Bathymetry is the study and mapping of sea floor topography. It involves obtaining measurements of the depth of the ocean and is equivalent to mapping the topography on land.
Such measurements can be made using:
- Multibeam (swath) echosounders
- Airborne laser measurements (LADS)
- Derived depths from satellite remote sensing
- Singlebeam echosounders
The full releasable multibeam dataset held by Geoscience Australia and gridded at 50m resolution is available for download.
Combining these different data sources and by digitising pre-existing hydrographic charts Geoscience Australia has produced Australian Bathymetry and Topography Grid, June 2009 at a spatial resolution of 250m.
The other major datasets are multibeam and sidescan backscatter which represent the intensity and amplitude of reflected acoustic signals from the sea floor resulting in an image of its physical reflectance and scattering characteristics. These patterns can be used to discriminate rocky, sand, rough and smooth habitat types and are thus useful in mapping benthic biodiversity.
Bathymetry has been used extensively by Geoscience Australia's Law of the Sea Project to determine the foot of slope of Australia's continental shelf, which, in turn, has been used to determine Australia's extended continental shelf. Knowledge about the location of near-surface seamounts and reefs is useful also for the Australian Hydrographic Service to chart shipping hazards.
Bathymetry is used by engineering companies to site undersea cables, oil rigs and sea floor pipelines. The data may be used also for more specialised activities such as identifying the extent of man-made bio-hazards or for locating material which have escaped onto, or sunk to, the sea floor. Australia's fishing industry also use bathymetric data to identify possible locations for deep sea fishing.
Bathymetric data gathered by Geoscience Australia have been used for other purposes such as tsunami and wave-surge modelling.