Coupling coordination relationship between urbanization and water environment in China

The intensification of urbanization (U_UR) in China exacerbates the pressure on the water environment (U_WE). The U_UR and U_WE exhibit incredibly intricate and intertwined interactions. The coordination between U_UR and U_WE is crucial for the sustainable development of cities. Hence, a comprehensive evaluation index system was developed to analyze the coupling coordination relationship and spatial effects between the U_UR and U_WE in China, based on the entropy weight method, the coupling coordination degree (CCD) model, and the spatial autocorrelation analysis method. The data was collected from the China Statistical Yearbook (2013-2023), the China Urban Construction Statistical Yearbook (2012-2022), and provincial statistical yearbooks. The results indicated that the overall trend of CCD in China showed an upward trajectory, increasing from 0.44 to 0.55 in 2012 to 0.56-0.66 in 2022. The average values of CCD for 31 provinces rose from 0.51 in 2012 to 0.61 in 2022, with a growth rate of 19.61%. The regional development level of CCD exhibited spatial heterogeneity, characterized by East > North > South > Northeast > Northwest > Southwest. However, the development of the U_WE subsystem lagged behind the U_UR subsystem, and there was a significant spatial imbalance in the CCD between the U_UR subsystem and U_WE subsystem in China from 2012 to 2022. The High-High Cluster areas of CCD were concentrated in the eastern part of China, while the Low-Low Cluster areas were concentrated in the western part. The research can provide theoretical and technical support to promote the sustainability of urban development and water environment protection.