Social vulnerability to natural hazards in São Paulo, Brazil

Global projections of climate change are generally linked to an increase in extreme weather events like extreme precipitation. Thus, improving risk management strategies depends on knowing what the most vulnerable to natural disasters areas and populations are. In this study, the Social Vulnerability Index (SoVI), created by Cutter et al. (Soc Sci Q 84(2):242–261, 2003) is used to identify those areas and populations in the city of Sao Paulo, Brazil. This flood-prone area has high levels of social inequality and has not been evaluated from the perspective of vulnerability to natural disasters, but from the economic one. The study is focused on examining the basin-level social vulnerability in the city of Sao Paulo in the year 2010. Based on the principal component analysis, a SoVI was computed for the city. Results were displayed on maps and then analyzed to monitor trends in spacial distribution. Five main components were found in the analysis: ‘Urbanization level and vulnerable populations’ that explains 21 % of all social vulnerability, ‘Favorable environmental and social conditions’ explaining 18 %, ‘Alternative basic sanitation solutions’ (14 %), ‘Unfavorable social conditions’ (10 %) and ‘Development indicators’ that explain 8 %. Vulnerability increases in the center–periphery direction. Sixty-nine point seven percent of the basins were classified within the medium vulnerability score, 23.2 % within medium–high or medium–low vulnerability and 7 % within very low, low, high or very high vulnerability. These results show that the components contributing to social vulnerability are different for each basin and represent how social fragmentation of the city hinders efforts of risk management strategies.