Future Surface Water Resources Sensitivity to Climate Changes Impacts

Abstract — Due to water resources limitation in most parts of Iran, it is essential to give especial attention on evaluating and managing water resources. Climate changes would significantly affect water resources in future. In this study clime change impacts on water resources has been evaluated. "Karun " as the most watery river in Iran with an annual discharge of 4927.4 MCM at the site of Karun4 dam, is selected as case study. For this purpose 28 scenarios for precipitation and temperature, by using 11 models of AOGCM (Atmosphere-Ocean Global Circulation Model) models from CCCSN (Canadian Climate Change Scenario Network) are established and downloaded for next 90 years. Scenarios are downscaled for being usable for the study region. Evapotranspiration scenarios are generated by models which are provided for the case study region. The precipitation and temperature scenarios are used as input data by the mentioned models to generate future evapotranspiration scenarios. Multivariable empirical regression models based on 30 years monthly historical recorded data are generated to predict future monthly discharge scenarios. All of the models are tested with historical data. The precipitation, temperature, evapotranspiration and discharge scenarios are taken into account to estimate future surface water resources. The study shows that there would be a reduction of 17.20 % (38.63 mm/year) in precipitation and 31.51 % (58 m3/s) reduction in annual discharge by the end of 2100. Also annual temperature would have a raise about 22.65 % (3.82 ° C). River runoff would have 27.8 % reduction and would cause more than 25 % reduction in water surface resources