Multiscalar spatial analysis of urban flood risk and environmental justice in the Charlanta megaregion, USA

Abstract

Abstract Previous research exploring the environmental justice implications of urban flood hazards has produced contrasting results due to the different dasymetric mapping techniques used, the various spatial scales of the analyses, and the specific geographical context of the individual study cities, particularly as it relates to the presence of coastal water-based amenities. To better understand if vulnerable populations are disproportionately exposed to urban flood hazards in non-coastal cities, this study assessed the magnitude of socio-economic inequities in flood risk throughout the Charlanta megaregion. Specifically, population characteristics within the 500-year flood zone were estimated using United States Census Bureau data for race, ethnicity, and poverty by applying three dasymetric mapping techniques at four spatial scales. Risk ratios were used to statistically evaluate if vulnerable populations were overrepresented in areas at risk for flooding overall as well as for lake and non-lake regions. Although the results varied according to the scale and socio-economic variable, the most accurate dasymetric mapping approach indicated that environmental injustices were systemic, as vulnerable individuals were between 14% and 42% more likely to reside in areas at risk for flooding when analyzing the entire megaregion. At the metropolitan scale, vulnerable individuals were still significantly more likely to reside in flood zones, and the influence of lake amenities on the disparities was nuanced. A complex spatial landscape of inequities was also observed at the county and census tract levels. Overall, the notable disparities faced particularly by non-Hispanic black and Hispanic populations suggest that urban flood risk inequities in the megaregion are largely due to structural forms of discrimination and residential segregation, which have been pervasive throughout the development of Charlanta.