Phoenix in the Swamp
Despite the obstacles, there's no shortage of rebuilding plans
One way or another, New Orleans will be rebuilt--at great cost and with full knowledge that another Katrina could strike at any time. The geographic, economic, and environmental obstacles are daunting, but the technology exists--and detailed plans have languished, unfunded, for years--to overcome past mistakes and make the entire region a much safer place. "We always said it would take a tragedy to get the attention of the nation," says Len Bahr, a longtime adviser to Louisiana's governors on coastal protection. "Hopefully, now the national dismay will add up to the national will to restore and protect as much as we can."
The first step, of course, is to reclaim the city from the floodwaters and re-establish the infrastructure on which all else will depend. In theory, New Orleans's drainage system has prodigious capacity--some 40,000 cubic feet of water per second, or about twice the flow over Niagara's American Falls. But Greg Breerwood, deputy district engineer for the U.S. Army Corps of Engineers in New Orleans, estimated last week that the pump network was working at just 10 percent of capacity. Some pumps were still under water or waiting for power, while others had to be shut down when their intakes clogged. The intakes are fitted with "trash racks," says Jim Peterson of pump manufacturer ITT Industries, but the motorized screens, which snare and remove debris, "aren't really designed to handle a car or a house."
Even before the city is drained--which could take as long as 80 days--the staggering task of restoring the city's infrastructure will begin in earnest. One of the biggest challenges will be providing a clean water supply. Unlike in earthquake or war zones, most of the sewage and water pipes will still be in place and functioning. But extensive flooding causes serious problems for drinking water systems, says Edward Bouwer, an environmental engineer at Johns Hopkins University in Baltimore. "The distribution system is usually under pressure, which keeps contaminants from leaking in," Bouwer explains. That pressure is gone now, and the pipes will have spent weeks or months soaking up contaminated muck before clean water starts flowing again. The entire system will have to be flushed out, Bouwer says, and carefully brought back on line section by section. "It's doable," he says, "but it has to be managed carefully."
Radical solutions. What is not doable, experts agree, is to make the rebuilt New Orleans 100 percent safe from hurricanes and floods. But civil engineers, hydrologists, and city planners say that there are many ways to make it a lot safer, including a range of solutions laid out in a 1998 coastal-protection plan called Coast 2050. At the time, the proposal's $14 billion price tag seemed prohibitive, but the economic havoc wrought by Katrina could change the cost-benefit calculus considerably. Whatever plans emerge will almost certainly include beefed-up levees and, quite possibly, a set of floodgates at the mouth of Lake Pontchartrain to keep storm surges from rushing in. Other, more radical suggestions may also get serious consideration. They include a controversial proposal to construct a "community haven" in central New Orleans. Developed by Joseph Suhayda, an engineering professor now retired from Louisiana State University, the idea is to surround key historical and business districts with a curtain of flood walls and floodgates robust enough to withstand even the worst storms. Much of the city would still be lost--protecting it all would be too expensive--but the cultural and commercial core of the city would be preserved, and the area could serve as a secure refuge for residents who wouldn't be able to evacuate in time.
Another plan would raise some areas of the city above sea level. John Marlin of the University of Illinois-Urbana-Champaign suggests starting by filling low-lying areas with crushed stone and brick debris from demolished buildings. An elevated city would continue to sink--the inevitable result of building on soft river sediments, exacerbated by pumping out groundwater, gas, and oil. Still, with subsidence rates in the city averaging about 2 inches per decade, proponents say, a major backfilling operation could protect significant areas of the city for generations.
Hardening the city's physical defenses will be a necessity, but experts say that no long-term solution can ignore natural flood control. The bayous, marshes, and barrier islands of southern Louisiana provide the best flood insurance available--every 4 miles of wetlands, for example, can reduce the height of Gulf storm surges by a foot. But coastal Louisiana has lost more than 1 million acres of wetlands over the past century. Shipping channels encourage erosion, and the levees and upriver dams that protect New Orleans from Mississippi River floods make the city more vulnerable to Gulf floods by robbing wetlands of the new sediment they need to rebuild. The solution, says Bahr, is to replumb the Mississippi River Delta to allow more water and sediment into the marshes. Engineers could help nature at both ends of the Mississippi, Marlin says, by barging excess river mud, currently choking marshes and rivers in Illinois, down to wetlands in Louisiana.
Planners and engineers will also be looking to other flood-prone countries for the latest flood control technologies. In the Netherlands, maintaining a comprehensive network of floodgates costs about $500 million per year--expensive, but effective enough to keep the 10 million Dutch citizens living below sea level safe for over 50 years. But such models are not always inspiring. In Bangladesh, where cyclone-driven floods killed more than 130,000 people in 1991, the government lacks funds for high-tech protection. Instead, it has constructed hundreds of elevated concrete shelters, which offer flood victims a safe haven.
New Orleans could become a model of smart planning and coastal protection. Or it could be rebuilt on the cheap, leaving its residents as exposed to the inevitable next hurricane as Bangladeshis clinging to a concrete tower in a monsoon. "Right now the window of opportunity to make the right decisions is open," says Bahr. "It won't be for long."
REDESIGNING NEW ORLEANS AND THE DELTA
After the floodwaters recede, New Orleans will be rebuilt. Engineers, urban planners, and geologists say Katrina's devastation provides a rare opportunity to make long-needed upgrades to the city's flood control system. Just as important, scientists say, keeping the Gulf region safe in future storms will require a radical replumbing of the Mississippi Delta.
[Map labels]
Mississippi River
New Orleans
Lake Pontchartrain; Industrial Canal floodgate; Chef Menteur Pass floodgate; Rigolets Pass floodgate; Floodgate
Lake Borgne
Lac des Allemands
Proposed artificial canals
Bayou Lafourche
Middle Barataria Basin wetlands
Breton Sound
Head of Passes
Gulf of Mexico
COMMUNITY HAVEN
This approach would surround central New Orleans with a ring of flood walls. But it's an uncomfortable compromise. Like a medieval city, the safe haven would protect the city core and serve as an emergency refuel. But outlying neighborhoods would still be vulnerable.
[inset map labels]
New Orleans
New Orleans International Airport
Lake Pontchartrain
Community Haven: Downtown, Superdome, French Quarter
Industrial Canal
Lakefront Airport
Mississippi River
FLOODGATES
Floodgates like this massive construction in the Netherlands could be employed to protect a rebuilt New Orleans from storm surges. At least four locations (shown in red on the map) could use gates of various sizes.
[inset map labels]
River
Gate
Pivot
Storm surge
SUPERLEVEES
These enhanced levees hold up well under the forces of flooding. Japanese engineers are using them in Osaka City, among other places. If used in New Orleans, superlevees could support new neighborhoods, raised above sea level.
[inset map labels]
Mississippi River
Superlevee
Old levee
New development
Pre-Katrina neighborhood
RESTORING WETLANDS
River diversions and gated levees would allow sediment from the Mississippi to flow into wetland areas, replenishing the vanishing storm surge buffer. Proposed diversions would carry various amounts of water.
7,481-37,403 gallons per second
37,403-112,208 gallons per second
112,208+ gallons per second
The Mississippi River's extensive levees are designed to keep water and sediment from damaging development in low-lying areas. The water diversion projects would reconnect the Mississippi River to the delta.
One diversion path tracks Bayou Lafourche, the Mississippi's course 1,000 years ago. The other would require an artificial canal.
Proposals have been made to restore degraded and fractured marshland in widespread areas using dredged sediments pumped through pipelines.
Some suggest closing the Mississippi River-Gulf Outlet. It would then no longer be dredged, and the ensuing silt buildup would gradually replenish the wetlands of the Breton Sound.
This area is a potential site for a large marsh building diversion project.
Enhancement of this barrier island chain using available sand
Building a structure here [Head of Passes], perhaps a pair of gates still to be designed, could allow unimpeded shipping traffic while preventing the annual loss of 200 million tons of sediment. Trapping that sediment could help replenish this delta and save the yearly $50 million now spent on dredging.
Sources: Louisiana Coastal Area; Len Bahr, Governor's Office of Coastal Activities; Joseph Suhayda and Nedra Korevec, LSU; Scientific American; Japan Institute of Construction Engineering; Ministry of Transport, Public Works and Water Management, Netherlands
Rob Cady and Stephen Rountree-- USN&WR
Satellite imagery--Landsat, NASA
With Alex Kingsbury
This story appears in the September 19, 2005 print edition of U.S. News & World Report.