Considering the effect of climate change on catchment runoff by the use of HadCM3 model under the scenarios of greenhouse gas emissions (case study: Karun catchment area in SHalu bridge site)

Climate change is one of the most important challenges which has effect on river runoff. Warmer climatic conditions have intensified the water cycle, rainfall changes, runoff time and amount. There were several studies with different result on this subject all over the world. Due to the importance of karoun zone and lack of studies, the researcher tried to study the effects of this phenomenon on this zone. At first, temperature and monthly rain amount of HadCM3 model of A1B, A2 & B1 scenarios have been spatially downscaled by the use of LARS-WG model, then they have been temporally downscaled by the use of change factor method. In the next step, for simulation of runoff, the SRM model has been used. Relatively after calibration, with introduce downscaled temperature and rainfall amount the future period to the model, the simulation took place. The result show that the rise in temperature and change in rainfall in 2011-2030 period comparing the base period . And of course the comparison  of 2011-2039 runoff with base period shows that the runoff under 3 mentioned scenario increases consequently  %14 , %22 , %13.5 which necessitates a planning in the field of water resources management .