Tempting Fate: Why We Insist on Living in Floodplains

By Emily Gertz, Grist.org. Posted April 5, 2008.

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Once it was a cornfield; now it's a Wal-Mart, a Taco Bell, a Target. Here along a stretch of Missouri's Highway 40, in the Chesterfield Valley area just west of downtown St. Louis, what's said to be the largest strip mall in the country sits on about 46 acres of Mississippi River bottomlands. Less than 20 years ago, the land was open space.

It's been fifteen years since the Great Flood of 1993 put this land under 10 feet of water. Since then, thousands of acres of floodplain in the St. Louis area have been built up with strip malls, office and industrial parks, and 28,000 new homes. And all this infrastructure depends on miles and miles of levees to hold back the Mississippi and Missouri rivers the next time they try to retake the land.

If you ignore the historical tendency of the Mississippi and Missouri to periodically drown it, this vast, flat landscape does present an appealing canvas for building. "When you have such an expansive floodplain, people don't have a problem with building on the fringes," says Dan Burkemper, director of the Great Rivers Habitat Alliance. "And then the fringe moves closer to the river every day."

Lessons Learned ... and Forgotten?

The Flood of 1993 was one of the most destructive in the recorded history of the Mississippi Basin: nearly 50 people were killed, over 70,000 evacuated, and 50,000 homes damaged on over 17 million acres (close to 27,000 square miles) across nine states. Over 16,000 square miles of working cropland was flooded, at a loss of more than $5 billion. All told, the flood caused around $16 billion in damage.

In the first blush of post-flood shock, some local and federal officials decided that trying to hold back the Mississippi River was likely to be a costly and never-ending enterprise. Instead of depending on levees and other structures for protection, some thought, it was time to move people's homes and workplaces off the floodplain and cede ground to the river. "We must and can work to design and build our communities better and, to the extent possible, out of harm's way," then-director of the Federal Emergency Management Agency James Lee Witt told Congress later that year. "Mitigation must become a priority throughout all levels of our government. We must be proactive on mitigation and not reactive."

And FEMA acted on this notion: In the nine states flooded in 1993, the agency ultimately moved more than 300 homes, and bought and razed nearly 12,000, at a cost of over $150 million; the lands were turned to flood-friendlier uses like parks and wildlife habitat. The village of Valmeyer, Ill., just downriver of St. Louis, became the buyout poster child: devastated when floodwaters overtopped its levee (an event that likely helped save St. Louis itself from a major flood), the entire town packed it in, selling out its bottomland location for a new site two miles away -- and 400 feet above the Mississippi floodplain. It may have been the greatest exodus of Americans from floodplain homes and businesses in the nation's history.

But official resolve to depopulate the floodplain has given way to development fever in Missouri: over $2.2 billion worth so far on land that was underwater in 1993. And unlike some of the other states deluged in the Flood of 1993, such as Wisconsin, Iowa, and Illinois, Missouri has been much slower to enact stronger regulations for floodplain development -- perhaps because the state has hundreds of miles of floodplain fronting the Mississippi and Missouri rivers (read: lots of tax income lost and jobs unrealized if new businesses and homes don't get built).

In the St. Louis metro area, there's been more built upon the floodplain since 1993 than in its entire prior history, says Tim Kusky, a professor of natural sciences at St. Louis University. This development brings new pressures that haven't been assessed for how they might intensify flooding elsewhere, or cumulatively damage floodplain ecosystems.

"Since 1993, projects now complete, underway, and in planning have put or will put [28.1 square miles] of the Mississippi and Missouri floodplains near St. Louis behind new levees, enlarged levees, or floodplain land raised above the 100-year to 500-year protection level," wrote Southern Illinois University at Carbondale geologist Nicholas Pinter in the journal Science in 2005. Those projects included over $190 million spent by the Army Corps of Engineers to work on nine levees in its St. Louis District.

The corps argues that flood-control structures prevented $19 billion of damage in 1993 across the nine states affected. But is the confidence that these protections inspire part of the problem? "Most infrastructure on the floodplain would not be there were it not for the historic reliance on levees," Pinter noted in Science.

"[The Army Corps] thinks that the levees are going to protect the people behind them, and the businesses behind them," says Kusky, "because there are calculations based on the assumed risk of floods on the hundred-year floodplain and the five-hundred-year floodplain." But, Kusky says, "there's a problem with that calculation." The problem -- shocker! -- is global warming.

See more stories tagged with: water, floods, floodplain, climate change, global warming, army corps

Emily Gertz is a New York City-based freelance journalist and editor who has written on business, design, health, and other facets of the environment for Grist, Dwell, Plenty, Worldchanging, and other publications.

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