Assessing the network characteristics and structural effects of eco-efficiency: A case study in the urban agglomerations in the middle reaches of Yangtze River, China

Abstract

Crude economic development models create severe environmental pressures. Eco-efficiency (EE) is an important basis for evaluating ecological civilization in China. Under the national strategy of ecological priority and green development in China's Yangtze River Economic Belt, the urban agglomerations in the middle reaches of Yangtze River (UAMRYR) was considered as a case study and an evaluation index system of county EE was constructed based on multi-source remote sensing data, the EE values from 2009 to 2018 were measured by a super slack-based measure (Super-SBM) model, the spatial correlations of EE were revealed by an improved gravity model, the spatial network characteristics of EE were portrayed by social network analysis, and the nature of network effects were further explored by multiple linear regression models. Findings of the study included EE has been shown to be indeed spatially correlated.The EE of the nodes, the differences increased, the transmission pattern was relatively stable, and the association was characterized by bidirectional inequity. The spatial network of EE was characterized by small groups, whose tightness was small and increasingly loose overall, and the overall network operation efficiency is low. In terms of the spatial structure of individual network, the Degree Centrality (DC) showed the circle structure, the Closeness Centrality (CC) demonstrated ‘central collapse’, and the Betweenness Centrality (BC) evolved into five ‘core-periphery’ sub-groups from the ‘circle distribution’. Regarding the structural effects, in terms of EE improvement, the UAMRYR nodes were mainly through the agglomeration effect as well as dissemination channels and spillover paths, the core nodes were self-sufficient, and the edge nodes mainly relied on, the radiation role of core nodes, the transmission role of intermediary nodes, and their own active integration and connection roles. This study provides a new perspective for understanding EE and these findings are important for promoting the synergistic improvement of green development in China and other countries.