Deciphering Spatial-Temporal Dynamics of Flood Exposure in the United States

Keywords: Flood Exposure, Urban-Rural Disparities, Flood Zone; Moran’s I, Natural Hazard, Spatial Analysis
Abstract Type: Paper Abstract

Abstract

Extracting baseline information on flood exposure and its temporal evolution is essential to formulate flood risk reduction strategies. At present, there is a lack of comprehensive, long-term spatial-temporal flood exposure research in the United States. The objective of the study is to evaluate county-wise flood exposure in the US and unravel its spatial-temporal dynamics from 2001-2019 to answer three research questions. First, how do the proportions of human settlement areas expose to flood threats in the US change through time? Second, do higher flood occurrences and damages lead to less development in the flood zone? Third, do disparities in the sensitivity to flood threats exist between urban and rural communities? Three corresponding hypotheses were examined. Results show that the rate of developed areas in flood zones in the contiguous United States has decreased from 2001-2019. It indicates that communities have become more responsive to flood threats. Counties with a high percentage of developed land in flood zones are primarily clustered in flat land proximal to rivers or coasts. Local Moran’s I analysis discovers pockets of clusters of communities that show a rapid increase of developed areas within flood zones over time. Counties experiencing higher flooding occurrences and damages are more responsive to flood hazards by avoiding development in flood zones. Urban communities are more sensitive to floods by reducing developed land growth in flood zones compared to rural areas. This study generates essential baseline information for policymakers and disaster practitioners to reduce flood losses, improve flood mitigation policy and strategy.