Mega-city region sustainability assessment and obstacles identification with GIS–entropy–TOPSIS model: A case in Yangtze River Delta urban agglomeration, China.

Sustainability is related to support the huge population and improve the residents' well-being in the Mega-city regions. Sustainability assessment is necessary under the context of implementing the Sustainable Development Goals in 2030. Refer to SDG 11, this study constructed an index system, assessed the sustainability level based on the theory of "weak" and "strong" sustainability and screened obstacles of 26 cities in the Yangtze River Delta (YRD) by applying a combined method of GIS–entropy–TOPSIS. The results showed that the overall sustainable level of the YRD improved, while its spatial pattern is relatively stable from 2007 to 2016. Furthermore, the co-operation effect within regions was unstable and unbalanced, due to the lack of interaction and influence among cities. In addition, the obstacles of each city gradually shifted from strong sustainable factors to weak sustainable factors. This paper also provided corresponding solutions regarding government management practice. • The overall sustainability level of the YRD improved obviously during 2007–2016. • The spatial correlation of sustainability among cities was weak and unstable. • The sustainability of megacities was more affected by weak sustainability factors. [ABSTRACT FROM AUTHOR]