Flood Inundation Hazard
Mitigation Application
Online
The ability to look days into the future to see how many city blocks
and roads might be flooded is becoming clearer with Flood Inundation Mapping.
The National Oceanic and Atmospheric Administration's (NOAA) National
Weather Service (NWS) and its National Ocean Service (NOS) Coastal Services
Center (CSC) are collaborating with the Federal Emergency Management Agency
(FEMA), and other partners, to develop inundation maps for inland freshwater
flooding. Sets of maps (referred to as libraries) are being developed
which include map layers depicting the spatial extent and depth of water
for various flood levels ranging from minor flooding all the way through
the flood of record in the vicinity of NWS river forecast locations. These
new flood hazard graphics will help emergency managers and impacted citizens
be better prepared to make important decisions regarding evacuations,
moving property, and other mitigation efforts.
“Flood forecast maps take us into the next generation of flood forecasting
to saves lives and property,” stated Glenn Austin, Chief of the
NWS' Hydrologic Services Division. “ These new flood inundation
graphics open the door to a new world of visual information coupling
technology and science to produce 21st century services.”
Combined with traditional NWS river forecasts and flood bulletin information,
these new flood maps show the areas of likely inundation based on current
conditions and future rainfall. Maps are produced using geographic information
systems (GIS) and datasets created in the production of FEMA's Flood Insurance
Rate Maps. These libraries are accessible via the Advanced Hydrologic
Prediction Service (AHPS) web portal, the NWS' engine that hosts its vital
river and flood forecast information. In addition to displaying inundation
maps using the NWS' web interface, decision makers can download these
inundation maps and related data for use in their GIS applications (see
http://www.weather.gov/ahps/inundation.php)
“This mapping initiative moves beyond the text descriptions to maps
of the areas inundated at various flood stages,” Paul Rooney,
Department of Homeland Security/FEMA Risk Analysis Branch . “This
provides a much better understanding for both the local government and
others of the risk in the area mapped because it shows impacts for a
number of scenarios other than the 100-year flood. It is useful both
for mitigation planning and for response purposes.”
In response to Hurricane Floyd's devastating impacts in 1999, NOAA created
a partnership with the U.S. Geological Survey and state officials to develop
16 map libraries for the Tar River Basin in eastern North Carolina . Hurricanes
Katrina and Rita (2005) exposed the vulnerability of other coastal states
to inland flooding caused by tropical storms. Thus, the concept was expanded
to the Gulf region. The NWS is in the process of creating a
total of 35 flood inundation map libraries for locations in Texas , Louisiana
, Mississippi , and Alabama . The majority of these new map libraries
will be available before the mid-point of the 2008 hurricane season.
“The NWS has conducted extensive outreach with our diverse user community
to validate the need for flood inundation map libraries,” stated
Dr. Thomas Graziano, Chief of the NWS' Hydrologic Services Branch. “For
only a small incremental investment beyond the cost of a typical FEMA
Flood Insurance Study, state and local communities can produce inundation
libraries which provide the capacity to make more informed strategic
and tactical decisions to better plan for and mitigate the impacts of
floods.”
NOAA is vigorously building coalitions with additional emergency and
floodplain managers to implement this new, cost effective hazard visualization
and communication technique for other vulnerable flood-prone areas. Leveraging
the investments being made by the Lower Colorado River Authority and the
Susquehanna River Basin Commission, NOAA plans to fast-track the implementation
of flood libraries for NWS river forecast locations in these areas.
The National Flood Insurance Program's (NFIP) Community Rating System
(CRS) is a voluntary incentive program that recognizes and encourages
community floodplain management activities that exceed the minimum NFIP
requirements. As a result, flood insurance premium rates are discounted
to reflect the reduced flood risk resulting from the community actions
meeting the three goals of the CRS:
- Reduce flood losses
- Facilitate
accurate insurance rating
- Promote the awareness of flood
insurance.
“Communities which make the investment and partner with the NWS to
implement flood inundation map libraries can receive discounts in their
flood insurance rates through the National Flood Insurance Program,” stated
Berry Williams, of Barry Williams and Associates Inc, who has worked
over the years with FEMA to create and update FEMA's CRS Schedule of
credited activities identified to help reduce insurance costs.
It is important to know when a flood will occur, how bad it will be,
and how long it will last. AHPS ability to provide a map showing people
the areas for potential flooding will more clearly identify places where
people and property owners need to take action. Anyone who may someday
be impacted by flooding will benefit from these new inundation maps. Community
leaders interested in the creation of inundation libraries are encouraged
to coordinate with their local NWS office or communicate their interest
via the feedback page accessible through http://www.weather.gov/ahps/.
Last updated:
March 12, 2008
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