Data of AH.Owlia thesis, The Lake Urmia Basin, Iran.

Actual evapotranspiration is one of the water balance equation and surface energy balance components. The estimation of agriculture water consumption in irrigation projects is based on the determination of this variable. In this study, MPySEBAL based on energy balance budget was developed due to customization of PySEBAL for The Lake Urmia Basin. Results of the models validations with lysimetric data from 2010 to 2011 showed that MPySEBAL (with selecting anchor pixels with land surface temperature and vegetation cover thresholds) is superior to PySEBAL by providing up to 70% less RMSE. After that, the values of evapotranspiration for the period from the beginning of 2000 to the end of 2019 were presented in monthly and annual temporal resolution and 250 meter spatial resolution. Then, using the precipitation data derived from synoptic stations that were located in the basin, precipitation, effective precipitation and agricultural water need maps for the reference period of 2000-2019 were calculated for the basin. Then, by dividing the catchment into three regions, east, west, and south and downscaling precipitation and temperature data on three selected stations in these areas (Urmia, Tabriz, and Miandoab), and using the HadGEM2_ES model, under three RCP2.6, 4.5, and 8.5 scenarios. In the process of downscaling, the 20-year period of 2000-2019 was selected as the reference period (observation data) and the period of 2021-2040 as the period of climate change. The results showed an average increase in air temperature up to 10 and precipitation up to 11 percent per year for the entire basin. By finding the relationship between air temperature, surface temperature, and evapotranspiration rate, the amount of agricultural water consumption in the next years was calculated, which results show an increase in agricultural water consumption (3% to 5%) and agricultural water demand (2% to 5%) in The Lake Urmia Basin. Therefore, it seems that due to the impact of climate change on this basin, the need to manage and exploit the available resources in the basin will be more important in the next years.