A Situation-Based Analysis of Flash Flood Fatalities in the United States

Abstract

Abstract This paper investigates the circumstances of 1,075 fatalities from flash flooding recorded from 1996 to 2014 across the United States. This study provides insights into the situations of the fatality events as determined by the victims’ profile and activity and the spatiotemporal context of the flooding. A reclassification of the individual fatality circumstance (i.e., location and/or activity) is performed to explore statistically the timing, the duration, and location of the flash flood event and the age and gender of the victims. In agreement with other studies, more than 60% of the reported fatalities were related to vehicles involving mainly males. A geospatial analysis indicated these were most common in southern states. Further, 21% of fatalities occurred outdoors, typically in neighborhoods near streams, where the victims were exhibiting high-risk-taking behavior, such as cleaning out drains and even playing in the floodwaters. Human vulnerability varies dynamically on a subdaily basis and depends on social and natural factors of the flash flood. For example, most campsite-related fatalities were associated with very fast-responding flash flood events (less than 5-h duration), occurred more commonly after midnight, and impacted younger females and males alike. On the other hand, fatalities related to inundation of permanent buildings were most commonly associated with longer-duration events and impacted the elderly. Situational rather than generic examination of vulnerability is required to realistically capture risky cases during short-fuse flood events. The circumstances in which people perished in flash floods suggest that situational rather than generic examination of vulnerability is required to realistically capture risky cases during short-fuse flood events.