Flash floods

Dateline article| David Murphy|

by David Murphy

Flash floods are, as the name implies, floods that occur quickly (in a flash), usually with very little warning. These floods are often the result of sudden downpours from heavy thunderstorms which raise water levels rapidly over portions of waterways.

Flash floods can turn gentle streams and creeks into raging water in a matter of minutes, or even seconds. Flash floods can also occur near storm drains and sewers when heavy rains saturate those passages and the water backs up onto normally flood-resistant areas. A given area is usually more prone to flash flooding after recent storms have saturated the ground, making it more apt to send run-off into neighboring creeks and streams.

Flash floods are the number one cause of weather related deaths in the U.S. and are a particular problem across most of our region, thanks to our hilly terrain and various soil types, some of which have limited ability to absorb water.

The fast moving, quick-rising water often surprises pedestrians and drivers as it overtakes roads and walkways. Only a few inches of fast-moving water can knock a person off their feet and only a couple of feet of water can float most cars. Once a car is afloat, it can be easily transported into deeper water where it can capsize. Cars also stall easily in relatively low water as it splashes up underneath the hood and into the engine. A stalled car is more susceptible to rising water.

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