Investigating the effect of climate change on water flow and water balance of Latyan dam using SWAT model

The Climate change can be a major threat to biodiversity and ecosystem integrity. Therefore, prediction of hydrological behavior of watersheds for conservation and reconstruction of ecosystems is necessary. In this research SWAT semi-distribution hydrological model was used to evaluate water flow and water balance by changing climate in Latyan dam near Tehran during 1988-2014. Also, the output of the CMIP5 series model is under two scenarios RCP 2.6 and RCP8.5 for the near future using the model, LARS-WG was introduced into the mode.The result of stimulation for 2021-2050 showed that mean temperature increases by 0.75 C° for RCP 2.6 optimistic scenario and 1.45 C° for RCP 8.5 pessimistic scenario. In addition, rain was reduced by 2 % in RCP 8.5 and 5 % in RCP 2.6. The result for water flow showed that high level of water flow decreases by 2.4 cubic meter per second in May and increases by 1.49 in April. The water flow in RCP 8.5 scenario for May and June was greatly reduced which it can negatively affect level of water in dam until starting rain. Average evapotranspiration was increased by 3 mm in optimistic scenario and 8 mm in pessimistic scenario which it negatively affects the accessible water resource. Reduction of rain was predicted for two scenarios.