Aassessing the Future Climatic Effects on the Hydrology of Qarahsu Watershed with the Approach of Ensemble General Atmospheric Circulation Models

Document Type : Research Paper


1 Department of Water Engineering, Faculty of Abureihan, University of Tehran, Tehran, Iran

2 Department of Environmental Sciences, Faculty of Science, University of Zanjan , Zanjan, Iran


Climate change and its impact on water resources is very important. The purpose of this study is to evaluate the effect of different weighting methods of AOGCM models on runoff in Qarahsu basin in the period 2021-04. rom 23 general circulation models, the best climatic models (HADGEM2-ES, MICRO IPSL-CM5A-LR, NOERESM1-M, ESM2M-GFDEL) were selected that were adapted to the observation basin and they were weighed by three weighting methods including the same method, Bayesian method and REA method. Then, by downscaling the climate models and introducing them to the SWAT model, the range of runoff changes in the basin in the future period was determined. The results showed that there is no specific pattern for a better weighting method among them. The highest temperature increase will occur in the Bayesian model (May) and the lowest increase will occur in the REA model (November). Rainfall also decreased in most months. Prediction of runoff changes using the output ensemble of climate models using hydrological model showed that in the next period the lowest percentage of runoff changes in REA method and the highest percentage of runoff changes in Bayesian method will be extruded. Overall, the results indicate a change in the temporal distribution of flow in the Qarahsu Basin in the coming period, which will cause significant changes in the quality and quantity of water resources


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