Estimates of present and future flood risk in the conterminous United States

Past attempts to estimate rainfall-driven flood risk across the US either have incomplete coverage, coarse resolution or use overly simplified models of the flooding process. In this paper, we use a new 30 m resolution model of the entire conterminous US with a 2D representation of flood physics to produce estimates of flood hazard, which match to within 90% accuracy the skill of local models built with detailed data. These flood depths are combined with exposure datasets of commensurate resolution to calculate current and future flood risk. Our data show that the total US population exposed to serious flooding is 2.6–3.1 times higher than previous estimates, and that nearly 41 million Americans live within the 1% annual exceedance probability floodplain (compared to only 13 million when calculated using FEMA flood maps). We find that population and GDP growth alone are expected to lead to significant future increases in exposure, and this change may be exacerbated in the future by climate change.

Impact/Purpose

This study uses outputs from a new version of EPA's Integrated Climate and Land Use Scenarios (ICLUS) in conjunction with a novel procedure for mapping floodplains to provide new estimates of flood exposure, under both current and future conditions. The study is generally consistent with other global change impacts assessment work taking place within ORD, in that the study incorporates future projections of population and land use consistent with climate change projections and scenarios.

Citation

Wing, O., P. Bates, A. Smith, C. Sampson, K. Johnson, J. Fargione, AND P. Morefield. Estimates of present and future flood risk in the conterminous United States. IOP Publishing LIMITED, Bristol, UK, 13(034023):1-7, (2018). [DOI: 10.1088/1748-9326/aaac65]

DOI: Estimates of present and future flood risk in the conterminous United States