Report says river flow can be turned up to keep oil at bay
Works that divert 30 percent of Mississippi River
Now that human technology has failed to keep oil out of Gulf coast wetlands, some scientists think the solution lies with one of nature's most ancient techniques—flooding of the Mississippi River.
The scientists have concluded that powerful river flows kept oil from the BP/Gulf spill from invading large areas of wetlands. But as winter runoff diminished, so too did the river flow, and now oil is making a destructive invasion. The strong flow could be restored, however, by simply adjusting dams upstream that are diverting water out of the river bed.
It almost seems too simple, but as a report in Popular Mechanics points out, the Army Corps of Engineers is considering the idea and no one seems to oppose it. PM magazine says the idea was first presented last week to the EPA by Paul Kemp, a former professor of marine science at Louisiana State University and current vice president of the National Audubon Society's Louisiana Coastal Initiative.
Here is how the magazine writes about the idea:
Kemp says the river is "the biggest tool in the toolbox" when it comes to keeping oil out Louisiana's swamps and marshes, which make up nearly 40 percent of the nation's wetlands.
For the most part, the winds have kept the oil plume from moving toward the Louisiana coast, Kemp says, instead pushing it toward Florida and Alabama. Last month, the winds shifted to the northwest. Even then, when the oil seemed as though it should have been blowing towards the mouth of the river, it didn't, says Denise Reed, a proponent of Kemp's plan and professor of earth and environmental sciences at the University of New Orleans. "That seems to be because there's been enough water coming out of the mouth of the river to have a little bit of a push out into the Gulf of Mexico," Reed says.
Since then, however, the water level in the Mississippi has dropped off drastically, due to seasonal changes in climate. "Time is of the essence. Every day we are losing another 40,000 to 50,000 cubic feet per second out of the river. I'm very concerned that all we need is a shift in the winds offshore, and when the oil comes in this time there won't be enough to keep it from coming into the interior of the marshes," Kemp says.
The water level can be raised using large concrete dams, called the Old River Control Structure, which sit 315 miles upstream from the river's mouth. These dams, which are maintained by the U.S. Army Corps of Engineers, control flow between the Mississippi and a smaller tributary to the west called the Atchafalaya River. Usually, they direct about 70 percent of the water down the Mississippi, with the remaining 30 percent diverted to the Atchafalaya. Kemp's plan calls for a gradual daily increase in the amount directed to the Mississippi, so that over the course of 10 days the river's proportion would increase to about 81 percent—maintaining the approximate level of the river in May. He is also looking into manipulating additional dams even further upstream.
An additional benefit of the plan, according to Kemp and Reed, is that a higher river could help clean off the oil that has already collected on the fringes of the marshes. This effect, called gentle flushing, is one of the few methods that can remove oil from the wetlands while minimizing ecosystem damage.