Building and Construction

Wetland Losses Are Outpacing Land Building in Mississippi Delta

13 April 2018

Mississippi River Delta. Source: WikipediaMississippi River Delta. Source: Wikipedia

A new study concludes that the rate of land-building from river diversions in the Mississippi River Delta likely will be dwarfed by the rate of wetland loss.

Scientists studied how fast the Mississippi River Delta grew each year before people inhabited the area and began changing the environment. They then compared that information with observations of how fast the delta is shrinking in modern times. The findings will inform coastal policy and management in this low-lying U.S. region.

The study results, published in the journal Science Advances, used optical dating to measure how fast the delta shoreline migrated seaward under natural conditions.

(Read "Hardening the Energy Coast.")

"Optical dating determines when sediment grains were deposited by measuring their last exposure to daylight," says Elizabeth Chamberlain of Vanderbilt University, the paper's lead author.

(Read "Gulf Coast Universities Team for Storm Resiliency Institute.")

Prior to human influence, the delta grew at a rate of 2 to 3 square miles per year. But over the past century, the rate of land loss in coastal Louisiana has averaged 15 to 20 square miles per year.

Geologist Torbjörn Törnqvist of Tulane University, a co-author of the study, says that given accelerating rates of sea level rise, losses will likely continue long into the future, and that even the best-designed river diversions won't be able to prevent more land loss.

(Read "Wetlands Renewal Project Advances with Stantec Selection.")

The only viable option, Törnqvist says, is to position river diversions in areas that have the greatest potential to build land and protect the largest population centers, as opposed to placing multiple diversions along the entire shoreline.

Chamberlain and Törnqvist conducted the research with colleagues from Coastal Carolina University, the University of Liverpool in the United Kingdom and Wageningen University in the Netherlands. Additional funding was provided by the Coastal Protection and Restoration Authority of Louisiana.

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Discussion – 1 comment

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Re: Wetland Losses Are Outpacing Land Building in Mississippi Delta
2018-Apr-13 12:40 PM

Maybe after all these years, there is just less sediment in the rivers to be deposited? Maybe everyone upstream should not be trying to control erosion? Trying to preserve the delta is like trying to preserve a sand dune. Or we should just allow the delta to be flooded every year? Pick your poison.

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