Fluorescent Sand as a 

Tracer of Fluvial 

Sediment

GEOLOGICAL SURVEY PROFESSIONAL PAPER 562-E
Fluorescent Sand as a 

Tracer of Fluvial 

Sediment

By VANCE C. KENNEDY and DOROTHY L. KOUBA

SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

GEOLOGICAL SURVEY PROFESSIONAL PAPER 562-E

An investigation of sand movement 

in a gravel-bed stream

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 30 cents (paper cover)
CONTENTS

Abstract-.- -_---___-------------------_-

Introduction. ___________________________

Acknowledgments__ ____________________

Methods used in this study_____________

Coating of grains with fluorescent paint. 

Sampling of stream sand____________

Sample processing.__________________

The experiment_______________________

Results_-_-______---__-____--_-----___

Page 

El

1

2

2

2

2

2

3

3

Results Continued

Relation of grain velocity to grain size___-_--____- E5

Mixing of fluorescent grains.-____________________ 7

Estimation of sediment discharge.________________ 10

Experiment with batch addition__________________ 11

Estimation of sediment in active storage within a

reach______________________________________ 12

Other possible uses for fluorescent solids in stream studies. 12 

Conclusions._______________________________________ 13

References cited.___________________________________ 13

ILLUSTRATIONS

Page 

FIGURE 1. Sketch map of study reach on Clear Creek at Golden, Colo_._______--_____-_----____-_- El

2. Sketch of equipment used in sampling transported sand______________________________ 2

3-10. Graphs showing concentration of fluorescent grains at station 3 resulting from addition at 

station 1:

3. Size range 0.99-1.29 mm-_-_-_____-_---_-___----_---__-__--_---_-----_--__- 4

4. Size range 0.86-0.99 mm-__-______-____-____-___-_-_____---____--_-----___- 4

5. Size range 0.52-0.86 mm_--_-_-_____-____-----_----_-_-_-------_-----_-_-_- 5

6. Size range 0.38-0.52 mm__-_________________-_-_-_-_-_-------_-_---________ 6

7. Size range 0.30-0.38 mm__-_____________________---_-_--__-_-_-_--__-______ 6

8. Size range 0.25-0.30 mm-___-_--_______--_-_---_-_-_-_---_-__----_-----___- 7

9. Size range 0.18-0.25 mm_______________________-__________-_--___-_________ 8

10. Size range 0.15-0.18 mm._______________________________-------_-_-___-____ 9

11-14. Graphs showing:

11. Relation of traveltime to grain size for fluorescent sand in Clear Creek..________ 9

12. Lateral mixing of fluorescent sand as related to grain size.._____________________ 9

13. Sediment discharge in relation to grain size as determined by depth-integrated

sampling and the fluorescent-tracer method__________-_-__-_---_-___-____. 10

14. Variation in concentration of 0.25 to 0.52 mm blue fluorescent sand at station 3

after batch addition at station 1_______________________________________ 11

TABLES

TABLE 1. Average number of fluorescent grains per minute added to Clear Creek in various size 

fractions.-______________________________________________________---_-______

2. Comparison of sediment discharge in Clear Creek calculated from depth-integrated samples 

and fluorescent-sand measurements ____________________________________________

3. Time to reach peak concentration of blue grains at station 3 as related to grain diameter. _ _

4. Sediment in active storage in Clear Creek.___________________________________________

Page 

E5

10

12

12

SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT

By VANCE C. KENNEDY and DOROTHY L. KOUBA

ABSTRACT

Stream sand coated with fluorescent paint was added at a 

constant known rate to dear Creek at Golden, Colo., during a 

28-hour period, and the concentration of fluorescent grains was 

monitored at a point 810 meters downstream from the point of 

introduction. Stream width in the study reach averaged about 

21 meters, mean velocity about 1.4 meters per second, and mean 

discharge 8.2 cubic meters per second. Flow was very turbulent 

over a gravel bed.

First-arrival time of fluorescent sand correlated with the 

square of grain diameter in the range 0.15-0.86 millimeters. Although Clear Creek meanders gently, complete lateral mixing of 

fluorescent sand was not achieved within the study reach. However, steady-state conditions apparently were achieved for the 

finer particles, with highest concentrations on the north side 

and lowest concentrations on the south side of the stream. 

Lateral mixing of coarser grains was much better than for finer 

grains.

Suspended-sediment discharges for various size ranges were 

computed from suspended-sediment samples which do not include sand-sized particles moving near or on the bed and from 

"dilution" of fluorescent sand which presumably measures total 

sediment discharges. The sediment discharge computed from 

the tracer-dilution method was about 30 percent greater than the 

suspended-sediment discharge computed from suspended samples 

for the 0.15-0.18 millimeter range and about 200 percent greater 

for the 0.38-0.52 millimeter range.

INTRODUCTION

A study of the movement of fluorescent sand in Clear 

Creek about 24 km (kilometers), or 15 miles, west of 

Denver, Colo., was made during the period May 26-28, 

1965. The 0.8 km (half-mile) study reach (fig. 1) began 

about 300 m (meters), or 1,000 feet, downstream from 

where Clear Creek leaves the Front Eange of the 

Colorado Eockies and ended within the town of Golden.

The main purpose of the investigation was to evaluate 

the use of fluorescent sand as a means of measuring sand 

discharge in a gravel-bed stream. This report summarizes the results of that study and also includes 

suggestions for other uses of solid fluorescent tracers in 

stream investigations.

Fluorescent materials have been used extensively in 

studying the movement of beach sediments (Aybulatov

and others, 1961; Eussel, 1961; Bruun, 1965; Kidson 

and Carr, 1962; and Ingle, 1966). Teleki (1966), Yasso 

(1962), and others have described techniques for coating sand. Glazov and Glazov (1959) and Zenkovitch 

(1958) indicated that sand coated with fluorescent paint 

has been used to study fluvial sand movement in the 

U.S.S.E., but details were not given. There apparently 

has been very little, if any, use of fluorescent particles as 

tracers in American streams. Instead, radioactive tracer 

particles have generally been used here, for example, 

Krone (in Krone and others, 1960), Hubbell and Sayre 

(1964), and Cummins (1965).

The radioactive-tracer method has the advantage that 

the radioactivity of the stream sediments can be measured continuously without removing samples from the 

stream, and this can be done with great sensitivity. Conversion of the radioactivity data into sediment discharge 

may, however, require knowledge of both the particlesize distribution on the stream bed and the depth of 

sediment movement on the bed if surface labeled particles are used. Prdinarily, coring of the bed sediments 

would be required to obtain this information. The radioactive-tracer method has the disadvantage that it requires clearance from various public agencies before use, 

and moderately expensive equipment is required to 

measure the radioactivity and to protect against radiation hazards.

K . . Middle,, _ North point South 

point I point

I I

183 METERS » 

CROSS SECTION AT STATION 3

FIGUBE 1. Sketch map of study reach on Clear Creek at Golden,

Colo.

El
E2 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

Fluorescent-sand tracers are also easily detected, and 

sensitivity is limited mainly by the size of the sample 

collected. Aybulatov, Boldyrev, and Griesseier (1961) 

claim a sensitivity of 1 part per 10 million. Except in 

clear shallow water, samples of sediment must be taken 

from the stream before the fluorescent particles can be 

detected. An ultraviolet light is all that is required for 

detection, and several different fluorescent colors can 

be used simultaneously to identify grains differing in 

size, shape, or specific gravity. When quantitative results are needed, relatively simple counting equipment 

can be used on fractions separated on the basis of sieve 

size or fall diameter. Both Teleki (1965) and DeVries 

(1966) have described instruments for counting fluorescent grains automatically.

ACKNOWLEDGMENTS

This experiment would have been impossible without the help of R. L. Malcolm, E. A. Jenne, R. C. Scott, 

F. C. Ames, F. C. Canney, and J. O. Johnson. Extensive discussions of the results with C. Nordin, W. W. 

Sayre, E. V. Richardson, and F. C. Ames have greatly 

aided in clarifying the significance of the data. A. T. 

Miesch supervised computer testing of the equations for 

lateral mixing of sediment. Professor R. B. Krone, of 

the University of California, kindly read the manuscript and made several constructive suggestions. To 

these individuals the authors express their great 

appreciation.

Personnel from the U.S. Bureau of Reclamation 

provided the washed sized sand from Clear Creek.

METHODS USED IN THIS STUDY 

COATING OF GRAINS WITH FLUORESCENT PAINT

Sand from Clear Creek was washed and sieved into 

three size fractions: 0.15-0.30, 0.30-0.52, and 0.52-1.29 

mm (millimeters). Each size fraction of thoroughly 

dried sand was coated with a different colored paint by 

placing it in a small motor-driven cement mixer along 

with an acetone solution of a water-insoluble fluorescent 

pigment.1 As soon as a thin layer of the acetone solution had coated the grains, they were spread out to dry 

on a polyethylene sheet. The resulting poorly cemented 

aggregates were passed between rubber rollers to reduce 

them to single grains. The number of fluorescent grains 

per gram in each size fraction was then determined by 

counting under ultraviolet light.

Cost of such coating can be less than 4.5 cents per 

kilogram (10 cents per Ib) if lots of several hundred 

kilograms are prepared.

1 Care was taken to do the coating outside in a strong breeze in order 

to reduce buildup of acetone vapors. In the pnoiper proportions airacetone m'ixtures are explosive and can be ignited by sparks from a 

motor turning the cement mixer.

SAMPLING OF STREAM SAND

A pumping sampler of the type shown in figure 2 

was used to obtain sediment moving near the stream 

bed. A rubber suction tube whose inside diameter (I.D.) 

measured 3.8 cm (centimeters) was placed on a base 

plate held on the stream bed in such a way that the 

open end of the tube was located about 15 cm (0.5 ft) 

back from the front of the base plate facing upstream. 

Water moving just above the bed entered the tube, 

passed through a 19 liter glass bottle, and then through 

a centrifugal water pump before returning to the 

stream. Coarse sediment settled in the glass bottle while 

fine sediment continued on through the pump. The glass 

bottle was replaced at intervals so that accumulated 

sediment could be removed. Although a considerable 

amount of sorting by size occurred during such sampling, this does not matter because it is the ratio of 

fluorescent to nonfluorescent grains in a particular size 

range that is important.

Three depth-integrated water-sediment samples were 

collected at station 3 during the period of study. Each 

sample consisted of a composite of subsamples collected 

at 15 equally spaced stream verticals in the cross section 

(U.S. Inter-Agency Comm. on Water Resources, 1952, 

p. 60-63; 1963). Sieve analyses of the suspended sands 

were made for two of the three composite samples. Such 

depth-integrated samples should be representative of 

silt and clay concentrations throughout the full depth 

of the stream because of uniform distribution throughout the stream vertical. However, because the sampler 

intake nozzle is lowered only to a point about 9 cm (0.3 

ft) above the stream bed, coarser sand-sized particles 

moving mainly on or near the stream bed are not adequately sampled.

SAMPLE PROCESSING

Each sediment sample was dried and sieved into eight 

size fractions covering the range 0.15-1.29 mm. Each 

size fraction was then placed in a vibratory feeder 

device with a spiral trough and observed under ultra1.9-cm-I.D. tubing 

3.8-cm-I.D. tubing

Handle for, 

man in boat

Water 

_ returns

FIGURE 2. Sketch of equipment used in sampling transported 

stream sand.
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT E3

violet light as the grains moved out of the feeder in 

virtually single file. The number of fluorescent grains 

of each color was recorded using a hand tabulator.

THE EXPERIMENT

The study reported here was intended to test the usefulness of the "steady-dilution" method (Clayton and 

Smith, 1963; Lean and Crickmore, 1963, 1966) as applied to the measurement of sediment discharge in Clear 

Creek at Golden, Colo. The test was made using fluorescent particles instead of radioactive materials as described in the articles mentioned, but the same general 

principles apply.

If a tracer of concentration d is added to a moving 

stream of material at a constant rate <?, the tracer will 

mix with the moving material, and at some point downstream a uniform concentration of the tracer in the material will be achieved. If C0 is the concentration of the 

tracer in the material before addition of tracer in the 

experiment, Q is the rate of transport of material, and 

C2 is the concentration of tracer after uniform mixing 

occurs, the following equation applies :

If C0 is taken as zero and Q is very large compared to 

q, then the equation is, in effect:

Where stream sand is transported mainly in suspension, samples collected at a station downstream from the 

point of tracer addition would be expected to show 

tracer concentrations increasing rather rapidly at first, 

then gradually reaching a "plateau" of constant concentration. If the tracer is moving on, or just above, the 

bed, the speed of movement may be low, and the concentration of tracer may increase slowly at the sampling 

point. When the constant concentration is reached, it is 

assumed that as many grains are passing the sampling 

point as are being added upstream. Normally, in order 

that such a constant concentration be reached, not only 

must the tracer be added at a constant rate, but the sand 

discharge being measured must also remain constant.

In this study a mixture containing 89 grams each of 

red 0.52-1.29-mm sand, yellow 0.30-0.52-mm sand, and 

green 0.15-0.30-mm sand was tossed into the middle of 

Clear Creek every 3 minutes beginning at 2 p.m. May 26 

and ending at 6 p.m. May 27, 1965. The fluorescent sand 

was added at station 1 (fig. 1) , and moving sediment 

was sampled intermittently at station 3 about 800 m 

(2,650 ft) downstream, during the periods from 2 : 05 

p.m. May 26 until 5 : 42 p.m. May 27 and from 10 : 12 

a.m. until 5 : 30 p.m. May 28, 1965. One set of three samples was obtained at station 2, about 400 m (1,300 ft)

downstream from the point of fluorescent-sand addition, between 1:00 and 3: 00 p.m. on May 27,1965. Blue 

fluorescent sand of 0.30-0.52-mm diameter was added in 

two batches, one at 6 p.m. May 26 and the other at 6 a.m. 

May 27.

During the first 28 hours of the experiment while 

fluorescent sand was being added, water discharge 

changed from about 8.8 to 7.8 m3 per sec (cubic meters 

per second), or from 310 cfs (cubic feet per second) to 

275 cfs. At the end of 62 hours, when the final sampling 

was completed, discharged was about 6.6 m3 per sec 

(235 cfs). Average velocity of the water was approximately 1.4 m per sec (meters per second), or 4.5 fps 

(feet per second), but maximum velocities were probably 

in the range 2 m per sec, or 6-7 fps, within the study 

reach.

Depth integrated samples collected at station 3 indicated 72 mg/1 (milligrams per liter) suspended sand 

19 hours after the beginning of the experiment and 65 

mg/1 at 26.5 hours, suggesting that there may have been 

some decrease in sediment discharge. However, this difference may be within the accuracy of the sediment sampling method and, hence, have little significance. A sample collected 1 hour after beginning the experiment was 

lost in processing.

Flow was over sediment whose average size was estimated to be a few centimeters but which contained cobbles as much as about 1 decimeter in diameter. Although 

some scattered showers occurred during and prior to the 

study period, the stream water remained relatively 

clear. Presumably, the natural sand being transported 

was derived from the bed and bank material in the channel system upstream from the study reach.

Sediment samples were also collected at station 3 

(fig. 1) by a pumping sampler for 15-minute periods 

during the first 2 hours. Thereafter, almost all samples 

were collected by pumping for 30-minute periods. Although most samples were collected at or near the midpoint of the stream, several were obtained near the north 

and south quarter points in order to determine the distribution of fluorescent material across the stream.

RESULTS

The changes in concentration of fluorescent particles 

with time at station 3 are shown in figures 3-10. ("Concentration," as used in this paper, refers to the ratio of 

fluorescent grains to iionfluorescent grains in a particular size range.) Narrow size ranges must be considered 

separately because the speed of transport and rate of 

mixing varies with grain size.

The time scale remains the same in each figure, although the concentration scale is changed for the various grain sizes. In figures 3-5, particles ranging from
E4 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

e.^

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2

< 20 

CD

8

E 15

w

z

<

cc

H 10

Z 

UJ

o 

w

UJ

a: c

0 5

3

_i 

u.

EXPLANATION I I |

At midpoint

- O

5-10 feet south of midpoint

 N 0S

At north po nt 

 S

 At south point

 S

- »N

_

9

O

0 

 * »N °.SOO| *Si.N |.N ^ |0 S.N

8

o B"z

100 *2UJ °- 

0. CD

W 7

55

< o

CD UJ

50 ^y 3

2z

^ o

o z

3

-J

u.

0 

04 8 12 16 20 24 28 32 36 40 44 48 52

TIME, IN HOURS

FIGURE 3. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.99-1.29 mm.

90 - " * 

80

70

w

2

2 60

CD

o

o

1-1

Z

- 50

w

z

< 

cc

CD

h- 40

z

UJ

o

w

UJ 

OL

0 30

_i 

u.

20

10

EXPLANATION

At midpoint S 

0 * 

 5-10 feet south of midpoint

 N

At north po nt 

.S %

_ At south point

 

.S A V

0 

*N

 ' 'N

V

/ .s

/

/

/

O »

~ o /

 >N 0 DX

 Xs Is

150

w

z

125 <

cc

O

(-

z

UJ

o

w

UJ

tr

100 O

3

-J

u.

Z

o

z

o

8

75 g

cc

UJ

Q_

w

z

50 |

hUJ 

O

w

UJ

cc

o

25 3

u.

0 - - n

0 4 8 12 16 20 24 28 32 36 40 44 48 52

TIME, IN HOURS

FIGURE 4. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.86-0.99 mm.
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT E5

280

240

< 200

160

EXPLANATION 

At midpoint

o

5-10 feet south of midpoint

 N 

At north point

 S 

At south point

/ 

.S

/CD0

os

150

100

75

50

25

16 24 28 32 

TIME, IN HOURS

36 40 48 52

FIGURE 5. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range

0.52-0.86 mm.

is

1.29 to 0.99 mm, 0.99 to 0.86 mm, and 0.86 to 0.52 mm in 

sieve diameter are considered. The scattering of points 

decreases with decreasing grain size; this is, in part at 

least, due to the larger number of fluorescent grains 

added in the finer fractions (table 1). In both the 0.86- 

0.99-mm and 0.99-1.29-mm size ranges, most of the samples collected contained less than 50 grams of material 

and less than 10 fluorescent grains. A constant plateau 

concentration was not achieved within the size range 

0.52-1.29 mm. It should be noted (figs. 3-5) that relatively high concentrations of tracer particles in the 0.52- 

0.99-mm range were still present at station 3, 20 hours 

after tracer addition ceased.

When one examines the curves for the finer grain 

sizes (figs. 6-10), a tendency to reach a constant concentration is apparent, and there is generally less deviation from a smooth curve than in the curves for the 

coarse sand. As grain size decreases, the time required 

for the first arrival of tracer particles at station 3 decreases (fig. 11), and there is an increase in the rate of 

removal of tracer particles from the study reach after 

tracer addition stopped (figs. 3-10).

TABLE 1 Average number of fluorescent grains per minute added to 

Clear Creek in various size fractions

Size range 

(millimeters) <

0. 15-0. 18____

. 18- .25- _

. 25- . 30 __

. 30- . 38____-

Number of grains 

idded per minute

272, 000

763, 000

225, 000

147, 000

Size range 

(millimeters)

0.38-0. 52 __ _

. 52- .86 __ _

.86- .99 _ __

.99-1. 29_____

Number of grains 

added per minute

76, 000

qo nnn

4,600

67

RELATION OF GRAIN VELOCITY TO GRAIN SIZE

The relation of maximum speed of movement to 

particle size was evaluated by plotting the time of the 

first arrival at station 3 against the square of the 

diameter of the smallest grains in a particular size fraction. The result for the 0.15-0.86-mm size range is virtually a straight line (fig. 11). The 0.86-mm material 

traveled at about 1.5 cm per sec (centimeters per second) or 3 feet per minute, which is %0 o the average 

velocity of the water between stations 1 and 3 and hence 

must have spent an appreciable part of the time on or 

near the stream bed. The fact that its time of first arrival 

lies on the same line as the finer sizes suggests that, 

throughout the 0.15-0.86-mm size range, the same general laws of transport may apply even though the 

coarser grains have spent a much greater percentage of 

time near or on the bed. Selection of the time of first 

arrival for the 0.99-mm sand is difficult because of the 

very few grains being transported in this size range. The 

point for 0.99 mm does not line up exactly with the other 

points in figure 11. This may be due simply to sampling 

error or to an actual change in the relation between 

grain velocity and grain size.

The fact that there is a good inverse correlation 

between velocity and the square of grain diameter for 

sand movement in Clear Creek raises the question as 

to whether a similar relation may exist under other 

conditions also. A plot of grain size versus grain velocity 

of beach sand was prepared by Ingle (1966, p. 158). 

Although the plot showed much scatter, there was a

369-125 O 7C
E6 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

ituu

1200

< 1000

8

Z 800

(/>

Z

<

ct

0 600 1-

z

HI 

O

a

g 400

D

H.

200

EXPLANATION

At midpoint

O

5-10 feet south of midpoint

 N

At north point

 S 

 At south point

 '^N .N 

.N

.N 

^,-^~~

^ 

/ o

/ o Jt ° «r ,s o ,s

/ 0 ^

^

/ N

/ .s «s 

A /*

-^*/*

1

250 

w

Z

ct

0

1-

z

HI

200 0 

w

HI

ct 

o

_J

H.

Z

150 §

o

8o"

o

oa

100 CL

w

Z

ct

0

1-

50 g

o

w

HI ct

0

_J

H.

n

0 4 8 12 16 20 24 28 32 36 40 44 48 52

TIME, IN HOURS

FIGUBE 6. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.38-0.52 mm.

3600

3200

2800

< 2400

Z 2000

1200

800

400

_ « -H _ _ _ _ __

00

EXPLANATION

At midpoint

O 

5-10 feet south of midpoint

 N 

At north point

 S 

At south point

12 16 «20 24 28 32 

TIME, IN HOURS

36 40 48

250 Z

150

100 a: 

o

50

52

FIGUBE 7. Concentration, of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.30-0.38 mm.
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT E7

ouuu

7200

6400

W 5600 

cc

o

o 4800

z 

w

< 4000

cc 

o

1-

Ul

0 3200

WUJ

OS 

0

_l 

" 2400

1600

800

1 1 1 1 1 1 1

_

N*

.N

EXPLANATION

At midpoint

O

5-10 feet south of midpoint

 N

At north point

 S

At south point

_____ ______

^^ 

 /^ o

 v

- / * °

/

/ (~\

7 * ° - ./

/ .s .s

 / .s

4 

9 / ^ A

/ 

~ * .s .«

I/ 1 1 1 1 1 1 1

200 

W

z

<

cr

o

iUJ

o 

150 2

tr

0

D 

_l 

u.

Z 

O

z

0

100 g

o 

a

UJ 

0.

w

z

<

K

50 0

\r

Z

UJ

o

w

UJ

cr

0

3

u. 

o - n

0 4 8 12 16 20 24 28 32 36 40 44 48 52

TIME, IN HOURS

FIGURE 8. Concentration of fluoresicent grains at station 3 resulting from addition at station 1. Size range is

0.25-0.30 mm.

decrease in velocity with increasing grain size. Yasso 

(1965) found in a study of beach sand movement that 

sand of 0.701-0.840-mm diameter moved at an average 

maximum transport velocity of 2.0 cm per sec, whereas 

sand of 0.589-0.701-mm diameter moved at 2.8 cm 

per sec. Inasmuch as first arrival times were used by 

Yasso (1965) in calculating velocity and the finest 

grains in any size fraction would be expected to arrive 

first, a comparison of velocity with finest grain size in 

a size fraction is appropriate. The ratio of speed of 

transport of Yasso's fine sand to coarse sand was 1.40,

of coarse sandV. -, * n 

- ] is 1.42. u j-u A- /diameter whereas the ratio (

diameter of fine sand 

The fact that these two ratios are virtually the same 

suggests that in Yasso's study also the speed of sand 

movement may have varied inversely with the square 

of grain diameter of the sand.

Because usable data are available for only two 

grain sizes from Yasso's study, the agreement of sand 

movement on the beach with sand movement in Clear 

Creek may be only fortuitous. Nevertheless, it seems

worth while to determine whether the inverse correla 

tion of maximum speed of movement with the square 

of grain diameter is characteristic of sand transport 

under conditions other than those present in Clear 

Creek.

MIXING OF FLUORESCENT GRAINS

The concentration of fluorescent particles at both stations 2 and 3 decreases from the north bank to the south 

bank, and this tendency becomes greater with decreasing 

grain size. Figure 12 shows a plot of the ratio of concentration of fluorescent grains at the north sampling point 

to that at the south point for sample sets taken at both 

stations 2 and 3 (see explanation of fig. 12 for times of 

sampling). It is apparent that the coarser grains are 

much better mixed across the stream than are the finer 

and that mixing improves as one might expect as the 

sediment moves downstream.

Although the points in figure 12 show a considerable 

amount of scatter, smooth empirical curves have been
E8 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

20,000

18,000

16,000

14,000

12,000

10,000

2 8000

4000 

.N

EXPLANATION

 

At midpoint

O

5-10 feet south of midpoint

 N 

At north point

 S 

At south point

/

.S

.3

300

250 C3

150

100 |

50

16 20 24 28 32 

TIME, IN HOURS

40 48

FIGURE 9. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.18-0.25 mm.

attributed to the different methods of movement. The 

coarse grains move near the stream bed, whereas the 

finer particles are more uniformly dispersed in the vertical. Although water velocities near the bed are relatively 

low, frequent changes of direction are necessitated by 

cobbles on the bed. Thus, lateral mixing is encouraged. 

At points higher in the vertical, there is less tortuosity 

in the water movement and finer grained particles there 

move more directly and rapidly downstream. The net 

result is to cause better mixing of coarse grains than 

fine at any specified distance below the point of tracer 

introduction.

Because the coarser particles move rather slowly but 

disperse laterally in a relatively short distance whereas 

the finer particles move rapidly but disperse laterally 

over a long distance, there is a tendency for the length 

of time for complete lateral dispersion to be constant 

regardless of grain size in a stream like Clear Creek. 

This suggests that two or three sampling cross sections 

should be located at various distances downstream from

drawn through them that fit the equation R= 

where R is the ratio

concentration of fluorescent grains on the north side 

concentration of fluorescent grains on the south side' 

D is grain diameter, e is the base of natural logarithms, 

and a and b are constants. The data at station 3 appear 

to follow the same equation as the data at station 2 with 

different values for the constants.

The available information does not suggest the nature 

of the curves for sizes less than 0.15 mm. However, in 

the empirical equation as the diameter approaches zero, 

the quantity elD approaches 1 and R approaches 1 + a. 

Thus, clay-sized particles might show an R value of 

about 1 + #.

It should be noted that the empirical equation appears 

to apply at the two cross sections sampled, but insufficient data are available to include the effect of downstream distance from the point of tracer introduction.

The fact that the coarser grains are more uniformly 

dispersed across the stream than the finer at station 3 is
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT E9

28,000

24,000

< 20,000 

C3

Z 16,000

12,000

8000

4000

EXPLANATION

At midpoint

O

5-10 feet south of midpoint

 N 

At north point

 S 

At south point

/

O O

o

300 <

{£. 

C3

250

200

150

8 12 20 24 28 32 36 40 44 48 

TIME, IN HOURS

FIGURE 10. Concentration of fluorescent grains at station 3 resulting from addition at station 1. Size range is

0.15-0.18 mm.

2 0.9

1 0.8

5

£ 0.7

O

<" 0.6

0.5

0.3

0.1

0.99

EXPLANATION

i 10.52

Range of time for sample collection, 

_ and particle diameter, in millimeters

/

/

.HQ.30

4 0.18

100 200 300 400 500 600 700 800 900 

TIME, IN MINUTES, FOR FIRST ARRIVAL 810 METERS 

DOWNSTREAM FROM POINT OF SAND INTRODUCTION

1000

FIGURE 11. Relation of traveltime to grain size for fluorescent 

sand in Clear Creek.

Q 20

O 16

uj 12

O

O 10

I I I

EXPLANATION

X

Station 2 at 23 to 25 hours after

beginning experiment

A

Station 3 at 20 to 22 hours after 

beginning experiment

Station 3 at 27 to 29 hours after 

beginning experiment

Plot of the function, 

RATIO = 1+32 e-475 DIAMETER

Plot of the function,

R ATIO = 1 + 1 1 e -5 65 DIAMETER

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 

MEDIAN DIAMETER OF SIZE FRACTIONS, IN MILLIMETERS

1.0

FIGURE 12. Lateral mixing of fluorescent sand as related to 

grain size.
E10 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

the point of tracer introduction. The closest cross section would be intended for study of the coarser sizes 

and the farthest cross section for the finest sizes. The 

period of sampling would be approximately the same at 

all cross sections.

ESTIMATION OF SEDIMENT DISCHARGE

Uniform mixing of tracer particles and constant sediment discharge are required if an accurate calculation of 

sediment discharge is to be made using tracer techniques. 

Also, the concentration of fluorescent particles at the 

sampling point must reach a constant value. None of 

these requirements were met perfectly in this study, and 

the lateral mixing of tracers was poor in the finer grain 

sizes. Nevertheless, calculations based on available data 

are enlightening.

Although tracer concentrations tended to be high on 

the north side of the stream and low on the south side, 

an average of the two gave concentrations close to those 

found for samples collected at the midpoint (figs. 6-10). 

Therefore, the midpoint concentrations may closely approximate those which would be found with uniform 

mixing.

Because water discharge decreased 11 percent during 

the first 28 hours of the experiment, it is probable that 

sand discharge decreased also. The suspended-sediment 

concentrations mentioned previously suggest this, but 

the concentration curve of fluorescent particles (fig. 9) 

for the 0.18-0.25-mm size range indicates in that size 

range the sand discharge was for the most part constant. 

If the sand discharge had decreased gradually during 

the experiment, the degree of tracer dilution would have 

been reduced and tracer concentration slowly increased.

For purposes of calculation it has been assumed (1) 

that the tracer concentrations found at the midpoint at 

station 3 are the same as those that would be found with 

uniform mixing and (2) that the error due to changing 

sediment discharge is small compared to other possible 

errors in the experiment. The remaining requirement, 

that is, that the concentration of tracer particles at the 

sampling point reach a constant value, was apparently 

achieved for some size fraction and not for others.

The apparent "plateau" or constant concentrations 

are shown by dashed lines in figures 6-10 and are used 

in calculating the sediment discharge in the various 

size ranges. The results of such calculations are given 

in table 2 and also in figure 13 as a cumulative curve.

The sediment discharge in each size fraction is measured independently in the fluorescent-tracer method, so 

the fact that a smooth curve results from combining the 

discharge data for several individual fractions suggests 

that there is at least internal consistency between the 

discharge estimates.

The sediment discharge calculated from depth-integrated samples is compared with that estimated by fluorescent-tracer measurements in table 2 and figure 13. 

Although the depth-integrating method measures only 

suspended load whereas the fluorescent method measures 

total load in the tracer size range, a comparison was 

made between them because no accepted reference 

method was available for this type of stream.

In the finer grain sizes one would expect the depthintegrating and fluorescent methods to agree, but in the 

coarser sizes which move near the bed, poorer agreement 

would be expected, and such is the case.

TABLE 2. Comparison of sediment discharge in Clear Creek 

calculated from depth-integrated samples and fluorescent-sand 

measurements

Sediment Discharge (metric tons per day)

Size range 

(millimeter)

0. 15-0. 18 _ __

. 18- .25 ____

.25- .30 ___.

.30- . 38_____

.38- . 52___._

From depthintegrated 

samples (A)

1.9 

7.9 

3.5 

4.2 

5.9

From "dilution" 

of fluorescent 

sand (B)

2.5 

10.0 

6.3

8.8 

13. 7

Ratio B/A

1.3 

1.3 

1.8 

2.1 

2.3

The use of a flow-through trap to collect stream sand 

in transport inevitably resulted in a tendency to concentrate more heavy minerals than light ones. This 

tendency is most evident in the finest size particles 

caught in the trap. In one set of samples, minerals heav0 0.1 0.2 0.3 0.4 0.5 0.6 

GRAIN DIAMETER, IN MILLIMETERS

FIGUBE 13. Sediment discharge in 'relation to grain size as 

determined by depth-integrated sampling and the fluorescenttracer method.
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT Ell

ier than bromoform (sp gr=2.9) were found to comprise 10.2 and 7.7 percent of the 0.15-0.18-mm and 0.18- 

0.25-mm size ranges, respectively. If it is assumed that 

no more than about 1 percent heavy minerals would be 

present in an unsorted sample of any size fraction of 

stream sand in Clear Creek, based on an estimate by 

Pettijohn (1957, p. 129) of heavy minerals in rocks, 

the revised estimate of sediment discharge from fluorescent-sand measurements would be 2.2 metric tons (2.4 

tons) per day for the 0.15-0.18-mm size range and 9.4 

metric tons (10.3 tons) per day for the 0.18-0.25-mm 

size range. This brings the estimates of sediment dis-, 

charge for the 0.15-0.18-mm size fraction by the two 

methods to within about 15 percent of each other. The 

possible errors in the two methods of measuring sediment discharge as used here may be greater than 15 

percent; therefore, one method can be said to provide 

an approximate check on the other for this particular 

size range.

EXPERIMENT WITH BATCH ADDITION

The method of continuous addition used in this experiment requires that sediment discharge remain constant long enough for the fluorescent material to mix 

thoroughly in the stream cross section and also attain a 

constant concentration at some downstream sampling 

point. If the stream is narrow and turbulent enough for 

rapid lateral mixing (vertical mixing is assumed to be 

very rapid), these requirements may be met in a reasonable time and distance. However, in many streams these 

requirements probably will not be met, and constant

concentrations at the sampling site will not be achieved 

before the sediment discharge changes significantly.

One possible way to reduce the effects of varying sediment discharge is to add one color of fluorescent sand 

(color A) at a constant known rate and also a series of 

different colors (colors B, C, D, E, etc.) of the same 

size in batches at perhaps 6-12-hour intervals. When 

batch material of color B is dumped into the stream, it 

will label the sand passing the introduction point at 

time T and, when half of that batch (or perhaps the 

peak concentration, as a rough approximation) has 

passed the sampling point downstream, the dilution factor of color A would then yield an estimate of the sediment discharge at time T at the point of tracer introduction (assuming thorough lateral mixing). A series of 

such time points should permit the calculation of sediment discharge at intermediate times by interpolation 

using concentrations of color A. If the amount of material in the batches were known and the concentration of 

color A remained constant for a suitable length of time, 

the sediment discharge could also be calculated from the 

area under the time-versus-concentration curve for 

colors B, C. D, etc. This multiple-color technique would 

be most applicable under circumstances where longitudinal dispersion was minimal.

To determine the character of the time-concentration 

curve resulting from batch addition to Clear Creek, an 

unmeasured amount of blue fluorescent sand of nominal diameter 0.30-0.52 mm was introduced 4 hours and 

16 hours after continuous introduction of the red, green, 

and yellow sand was started. Figure 14 shows the resulting concentration-versus-time curves.

500

O

o 400

- 300

EC 

o

O 200

100

EXPLANATION

Size range, in millimeters

 

0.38-0.52

 

0.30-0.38

O 

0.25-0.30

20 24 28 32 

TIME. IN HOURS

40 44

FIGUBE 14. Variation in concentration of 0.25 to 0.52-mm blue fluorescent sand at station 3 after batch addition

at station 1.
E12 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

Although the size fraction used was supposed to have 

had grains less than 0.30 mm removed, some still remained owing to incomplete sieving. Thus, the 0.25- 

0.30-mm material undoubtedly had a size distribution 

skewed far toward 0.30 mm with a median diameter of 

perhaps 0.29 mm.

Table 3 summarizes the relation of grain size to peaking time after introduction. The data suggest that there 

may be an inverse correlation between the square of 

grain diameter and the time for the peak concentration 

to move downstream to the sampling point.

TABLE 3. Time to reach peak concentration of blue grains at 

station 8 as related to grain diameter

Median Median 

Size fraction diameter diameter Time for concentration 

curve to peak (min) Ratio

0.25-0.30- ___

.30- .38-__-

.38- .52____

(A)

0.29

.34

.45

(B)

0.084

. 116

.202

Range

150-160

240-270

330-480

Average

(C)

155

255

405

0.54

.46

.50

ESTIMATION OF SEDIMENT IN ACTIVE STORAGE 

WITHIN A BEACH

The shape of the concentration-versus-time curve 

(fig. 9, for example) can be helpful in estimating the 

amount of sediment in active storage within the study 

reach. (Active storage refers to the sediment within the 

study reach which is moving on the bed or in suspension.) When a constant concentration has been achieved 

at the sampling station for a particular size fraction, 

one can assume that, for the size fraction, the concentration of fluorescent sand in sediment moving on the bed 

is the same as that in suspension. If this is so, and one 

extends a horizontal line from the constant concentration back to zero time, an area the shape of an inverted 

trapezoid or distorted triangle will be enclosed to the left 

of the rising concentration curve. This area is a measure 

of the amount of fluorescent sand that went into active 

storage in the study reach before a plateau concentration was achieved. Knowing the amount of fluorescent 

sand in active storage and its concentration there, one 

can compute the amount of nonfluorescent sand in active 

storage.

For a gravel-bed stream it is apparent that a lot of 

sand cannot be in active storage unless the stream is 

very turbulent and suspended-sand concentrations are 

very high. Clear Creek is moderately turbulent but has 

a low concentration of suspended sand; therefore, one 

would expect relatively small amounts of sand in active 

storage there. The calculated sand in active storage in 

a %-mile reach of Clear Creek is given in table 4. The 

amounts are rather small.

In a sand-bed stream, on the other hand, the quantity 

of sand moving in dunes on the bed may be very large, 

and this technique should be helpful in estimating the 

amount of sand in active storage in such streams.

If one can calculate the quantity of sand in active 

storage in a reach and knows the area of the reach, 

then the average depth of moving sand can be estimated 

(assuming that all the sand is moving on the bed). The 

average thickness for various grain sizes was found 

to be less than 1 grain diameter in Clear Creek (table 

4). In other words, if all the moving sand grains were 

rolling along the bed, only a fraction of the bed would 

be covered with sand. In fact, there was relatively little 

sand on the bed of Clear Creek; material on the bed was 

composed mainly of particles larger than sand.

One assumption implicit in the above discussion is 

that no significant amount of tracer material is lost by 

"permanent" deposition on the bed. If this is not so, the 

estimate of sediment in active storage will be too high. 

In any case, this estimate of sediment in active storage 

will be only a gross approximation unless (1) the length 

of reach required for complete lateral dispersion is small 

compared with the length of reach above the sampling 

point in which lateral dispersion is complete, or (2) the 

sediment discharge per unit width is virtually uniform 

across the stream and an average tracer concentration 

across the sampling section is used.

The fact that complete lateral mixing did not occur 

within the study reach on Clear Creek means that the 

calculated figures are somewhat in error.

TABLE 4. Sediment in active storage in Clear Creek

Size range (millimeters)

Sand in active storage Maximum depth of 

(metric tons) sand moving on the 

bed (millimeters)

0.15-0.18. 

.18- .25. 

.25- .30. 

.30- .38. 

.38- .52.

0.3

1.4

1.5 

2.5 

4.6

0.01 

.07 

.07 

. 11 

.21

OTHER POSSIBLE USES FOR FLUORESCENT SOLIDS 

IN STREAM STUDIES

The effects of specific gravity on sediment transport 

can be evaluated by coating particles of different specific 

gravities with various colored paints and determining 

their relative speed of transport. Of course, the sieve 

size and shape would have to be held as nearly constant 

as possible for the particles of various specific gravities.

An attempt to do this was made in the present study, 

but the heavy particles used were magnetic grains removed by electromagnet from Clear Creek sand, and 

they ranged from a few percent to 100 percent magnetite 

or high-iron ilmenite. The remainder of these multi-
FLUORESCENT SAND AS A TRACER OF FLUVIAL SEDIMENT E13

granular magnetic particles were commonly composed 

of quartz or feldspar, thus giving a wide range of actual 

specific gravities. The results, therefore, were quite unsatisfactory.

Shape effects can also be evaluated using an approach 

similar to that proposed for determining the effects of 

specific gravity.

Yet another potential use of fluorescent sand is that 

of determining the depth of scour in a stream bed during a rise. If fluorescent sand equal in size to the median 

diameter of the bed material were added continously 

at a point upstream from the area of interest, the sediment in transit would be labeled with fluorescent particles. As discharge decreased the labeled sediment 

would be deposited on the bed. After the flow had subsided, one could take cores of the bed sediment and 

determine the maximum depth of scour by examining 

the cores under ultraviolet light. In addition, if one 

added a series of colors in sequence during the time 

of decreasing discharge, different colored layers of 

sand would result showing the approximate time during which "permanent" deposition on the bed occurred.

CONCLUSIONS

An experiment conducted in Clear Creek at Golden, 

Colo., showed that the maximum speed of transport of 

fluorescent sand-sized particles added steadily to the 

stream correlated inversely with the square of the grain 

diameter under conditions where sand was being transported by turbulent water above a gravel bed.. There is 

a suggestion that the modal speed of transport of sand 

added to the stream in batches may show a similar relation to grain size. Lateral mixing improved with increasing grain size. Although complete lateral mixing of 

fluorescent particles did not occur, an estimate of 

sediment discharge by the fluorescent-tracer method for 

medium to fine sand showed reasonable agreement with 

sediment discharge calculated from depth-integrated 

samples after the differences inherent in the two 

methods were taken into consideration.

The results of this study suggest that much more 

effort could be profitably devoted to the use of fluorescent 

tracers in studies of sediment movement in the fluvial 

environment.

REFERENCES CITED

Aybulatov, N., Boldyrev, V., and Griesseier, H., 1961, Das 

studium der sedimentbewegung in flussen und meeren mit 

hilfe von lumineszierenden farbstoffen und radioactiven 

isotopen: Petermann's Geog. Mitt. 1. 105, no. 3, p. 177-186; 

no. 4, p. 254-263.

Bruun, P., 1965, Quantitative tracing of littoral drift, in Fed. 

Inter-Agency Sedimentation Conf., 1963, U.S. Dept. Agr. 

Misc. Pub. 970, p. 756-765.

Clayton, C. G., and Smith, D. B., 1963, A comparison of radtoisotope methods for river flow measurements, in Radioisotopes in Hydrology: Vienna, Internat. Atomic Energy 

Agency, p. 1-24.

Cummins, R. S., Jr., and Ingram, L. F., 1965, Use of radioisotopes 

in sediment transport studies, in Fed. Inter-Agency Sedimentation Conf., 1963: U.S. Dept. Agriculture Misc. Pub. 

970, p. 578-592.

DeVries, M., 1966, Applications of luminophores in sand transport studies: Delft Hydraulic Lab., Delft, The Netherlands. 

Pub. 39.

Glazov, N. V., and Glazov, A. N., 1959, New Instruments and 

methods of engineering geology: New York, Consultants 

Bureau, 91 p.

Hubbell, D. W., and Sayre, W. W., 1964, Sand transport studies 

with radioactive tracers: Jour. Hydraulics Div. Am. Soc. 

Civil Engineers, v. 90, no. HY3, p. 39-68.

Ingle, J. C., Jr., 1966, The movement of beach sand: New York, 

Elsevier Pub. Co., 221 p.

Kidson, C., and Carr, A. P., 1962, Marking beach materials for 

tracing experiments: Jour. Hydraulics Div. Am. Soc. Civil 

Engineers, v. 88, No. HY4, pt. 1, p. 43-60.

Krone, R. B., Einstein H. A., Kaufman, W. J., and Orlob, 

G. T., 1960, Methods for tracing estuarial sediment transport processes: California Hydraul. Bng. Lab. and Sanitation Eng. Research Lab., 57 p.

Lean, G. H., and Crickmore, M. J., 1963, Methods for measuring sand transport using radioactive tracers, in Radioisotopes in Hydrology: Vienna, Internat Atomic Energy 

Agency, p. 111-131.

 1966, Dilution methods of measuring transport of sand 

from a point source: Jour. Geophys. Research, v. 71, No. 24, 

p. 5843-5855.

Pettijohn, F. J., 1957, Sedimentary Rocks: New York, Harper 

Bros., 718 p.

Russell, R. C. H., 1961, The use of fluorescent tracers for the 

measurement of littoral drift: Coastal Eng. Conf., 7th, 

The Hague, Netherlands, August 1960, Proc., p. 418-444.

Teleki, P. G., 1965, A summary of the production and scanning 

of fluorescent tracers, in Fed. Inter-Agency Sedimentation 

Conf. 1963: U.S. Dept. Agriculture Misc. Pub. 970, p. 765- 

768.

 1966, Flourescent sand tracers: Jour. Sed. Petrology, v.

36, no. 2, p. 468-485. 

U.S. Inter-Agency Committee on Water Resources, 1952, The

design of improved types of suspended sediment samplers:

Washington Govt. Printing Office, Rept 6.

 1963, Determination of fluvial sediment discharge:

Washington Govt. Printing Office, Rept 14. 

Yasso, W. E., 1962, Fluorescent coatings on coarse sediments:

An integrated system: U.S. Navy, Office of Naval Research,

Geography Br., Project NR 388-057, Tech. Rept 1, 29 p.

(Columbia Univ. Dept. Geology).

 1965, Fluorescent tracer particle determination of the 

size velocity relation for foreshore sediment transport, 

Sandy Hook, New Jersey: Jour. Sed. Petrology, v. 35, no. 

4, p. 989-993.

Zerikovitch, V. P., 1958, Emploi des luminophores pour 1'etude 

du mouvement des alluvions sablonneuses: Inf. Comite Cent. 

Oceanographie Etude des Cotes, Bull. 10, p. 243-253.