Scientists believe wetlands are important ecologically, because they filter wastes out of the water. They also provide a barrier between the land and large bodies of water, such as the Gulf of Mexico . During a hurricane, for instance, vegetated wetlands act like sponges to absorb water from a storm surge, as they absorb some of the energy from the storm itself.

But gauging the health of wetlands can pose a challenge. The interior regions are hard to reach, which makes it difficult for scientists to measure water levels manually. Most in-ground gauges are placed in easily accessible areas along the edges.

Case in point: two of the four locations imaged by radar in this study were deep within the wetlands, with the closest in-ground water gauge miles away. That posed a difficulty for Shum's team as they tried to determine whether their satellite data was accurate.

"Some of the gauges were quite far away, but at least we were able to show a qualitative agreement with seasonal changes," Shum said.

In future studies, they want to examine data from more locations, and couple the data with more ground measurements.

"Because of the ground track layout for TOPEX/Poseidon, most times one has to be lucky that the tracks fall on the wetlands. We may try using other radar altimeter satellites to improve the spatial resolution of the wetland study. However, the primary limitation for TOPEX/Poseidon is its narrow measurement swath on the ground," Shum said. The satellite gathers data in a strip, up to only 3 miles wide.

Shum pointed to the proposed WATER HM (short for Water And Terrestrial Elevation Recovery Hydrosphere Mapper) satellite mission, led by Doug Alsdorf, assistant professor of earth sciences at Ohio State . That miss
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Contact: C.K. Shum
ckshum@osu.edu
614-292-7118
Ohio State University
11-Dec-2006