8106

• UCREFRP Catalog Number: 8106
• Author: Anderson, R. M.
• Title: Riverine Fish-Flow Investigations.
• USFW Year: 1998.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

Table 4-B. The mean and standard deviation of the inflection point flows (cfs) and
the inflection point flow for the 50, 70, 80 and 90 percentile runs for seven variables
at 40 runs.

Variable Mean Std. Dv. 50% 70% 80% 90%
Wetted Width (ft) 86.5 53.7 60 100 125 150
Average Depth (ft) 86.3 45.9 80 100 120 125
Change in Stage (ft) 84.0 24.4 80 80 80 100
WidthlDepth Ratio 76.1 53.7 60 100 125 150
Wetted Area (sq ft) 90.0 25.8 80 100 100 125
Average Velocity (ftls) 91.8 36.0 100 100 100 125
Grand Mean 85.8 41.6

There were a total of 13 pools with cross sections, of which eight were in Strata 6

and five in Strata 8. The grand mean for inflection points on pools was 89 cfs. For most

variables the mean of inflection points for pools were generally somewhat less than for

rimes and runs. The main exception was for velocity, which was 127 cfs (Table 4-C) and

the higher flow for velocity caused the grand mean for pools to be higher than runs. The

higher inflection points for velocity is explained by the fact that velocity is very low in

pools and therefore, the curve for the velocity/flow relationship does not have a dramatic

rate break as flows decrease to zero.

Flows of80 cfs would achieve inflection points on 50% of the pools measured

and 110 cfs would maintain 80% of the pools. Flows that equal or exceed the mean of

inflection points for rimes and runs, will also encompass those identified for pools.

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