Processing and interpretation of 95 kHz backscatter data from shallow-water multibeam sonars

95 kHz backscatter data are routinely collected by the Canadian Hydrographic Service using shallow water multibeam sonars (Simrad EM100 and EM1000 systems). This data is co-registered with high resolution bathymetry and provides a means of generating sidescan images of the seabed which can be correlated with the bottom topography. Changes in amplifier gains are corrected so that the authors can compare the acoustic signature of distinct seabed lithologies for use as part of a remote sediment classification scheme. In order to groundtruth the acoustic signatures, an experiment is underway in the Bay of Fundy (using the intertidal zone where tidal ranges locally exceed 15 m) using terrestrial survey and sampling methods. As part of the experiment, interactive graphical tools have been developed that allow the data to be processed as it is acquired and enable near-real time data quality assessment