Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />Run the monthly historic Yampa River Basin model with the irrigation water requirement file <br />(*.ddc) created in Task 1.2 and the basetlows developed in Task 1.3. The simulation will be <br />performed with StateMod's variable efficiency and soil moisture options set to "on". The <br />simulation log file will be reviewed for errors and warnings. The variable efficiency calculation <br />will be hand-checked on two representative structures during the period 1976 through 1996 and <br />compared to StateCU output files. <br /> <br />Task 1.5 Compare StateCU Variable Efficiency and Soil Moisture Accounting Historic Model <br />Results to Previous Model Results and Historic Measurements <br />Prepare a technical memorandum that compares the results of the historic monthly Yampa River <br />Basin Model StateMod simulation with variable efficiencies and soil moisture accounting to the <br />previous Historic Yampa River Basin Model results and historic measurements. The comparison <br />will concentrate of the recent period of 1976 through 1996. The results will be assessed to <br />determine the effect of variable efficiency and soil moisture calculations on the model <br />calibration by comparing: <br />Simulated verses Previous Simulated Diversions, Streamtlows, and Reservoir Contents <br />Simulated versus Historic Diversions, Streamflows, and Reservoir Contents <br />Representative structures, identified as having large variations in efficiencies based on StateCU <br />results, will be further reviewed to see the specific effects of the variable efficiency simulation <br />on wet, average, and dry years. This technical memorandum will include up to 15 figures that <br />present comparative results in graphical form. These figures are expected to describe the change <br />basin wide and for selected ditch types (e.g. senior, swing, and junior). Note that additional <br />calibration is not included in this Scope of Work. <br /> <br />TASK 2 - CALCULATE RIVER HEADGATE DEMANDS <br /> <br />Background: <br /> <br />Currently, headgate demand for the Calculated model scenarios is determined by dividing the irrigation <br />water requirement for a structure by the average monthly structure efficiency. Winter diversions for <br />stock watering are handled based on historic water use on a case by case basis. The average monthly <br />structure efficiency (12 values) is determined by comparing historic headgate diversions with estimated <br />irrigation water requirements by month. <br /> <br />Objective: <br /> <br />Determine calculated headgate demands using three additional methodologies. Compare the calculated <br />head gate demands to historic head gate demands and head gate demands developed previously for the <br />Calculated Yampa Basin model. Recommend an approach to calculating headgate demands for Task 3. <br /> <br />Task 2.1 Calculate Headgate Demands using Dry, Wet, and Average Monthly Structure <br />Efficiencies <br />During the Phase III CRDSS effort, each month during the period 1909 through 1996 was <br />characterized based on indicator stream gages as dry, wet, or average. Based on this <br />characterization, determine the average structure efficiencies for the dry months, wet months, <br />and average months. Estimate calculated head gate demand to be monthly irrigation water <br />requirement divided by the appropriate dry, wet, or average efficiency for the structure. <br /> <br />Coordinate with RTi to enhance demandts to perform the calculations and create the diversion <br />demand file (*.ddm). <br /> <br />C:\Cdss\statemod\Variable eft evaluation contract_ 4.doc <br /> <br />Page 12 <br />