Evaluation of Statistical downscaling method in simulation of climate change of Karkheh basin up to the Karkheh dam

In recent decades the rapid growth of industrial activities has caused imbalance in climate of the earth which is so called named climate change. This phenomenon directly affects meteorological parameters such as temperature and precipitation. The objective of this research is investigation of the impacts of climate change on precipitation and maximum and minimum temperatures in Karkheh River Basin during the period of 2010-2039. The representative climate model of the region using AOGCM and observed data period of 1971-2000 was selected. Comparison of performance indicators of few AOGCM models for rainfall and temperature simulation showed that generally HadCM3 model is suitable for the region using synoptic and climatological weather stations of the region. Statistical and regression downscaling was carried out for the selected AOGCM. Statistical and regression downscaling was performed using statistically dynamic model of SDSM. The final results for near future, 2010-2039, shows 2% reduction in rainfall for both synoptic stations of Kermanshah and Khoramabad in the north of the basin and 4% reduction in Hamidieh climatological weather station in the south of the basin. The increase in maximum temperature for above stations are estimated as 119 and 3% and increase in minimum temperature are 24,4 and 1% respectively. Using HadCM3 and SDSM for near future, 2010-2039, simulation shows that as we move from north to the south of the basin (colder climate to warmer climate) the effects of climate change on maximum and minimum temperature are less pronounced while the trend for rainfall, although small, is opposite and is 2% for the north and 4% for the south.