Flash Floods

Flash floods - rapid rises in water levels with high flowdry to quickly absorb the water and the lack of plant
velocities - can occur in a matter of seconds. Factorslife to slow the water's course.
such as rainfall intensity and duration, as well asAreas with a high risk of flash floods (such as the land
regional topography, can all contribute to a flash floodsurrounding large dams) often have warning systems
situation. Urbanization is also an important cause ofin place to help alert the population in advance of a
flash floods. The roofs, sidewalks, and roads of a cityflood. The forecast center for your region calculates
create dangerous amounts of runoff water during bigflash flood guidance for all the bodies of water in the
storms, and this runoff can easily become a flash floodarea. Flash flood guidance is the amount of rainfall for
if an adequate storm sewer system is not in place.a given duration necessary to produce flash flooding.
In mountainous regions the rainfall can run down aWith these figures readily available, weather services
steep mountain and pick up so much speed that itcan provide predictions and early warnings to give
becomes a dangerous wave moving too fast forinhabitants of the region time to move to higher ground.
people to escape. A similar situation occurred in RapidIf you live in a region that is prone to flash floods, make
City, South Dakota, in 1972 when 237 people weresure you have a map to the quickest region of high
killed.ground. Also, make sure you monitor weather service
Even deserts are not immune to flash flooding. Dryannouncements during big storms in case of a flash
riverbeds can channel water long distances and createflood warning.
dangerous flood waves, due to the ground being too