19-Assessment of Evapotranspiration Estimation Methods in a Semi Arid Region.

Abstract

Estimation of accurate reference crop evapotranspiration (ET)) is necessary for a reliable irrigation management system. This paper deals with evaluation of seven reference crop evapotranspiration (ET0) methods viz. 1982 Kimberly Penman (K-P 82), FAO-24 Penman (P-24), Penman 1963 (P-63), FAO 56 Hargreaves (F-H), Priestly-Taylor (P&T), Turc and FAO 24 Pan Evaporation (PE). These methods were compared with FAO-56 Penman-Monteith (F-PM) for their capabilities to predict ETo. Daily weather data for the period of 1971 to 2002 were used for comparison on daily, weekly, and monthly basis. The statistical results based on root mean squared error (RMSE) and average deviation (D) indicated that for estimation of ET° in Marathwada region PE is the most reliable and accurate method. The sequence of performance from the most to the least accurate methods for the semi arid and sub-tropical region of Marathwada is PE, P-63, Turc, F-H, P&T, P-24, and KP-82.