By: Bob Marshall, The Times-Picayune |
The 20 Arpent canal levee runs straight as a green arrow through the wetlands of eastern St. Bernard Parish, its sides covered with a thick carpet of grass, its crown dry and firm enough to support the SUV Hassan Mashriqui has just stepped from to begin his lecture.
With a wide wave of his arm the Louisiana State University researcher is explaining that on Aug. 29 the western edge of Hurricane Katrina's eye wall passed over this spot, its 85 mph winds driving 5-foot waves across the top of a storm surge that would rise to 17 feet on the nearby Mississippi River-Gulf Outlet. Levees just to the north and east of where Mashriqui stands crumbled under the shock of waves and water, allowing a flood of death and destruction to swamp the parish.
But the only evidence of that violent night on the 20 Arpent Canal levee is a line of marsh grass that rests about 10 feet from its crown.
"Why the difference?" asks Mashriqui, who quickly provides the answer by pointing to the thin line of trees and marsh beyond the debris line. "It is this marsh and those trees that saved this levee."
"This is called greenbelt defense. On soils like we have, marsh and trees - even small amounts - can be better armoring than concrete and steel, because they don't sink, and don't have to be rebuilt."
"Katrina has proven these are things we must start considering."
In the months since Katrina took only a few hours to humble the system of levees and floodwalls built by the Army Corps of Engineers over 40 years, most of the headlines have been generated by investigations focused on "what went wrong." But a quieter, equally important story is being written by researchers studying what went right.
Storm specialists want to know why Katrina's fury reduced some levee sections to warm Jell-O while others nearby stood tall and strong. The answer, they are finding, comes in two parts.
The America's WETLAND Foundation manages the largest, most comprehensive public education campaign in Louisiana's history, raising public awareness of the impact of Louisiana's wetland loss on the state, nation and world. The America's Energy Coast initiative works to sustain the environmental and economic assets of the Gulf Coast region. The initiative is supported by a growing coalition of world, national and state conservation and environmental organizations and has drawn private support from businesses that see wetlands protection as a key to economic growth. For more information, visit www.americaswetland.com or www.futureofthegulfcoast.org.