US built 2,000 km of Mississippi levees; Louisiana later lost 4,900 sq km of land
The construction of 2,000 kilometers of levees along the Mississippi River has protected infrastructure but caused severe ecological damage by starving coastal Louisiana of sediment. This has led to the loss of 4,900 square kilometers of land, prompting environmental agencies to attempt restoration by pumping mud back into the delta.
Why it matters
It illustrates the long-term, unintended environmental consequences of large-scale civil engineering projects.
Nearly 2,000 kilometres of levees built along the Mississippi River over the past century helped protect cities and farmland from major floods. But the barriers also caused one of North America's most serious ecological losses. By cutting coastal estuaries off from vital river sediment, the flood control system has contributed to the loss of about 4,900 square kilometres of Louisiana's coastal land since the 1930s. Without fresh silt spreading across the delta during annual floods, large areas of coastal marshland have slowly sunk beneath the Gulf of Mexico. Detailed maps and scientific records from the United States Geological Survey (USGS) show that Louisiana lost nearly 1,900 square miles of coastal land between 1932 and 2010.
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