Investigation of Climate Change Impacts on Inflow Discharge to Jarreh Dam Using the Output of CMIP5 Models

Nowadays, global warming and climate change phenomena are considered as the most important threats to water resources and sustainable agricultural development. Due to the limitation of water resources in Iran, population growth and subsequent water demand increase, investigation of the effects of climate change on the water resources systems and agriculture is an important issue. In this study, the effect of climate change on inflow discharges to Jarreh Dam reservoir located in Zard River Basin was investigated. For this purpose, using the performance weighting method, among 20 atmospheric general circulation models (GCM), three models were chosen that were more compatible with historical data (CSIRO-Mk3.6.0, MIROC-ESM and GFDL-ESM2M). Then, precipitation and air temperature values at a height of two meters above the ground in future periods and under RCP4.5 and RCP8.5 climate scenarios were estimated. In order to rainfall- runoff simulation and estimating the inflow to the dam reservoir, the IHACRES model was applied and the daily precipitation, temperature and discharges series recorded at the Mashin Hydrometric Station in the period of 1976- 2005 were used to optimize the model parameters. After downscaling and generating the precipitation and temperature series and verifying the accuracy of the IHACRES model, the corresponding inflow discharge to dam reservoir for every climatic scenario was simulated. The results showed that the value of inflow to dam reservoir has decreased under both considered scenarios. The annual average of inflow into Jarreh Dam reservoir will decrease 27 and 40 percent under RCP 4.5 and RCP 8.5 scenarios, respectively.