by John C. Stennis Space Center

More articles in Satellites
John C. Stennis Space Center, Stennis Space Center, MS 39529-6000

HANCOCK COUNTY, Miss. — NASA scientists at Stennis Space Center are using satellites to study the Louisiana wetlands, which are disappearing because of erosion, sinking land and rising sea- levels. The wetlands are shrinking at the speed of 65 to 91 square km (25 to 35 square miles) each year.

Much of the Louisiana wetlands, where blue-crab fisher Michael Comardelle has lived all his life, are gone. With the wetlands goes the homeland of Comardelle's Cajun culture, as well as the buried relics of the Native American cultures that came before it.

"That was our playground," Comardelle said. "The swamp and the bayou were right at our doorstep. All that's eroding away so quick, so fast, it disappears in front of your eyes just about." Human alteration of the flow of the Mississippi River is the primary culprit. Flood-control levees along its banks prevent the river from spilling out into the surrounding wetlands. Normally, the sediment from the river would build up the wetlands and help counter the erosion process, but without this influx of sediment, erosion goes unchecked.

The loss is particularly worrisome because southern Louisiana is home to 40 percent of the coastal wetlands in the 48 contiguous states. Beyond the natural functions they serve as water purifiers, these marshes and estuaries are vital to the local fishing and tourism industries and they provide a buffer against flooding by storm surges during hurricanes.

For example, during the recent one-two punch of Tropical Storm Isidore and the following week's Hurricane Lili, Comardelle said that, "people who've been living there 20 or 30 years have never seen storm surges come up that high."

To counter this loss of wetlands, the Army Corps of Engineers is spearheading an ambitious restoration project called Coast 2050. The project will extend 50 years into the future to try to restore 20,000 square miles of wetlands. Because the project will require detailed measurements of the landscape for planning, the Army Corps of Engineers is recruiting data from NASA satellites to help.

Dr. Marco Giardino, acting chief of the Applications Engineering Division for the Earth Science Applications Directorate at Stennis Space Center, is helping coordinate NASA's involvement in Coast 2050. "These swamps and marshes are often very dense and hard to get around in, which makes them difficult to survey," he said. "By using satellite imagery from NASA's fleet of Earth science sensors, we can supplement traditional surveying techniques and improve decision- making."

The first target will be the hundreds of ancient Native American sites scattered throughout the bayou. Most of these are visible only as wide mounds rising just a few feet in elevation. How can a satellite in orbit spot a subtle mound in a vast swamp?

Satellites distinguish changes in vegetation that can be important clues about the wetland characteristics — sunlight reflecting off a patch of swamp carries the "fingerprints" of the area's plant life in its bands of colors, for instance. A patch of oaks will have a different color fingerprint than a patch of reeds or grasses.

So by looking at the reflected light, the satellites that will be used (NASA's Terra, EO-1, and Landsat 7 satellites) can map out the raised areas in a large bayou or swamp, and thus identify candidates for archeological sites.

"The use of satellites will make it possible for archeologists to pinpoint areas to look at on the ground without having to first undertake extensive terrestrial surveys," said Dave Davis, an archeologist at Tulane University and a consultant for Coast 2050.

Coast 2050 hopes to preserve the habitat for thousands of species and restore the buffer between Gulf storm surges and inland cities. They will also help save the bayou that Cajuns like Comardelle call home, and preserve the relics of Native Americans who called it home ages ago.