Researchers: Use mud instead of sand to build land

Land building can be maximized by gearing diversions toward sections of vegetated delta plain instead of near open coast, researchers have found.

In their new publication "Efficient retention of mud drives land building on the Mississippi Delta plain," researchers from The Water Institute of the Gulf, Tulane University and Coastal Carolina University analyzed a centuries-old crevasse along Bayou Lafourche.

They found that mud – which is prevalent in the Mississippi River – may work better than sand in building land. Mud can build enough land to keep up with sea level rise if the outflow area is protected from waves and tides, researchers said.

"That's a big deal when you're planning a river diversion," said Christopher Esposito, a research scientist at The Water Institute of the Gulf who studied at Tulane University. "You really need to get an idea of how much sediment can be retained in the environment you're targeting. Our estimate is somewhere between 75-100 percent."

"This is dramatically higher than rates observed in growing coastal delta lobes, which retain only 5 to 30 percent of incoming sediment," said Zhixiong Shen, assistant professor of Marine Science at Coastal Carolina University.

According to the publication, the crevasse splay, located near Napoleonville, is made of mud deposits that have remained stable enough over centuries to support farming more than five miles from the Bayou Lafourche channel. Such crevasses are common in the Mississippi River delta, researchers said.

The crevasse formed between 800 and 1400 when Bayou Lafourche shared water and sediment flow with the Mississippi. Researchers found that the crevasse splay contained about 5 percent sand but had a high retention of mud.

"Site selection is very important," Esposito said. "That's the main thrust of it."

-- Staff Writer Bridget Mire can be reached at 448-7639 or bridget.mire@dailycomet.com. Follow her on Twitter @bridget_mire.