At a Glance

Concerns about the rebuilt levees, flood gates and other protection measures date back several years. The Corps is conducting a study to determine whether shoring the system up even more is feasible. Draft of the study should be done by December.

The vast network of levees, flood walls, gates and pumps that protects New Orleans was rebuilt after Hurricane Katrina, and just finished last year, at a cost of some $14 billion.

But now, the rapid onset of climate change and rising sea levels means that within five years, the system could be overcome in the face of a 100-year storm, according to the U.S. Army Corps of Engineers and other experts.

The Corps is embarking on a study to determine how - or if - to further shore up the system

“Absent future levee lifts to offset consolidation, settlement, subsidence, and sea level rise, risk to life and property in the Greater New Orleans area will ,” the Corps stated in a notice of intent to investigate all options.

The statement goes on to predict the system might no longer provide the protection needed to withstand a storm surge that has a 1% chance of occurring in any given year, commonly referred to as a "100-year storm."

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The notice was published April 2 in the Federal Register, and indicated that the Corps expects to have a draft report completed by December of this year.

The levees failed dramatically during Hurricane Katrina in September 2005, flooding much of the city. At least are estimated to have died in the storm, with drowning likely being the most common cause.

A 2015 by weather.com detailed the history of New Orleans flood control measures, from devastation after Hurricane Betsy in 1965 that spurred initial construction of the system, to their failure during Katrina and the subsequent reconstruction efforts.

The restoration and expansion was finished last year. The project took a decade and cost an estimated $14 billion, according to the Corps of Engineers notice. It is considered to be one of the most technically advanced ever built, according to the state flood protection agency that oversees it.

The system was rebuilt to withstand a 100-year-flood, but the Corps said it has since become clear that the network may not be able to keep up with climate change and rising sea levels.

“It’s happening a than our projections in 2007,” Corps of Engineers spokesman Matthew Roe told Climatewire, in an article reprinted by Scientific American.

Roe said the earthen levees that form the backbone of the 350-mile maze of protection are the most vulnerable. The levees are settling and losing height, in part due to the area’s soft soil.

Similar concerns about the project date back to , when an engineering firm hired to study the east bank portion of the levee system said it should be re-analyzed prior to an already-required 2023 assessment, NOLA.com recently reported.

The Corps agreed and, in 2015, announced would be done, according to the news outlet.

NOLA.com also reported that the National Academy of Sciences projected in 2016 that New Orleans could be one of the world cities hit hardest by climate change, along with Manila, Jakarta and Bangkok.

“The public may feel complacent. The [protective] system was built, and they think it’s done. They look at that levee as a static monolith,” John Lopez, director of the coastal and community program for the Lake Pontchartrain Basin Foundation, an environmental group, told NOLA.com. “But the crisis never really was over. We improved the system, but we have always been under threat.”