Measurement and drivers of interprovincial water resource carrying capacity in China

China faces a persistent spatial mismatch between water-resource availability and socioeconomic demand, while pollution and uneven regional development further intensify water stress. This study develops an integrated framework combining support–pressure decomposition, multi-scale water resource carrying capacity (WRCC) assessment, and spatial mechanism analysis. Using panel data for 30 provincial-level administrative units in China from 2012 to 2023, the Grey Relational Entropy method is applied to evaluate water-resource support, pressure, and overall WRCC, while Spatial Durbin Models are used to identify local and spatial spillover effects. The results reveal pronounced regional heterogeneity. WRCC is generally higher in southern and southwestern China because of stronger natural water-resource support, whereas northern and eastern coastal regions experience greater pressure from intensive socioeconomic activities. Water-resource endowment, precipitation, reservoir capacity, forest coverage, water reuse, and sewage treatment strengthen local support capacity. In contrast, low economic water-use efficiency, groundwater exploitation, domestic and agricultural water demand, and wastewater discharge increase local pressure. Significant indirect effects further indicate that water demand, pollution burdens, and governance outcomes can extend across provincial boundaries. Based on these findings, differentiated provincial water-demand management and stronger basin-level coordination in water allocation, groundwater regulation, pollution control, ecological compensation, and cross-regional monitoring are recommended.