7930

• UCREFRP Catalog Number: 7930
• Author: Ketcheson, G. L.
• Title: Sediment Rating Equations
• USFW Year: 1986.
• USFW - Doc Type: An Evaluation for Streams in the Idaho Batholith.
• Copyright Material: NO

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SEDIMENT YIELD USING
RATING EQUATIONS, mg/YR
Figure 6-Comparison of sediment yield esti-
mates from two methods: (1) by using sedi-
ment rating equations and (2) by time-
integration between hand samples. Data
from stream monitoring on the Boise
National Forest.
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SEDIMENT YIELD USING RATING EQUATIONS, mg/YR
Figure 7-Comparison of total sediment
yield estimates from two methods: (1) by
using sediment rating equations and (2) by
time-integration between hand samples. Data
from streams in the Silver Creek study area.
Five estimates of sediment yield were made from the
data in Silver Creek (table 2). The first method used a
sediment rating curve for total sediment from the hand
samples and mean daily streamflow. The second method
time-integrated total sediment as described above for the
Boise National Forest data. The third and fourth
methods were the same as the first two with the excep-
tion that the automatic pumping sampler sediment data
were used. The fifth method estimated sediment yield
based on the volume of sediment in sediment dams.
The equivalency of the rating equation method and
integration method for the hand samples was tested
with a paired t test. The hypothesis that the two
methods give the same estimates was accepted at the
95 percent level. However, as with the Forest monitoring
data, the time-integration method averaged slightly
higher yields than the rating equation method (fig. 7).
The sediment yields from these two methods are com-
pared with the sediment dam yields (fig. 8), and neither
tested different from the sediment dam yields at the 95
percent level. But the yield estimates from the rating
equations did test different at the 90 percent level.
Although the differences were not significant by the
paired t test, the sediment dam yields were somewhat
less for years of low sediment yields and greater for high
sediment years than the estimates by rating curves and
integration. The paired t test only tests the means, so
the variances could be different.
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SEDIMENT YIELD FROM SEDIMENT DAMS, mg/YR
Figure 8-Comparison of sediment yield esti-
mates using time-integration, rating equa-
tions, and sediment dams from Silver Creek
data.
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