Floods engulf archaic levee system
The Midwest's patchwork of levees wasn't adequately monitored or maintained.
The floodwaters, in many cases, have simply been too high.Skip to next paragraph
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The sprawling network of levees – built over many years to protect the Upper Mississippi basin from the sort of disastrous flooding that has claimed homes, lives, and millions of acres of farmland this past week – was never designed to withstand the magnitude of a 500-year flood.
And so towns like Gulfport, Ill., and Alexandria, Mo., have watched as waters spilled over the tops of levees that were supposed to keep them dry. [Editor's note: The original version misstated one of the towns referenced.]
The flooding has raised questions about the adequacy of the patchwork system – in which little information is known about where levees exist, who maintains them, and what their condition is – even as towns downstream hurry to fortify their own levees in preparation for the cresting floodwaters still moving south.
"Nature has its way of upping the ante," says Eric Halpin, special assistant for dam safety and levee safety with the US Army Corps of Engineers. "This storm proved that even if we had built levees to the floods of record, they would have been overwhelmed by this event."
So far, at least 20 levees along the Mississippi have overtopped this week, and another 20 to 30 are at risk.
It is too soon, say officials, to determine which ones may have failed before the water spilled over the top and which ones breached due to weakening after the water had overflowed.
Each day brings news of more levees overtopped or breached. Some are smaller agricultural levees built to 30- or 40-year flood standards, while others are higher, designed to protect river towns.
Already, the flood seems likely to equal or exceed the 1993 floods that wreaked havoc in these states, taking 48 lives and causing more than $20 billion in damage. On Thursday, President Bush was expected to tour flooded Iowa counties.
The news of so many levees overtopping or breaching can come as a shock to residents who felt safe behind their walls.
But experts say it's hardly surprising, especially given the low standards to which most levees are built.
To qualify for the National Flood Insurance Program, structures simply need to be behind a levee built to a so-called 100-year standard, meaning there is a 1 percent chance in any given year that a flood will rise above the levee. In the Netherlands, on the other hand, levees for ocean flooding are built to a 10,000-year standard, and inland levees are designed at least to a 250-year standard and usually in excess of 1,250 years.
"Around the world, the 100-year standard is a joke," says John Barry, author of "Rising Tide," his book about the Mississippi River flood of 1927, and a member of a flood control authority that oversees six levee districts in metropolitan New Orleans. "We invest on the cheap."