Future changes and distribution of water resources in China under global warming levels of 1.5–4.5 °C

Study region: China (excluding Hong Kong, Macao, and Taiwan). Study focus: Few studies have nationally evaluated China's spatiotemporal distribution of future runoff and per capita water resources (PCWR). Based on the SSP1-RCP2.6, SSP3-RCP7.0, and SSP5-RCP8.5 scenarios, the future runoff and PCWR in China under global warming levels of 1.5–4.5 °C are predicted. The calibrated Water and Energy Budget-based Distributed Hydrological Model with improved Snow physics for Global simulation (WEB-DHM-SG) was driven by the Inter-Sectoral Impact Model Intercomparison Project 3b (ISIMIP3b) protocol data to simulate runoff and future population data were used to predict the PCWR. Furthermore, the pre-industrial scenario was compared with future development scenarios to analyse the impact of human-induced climate change (HICC). New hydrological insights for the region: The average annual runoff would increase by 6.9–27.6 % nationally and increase in 28 provinces, whereas it would decrease in the other 3 provinces. Seasonal runoff decreased in winter but increased in the other three seasons. Runoff is affected by HICC by 4.1–30.0 %. The national average PCWR would change by −7.5 % to 20.4 %. Water shortage conditions might be further intensified in nine provinces but relatively alleviated in the other 22 provinces. Our results can provide scientific support for the future national and regional water planning and management in China.