Study of Wetland Flow Dynamics Using Satellite Altimetry

Study of wetland flow dynamics using satellite altimetry
Motomu Ibaraki1, Hyongki Lee1 and C.K. Shum1
1 Department of Geological Sciences, The Ohio State University, 125 South Oval Mall,
Columbus, Ohio 43210-1308, USA
Tel: (614) 292-7528; Fax: (614) 292-7688;
Wetlands typically occur in low-lying areas at the edges of lakes, and rivers, or in coastal
areas protected from waves and are found in a variety of climates on every continent except
Antarctica. Wetlands not only provide habitat for thousands of aquatic/terrestrial plant and
animal species but also control floods by holding water much like a sponge. Wetlands filter
pollutants and sediments and so provide a major environmental and health benefit in cleaning
up contaminated water. Human activities have so many negative impacts on wetlands and
these became main contributing factors to many wetlands loss. Louisiana's wetlands has lost
more than 100 km2 of its area per year. Satellite radar altimetry has been proven to be useful
for large lake and river hydrologic studies, however, has not yet been used for measuring of
water elevation changes of wetland and coastal estuaries, including Louisiana wetlands. In
this study, we demonstrate the use of TOPEX/POSEIDON radar altimetry to measure wetland
water level changes over Louisiana wetlands. It is found that most of the waveforms are
specular (narrow-peaked), and the waveforms are retracked using threshold algorithm. Six
study sites are chosen to generate decadal (1992-2002) time series of relative water level
changes which show a clear seasonal variation. The altimetry measurements generally agree
well with the river stage measurements which were obtained near the study sites. Seasonal
and interannual variations are quantified, towards understanding the underlying flow