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As the main consumer of water resources in Iran, restriction of water resources has caused the agricultural sector, to face a shortage of water for food production. The most important challenge for the agricultural sector is now to increase water productivity by calculating the exact amount of water consumed by the agricultural sector using new technologies. Awareness of need for the amount of water needed for irrigation of field crops and horticultural crops are the basic requirements of any irrigation project. In this regard, this research project in sponsorship of the Esfahan jihad-e-agriculture organization designed to determine net water consumption in Agricultural sector (autumn and spring plants) in 24 districts and 5 defined climates of the Isfahan province. To do so, the reference evapotranspiration (ETo) was calculated using FAO Penman-Montieth equation via coding in visual basic software and then zoning them in the Arc GIS environment. In this regard, by establishing the relationship between the physiographic units with the climatic parameters of each synoptic and climatologic meteorological station ETo amount was calculated in rasterized ACZ map units. It is notable that the clustered maps of meteorological data involved in the calculations are presented as raster maps and graphic figures. The rasterized pixels of the maps are prepared to show UTM, capability class of soils, soil texture and, EC, reference evapotranspiration and net irrigation water requirement when each pixel is pointed. To manage water demand in the agricultural sector under current conditions, crop evapotranspiration (ETc) was calculated according to the physiological characteristics including root depth, canopy cover, planting methods, planting date, variety, plant height and crop coefficient (Kcb and Ke). Rasterized map of soil parameters including salinity - texture - moisture content and arable lands were included in project performance map. In the end, the net water requirement amounts and related maps were provided for each crop to be used by policymakers in the agricultural sector. Intelligent computing algorithms, creation of proper database were prepared to establish a database in this study. For instance for the two template field and horticultural crops of wheat and pistachio, according to the graph outputs of the ETo amounts, annual reference evapotranspiration varied between 1219 mm in western part to over 2027 mm in the eastern part of the Isfahan province. The minimum and maximum evapotranspiration for wheat crop were 342.7 and 552.6 mm, and for pictachio were 665 and 770 mm, respectively.Keywords: Crop coefficient, FAO Penman-Montieth, Isfahan, Net water requierment.
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