Vulnerability to urban flooding assessed based on spatial demographic, socio-economic and infrastructure inequalities

Urban flooding is a priority in natural risk management and mitigation because it is the most frequent natural disaster in densely urbanised environments. This research explores flood vulnerability in cities by developing an index that can be easily implemented across the world. Our methodology is based on the arrangement of a series variables into three different classes (demography, socioeconomics and infrastructure) and the determination of their spatial variability through a Principal Component Analysis (PCA). We tested the proposed approach in the city of Santander (Spain) where a vulnerability index map was generated based on the combination of the proposed classes. The analysis show that we can reduce complexity from an initially identified 159 relevant variables to 16 representative and impactful variables in terms of spatial variance. Classification of the variables into three different classes made it possible to quantify the main causes of vulnerability to flooding across space. We produce a flood risk map by integrating our findings with a flood hazard map for the same area. This flood risk map gives urban planners detailed information about the most affected areas and allows them to design measures that mitigate the severity and effects of floods optimising available resources.This research was funded by the Conselleria for Innovation, Universities, Science and Digital Society of the Generalitat Valenciana through the project CIGE/2021/079, as well as by the Spanish Ministry of Science and Innovation (MCIN) and the Spanish State Research Agency (AEI) through the project PID2021-122946OB-C33 financed by MCIN/AEI/10.13039/501,100,011. Alejandro Roldán-Valcarce thanks the Spanish Ministry of Science, Innovationfor funding his investigations at the University of Cantabria through a Researcher Formation Fellowship, grant number PRE2019-089,450