Look. We know that all hurricanes are bad. And we know that category 5 hurricanes are really bad.
But something like this hitting New Orleans is perhaps the worst. New Orleans lies below sea level, and is protected by levees. It’s basically a large bowl, and even in normal weather, water has to be pumped out of the basin. And those pumps rely on electricity, something that is unlikely to work in the wake of Katrina.
Read this, published in American Prospect, on May 23 of this year. And as you read, keep in mind that they are predicting 28-foot storm surges, and that Katrina will hit New Orleans at high tide:
In the event of a slow-moving Category 4 or Category 5 hurricane (with winds up to or exceeding 155 miles per hour), it’s possible that only those crow’s nests would remain above the water level. Such a storm, plowing over the lake, could generate a 20-foot surge that would easily overwhelm the levees of New Orleans, which only protect against a hybrid Category 2 or Category 3 storm (with winds up to about 110 miles per hour and a storm surge up to 12 feet). Soon the geographical "bowl" of the Crescent City would fill up with the waters of the lake, leaving those unable to evacuate with little option but to cluster on rooftops — terrain they would have to share with hungry rats, fire ants, nutria, snakes, and perhaps alligators. The water itself would become a festering stew of sewage, gasoline, refinery chemicals, and debris.
A direct hit from a powerful hurricane on New Orleans could furnish perhaps the largest natural catastrophe ever experienced on U.S. soil. Some estimates suggest that well over 25,000 non-evacuees could die. Many more would be stranded, and successful evacuees would have nowhere to return to. Damages could run as high as $100 billion. In the wake of such a tragedy, some may even question the wisdom of trying to rebuild the city at all. And to hear hurricane experts like Louisiana State University’s Ivor van Heerden tell it, it’s only a matter of time before the "big one" hits.
UPDATE: Here’s an article from 2002:
Imagine what a disaster it would be if a hurricane-driven storm surge up to 20 feet high swept into New Orleans or another Louisiana coastal city.
That’s exactly the type of thing a team of Louisiana scientists will be thinking about over the next few years. Their task is to come up with such scenarios and try to figure out both what would happen and how best to recover.
The Louisiana Board of Regents recently approved a $3.7 million grant for the five-year study. The money comes from the state’s share of the national tobacco lawsuit settlement.
Ivor van Heeden, deputy director of the LSU Hurricane Center, will head the effort.
The coastal wetlands that protect New Orleans and other coastal cities in Louisiana are shrinking, making people more vulnerable to hurricanes.
Even a slow-moving category 3 hurricane, which has sustained winds of 111-130 miles per hour, could flood New Orleans, van Heerden said.
"If you flood it completely, you are going to have 13 to 17 feet of water in the city. That forces people to get up on their roofs," van Heerden said. "There would be upwards of 400,000 people trapped because a large number will not evacuate, a large number don’t own motor vehicles, some are disabled or street people."
One idea on how to rescue those people is what van Heerden and his associates call "Operation Dunkirk." Private boats from the North Shore would be used to reach people in New Orleans, van Heerden said.
The name comes from the World World II evacuation of Dunkirk, where a flotilla of private boats shuttled across the English Channel to rescue Allied troops who were trapped by the Germans in France.
Van Heerden said authorities would obviously use helicopters too, but noted that an inundated New Orleans "would stress every resource we’ve got."
The health of people stranded on their roofs would also be a concern.
"Typically, they don’t take clothing, food, water and, particularly, medicines," he said.
Getting the stranded people out of the city would be just one of many difficult aspects of post-storm recovery. Pumping all the water out of New Orleans, most of which lies below sea level, could take up to nine weeks, he said.
"The flood waters are going to contain a myriad of chemicals, in additional to animal corpses — be they wild animals or pets — or even human," he said.
"We could have fairly large and widespread disease outbreaks, and not just one disease," he said.
Dengue fever, West Nile or some other type of encephalitis and cholera are just a few of the potential illnesses, van Heerden said.
Houston’s experience with Tropical Storm Allison last year showed buildings would have to be decontaminated, a time-consuming task, he said.
"Maybe we will have 700,000 people homeless," he said. "We will have to build tent cities. Where are we going to build them? When you concentrate people like that, the disease potential goes up enormously. … This would be a catastrophe, a national catastrophe, and the economic impact would probably exceed $50 billion."