Coupling coordination and driving mechanisms of water resources carrying capacity under dynamic water-economy-ecology interactions in the Tianshan North Slope Economic Belt

Water resources carrying capacity (WRCC) reflects the interactions among water resources, socioeconomic development, and ecological conditions and is fundamental to sustainable development in arid regions. Taking the Tianshan North Slope Economic Belt in Xinjiang as the study area, this study investigated the evolution, coupling coordination, dynamic interactions, and driving mechanisms of WRCC from 2000 to 2023 using an integrated framework combining comprehensive assessment, coupling coordination analysis, PVAR, GTWR, and GeoDetector. The results showed that: (1) WRCC showed a pronounced stage-wise evolution from persistent overload toward a critical carrying state. After remaining predominantly overloaded during 2000–2006, it improved steadily through 2007–2015 and reached a peak of 0.68 in 2016, followed by a gradual decline to 0.45 in 2023, approaching the lower bound of the critical carrying interval. Overall coupling coordination remained transitional, fluctuating mainly between slight and moderate coordination. (2) The water resources subsystem was the core of the dynamic interactions among the three subsystems, and significant bidirectional feedback existed between water resources and the ecological environment. By contrast, within the short-term lag structure, the socioeconomic subsystem did not exert direct leading shocks on either water resources or ecology, and the system as a whole displayed a shock-response pattern of rapid convergence and weak transmission. (3) The spatial differentiation of WRCC was primarily controlled by hydrological supply and ecological conditions, while socioeconomic pressures exerted stronger effects only in specific sub-regions. Water-resource drivers dominated in most regions, and ecological indicators, particularly FVC and NDVI, had the strongest explanatory power for interregional differences. Interactions among hydrological, ecological, and socioeconomic factors were generally stronger than the corresponding single-factor effects, with bi-factor and nonlinear enhancement prevailing and further amplifying the spatial differentiation of WRCC. These findings reveal the dynamic and spatially heterogeneous mechanisms of water-economy-ecology interactions and provide a basis for differentiated water-resource management, ecological regulation, and regional carrying-capacity improvement in arid areas.