A quantitative methodology for the assessment of the regional economic vulnerability to flash floods

Economic losses caused by flash floods are expected to rise worldwide in the coming decades, which is largely due to the increasing exposure of elements at risk. Therefore, a comprehensive analysis of the economic context of the potentially affected areas is highly recommendable. Numerous papers have been published to date that focus on quantifying vulnerability in general and in areas affected by floods in particular. However, the number of studies devoted to flash flood-prone areas is far lower. Integrated economic vulnerability assessment enables one to learn what characteristics explain, trigger, intensify, and attenuate the exposure, sensitivity, and resilience of economically vulnerable populations, which can be combined to achieve an Integrated Economic Vulnerability Index (IEVI). The methodology deployed here was conducted in Castilla y León (northwest Spain; 94.223 km2) and has allowed the economic vulnerability of urban areas to be analyzed, which has been primarily addressed by the estimation of economic losses or, more recently, including a few economic variables within social vulnerability assessments. Thus, 118 economic variables were initially gathered and then divided into groups through a hierarchical segmentation analysis. Subsequently, variables were combined employing a principal components analysis, giving rise to the economic vulnerability factors that were subsequently aggregated to construct the IEVI. Tolerance statistic was used as a weighting method to define the IEVI, whereas quintiles were chosen as a statistical criterion to map economic vulnerability. As a final step, latent class cluster analysis was implemented to identify spatial patterns of vulnerability. Our findings show that IEVI scores have a high spatial variability and a high degree of complexity in the relationships among different vulnerability factors. Moreover, they help to identify spatial patterns of vulnerability, which makes the design of suitable vulnerability reduction strategies possible, thereby improving the efficiency of flood risk management plans and policies.