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

for 80% of the riffles surveyed while 100 cfs would equal or surpass the inflection points

for 50% of the riffles.

Table 4-A. The mean and standard deviation of the inflection point flows (cfs) and
the inflection point flow for the 50, 70, 80 and 90 percentile rime for seven variables
at 30 rimes.

Variable Mean Std. Dev. 50% 70% 80% 90%
Wetted Width (ft) 82.8 49.6 80 100 125 150
Average Depth (ft) 100.8 35.2 100 100 125 125
Change in Stage (ft) 92.2 49.6 80 80 100 125
Width/Depth Ratio 78.8 50.8 60 117.5 125 150
Wetted Area (sq ft) 111.0 34.9 100 117.5 125 125
Average Velocity (ftls) 92.7 31.0 100 100 100 125
Grand Mean 93.1 40.0

Eighteen run cross sections were done in 8 clusters and 22 cross sections in 9

clusters in Strata 6 (Appendix Tables 3 and 4). Unlike riffles, it was felt that all run

cross sections should be included. All runs sampled had multiple cross sections and were

selected to represent different habitat qualities of that run. For example, the tail of a run

had characteristics similar to riffles while upper reaches may have had characteristics

similar to pools.

The mean of the inflection points for runs ranged from 76 cfs (width/depth ratio)

to 92 cfs (velocity) (Table 4-B). The mean of the inflection points for width, depth, area

and stage were very similar at 87, 86, 90 and 84 cfs, respectively. The grand mean for

the inflection points for runs at 86 cfs, was somewhat less than identified for riffles. A

flow of 100 cfs would equal or surpass inflection points for 70% of the runs.

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