LidarBathymetrie

LiDAR-Bathymetrie, or bathymetric lidar, is an airborne remote sensing method that uses laser pulses to measure shallow water depths by penetrating the water column and returning from the seabed, riverbed, or coastal features. It enables simultaneous collection of submerged bathymetry and land elevations, producing integrated coastal and estuarine maps.

The technique relies on a green laser, typically around 532 nm, which can penetrate clear water, and on a separate channel to capture surface returns. The sensor sends pulses to both the water surface and the bottom; the time of flight for the bottom return, corrected for water surface position and environmental effects, yields depth. Water properties such as clarity and turbidity affect penetration and accuracy.

Equipment includes airborne LiDAR systems mounted on aircraft or boats, with a green bathymetric laser, multi-return capability, and precise navigation. Many systems combine bathymetric and terrestrial LiDAR or integrate with imagery for co-registration. Depth ranges in clear coastal waters often extend to several tens of meters, with sub-meter to meter-scale horizontal resolution depending on flight altitude.

Data processing involves calibration, georeferencing, water-column removal, bottom detection, depth conversion, tide and refraction corrections, and integration with topographic data to produce bathymetric digital terrain models (DTMs) or hydrographic products.

Applications include coastal mapping, harbor and channel management, flood risk assessment, and habitat mapping. Benefits include rapid, large-area coverage and integration with topography; limitations include dependence on water clarity, surface conditions, and reduced accuracy with depth.