Application of new mass transfer formulae for computation of evapotranspiration

This study aims to compare mass transfer-based models to detect the best model under different weather conditions. For this purpose, weather data were gathered from 181 synoptic stations in 31 provinces of Iran. The reference crop evapotranspiration was estimated using 11 mass transfer-based models and was compared with the FAO Penman-Monteith model. The results showed that the Penman model estimates the reference crop evapotranspiration better than other models in the most provinces of Iran. However, the values of R-2 were less than 0.90 for 24 provinces of Iran. Therefore, the models were calibrated using new formulae and preciseness of estimation was increased. The mass transfer-based models estimated the reference crop evapotranspiration in the eastern provinces (desert regions) of Iran better than other provinces. The best values of R-2 were 0.96 and 1.00 for Trabert and Penman models in AR and TE, KE, and YA provinces before and after calibration, respectively.