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

peak in this curve represents the increment of discharge which transports the highest

fraction of the annual sediment load of the stream, and represents the "effective

discharge'., as defined by Andrews (1980).

Analysis of Discharge Records to Determine Threshold Discharges

We analyzed ar~hived USGS discharge measurements for station 09306500 for

the periods between September 15, 1967, and October 3,1979, and between October 29,

1985, and September 30, 1997. Discharge measurement notes include channel depth and

width, as well as the location of the measurement in relation to the gage. These records

provide documentation of long term changes in channel geometry and seasonal

fluctuations in bed elevation (Smelser and Schmidt, 1997). At low discharges,

measurements were typically made within 75 meters up or downstream from the gage

with a wading rod. At higher discharges, measurements were made with a sounding

weight suspended from the cableway located at the gage. Actual discharge

measurements were made approximately twice each month during the period of time

while the gage was maintained, and were used to establish a stage-discharge rating

relation. Measured discharges, cross-sectional area, mean depth, maximum channel

depth, and distance of the measurement from the gage were transferred from the records

into a spreadsheet and analyzed.

The elevation of the thalweg was calculated by subtracting the maximum depth

during a discharge m.easurement from the stage elevation at the time of measurement.

All elevations were adjusted to a common datum for comparison. The temporal sequence .

of thalweg elevation through time was compared to the record of mean daily discharge.
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