Mighty Mis­sis­sippi: Sci­en­tists use model in land loss fight

Sun.Star Pampanga - - SCIENCE! -

B ATON ROUGE, La. (AP) — Sci­en­tists work ing on new ways to bat­tle the ero­sion that threat­ens Louisiana’s coast­line have a dra­matic new tool: a mas­sive replica of the lower Mis­sis­sippi River.

The Louisiana State Uni­ver­sity’s Cen­ter for River Stud­ies is home to the newly opened Lower Mis­sis­sippi River Phys­i­cal Model, a 10,000-square-foot (930-square-me­ter) re­pro­duc­tion of nearly 200 miles (322 kilo­me­ters) of the lower Mis­sis­sippi from the town of Don­ald­sonville north­west of New Or­leans to the Gulf of Mex­ico. The model will help ex­perts study one of the most im­por­tant rivers in North Amer­ica and how sed­i­ment from it can be used to fight coastal ero­sion.

“Not only can we model the flows and the wa­ter stages of the wa­ter lev­els in the Mis­sis­sippi River, we can also model or sim­u­late the trans­port or the move­ment of the Mis­sis­sippi River sand down the river, and we can do all that in roughly one hour to repli­cate one year on the river,” said Clint Will­son, the LSU pro­fes­sor who heads the Cen­ter for River Stud­ies.

Louisiana is in a race to pro­tect and re­build its frag­ile coast­line from decades of ero­sion while also fac­ing ris­ing seas from cli­mate change. It’s es­ti­mated to have lost 2,000 square miles (5,180 square kilo­me­ters) of coast­line since the 1930s, ac­cord­ing to Rudy Si­moneaux of the state’s Coastal Pro­tec­tion and Restora­tion Au­thor­ity. That’s about the size of Delaware.

To fight back, Louisiana de­vel­oped a plan that re­lies in part on slic­ing chan­nels or di­ver­sions at var­i­ous lo­ca­tions into the lev­ees that keep the Mis­sis­sippi River in its course and let­ting some of the sed­i­ment in the river into the rapidly erod­ing wet­lands to re­build land. The idea, said Si­moneaux, is to “put the river back to work to re­build what it once built on its own.”

The Delta re­gion of south­east­ern Louisiana was built over cen­turies on sed­i­ment that washed down the river. But lev­ees built along the river to pre­vent flood­ing mean the sed­i­ment ba­si­cally washes into the Gulf. As part of its ef­forts to study the sed­i­ment di­ver­sions, the CPRA cre­ated the $18 mil­lion model and Cen­ter for River Stud­ies, re­plac­ing an older, smaller river model that was de­com­mis­sioned in 2009.

The new model, housed just a stone’s throw from the ac­tual Mis­sis­sippi River, is de­signed to help re­searchers an­swer such ques­tions as: How does open­ing one di­ver­sion af­fect the river’s flow? How do the di­ver­sions af­fect the dredg­ing done by the U.S. Army Corps of En­gi­neers? How do mul­ti­ple di­ver­sions along the river af­fect each other?

“What you do in one place has an im­pact on an­other, and so the idea of look­ing at larger-scale im­pacts or larger-scale pro­cesses is crit­i­cal to look­ing at what the po­ten­tial im­pacts are or the un­in­tended con­se­quences of projects, and so a model of this scale al­lows you to do that,” said Will­son.

The model was made of high den­sity foam pan­els strong enough for peo­ple to walk on. Data about the di­men­sions and shape of the Mis­sis­sippi River and sur­round­ing to­pog­ra­phy were put into a com­puter and then used to cut the pan­els. The pan­els, com­bined with the steel ca­bles and jacks un­derneath, weigh about as much as one of the 737 jets flown by South­west Air­lines, Si­moneaux said.

When vis­i­tors walk into the sec­ond floor to look down onto the model, they can feel the mois­ture com­ing from the roughly 6,000 gal­lons (33,710 liters) of wa­ter float­ing on the model that repli­cate the river, the Gulf of Mex­ico and the var­i­ous lakes and bay­ous along the coast. Tiny par­ti­cles of plas­tic in­jected into the wa­ter mimic the sed­i­ment cours­ing through the Mis­sis­sippi River. And they can raise the wa­ter level to repli­cate ris­ing seas.

Of­fi­cials are hope­ful that lessons learned at the cen­ter can be shared with other coun­tries and re­gions strug­gling with sim­i­lar prob­lems as Louisiana.

“An im­age like this model tells the story in a way that is way more pow­er­ful than a slide show, than a nu­mer­i­cal mod­el­ing,” said Justin R. Ehren­werth, who heads the Wa­ter In­sti­tute of the Gulf , a Baton Rouge­based re­search or­ga­ni­za­tion that stud­ies and helps coastal ar­eas af­fected by prob­lems like ris­ing seas and sub­si­dence.

Newspapers in English

Newspapers from Philippines

© PressReader. All rights reserved.