The underwater counterpart of topography: depths or seabed elevations measured by echo sounder, lidar or lead line and delivered as soundings, grids or contours. Bathymetry for charting is reduced to chart datum and judged against an accuracy standard; bathymetry for engineering or science may be referenced to the ellipsoid or a land levelling datum instead. The word covers both the data set and the activity.
Bathymetry from the last pass shows the channel toe has crept 15 metres east since the dredge left.
Also heard as
- bathy
- seabed topography
Related terms
Hydrographic survey
A systematic measurement of depths, seabed features and shoreline, made so the results can be charted and trusted by mariners.
Sounding
A single measured depth at a known position, or a depth figure printed on a chart.
Gridding
Turning millions of scattered soundings into a regular grid of depth values at a chosen cell size.
Bathy
Clipped form of bathymetry, used for depth data, depth surfaces or the depth-measuring part of a job.
MBES
Multibeam echo sounder: a sonar that measures a fan of depths across the track on every ping, covering a wide swath.