Spatiotemporal evolution and configurational pathways of synergistic green development in the Yangtze river economic belt

While the Yangtze River Economic Belt (YREB) serves as a strategic frontier for ecological civilization, existing scholarship lacks a systemic analysis of the co-evolutionary logic and governance configurations governing the synergistic green development (SGD). Utilizing panel data from 2011 to 2024, this study employs coupling coordination modeling, Social Network Analysis (SNA), and Qualitative Comparative Analysis (QCA) to evaluate its synergistic developmental quality. The findings indicate that SGD levels exhibit a fluctuating upward trajectory, facilitating a paradigmatic shift from "downstream-led breakthroughs" toward "basin-wide inclusive upgrades". However, this progression has simultaneously induced intensified internal "center-periphery" polarization. Such spatial evolution has catalyzed a structural transformation of the association network, migrating from a polarized "dense-East, sparse-West" pattern toward a polycentric, grid-based collaborative ecosystem, as evidenced by the rise of inland hubs like Chongqing and Wuhan. Causally, high-efficiency synergy originates from structural spillovers within the Government-Market-Society (GMS) framework. Through the equivalence relation between capital investment and human capital, modernized social governance effectively compensates for the rigidities of administrative mandates. Consequently, the basin's driving mechanism demonstrates a spatial transition from "government-led compensatory intervention" in the upper reaches to "endogenous synergetic drive" in the lower reaches. This study elucidates a policy pathway for achieving sustainable regional growth through functional compensation and pathway substitution.