Multibeam assessments of Australian seabed habitats

Abstract

In the period 2003–2006 a major program of shallow seabed habitat assessment has been undertaken in Australian coastal seas. As part of the Coastal Water Habitat Mapping (CWHM) project of the national Cooperative Research Centre for Coastal Zone, Estuary and Waterway Management, research into optimal use of acoustic techniques for habitat assessment has been undertaken. Echo sounder, side scan, and multibeam acoustic systems have been used and evaluated in this program. Multibeam systems have been primarily employed with particular attention being given to combining topography data with associated measures of backscatter intensity. The emphasis on shallow waters, generally 50-m depth or less, and high-frequency multibeam systems with up to 240 beams has provided data sets with relatively high levels of spatial resolution. Measures of backscatter variation with incident angle have been incorporated into the interpretation process and a new angular dependence correction algorithm developed for production of backscatter imagery. The processing techniques developed in the CWHM project have been evaluated using towed video data for a variety of tropical and temperate coastal environments around Australia.