Study: Louisiana. slowly slipping into gulf

[one...two...tree 2,762]

By CAIN BURDEAU, Associated Press Writer

A new report by scientists studying Louisiana's sinking coast says the land here is not just sinking, it's sliding ever so slowly into the Gulf of Mexico.

The new findings may add a kink to plans being drawn up to build bigger and better levees to protect this historic city and Cajun bayou culture.

If the land is shifting — even slightly — engineers may need to take that into consideration as they build new levees and draw lines across the coast to identify areas that should and shouldn't be protected.

Researchers have known for years that the swampy land under south Louisiana is sinking (potholed streets and wobbly porches and floors are visible evidence of that) but a lateral movement of the land into the Gulf enters largely unstudied terrain.

The report, which appeared in December's Geophysical Research Letters, a peer-reviewed journal published by the American Geophysical Union, says the bedrock under heavily populated southeast Louisiana is breaking away at a glacial speed — at the pace fingernails grow.

The southward movement, the study says, is triggered by deep underground faults slipping under the enormous weight of sediment dumped by the Mississippi River.

The slippage, though, is confined to a large egg-shaped area approximately 250 miles long and 180 miles wide that encompasses the delta of the Mississippi, which was built up by river deposits over the past 8,000 years, the report says.

The report was based on data collected between 1995 and 2006 by Global Positioning System stations installed in recent years to better understand the dynamic nature of this delta the French settled in 300 years ago.

"People should not be afraid that we're going to fall into the Gulf. That's not going to happen," said Roy Dokka, lead researcher and executive director of the Center for GeoInformatics at Louisiana State University.

He described the slide into the Gulf as "a kind of avalanche of material, except that it is happening very slowly. It moved about the width of two credit cards this year."

While that may seem trifling in the big picture, Dokka said engineers need to include this reality into their plans for levees, floodgates and other projects.

Windell Curole, a levee and hurricane expert who is on a state board developing a master protection plan, said the phenomenon of sinking, or subsidence, has not been "included in a big way" in the new plan but that planners are "aware of it."

"As we understand it better, we will include it," he said. "You have to be aware of the elevation issues and the rate — these things need to be in the equation."

Flood protection planners have their work cut out for them as they choose between often competing theories about what is causing Louisiana to lose land at alarming rates. Since the 1930s, more than 2,000 square miles of coast sank or eroded.

Some scientists believe oil and natural gas extraction in the middle and late 20th century caused much of the sinking; others say the land is caving in because the Mississippi River and other waterways were straightjacketed by levees, which stopped floodwaters from replenishing the soil.

And some scientists have suggested the debate over subsidence is overstated.

Torbjorn Tornqvist, an associate professor of earth and environmental sciences at Tulane University, found much of the region surprisingly stable and the rate of sinking to be at least 10 times less than previously reported.

[almaty 19]

hmm...global warming ??

[almaty 19]

hmm...global warming ??

[Jenn! 918]

Wow, Louisiana is just the Venice of the U.S., isn't it? Carnevale and sinking!

[w¡n9Nµ7 §£@¥€r 123]

Sink sink sink sink sink

[mrc 0]

hmm...global warming ??

Yes, global warming caused by George W. Bush is creating this.

[Hornet 2]

Could the USA be that lucky? lol

[peejay 327]

Wow, Louisiana is just the Venice of the U.S., isn't it? Carnevale and sinking!

It may seem like a joke...but there is a small town at the mouth of the Mississippi River in Louisiana named Venice. It is at the end of the world south of New Orleans. Only one road in and out of the place and the road ends in Venice, LA.

It is a major hub for oilfield workers to go to and from work on the Gulf of Mexico via boat or helicopter. I've flown and boated in and out of there many times through the years. Once you go over the levy in Venice you are at the mercy of Gulf tides and the Mississippi River. Many a returning oilfield worker has lived to regret parking their vehicle in the lots on the other side of the levy. I always parked my car on the protected side of the levy and caught a ride to the docks.

Flying over the area you notice one obvious observation...sinking or sliding...anyone that would stay in the area when a hurricane is approaching has a death wish. The Louisiana marsh is right at sea level and it doesn't take much to put it underwater. It is pretty from the air and full of alligators.

An interesting place to visit, but I wouldn't want to live there.

[bucknekkid 0]

*Stand on the beach in Arkansas and waves bye-bye* B)