Simulation of Hydro-Climatic Variables by AOGCMs, Evaluating the Range of Changes in Variables, Due to Climate Change, in Upper Dez (Dez Oliya) Basin

Climate change, in addition to increasing temperature, causes changes in the duration, intensity, form, and timing of rainfall in different parts of the Earth, which can cause droughts and floods. It also changes the volume, duration, and runoff duration, which will bring about many developments and changes in the water-resource management (Kamal and Massah Bavani, 2009). In order to reduce inconsistencies, studying the impacts of climate change on water resources is necessary. One of the most widely used models for these future studies is Atmosphere-ocean General Circulation Models (AOGCMs) (Wilby and Harris, 2006). In general, most studies present a high degree of uncertainty as a result of using AOGCMs in the simulation of climate change and hydrology parameters. the outputs of simulated water-resource models under climate change could be relied on when the uncertainties are taken into account at all stages (Semenov and Stratonovitch, 2010). In order to innovate the research method, in this study 10 AOGCMs under three greenhouse gas emission scenarios (A1B, A2, and B1) were used in the simulated range of hydro-climatic variables through climatic models and downscaling methods in the Dez Oliya basin during 2040-2069. In Summary, when reviewing the range of hydro-climatic variable changes in the future period, it could be observed that the uncertainty of AOGCMs under all three emission scenarios is greater than the downscaling methods.