7087

• UCREFRP Catalog Number: 7087
• Author: Elliot, J. G., J. E. Kircher and P. V. Guerard.
• Title: Sediment Transport in the Lower Yampa River, Northwestern Colorado.
• USFW Year: 1984.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

Table 4.--Sediment-transport equations derived from sediment discharges
estimated with the Modified Einstein procedure at
station 09260050 Yampa River at Deerlodge Park
[Qs, sediment discharge in tons per day; Q, water discharge in cubic feet
per second; R2, coefficient of determination; SE, standard error of
estimate in percent; n, sample size; mm, millimeter]
Type of sediment
discharge Regression equation R2 SE n
Total----------------- Qs = 0.143 Qi•as
Sand and gravel------- Qs = 0.00946 Qi•s7
Silt and clay---------
0.062-0.25 mm---------
0.25-1.0 mm-----------
Coarser than 1.0 mm---
Q =
s 0.231 Q1.21
Q =
s 0.00125 Qi•ss
QS = 0.0108 Q1.48
Q
s 0.00130 Qi•4s
0.80 76 33
0.82 82 33
0.58 133 33
0.86 74 33
0.74 103 33
0.52 241 33
define the frequency of discharge occurrence (flow duration), and when data
are available to construct a relation between sediment discharge and water
discharge. The annual sediment load transported by increments of discharge is
computed by combining the relation between sediment discharge and water
discharge (sediment transport equation) with the average frequency of dis-
charge occurrence (flow-duration curve). This technique commonly utilizes
total sediment discharge, or suspended sediment discharge versus water-
discharge equations; however, it also may be used with sediment transport
equations of other material sizes or categories, such as the sediment trans-
port equations in tables 3 and 4.
The frequency distribution of Yampa River discharges during the last 43
years of record is shown in figure 6. This flow-duration curve was combined
with sediment-transport equations derived from measured data in table 3 to
compute: (1) Annual total sediment load; (2) annual suspended sediment load;
(3} annual discharge of bedload; and {4) annual sediment loads of material in
the sand gravel- and silt-clay-size categories. The annual total sediment
load computed using the sediment transport equation derived from measured
sediment discharges was 2.04 million tcn%yr (table 5). The annual suspended
sediment load was 1.34 million ton/yr, and the annual discharge of bedload was
0.10 million ton/yr. Therefore, bedload constitutes about 5 percent of the
total sediment load transported through Deerlodge Park annually. This prapor-
tion for bedload seems reasonable; based on observations from instantaneous
sediment discharge measurements, bedload discharge as a percentage of total
sediment discharge varied from 1 to 32 percent and averaged 7 percent (see
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