Who is exposed and who is harmed? Social disparities in flood exposure and impact in Pernambuco, Brazil

How do geospatial sorting and social stratification condition natural-disaster exposure and impact? Using the case of the May 2022 flash floods in Pernambuco, Brazil, we address this question with a dual-source approach that captures disparities in both exposure to anomalously high rainfall and the reported impacts of resulting floods. While exposure to anomalous rainfall is tied to geospatial segregation patterns, reported impacts may also reflect localized infrastructure, such as drainage systems or piped water availability, that capture municipality-level investment and capacity to withstand flooding. Findings from exposure analysis reveal significant disparities by race, religion, maternal education, and income. However, these relationships fully attenuate after adjustment for municipal location, suggesting that settlement patterns and geospatial marginalization drive the observed exposure disparities. Findings from the analysis of self-reported flood impact also show disparate impacts by race, employment status, number of children under 15, and household income, but in this case, only racial disparities are fully attenuated after spatial adjustments. Further findings show that low-income households and those with more children report significantly greater impacts even after adjusting for both municipal fixed effects and hazard exposure. Interaction models reveal steeper dose-response relationships between rainfall and impacts for low-income households, and we find evidence that household infrastructure significantly mediates economic disparities in flood impacts. Combined, results demonstrate that relying solely on externally measured exposure to gauge the stratified impacts of extreme precipitation or flash floods may miss important socioeconomic disparities. Both geospatial segregation patterns and household-level capacities to withstand environmental shocks shape vulnerability. Supplementary Information: The online version contains supplementary material available at 10.1007/s11111-026-00523-z.