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Why wetlands matter | Why wetlands disappear

The landscape of New Orleans is part of the wetlands system of southern Louisiana, and the city’s future depends on the health of that regional system.

Why wetlands matter

During storms and hurricanes, the wetlands protect New Orleans from surges in the Gulf of Mexico by absorbing and slowing water. Estimates vary, but scientists at the Massachusetts Institute of Technology suggest that an area of one to four square miles of wetlands between New Orleans and the gulf can reduce a storm surge that threatens the city by one foot (source: Anna Simon, MIT, 20 August 2010). Beyond that, the wetlands support industries that contribute substantially to the city’s economy.

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Why wetlands disappear

The bayous and streams that once distributed the main channel of the Mississippi River across its delta have been closed. As a consequence, they no longer replenish the wetlands with sediment. Beyond that, significant areas of wetland have been lost to erosion, subsidence, channelization for navigation and industry. In southern Louisiana 75 square kilometers of wetlands disappear every year; this translates to approximately two acres per hour (source: U.S. Geological Survey, Marine and Coastal Geology Program, 20 August 2010). The BP oil spill of April 2010 dealt a catastrophic blow to southern Louisiana’s wetlands. No one knows what such widespread contamination will mean for the future of the region.

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