Louisiana State professor: Wetlands management is key to flood control
When it comes to flood control, engineered dominance over natural forces can be a solution that will come back to haunt you, a scientist from Louisiana State University told a group of North Dakota university scientists and engineers gathered Wed...
When it comes to flood control, engineered dominance over natural forces can be a solution that will come back to haunt you, a scientist from Louisiana State University told a group of North Dakota university scientists and engineers gathered Wednesday in Grand Forks.
The 1928 project tamed the Mississippi River Delta and turned the river into a major economic asset for the nation, but it also reduced the flow of sediment that maintains the wetlands buffering cities and towns from flooding, said Robert Twilley, an ecologist and LSU's associate vice chancellor of research.
The flooding in New Orleans and other Louisiana communities after Hurricane Katrina were consequences of that as is the oil damage along the coast after the fire at a BP oil platform this year, damage that might have been blocked by barrier islands had more existed.
"You can't think of the Ninth Ward of New Orleans unless you've actually thought all the way out to the entire delta," Twilley said. The billions of dollars in trade at Louisiana's ports are of national importance, he said, but so is protecting those ports.
Now a member of a team developing plans to restore Louisiana's coastal areas, he's advocating restoration of some river channels to allow more sediment to flow to the coast.
To his audience, he said universities need to teach future scientists and engineers to think in multiple dimensions, including the environment, not just look at one solution as the civil engineers involved in the 1928 project did. Otherwise, he said, "We're leading ourselves to amplify the next crisis."
The occasion was a conference of the state EPSCoR group, a long acronym for a National Science Foundation program aimed at spreading federal research dollars to states that are traditionally not major recipients. This year's event saw a record 380 registered attendees.
Twilley's keynote speech touched on some themes familiar to longtime residents of the Red River Valley, such as flooding and the response to it.
Less well known are past debates among environmentalists and farmers regarding the role wetlands could play in mitigating flooding. Past studies, done in the aftermath of the Flood of 1997, have found that wetland restoration, at least in parts of the valley, would do little to reduce water levels in another major flood.
The 1928 Mississippi project was launched in the aftermath of the Great Mississippi Flood in the previous year, one of the most destructive in the nation's history -- killing 200, displacing 600,000 and causing $1.5 billion in property damage. Taking the lead in the project was the U.S. Army Corps of Engineers, which designed a 2,200-mile dike system and a series of floodways capable of diverting 3 million cubic feet of water per second.
Where there were many drain ways, formed as the river gradually shifted its course over thousands of years, the corps reduced it to two. While this controlled flooding, it also reduced the flow of sediments to two areas.
Southern Louisiana is gradually sinking while ocean levels are rising, so the wetlands are sinking at an inch a year, Twilley said. Without sediments to build up the land, he said, a football-field's worth of wetlands is disappearing every 15 minutes.
He showed a map of the Louisiana coastline today and a projection of what it'd be like in 2100 if nothing is done. The coastline has receded by hundreds of miles. A strip along the Mississippi River remains with New Orleans hanging on tenuously.
"This is not people moving toward the coast," he said, "this is the coast moving toward people."
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