Assessing the Impacts of Population Shrinkage on Agricultural Water Resource Utilization and Environmental Carrying Capacity in Northeast China

Investigating the dynamic interplay between population shrinkage and water resource carrying capacity holds critical implications for safeguarding national food security and ecological resilience. This study systematically examines the underlying mechanisms and spatiotemporal evolution of their coupling relationship in Northeast China, thereby advancing the theoretical framework of human–land systems and delivering empirically grounded insights for sustainable regional development. Drawing on balanced panel data from 34 prefecture-level cities in Northeast China over the period 2010–2023, this study develops a population shrinkage index grounded in registered population dynamics. Building upon the DPSIR (driving forces–pressures–state–impacts–responses) conceptual framework, we construct a comprehensive evaluation system for agricultural water resource carrying capacity, explicitly operationalizing each of its five dimensions. Employing a spatial Durbin model (SDM), we rigorously estimate the direct effect of population shrinkage on carrying capacity, while simultaneously testing the mediating pathways through human capital accumulation and fiscal policy interventions. The empirical analysis reveals that (1) over the study period (2010–2023), population shrinkage in Northeast China intensified progressively, expanding spatially from initially localized pockets to widespread, regionally contiguous areas. Concurrently, agricultural water resource carrying capacity displayed pronounced spatial heterogeneity and statistically significant spatial clustering. (2) Overall, the degree of population decline significantly negatively affects agricultural water resource carrying capacity. Further heterogeneity tests showed that this negative effect exhibits significant variation across different population-contracted regions and provinces. Among the control variables, urbanization rate, per capita GDP, and total water resources availability exhibit statistically significant positive associations with agricultural water resource carrying capacity (3) Over the study period, higher human capital endowment and greater fiscal intervention intensity significantly attenuated the adverse effect of population shrinkage on agricultural water resource carrying capacity.