Hydrological responses and multi-pathway regulatory mechanisms associated with vegetation change in the Yellow River Basin

Vegetation change strongly influences watershed hydrological processes, yet its responses to climate change (CC) and human activities (HA) remain uncertain. Focusing on the Yellow River Basin (YRB), this study analyzed vegetation dynamics from 1982 to 2020 using long-term leaf area index (LAI) data combined with trend analysis, sensitivity assessment, partial correlation, and residual trend analyses to identify driving mechanisms. An enhanced SWAT model integrating remotely sensed LAI was coupled with the InVEST model and partial least squares structural equation modeling (PLS-SEM) to clarify how vegetation change regulates key hydrological processes. Results indicate that: (1) Vegetation cover in the YRB increased, with an average LAI growth rate of 0.0022 /a, and areas with significant greening accounted for 60.45% of the basin, particularly in the middle reaches. (2) HA dominated vegetation improvement (70.73%), surpassing CC (29.27%), although precipitation (PRE) remained the main climatic constraint. (3) Runoff displayed spatial heterogeneity, increasing in headwaters and upper reaches while decreasing in middle and lower reaches. (4) Incorporating LAI improved SWAT performance (R 2 increased by 0.015 and NSE by 0.10), and simulated water yield (WYLD) trends matched InVEST results. (5) Mechanistic analysis suggests that vegetation change primarily regulates hydrological processes by enhancing evapotranspiration (ET) and depleting soil water (SW), producing nonlinear effects on runoff depth (RD) and WYLD. These findings underscore the role of vegetation restoration in reshaping basin-scale water allocation and guiding water resources management under ecological restoration scenarios. • An integrated framework quantified climate and human contributions to YRB vegetation. • LAI incorporation improved SWAT performance (mean + 0.015 R 2 , +0.10 NSE). • A coupled SWAT–InVEST framework validated basin-scale water yield estimates. • Vegetation regulates runoff and water yield mainly via evapotranspiration and soil water use.