Hydrological Impact of Climate change on the GavehRud Watershed as Affected by the Parameter Uncertainty

The latest investigations have demonstrated the climate change is definitely happening. As the climate change strongly impacts the global temperature and rainfall, and their variabilities, it highly affects water resources, thus the environment, as well as agricultural and industrial activities. In this study, the climate change impacts on the Gavehrud basin runoff during the 2016-2099 periods was investigated using the outputs of the HadCM3 GCM model under the A2 scenario. The SDSM (statistical downscaling model) was used for the statistical downscaling of temperature and rainfall. For simulation of the future runoff using the downscaled data, HYMOD model was used. The HYMOD was calibrated using the DREAM model for considering its parameters uncertainty. The SDSM results indicated a considerable change in temperature and rainfall, in the future as compared with the historical time horizon of 1989-2000. The mean temperature increase in the future would be about 5% to 8.5%, while the mean rainfall decrease would be about 3% to 5%. The results of this study indicated that a 5% to 23% decrease in the future average runoff in comparison to the historical values.