A Cocodrie scientist said his research shows Louisiana is sinking more slowly than in previous years, a phenomenon that could translate into cost and time savings for coastal-restoration projects.
Alex Kolker, a scientist at the Louisiana Universities Marine Consortium in Cocodrie, studied tidal data collected in Grand Isle, Galveston, Texas, and Pensacola, Fla., over the past 70 years to identify trends in subsidence, or the gradual sinking of coastal land.
Kolker's paper, published in the scientific journal “Geophysical Research Letters,” says subsidence is closely linked to oil production.
As extraction of oil and gas from the ground under our feet slows, so too does the rate at which the land sinks, the paper says.
A lowered rate could mean less Mississippi River sediment is needed to rebuild lands, a tremendous savings in terms of both time and cost.
In the current market, it can cost as much as $20,000 to dredge and relocate enough sediment to create an acre of land, Terrebonne Levee Director Reggie Dupre said. A typical restoration project must build hundreds or thousands of acres of new land to make a difference.
Scientists have long said subsidence in Louisiana is, in part, linked to the extraction of oil and gas.
The compaction of the Mississippi River delta over time and the lack of new, nourishing river sediment also is a factor.
Kolker said his findings “suggests that coastal restoration may be somewhat easier than people think.”
But Syed Khalil, a geologist and assistant administrator with the state Coastal Protection and Restoration Authority, said the amount of sediment needed to rebuild Louisiana's coast is so great that there's probably not enough sediment available to meet the need, even at the reduced rate predicted by Kolker.
The Louisiana coast has lost about 1,883 square miles of wetlands since 1932. It would take 4 billion cubic yards of sediment, or four times the debris left behind at the World Trade Center after the Sept. 11, 2001, terrorist attack, to rebuild all that land to a height of 1 foot.
It's impossible to get that much material to rebuild the coast, Khalil said. That's why the state, in the drafting of its 2012 coastal master plan, is trying to select the projects and places that will have the biggest effect on curbing coastal erosion.
“The coast is dynamic, and you can't get it back,” Khalil said. “That's why at the Coastal Protection and Restoration Office we're trying to front-end that by doing things that will reverse the trend of land loss.”
