Evaluating the impact of climate change on runoff using hydrological model (Case study: Bazoft-Samsami Watershed)

Increasing greenhouse gases in recent decades and increasing its resulting temperature has causes the imbalance of the Earth’s climate system and widespread climate changes in most regions of Earth planet. Development strategic policy in this area has been forced with a big challenge because of the need for water in the central region on the one hand and water resource constraints on the other hand. In this study, first, WetSpa rainfall-runoff model was calibrated for Bazoft-Samsami watershed as one of the important sub-basins of Karun basin. Then, values of temperature and precipitation for future period were downscaled based on climate change scenarios with atmospheric general circulation model outputs (HadCM3) for three scenarios of A1B, A2 and B2 using LARS-WG model. Then, to simulate the basin runoff, data were introduced to WetSpa model. The results verified the performance of LARS-WG model in estimating rain and temperature. Also, the results showed that runoff in statistical periods of 2011-2040 and 2071-2100 compared with observation period in all three scenarios has increased %8.86 and %4.83, respectively, and has decreased in 2041-2070 to the amount of %7.25. This subject indicates the impact of climate change on runoff in mid-term future period in studied watershed. So, considering the obtained results, the policy of programming in order to adapt to climate change is necessary in Bazoft-samsami watershed.