Scenario-based evidence for anthropogenic contributions to future water supply-demand risk in the Songliao Basin

Study region The Songliao Basin in Northeast China is a large temperate monsoon basin covering approximately 1.25 million km 2 . As a major grain-producing region, established industrial base, and ecological security barrier in China, it is characterized by pronounced seasonal and interannual variability in water availability, uneven precipitation distribution, and increasing water-use pressure associated with urbanization and socioeconomic development. These characteristics make it a representative region for investigating future water supply–demand risk under coupled climate and human influences. Study focus A scenario-based Water Supply–Demand Risk (WSDR) assessment and attribution framework was developed for the Songliao Basin under future SSP-RCP pathways. The framework integrated land-use simulation, water supply estimation, sectoral water-demand calculation, risk identification, and counterfactual attribution analysis into a unified system. This enabled a coupled assessmen of supply-side fluctuations and demand-side growth, while quantitatively distinguishing the relative contributions of climate change, human activities, and their interaction to future WSDR evolution. New hydrological insights for the region Future land use diverged markedly across scenarios, with cropland generally declining and urban land expanding most strongly under SSP5–8.5. Water supply remained highly variable, whereas total water demand increased steadily and reached 156.29 billion m 3 under SSP5–8.5 by 2100. In parallel, medium-high and high-risk zones expanded and became more aggregated under medium and high-development pathways. Attribution analysis suggested that, under the SSP-RCP scenarios, the WSDR intensification was more strongly associated with human activities, which generally contributed 60%-80% of total risk change, while climate change mainly amplified supply-side fluctuations. These results suggested that future water risk in the Songliao Basin was less related to a simple decline in water availability than to an increasingly pronounced mismatch between unstable supply and rising demand.