Flood exposure and social vulnerability in the United States

Eric Tate,Md Asif Rahman,Christopher T Emrich,Christopher C Sampson

doi:10.1007/s11069-020-04470-2

Eric Tate, Md Asif Rahman + Show 2 more

Open Access

https://doi.org/10.1007/s11069-020-04470-2

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Abstract

Human exposure to floods continues to increase, driven by changes in hydrology and land use. Adverse impacts amplify for socially vulnerable populations, who disproportionately inhabit flood-prone areas. This study explores the geography of flood exposure and social vulnerability in the conterminous United States based on spatial analysis of fluvial and pluvial flood extent, land cover, and social vulnerability. Using bivariate Local Indicators of Spatial Association, we map hotspots where high flood exposure and high social vulnerability converge and identify dominant indicators of social vulnerability within these places. The hotspots, home to approximately 19 million people, occur predominantly in rural areas and across the US South. Mobile homes and racial minorities are most overrepresented in hotspots compared to elsewhere. The results identify priority locations where interventions can mitigate both physical and social aspects of flood vulnerability. The variables that most distinguish the clusters are used to develop an indicator set of social vulnerability to flood exposure. Understanding who is most exposed to floods and where, can be used to tailor mitigation strategies to target those most in need.

Highlights

Inland flood exposure continues to rise in the USA, driven by changes in precipitation and development in floodplains
This study explores the geography of social vulnerability to inland flood exposure in the conterminous United States (CONUS)
Most current measures of social vulnerability are generalized, meaning similar sets of indicators tend to be applied across a wide range of hazards, geographies, and disaster phases

Summary

Introduction

Inland flood exposure continues to rise in the USA, driven by changes in precipitation and development in floodplains. National-level understanding of population exposure is limited, in part constrained by the lack of spatially contiguous floodplain data. Flood exposure is higher for socially vulnerable populations (Lee and Jung 2014; Rolfe et al 2020), especially for inland floods (Qiang 2019). FEMA maps depict the spatial extent of the 1% annual chance flood (100-year flood) for communities enrolled in the National Flood Insurance Program. FEMA flood maps have varying levels of quality and spatial coverage, with notable gaps in small catchment areas and low population communities (Qiang et al 2017; Wing et al 2017). Nationwide, there are significant differences among FEMA maps in the underlying input data, analytical methods, and recency (Wing et al 2018; Pralle 2019)

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