Monday, September 05, 2005

Mississippi River Watershed

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Map courtesy of National Geographic

The Lost Coast

With the runoff from a third of the nation, the Mississippi River built coastal Louisiana, a swath of marsh, islands, and swamp that covered more than 6,000 square miles (15,500 square kilometers) in the early 20th century. Levees raised in the 1930s ended spring floods that pumped vital sediments and nutrients into wetlands. Then nutria, a South American rodent imported by fur farmers, escaped into the wild and began devouring marsh roots. By the 1960s the U.S. Army Corps of Engineers had dredged 14 major ship channels to inland ports, while oil companies cut countless canals for pipelines and wells, resulting in wetland loss in such areas as Barataria Basin. Add the toll from subsidence and sea-level rise, and Louisiana has lost 1,900 square miles (4,900 square kilometers) of wetlands since the 1930s. With another 700 square miles (1,800 square kilometers) likely to vanish by 2050, the state has proposed an ambitious 14-billion-dollar plan to save what's left. "We ripped the guts out of south Louisiana," says University of New Orleans geologist Shea Penland. "Now we want it back."   

Posted at 11:52 PM in Science | Permalink


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What I find fascinating is that by rights, the Mississippi
River should not even be anywhere near NOLA, or even Baton
Rouge. For decades the U.S. Army Corps of Engineers has
struggled to keep that mighty river from doing what rivers
do best -- going downhill to sea through the most efficient
route. That route is no longer through NOLA; somewhere
upstate in a place called Atchafalaya are massive dams that
attempt to prevent the natural processes that, if left
unchecked, would result in the southern terminus of the
Mississippi moving many tens of miles to the west. This is
all documented in an excellent book by one of my favorite
authors: John McPhee's "The Control of Nature." While
perhaps not directly germaine to the current tragedy, I
highly recommend it.

Posted by: Anon Y. Mouse | Sep 8, 2005 3:33:55 PM

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