Measurement of green development energy level and analysis of obstacle factors in the Yangtze River Delta urban agglomeration based on the improved WRSR model and obstacle degree model

Accurately measuring the green development energy level of the Yangtze River Delta urban agglomeration and identifying its key drivers are crucial for promoting regional sustainable development, yet they remain complex challenges. This study first establishes a comprehensive evaluation index system covering four dimensions: green economy, green innovation, green support, and green openness. Combined weights are determined by integrating the G1 method and entropy method through game theory, and an optimized Non-integer Weighted Rank-Sum Ratio (WRSR) evaluation model is proposed. Subsequently, using the improved WRSR model and obstacle degree model, the green development energy levels of 27 representative cities in the region from 2006 to 2021 are measured and analyzed. The results indicate that: (1) The overall green development energy level of the agglomeration increased slowly from 0.275 in 2006 to 0.300 in 2021, with significant disparities among cities. (2) Cities are classified into four tiers, with Shanghai and Nanjing as higher-level cities, Wuxi, Changzhou, and Suzhou as high-level cities, Chuzhou, Xuancheng, and Anqing as low-level cities, and Chizhou as a lower-level city, revealing a core-periphery spatial pattern. (3) Green openness and green innovation are key influencing factors, with obstacles mainly arising from indicators such as foreign trade dependence, actual utilized foreign direct investment, and the number of full-time teachers in higher education institutions. This research provides a methodological reference for evaluating urban green development and offers targeted policy insights to support coordinated green transition across city tiers.