June 29, 2009 -- Even under best-case outcomes for projects to restore Louisiana's dying coastline, the Mississippi River can't feed enough sediment into marshes to prevent catastrophic land loss, Louisiana State University geologists conclude in a scientific paper published today. They conclude that, as a result, Louisiana will lose as much as 5,212 square miles of coastline by 2100. The reason: The Mississippi and F rivers carry only half the sediment they did a century ago, down to 205 million tons today. The rest is captured by more than 40,000 dams and reservoirs that have been built on rivers and streams that flow into main channels. Yet even if those dams were torn down and the river's full sediment load employed in restoration efforts, it would not be enough to halt coastal erosion, according to Michael Blum, a former LSU geologist now working for Exxon Mobil Upstream Research Co. in Houston, and LSU geology professor Harry Roberts. They advocate a targeted approach, rather than broad restoration efforts. Related Content:
Even the river's highest potential sediment load, which created south Louisiana's once-lush and fertile delta over centuries of seasonal flooding, can no longer compete with forces pushing the Gulf of Mexico inland, the researchers conclude. Increased rates of sea-level rise, combined with the state's rapid rate of soil subsidence, will inundate wetlands over the next century, according to the study. The paper predicts water levels will rise between 2.6 feet and 3.9 feet along the coast by 2100. If the researchers are correct, the restoration effort in wetlands and barrier islands is a lost cause. "Louisiana is facing some really tough decisions here," Roberts said. "You can't do this restoration all over the coast because the whole coast is not sustainable and it never has been." Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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