United States Geological Survey Makes Better Flood Maps At Much Lower Cost
The new, streamlined method uses geographic information system (GIS)
computer programs that can include digital map information such as the
location of roads and buildings.
"Many of the aging flood maps were based on now-outdated flood flow
estimates, as well as on paper maps that lack sufficient detail," said
Joseph L. Jones, USGS hydrologist and lead developer of the new system.
"With our new digital method, we can cut map-updating costs by up to
80 percent over the traditional methods while producing maps with improved
accuracy and much greater detail. We can quickly update maps as new flood
probability estimates and high-accuracy elevation data become available."
Most of the detailed flood maps produced for the National Flood Insurance
Program in the 1970's and 1980's now need updating. Since the original
maps were drawn, more flood level data have accumulated, which can significantly
change calculations of flood estimates. The new USGS method is a quick,
affordable way to include the new data and calculations while also providing
greater detail and more flexible analysis capabilities.
The report detailing the new method, "Updating flood maps efficiently--Building
on existing hydraulic information and modern elevation data with a GIS,"
by Joseph L. Jones, Tana L. Haluska, Alex K. Williamson, and Martha L.
Erwin, is published as U.S. Geological Survey Open-File Report 98-200.
The report can be viewed on the World Wide Web at this URL:
A limited number of copies of the report are available from the USGS
Washington District, 1201 Pacific Avenue, Suite 600, Tacoma, Washington
98402, telephone (253) 428-3600. The report can be purchased from the
U.S. Geological Survey, Branch of Information Services, Box 25286, Denver,
Colorado 80225, telephone (303) 202-4610.
As the nation's largest water, earth, and biological science and civilian
mapping agency, the USGS works in cooperation with more than 2,000 organizations
across the country to provide reliable, impartial, scientific information
to resource managers, planners, and other customers. This information
is gathered in every state by USGS scientists to minimize the loss of
life and property from natural disasters, contribute to sound economic
and physical development of the nation's natural resources, and enhance
the quality of life by monitoring water, biological, energy, and mineral
resources. Contact Joseph L. Jones, Hydrologist, (253) 428-3600, ext 2684
(253) 428-3614 fax , e-mail: jljones@usgs.gov.
October
2, 1998 - A new mapping method developed by the United States Geological
Survey can produce updated flood inundation maps with greater detail at
a much lower cost than traditional hand-drawn flood maps.