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<br />CONI <br /> <br />Methodologies for Estimating and Projecting Urban (Municipal & Industrial) and <br />Agricultural Demands and Environmental and Recreational Flow Requirements <br />November 2003 <br /> <br />Methodology for Estimating Agricultural Demands <br />Introduction <br /> <br />Agricultural water demands will be characterized for current and future conditions in <br />each of the eight major river basins in Colorado. Irrigated acreage, cropping patterns, <br />and climatic data will be used to estimate crop irrigation water requirements, while <br />diversion records and other studies will be used to estimate historic application <br />amounts and consumptive use. A listing of terminology used in this discussion is <br />included in Table 2. <br /> <br />Table 2 Agricultural Demand Terminology <br /> <br />Term Description Primary Data Sources CDSS1 Tools <br />Historic Water Application Total water supply delivered to * SEO diversion database * Hydrobase <br />(Surface Diversion and meet crop irrigation water * Groundwater Pumping * StateMod <br />Groundwater Pumping) requirement Estimates <br /> * Basin Studies and Reports <br />Crop Irrigation Water Theoretical value based upon * GIS and other Land Use Studies * Hydrobase <br />Requirement (IWR) Blaney-Criddle procedure or * Climatic Data * StateCU <br /> other method * Crop Characteristics <br />Crop Consumptive Use of Estimated value based upon * Historic Water Application * StateCU <br />Irrigation Water (CU) expected system efficiency *IWR * StateMod <br /> and available water supply <br /> <br />1 Colorado's Decision Support System <br /> <br />The Colorado, Gunnison, Yampa/White/Green, San Juan/Dolores, and the Rio <br />Grande river basins have existing Colorado Decision Support System (CDSS) data sets <br />and models. For these basins, the StateCU model and data will be used to estimate <br />irrigation water requirements. <br /> <br />For those basins without developed CDSS data sets (i.e., the Arkansas, South Platte, <br />and North Platte), information for irrigated acreage and cropping patterns will be <br />gathered from existing sources and studies. A statewide StateCU climate data set is <br />scheduled to be prepared by the State and consultants within the coming months. If <br />available, these sources should provide sufficient information to apply StateCU for <br />these basins in a more general fashion. <br /> <br />Annual average crop irrigation water requirements will be estimated for <br />representative wet, dry, and normal hydrologic periods. The State's StateMod CDSS <br />data sets and HydroBase will be queried to estimate historic diversions and pumped <br />groundwater for agricultural use by river basin. Other data sources will be consulted <br />to supplement data deficiencies where possible. Table 3 is an example of how the <br />summary data may be presented. To illustrate the variability of demands for key <br />structures (e.g., the largest ditch in a basin), a summary of key ditches may be listed. <br /> <br />7 <br /> <br />S:\TASK 8 & 9 SUPPLY AND DEMAND\SWSI DEMAND METHODOLOGY 11-26-03.DOC <br />