STENNIS SPACE CENTER, Miss., Sept. 6 (UPI) -- A satellite monitoring program that tracks sediment changes in shallow waters could become a valuable tool to help scientists understand more clearly what is going on in such environments and also benefit human health.
Scientists at NASA's Stennis Space Center tested how technology that roams across the sky might open a window to what is going on beneath the water's surface.
Led by Richard Miller, chief scientist for NASA's Earth Science Applications Directorate, researchers used two spacecraft -- NASA's SeaWiFS satellite and the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer -- to take pictures of shallow water and measure changes in light or reflectance of the water, an indication of sediment moving around.
SeaWiFS, which stands for Sea-viewing Wide Field-of-view Sensor, orbits about 248 miles above the Earth and takes photographs of the water.
Miller's team tested this technology on Lake Pontchartrain, just north of New Orleans. Wind-driven waves can stir up sediment, called natural re-suspension. What scientists are looking for, Miller explained, is to know where re-suspension is occurring and how intense it is.
"The key is to be able to quantify the amount of sediments in the water," Miller, who is manager of the Lake Pontchartrain project, told United Press International. "With this particular system, we should be able to monitor the transport of particles."
Using a computer model, the researchers are able to calcuate the expected level of sediment stirring based on wind direction and speed, and the depth and shape of the water. The computer returns with its calculation, a figure referred to as the index of resuspension intensity. It then is plotted over the body of water in the form of contours or colors.
Understanding changes in sediment can provide clues to the chemical composition of the water. For example, chemicals that get into the water are dissolved and absorbed by particles, Miller explained. Bacteria start using up the oxygen in these particles or sediment, and when oxygen levels change in the sediment, the solubility of these chemicals changes. If a storm or strong wind passes through, those particles and potentially harmful chemicals could be released.
"I don't want to imply we can monitor pollutants," Miller said. The system doesn't make judgment calls on water quality, however if the satellite notices something different, NASA scientists can alert the appropriate authorities to a potential problem in the water. That, in turn, could result in beaches being closed or warnings about consuming fish or shellfish from a particular body of water.
"That's a problem for human health," Miller said. "From looking at the color of the water, it gives us an idea of what's in the water."
Results from the Lake Pontchartrain project have been so successful a similar pilot project is underway at East Carolina University in North Carolina. Miller's research team also has started a new phase of field tests using a different satellite sensor with clearer resolution, called MODerate-resolution Imaging Spectro-radiometer or MODIS.
Miller said it's not yet known when the system might expand. "When you're developing a new or better mouse trap, you got to test it," he said.
Ed Overton, a professor of environmental sciences at Louisiana State University in Baton Rouge, said this new satellite technology is very exciting and promising.
"I congratulate NASA on their vision," Overton told UPI. "This will open up a window of information. This technology could have huge implications for the coast," where coastal erosion is a growing problem.
One of the advantages of satellite technology is that it provides a fresh perspective from a distance of what is going on in the waters, as opposed to researcher being knee-deep in these waters and taking samples. As the technology develops, Overton added, scientists will think of newer applications that might not have been part of the original project. "This will open up opportunities we never thought of before."
(Reported by Katrina Woznicki, UPI Science News, in Washington)
