MORPHOMETRIC ANALYSIS OF ICEBERG SCOURS USING MULTIBEAM SONAR BATHYMETRY DATA, EASTERN CANADIAN CONTINENTAL SHELf

摘要

This paper presents a newly developed methodology for mapping and morphometric analysis of iceberg scour features using multibeam sonar bathymetry data, with selected examples from study areas on the eastern Canadian continental shelf. The method involves scour digitization by the interpreter, followed by automated cross-sectional and planimetric data extraction and analysis, and database archiving. The analysis is based on multibeam-generated Digital Elevation Models (DEMs) and acoustic backscatter data. A key feature of the analysis method is the ability to define a pre-scour, 'undisturbed' seabed surface based on seabed slope and curvature threshold criteria, which is used as a reference datum for measurement of cross-sectional scour dimensions. The seabed DEM data are filtered to remove data points with high slope and curvature values representing 'disturbed' seabed (scour troughs and berms), yielding a reference datum for scour measurement. The high spatial density of morphometric measurements provided by multibeam sonar data allows robust statistical analysis of scour parameters for input to iceberg grounding and risk models.