Comparison of Potential Evapotranspiration Models and Establishment of Potential Evapotranspiration Curves for Temperate Kashmir Valley

Potential evapotranspiration (PET) is a crucial indicator of hydrologic regime of a region. It is an important variable in the estimation of actual evapotranspiration (AET) in hydrological and ecosystem modeling. Evapotranspiration affects the amount of runoff and thus the irrigation water requirements of crops as well as water resources management. The present study has been carried out to compare the commonly used PET methods for the Shalimar weather station in district Srinagar of Kashmir Valley. FAO-56 Penman-Monteith equation is a standard method in estimating the PET. Other methods of PET estimation namely Modified-Penman, Hargreaves, Turc, Blaney Criddle, Christiansen, and Open Pan were compared with reference to Penman-Monteith method. Modified-Penman method was most correlated with the FAO-56 PM method with the coefficient of determination (R2) as high as 0.99. Modified-Penman method was followed by Hargreaves method with R2 of 0.98. Hargreaves method was then used to establish PET curves for other districts of Kashmir valley namely, Anantnag, Budgam, Baramulla, Kulgam, Kupwara and Pulwama where only data on air temperature is available. The highest annual PET was obtained for District Budgam being 951 mm and the least was obtained for district Baramulla being 759 mm.