Quantifying future water and energy security in the source area of the western route of China's South-to-North water diversion project within the context of climatic and societal changes

Study region: Yalong River Basin (YLRB), China.Study focus: The YLRB was selected to investigate the impacts of climatic and societal changes on water and energy security in the water-diverting area of China's South-to-North water diversion project (SNWD-W). The future runoff and hydropower generation were projected using Watergap hydrological model (WGHM) under different Representative Concentration Pathway (RCP) scenarios and water withdrawals were predicted based on the shared socio-economic pathways (SSPs).New hydrological insights for the region: The results show that the future runoff and hydropower generation in the YLRB display significant increasing and decreasing trends under RCP8.5 and RCP2.6, respectively. The water stress index (WSI) is projected to increase by about 30%, but it is still lower than 0.2 even combined with the SNWD-W project. The future hydropower generation is projected to change by - 0.87-4.75% and 0.44-6.10% under RCP2.6 and RCP8.5 without water diversion, respectively. The slight increment caused by climate change cannot offset the substantial decrement caused by water diversion, especially in the maximum transfer amount scenario, which highlights the tradeoffs between the mitigation of water stress in the waterreceiving area and the loss of hydropower generation in the water-diverting area. Our results provide a valuable reference for the water resources administration in the YLRB and the design of the water diversion scheme for the SNWD-W.