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CRDSS <br />TASK MEMORANDUM 1.15-27 <br />Water Rights Planning Model <br />Calibration of MODSIM Prototype <br />1.0 ISSUE <br />The purpose of this task memorandum is to describe and document the procedures used to calibrate the <br />MODSIM computer model develope d as the prototype water rights planning model (WRPM) for the <br />Gunnison River basin. Calibration is necessary to establish the credibility of the model performance <br />and to ensure that the model of the river system is producing accurate data. <br />2.0 DISCUSSION/ANALYSIS <br />General <br />For the purposes of the CRDSS, calibration is acco mplished by comparing the model simulation results <br />to the GUNMOD version 0.99 model calibration and to measured historical data available from the U.S. <br />Geological Survey (USGS) and the Division of Water Resources (stream gage data, reservoir storage <br />contents, diversions at key structur es, etc.). In order to replicate historic hydrologic conditions in the <br />"good neighbor" <br />Gunnison River basin, the results from the model simulation for the protocol were <br />used in the calibration. As opposed to river administra tion in strict accordance w ith the priority system, <br />the good neighbor protocol reflects a number of informal agreements among the major water users and <br />the Division Engineer that are intende d to maximize beneficial use of water within the basin by limiting <br />an administrative "call" by senior water rights agai nst junior water rights in the Gunnison River and <br />Uncompahgre River basins. <br />The model calibration focused on the 11-year pe riod from 1970 through 1980. This period was selected <br />because it represents both wet and dry year hydrol ogic conditions and is recent enough to reflect the <br />operations of most of the major storage and dive rsion facilities in the basin, with the exception of <br />Ridgway Reservoir (1988). <br />Calibration Points <br />The following stream gages, reservoi rs, and key water right structures were selected for the comparison <br />of historic versus model simulated data: <br />Stream Gages: <br />Gunnison River at Gunnison; Gunnison River at Delta; North Fork of Gunnison <br />near Somerset; Uncompahgre River at Colona; Uncompahgre River at Delta; <br />Gunnison River near Gra nd Junction; Gunnison Ri ver below the Gunnison <br />Tunnel. <br />Reservoirs: <br />Blue Mesa Reservoir; Taylor Park Reservoir. <br />Key Structures: <br />Gunnison Tunnel (South Canal); North Delta Canal; Fire Mountain Canal; <br />Loutzenhizer Ditch; Selig D itch; and Ironstone Ditch. <br />1 <br />A275 02.23.94 1.15-27 Fosha, Ritsch <br />