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SPDSS Memorandum <br />Final <br />To: Ray Bennett and Ray Alvarado <br />From: LRE, Erin Wilson and Mark Mitisek <br />Subject: South Platte Historic Consumptive Use -Annual Irrigation Parameter Time Series <br />(Ground Water Acreage and Sprinkler Acreage) <br />Date: March 20, 2006, Updated March 2008 to Include 2005 Acreage <br />Introduction <br />Irrigated acreage and crop types are key data components used to estimate crop consumptive use <br />in the SPDSS study area. GIS coverages were developed for SPDSS (RTi, 2006) that represent <br />acreage and crop types by ditch or water source for 2005, 2001, 1987, and 1976 using thermal <br />signatures from satellite imagery, aerial photos, and field interviews. In addition, a coverage was <br />developed that represents irrigated acreage by ditch or water source for 1956 using aerial <br />photography. The Task 71 memorandum included a recommendation for filling crop acreage <br />between GIS coverages. <br />This memorandum presents the general approach to fill missing irrigated acreage data for the <br />following: <br />Determine an appropriate method for estimating supplemental ground water acreage and <br />sprinkler acreage, by ditch or other water source, for the entire SPDSS study period (time <br />periods before, after, and between GIS irrigated acreage coverages). The method must be <br />able to be added as a feature to StateDMl and utilize data stored in HydroBase directly <br />from the GIS coverages plus information stored in HydroBase that match wells assigned to <br />acreage in the GIS coverages with their permit or adjudication dates. <br />Each modeled surface water structure, group of surface water structures, or group of wells are <br />assigned a total acreage and crop type in the crop distribution file (*.cds). In addition, total <br />acreage is split by application method and source and assigned in the yearly irrigation parameter <br />file (*.ipy). The acronym assigned below is used to describe the "type" of acreage (acreage <br />subsets) in the remainder of this memorandum. <br />- Acreage receiving surface water only, irrigated by sprinkler application (SS) <br />- Acreage receiving surface water only, irrigated by flood application (SF) <br />- Acreage receiving ground water (and surface water if assigned to ditch) irrigated by <br />sprinkler application (GS) <br />- Acreage receiving ground water (and surface water if assigned to ditch) irrigated by flood <br />application (GF) <br />Page 1 of 14 <br />