The study area comprises Bolivar Peninsula and Galveston Island which, are both low-lying barrier island/spit structures located at the mouth of Galveston Bay. There are some differences between the two; Galveston Island is fairly developed and is comprised of a lot of sandbars. Bolivar Peninsula, on the other hand, is more remote and contains extensive wetlands.
Data Acquisition
One of the more recent sensors to be used for remote sensing is Synthetic Aperture Radar (SAR). SAR can be used for classification of terrestial environments. Measurements of the SAR backscattering coefficient can be related to topography, geology, soil moisture and salinity, and vegetation density and structure. The focus of this work is the modeling of the SAR backscatter coefficent for coastal environments. Fully polarametric SAR data in C, L, and P bands as well as the fixed-baseline interferometric SAR (TOPSAR) were acquired in April 1995 and June 1996. The data were acquired to detect topographic change and relict geomorphic features on the islands and to map the coastal wetlands.
Information on 1996 acquisition
Data Analysis
An initial study of the AIRSAR data was to identify and map herbaceous coastal wetlands. Our testsite on Bolivar Peninsula contains several environmental units including salt marsh, vegetated upland flats, and an intermediate transition zone. These regions often have maximum elevations of only five feet above sea level, so slight variations in elevation can have a great impact on determining the species of vegetation which are found there.
Each of these subenvironments have distinct vegetation cover, soil texture, and soil salinity. These highly vegetated areas make it difficult to apply empirical surface models to represent the backscatter which is received by the AIRSAR. However, discrete scatterer models can be fit to the coastal wetland site on Bolivar Peninsula. These models provide some insight into the dominant scattering mechanisims, and should aid in mapping of coastal wetlands.
Further Reading on Vegetation Modeling, : "Modeling Wetland Vegetation Using Polarimetric SAR" C. Slatton, M. Crawford, J. Gibeaut, R. Gutierrez
