Some commentators have suggested that the ongoing oil spill in the Gulf of Mexico could be “another Katrina,” a reference to the major hurricane that nearly leveled New Orleans in 2005. For the most part, the comparison is a stretch. No major cities will have to be evacuated for the oil spill, millions of people will not be made homeless, drinking water and cellular telephone service will continue to be available, oil and natural gas production in the area will not have to shut down completely for a couple of weeks.
In some ways, though, a prolonged oil spill could be just as harmful as a major hurricane. One of those ways, possibly, is the effect on the land area of the Mississippi delta. By knocking over the trees that hold the ground in place, Hurricane Katrina took away significant parts of the land area of the Mississippi Delta. Much of this was land that was below sea level, held in place only by grass and trees. After the hurricane washed the plants away, normal coastal erosion washed away the ground, making it impossible for the plants to grow back. Where there used to be land a foot below sea level, now there is sea water five or ten feet deep.
An oil spill could have the same effect. According the the EPA, light crude oil, the kind that would tend to wash ashore, kills grass quickly, and prolonged exposure to oil can damage the roots of any plant, including trees. No one knows a way to clean up oil from a salt marsh, however, so any oil that gets in will tend to linger there, and from everything we know, we would expect it to kill off most of the plants. If oil kills plants, it has the same effect as a hurricane. The tides can then wash the unprotected ground away, potentially taking away most of the land area east of New Orleans.
This would be a serious problem for the city. The lowlands act as a barrier protecting New Orleans from the waves of the gulf. If they are washed away, it wouldn’t take a hurricane to prompt an evacuation of New Orleans. Any little storm would be able to flood half the city.
The only answer is to keep the oil offshore, as much as possible, and hope for the best. Choppy weather yesterday, though, washed the oil slick right over the barriers that were meant to stop it. If the weather improves and the oil spill can be stopped, there is a chance that the oil can be kept out of the Mississippi delta. If not, though, this event could lead to land losses just as significant as you would see in a major hurricane.