Classification of geomorphological features in Pântano do Sul Bay (SC) from side-scan sonar images

The objective of this work is to characterize the submerged bedforms of Pantano do Sul Bay (State of Santa Catarina) from the identification of local geomorphological features and speculation about their relationship with the dynamics of the inner continental shelf. Geoacoustic data was collected using a 540 kHz interferometer/phase differentiator and covered approximately 200 km of sampled lines. Obtained data was processed in SonarWiz 6 and followed the steps: botton track detection and signal processing to enhance the images. The filters used were: 1) Automatic Gain Control (AGC), where the large-scale effects of the angle of incidence and of the propagation distance in the reflected amplitude of a signal are eliminated; and 2) Time Variation Control (TVG), in which the filter attempts to create a uniform display of sonar data from close ranges to the edge of the beam, in dealing with progressively weaker signals over longer distances. The obtained classification was manually inferred and aligned crests, apparently composed by sand, and flat areas, suspected to be sand-mud, were identified along the area. Apparently, the group of islands located at the entrance of the bay has as important contribution in the geomorphic configuration of the bay's substrate due to the transformation induced over incident waves.