Image: © Pattie Steib
At least 19 levees in Iowa, Illinois and Missouri have failed over the past week after heavy rains, according to the U.S. Army Corps of Engineers—and workers swarmed to shore up others with sandbags to prevent rising waters in the Mississippi and its tributaries from overflowing and washing away surrounding communities, farmland and soil. Engineers blame overdevelopment—and potentially poor maintenance of the levees—for the flooding.
"Whenever you have development, you are going to increase the runoff, increase how much the rivers and streams have to carry," says civil engineer W. Gene Corley, a senior vice president at CTLGroup, an engineering firm that evaluates infrastructure, such as levees. "The other side of that is that if you don't have development, you don't have housing for people or business or manufacturing."
In addition, by paving over previously open space—or farming previously reserved lands—communities in these watersheds contribute to record high waters through increased runoff.
This extra runoff is why waters in Cedar Rapids, Iowa, for example, rose to a record 30-plus feet (over nine meters). "The amount of development that has happened in communities up and down the river way creates less opportunity for water to be absorbed back into the earth as opposed to just running off," notes structural engineer Jeffrey Garrett, president and CEO of CTLGroup. "Suddenly, you've got a lot more water that has to flow between the levees."
Efforts to carve a controlled channel for the Missouri, Mississippi and their tributary rivers also contributed to the problem. The reason: the Mississippi now flows through a conduit roughly half the width of its channel that existed before most of the levees were built, which means more water passes faster through a narrower area. "Channeling the river means you are going to have higher crests in the river," Corley notes, that are sometimes higher than the levees built previously to contain them.
Ultimately, levee breaches in places like Gulfport, Ill., help preserve communities farther downriver—by siphoning off some of the raging waters. (When a levee breaks, some water remains and inundates the land behind the breached embankment. This lowered volume reduces the pressure downstream.)
The majority of levees in the Midwest have held so far during the torrential downpours, although those that failed, Corley says, may also have been poorly maintained. But, he adds, "it's too early to tell" the exact reasons the levees failed.
Failure to build strong enough levees—and fix known flaws in them—was blamed for catastrophic flooding in New Orleans, Mississippi and Alabama after Hurricane Katrina in 2005, which killed more than 1,800 people and caused more than $81 billion in damage.
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2 Comments
Add CommentNo kidding. This is a problem all over the USA. California has very serious problems because local and state politicians have bowed to the pressure of making a buck and put huge developments in flood plains. I used to live in Missouri, and the same thing happened there. Even right after a huge flood that washed away homes there was immediate pressure to rezone bottomlands from reserve and farming to be built on.
Reply | Report Abuse | Link to thisWhat this really means is that the US taxpayers are giving billions to shyster developers, screwing over normal working people, and leaving the federal government (meaning your and my tax dollars) to clean up the mess. This is way beyond wrong.
The people who profited from putting homes and commercial development in the wrong place should be prosecuted for lying to us just like Cioffi the former Bear Stearns exec.
You see, these people know exactly what they did, they don't care because it made them rich. I'd say on the order of 10,000 of them belong in jail.
It would be nice if we all could live in Camelot, I don't see any immediate solutions to all this. Prosecute these guys? The "Robber Barons" used to buy off politicians & judges with impunity, nothing much has changed in this regard. I think however, the general public should be more throughly informed of the risks of living in a house on a flood plain, a heavily wooded area, or a fault zone as some examples. Living just about anywhere these days has some inherent risks, but I agree with you someone who builds a house on a sand spit on the coast of South Carolina shouldn't expect full compensation from the public coffers when their house floats out to sea.
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