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Flood-Related Mortality -- Missouri, 1993

Public health surveillance documented the impact of flood-related morbidity following the floods in the midwestern United States during the summer of 1993 (1,2). Because of extensive flooding of the Missouri and Mississippi rivers and their tributaries, the Missouri Department of Health (MDH) initiated surveillance to monitor flood-related mortality. This report summarizes epidemiologic information about deaths in Missouri that resulted from riverine flooding and flash flooding during the summer and fall of 1993.

To identify flood-related deaths, CDC and MDH telephoned and obtained epidemiologic information from medical examiners and coroners (ME/Cs) in the 71 disaster-declared counties and in St. Louis (1990 combined population: 4,166,122) and contacted coroners of 24 counties adjacent to disaster-affected areas (1990 combined population: 435,127). A flood-related death was defined as a death resulting from an event that occurred after June 28 (when flash floods began to occur and the potential threat of riverine flooding was recognized by the State Emergency Management Agency) and would not have happened -- given the information provided by ME/Cs -- had the floods not occurred. Summer Flood-Related Mortality

From July 1 through August 31, ME/Cs from disaster-declared counties classified 27 deaths as flood-related. Decedents' ages ranged from 9 years to 88 years (mean: 37.8 years); 18 (67%) were male. No flood-related deaths were reported in adjacent counties.

Of the 27 deaths, 21 were directly related to the floods and resulted from drowning; six were indirectly related to the floods (i.e., flood-related activity with no direct physical contact with flood water). Thirteen of the 27 deaths were motor-vehicle-related (i.e., associated with operating or riding in a motor vehicle). Of the 16 (59%) deaths directly related to flash flooding, 14 resulted from drowning; of these, eight deaths occurred in four separate motor-vehicle-related incidents. Of the 11 (41%) deaths directly related to riverine flooding, seven resulted from drowning; of these, three deaths occurred in separate motor-vehicle-related incidents. Of the six deaths indirectly related to the floods, two each were attributed to electrocutions that occurred during cleaning efforts in or while reentering a flooded residence or business, stress-induced cardiac arrests, and trauma from motor-vehicle crashes in which usual traffic patterns were diverted because of rising water.

Of the 21 drownings, 10 were associated with recreational activities. Six drownings occurred in one incident when a flash flood inundated a cave in which the victims were exploring, and four drownings occurred in separate incidents associated with riverine flooding. Fall Flood-Related Mortality

Flooding from heavy rains that occurred periodically from late September through early November contributed to 16 additional deaths: 14 were motor-vehicle-related, and two occurred when rising waters from the Missouri River flooded homes. Four deaths were associated with the Missouri River and 12 with smaller rivers or creeks. Reported by: HD Donnell, Jr, MD, State Epidemiologist, R Hamm, MD, Office of Epidemiology, Missouri Dept of Health. Emergency Response and Coordination Group, and Disaster Assessment and Epidemiology Section, Health Studies Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health, CDC.

Editorial Note

Editorial Note: Patterns of flood-related mortality vary according to flood type as determined by hydrologic characteristics (3). Flash floods, characterized by high-velocity streamflow and short warning and response times, have the greatest potential for causing death. In contrast, because riverine floods usually are caused by gradual accumulation of heavy rainfall, warning times are sufficient to allow safe evacuation of nearby communities. In Missouri, both flash flooding and riverine flooding occurred almost simultaneously on two major rivers and on other smaller rivers and creeks.

During the summer and fall floods of 1993 in Missouri, drowning was the leading cause of flood-related deaths -- similar to other hydrologic disasters (3-6). Furthermore, a large proportion of flood-related drownings have been attributed to operating or occupying motor vehicles, particularly during flash floods. This may reflect motorists' misconception that motor vehicles can provide adequate protection from rising or swiftly moving flood waters. In this report, 75% (27/36) of the drownings that occurred during the summer and fall floods in Missouri were motor-vehicle- related.

The findings in this report underscore the importance of two strategies for preventing flood-related injuries and death. First, information about flood and post-flood hazards must be disseminated rapidly and widely to groups at increased risk for injury. For example, motorists should be warned not to drive through areas inundated by flash floods, not to enter swiftly moving water, and that only 2 feet of water can carry away most automobiles (7). In addition, recreational activities, such as wading or bicycling, in flooded areas should be discouraged. Second, hydrologic studies and hazard analyses should address potentially flood-prone tributaries. The hazard potential of such areas during flash floods should be identified, and appropriate warning signs should be posted. MDH is continuing surveillance of flood-related mortality to monitor circumstances of death.


  1. CDC. Public health consequences of a flood disaster -- Iowa, 1993. MMWR 1993;42:653-6.

  2. CDC. Morbidity surveillance following the Midwest flood -- Missouri, 1993. MMWR 1993; 42:797-8.

  3. French JG. Floods. In: Gregg MB, ed. The public health consequences of disasters. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1989:39-49.

  4. French JG, Ing R, Von Allmen S, Wood R. Mortality from flash floods: a review of National Weather Service reports, 1969-81. Public Health Rep 1983;98:584-8.

  5. Duclos P, Vidonne O, Beuf P, Perray P, Stoebner A. Flash flood disaster -- Nimes, France, 1988. Eur J Epidemiol 1991;7:365-71.

  6. Wintemute GJ, Kraus JF, Teret SP, Wright MA. Death resulting from motor vehicle immersions: the nature of the injuries, personal and environmental contributing factors, and potential interventions. Am J Public Health 1990;80:1068-70.

  7. National Weather Service/American Red Cross/Federal Emergency Management Agency. Flash floods and floods...the awesome power!: a preparedness guide. Washington, DC: US Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service/American Red Cross, 1992; report no. NOAA/PA 92050, ARC 4493.

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