Better Levees Cannot Fully Eliminate Risk of New Orleans Flooding Again

Photo: New Orleans, La., Aug. 30, 2005 - Cars parked on the New Orleans streets are flooded to the top of the wheel wells. (Marty Bahamonde/FEMA)

The National Academy of Engineering and the National Research Council have come out with their final report which says voluntary relocation of people and neighborhoods from areas that are vulnerable to flooding should be considered "a viable public policy option."

The long and short of it is that that no matter how large or sturdy new levees and floodwalls surrounding New Orleans are constructed, they cannot provide absolute protection against overtopping or failure in extreme events.

According to a news statement released today, the report is the fifth and final one to provide recommendations to the Interagency Performance Evaluation Task Force (IPET), formed by the U.S. Army Corps of Engineers to examine why New Orleans' hurricane-protection system failed during Hurricane Katrina and how it can be strengthened.

The conclusions of the committee preparing the report was that levees and floodwalls should only be viewed as a way to reduce risks from hurricanes and storm surges, not as measures that could completely eliminate risk.

The report adds that, as with any structure built to protect against flooding, the New Orleans the hurricane-protection system - a 350-mile structure network - promoted a false sense of security that areas behind the structures were absolutely safe for habitation and development.

Comprehensive flood planning and risk management should be based on a combination of structural and nonstructural measures, including the option of voluntary relocations, floodproofing and elevation of structures, and evacuation, the committee urged. Rebuilding the New Orleans area and its hurricane-protection system to its pre-Katrina state would leave the city and its inhabitants vulnerable to similar disasters. Instead, settlement in areas most vulnerable to flooding should be discouraged, and some consideration should be given to new designs of the New Orleans metro hurricane-protection system.

For structures in hazardous areas and residents who do not relocate, the committee recommended major floodproofing measures -- such as elevating the first floor of buildings to at least the 100-year flood level and strengthening electric power, water, gas, and telecommunication infrastructure.

For more information, see http://national-academies.org/studycommitteprocess.pdf.