Background: The long-term effects of climate change in all countries have been able to affect the water management system. Therefore, it is vital to consider the impacts of this phenomenon in sustainable management. A conditional framework has been conducted to predict crop water requirement in semi-arid regions with two climate scenarios of RCP 4.5 and RCP 8.5 considering the IPCC datasets.Methods: Eight models including EC EARTH, CESM, CANESM, HADGEM, GISS E2, GFDLCM2, MIROC ESM and IPSL were implemented to evaluate the extreme points of the evapotranspiration in future.Result: Results showed that GISS E2 and GFDLCM2 models were more accurate to estimate the evapotranspiration. Moreover, in the next two periods for all four parameters in all GCM models, the RCP 8.5 situation was anticipated a better esteem than the RCP 4.5 choice. Comes about appeared that GFDLCM2 and GISS E2 models have more certainty for evapotranspiration. The lowest values during the next two periods 2020-2030 and 2080-2090 and the methods RCP 4.5 and RCP 8.5 for evapotranspiration by GISS E2 model have been obtained. The evapotranspiration alters based on the climate alter models amid the following two periods, distant and close, were inspected for two scenarios, RCP 4.5 and RCP 8.5. The comes about appeared that the RCP 8.5 situation has assessed the four parameters for the following period more than the RCP 4.5 situation.Conclusion: The comes about appeared that the RCP 8.5 situation has assessed the four parameters for the following period more than the RCP 4.5 situation. At that point the changes of the least and most extreme parameters of evapotranspiration for the two outflow scenarios amid the following two close and distant periods were inspected that the comes about appeared that the both scenarios have a nearly steady slant amid both the close and distant prospects and encompasses a slight increment and diminish.