Laserfiche WebLink
<br />001952 <br /> <br />XCONS was developed by Reclamation in 1989 and has been modified several times since, The <br />following modified excerpt, adapted from the Inventory of Hydrologic Models (Reclamation, 1991), <br />gives a brief description of XCONS: <br /> <br />PURPOSE: <br /> <br />Estimates monthly crop evapotranspiration (consumptive use) using the modified <br />Blaney-Criddle Method. An option is not available to estimate monthly crop <br />evapotranspiration (consumptive use) using the Original Blaney-Criddle method. <br /> <br />SPATIAL PRECISION: <br />Point estimates based on weather station locations. <br /> <br />TEMPORAL PRECISION: <br />Monthly, <br /> <br />CAPABILITIES: <br />Provides monthly estimates of consumptive use and crop irrigation <br />requirement and allows for overall estimates weighted by crop, Assumes that <br />consumptive use is a function of temperature, precipitation, location, and crop <br />phenology only. <br /> <br />INPUT REQUIREMENTS: <br />Climate (temperature, precipitation, and growing season) and crop phenology. <br /> <br />OUTPUT PRODUCED: <br />Monthly consumptive use (et) and crop irrigation requirement estimates. <br />Estimates of effective precipitation using the SCS method. <br /> <br />XCONS computes the average monthly temperature and precipitation for a specific area from the <br />weight of each weather station used, and computes monthly consumptive use, monthly effective <br />precipitation and monthly consumptive irrigation requirements in inches per acre. Net irrigation <br />requirements (monthly irrigation depletions rate) are estimated by subtracting effective precipitation <br />from estimated crop consumptive use. The SCS effective precipitation method as explained in TR 21 <br />was used with a 3-inch application depth to determine effective precipitation. <br /> <br />Monthly irrigation depletions were estimated by Unit. Some Units were further divided to distinguish <br />historic from newer irrigated areas or where it was deemed appropriate to distinguish between sources <br />of irrigation water or locations of return flows, <br /> <br />Climate Data <br />Monthly average temperature and total monthly precipitation data were obtained for all National <br />Oceanographic and Atmospheric Administration (NOAA) stations located within the Basin. Selection <br />of NOAA stations to represent the climate of a Unit were based on a station or stations proximity to <br />irrigated lands, A GIS coverage of weather station locations in Colorado, New Mexico and Utah was <br />combined with an irrigated lands coverage (see later discussion), This combined coverage showed the <br />proximity of meteorologic data to GIS crop acreage. Selected weather stations followed the <br />recommendations of the State of Colorado CRDSS Task Memorandums 2,09-14, 15, 16, 17, and 18. <br /> <br />DRAFT - SJRIP Hydrology Model Documentation <br />June 18, 1999 <br /> <br />13 <br />