Sea-level rise and sinking land mean the Mississippi River Delta's habitable land will shrink, a new study finds.
Katie Carter/The Vicksburg Evening Post/AP
Unless enormous amounts of soil are dumped onto the Mississippi River Delta, the region could lose up to 5,212 square miles of land to ocean and tidal marsh by 2100 – a result of sea-level rise and the land sinking.
Even if levees are intentionally breached to supply fresh sediment to the delta, the Mississippi River would fall billions of tons short of delivering enough silt to maintain a delta that looks anything like it does today.
That’s the picture two scientists with Louisiana State University have painted after trying to get a better handle on the restoration challenges facing the state’s delta region.
“This was an attempt to give real boundary conditions for restoration efforts,” says Harry Roberts, a scientist with Louisiana State University’s Coastal Studies Institute in Baton Rouge and one of the researchers conducting the study.
The boundary conditions appear unforgiving. For instance, all that remains of New Orleans would probably be the French Quarter and the airport. Lake Pontchartrain would lie beneath a vast bay. Along its southernmost reaches, the Mississippi River would remain a river only by virtue of the levees raised to contain it.
The researchers acknowledge that the study is a first cut at putting numbers to the problem. Others are likely to devise more precise estimates. “But even if we’re off by 50 percent, it’s still bad,” says Michael Blum, Dr. Roberts’s colleague on the work.
During the past 12,000 years, according to the study, up to 3.5 trillion tons of sediment have been deposited into a valley stretching from Memphis, Tenn., to the Gulf of Mexico. Some 80 percent of that muck makes up the delta plain.