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<br />0006 3 <br /> <br />. Incorporated higher negative costs for the storage links from Blue Mesa <br />Reservoir to the Uncompahgre Project canals to ensure that Blue Mesa <br />storage was not picking up lower costs of the 'Gunnison Tunnel's direct <br />flow right and to ensure that Ridgway storage is used first. <br /> <br />All of these modifications and improvements were made to improve the calibration of the model <br />with respect to replication of actual historic administrative and operational conditions that are <br />reflected in the historic stream gage and diversion data. <br /> <br />2.4 Results of the Prototype Calibration <br /> <br />The results of the calibration process are evaluated by a comparison of the results from the <br />simulated model runs at the defined calibration points versus the historic data at those locations. <br />This is accomplished by graphical plots of the flows for both conditions over the 11-year time <br />period. 1970 through 1980. These graphical comparisons are attached hereto. <br /> <br />Stream Gaaes: Inspection of the comparative plots of the flow at the USGS stream gages <br />indicates a very close match between simulated and historic data. <br /> <br />End of Month Reservoir Storaae Content: For most years. the MODSIM simulation for end of <br />month storage in Blue Mesa Reservoir tracks with historic data reasonably well. In three of the <br />calibration. the MODSIM data was less than historic. probably as a result of too low of reservoir <br />target storage levels. For Taylor Park Reservoir, the MODSIM simulated data tracks reasonable <br />well, although there is a general tendency to understate in comparison to historic data. Beginning <br />in 1988. the MODSIM data begins to diverge more noticeably. possibly indicative of too high of <br />release for stream flow maintenance in the upper Gunnison or because of underestimated inflows. <br />At Paonia Reservoir, the simulation compares favorably, with a tendency toward emptying the <br />reservoir more frequently. This is believed to be due to the inclusion of an account to be released <br />for Endangered Fish. Comparison against historic data for Ridgway Reservoir is somewhat limited <br />because of historical data only being available since is construction in 1988. <br /> <br />Diversions at Kev Structures: The MODSIM simulated diversions at key structures matches well <br />with historic diversion data. Simulated diversions through the Gunnison Tunnel are typically less <br />than historic. possibly because of understated demands at the Uncompahgre Project Canals and/or <br />less storage water being imported through the tunnel because of releases from Ridgway Reservoir. <br />There is also a general tendency to slightly understate diversions at structure head gates (Selig, <br />Loutzenhizer and North Delta). This may relate directly to the fact that the model is driven by <br />calculated irrigation demands (acreage x C.U. + efficiency) and would not reflect historic .excess. <br />diversions. <br /> <br />3.0 CONCLUSIONS <br /> <br />The MODSIM prototype for the Gunnison River basin was calibrated to ensure that the model is <br />accurately representing the actual administration of water rights and operation of key reservoirs. <br /> <br />A276 01-26.96 <br /> <br />5 <br /> <br />1.16-27 Fosh.. Ritsch <br /> <br />1 <br />