Keeping the Waters at Bay
There's no shortage of ideas on how to protect the Crescent City. But ideas are the easy part
NEW ORLEANS--Standing on a bridge he helped build, U.S. Army Corps of Engineers project manager Jack Fredine surveys the mouth of New Orleans's 17th Street Canal. A year ago, this was a spot nobody paid a lick of attention to. Now, thanks to Hurricane Katrina and the catastrophic failure of the canal's levee, it's infamous. Just downstream, to the north, lies the broad expanse of Lake Pontchartrain, from which a 12-foot wall of water surged into the canal on the morning of August 29. To the south, the drainage canal's pumping station is just barely visible. In between, along the canal's eastern bank, lies what little remains of the Lakeview neighborhood--block after block of shattered homes and shattered dreams. "The water hit the end of the canal, and it didn't have anywhere to go but out there," says Fredine, pointing to the rupture point, just a hundred yards or so upstream from the bridge. The breach has been dammed off with large metal sheet pilings and shored up with rock and gravel. A pump shoots seepage back into the canal in a high muddy arc.
What's most striking, however, is just how little has changed. With the clock ticking down toward this year's hurricane season--it starts on June 1--residents of New Orleans can be forgiven for wondering if their city's battered defenses will be ready should another killer storm hit. "I think it's going very well given where we started," says Walter Baumy, deputy director of Task Force Guardian, the Army Corps's $770 million program to repair levees, floodwalls, and other damaged pieces of the region's flood-protection system. Almost all the contracts--56 of 59, to be exact--have been awarded, Baumy notes, and the pace of the work is picking up. "We expect it to be pretty much 24 hours a day,"Baumy says, acknowledging that June is an awfully tight deadline.
Step by step. Baumy's assignment is to repair the damage caused by last year's storm--to get the system back to where it was when Katrina rumbled through. Making New Orleans safer than before, well, that's another story. The decisions there will ultimately be made by Congress and carried out by the corps--which will issue a report on the subject by June. In the meantime, however, at least four other groups are proposing solutions. They range from teams of nationally known scientists and engineers to a local committee set up by New Orleans Mayor Ray Nagin. The plans differ in detail, but there are broad areas of agreement, on issues like the need to harden levees and floodwalls, protect canals from in-rushing storm surges, and get serious about reversing a century or more of destruction of Louisiana's coastal wetlands--the marshes, swamps, and bayous that used to act as natural barriers against storm surges.
The first priority, says Larry Roth, deputy executive director of the American Society of Civil Engineers, is to make sure the region's earthen levees are "armored,"or paved over with concrete, asphalt, or rock along the outside. The levees are just mounds of compacted earth, some with concrete floodwalls along their crest; when floodwater from the canals flows over the top of the system, unarmored levees can be washed away. The catastrophic flooding in the Lower Ninth Ward, for example, was caused by breaches in the inner harbor navigation canal levee, which failed because waves pouring over the top of its floodwall sent water rushing down the outside to undercut the soil at its base. Armoring is simple enough in concept, and it's certainly a low-tech solution. But with 129 miles of levees in the Orleans Levee District alone, Roth says, armoring the entire region will "not be easy or inexpensive."
Experts also recommend sealing off the 17th Street Canal, as well as other canals that give in-rushing water access to the heart of vulnerable neighborhoods. The drainage canals, built a century ago to move rainwater from the city to Lake Pontchartrain, used to start at the outskirts of New Orleans. But the city has grown all the way to the lakeshore, so any levee failures along the canals are dangerous. The engineers' group supports a plan to move the pumping stations to the mouth of the 17th Street, Orleans Avenue, and London Avenue canals. Shifting the pump installations, says Roth, would enable them to keep pumping during a storm and allow them to act as surge-protection dams to keep floodwater out of the canals. "The pump-station structure itself would resist surges from the lake into the canal," he says, "and that would eliminate several miles of rather fragile floodwall and levees from exposure to storm surge."
But that project would cost some $450 million and take five or more years to complete, says John Koerner, chairman of a subcommittee of Mayor Nagin's Bring New Orleans Back Commission. Koerner's group is pushing for a more immediate solution, involving "living dams"--specially constructed barges, outfitted with powerful pumps, which would be maneuvered into place and submerged at the canal mouths when storms threatened. The project would cost under $75 million and could be completed in months, Koerner says, but it's "probably ... too much to hope for." Koerner is one of many who believe that the corps will resist such novel approaches.
Koerner's group also proposes damming the mouth of the Inner Harbor Navigation Canal, to protect the Lower Ninth Ward. And it has concerns as well about an underutilized navigation channel called MR-GO, which many observers would like to see, well, go. The Mississippi River-Gulf Outlet was dredged through 76 miles of wetlands in the 1960s and is blamed for intensifying erosion there and acting as a conduit for Katrina's swell. But Koerner's subcommittee stops short of insisting that the channel be completely filled in. The channel is still used by shrimpers, offshore oil service boats, and recreational boaters, Koerner says. His subcommittee proposes constructing a type of dam that would allow boats and water to pass and have a floodgate that could close in times of danger. "We tried to serve as many constituencies as possible," says Koerner of his group's report. "If our ideas get shot down, then so be it. But let's at least get talking about something other than the same old stuff."
Nature's way. Two more groups, the Lake Pontchartrain Basin Foundation and a consortium of scientists led by oceanographer Don Boesch of the University of Maryland, have focused in particular on the region's natural defenses. For decades, the swamps, marshes, and barrier islands of the Louisiana coastline have been devastated by development. Robert Twilley, a wetlands ecologist at Louisiana State University, says that it's tough to work out exactly what protective impact an aggressive restoration effort would have, "but it's not just putting an apron of wetland there. It has to be extensive." Wetlands restoration, measured in decades and many billions of dollars, would be slow, expensive, and uncertain--and, almost everyone seems to agree, absolutely essential.
If there is full consensus on any one point, however, it is that no single solution will be enough to protect New Orleans from future storms. Instead, says John Lopez of the Lake Pontchartrain Basin Foundation, the focus should be on "multiple lines of defense"--starting with rebuilding the barrier islands and wetlands, and including enhancements to other flood barriers, like natural ridges and the raised beds of railway tracks and roads. The city itself should be compartmentalized into many smaller basins, the foundation says, so that any future flooding can be contained. The group is also pushing for flood-resistant buildings, like elevated homes. Even Roth, the engineer, agrees that New Orleans won't be able to simply engineer itself out of trouble. "You can't just rely on structural means of protection," he says. "You have to include flood-resistant design and city planning, and you have to look at rejuvenation and rehabilitation of natural barriers." Congress has thus far approved $1.5 billion for improved hurricane protection for the region, both for this year's repairs and for long-term upgrades, and last week the Bush administration asked for $1.4 billion more. But that may not be nearly enough. A 2001 study estimated that a linked hurricane protection and coastal restoration program could cost $14 billion and take up to three decades to complete.
Back at the 17th Street Canal, the repair work continues. In addition to fixing the mess from last year, the corps's plans this season call for a few upgrades, including stronger floodwalls topping the levees along the Inner Harbor Navigation Canal and some limited armoring of particularly vulnerable stretches of the system. The crude sheet-pile dams at the mouths of the city's outfall canals--17th Street and its sisters--are being replaced by temporary gated structures, which can be left open for regular drainage and slammed shut at the approach of a big storm.
Come hurricane season, says the Army Corps's Baumy, "I'm confident [the system] will be able to withstand the hurricane it was designed for." That means a Category 3 storm--exactly what the previous system was designed to withstand and exactly the strength at which Katrina hit New Orleans. Others believe New Orleans deserves a system that could withstand a Category 5 blow. Come June 1, New Orleans residents will have plenty to think about.
PROTECTING THE CRESCENT CITY
With the 2006 hurricane season less than four months away, the clock is ticking on efforts to repair flood barriers and begin the process of upgrading the Crescent City's protection. Basic repairs and modest upgrades to the levees, floodwalls, and canals are scheduled to be completed by June 1 of this year under a U.S. Army Corps of Engineers project, Task Force Guardian. Another corps effort, Task Force Hope, will focus on longer-term upgrades, though the ultimate goal of an integrated levee and floodwall system to shield the area from a category 5 storm most likely is years away.
Built near the outlets of the 17th Street, Orleans Avenue, and London Avenue outfall canals, these pumps and gates will prevent another Katrina-type of storm surge from swelling into the canals toward the city and washing over the levees and floodwalls.
Orleans Ave. Canal; London Ave. Canal; Outfall canals; Lake Pontchartrain ; Causeway
WHERE ALL THE WATER CAME FROM
As Hurricane Katrina hammered the Louisiana coast, it caused flooding in two major ways:
1 Water blown from Lake Borgne converged with the Intercoastal Waterway and the Mississippi River-Gulf Outlet, creating an amplified storm surge pushing west to the Industrial Canal and into surrounding neighborhoods.
2 Later, as Katrina passed east of the city, winds forced water to the southern shore of Lake Pontchartrain, shooting a surge of water into the three outfall, or drainage, canals.
Undamaged levees; Damaged levees; Mississippi River; Intercoastal Waterway Superdome; Garden District; French Quarter Storm surge; Storm surge; Storm surge; Lake Pontchartrain; Storm surge; Storm surge; Storm surge; Storm surge; Storm surge; Lake Borgne; Mississippi River-Gulf Outlet(MR-GO)
LENGTHY SURGE STOPPER
One long-term proposal: a system of levees, floodgates, and locks along Route 90 to help protect the 1.4 million residents around Lake Pontchartrain.
KATRINA FLOOD LEVELS
0-2 feet2-4 feet4-6 feet6-8 feet8-10 feet17th Street Canal10+ feet
Downtown New Orleans; Lakeview; Lower Ninth Ward; Industrial Canal; (also called Inner Harbor Navigation Canal)
Water pumped out of canal; PumpsGate closes to stop storm surge; Interim outfall canal pump and gate;
Task Force Guardian; Floodwall repair/replacement; Levee repair; Minor amount of levee armoring (only where Katrina overtopping was severe)
Interim gated structures for outfall canals; Scheduled completion: June 1, 2006
Damaged levee/floodwall; Task Force Hope Upgrading New Orleans's protection
More-ambitious levee armoring to prevent erosion due to overtopping
Floodwall redesign; Permanent gated structuresfor outfall canals
Starting the process of coastal wetlands restoration; Channel control
Close the Mississippi River-Gulf Outlet, or keep it open for shipping? One long-term solution might be a floating flood control gate, which could keep a shipping lane open yet could close to block a storm's surge.
The wetlands factor
Hurricanes Katrina and Rita transformed about 100 square miles of Louisiana's marsh to open water, according to initial U.S. Geological Survey estimates. There's widespread agreement that restoring the wetlands will provide an essential natural buffer to future storm surges and that this endeavor-however expensive-must be part of any long-term solution. Lost wetlands: 1,900 square miles (1937-2000) Levee and floodwall repair/upgrades
IMMEDIATE AND LONG-TERM PLANSTASK FORCE GUARDIAN
Levees repaired to pre-Katrina height of 15 feet. Levees with the worst overtopping damage could be reinforced with riprap or concrete, called "armoring."
TASK FORCE HOPE
Proposals include: More-extensive armoring of the leveesArmoring with: riprap or concrete Floodwall Levee River or canal
LAKE BORGNE'S PROPOSED LEAKY LEVEE
To blunt storm surges from Lake Borgne, a "leaky levee" skirting the western shore of the lake might be built. Its openings allowing the free flow of water and marine life would be closed during a storm.
Floating gate; Construction in progress; Undamaged levee/floodwall; Leaky levee; Proposed flood control gate; Proposed flood control gate; Proposed flood control gate; Proposed flood control gate; Erosion
Sources: U.S. Army Corps of Engineers; Bring New Orleans Back Commission; USGS; Louisiana Department of Natural Resources
GRAPHIC BY STEPHEN ROUNTREE AND ROB CADY-USN&WR
This story appears in the February 27, 2006 print edition of U.S. News & World Report.