Flood exposure of critical infrastructures in the United States

Abstract

This study provides a nationwide spatial assessment of flood exposure of critical infrastructures (CI) in the United States. By combining the FEMA flood maps and the USGS National Structure Database, the exposure of CI facilities to 100-year-flood was estimated for the country and states. Spatial analyses and statistical tests were conducted to analyze variations of flood exposure of the CIs in different states, counties, sectors and categories. At the national level, the ratios of CI flood exposure ranges from 2.7% to 27.1% in different sectors. The spatial analyses indicate that the southern states near the Gulf Coast (particularly Louisiana and Florida) have a high exposure ratio in most of the CI sectors. Hot spot analysis was applied to detected local clusters of high flood exposure, where actions of flood risk reduction should be potentially prioritized. By comparing the flood exposure of the CI facilities with the general urban exposure (i.e. baseline exposure), states and CI sectors where the flood exposure is deviated from the expected value are identified. This study reveals the general trend of CI flood exposure in the U.S. and identified outliers deviated from the trend. The underlying factors behind these deviations are discussed. Overall, this study provides valuable information for U.S. policy-makers at different levels to better evaluate and mitigate potential flood risk from these ‘lifeline’ systems.