A Statistical Comparison of Reference Evapotranspiration Methods: A Case Study from Jharkhand State of India
Agricultural planning relying on evapotranspiration suffers due to inaccuracy in its estimation. The nonavailability of meteorological parameters required for accurate estimation of reference evapotranspiration (ETo) resulted in the development of different methods of ETo estimation. The present study compares various universally accepted methods of ETo estimation by considering the Penman Monteith as a standard method. Comparative analysis indicated the suitability of Hargreaves (1985) method followed by Christiansen (1968) method and Pan Evaporation method (1977). The improvement in ETo estimation was carried out through transformation of standard equations using single or multi parametric approach after analyzing dependency and sensitivity of different meteorological parameters on ETo. The developed transformed models indicated that during ETo estimation morning time relative humidity (RH1) can play the dominant role (99%). ETo estimation by combination of bright sunshine hours and wind speed (WV) exhibit better role (98.8%) than the combination of minimum temperature (Tmin) and WV (98.6%).