Spatiotemporal Evolution and Optimization of Urbanization–Water Environment Coupling in the Cheng-Yu Region

With global urbanization on the rise, China has entered the mid-to-late urbanization stage, and the Cheng-Yu region, as a key economic zone and new urbanization model in China, has faced water environmental issues due to rapid urbanization, while systematic research on the synergy between its urbanization and water environment governance remains scarce. This study explores the spatiotemporal evolution of and optimization strategies for the coupling and coordinated development of urbanization and water environment governance in the Cheng-Yu region. A comprehensive evaluation index system was established to measure the Urbanization Development System (UDS) and Water Environment Governance System (WEGS), and a coupling coordination model was utilized to analyze the spatiotemporal relationships between the two systems from 2013 to 2021. The coupling coordination index of the two systems showed a steady upward trend from 2013 to 2021, evolving from a state of severe imbalance to high-level coordination. Initially, the UDS was relatively low, while the WEGS was higher but grew at a slower rate. After 2019, rapid urbanization caused the UDS to exceed the level of the WEGS, indicating growing environmental pressures. Moreover, there are persistent disparities among cities. Industrial cities like Chengdu, with a high UDS but low WEGS, urgently need to enhance water resource management. In contrast, cities such as Dazhou, which have a high WEGS but low UDS, should make full use of their water resources to drive sustainable urban development. For policymakers, this research provides practical guidelines, such as suggesting targeted investment in water treatment facilities in industrial cities like Chengdu and promoting water-based economic development in cities like Dazhou. It emphasizes the importance of balancing urbanization with environmental sustainability. The findings not only deepen the understanding of the dynamic interactions between urban development and water environment governance but also lay a solid foundation for optimizing future policies in the Cheng-Yu region and other similar areas.