A flash flood is a rapid flooding of water over land caused by heavy rain or a sudden release of impounded water (e.g., dam or levee break) in a short period of time, generally within minutes up to several hours, a timescale that distinguishes it from fluvial floods. It also includes freshet, which is a great rise or overflowing of a stream caused by heavy rains or melted snow and huayco or huaico (Quechua term waygu meaning “depth, valley”) which are Peruvian terms referring to flash floods caused by torrential rains in high mountains.
Characteristics: Flash floods are typically characterized by raging torrents in response to heavy rainfall that rip through riverbeds, urban streets, or mountain canyons sweeping away large debris and sediment with them. The Federal Emergency Management Agency (FEMA) characterizes it as a flood with a quick rise in water surface elevation with abnormally high water velocity often creating a “wall” of water...
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