A Preliminary Study of 

Sediment Transport Parameters 

Rio Puerco Near Bernardo 

New Mexico

GEOLOGICAL SURVEY PROFESSIONAL PAPER 462-C
A Preliminary Study of 

Sediment Transport Parameters 

Rio Puerco Near Bernardo 

New Mexico

By CARL F. NORDIN, JR.

SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

GEOLOGICAL SURVEY PROFESSIONAL PAPER 462-C

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington, D.C. 20402
CONTENTS

Glossary of terms___________________-__----_

Symbols ___________________________________

Abstract.._ __________________-______----_--

Introduction ___________-_-_______---------_

Purpose and scope__--_-_-_____---------

Previous investigations____________---__-

Rio Puerco drainage basin and the study reach_ 

Observed data______________________________

Page 

in

IV

Cl 

1 

1

1

2

2

Velocity distributions__ _ _ __________________

Flow resistance.-__________________________

Concentration distributions_________________

Channel bed______________________________

Extreme concentrations in ephemeral streams. 

Summary. _ _______________________________

References cited___________________________

Page

C7

9

10

15

19

20

21

ILLUSTRATIONS

FIGURE 1. Rio Puerco drainage basin._______________

2. Sketch map of study reach________________

3. Study reach, July 1961__-----------_-___-

4. Daily water discharge and concentration of 

suspended sediment, July-September 1961_

5. Variation of velocity with distance above 

streambed ____________________________

6, 7. Variation of concentration with (D-y)ly, 

station 200 6. August 19, 1961 ________

7. September 11, 1961-__---___---------

8. Variation of concentration with (D-y)/y, 

station 170, September 20, 1961 __'_______

9. Particle-size distribution from visual-accumulation-tube analysis _________________

10. Variation of fall velocity with concentration,

11. Z and Z' plotted against Zi _______________

12. Variation of apparent viscosity with temperature. _ _____________-_-_---__--___-

Page

C3

4

10

11

11

12

12

13

14

Page

FIGURE 13. General shape of viscosity curves for claywater systems with various amounts of 

added base__________________________ C14

14. Section B, showing thickness of clay-impregnated layer of bed-____-_______________ 15

15. Particle-size distribution of clay-impregnated

layer of bed and of underlying sand _____ 15

16. Cross sections defined from water-discharge 

measurements, and lateral distribution of 

bed material __________________________ 16

17. Standing waves and antidunes in reach,

September 11, 1961_____-____-_____.___ 17

18. Headcut in clay-armored bed____________ 18

19. Section B on October 5, 1961____________ 18

20. Study reach, October 5, 1961______________ 18

21. Relation of transport rate of suspended sand

per foot of width to unit discharge_______ 19

TABLES

TABLE 1. Basic data______________________________

2. Velocity distributions, ___-_--________.___

3. Concentration distribution._______________

4. Particle-size distribution of suspended sediment and bed material _________________

5. Measured and computed exponents of sediment distribution. _____________________

Page 

C5

5

6

13

TABLE 6. Partial chemical analysis of native water____

7. Mineralogical composition of suspended sediment finer than 0.004 mm, September 11, 

1961__-___--_-_----------_--__-------

8. Extreme sediment concentrations observed in 

ephemeral streams._________-__--__---_

Page 

C14

14

20

GLOSSARY OF TERMS

Bed material. Material that makes up the channel bed.

Clay. Sediment finer than 0.004 millimeters (mm), regardless of mineralogical composition.

Concentration. Sediment concentration, except where specified otherwise, is the ratio of the dry weight of 

sediment to the weight of the water-sediment mixture, expressed in parts per million (ppm). In general, 

this definition of concentration may refer to any material, dissolved or suspended, in a stream.
IV CONTENTS

Fine material. Material finer than 0.062 mm.

High concentrations. Arbitrarily taken as any concentration greater than 50,000 ppm.

Sand. "Sand" and "sand sizes" are used interchangeably to refer to sediment between 0.062 mm and 2.0 mm in

size, regardless of mineralogical composition. 

Sediment. Fragmental material that originates from weathering of rocks and is transported by, suspended in.

or deposited by water. 

Silt. Sediment between 0.004 mm and 0.062 mm in size.

SYMBOLS

	Units

a Reference distance above the bed________________________ ft

A Unit horizontal area_____________________________________ ft 2

c Concentration, in weight per unit volume_________________ Ib per ft 3

C Concentration_________________________________________ ppm

Cv Volume concentration_____________________-__________-__- 0

Ce/-\/g Dimensionless Chezy coefficient--------------------------- 0

Ci A constant-_-_-________________--_-____-__--_-__-___-_- 0

d Median diameter._______________________________________ mm

</65 Particle size for which 65 percent by weight is finer__________ mm

# Depth at a vertical____-_________________________________ ft

D Mean depth of flow at a cross section ______________________ ft

F Froude number_-_____________-_______--_________--_____ 0

g Acceleration of gravity___-____---_--_------_--_--_--_---_ fps 2

k The coefficient of turbulent exchange-__-_____--_-__-----_- 0

Kt A length parameter._____________________________________ ft

m Slope of the semilogarithmic plot of velocity versus depth above

	the streambed_______________________________________ fps

n Manning's resistance coefficient- __________________________ ft 1/6

Pj Power to overcome friction,______________________________ ft-lb per sec

Ps Power to support the sediment____-_--_-__-_-----_------__ ft-lb per sec

Ps' Power added by the sediment--_---_--_-__----__---------- ft-lb per sec

2 Discharge per foot of width__ _ ____________________________ ft 3 per sec per ft

& Transport rate of observed suspended sand_-__-________--__ tons per day per ft

R Hydraulic radius_ _______________________________________ ft

S Water-surface slope___-_____-_-____-_____________________ ft per ft

V Velocity at a point--_-__________-_-___---------------_-- fps

V Mean velocity in a cross section.__________________________ fps

F* Shear velocity__________________________________________ fps

y Distance above the streambed____-_--_--_--__--------_-__ ft

Z Computed exponent for the vertical distribution of suspended

	sediment.____________________________________________ 0

Zi Observed exponent for the vertical distribution of suspended

	sediment-____________________________________________ 0

/3 Angle of inclination between the streambed and the horizontal, degrees

7 Specific weight of water._________________________________ Ib per ft 3

7s Specific weight of sediment_ _______________________________ Ib per ft 3

em Momentum transfer coefficient-______-_--____--___-_--_-__ 0

es Sediment transfer coefficient-______________-______-_-_---_ 0

n Coefficient of viscosity.__________________________________ centipoise

w Fall velocity.___________________________________________ fps
SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

A PRELIMINARY STUDY OF SEDIMENT TRANSPORT PARAMETERS, RIO PUERGO NEAR

BERNARDO, NEW MEXICO

By CARL F. NORDIN, JR.

ABSTRACT

Preliminary findings of a study of sediment transport in 

streams with high concentrations of suspended fine sediment indicate that for the Rio Puerco near Bernardo, N. Mex., the velocity varies logarithmically with depth, and the concentration distribution for several size classes of sand may be described by 

a conventional distribution equation if the fall velocity of the 

sand is corrected for the influence of the fine sediment. A corrected fall velocity, empirically defined for a temperature of 

24° C and for concentrations of as much as about 150,000 parts 

per million, is given.

Through the period of the study, the channel of the Rio Puerco 

changed rapidly. The bed material varied from cohesive fine 

material to coarse sand. At the beginning of the study, the 

sand bed of the channel was impregnated with clay, and the clayimpregnated layer acted as an effective "armoring" which persisted for several weeks, forming a cohesive boundary for the 

flow and limiting the availability of sand for transport. For the 

last several observations, a "headcut" in the armored layer had 

progressed upstream into the study reach. The influence of the 

headcut was reflected in an increase in the water-surface slopes 

and in the concentrations of suspended sand.

Flow resistance, as measured by Manning's n, was approximately constant and was independent of the condition of the bed 

(cohesive or noncohesive) and of the average size distribution 

of the bed material.

Some observations of extreme sediment concentration are 

cited, and some of the problems involved in attempting to explain or to predict sediment transport rates for extreme conditions are discussed briefly.

The rapid changes in the channel geometry and in the characteristics of the bed material, and the extreme sediment concentrations that were observed, reflect conditions which, in general, are not described adequately by conventional sediment 

transport relations.

Observations in this report point out the extreme complexity 

of the natural processes operating in the Rio Puerco watershed 

and indicate the need for a better understanding of the factors 

controlling the flow and the sediment transport in ephemeral 

streams.

INTRODUCTION

Arid and semiarid regions are characterized by 

spectacular erosion features that have developed over 

short periods of time. Along with the erosion features, 

and equally spectacular, are the vast quantities of sediments delivered by the ephemeral streams to the major 

watercourses. Suspended-sediment loads in streams 

have been observed for many years, and something of 

the magnitude of the loads carried by the streams in 

arid or semiarid environments is known. However, 

there is little or no information on the mechanics of 

flow in streams carrying extreme concentrations of fine 

suspended material, and there exist no suitable methods 

for estimating the rates of sediment transport or for 

describinc: ~ the flow and sediment characteristics which

control the rates of transport.

This report presents preliminary findings of a study 

of sediment transport in streams with high concentrations of fine suspended sediment.

PURPOSE AND SCOPE

The purpose of this study was to investigate some 

aspects of the sediment-transport parameters and the 

mechanics of flow in streams transporting high concentrations of suspended fine material. Field observations 

were conducted on a reach of the Rio Puerco near 

Bernardo, N. Mex. The data obtained were supplemented by existing records of the Rio Puerco and other 

streams where applicable.

Specifically, the investigation included a study of 

the following: (a) Vertical-velocity distributions; (b) 

flow resistance; (c) vertical suspended-sediment concentration distributions; (d) channel-bed material and its 

effect on sediment-transport rates and related flow 

phenomena; and (e) extreme sediment concentrations.

PREVIOUS INVESTIGATIONS

The Rio Puerco in New Mexico is a notorious example of accelerated erosion, and several references to 

the channel and to the watershed are found in the literature. Bryan (1928, 1940) discussed some of the 

historical evidence of erosion in the Rio Puerco, and 

Leopold x presented some aspects of the erosion problem

1 Leopold, L. B., 1950, The erosion problem of Southwestern 

United States: Ph. D. Dissertation, Harvard University.

Cl
C2 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

over a wide area of the Southwest, including the Rio 

Puerco basin. Several reports deal with observations 

of other streams in semiarid environments, and many 

of the conclusions drawn probably apply to the Rio 

Puerco. Leopold and Miller (1956) indicated that certain hydraulic factors such as width, depth, velocity, 

and suspended-sediment load are related to the discharge as simple power functions. Schumm (1960, 

1961) related the shape of alluvial channels (the width 

to depth ratio) to the types of sediment in the bed and 

banks and suggested that the relation between the channel shape and the weighted mean percent silt-clay can 

be used as a criterion for channel stability in ephemeral 

streams.

These and many other studies provide considerable 

insight into the nature of erosion and channel morphology, but none of the references deals specifically with 

the mechanics of sediment transport. Haushild (oral 

communication, 1960) and Simons and others (1963) 

used high concentrations of bentonite and kaolin as fine 

sediments in a series of flume experiments. They found 

that the fine material had a definite effect on the viscosity and specific weight of the fluid. Changes in the 

fall velocities of the bed material, caused by the variations in the fluid properties, influenced the form of bed 

roughness, the flow resistance, and the sediment transport. Earlier studies of transportation of fine sediments were given by Hsia 2 and Kalinske and Hsia 

(1945), who related the concentration of fine sediment 

to the composition of the bed, the ratio of fall velocity 

to shear velocity, and the shear velocity Reyonold's 

number. Some limited information on velocity and 

concentration distributions for field conditions was discussed by Nordin and Dempster (1963).

RIO PUERCO DRAINAGE BASIN AND THE STUDY REACH

The Rio Puerco drains approximately 6,200 square 

miles in central New Mexico (fig. 1). The drainage 

basin is bounded on the east by the Rio Grande drainage basin, on the west by the Continental Divide, on the 

north by the Jemez Mountains, and on the south by the 

Ladrone Mountains. Altitudes in the basin range from 

4,700 feet above mean sea level near the confluence with 

the Rio Grande to about 10,000 feet near the headwaters. 

Rainfall varies roughly with altitude. The average 

annual rainfall ranges from 20 inches or more in the 

headwaters to about 10 inches over a major part of the 

basin (Dorroh, 1946).

In the past, some irrigated agriculture was practiced 

in the Rio Puerco valley. In more recent times, the 

major land use has been for grazing cattle and sheep.

2 Hsia, C. H., 1943, A study of transportation of fine sediments by flowing water: 

Ph. D. Dissertation, Iowa State University.

Over most of the watershed, vegetation is sparse, consisting mostly of pinon, juniper, and rough range 

grasses.

Large quantities of readily erodible sediments are 

available over most of the watershed. Observed suspended-sediment samples for the Rio Puerco near 

Bernardo contain, on the average, more than 50 percent clay-sized material. Clays derived from weathered 

shales, primarily the Chinle Formation of Triassic age 

and the Mancos Shale of Cretaceous age, represent the 

bulk of the sediment load carried by the Rio Puerco. At 

times the Rio Puerco also carries large quantities of 

sand, of which there is an abundant supply generally 

available for transport. Deposits of fine wind-blown 

sands are present over much of the watershed, but the 

Santa Fe Formation of middle (?) Miocene to Pleistocene ( ?) age is exposed in many places along the lower 

50 or 60 miles of the Rio Puerco and probably serves 

as a source for much of the sand transported by the 

stream. The bed material of the active channel of the 

Rio Puerco, from the Chico Arroyo to the confluence 

with the Rio Grande, is composed primarily of fine sand 

with thin layers of clay. Core drilling in the channel 

at the Rio Puerco near Bernardo, N. Mex., shows alternate layers of fine sand and clay to a depth of about 70 

feet and layers of sand and coarse gravel to greater 

depths.

The major tributaries to the Rio Puerco, the site of 

the U.S. Geological Survey gaging station near Bernardo, and the location of the study reach are shown in 

figure 1. Streamflow and suspended-sediment records 

for the Rio Puerco near Bernardo are published annually in Geological Survey Water-Supply Papers covering the hydrologic division, Part 8, Western Gulf of 

Mexico Basins.

The study reach for the observations presented in this 

report is approximately one-quarter of a mile downstream from the gaging station on the Rio Puerco near 

Bernardo, N. Mex. Figure 2 is a sketch map of the 

study reach, and figure 3 shows the reach as it appeared 

in July 1961. Section B is the site of the permanent 

cable installed for stream gaging and is approximately 

midway between the two bridges, which are about 1,900 

feet apart.

OBSERVED DATA

Field observations and sampling included the following: Measuring water discharge, water-surface slope, 

water temperature, and water velocities at several points 

in one or more verticals in the section; collecting bedand suspended-material samples; and taking photographs of the reach.
RIO PUERCO NEAR BERNARDO, N. MEX. C3

-36°

NEW MEXICO

10 5 10 20 MILES 

I

108 C

Gaging station and study reach, 

Rio Puerco near Bernardo

107°

FIGURE 1. The Rio Puerco drainage basin, showing the location of the study reach.
C4 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

Section A

Section B 

(cable)

Section C

US Highway 85 

bridge

FIGURE 2. Sketch map of the study reach.

Velocities at points in the verticals were measured 

with a Price current meter, and water discharge was 

computed. Water-surface slopes were determined by 

staff gages at sections A, B, and C, referred to the datum 

of mean sea level. Bed material was sampled with a 

BM-54 bed-material sampler, which collects material 

from the top 1 or 2 inches of the bed. Suspended sediment was sampled with a US P^6 point-integrating 

sampler or with a modified US DH-48 hand sampler. 

These samplers collect material to within about 0.3 to 

0.5 foot from the streambed.

Suspended-sediment samples were collected at several 

points in one or more verticals in the cross section to 

define vertical sediment concentration distributions. 

Depth-integrated samples collected at equal centroids 

of flowT or depth-integrated samples collected at a series 

of equally spaced verticals of the cross section were 

analyzed to determine average concentrations and 

particle-size distributions of the suspended sediment in 

the sampled zone.

Particle-size distributions of bed material and of suspended sediments wT ere determined by the pipette 

method for sizes smaller than 0.062 millimeter (Kilmer 

and Alexander, 1949) and by the visual-accumulation 

method for sand sizes (U.S. Inter-Agency Committee 

on Water Resources, 1957a).

Basic data for the hydraulic characteristics of the 

reach for the several observations in 1961 are given in 

table 1. Tables 2 and 3 show point velocity measurements and concentration distributions for various size 

classes of the point sediment samples, respectively, in

1961. All observations were at section B, and the stations shown in tables 2 and 3 correspond to the stationing of the permanent cable. Table 4 gives the average 

particle-size distributions for samples of suspended 

sediment and of bed material.

Water discharges and mean daily concentrations for 

July through September 1961 are shown in figure 4. 

Typically, the flow rose rapidly over the dry bed from 

runoff of short duration that resulted from high-intensity storms occurring upstream from the study reach. 

Discharge measurements and samples were difficult to 

obtain on rising stages because of the debris carried by 

the flow. Observations and sampling for the data in 

tables 1 through 4 were conducted during periods of 

receding flowT .

B

FIGURE 3. The study reach, July 1961. A, View upstream from section B; B, view 

downstream from section B.
RIO PUERCO NEAR BERNARDO, N. MEX. C5

TABLE 1. Basic data

[Water surface altitudes are referred to the datum of mean sea level]

Date

July 10___-_________---_-

Aug. 18_______-_____-____

Do______. ___________

Aug. 19 __ ______________

Aug. 30_________________-

Sept. 11. _____-____--_---

Sept. 20_________________

Q

(cfs)

403

31.4

636

2,380

5. 46

1,110

1,430

T ( F)

72

82

75

74

79

66

63

b (ft)

82.0

24 0

90.0

119

16.0

91

89

D

(ft)

1.71

.74

2.08

4. 47

.29

2.08

2. 48

V 

(fps)

2.88

1.76

3.40

4.46

1. 14

5. 87

6.48

s

(ft per ft)

0 000385

00073

00049

00024

00105

00122

00148

Water 

surface 

altitude

4, 730. 76

4, 731. 30

4, 734. 60

4, 731. 81

4, 731. 49

V*=^gDS 

(fps)

0. 145

. 132

. 181

. 192

.099

. 286

.344

cv/Va

=*V^g~DS

1Q Q

13. 3

18.8

23. 2

11.5

20. 5

18.9

n

(ftl/8)

0 0144

0180

0159

0140

0185

0144

0162

F

0 39

36

42

37

37

72

73

TABLE 2. Velocity distributions

Date

July 10. ____________________________

Aug. 18_ ____________________________

Aug. 19_--__--_-___- _______________

Sept. 11_____.________ _______________

Sept. 20 _ ________________________

Station

170

170

170

185

170

200

155

170

185

155

170

185

D

(ft)

2.6

2. 5

3.6

2. 6

5.8

4.8

2.6

3. 1

3.0

2. 5

3.6

3.8

A

0.3

. 3

. 5

. 5

. 5

. 5

. 5

. 6

. 5

. 5

.5

. 5

V 

(fps)

2.92

2. 86

3. 20

3.43

3. 80

4.45

4. 86 .

5.80

5. 33

4.90

7.38

6.83

V(ft)

0.7

.7

1.0

1. 1

1.0

. 8

1. 1

1. 1

1.0

1.0

1. 6

1.4

V 

(fps)

3. 28

3.43

3.88

3.97

4. 25

4.48

5.74

6. 85

5.96

5.95

9. 12

7.75

(ft)

1. 1

1. 2

2.0

1.6

2. 2

1.8

1. 6

1. 6

1. 5

1. 5

2. 6

2.5

V 

(fps)

3. 80

3. 72

4. 25

4. 15

4. 84

4. 69

6.38

7. 23

6.99

6. 76

Q 70

9. 66

V(ft)

1.6

1.7

3.0

2. 1

3.4

2.8

2. 1

2. 1

2.0

2.0

3.2

V 

(fps)

3. 97

3.97

4. 54

4. 15

5. 18

4.89

6. 85

8. 18

7.46

7.14

9.79

y (ft)

2.2

2. 1

4. 6

3.8

2. 6

2. 5

V 

(fps)

3.97

3.97

5. 18

5. 12

8.02

7. 59

The reach of the Rio Puerco near Bernardo has been 

steadily aggrading for a number of years. At the beginning of the observations in the summer of 1961, the 

sand bed of the channel was impregnated with clay to 

a depth of about 0.6 foot. This clay armoring of the 

bed persisted through the observations of July 10 and 

August 18 and 19, 1961, and was reflected in extremely 

low concentrations of suspended sands for these dates 

(table 4). For the observations on September 11 and 

20, at least a part of the bed was sand, and the concentrations of suspended sands were much higher.

Because the bed material varied from cohesive fine 

material to coarse sand with a median diameter of 0.5 

mm, the results discussed below may not be generally 

applicable to all streams carrying high concentrations 

of suspended material. Nonetheless, differences in the 

characteristics of flow and of sediment transport for 

the different bed conditions lead to some significant conclusions that should prove useful to understanding the 

mechanics of flow and the sediment transport in similar 

streams.

In the following discussion of the results of this investigation it is assumed that the flow is uniform for

240,000

200,000

2400

: 160,000

< 120,000

80,000

40,000

FIGURE 4. Daily water discharge and concentration of suspended sediment, JulySeptember 1961.

695-953 O - 63 - 2
C6 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

TABLE 3. Concentration distribution

Date

July 10..... ................. -

Do........... ................

Aug. 18 

Aug. 19 

Do 

Sept. 11 

Do........ ...................

Station

170 

170

185 

170

200

200 

170 

185

-O(ft)

2.6 

2.5

2.6 

5.8

4.8

2.0 

3.4 

3.3

Y(ft)

0.3 

.7 

1.1 

1.6 

2.2

.3

.7 

1.2 

1.7 

2.1

.5 

1.1 

1.6 

2.1

.5 

1.0 

2.2 

3.4

4.6

.5 

.8 

1.8 

2.8 

3.8

.3

.6 

1.0 

1.5

.4 

1.0 

2.2 

3.0

.4 

1.3 

2.1 

2.7

D-y

y

7.67 

2.71 

1.36 

.625 

.182

7.33

2.57 

1.08 

.471 

.190

4.20 

1.36 

.625 

.238

10.6 

4.80 

1.64 

.706 

.261

8.60 

5.00 

1.67 

.714 

.263

5.67 

2.33 

1.00 

.333

7.50 

2.40 

.545 

.133

7.25 

1.54 

.571 

.222

Concentration in parts per million, for indicated size class, in millimeters

<0.002

47,000 

41,300 

41,000 

41,800 

47,700

41,500 

41,600 

41,600 

40,800 

40, 500

95,400 

93, 300 

98, 100 

91,500

73,400 

68,600 

63,900 

68,600 

70, 200

66,800 

66,300 

66,500 

71,400 

66,400

61, 700 

62,500 

59,000 

63,000

55.900 

55,400 

70,200 

75,300

64,800 

63,900 

51,400 

82,100

0.002- 

0.004

4,310 

8,810 

9,030 

8,690 

4,670

7,530 

10,300 

8,610 

8,620 

9,240

15,700 

14,600 

10,300 

13,400

6,070 

17,000 

16,100 

13,400 

11, 400

8,980 

10,400 

13, 100 

7,730 

6,050

7,990 

6,720 

8,860 

11,100

16,300 

4,920 

14,600 

11,400

7,480 

8,260 

16,600 

9,680

0.004- 

0.008

10,900 

11,100 

10,100 

9,850 

8,120

8,340 

7,760 

9,330 

8,420 

9,240

11, 700 

13,900 

19,200 

20,500

10,800 

7,200 

13,900 

14, 800 

11,700

15,800 

13. 000 

13, 100 

11,800 

11,600

10,200 

8,360 

9,020 

4,350

8,750 

5,410 

8,320 

6,050

11, 900 

10,200 

8,320 

1,580

0.008- 

0.016

5,590 

5,160 

5,270 

5,090 

4,540

5,560 

4,380 

4,500 

4,770 

4,580

26,300 

31,500 

25,800 

20,600

19,500 

15, 900 

14, 100 

12,800 

15, 700

13,600 

13,800 

14, 100 

14, 700 

13, 500

13,300 

11,600 

12,300 

12,400

13,900 

38, 600 

13,200 

16, 400

14,400 

17,700 

17,100 

17,100

0.016- 

0.031

495 

1,170 

1,570 

1,970 

1,620

2,170 

928 

1,060 

1,500 

1,110

24,000 

21, 400 

19,200 

23,100

13, 200 

12,600 

14, 500 

13, 500 

14,400

16,000 

16,900 

14, 300 

16, 100 

17,400

21,600 

20,000 

18,000 

21,700

34,700 

10,100 

22,600 

22,000

24,800 

23,300 

24,700 

25,900

0.031- 

0.062

495 

688 

889 

475 

677

1,360 

663 

596

784 

524

3,920 

2,670 

4,630 

8,370

4,880 

6,160 

4,980 

4,580 

4,720

7,390 

6,630 

6,810 

6,420 

8,320

21,600 

26,400 

28,000 

22,400

34,300 

41,800 

40,700 

40,500

39,500 

41,800 

45,500 

32,000

0.062- 

0.125

608 

323 

287 

48 

230

502 

332 

265 

215 

203

410 

357 

391 

268

2,080 

1,930 

1,880 

1,960 

2,010

1,950 

1,780 

1,750 

1,760 

1,730

22,500 

21,100 

22,000 

20,500

50, 300 

56,800 

45,000 

39, 400

52,600 

51,700 

46,300 

38,300

0.125- 

0.25

1,220 

248 

191 

20 

95

841 

298 

192 

137 

118

344 

357 

355 

250

1,620 

1,400 

1,340 

1,200 

903

1,330 

1,210 

1,200 

1,080 

993

10,200 

6,800 

6,430 

5,590

27,200 

30,700 

16,100 

13,000

36,600 

24,300 

19, 200 

17,600

0.25- 

0.50

57

36 

18 

18 

18

424 

197 

158 

105

119 

52 

92 

26 

13

1,020 

589 

426 

97

1,700 

2,210 

231

5,930 

1,700 

926 

902

Total

70,660 

68,810 

68,360 

67,890 

67,690

67,800 

66,320 

66,160 

65,280 

65,520

178,200 

178,500 

177,500 

178,400

132,400 

131, 100 

131,400 

130, 900 

130,800

131,800 

130,200 

130, 800 

131, 200 

125, 700

170, 300 

163,600 

164,000 

161,000

243, 100 

245, 700 

236,000 

223,700

258, 00n 

242, 60X 

231,4 

225,5$

TABLE 4. Particle-size distribution of suspended sediment and bed material 

[Methods of analysis: P, pipette; W, in distilled water; C. chemically dispersed; M, mechanically dispersed; V, visual-accumulation tube]

Date

July 19. ............

Aug. 18 ......

Aug. 19 ..........

Sept. 11............

Sept. 20-. _ . ...

July 10.. ....

Aug. 18 ..

Aug. 19. ............

Sept. 11-..-..,.....

Sept. 20-... ...

Type of sample

.. do 

 do... ..................

.....do ..................

.....do... .........

 do ..................

 do ... ... ... .... .... -

 do...-.-...-.-.--......

 do .................

Water 

discharge 

(cfs)

403 

636 

2,380 

1,110 

1,430

403 

636 

2,380

1,110 

1,430

Concentration 

sample 

(ppm)

75, 800 

178, 000 

132, 000 

175, 000 

240, 000

Percent finer than indicated size, in millimeters

0.002

63.0 

50.8 

52.0 

33.6 

26.6

24.2

21.9 

11.6

0.004

73.4 

61.7 

59.2 

38.5 

30.3

28.4

25.7 

14.1

0.008

87.7 

71.0 

66.8 

41.1 

35.1

34.4

27.4 

16.4

0. 0156

98.7 

84.4 

80.5 

49.9 

42.3

39.6

31.6 

20.4

0.0312

99.2 

96.7 

92.5 

60.5 

51.8

45.3

36.2 

24.2

0. 0625

99.4 

99.6 

97.3 

75.5 

64.9

53.3

84.8 

65.6 

44.8 

29.5

0.125

99.8 

99.8 

99.1 

93.8 

88.6

70.8 

88.7 

69.3 

55.0 

43.0

0.250

99.9 

100 

100 

99.8 

99.6

92.3 

96.9 

81.1 

80.5 

68.7

0.500

100

100 

100

99.8 

99.7 

98.2 

95.1 

85.9

1.00

100 

100 

100 

99.7 

97.8

2.00

100 

99.6

4.00

"99^9"

Methods of 

analysis

VPWCM 

VPWCM 

VPWCM 

VPWCM 

VPWCM

VPWCM 

V 

V 

VPWCM 

VPWCM
RIO PUERCO NEAR BERNARDO, N. MEX. C7

the time of the observations; that the water-surface 

slope equals the slope of the energy gradient through the 

reach; and that the hydraulic radius, R, approximately 

equals the mean depth of flow, D.

VELOCITY DISTRIBUTIONS

Plots of velocity, F, against the distance, y, from the 

streambed for the various points in the verticals (fig. 

5) indicate that the velocity is proportional to the logarithm of the depth. The figure suggests that the 

velocity distribution perhaps can be described by some 

form of the von Karman-Prandtl logarithmic velocity 

equation.

The logarithmic velocity equation, as given by Kuelegan (1938) for two-dimensional open-channel flow over 

a rigid wholly rough boundary, is

2.303 _ 

T

where

t/=the distance from the streambed, in feet;

F=the velocity at the distance y from the streambed, in

feet per second; 

F*=the shear velocity = -\]gRS, in feet per second;

fc=the dimensionless coefficient of turbulent exchange; 

K,=a length parameter, describing the roughness elements on the bed, in feet; 

Ci=a dimensionless constant; 

R=the hydraulic radius, in feet;

S=the slope of the energy gradient, in feet per foot; and 

<7=the acceleration due to gravity, in feet per second 

squared.

For a sand-grain-type roughness, the length parameter, 

KS, assumes the value of the representative size of the 

sand. For uniform sands, the representative size may 

be taken as the median diameter, d ; whereas for naturally worn river sediments, the representative size is more 

closely given by the diameter for which 65 percent by 

weight of the mixture is finer, des (Einstein, 1950).

In general, equation 1 does not adequately describe 

the velocity distributions for flow over an alluvial bed. 

The values of Ks and d which are found applicable for 

flow over a rigid boundary with a sand-grain roughness, are not applicable for flow over a mobile boundary 

where there is moving sediment, even though the channel bed be plane and free from irregularities. A recent 

study of vertical velocity distribution for flow in the 

Eio Grande showed that for flow over a plane bed, if 

the constant d is assumed equal to the value 8.5 given 

by Kuelegan, the length parameter, Ks, has an average 

value of about 400 times d65 (Nordin and Dempster, 

1963). On the other hand, if there are dunes and maj or 

bed configurations in the channel, the velocity is not

proportional to the shear velocity, ^JgR8, but to some 

values less than the shear velocity (Einstein, 1950).

Eegardless of the values which Ks and d may assume, if a form of equation 1 applies for the velocity 

distributions in the individual verticals, it is possible to 

investigate the values of the von Karman coefficient of 

turbulent exchange from the observed vertical velocity 

distributions. Values of k can be computed from equation 1 as

2.303

log yi log y2 k

(2)

where FI and F2 are the velocities at distances y\ and 

7/2, respectively, and m is the slope of the velocity profile, in feet per second, and is equal to the change in 

velocity for one log cycle of depth; thus,

k=2.303 T7*

(3)

Values of k were computed for each of the verticals 

plotted in figure 5 by measuring the slope, m, of the line 

fitted by eye through the plotted points and by assuming the value of F* to be equal to -\JgDS, where D is the 

depth at the vertical. Values of m and &, so computed, 

are shown in figure 5.

Some of the velocity profiles are not well defined. 

The velocity profile for station 185 on September 20 

was influenced by violent antidunes in the section and 

probably is not suited to the determination of Tc. The 

Tc value of 0.617 for station 200 on August 19 was probably due to three-dimensional flow effects or to secondary circulation. Sayre and Albertson (1961) reported h values ranging from 0.34 to 2.77, as determined by the velocity-profile method for clear-water 

flow over isolated roughness baffles. They attributed 

the large variation in Jc to three-dimensional flow 

effects and to large-scale vortices. Nordin and Dempster (1963) showed a similar large variation in Jc for 

flow over a dune bed in the Rio Grande, where k ranged 

from 0.35 to 1.2 and was generally greater than 0.4.

The values of Jc found in the Rio Puerco appear to 

be consistent with the values reported by other investigators (Vanoni and Nomicus, 1960; Nordin and Dempster, 1963). For those dates when the channel bed was 

armored with clay, the values of Jc varied from 0.32 to 

0.62 and averaged 0.38; whereas for the observations 

when the bed was partly covered with sand and large 

quantities of sand were carried in suspension, the values 

of k varied from 0.22 to 0.31 and averaged 0.25.

Ismail (1951) suggested that sediment dampens the 

turbulence and reduces the momentum transfer, which
C8 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

10 r July 10

1.0

Sta 170

7=1.30 

A=0.316

0.1

August 18

Sta 170 ^

= 1.62 

185 / ^=0.338

= 1.18 

A=0.401

August 19

LLl

O 

m 

< 5.0 i 

LLl

O

1.0

0.1

September 11

185

k= 0.234

170

10 4 

VELOCITY, V, IN FEET PER SECOND

September 20

Sta 155

185 170

10

FIGURE 5. Variation of velocity with the distance above the streambed.
RIO PUERCO NEAR BERNARDO, N. MEX. C9

results in a reduction in k. Einstein and Chien (1954) 

and Vanoni and Nomicus (1960) correlated the reduction in k with the ratio of energy required to support 

the sediment to the energy dissipated in overcoming 

friction. According to Vanoni and Nomicus, the power, Ps, to support the sediment in a water prism with 

unit horizontal area, A, and depth, Z>, equal to the 

stream depth is

(4)

7*

in which y and ys are the specific weights of water and 

sediment, respectively; c is the mean concentration over 

the depth, in weight per unit volume; and o> is the settling velocity of the sediment. The power Pj to overcome the friction of the prism of water is

Pf=AyDVS.

The ratio of the two powers is

Pf y*yVS

(5)

(6)

The value of k was found to decrease with increasing 

values of the ratio Ps/Pf (Einstein and Chien, 1954).

The values of the ratio Ps/Pf were not computed for 

the data given in this report for two reasons. First, it 

is extremely difficult to determine what fall velocity 

should be used in equation 4 when high concentrations of 

fine material are present in the stream, due to the variable viscosity and mass density of the stream fluid; and 

second, equation 6 is not a good index to the reduction 

in k in streams transporting high concentrations of fine 

material, because the equation does not account for the 

energy added by the sediment.

According to Bagnold (1956), the sediment contributes to the total tractive force on the bed by an amount 

equal to the tangential component along the bed of the 

submerged weight of the sediment. In form analogous 

to equation 4, the power contributed by the sediment can 

be expressed as

in ft (7) 

n

where /? is the postive angle of inclination between the 

bed and the horizontal. For the small angles usually 

found in natural channels, Sin /? may be assumed equal 

to the slope, S. The ratio of the power to support the 

sediment to the power contributed by the sediment 

(equation 4 divided by equation 7) is given by

CO : vs (8)

Thus, the power added by the sediment to the flow will 

be greater than the power extracted from the flow in 

supporting the sediment when &> is less than the product 

VS. For the August 18 observation, the product 

VS=3.40X0.00049=0.00167 fps (feet per second), and 

the median diameter of the suspended material is less 

than 0.002 mm (millimeter). The fall velocity from 

Stokes' equation for a sphere with a diameter of 0.002 

mm and a specific gravity of 2.65 falling in distilled 

water at a temperature of 75° F is about 1.28 X 10~5 fps. 

The fall velocity of a similar particle in natural stream 

conditions would be even less. Thus, the energy added 

by the sediment is about 130 times as great as the energy 

required to support the sediment.

Equation 6 probably is not a good measure of the reduction in k where the energy added by the sediment is 

equal to or greater than the energy required to support 

the sediment.

If equation 8 is approximately correct, it can be seen 

that the concentration of fine sediment can be increased 

indefinitely; that is, there is no upper limit to the concentration which may be found in natural streams transporting fine materials other than the static limit imposed by some upper limiting concentration at which 

the mixture turns into a mudflow.

FLOW RESISTANCE

The overall resistance to flow, as measured by Manning's n and by the dimensionless Chezy coefficient

<?c/V<7? was determined for each of the observations in 

table 1. Excluding the two lowest discharges (August 

18, 30), the flow resistance was remarkably constant. 

Values of Manning's n ranged from 0.0140 to 0.0162 and 

averaged 0.0150. The maximum deviation from the average value was + 8 percent.

For the low discharges of August 18 and 30, values of 

Manning's n were about 0.018. The greater flow resistance may be attributed, in part, to sinuosity effects in 

the low flow channel.

Recent (1962) studies of flow resistance for the Rio 

Grande near Bernalillo, N. Mex., indicate that values of 

Manning's n vary from 0.035 to 0.012, depending upon 

the configuration of the channel bed. The average 

value of n is about 0.030 for a dune bed and 0.015 for a 

plane bed. The median diameter of the bed material for 

these observations was 0.29 mm.

The flow resistance for the Rio Puerco was comparable to the flow resistance over a plane sand bed for the 

Rio Grande. In general, bed configuration does not influence the flow resistance for the Rio Puerco except at 

low stages; most of the flows for discharges greater than
CIO SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

about 300 cfs (cubic feet per second) are over a plane 

bed.

It is significant that the resistance coefficients for the 

Rio Puerco do not seem to be controlled by the condition 

of the channel bed or by the size distribtuion of the bed 

material. There was no appreciable difference between 

the flow resistance over the clay-armored bed and the 

flow resistance over the sand bed.

CONCENTRATION DISTRIBUTIONS

The equation for sediment suspension was introduced 

by O'Brian (1933) in the form of a standard diffusion 

equation:

<aC=e, dc 

dy (9)

where ^dC /dy equals the rate of upward transfer of 

suspended sediment through turbulent exchange. Rouse 

(1937) showed that equation 9 could be integrated to 

yield an equation for the distribution of the relative 

concentration of the suspended, sediment as

Cy = (D-y a V 

Ca V y D-aJ (10)

where

Cj, = the concentration of a grain size at the distance y

above the bed, in parts per million; 

Ca =the concentration of a grain size at reference level a

above the bed, in parts per million; and 

Z the theoretical exponent of the distribution equation

given by

Z=i^r- (ID

In the derivation of equations 10 and 11, it was assumed 

that the transfer coefficient for the sediment es equals 

the momentum transfer coefficient ew.

Equation 10 plotted logarithmically is a straight line 

with a slope Z. If Values of the observed concentration 

Oy at the depth y are plotted against the values of 

(D y}/y on a logarithmic scale, the slope of the line 

through the plotted points equals Z^ the observed exponent of suspended-sediment distribution. Typical 

concentration distributions for some of the size classes 

given in table 3 are shown plotted in figures 6 through 8. 

In general, the slope, Z^ of the line which was fitted 

by eye to the plotted points is not well defined.

Values of the observed exponent Z^ usually do not 

agree with the values of Z, the computed exponent from 

equation 11. One reason for the difference is that the 

fall velocity, w, used to compute Z is usually taken as 

the terminal fall velocity of a particle falling alone in 

quiescent distilled water of temperature equal to the 

stream temperature, whereas the fall velocity in the 

actual stream may assume a value of a completely different order of magnitude.

It is impossible to determine the fall velocity of a 

sediment particle in the natural condition of a stream, 

but it is possible to determine some of the effects of the 

concentrations of fine sediment upon the fall velocity 

of the sand-size particles. Simons and others (1963) 

determined apparent viscosities of suspensions of varying concentrations of bentonite and kaolin in water and 

computed fall velocities based upon the mass densities

10

5.0

i.o

0.5

o.i

0.05

0.25-0.50 mm 0.125-0.25 mm 0.062-0.125 mm <0.002 mm Total

10 100 1000 10,000

CONCENTRATION, IN PARTS PER MILLION

FIGURE 6. Variation of concentration with (D y)ly, station 200, August 19, 1961.

100,000 1,000,000
RIO PUERCO NEAR BERNARDO, N. MEX. Cll

10

5.0

1.0

0.5

0.25-0.50 mm

0.1,-

O () () O O

0 C

0.125-0.25 mm 0.062-0.125 mm

<0.002 mm

0 C

Total

<0.062 mm

0.05

100 1000 10,000 100,000

CONCENTRATION, IN PARTS PER MILLION 

FIGURE 7. Variation of concentration with (D-y)jy, station 200, September 11, 1961.

1,000,000

10

5.0

Q

1.0

0.5

0.25-0.50 mm

0.1

0.05

0.125-0.25 mm 0.062-0.125 mm <0.002 mm

) C

Total

^<0.062 mm

100 1000 10,000 100,000

CONCENTRATION, IN PARTS PER MILLION 

FIGURE 8. Variation of concentration with (D y)ly, station 170, September 20, 1961.

1,000,000
C12 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

and the apparent viscosities of the fluids, using theoretical considerations and empirical relations given in 

Inter-Agency Committee on Water Resources (1957b). 

The computed fall velocities compared favorably with 

fall velocities determined by analyzing a sand of known 

distribution in the visual-accumulation tube, using 

suspensions of known concentrations of fine material 

as a sedimentation fluid.

The determination of the effects of concentrations of 

suspensions of fine sediment upon fall velocities using 

the visual-accumulation tube is simple. Figure 9 shows 

the particle-size distribution of a sample of sand from 

the bed of the Rio Puerco analyzed in distilled water 

(curve A) and in a suspension of fine sediment (curve 

B). The median diameter in distilled water is 0.33 mm, 

which has a standard fall velocity of 4.9 cm per sec 

(centimeters per second) at 24° C. The median diameter of the sample in the native water is 0.16 mm, which 

has a standard fall velocity of about 1.84 cm per sec. If 

values of fall velocity determined in this manner are 

plotted along the ordinate against concentrations of fine 

sediment in the sedimentation fluid, plotted on the

99.0

98

95

90

50

10

1.0 -

0.1

0.05 0.1 0.5 

DIAMETER, IN MILLIMETERS

1.0

FIGURE 9. Particle-size distributions from visual-accumulation-tube analysis in 

distilled water (curve A) and in native water with 150,000 ppm suspended sediment 

finer than 0.053 mm (curve B),

abscissa, the plotted points define a trend which is indicative of the effects of concentrations of fine material 

upon fall velocity.

Figure 10 shows the trends defined by the method described above for the geometric mean of several size 

classes of sands. The sedimentation fluids used were 

(a) suspensions of fine material (<0.053 mm) from the 

Rio Puerco in native water, mechanically dispersed; 

and (b) suspensions in distilled water, mechanically and 

chemically dispersed. The ratio of the weight of the 

dispersing agent (sodium hexametaphosphate) to the 

weight of the fine sediment was 1 to 100. Some flocculation of the clays occurred in the native water. The 

flocculation did not have any major effects on the size 

distributions for low concentrations of fine material, but 

at concentrations of about 100,000 ppm or greater the 

flocculation of the clay appeared to cause a clogging of 

the sand grains in the visual-accumulation tube. Several of the points in figure 8 with extremely low fall 

velocities are the results from analysis where the clogging occurred. No weight was given these points in 

drawing the trend lines in the figure. The fall velocity 

defined by figure 10 will be designated to'.

Values of Z', the sediment distribution exponent computed from equation 11 using </ from figure 10, show 

better agreement with Zi than do the values Z comi.o

o.i

0.01

0.001

0.0001

0.5-1.0 mm

0.25-0.5 mm

0.125-0.25 mm

0.062-0.125 mm

o 0.5-1.0 mm

 0.25-0.50 mm

-e- 0.125-0.25 mm 

(() 0.062-0.125 mm

0 100,000 200,000

CONCENTRATION, IN PARTS PER MILLION 

FIGURE 10. Variation of fall velocity with concentration.
RIO PUERCO NEAR BERNARDO, N. MEX. C13

puted using the standard fall velocities, o>. Computations of values Z andZ' for given dates in 1961 are 

given in table 5, and values of Z and Z' are plotted 

against Zi in figure 11.

As might be expected, there is considerable scatter in 

the relation of Z' to Za . Part of this scatter may be 

attributed to variations in the stream temperature, 

which ranged from 17° C to 24° C. The relation of 

fall velocity to concentration was defined for only one 

temperature, 24° C, and was applied to all the Z values 

regardless of the temperature of the stream.

The effect of temperature on the fall velocities for a 

given sand size and concentration of fine material was 

not defined from the data in this investigation. However, something of the magnitude of the temperature 

effects may be indicated. Figure 12 shows the variation of the apparent viscosity with temperature of dispersed fine sediments in native water for the Rio 

Puerco near Bernardo, N. Mex., for a range of temperature from 2° C to 40° C at a constant concentration of 

127,000 ppm. The apparent viscosities were determined with a Stormer Viscometer. Simons and others 

(1963) found that for a given fine material dispersed in 

distilled water, the ratio of the viscosity of the dispersion to the viscosity of water was independent of temperature. Therefore, some of the scatter in figures 10 

and 12 probably is due to variations in viscosity of the 

dispersions other than the variations caused by concentration and temperature.

Other major factors which influence the viscosity of 

a clay-water system are the mineralogical composition 

of the clay, the nature and amount of adsorbed ions, 

and the electrolytes present in solution (Houwink, 

1952).

Partial chemical analyses of the native water of the 

Rio Puerco for two of the observation dates in 1961 are 

given in table 6. The mineralogic composition of the 

suspended sediment finer than 0.004 mm for September 

11,1961, is shown in table 7. This information was fur2.0 3.0

2.0 3.0

FIGURE 11. Z and Z' plotted against Z\.

nished by Mr. V. C. Kennedy, U.S. Geological Survey, 

Denver, Colo. (oral communication, 1962). The cation 

exchange capacity for this sample was not available for 

this report. Without knowing the exchange capacity, 

it is impossible to predict the effects of the chemical 

constituents in the native water upon the properties of 

the suspension.

Because illite and montmorillonite plus mixed-layer 

clay constitute more than 50 percent of the clay-sized 

material, it is assumed that the exchange capacity is 

high and that the chemical constituents of the native 

water have considerable effect upon the properties of 

the suspension.

The general shape of the viscosity curves for claywater systems with various amounts of added base is 

shown qualitatively in figure 13. Where both monovalent and divalent ions are present (table 6), the 

general shape of the viscosity curve would probably 

fall somewhere between the extremes shown in figure 13.

TABLE 5. Measured and computed exponents of sediment distribution

Date

July 10 

Aug. 18 

Sept. 11- .

Station

170

170

185

170

200

200

170

185

D

(ft)

2.6

2.5

2.6

5.8

4.8

2.0

3.4

3.3

(fps)

0.179

.176

.205

.192

.402

.383

ft

0.317

.316

.401

01 Q

.617

.23

010

.287

r

(°C)

22

22

24

23

23

19

17

17

w, in feet per second

0.062

-0.125

(mm)

0. 0226

.0226

.0233

.0230

.0230

.0203

.0203

0.125

-0.25

(mm)

0. 0669

.0669

0684

.0684

0633

AfioO

.0623

0.250

-0.50

(mm)

0.174

.172

.172

.163

1 KQ

.159

a', in feet per second

0.062

-1.25

(mm)

.005

.00066

.0017

0007

AftA»>

.0002

0.125

-0.25

(mm)

0.034

.034

.021

.014

.0077

.0077

0.250

-0.50

(mm)

0.052

.070

.070

.034

.034

Zi

0.062

-0.125

(mm)

0.48

.22

.14

0

.02

AQ

.10

.10

0.125

-0.25

(mm)

0.82

.51

.20

.10

.20

.21

.20

0.250

-0.50

(mm)

0.36

.47

.67

.62

.52

z^/*n

0.052

-0.125

(mm)

.406

.283

340

.195 091

.185

0.125

-0.25

(mm)

1.18

1.20

.580

QQO

498

.566

0.250

-0.50

(mm)

2.12

2 54

1.46

2 CO

1.27

1.45

z^/tv.

0.062

-0.125

(mm)

0.088

.090

nor:

.014

.011

002

.002

0.125

-0.25

(mm)

0.600

.612

.170

01 1

.178

.217

AGO

.070

0.250

-0.50

(mm)

0.63

1.04

.593

.807

979

.309
C14 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

VISCOSITY, n, IN CENTIPOISE 

FIGUEE 12. Variation of apparent viscosity with temperature for dispersed fine sediment in native water, Rio Puerco near Bernardo. N. Mes.

TABLE 6. Partial chemical analysis of native water

Date

July 10...........

Sept. 11 ............

Specific 

conductance (micromhos 

at 25°C)

3,050 

1,730

pH

7.2 

7.3

Concentration (parts per million)

Total

2,200 

1,270

Ca

198 

158

Mg

36 

17

Na

473

K

15

Na+K

228

TABLE 7. Mineralogical composition of suspended sediment finer 

than 0.004 mm, September 11, 1961

Material Percent

Amorphous material-..___-______________ 2-3

Kaolinite (hydromica)_________________ 25-30

Illite______ _____________________________ 10-15

Montmorillonite plus mixed-layer clay____ 40-45

Quartz _________________________________ 9-12

Calcite. _ _______________________________ 2-3

Previous records show appreciable variations in the 

concentrations of the chemical constituents in the Eio 

Puerco flow. The physical properties of the fine sediments such as the color, size distribution, and plasticity are known to vary, depending upon the source of 

the sediment. It may be assumed that the mineralogical composition of the material finer than 0.004: mm 

also varies. Obviously, on the Bio Puerco the clay-water 

systems become extremely complex, and the viscosities

of the dispersions cannot be predicted with any degree 

of certainty. It is generally conceded that the effects 

of the factors influencing the viscosity of heterogeneous 

fluids containing ionized particles are beyond explanation at the present time (Houwink, 1952).

So far as sediment transport is concerned, the effects 

of fine material upon the fall velocities and concentration distributions of sand-sized particles must be defined 

from empirical relations, such as those in figures 10

Viscosity

Monovalent ions such as 

Li, Na, and K

Divalent ions such 

as Ca and Mg

Added base

FIGURE 13. General shape of the viscosity curves for clay-water systems 

with"various amounts of added base. From Simons and others (1963).
RIO PUERCO NEAR BERNARDO, N. MEX. C15

and 12. As shown by figure 11, these empirically defined 

relations cannot be expected to yield accurate results. 

From a practical viewpoint, however, it is probably 

not necessary to determine accurately the concentration 

distributions in streams such as the Rio Puerco, because 

the total concentration distribution is so nearly uniform 

through a vertical that samples taken anywhere in the 

vertical give a reasonable representation of the average 

concentration and particle-size distribution of the sediment transported by the stream. From figures 6 through 

8 and table 3, it can be seen that in almost all instances 

the slope of the line through the points representing 

total concentrations is not much different from the slope 

of the line through the points for the very finest fraction. (Some of the fine fractions show a reverse concentration gradient; that is, the concentration appears 

to be greater near the surface than near the bed. This 

is probably due to errors inherent in the sampling and 

laboratory procedures.) Also, the total concentration 

distribution depends to some extent upon the concentrations of sands in the flow; as will be shown in the 

next section, the concentration of the sands is unpredictable over a considerable range of conditions.

CHANNEL BED

The characteristics of the channel-bed material effect 

both the flow and the sediment transport. 

When this investigation began in July 1961, the sand

bed of the channel was impregnated with clay to a depth 

of about 0.6 foot (fig. 14). Analyses of core samples 

for particle-size distribution showed the clay-armored 

layer to have a median particle diameter of 0.067 mm 

and to contain about 50 percent sand, 23 percent silt, 

and 27 percent clay. The underlying sand contained 10 

percent fine material and had a median particle diameter of 0.20mm (fig. 15).

CABLE STATION, IN FEET

240 200 160 120

Left 

4735,- bank

>

§4730 

<

Right 

bank;

Clay-impregnated layer of bed /

4725

FIGUEE 14. Section B, showing the thickness of the clay-impregnated layer of the

bed.

10

0.001 0.005 0.01 0.05 

DIAMETER, IN MILLIMETERS

FIGUBE 15. Particle-size distribution of the clay-impregnated layer of the bed (curve A) and of the underlying sand (curve B).
C16

July 10

August 18

August 19

September 11

September 20

SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

CABLE STATION, IN FEET

240 200 160 120

Left 

bank

4735

4730

August 19

Station 222

Station 225

176 163 140

Silt and clay 

</= 0.048 mm

Sand 

</=0.21 

mm

Clay 

0K0.002 mm

135

Silt and clay 

(85 percent <0.062 mm)

Station 241 176 163

Station 224

Station 224

200 158 133

Clay and silt 

</= 0.005 mm

Sand 

</= 0.23mm

Fine sand 

d- 0.066 mm

205 180 160 135

Clay 

c/<0.002 mm

Sand 

^=0.16 mm

Sand 

^=0.52 mm

Silt and clay 

d= 0.008 mm

FIGURE 16. Cross sections defined from water-discharge measurements, and lateral distribution of bed material, 1961.

Right 

bank

. . . __. . _ . __ September 11 

September 20 

August 18

122

Silt and clay 

(74 percent <0.062)

Sand 

</=0.29 

mm

Clay 

</= 0.002 mm
RIO PUERCO NEAR BERNARDO, N. MEX. C17

The conditions which caused the bed to armor are not 

known. Probably, the armoring was the result of a 

combination of (a) the deposition of sand, silt, and clay 

during receding flows; and (b) the infiltration of flow 

into the channel bed, carrying clay into the pore spaces 

between the sand grains. The clay served as a matrix 

to bind the top few inches of the bed when the material 

dried.

Streamflow records show that the July and August 

flows originated above the confluence of the Rio Puerco 

and the Chico Arroyo. From the extremely low concentrations of suspended sand in these flows (table 4), it is 

concluded that the channel bed was armored through 

the entire 100-mile reach. Thus, although there are vast 

quantities of sand in the Rio Puerto watershed, under 

some conditions this sand is not available for transport.

Figure 16 shows the cross sections of the channel defined from the water-discharge measurements. The bar 

graphs plotted below the cross sections give an indication of the bed material across the wetted perimeter at 

the time of the observations. The graphs were constructed from the size analyses of the individual samples 

of bed material collected with the BM-54 sampler. The 

stations listed at the top of each bar graph indicate the 

approximate boundaries of the different types of bed 

material. The graphs show, for example, that on July 

10, 1961, sand with a median particle diameter of 0.21 

mm was present on the bed of the channel between stations 163 and 176, whereas on August 18, the entire 

wetted perimeter (station 135 to station 225) was covered with silt and clay. The average size distribution 

of the bed material is given in table 4. Of special interest are the wide variations in the size distributions 

of the bed material and the presence of the coarse sand 

(d=0.52 mm) on September 20.

Trains of standing waves were present through the 

reach during both of the September observations (fig. 

17); on September 20, violently breaking antidunes were 

noted. The coarse sand was found on the bed in the area 

of the channel where trains of these waves were forming, breaking, and reforming at regular intervals of 

about 2 to 3 minutes. Standing waves were not observed 

to form over the clay-impregnated bed.

During July through September, the period of these 

observations, the channel of the Rio Puerco was undergoing relatively rapid changes. A "headcut" in the 

clay armoring of the bed, commencing at the confluence 

of the Rio Puerco and the Rio Grande, had progressed 

upstream by August 19 to the bridge at U.S. Highway 

85. On August 30, it was about 50 yards downstream 

from the cable (fig. 18). There was no evidence from 

the cross sections in figure 15 to indicate that the headcut had moved upstream from section B on September

A

B

FIGURE 17. Standing waves and antidunes in the reach, September 11,1961.

11 or 20. Probably, the headcut was upstream from 

section B, and the cut channel had refilled with sand. 

There was no discontinuity in the water-surface profile 

to indicate the presence of the headcut, because at discharges greater than about 300 cfs, the plunge pool 

would drown out. Figure 19 shows the cross section 

of the channel measured under the cable on October 5, 

1961. On this date the headcut was upstream from the 

old Highway 85 bridge. In the channel above the headcut the bed was still armored with clay; in the cut channel the bed material was composed of sand with a 

median diameter of 0.35 mm. The core samples taken 

prior to the headcut showed the material at the same 

elevation to have a median diameter of about 0.2 mm, 

hence there was an appreciable change in the bed material as the headcut moved upstream.

The presence of the headcut in the study reach is reflected in the increased water-surface slopes for the 

September observations. The cut channel through the 

reach was uniform in cross section, averaging 25 feet 

wide and 3 feet deep (fig. 20). Changes in the channel
CIS SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

FIGUEE 18. Headcut in the clay-armored bed.

geometry induced by the headcut can be seen by comparing the plotted cross sections (figs. 16,19), and from 

the appearance of the reach preceding and after the 

headcut (figs. 3, 20). The headcut exposed numerous 

deposits of clay balls, which have been described in 

detail elsewhere (Nordin and Curtis, 1962).

Headcuts and discontinuous gullies are characteristic 

of streams in semiarid environments, and although the 

changes in the channel reported here are more intense 

than those that have been observed for this reach in the 

past, these phenomena are not unique. In fact, such 

changes are to be expected in streams such as the Bio 

Puerco. Some of the conditions necessary for the formation of discontinuous gullies and headcuts were dis240 

I

CABLE STATION, IN FEET

200 160

I . . . I

120

_I

Left 

4735r- bank

§ 4730

4725

Right 

banky

FIGURE 19. Section B on October 5,1961.

B

FIGUEE 20. The study reach, October 5, 1961. A, View upstream from section B; 

B, view downstream from section B.

cussed by Leopold and Miller (1956) and by Schumm 

andHadley (1957).

It is beyond the scope of this study to discuss channel morphology, but the observations given above emphasize the complexity of the natural processes operating in the Bio Puerco watershed and indicate the urgent 

need for a better understanding of these processes.

In terms of sediment-transport parameters, the observed changes in the channel of the Bio Puerco are 

reflected in the geometry of the cross section, the hydraulic characteristics of the reach, the nature of the 

boundary (cohesive or noncohesive) the composition 

of the bed material, and the availability and, hence, the 

concentration and size distribution of the suspended 

sediment.
RIO PUERCO NEAR BERNARDO, N. MEX. C19

EXTREME CONCENTRATIONS IN EPHEMERAL 

STREAMS

Streams with high concentrations of fine sediment 

have a tremendous capacity for transporting sand. 

Figure 21 shows the relation of the transport rate of 

suspended sand per foot of width, qs , to unit discharge, 

<?, for the Rio Grande near Bernalillo and for the Rio 

Puerco. The concentrations of fine sediment in the Rio 

Grande were relatively low about 500 to 1,000 ppm. 

The slope of the Rio Grande is approximately 0.001, or 

about the same as the slope of the Rio Puerco. For a 

given unit discharge, the Rio Puerco may transport 10 

or more times as much sand as the Rio Grande, pro10,000

Jo 1000

LJ

> cc

CC LJ LU CL

V)

CO >

O cc

LJ 

LJ Q_ is ^

2?

CO

< 

cc

100

10

 / * Relation for the Rio Grande 

' n near Bernalillo, N Mex

o

 Rio Puerco

4> Rio Puerco (this study)

O Rio Grande near 

Bernalillo, N Mex

I_______________

1 10 100

UNIT DISCHARGE, g, IN CUBIC FEET PER SECOND 

PER FOOT OF WIDTH

FIGURE 21. Relation of the transport rate of suspended sand per foot of width to 

unit discharge.

vided the sand is available for transport. Note that 

the points for the July and August observations, when 

the bed was armored and sand was not available, plot 

along the line for the Rio Grande.

The increased transport capacity for streams such as 

the Rio Puerco is partly due to the increased viscosity 

and mass density of the transporting media and to the 

reduced fall velocity of the sand particles. Presumably, at sufficiently high concentrations of fine material, 

the fall velocities of the sand would be so reduced that 

the rate of sand transport would be similar to the transport of fine material; that is, the transport rate would 

be limited either by the availability of the sand or, at 

the upper limit, by the concentration at which the sand 

particles are in actual contact. Again, as in the instance 

of fine sediment with extremely low fall velocities, the 

upper limit would be a "mudflow."

Bagnold (1956) gave a volume concentration, Cv , of 

0.6 as the upper limiting "fluid" concentration of uniform spheres in a Newtonian fluid; at higher concentrations the mixture behaved as a granular paste. "Volume concentration" is defined as the grain-occupied 

volume divided by the total volume. For a specific 

gravity of 2.65, the volume concentration of 0.6 equals 

a concentration by weight of 800,000 ppm. Probably 

the upper limiting "fluid" concentration for sediments 

in natural channels should be of this same order of 

magnitude. Documentation of such high concentrations 

in natural streams has not been accomplished. The 

highest recorded concentration appears to be 680,000 

ppm for the Rio Puerco, reported by D. C. Bondurant 

(1951). About 75 percent of the sample was sand. 

(See Lane and Borland, 1954.) Some examples of high 

concentrations determined from samples collected with 

standard U.S. Geological Survey sampling equipment 

are given in table 8 (J. P. Beverage, oral communication, 1962).

Obviously, to be applicable in streams transporting 

such high concentrations of suspended sediment, the 

conventional transport equations require considerable 

modification. This study has shown that the velocity 

follows a conventional logarithmic distribution with 

depth; and for the range of sizes and concentrations 

considered, the concentration distributions may be described by equation 10 if the fall velocity is corrected 

for the effects of the fine sediment. Simons and others 

(1963) concluded from their flume experiments that 

the total transport rate can be predicted if, where fine 

sediment is involved, the concentration of fine sediment 

is determined by sampling and the effects of fine sediment on the properties of the stream liquid are taken 

into account. In Simons' experiments, the highest
C20 SEDIMENT TRANSPORT IN ALLUVIAL CHANNELS

TABLE 8. Extreme sediment concentrations observed in ephemeral

streams

Station

Mex.

Mex. 

Paria River at Lees Ferry, Ariz

Little Colorado River at Cameron, Ariz.

Date

Aug. 6, 1951

July 22, 1954 

July 24, 1949

Aug. 27, 1952

Aug. 26, 1954 

Oct. 8, 1954 

Aug. 4, 1961

.. ..do..... ...

Aug. 20, 1957

Aug. 25, 1957

Discharge 

(cfs)

1,080

408 

435

3,080

Concentration 

(ppm)

414,000

327, 000 

418, 000

646, 000

468, 000 

427, 000 

596,000

451,000

620, 000

299, 000

Concentration of 

sand (ppm)

131, 000 

117,000

300, 000 

205, 000 

447, 000

262, 000

111,000

total concentration was 102,000 ppm, of which 50,000 

ppm was sand. It is probable that at the high concentrations given in table 8, the presence of the sand as 

well as the fine material will influence the properties 

of the fluid, and additional studies are needed to determine the combined effects of a wide range of sizes on 

fluid properties.

When extreme concentrations of sand, say 300,000 

ppm or more, are present in a stream, fall velocities 

probably have no meaning. It is difficult to visualize 

how turbulence, if it existed at all, could be an effective 

mechanism in supporting the sediment. A more plausible explanation has been advanced by R. A. Bagnold 

(1954), who postulated a dispersive stress arising from 

the mutual encounters between the grains. Bagnold 

was able to measure this stress for dispersions of uniform, solid, spherical grains sheared in Newtonian 

fluids in the annular space between two concentric 

drums, and he applied the results to predict the velocity 

of dry sand flowing down an inclined slope and to explain an observed gravel flow. The case of heterogeneous grains sheared in a non-Newtonian fluid, such as a 

clay-water system, has not been investigated. Simons 

and others (1963) discussed the applicability of the 

Bagnold shear and transport functions (Bagnold, 1956) 

for concentrations of as much as 102,000 ppm.

It should be emphasized that most extreme concentrations in natural streams are observed during rapid 

changes in stage and in concentration. Under these 

conditions, the assumptions of uniform flow and of 

an equilibrium relation between a shear and a transport 

function become untenable, and a sediment-transport 

rate cannot be predicted.

If the bed is armored or partly armored with clay, 

equilibrium transport rates cannot be predicted, because 

the transport of sand would be controlled by the availability of the sand, and because there exist no methods 

for describing an equilibrium condition between flow 

parameters and a cohesive bed.

SUMMARY

This report presents some limited findings for an investigation of sediment transport in the Bio Puerco 

near Bernardo, N. Mex.

The velocity of sediment transport in a vertical varies 

logarithmically with depth, and the concentration distribution for the geometric mean of several size classes 

of sand can be described by a conventional distribution 

equation if the fall velocity of the sand is corrected for 

the influence of fine sediment. Flow resistance, 

measured by Manning's n. is approximately constant 

and is independent of the condition of the bed (cohesive 

or noncohesive) and of the average size distribution of 

the bed material.

Through the period of this study, the channel of the 

Kio Puerco was undergoing some relatively rapid 

changes. At the beginning of the study, the bed of 

the channel was armored with a layer of sand, silt, and 

clay about 0.6 to 1.0 foot thick. This layer contained 

about 25 percent clay, which served as a matrix to bind 

the material. A headcut in the clay-impregnated layer 

of the bed moved upstream into the study reach and 

resulted in changes in the channel geometry and in the 

composition of the bed material. The bed material 

ranged from a cohesive fine material to a coarse sand. 

When the bed of the channel is composed of cohesive 

material, the availability of sand for transport is 

limited; and the standard equations for predicting the 

rate of sediment transport are not applicable.

Some observations of extreme sediment concentrations 

indicate concentrations of sand ranging from 117,000 

to 447,000 ppm. Conventional sediment transport relations generally are not applicable for extreme conditions, because most high concentrations occur for 

periods of rapidly changing stage, and because the 

effects of high concentrations of sand upon fluid properties have not been defined.

Finally, the data presented herein point out the complexity of the natural processes that are operating in 

the Rio Puerco watershed and indicate the need for 

additional study of sediment transport and related flow 

phenomena in ephemeral streams transporting high 

concentrations of suspended sediment. Further investigations should be oriented to provide information on 

the following:

1. The effects of the physiochemical properties of the 

fine material upon fluid properties.

2. The relation of the source of sediment to the physiochemical properties of the fine sediment and to the 

chemical quality of the water.

3. The effects of high concentrations of sand upon fluid 

properties.
RIO PUERCO NEAR BERNARDO, N. MEX. C21

4. The conditions which lead to the armoring of the bed.

5. The conditions which influence the cycle of deposition and incision in existing channels.

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U.S. GOVERNMENT PRINTING OFFICE: 1963 O 695-953