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picking up lower costs of the Gunnison Tunnel's direct flow right and to ensure tha t <br />Ridgway storage is used first. <br />02-13-95 Changed irrigation efficiency for demand nodes in the Austin area from 0.3 0 <br />? <br />(GUNMOD) to 0.45 to be more consistent with the magnitude of the irrigate d <br />acreage and the historic diversions. <br />Modified the flow regime below Taylor Park Reservoir, reduc ing the monthly flow <br />? <br />requirements to be consistent with the GUNMOD calibration effort. <br />Performed additional review of the mode l to assure that MODSIM is accuratel y <br />? <br />representing the data and assumptions of GUNMOD e x c e p t where the assumption s <br />have been modified by the CRDSS team. <br />Adopted storage levels for Blue Mesa and Taylor Park from the GUNMOD <br />? <br />forecasts. Computed a complete time se ries of forecast end-o f-month target storag e <br />levels using the GUNMOD forecast module GUNFRCST. <br />All of these modifications were made to improve the calibration of the model with respect to replicating <br />actual historic administrative and operational conditions that are reflected in the historic stream gage <br />and diversion data. <br />Differences Between Baseline and Calibration Network Models <br />There are two baseline network models for the G unnison River prototype: the "Strict Administration <br />Model,? sadmin2.22, and the "good ne ighbor" protocol, gad min2.22. The former (sadmin2.22) reflects <br />strict administration of all decreed water right prioritie s, in particular the direct flow water rights of the <br />Uncompahgre project and the G unnison Tunnel. The second ne twork (gadmin2.22) reflects the <br />administration that has informally b een practiced in the basin, notably th at the direct flow rights of the <br />UVWUA are subordinated to other non-project water rights on the ma in stem of the Uncompahgre <br />River, and the direct flow right of the Gunnison Tunne l is subordinated to all j unior direct flow rights <br />on the main stem of the Gunnison Ri ver and is treated as senior only to the large storage right of Blue <br />Mesa Reservoir. For the subsequent calibration of the MODSIM model, the gadmin2.22 network was <br />used as the baseline condition. The final ca libration network, cal2.212, wa s obtained by making the <br />following modification to gadmin2.22: <br />? <br />Because of the one annual fill rule, the simulati on resulted in large swings in storage (modeled <br />versus historic). To correct for this, the carr yover storage provision was di sabled such that the <br />reservoirs could still fill in the spring months. In the MODSIM simulation, this was accomplished <br />by artificially increasing the storage right of Blue Mesa by 500,000 acre-feet and the storage right <br />of Taylor Park by 40,000 acre-feet. <br />Results of the Prototype Calibration <br />The results of the calibration process are evaluate d by comparing the simulation results from the model <br />runs at the defined calibration point s to the historic data at those locations. This is accomplished by <br />analyzing tabular comparisons a nd graphical plots of the monthly flows betw een historical and <br />simulated conditions over the 11-year period (1970 through 1980). These tables and graphical <br />comparisons are attached in Appendices A and B. <br />5 <br />A275 02.23.94 1.15-27 Fosha, Ritsch <br />