Temporal-spatial assessment of the vulnerability of human settlements in urban agglomerations in China

Although many studies have focused on the livability and satisfaction of the human settlement environment in Chinese cities, few have paid attention to the vulnerability of human settlements in urban agglomerations in China (VHSUAC). The analytic hierarchy process and the entropy method are combined in this paper to comprehensively weight the constructed four-dimensional evaluation index system. Then, we identified the key factors influencing VHSUAC. Finally, we use the environmental vulnerability index (EVI) to calculate the vulnerability value from 2008 to 2017 and display the vulnerability changes over time and space using ArcGIS software. The results show that (1) from the perspective of temporal pattern, VHSUAC showed a downward trend from 2008 to 2017, but the degree of decline in each urban agglomeration was not equal. There is a certain difference in the vulnerability value of the human settlement environment between the urban agglomeration and its inner cities, and their direction of change is not always the same. (2) From the perspective of spatial pattern, VHSUAC has obvious regional heterogeneity, presenting a spatial pattern of "low coastal areas and high inland areas." Coastal urban agglomerations pay more attention to the optimization of the human settlement environment. (3) In terms of influencing factors, the vulnerability values of the four system indicators are listed in the following order: economic support environment>urban ecological environment>public service environment>urban living environment. We found that domestic waste and sewage treatment have a more obvious impact on VHSUAC.