7824 - Laserfiche WebLink

Home Browse Search

Subsequently, a high flow level of about 7,000 cfs was measured on July 13 and a total of 5 cross-sections were completed. On July 22, a . middle flow., measurement (4200 cfs) was completed and the low flow was measured on-October 23. Green River The Mineral Bottom reach was measured at average flows of 9,700, 5,000 and 2,400 cfs. Between the second and third measurements, a large thunderstorm caused considerable input of sediment and debris into the river, resulting in aggradation across the lower transect. At Gray's Canyon, flows of 9,500, 5,000, and 2,800 cfs were meas- ured. The initial six transects were reduced to five because the upper- most transect was unmeasurable at the high flow. Two major tributaries occur between this reach and the Ouray site. The study site at the Ouray National Wildlife Refuge (called the Ouray Reach) was measured at discharges of 6,000, 3,300, and 2,200 cubic feet per second. This study site is located above confluences of the Duchesne and White River which account for the large difference in flows between this site and Gray's Canyon. Hvdraulic Simulation Model Calibration Details of the data reduction, correction and review process are • presented in Appendix I. The hydraulic simulation results for IFG-2 and IFG-4 presented in this report are considered adequate for the present purposes, and no further refinements are expected prior to use of the simulation models in actual analyses. Calibration, predicted and target velocities, and water surface elevations for the IFG-2 (WSP) runs (Potash, Mineral Bottom, Ouray) are also presented in Appendix I as are stage regressions and velocity adjustment factors for the IFG-4 runs (Black Rocks, Moab, Gray's Canyon). Review of Appendix I will show that results of the calibration processes were quite successful for all reaches after only minimal input adjustments. The calibration flow range was acceptable for all study sites except Black Rocks and a fourth sampling trip was planned for that reach in March 1981. Habitat Suitability Curves .At the time of this writing, habitat suitability curves for young-of- the-year (YOY) Colorado squawfish and adult humpback chubs at the Black Rocks reach were completed. Because it was felt that much of the vari- ability in the habitat preferences of adult Colorado squawfish was attributable to available habitat distributions at the different collec- tion points, a more thorough analysis was necessary. Since YOY squawfish were captured only in a restricted range of • depth, velocity, and substrate conditions, it was assumed that habitat 6