 117 7.9 18.6 35.9 53.6 68.1 80.0 87.7 93.0 96.1 98.0 99.1 99.8 100.0 100.0 100.0 100.0 7:05 DI 6.55 n/a 64.01 1.003 37.3 106 8.2 19.5 37.4 55.5 70.1 81.8 89.2 94.2 97.0 98.4 99.3 99.8 100.0 100.0 100.0 100.0 7:08 DI 6.55 n/a 64.01 0.869 35.9 139 7.6 17.8 34.3 51.6 66.3 78.8 86.9 92.6 96.0 97.9 98.9 99.6 99.8 99.9 100.0 100.0 

Notes: DI = depth-integrated (nozzle open during downward and upward transits).

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 25, 2007; 

verticals 1 through 9 located respectively at stations 44, 67, 91, 114, 138, 161, 185, 208, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 20 and 255 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:03- 8:37

EWI-5v n/a n/a 369 n/a 41.3 126 7.4 17.3 33.6 50.9 65.8 78.4 86.7 92.3 95.6 97.3 98.4 99.2 99.5 99.8 99.9 100.0 

8:07-8:32

EWI-3v n/a n/a 275 n/a 58.1 135 7.5 17.5 33.8 50.9 65.4 77.8 86.2 92.1 95.6 97.4 98.5 99.3 99.6 99.9 99.9 100.0 

8:03-8:37

EWI-9v n/a n/a 733 n/a 47.2 122 7.5 17.5 34.0 51.5 66.4 78.9 87.0 92.6 95.9 97.6 98.6 99.4 99.6 99.9 99.9 100.0 

8:03 v1 4DI 3.35 n/a 101 0.354 36.1 132 8.3 19.3 37.1 55.7 70.9 82.9 90.1 94.3 96.3 97.4 98.4 99.3 99.7 99.9 100.0 100.0 8:07 v2 2DI 8.08 n/a 107 0.339 63.4 145 8.0 18.7 35.9 53.6 68.3 80.7 88.7 94.1 97.0 98.4 99.2 99.8 100.0 100.0 100.0 100.0 8:12 v3 2DI 7.47 n/a 94 0.466 39.9 151 6.4 15.0 29.8 46.5 61.8 75.6 85.1 91.6 95.7 97.5 98.5 99.1 99.4 99.8 99.9 100.0 8:16 v4 2DI 6.86 n/a 88 0.430 32.4 60.2 9.0 20.8 39.8 59.3 74.4 85.4 91.6 95.5 97.6 98.6 99.6 99.9 100.0 100.0 100.0 100.0 8:19 v5 2DI 6.40 n/a 82 0.471 41.9 121 7.4 17.2 32.9 49.5 63.4 75.5 84.0 90.2 94.0 96.1 97.5 98.5 99.2 99.7 99.9 100.0 8:23 v6 2DI 6.55 n/a 83 0.417 51.6 129 6.9 16.5 32.5 49.7 64.6 77.3 85.4 91.1 94.9 97.2 98.5 99.3 99.5 99.8 99.9 100.0 8:26 v7 2DI 6.71 n/a 85 0.403 42.5 117 7.7 17.9 34.5 52.4 67.5 80.0 87.8 92.9 96.0 97.8 99.0 99.7 99.9 100.0 100.0 100.0 8:31 v8 2DI 6.55 n/a 86 0.319 73.9 141 7.0 16.3 31.9 49.0 63.8 76.9 85.6 91.8 95.5 97.4 98.7 99.5 99.7 99.9 100.0 100.0 8:34 v9 4DI 4.72 n/a 115 0.350 45.6 91.9 9.4 22.1 41.8 61.1 75.8 86.8 92.9 96.4 97.8 98.4 99.3 99.8 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-77-bag-type nonomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section A on August 25, 2007; 

verticals 1 through 9 located respectively at stations 78, 100, 122, 144, 165, 187, 209, 231, and 252 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 56 and 274 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:42-9:19

EWI-5v n/a n/a 357 n/a 44.9 137 6.5 15.4 30.4 46.8 61.3 74.2 83.4 90.2 94.7 97.2 98.6 99.4 99.7 99.9 100.0 100.0 

8:45-9:16

EWI-3v n/a n/a 243 n/a 36.4 120 7.4 17.0 32.8 49.6 64.3 77.0 85.7 91.9 95.7 97.6 98.6 99.1 99.4 99.8 99.9 100.0 

8:42- 9:19

EWI-9v n/a n/a 702 n/a 39.8 133 6.9 16.1 31.2 47.7 62.1 74.9 83.9 90.6 94.9 97.2 98.5 99.3 99.6 99.8 99.9 100.0 

8:42 v1 2DI 4.57 n/a 57 0.465 62.7 140 6.4 15.3 30.5 47.1 61.7 74.8 84.0 90.5 94.3 96.2 97.8 98.9 99.3 99.7 99.9 100.0 8:45 v2 2DI 7.47 n/a 95 0.422 34.9 132 7.0 16.4 31.8 48.6 63.3 76.3 85.2 91.4 95.2 97.1 98.2 98.9 99.3 99.7 99.9 100.0 8:50 v3 2DI 8.53 n/a 108 0.571 43.5 149 6.1 14.6 28.7 44.5 58.6 71.6 81.0 88.3 93.7 96.8 98.5 99.5 99.9 100.0 100.0 100.0 8:54 v4 2DI 8.23 n/a 104 0.667 33.7 133 6.8 16.0 31.2 47.7 62.0 75.0 84.1 91.1 95.5 97.6 98.7 99.3 99.6 99.8 99.9 100.0 8:59 v5 2DI 7.16 n/a 92 0.505 35.3 112 7.6 17.3 33.2 50.0 64.4 77.0 85.6 91.9 95.8 97.8 98.8 99.3 99.6 99.8 99.9 100.0 9:04 v6 2DI 7.01 n/a 90 0.430 34.0 124 8.3 18.2 33.8 49.9 63.5 75.4 83.6 89.6 93.7 96.3 97.7 98.7 99.2 99.7 99.9 100.0 9:08 v7 4DI 5.94 n/a 148 0.141 39.4 172 6.2 15.0 30.4 47.7 63.0 76.5 85.6 92.2 96.2 98.3 99.5 99.9 100.0 100.0 100.0 100.0 9:14 v8 4DI 4.42 n/a 112 0.086 61.1 93.2 9.4 21.1 39.4 58.0 73.1 84.9 92.8 97.8 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:19 v9 4DI 2.29 n/a 52 0.111 84.6 98.4 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section B on August 25, 2007; 

verticals 1 through 9 located respectively at stations 44, 67, 91, 114, 138, 161, 185, 208, and 232 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 20 and 255 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:38-

10:19

EWI-5v n/a n/a 336 n/a 26.7 69.0 8.3 19.3 37.0 55.2 70.1 82.1 89.6 94.3 96.7 97.9 98.8 99.5 99.8 99.9 100.0 100.0 

9:43- 

10:15

EWI-3v n/a n/a 253 n/a 27.2 60.5 8.6 20.2 38.6 57.2 71.9 83.5 90.4 94.7 97.0 98.1 99.0 99.5 99.8 99.9 100.0 100.0 

9:38-

10:19

EWI-9v n/a n/a 671 n/a 27.4 65.5 8.6 19.9 38.0 56.4 71.2 83.0 90.2 94.8 97.1 98.2 99.1 99.7 99.9 100.0 100.0 100.0 

9:38 v1 4DI 3.05 n/a 73 0.620 28.4 67.6 8.8 20.7 39.7 59.1 74.2 85.7 92.2 96.1 97.9 98.8 99.6 99.9 100.0 100.0 100.0 100.0 9:43 v2 2DI 7.77 n/a 98 0.559 29.7 59.7 8.7 20.7 39.6 58.5 73.1 84.6 91.7 96.2 98.1 98.9 99.7 99.9 100.0 100.0 100.0 100.0 9:47 v3 2DI 7.16 n/a 88 0.656 26.4 83.5 7.4 17.2 33.2 50.4 65.3 78.3 87.0 93.0 96.4 98.0 98.9 99.7 99.9 100.0 100.0 100.0 9:52 v4 2DI 6.55 n/a 81 0.807 23.7 56.4 9.8 22.1 41.1 60.0 74.7 85.7 91.8 95.3 97.1 98.1 99.0 99.6 99.8 100.0 100.0 100.0 9:57 v5 2DI 6.10 n/a 77 0.738 23.5 49.5 10.0 22.5 41.8 60.6 74.9 85.3 90.9 94.0 95.7 96.7 97.8 98.6 99.3 99.7 99.9 100.0 

10:02 v6 2DI 6.25 n/a 78 0.690 31.1 61.4 9.6 21.8 40.7 59.0 73.3 84.6 91.6 96.0 97.9 98.6 99.5 99.9 100.0 100.0 100.0 100.0 10:07 v7 2DI 6.40 n/a 78 0.607 31.0 80.9 7.7 18.3 35.8 54.2 69.5 82.1 90.0 94.9 97.2 98.1 99.0 99.7 99.9 100.0 100.0 100.0 10:14 v8 2DI 6.25 n/a 78 0.607 28.5 74.5 7.4 17.8 35.2 53.4 68.5 80.8 88.7 93.9 96.9 98.4 99.4 99.9 100.0 100.0 100.0 100.0 10:19 v9 4DI 4.42 n/a 112 0.441 24.7 57.8 9.6 21.6 40.4 59.4 74.1 85.3 91.5 95.2 97.1 98.3 99.3 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at River-mile 30 sediment station cross section A on August 25, 2007; 

verticals 1 through 9 located respectively at stations 78, 100, 122, 144, 165, 187, 209, 231, and 252 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 56 and 274 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:27-11:06

EWI-5v n/a n/a 323 n/a 24.3 73.3 7.6 17.3 33.1 50.1 64.7 77.4 86.0 92.2 96.2 98.3 99.3 99.9 100.0 100.0 100.0 100.0 

10:30-11:02

EWI-3v n/a n/a 226 n/a 24.0 72.0 7.9 17.9 34.1 51.2 65.8 78.3 86.6 92.6 96.3 98.1 99.2 99.8 99.9 100.0 100.0 100.0 

10:27-11:06

EWI-9v n/a n/a 648 n/a 24.9 74.9 7.6 17.5 33.7 51.0 65.7 78.3 86.6 92.5 96.2 98.1 99.2 99.8 99.9 100.0 100.0 100.0 

10:27 v1 2DI 3.75 n/a 48 0.540 24.9 67.3 7.2 17.2 33.9 52.4 68.3 81.5 90.2 96.0 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 10:30 v2 2DI 7.16 n/a 91 0.722 22.5 73.2 8.1 18.2 34.2 51.2 65.8 78.3 86.8 92.7 96.4 98.1 99.1 99.7 99.9 99.9 100.0 100.0 10:34 v3 2DI 8.23 n/a 104 0.717 23.4 76.2 7.7 17.3 32.6 49.0 63.4 76.0 84.6 91.0 95.4 98.0 99.2 99.8 100.0 100.0 100.0 100.0 10:39 v4 2DI 7.92 n/a 100 0.803 28.0 84.9 7.1 16.8 33.1 50.5 65.4 78.1 86.4 92.3 95.8 97.7 98.9 99.6 99.8 99.9 100.0 100.0 10:44 v5 2DI 6.86 n/a 85 0.617 24.7 73.1 7.6 17.5 33.5 50.6 65.0 77.5 86.0 92.2 96.2 98.2 99.3 99.9 100.0 100.0 100.0 100.0 10:49 v6 2DI 6.71 n/a 84 0.651 24.5 70.9 7.9 18.4 35.6 53.7 68.7 80.9 88.5 93.4 96.2 97.9 99.1 99.8 100.0 100.0 100.0 100.0 10:54 v7 4DI 5.64 n/a 140 0.310 22.6 78.4 7.5 17.0 33.0 50.2 65.0 77.8 86.4 92.4 95.8 97.5 99.0 99.8 100.0 100.0 100.0 100.0 11:00 v8 4DI 4.11 n/a 99 0.276

6

28.5 62.1 8.3 19.0 36.0 54.2 69.3 81.4 89.0 93.9 96.6 98.1 99.2 99.8 100.0 100.0 100.0 100.0 

11:05 v9 4DI 1.98 n/a 32 0.186 49.9 19.6 --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw labora

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
Data collected at the Lower Marble Canyon gaging station P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on September 22, 1998; vertical located at the station 180 ft from the right-bank end point of the cable

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:38 Up DI 5.30 n/a 13.22 1.300 210 148 11.5 30.9 49.3 67.4 79.9 88.3 95.0 96.1 96.7 96.7 98.7 100.0 100.0 100.0 100.0 100.0 8:47 Point 5.31 0.15 14.10 0.582 273 407 6.2 13.8 28.5 45.0 57.4 71.8 80.2 85.0 88.4 92.9 100.0 100.0 100.0 100.0 100.0 100.0 8:57 Point 5.31 0.06 20.00 0.673 230 613 4.5 9.3 14.7 21.5 31.2 42.3 55.0 64.0 76.0 86.1 93.0 100.0 100.0 100.0 100.0 100.0 9:05 Point 5.31 0.12 20.00 0.641 276 639 5.9 12.6 17.7 23.7 32.5 42.9 55.1 67.4 77.3 89.3 96.5 99.8 100.0 100.0 100.0 100.0 9:08 Point 5.31 0.45 16.00 1.047 260 414 6.7 14.3 22.0 31.6 44.2 62.8 80.6 85.2 91.5 96.1 99.9 100.0 100.0 100.0 100.0 100.0 9:13 Point 5.31 0.45 16.00 1.062 246 375 7.6 15.8 25.0 38.4 57.2 75.3 84.0 90.0 94.3 98.0 99.5 99.9 100.0 100.0 100.0 100.0 9:16 Point 5.31 0.45 16.00 1.158 231 479 6.9 13.6 20.5 28.8 37.4 50.7 71.3 84.2 90.6 95.4 99.1 100.0 100.0 100.0 100.0 100.0 9:20 Point 5.31 1.06 15.00 0.963 241 264 11.3 24.9 36.7 51.7 68.2 84.4 92.0 95.3 99.4 99.8 100.0 100.0 100.0 100.0 100.0 100.0 9:23 Point 5.31 1.06 15.00 1.375 234 254 9.5 20.5 31.0 44.7 64.0 84.0 92.0 94.9 98.0 99.5 100.0 100.0 100.0 100.0 100.0 100.0 9:26 Point 5.31 1.06 15.00 1.205 253 310 9.4 19.4 31.5 45.8 60.7 73.3 87.2 92.0 96.5 99.9 100.0 100.0 100.0 100.0 100.0 100.0 9:29 Point 5.31 2.13 12.00 1.453 240 209 10.9 26.6 41.9 56.1 74.4 86.5 94.0 97.2 99.5 99.9 100.0 100.0 100.0 100.0 100.0 100.0 9:33 Point 5.31 2.13 12.00 1.464 237 190 14.7 26.2 42.2 56.9 72.3 86.5 93.8 98.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:35 Point 5.31 2.13 12.00 1.500 227 157 13.0 32.3 49.2 66.0 82.7 89.4 96.2 99.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:39 Point 5.31 3.33 10.00 1.408 220 222 11.1 21.5 37.3 53.5 74.8 88.7 95.9 98.4 99.7 99.9 100.0 100.0 100.0 100.0 100.0 100.0 9:42 Point 5.31 3.33 11.00 1.422 238 151 16.0 29.6 46.3 68.4 82.3 91.8 99.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:45 Point 5.31 3.33 11.00 1.577 224 115 18.0 41.3 57.7 73.9 84.9 96.2 98.2 98.4 98.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:50 Point 5.31 4.96 8.00 1.468 217 70.1 32.0 62.8 76.9 90.4 99.6 99.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:51 Point 5.31 4.96 10.00 1.554 217 75.0 23.0 51.4 72.6 89.6 97.5 99.3 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:53 Point 5.31 4.96 10.00 1.555 195 69.3 30.4 54.6 73.2 93.0 98.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 9:59 Up DI 5.27 n/a 16.80 1.297 232 173 11.7 27.5 41.7 55.7 72.0 85.4 90.9 93.9 95.6 98.2 99.4 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.

P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on September 22, 1998; vertical located at the station 280 ft from the right-bank end point of the cable

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:11 Up DI 4.76 n/a 12.90 0.945 239 123 19.9 41.1 58.0 70.6 84.1 91.4 97.0 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:17 Point 4.75 0.15 20.00 0.925 244 438 5.5 11.9 19.0 26.8 36.0 48.5 61.0 69.6 81.6 91.2 98.5 100.0 100.0 100.0 100.0 100.0 10:20 Point 4.75 0.15 18.00 0.884 264 382 6.9 17.6 24.8 35.3 46.4 57.3 66.8 73.8 84.7 94.7 99.2 100.0 100.0 100.0 100.0 100.0 10:23 Point 4.75 0.15 18.00 0.935 273 372 7.6 15.7 22.2 30.5 41.5 53.2 63.1 72.7 82.1 89.9 96.8 100.0 100.0 100.0 100.0 100.0 10:26 Point 4.75 0.46 15.00 0.993 239 214 9.7 23.5 35.3 50.4 68.1 83.5 90.4 93.3 97.2 97.9 98.5 99.6 100.0 100.0 100.0 100.0 10:29 Point 4.75 0.46 16.00 1.005 243 293 7.7 18.8 32.2 43.7 54.4 67.6 77.9 84.0 92.6 96.9 99.5 100.0 100.0 100.0 100.0 100.0 10:31 Point 4.75 0.46 16.00 1.053 254 228 11.4 20.6 31.0 43.6 63.6 76.4 82.5 88.3 92.6 97.8 100.0 100.0 100.0 100.0 100.0 100.0 10:35 Point 4.75 0.92 13.00 1.324 229 168 13.4 25.5 42.1 59.5 74.7 85.4 90.6 94.4 98.8 99.7 100.0 100.0 100.0 100.0 100.0 100.0 10:37 Point 4.75 0.92 13.00 1.174 244 178 12.5 27.7 50.0 64.2 79.9 91.8 95.1 98.1 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:40 Point 4.75 0.92 13.00 1.388 242 121 13.1 28.3 47.6 67.3 80.9 89.4 92.0 95.7 99.1 99.8 100.0 100.0 100.0 100.0 100.0 100.0 10:42 Point 4.75 1.82 10.00 1.161 237 171 12.6 23.6 43.0 63.2 76.1 85.0 94.5 97.4 99.5 99.9 100.0 100.0 100.0 100.0 100.0 100.0 10:45 Point 4.75 1.82 11.00 1.323 242 125 12.6 33.5 59.8 73.4 87.9 93.3 98.3 99.3 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:54 Point 4.75 1.82 11.00 1.338 235 150 15.0 39.4 54.9 70.4 81.6 90.3 97.1 99.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:56 Point 4.75 3.03 9.00 1.434 248 123 19.3 38.3 54.7 72.8 85.0 93.6 97.0 97.2 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:59 Point 4.75 3.03 10.00 1.379 227 119 21.1 43.9 62.6 76.6 89.8 96.8 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:01 Point 4.75 3.03 10.00 1.268 253 120 22.0 39.7 60.0 75.5 88.8 98.0 99.3 99.7 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:04 Point 4.75 4.40 9.00 1.464 195 69.3 30.4 54.6 73.2 93.0 98.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:09 Point 4.75 4.40 10.00 1.443 248 117 21.5 39.0 62.3 80.2 93.6 99.5 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:11 Point 4.75 4.40 10.00 1.348 270 199 9.7 23.3 37.4 61.5 87.7 96.1 99.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:14 Up DI 4.78 n/a 11.16 0.919 309 319 10.6 20.7 34.7 52.2 78.0 88.3 92.4 93.2 95.3 95.6 99.4 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.
P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on February 8, 2006; vertical located at the station 295 ft from the former right-bank end point of the cab

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:54 Point 3.81 0.41 25.12 0.791 15.2 37.1 7.1 17.4 32.5 47.5 61.5 71.0 80.5 86.9 91.4 92.9 97.3 99.5 100.0 100.0 100.0 100.0 14:57 Point 3.81 0.26 35.19 0.730 17.1 33.6 8.8 19.6 35.7 51.6 64.0 72.6 80.0 86.5 90.7 94.5 98.6 99.7 100.0 100.0 100.0 100.0 14:59 Point 3.81 0.26 41.10 0.730 13.7 30.6 9.5 20.6 36.9 53.0 66.1 75.9 83.5 89.6 93.9 97.6 99.6 99.9 100.0 100.0 100.0 100.0 15:02 Point 3.81 0.87 40.47 0.918 13.7 23.8 11.1 25.1 45.6 65.2 80.1 89.6 95.5 98.7 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:04 Point 3.81 0.87 40.56 0.898 12.4 23.2 12.1 26.4 46.6 65.8 79.9 88.3 94.3 98.2 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:08 Point 3.81 0.87 37.44 0.793 13.1 22.6 12.3 27.6 47.8 60.0 77.5 84.3 87.5 91.7 94.2 94.3 94.6 99.5 100.0 100.0 100.0 100.0 15:10 Point 3.81 1.48 36.90 0.894 12.5 23.4 11.2 24.9 44.3 62.1 75.6 85.7 92.6 97.5 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:12 Point 3.81 1.48 37.09 1.043 29.5 31.5 14.3 31.4 53.8 73.4 86.5 94.1 97.8 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:15 Point 3.81 1.48 33.97 1.034 10.8 19.4 13.0 29.3 51.9 71.9 85.8 93.1 96.7 98.2 98.8 99.0 99.3 99.9 100.0 100.0 100.0 100.0 15:18 Point 3.81 2.40 33.35 1.058 11.9 16.4 11.7 26.3 47.9 60.9 79.9 85.6 93.3 97.2 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:20 Point 3.81 2.40 33.12 1.086 11.1 19.8 12.3 26.7 46.5 65.1 79.2 87.7 94.1 98.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:22 Point 3.81 2.40 39.29 0.905 12.4 20.4 10.5 23.7 43.0 61.9 76.3 86.1 93.1 97.8 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:24 Point 3.81 3.31 33.31 1.080 10.3 11.9 13.6 29.9 51.3 70.0 82.6 89.3 94.0 96.7 98.1 98.3 98.8 99.8 99.9 100.0 100.0 100.0 15:27 Point 3.81 3.31 33.15 1.038 10.9 12.8 14.4 30.1 49.2 65.2 75.5 80.2 83.5 86.4 87.8 88.2 92.3 98.7 99.6 100.0 100.0 100.0 15:29 Point 3.81 3.31 33.38 1.021 11.9 13.3 11.1 23.0 38.7 52.2 61.6 67.1 71.0 75.0 79.4 83.8 89.2 95.3 98.8 99.5 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 

P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on February 8, 2006; vertical located at the station 165 ft from the former right-bank end point of the cab

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:33 Point 4.57 0.41 40.13 0.646 7.81 52.4 6.5 14.3 26.1 38.3 49.4 59.6 69.0 78.9 87.5 93.6 98.1 99.7 100.0 100.0 100.0 100.0 15:35 Point 4.57 0.41 41.28 0.700 12.9 43.0 6.2 13.7 25.3 37.7 49.0 60.0 70.3 80.6 89.2 95.0 98.4 99.7 100.0 100.0 100.0 100.0 15:37 Point 4.57 0.41 42.44 0.757 13.2 45.7 6.1 14.0 26.7 40.2 52.4 63.9 73.9 83.0 90.3 95.7 99.0 99.8 100.0 100.0 100.0 100.0 15:40 Point 4.57 0.87 35.22 0.955 13.1 32.3 8.0 18.2 33.1 47.6 59.2 68.6 76.8 84.9 91.0 95.5 98.6 99.8 100.0 100.0 100.0 100.0 15:42 Point 4.57 0.87 33.39 0.859 12.6 40.8 6.4 15.1 29.4 45.1 58.8 69.4 78.6 86.9 92.6 96.5 99.2 99.9 100.0 100.0 100.0 100.0 15:44 Point 4.57 0.87 34.91 0.921 33.2 43.2 5.9 13.7 26.3 40.0 52.1 62.4 72.1 82.2 90.1 94.8 98.3 99.7 100.0 100.0 100.0 100.0 15:47 Point 4.57 1.48 33.19 1.111 11.4 27.1 8.9 20.1 36.9 54.0 67.9 77.9 85.8 92.4 95.8 97.5 99.2 99.9 100.0 100.0 100.0 100.0 15:49 Point 4.57 1.48 32.93 1.075 11.1 29.9 10.3 22.6 40.4 58.8 73.7 83.1 90.0 95.1 97.4 98.1 99.4 99.9 100.0 100.0 100.0 100.0 15:51 Point 4.57 1.48 33.19 1.028 9.11 38.8 9.7 22.1 40.3 57.8 71.1 79.8 85.8 90.8 93.5 95.9 99.0 99.8 100.0 100.0 100.0 100.0 15:53 Point 4.57 2.40 32.03 0.957 13.5 24.0 9.9 22.8 42.1 61.3 76.3 85.5 91.9 97.0 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:55 Point 4.57 2.40 32.28 1.133 12.5 22.1 11.1 25.2 45.7 65.4 80.2 88.7 94.3 98.2 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:57 Point 4.57 2.40 32.04 1.123 12.1 23.2 10.6 24.0 43.2 62.2 76.5 85.3 92.7 97.6 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 11, 2006; vertical located at the station 295 ft from the former right-bank end point of the cabl

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm 

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:56 Point 4.33 0.47 30.10 0.844 60.2 170 8.3 18.8 35.1 51.9 65.8 77.5 85.6 91.5 95.2 97.0 98.4 99.3 99.8 99.9 100.0 100.0 10:59 Point 4.33 0.47 30.40 0.893 55.8 148 9.9 21.7 39.1 56.2 69.7 80.7 88.0 93.2 96.2 97.6 98.7 99.7 99.9 100.0 100.0 100.0 11:01 Point 4.33 0.47 30.30 0.845 54.7 135 8.7 19.5 36.1 52.9 66.7 78.2 86.2 91.9 95.1 96.8 98.6 99.7 99.9 100.0 100.0 100.0 11:05 Point 4.33 1.18 30.40 0.990 51.1 103 11.0 24.2 43.5 61.9 76.0 86.8 93.6 97.9 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:07 Point 4.33 1.18 30.20 1.037 49.4 102 10.1 22.4 40.7 58.0 71.3 81.7 88.4 93.2 95.9 97.5 99.1 99.8 100.0 100.0 100.0 100.0 11:10 Point 4.33 1.18 25.00 1.109 44.4 103 10.7 23.0 40.7 57.4 70.4 80.8 87.6 92.6 95.7 97.6 99.3 99.9 100.0 100.0 100.0 100.0 11:13 Point 4.33 1.69 25.20 1.148 47.4 80.1 13.2 28.1 48.6 66.6 79.2 87.8 92.6 95.7 97.3 98.3 99.5 99.9 100.0 100.0 100.0 100.0 11:16 Point 4.33 1.69 25.30 1.217 44.9 81.9 13.3 27.9 47.5 64.4 76.1 83.9 88.4 91.3 92.6 93.1 94.1 94.3 95.5 98.0 99.3 100.0 11:18 Point 4.33 1.69 23.20 1.199 44.1 79.4 12.9 27.6 47.9 66.3 80.3 90.2 95.8 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:20 Point 4.33 2.15 19.70 1.024 43.3 62.2 10.5 23.9 43.9 61.8 74.5 83.4 88.8 92.4 93.8 94.8 97.3 99.0 99.7 99.9 100.0 100.0 11:22 Point 4.33 2.15 23.00 1.127 44.7 82.3 11.3 24.9 44.5 62.4 75.7 85.4 91.3 95.2 97.1 98.1 99.5 99.9 100.0 100.0 100.0 100.0 11:24 Point 4.33 2.15 23.00 1.172 40.0 54.5 11.8 26.4 47.3 66.3 80.4 89.7 95.1 98.5 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:27 Point 4.33 3.22 23.20 1.031 36.2 53.0 12.1 27.5 50.0 70.1 83.9 92.8 97.3 99.3 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:29 Point 4.33 3.22 22.90 1.177 52.7 58.3 15.0 31.5 53.7 72.5 85.1 93.1 97.2 99.2 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:31 Point 4.33 3.22 30.00 1.024 49.0 62.1 14.9 31.6 53.9 72.8 85.6 93.5 97.3 99.2 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 

P-61 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 11, 2006; vertical located at the station 165 ft from the former right-bank end point of the cabl

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:35 Point 4.97 0.81 29.50 0.912 51.0 174 6.4 15.5 30.8 47.1 61.3 73.7 82.6 89.5 94.3 97.0 98.5 99.6 99.8 99.9 100.0 100.0 11:37 Point 4.97 0.81 29.70 1.116 50.7 146 7.9 17.3 31.4 46.1 58.7 70.2 79.2 86.9 92.8 96.6 98.7 99.7 99.9 100.0 100.0 100.0 11:40 Point 4.97 0.81 27.10 0.976 52.4 171 6.6 15.4 29.4 44.5 58.1 70.5 79.8 87.6 93.1 96.3 98.0 98.9 99.3 99.7 99.9 100.0 11:43 Point 4.97 1.36 28.20 0.940 65.7 130 8.4 19.3 36.0 53.0 67.1 78.7 86.7 92.7 96.4 98.2 99.5 99.9 100.0 100.0 100.0 100.0 11:45 Point 4.97 1.36 25.90 0.927 53.9 159 7.6 17.7 33.7 50.2 64.4 76.6 85.3 91.8 95.9 98.0 99.5 99.9 100.0 100.0 100.0 100.0 11:47 Point 4.97 1.36 26.40 1.152 52.1 116 8.9 20.1 37.4 54.7 68.7 80.2 88.0 93.6 96.9 98.2 99.3 99.9 100.0 100.0 100.0 100.0 11:50 Point 4.97 1.88 24.90 1.228 36.0 76.7 10.2 23.1 42.5 61.2 75.5 86.5 93.3 97.9 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:52 Point 4.97 1.88 23.00 1.286 44.1 95.8 11.4 24.7 43.6 60.9 73.9 83.8 90.1 94.4 96.5 97.8 99.4 99.9 100.0 100.0 100.0 100.0 11:54 Point 4.97 1.88 24.00 1.059 51.0 107 8.2 18.7 34.9 51.3 64.8 76.6 85.4 92.3 96.2 98.1 99.6 99.9 100.0 100.0 100.0 100.0 11:57 Point 4.97 2.82 22.80 1.385 54.3 52.3 12.2 27.0 48.7 68.3 82.0 90.9 95.7 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:59 Point 4.97 2.82 19.70 1.201 44.4 81.5 10.4 23.5 43.2 61.9 76.1 86.6 93.4 97.9 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:01 Point 4.97 2.82 20.70 1.198 55.4 92.3 9.5 21.2 39.4 57.5 72.2 84.1 92.0 97.4 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:03 Point 4.97 3.86 24.70 1.212 42.2 43.0 15.3 32.2 54.8 73.8 86.1 93.4 97.0 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:05 Point 4.97 3.86 22.30 1.397 49.6 50.6 11.8 27.0 48.7 68.2 82.1 91.3 96.6 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:08 Point 4.97 3.86 22.10 1.248 54.5 60.8 11.1 24.4 44.1 62.6 76.9 87.6 94.0 98.2 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; point-sample elevations are relative to the mean bed elevation associated with this 
D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on February 27, 2007; 

verticals 1 through 9 located respectively at stations 64, 88, 112, 136, 160, 184, 208, 232, and 256 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 40 and 280 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:37-15:45

EWI-5v n/a n/a 369 n/a 18.4 29.1 13.4 28.3 47.6 63.7 74.9 82.8 88.0 92.1 95.3 97.6 99.1 99.7 99.8 99.9 100.0 100.0 

14:44-15:40

EWI-3v n/a n/a 274 n/a 17.5 24.0 15.3 31.1 50.2 65.3 75.8 82.5 86.5 90.1 93.7 97.2 99.3 99.9 100.0 100.0 100.0 100.0 

14:37- 15:45

EWI-9v n/a n/a 733 n/a 18.7 26.1 13.7 28.9 48.2 64.0 74.9 82.5 87.3 91.2 94.6 97.3 99.1 99.8 99.9 100.0 100.0 100.0 

14:37 v1 6DI 1.98 n/a 34 0.557 38.7 30.5 14.4 33.0 59.1 80.9 93.5 98.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:44 v2 6DI 3.05 n/a 56 0.970 17.7 26.4 15.3 29.5 46.3 59.9 70.2 76.3 80.1 84.7 90.7 96.6 99.3 99.9 100.0 100.0 100.0 100.0 14:50 v3 6DI 3.05 n/a 56 1.010 18.3 26.4 12.2 26.9 47.3 64.9 77.2 86.0 91.4 95.2 97.2 98.1 99.4 99.9 100.0 100.0 100.0 100.0 14:54 v4 6DI 4.27 n/a 77 1.162 21.7 24.3 13.7 30.3 52.1 69.8 81.3 89.0 93.1 95.7 97.2 98.5 99.5 99.9 100.0 100.0 100.0 100.0 15:02 v5 6DI 5.36 n/a 100 1.103 17.7 27.7 15.4 30.6 48.5 62.7 72.8 79.4 83.8 87.9 92.1 96.3 99.1 99.9 100.0 100.0 100.0 100.0 15:10 v6 6DI 6.10 n/a 113 1.102 18.8 25.0 13.4 27.2 43.8 57.1 66.8 73.9 79.0 84.2 89.6 94.9 98.4 99.7 100.0 100.0 100.0 100.0 15:25 v7 6DI 6.31 n/a 118 1.022 17.6 35.6 12.0 25.9 44.3 60.0 71.3 80.4 86.8 91.8 95.5 97.6 98.7 99.4 99.6 99.8 99.9 100.0 15:34 v8 6DI 6.25 n/a 118 0.871 17.2 18.8 15.2 33.0 55.8 73.5 84.7 91.9 95.5 97.6 98.5 99.0 99.7 100.0 100.0 100.0 100.0 100.0 15:43 v9 6DI 3.81 n/a 61 0.694 13.6 17.3 14.6 32.2 55.1 73.6 85.2 92.3 96.2 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thr

indicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on February 27, 2007; 

verticals 1 through 9 located respectively at stations 97, 130, 165, 196, 229, 262, 295, 328, and 361 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 64 and 396 ft from the left-bank 

Time

(MST)

Sample

type 

Water

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

16:00-16:58

EWI-5v n/a n/a 365 n/a 36.9 33.7 17.1 35.0 56.3 71.8 80.8 86.1 89.3 91.8 94.0 96.6 98.5 99.4 99.7 99.9 100.0 100.0 

16:04-16:51

EWI-3v n/a n/a 220 n/a 29.6 29.5 17.0 36.7 61.2 79.1 89.2 94.7 97.3 98.6 99.1 99.5 99.8 100.0 100.0 100.0 100.0 100.0 

16:00- 16:58

EWI-9v n/a n/a 654 n/a 32.2 31.8 17.2 35.7 58.1 74.6 84.0 89.4 92.3 94.3 95.9 97.5 98.8 99.4 99.7 99.9 100.0 100.0 

16:54 v1 8DI 4.42 n/a 108 1.073 49.0 41.7 16.8 34.6 55.7 70.9 79.7 85.0 88.2 90.8 93.1 95.7 97.8 98.9 99.4 99.8 99.9 100.0 16:48 v2 8DI 3.05 n/a 84 0.983 34.2 34.1 17.1 37.7 63.4 82.0 91.8 96.8 98.8 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:40 v3 8DI 2.99 n/a 70 0.966 32.8 37.7 16.8 33.4 52.8 66.9 75.5 80.8 84.5 88.0 91.6 96.0 98.9 99.8 100.0 100.0 100.0 100.0 16:33 v4 8DI 2.83 n/a 69 0.938 20.9 34.9 17.5 35.7 58.4 75.6 85.8 91.8 94.6 96.1 96.7 97.3 98.1 98.7 99.1 99.6 99.9 100.0 16:27 v5 8DI 2.99 n/a 72 0.883 27.0 26.9 16.9 35.5 58.3 75.3 85.4 91.5 94.7 96.6 97.6 98.4 99.4 99.9 100.0 100.0 100.0 100.0 16:11 v6 8DI 2.93 n/a 72 0.687 20.8 17.2 17.2 36.6 60.7 78.7 89.2 95.0 97.6 99.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:08 v7 8DI 2.77 n/a 65 0.549 25.1 19.0 21.0 40.4 62.2 77.6 86.6 91.6 94.0 95.9 96.7 97.7 99.3 99.9 100.0 100.0 100.0 100.0 16:04 v8 8DI 2.26 n/a 64 0.396 20.8 21.1 16.9 35.1 58.2 76.2 87.6 94.3 97.7 99.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:00 v9 8DI 2.04 n/a 50 0.423 32.8 21.8 17.8 38.5 65.8 87.7 96.7 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on February 27, 2007; 

verticals 1 through 9 located respectively at stations 84, 118, 151, 185, 219, 253, 287, 321, and 354 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 50 and 388 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

17:21-18:55

EWI-5v n/a n/a 840 n/a 49.9 34.9 20.8 40.7 62.5 77.1 85.0 89.3 91.7 93.7 95.7 97.5 99.0 99.5 99.7 99.9 99.9 100.0 

17:28-18:49

EWI-3v n/a n/a 602 n/a 43.8 28.8 21.1 41.1 63.0 77.3 84.9 88.8 90.9 92.8 95.0 97.0 98.6 99.3 99.6 99.8 99.9 100.0 

17:21-18:55

EWI-9v n/a n/a 1660 n/a 47.5 35.2 21.7 41.5 63.0 77.3 85.2 89.5 91.8 93.8 95.7 97.5 99.0 99.5 99.7 99.9 100.0 100.0 

17:21 v1 8DI 1.89 n/a 84 0.189 50.4 34.6 23.6 44.8 67.6 82.8 91.4 95.9 98.0 99.3 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 17:28 v2 8DI 3.20 n/a 149 0.434 42.9 41.1 18.3 39.1 64.0 81.0 89.7 93.8 95.4 96.4 96.8 97.1 97.7 98.3 98.8 99.5 99.8 100.0 17:36 v3 8DI 3.35 n/a 172 0.598 53.6 43.1 22.1 41.5 62.0 75.8 83.6 87.7 89.9 92.3 94.7 97.1 99.3 99.9 100.0 100.0 100.0 100.0 17:44 v4 8DI 4.08 n/a 206 0.583 53.1 38.0 18.6 38.0 59.5 74.3 83.0 87.8 90.3 92.6 95.0 97.3 99.2 99.9 100.0 100.0 100.0 100.0 17:56 v5 8DI 4.48 n/a 209 0.891 50.4 29.0 21.1 41.5 63.3 77.3 84.8 88.6 90.8 93.0 95.5 97.7 99.4 99.9 100.0 100.0 100.0 100.0 18:09 v6 8DI 4.42 n/a 221 0.777 49.2 42.0 25.9 46.1 66.5 79.7 87.0 91.2 93.9 95.9 97.2 98.6 99.7 99.9 100.0 100.0 100.0 100.0 18:29 v7 8DI 4.27 n/a 219 0.544 49.8 40.7 18.5 37.7 60.0 75.6 84.3 89.6 92.4 94.4 95.8 96.9 98.1 98.6 99.0 99.5 99.8 100.0 18:40 v8 8DI 4.72 n/a 244 0.594 35.7 23.0 23.1 42.0 61.7 74.5 81.2 85.1 87.4 89.7 92.7 95.9 97.9 99.1 99.7 99.8 100.0 100.0 18:50 v9 8DI 3.35 n/a 156 0.199 34.6 20.7 24.7 48.4 73.6 89.6 96.9 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on February 28, 2007; 

verticals 1 through 9 located respectively at stations 64, 88, 112, 136, 160, 184, 208, 232, and 256 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 40 and 280 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:12- 12:03

EWI-5v n/a n/a 343 n/a 28.3 50.1 10.8 23.7 41.5 57.7 69.9 79.1 85.0 89.8 93.9 97.2 99.3 99.9 100.0 100.0 100.0 100.0 

11:15-11:56

EWI-3v n/a n/a 239 n/a 24.7 42.5 13.1 27.4 46.0 61.9 73.7 81.6 86.4 90.3 94.0 97.4 99.5 99.9 100.0 100.0 100.0 100.0 

11:12-12:03

EWI-9v n/a n/a 670 n/a 24.2 44.0 12.0 25.3 43.2 58.8 70.6 79.1 84.6 89.1 93.3 96.9 99.2 99.9 100.0 100.0 100.0 100.0 

11:12 v1 6DI 1.98 n/a 36 0.377 21.7 28.5 11.0 26.1 48.9 70.4 84.4 94.1 98.2 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:15 v2 6DI 3.05 n/a 49 0.743 21.1 31.0 14.7 30.8 52.4 71.0 83.7 92.1 96.5 99.0 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:20 v3 6DI 3.05 n/a 52 0.804 17.9 34.3 12.0 27.0 48.2 66.6 79.4 88.3 93.3 96.5 98.0 98.8 99.7 99.9 100.0 100.0 100.0 100.0 11:24 v4 6DI 4.27 n/a 75 0.713 22.3 41.8 12.6 25.6 42.0 55.9 66.7 74.2 79.3 84.2 89.8 95.8 99.0 99.9 100.0 100.0 100.0 100.0 11:31 v5 6DI 5.36 n/a 87 0.507 35.3 56.5 12.4 26.1 43.9 59.2 71.0 78.9 83.6 87.7 92.2 96.8 99.4 99.9 100.0 100.0 100.0 100.0 11:39 v6 6DI 6.10 n/a 100 0.904 20.4 40.4 13.0 26.5 43.8 58.5 69.4 77.2 82.4 87.1 91.5 95.6 98.7 99.8 100.0 100.0 100.0 100.0 11:47 v7 6DI 6.31 n/a 107 0.605 32.2 69.2 9.7 20.7 35.9 50.0 61.6 71.2 78.4 85.0 90.9 95.8 98.8 99.8 100.0 100.0 100.0 100.0 11:54 v8 6DI 6.25 n/a 103 0.762 20.4 39.9 13.1 27.2 45.3 60.8 72.2 80.1 85.0 89.3 93.3 97.0 99.3 99.9 100.0 100.0 100.0 100.0 12:02 v9 6DI 3.81 n/a 61 0.675 27.3 36.3 10.6 24.8 46.2 66.2 80.4 90.5 95.9 98.9 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical. 
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on February 28, 2007; 

verticals 1 through 9 located respectively at stations 97, 130, 165, 196, 229, 262, 295, 328, and 361 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 64 and 396 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:48-13:26

EWI-5v n/a n/a 245 n/a 21.5 48.7 12.3 25.9 44.4 60.6 72.4 81.0 86.6 90.8 93.8 96.2 98.2 99.1 99.5 99.8 99.9 100.0 

12:55-13:23

EWI-3v n/a n/a 135 n/a 21.9 43.4 15.1 30.8 50.6 66.6 77.4 84.6 89.0 92.1 94.8 97.6 98.7 99.1 99.4 99.7 99.9 100.0 

12:48-13:26

EWI-9v n/a n/a 424 n/a 21.0 43.7 13.0 27.4 46.7 63.3 74.9 83.1 88.3 92.0 94.7 97.2 98.8 99.4 99.7 99.9 99.9 100.0 

12:48 v1 6DI 4.42 n/a 78 0.746 19.1 48.4 13.2 26.2 42.7 56.8 67.4 75.6 81.8 86.9 91.4 95.7 98.8 99.8 100.0 100.0 100.0 100.0 12:55 v2 6DI 3.05 n/a 51 0.862 20.7 42.2 16.1 31.2 49.3 63.8 73.8 80.5 85.2 88.9 93.0 98.2 99.7 100.0 100.0 100.0 100.0 100.0 13:00 v3 6DI 2.59 n/a 44 0.866 21.7 51.8 10.7 23.5 42.1 59.1 71.5 80.6 86.1 90.1 93.0 95.2 97.1 98.4 99.0 99.6 99.9 100.0 13:06 v4 6DI 2.83 n/a 45 0.680 18.9 30.7 11.5 26.7 48.2 67.1 79.8 88.0 92.5 95.3 96.7 98.1 99.6 99.9 100.0 100.0 100.0 100.0 13:09 v5 6DI 2.99 n/a 48 0.638 24.2 48.3 14.4 29.6 49.5 65.9 77.1 84.8 89.3 92.3 94.0 95.4 96.8 97.6 98.4 99.3 99.8 100.0 13:14 v6 6DI 2.93 n/a 47 0.575 21.1 33.6 13.1 29.5 52.5 71.9 84.6 92.7 96.9 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:17 v7 6DI 2.77 n/a 45 0.515 20.2 48.4 9.7 22.4 41.5 59.7 73.4 83.9 90.6 95.1 97.2 98.1 99.4 99.9 100.0 100.0 100.0 100.0 13:21 v8 6DI 2.26 n/a 36 0.589 20.8 38.7 14.2 31.9 55.4 74.3 86.2 93.5 97.1 99.2 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:25 v9 6DI 2.04 n/a 30 0.510 26.8 43.8 13.3 29.7 52.3 71.2 83.8 91.8 96.1 98.9 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on February 28, 2007; 

verticals 1 through 9 located respectively at stations 84, 118, 151, 185, 219, 253, 287, 321, and 354 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 50 and 388 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

13:33-14:14

EWI-5v n/a n/a 291 n/a 26.3 34.2 12.6 28.3 50.4 69.6 82.7 91.4 95.9 98.0 99.0 99.4 99.8 100.0 100.0 100.0 100.0 100.0 

13:36-14:10

EWI-3v n/a n/a 204 n/a 23.8 36.6 12.9 27.8 48..3 66.1 78.4 87.0 92.0 95.2 96.8 97.7 98.7 99.2 99.3 99.7 99.9 100.0 

13:33- 14:14

EWI-9v n/a n/a 559 n/a 25.4 35.9 13.1 28.6 49.7 68.0 80.6 89.1 93.8 96.4 97.6 98.2 98.9 99.3 99.5 99.8 99.9 100.0 

13:33 v1 6DI 1.89 n/a 33 0.236 65.3 35.2 13.6 28.3 48.1 66.3 80.6 91.7 97.3 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:36 v2 6DI 3.20 n/a 51 0.324 29.5 39.1 17.0 34.1 56.1 74.2 85.9 93.4 97.4 99.3 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:40 v3 6DI 3.35 n/a 57 0.536 26.7 33.8 13.5 30.8 54.6 74.5 87.2 94.8 98.2 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:44 v4 6DI 4.08 n/a 65 0.632 27.4 34.4 13.3 29.0 49.9 67.3 79.1 87.3 91.8 94.6 96.2 97.1 98.4 99.2 99.4 99.8 99.9 100.0 13:47 v5 6DI 4.48 n/a 75 0.789 22.4 30.7 12.4 27.4 48.4 66.4 78.7 87.1 92.1 95.3 97.2 98.3 99.5 99.9 100.0 100.0 100.0 100.0 13:57 v6 6DI 4.42 n/a 74 0.723 21.4 34.7 14.0 29.4 49.7 66.7 78.5 86.8 91.6 94.6 96.2 97.0 97.9 98.4 98.8 99.5 99.8 100.0 14:02 v7 6DI 4.27 n/a 72 0.527 24.8 38.3 10.8 25.6 47.8 68.5 83.1 93.0 97.7 99.5 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:08 v8 6DI 4.72 n/a 78 0.438 23.4 45.7 34.5 60.4 86.6 97.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14:12 v9 6DI 3.35 n/a 54 0.238 24.3 39.1 20.7 38.6 57.4 70.2 77.4 81.2 83.9 86.7 90.1 95.9 98.8 99.8 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 28, 2007; 

verticals 1 through 9 located respectively at stations 114, 148, 182, 216, 250, 284, 318, 352, and 386 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 80 and 420 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

13:02-13:24

EWI-5v n/a n/a 115.8 n/a 1510 134 11.0 24.9 45.2 64.0 77.6 87.1 92.4 95.6 97.2 98.1 99.2 99.8 99.9 100.0 100.0 100.0 

13:03- 13:21

EWI-3v n/a n/a 79.3 n/a 1520 160 10.3 23.6 43.3 62.0 75.9 85.9 91.6 95.1 96.7 97.6 98.8 99.5 99.7 99.9 100.0 100.0 

13:02-13:24

EWI-9v n/a n/a 220.5 n/a 1490 146 10.7 24.0 43.5 61.8 75.4 85.4 91.2 94.7 96.6 97.7 98.8 99.4 99.6 99.9 99.9 100.0 

13:02 v1 2DI 2.29 n/a 14.0 0.425 1450 132 15.8 33.1 56.1 74.9 87.3 94.4 97.2 98.9 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:03 v2 2DI 3.51 n/a 20.3 0.692 1500 108 13.3 29.4 51.4 70.4 83.5 92.1 96.6 99.0 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:07 v3 2DI 3.96 n/a 20.3 1.357 1490 121 12.4 27.4 48.5 66.9 79.7 88.4 93.1 96.0 97.5 98.5 99.5 99.9 100.0 100.0 100.0 100.0 13:10 v4 2DI 4.42 n/a 27.0 1.156 1480 155 11.4 24.5 42.8 59.6 72.4 82.4 88.6 92.8 95.5 97.1 98.3 99.0 99.3 99.7 99.9 100.0 13:12 v5 2DI 4.88 n/a 30.0 1.241 1580 177 9.9 22.8 42.4 61.3 75.5 85.6 91.3 95.0 96.7 97.6 99.3 99.9 100.0 100.0 100.0 100.0 13:15 v6 2DI 4.72 n/a 28.4 1.302 1470 180 9.1 21.0 39.3 57.3 71.5 82.7 89.3 93.5 95.9 97.3 98.4 99.1 99.3 99.7 99.9 100.0 13:18 v7 2DI 4.72 n/a 28.9 1.419

8

1470 108 11.5 25.8 46.3 64.6 77.6 86.9 91.8 94.9 96.5 97.6 98.6 99.5 99.8 99.9 100.0 100.0 

13:21 v8 2DI 4.88 n/a 29.0 1.076 1450 162 9.9 22.7 42.0 60.3 74.1 84.6 90.5 94.0 95.9 97.0 97.9 98.8 99.3 99.7 99.9 100.0 13:24 v9 2DI 3.81 n/a 22.6 0.533 1480 121 9.0 21.5 41.3 61.2 76.5 87.8 94.3 98.3 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on August 28, 2007; 

verticals 1 through 9 located respectively at stations 90, 112, 133, 156, 176, 200, 219, 244, and 262 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 68 and 284 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation 

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

13:50- 14:10

EWI-5v n/a n/a 149.8 n/a 1120 104 11.7 25.5 44.8 62.2 74.9 84.5 90.2 93.9 96.2 97.6 98.7 99.4 99.7 99.9 100.0 100.0 

13:52-14:08

EWI-3v n/a n/a 95.7 n/a 1180 103 10.5 23.8 43.3 61.5 74.9 85.0 90.9 94.6 96.7 98.0 99.0 99.6 99.8 99.9 100.0 100.0 

13:50-14:10

EWI-9v n/a n/a 266.9 n/a 1150 105 11.5 25.3 44.7 62.2 75.0 84.7 90.4 94.2 96.4 97.7 98.7 99.4 99.7 99.9 100.0 100.0 

13:50 v1 2DI 3.35 n/a 18.9 1.363 1210 88.2 14.3 30.2 50.9 68.7 81.2 89.6 94.1 96.9 98.1 98.6 99.4 99.9 100.0 100.0 100.0 100.0 13:52 v2 2DI 3.35 n/a 18.3 1.581 1210 114 9.9 22.9 42.3 60.7 74.7 85.2 91.4 95.3 97.6 98.8 99.7 99.9 100.0 100.0 100.0 100.0 13:54 v3 2DI 4.27 n/a 25.2 1.542 1190 98.5 13.3 28.6 49.4 67.2 79.6 88.5 93.4 96.3 97.7 98.4 99.5 99.9 100.0 100.0 100.0 100.0 13:56 v4 2DI 4.88 n/a 31.7 1.420 1170 96.1 12.2 27.0 47.2 64.8 77.1 86.0 91.3 94.7 96.6 97.7 98.5 99.2 99.5 99.8 99.9 100.0 13:59 v5 2DI 6.86 n/a 42.1 1.264 1180 99.1 10.3 23.5 42.9 60.8 74.2 84.2 90.3 94.2 96.6 98.0 99.0 99.8 99.9 100.0 100.0 100.0 14:01 v6 2DI 5.18 n/a 31.8 1.453 1160 117 11.3 24.8 43.6 60.5 73.2 83.1 89.4 93.6 96.1 97.6 98.7 99.6 99.9 100.0 100.0 100.0 14:05 v7 2DI 6.86 n/a 42.2 1.209 978 136 10.9 23.3 40.7 57.0 69.7 79.9 86.6 91.3 94.4 96.4 97.7 98.7 99.3 99.7 99.9 100.0 14:08 v8 2DI 5.79 n/a 35.3 1.130 1170 101 11.2 25.1 44.9 62.9 76.1 85.8 91.2 94.4 96.2 97.3 98.3 99.0 99.3 99.7 99.9 100.0 14:10 v9 2DI 3.66 n/a 21.4 0.798 1080 60.9 13.3 29.6 51.4 70.3 83.2 90.6 93.4 95.1 96.6 98.2 99.6 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on August 28, 2007; 

verticals 1 through 9 located respectively at stations 103, 136, 169, 202, 235, 268, 301, 334, and 367 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 70 and 400 ft from the left-ban

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm 

% 

< 

14:18-14:42

EWI-5v n/a n/a 92.9 n/a 1130 128 10.1 22.4 40.3 57.3 70.8 81.6 88.4 93.1 95.9 97.4 98.5 99.3 99.6 99.8 100.0 100.0 

14:20-14:39

EWI-3v n/a n/a 53.0 n/a 1110 127 10.2 22.5 40.3 57.4 70.9 81.6 88.5 93.1 95.8 97.2 98.3 99.1 99.4 99.8 99.9 100.0 

14:18-14:42

EWI-9v n/a n/a 163.8 n/a 1100 126 10.3 22.7 40.8 58.0 71.4 82.1 88.9 93.5 96.0 97.4 98.6 99.3 99.7 99.9 100.0 100.0 

14:42 v1 2DI 4.72 n/a 28.2 1.464 1130 115 9.8 22.1 40.6 58.5 72.5 83.6 90.3 94.4 96.7 97.9 98.7 99.3 99.6 99.8 99.9 100.0 14:39 v2 2DI 3.35 n/a 19.4 1.510 1070 158 9.8 21.6 38.9 56.1 70.2 81.7 89.0 93.7 96.3 97.5 98.3 99.0 99.3 99.7 99.9 100.0 14:37 v3 2DI 3.20 n/a 17.7 1.468 1100 178 7.8 18.0 33.7 49.8 63.5 75.6 84.4 91.0 94.9 96.9 98.5 99.5 99.9 100.0 100.0 100.0 14:35 v4 2DI 3.20 n/a 18.2 1.429 1060 104 11.1 24.3 43.1 60.3 73.2 83.3 89.6 93.7 95.5 96.6 98.2 99.4 99.9 100.0 100.0 100.0 14:32 v5 2DI 3.20 n/a 18.8 1.378 1140 98.7 10.4 23.1 41.2 57.8 70.3 80.0 86.2 90.8 94.1 96.2 97.6 98.5 99.1 99.6 99.9 100.0 14:26 v6 2DI 3.20 n/a 18.5 1.364 1010 105 11.1 24.4 43.4 61.1 74.2 84.0 90.1 94.3 96.8 98.3 99.5 99.9 100.0 100.0 100.0 100.0 14:23 v7 2DI 2.90 n/a 16.3 1.232 1130 121 12.6 25.7 43.3 59.3 71.8 81.8 88.1 92.5 95.1 96.7 98.1 99.0 99.4 99.7 99.9 100.0 14:20 v8 2DI 2.59 n/a 14.8 1.145 1120 116 10.7 23.6 42.3 59.9 73.3 83.6 90.2 94.6 96.6 97.8 99.3 99.9 100.0 100.0 100.0 100.0 14:18 v9 2DI 2.13 n/a 11.9 0.986 1200 141 13.1 29.3 51.7 71.4 85.2 94.4 98.3 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 28, 2007; 

verticals 1 through 9 located respectively at stations 114, 148, 182, 216, 250, 284, 318, 352, and 386 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 80 and 420 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time 

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:56-15:32

EWI-5v n/a n/a 232.6 n/a 1020 139 10.6 23.6 42.7 60.6 74.2 84.4 90.4 94.3. 96.5 97.8 98.6 99.2 99.5 99.8 99.9 100.0 

15:01-15:28

EWI-3v n/a n/a 155.6 n/a 1030 152 9.2 21.0 39.0 56.5 70.3 81.2 87.8 92.4 95.2 97.0 98.4 99.2 99.5 99.8 99.9 100.0 

14:56- 15:32

EWI-9v n/a n/a 437.1 n/a 1020 141 10.4 23.2 42.1 59.9 73.4 83.5 89.5 93.4 95.7 97.1 98.3 99.0 99.4 99.8 99.9 100.0 

14:56 v1 2DI 2.13 n/a 23.8 0.304 1070 155 12.1 27.3 49.1 68.7 82.1 90.8 95.8 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:01 v2 2DI 3.05 n/a 39.2 0.449 1050 101 11.9 26.2 46.0 63.4 75.6 84.1 88.9 92.2 94.1 95.5 97.5 98.7 99.2 99.7 99.9 100.0 15:04 v3 2DI 3.81 n/a 46.9 0.597 1050 99.6 14.5 30.7 52.3 70.6 83.1 91.8 96.4 99.0 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 15:08 v4 2DI 4.27 n/a 51.4 0.647 1040 125 9.4 21.5 39.6 56.6 69.4 79.3 85.7 90.2 93.2 95.3 97.1 98.6 99.3 99.7 99.9 100.0 15:12 v5 2DI 4.72 n/a 59.6 0.664 1030 170 8.1 18.6 35.2 52.0 65.9 77.6 85.2 90.7 94.5 96.8 98.2 99.0 99.4 99.7 99.9 100.0 15:18 v6 2DI 4.57 n/a 57.1 0.602 1010 170 10.1 22.3 40.6 58.1 71.6 81.9 88.2 92.4 94.8 96.4 97.6 98.6 99.1 99.6 99.9 100.0 15:22 v7 2DI 4.57 n/a 56.0 0.650 983 134 11.2 24.7 44.3 62.5 75.9 85.6 90.8 93.9 95.6 96.9 97.8 98.6 99.1 99.7 99.9 100.0 15:27 v8 2DI 4.72 n/a 56.8 0.368 1020 160 10.1 23.1 42.9 62.0 76.3 86.8 92.6 95.9 97.3 98.2 99.2 99.9 100.0 100.0 100.0 100.0 15:31 v9 2DI 3.66 n/a 46.3 0.225 950 132 11.5 26.5 49.0 69.7 84.1 93.3 97.5 99.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on August 28, 2007; 

verticals 1 through 9 located respectively at stations 90, 112, 133, 156, 176, 200, 219, 244, and 262 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 68 and 284 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:51-16:24

EWI-5v n/a n/a 277.4 n/a 799 110 9.2 20.6 37.9 55.0 68.8 80.0 87.3 92.4 95.4 97.1 98.3 99.2 99.5 99.8 99.9 100.0 

15:55-16:21

EWI-3v n/a n/a 185.5 n/a 803 109 10.3 22.6 40.5 57.7 71.1 81.9 88.9 93.6 96.3 97.8 99.0 99.7 99.9 100.0 100.0 100.0 

15:51-16:24

EWI-9v n/a n/a 524.1 n/a 794 114 9.9 21.9 39.4 56.3 69.8 80.8 87.9 92.8 95.7 97.3 98.5 99.3 99.6 99.9 100.0 100.0 

15:51 v1 2DI 2.90 n/a 33.9 0.763 817 113 8.9 21.1 40.2 59.1 73.8 85.1 91.5 95.5 97.5 98.4 99.4 99.9 100.0 100.0 100.0 100.0 15:55 v2 2DI 2.90 n/a 33.7 0.837 819 115 10.4 22.9 41.1 58.3 71.5 81.7 88.1 92.5 95.3 97.1 98.8 99.7 100.0 100.0 100.0 100.0 15:57 v3 2DI 3.81 n/a 46.5 0.881 832 97.1 9.4 20.9 37.8 54.2 67.3 78.1 85.4 90.8 94.2 96.3 97.8 99.0 99.5 99.8 99.9 100.0 16:00 v4 2DI 5.03 n/a 65.5 0.648 782 121 11.2 24.1 42.3 59.0 71.9 82.3 89.1 93.9 96.9 98.5 99.4 99.9 100.0 100.0 100.0 100.0 16:05 v5 2DI 6.40 n/a 84.5 0.723 809 117 9.9 21.6 38.9 55.8 69.3 80.6 88.0 93.2 96.4 98.0 99.0 99.7 99.8 100.0 100.0 100.0 16:09 v6 2DI 6.40 n/a 80.2 0.719 779 135 10.5 22.3 39.2 55.4 68.5 79.5 86.9 92.1 95.3 97.0 98.1 99.0 99.4 99.7 99.9 100.0 16:14 v7 2DI 6.40 n/a 81.1 0.708 768 121 7.8 18.0 34.3 51.2 65.5 77.5 85.4 90.9 94.2 96.0 97.4 98.4 99.1 99.6 99.9 100.0 16:20 v8 2DI 5.33 n/a 67.3 0.535 781 91.4 10.9 24.3 43.5 61.3 74.7 85.0 91.4 95.4 97.2 98.0 99.2 99.9 100.0 100.0 100.0 100.0 16:23 v9 2DI 2.29 n/a 31.4 0.429 749 66.7 14.6 30.7 51.5 68.8 80.4 87.7 91.4 93.9 95.3 96.8 99.2 99.8 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on August 28, 2007; 

verticals 1 through 9 located respectively at stations 103, 136, 169, 202, 235, 268, 301, 334, and 367 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 70 and 400 ft from the left-ban

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

16:32- 16:56

EWI-5v n/a n/a 182.4 n/a 759 115 11.7 25.4 44.6 62.6 76.2 86.4 92.3 96.0 97.9 98.8 99.5 99.9 100.0 100.0 100.0 100.0 

16:35-16:54

EWI-3v n/a n/a 101.4 n/a 761 101 11.7 25.4 44.4 61.8 74.9 84.9 90.8 94.9 97.3 98.4 99.4 99.9 100.0 100.0 100.0 100.0 

16:32- 16:56

EWI-9v n/a n/a 320.7 n/a 756 112 11.4 24.7 43.6 61.3 74.8 85.0 91.1 95.1 97.2 98.3 99.3 99.8 99.9 100.0 100.0 100.0 

16:32 v1 2DI 4.57 n/a 55.6 0.720 803 138 12.0 25.4 44.6 62.9 76.7 87.1 92.9 96.4 98.1 99.0 99.6 99.9 100.0 100.0 100.0 100.0 16:35 v2 2DI 3.20 n/a 38.8 0.715 770 110 10.3 22.8 40.7 57.6 70.9 81.6 88.5 93.5 96.5 98.1 99.2 99.8 100.0 100.0 100.0 100.0 16:39 v3 2DI 3.05 n/a 36.8 0.754 750 117 10.4 22.9 41.0 58.3 71.8 82.7 89.5 94.0 96.5 97.9 99.1 99.8 100.0 100.0 100.0 100.0 16:42 v4 2DI 3.05 n/a 36.5 0.734 739 97.0 11.3 24.6 43.0 59.8 72.6 82.4 88.3 92.1 94.3 96.0 97.8 99.1 99.5 99.8 99.9 100.0 16:44 v5 2DI 3.05 n/a 35.7 0.643 756 100 11.5 25.4 44.6 62.0 75.1 85.0 91.0 95.0 97.1 98.1 99.3 99.9 100.0 100.0 100.0 100.0 16:47 v6 2DI 3.05 n/a 36.1 0.508 753 138 9.1 20.5 37.9 55.2 69.4 80.9 88.3 93.4 96.4 98.1 99.4 99.9 100.0 100.0 100.0 100.0 16:51 v7 2DI 2.74 n/a 30.9 0.469 696 109 12.9 27.8 48.6 67.5 81.1 90.9 96.3 99.1 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:54 v8 2DI 2.44 n/a 26.9 0.492 748 86.7 15.8 32.4 53.8 72.2 85.3 93.3 96.6 98.6 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 16:56 v9 2DI 1.98 n/a 23.4 0.479 709 64.6 14.5 30.7 52.3 71.0 83.8 91.8 96.1 98.8 99.9 100.0 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on August 29, 2007; 

verticals 1 through 9 located respectively at stations 103, 136, 169, 202, 235, 268, 301, 334, and 367 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 70 and 400 ft from the left-ban

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:04-8:21

EWI-5v n/a n/a 91 n/a 5980 239 9.2 20.7 37.8 54.6 68.1 79.2 86.5 91.8 95.2 97.0 98.1 98.9 99.3 99.7 99.9 100.0 

8:06-8:19

EWI-3v n/a n/a 52 n/a 5890 271 11.5 23.9 41.3 57.6 70.3 80.6 87.5 92.5 95.6 97.2 98.3 99.0 99.5 99.8 99.9 100.0 

8:04-8:21

EWI-9v n/a n/a 162 n/a 5940 252 9.7 21.2 38.0 54.3 67.5 78.4 85.7 91.1 94.5 96.5 97.8 98.8 99.3 99.7 99.9 100.0 

8:04 v1 2DI 4.88 n/a 26 0.907 5930 232 9.4 21.3 39.4 57.3 71.4 82.7 89.5 93.9 96.3 97.5 98.3 99.0 99.3 99.7 99.9 100.0 8:06 v2 2DI 3.51 n/a 18 1.037 5820 286 14.1 27.0 44.0 59.3 70.8 79.9 86.1 90.5 93.3 95.2 96.8 98.1 99.0 99.6 99.9 100.0 8:08 v3 2DI 3.35 n/a 18 0.994 6020 274 9.6 20.7 36.5 51.5 63.7 74.0 81.1 86.5 90.4 93.1 95.1 96.9 98.2 99.3 99.8 100.0 8:12 v4 2DI 3.35 n/a 19 0.903 5890 285 7.6 17.6 33.3 49.3 62.9 74.8 83.1 89.5 93.8 96.4 97.8 98.9 99.5 99.8 99.9 100.0 8:13 v5 2DI 3.35 n/a 18 0.880 5990 224 9.6 22.1 40.5 58.2 72.1 83.2 90.4 95.5 98.7 99.7 99.9 100.0 100.0 100.0 100.0 100.0 8:15 v6 2DI 3.35 n/a 18 0.834 5970 200 9.4 21.1 38.0 53.9 66.5 76.9 84.0 89.3 92.9 95.2 97.1 98.3 98.9 99.5 99.8 100.0 8:17 v7 2DI 3.05 n/a 17 0.847 5930 245 7.3 17.2 32.6 48.6 62.6 75.0 84.0 90.9 95.6 98.0 99.3 99.9 100.0 100.0 100.0 100.0 8:18 v8 2DI 2.74 n/a 16 0.351 5890 354 8.3 18.9 35.2 51.9 65.9 77.8 86.0 92.2 96.1 98.1 99.3 99.9 100.0 100.0 100.0 100.0 8:20 v9 4DI 2.29 n/a 24 0.545 6120 194 10.3 23.7 43.2 61.1 74.3 84.3 90.6 95.1 97.8 99.0 99.8 100.0 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on August 29, 2007; 

verticals 1 through 9 located respectively at stations 90, 112, 133, 156, 176, 200, 219, 244, and 262 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 68 and 284 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:26-8:46

EWI-5v n/a n/a 141 n/a 6610 262 10.6 23.3 41.3 57.9 70.4 80.3 86.8 91.5 94.9 97.0 98.3 99.0 99.4 99.7 99.9 100.0 

8:28-8:44

EWI-3v n/a n/a 91 n/a 6620 226 9.3 21.2 39.0 55.9 69.0 79.4 86.1 90.9 94.3 96.4 97.8 98.7 99.1 99.6 99.9 100.0 

8:26-8:46

EWI-9v n/a n/a 287 n/a 6610 255 10.1 22.4 40.1 56.5 69.1 79.2 85.9 90.8 94.4 96.6 98.0 98.9 99.4 99.8 99.9 100.0 

8:26 v1 2DI 3.51 n/a 19 0.770 6370 200 11.5 25.6 45.5 63.8 77.1 86.9 92.4 95.9 97.8 98.8 99.7 99.9 100.0 100.0 100.0 100.0 8:28 v2 2DI 3.51 n/a 19 1.015 6430 187 10.0 23.0 41.9 59.7 73.2 83.4 89.5 93.6 96.1 97.8 99.0 99.7 99.9 99.9 100.0 100.0 8:29 v3 2DI 4.42 n/a 24 0.983 6480 292 10.4 22.3 39.0 54.7 67.0 77.3 84.4 89.9 94.1 96.7 98.3 99.4 99.8 99.9 100.0 100.0 8:32 v4 2DI 5.79 n/a 35 0.819 6570 243 9.5 21.3 38.5 54.7 67.4 77.7 84.8 90.2 94.2 96.7 98.2 99.2 99.7 99.9 100.0 100.0 8:35 v5 2DI 7.01 n/a 39 0.853 6660 249 9.4 21.3 38.6 54.7 67.2 77.2 83.8 88.7 92.6 95.2 96.9 98.0 98.6 99.4 99.8 100.0 8:38 v6 2DI 7.01 n/a 40 0.933 6680 295 10.1 21.8 38.3 53.6 65.4 75.2 82.1 87.6 91.9 94.8 96.7 98.1 99.0 99.6 99.9 100.0 8:41 v7 2DI 7.01 n/a 40 0.880 6750 308 11.2 24.6 43.2 60.0 72.4 82.2 88.5 93.1 96.1 97.9 98.7 99.2 99.4 99.8 99.9 100.0 8:43 v8 2DI 5.94 n/a 33 0.711 6720 225 8.5 19.9 37.8 55.2 69.1 80.3 87.4 92.4 95.6 97.5 98.5 99.1 99.3 99.7 99.9 100.0 8:44 v9 4DI 3.28 n/a 38 0.458 6630 153 11.6 26.1 46.3 64.0 76.5 85.7 91.2 95.1 97.2 98.4 99.5 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-77-bag-type noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 29, 2007; 

verticals 1 through 9 located respectively at stations 114, 148, 182, 216, 250, 284, 318, 352, and 386 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 80 and 420 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

8:56-9:17

EWI-5v n/a n/a 142 n/a 6590 232 9.9 21.8 39.0 55.2 67.9 78.5 85.7 91.1 94.8 96.9 98.2 99.1 99.6 99.8 99.9 100.0 

8:59-9:14

EWI-3v n/a n/a 96 n/a 6640 239 9.3 20.9 38.0 54.3 67.3 78.0 85.4 90.8 94.5 96.5 97.8 98.8 99.3 99.7 99.9 100.0 

8:56-9:17

EWI-9v n/a n/a 269 n/a 6610 243 10.5 22.6 39.9 56.2 69.0 79.5 86.5 91.6 95.0 97.1 98.3 99.2 99.5 99.8 99.9 100.0 

8:56 v1 4DI 2.44 n/a 32 0.330 6230 214 9.8 22.5 41.8 60.6 74.8 85.9 92.9 97.6 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 8:59 v2 2DI 3.66 n/a 25 0.531 6400 190 10.6 23.7 42.5 59.9 72.9 82.7 88.5 92.4 94.7 96.1 97.6 98.5 99.0 99.6 99.8 100.0 9:02 v3 2DI 4.11 n/a 28 0.741 6530 204 10.4 23.1 41.2 58.2 71.5 82.2 89.0 93.7 96.4 98.0 99.1 99.8 100.0 100.0 100.0 100.0 9:04 v4 2DI 4.57 n/a 32 0.460 6520 303 13.4 26.0 42.8 58.0 69.8 79.6 86.2 91.2 95.0 97.3 98.6 99.5 99.7 99.9 100.0 100.0 9:06 v5 2DI 5.03 n/a 36 0.818 6640 247 8.9 19.9 36.2 51.8 64.5 75.5 83.4 89.7 94.0 96.5 97.8 98.8 99.4 99.7 99.9 100.0 9:08 v6 2DI 4.88 n/a 35 0.852 6700 243 10.1 22.4 40.2 57.2 70.6 81.4 88.3 93.0 96.0 97.7 98.8 99.5 99.6 99.8 99.9 100.0 9:11 v7 2DI 4.88 n/a 34 0.803 6670 228 10.5 22.6 39.5 55.1 67.3 77.2 83.9 89.1 93.2 96.0 97.7 98.8 99.4 99.7 99.9 100.0 9:13 v8 2DI 5.03 n/a 35 0.573 6810 259 9.2 20.9 38.3 55.1 68.4 79.3 86.6 91.7 95.0 96.8 98.0 98.8 99.4 99.7 99.9 100.0 9:16 v9 4DI 3.96 n/a 55 0.304 6570 274 10.6 23.0 40.8 57.4 70.4 81.0 88.1 93.1 95.9 97.3 98.4 99.3 99.7 99.9 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section B on August 29, 2007; 

verticals 1 through 9 located respectively at stations 103, 136, 169, 202, 235, 268, 301, 334, and 367 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 70 and 400 ft from the left-ban

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:41-9:59

EWI-5v n/a n/a 118 n/a 8040 265 11.7 24.5 42.0 58.0 70.6 80.9 87.8 92.7 95.7 97.3 98.4 99.1 99.5 99.8 99.9 100.0 

9:43-9:57

EWI-3v n/a n/a 65 n/a 8120 231 14.0 28.4 46.9 62.8 74.4 83.5 89.2 93.2 95.8 97.2 98.3 99.0 99.4 99.8 99.9 100.0 

9:41- 9:59

EWI-9v n/a n/a 205 n/a 8030 244 12.6 26.0 43.9 59.9 72.0 81.9 88.4 93.0 95.8 97.4 98.4 99.2 99.5 99.8 99.9 100.0 

9:41 v1 2DI 4.88 n/a 37 1.471 7760 298 11.2 23.4 40.7 57.1 70.3 81.5 88.8 93.8 96.4 97.6 98.4 99.1 99.4 99.8 99.9 100.0 9:43 v2 2DI 3.51 n/a 24 1.421 7900 231 15.5 30.9 50.3 66.3 77.7 86.2 91.4 94.9 96.9 98.0 98.8 99.5 99.6 99.8 99.9 100.0 9:46 v3 2DI 3.35 n/a 22 1.494 8030 324 9.8 21.0 37.0 52.6 65.4 76.5 84.4 90.5 94.6 97.1 98.4 99.2 99.5 99.8 99.9 100.0 9:47 v4 2DI 3.35 n/a 22 1.359 8010 237 12.7 26.2 44.0 59.6 71.2 80.3 86.5 91.0 94.0 96.1 97.7 98.9 99.5 99.8 99.9 100.0 9:50 v5 2DI 3.35 n/a 23 1.568 8170 235 13.9 28.1 46.5 62.6 74.5 83.5 89.0 92.7 95.2 96.7 97.9 98.6 99.2 99.7 99.9 100.0 9:52 v6 2DI 3.35 n/a 23 1.307 7910 168 16.0 32.2 52.4 68.8 80.0 88.1 93.2 96.6 98.5 99.3 99.8 100.0 100.0 100.0 100.0 100.0 9:54 v7 2DI 2.74 n/a 21 1.316 8260 202 13.0 27.2 45.6 61.1 72.5 81.8 88.2 92.9 96.0 97.7 98.9 99.8 99.9 100.0 100.0 100.0 9:56 v8 2DI 2.44 n/a 18 1.257 8360 222 11.9 25.0 42.4 57.6 69.2 79.1 86.2 91.6 95.1 96.8 98.1 99.0 99.5 99.8 99.9 100.0 9:58 v9 4DI 2.29 n/a 29 0.948 8410 202 13.1 27.9 47.6 64.4 76.2 85.1 90.6 94.4 96.6 97.7 98.5 99.4 99.8 99.9 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section A on August 29, 2007; 

verticals 1 through 9 located respectively at stations 90, 112, 133, 156, 176, 200, 219, 244, and 262 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 68 and 284 ft from the left-bank 

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection 

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm 

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:03-10:23

EWI-5v n/a n/a 181 n/a 9380 237 14.1 28.6 47.3 63.2 74.6 83.3 88.7 92.6 95.3 97.1 98.3 99.1 99.5 99.8 99.9 100.0 

10:05-10:20

EWI-3v n/a n/a 115 n/a 10200 209 14.0 29.1 48.6 64.9 76.3 84.7 89.8 93.5 95.9 97.5 98.6 99.4 99.7 99.9 100.0 100.0 

10:03-10:23

EWI-9v n/a n/a 338 n/a 9710 227 13.7 28.1 46.9 62.7 74.1 82.6 88.0 92.0 94.9 96.8 98.2 99.1 99.5 99.8 99.9 100.0 

10:03 v1 2DI 3.51 n/a 24 1.398 9180 210 14.8 30.8 51.4 68.5 80.2 88.5 93.0 95.7 97.4 98.3 98.9 99.2 99.4 99.8 99.9 100.0 10:05 v2 2DI 3.51 n/a 24 1.630 9200 190 12.6 27.7 48.3 65.9 77.9 86.5 91.4 94.7 96.8 98.0 98.9 99.5 99.7 99.9 100.0 100.0 10:07 v3 2DI 4.42 n/a 31 1.499 9440 233 13.0 27.4 46.3 62.5 74.2 82.8 88.3 92.1 94.8 96.7 98.0 99.0 99.5 99.8 99.9 100.0 10:09 v4 2DI 5.94 n/a 42 1.327 9500 250 12.8 26.9 45.4 61.6 73.5 82.5 88.2 92.4 95.2 97.1 98.3 99.0 99.3 99.7 99.9 100.0 10:12 v5 2DI 7.01 n/a 49 1.335 9530 251 13.2 27.3 45.9 61.9 73.4 82.3 87.8 92.0 95.0 97.0 98.4 99.3 99.7 99.9 100.0 100.0 10:14 v6 2DI 7.01 n/a 49 1.435 9700 240 11.9 25.0 42.4 57.2 67.9 76.3 82.1 87.0 91.4 94.9 97.1 98.6 99.2 99.7 99.9 100.0 10:17 v7 2DI 7.01 n/a 50 1.241 9200 254 15.3 29.3 46.6 61.4 72.3 81.1 87.0 91.4 94.6 96.5 97.8 98.7 99.3 99.7 99.9 100.0 10:19 v8 2DI 5.94 n/a 42 1.119 11900 166 17.2 34.1 54.6 70.5 80.9 88.2 92.5 95.3 96.9 98.0 98.8 99.5 99.7 99.9 100.0 100.0 10:22 v9 2DI 3.81 n/a 27 0.565 9760 171 15.0 32.0 53.9 71.7 83.2 90.7 94.7 97.2 98.4 98.9 99.7 99.9 100.0 100.0 100.0 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.

D-96-A1 noncomposited multivertical suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 29, 2007; 

verticals 1 through 9 located respectively at stations 114, 148, 182, 216, 250, 284, 318, 352, and 386 ft from the left-bank end point of the tagline, left and right edges of water are respectively at 80 and 420 ft from the left-bank 

left-bank end point of tagline is approximately 30 ft farther from the river than the end point used in February 2007

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:31-10:52

EWI-5v n/a n/a 141 n/a 9640 208 14.0 28.8 48.0 64.2 75.7 84.1 89.2 92.7 95.2 96.9 98.1 98.9 99.3 99.7 99.9 100.0 

10:33- 10:48

EWI-3v n/a n/a 61 n/a 9500 210 12.5 26.6 45.5 62.1 74.1 83.3 89.1 93.1 95.6 97.2 98.4 99.2 99.6 99.8 99.9 100.0 

10:31-10:52

EWI-9v n/a n/a 268 n/a 9630 214 14.1 28.7 47.4 63.2 74.5 83.0 88.3 92.2 94.9 96.8 98.1 98.9 99.4 99.7 99.9 100.0 

10:31 v1 4DI 2.44 n/a 32 0.418 8750 153 13.8 30.7 53.7 73.4 86.3 94.2 97.9 99.5 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 10:33 v2 2DI 3.66 n/a 25 0.721 9020 203 12.6 27.0 46.6 63.7 75.9 84.9 90.2 93.7 95.9 97.4 98.6 99.3 99.5 99.8 99.9 100.0 10:35 v3 2DI 4.11 n/a 29 1.119 9270 192 15.3 30.4 49.3 65.0 75.9 83.8 88.5 91.7 94.2 96.0 97.2 98.0 98.6 99.4 99.8 100.0 10:38 v4 2DI 4.57 n/a 32 1.287 9460 238 14.8 28.3 45.0 58.8 68.9 76.9 82.4 86.9 90.8 93.9 96.1 97.6 98.5 99.4 99.8 100.0 10:40 v5 2DI 5.03 n/a 35 1.241 9530 208 12.5 26.3 44.6 60.5 72.1 81.1 87.0 91.3 94.2 96.1 97.5 98.6 99.2 99.7 99.9 100.0 10:43 v6 2DI 4.88 n/a 34 1.441 9890 213 15.3 30.5 49.2 64.4 75.2 83.5 89.0 93.2 96.1 97.7 98.7 99.5 99.7 99.9 100.0 100.0 10:45 v7 2DI 4.88 n/a 34 1.250 9780 215 15.2 30.8 50.8 67.2 78.6 86.7 91.3 94.5 96.7 98.2 99.2 99.8 100.0 100.0 100.0 100.0 10:47 v8 2DI 5.03

2

n/a 36 0.943 9740 215 12.5 26.8 46.2 63.2 75.7 85.3 91.2 95.0 97.1 98.5 99.4 99.9 100.0 100.0 100.0 100.0 

10:51 v9 4DI 3.96 n/a 54 0.413 11200 265 12.4 26.2 44.9 61.3 73.3 82.4 87.7 91.4 94.0 96.0 97.4 98.4 99.1 99.6 99.9 100.0 

Notes: EWI-5v = 5-vertical EWI measurement mathematically composited using raw laboratory data from verticals 1, 3, 5, 7, and 9; EWI-3v = 3-vertical quasi-EWI measurement mathematically composited using raw laborat

EWI-9v = 9-vertical quasi-EWI measurement mathematically composited using raw laboratory data from all 9 verticals; DI = depth-integrated (nozzle open during downward and upward transits); v1 through v9 refer to verticals 1 thrindicates the number of transits at each vertical.
Single-vertical D-96-A1 suspended-sediment samples collected at Lower Marble Canyon gaging station cross section C on August 30, 2007; vertical located at the station 230 ft from the former right-bank end point o

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

6:26 DI 4.97 n/a 34.26 1.372 1,570 265 14.2 30.8 52.2 69.4 80.6 88.1 92.4 95.1 96.9 97.9 98.8 99.3 99.5 99.8 99.9 100.0 6:29 DI 4.97 n/a 33.79 1.353 1,490 186 11.4 25.4 45.0 62.4 75.1 84.6 90.4 94.3 96.7 98.3 99.2 99.8 100.0 100.0 100.0 100.0 6:32 DI 4.97 n/a 34.97 1.366 1,550 291 13.8 29.5 49.7 66.2 77.3 85.4 90.2 93.7 96.1 97.5 98.6 99.2 99.4 99.8 99.9 100.0 6:35 DI 4.97 n/a 33.30 1.459 1,560 300 14.8 31.3 52.3 69.0 79.9 87.3 91.6 94.4 96.4 97.7 98.6 99.2 99.4 99.8 99.9 100.0 6:38 DI 4.97 n/a 33.50 1.499 1,540 281 14.4 30.9 52.1 69.0 80.1 87.7 92.0 94.8 96.8 98.0 98.8 99.4 99.6 99.8 99.9 100.0 6:41 DI 4.97 n/a 33.79 1.513 1,500 236 15.5 32.5 53.9 70.6 81.3 88.4 92.1 94.7 96.6 97.8 98.7 99.3 99.5 99.8 99.9 100.0 6:44 DI 4.97 n/a 33.99 1.360 1,530 304 13.8 29.6 50.0 66.8 78.1 86.1 90.7 93.9 96.2 97.7 98.8 99.4 99.6 99.8 99.9 100.0 6:47 DI 4.97 n/a 34.87 1.245 1,520 310 12.6 27.7 47.9 65.0 76.6 85.1 90.3 94.0 96.4 97.9 98.7 99.3 99.5 99.8 99.9 100.0 6:50 DI 4.97 n/a 34.58 1.371 1,490 296 15.2 31.5 52.0 68.4 79.1 86.5 90.8 93.9 96.0 97.3 98.5 99.1 99.4 99.8 99.9 100.0 6:53 DI 4.97 n/a 34.97 1.380 1,490 211 16.7 34.6 56.2 72.6 82.7 89.4 93.1 95.5 97.0 98.0 98.7 99.3 99.5 99.8 99.9 100.0 6:56 DI 4.97 n/a 33.30 1.406 1,510 279 14.2 30.5 51.3 67.9 78.9 86.4 90.9 93.9 95.8 97.2 98.3 99.0 99.4 99.8 99.9 100.0 6:59 DI 4.97 n/a 34.09 1.471 1,520 266 15.0 31.6 52.7 69.3 80.0 87.4 91.5 94.4 96.3 97.5 98.5 99.1 99.3 99.7 99.9 100.0 7:02 DI 4.97 n/a 34.09 1.341 1,480 423 15.2 31.5 51.7 67.5 77.9 85.3 89.9 93.3 95.7 97.1 98.2 98.8 99.2 99.7 99.9 100.0 7:05 DI 4.97 n/a 33.60 1.389 1,490 276 14.2 30.2 50.6 66.9 77.6 85.5 90.2 93.7 96.0 97.4 98.5 99.2 99.5 99.8 99.9 100.0 7:08 DI 4.97 n/a 33.40 1.382 1,470 303 14.2 30.6 51.7 68.8 80.0 87.8 92.3 95.3 97.0 98.1 98.9 99.5 99.6 99.8 99.9 100.0 

Notes: DI = depth-integrated (nozzle open during downward and upward transits).
Data collected at the Grand Canyon gaging station P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 27, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:01 Up DI 6.81 n/a 6.85 2.985 1,140 2,480 11.5 24.9 40.0 52.9 66.4 76.7 83.9 90.7 96.0 97.3 98.5 100.0 100.0 100.0 100.0 100.0 110:11 Up DI 6.81 n/a 6.66 2.877 1,200 3,110 8.4 19.7 32.0 46.2 59.3 70.7 80.6 88.1 94.2 97.6 99.2 99.6 100.0 100.0 100.0 100.0 112:44 Up DI 6.35 n/a 6.37 2.997 875 2,700 7.7 17.6 29.2 41.8 55.0 66.4 77.0 87.1 95.5 97.7 99.0 99.7 100.0 100.0 100.0 100.0 112:49 Up DI 6.66 n/a 6.44 2.819 868 2,610 7.2 17.0 29.4 42.2 54.5 67.0 77.7 86.1 92.4 96.9 98.8 99.7 100.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 27, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:57 Up DI 6.76 n/a 6.34 2.769 860 3,530 5.1 13.0 23.1 34.5 47.0 59.2 70.0 79.7 88.7 95.4 98.7 99.5 100.0 100.0 100.0 100.0 113:02 Up DI 6.76 n/a 6.22 2.476 857 3,780 5.3 13.0 21.8 32.2 43.4 54.8 66.9 77.5 85.4 93.9 98.0 99.5 100.0 100.0 100.0 100.0 115:07 Up DI 7.36 n/a 6.87 2.772 658 2,340 7.0 16.1 28.0 39.2 51.3 62.4 72.1 81.9 91.9 97.6 99.2 99.6 100.0 100.0 100.0 100.0 115:10 Up DI 7.21 n/a 6.28 2.551 674 2,690 5.3 13.3 23.3 35.3 46.7 59.2 71.1 82.1 90.6 96.4 99.2 99.7 100.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 28, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:19 Up DI 8.00 n/a 7.60 2.535 335 2,760 2.9 7.9 15.0 23.6 33.9 46.6 59.0 70.7 83.0 92.5 97.0 99.1 99.5 100.0 100.0 100.0 110:25 Point 7.80 0.00 12.00 0.516 471 14,200 1.0 2.0 4.0 7.7 12.5 19.9 29.8 42.7 58.3 73.9 88.9 97.8 100.0 100.0 100.0 100.0 110:29 Point 7.80 0.00 30.00 0.446 585 19,900 0.3 1.7 3.5 6.3 11.1 18.3 29.7 43.1 57.3 72.4 85.1 94.8 98.7 98.8 98.8 100.0 110:41 Point 7.80 0.34 12.00 1.789 339 5,140 1.9 5.1 10.1 17.2 25.9 37.4 50.1 63.7 76.1 87.5 94.9 99.0 99.2 99.2 99.2 100.0 110:46 Point 7.80 0.70 10.00 2.342 361 2,730 3.2 8.6 16.4 26.1 37.1 49.6 61.5 73.4 82.5 92.0 97.1 98.9 98.9 99.2 100.0 100.0 110:49 Point 7.80 0.70 8.00 2.469 363 2,080 3.8 9.8 17.6 27.9 39.4 51.4 62.3 72.4 83.5 90.6 97.5 99.0 100.0 100.0 100.0 100.0 110:53 Point 7.80 0.70 8.00 2.488 338 2,080 4.6 10.2 19.6 29.9 41.5 54.3 65.9 77.6 87.4 94.4 98.0 99.1 100.0 100.0 100.0 100.0 110:57 Point 7.80 1.41 6.00 2.234 360 2,480 3.1 8.4 16.1 25.9 35.9 46.8 58.2 68.9 80.7 91.2 97.0 98.8 99.5 100.0 100.0 100.0 111:01 Point 7.80 1.41 6.00 2.402 358 1,950 3.8 9.8 18.5 27.4 38.6 50.4 63.1 76.0 86.3 94.3 97.4 98.1 98.5 100.0 100.0 100.0 111:04 Point 7.80 1.41 6.00 2.287 365 2,150 3.7 9.3 18.1 28.0 39.4 51.2 61.3 71.0 85.5 94.7 97.7 98.4 100.0 100.0 100.0 100.0 111:07 Point 7.80 2.67 6.00 2.474 335 2,270 3.3 10.4 18.2 29.6 40.2 52.2 63.8 73.8 87.1 94.3 97.6 98.7 100.0 100.0 100.0 100.0 111:10 Point 7.80 2.67 6.00 2.280 370 2,130 3.6 9.5 17.4 28.1 39.5 51.8 62.6 73.3 82.7 92.4 97.6 98.8 100.0 100.0 100.0 100.0 111:13 Point 7.80 2.67 6.00 2.516 376 1,910 3.5 9.6 18.9 30.2 42.3 53.6 65.5 79.3 91.6 95.9 97.8 98.6 100.0 100.0 100.0 100.0 111:17 Point 7.80 4.73 5.00 2.369 356 1,490 3.2 12.1 21.9 33.7 43.6 56.4 68.4 81.0 89.8 95.1 97.4 98.6 100.0 100.0 100.0 100.0 111:20 Point 7.80 4.73 5.00 2.644 352 1,420 4.5 13.3 22.3 32.8 44.9 59.5 72.4 85.0 94.0 97.0 99.4 100.0 100.0 100.0 100.0 100.0 111:23 Point 7.80 4.73 5.00 2.589 353 1,570 5.0 12.3 23.7 35.0 45.2 56.5 69.8 86.7 95.0 97.0 98.6 100.0 100.0 100.0 100.0 100.0 111:27 Point 7.80 7.47 5.00 2.572 338 1,530 4.7 12.4 23.8 34.7 46.2 58.5 70.9 86.4 93.5 96.2 97.2 100.0 100.0 100.0 100.0 100.0 111:29 Point 7.80 7.47 5.00 2.741 348 1,560 4.2 12.3 22.6 33.0 42.5 53.9 64.7 75.3 86.9 95.6 97.0 99.8 100.0 100.0 100.0 100.0 111:31 Point 7.80 7.47 5.00 2.587 348 1,460 5.2 13.8 24.9 37.3 50.0 63.2 76.6 87.4 95.6 98.0 99.2 100.0 100.0 100.0 100.0 100.0 111:36 Up DI 7.51 n/a 7.03 2.844 337 1,860 4.0 10.5 19.0 29.0 40.1 52.5 64.4 75.3 86.1 95.0 97.8 98.8 99.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sample

relative to the mean bed elevation associated with this mean water depth.
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 28, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:45 Up DI 6.48 n/a 5.75 2.757 402 1,660 5.9 12.5 21.9 32.8 44.1 56.3 68.9 80.0 90.9 96.6 98.5 99.6 100.0 100.0 100.0 100.0 111:52 Point 6.96 0.41 10.00 1.856 609 3,740 0.5 3.6 8.5 15.1 24.4 36.3 52.0 68.0 79.8 91.2 97.5 99.8 100.0 100.0 100.0 100.0 111:56 Point 6.96 0.47 10.00 1.423 650 4,220 0.6 4.1 9.0 15.3 23.7 35.2 49.2 64.4 79.2 91.0 97.4 98.9 99.2 100.0 100.0 100.0 111:58 Point 6.96 0.47 10.00 1.830 325 4,620 2.0 4.9 9.5 15.5 23.7 34.7 47.9 62.8 78.5 91.2 97.9 99.7 100.0 100.0 100.0 100.0 112:01 Point 6.96 1.17 8.00 2.046 352 2,740 3.1 7.8 15.0 23.8 34.3 46.6 59.9 72.9 85.3 93.3 97.6 98.4 98.4 100.0 100.0 100.0 112:11 Point 6.96 1.17 8.00 1.771 370 2,610 3.3 9.5 17.6 26.9 37.9 49.4 61.4 73.1 85.0 94.0 97.3 99.3 99.9 100.0 100.0 100.0 112:14 Point 6.96 1.17 8.00 2.202 347 2,710 3.5 8.3 15.2 24.0 33.2 44.4 56.4 70.1 83.6 95.0 97.8 99.0 100.0 100.0 100.0 100.0 112:33 Point 6.96 1.72 7.00 1.983 395 2,570 3.0 8.0 14.9 24.7 35.5 45.7 57.0 69.1 82.5 93.2 97.5 98.1 99.4 100.0 100.0 100.0 112:36 Point 6.96 1.72 7.00 2.094 353 1,880 4.6 10.9 19.1 30.6 43.4 54.5 66.7 75.8 85.1 92.9 97.5 98.3 99.0 100.0 100.0 100.0 112:38 Point 6.96 1.72 7.00 1.871 357 2,890 2.9 7.7 14.8 24.1 33.9 46.0 58.4 69.8 81.6 92.7 97.5 99.2 99.3 100.0 100.0 100.0 112:17 Point 6.96 2.48 7.00 1.996 384 2,010 4.3 12.1 20.7 30.8 43.1 54.1 66.0 76.1 88.4 95.6 97.8 98.9 100.0 100.0 100.0 100.0 112:19 Point 6.96 2.48 7.00 2.220 384 2,040 4.4 10.7 19.0 29.9 40.0 49.3 60.6 71.9 83.0 92.2 96.7 97.7 98.4 100.0 100.0 100.0 112:22 Point 6.96 2.48 7.00 2.014 356 2,060 4.0 10.4 19.0 29.7 41.6 54.9 66.7 77.9 88.8 95.1 98.4 98.9 100.0 100.0 100.0 100.0 112:24 Point 6.96 4.19 7.00 2.310 365 1,270 4.7 14.2 24.7 38.1 52.3 64.3 77.1 88.8 94.4 98.3 98.8 99.4 100.0 100.0 100.0 100.0 112:29 Point 6.96 4.19 7.00 1.890 347 1,820 4.8 10.8 19.9 31.0 42.8 52.4 64.3 77.6 89.6 95.1 97.8 98.8 100.0 100.0 100.0 100.0 112:31 Point 6.96 4.19 7.00 2.106 354 1,870 4.6 11.8 20.8 32.5 45.0 57.1 66.7 77.5 87.3 94.6 97.0 98.8 100.0 100.0 100.0 100.0 112:42 Point 6.96 6.63 7.00 2.293 312 1,040 5.7 18.6 32.4 46.4 60.9 74.8 89.2 94.4 97.6 98.5 99.1 100.0 100.0 100.0 100.0 100.0 112:45 Point 6.96 6.63 7.00 2.406 338 1,040 4.7 16.6 30.1 45.0 57.2 69.7 83.8 92.8 95.5 96.2 98.0 98.5 100.0 100.0 100.0 100.0 112:47 Point 6.96 6.63 7.00 2.222 307 875 5.1 17.3 33.0 48.3 61.6 73.5 84.7 93.8 96.5 96.8 97.4 98.0 100.0 100.0 100.0 100.0 112:51 Up DI 7.21 n/a 7.12 2.540 348 1,840 4.0 10.6 19.8 31.4 44.2 55.6 66.7 78.7 90.9 96.9 98.6 99.6 100.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sample

relative to the mean bed elevation associated with this mean water depth.

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 29, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:07 Up DI 7.82 n/a 6.56 2.525 213 1,600 1.9 4.6 9.5 15.8 24.6 35.0 47.7 64.9 84.2 93.1 97.5 99.4 99.6 100.0 100.0 100.0 115:11 Up DI 8.18 n/a 6.59 2.712 228 1,790 3.3 7.8 14.4 23.5 34.1 45.5 57.4 68.0 78.5 86.9 96.7 99.3 100.0 100.0 100.0 100.0 116:29 Up DI 7.79 n/a 6.37 2.895 223 1,480 3.1 7.2 15.2 23.4 32.8 43.3 56.3 67.0 78.9 89.3 94.8 98.3 98.6 98.8 100.0 100.0 116:32 Up DI 7.48 n/a 6.41 2.862 222 1,450 3.2 7.2 15.1 23.6 34.8 45.2 55.8 66.9 78.3 90.7 96.2 99.8 100.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 29, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

16:38 Up DI 6.76 n/a 5.59 2.828 237 1,570 3.2 8.3 14.7 21.4 30.3 41.0 52.4 65.0 77.8 89.2 97.4 99.6 100.0 100.0 100.0 100.0 116:40 Up DI 6.54 n/a 5.34 2.854 253 1,900 2.3 6.5 12.5 20.1 30.3 41.3 52.7 64.7 76.9 89.4 97.1 98.6 100.0 100.0 100.0 100.0 117:45 Up DI 7.43 n/a 6.10 2.601 213 2,460 2.2 5.5 11.2 19.2 28.2 39.8 53.9 66.5 77.7 87.5 97.2 99.5 100.0 100.0 100.0 100.0 117:47 Up DI 7.58 n/a 5.96 2.468 234 2,220 2.2 6.2 12.2 19.1 28.8 39.4 54.3 67.9 80.1 90.0 97.6 99.0 100.0 100.0 100.0 100.0 1

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 30, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:47 Up DI 7.06 n/a 6.09 2.877 213 2,520 2.2 6.7 12.6 21.7 31.2 42.9 55.2 67.7 79.9 91.7 95.6 98.7 99.5 100.0 100.0 100.0 9:54 Point 7.10 0.09 10.00 1.848 236 5,080 0.4 3.0 7.7 14.1 22.5 33.5 45.0 56.7 67.4 79.4 91.5 98.0 99.0 99.0 100.0 100.0 9:57 Point 7.10 0.25 10.00 2.256 262 3,120 1.2 4.4 10.2 18.4 29.3 41.6 55.8 68.8 78.9 88.5 94.9 98.6 98.8 98.9 99.2 100.0 

10:01 Point 7.10 0.00 10.00 2.272 245 2,790 2.4 6.4 12.5 21.2 32.2 44.2 60.0 73.9 85.3 92.9 98.5 99.3 100.0 100.0 100.0 100.0 10:04 Point 7.10 0.30 8.00 2.231 241 2,470 2.2 7.4 13.8 23.0 33.8 46.9 60.3 71.6 82.3 88.5 96.7 98.6 100.0 100.0 100.0 100.0 10:08 Point 7.10 0.30 8.00 2.072 248 2,220 2.6 7.0 14.5 24.0 35.5 48.5 61.2 72.1 82.9 92.9 97.7 98.4 98.7 99.9 100.0 100.0 10:11 Point 7.10 0.30 8.00 1.942 267 2,800 2.7 6.4 12.3 20.5 29.8 41.6 54.8 68.4 81.3 93.3 97.4 98.4 100.0 100.0 100.0 100.0 10:13 Point 7.10 1.01 7.00 2.276 233 1,840 2.6 7.3 13.9 23.9 34.0 46.1 58.4 71.8 83.9 93.0 97.3 98.5 98.7 100.0 100.0 100.0 10:16 Point 7.10 1.01 7.00 2.790 205 1,400 3.6 9.4 18.2 29.3 41.0 51.0 62.4 74.0 84.1 91.7 95.4 97.6 98.1 99.2 100.0 100.0 10:18 Point 7.10 1.01 7.00 2.412 229 1,880 1.4 7.1 14.8 24.1 34.7 46.5 58.3 68.9 80.5 92.1 96.9 98.4 98.6 99.5 100.0 100.0 10:21 Point 7.10 2.28 7.00 2.615 198 1,360 3.1 8.7 17.6 27.4 37.4 48.1 60.9 72.1 83.3 92.9 97.1 98.1 99.1 100.0 100.0 100.0 10:24 Point 7.10 2.28 7.40 2.443 228 1,810 2.9 7.7 14.6 25.0 35.6 45.8 55.6 66.9 80.8 92.8 96.4 98.8 99.4 100.0 100.0 100.0 10:26 Point 7.10 2.28 7.00 2.524 211 1,330 3.5 9.0 18.0 28.0 40.4 51.3 61.8 73.4 83.4 93.6 97.9 99.2 100.0 100.0 100.0 100.0 12:34 Point 7.10 4.33 7.00 2.516 191 1,240 3.1 9.1 17.1 26.2 36.1 46.7 57.9 69.6 79.6 89.8 95.6 97.7 97.7 98.1 100.0 100.0 12:38 Point 7.10 4.33 7.00 2.498 190 1,220 1.9 7.5 16.4 26.6 36.9 47.8 59.5 72.0 81.9 94.0 97.3 97.9 99.1 100.0 100.0 100.0 12:40 Point 7.10 4.33 7.00 2.459 199 1,060 4.6 10.3 18.4 27.8 40.6 50.5 61.7 70.9 81.6 91.6 95.8 96.6 100.0 100.0 100.0 100.0 12:42 Point 7.10 6.77 7.00 2.387 176 793 5.4 12.8 22.3 34.2 47.8 60.7 74.5 87.6 93.7 97.0 98.7 99.6 100.0 100.0 100.0 100.0 12:45 Point 7.10 6.77 7.00 2.570 173 622 5.4 13.2 23.8 36.6 51.3 67.7 82.1 90.6 95.1 96.9 97.9 100.0 100.0 100.0 100.0 100.0 12:50 Point 7.10 6.77 7.00 2.291 208 1,030 4.3 9.4 17.2 28.6 38.1 47.7 57.2 68.4 80.5 90.5 95.6 96.5 97.1 100.0 100.0 100.0 12:51 Up DI 6.84 n/a 5.81 2.942 204 1,530 2.0 5.7 12.3 19.6 28.9 37.1 49.2 60.0 73.2 86.3 94.1 97.3 98.0 99.8 100.0 100.0 

Notes: DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point samples; p

to the mean bed elevation associated with this mean water depth.

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 30, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:56 Up DI 7.82 n/a 6.22 2.471 175 1,420 3.7 7.7 12.7 20.0 28.3 37.8 47.7 56.7 71.2 86.1 93.5 96.4 99.4 100.0 100.0 100.0 13:09 Point 7.71 0.06 15.00 1.094 212 2,670 1.4 4.6 9.7 16.3 24.6 34.6 47.6 62.2 75.5 86.6 96.6 98.8 100.0 100.0 100.0 100.0 13:13 Point 7.71 0.03 15.00 0.872 247 4,110 1.1 3.5 6.8 11.8 18.7 27.5 39.6 55.8 71.2 85.5 96.2 98.6 99.3 100.0 100.0 100.0 13:15 Point 7.71 0.03 15.00 0.908 241 3,800 1.0 3.2 7.5 12.8 19.9 28.4 39.1 55.4 72.8 87.5 95.8 98.6 99.4 100.0 100.0 100.0 13:21 Point 7.71 0.39 10.00 1.521 218 3,200 1.9 4.3 8.5 14.1 22.2 32.0 44.2 57.0 73.0 90.2 97.4 98.4 98.5 99.0 100.0 100.0 13:23 Point 7.71 0.39 10.00 1.235 216 3,490 1.1 4.0 7.9 13.6 21.2 30.9 45.2 60.8 77.1 90.8 98.3 99.1 100.0 100.0 100.0 100.0 13:27 Point 7.71 0.39 10.00 1.131 229 4,490 1.8 3.9 7.7 12.3 18.7 27.0 37.9 52.3 66.9 82.4 93.6 98.8 99.6 100.0 100.0 100.0 13:30 Point 7.71 1.25 8.00 1.885 221 2,270 1.9 5.3 11.1 18.3 27.1 37.9 50.2 63.1 75.1 86.8 96.6 98.8 99.4 100.0 100.0 100.0 13:32 Point 7.71 1.25 8.00 1.759 225 2,550 1.9 5.6 10.9 18.0 26.4 36.6 48.8 61.7 73.8 88.2 97.0 98.8 100.0 100.0 100.0 100.0 13:34 Point 7.71 1.25 8.00 1.641 200 1,780 2.9 7.8 14.1 20.8 29.7 39.4 48.9 61.1 75.8 90.8 95.9 98.8 100.0 100.0 100.0 100.0 13:37 Point 7.71 2.62 7.00 2.150 208 1,460 2.2 6.4 12.2 19.9 28.3 36.8 46.9 57.7 69.7 82.3 95.2 97.9 100.0 100.0 100.0 100.0 13:39 Point 7.71 2.62 7.00 2.177 226 1,360 3.1 7.6 13.7 23.1 33.1 43.3 54.1 63.4 78.1 89.7 94.9 97.3 100.0 100.0 100.0 100.0 13:41 Point 7.71 2.62 7.00 1.200 263 2,000 2.3 6.6 12.3 19.3 28.3 36.9 46.1 57.1 69.2 79.6 92.7 96.1 98.2 100.0 100.0 100.0 13:43 Point 7.71 4.63 7.00 2.235 203 1,540 3.1 7.1 13.7 20.9 31.1 41.9 52.4 65.7 78.2 89.8 95.7 97.9 97.9 99.5 100.0 100.0 13:47 Point 7.71 4.63 7.00 2.175 208 1,180 3.3 9.1 16.7 26.1 37.2 46.7 57.8 69.4 83.5 92.9 96.8 97.0 100.0 100.0 100.0 100.0 13:50 Point 7.71 4.63 7.00 2.574 201 1,160 3.4 8.8 17.3 27.5 36.4 45.2 55.7 69.0 85.8 93.1 96.9 98.2 100.0 100.0 100.0 100.0 13:52 Point 7.71 7.38 7.00 2.443 181 812 6.9 13.7 24.6 36.4 47.4 59.1 70.9 83.9 92.7 96.2 96.6 96.7 100.0 100.0 100.0 100.0 13:55 Point 7.71 7.38 7.00 2.360 180 1,160 2.6 8.6 16.2 27.3 37.3 47.7 57.8 68.0 80.7 93.2 96.7 98.1 100.0 100.0 100.0 100.0 13:57 Point 7.71 7.38 7.00 2.181 199 882 4.9 10.5 20.9 31.3 43.6 53.6 68.1 82.7 91.0 96.4 97.9 100.0 100.0 100.0 100.0 100.0 14:03 Up DI 7.03 n/a 6.10 2.641 202 1,280 1.7 7.7 14.3 22.1 29.4 38.7 48.0 59.7 69.7 82.2 92.8 96.7 97.3 97.8 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 31, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity 

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

14:11 Up DI 6.81 n/a 5.88 2.810 149 1,040 3.3 8.2 15.3 22.1 32.5 42.7 55.2 67.3 79.4 87.7 94.9 97.2 100.0 100.0 100.0 100.0 14:14 Up DI 6.90 n/a 5.68 3.093 131 1,320 3.2 7.0 13.8 21.1 29.3 39.5 50.4 63.1 76.7 89.4 96.6 97.9 100.0 100.0 100.0 100.0 15:28 Up DI 7.88 n/a 6.50 2.676 162 1,410 2.7 6.2 13.0 19.9 26.5 34.9 44.6 55.6 66.7 78.5 91.6 97.8 100.0 100.0 100.0 100.0 15:31 Up DI 7.85 n/a 6.41 2.602 141 1,230 3.2 6.9 12.6 20.8 28.9 37.5 45.9 56.2 67.9 79.4 90.5 96.8 98.3 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on March 31, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

15:36 Up DI 6.48 n/a 5.40 2.472 166 1,190 3.9 8.2 13.5 21.1 30.4 40.5 49.2 58.5 69.5 84.0 92.1 96.1 99.1 100.0 100.0 100.0 15:39 Up DI 6.54 n/a 5.40 2.546 173 1,190 1.7 6.4 13.0 21.0 28.4 37.0 48.2 59.5 74.1 86.9 93.3 95.9 97.8 100.0 100.0 100.0 16:45 Up DI 6.45 n/a 5.53 2.435 177 1,620 3.1 7.8 12.5 19.6 27.1 34.9 43.9 54.2 65.3 80.2 91.9 96.3 97.7 100.0 100.0 100.0 16:48 Up DI 6.57 n/a 5.28 2.736 193 1,810 2.6 6.6 12.8 19.8 26.9 32.5 42.3 51.9 63.4 79.1 91.8 96.1 98.5 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 1, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:53 Up DI 6.78 n/a 6.22 3.156 123 1,150 3.2 7.4 13.7 21.9 29.7 37.1 46.2 56.7 68.6 79.9 90.5 97.6 98.8 100.0 100.0 100.0 9:56 Up DI 6.45 n/a 5.91 2.772 137 1,720 2.5 6.2 9.9 15.6 23.1 30.5 38.5 46.9 58.2 72.4 87.2 96.5 98.5 100.0 100.0 100.0 

11:32 Up DI 7.36 n/a 6.43 3.007 134 1,080 3.9 9.2 17.3 25.8 34.1 43.5 54.7 68.7 83.7 92.7 96.9 98.8 100.0 100.0 100.0 100.0 11:35 Up DI 7.45 n/a 6.44 2.903 159 957 2.6 5.9 13.3 20.9 30.4 39.9 50.7 64.4 77.4 88.4 93.2 95.1 96.2 99.4 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 1, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand

< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:40 Up DI 8.04 n/a 6.65 2.046 150 1,450 1.8 5.4 11.8 19.9 30.8 42.2 55.7 70.6 83.9 95.1 98.2 99.0 100.0 100.0 100.0 100.0 11:44 Up DI 7.79 n/a 6.56 2.315 160 1,650 1.6 4.9 11.2 17.0 26.4 36.3 47.5 61.6 77.8 92.8 95.8 97.8 100.0 100.0 100.0 100.0 12:59 Up DI 6.63 n/a 5.50 2.742 173 1,400 2.4 7.6 14.2 21.0 28.7 37.4 46.8 57.2 72.6 86.0 93.3 97.2 98.3 100.0 100.0 100.0 13:05 Up DI 6.60 n/a 5.78 2.613 155 1,330 3.1 7.4 12.7 18.6 25.5 34.9 45.1 57.8 71.4 85.5 93.6 96.2 97.2 97.9 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 2, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Point or DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:21 Up DI 6.84 n/a 6.54 2.772 337 2,020 4.6 11.6 20.8 29.8 37.7 44.7 51.4 58.0 66.2 79.5 92.9 97.3 98.5 100.0 100.0 100.0 10:34 Point 7.19 0.43 7.00 1.925 303 3,880 3.1 7.6 12.6 19.2 26.1 33.1 41.0 49.1 60.2 75.0 90.5 97.7 99.5 100.0 100.0 100.0 110:37 Point 7.19 0.40 7.00 2.112 263 2,230 4.1 10.4 19.0 28.9 37.9 44.7 53.6 65.6 77.0 86.0 95.6 98.6 99.5 100.0 100.0 100.0 110:41 Point 7.19 0.24 7.00 1.902 279 3,490 2.9 6.8 11.5 17.4 24.1 29.6 36.3 44.8 55.1 67.2 85.2 95.5 98.2 99.6 100.0 100.0 110:46 Point 7.19 0.70 7.00 2.302 256 1,840 4.7 11.7 20.2 29.7 38.0 46.3 54.0 60.6 69.9 81.3 90.8 96.1 99.0 100.0 100.0 100.0 110:49 Point 7.19 0.70 7.00 2.207 249 1,610 5.3 12.4 23.2 33.9 43.3 52.3 61.0 69.8 76.5 88.0 95.9 98.4 98.8 100.0 100.0 100.0 110:51 Point 7.19 0.70 7.00 2.409 263 1,830 4.3 10.2 18.6 28.0 37.3 44.8 52.2 59.3 67.8 76.8 87.3 93.0 97.3 100.0 100.0 100.0 110:54 Point 7.19 1.41 7.00 2.305 292 1,550 5.2 11.3 20.7 32.5 40.7 49.1 57.0 64.7 74.1 84.6 93.4 97.2 98.1 100.0 100.0 100.0 110:58 Point 7.19 1.41 7.00 2.312 299 1,720 4.4 11.6 19.9 30.2 40.3 48.7 56.5 63.6 70.4 77.1 85.8 96.9 98.3 100.0 100.0 100.0 111:00 Point 7.19 1.41 7.00 2.162 266 1,580 4.8 11.3 20.4 30.5 39.3 47.1 54.4 61.8 70.8 81.4 91.0 96.6 97.5 100.0 100.0 100.0 111:04 Point 7.19 2.06 7.00 2.095 255 1,370 5.3 14.7 25.1 35.1 45.2 53.5 59.9 67.0 78.9 86.9 93.9 98.3 100.0 100.0 100.0 100.0 111:09 Point 7.19 2.06 7.00 2.293 256 1,310 5.2 13.2 23.6 34.1 44.1 51.7 58.1 66.7 76.3 87.1 95.4 96.9 97.9 100.0 100.0 100.0 111:12 Point 7.19 2.06 7.00 2.230 259 2,190 3.5 8.9 15.6 23.0 30.4 36.9 43.0 48.7 56.3 67.1 79.7 93.1 97.5 98.0 100.0 100.0 111:15 Point 7.19 4.42 7.00 2.385 257 1,370 5.5 12.5 23.0 33.8 43.5 52.6 60.5 68.2 78.0 88.5 95.3 97.0 99.2 100.0 100.0 100.0 111:19 Point 7.19 4.42 7.00 2.329 253 1,260 5.7 13.3 24.7 36.1 46.4 54.0 61.6 69.5 79.8 89.4 96.0 97.3 98.7 100.0 100.0 100.0 111:21 Point 7.19 4.42 7.00 2.425 282 1,230 4.9 14.0 24.9 35.7 45.8 53.6 61.4 68.8 75.9 84.0 94.5 95.6 96.3 96.9 99.7 100.0 111:25 Point 7.19 6.86 7.00 1.154 231 644 7.3 17.5 30.2 44.5 61.2 80.9 89.4 93.1 95.2 96.9 97.7 99.7 100.0 100.0 100.0 100.0 111:29 Point 7.19 6.86 7.00 2.216 221 721 7.2 18.2 30.6 44.1 58.9 72.0 83.1 88.6 92.7 96.2 98.0 98.9 100.0 100.0 100.0 100.0 111:33 Point 7.19 6.86 7.00 2.308 212 817 6.1 17.3 30.8 45.1 59.5 71.9 83.3 89.2 93.8 97.2 98.5 100.0 100.0 100.0 100.0 100.0 111:36 Up DI 7.45 n/a 7.72 2.692 215 1,450 4.5 10.6 19.7 30.3 40.2 49.6 59.0 69.7 80.9 89.5 95.9 98.1 99.2 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 2, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm 

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:42 Up DI 6.39 n/a 6.66 2.661 189 1,440 4.9 10.7 19.3 29.1 39.0 47.4 54.6 64.9 74.8 86.8 93.1 97.0 98.6 99.0 100.0 100.0 11:46 Point 6.55 0.30 8.00 2.215 177 2,420 2.2 6.8 12.6 19.9 27.3 35.3 42.8 51.0 61.3 73.2 88.0 95.8 98.2 98.7 100.0 100.0 111:49 Point 6.55 0.39 8.00 2.198 225 2,450 1.7 6.4 11.8 19.7 27.0 33.2 40.3 47.9 56.7 67.0 83.1 94.2 98.3 99.1 100.0 100.0 111:53 Point 6.55 0.06 8.00 1.131 173 11,200 0.2 1.2 2.4 3.5 5.9 8.9 12.9 17.6 26.2 41.7 62.2 82.6 96.2 99.3 100.0 100.0 111:57 Point 6.55 0.76 7.00 1.962 177 843 2.4 7.0 12.6 19.5 26.1 31.9 37.9 46.4 55.0 68.6 82.5 93.5 97.2 98.4 100.0 100.0 112:00 Point 6.55 0.76 7.00 2.191 199 1,860 2.1 8.0 13.7 22.9 32.2 40.4 48.2 57.7 66.9 77.2 92.8 98.2 100.0 100.0 100.0 100.0 112:04 Point 6.55 0.76 7.00 1.909 234 3,100 1.7 5.6 9.2 14.2 21.4 27.3 35.1 43.8 53.7 68.7 86.8 97.7 99.1 100.0 100.0 100.0 112:07 Point 6.55 1.31 7.00 2.126 220 1,740 2.8 7.9 16.3 24.5 34.3 43.0 51.1 59.0 70.0 80.5 91.0 97.4 99.5 100.0 100.0 100.0 112:10 Point 6.55 1.31 7.00 2.084 194 2,170 2.2 6.2 11.1 19.3 26.3 33.6 41.8 50.7 61.0 73.7 85.8 97.3 99.1 100.0 100.0 100.0 112:13 Point 6.55 1.31 7.00 1.718 213 1,640 3.4 7.1 14.9 25.4 34.1 41.4 50.9 61.4 72.4 87.0 94.3 97.9 99.5 100.0 100.0 100.0 112:16 Point 6.55 2.07 7.00 2.146 178 1,710 2.7 8.2 13.5 21.9 29.9 38.7 44.6 51.5 61.6 73.2 86.0 95.9 98.4 100.0 100.0 100.0 112:18 Point 6.55 2.07 7.00 2.197 194 1,300 2.2 8.2 15.4 26.4 37.1 47.7 57.4 66.7 74.0 83.8 90.3 96.4 100.0 100.0 100.0 100.0 112:21 Point 6.55 2.07 7.00 2.165 190 1,770 2.8 7.9 15.6 23.9 31.7 39.2 47.8 57.0 65.0 74.9 88.4 95.2 97.7 98.8 100.0 100.0 112:33 Point 6.55 4.08 7.00 2.247 141 912 6.9 12.6 23.0 34.6 44.6 54.3 65.2 72.8 81.5 87.4 92.3 94.4 96.0 98.6 100.0 100.0 112:36 Point 6.55 4.08 7.00 2.361 182 879 3.6 10.9 20.9 31.4 43.3 52.7 62.4 74.0 82.0 87.9 94.3 97.2 98.7 100.0 100.0 100.0 112:39 Point 6.55 4.08 7.00 2.212 152 1,300 4.4 9.3 18.2 28.6 38.1 46.8 55.3 63.7 76.7 88.7 95.0 97.2 98.0 100.0 100.0 100.0 112:44 Point 6.55 6.22 7.00 2.091 170 696 5.9 13.9 24.3 38.3 51.2 63.7 80.0 85.9 90.4 94.1 97.3 97.5 97.5 100.0 100.0 100.0 112:46 Point 6.55 6.22 7.00 2.287 146 747 3.8 10.0 20.6 31.9 49.0 68.1 81.6 88.0 93.0 96.8 98.1 99.8 100.0 100.0 100.0 100.0 112:49 Point 6.55 6.22 7.00 2.075 152 784 5.3 14.2 25.3 35.3 45.7 56.1 68.9 77.6 82.8 90.4 96.2 98.4 100.0 100.0 100.0 100.0 112:53 Up DI 6.61 n/a 6.32 2.282 168 2,170 2.3 5.3 9.7 16.5 22.8 30.3 38.6 46.1 55.8 70.4 89.0 96.9 97.9 99.4 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 3, 1996; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:00 Up DI 6.49 n/a 9.38 1.827 131 1,070 3.8 10.4 19.6 29.4 41.1 53.2 62.9 74.0 86.4 92.0 98.1 98.8 100.0 100.0 100.0 100.0 12:11 Up DI 6.52 n/a 8.83 2.052 142 1,260 4.1 9.7 17.4 27.2 36.2 44.9 53.5 60.5 66.8 74.1 86.4 93.8 96.2 98.9 100.0 100.0 12:15 Up DI 6.58 n/a 8.50 1.671 167 1,030 3.6 11.1 20.8 29.3 41.4 50.8 64.3 77.0 83.9 90.3 94.1 95.9 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on April 3, 1996; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

12:21 Up DI 6.07 n/a 8.78 1.781 172 1,220 2.5 7.6 16.5 28.2 37.9 48.7 59.8 68.6 80.4 91.5 96.1 98.5 100.0 100.0 100.0 100.0 12:24 Up DI 5.92 n/a 8.22 1.914 154 846 4.0 10.7 21.4 33.9 46.0 55.8 71.0 86.0 89.4 92.7 95.8 98.1 100.0 100.0 100.0 100.0 13:34 Up DI 5.76 n/a 8.30 1.759 161 1,050 3.3 10.0 20.0 32.6 45.1 57.5 71.7 80.5 88.2 93.9 97.4 97.7 99.1 100.0 100.0 100.0 13:38 Up DI 5.76 n/a 8.31 1.696 144 1,130 4.5 10.4 19.3 31.1 41.7 53.2 64.6 76.9 87.9 94.4 97.5 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit).

P-61 suspended-sediment samples collected at the Grand Canyon gaging station on September 26, 1998; vertical located at the station 290 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

10:22 Up DI 6.26 n/a 10.29 1.008 171 133 8.9 20.4 35.4 48.0 58.1 69.8 77.8 79.7 89.9 97.2 100.0 100.0 100.0 100.0 100.0 100.0 10:27 Point 6.36 0.28 20.00 0.805 206 428 6.6 13.4 20.5 29.9 42.8 52.5 68.7 82.6 91.4 95.9 97.8 99.4 100.0 100.0 100.0 100.0 10:30 Point 6.36 0.28 20.00 0.819 216 528 4.0 9.9 16.7 23.1 33.0 46.3 59.5 76.4 89.0 95.2 98.6 100.0 100.0 100.0 100.0 100.0 10:34 Point 6.36 0.28 20.00 0.881 191 430 4.7 9.9 16.8 25.4 35.6 46.6 62.1 78.3 88.1 94.6 99.0 99.7 100.0 100.0 100.0 100.0 10:37 Point 6.36 0.56 15.00 0.985 199 361 7.3 14.8 23.4 33.3 47.3 60.4 75.1 83.7 92.5 98.5 99.3 100.0 100.0 100.0 100.0 100.0 10:40 Point 6.36 0.56 15.00 0.913 196 397 4.6 11.2 18.3 28.1 39.6 56.0 73.3 83.4 92.6 97.6 98.9 99.2 100.0 100.0 100.0 100.0 10:43 Point 6.36 0.56 15.00 0.762 224 390 6.1 14.3 21.2 33.2 45.0 57.9 71.8 83.3 90.8 97.1 99.2 100.0 100.0 100.0 100.0 100.0 10:51 Point 6.36 1.17 12.00 0.997 176 331 5.5 11.5 20.0 30.8 50.0 67.5 79.2 87.3 93.3 98.8 99.9 100.0 100.0 100.0 100.0 100.0 10:57 Point 6.36 1.17 14.00 0.924 198 325 5.9 13.7 22.6 35.2 49.3 63.9 78.3 88.9 94.9 99.1 100.0 100.0 100.0 100.0 100.0 100.0 11:01 Point 6.36 1.17 14.00 0.802 198 385 6.7 13.9 23.1 33.7 45.8 58.4 70.5 84.2 92.8 96.7 99.0 100.0 100.0 100.0 100.0 100.0 11:06 Point 6.36 2.22 12.00 1.214 165 201 5.3 16.5 30.1 44.9 61.3 74.0 83.5 91.1 96.4 98.4 100.0 100.0 100.0 100.0 100.0 100.0 11:08 Point 6.36 2.22 13.00 1.100 169 293 3.3 9.7 17.8 30.6 48.3 68.6 79.7 88.4 93.4 97.5 98.9 99.4 100.0 100.0 100.0 100.0 11:10 Point 6.36 2.22 13.00 0.958 208 291 8.2 16.3 23.9 34.9 49.5 67.9 82.3 90.0 93.4 99.0 100.0 100.0 100.0 100.0 100.0 100.0 11:13 Point 6.36 3.75 13.00 1.285 198 282 9.2 23.9 33.9 49.1 69.4 79.0 90.1 95.5 99.4 99.9 100.0 100.0 100.0 100.0 100.0 100.0 11:16 Point 6.36 3.75 13.00 1.400 161 146 6.4 20.4 40.1 64.6 76.6 84.3 92.7 97.7 99.5 99.8 100.0 100.0 100.0 100.0 100.0 100.0 11:18 Point 6.36 3.73 13.00 1.309 171 155 12.3 27.4 38.6 55.0 68.3 78.5 87.1 91.8 94.2 98.6 100.0 100.0 100.0 100.0 100.0 100.0 11:21 Point 6.36 6.01 10.00 1.320 161 80.5 19.9 46.2 63.5 83.4 87.2 92.8 93.5 97.9 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:24 Point 6.36 6.01 12.00 1.408 163 101 17.1 37.3 57.3 72.7 87.2 92.4 98.7 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:26 Point 6.36 6.01 12.00 1.319 152 50.9 12.3 31.5 56.7 79.8 92.1 94.5 94.5 97.8 99.1 100.0 100.0 100.0 100.0 100.0 100.0 100.0 11:34 Up DI 6.47 n/a 14.43 0.892 176 189 13.7 26.6 42.4 58.9 71.4 81.0 88.7 95.8 98.0 98.9 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.
P-61 suspended-sediment samples collected at the Grand Canyon gaging station on September 26, 1998; vertical located at the station 190 ft from the right-bank end point of the cableway

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

Pointor DI 

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

11:45 Up DI 6.86 n/a 18.66 1.074 159 150 13.7 28.9 46.2 64.7 76.6 85.2 87.8 93.1 96.2 99.0 100.0 100.0 100.0 100.0 100.0 100.0 11:49 Point 6.92 0.22 20.00 0.737 200 523 5.3 10.7 15.8 22.0 28.4 36.7 45.6 61.0 79.7 89.2 98.2 99.5 100.0 100.0 100.0 100.0 11:56 Point 6.92 0.22 20.00 0.646 144 404 0.0 14.7 20.2 25.5 31.7 39.2 47.5 60.9 79.8 88.8 97.9 99.5 100.0 100.0 100.0 100.0 11:58 Point 6.92 0.22 20.00 0.737 179 401 5.7 12.3 18.7 29.0 40.9 57.6 74.6 85.6 93.1 97.7 99.8 100.0 100.0 100.0 100.0 100.0 12:01 Point 6.92 0.68 20.00 1.028 171 294 8.9 17.6 26.7 35.7 45.2 56.5 67.4 79.2 90.6 96.6 99.7 100.0 100.0 100.0 100.0 100.0 12:04 Point 6.92 0.68 20.00 0.999 188 255 8.3 17.0 26.5 37.2 50.1 62.6 72.9 80.7 89.9 95.9 99.6 100.0 100.0 100.0 100.0 100.0 12:06 Point 6.92 0.68 20.00 0.969 165 259 5.0 13.5 23.1 34.8 50.4 66.5 74.8 82.1 89.4 95.1 99.1 100.0 100.0 100.0 100.0 100.0 12:09 Point 6.92 1.12 16.00 1.127 159 170 9.9 19.4 31.0 46.3 64.1 78.1 84.3 90.8 97.0 98.8 100.0 100.0 100.0 100.0 100.0 100.0 12:12 Point 6.92 1.12 16.00 1.048 166 195 8.8 19.6 30.9 48.3 65.7 76.2 85.2 92.2 95.8 98.3 100.0 100.0 100.0 100.0 100.0 100.0 12:15 Point 6.92 1.12 16.00 1.086 164 184 10.3 20.8 34.0 48.2 63.1 78.1 85.5 90.5 97.4 98.9 99.9 100.0 100.0 100.0 100.0 100.0 12:19 Point 6.92 2.79 13.00 1.268 159 168 9.3 25.2 40.8 56.7 71.6 77.8 85.4 92.6 97.1 99.8 99.9 100.0 100.0 100.0 100.0 100.0 12:22 Point 6.92 2.79 13.00 1.173 163 145 12.4 30.5 44.1 60.8 73.4 81.9 87.0 90.4 97.7 99.6 100.0 100.0 100.0 100.0 100.0 100.0 12:24 Point 6.92 2.79 13.00 1.188 160 140 12.2 24.6 44.0 66.6 77.1 85.6 88.1 94.2 96.8 98.8 99.7 100.0 100.0 100.0 100.0 100.0 12:28 Point 6.92 4.30 11.00 1.236 149 127 14.3 29.0 53.0 70.0 83.7 91.4 97.4 99.0 99.5 99.8 99.8 100.0 100.0 100.0 100.0 100.0 12:30 Point 6.92 4.30 12.00 1.212 162 136 8.8 28.4 44.5 67.9 78.4 88.3 90.5 92.4 94.4 99.4 100.0 100.0 100.0 100.0 100.0 100.0 12:32 Point 6.92 4.30 12.00 1.231 170 117 19.2 32.5 50.5 69.0 86.4 93.3 97.8 98.6 99.6 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:34 Point 6.92 6.57 12.00 1.102 155 74.9 17.5 37.9 58.4 72.0 85.4 88.1 93.4 99.1 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:37 Point 6.92 6.57 13.00 1.165 158 93.7 10.0 29.4 57.6 72.0 85.9 93.1 97.3 99.7 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:39 Point 6.92 6.57 13.00 1.151 138 57.4 21.2 44.2 63.4 83.6 92.1 98.2 99.7 99.8 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 12:42 Up DI 6.98 n/a 16.07 0.984 174 136 16.8 34.5 48.2 60.8 72.8 84.5 91.1 94.3 98.1 100.0 100.0 100.0 100.0 100.0 100.0 100.0 13:40 Up DI 6.91 n/a 16.06 0.978 156 176 6.7 14.4 27.7 42.4 55.0 62.4 71.8 77.6 85.2 92.3 97.0 99.4 100.0 100.0 100.0 100.0 13:43 Up DI 6.91 n/a 15.72 1.084 154 129 13.3 25.1 42.0 52.4 63.3 69.5 73.7 79.0 87.4 98.2 99.6 99.9 100.0 100.0 100.0 100.0 15:47 Up DI 6.40 n/a 14.20 1.005 120 123 10.0 21.7 38.2 57.7 67.8 74.4 81.9 87.2 93.8 98.8 100.0 100.0 100.0 100.0 100.0 100.0 15:51 Up DI 6.37 n/a 14.68 0.963 135 116 10.5 23.8 36.9 52.6 62.4 66.5 72.9 82.4 90.6 99.5 100.0 100.0 100.0 100.0 100.0 100.0 

Notes: Up DI = depth-integrated on upward transit (intake closed during downward transit); Water depths associated with the point samples are the mean water depths at this vertical during the collection of the 18 point sampl

relative to the mean bed elevation associated with this mean water depth.

Single-vertical D-96-A1 suspended-sediment samples collected at the Grand Canyon gaging station on August 31, 2007; vertical located at the station 253 ft from the right-bank end point of the cablewa

Time

(MST)

Sample

type 

Water 

depth

(m)

Sample

elevation

above

bed (m)

Sample

collection

time

(s)

DI

intake 

velocity

(m/s)

Silt and 

clay 

conc.

(mg/L)

Sand

conc.

(mg/L)

Grain-size analysis of sand (0.0625-2.0 mm) fraction

% sand

< 0.074 

mm

% sand

< 0.088 

mm

% sand

< 0.105 

mm

% sand

< 0.125 

mm

% sand

< 0.149 

mm

% sand

< 0.177 

mm

% sand

< 0.210 

mm

% sand

< 0.250 

mm

% sand

< 0.297 

mm

% sand

< 0.354 

mm

% sand

< 0.420 

mm

% sand< 0.500 

mm

% sand

< 0.595 

mm

% sand< 0.707 

mm

% sand

< 0.841 

mm

% sand

< 1.00

mm

% 

< 

9:36 DI 5.18 n/a 40.20 0.829 1,140 389 9.1 20.3 37.2 53.9 67.5 78.6 86.1 91.4 95.0 97.1 98.4 99.1 99.4 99.8 99.9 100.0 9:39 DI 5.18 n/a 38.24 0.780 1,180 461 8.4 19.0 35.4 52.4 66.6 78.4 86.2 91.7 95.3 97.4 98.5 99.2 99.5 99.8 99.9 100.0 9:41 DI 5.18 n/a 38.24 0.792 1,200 448 8.2 18.7 35.0 51.8 65.8 77.6 85.5 91.1 94.8 96.7 97.9 98.6 99.0 99.6 99.8 100.0 9:44 DI 5.18 n/a 38.24 1.080 1,200 379 8.5 19.2 35.4 51.8 65.4 76.9 84.6 90.3 94.5 97.0 98.4 99.3 99.6 99.8 99.9 100.0 9:46 DI 5.18 n/a 38.24 0.860 1,180 406 8.5 19.2 35.7 52.2 65.9 77.6 85.5 91.1 95.0 97.1 98.4 99.2 99.5 99.8 99.9 100.0 9:48 DI 5.18 n/a 37.25 1.102 1,200 372 9.2 20.7 38.0 54.9 68.5 79.7 86.9 92.0 95.3 97.3 98.5 99.3 99.6 99.8 99.9 100.0 9:50 DI 5.18 n/a 37.25 1.043 1,230 425 8.2 18.6 34.7 51.1 64.8 76.4 84.2 89.9 93.9 96.5 97.9 98.9 99.4 99.7 99.9 100.0 9:52 DI 5.18 n/a 39.22 1.020 1,200 375 8.4 19.3 36.2 53.2 67.2 78.8 86.3 91.6 95.2 97.3 98.6 99.4 99.6 99.8 99.9 100.0 9:54 DI 5.18 n/a 39.22 1.042 1,230 399 8.3 19.1 36.0 53.2 67.2 79.1 86.8 92.2 95.6 97.5 98.6 99.3 99.6 99.8 99.9 100.0 9:56 DI 5.18 n/a 41.18 0.853 1,230 516 7.3 17.0 32.7 49.3 63.6 75.8 84.0 90.1 94.4 97.0 98.5 99.3 99.6 99.8 99.9 100.0 9:59 DI 5.18 n/a 38.24 0.870 1,240 459 8.2 19.1 35.8 52.8 67.0 78.8 86.8 92.7 96.5 98.7 99.6 99.9 100.0 100.0 100.0 100.0 

10:01 DI 5.18 n/a 39.22 0.906 1,240 410 9.6 20.5 36.4 52.1 65.0 75.8 83.4 89.5 94.1 97.2 99.1 99.9 100.0 100.0 100.0 100.0 10:04 DI 5.18 n/a 39.22 0.958 1,230 485 8.0 18.4 34.7 51.7 66.0 78.1 86.0 91.6 95.3 97.5 98.7 99.4 99.6 99.8 99.9 100.0 10:06 DI 5.18 n/a 40.20 1.015 1,230 484 7.8 18.0 34.0 50.5 64.5 76.4 84.6 90.6 94.8 97.1 98.4 99.2 99.5 99.8 99.9 100.0 

Notes: DI = depth-integrated (nozzle open during downward and upward transits).
Appendix B 87

Appendix B . Cross-Stream Spatial Structures in Depth-Integrated SuspendedSediment Concentration in Noncomposited Nine-Vertical Measurements at the River-mile 30 Sediment Station and Lower Marble 

Canyon Gaging Station
88 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure B1. Stable and unstable cross-stream spatial structures 

in depth-integrated suspended-sand concentration along cross 

section A at the River-mile 30 sediment station (figs. 1, 2D). Error 

bars indicate mean number-of-transits error (MNOTE) at each 

vertical; see appendix A for data. A, Normalized suspendedsand concentration at each of nine verticals sampled during 

two measurements on February 24, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that spatial 

cross-stream structure in suspended-sand concentration is 

dissimilar between two measurements spaced ~6 hours apart. 

B, Normalized suspended-sand concentration at each of nine 

verticals sampled during the two measurements on August 24, 

2007. Note that spatial cross-stream structure in suspended-sand 

concentration is similar between two measurements spaced ~2 

hours apart. C, Normalized suspended-sand concentration at each 

of nine verticals sampled during two measurements on August 25, 

2007. Note that spatial cross-stream structure in suspended-sand 

concentration is dissimilar between two measurements spaced 

~2 hours apart. D, Relation between normalized suspended-sand 

concentrations at each vertical sampled in measurements 1 (C1) 

and 2 (C2) on February 24 and on August 24 and 25, 2007. Only 

relation between measurements on August 24 is significant at 

p=0.05 level.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

February 24, 2007

C2 = 1.0 - 0.050C1, R2

= 0.014, p = 0.76 

August 24, 2007

C2 = 0.36 + 0.64C1, R2

= 0.61, p = 0.013 

August 25, 2007

C2 = 0.12 + 0.88C1, R2

= 0.36, p = 0.086 

EXPLANATION

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 55.2 mg/L 

Measurement 2 (~6 hours later),

mean concentration = 68.9 mg/L 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 64.5 mg/L 

Measurement 2 (~2 hours later),

mean concentration = 87.9 mg/L 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 128 mg/L 

Measurement 2 (~2 hours later),

mean concentration = 67.3 mg/L 

NORMALIZED SUSPENDED-SAND CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

SUSPENDED-SAND CONCENTRATION

 AT VERTICAL

 MEASUREMENT 2 NORMALIZED SUSPENDED-SAND CONCENTRATION AT VERTICAL

VERTICAL

D
Appendix B 89

Figure B2. Unstable cross-stream spatial structures in depthintegrated suspended-sand concentration along cross section 

B at the River-mile 30 sediment station (figs. 1, 2D). Error bars 

indicate mean number-of-transits error (MNOTE) at each 

vertical; see appendix A for data. A, Normalized suspendedsand concentration at each of nine verticals sampled during 

two measurements on August 24, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that spatial 

cross-stream structure in suspended-sand concentration is 

dissimilar between two measurements spaced ~1.5 hours apart. 

B, Normalized suspended-sand concentration at each of nine 

verticals sampled during two measurements on August 25, 2007. 

Note that spatial cross-stream structure in suspended-sand 

concentration is dissimilar between the two measurements 

spaced ~1.5 hours apart and that both cross-stream spatial 

structures appear to differ from those observed on previous day. 

C, Relation between normalized suspended-sand concentrations 

at each vertical sampled in measurements 1 (C1) and 2 (C2) on 

August 24 and 25, 2007. Relations are not significant at p=0.05 

level, indicating no significant temporal correlation in suspendedsand concentration at each vertical over time scales of hours. 

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 24, 2007

C2 = -0.043 + 1.0C1, R2

= 0.11, p = 0.37 

August 25, 2007 

C2 = 0.64 + 0.36C1, R2

= 0.23, p = 0.19 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 121 mg/L

Measurement 2 (~1.5 hours later), 

mean concentration = 65.7 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 51.1 mg/L

Measurement 2 (~1.5 hours later), 

mean concentration = 92.8 mg/L

NORMALIZED SUSPENDED-SAND CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

SUSPENDED-SAND CONCENTRATION 

 AT VERTICAL

MEASUREMENT 2 NORMALIZED 

SUSPENDED-SAND CONCENTRATION  AT VERTICAL

VERTICAL
90 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure B3. Stable cross-stream spatial structures in depthintegrated suspended-sand concentration along cross section 

A at the Lower Marble Canyon gaging station (fig. 1, 2C). Error 

bars indicate mean number-of-transits error (MNOTE) at each 

vertical; see appendix A for data. A, Normalized suspendedsand concentration at each of nine verticals sampled during two 

measurements on August 28, 2007; concentration at each vertical 

in each measurement normalized by mean concentration among 

all nine verticals in each measurement. Note that cross-stream 

spatial structure in suspended-sand concentration appears to 

be similar between two measurements spaced ~2 hours apart. 

B, Normalized suspended-sand concentration at each of nine 

verticals sampled during two measurements on August 29, 2007. 

Note that cross-stream spatial structure in suspended-sand 

concentration appears to be similar between two measurements 

spaced ~1.5 hours apart. C, Relations between normalized 

suspended-sand concentrations at each vertical sampled 

in measurements 1 (C1) and 2 (C2) on August 28 and 29, 2007. 

Relations are significant at p=0.05 level, indicating significant 

temporal correlation in suspended-sand concentration at each 

vertical over time scales of hours on each day. Note similarity of 

relations on both days, identical to behavior observed along cross 

section C (fig. 13C).

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007

C2 = 0.32 + 0.68C1, R2

= 0.55, p = 0.022 

August 29, 2007

C2 = 0.44 + 0.56C1, R2

= 0.59, p = 0.015 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 101 mg/L 

Measurement 2 (~2 hours later), 

mean concentration = 109 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 239 mg/L 

Measurement 2 (~1.5 hours later), 

mean concentration = 218 mg/L

NORMALIZED SUSPENDED-SAND CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

SUSPENDED-SAND CONCENTRATION 

 AT VERTICAL

MEASUREMENT 2 NORMALIZED 

SUSPENDED-SAND CONCENTRATION  AT VERTICAL

VERTICAL
Appendix B 91

Figure B4. Unstable cross-stream spatial structures in depthintegrated suspended-sand concentration along cross section 

B at the Lower Marble Canyon gaging station (figs. 1, 2C). Error 

bars indicate mean number-of-transits error (MNOTE) at each 

vertical; see appendix A for data. A, Normalized suspendedsand concentration at each of nine verticals sampled during 

two measurements on August 28, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that crossstream spatial structure in suspended-sand concentration is 

dissimilar between two measurements spaced ~2 hours apart. 

B, Normalized suspended-sand concentration at each of nine 

verticals sampled during two measurements on August 29, 2007. 

Note that cross-stream spatial structure in suspended-sand 

concentration is dissimilar between two measurements spaced 

~1.5 hours apart and that both cross-stream spatial structures 

appear to differ from those observed on previous day. C, Relations 

between normalized suspended-sand concentrations at each 

vertical sampled in measurements 1 (C1) and 2 (C2) on August 

28 and 29, 2007. Relations are not significant at p=0.05 level, 

indicating no significant temporal correlation in suspended-sand 

concentration at each vertical over time scales of hours.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007

C2 = 1.1 - 0.082C1, R2

= 0.0064, p = 0.84 

August 29, 2007

C2 = 0.74 + 0.26C1, R2

= 0.063, p = 0.51 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 126 mg/L 

Measurement 2 (~2 hours later), 

mean concentration = 107 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 255 mg/L 

Measurement 2 (~1.5 hours later), 

mean concentration = 235 mg/L

NORMALIZED SUSPENDED-SAND CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

SUSPENDED-SAND CONCENTRATION 

 AT VERTICAL

MEASUREMENT 2 NORMALIZED 

SUSPENDED-SAND CONCENTRATION  AT VERTICAL

VERTICAL
92 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure B5. Stable and unstable cross-stream spatial structures 

in depth-integrated suspended-silt-and-clay concentration along 

cross section A at the River-mile 30 sediment station (figs. 1, 2D). 

Error bars indicate mean number-of-transits-error (MNOTE) at each 

vertical; see appendix A for data. A, Normalized suspended-siltand-clay concentration at each of nine verticals sampled during 

two measurements on February 24, 2007; concentration at each 

vertical in each measurement normalized by mean concentration 

among all nine verticals in each measurement. Note that crossstream spatial structure in suspended-silt-and-clay concentration is 

dissimilar between two measurements spaced ~6 hours apart. 

B, Normalized suspended-silt-and-clay concentration at each of 

nine verticals sampled during two measurements on August 24, 

2007. Note that cross-stream spatial structure in suspended-siltand-clay concentration is dissimilar between two measurements 

spaced ~2 hours apart. C, Normalized suspended-silt-and-clay 

concentration at each of nine verticals sampled during two 

measurements on August 25, 2007. Note that spatial cross-stream 

structure in suspended-silt-and-clay concentration is similar 

between two measurements spaced ~2 hours apart. D, Relations 

between normalized suspended-silt-and-clay concentrations 

at each vertical sampled in measurements 1 (C1) and 2 (C2) on 

February 24 and on August 24 and 25, 2007. Only relation between 

measurements on August 25 is significant at p=0.05 level.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

February 24, 2007

C2 = 1.1 - 0.10C1, R2

= 0.014, p = 0.77 

August 24, 2007

C2 = 0.65 + 0.35C1, R2

= 0.13, p = 0.34

August 25, 2007

C2 = 0.33 + 0.67C1, R2

= 0.65, p = 0.0087 

EXPLANATION

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 47.7 mg/L 

Measurement 2 (~2 hours later),

mean concentration = 27.7 mg/L 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 31.2 mg/L 

Measurement 2 (~2 hours later),

mean concentration = 34.7 mg/L 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 16.8 mg/L

Measurement 2 (~6 hours later),

mean concentration = 17.2 mg/L 

NORMALIZED SUSPENDED-SILT-AND-CLAY CONCENTRATION

A

B

C

MEASUREMENT 1 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY

CONCENTRATION AT VERTICAL

MEASUREMENT 2 NORMALIZED  SUSPENDED-SILT-AND-CLAYCONCENTRATION AT VERTICAL

VERTICAL

D
Appendix B 93

Figure B6. Stable and unstable cross-stream spatial structures 

in depth-integrated suspended-silt-and-clay concentration 

along cross section A at the Lower Marble Canyon gaging 

station (figs. 1, 2C). Error bars indicate mean number-of-transit 

error (MNOTE) at each vertical; see appendix A for data. A, 

Normalized suspended-silt-and-clay concentration at each of 

nine verticals sampled during two measurements on August 

28, 2007; concentration at each vertical in each measurement 

normalized by mean concentration among all nine verticals in 

each measurement. Note that cross-stream spatial structure 

in suspended-silt-and-clay concentration is similar between 

two measurements spaced ~2 hours apart. B, Normalized 

suspended-silt-and-clay concentration at each of nine verticals 

sampled during two measurements on August 29, 2007. Note 

that although cross-stream spatial structure in suspendedsilt-and-clay concentration is somewhat similar between two 

measurements spaced ~1.5 hours apart, suspended-silt-and-clay 

concentrations differ widely between two measurements at 

vertical 8. C, Relations between normalized suspended-silt-andclay concentrations at each vertical sampled in measurements 

1 (C1) and 2 (C2) on August 28 and 29, 2007. Relation between 

measurements on August 28 is significant at p=0.05 level, 

whereas that between measurements on August 29 is not.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007

C2 = 0.62 + 0.38C1, 

R2

= 0.51, p = 0.030 

August 29, 2007

C2 = -1.0 + 2.0C1, 

R2

= 0.22, p = 0.21 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 1,150 mg/L 

Measurement 2 (~2 hours later), 

mean concentration = 793 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 6,590 mg/L 

Measurement 2 (~1.5 hours later), 

mean concentration = 9,710 mg/L

NORMALIZED SUSPENDED-SILT-AND-CLAY CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY

 CONCENTRATION AT VERTICAL

MEASUREMENT 2 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY CONCENTRATION AT VERTICAL

VERTICAL
94 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Figure B7. Unstable cross-stream spatial structures in depthintegrated suspended-silt-and-clay concentration along cross 

section B at the Lower Marble Canyon gaging station (figs. 1, 2C). 

Error bars indicate mean number-of-transits error (MNOTE) at 

each vertical; see appendix A for data. A, Normalized suspendedsilt-and-clay concentration at each of nine verticals sampled 

during two measurements on August 28, 2007; concentration 

at each vertical in each measurement normalized by mean 

concentration among all nine verticals in each measurement. 

Note that cross-stream spatial structure in suspended-silt-and-clay 

concentration is dissimilar between two measurements spaced 

~2 hours apart (mostly at verticals 6, 7, and 9). B, Normalized 

suspended-silt-and-clay concentration at each of nine verticals 

sampled during two measurements on August 29, 2007. Note that 

suspended-silt-and-clay concentration is basically uniform across 

entire cross section in both measurements. C, Relations between 

normalized suspended-silt-and-clay concentrations at each 

vertical sampled in measurements 1 (C1) and 2 (C2) on August 

28 and 29, 2007. Neither relation is significant at p=0.05 level; 

however, note that analysis is hampered by uniform distribution of 

suspended silt and clay across cross section.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007

C2 = 1.3 - 0.26C1, R2

= 0.092, p = 0.48 

August 29, 2007

C2 = 0.20 + 0.80C1, R2

= 0.18, p = 0.077 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 1,110 mg/L

Measurement 2 (~2 hours later), 

mean concentration = 747 mg/L

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 5,950 mg/L 

Measurement 2 (~1.5 hours later), 

mean concentration = 8,090 mg/L

NORMALIZED SUSPENDED-SILT-AND-CLAY CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY

 CONCENTRATION AT VERTICAL

MEASUREMENT 2 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY CONCENTRATION AT VERTICAL

VERTICAL
Appendix B 95

Figure B8. Unstable cross-stream spatial structures in depthintegrated suspended-silt-and-clay concentration along cross 

section C at the Lower Marble Canyon gaging station (figs. 1, 2C). 

Error bars indicate mean number-of-transits error (MNOTE) at 

each vertical; see appendix A for data. A, Normalized suspendedsilt-and-clay concentration at each of nine verticals sampled 

during two measurements on August 28, 2007; concentration 

at each vertical in each measurement normalized by mean 

concentration among all nine verticals in each measurement. 

Note that cross-stream spatial structure in suspended-silt-andclay concentration is dissimilar between two measurements 

spaced ~2 hours apart (mostly at verticals 1, 5, and 9). B, 

Normalized suspended-silt-and-clay concentration at each of nine 

verticals sampled during two measurements on August 29, 2007. 

Note that although cross-stream spatial structure in suspendedsilt-and-clay concentration is somewhat similar between two 

measurements spaced ~1.5 hours apart, suspended-silt-and-clay 

concentrations differ widely between two measurements at 

vertical 9. C, Relations between normalized suspended-silt-andclay concentrations at each vertical sampled in measurements 

1 (C1) and 2 (C2) on August 28 and 29, 2007. Neither relation is 

significant at p=0.05 level.

0.0

0.5

1.0

1.5

2.0

0.0 0.5 1.0 1.5 2.0

August 28, 2007

C2 = 0.91 + 0.088C1, 

R2

= 0.0041, p = 0.87 

August 29, 2007

C2 = -0.42 + 1.4C1, 

R2

= 0.26, p = 0.16 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 1,490 mg/L 

Measurement 2 (~2 hours later),

mean concentration = 1,020 mg/L 

0.0

0.5

1.0

1.5

2.0

1 2 3 4 5 6 7 8 9

Measurement 1,

mean concentration = 6,560 mg/L 

Measurement 2 (1.5 hours later),

mean concentration = 9,630 mg/L 

NORMALIZED SUSPENDED-SILT-AND-CLAY CONCENTRATION

A

B

C

 MEASUREMENT 1 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY

 CONCENTRATION AT VERTICAL

MEASUREMENT 2 NORMALIZED 

 SUSPENDED-SILT-AND-CLAY CONCENTRATION AT VERTICAL

VERTICAL

Produced in the Menlo Park Publishing Service Center, California

Manuscript approved for publication, July 29, 2011

Edited by George A. Havach and Peter Stauffer
98 Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers

Topping and others—Field Evaluation of Error from Inadequate Time Averaging in Depth-Integrating Suspended-Sediment Samplers—Professional Paper 1774

98 Field Evaluation of Depth-Integrating Suspended-Sediment Samplers