Impacts of inter-basin water transfer and land use changes on water yield service supply-demand risk

The growing disparity between water yield service (WYS) supply and demand poses a critical challenge to sustainable development in semi-arid regions. While inter-basin water transfer (IBWT) projects are widely implemented to alleviate water scarcity, their long-term impacts on WYS supply-demand dynamics under evolving land use patterns remain poorly quantified. This study addresses this gap by integrating land use simulations and ecosystem service modeling to assess future risks in the Fen River Basin, China. Using the PLUS model, we projected land use changes (2020-2030) under three scenarios: natural development (ND), ecological protection (EP), and economic growth (EG). The InVEST model quantified WYS supply, while demand was evaluated based on socioeconomic and land use data. A novel risk assessment framework incorporating IBWT effects revealed that rapid urbanization (notably cropland-to-artificial land conversion) could increase WYS demand by 12.0 × 10⁸ m³ under the EG scenarios by 2030. IBWT implementation reduced high-risk areas by 18.7%, particularly in midstream urban zones, though downstream regions showed limited improvement (only 0.7%). Geodetector analysis identified land use change (q = 0.68) and IBWT (q = 0.31) as dominant drivers, with spatially heterogeneous influences-artificial land expansion critically impacted upstream areas, while temperature and topography governed midstream risks. Our findings emphasize the need for scenario-specific strategies: restricting urban sprawl, diversifying water sources, and enhancing policy coherence. This integrated approach provides actionable insights for balancing water security and ecological sustainability in water-stressed basins.