7199 - Laserfiche WebLink

Home Browse Search

3 collection for the six years of record was incomplete at the Quarry site, beginning approximately June 1 each year. This data was supple- mented with meteorological data from the nearest station with complete records at Grand Junction for the period from March 1 to May 31. The meteorological records for the Headquarters site at Dinosaur National Monument and for Craig, Colorado were also reviewed during the compila- tion of the input data files. The final data represents a composite of the available meteorological records. Hydrology data. The hydrologic parameters of discharge and water temperature were obtained from U.S. Geological Survey gaging stations at Flaming Gorge on the Green River, Maybell on the Yampa River, Lily, Colorado on the Little Snake River, and at Jensen, Utah on the Green River. The daily values were compiled to calculate mean weekly values. Stream geometry. Stream geometry parameters of stream width, latitude, elevation, streambed roughness, and stream shading are required for the model. These parameters were obtained from U.S. Geological Survey topographic maps and from field measurements. Model Calibration The model was calibrated using the Jensen gage as a validation point. The input discharges and temperatures at the headwaters were modeled throughout the Yampa and Green Rivers in Dinosaur National Monument to the Jensen gage using the historical meteorological data. The predicted water temperature at Jensen was compared to the actual water temperature measured at Jensen. The error between the actual and predicted water temperature was calculated and the input meteorology (specifically air temperature) was adjusted accordingly for the next simulation. This -recursive process was continued until acceptable error limits were obtained. The final calibrated meteorological data set was used for all model runs made with the simulated discharges. RESULTS AND DISCUSSION The NPS minimum streamflow hydrograph is a series of discharges required to sustain the natural conditions and processes of the channel morphological and biological resources. These resources include sediment loa# and channel substrate, aquatic biology, and riparian vegetation. The minimum streamflow hydrograph is shown in Figure I. When superimposed on a historical flow year, the simulated discharge or the natural discharge, whichever is less for the given week, is incorporated into a composite hydrograph for that particular year (Figures 2-7). The composite hydrograph always represents an annual flow volume less than the historically recorded volume. The reduced discharges were analyzed for the effects on water temperatures. The meteorological conditions were sucessfully calibrated to dupli- cate the water temperature conditions at the Jensen gaging station on the Green River in Jensen, Utah, downstream of the Dinosaur National