FEMA Developing Technology for Accurate Flood Mapping
Release Date: July 3, 2007
Release Number: FNF-07-038
Dear Editor:
The Press-Register's series of articles on flood insurance and flood maps highlights a problem that the Federal Emergency Management Agency faces: informing the public about flood risk and the limits of flood maps.
Right now in Alabama's neighboring states, you can read stories and editorials critical of map changes that show more property at higher risk for flooding. It is the old damned-if-we-do, damned-if-we-don't syndrome: Saying you are at risk draws criticism, and not showing risk also draws criticism.
While it is true that many of the flood maps in use in this country are more than 20 years old, FEMA is well into a billion-dollar, five-year Map Modernization program to provide the public with more accessible and updated maps.
The first phase of MAP-MOD, as the program is called, is almost complete. Digital flood map products covering 92 percent of the nation's population are on track for adoption by 2010.
In the second phase, currently under development, FEMA plans to leverage the new digital maps with even better data to present the best-available risk information to communities nationwide.
The Press-Register's articles mentioned this initiative in passing, but the chief point of modernizati.on is that all flood insurance rate maps will be updated and digitized.
It is ironic that when this results in more at-risk properties, we are often told that the land hasn't changed or "the science is wrong."
FEMA undertook this expensive project precisely because information and technology does change. The 90,000 paper flood maps across the nation need to be modernized to keep up with rapid changes in land-use, flood information and the technology to determine risk.
MAP-MOD puts FEMA and its partners in flood plain management at the federal, state and local levels on track to keep up with shifting needs, better technology and ever-changing flood risks.
When flood maps were first developed, especially maps in coastal areas like Mobile, the storm surge data were from a fairly short time period. Coincidentally, those maps were done during a relatively quiet period in America's hurricane history.
New storm surge modeling, better land-use data and other information collected since the first maps were introduced will improve the new flood insurance rate maps and represent the real risks.
FEMA flood maps are based on complex engineering, hydrological and climatological information, and reflect the best available information on flooding from rivers overtopping as well as from storm surge.
As technology advances, FEMA updates flood maps to reflect those advances and is currently working on new storm surge models. These models take into account the latest in scientific understanding on how storms work and the effects they create.
These new models will add greatly to our understanding on how areas subject to coastal surge are affected during a major event, and our maps will represent that new knowledge.
FEMA has always held that everyone needs to consider purchasing flood insurance as a way to protect their financial investments. As early as the 1980s, a FEMA/National Flood Insurance Program brochure was headlined "Everyone Lives in the Floodplain."
The perception may exist that only people in flood plains need flood insurance, or that people living outside of flood plains can't buy flood insurance. Both perceptions are wrong.
FEMA works aggressively to educate the public about floods. (People can go to www.floodsmart.gov for information on flood insurance and flood risk throughout the country.)
Every citizen needs to fully understand that standard homeowners policies do not cover damage from flooding, and every property owner needs to know his or her flood risk. Neither directly nor indirectly would FEMA tell a property owner that flood insurance is not needed.
In many cases, based on whether a home is in a Special Flood Hazard Area, flood insurance may not be required, but without exception every property owner needs to know the risk and consider flood insurance.
We know that the standard term "100-year flood plain" has long been confusing to lay people. FEMA did not invent this term, and has since replaced it with the more accurate "1-percent annual chance standard."
The new term does not predict how often an area will flood, but instead reflects the statistical chance in any given year.
If that sounds the same, consider this experiment: If you toss a quarter 10 times and it comes up heads every time, what are the odds it will come up heads on the 11th toss? The answer is 50/50, because coins have no memory.
Neither does Mother Nature.
The Press-Register's series also wrongly characterizes the term to mean a storm which will only occur every 100 years. The 1-percent event, as noted in the series, happens with much more frequency than once every 100 years.
By repeatedly calling it a 100-year map/storm/flood zone, the series reinforces the incorrect idea that such storms and floods only happen once every 100 years. This is inaccurate and long-outdated information.
And it's important to understand that, by design, the 1-percent annual chance event is an absolute minimum. That means that it represents a fairly routine flooding event -- not a catastrophic storm like Hurricane Katrina.
The 1-percent standard, and the flood insurance rate maps which are based on it, are not public safety maps. They are designed for the National Flood Insurance Program to rate properties and to provide information on areas most likely to flood so that local governments can curtail development in the riskiest areas.
They are not now, and never have been, intended to show every area susceptible to flooding. In other words, we do not expect or predict that floods will ever conform to these maps.
Accurate risk information is the cornerstone of being prepared. Residents of hurricane-prone states like Alabama need to prepare now for hurricanes, no matter what the map shows.
For those in areas vulnerable to hurricanes, the message is: Know your risk from wind and floods, from storm surge and storm runoff, and prepare now. That means having adequate flood insurance coverage, a disaster plan and an emergency kit.
This is a message everyone needs to hear.
By DAVID MAURSTAD
Assistant Administrator of Mitigation
Federal Emergency Management Agency- Washington DC
Last Modified: Tuesday, 03-Jul-2007 13:42:17