9658

• UCREFRP Catalog Number: 9658
• Author: Schmidt, J. C. and K. L. Orchard.
• Title: Report A - Geomorphic Analysis In Support of a Channel-Maintenance Flow Recommendation for the White River Near Watson, Utah Draft Report.
• USFW Year: 2002.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

tiner bed material occurred at discharges below bankfull stage in several of the coarse-
.

bedded rivers he studied. The channel of the White River within the study reach is made

of both firie-grained and gravel deposits. While some of our evidence suggests that a

threshold of equal mobility is reached near 41 m3/s (1460 fels), it is more likely that

selective transport of the finer deposits occurs at this discharge. Both the aggradation of

the bed at higher dischatges in very coarse bedded areas of tlie stream, and a peak in the

sediment transport curve at 14 m3/s (500 ft3/s), suggests that finer sediments are being

transported selectively at low discharges.

Flood magnitudes decreased significantly in the mid-1960s, and have remained,

on average, lower than during the earlier portion of the century. While mean daily

discharge values are available for most of the century, the actual notes made by

technicians conducting discharge measurements at the Watson gage only exist for dates

between 1968 and present. These notes provide information on channel width and depth

used for the analysis in this study. Thus, the analysis we conducted using these data only

represent conditions during the past two or three decades where peak floods have been

significantly lower than during than during the first half of the century.

CONCLUSIONS

1. Effective discharge, the discharge where the river accomplishes the most geomorphic

work. occurs at discharges lower than bankfull. Discharges responsible for maintaining

the form of the channel occur between 48 and 82 m3 Is.

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