Bowser, C. J.. University of Wisconsin, bowser@geology.wisc.edu
Marzolf, R. J.. U. S. Geological Survey, rmarzolf@usgs.gov

 
FLOW-DISCHARGE CALIBRATION USING CONDUCTIVITY IN THE COLORADO RIVER DOWNSTREAM FROM THE GLEN CANYON DAM
 
In connection with the experimental high level release of water from the Glen Canyon Dam in March-April 1996 we investigated changes in net primary productivity before and after the flood event downstream of the dam. Measurements included deployment of conductivity sensors at positions along the tailwater stretch between the dam and Lees Ferry. Coincidence of the conductivity variation at the dam and Lees Ferry sites is striking, with little modulation of the signal along 15 miles of river transit. Flow velocities were calibrated over a range of river discharges (500-750 m^3/sec) yielding a linear relationship that agrees well with Rhodamine-WT based dye studies conducted earlier by the USGS. Mean velocity (m/s) = 0.000865oDischarge (m^3/s) + 0.27272 (R^2=0.984) Reasons for the downstream conductivity variations are unproven, but we believe they are related to internal seiches in waters of the chemically stratified Lake Powell forebay. Location of the reservoir chemocline at the depth of the water inlet structures of the generators at the time of the experimental flood provided maximum signal difference. The observations suggest a powerful, yet inexpensive technique for measuring river flow velocities and dispersion downstream of the dam over a wide range of river discharges.
 
Day: Tuesday, Feb. 2
Time: 10:30 - 10:45am
Location: Sweeney Center
 
Code: SS19TU1030S