Sunday, August 27, 2006
With global warming and storms on the rise everywhere, other nations are trying to learn from the human errors that led to the disaster of Katrina. Prescriptions are to slow down construction near the coasts, build flood gates to protect against storm surges, and preserve wetlands that serve as buffer to coastal storms and erosion. These are all essential.
Meanwhile, back in the United States, we constantly hear that the losses of Louisiana’s coastal wetlands, in part destroyed to help “big oil,” exacerbated the impact of Katrina. There is no doubt that the erosion of Louisiana’s coastal wetlands increases the risk of storm damage to human settlements. And at least part of the New Orleans flooding was caused by water funneling up the much-maligned Mississippi River-Gulf Outlet, leading to a “Mr. Go Must Go!” campaign. This is all well and good. But let’s not forget that such land use decisions involve difficult trade-offs. One of the chief reasons that Louisiana’s wetlands have been disappearing are the levees and channelization of the Mississippi River, which no longer periodically floods with its sediment, as it did for millennia. This work was done to protect Americans from the horrible consequences of river floods, such as the 1927 disaster. As let’s also not forget that most of the damage to New Orleans came from water pushed into the city’s canals (themselves built to flush standing water out of the city) from Lake Pontchartrain to the north, not from the wetlands areas to the south and east. Flood control changes necessarily involve difficult choices, with the amelioration of some threats creating others.