Each year, more deaths occur due to flooding than from any other thunderstorm-related hazard because people underestimate the power and force of water.
Many deaths occur in automobiles as people and their vehicles are swept downstream. Many of these drowning accidents are preventable, but too many people continue to drive around barriers warning that roads are flooded. Whether you are driving or walking, if you come to a flooded road, stop and do not cross. With water across the roadway, you cannot always determine the depth of the water or the condition of the road under the water. Six inches of moving water can knock a person down and a mere two feet of water can move a large vehicle such as a bus.
Most flash floods are caused by slow moving thunderstorms, thunderstorms that move repeatedly over the same area or heavy rains from tropical storms and hurricanes. These floods can develop within minutes depending on the intensity and duration of the rain, the topography, soil conditions, and ground cover.
Flash floods can move boulders, uproot trees, destroy buildings and bridges, and scour out new channels. Occasionally, floating debris can accumulate at a natural or man-made obstruction and restrict the flow of water. Water held back by the debris jam can cause flooding upstream. Subsequent flash flooding can occur downstream if the obstruction should suddenly release.
Know What to Expect
Know your area’s flood risk. If unsure, contact the Office of Emergency Management for additional information.