Yesterday, in the second installment of his three-part series, "Storm Warning," John McQuaid visited the Netherlands, whose state-of-the-art system for protecting its coast could offer the United States lessons for buffering our own vulnerable coastal communities—that is, if the government is willing to make this a national priority. So far the president has committed to building a "flood protection system stronger than it has ever been," which, frankly, isn't saying very much. Today, in the conclusion of the series, McQuaid reports on what it will take to strengthen the nation's coastal defenses: among other things, efforts to preserve and rebuild the vanishing marshlands that act as a natural barrier to storm surges; a shake-up at the feckless U.S. Army Corps of Engineers, an agency that has carried out wasteful pork-barrel projects while ignoring those intended to keep Americans safe; and, yes, a national commitment to protecting coastal communities. The need to take bold action should have been evident after Katrina destroyed one of America's most storied cities. Sadly, it may take another Katrina before the government gets the message.
The term "terraforming"—reshaping the surface of another planet for human settlement—was coined by science-fiction writers. And that's not too far from what engineers must do for the Mississippi delta. They must resculpt a patchwork of degraded marshland, ruined city neighborhoods, and sprawling subdivisions into an integrated defense against flooding.
Part of the idea is to revive the process that built the Mississippi delta in the first place. When New Orleans was founded, rising, silt-laden water overflowed the riverbanks each spring, refreshing and expanding the marshes. The river levees constricted this flow in the 19th century, and the entire delta started slowly sinking back into the sea. Now scientists want to try strategically breaching the levees, diverting river water over the marshes to deposit silt once again. Those projects would be knit together with upgraded levees, walls, and floodgates at a cost of $50 to $55 billion spread over several decades, according to Louisiana officials.
On an array of high-resolution monitors in Joannes Westerink's Notre Dame University lab in South Bend, Indiana, a virtual storm is taking shape and crashing into a digital New Orleans. Anyone watching the news coverage of Katrina was treated to images like these—computer programs capable of digitally recreating landscapes and weather patterns, rerunning historical storms, even rearranging the configuration of levees and wetlands to test different designs and possible outcomes. It was these simulations that back in the 1980s and 1990s revealed shocking weaknesses in the levee system—yet Corps "muddy boots" traditionalists scorned modeling and never bothered to use it to reassess their decades-old designs.
A native of the Netherlands, with a mathematician's clinical detachment, Westerink has worked for years to bring the virtual world into ever-more precise alignment with the real world of wind, water, and barriers made of mud. Katrina provided both a wealth of new data and, in the end, funding from a reawakened Corps. Now that the Corps is finally interested, the models are revealing huge and dangerous defects in the entire delta layout.
Westerink, who has rerun his virtual Katrina hundreds of times, fires up his monitor once more for me. Speaking in a soft monotone, he explains that the river levees, which bisect the delta marshes for a hundred miles southeast of New Orleans, are the highest objects around. As Katrina approached from the south that August 29, it began pushing water against the river levees. Water built up against the walls and then moved northward with the storm, swallowing small towns. Some of that buildup flowed into metro New Orleans. Then, as Katrina passed east of the city, it propelled the rest of the huge wave straight into the Mississippi coast, where it reached a height of 30 feet, the highest storm surge ever to hit the U.S. coast. If the river levee hadn't been there—or had been designed differently—the devastation would have been far less.
"Can you control that flow?" Westerink asks. "This becomes a huge federal problem of who gets whose water." The hurricane risk to the Mississippi and Alabama coasts would be much lower if the river levees disappeared tomorrow. But nobody, least of all the Corps, wants to tell that to the shipping companies. Westerink and some Corps scientists say one solution is to cut big gaps in the levees, so storm surge waves would flow through and dissipate. That might preserve navigation, but it also would upend life in the delta as it's existed for more than a century. Louisiana towns such as Venice, at the extreme southeast end of the river, would literally become islands, tethered to each other by bridges. Places left outside the hurricane protections, such as Isle de Jean Charles, a tiny community of Indians from the Biloxi-Choctaw-Chitimacha tribe southwest of New Orleans, would probably disappear.
Clearly, such big fixes will make government agencies and political jurisdictions think about things they never imagined before. But thinking big is necessary; the alternative is to face more Katrina-sized storm surges—which will be increasingly likely given warming seas and melting polar ice—with weak flood defenses.
The most ambitious piece of any coastal protection plan will be rebuilding Louisiana's raggedy, sinking marshes. Anyone who grew up on the bayou knows that marshes help reduce storm surges. But official flood control policy has always focused on levees, so very few scientists—and no one in the Corps—had ever looked at just how that happens. That changed in 2002, when Tropical Storm Isidore nearly flooded Corps geologist John Lopez's house on Lake Pontchartrain. Isidore was a weak storm, yet its surge was large; Lopez wondered if the area's vanishing marshes had had anything to do with it.
Louisiana's vast wetlands have been sinking and eroding for decades. Since the 1930s, approximately 1,900 square miles of land has vanished—a swath roughly the size of the state of Delaware. In a single year, Hurricanes Katrina and Rita washed away an additional 217 square miles, according to a recent study by the U.S. Geological Service. Since then, scientists have grown even more alarmed at the rate at which erosion has been outpacing the modest efforts at coastal restoration. Rebuilding wetlands isn't easy, and it's that much harder if they're disappearing. In many places it will be possible only to slow the pace of erosion, not reverse it. Unless major progress is made in the next decade, the Times-Picayune reported in March, some coastal scientists say the delta may enter a kind of death spiral.