RC.2058

GEOLOGICAL SURVEY CIRCULAR 205

INVESTIGATIONS OF 

FLUVIAL SEDIMENTS OF THE 

NIOBRARA RIVER NEAR 

VALENTINE, NEBRASKA

By B. R. Colby, D. Q. Matejka, and D. W. Hubbell
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

GEOLOGICAL SURVEY CIRCULAR 205

INVESTIGATIONS OF FLUVIAL SEDIMENTS OF THE NIOBRARA RIVER

NEAR VALENTINE, NEBRASKA

By B. R. Colby, D. Q. Matejka, and D. W. Hubbell

Prepared as part of a program

of the Department of the Interior for

development of the Missouri River Basin

Washington, D. C., 1953

Free on application to the Geological Survey, Washington 25, D. C.
CONTENTS

Abstract ----------------- _-__-__

Introduction - --- - 

River channel - - - --- -- 

Measuring sections _____ __ 

Contracted section - - -

Normal sections - - - - 

Sections at Sparks gaging station - 

Daily water and sediment discharges - 

Page 

i

1

2

2

2

23

Measured slopes of the water surface -

Distribution of sediment in section B

Particle size --- _____ 

Analyses of suspended sediment -

Analyses of bed material 

Unmeasured sediment discharge 

Conclusions - _____ -_ 

Tables - --- -- - --

Page 

23 

23 

23 

23 

31 

31

ILLUSTRATIONS

Figure 1. Sketch map of the Niobrara River near Valentine and Sparks, Nebr - - 2

2. Looking upstream toward the contraction of the Niobrara River formed by bank

caving ---- - ___ __ ____ __ ___ ____ __ - __ 3

3. Looking downstream from the upper end of the contracted channel - -- - -- 3 

k. Footbridge where samples were taken to determine total sediment discharge of the

river section B ---- ____ _____ _ __ ______ _____ _ k

5. Sketch map showing location of sampling sections of the Niobrara River above

Buffalo Bridge, near Valentine, Nebr ---- ____ _ _ ___ _ _ £

6. View of section A_' from right bank - --- --- -- -- 5

7. View of section £ from left bank -- 6

8. View of channel at section D 1 from left bank _____ ____ __ 6

9. View of bridge section, Sparks gaging station - --__ _ - -- 7

10. View of wading sections^ Sparks gaging station - - - ----- 7

11. Lateral distribution of depth, velocity, and concentration of suspended sediment,

section A, Niobrara River near Valentine -- --- - - 9

12. Lateral distribution of depth, velocity, and concentration of suspended sedimdnt,

section A' , Niobrara River near Valentine - - ---- - ----- 10

13-l5« Lateral distribution of depth, velocity, and concentration of- suspended sediment,

section B, Niobrara River near Valentine - -- - - 11

l6-l8. Lateral distribution of depth, velocity, and concentration of suspended sediment,

section £, Niobrara River near Valentine -- -- ---- - -- li|

19. Lateral distribution of depth, velocity, and concentration of suspended sediment,

section D 1 , Niobrara River near Valentine - - --- 17

20. Lateral distribution of depth, velocity, and concentration of suspended sediment,

section D, Niobrara River near Valentine - -- - - - 18 

21-22. Lateral distribution of depth, velocity, and concentration of suspended sediment,

bridge section, Niobrara River near Sparks - - --- - - - -- 19 

23. Lateral distribution of depth, velocity, and concentration of suspended sediment,

wading sections, Niobrara River near Sparks - ---_ --- - _____ 21 

2i|. Lateral distribution of depth, velocity, and concentration of suspended sediment,

wading section, Niobrara River near Sparks - - -- - --- 22

25. Rating curve for the Niobrara River above Buffalo Bridge, near Valentine 2i|

26. Water-sediment discharge curve for the Niobrara River near Sparks - -- - ---- 25

27. Vertical distributions at section B, Nov. 30, 1950 26

28. Vertical distributions at section B, Dec. 7, 1950 27

29. Vertical distributions at section B, Dec. 21, 1950 28

30. Vertical distributions at section B, May 8, 1951 29

31. Vertical distributions at section B, June 28, 1951 30

32. Particle-size analyses of suspended sediment, section A, Niobrara River near

Valentine 32

33. Particle-size analyses of suspended sediment, section A 1 , Niobrara River near

Valentine 32 

3U-36. Particle-size a'nalyses of suspended sediment, section B_, Niobrara River near

Valentine 33 

37-38. Particle-size analyses of suspended sediment, section C_, Tfiobrara River near

Valentine -- -- _____ _- _ -___ _ _ ___ %k

39. Particle-size analyses o£ suspended sediment, section D', Niobrara River near

Valentine 35

i|0-I).3. Particle-size analyses of suspended sediment of the Niobrara River near Sparks 36 

'[ -J|7« Particle-size analyses of bed material of the Niobrara River near Valentine - 38 

'.9. Particle-size analyses of bed material of the Niobrara River near Sparks i|0

iii
TABLES

Table 1. Discharge measurements of the Niobrara River above Buffalo Bridge, near Valentine,

Nebr., during the year ending Sept. 30, 1951 --- -- ---- ____ -__ jjjj.

2. Discharge measurements of the Niobrara River near Sparks, during the year ending

3. Sediment discharge measurements of the Niobrara River near Valentine (contracted 

i|. Sediment discharge measurements of the Niobrara River near Valentine (normal

5. Sediment discharge measurements of the Niobrara River near Sparks - --- -- LJ.7

6. Comparison of suspended-sediment concentrations of measuring sections of the

Niobrara River near Valentine and Sparks, from Nov. 2, 1950, to July 17» 1951 --- ij-8

7. Suspended-sediment concentrations at cross sections of the Niobrara River near

Valentine and Sparks, from Nov. 2, 1950, to July 17> 195l» in average percentage

of the concentration at the contracted section B - -- _--- _-_ _____ £o

8. Daily suspended-sediment discharge of the Niobrara River near Valentine, section B,

and near Sparks, 1950-51 water year - - ______________ __ ____ _________ £o

9. Slope observations on the Niobrara River near Sparks ---_-_- - ____________ £o

10. Particle-size analyses of suspended sediment (point-integrated samples), Niobrara

River near Valentine, section B, 1950-51 water year - --- --- _____ _ 51

11. Particle-size analyses of suspended sediment, Niobrara River near Valentine,

section B, 1950-51 water year ___-_--_______ ________ __ _____ ___ __ __ £[|

12. Particle-size analyses of suspended sediment, Niobrara River near Valentine,

normal sections, 1950-51 water year -- -- _----_-__-_--_--____--_-_--- 55 

13« Particle-size analyses of suspended sediment, Niobrara River near Sparks, 1950-51

li|. Particle-size analyses of bed material, Niobrara River near Valentine, normal

15. Particle-size analyses of bed material, Niobrara River near Sparks - --- - 57

iv
INVESTIGATIONS OF FLUVIAL SEDIMENTS OF THE NIOBRARA RIVER

NEAR VALENTINE, NEBRASKA

ABSTRACT

This report contains results of observations that were made from the time when a natural constriction was formed in the Niobrara 

River near Valentine, Nebr., to the time when 

it was widened by high flows. After the constriction was widened, insufficient turbulence was developed to suspend most of the 

sediment. The report gives information on the 

amount and characteristics of the sediment 

that moves as unmeasured load at normal sections of the stream near the constriction and 

at the measuring sections at the Sparks gaging station.

Lateral distributions of depth, velocity, 

and concentration are shown for the sections 

where sediment discharge was measured. In addition, vertical distributions of concentration, velocity, and percentage of particles 

coarser than 0.25 mm are shown for the contracted section. The vertical distributions 

seem to indicate that the total sediment load 

of the stream was usually in suspension at the 

contracted section. Exclusive of the period 

during the winter when upstream reservoirs . 

were not flushed, the measured discharge of 

suspended sediment at the normal sections near 

the contraction averaged I).? percent and at the 

Sparks gaging station l[l percent of the measured sediment discharge at the contracted section.

Particle sizes of suspended sediment and bed 

material are tabulated, and some size distributions are plotted. In conformity with bedload theory, the computed particle sizes of 

the unmeasured load we.re slightly smaller than 

the average particle sizes in the samples of 

bed material.

INTRODUCTION

An investigation of sediment transport within a reach of the Niobrara River on the Port 

Niobrara National Wildlife Refuge near 

Valentine and Sparks, Nebr. (fig. l),was 

undertaken by the U. S. Geological Survey at 

the request of and in cooperation with the 

U. S. Bureau of Reclamation. This investigation to determine water and sediment discharges in and near a' contracted channel was 

made as a part of the Department of Interior 

program for the development of the Missouri 

River basin. The contracted channel was formed 

about October 1, 1950, when bank caving constricted the low and medium flows of the 

Niobrara River east of Valentine to a chute

about 30 ft wide. (See fig. 2.) During the 

period November 2 to 17, measurements relating 

to stream flow, suspended sediment, and bed 

material were made in the chute, at nearby 

sections, and at the gaging station near 

Sparks. On November 17, 1950 » a. meeting of 

representatives of the Bureau of Reclamation 

and of the Geological Survey was held to discuss future operations of the investigation. 

At this meeting the scope of the field work 

was limited to observations at the contracted 

section and at the Sparks gaging station. A 

similar meeting was held on May 8 and 9, 195l» 

at which time the investigation was expanded 

to include again the collection of data on 

stream flow, suspended sediment, and bed material at the previously investigated sections 

near the chute. However, two of these former 

sections were replaced by more completely 

alluvial sections.

The part of the investigation carried on by 

the Geological Survey was under the supervision of P. G. Benedict, regional engineer, 

Quality of Water Branch, and R. B. Vice, 

hydraulic engineer. D. Q. Matejka, hydraulic 

engineer, was in charge of field work. G. E. 

Burdick, area engineer, Bureau of Reclamation, 

assigned engineers from the Ainsworth office 

to do much of the field work. Mean daily water 

discharges at the Sparks gaging station for 

the 1951 water year were furnished by the 

Lincoln district office of the Surface Water 

Branch, D. D. Lewis, district engineer.

The field work included determinations of 

water and sediment discharges and the collection of samples of suspended sediment and bed 

material for particle-size analysis. Vertical 

and lateral distributions of velocity, concentration, and particle size were defined for 

the contracted section, five normal sections 

near the contraction, and two sections at the 

Sparks gaging station. Velocities and vertical 

distributions in the chute indicated that 

most, if not all, of the sediment load of the 

river was in suspension. Also, data from field 

measurements provided information as to the 

amount of sediment that is discharged as unmeasured load at normal sections near the 

chute. Indirectly they helped in computing the 

rate of sediment discharge as unmeasured load 

at the gaging station near Sparks, about 6 

miles downstream, where daily discharges of 

suspended sediment were determined from May 

to January 1951.

This report conbains a summary of the information that was obtained from November 2, 

1950, to July 17, 1951- High flow on July 29
STATE

\

Sparks 223

V

ration, Niabrara (( \ ' { / I

River above Buffalo Bridge Gaging station, Niob/ora,

Valentine Nebr. ^ i /River near Sparks, Nebr. I.

N ( \ 

V !

FORT NIOBRARA

NATIONAL 

WILDLIFE REFUGE

Figure 1. Sketch map of the Niobrara River near Valentine and Sparks, Nebr.

widened the constriction to the extent that 

velocities and turbulence were not nearly sufficient t» suspend the total sediment load. 

The final field data were collected on July 17.

In this report suspended sediment is that 

part of the sediment load of a stream that can 

be collected in a depth-integrating sediment 

sampler. Suspended-sediment discharge or 

suspended-sediment load is the sediment discharge thatcan be computed from water discharge and the concentration from depthintegrated sediment samples. The unmeasured 

load is the difference between the total sediment load of a stream and the suspendedsediment load.

RIVER CHANNEL

The channel of the Niobrara River in the 

Port Niobrara National Wildlife Refuge averages about l^O ft in width. Most of the stream 

bed is composed of shifting sand, but in 

places the bed is scoured down to shale or 

firm clay. The channel banks are generally low 

and partly covered with brush except for an 

occasional place where the river flows at the 

base of a steep bank of Brule clay. The slope 

of the channel is about 8 ft per mile; the 

measured slopes downstream near the Sparks 

gaging station averaged 7.£ ft per mile.

A small power dam about 2-| miles upstream 

from the contraction forms a pool in which 

sediment is trapped. (See fig. 1.) During the 

summer this pool is flushed periodically to 

remove part of the accumulated sediment. A 

small power dam on Minnec-haduza Creek about 6 

miles upstream from the contraction forms another small pool that is also flushed occasionally. The flushing of these pools probably 

causes alternate fill and scour of the channel 

for several miles below the dams.

MEASURING SECTIONS 

Contracted Section

.Before the contracted section was formed, 

the channel was probably 100 to 1^0 ft wide. 

Immediately after, it was constricted to a 

width of about 30 ft for a distance of about 

100 ft along the channel (fig. 3). A footbridge was built by the Bureau of Reclamation 

near the downstream end of the contracted 

channel, where the flow was swift and turbulent (fig. I).). The downstream side of the 

footbridge was the section, called section B_, 

at which measurements were made to determine' 

total sediment discharge of the river. Sampling stations were measured from the right 

bank. Mean velocities measured at section B 

during the period November through January 

ranged from 3.28 fps at a discharge of 237 cfs 

to 8.77 fps at a discharge of 1,llj.0 cfs. Standing waves, high velocities, and an uneven 

stream bed were factors that limited the accuracy of measurements of stream flow at this 

section. During the early part of February, 

ice dislodged the footbridge and widened the 

constriction to about 1^.0 ft. A second footbridge was constructed in April by personnel 

of the Bureau of Reclamation. It spanned the 

constriction at the original site; however, 

the bridge stationing was shifted 12 ft to the 

right so that station 0 would be over the 

right bank. After the channel was widened, 

measured velocities ranged from 6.00 fps at 

990 cfs to 6.91+ fps at 1,01^0 cfs. Standing 

waves, high velocities, and an uneven stream 

bed continued to limit the accuracy of streamflow measurements at the section.

On July 29, I9£l, a flood collapsed the 

footbridge and further widened the constriction to about 75 ft. Resulting lower velocities and turbulence were sufficient to suspend
Errata Circular 205

Credit to tue tt. S. Bureau of Reclamation for figure 2 on page 3 was inadvertently 

:^dtted. The title for figure 2 on page 3 should read as follows*

Figure 2. Looking upstream toward the contraction of the Niobrara Riirer 

formed by bank caving (Photograph courtesy of Uo S. Bureau of Reclamation)*

Figure 2. Looking upstream toward the contraction of the NIobrara River

formed by bank caving.

Figure 3. Looking downstream from the upper end of the contracted

channel.
Figure ij.o Footbridge where samples were taken to determine total 

sediment discharge of the river section B.

only a part of the sediment load that was unmeasured at the normal sections.

The locations of the contracted section, the 

five normal sections, and the staff gage in 

the reach of the Niobrara River near Valentine 

are shown in figure 3>«

Normal Sections

Section A is the farthest upstream of any of 

the measuring sections. At this section the 

water surface is about ll|0 ft wide, and the 

stream bed is composed of shifting sand. Section A- is about a quarter of a mile upstream 

from section B and is reasonably representative of this reach of the river channel; however, it is in a relatively inaccessible part 

of the stream.

On May 8, section A was replaced by section 

A 1 (fig. 6), which is 450 ft upstream from 

section B. Section A 1 is about 13>0 ft wide. 

Its bed is composed of relatively stable sand. 

L.ow standing waves sometimes are present near 

the center of the stream.

Section £ (fig. 7) was selected as a typical 

section of the channel. It is about 3>00 ft 

downstream from section B and close beldw 

Buffalo Bridge. The bottom is shifting sand 

except for an occasional place where more stable material is exposed. The section is about 

190 ft wide.

Section D_, three-quarters of a mile downstream from section B_, was initially a representative section of the channel. It was about

160 ft wide and had a s#.ndy, shifting bottom. 

Subsequent measurements, however, indicated 

that section D is not a true alluvial section 

because it sometimes scours to its Brule clay 

bed.

On May 8, section D was replaced by section 

D' (fig. 8), about 1,3>00 ft downstream from 

section B_. Section D 1 is about lij.0 ft wide, 

and its bed is composed of fairly firm sand. 

It is considered to be a representative section of the channel.

Sections A, A 1 , C_, D 1 , and I) (fig. 3>) were 

all selected as sections at which the ratio of 

suspended-sediment discharge to total sediment 

discharge seemed likely to be representative 

of the normal river channel near the contracted section. In this report these five 

sections are frequently referred to as normal 

sections to contrast them with the natural 

constriction, section B.

Sections at Sparks Gaging Station

The gaging station near Sparks, Nebr., is 

about 6 miles downstream from section B. The 

channel under the bridge (fig. 9) is somewhat 

narrower than the average width of the river. 

Measurements of water discharge are made from 

the bridge, which is a few feet upstream from 

the recording gage, or at low stages, by wading at wider sections downstream from the 

bridge. (See fig. 10.) Samples for determining 

the average concentration of suspended sediment at a cross section were collected at the 

section where the measurement of stream flow 

was made on the s ame day.
)staff 

Section A1-

gagt

Section A

Sectio^_Bj;contraction) 

Section C ** %=:-_

Section D

Sparks gaging 

station 4.6 miles 

Section D 1

It \\ 

\\

 }\ ' 

9 ***\ "" ~~Heod,quorTers of Wildlife Refuge/ 

\\ a 

\\ 

\\ 

\\ \\

II // 

// 

// 

// 

//

2 Mile

Figure %. Sketch map showing location of sampling sections of the Niobrara River above Buffalo

Bridge, near Valentine, Nebr.

Figure 6. View of section A 1 from right bank. 

Section extends directly across the channel.
Figure 7« View of section C_ from left bank. Section is parallel to 

and about 1|0 ft downstream from Buffalo Bridge.

Figure 8. View of channel at section D 1 from 

left bank.
Figure 9. View of bridge section, Sparks gaging station.

Figure 10. View of wading sections, Sparks gaging station.

7
During the period of record, the numbers of 

determinations of suspended sediment at the 

different sections with each type of suspendedsediment sampler were as follows:

Section D' 

Sparks gaging

Number of determinations 

1 with indicated sediment 

samples

US DH-lj.8

k

11

3

1

14

US D-U3 or 

US D-l]_9

8

12

US P-U.6

a 5 

b 38

a Point-integrated samples, 

b Depth-integrated samples.

Usually the water discharge was measured on 

each day when samples were collected. All the 

stream-flow measurements are summarized in 

tables 1 and 2. Tables 3 to 5 show results of 

the sediment discharge measurements. Gage 

heights for measurements at all sections near 

Valentine were read on a staff gage that was 

installed on November 8 about 220 ft upstream 

from section B.

Figures 11 to 21; show the lateral distributions of depth, velocity, and concentration of 

suspended sediment at each section and the 

changes in the lateral distribution with time. 

Because the lateral distribution at section B 

for a given water discharge (figs. 13 to 15) 

changed slowly with time, the results were not 

plotted for all measurements. The velocity distribution changed considerably with changes in 

flow of the river. Scour of the bottom and 

sides of the channel was too slow to be detected by observation or by the measurements 

at section B.

The general hydraulic characteristics of sections A, A', C, D 1 , and D are similar (figs. 

11, 12, and l£> to 20), but both sections A_ and 

C_ shift considerably from time to time. At the 

Sparks gage the bridge section and the wading 

sections are more stable and seem to change 

less with time than do sections A_ and C_. The 

channel at section A_' is more stable than at 

any of the other sections where measurements 

were made.

A comparison between the suspended-sediment 

concentrations at section B_ and at all other 

sections is shown in table 6. Concentrations 

at the normal and Sparks sections, taken from 

tables 1; and 5>» a- re listed along with observed 

concentrations at section B, taken from table 

3, and also estimated concentrations at section B_. These estimated concentrations at section B were computed from the observed concentrations and gage-height records. An allowance 

for the time of travel was made so that they 

would be comparable to measured suspendedsediment concentrations at the other sections.

An average of concentrations at each of the 

normal and Sparks sections, expressed as a 

percentage of the estimated concentrations at 

section B, is given in table 7- The percentages, within the limits of accuracy of the 

data, are also the percentages of the total

sediment discharge that are in suspension if 

the following assumptions are correct:

1. For the given times, the stream flow at 

the uncontracted section was the same as at 

section B.

2. For the given times, the total sediment 

discharge at the uncontracted section was the 

same as at section B.

Actually, the assumption of equal flow at 

each section is substantially correct although the flow at the Sparks gage probably 

averages a few percent greater than at the 

other sections (table 8). The assumption of 

equal total sediment discharge is not always 

even approximately correct when section B_ and 

the sections at the Sparks gage are compared. 

Eight determinations of suspended-sediment 

concentrations during winter months indicate 

a greater suspended-sediment discharge at the 

Sparks station than total sediment discharge 

at section B. Evidently the channel between 

section B and the Sparks gage was degrading 

during this period. Probably total sediment 

discharge does not vary greatly between section B and any one of the normal sections 

near section B.

Twenty-one determinations of suspendedsediment concentration at the normal sections 

near section B ranged from 29 to 88 percent 

and averaged Ijj percent of the concentration 

at section B at comparable times. Thus the 

discharge of sediment as unmeasured load at 

sections A, A_', C_, D', and D is about equal to 

the discharge of suspended sediment for the 

period when these concentrations were determined.

Six determinations of the ratio of suspendedsediment discharge at the gaging station near 

Sparks to the suspended-sediment discharge at 

section B, about 6 miles upstream, averaged 

Q.l+l to 1 in the periods November 2 to 17, 

1950, and May 8 to July 17, 195>1. During'the 

winter period, November 18, 195>0, to May 7, 

195>1» this ratio was about 1.4 to 1. In general, the ratio increased with time within 

this winter period. The high ratios during 

the winter were due to low concentrations at 

the contracted section. These low concentrations were probably caused by entrapment of 

sediment in the upstream reservoirs after 

periodic flushing was discontinued. The recorder chart from the Sparks gage indicates 

that the last flushing of the reservoir on 

the Niobrara River near Valentine during the 

fall of 1950 was on November 18. It is also 

possible, but not likely, that the high ratios 

during the winter resulted from the seasonal 

effect of ice formation.

The assumption that the high ratios during 

the winter were caused by sediment entrapment 

in the reservoirs seems to be logical because 

the relatively clear water leaving the reservoirs would immediately begin to degrade the 

alluvial channel. Probably the most'extensive 

degradation would at first occur directly below the dams. Because the supply of sediment 

in the channel immediately below the dams 

would not be replenished at a normal rate 

after November 18 when flushing operations 

ceased, scour could be expected in the river 

reach between the constricted section and the 

Sparks gage during most of the period until 

flushing is resumed. Scour between section B 

and the Sparks gage could cause the high 

ratio of concentration at the Sparks gage to
FEET A00Vt ARBITRARY DATUM VELOCITY, IN FEET PER SECOND (MEAN IN VERTICAL) CONCENTR
-. 2000

1500

SUSPENDED SEDIMENT CONCENTRATION ACROSS SECTION

> Q

< CO

or 13

o i*J

03 O

VELOCITY ACROSS SECTION

EXPLANATION 

May 9, 1951 

May 23, 1951

DEPTH OF WATER ACROSS SECTION

60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 ISO

Figure 12. Lateral distribution of depth, velopity, and concentration of 

suspended sediment, section A', Niobrara River near Valentine.

10
5000

40OO

3000

SUSPENDED-SEDIMENT CONCENTRATION SECTION

. aooo

1000

EXPLANATION 

Nov. 10, 1950

10

-2

-3

-4

VELOCITY ACROSS SECTION

DEPTH OF WATER ACROSS SECTION

30 25 30 15 10 5 

STATION ACROSS SECTION, IN FEET

Figure 13. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section B, Niobrara River near Valentine.

11
ELEVATION, IN FEET1 (GAGE DATUM) VELOCITY, IN FEET PER SECOND (MEAN IN VERTICAL) CONCENTR
10,000 SUSPENDED SEDIMENT CONCENTRATION ACROSS SECTION

EXPLANATION 

Jan. 26, 1951 Old bridge

May 8, 1951 New bridge

 _ 

May 23, 1951 New bridge

June 28, 1951 New bridge

x x 

July 17, 1951 New bridge

II

L

VELOCITY ACROSS SECTION

40 35 30 25 20 15 10 5 0 -5 -10 

STATION ACROSS SECTION, IN FEET ON OLD BRIDGE

I______|______|_______|______|______|______|______|______|______|_____

50 45 40 35 30 25 20 15 10 5

STATION ACROSS SECTION, IN FEET ON NEW BRIDGE

Figure IJJ. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section B, Niobrara River near Valentine.

13
2500

2000

1500

1000

500

SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

VELOCITY ACROSS SECTION

EXPLANATION

Nov. 2, 1950

 -- - 

Nov. 3, 1950

o o

Nov. 9, 1950

DEPTH OF WATER ACROSS SECTION

60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 180 200

Figure 16. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section C, Wiobrara River near Valentine.

14
2500

2000

1500

SUSPENDED SEDIMENT CONCENTRATION ACROSS SECTION

- 1000

500

EXPLANATION 

Nov. 10, 1950 

Nov. 17, I95O 

Dec. 21, 1950

DEPTH OF WATER ACROSS SECTION

40 60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 ISO 200

Figure 17. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section C, Niobrara River near Valentine.

15
3500

aooo

1500

1000

500

SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

VELOCITY ACROSS SECTION

DEPTH OF WATER ACROSS SECTION

20 40 60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 180 200

Figure 18, Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section C, Niobrara River near Valentine.

16
SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

+ 1

-2

-3

-4

p. VELOCITY ACROSS SECTION

EXPLANATION 

May 9, 1951

DEPTH OF WATER ACROSS SECTION

20 40 60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 180 200

Figure 19. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section D<, Niobrara River near Valentine.

17
2500

2000

1500

1000

500

SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

-2

-3

VELOCITY ACROSS SECTION

EXPLANATION 

Nov. 3, 1950

DEPTH OF WATER ACROSS SECTION

20 60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

160 180 200

Figure 20. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, section D, Niobrara River near Valentine.

18
2500

2OOO

IS'OO

1000

500

SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

' \ <**

VELOCITY ACROSS SE.CTIQN

EXPLANATION

Nov. 21, 1950

Nov.

Dec. II, 1950

Dec. 20, 1950

DEPTH OF WATER ACROSS SECTION

40 6O 8O IOO I2O 

STATION ACROSS SECTION, IN FEET

Figure 21. Lateral distribution of depth, velocity, and concentration of 

suspended sediment, bridge section, Niobrara River near Sparks.

19
ELEVATION, IN FEET (GAGE DATUM) VELOCITY, IN FEET PER SECOND (MEAN IN VERTICAL) CONCEN

CO CD 

CO t\J

 c ro CD P i

P. I

CD tr1

P, JD

ct 

ra CD

CD 4 

p. SO 

p. )_"

CD p.

cr H4 cr

p. p, 

O CD

O <

a" CD

4 H

SB O

 ^ O

SB HCD SB

4 P

PM

CD O

SB O

1 P

O

CO CD 

tJ 13 

fD Ct
SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

VELOCITY ACROSS SECTION

EXPLANATION 

Nov. 17, 1950 (b)

Dec. 22, 1950 (b)

Nov. 3, 1950 (a)

(a) Discharge measurement 

made 100 ft below gage

(b) Discharge measurement 

made 350 ft below gage

DEPTH OF WATER ACROSS SECTION

60 8O IOO I2O I4O 

STATION ACROSS SECTION, IN FEET

I6O ISO

Figure 23.--Lateral distribution of depth, velocity, and concentration of 

suspended sediment, wading sections, Niobrara River near Sparks.

21
SUSPENDED-SEDIMENT CONCENTRATION ACROSS SECTION

VELOCITY ACROSS SECTION

Jan. 26, I95l(c) 

o c

March 9, I95l(c)

(c) Discharge measurement 

made 300ft below gage.

DEPTH OF WATER ACROSS SECTION

60 80 100 120 140 

STATION ACROSS SECTION, IN FEET

200

Figure 2l±. --Lateral distribution of depth, velocity, and concentration of 

suspended sediment, wading section, Niobrara River near Sparks.

22
that at section B even though the concentration at the Sparks gage was lower than at 

other seasons of the year.

DAILY WATER AND SEDIMENT DISCHARGES

Daily water discharge of the Niobrara River 

above Buffalo Bridge, near Valentine, was computed for the period November 28 to December 

21. Gage heights read on the staff gage upstream from section E were plotted on a print 

of the recorder chart for the Sparks gaging 

station. A continuous graph of estimated gage 

height at the staff gage was drawn for all 

this period of the record except December 16 

to 19. Between gage readings, the graph was 

based on the changes in gage height at the 

Sparks station and on temperature records. The 

gage-height graph and a rating table based on 

the rating curve shown in figure 2 5 were used 

to compute the daily water discharges for use 

at section B and at the normal sections near 

Valentine. Mean daily water discharges for 

December 16 to 19 were estimated" on the basis 

of records for the Sparks station. When daily 

water discharges at the staff gage were compared with those for the Sparks gaging station, some inconsistencies were found. The 

stage-discharge relation shifted considerably 

at each place because of (a) changes in bed 

elevation and (b) backwater from ice at times. 

Records of daily discharge at the staff gage 

were revised slightly on a few days when the 

revisions were not inconsistent with measured 

discharges. On other days when the water discharge at the two sites seemed to be inconsistent by only a small percentage, no revisions were made.

Daily discharges of suspended sediment for 

November 28 to December 21 were computed for 

section B and for the gaging station near 

Sparks from daily water discharges and graphs 

of sediment concentration. The daily figures 

of water discharge, suspended-sediment discharge, and sediment concentration are listed 

in table 8. For December 2 to 5 and 7, when no 

daily samples were collected at the Sparks 

station, the sediment discharge was computed 

from a water-sediment discharge curve (fig. 

26).

MEASURED SLOPES OP THE WATER SURFACE

Water-surface slopes were recorded for the 

reach of river above _the Sparks gaging station. Simultaneous gage readings were obtained 

at the Sparks water-stage recorder and at a 

staff gage 890 ft upstream. Staff gage and recording gage were at the same datum. The average slope was 7»5 ft per mile. (See table 9.) 

Water-surface slope readings were discontinued 

after the staff gage was removed by ice. The 

last reading was obtained November 21, 1950.

distribution in section B of concentration, 

velocity, and percentage of particles larger 

than 0.25 mm. The 0.25-mm size was used for 

comparison; it approximates the median particle size. Each discontinuous line connecting 

the plotted points is only one interpretation 

of the distribution that seems to be indicated by the points -and may be inaccurate, 

especially near the bottom of each vertical.

Samples collected on November 30 and December 21 show little increase in sediment concentration from top to bottom of the verticals. Also the percentage of particles larger 

than 0.25 mm does not increase appreciably . 

with depth below the surface of the water. 

The sediment load must be far below the maximum carrying capacity at any section where 

the turbulence is sufficient to maintain 

nearly uniform vertical distribution of 

coarse sediment particles. The sediment trans 

ported as unmeasured load at such a section 

is probably a minute fraction of the total 

sediment discharge.

On December 7 the water discharge was low, 

and the mean velocity by current-meter measurement at 10:20 a.m. was 1^.11 fps. Vertical 

distributions show an increase of concentration and of percentage of particles coarser 

than 0,25 mm toward the bottom of the section 

at four of the seven sampling stations. At 

the other three verticals the concentration 

and the percentage of particles coarser than 

0.25 mm did not show a significant increase 

with depth. Perhaps an appreciable amount of 

sediment was discharged as bed load on December 7> but the engineers who took the samples 

did not report any deposits of sand on the 

bottom of the channel at section B_ at that 

time. In general, during the period before 

the channel widened to about 1|.0 ft it is probably safe to assume that, except when the 

stream flow was exceptionally low or there 

was backwater from an ice jam, almost all the 

sediment passed section B_ in suspension.

On both May 8 and June 28, 1951, vertical 

distributions showed an increase of concentration and of the percentage of particles 

coarser than 0.25 mm toward the bottom of the 

section at one of the three verticals that 

were sampled. The vertical showing this increase was at about the same location on both 

days. Soundings on May 8, 195l» indicated a 

wedge of deposited material from the right 

bank to station 8. In this part of the cross 

section the velocities of flow were low and 

the alluvial bank was being undercut. On May 

8 and June 28 at the other two verticals in 

the cross sections, the concentration and 

distribution of materials coarser than 0.25 

mm did not change appreciably with depth. 

During the period from May 8 to July 17, 

probably somewhat less than the total sediment load was transported in suspension.

DISTRIBUTION OF SEDIMENT IN SECTION B

Point-integrated samples of suspended sediment were collected at section B on November 

30 and December 7 and 21, 1950, and on May 8 

and June 28, 195l. Two samples were taken at 

each sampling point. Concentrations, velocities, and particle sizes for each sampling 

point are listed in table 10. These velocities 

were computed from the filling time of the 

samples. Figures 27 to 31 show the vertical

PARTICLE SIZE 

Analyses of Suspended Sediment

The particle-size distributions of suspended sediment were determined I}.!}, times at 

section B, 22 times at the normal sections 

near B, and 16 times at the gaging station 

near Sparks. Usually less than 6 percent of 

the suspended sediment was coarser than 0.5 

mm. (See tables 11 to 13.) Some of the

23
1.6

1.4

1.2

1.0

\,

\

V

10.6

U>

UJ

z

UJ 

00.6

<

o

0.4

V «

0.2

\

\.

\ 

\

200 400 600 800 1000

DISCHARGE, IN CUBIC FEET PER SECOND

Figure 25. Rating curve for the Niobrara River above Buffalo Bridge, near Valen
5000

Q

z 

o 

o

UJ

tn 

cc

UJ

a.

1000

< 1 ( <

 *

o

X

^

x^

_ 

^

i >_

D

^.^

^X'

I

D

-""

> !

^x"

5 i

O

I

t ^

>

)

(

^f 

D

(

D

X.

,x

1 <

'0

i

. Xo9j >

 « y of n 

S^c ,,

t.1^

</

n

0

v<^f '

o o O "

^

1 

0 

X

>

0

*g^

D

5 8

 x"x

a

a

X

,^

D

J

Li

E

Sediment d

1947 and 

19

I9

19

; 5 * 

100

50 100 1000 

SUSPENDED-SEDIMENT DISCHARGE, IN TONS PER DAY

Figure 26.--Water-sediment/ discharge curve for the Niobrara River near S
0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0

43

 

3

X

4

/

r4

\ 

\

-VV 

\\

XL

4A

/

X

V\'

STA- ION 4

\

\

\

^^

\

\

^

STJ VTIOt 1 9

^

\

T

\

f ''/

\ 

^V

\

i t /

//

S

\

\

\

\ \ \

$

j I

t

L\~

2000 3000 4000 5000 6000 0 1000 

SUSPENDED-SEDIMENT CONCENTRATION, IN PPM

10 12 14 16 18 20 0 

VELOCITY, IN FEET PER SECOND

10 20 30 40 50 60 70 80 90 100

PERCENT COARSER THAN 0.25 MM

10 20 30 40 50 60 70

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

4.5 

5.0,

-STA

_.

TION

t

 ~~r

\

i

-H2-

^

//

-/"'

/

\

X

/

/

a

\

V

1

/

/

r/

1

1 

1

1

1

1

1

1

1

/

/

STAIONt

h

r/i

-''

i

i 

t

ft

s

\

\

/

/'

\ 

\

\

'

1

f

1

1

1

X

X

4-

4

) IOOO 2000 3000 0 IOOO 2000 3000 0 

SUSPENDED -SEDIMENT CONCENTRATION, IN PPM

t

s

'

 ATK

,''

(

/

i 

\

i

\

\ 

I

9 i

)-J 

i

i i

IOOO 2000 30

0246 8 10 12 0 

VELOCITY, IN FEET PER SECOND

20 30 40 SO 60 0 10 20 30 40 SO 60 

PERCENT COARSER THAN 0.25 MM

10 20 30 40 50 60

,_ 1.5

S"ATIC)N 22

STATION--26

EXPLANATION

Concentration in ppm

Velocity in feet per second

Percent coarser than 0.25mm

IOOO 2000 3000 0 IOOO 2000 

SUSPENDED SEDIMENT CONCENTRATION, IN PPM

VELOCITY, IN FEET PER SECOND

10 20 30 40 50 60 0 10 20 30 40 50 

PERCENT COARSER THAN 0.25 MM

Figure 27. Vertical distributions at section B, Nov. 30, 1950.

26
0.5

a ..0 u.

- 1.5 I*

EZO

o

2.5

3'°c

X 

X 

X

\ \

 

\

*

 7 

/

/

\ 

\

\-

/ /

u

-T- K

\

V

* 

^.

STAT

^^*"«.

ION

 " i~

""*^>^

4

- 

 ^^

 -~. " i. « "' n.

- * ^

Concentration in ppm

 0 

Velocity in feet per second 

Percent coarser than 0.25mm

 

 . ,

) 1000 2000 300O 40OO 5000 6000 7000 8000

SUSPENDED -SEDIMENT CONCENTRATION, IN PPM

-- 

9000 10 fl

0 

0.5 

K 1.0

Ul 

Ul

u.

1.5

z

i" 2.O 

o.

Ul

0 2.5 

3.0

3.5 

C

(

( 

0

as

1.0 

ui 1.5

Ul

u.

I

Ul

o 

3.0

3.5 

4.0

t 2

0 10

4 6 8 to 12 14 16 18 20 

VELOCITY, IN FEET PER SECOND 

i i i ii i i i i

20 30 40 SO 60 70 80 90 100 

PERCENT COARSER THAN 0.25 MM

\

/

X

)

1

> 2

\

3 10

\

J

f

i

? 

1

«

? l

f 

1

1

I

\

\

X

V '

\

\

\

iTAT

^

^

ON

v

V

8

x^

STAt

/

'ION

/

/

\ 

\

i

i \

r

»

4-

i

\

-N

\

STAT

i

P

S

\» \

x^l

M

ON 1

/

/'

y

n

\

\

\

\

\

1000 2000 3OOO 4000 0 1000 2000 3000 0 2000 3000 

SUSPENDED SEDIMENT CONCENTRATION, IN PPM 

i i i i i i | i i i i i ii

46 8 10 12 14 16 0 2 4 6 8 10 <2 0 2 468 

VELOCITY, IN FEET PER SECOND 

i i t i i i i i i i i .1 i iii

20 30 40 50 60 70 80 0 10 20 30 40 50 60 0 10 20 30 40 

PERCENT COARSER THAN 0.25 MM

t^\

\

1

X

 /\

3

i

3 2

i

V

\ 

» 

\

\

\ 

r - V1

A

t 

P

S PATH 3N I 9

JLr ^

qrM

V

 } *-s

\

\

s

TATI ON d2

 T* 

V

-ft1 4/-

y /<

/

4Ty1 \

»

sr/iTIOf* 25

1000 2000 3000 0 1000 2000 3000 0 1000 2000 3000 

SUSPENDED SEDIMENT CONCENTRATION, IN PPM 

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

4 6 8 10 (2 0 2 4 6 8 10 12 0 2 4 6 8 10 12 

VELOCITY, IN FEET PER SECOND

iii i i i i it ii ii i

20 50 60 0 10 20 90 40 50 60 

PERCENT COARSER THAN 0.25 MM

30 40 50 60

Figure 28. Vertical distributions at section B, Dec. 1, 19^0.

27
EXPLANATION

Concentration in p p m

Velocity in feet per second 

Percent coarser than 0.25mm

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 (

ST7

N

TIOI

\

"A

J 4

\

1

4

-}

-t_ >

^ <*

'A

\

e

 tH 

f 

/

tX

\

X

X 

1

\ ^

-f.

t

"-.

L

4i /

^

TATI

/ 

/

/-'

\ 

 -^

>w 

N 

N

)N 1

X

/

/ 

s

\

-4J X

/

f

/

1

?/ / 

t

\

\

f

1

f

) 1000 2000 3000 0 1000 2000 3000

SUSPENDED SEDIMENT CONCENTRATION, IN PPM

8 10 12 14 0 2 4 6 

VELOCITY, IN FEET PER SECOND

10 12

10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 

PERCENT COARSER THAN 0.25 MM

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

4.5

5 '°c

\

-\

-t

\

/'

_/_-

^x

\

A

1>

/

/

._ -

STAT

, "

 

ION

s'

\

«?

\ 

\

 v-

\ 

\

\ 

f»

 r

 14 19- 

/ 

/

5

\

\

T

\

t

t

1

t

 A

U\

i

-

;

i^ 

/

1-

ST

^^

~^ 

\

ATIO

/

S

V-

\

N I

/

/ /

\ 

\ 

-^^

\ 

\

M/

/

/>

'

l

I

^

^^ ^

X1 

fIL

STi

I

\

^

\

VTlOf

^

\

\ 

\

\

\ 

\

V 2*

/ / 

s

\

-\ 

\ 

\

\ 

\ _f_

/ /

) 1000 2000 3000 0 1000 2000 3000 0 1000 2000 

SUSPENDED SEDIMENT CONCENTRATION, IN PPM

10 12 0 2 4 6 8 10 12 0 

VELOCITY, IN FEET PER SECOND

10

10 20 30 40 50 60 0 10 20 30 40 50 60 0

PERCENT COARSER THAN 0.25 MM

10 20 30 40 50

Figure 29. Vertical distributions at section B, Dec. 21, 1950.

28
0.5 

h- 1.0

lL) 

UJ

" 1.5

Z

l"2.0 

1- 

0.

UJ

0 2.5 

3.0 

3.5(

 «

«- ""

)

S

^

' < 

\-4

Hi * 

t

s

I 

I-'

s.

/

^"' x.

"^-^

 ^s.

 *^»,

^

/

{

\

^H

\

J

"*-

^*^

~ -^

STA

~ - ,_

TION 16

> 1000 2000 3000 4000 5000 6000 7000 8000 9000 IO,OO

SUSPENDED SEDIMENT CONCENTRATION, IN PPM

(

V

(

0 

0.5

1.0

hu .* UJ 1.5

u, 

2 2.0

i" 

a 2.5

UJ

o 

3.0

3.5 

4.0

< 

(

) 2 4 6 8 10 12 

ELOCITY, IN FEET PER SECOND °

i ill

) 10 20 30 40 50 60 70 8 

PERCENT COARSER THAN O.Z5 IV

f

\

V

-4

\S

I

/

1

\

4-

i 

i -i 

i 

i

i 

i 

i

STA

-

TION

1 

27

> 1000 2000 3000 4C 

SUSPENDED SEDIMEN

i i i i i i

0 90 100 0 .

1M

1.0

1.5 

hUJ 2.0

u.

I 

hQ. 3.0 

UJ 

O

3.5 

4.0 

4.5

oo 5'°c

T CONCENTRATK

T

T

|

T

-t- y

s

1 

1 

1

/

STA

\ 

\

1 

1

1 

1

f

 t 

1 

1

-f 

-Note

coa 

0.2!

perc

TION

None 

rser than 

5mm (100 . 

:ent finer)

38

) 1000 2000 3000 

)N, IN PPM

lit i

J 2 4 6 8 10 12 14 16 0 2 4 6 8 10 |-& 

VELOCITY, IN FEET PER SECOND

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

) 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60

EX

Conce

Velocity 

Percent co

PERCENT COARSER THAN 0.25 MM

Figure 30. Vertical distributions at section B, May 8,
EXPLANATION

Concentration in p p m

Velocity in feet per second

Percent coarser than 0.25mm

0.5

1.0

1-

u. 

2 2.0

t 2.5

Ul

O 

3.0

3.5 

4.0C

C

c

^

-~-'

i

'

/

/

\ 

\

Ul

AX

\

\

/

\

\

x

X,

X

\

^

\

\

\

\

^

^-, »-^

STATION

 ^-- 

- . »

15

 -- 

1000 2000 3000 4000 5000 6000 7000 8000 9000 

SUSPENDED -SEDIMENT CONCENTRATION, IN PPM 

i ii i i i | |

) 2 4 6 8 10 12 14 16 18 20 

VELOCITY, IN FEET PER SECOND 

i ii iii _ |_ j

) 10 20 30 40 50 60 70 80 9O 100

PERCENT COARSER THAN 0.25 MM

u 

0.5 

1.0

1.5

hUJ

uj 2.0 

u.

Z 2.5 

i" 

t 3.0

UJ

o 

3.5

4.0 

4.5 

5.0C

\

\

 \ 

\

-i

,

{ 

\

X

;* \"

v 

\

V

/

/

f

\

\ 

\ 

 V-

\ 

\

 \

i

i

; /

/ /

-h

i i

i 

STA-

>

"ION ' 26

i 

iu _^«^

1

 f

/ 

 

1r

i

 h 

/ /

 f 

S

i i ?- 

/ /

; / /

/ 

p /

STATION

Not 

th 

(1C

37.5

e: None coarser 

an 0.25 mm 

)0 percent finer)

) 1000 2000 3000 0 1000 2000 3000 4000 5000

SUSPENDED SEDIMENT CONCENTRATION, IN PPM 

j___i___i___i i - i___i___i___i___i

10 12 14 02468 

VELOCITY, IN FEET PER SECOND

10 12 14 16 18 20

0 10 20 30 40 50 60 70 

PERCENT COARSER THAN 0.25 MM

Figure 31. Vertical distributions at section B, June 28, 1951.

30
particle-size analyses are shown in figures 

32 to [|3. The size distribution of the sediment at all the Valentine and Sparks sections 

for the entire period of record did not seem 

to vary appreciably with either time or water 

discharge. In addition, no apparent difference's existed in the size distributions between the normal sections near Valentine and 

the Sparks gaging station.

Analyses of Bed Material

Fifteen sets of bed-material samples from 

the normal sections and ten sets from the 

Sparks bridge section were analyzed for particle size by sieving. Each set consisted of 

samples from two to four points in the section. Only a few percent of the particles from 

any analysis were larger than 0.5 mm. Although 

the size distributions of the different sets 

of samples varied considerably, the analyses 

showed that the bed material near the Sparks 

gage averaged finer than the bed material at 

the normal sections during the winter period. 

(See tables ll). and 15 and figs. ijlj. to ij.9.) 

Presumably, the finer materials were depleted 

from the bed by selective sorting near the 

normal sections. This selective scour probably 

continued downstream at a decreasing rate 

while flushing of the small reservoirs above 

the power plants was discontinued because of 

ice. After flushing was resumed in the spring,

the size distribution of the streambed material of the two reaches resembled each other 

more closely.

UNMEASURED SEDIMENT DISCHARGE

For the period of record exclusive of winter months, the assumption can be made that 

probably most of the sediment that passed 

section B was in suspension. (See figs. 27 to 

31.) Also an average of _i|.7 percent of the 

suspended-sediment discharge at section B was 

in suspension at the normal sections (table 

7). Thus, over half of the total sediment 

discharge was transported as unmeasured load 

at the normal sections according to samples 

collected from November 2, 1950* to July 17> 

195l« During other periods and at different 

rates of water discharge, this ratio of unmeasured load to total load might be significantly different.

Information on particle sizes can be used 

to compute the size distribution of the sediment that passes the normal section as unmeasured load. The averages of the size distributions of the 20 sets of samples from 

sections A, A', £, D', and D during the period November 2~ to 17, 1950, and May 8 to July 

17, 195l> and of the 11 sets of size distributions from section B during the same period 

are shown in the following table:

Average particle size of sediments of the Niobrara River near Valentine for the periods Nov. 2

to 17, 1950, and May 8 to July 1?, 195l

Type and location of sampling

Percent finer than 

indicated size (mm)

0.125

35 

19

5

0.25

92 

72 

55 

1^6

0.5

100 

99 

98 

93

If the suspended- sediment discharge is 14.7 percent of the total sediment discharge and all 

the sediment is in suspension at section B, 

then, the size distribution of the sediment" 

that is discharged as unmeasured load at sections A, A_ f , C_, D' , and D can be readily computed. If the percentages of particles finer 

than any particular size are represented by 

PB» Pn, and Pu, for suspended sediment at section B, suspended sediment at any normal section, and sediment transported as unmeasured 

load at the same normal section, respectively; 

then for measuring sections near Valentine

PB = 0.53 P

This equation was solved for Pu to compute the 

figures in the next to the last line of the 

above table. The size distribution of the bed 

material is also shown in this same table.

Although the size distribution of bed material is not necessarily the same as the size 

distribution of the sediment that moves as unmeasured load, the two probably are similar 

for the range of particle sizes that are found 

in appreciable quantities in the bed of this 

reach of the Niobrara River.. The relatively 

close agreement between the particle si.ze of 

unmeasured load and bed material for sections 

A, A_' , C_, and D' (see above table) may indicate that the computed size distribution for

the sediment that moves as unmeasured load at 

the normal sections is reasonable.

Neither the quantity nor the size distribution of the sediment that is discharged as 

unmeasured load at the Sparks gaging station 

can be computed directly during the period 

November 19 to March 26, the period during 

which flushing of the reservoirs was discontinued. The average suspended-sediment 

discharge during this period was greater at 

the Sparks station than it was at the normal 

sections near the contraction or even than it 

was at section B. (See table 6.) Evidenbly 

scour during this time, as described previously, prevents any direct determination of 

the percentage of the total sediment discharge that is in suspension at the Sparks 

gaging station during the winter months.

Throughout the remainder of the period of 

record, when neither ice nor discontinuance 

of flushing affected the water-sediment relationships, the six determinations of 

suspended-sediment discharge at the Sparks 

gaging station averaged [(.1 percent of the 

total sediment discharge at section B. Thus, 

during this period the relationship for the 

sections at the Sparks station is

PB = O.IH Pn + 0.59 P u

31
0.01 O.I UO10

DIAMETER, IN MILLIMETERS

- IO WO

 O 

 M 

0» 

tout 

OJ 

 * 

u 

c

 -^

U

O> 

N

~~ 1

\ *»

\

PERCENT FINER «>«.«>«,

» U « Ul en ~g m <O IO <« ID <« ID << 

O O O O O O O O W O>OWO><0

\ '

\

K^ "**

\

S

1

1 

111

g JS.«

* in i 

$ - 

<0 "0 

01 01 <

 O *

S- 3-i

C

> 

c

D

>

J

<J

n 

A 

>4* 

»

V

v\

'V'^

rn

X

TJ

J>

Z

o

\

"d

5j

^,- -^^

=--

'"*-.

Figur

32

aly

ol-*l

w

<!si 

p w 

i-"r)

CD CD 

3 0 

ct PJ 

H- CD 

3 P0

 CO 

CD

on A

0.01 O.I 1.0

DIAMETER, INMILLIMETERS

PERCENT 

 M Of *> Ul o> -J 

-14 Ul O O O O O O O 

O)

K) 

0» 

00 

N

1 1

z z

o o

< <

OJ OJ

u> u>

 tn tn

p p

Ctl =

1

.

\ ^

\ \

N

Z 

< r

8 5

01 i

] 

<

? °

3 3

O> O> -4

 §62

i? ( w

V

\

^ \

^

n 

<

D

>

r ^ 

>

5

^

^

^

N 
PERCENT FINER

ltd

HT3 

CD CD

ltd

PPERCENT 

UI 0> 

OO

 yo

z z z z m 

? S ? S

(0 (0 (0 <£ 7

(II CD (II (II ~

O O p O >

_ O 

O 'a

^
99.6

99.5 

99.0 

96

95 

90

CC

z

IL.

70

I"

*40 

30

20

10 

5

2

1

i : ;

/

/

6 ;

/

1

^

;

i i

/

Y

i

/

Iff

//

Jj

&tr

f

\

 H

/t t

v i* $'t

W

\

f,

// ''I

i

1

/

\ S i

EXPLA

 Moj 

 Moj

 Moj

-

Hr ) ! ' :

NATIO 

8,195 

9,195 

I 23,195 

B 28,19 

17, 19

N 

i; 842cfs 

i; 771 cfs

i; i.oiocfs

5i; 952 cfs 

5i; 826 cfs

t i

 I til,

'- 5 4 5 § 7 i I 9

O.I 1.0 

DIAMETER, IN MILLIMETERS

10.0

Figure 36. Particle-size analyses of suspended sediment, section B, Niobrara River near

Valentine.

99.9 

994

99.5 

99.0 

98

95 

90

CC 

^80

iZ 

70

I"

£ so

°-40 

30

HO

10 

5 

2

: : : ' !

' '

/

'i

i ;

^

r

i

..

^

\

 l

/<

¥

i

 r

//ff/

"/I

f

:

tV

f

1 . 5 ' > '

EXPLA

 Nov

- -- NOV 

 . Now

 - NOV

r e 9

NATIO 

2,195 

3,195 

9,195 

10, 195 

17, 195

N 

0; 7l8c 

0; 804c 

0; 728c 

0; 616 c 

0; 832 c

fs 

fs

fs

fs

fs

? 3*5 » ' ' 1 ?

0.1 1.0 

DIAMETER, IN MILLIMETERS

10.0

Figure 37. Particle-size analyses of suspended sediment, section C_, Niobrara River near

Valentine.

34
99.9 

993

99.5 

99.0 

98

95 

90

|so

il 

70

5"

« 50 ut

°-40 

30

So

(0 

5

2

l

i : : < . ! i !

x!

/

 ^^

1 

^

^

1

?

^

1 '

£

i

/

//.

^J/L

iff/

V/l

#// 'f

'.

1

/ 

If '#/

'/

/

'

/

/

i

/

/

' i i . :

 

EXPLA

 - May 

 May 

- - Mou

._-______. Julu r .f

i

NATION 

26,1951, 681 cfs

8, 195i; 790cfs 

9, I95i; 774cfs 

23, 195i; l,OIOcfs 

) 28,1951; 933cfs 

17,1951, 826cfs 

? ^ * > ' i ?

O.I 1.0

DIAMETER, IN MILLIMETERS

Figure 38. Particle-size analyses of suspended sediment, section C_, Niobrara River near

Valentine.

99.9 

99.8

99.5 

99.0 

98

95 

90

!*>

iH 

70

I"

£ 50

°-40 

30

£0

10 

5

2

1

i ; ' ! !

/

/

1 i

/

/

1

/

/

'

)

/

1

/ 

/

f 

/

/

/

-/-

/

/

/

i

/ 

/ 

/

/

/

/

;

-f

/

\ '

/

/

/

/

x-Somple !

> ! S 1

/

/

earned to contoin bad

EXPLAN

 june j

.' : \\ii \y» !

moterial

AT ION 

, 1951 ; 757 cfs 

!8, 195i;924cfs 

r, 1951 ; 826cfs

U4U; . 1 ! > ' 5 ' 1 1 ?

0.01 0.1 . 1.0 10.0

DIAMETER, IN MILLIMETERS

Figure 39. Particle-size analyses of suspended sediment, section D', Niobrara River near

Valentine.

35
PERCENT FINER PERCENT 

-pw 

 d 

f»

S0

, DIAMET

M 

31z2

r Zm

m 

aj

</>

_o00 1 S0

is

S 

en 0£

* "V*1

\

%

0 < 

 0

5 ,

S 

en

P -<

* J 

^ <

? <

\\

s

»s

\ 1n- 0

ii

i?n

\

\^

k

7 

> 1

It

> 13tk

V ^^

*%%

EXPLAIN!;

H Oz

s\

N 

;>*

*%^

sx>

* ^

*,

X^

\ x

O.v

^^

 >!»

 v

^0,

\

e 4

CD ,

-P- O

*f

M P4cl- OH

1 CON

CD3H

 ^

CD M0

M)

CO£w d

CD

B,

CD

CL,

CD

P- 3

13o

trt 

I31 

CD

P O

tfP

4 p

H-

< 

CD

4 

13

CD P4W dPw
0.01 O.I1.00.

DIAMETER, INMILLIMETERS

Figure [(.3. --Particle-size analyses ofsuspended sediment thNiobrara Rivernear Spark

-to ui o

-rf 

<D 

 w 

10 

w 

 * 

Ul 

e_

c_

 J5

35 

UJ

m(0 

Ul 

 o

JT

PERCENT FINER «> <o « «

l« 01 * Ul <D -4 00 10 10 10 JO U> <0 I

o o o o o o o o <* o> o ui <B u

xxJS^

K jv

: i

i!

Ml

<n M c 

3 5 y

Ul 01 i

0) d> U w o

(JD 0* "

2. 2. E Ul Ul 0

\

vv

\N

m

X

f ?

o Z

!§

D

>

1

 t

1

XX^

Xy x\*^^s.

0.01 O.I 1.00

DIAMETER, INMILLIMETERS

Figure l±2. Particle-size analyses ofsuspended sediment thNiobrara Rive,near Sparks

-to Ul 5

-* 

<D 

(0 

10 

W 

 A 

Ul 

O

 J°

UJ 

(C

5

 o

Ul

1 1 1 1 11

f

to

 >!

U> 

Ul

GO - 

(0 

-J 

n

Ul

PERCENT 

S

Ot*OI«-4

O O O O 

\\

N{.

^

"n c 

n c 

1 . :

O ; 

*» S

\O (J Ul C

o - 

w i

0 « 

>. £

" 

1

5

5

i

a 

n

J. 

i

N\

'

v

^

EXPLAN

0

Z

L

^>^

\

^

^

N

S

N

S

N 

^
0.01 O.I

DIAMETER, INMl

Figure I|5>. Particle-size analyses ofbedmatei

LLIMETERS ''°°

'ial oftheNiobrara Rivernear Valentine

-to 01

Ul 

o> 

^x^^^^

£ 3

0 <

ro t> w o

0

^

: a

c <«

3 t>

U (J

: 3

c <«

3 

» (

PERCENT FINER «>«> ><,

is> OJ « in CD ~j <c tO u> u>iD<OiO< 

O O O O O O O O w O>ouia>u

^v

*x

n

ft

D C

X,

^

EXPLA

10 ^0 (£ (0 10 ^

55 S2 52 < ? S5 j>

681 cfs;Section £

, 765cfs; Section A1 - IpSOcfs; Section A* 

1,010 cfs;Section CIpiO cfs;Section D1

O

^

 *s

*v^

^

<

">>

^

X

^i

^x

^s

" > 

S

X

ft^"

\

-v-

*>\

V

1

»,.

v

^^

0.0!.! 101

DIAMETER, INMILLIMETERS

Figure i|i|. Particle-size analyses ofbedmaterial theNiobrara Rive near Valentine

- ro ui O

\

<^v

z

O

< 

m 

5

 en 

O

00 

w

0

o>

W 

« 

_ r>

5'

3

10

^

1 1 

1 1 1 1

f 1

J5 ^

5 i 

ui t 

P S

2 ? 

? 5 

.«? -«

(0 C

« 1 a J 

1 i

10 |t

PERCENT 

M w » w o> 

OOOOOO

^N

fl

0 /> 

0 ^

3c

-J ^ 

S 5

*.-

? 8

i t

\ !

 > i>

> "

3

.

1

J 

5

h

1

'

»

\

S^^^

mX.

TJ

r 

>

NATIO

^

\

 s^\

.^

*^^

\

"^

x '-

^>»

**

 V

^>
PERCENT FINER

-0

analy

PERCENT 

» Ol 01 

o o o 

553m 

« « « x 

N> N> N> 2

GO GO QD '

U> (0 (0

N> W 01

» a I

» ». .".

«> « « a * «

o *>. «

5' 5' 5'

§33

to 10 u>
Fig

1+9

Spark

PERCENT FINER

AuioD-ga) 

0000

i

ID ui oj

OB 09

0) OJ

« O

ui O

3. 5.

\

Figur

ij.8

ar Spark

0.01 O.I 1.00

DIAMETER, INMILLIMETERS

ro

w 

ui 5

y >

*Vx

V s-

\%

N

0

1?

' V

(

1

c

,.

X

x.

X

"x

PERCENT 

iooi»uia>-^

OOOOOO

"* » ^^

X.

7002 

1 » « 0

 > n r> f

o f> D -b OS 0

5 <D (D U 

n 01 Ul t 

3 P O j:

D vD 0 

n w 

 4 ->l

J. 2. 2 1 01 01

: f

» ro

j -

EXPLAN

O

950;824cfs "

N 

^<

x

^

-x

^s

Sx
When the equation is solved for Pu, the computed size distribution compares favorably 

with the measured size distribution of bed 

 material from the Sparks station, as shown

by the following table. This favorable comparison may indicate that the computed size 

distribution of the material that moves as 

unmeasured load is reasonably accurate.

Average particle size of sediments of the Niobrara River near Sparks for the periods Nov. 2 to 17*

1950, and May 8 to July 17, 1951

Type and location of sampling

_ J J J 4. 4. 0 , J +. 

Percent finer than 

indicated size (mm)

0.125

la

18 

2 

3

0.25

92 

68 

51 

Itf

0.5

100 

96 

93 

91^

CONCLUSIONS

1. During the periods November 2 to 17,

1950, and May 8 to July 17, 1951, nearly 

all the sediment was probably in suspension at the contracted section, section 

B, although a small amount of sediment 

may have moved through the contracted 

section as unmeasured load during May, 

June, and July, 1951« At times during 

the winter when the flow was exceptionally low or there was backwater from 

ice, appreciable quantities of sediment 

may have been discharged through section 

B as unmeasured load.

2. Twenty-one determinations of suspendedsediment concentration at the normal 

sections A_, A_', C_, D', and D averaged ij.7 

percent of the concentration at section 

B at comparable times. Thus at the times 

of measurement an average of about 53 

percent of the total sediment load of 

the Niobrara River near Valentine was 

discharged as unmeasured load through 

the normal sections. During other seasons and at other rates of water discharge the percentage of sediment that 

moves as unmeasured load might be considerably different.

3. The characteristics of sediment discharge 

gradually changed during the winter 

months while the periodic flushing of 

the upstream reservoirs was discontinued. 

Theoretically, the low concentrations at 

the outlets of the unflushed reservoirs 

should begin to increase downstream by 

the scouring of the finer materials from 

the stream bed. Both the rate of degradation and the particle sizes of the bed 

material should decrease downstream, but 

the concentration should increase downstream. However, even as far downstream 

as the Sparks gage the concentration may 

be lower than normal. The greater observed suspended-sediment concentrations 

at the Sparks gaging station than at the 

contracted section B_ show that the 

stream bed in this reach was degrading 

during the winter. The few samples, of 

bed material collected during the winter 

seem to show the expected decrease of 

particle size from the normal sections 

near Valentine to the Sparks gage.

Ij.. Six determinations of suspended-sediment 

concentration at the Sparks gaging 

station averaged Ip. percent of the concentration at section B at comparable

times. The standard error of the mean 

for this average indicates that there 

is 1 chance in 20 that the actual average would be less than 31 percent or 

greater than 5l percent. The standard 

error of the mean may not be very significant for a small sample of this 

type. Other errors may be more significant than sampling errors.

At the times of measurement an average 

of about 59 percent of the total sediment load was transported as unmeasured 

load at the Sparks gage. The average 

percentage of unmeasured load may be 

different at other times or at other 

rates of water discharge. Certainly 

during the winter the suspendedsediment concentration at the Spares 

gaging station was a much larger percentage of the concentration at section 

B than during the summer.

The computed particle sizes of the sediment that moved as unmeasured load at 

the normal sections near Valentine, but 

was presumably suspended in the contracted section, were slightly smaller 

than the average particle sizes in the 

samples of the bed material. Only small 

amounts of material coarser than 0.5 i 

were found either in the suspended sediment or the bed material.

During this investigation certain items 

of base data that were not obtained 

would have been useful particularly in 

explaining the results in terms of 

theories of sediment transportation. 

Some of these are:

. A continuous gage-height record from 

a water-stage recorder installed at 

the staff gage site above the contraction.

. Water-surface slopes and enough cross 

sections at each normal section near 

the contraction to determine the 

energy gradient even though the 

Niobrara River is not a strictly 

alluvial stream at all sections near 

Valentine.

. Occasional point-integrated samples at 

the normal sections near the contraction and at the measuring sections at 

the Sparks gaging station. These data 

would help to define vertical distributions of velocity, concentration,

41
and particle size and to indicate 

approximate amounts of unmeasured 

sediment that is carried in suspension below the sampling range of 

depth-integrating samplers.

d. Daily suspended-sediment samples at 

the contracted section and at the 

Sparks gaging station.

e. A few series of samples of suspended 

sediment and of bed material every 

mile or two from just below the dam 

on the Niobrara River near Valentine 

to the Sparks gaging station.

f. Soundings in the chute to locate any 

possible areas of deposition, undercutting, or other changes ifi the 

channel cross section.

42
TABLES

43
Table 1. Discharge measurements of the Niobrara River above Buffalo Bridge, near Valentine, Nebr., during the ye

Date

Nov. 2, 1950 

Do 

Nov. 3 

Tin _ ___ __

Tin _ _

Nov. 10 

Nov. 17 

Nov. 21 

Nov. 22 

Nov. 28 

Nov. 29 

* Dec. 6 ------

T1or> R _ _

Dec. 11 

nor* 1 9 

Dec. 13 

Do -----

Dec. lit. 

Dec. 15 

DSC 20 

T1or« 91 __

Do 

T»or» 99 _-._

Jan. 26, 1951

Tin ________

MaTT fi _______

Do 

Matr 0 ____ __

Do 

May 23 

Tin 

Made by

M t 'k R 'tt

Raitt, Wertenberger 

Matejka, McKim, Raitt - 

Matejka, McKim 

McKim, Raitt, Whitsel -

Mrlf-im Wri t <=el ________

Raitt, Whitsel ----- - 

McKim, Miller, Raitt 

0

Raitt, Wark, Whitsel 

Wark, Whitsel 

Raitt, Wark > 

Busalacchi, Wark, Raitt

Raitt, Wark ---- - 

McKim, Whitsel 

McKim, Vice, Whitsel 

McKim, Whitsel ----- 

McKim, Vice, Whitsel 

Colby, Evjen, Wark - -

Whitsel 

Huhhpn Wsrk- __ __ .-_-

__ do ____ 

fiharhii p.k- . Tlavi R _______

Width 

(feet)

1U2 

191 

lliO 

190

137 

156 

196 

30.5

195 

200 

32 

32

31 

32 

32 

32

31 

31 

31 

31

31.5 

31.5 

31 

31.5

3U.5 

33 

32 

32

33 

190 

33 

35

199 

200 

UO 

1U3

201 

1U9

10

Area 

(sq ft)

198 

225 

219 

239

22U

228 

80.8

192 

232 

119 

115

113 

12U 

121 

116

110 

72.3 

92.6 

110

130 

130 

133 

132

1U3 

136 

119 

117

122 

309 

136 

138

318 

200 

127 

201

200 

206

277 

 Kn

Mean 

velocity 

(fps)

3.19 

3.58 

3.36

3.76 

3.U2 

3.20 

5.97

3.22 

3.60 

6.5U 

7.28

8.3U 

8.30 

7.06 

7.92

5.UO 

3.28 

lull 

5.oo

8.69 

8.77 

7.76 

8.12

7.76 

6.90 

8.2U 

8.U3

7.7U 

3.07 

7.17 

6.70

2.56 

3.76 

6.01 

3.73

3.70 

3.68 

3.76

A-Q)!

Gage 1 

height 

(feet)

0.56 

.26

.63 

.67

1.07 

1.08 

.91 

.87

.85 

.12 

.59 

1.28

1.U6 

1.U5 

1.62 

i.UU

1.62 

1.6U 

1.22 

1.1U

1.11 

1.26

i.Uo 

1.61

1.53

-.18

-.19

.30 

_^n

Discharge 

(cfs)

701 

718

8UO 

8U5 

728 

U82

616 

832 

778 

835

9U1 

1,030 

855 

916

590 

237 

378 

550

1,130 

i,oko

1,070

1,110 

939 

98U 

986

9U9 

97U 

92U

813 

750 

763 

750

7Ul 

758

i oho

Method

0.6, .2-. 8

A 9_ ft

o. 

vn

O CN <

orororo rorororo roro>.

ill III |i

30COOOCO cooococo cocococo cocoooco CoCoO^Co CoGOCoco Cocococo Coococo CoCoc

Meas. 

sees, 

(no.)

31

U2

3U 

20

22 

29 

17 

17

16 

18 

17

17 

13 

13 

13

15 

15

15 

15

17 

15 

17 

17

18 

3U 

17 

19

31 

U3 

33 

31

37 

U2 

30

91

Gageheight 

change 

(feet)

-0.12

+.16

+.02 

+ .08

-.06 

+.03 

-.07 

-.05

-.06

+.10 

0

+ .03

-.08 

-.30 

-.09

-.33 

-.lit 

-.10 

0

-.09 

+ .01 

-.36 

-.26

-.22 

-.19

-.01 

+.09 

0 

o

1

1

1

1

1

1

1

1

1

1

1

1
Tin __ _ _

July 17 

-L7U

Uo

U3.5

1U9

£. fU

155

165

r\ f\

->«;>£

6.11

6.00

3.UU

.07

.13

.10

7*47

9U9

990

908

 x o Q

6

0 Q

6

0 D

35

23

O *C

-.06

-.OU

-.06

1 Staff gage located on right bank 6f>0 ft above Fish and Wildlife Service Buffalo Bridge.

Note. Employees of Bureau of Reclamation are J. Busalacchi, F. G. Macias, C. R. Miller, D. B. Raitt, D. Walker, R. Werten

K. Zentner.

Table 2. Discharge measurements of the Niobrara River near Sparks, Nebr., during the year ending Sep

Date

Oct. 23, 1950 

Nov. 3 

Nov. 17 

Nov. 21 

Nov. 28 

01 Jan. 10, 1951

Feb. 22 

Mar. 23 

Apr. 9 

May 7 

Matr O _ _____

May 23 

May 26 

June 22 

Tune 9fl __ _

July 6 

July 17 

Made by

Matejka, McKim, Raitt - 

McKi'm, Raitt, Whitsel -

Busalacchi, Raitt, Wark

McKim, Whitsel 

 do 

Wark, Hubbell, Steele, 

Whitsel 

Davis, Chadwick, Raitt,

Mh-i t col _-_ __ _ _> _ __

 do 

Raitt, Whitsel 

Raitt, Wark, Whitsel 

Width 

(feet)

165 

166 

16U 

139

mo

138 

1U2 

127

16U 

160 

160 

160

136 

lUo

lUo 

163 

163 

161

1U5

138 

165 

165 

16U

138

139 

lUo

Area 

(sq ft)

231 

228 

229 

231

255 

265 

277 

252

256 

302 

289 

32U

188 

309

316 

2UU 

259 

222

261

270 

251 

2U9 

26U

23U

212 

239

Mean 

velocity 

(fps)

3.55 

3.U3 

3.60 

3.71

U.OO

3.66 

3.61 

3.78

3.71 

2.77 

2.91 

3.15

2.77 

3.72

U.27 

3.66 

3.76 

3.1*1

3.62

3.92 

3.71 

3.U9 

3.90

1.15 

U.oo

3.77

Gage 

height 

(feet)

2.95 

2.9U 

2.93 

2.93

3.02 

3.22 

3.11 

3.05

3.06 

3.23 

3.1U 

3.29

2.56 

3.08

3.30 

2.9U 

3.06 

2.87

2.93

3.09 

3.0U 

2.97 

3.21

3.06

3.0U 

3.10

Discharge 

(cfs)

819 

781 

825 

859

1,020 

971 

1,000 

953

959 

836 

8Ul

1,020 

521

1,150

i,35o 

893 

97U 

758

923

1,060 

9Uo 

869 

1,030

971

8U8 

900

Method

0.5, .6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8

.6, .2-. 8 

s,.5,.6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8

.6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8 

.6, ,2-.6

.6, .2-. 8 

.5, .6

.6, .2-. 8 

.5, .6, .2-. 8 

.6, .2-.8 

.6, .2-.8

.6

.6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8 

.6, .2-. 8

.5, .6

.5, .6, .2-. 8 

.6, .2-. 8

Meas. 

sees, 

(no.)

36 

37 

37 

28

28 

28 

22 

27

37 

31 

33 

35

31 

30

31 

35 

35 

36

30

31 

36 

39 

U2

26

37 

25 

Gageheight 

change 

(feet)

+0.01 

+ .02 

-.01

-.06* 

-.02

-.07 

-.08 

0

-.02 

+.07

+.01* 

0 

-.02 

+ .OU

+.03

-.01 

0 

+.02 

+ .02

-.01

+ .02

+ .01

Time 

(mst)

11:30 a.m. 

10:35 a.m. 

12:50 p.m. 

1:30 p.m.

1:25 p.m. 

10:30 a.m. 

12:35 p.m. 

11:00 a.m.-

10:35 a.m. 

11:35 a.m. 

12 : 07 p.m. 

12:50 p.m.

11:25 a.m. 

1:25 p.m.

11:13 a.m. 

10:20 a.m. 

12:10 p.m. 

11:1*2 a.m.

3:1*8 p.m.

2:33 p.m. 

10:35 a.m. 

10:03 a.m. 

10:1*5 a.m.

3:57 p.m.

9:W a.m. 

2:30 p.m.

Note. Employees of Bureau of Reclamation are J. Busalacchi, F. G. Macias, D. B. Raitt, R. Steele, and G. J. Whitsel.
Table 3.--Sediment discharge measurements of the Niobrara River near Valentine, Nebr.

(contracted section)

Date

Nov. 2, 1950 

Do 

o

"KTmr O __ __

AT nV TO _________

JMOV. JL | 

Wnv ?1 _- ______

Do

Wmr ?? _________

Tin ____________

Wmr ?ft _ ___ _-

Do

Do

Dec 6 ____-___-_

noo in _________

Do 

Dn ____________

Dec 14 ---------

Do

Do 

Do 

Do

Do

Dec 22 

Do ______

Jan. 26, 1951 

Mmr ft ___________

Matr Q ___ __ __

IVfn IT- 9 Q _ _ _

Tuna ? ft _ ______

T-i , 1 -H. "1 "7 _ ____ UU.-LJ JL ( _____

Time 

(mst)

2:30 p.m.

10:00 a.m.

1:00 p.m. 

12:45 p.m.

2:15 p.m.

9:40 a.m.

9

» *3 C\ Q m

10:00 a.m.

4:00 p.m.

8:10 a.m.

10:30 a.m.

11:15 a.m.

10:10 a.m.

3:05 p.m.

8:55 a.m.

12:00 m.

11:20 a.m.

2:10 p.m.

3:30 p.m. 

10:25 a.m.

4:25 P.m.

10:10 a.m.

3:50 p.m.

10:00 a.m.

3:10 p.m.

10:40 a.m. 

4:45 p.m.

8:40 a.m.

4:00 p.m.

8 40 a n

11:00 a.m.

10:05 a.m.

4:00 p.m.

4:00 p.m. 

8:45 a.m.

3:45 p.m.

8:40 a.m.

11:20 a.m.

10:50 a.m. 

5:10 p.m.

12:00 m.

11:30 a.m.

12:25 p.m.

11:40 a.m.

\fj Q + O Y»

discharge 

(cfs)

b 1-7-1 Q

b 804

bb 824

 -7 Q o

702 

502

Dt i.

969

790 

790

6

i^Q

1,330

Q / i-j

1,080

r\~\ Q

944 / 4 A

222

250

605

i-'Q ,-. 509

y-,-1 O

1,150

1,050

1,070 

1,050

1,030

1,100

Q r'n

935

935

1,000

r\ *~rQ

1,000

,-, i-iQ 97o 

916

Qt9

960

1,000 

681

Q J o

771

1,010 

952

Qo£

Suspendec

Mean 

concentration 

(ppm)

1,560

o n^n

1 7QO

c 1,510 ? ?i n

1 qon

2,klO

1,800

1,210 

1,810

1,540

1,850

1,350

1,710

1,500

1 ^PO

1 77O

440

1 770

D *} r\

5io

1,260

L -7r\

690

610

560

440

690

340

700 

120

150

130

5io

210

/L rjf\

350

£.or\

120

770

247 i,64o

2,OkO

I

D Q r\

1,680

1 sediment

Discharge 

(tons per day)

3,020 4,410

3,980

4,670

2 7OO

3,960

3,170 

3,860

3

oD r\ ,200

4,290

4,850

4,000

3 P7O

4,510 -ir'R 758

1,060

560

0*^*5 o33

2,000 

1,660

2,140

1,730 

1,620

1,250

1 Q?n

1,010 

1,610

303

379

351

1,350 r'L -! 567

1 77O -L, 1 f U 

&£.£.

1,590

311

j>, i jv 4,250

5,130

I;, 320

4,640

Gage 1 

height

1.34 -*- -^*-r 

i.*3

 ->Q

 ->£,

 7o

.66

.84

i.1

.97 

1.41

o r\ .o9

1.14

D-t .87

.90

.91 

.16

.21

1.41 

1.39

1.22

1.48

1.35

T OQ

1 JiQ

T 55

1.94

1.16

T Q Q

i c;?

1.44 

1.15

1.45

1.23

T 9A

1.65

.97

1.40 

-.09

-.10

.30

.07

.02

b Discharge measurement.

bb Discharge is average from two measurements made on this day.

c For one vertical only.

1 Staff gage located on right bank 650 ft above Pish and Wildlife Service Buffalo Bridge.

46
Table 4..--Sediment discharge measurements of the Niobrara River near Valentine, Nebr.

(normal sections)

Date

Wnir ? IQ^n -__

Do

Wmr °, _________

Pirt _ _ _ _

Do 

Wmr Q _________

Nov. 10 

Jan. 26, 1951 

Mmr ft __________ ria.y <~> 

May 9 

T)Q _ 

"Hr\

Mo IT P^ _____-._...-.

June 28 - ---

Tin -_--____---

Do

Tnl-v 17 ________

Do 

Time 

(mst )

11:30 a.m.

1:00 p.m. 

11:00 a.m.

12:00 m.

3:15 p.m.

3:30 p.m.

4:00 p.m.

1:00 p.m. 

1:14.5 p.m.

10:30 a.m.

1:00 p.m. 

11:55 a.m.

12:15 p.m.

1:00 p.m.

11:14.0 a.m.

10:4.0 a.m. 

12:30 p.m.

2:20 p.m.

11:4.0 a.m.

12:4.0 p.m.

1:10 p.m.

discharge 

(cfs)

b 701

b 718

, Q t b 814.3

b 804

b 840

i D 1 r* b 814.5

b

t-7O D

b 616

b 832

/ Qn

790

774

 7/r!

765 

757

1,050

1,010 

951

933

924

Do/

D o/

Do/

Suspendec

> Mean 

concentration 

(ppm)

rjQ /-,

770

700

1,040

1,340 

750

l,lj.OO

1,000

1,440

On T

758

D QT

c 2,680

/ X-lQ

563

752

490 

566

/ Q O

QrvQ

1 sediment

Discharge 

(tons per day)

A 1,480

C i )i on

A i con

C 2,260

A 3,040

D 1,710 

Cy 7tn

C 1,660

C

o poo

c 401

p i 7°,n

c 1,580

A' 1,820

D' 5,480

A' 1,710 

C 1,540

 " -L, 7 J*J

C T yzn

D' 1,4.10

c 1,520

D' 1,800

temperature

(Op)

£ 7

70

Gage 1 

height

0.50

.48

1.40 

-.15

-.10

-.10

-.10

"k t

.34

OUon

.07

.05 .014.

.02

.02

.02

b Discharge measurement.'

c This sample apparently contained bed material.

1 Staff gage located on right bank 650 ft above Pish and Wildlife Service Buffalo Bridge.

Note.--Capital letters indicate sections.

Table 5. Sediment discharge measurements of the Niobrara River near Sparks, Nebr.

Date

Oct. 23, 1950 --

"Wr\T- ^

Nov. 17 

Nov. 21 

Nov. 28 

non A _ __

riAr> 1 1 ________

t)Ar> ?0 ________

ri£>r> ?? ________

Jan. 10, 1951 

Tan ?6 --_---_-

 CI A V. oo ________

Mar. 27 

AjJ A ri ! Y» Q 7 -» -' -' -' « _

A-HY* 7O . ..-.

May 7 

Mnv Q __________

May 26 

June 22 

TTmp ?fi ________

TnT-rr A 

July 17 

Time 

(mst)

1:4.0 p.m.

11:4.0 a.m. 

l:l].0 p.m.

2:30 p.m.

11:35 a.m.

12:20 p.m.

2:4.0 p.m. 

12:35 p.m.

12:4.0 p.m. 

1:35 P.m.

1:00 p.m.

2:45 p.m. 

12:15 p.m.

1:30 p.m.

12:20 p.m. 

1:50 p.m.

1:35 p.m.

7:10 p.m. 

4:00 p.m.

12:15 p.m.

11:40 a.m.

12:14.0 p.m. 

5:00 p.m.

12:30 p.m. 

3:30 p.m.

discharge 

(cfs)

793

D n /

782

D r\\

817

a 250

1,140 

957

957

687

 7O£.

768

1,04.0 

517

897

Q Or"

Qo j

770

981

933

QQ r1

1,020

DD r*

839

Q D r*

Suspendec

Mean 

concentration 

(ppm)

700

*~7£. f~\

920

1,240

1,530

140

1,490

1,060

1,020

700 

237

llj.0

293 

520

1,900 

560 r'r'Q 558

r'D r\

1,240

1,010

r-'oD 528

1,5-90

697

/ r\O

510 / /-.D

1 sediment

Discharge 

(tons per day)

1,500

1,670

1,940 

2,690

3,370

94 

4,590

2,740 

2,614.0

1,300

471 

290

o o o

823

rjOA

4,600

1,340

i,35o

1,210 

3,280

1,330 

3,560

1,920 

1,450

1,160

1,450

temperature 

(°P)

49

Gage 

height

2.92

2.94

2 QT

2

O*3

2.99

o, o,p J*JC3.06

3.06

3.13

3.07

3.30 

2.55

2.92 

o en

o rn

2.90

3

j-»D

3. ol|.

3.00

3.20 

3.03

3.05

3.09

a Mean daily discharge.

47
Table 6. Comparison of suspended-sediment concentrations of measuring sections of the Niobrara River

to July 17, 1951

near Valentine and Sp

Date

Nov. 2 

Do 

Do 

Nov. 3 

Do 

TV* 

Do 

Do 

Do 

Do 

Nov. 9 

Do 

Nov. 10 - 

Do 

Nov. 17 -

TVi __

Do - _

Nov. 21 -

Do 

Nov. 22 - 

Do

Nov. 28 - 

Do 

Do 

Nov. 29 - 

Do 

Nov. 30 - 

Dec. 1 

Do 

Dec. U 

Do 

Dec. 6 

Do 

Dec. 8 

Dec. 11 - 

Do 

Section B

Time 

(mst)

2:30 p.m.

1:00 p.m.

2:15 p.m.

9:1*0 a.m. 

9:30 a.m.

10:00 a.m.

l*:00 p.m.

8:10 a.m. 

10:30 a.m. 

11:15 a.m.

t*:l*0 p.m.

10:10 a.m. 

3t05 p.m. 

2:30 p.m. 

8:55. a.m. 

12:00 m.

11:20 a.m. 

2:10 p.m.

3:30 p.m. 

1:25 p.m.

10:25 a.m. 

l*:25 p.m.

10:10 a.m.

Concentration 

(ppm)

""^560

2,030

1,790

2,210

1,990 

2,1*10

1,800

1,210

1,810 

i,5Uo 

1,850

1,350

1,710 

1,500

a 2,01*0 

1,320 

1,770

Ul*o

1,770

830 

a 1,1*90

510

670

For comparison

Time 

(mst)

11:30 a.m. 

1:00 p.m.

9:1*0 a.m.

11:00 a.m. 

12:00 m.

3:10 p.m. 

3:15 p.m.

1:00 p.m.

11:UO a.m.

1:1*5 p.m.

12:30 p.m.

12:25 p.m.

9:35 a.m.

10:20 a.m.

Estimated 

concentration 

(ppm)

1,560 

1,560

2,01*0

1,960 

1,880

1,71*0

1,750

1,900

2,1*00 

2,1*00

1,500

1,780

81*0

670

Section A

Time 

(mst)

11:30 a.m.

11:00 a.m.

3:15 p.m.

 

Concentration 

(ppm)

780

700

1,31*0

_______

Percentage of 

concentration 

at section B

50

36

77

________

Section C

Time 

(mst)

1:00 p.m.

12:00 m.

1*:00 p.m.

1:00 p.m.

1:1*5 p.m.

Concentration 

(ppm)

770

1,01*0

1,1*00

1,000

i,UUo

Percentage of 

concentration 

at section B

U9

55

63

53

60

Section D

Time 

(mst)

3:30 p.m.

Concentration 

(ppm)

750

Pe

a

co

tr

at 

t
uo 

Dec. 12 - 

Do 

Dec. 13 - 

Do 

Dec. 1U -

Do 

Do 

Dec. 20 -

Do 

Dec. 21 -

DoDec. 22 -

Do 

Do 

Jan. 26 - 

Do 

T\r\ _ _.

May 8 - 

May 9 

Do 

Do 

Do _ __

May 23 

Do 

no _-

June 28 -

Do 

Do 

Do 

July 1? - 

Do 

TW-i ____

no --

TWi _ _

j:i>u p.m. 

10:00 a.m. 

3ilO p.m. 

10:UO a.m. 

U:U5*p.m.

8:UO a.m.

U:00 p.m. 

9:15 a.m.

UrOO p.m. 

8:U5 a.m. 

12:00 m.

3:U5 p.m. 

8:UO a.m.

11:20 a.m.

10: 50 a.m.

oyu 

610 

560 

UUO 

690

3UO

700 

210

670 

350 

a 520

620 

12O

770

2U7

12:UO p.m.

10:35 a.m.

10:UO a.m.

10:30 a.m.

11:00 a.m.

520

300

680

2U7

2U7

Section B

12:00 m.

11:30 a.m.

12:25 p.m.

11:UO a.m.

 

1,6UO 

2,OUO

1

QQ/-V

1,680

2,080

_______

1:00 p.m.

11:55 a.m.

12:15 p.m.

12:53 p.m.

11:15 a.m.

11:UO a.m.

2:00 p.m. 

10:UO a.m*

12:30 p.m.

2:13 p.m.

11:UO a.m. 

12:liO p.m.

1:30 p.m.

1,510

2,OUO

2,050

2,060

2,560

1,890

1,870

1,770 

1,710

1,670

1,680 

1,690

2,080 

2,020

2,010 

2,010

Section A 1

__________

12:15 p.m.

11:15 a.m.

__________

10:UO a.m.

__________

11:UO a.m.

_______

881

602

_______

752

 

982

________

U3

32

________

uu

 

U7

10:30 a.m. 218

-

88

Section C

1:00 p.m.

11:55 a.m.

11:UO a.m.

12:30 p.m.

12:liO p.m.

811

758

 563

U90

683

5U

37

30

29

3U

Section D 1

2:20 p.m.

1:10 p.m.

556

808

a From point-integrated samples.
Table 7« Suspended-sediment concentrations at cross sections of the Niobrara River near 

Valentine and Sparks, Nebr., from Nov. 2, 1950, to July 17, 195l, in average percentage of the concentration at the contracted section B

Section

C ____ 

D' -

D -

All noi

Sparks

Sparks 

1950,

gaging station (Nov. 2 to 17, 

and May 8 to July 17, 195l) 

Number of concentration 

comparisons with section B

3

4

11 

2 

1

21

14

6

Average concentration in 

percent of concentration 

at section B

42

50 

\1>

47

97

41

Table 8. Daily suspended-sediment discharge of the Niobrara River near Valentine, section B_, and

near Sparks, Nebr., 1950-51 water year

Niobrara River near Valentine, section B Niobrara River near Sparks

Date

Nov. 28 

29 

30 

Dec. 1 

2 

3

k

6 

1

8 

9 

10 

11 

12 

13

%

16 

17 

18 

19 

20 

21

Total

Water 

discharge 

(cfs)

1,090 

986 

926 

952

714

431^ 

541 

27^

228 

384

^ 614

833 

1,040 

1,090

1,000

960

901 

850 950

900

94^ 

986

944

19,035

Concentration 

(ppm)

1,600 

1,630

1,520

450

1,300 

930

860

690 

600 

560

530 

200

280

380 

450

Sediment 

discharge 

(tons per day)

I*, 700

4,300 

3,800 

3,900 

2,200 

680 

660 

960

570 

810 

1,100

1,700

2,000 

1,900

1,800 

i,5oo

1,400 

490 

320 

1^90

530 

710

1,000 

1,100

38,620

Date

Nov. 28 

29 

30 

Dec. 1 

2 

- 3

\

6

7 

8 

9 

10 

11 

12 

13

14 

15 

16

17 

18

19 

20 

21

Total

Water 

discharge 

(cfs)

1,000 

957 

885 

885 

720 

450 

520 

300

250

400

5oo 

65o 

850 

1,050

1,100 

1,100

1,020 

957 

897 

969 

921 

945 

957 

969

19,252

Concentration 

(ppm)

1,380 

1,460 

1,540 

1,570

140

690 

1,050 

790 

910 

1,100 

1,160

1,100 

1,020 

1,020 

1,110 

1,340 

1,110 

1,060 

1,180

Sediment 

discharge 

(tons per day)

3,730 

3,770 

3,680 

3,750 

1,230 

430 

590

170

90 

330 

930 

1,840 

1,810 

2,580 3,270

3,45o

3,030 

2,640 

2,470 

2,900 

2,830 

2,830 

2,740 

3,090

54,180

Table 9.--Slope observations on the Niobrara River near Sparks, Nebr.

Date

June 24, 1950 

July 13 

T-nl-y ^0 - __-.-. -------

J± ULgj X 7 

J± LL^j ( ^

-H. Ll^j * < *-*

Aug. 30 

Sept. 15 

Nov. 3 

Nov. 21 

Do 

A

Time 

(mst )

1:00 p.m.

10:40 a.m.

10:00 a.m.

10:10 a.m.

10:20 a.m.

7:50 a.m.

5:40 p.m.

12:35 P.m.

1:45 p.m.

Staff 

reading 

(feet)

I].. 20

1 *~i /

4.20

4.23

1 n O

4.13

i / «

4.63

1 o O

1 o /

4.10

4.15

Recorder 

reading 

(feet)

3.03

2.96

2 oA

 > Q).

2

O T~J

3.25

2.94

? Q?

2.9^

O QO

Difference 

(feet)

1.17

1.30

1.24

-!- * /

1

o£.

1

f\ Q

-i "i 1 1.34 

1.3U

1.16

1.22

1.22

Slope 

(ft per mile)

6.94

7.71

 7 O i.

7

i. r" .05

7.48

8.19

7.95

7.95

6

6 Q

7.24

7 ?)i

7.51

Note. Staff gage and Sparks recorder set to same datum. Staff gage on right bank 890 ft upstream from recorder.

50
Table 10. particle-size analyses of suspended sediment (point-integrated samples), Niobrara River near Valentine, Nebr.

/Sethods of analysis: S, sieve; W, in distilled water/ 

Date

Nov. 30, 1950 

Do 

Do 

TV*

Do 

Do 

Do 

Do 

Do 

TV, ________

Do 

Do 

Do 

TV* ... _____

Do 

Do 

Do 

Do 

Do 

Do 

T\_

Do 

Do 

Do 

T) n ____ _ _

Tin ________

Do - 

nn __ ____

Do 

Do 

Do 

Do 

TV) 

Time 

(mst)

U:Ul p.m. 

U:08 p.m. 

3:38 p.m. 

3:31 P.m.

3:2U p.m. 

3:20 p.m. 

3:lU p.m. 

3:05 p.m.

2:59 p.m. 

2:5U p.m. 

2:U8 p.m. 

2:U3 p.m.

2:36 p.m. 

2:32 p.m. 

2:16 p.m. 

2:10 p.m.

2:03 p.m. 

1:58 p.m. 

1:U9 p.m. 

1:UO p.m.

1:32 p.m. 

1:29 p.m. 

1:19 p.m. 

l:lU p.m.

1:07 p.m. 

1:01 p.m. 

12:57 p.m. 

12:21 p.m.

3:18 p.m. 

3:lU p.m. 

3:10 p.m. 

3:02 p.m.

2:U8 p.m. 

2:U2 p.m. 

2:36 p.m. 

?-^? n.m.

Water 

discharge 

(cfs)

926 

926 

926 

926

926 

926 

926 

926

926 

926 

926 

926

926 

926 

926 

926

926 

926 

926 

926

926 

926 

926 

926

926 

926 

926 

926

38U 

38U 

38U 

3SU

38U 

38U 

38U

^Rh

Sampling 

station

u 

u 

u 

u

9 

9 

9 

9

12 

12 

12 

12

16 

16 

16

16

19 

19 

19 

19

22 

22 

22 

22

26 

26 

26 

26

U 

U 

U 

U

8 

8 

8

R

Total 

depth 

(feet)

3.7 

3.7 

3.7 

3.7

U.I 

U.I 

U.I 

U.I

U.2 

U.2 

U.2 

U.2

U.5 

U.5 

U.5 

U.5

U.6 

U.6 

U.6 

U.6

U.2 

U.2 

U.2 

U.2

U.i 

U.I

U.i 

U.i

2.5 

2.5

2.5 

2.5

3.3 

3. .3 

3.3 

^.^

Suspended sediment

Sampling point

Velocity 

(fps)

8.7U 

9.59 

U.16 

6.68

9.50 

10.86 

9.98 

7.6U

12.96 

11.66 

10.12 

6.51

10.05

10. 8U

10. U5

7.28

10.52

11.00 

9.8U 

U.38

8.0U 

9.01 

9.79 

U.6U

6.UO 

7.16 

6.8U 

.60

3.U7 

U.U6 

U.oo

2.30

'U.18 

U.OU 

U.52

^-CK

Depth 

(feet)

0.5 

1.9 

2.2 

3.2

.5 

1.6 

2.6 

3.6

.5 

1.6 

2.7 

3.7

.5 

1.7 

2.9 

U.o

.5 

1.6 

2.9 

U.i

.5 

1.6 

2.7 

3.7

1.0 

1.6 

2.6 

3.6

.5

1.0

1.5

2.0

.5

1.2 

2.0 

?.R

Concentration 

(ppm)

5,oUo

5,720

5,870

3,010 

3,080 

2,7UO 

2,130

2,180 

2,3UO

i,55o

1,260

1,570 

1,660 

l,3Uo 

1,220

1,2UO 

1,150

1,150

1,070

620 

780 

710 

870

5io 

6UO 

630 

660

1,660

2, QUO 

2,650 

6,980

1,700 

2,060 

2,700 

^.6^0

Percent finer than indicated size

0.002 O.OOU 0.008 0.016 0.031 0.062

U 

3 

3

6 

5 

6 

8

8 

7 

10 

12

10 

10 

12 

12

12

1U 

15 

16

22 

18 

17 

15

23

21 

20 

21

5 

U 

U 

1

6 

5 

U 

 *

0.125

15

12 

12

21 

20 

20 

2U

27 

25 

31 

38

3U 

33 

38 

38

U2 

U3 

U6 

U7

62

5U 

53 

U7

63

58 

58 

53

22 

19 

16 

8

23

20 

18 

-K
Table 10. Particle-size analyses of suspended sediment (point-integrated samples), Niobrara River near Valentine, Nebr., se

/Methods of analysis: S, sieve; W, in distilled water/ 

Date

Dec. 7, 1950 

Do * 

T\n _

Do 

Do 

Tin ___ ___

T\n ____ __ __

Tli-i __ _

Do 

Do 

T\n .......

Do -» ._- 

TVi ..... ..

Do 

no _ -

Dec. 21 

TV) ________

TVi ________

Do 

TV) __ __ ____

Do 

TV) ________

TVi __ _ _ lyw ________

Do _______

Do 

Do 

Do 

TV> 

Time 

(mst)

2:27 p.m. 

2:2U p.m. 

2:12 p.m. 

2:02 p.m.

1:56 p.m. 

1:52 p.m. 

1:33 p.m. 

1:26 p.m.

1:11 p.m. 

1:06 p.m. 

1:02 p.m. 

12:56 p.m.

12:08 p.m. 

12:16 p.m. 

12:02 p.m. 

11:57 a.m.

11:50 a.m. 

11:14; a.m. 

11:38 a.m. 

11:30 a.m-.

12:U8 p.m. 

12:U5 p.m. 

12jU2 p.m. 

12:35 p.m.

12:30 p.m. 

12:10 p.m. 

12:05 p.m. 

12:05 p.m.

12:00 m. 

11:55 a.m. 

11:55 a.m. 

11:50 a.m.

11:U5 a.m. 

11:UO a.m. 

11:35 a.m. 

11:35 a.m.

11:30 a.m. 

11:30 a.m. 

11«2^ a.m.

Water 

discharge 

(cfs)

38U 

38U 

38U 

38U

38U 

38U 

381; 

381;

381; 

381; 

381; 

381;

381; 

381; 

381; 

381;

381; 

381; 

381; 

381;

918 

910 

910 

892

88U 

8U2 

1 821; 

821;

808 

790 

790 

782

765 

7U8 

7UO 

7UO

722 

722 

711i

Sampling 

station

12 

12 

12 

12

16 

16 

16 

16

19 

19 

19 

19

22 

22 

22 

22

25 

25 

25 

25

u 

u

U 

U

9 

9 

9 

9

11; 

U» 

1U

u»

19 

19 

19 

19

21; 

21; 

2),

Total 

depth 

(feet)

3.0 

3.0 

3.0 

3.0

3.2 

3.2 

3.2 

3.2

3.6 

3.6 

3.6 

3.6

3.5 

3.5 

3.5 

3.5

3.8 

3.8 

3.8 

3.8

3.5 

3.5 

3.5 

3.5

3.5 

3.5 

3.5 

3.5

3.7 

3.7 

3.7 

3.7

U.6 

U.6 

U.6 

U.6

U.5 

U.5 

L.^

Suspended sediment

Sampling point

Velocity 

(fps)

6.18 

5.02 

3.U8 

1.61;

3.78 

5.21 

2.85 

1.51;

5.37 

5.70 

5.33

2.05

3.59 

5.11 

2.38 

2.10

2.UU 

3.20 

1.00 

1.08

10.36 

10.32 

10.56 

10.11

7.U6 

12.78 

11.36 

9.81;

10. U8 

11.80 

11.39 

10.12

8.5U 

11.61 

10.56 

6.9U

6.10; 

8.30 

9.2)1

Depth 

(feet)

o.5 

1.1 

1.7 

2.5

.5. 

1.3 

2.0 

2.7

.5 

l.l; 

2.3 

3.1

.5 

1.3 

2.2 

3.0

.5 

i.U

2.9 

3.3

.5 

1.7

2.1; 

3.0

.5 

1.7 

2.1; 

3.0

.u

1.8 

2.5 

3.2

.5 

2.3 

3.2 

U.I

.u

1.8 

^.n

Concentration 

(ppm)

1,720 

1,960 

2,300 

2,600

1,220 

1,310 

1,170 

1,610

790 

820 

750 

810

560 

580 

570

600

530 

560 

670 

650

1,300 

1,820 

1,920 

1,760

890 

1,170 

780 

610

310 

U60 

U20

380

200 

310 

320 

360

3UO 

320 

no

Percent finer than indicated size, 

0.002 O.OOU 0.008 0.016 0.031

.

0.062

7 

6 

5 

U

7 

6 

7

5

9 

8 

7

8

1U 

12 

12 

12

15 

13 

13 

10

7 

5 

U 

U

8 

6 

9

11

20

15 

15 

16

28 

18 

16 

16

18

17 

?i

0.125

27 

25 

22 

20

30 

29 

28 

2U

38 

3U 

31 

30

Ui 

38 

38 

36

U2 

38 

36 

32

18 

13 

11 

12

21 

16 

22 

27

U3 

33 

36 

36

59 

Ul 

Ul 

39

U7 

U8

),7
S9

oooo oooo 

1 1 1 1 1 

j j 

POPOPOPO UjVjJUJVjJ 

CH

O O (D O O O 

PO 

CO

1

1 

1

O O O O O O 

!

S

1? $% 

a>

i i 

H vnvnvnvn ON vn o\ ON-ON ON POPOPOPO 

UJ PO H H H H Vxvnp- U) PO H fOU) 

P-UJ O H ro U) ONUTP-H J H H O\ 

*T3 *£i *T3 *O *£i *T3 *T3 *T3 

3333 3333 

PO p-UJ p-U) O UT PO U> 

O CO H O CO p- ->] POCO 

fu T3T3T3T3 CT3 1 T3T3T3T3 T3 >C >C O 

3 33 33 33 33 33 3333 

oooo

CDCOCOCO

->]->]->]->] 

vnurvj-ivn

ropot-oro

cocococo

p ^^^^ u,u, P-P-P-P- ^^^^ P-p-p-t- P-P-^-PVJ CD -<J ON VJ~i Co ON *J ~^3 ON ^^ ~^3 Co ON vn VJT CD p--^3 -^3 ON VJ~i P- 

- ->ICOCOUT U)co OOVJION H->icoco P-HOCD ->iONUJPO 

^ O UT O co NO PO PO H UT->] co PO UT O O cop-->] ON co p- ro 

P POroH *-jJ P-POH UJPOH P-(^JH p-UJH 

c -jp-rovn POVJI HCOONVR ropopovn. roo->]vn UJO->avn 

M ON p-U) p-VjJ H H H H 

OO r\3OOO HONO^O 

PO ro ro ro vn^J^P-^J^ 

VjJ VA J ' 1ON o rsD ^O VJ~l CD 

OsO ro J Ol- J l- VSHP-O 

8

VJION CONONO^O OOQ 

ro-j p-h-'Mp- 000 

C^^O

O

o

i

coco cococoos cocococo 

sis; s:s;s;s: s;s;s;s; 

H 

ONp-vn O 

P ->]POONP- coco poporopo 

(N ov3->Jco ijjso corocovn 

c oooo P-P- o PO o o 

1 

1

1

1

11

11

1

1 

1 

1 

1 

1

I

r ro PO ro 

c ONVR *J~i 

oof ON<-JJ 

h J l- J l- H 

C O O O 

c o o o 

1

1 1 1

1

11

1 1 11

!

i

h H H H 0 

vj MrOf^oro OO <J 

^ H H \jj UJ j\ 

V \Op-O ON ON ro ~ 

_j 

c p-vn-jp- Bco\o 

vj co o p- PO J l- o 

H 1 

C ON CONO -J 

H H 

O O 

0 0 

i i i 

i i 

o cocococo coco cocococo 
Table 11. Particle-size analyses of_suspended sediment, Niobrara River near Valentine, Nebr.

/Methods of analysis: S, sieve; W, in distilled water/

section B, 

DateNov. 2, 1950 

Nov. 3 

Nov 10 - __ __ __

Nov. 17 

Do 

Nov. 22 

Tin ____

Nov. 28 

Do

Do 

en n«P ), _ __ _

T\i-\

TJor* 1 9 - 

T\c*r* 1 1. __. _

Tin - ._ ...... -

T\n - _

Do

Dec. 20 

Do

Dec 22 - __ _

Mav fi. IQCl 

Time 

(mst)

2:30 p.m. 

10:00 a.m. 

1:00 p.m. 

2:15 p.m. 

9:UO a.m.

9:30 a.m. 

10:00 a.m. 

U:00 p.m. 

8:10 a.m. 

10:30 a.m.

11:15 a.m. 

lj.:I|.0 p.m. 

10:10 a.m. 

3:05 p.m. 

8:55 a.m.

12:00 m. 

11:20 a.m. 

2:10 p.m. 

3:30 p.m. 

10:25 a.m.

14:25 p.m. 

10:10 a.m. 

3:50 p.m. 

10:00 a.m. 

3:10 p.m.

10:UO a.m. 

ksk5 p.m. 

8:UO a.m. 

U:00 p.m. 

8:140 a.m.

11:00 a.m. 

10:05 a.m. 

U:00 p.m. 

9:15 a.m. 

U:00 p.m.

8;i*5 a.m. 

3:U5 p.m. 

8:UO a.m. 

11:20 a.m.

^ 10 n.iB.

Water 

discharge 

(cfs)

b 718 

b 80U 

bb 8214 

782 

502

816 

969 

790 

790

858 

1,330 

867 

1,080 

918

638 

222 

250 

605

589 

918 

1,150

1,050

1,070

1,050 

1,030 

1,100 

850 

935

935 

1,000 

978 

1,000 

978

916 

952 

960 

1,000

fill?

Suspended sediment

Concentration of 

sample 

(ppm)

1,560 

2,030 

1,790 

2,210 

1,990

2,1(10 

1,800 

1,210 

1,810

1,850 

1,350 

1,710 

1,500

1,320 

1,770

kkO

1,770 

830 

510

1,260 

670 

690 

610 

560

690 

3UO 

700 

120

150 

130 

510

210

670

350 

620 

120 

770

1 .fllf)

Percent finer than indicated size, in millim

0.002

'

0.0014 0.008 0.016 0.031 0.062

6 

5 

6 

6 

5

k 

5

u

5

7 

8 

6 

9

11

11 

5

2 

3

14 

k

7 

9

5 

7

7 

5 

3 

8 

214

17 

18 

8 

13 

8

10 

12 

32 

10

%

0.125

21 

17 

18 

26 

21

20 

19

12 

1)4

25 

26 

18 

30 

33

30 

17 

10 

22 

17

25 

29 

38 

22 

31

21 

20 

12 

29

37 

27 

17 

21 

28

21 

29 

Ul 

214

??

0.250

75 

73 

68 

72 

70

69

714

62 

61;

66 

65 

59 

69

714

68 

67 

55 

6U 

66

70 

65 

76 

68 

81

76 

67 

62 

70

55

71 

55 

57 

U8 

61

56 

57 

59 

61

71,
May 9 

May 23 

June 28 

July 17 

12:00 m.

12:30 p.m.

1:25 p.m. 

12:UO p.m.-

771

1,010

QCt9

Oo X

2,OUO

1,680

3

15

3

12

15

. 16

20

75

66

XQ

«Q

78

b Discharge measurement.

bb Discharge is average of two measurements made on this day.

Table 12. Particle-size analyses of suspended sediment, Niobrara River near Valentine, Nebr., normal sections

/Methods of analysis: S, sieve; W, in distilled water/

Date

Nov. 2, 1950 -

Do 

Nov. 3 

Do 

Do 

Nov. 9 

Nov. 10 

Nov. 17 

Jan. 26, 1951-

May 8 

May 9 

Do 

Do 

May 23 

Do 

June 28 

nn ___ ___ _

Do 

July 17 

Do 

Do 

Time 

(mst)

11:30 a.m. 

1:00 p.m. 

11:00 a.m. 

12:00 m. 

3:15 p.m.

3:30 p.m. 

U:00 p.m. 

1:00 p.m. 

1:U5 p.m.

11:30 a.m. 

2:00 p.m. 

12:15 p.m. 

11:55 a.m. 

1:00 p.m.

12:15 p.m. 

12:UO p.m. 

11:UO a.m. 

1:30 p.m. 

2:20 p.m.

12;UO p.m. 

1:UO p.m. 

2:10 p.m.

Water 

discharge 

(cfs)

b 701 

b 718 

b 8U3 

b SOU 

b 8UO

b8U5 

b.728 

b 616 

b 832

681 

790 

765 

77U 

757

1,050 

1,010 

951 

933 

92U

826 

826 

826

Suspended sediment

Concentration of 

sample 

(ppm)

780 

770 

700

i,oUo

1,3UO 

750

i,Uoo

1,000

i,UUo

218 

811 

881 

758 

2,680

602 

563 

752 

U90 

566

982 

683 

808

Percent finer than indicated size, in millimeters

0.002 O.OOU 0.008 0.016 0.031 0.062

16 

9 

12 

8 

6

10 

6

31 

6

10 

8 

5 

7

19 

19 

15 

19 

3U

8 

13 

10

0.125

35 

3U 

29 

28 

28

3U 

3U 

3U 

32

26 38' 

2U 

32

36 

38 

32 

39 

35

Ul 

U6 

U3

0.250

92

9U 

88 

90 

80

92 

9U 

86 

92

80 

92 

92 

87

9U 

90 

100 

100 

100

98 

96 

91

o.5oo

100 

100 

100 

100 

100

100 

100 

100 

100

99 

100

«

100

1

b Discharge measurement.
Table 13« Particle-size analyses of suspended sediment, Niobrara River near Sparks, Nebr., 1950-51 w

/Methods of analysis: S, sieve; W, in distilled water/

Date

Oct. 23, 1950 

Jan. 10, 1951 

TTah 99 

Mar. 27 

Mair O

M air 9 "3

Tnl tr 1 7

Time 

(mst)

l:iiO p.m. 

11:UO a.m. 

2:30 p.m. 

2:25 p.m. 

11:35 a.m.

12:20 p.m. 

2:UO p.m. 

12:35 p.m. 

1:35 p.m. 

2:U5 p.m.

1:30 p.m. 

7:10 p.m. 

5:00 p.m. 

6:00 p.m. 

12:30 p.m. 

U:30 p.m.

Water 

discharge 

(cfs)

793 

816 

SOU 

817 

a 250

l,lltO

957 

957 

736 

i,oUo

897 

981 

981 

885 

839 

885

Suspended sediment

Concentration of 

sample 

(ppm)

700 

760 

l,2ltO 

1,530

lUo

1,U90 

1,060 

1,020 

237 

293

1,900 

1,2UO 

1,010 

608 

510 

608

Percent finer than indicated size, in millime

0.002 .O.OOU 0.008 0.016 0.031 0.062

12 

8 

8 

8 

25

9 

8 

5 

12

25

23 

1U 

1U 

18 

16

10

0.125

53 

38 

30 

27 U3 '

32 

27 

18 

3U 

U9

59 

31 

35 

U2 

hh 

hi

0.250

95 

96 

82 

76 

90

83 

79 

75 

89 

8U

90 

88 

85 

9h 

96 

92

a Mean daily discharge.

Table llu Particle-size analyses of bed material, Niobrara River near Valentine, Nebr., normal se

/Analysis by sieve only/

Date

Nnv ? 1 Q tiO - - __ -

Nov 9 - ____ - ___ - -

Nov. 10 

Jan. 26, 1951 

MQTT Q .

MflV 9^

ria$ c*j 

Do

TV-» _ ,__-.___ _____ _-

June 28 

Do

JjQ ___ ______ __ __ _ ____ ____ __ _

July 17 

Do

Do LflJ

Number 

of 

sampling 

points

h 

3 

2 

3 

3

3 

3 

3 

3 

3 '

2 

3 

3 

3 

3

Deposited sediment

Percent finer than indicated size, in millimeters

o.ooU 0.008 0.016 0.031 0.062

0 

0 

0 

0 

0

0 

0 

0 

0 

0

0 

0 

1 

3 

2

0.125

1 

7

2 

23 

3

2 

3 

5 

h 

3

2 

2 

3 

6 

h

0.250

30 

70 

3h 

53 

29

36 

ho 

60 

63 

U7

36 

3h 

hh 

h9 

U5

0.500

96 

96 

9h 

98 

85

97 

95 

96 

99 

98

95 

88 

98 

90 

67

1.000

100 

97 

99 

100 

99

100 

100 

98 

100 

100

99 

97 

100 

95 

90
Table 15. Particle-size analyses of bed material, Niobrara River near Sparks, Nebr.

/Analysis by sieve only/

Date

Nov. 21, 1950- 

Nov. 28 

Dec. lU 

May 9, 1951 

iidjr C.J

June 28 

July 17 

Number 

of 

sampling 

points

3 

3 

3

3 

3

2 

3 

3

3 

3

Deposited sediment

Percent finer than indicated size, in millimeters

O.OOU 0.008 0.016 0.031 0.062

0 

k

1

1 

2

0

1 

0

0 

0

0.125

13 

35 

20

11

5

5 

3 

2

2 

3

0.250

81 

68 

79

75 

U3

72 

37 

U2

36 

39

0.500

100 

100 

99

99

88

99

85 

98

92 

95

1.000

100

100 

97

100 

9U 

100

98 

100

2.000

99

96

99