USGS Science Helps Build Safer Communities —A National Threat

Presidential declarations related to flooding in the United States and Puerto Rico Can Happen Almost Anywhere In the late summer of 2005, the remarkable flooding brought by Hur- ricane Katrina, which caused more than $200 billion in losses, constituted the costliest in U.S. history.

However, even in typical years, flood- ing causes billions of dollars in damage and threatens lives and property in every State.

Natural processes, such as hurricanes, systems, and snowmelt, can cause floods. Failure of levees and dams and inadequate drainage in urban areas can also result in flooding.

On average, floods kill about 140 people each year and cause $6 billion in property damage.

Although loss of life to floods during the past half-century has declined, mostly Presidential disaster declarations related to flooding in the United States, shown by county: because of improved warning systems, Green areas represent one declaration; yellow areas represent two declarations; orange economic losses have continued to rise areas represent three declarations; red areas represent four or more declarations between due to increased and coastal June 1, 1965, and June 1, 2003. Map not to scale. Sources: FEMA, Michael Baker Jr., Inc., the development. National Atlas, and the USGS Science Helps Meet the Challenge Flood Impacts USGS Science Priorities Reduction of flood losses must be based on the best possible understanding of how and where floods happen and how • Cost $6 billion in average annual • National Streamflow Information they cause damage. losses Program: the Federal backbone for acquiring real-time and historical • Cause about 140 deaths each year streamflow information • Damage infrastructure, causing • StreamStats: a Web-based capability indirect losses due to disruption of of estimating streamflow informa- economic activity tion everywhere, including places • Threaten greater losses as increased lacking gages urbanization and coastal develop- • Flood forecasting: using historical ment lead to heightened data to enable flood modeling • Study , which directly affects the intensity and During the 1993 Midwest floods, boaters frequency of floods pass an airport in Chesterfield, Mo., Friday, July 9, 1993. (FEMA photo/Andrea Booher)

U.S. Department of the Interior Fact Sheet 2006-3026 U.S. Geological Survey Printed on recycled paper January 2006 For more than 100 years, the U.S. The USGS national streamgage Geological Survey (USGS) has played network forms the scientific basis both a critical role in reducing flood losses for long-term planning before and after by operating a nationwide streamgage floods and for emergency response dur- network that monitors the level and ing flooding. flow of the Nation’s rivers and streams. Collaboration Leads to Protection Through satellite and computer tech- The USGS works closely with the nology, streamgages transmit real-time NWS, the Army Corps of Engineers, and information, which the National Weather other Federal agencies and partners in Service (NWS) uses to issue warnings so every State, as well as many local govern- During flooding, USGS hydrographers pre- local emergency managers can get people ments, to fund and maintain about 7,000 pare to make a streamflow measurement at out of harm’s way, and operators of flood- streamgaging stations. These relation- the White River at Petersburg, In., Tuesday, control dams and levees use to take action ships ensure that scientific information is January 11, 2005. (Evansville Courier & to reduce flood impacts. always available. Press/Vincent Pugliese)

This information is also available to Looking Ahead the public at http://waterdata.usgs.gov/ The USGS will continue research on nwis/rt/. the physical and statistical characteris- tics of flooding, determining how flood Streamgages provide long-term data frequency changes with urbanization, that scientists need to better understand climate variability, and other factors for floods and to define flood-prone areas as locations nationwide. well. The USGS will also work to mod- The USGS has developed a flood-map- ernize the streamgaging network and increase its coverage and robustness. ping method that delivers online flood At the Sorlie Bridge between Grand Forks, maps—including time of arrival, depth, For areas without streamgages— N. Dak., and East Grand Forks, Minn., and extent of flooding—before a floodwaters from the Red River of the North hits. See http://pubs.water.usgs.gov/ roughly 90 percent of river basins in the United States—scientists are develop- crest at 54.35 feet, Tuesday, April 22, 1997. fs2004-3060/ for more information. ing new methods to gather streamflow This depth was more than 24 feet above flood information. stage and more than 4 feet above the previ- Streamgage data also help in designing ous record. (USGS photo) structures resilient to flooding and are the The USGS helps the public, policy- basis for the Federal Emergency Manage- makers, and the ment Agency’s (FEMA) National Flood community make informed decisions on Insurance Program, the only Federal how to prepare for and react to flood haz- insurance program for natural hazards. ards and reduce losses from future floods.

Flood Facts

• The 1993 Midwest flooding was the costliest river-related flood in history, at $20 billion. USGS biologists prepare to launch a wet- lands research boat for search and rescue • More than half of all fatalities during floods are auto related, usually the result in New Orleans during flooding from Hur- of drivers misjudging the depth of water on a road and the force of moving ricane Katrina, Sunday, September 4, 2005. water. A car can float in just a few inches of water. (USGS photo) • The principal causes of floods in the Eastern United States and the Gulf Coast are hurricanes and . For More Information • The principal causes of floods in the Western United States are snowmelt and rainstorms. http://water.usgs.gov/osw/ • Flooding is the only natural for which the Federal government provides insurance: FEMA’s National Flood Insurance Program. http://www.usgs.gov/