Research on methodology for assessing social vulnerability to urban flooding: A case study in China

Cities are economically developed, densely populated, highly concentrated areas of social wealth and high social vulnerability to floods. Assessing social vulnerability to urban flooding (SVUF) is important for improving a city's ability to resist floods and reduce casualties and economic losses caused by disasters. However, owing to the abstract and complex nature of social vulnerability itself, the connotation of SVUF and the indicator system have not been standardised, and the rationality of the assessment methodology is controversial; therefore, assessing the SVUF faces great challenges. In this study, the connotation of SVUF was analysed based on social system theory. We considered the interactions between disasters and groups to construct a system of assessment indicators. The game-theory combinatorial weighting method (GTCWM) was used to determine the weights of indicator combinations, combined with the technique for order preference by similarity to an ideal solution (TOPSIS) to establish the SVUF assessment model. Zhengzhou City was taken as an example to verify the results of the model. The assessment results show that the Huiji District in Zhengzhou City has the lowest SVUF. Erqi and Zhongyuan Districts have similar SVUF, and both are at a medium level. Guancheng District has high SVUF. Jinshui District has the highest SVUF. Jinshui District is an old urban area with a large poor population, high unemployment rate, and old infrastructure, which makes its overall SVUF high and susceptible to flooding. This assessment model can provide a scientific basis for urban flood mitigation measures.