Effects of Climate and Land-Use Change on the Supply and Demand Relationship of Water Provision Services in the Yellow River Basin

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.