Coastal-ecology degradation contributed to Katrina’s destructive force

Far from being solely a “natural” disaster, Hurricane Katrina’s impact was compounded by human alterations of the Gulf Coast ecology. Complex levee and canal systems built to protect New Orleans from being flooded by the Mississippi River, and to improve the river as a shipping channel, have also prevented river silt from replenishing the region’s marshlands and river delta for centuries. More than a million acres — 1,900 square miles — of Louisiana’s coastal wetlands have been lost to development and flood controls since the 1930s, along with barrier islands and stands of coastal forest. Louisiana continues to lose about 25 square miles of coastal area each year. These natural barriers could have absorbed some energy and water from Katrina’s storm surge and mitigated the hurricane’s force; studies estimate that storm surges rise by about a foot for each square mile of wetlands lost. As recently as last week, Louisiana’s senators and the federal government were grappling with funding for wetlands and coastal restoration.