Alireza Sharifi - PhD Student of Water Resources Engineering, Department of Water Engineering, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran

Sensitivity analysis of reference crop evapotranspiration (ET0) in arid and semi-arid areas is an important necessity for better management of available water. To estimate the ET0, FAO-56 Penman-Monteith method, as the most recommended method for estimation of ET0, was used. Sensitivity of ET0 was analyzed in terms of change in mean air temperature (Tmean), actual vapor pressure (ea), net solar radiation (Rn) and wind speed (u2) within a r-term values (1960-2009). Also, the amount of ETc was calculated for rice, maize and winter wheat as the common crops in Isfahan. In annual time scale, results indicated ET0 is more and less sensitive to Rn and VPD, respectively. In seasonal time scale, Rn and ea have more and less effect on ET0 in summer, respectively. Also results showed that water requirement for rice is very high in compare with other crops

Climate parameters, Evapotranspiration, Penman-Monteith, Isfahan