Evaluation of Climate Change Impact on Runoff: A Case Study

Background/Objectives: In this study we have investigating Evaluation of Climate Change Impact on runoff. Methods/Statistical Analysis: In this study, outputs of HADCM3 (Hadley Center Coupled Model, version 3) GCM (General Circulation Model) under A2 scenario is used to investigate the climate change impact on runoff of Gaveh Rood catchment in western Iran. The SDSM (Statistical Down Scaling Model) is employed to statistically downscale climate variables of temperature and precipitation. A runoff-rainfall Hydrological Model, named HYMOD is used for developing runoff time series under climate change impacts regarding the downscaled climate variables. Findings: The performance of calibrated SDSM model shows its well performance in rainfall and temperature downscaling in the study area. The downscaling results show considerable changes in temperature and precipitation in future under climate change impacts. In the period of 2020-2099, the mean temperature and precipitation is increased by 5-8.5% and 3-5%, respectively, relative to the observed period of 1989-2000. The calibration and validation results of the developed HYMOD show that it the mean runoff decreased by 7-16% (11.5%, on average) in the predicted period relative to the observed period. Applications/Improvement: These changes highly affect the water resources systems and special attention should be given to them in future planning of water resources.