Report calls for upgrading federal flood zone maps

Better data could protect lives, property

By Frederic J. Frommer
Associated Press / January 24, 2009
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WASHINGTON - Upgrading outdated maps used to calculate flood danger would save lives, prevent damage to property and businesses, and preserve infrastructure, researchers said nearly four years after Hurricane Katrina devastated the Gulf Coast.

Flood insurance rate maps issued by the Federal Emergency Management Agency are used to set flood insurance rates, regulate development in flood plains, and let people know about the risk they face.

FEMA is wrapping up a five-year effort to develop digital flood maps for 92 percent of the continental US population, the National Research Council said in a report made public yesterday. But even after $1 billion has been spent, only 21 percent of the population has maps that meet all FEMA data quality standards, according to the study.

The report was requested by FEMA and the National Oceanic and Atmospheric Administration. It said FEMA often bases maps on US Geological Survey elevation data, but that more accurate maps are available using lidar, which measures elevation with lasers on aircraft.

Among its recommendations, the report calls on FEMA to increase its collaboration with federal, state, and local agencies to acquire high-resolution, high-accuracy topographic data.

"FEMA has recently begun to support collection of lidar data along the Gulf Coast, but lidar data coverage over most inland areas is still sparse," the report says.

A FEMA spokesman, Butch Kinerney, said the report "validates a lot of the things we're doing, and have done, and gives us good recommendations for going forward. We're changing the way we're looking at maps."

In addition to upgrading the maps, the agency is also helping communities to write plans to prepare for all sorts of disasters, including floods, he said.

Asked if he agreed that better maps could save lives and property, Kinerney said a lot depends on whether local communities use the improved information.

"If a community chooses not to adopt it, it could be for naught," he said.

The report said that despite ongoing changes in the flood plain, "FEMA flood maps are not updated on a regular schedule. Requests for changes are made irregularly and physical map revisions are infrequent due to funding constraints."

The report also suggested that FEMA replace its one-dimensional model for calculating wave heights with a two-dimensional model. The council did credit the agency with encouraging "rapid advancements in coastal flood modeling and mapping" after Hurricane Katrina in August 2005.

The National Research Council is part of the National Academies, an independent organization chartered by Congress to advise the government on scientific matters.

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