A comparison of acoustic imagery of sea floor features using a towed side scan sonar and a multibeam echo sounder

Significant improvements in the quality of imagery data available from multibeam echo sounders have recently been made. The intensity time series values are derived from the same transmit beam pattern that produces the sounding values. This sampling approach provides a dataset with co-located bathymetry and imagery. This paper presents examples of seafloor features imaged with both a Klein system 2000 towed side scan sonar and with Reson 8100 series multibeam echo sounders. The multibeam echo sounder imagery presented is derived from the receive beams formed to make the bathymetric measurements. The comparison focuses on depths shallower than 40 metres, and including a variety of terrains surveyed along the northeastern US. The areas investigated include hydrographically significant bottom features and multiple benthic habitats imaged with both types of systems. This paper demonstrates the contribution that can be made when the multibeam echo sounder imagery data is acquired and processed along with the bathymetry data from a multibeam echo sounder. The imagery data can provide complimentary information during the processing and analysis phases of data reduction. While the resulting imagery is not as sharp as the imagery from a towed side scan sonar, the resulting dataset does offer some significant advantages. This approach can support a wide range of survey applications including: hydrography, search and locate, route survey, habitat mapping, and seafloor characterization.