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CRDSS <br />TASK MEMORANDUM 2.09-05 <br />Crop Consumptive Use Estimates for the Upper Colorado River Basin for calendar years 1985- <br />1990. <br />1.0 ISSUE <br />This task memorandum describes the calculation of crop consumptive use (CU) for the Upper Colorado <br />River Basin. The calculation of CU for the basin is based on a pro-ration of the CU for a portion of the <br />basin (areas associated with diversion structures being modeled) to the area of the full basin obtained <br />from GIS. <br />2.0 DISCUSSION <br />Crop consumptive use has been estimated for selected structures in the Upper Colorado River Basin <br />through the use of the CRDSS-CU model. The CRDSS-CU model calculates irrigation water <br />requirements which are provided to STATEMOD. STATEMOD imposes the irrigation water <br />requirements on a historic hydrology to estimate the water supply available for each structure. The <br />CRDSS-CU model then uses the water supply provided by STATEMOD to calculate the CU for each <br />diversion structure. The process is described by the following flowchart: <br />demand_cu UNIX script <br />List of Key Structures ---> CRDSS-CU Model ---> Demands for input to STATEMOD <br />STATEMOD Simulation ---> CRDSS-CU with Water Supply <br />To estimate CU for areas larger than the areas being served by the diversion structures being modeled, <br />the CU for modeled structures is pro-rated on the basis of the total area to modeled areas. <br />reportn utility program <br />CU and areas for modeled structures ---> GIS report of total areas ---> Pro-rated basin CU <br />2.1 Structures being Modeled <br />The diversion structures being modeled in STATEMOD for the Upper Colorado River Basin are <br />provided to the CRDSS-CU model via the coloup.dds file, the header and a small portion of the specific <br />file used in this process is shown in Table 1. These diversion structures are only a portion of the <br />diversion structures in the Upper Colorado River Basin. The water supply information for each structure <br />is provided by STATEMOD in the coloup.xcu file, the header and a small portion of this file is shown in <br />Table 2. A total of 254 diversion structures are modeled in the Upper Colorado River Basin <br />corresponding to a total irrigated area of 169,488 acres. <br />1 <br />Page <br />12/16/96 2.09-05 CSU/IDS <br />