More accurate FEMA flood maps could help avoid significant damages and losses

Science Daily: Significant loss of life, destroyed property and businesses, and repairs to infrastructure could be avoided by replacing Federal Emergency Management Agency flood maps with ones that contain high-accuracy and high-resolution land surface elevation data, says a new report from the National Research Council.

The benefits of more accurate flood maps will outweigh the costs, mainly because insurance premiums and building restrictions would better match the actual flood risks. Coastal region flood maps could also be improved by updating current models and using two-dimensional storm surge and wave models.

….The costs for improving flood maps would come from collecting, updating, modeling, and analyzing the flood-related data; increasing construction of property and businesses; losing land to development; updating regulations; and informing the public of changes. The committee found that these costs would be outweighed by benefits of more accurate flood maps, including reduced loss of life, property, and businesses; more efficient planning and response for emergency services; and preservation of natural functions of floodplains. In addition, better maps would provide more reliable measures of flood hazard, which would enable more targeted land-use regulations and structures to be insured at appropriate levels. Maps that include estimates of the height flood water will rise or exceed during a 100-year flood provide significantly more benefits than those that do not.

...FEMA's transition to digital flood mapping also provides opportunities for better informing the public of flood hazards and risks through maps and Web-based products, the committee noted. To adequately convey risk, the maps and products must show where the flood hazard areas are located and the likely consequences of flooding, such as damage to houses or coastal erosion. Additionally, floodplain residents should know how their land elevation level compares with various possible flood heights, which will offer a finer discrimination of potential risk. Currently, maps that show only floodplain boundaries imply that every building in a designated flood zone may flood and every building outside the zone is safe….

After Hurricane Katrina hit New Orleans, a flood surge smashed this house in the Upper 9th Ward. Photo by Infrogmation, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2