Potential impacts of landuse changes on the supply–demand relationship of water resources in semiarid loess hilly regions

In ecologically fragile semiarid loess hilly agricultural regions, water resources constitute a critical constraint on sustainable development. Previous studies have demonstrated that landuse changes significantly affect the spatiotemporal distribution of water through vegetation cover modifications and hydrological process shifts. This study aims to predict future landuse changes and assess their impacts on water supply and demand, thereby providing a basis for sustainable water resource management. The current study employed an integrated PLUS-Markov chain approach (with a high validation accuracy, OA > 0.9 and Kappa > 0.83) complemented by the InVEST model to project landuse arrangements under three scenarios (NIS, FSS, and EDS) for Guyuan city in 2030, 2040, and 2050, and to analyze the consequent spatiotemporal evolution of water supply and demand risks. The results indicated that by 2050, the cropland under the NIS scenario decreased by 6.7%, primarily transitioning to grassland. In contrast, the FSS scenario led to a substantial increase in cropland by 10.7%, resulting in an overall reduction in built-up area. Meanwhile, the EDS scenario drove rapid urbanization, with a built-up area expansion rate reaching 2.99 km²/year, largely at the expense of cropland. By 2050, landuse change was projected to exert minor influences on the regional water supply, with only a 7.8% variation projected compared with 2030 levels, whereas substantial impacts were projected for the water demand, which increased by 43.3% during the same period. Notably, approximately 90% of Guyuan's area may face water security risks by 2050, particularly in ecological reserves and urban zones, with the risk severity increasing over time. Several adaptive strategies were proposed to reconcile land-water relationships, thereby offering practical solutions for sustainable agroecosystem management in semiarid loess hilly regions.