Spatial and temporal differentiation characteristics of green development levels in urban agglomerations within the Yangtze River economic Belt and analysis of influencing factors

Green development is one of the core elements of high-quality regional development. The Yangtze River Economic Belt stands as the primary area for China's pursuit of sustainable development. This study analyzes the changes in water resource depletion values within the urban agglomeration of the Yangtze River Economic Belt, as well as the overall scale structure. A total of 44 indicators were selected from the three dimensions, namely green environment, green lifestyle, and green economy, to establish an evaluation index system aimed at assessing the level of green development. Through the application of the entropy-TOPSIS method, geographical detectors, and spatial autocorrelation analysis, the spatial and temporal differentiation variances in green development levels were examined, as well as the influencing factors across 73 cities situated within the three major city clusters from 2000 to 2020. The results show that: (1) The total value of water resource depletion in the three major urban agglomerations exhibits a fluctuating downward trajectory, reaching its lowest point in 2020. (2) City sizes within these three major urban agglomerations are relatively centralized, with high-ranking cities exhibiting limited prominence, showing weak leading advantages. (3) The green development level exhibits an overall upward trend from 2000 to 2020. Cities with higher levels of green development are mainly concentrated in the Yangtze River Delta and the capital cities are situated in the upper and middle reaches. (4) Key influencing factors of the green development level include carbon emissions per unit of GDP, length of drainage pipe per capita, gross domestic product per capita, disposable income of urban residents per capita, and water consumption per unit of GDP. The spatial variance in these indicators explains over 60% of the green development level. Based on the research results, this paper puts forward three policy recommendations: first, to grow the green industry. The second is to promote green municipal infrastructure planning. The third is to encourage regional synergistic cooperation and play the role of radiation leadership of core cities.