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Evapotranspiration and irrigation water requirements for Jordan's national water master plan: GIS-based ET calculations




Taha, Suzan, author
AlIen, Richard G., author
Jacobi, Klaus, author
Qunqar, Edward, author
U.S. Committee on Irrigation and Drainage, publisher

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Evapotranspiration (ET) from irrigated cropland is a significant component of water consumption in Jordan. During 2000 and 2001, the MWP5 created a large GIS-based system that includes components for processing ET and net irrigation requirements (NIR) for various agroclimatic zones in Jordan. The NIR system, named NIR_Calculator, is programmed within Microsoft Access database using a Visual Basic interface and is highly flexible. Incorporation of irrigation-specific and culture-specific characteristics for crops has improved the prediction of evaporation and transpiration inside greenhouses and under plastic mulch. Computations include partitioning of irrigated crops into drip, sprinkler and surface irrigated classes, with evaporation from soil surfaces during initial crop development periods and during nongrowing periods calculated for each class separately. A monthly soil water balance determines the impact of stored soil moisture and off-season precipitation on NIR. Evaporation during nongrowing periods is considered when computing annual effective precipitation.


Presented at the 2002 USCID/EWRI conference, Energy, climate, environment and water - issues and opportunities for irrigation and drainage on July 9-12 in San Luis Obispo, California.

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