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Nov 10, 2005

New Flood Maps Of Miss. Coast Due Soon

The Federal Emergency Management Agency (FEMA) is schedule to publish new flood maps of the Mississippi coast on November 18, the Biloxi Sun Herald reported today. The new maps, which will be posted online, will depict flood elevations from 3 to 8 feet higher than the current maps. However, the new, higher, flood elevations are still lower than Hurricane Katrina's storm surge. "Quite frankly, in terms of hurricane storm surge, nothing compares to Hurricane Katrina. Not even close," Todd Davison, FEMA's mitigation director told the Sun Herald. Katrina's highest recorded surge was 35 feet, in west Pass Christian. FEMA officials say that it might be impossible to raise their flood elevation guidelines to protect structures based on Katrina's storm surge. The new flood elevations will be based on the "100-year" flood levels, as all flood maps have been. That means that another hurricane of the size and severity of Katrina would likely cause extensive flooding.

A frequent source of confusion, the, "100-year" flood elevation is based on a 1% chance in any given year that floodwaters will reach or exceed that elevation. That does not mean that the area will suffer a flood of that severity only once in a 100 years. FEMA used data from Katrina's flooding in preparing the new maps. However, the more recent data was combined with historical storm data.

FEMA is using sophisticated satellite technology to generate the new maps. In addition to showing the 100-year flood elevations, the new maps also will also show Katrina's storm surge. FEMA last published flood maps of the Mississippi coast in 1982 and was in the process of updating them when Katrina struck.

FEMA plans to have final versions of the maps in 18 months, when they will submit them to local governments for public review. Local governments must then adopt the new maps or be dropped from the National Flood Insurance Program. Until then, FEMA is urging coastal governments to require that residents rebuild using the new flood elevations.