Hurricane Destroys Last of Nature’s Speed Bumps

As scientists review aerial photographs of devastation, the evidence of the next huge challenge facing the Gulf Coast jumps out at them: Katrina ripped through the coastline’s few remaining barrier islands, and with the hurricane season half over, New Orleans lies naked to the ravages of future storms.

“The entire delta is gone, destroyed,” said James B. Johnston, a biologist who coordinates the study of Louisiana’s coastline at the National Wetlands Research Center in Lafayette, La.

For years, coastal engineers and hurricane scientists have warned about the destruction of the region’s wetlands and sand barrier islands that acted as nature’s speed bumps against wind, waves and storm surge.

Now, officials from Louisiana are begging Washington to help shore up these natural buffers so that the inundated city of New Orleans will stand a chance against the forces of nature once it is rebuilt.

“These barrier islands and wetlands are our first line of defense from hurricanes,” said Sidney Coffee, who heads Louisiana Gov. Kathleen Babineaux Blanco’s coastal policy office. “This needs to be treated as an emergency. We need everyone to recognize that restoration efforts must begin immediately.”

Those who have spent years pushing for more federal dollars for wetlands restoration lament how the tragedy has unfurled -- precisely as predicted.

“We used to say, we either pay now or later. We are in the later part,” said Valsin A. Marmillion, former chief of staff to then-Rep. John B. Breaux (D-La.) and now a spokesman for America’s Wetland: Campaign to Save Coastal Louisiana, a public education group. “When you repair things in an orderly way, it costs much less than to have them upended and then have to be put back together.”

A wish list of coastal restoration projects worked out by 11 state and federal agencies has a price tag of $14 billion.

The problem is that the southern edge of Louisiana is slowly sinking into the Gulf of Mexico. And the Mississippi River, confined to channels by levees, deposits its mud and sand directly into the Gulf rather than rebuilding marshes and barrier islands with a fresh layer of sediment as it did for millenniums.

As a result, Louisiana has been losing about 24 square miles of its coastline a year, a process that has been accelerated by canals dredged through the wetlands, mostly used by the oil and gas industry. So much marshland has receded into open bays that New Orleans, a city that largely lies below sea level, had come to resemble a bowl surrounded by water. Its levees had fended off Lake Pontchartrain to the north and the Mississippi River to the south and west.

“We understand the problem. Now let’s fix it,” said Robert Reece Twilley, an ecologist at the University of Louisiana in Lafayette.

Twilley led a team of scientists who helped the Army Corps of Engineers in 2000 to develop a $2 billion plan to get started on coastal restoration. The plan, which stalled in Congress, would release some freshwater and sediment from the Mississippi River to replenish marshland and shore up barrier islands with dredged sand.

Scientists say it won’t be possible to make New Orleans and coastal Louisiana disaster-proof. Nor will they speculate whether fully restored barrier islands and a healthier buffer of marshland could have saved the city from disastrous breaches in its levees. But they do say the storm’s momentum would have been slowed.

As a general rule, most scientists say, every mile or two of marshland will reduce a storm surge by a foot. A storm surge is the wall of water that moves like an extremely high tide in front of a hurricane. Marshland, or any other kind of land, quickly reduces the strength of winds and waves because it robs hurricanes of the warm water that fuels them.

“I don’t subscribe to the philosophy that this was a monster [hurricane] and there was nothing you could do about it,” said Gregory William Stone, a coastal sciences professor at Louisiana State University. “Every time you replace water with land, you reduce wind speed, storm surge and wave height.”

In the initial analyses, Stone said, Hurricane Katrina eerily followed forecasting models of hypothetical storms.

Katrina hit the coast with a 20 to 25 foot storm surge and carried at least a 10 foot surge into Lake Pontchartrain, he said. That was topped by wind-driven waves 5 to 7 feet high.

“It was just too much for portions of those levees to withstand,” Stone said.

The storm surge passed right over a necklace of barrier islands, the Chandeleur Islands, stripped of vegetation by Hurricane Ivan last year. Some of them are now submerged shoals with waves breaking over them instead of islands protruding from the surface of the sea.

“The Chandeleurs could have played a critical role in diminishing Katrina, if they had been robust,” Stone said.

It was the transformation of those islands that stunned Johnston and other scientists at the U.S. Geologic Survey’s National Wetlands Research Center when they saw the aerial photographs after the hurricane.

The flyover survey showed that half of the land mass had vanished. Images from space revealed how much land Louisiana had lost since the 1930s -- an area about the size of Delaware.

In 1969, the Louisiana coast was hit with an even more powerful storm: Camille, a Category 5 hurricane. Katrina was downgraded to Category 4 just before it reached the coast.

“Camille’s path was slightly more to the east, but it’s pretty clear that because there was more landmass then to slow the wind and absorb the water, there was less damage,” Johnston said. “That means that if this land was even a few feet higher, there would have been less damage in New Orleans now. Our wetlands could have prevented damage if they had been there.”

Coastal engineers are hoping to make some progress in wetland restoration, under a program contained in the comprehensive energy legislation signed by President Bush last month that is expected to share more oil and gas revenues with oil-producing states.

Louisiana state officials have pledged to place their share of the $541 million into a coastal restoration trust fund.

None of this comes too soon to those scientists who have long-studied the problem.

“As I say at the beginning of every hurricane season,” Stone said, “coastal Louisiana is more vulnerable to storm surge and storm wave inundation than the previous hurricane season.”

Cart reported from Louisiana and Weiss from Los Angeles.