Investigating the effect of climate change on discharge, NO3 load, and agricultural products yield upstream of Esteghlal dam

In this paper, the SWAT model is used to study the effects of climate change on discharge and water quality of inflow of Esteghlal reservoir in Minab catchment. Climate change scenarios (RCP2.6, RCP4.5, RCP6, and RCP8.5) in 5 GCMs (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC, NoerESM1-M) to simulate future discharge, NO3 load, and agricultural products yield, were applied. According to the analysis of different climate change scenarios, the highest average annual precipitation decrease and increase were 34.8% and 37.2% in RCP8.5 and RCP6 scenarios in NoRESM1-M model, respectively. In the baseline period, the share of precipitation in winter is 65.8%, spring 5.1%, summer 1.8% and fall 27.4%. Crop yield change depends on the type of crop and its irrigation period. Because of the 77% water requirement of lima bean crop in winter, the average yield of this crop increases by 19%, as models show that the share of precipitation in winter increases by 9%. Also, 75% of water requirement of wheat and 44% of water requirement of eggplant is in autumn and winter that increased and stabilized rainfall in these seasons caused slight variations in yield. In contrast, 80%of water requirement of corn crop is in summer, and due to the severe decrease in precipitation in summer (15%), corn yield has decreased by 17%.