[StBernard] Teams gathering data on remains of battered islands

[Westley Annis]

Teams gathering data on remains of battered islands
Posted by By Mark Schleifstein, Staff Writer July 08, 2007 10:34PM


>From the air, the Chandeleur islands -- a 50-mile-long nearly contiguous

crescent of sand, topped in places with 18-foot dunes just a decade ago --
appear a tattered assemblage of sandy spits that poke out just a few feet
from the Gulf of Mexico. 
Neighboring barrier islands suffered a similar fate. What once was Curlew
Island, a separate crescent between the Chandeleurs and Breton Island to the
south, is a series of submerged, zigzagging sand bars. Only a sliver of
nearby Grand Gosier Island has emerged from the water in the nearly two
years since Hurricanes Katrina and Rita. 

In a mere decade, ferocious hurricanes have splintered the land and washed
much of it out to sea, destroying a vital barrier that once sapped power
from the storms before they surged ashore on the mainland. Though the
islands have been eroding for more than 1,000 years, scientists believed as
recently as the 1980s that they would survive for centuries to come. 

"When we made predictions on how long various barrier islands along our
coast would last ... we gave the Chandeleurs 300 years," said coastal
geologist Shea Penland, director of the University of New Orleans'
Pontchartrain Institute for Environmental Sciences, during a flight out to
the islands two weeks ago. 

Now, with that life span cut short, scientists and government officials have
to figure out whether and how to rebuild the barrier islands, all part of
the Breton National Wildlife Refuge, and at what cost. 

Historically, barrier islands have played a key role in knocking down storm
surge and reducing wave energy before it reaches the coastal wetlands and
levees that provide the other two lines of defense against flooding. To that
end, scientists financed by the Army Corps of Engineers have launched an
effort to survey the remains of the islands and to find the sand that's been
washed off their beaches by a century's worth of hurricanes. 

Using satellite-based surveying equipment, sensitive measuring instruments
pulled behind ships to measure the depth of underwater sand deposits, and
Lidar -- a type of laser-based radar -- they're mapping the post-Katrina
height of the islands and the sand deposits in the water surrounding them. 

The team is drilling into the underwater sand deposits to sample their
makeup, seeking to determine whether the sand grains are the right size and
shape to be used in rebuilding the islands. The scientists are also mapping
the currents that move sand back and forth between hurricanes, and the level
of salt in the water surrounding the islands. 

Yet as they pinpoint potential solutions, scientists also have to be mindful
of the role of the islands and their sea grasses and marshes in the life
cycles of the rich fisheries that are important not only to the economies of
Louisiana and Mississippi, but the entire nation, and the bird habitats that
first brought the islands into federally protected status a century ago. 

Back in 1904, when President Theodore Roosevelt rolled all of the islands
into the then-new Breton National Wildlife Refuge -- the nation's second
refuge -- he aimed to protect those birds and their eggs from human
predators, not hurricanes. 

Today, the rookeries of brown pelicans, terns and other water birds that
once covered the wide expanse of sand dunes at the southern end of Breton
must now bunch together precariously on the flat, tiny patch of sand that is
the island's northern point. 

The research team includes UNO, the U.S. Geological Survey and the Louisiana
Department of Natural Resources. The U.S. Fish and Wildlife Service, which
governs the refuge, will use the research to make decisions on whether and
how to rebuild the island, and at what cost. Scientists hope to find out how
to get the biggest bang for the buck in rebuilding islands along the coast,
before they disappear. 

The monitoring program on the Chandeleur-Breton island chain is part of a
new statewide Barrier Island Comprehensive Monitoring Program aimed at
gathering data on all barrier islands and sand shorelines along the
Louisiana coast. It joins a separate federal-state monitoring program aimed
at measuring the effects of rebuilding projects on interior wetlands. 

The data from both are providing state and federal officials with a rich
source of information that's already being used in developing larger
restoration projects as part of the $500 million Coastal Impact Assistance
Program and the larger, proposed Louisiana Coastal Protection and
Restoration Plan, said Darin Lee, the monitoring program's state project
manager.

Demise of a delta 

More than 3,000 years ago, the Chandeleur islands and their neighbors
weren't islands at all, but part of a rich expanse of wetland delta at the
mouth of an earlier pathway of the Mississippi River, which ran east through
what would become New Orleans before emptying into the Gulf. 

What became known as the St. Bernard Delta started to erode, however, when
the river switched to a more westerly path to the Gulf of Mexico 2,000 years
ago, leaving behind a crescent of shoreline beaches and wetlands that began
sinking under their own weight. 

As winter storms and hurricanes worked and reworked the outer edges of the
marsh, the Chandeleur crescent formed. At the same time, the Gulf continued
to swallow what became known as the Biloxi Marshes: the wetlands between the
island and what is now New Orleans and St. Bernard Parish. 

Given that history, scientists are hardly surprised to see the islands
continue to sink and erode, but the speed at which they are disappearing has
alarmed them. Katrina and Rita ate away up to 1,000 feet of shoreline at
some points along the islands. But predicting what restoration projects will
be successful has been difficult because of a lack of understanding of how
the barriers and shoreline beaches behave in both hurricanes and other
storms. 

"We've never had enough baseline information to fully understand how these
islands perform naturally or how they're affected by storms or other
processes," Kirk Rhinehart, coastal restoration director for the Department
of Natural Resources, said during the plane ride to the islands. 

UNO participated in a $1 million program to replant marsh plants and sea
grasses in shallow water on the western side of the Chandeleur chain after
Hurricane Georges sliced the crescent into little pieces in 1998. 

The corps also delivered sand dredged from the Mississippi River-Gulf Outlet
to areas just offshore of some of the islands, where waves washed it ashore
to strengthen beaches. They used that method because federal rules at the
time prohibited applying sand directly to the island, a protected wilderness
area. The rule was one of a series of regulations aimed at limiting the
disruption of natural processes of all federal wilderness areas. But the
prohibition made no sense for the unique case of a dying island, and has
since been changed. 

Both projects seemed a success until the one-two punch of Katrina and Rita
washed away much of the replanted areas, Rhinehart said. 

"For the Chandeleurs, the critical question is: Have we passed the point of
no return?" Penland said. "The islands have shrunk since 1998, hit by
Georges, Isidore, Lili, Katrina and Rita." 

Naturally resurgent 

The Fish and Wildlife Service also is interested in the information because
of its value in determining whether the island refuge can be restored and
how best to do it, said Dawn Lavoie, Gulf Coast science coordinator for the
U.S. Geological Survey. 

"We'll be able to determine what's the future of Breton Island, with and
without restoration," Lavoie said. "It's a key habitat for migrating birds
and for brown pelicans, and we have to keep that in mind. Before Katrina,
there were 4,000 breeding pairs there. Last year there were only 600." 

Penland remains convinced that despite the dramatic loss of sand during
Katrina and Rita, natural movement of the sand near the islands will help
rebuild them, just as it has over the past century. 

"There's a favorable wave climate, a sand-rich wave climate that you see in
the re-emergence of Grand Gosier Island," Penland said. "We see both strong
hurricane impacts and some recovery." 

Indeed, measurements along northern Chandeleur indicate some areas that lost
700 feet of beach to Katrina and Rita already have seen 300 feet of beach
return. And even the underwater remains of devastated islands can help
reduce the effects of hurricane storm surge on inland areas and protect
fisheries, he said. 

And though almost all of Grand Gosier Island is submerged, its shoal still
provides a barrier between the pounding of Gulf waves and the less-saline
remains of the Biloxi Marsh. 

That was reinforced by modeling conducted by the corps-sponsored Interagency
Performance Evaluation Task Force, which indicates making the wide stretch
of sea bottom shallower between the Chandeleur islands and the shorelines of
eastern St. Bernard and New Orleans could reduce the height of storm surge,
Penland said. 

"We'll have more information to guide investments in the new landscape
behind the islands," he said, "and know at what points we might want to
intervene with an oyster reef or a sand reef." 

To gather that information, the interagency team is using a fleet of boats
and ships that allows measurements to be taken in the water and on the
beaches. 

"The task here is to map the sea floor," said Mark Kulp, associate director
of UNO's Pontchartrain Institute for Environmental Sciences. "The
geophysical measurements allow us to reconstruct what the depth of water is.
Then we can compare that with historic data sets to see what changes are
taking place, where we're seeing sand depositing on the former island
locations."

Mark Schleifstein can be reached at mschleifstein at timespicayune.com or (504)
826-3327.