The Floods: A Man-Made Disaster?

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Jeff Roberson / AP

Floodwater from the Mississippi River flows past the St. Louis skyline.

On March 4, three Midwestern University professors wrote to warn the Army Corps of Engineers that its concrete navigation structures in the Mississippi River were intensifying floods, and that its plans to build more wingdikes and weirs would "exacerbate a severe and growing problem." They called some of the structures — designed to scour out the river's bottom so that barges could pass — "loaded cannons pointing at St. Louis and East St. Louis, waiting to go off in the next flood." Citing "clear and unequivocal data" from a dozen peer-reviewed articles, they declared that "the time to ask these questions is now, and not in the aftermath of the next great flood."

The Army Corps, the troubled, gung-ho public works agency that bears much of the blame for leaving New Orleans underwater, blew off the academics' concerns. "I refuse to argue one side or the other, and instead prefer to take the road which best ensures and protects public safety, no matter the course of action," Colonel Lewis F. Setliff, commander of the agency's St. Louis District, replied on March 31. "I am completely confident that the Corps of Engineers has done this with regard to the river structures to which you refer."

The Army Corps is always completely confident, even when it's completely wrong. Its levees protecting St. Louis and East St. Louis survived this year's great flood, thanks in part to dozens of levee breaks upstream that reduced the pressure downstream, but there is powerful evidence that the Corps' mania for concrete significantly magnified the flood's power. Army Corps structures aren't the only reason 500-year floods seem to be hitting the Mississippi every 15 years, but a National Science Foundation-funded database of 8 million hydrologic measurements suggests they are the most important reason. Professors Nicholas Pinter of Southern Illinois University, Robert Criss of Washington University and Timothy Kusky of Saint Louis University have calculated that Corps structures are stacking up water during floods — as much as two meters around Winfield, Mo., and nearly six meters around Grand Tower, Ill.

"River engineering is the 800-pound gorilla driving these flood levels higher," says Pinter, who oversees the database and wrote the March 4 letter. "We're not talking inches higher; we're talking meters higher."

The notion that human beings in general and Army Corps engineers in particular are making floods much worse is not new; I've been banging my spoon on that high chair for years. Floods are natural events, but they are unnatural disasters; in the words of the legendary engineer Charles Ellet, the water is supplied by nature, but the height is increased by man.

In the past, those of us who described floods as man-made tended to focus on the construction of levees that forced rivers into narrow channels, the destruction of wetlands that once absorbed excess rainfall, and the overdevelopment of vulnerable floodplains. But now professors Pinter, Criss and Kusky have illuminated an even more serious factor amplifying floods: the wingdikes and weirs that the Corps has been building — usually underwater — to "train" the waters of the Mississippi into the center of the channel. The main goal is to save money on costly maintenance dredging by encouraging the river to dredge itself. The St. Louis District built nearly five miles worth of "bendway weirs" and nearly three miles of wing dikes in the three years before the great flood of 1993; they're still building similar projects. Pinter's data shows a startling correlation between new structures and the height of the water, even when the amount of water is held constant.

Corps engineers in St. Louis did not return calls. But they've told Pinter they don't believe they're increasing floods, based on "engineering intuition" and some work they've done in a sandbox model of the Mississippi. "It's amazing; they just assume everything's fine," Pinter says. "Hey, they've got a sandbox and a garden hose."

The dozens of recent levee collapses along the river have prompted calls for stronger protection, but if those levees had held, the water would have risen even higher downstream. Water has to go somewhere.

And now there's more of it. Global warming seems to be creating a modest increase in violent downpours, but the real problem is the transformation of Midwestern wetlands into farmland and asphalt, which has eliminated the region's natural sponges and forced billions of additional gallons of rain into already swollen waterways. Farmers have sucked their fields dry with millions of miles of tile drains, which helps explain why the Iowa and Cedar rivers rose so quickly last week. And the Army Corps is the federal agency responsible for protecting wetlands, a job it has executed with a predictable lack of ardor, since it spends much of its time destroying wetlands with its own water projects — like this discredited flood-control boondoggle it is pursuing along the Mississippi.

Of course, we wouldn't care so much about floods — even enlarged floods — if there weren't homes, businesses and crops in harm's way. Americans like to live and work and farm around rivers, and flood insurance and crop insurance programs make it easier for us to do that. So do levees, Corps-built or not; the town of Gulfport, Ill., was officially removed from the "100-year floodplain" after its levee was approved in 1999; the levee failed last week, so the town is now underwater.

Unfortunately, the motto of the Corps is not "first, do no harm," but "essayons," which is French for "let us try." The Government Accountability Office, the National Academies of Sciences and the Pentagon inspector general have all documented the agency's bias toward construction projects that keep its employees busy. It's going to take more than the flood of 2008 to stop the Corps from pouring concrete into the river.