Impacts of climate change on water resources and water environment in the Three Gorges Reservoir

Climate change is one of the major global issues commonly concerned by international communities. Taking the Three Gorges Reservoir which is the largest water conservancy project in China as the object, this study attempts to clarify the current conditions of water resources and water environment especially the spatial distribution characteristics of water resources amount and main non-point source pollution loads in recent years, and further predict the evolution trends of hydrological elements and evaluate the impacts of climate change on water resources and water environment through coupling the global climate models with the hydrological model employing a statistical downscaling method. The results indicate that, 1) currently, except the precipitation in Wanzhou, Shizhu and Xingshan is larger while less in Zhong, Fengdu and Zigui, and the runoff in Wuxi, Kai and Xingshan is larger while less in Fengdu and Zhong, the spatial distribution of annual precipitation and runoff in the region is relatively even and do not vary greatly in the other counties; the spatial distributions of total nitrogen load and total phosphorus load are similar with the characteristics that six counties including Yichang, Kai, Yunyang, Zhong, Wanzhou and Badong contribute more and four counties including Yubei, Nanan, Jiangbei and Wulong contribute less; 2) in the future, comparing with the historical average, the temperature in the region will increase by 1.3°C and the evapotranspiration will increase by 2.8%, while the precipitation, runoff and non-point source pollution load will decrease by 0.8% , 8.2% and 8% respectively. Although the precipitation will not change greatly, the reduction extent of runoff is larger than that of precipitation, bringing forward higher requirements for integrated water resources management in the Three Gorges Reservoir.