Islands flanking Mississippi ‘might vanish’ due to oil spill, sea level rise

Saturday, October 30, 2010

WASHINGTON - Researchers have warned that the islands flanking the Mississippi river might entirely disappear in the coming decades not only due to sea level rise and local subsidence but also because of unknown impacts from oil recovery operations.

The Chandeleur Islands to the east of the river outlet are remote, tenuous strips of sand that have served as surf breaks for the steadily sinking Biloxi Marsh.

“Hurricanes have done a number on them,” said Mary Ellison of the University of New Orleans.

The sediments show that what the marsh a part of the delta with the Mississippi river, but the river abandoned the east channel and drained further west. Waves from the Gulf took over and started chipping away at the delta, eventually winnowing out the finer grained silts and leaving the larger-grained sand - creating Chandeleur Islands.

But now, the trend is being accelerated by the lack of any sand from the Mississippi River so the islands are now cannibalizing themselves in order to maintain their shorelines.

The result is that the islands are on course to become little more than shoals in 50 years or so, Ellison explained.

On the other side, to the west, is Grand Isle which is the focus of a study that helps document what conditions BP needs to restore oil-damaged beaches to return to some kind of normal state - at a time when the island itself is undergoing massive and rapid changes due to hurricanes and repeated beach nourishment efforts.

“The BP cleaning process is to scrape the top layer of sand off the beach and clean it,” said Tyler Brown of Tulane University.

With the oil spill coming on top of the most recent beach nourishment project completed in March 2010, that has resulted in some interesting changes and maybe even a net gain of sand for the beaches in some areas, he said. (ANI)

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