In the wake of Hurricane Katrina, experts are hoping that the natural marshland that buffers the Gulf coast can be restored. The lack of a healthy ecology in the area, they say, increased the damage from the August storm, and should serve as a lesson for other areas that need protection.
It has long been known that the sandy barrier islands and marshy bayous of the Louisiana coast are capable of acting as a wave-deflecting and energy-absorbing one-two punch. These natural features are in decline however; more than 60 square kilometres of land erode each year.
And there is little mud and silt filtering into the area to replace the eroded material: modern agriculture holds on to silt, as do dams, so the muddy Mississippi is no longer quite so murky.
“It looks green from here. It doesn’t carry the silt it used to,” says Gerald Duszynski from his office in Baton Rouge. Duszynski is the acting assistant secretary of the Office of Coastal Restoration and Management in the Louisiana Department of Natural Resources.
Worn away
Frequent low-intensity storms have battered the area over time, washing away much of the remaining land. The United States Geological Survey reports that several of the barrier islands off the Louisiana coast have been washed away altogether by Katrina.
Robert Twilley, a coastal ecosystem scientist at Louisiana State University (LSU), is not sure that things would be different in New Orleans had the delta still had its Delaware-sized swathe of wetlands. But the communities along the Gulf coast would have been much better off, he says.
Twilley recalls the effect of smaller storms on the same areas 50 years ago: “You’ve got people who as kids never saw water in their yard, and now there’s water in the yard and covering the road. Without a doubt, our coastal landscape used to protect us from storms.”
Similar protection from natural landscapes have been noted elsewhere. Healthy bands of coral reefs or mangroves, for example, saved some areas from the damage wreaked by the tsunami in the Indian Ocean last December; degraded areas fared worse. Experts caution that coastal protection in that area is vital.
“Bangladesh is losing its coasts much as we are, and they have typhoons equivalent to our hurricanes,” notes Gregory Stone of the LSU Coastal Studies Institute in Baton Rouge.
Paying for protection
A 1998 document called Coast 2050, written by state officials, called for significant investment in wetlands restoration, not only for the good of fisheries and endangered species, but for “buffering hurricane storm surges”.
The state’s Department of Natural Resources says it will act on the top priorities of the plan, depending on funds awaiting approval or appropriation in Congress this year. Funding is likely to be far short of the $14-billion estimated cost of the whole plan; observers say they are more likely to get $1.9 billion over ten years.
“Ecosystem services are a hard sell in Congress, let’s face it,” says Twilley, who has worked with the state on coastal management. It is not clear whether the disaster will focus attention on the area and liberate funds, or if money will be spent instead on immediate rebuilding.
“We need sustained funding for our chronic erosion problem,” argues Stone. “The scientists are really frustrated that it has been ignored. I think in many ways you need a catastrophe for the world to sit up.”
Source: Nature.com
Social Profiles