Abstract
Flood losses worldwide have increased over the last century, and they will continue to increase even under stringent climate mitigation and adaptation strategies. Along the United States Gulf and East coasts, flooding can result from various drivers including pluvial, fluvial, or coastal contributions and it can be caused by one or multiple of those drivers. Assessing how those flood drivers individually and combined cause flood losses in terms of property and crop damage, injuries, and fatalities is a challenging task. Top-down approaches typically start with the flood driver characterization and then rely on models to simulate flood hazard and combine it with exposure and vulnerability information. This is computationally expensive at large spatial scales and relevant data for model development and validation is often not readily available. Here, we follow a bottom-up approach which starts with county-level flood losses (from 1980 to 2020) as recorded in the Spatial Hazards Events and Losses Database of the United States (SHELDUS). We link those losses to hydrometeorological data to explore how different flood drivers contributed to losses along the U.S. Gulf and East Coasts. We assess the role of compound events, where two or more flood drivers exceeded high thresholds at the time of a loss event, versus univariate events where only one flood driver was extreme and hence likely the main cause of the recorded losses. The results highlight the spatial variability of the relative importance of different flood drivers and the crucial role of compound events in generating high impact events. For example, the share of compound flood events varies across the region from less than 50% to close to 100% (indicating that almost all recorded flood losses were likely caused by compound events). Precipitation is the flood driver that is most often involved in those compound events, followed by river discharge, soil moisture, and coastal flood drivers (i.e., storm surges and waves). This is one of the first attempts of using empirical loss data for compound flood analysis and while data challenges remain, the framework and results derived provide a new perspective to the existing compound flooding literature.
CITATION
Wahl, T., Ali, J., Morim, J., Enriquez, A. R., Emrich, C. T., & Gall, M. (2024). Dissecting Flood Losses Along the United States Gulf and East Coasts (GC51B-03). AGU Fall Meeting 2024, Washington, D.C., 13 Dec 2024.