Exploration of coupling effects in the Economy–Society–Environment system in urban areas: Case study of the Yangtze River Delta Urban Agglomeration

The rapid development of the economy and society in China has led to a series of environmental pollution problems. Exploring the interaction and coupling effects within the Economy–Society–Environment (ESE) system in urban agglomeration areas is conducive to promoting high-quality sustainable urban development. Based on systems theory, we constructed an ESE system with multiple elements, information and interaction flows. Taking the Yangtze River Delta Urban Agglomeration (YRDUA) in the period from 2010 to 2018 as a research sample, we used the Entropy Method (EM) and the Coupling Coordination Degree Model (CCDM) to synthetically evaluate the coupling coordination degree of the ESE system. The Back-Propagation Artificial Neural Network (BPANN) was applied to explore the influencing factors of the ESE system’s coupling coordination degree considering the nonlinear relationship between the various indicators and the ESE system’s coupling coordination degree. The main results can be summarized as follows. (1) The coupling coordination degree of the ESE system and the comprehensive quality of its subsystems in the YRDUA showed trends of growth during 2010–2018. There were obvious spatial differences: Shanghai had the highest quality scores, Jiangsu and Zhejiang had medium values, and Anhui had the lowest scores. However, these disparities continued to decrease during the study period. The overall coupling coordination degree distribution presents a normal distribution shape, most of cities concentrated in the moderate coordination grade. (2) At present, the coupling coordination of the society-environment binary system makes a great contribution to the ESE ternary system. (3) The comprehensive quality of the economy provides strong support for sustainable social and environmental development. (4) Factors such as the urbanization rate, proportion of tertiary industry in GDP, per-capita retail sales of consumer goods are critical to the coordinated development of the ESE system.