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A simulation model for evapotranspiration of applied water




Orang, Morteza N., author
Matyac, J. Scott, author
Snyder, Richard L., author
Geng, Shu, author
Sarreshteh, Sara, author
U.S. Committee on Irrigation and Drainage, publisher

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The SIMETAW program was written to provide a new and innovative tool for estimating evapotranspiration of applied water (ETAW), which is a seasonal estimate of the water requirement for evapotranspiration of a crop minus any water supplied by effective rainfall. ETAW information is needed to determine consumptive use requirements. In addition to using measured weather data, the SIMETAW program simulates daily weather data from monthly climate data. Simulation of daily weather data where only monthly means exist is a good tool for filling missing data points. In addition, the simulation program is useful for studying the effects of climate change on ETAW. All of the ETAW calculations are done on a daily basis, so the estimation of effective rainfall and, hence, ETAW is greatly improved over earlier methods. In addition, the use of the widely adopted Penman-Monteith equation for reference evapotranspiration (ETo) and improved methodology to apply crop coefficients for estimating crop evapotranspiration is used to improve ETAW accuracy.


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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