Contrasting Impacts of Climate and Vegetation Changes on Water Yield Across Global and Regional Scales

Abstract

Water yield (WY) is a key indicator of water availability and the mechanisms regulating WY have become increasingly complex with ongoing global changes in climate and vegetation. Existing studies remain confined to the relative contribution and interacting pathways of multiple drivers, providing limited insights into heterogeneity across different regions. This study conducted a global spatiotemporal analysis of WY using multi‐source remote sensing and meteorological data from 1982 to 2020, integrating the Random Forest model and Structural Equation Model to quantify the relative contributions and pathways of climate and vegetation changes to WY at global and regional scales (arid and humid regions). The results show: (a) WY increased at the global scale and in arid regions but decreased in humid regions; (b) Climate change contributed more to WY at the global scale (relative contribution ratio, R = 55.11%) and in humid regions (R = 62.00%), whereas vegetation change contributed relatively more in arid regions (R = 64.49%); (c) Globally, the Palmer Drought Severity Index (PDSI), vapor pressure deficit, and wind speed exerted positive effects on WY. Downward surface shortwave radiation and Leaf Area Index (LAI) had negative effects. Notably, the positive effect of PDSI weakened in arid regions but strengthened in humid regions, whereas the negative effect of LAI reversed. These findings highlight the nonlinear and regional responses of WY and provide a scientific basis for ecological restoration and water resource management.