The 1996 acquisition of AIRSAR was flown over Galveston Island and Bolivar Peninsula as part of a three year proposal to study topograhic and vegetation changes on the barrier islands of the Texas Coast. The first AIRSAR acquisition occurred in April 1995 and a second, more extensive acquisition was flown June 25-26, 1996.
Shuttle Photography of Bolivar Peninsula shows the flight lines and the reflector locations for the most recent NASA/JPL's AIRSAR data acquisition. From the shuttle photography, Bolivar Peninsula's two washover fans are evident. Extensive salt marshes occur on these washover fans. In recent decades, much of the land area has been converted to open salt water due to highly localized land subsidence associated with newly active faults. One of the washover fans was acquired in both a parallel pass and a perpendicular pass to capture the full capabilities of the radar.
South Texas Coast
Additional funding was provided by NASA's Johnson Space Center to fly the AIRSAR sensor over Aransas and Compano Bays which are part of the San Antonio/Nueces River Watershed. The San Antonio/Nueces River Watershed has been identified by the state as a high priority area which is environmentally sensitive and is subject to subsidence. The Texas Natural Resources Conversation Commission (TNRCC) have used this watershed as a test site for many of their environmental studies.
In addition to the AIRSAR data acquistion, Calibrated Airborne Multispectral Scanner (CAMS) was flown in early July by NASA's Stennis Space Center. The CAMS data is spectrally similar to the Thematic Mapper which is flown on the Landsat satellites, but offer superior spatial resolution of approximately 3-5 meters. The CAMS spectral range spans the visible to the mid-infrared bands which is important for discriminating vegetation types.
Extensive ground truth and field work was done at the time of the overflights. This included the deployment of 1 meter di-hedral reflectors placed at several locations along the flight line. Each of the reflectors were surveyed into a GPS database and will be used for image registration and recognition. The majority of the reflectors were placed near the beach, typically 50 meters inland from the dunes.
Beach profiles were made at several locations along the islands, including many of the reflector sites. The beach profiles were made by a theodolite and show relatively small slopes, typical of the Texas coasts. In addition to beach profiles, vegetation and soil samples were taken at several locations identified as a marsh testsite for this study. The vegetation from the herbaceous marsh consisted mostly of salt marsh vegetation. These include Spartina alterniflora, Spartina patens, Juncus roemerianus, Batis maritima, Salicornia virginica, Borrichia frutescens, and Distichlis spicata. Salinity and GPS measurments were also taken at several locations in the testsite on Bolivar Peninsula.
Further ground measurements were made with the help of the Marine Science Institute which is located in Port Aransas, Texas. Students from UT were taking extensive vegetation surveys as well as soil samples at several locations along the Aransas and Compano Bays. Reflectors were also placed at several locations in the San Antonio/Nueces River watershed and will be used for image registration and recognition.
Many thanks are necessary for making this data acquisiton possible;
Center for Space Research, Bureau of Economic Geology, Marine Science Institute, Johnson Space Center, and Texas Space Grant Consortium.
Thursday, 17-Feb-2005 16:53:58 CST
CSR/TSGC Team Web