Assessing flash flood hazard and damages in the southeast United States

Flash floods are common natural hazards in the southeast United States (SEUS) as a consequence of frequent torrential rainfall caused by tropical storms, thunderstorms, and hurricanes. Understanding flash flood characteristics is essential for mitigating the associated risks and implementing proactive risk management strategies. In this study, flash flood characteristics including frequency, duration, and intensity are assessed in addition to their associated property damages. The National Oceanic and Atmospheric Administration (NOAA) Storm Events database as well as hourly precipitation data of the North American Land Data Assimilation System project phase-2 (NLDAS-2) are utilised, and more than 14,000 flash flood events during 1996-2017 are analysed. Flash flood hazard is investigated at county, state, and regional levels across the SEUS. Results indicate increasing pattern for the frequency and intensity of flash flooding over the SEUS. The frequency of flash flooding is found to be higher in spring and summer, whereas the duration and intensity of events are higher during winter and fall, respectively. The western parts of the SEUS are prone to more frequent and intense flash flooding compared to the eastern parts. Overall, our analyses suggest that flash flood hazard in Louisiana is higher than other states in the SEUS.