What are the two types of floods?

There are two basic types of floods: flash floods and the more widespread river floods. Flash floods generally cause greater loss of life and river floods generally cause greater loss of property.

A flash flood occurs when runoff from excessive rainfall causes a rapid rise in the water height (stage) of a stream or normally-dry channel. Flash floods are more common in areas with a dry climate and rocky terrain because lack of soil or vegetation allows torrential rains to flow overland rather than infiltrate into the ground.

River flooding is generally more common for larger rivers in areas with a wetter climate, when excessive runoff from longer-lasting rainstorms and sometimes from melting snow causes a slower water-level rise over a larger area. Floods also can be caused by ice jams on a river or high tides, but most floods can be linked to a storm of some kind.

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October 14, 2009

Streamgages: The Silent Superhero

Whether you drink water from your tap, use electricity or canoe down your local river, chances are you benefit from USGS streamgage information. So what is a streamgage and what does it do for you? This CoreCast episode gives you the inside scoop on your silent superhero.

Transcript and captions available soon.

USGS CoreCast
June 18, 2008

Two 500-Year Floods Within 15 Years?

We talk to Bob Holmes about some of the recent flooding events occuring in the Midwest, how does a 500-year flood occur twice in 15 years, and what do the recent events have in store for folks downriver.

Image: Flooded Neighborhood
June 12, 2008

Flooded Neighborhood

Flooded neighborhood near Wilson Ave. SW and Hamilton Street SW

Attribution: Natural Hazards
June 4, 2008

How are floods predicted?

Listen to hear the answer.

February 20, 2008

Are there different types of flooding?

Listen to hear the answer.

February 5, 2008

We had a "100-year flood" two years in a row. How can that be?

Listen to hear the answer.

Stream water flowing over a rural road.
June 30, 2006

A flooded road in Highland County, Virginia.

Streamwater flowing over a rural road in Highland County, Virginia, June, 2006.

February 19, 1993

Flash Floods: USGS Against the Water

A glimpse at the often dangerous task USGS employees make every year to obtain stream flow measurements from flood events.