Water depth of the shallow water area can be reflected in SAR (Synthetic Aperture Radar) imagery and TM imagery.
The water depth can be detected by SAR and by TM. The water depth SAR detection is based on the mathematical
model describing the movement of tidal current and the interaction between the Radar's microwave and the micro-scale
waves in the sea surface. The water depth TM detection is based on the relation between the water depth and the gray
value of TM image. In order to testify the capability of the water depth detection by SAR and by TM, one area in Taiwan
Shoal, which locates in 118.55°~118.75°E, 23.0°~23.3°N, is taken as the study area for the water depth detection by
SAR and by TM. The detection results shows that SAR image and TM image also can be used in the water depth
detection, but the detection results by SAR is better than by TM and the largest water depth detected by SAR is larger
than by TM. The water depth TM detection result based on several typical real water depths includes the large-scale
information of underwater topography, and this can be used in the water depth SAR detection as the initial water depth.
A new water depth detection method combing SAR image, TM image and several typical real water depths is concluded.
Synthetic Aperture Radar is a most useful instrument for internal wave observation. The northern of South China Sea (SCS) is one of interested sea areas to researchers, and the large amplitude and long-crested internal solitary waves in this area are often encountered in SAR images. The waves are generated by the interaction between the tidal current and shallow bottom topography in the Luzon Strait. The spatio-temporal distribution of internal solitary waves in the northern of SCS is studied by analyzing the ERS SAR images from 1995 to 2001. In the South China Sea internal wave occurs frequently from May to August, and infrequently from November to next March. The frequent occurring area of internal wave is located in north of coral reef Dongsha. Using an ERS-2 SAR image the amplitudes of internal waves in Xijiang oil field in Northern of South China Sea are estimated by one-dimensional model with good result compared with data in situ.