Development and application of a social vulnerability index (SOVI) to landslide risk analysis in ribeira medium valley, Brazil

Abstract

In the last decades, the frequency and intensity of natural disasters in Brazil has increased, resulting in substantial economic, environmental, and social damage. Knowing the specific vulnerabilities of populations exposed to risks reflects on their disaster preparedness, response, and recovery capacities. However, social vulnerability studies in Brazil are still incipient. This study developed a Social Vulnerability Index (SoVI) for the Ribeira Medium Valley to fill this gap. The region is highly susceptible to landslides, and is one of the most impoverished and underdeveloped regions of the state of São Paulo, with a predominantly rural population. The index was composed by selecting 30 variables from 373 census sectors. Principal Component Analysis (PCA) was used to extract seven principal components, accounting for 71.64% of the data variability. The obtained SoVI scores were mapped and subsequently applied in a risk analysis. The most vulnerable municipalities were identified, and each vulnerability component's spatial distribution was visualized. It was also noted that the areas most vulnerable to landslides are also the most socially vulnerable. The results of this study can steer the government towards actions aimed at reducing social vulnerability. They may also help in developing disaster risk mitigation strategies.