WSP10382

• File Number: 8200.760
• Description: Yampa River
• State: CO
• Basin: Yampa/White
• Water Division: 1
• Date: 6/27/1984
• Author: USGS
• Title: Sediment Transport in Lower Yampa River, Northwestern Colorado
• Water Supply Pro - Doc Type: Report/Study

Table 4.--Sediment-transport equations derived from sediment discharges
estimated r.vith 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 Q1'36 0.80) 76 33
Sand and gravel------- Qs = 0.00946 Q1'S7 0.8/ 82 33
Silt and clay--------- Qs = 0.231 Q1'21 0.581 133 33
0.062-0.25 mm--------- Qs = 0.00125 Q1'69 0.861 74 33
0.25-1.0 mm----------- Qs = 0.0108 Q1'48 0.74< 103 33
, /-
Coarser than 1.0 mm--- Qs = 0.00130 Q1'4S /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
di scharge (sediment transport equation) with the average frequency of di s-
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 Vampa 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 us i ng the sediment transport equation deri ved from measured
sediment discharges was 2.04 million ton/yr (table 5). The annual suspended
sediment load was 1. 94 mi 11 ion ton/yr, and the annual discharge of bedload was
0.10 miilion ton/yr. Therefore, bedloa.d constitutes a.bout 5 percent of the
total sediment load transported through Deerlodge Park annually. This propor-
tion for bedload seems reasonable; based on observations from instantaneous
sedi ment di scharge measurements, bedload di scharge as a percentage of total
sediment discharge varied from 1 to 32 percent and averaged 7 percent (see

19