Coupling SDSM downscaling climate and WMS hydrologic models in Khansar basin for runoff prediction under future climate change conditions

In recent years downscaling models are increasingly used in predicting climate variables. One of the application of the downscaling general circulation model (GCM) is used to predict the hydrological watershed. In this study, using rainfall data during the observed period (1961-1990), in the first step using SDSM model and data HadCM3 scenario A2, were simulated runoff in Khansar watershed located in southern Yazd previence. Then anticipated rainfall-runoff Khansar basin in 30-year period (2011-2040). After downscaling and forecast rainfall Meshkan station, the nearest meteorological stations in Band-paein basin, implemented rainfall and runoff forecasting Band-paein Station at the same period. The results show that, despite the fact that rainfall in the forecast period is 6% higher than the normal period, the rate of runoff from 19.3 million cubic meters during the 30 year period (normal climate) of 1971-2000 to 17.4 million cubic meters The period will be from 2011 to 2040, which is about 9% lower. The effects of changes in the distribution of rainfall means an important issue in the future, climate change is one of consequences. Therefore, it need to planning and management of water resources, particularly for the study in arid areas.