Abstract
The main aim of this research work is to assess the performance of the various mass transfer-based method with respect to standard FAO56-PM. Daily meteorological data from 1979 to 2018 has been used to compute reference evapotranspiration (ETo). The climatic data from 1979 to 2006 were used for the development of the calibrated equations and data from 2007 to 2018 were applied for validation purpose. The evaluated, calibrated and further validation of calibrated models were compared using statistical tools in order to ranked the models effectiveness using Global Performance Indicator (GPI) where higher GPI value shows better model. The models were then arranged using GPI and it was found that proposed model resulted with best GPI value of 5.02, 2.85 and 5.19 during evaluation, calibration and validation respectively followed by Albrecht model. The results of this study could be used by the water management system, crop cultivators, crop advisors, researchers from research centres. Moreover, it is beneficial for the decision maker in the vast field of agriculture, hydrology and environment. The calibration and validation of different ETo equations tend to increase their performance. Thus, the validated evapotranspiration model that used less climatic parameters can predict the ETo condition accurately for Asir region.