Herd Creek
General Information
Herd Creek is a tributary of the East Fork of the Salmon River. The study reach is
a 600 ft length of stream about 1.6 miles upstream from the confluence with the East
Fork Salmon River. The site is below the Bennett Ranch on land administered by the
Bureau of Land Management at an elevation of about 5,900 ft above sea level. The
drainage area is 110 mi2 and the geology of the watershed is predominantly mixed
volcanics.
In 1994 and 1995, personnel of Case Western Reserve University established a
stream gage and measured sediment transport and streamflow at this site. Additional
measurements included a survey of the stream reach, pebble counts of the substrate
surface and transport distance of painted rocks during high flows. Figures 1 and 2 show
photographs of Herd Creek looking upstream and downstream from the measurement
location for stream discharge and sediment transport.
Figure 1. Herd Creek looking upstream from the measurement site.
Figure 2. Herd Creek looking downstream from the measurement site.
Streamflow was recorded for water years 1994 and 1995 from the beginning of
the spring snowmelt hydrograph until fall. Estimated average annual streamflow (Qa) for
the stream is 46.2 ft3/s and the estimated bankfull discharge (Qb) is 193 ft3/s. Stream
discharge was recorded in 1994 from May 5 to October 22. Stream discharge was very
low in 1994 and the largest daily mean discharge was only 42 ft3/s. In 1995, stream
discharge was recorded from April 20 to November 2 and the largest daily mean
discharge recorded was 275 ft3/s on June 28, well above bankfull discharge.
Channel Profile and Cross-Section
Figure 3 shows the longitudinal profile for the channel bed in the center of the
channel, the water surface elevations along each bank at the time of the survey and
bankfull flow elevations (floodplains). The average gradient for the study reach is 0.0077
ft/ft. Cross-sections of the channel were surveyed at four locations. Discharge and
sediment transport measurements were made at cross-section 1 (XS1) and the movement
of painted rocks during the spring and early summer snowmelt flows in 1995 were
measured at two transects (PR transects in Figure 3) about 39 and 56 ft downstream of
XS1.
168
166
164
XS3
162
XS4
160
XS2
158
XS1
PR Transects
156
0
100
200
300
400
500
600
700
Distance, ft
Figure 3. Longitudinal profile of the study reach in Herd Creek.
180
Herd Creek
175
Elevation, ft
Elevation, ft
Water Surface Elevation Left Edge
Center of Channel Bed Elevation
Water Surface Elevation Right Edge
Bankfull Elevation Left Side
Bankfull Elevation Right Side
Herd Creek
Cross-section 1
170
165
Qb
Qa
160
155
0
10
20
30
40
50
60
70
Distance, ft
Figure 4. Cross-section of Herd Creek at the sediment transport measurement
site.
80
Channel Geometry
Figure 4 shows the cross-section at the sediment transport measurement site,
cross-section 1. The channel geometry relationships for this cross-section are shown in
Figure 5. All data collected in 1994 and 1995 were used to develop the displayed power
relationships with discharge. Over the range of discharges when sediment transport was
measured (10.2 to 287 ft3/s) estimated stream width, estimated average depth and
estimated average velocity varied from 23.9 to 30.31 ft, 0.40 to 1.89 ft, and 1.1 to 5.0 ft/s,
respectively. The average reach gradient is 0.0077 ft/ft.
10
100
Width
0.071
y = 20.23x
2
R = 0.91
10
Velocity, ft/s
Depth and Width, ft
Herd Creek
Average Depth
0.468
y = 0.134x
2
R = 0.99
1
Average Velocity
0.460
y = 0.370x
2
R = 0.99
Average Depth
Top Width
Average Velocity
0.1
1
10
100
3
Discharge, ft /s
Figure 5. Width, average depth and average velocity versus stream
discharge at the measurement cross-section on Herd Creek.
1
1000
Channel Material
Surface pebble counts were made along four transects near cross-section 1 in July
1994. No subsurface core samples were collected at this site. The average D50 and D90
for the surface material was 67 mm and 122 mm, respectively (Figure 6).
100
Herd Creek
90
80
Percent Finer
70
60
50
40
30
20
10
Measurement Data:
July 1, 1994
0
1
10
100
1000
Particle Size, mm
Figure 6. Particle size distribution for surface material samples in Herd Creek.
Sediment Transport
Sediment transport measurements made in 1994 and 1995 include 72
measurements of bedload transport and 23 measurements of suspended sediment
transport. Sediment transport measurements spanned a range of stream discharges from
10.2 ft3/s (0.22Qa; 0.05Qb) to 287 ft3/s (6.21Qa; 1.49Qb). Bedload transport ranged from
0.000964 to 60.2 t/d and suspended transport ranged from 0.265 to 218 t/d. Over the
range of measured discharges, suspended transport accounts for the majority of the
material in transport with a four to over five fold greater transport rate than the bedload
transport rate (Figure 7).
1000
Herd Creek
Sediment Transport, tons/day
100
10
Suspended
2.397
y = 2.441E-04x
2
R = 0.95
BCF=1.149
1
0.1
Total Bedload
2.458
y = 3.949E-05x
2
R = 0.83
BCF=1.596
0.01
0.001
Total Bedload
Suspended
Qa
Qb
0.0001
1
10
100
Discharge, ft3/s
Figure 7. Bedload and suspended load transport rate versus discharge.
1000
The bedload transport rates by size class (Figure 8) shows that the larger rates are
associated with material in the 0.5 to 2mm diameter size class. No curve fitting was done
for sediment >32mm diameter since only nine of the samples contained this size class of
material. All discharges transporting material >32mm exceeded 100 ft3/s.
100
Herd Creek
Bedload Transport, tons/day
10
<0.5 mm
1.910
y = 6.625E-05x
2
R = 0.80
1
0.5 - 2 mm
2.246
y = 3.441E-05x
2
R = 0.80
0.1
2 - 8 mm
2.680
y = 3.156E-06x
2
R = 0.74
0.01
8 - 32 mm
2.597
y = 3.920E-06x
2
R = 0.76
0.001
Qa
Qb
<0.5 mm
0.5 - 2 mm
2 - 8 mm
8 - 32 mm
>32 mm
0.0001
1
10
100
1000
Discharge, ft3/sec
Figure 8. Bedload transport rate versus discharge for selected size classes.
The size of the largest particle in the bedload sample increased with discharge
(Figure 9). The largest particle measured in a bedload sample was 60.5 mm at a
discharge of 95.7 ft3/s. At discharges greater than bankfull (193 ft3/s) the largest particle
usually exceeded 40 mm. There is also a trend of increasing median size of the bedload
sample with increasing discharge. The D50 for most of the bedload samples was in the
sand size, 0.5 to 2.0 mm. The largest median diameter of a bedload sample was 9.7 mm.
The information on the largest particle in the bedload sample and observations of painted
rock movement suggest that discharges at or slightly above the bankfull discharge are
capable of moving the median diameter particles on the channel surface.
1000
Herd Creek
Particle Size, mm
100
Largest Painted
Rock Moved in
1995
D50 Surface
Substrate
R2 = 0.70
10
R2 = 0.41
1
Qb
Qa
Median Diameter
Largest Particler
0.1
1
10
100
3
1000
Discharge, ft /s
Figure 9. Median size of the bedload sample and the largest particle size versus
stream discharge for Herd Creek.
Painted Rock Transport
A total of forty painted rocks were placed across two transects (twenty per
transect) on April 27, 1995. Daily mean discharge on the day of rock placement was
18.75 ft3/s. The size of the rocks ranged from 38 to 115 mm diameter (b-axis) which
represents the D17 up to the D89 of the surface particle size distribution measured at crosssection 1. Transport of the rocks as of July 12, 1995 are shown in Figures 10 and 11.
18
Herd Creek
16
Painted Rocks
Transect 1
Downstream Distance Moved, ft
14
12
10
8
Particle B-axis, mm
6
57
103
4
111
91
M
115
53
43
82
M M
72
38
72
114
48
103
50
74
97
77
102
55
M
2
0
14.8
15.7
16.7
17.7
18.7
19.7
20.7
21.6
22.6
23.6
24.6
25.6
26.6
27.6
28.5
29.5
30.5
31.5
32.5
33.5
Distance from Left Stake, ft
Figure 10. Transport distance of painted rocks at transect 1.
14
Herd Creek
Painted Rocks
Transect 2
Downstream Distance Moved, ft
12
10
8
6
Particle B-axis, mm
4
2
78
76
88
78
M
51
M
102
M
95
124
M
93
M
75
52 105
M M
99
64
43
M
M
69
M
52
45
M
60
64
0
17.2
18.0
18.9
19.7
20.5
21.3
22.1
23.0
23.8
24.6
25.4
26.2
27.1
27.9
28.7
Distance from Left Stake, ft
Figure 11 Transport distance of painted rocks at transect 2.
29.5
30.3
31.2
32.0
32.8
Twenty five of the forty rocks were found. Of those found, only two had not
moved. The maximum transport distance was 15.4 ft for a 82mm diameter rock and the
average was transport distance was 4.5 ft. The largest daily mean discharge during this
period was 275 ft3/s on June 28, 1995 and the largest instantaneous discharge was 342
ft3/s.