Hydrological response to future climate changes in Chehelchay Watershed in Golestan Province

The hydrological effects of climate change is a great challenge for water resources management. Determining climate change impacts on hydrological process is a prerequisite for adaptation strategies to climate change; which in turn is necessary for water scarcity crisis in future. The purpose of this research is to determine climate change impacts on hydrologic regim of Chehlcahy Watershed in Golestan Province. J2000 distributed process based model was used for simulation of the hydrological process. Output results of seven climate models including CanESM2، CCSM, BBC-CSM1.1, CESM1-BG, CESM1-CAM5, ICHEC- EC-EART and MPI-M-MPI-ESM-LR for two representative concentration pathways scenarios (RCP 4.5 and RCP 8.5) for 2071-2100 were used for climate change analysis. Results revealed that the maximum temperature for RCP 4.5 and RCP 8.5 in 2071-2100 will increase by 2.6 and 4.7 C and the minimum temperature will increase by 2.4 and 4.5 C, respectively by the end of the 21st century . In addition, precipitation for RCP 4.5 will increase by 0.6 percent and for RCP 8.5 decrease by 0.6 percent. Modeling results showed that these will lead to significant changes in the hydrological regime. In particular, evapotranspiration will increase by 9.6 and 16.7 percent and stream flow will decrease by 4.2 and 3.2 percent. The results of the  hydrological changes will cause a decrease in stream flow in April –June  and  for RCP 8.5 will be continued till October.