Word: sediments
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...been plagued from the start by unintended consequences. To prevent catastrophic floods like the 1927 disaster that left 700,000 people homeless from Illinois to Louisiana, the Corps leveed and streamlined the Mississippi. That effort turned the meandering, porous waterway into the world's largest high-pressure hose, shooting sediment and nutrients off the continental shelf in the Gulf of Mexico. Starved of silt and undermined by oil-drilling operations, the delta has been sinking at the same time global warming has caused water levels to rise. The result: every half an hour, a chunk of land about the size...
...western Louisiana coastline, similarly deprived of Mississippi river sediment, has been losing, in some places, as much as 35 ft. of beach a year, according to biologist David Richard, a specialist in the area's wetlands. By the time Rita hit, he says, the Gulf of Mexico was more than a quarter of a mile closer to the inland cities than it was when Hurricane Audrey struck...
...scheduled to begin in 2008, would occur in stages, and if it goes as planned, the Pacific Northwest will lose only a tiny amount of hydropower and regain a legendary salmon fishery. But there could be problems. Behind the Elwha dams are some 18 million cubic yards of accumulated sediment, enough to fill four superdomes, and if a lot of that sediment starts to move downstream at once, the ecological consequences could be severe...
...then there's the Glen Canyon Dam on the Colorado, which after its completion in 1963 not only robbed the Grand Canyon of sediment needed to rebuild sandbars and beaches but also drowned a spectacular landscape far bigger than the Hetch Hetchy Valley. Thanks to a multiyear drought that has only recently eased, the landscape has begun to re-emerge, energizing an effort by the Glen Canyon Institute to correct what conservationist David Brower called "America's most regretted environmental mistake." It's bound to be an uphill battle. The Glen Canyon Dam is part of the seven-state Colorado...
...elongated into an ellipse as the coral (which seeks warm waters) migrated toward the shallows north of the original crater. Some 1.8 million years ago, the atoll contained an inland sea continually replenished by ocean waters. But as the rising coral walls gradually closed out the ocean, newly deposited sediments' piled up in the forming lagoon. The inland sea shrank, the basin filled with fresh water and, in the warm southern sun, soon became clogged with the rich grasses that formed the Everglades. Central Florida's Lake Okeechobee, says Petuch, is the last remnant of that great, sediment-filled lake...