Airborne lidar bathymetry fires green laser pulses at 532 nm that reflect from both the water surface and the seabed; the delay between those returns gives depth after refraction and speed-of-light corrections. Many systems add an infrared pulse to fix the surface. It maps shallow, clear coastal water and surf zones quickly and without risk to boats, but turbidity limits it to roughly two to three times the Secchi depth.
ALB got everything inside the reef down to 25 metres, the launch only has to fill in the channel.
Also heard as
- airborne lidar bathymetry
- bathymetric lidar
Related terms
Bathymetry
The measured depth and shape of the seabed, or the work of measuring it.
MBES
Multibeam echo sounder: a sonar that measures a fan of depths across the track on every ping, covering a wide swath.
Coverage
The portion of the seabed actually measured or imaged by a survey, expressed as a percentage of the area.
Survey launch
A small survey boat fitted with sonar and positioning gear, often lowered from a mother ship for inshore work.