Deteriorating levees following Hurricane Katrina necessitate a $1 billion investment for enhancement

The flood protection system in metro New Orleans, a colossal civil works project and home to the world's largest surge barrier of its kind, is facing a daunting future. Built after Hurricane Katrina, the system is now costing more than $1 billion to maintain at a sufficient height for the next five decades, according to the Army Corps of Engineers (USACE).

The system, known as the Hurricane and Storm Damage Risk Reduction System (HSDRRS), was designed with speed in reconstruction as a priority. As a result, it provides adequate protection only through 2057, and will stop providing adequate protection by 2073. To address this, $1.1 billion is needed to lift 50 miles of levees, replace a mile of flood wall, and add 2.2 miles of flood wall.

The HSDRRS system includes the Lake Borgne Surge Barrier, a major feature of the new protection system, which features 26-foot-high gates and 32-foot concrete flood walls. These are twice the height of their predecessors. However, the land in the New Orleans area is sinking as water, oil, and gas are extracted from below the ground and as the region's soft soil compresses under the weight of levees and concrete flood walls.

Congress directed the USACE to raise levee heights and strengthen the New Orleans-area levee system to achieve certification for participation in the flood insurance program. The New Orleans area has the highest concentration of flood insurance policies sold by the National Flood Insurance Program (NFIP), with six out of the top 10 counties being in the area. 74% of homes in the New Orleans area have NFIP coverage.

However, Mark Davis, an environmental law expert at Tulane University Law School, wrote that the mandate to quickly make the city again eligible for flood insurance lowered the protection level provided by the rebuilt system. Sandy Rosenthal, who created levees.org after Katrina, echoes this sentiment, stating that "it's always hard to get money" for maintaining the protection system.

The new system built new flood walls, pumps, and surge barriers farther away from the heart of New Orleans and left the pre-Katrina structures closer to the center city as secondary protection. This means that the city's primary flood protection is not as close to the city as it once was.

The Louisiana coast is notoriously difficult to protect from hurricanes. Sea levels along the Southeast and Gulf coasts have risen at unprecedented rates since 2010, according to a study by Tulane University scientists. This rise, coupled with the subsidence of the land, presents a significant challenge to the HSDRRS system.

The USACE is responsible for the maintenance and preservation of the flood protection systems around the New Orleans metropolitan area for the next five decades. The system's ability to provide flood insurance for property owners is crucial, as a small weakening of protection could make hundreds of thousands of property owners ineligible. The protection system is one of the largest civil works projects ever undertaken, and its future will be closely watched as climate change and subsidence continue to pose challenges.

Deteriorating levees following Hurricane Katrina necessitate a $1 billion investment for enhancement