Social disparities in flood exposure and associations with the built environment in 47,187 urban neighborhoods in eight Latin American countries

BACKGROUND AND AIM: Climate change is expected to greatly increase population exposure to flooding and related health impacts, particularly in urban areas of the Global South. We aimed to examine within-city social disparities in exposure to flooding within 326 Latin American cities and associated features of the neighborhood environment. METHOD: We used a high spatial resolution dataset of historical flood events from 2000-2018 to describe flood exposure at the neighborhood level for all cities with 100,000+ residents in eight Latin American countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Guatemala, Mexico, and Panama). We estimated the percent of the population living in neighborhoods with one or more observed floods, comparing across neighborhood educational attainment quintiles. We also contrasted within-city disparities across study cities (i.e. Slope Index of Inequality). We modeled univariable city- and neighborhood-level factors of the urban environment associated with flood exposure. RESULTS: We examined 47,187 neighborhoods in 326 cities from eight countries with a total of 236 million residents, and over 150 distinct flood events from 2000-2018. Over 22% of residents in neighborhoods in the lowest education quintile lived in neighborhoods with flooding, while only 4.3% of residents in the highest neighborhood education quintile lived in flooded neighborhoods. Neighborhood flooding was associated with lower neighborhood-level educational attainment and with neighborhoods that were less dense (population or intersection), further from the city center, greener, and had steeper slopes (all p-values 0.05). There was no association between city-level educational attainment and flood risk. CONCLUSIONS: There are large social disparities in neighborhood flooding within Latin American cities. Residents of areas with lower education attainment face substantially higher risks of flooding. Neighborhoods that were less dense, more peripheral, greener, and had steeper slopes had higher odds of flooding. Policymakers must prioritize flood adaptation and recovery efforts in neighborhoods with lower socioeconomic position.