Coupled Coordination Analysis and Driving Factors of “Water-Carbon-Ecology” System in the Yangtze River Economic Belt

Driven by global population growth and resource shortages, the coupled and coordinated development of the “Water-Carbon-Ecology” (W-C-E) nexus has emerged as a crucial factor for sustainable societal development. This study constructs a multidimensional evaluation model for the W-C-E system in the eleven provinces and municipalities of the Yangtze River Economic Belt (YEB), encompassing the richness of individual systems, the coordination between dual systems, and the robustness of the tertiary system. We propose the “W-C-E Nexus Index” (WCENI) to analyze the coupling and coordination levels among the W-C-E systems in these regions from a bottom-up perspective. Utilizing the obstacle degree model and geographical detector model, we explore the impact of key indicators on the coupled and coordinated development of the W-C-E system. The findings reveal the following: (1) The coordination index and robustness index among the three W-C-E subsystems have increased significantly, while the richness index of individual subsystems varies widely among the YEB. (2) During the study period, the WCENI for the YEB rose from 0.351 to 0.391, indicating an overall upward trend in the coupling and coordination among the W-C-E subsystems. Jiangsu recorded the highest average WCENI value of 0.445, topping the list of the eleven regions. (3) The interaction between pairs of driving factors exceeds the influence of any single factor, with per capita water consumption emerging as the primary driver for the coupled and coordinated development of the W-C-E nexus in the YEB, with an average obstacle degree of 12.05%. These findings provide a theoretical basis for regional coordinated management and sustainable development.