THE deaths caused by Hurricane Katrina are heart-rending. The suffering of survivors is wrenching. Property destruction is shocking. But perhaps the most agonizing part is that much of what happened in New Orleans this week might have been avoided.
Watching the TV images of the storm approaching the Mississippi Delta on Sunday, I was sick to my stomach. Not only because I knew the hell it could unleash (I wrote an article for Scientific American in 2001 that described the very situation that was unfolding) but because I knew that a large-scale engineering plan called Coast 2050 - developed in 1998 by scientists, Army engineers, metropolitan planners and Louisiana officials - might have helped save the city, but had gone unrealized.
The debate over New Orleans's vulnerability to hurricanes has raged for a century. By the late 1990's, scientists at Louisiana State University and the University of New Orleans had perfected computer models showing exactly how a sea surge would overwhelm the levee system, and had recommended a set of solutions. The Army Corps of Engineers, which built the levees, had proposed different projects.
Yet some scientists reflexively disregarded practical considerations pointed out by the Army engineers; more often, the engineers scoffed at scientific studies indicating that the basic facts of geology and hydrology meant that significant design changes were needed. Meanwhile, local politicians lobbied Congress for financing for myriad special interest groups, from oil companies to oyster farmers. Congress did not hear a unified voice, making it easier to turn a deaf ear.
Fed up with the splintered efforts, Len Bahr, then the head of the Louisiana Governor's Office of Coastal Activities, somehow dragged all the parties to one table in 1998 and got them to agree on a coordinated solution: Coast 2050. Completing every recommended project over a decade or more would have cost an estimated $14 billion, so Louisiana turned to the federal government. While this may seem an astronomical sum, it isn't in terms of large public works; in 2000 Congress began a $7 billion engineering program to refresh the dying Florida Everglades. But Congress had other priorities, Louisiana politicians had other priorities, and the magic moment of consensus was lost.
Thus, in true American fashion, we ignored an inevitable problem until disaster focused our attention. Fortunately, as we rebuild New Orleans, we can protect it - by engineering solutions that work with nature, not against it.
The conceit that we can control the natural world is what made New Orleans vulnerable. For more than a century the Army Corps, with Congress's blessing, leveed the Mississippi River to prevent its annual floods, so that farms and industries could expand along its banks. Those same floods, however, had dumped huge amounts of sediment and freshwater across the Mississippi Delta, rebuilding each year what gulf tides and storms had worn away and holding back infusions of saltwater that kill marsh vegetation. These vast delta wetlands created a lush, hardy buffer that could absorb sea surges and weaken high winds.
The flooding at the river's mouth also sent great volumes of sediment west and east into the Gulf of Mexico, to a string of barrier islands that cut down surges and waves, compensating for regular ocean erosion. Stopping the Mississippi's floods starved the wetlands and the islands; both are rapidly disintegrating, leaving the city naked against the sea.
What can we do to restore these natural protections? Although the parties that devised Coast 2050, and other independent scientists and engineers who have floated rival plans, may disagree on details, they do concur on several major initiatives that would shield New Orleans, reconstitute the delta and, as a side benefit, improve ports and shipping lanes for the oil and natural gas industries in the Gulf of Mexico.
Cut several channels in the levees on the Mississippi River's southern bank (the side that doesn't abut the city) and secure them with powerful floodgates that could be opened at certain times of the year to allow sediment and freshwater to flow down into the delta, re-establishing it.
Build a new navigation channel from the Gulf into the Mississippi, about 40 miles south of New Orleans, so ships don't have to enter the river at its three southernmost tips 30 miles further away. For decades the corps has dredged shipping channels along those final miles to keep them navigable, creating underwater chutes that propel river sediment out into the deep ocean. The dredging could then be stopped, the river mouth would fill in naturally, and sediment would again spill to the barrier islands, lengthening and widening them. Some planners also propose a modern port at the new access point that would replace those along the river that are too shallow to handle the huge new ships now being built worldwide.
Erect huge seagates across the pair of narrow straits that connect the eastern edge of Lake Pontchartrain, which lies north of the city, to the gulf. Now, any hurricane that blows in from the south will push a wall of water through these straits into the huge lake, which in turn will threaten to overflow into the city. That is what has filled the bowl that is New Orleans this week. But seagates at the straits can stop the wall of water from flowing in. The Netherlands has built similar gates to hold back the turbulent North Sea and they work splendidly.
Finally, and most obviously, raise, extend and strengthen the city's existing but aging levees, canal walls and pumping systems that worked so poorly in recent days.
It's hard to say how much of this work could have been completed by today had Coast 2050 become a reality. Certainly, the delta wetlands and barrier islands would not have rebounded substantially yet. But undoubtedly progress would have been made that would have spared someone's life, someone's home, some jazz club or gumbo joint, some city district, some part of the region's unique culture that the entire country revels in. And we would have been well on our way to a long-term solution. For there is one thing we know for sure: hurricanes will howl through the Mississippi Delta again.