Evaluation of eleven models for reference crop evapotranspiration estimation in Haji Abad region of Hormozgan

Reference crop evapotranspiration (ETo) is an important parameter for determining crop water requirements in the FAO method, and hence, its accurate estimation is of crucial importance in optimizing crop water use and water resources management. In this research where conducted in Haji Abad region of Hormozgan province for four years, weekly evapotranspiration from grass as a reference crop was measured using a drainable lysimeter. The ETo was also estimated using eleven models including FAO Radiation, Evaporation Pan, Blaney-Criddle, Penman and Penman-Monteith and Papadakis, Ivanov, Jensen-Haise, Hargreavse-Samani, Tork, and Makking models. The estimated ETo values from different models were compared with the data measured from lysimeter using linear regression, root mean square error, mean bias error, index of agreement and variance of the distribution of differences. Results showed that FAO Penman, Ivanov, Papadakis and Jensen-Haise models overestimated ETo, but the FAO evaporation pan, Hargreaves-Samani, Turk and Making models underestimated it. The results also indicated that the FAO Blaney-Criddle and FAO Penman-Monteith models had respectively higher accordance and homogeneity with the real data measured from lysimeter and can predict ETo with higher accuracy than other tested models. Therefore, these models are recommended, respectively, as the most appropriate models to estimate ETo in Haji Abad region and the areas having the same climate.