Engineers Plan for Next-Generation Hurricanes

By Larry O'Hanlon

One of the greatest gambles in American history started in the year 1965. That's when the Army Corps of Engineers was given 50 years to complete almost 20-foot-high Category 3 hurricane-rated levees along miles of shipping canals and the south shore of Lake Pontchartrain. Since then, for 40 hurricane seasons, New Orleans has put it all on the line, rolled the dice and prayed that the Big One wouldn't hit.

Of course, it was no secret back in '65 that the city really needed Category 5 protection, or that 50 years was an awfully long time to shoot craps with an entire city.

"The levees could have been higher, for Category 5," said engineer Joseph Suhayda, a New Orleans hydraulics expert at Louisiana State University in Baton Rouge. But the plans were driven by budgets, he said, and the U.S. Army Corps of Engineers (USACE) just wasn't given the resources.

That was then, and this is the post-Katrina now. "What we have to do now is commit to a Category 5 and put aside the benefits and costs analyses," said Suhayda.

And so just weeks after the catastrophic end of New Orleans' 39-year winning streak, government and university academic engineers have put together an array of mega-projects that ask for nothing less than the full protection that was needed all along — ASAP.

NEXT: Moving the Battle

The first order of business, as usual, is the levees. There are already some massive levees in New Orleans, most noticeably along the Mississippi River. These were funded and built in response to the first disastrous flooding of the city in 1927. Now, say the engineers, it's time to bulk up the others.

Among the options being floated by USACE is to simply raise existing levees to withstand a storm surge in Lake Pontchartrain caused by a Category 5 hurricane, says Alfred Naomi, a USACE project supervisor.

A second option is to raise the levees only on the edges of the city and build gates on the canals to keep the surge at bay, giving extra protection to the city zones along the canals while creating a safe haven for ships.

Naomi, for his part, prefers yet another plan, one that would involve building tens of miles of brand-new Category 5 levee east of the city and up the eastern side of Lake Pontchartrain.

This new levee would keep a storm surge from getting into the lake from the Gulf of Mexico. Without Gulf waters, the existing Category 3 levees along the north side of the city would be adequate for keeping out the lake, he says.

"You move the fight from the backyards of people's homes," explained Naomi. "And it gives you another line of defense." With an unlimited budget, he figures this plan could be accomplished in about ten years.

Regardless of the levee project that's eventually chosen, bigger, stronger levees won't be cheap and some will require reinforced foundations, depending on the geological conditions underfoot, says Naomi.

NEXT: The Good Ship New Orleans

But what if the worst happens and even the new mega-levee system fails? And how can the city be protected during the ten years it would take to build the new levees?

"We're not out of the woods," said Suhayda. "There is not a single fix to this."

Instead, a series of projects need to be initiated inside the city to protect it immediately from a repeat of the Katrina's chaos.

Suhayda and his colleagues propose a three-tiered approach that gives the city and its residents three levels of protection against a "Level 6" hurricane, as he likes to call it.

The first tier goes along with raising the levees: an upgraded pumping system that can move a lot more than the current half-inch-per-hour from inside the city. The next tier of protection is to compartmentalize the city so that a few levee breaches can't flood the entire thing.

"You don't let a hole in one part of the hull sink the whole ship," said Suhayda. "You close the water-proof doors and go on."

The last layer of protection: build watertight walls around vital buildings and move power generators and other vital technology onto the levees or other high ground. These are perhaps the cheapest and most immediate steps that can be taken, said Suhayda.

NEXT: The Southern Surge

Almost forgotten in the troubles of New Orleans east of the Mississippi River is the other part of the city — across the river. That part of town is also protected from the river by a levee, but it's rapidly losing its natural barrier from storm surges from the Gulf of Mexico to the south: the coastal marshlands.

Ironically, it's the river levee itself, built in the 1930s, that has caused the problem, says Robert Twilley, a professor of wetlands biogeochemistry at LSU.

Before the levee, the river periodically flooded over the southern marshlands, depositing silt that built up the land there, keeping it ahead of the ongoing subsidence of the river delta into the Gulf of Mexico.

For more than 70 years now there have been no floods and no silt, and the marshlands are steadily sinking, he says.

To halt that trend, Twilley says, engineers, biologists and geologists are working together — instead of knocking heads, which has been the case for decades.

"Post-Katrina, it's really all going to be one," said Twilley of the efforts to protect New Orleans and the entire Louisiana coast.

Of course, none of these projects will change the geological fact that New Orleans is still sinking. Some estimates have put Louisiana's loss of land at 35 square miles every year.

But they will buy something that's been in short supply along Louisiana's Gulf Coast: the hope that someday another Katrina won't be able to wreak so much havoc.