Balancing hydrological trade-offs through land-use regulation in a semi-arid watershed

Effective land-use regulation is a key policy instrument for shaping watershed hydrology and promoting sustainable regional development. However, current land-use policies often rely on uniform, single-objective that overlook spatial heterogeneity and integrated hydrological trade-offs. Here, we selected the Yanhe River Basin on the Loess Plateau, China, as a case study, where rapid land-use transitions have intensified water-resource constraints. SWAT model was applied to simulate hydrological responses under 15 slope-based land-use scenarios reflecting various policy options. An ecological indicator-based evaluation framework incorporating evapotranspiration (ET), water yield (WYLD), and soil moisture (SM) was developed to identify optimal subbasin-level regulation schemes and to assess their resilience under future climate scenarios. Results show that both ET and WYLD increased basin-wide from 2000 to 2022. Afforestation elevated ET and reduced SM, particularly in downstream areas, whereas grassland restoration moderated ET increases and enhanced WYLD. The most effective land-use strategy involves protecting existing cropland and converting slopes >15° in the upper–middle basin and > 5° in the middle-lower basin to grassland. This spatially differentiated strategy simultaneously reduces ET, while maintains SM and increases WYLD, offering the largest hydrological benefits both historically and under future climate conditions. The highest benefits were observed under SSP126 (WYLD +4.19%; ET −8.93 mm), followed by SSP585 (WYLD +3.96%; ET −8.69 mm). By translating hydrological trade-offs into slope- and subbasin-specific regulation rules, this study provides actionable policy guidance for optimizing land-use planning, improving water security, and aligning ecological restoration programs with hydrological constraints in the Loess Plateau.