The Yellow River Basin (YRB) has undergone profound climate and land-use change. These transformations are anticipated to affect the availability of water resources, potentially causing substantial perturbations to the equilibrium between water availability and societal needs. Consequently, research is warranted to explore the ramifications of climate and land-use change on the water provision service, particularly their impacts on the delicate equilibrium between supply and demand. To quantify the water supply–demand relationship, this study introduces the water supply and demand index (WSDR). This study examines the impacts of climate and land-use change on the actual evapotranspiration, water yield, and WSDR in the YRB from 1995 to 2019. According to the results, the YRB experienced an increase in forest land by 4.72%, grassland by 1.71%, and a substantial surge of 595.36% in construction land; however, cropland witnessed a decrease of 5.95%. The climate exhibited a discernible wetting trend (3.38 mm/year, p < 0.01). The actual evapotranspiration significantly increased by 2.45 mm/year (p < 0.01), but this increase was not substantial enough to result in a decline in the water yield, since precipitation also increased. The annual water demand depth demonstrated a statistically significant increasing trend (0.13 mm/year, p < 0.01), but this increase was not sufficient to cause a decrease in the WSDR, since the water yield also increased (0.94 mm/year). Land use had a significantly negative effect on the water yield and WSDR, but this negative effect was offset by the positive effects of climate variability. At the basin scale, there exists a surplus of water resources (WSDR > 0). Nevertheless, regions grappling with water resource deficits (WSDR < 0) have witnessed an increase from 18% in 1995 to 26% in 2019. This indicates that the primary water resource problem in the YRB is the uneven spatial distribution of water resources. Hence, implementing spatial management strategies at larger scales may be instrumental in mitigating water scarcity in the region. These findings can serve as a valuable reference for the management of water resources, as well as for basin planning and construction.

Leaf area index (LAI) is a key vegetation structural parameter widely used to quantify vegetation dynamics. A thorough understanding of its spatiotemporal characteristics and driving mechanisms is essential for sustainable ecosystem management. This study combines LAI and climate remote sensing data with socioeconomic statistics, and uses the Geographically and Temporally Weighted Regression (GTWR) model and geographic detector to identify the key drivers of LAI changes and their spatial differentiation characteristics. The results indicate a significant upward trend in the LAI across the basin, with a markedly higher growth rate after 2000 (0.0123/year) compared to the period before 2000 (0.0028/year). Spatially, before 2000, 57% of the regions showed an increasing trend in LAI, while after 2000, 69% of the regions exhibited an increasing trend in LAI. In terms of temporal LAI dynamics, in the eastern region, the positive promotion effect of the Grain for Green policy (GRGR) was the most significant factor affecting LAI changes. In the central region, the employed population ratio (EPR) emerged as the dominant factor driving LAI increase. In the western region, the negative effect of the urban–rural income ratio (IR) served as the primary driver of LAI change. Regarding the spatial distribution of LAI, both natural and policy factors were statistically significant. Mean precipitation (MP) and mean slope (MS) exerted the most pronounced influences, followed by mean temperature (MT) and GRGR, whereas mean elevation (MD) showed the weakest effect. Notably, socioeconomic factors did not demonstrate statistically significant impacts on the spatial distribution of LAI. This study provides a theoretical foundation for understanding the driving mechanisms of LAI dynamics in the Yellow River Basin and offers scientific support for ecological restoration and sustainable management in the region.