A study on the spatial and temporal variation of urban integrated vulnerability in Southwest China

Natural hazards and urbanization put enormous pressure on cities and affect their sustainable development. Against the backdrop of the increasingly prominent urban disease, a comprehensive urban vulnerability assessment has a positive effect on improving the quality of urbanization. In this study, prefecture-level cities in Southwest China were taken as the study area, and their vulnerability was studied dynamically from 2010 to 2019. The four major systems were integrated, and a comprehensive vulnerability evaluation index system was constructed. Game theory and TOPSIS were combined to minimize the impact of subjective factors on the results. The results indicate that the overall vulnerability of Southwest China shows an irregular downward trend and strong spatial heterogeneity. There are 5 cities with very high vulnerability and 1 with very low vulnerability in 2010, accounting for 15.15% and 3.03% of the total number of cities, respectively. In contrast, the results for 2019 are the opposite, with 1 city with very high vulnerability and 5 cities with very low vulnerability. The better the economic situation, the lower the urban vulnerability. And there is a non-strictly negative correlation between urban vulnerability and urban size. When the difference in size between two cities is large enough, the vulnerability of the larger city is significantly lower. Leading development cities such as Chengdu and Chongqing have low vulnerability, while high vulnerability is mainly distributed in cities with poor infrastructure. On the basis of results, the research can be regarded as reference for urban management and coordinated development.