Digital Surface Models (DSMs) of the study area surveyed by drone between June 2024 and March 2025. Each pixel contains the elevation value corresponding to the terrain at the time of the mission. These DSMs were generated from around 1,300 images (depending of the survey) acquired using the DJI Mavic 3E RTK drone, with a resolution of 3.2 cm/pixel. The surveyed area covers around 2.1 km². The campaign was conducted on the highest tides of each month. The drone acquisitions were carried out by Nicolas Lachaussée from the LIENSs UMR Drone Platform. Photogrammetric processing was performed by Natacha Volto (LIENSs) using Agisoft Metashape software. The vertical coordinate system is NGF IGN69. The vertical accuracy (RMSD ~ 3 cm), calculated using around 100 control points, randomly distributed across the study area. It is derived from the vertical difference for each control point between the value measured with the DGPS SP80 and the value extracted from the photogrammetry-generated DSM. These drone surveys were carried out as part of the thesis of Loës Le Goff Le Gourrierec supervised by Xavier Bertin.

The bathymetric DEM of the atlantic facade with a resolution of 0.001° (~ 100 m) was prepared as part of the HOMONIM project. It encompasses part of the North Sea, the Channel and the Bay of Biscay. Offshore, this DTM extends beyond the slope to approximately 4800 m depth. The DEM is designed to be used in hydrodynamic models in order to produce high-precision forecasts for coastal water levels and sea conditions and therefore improve the pertinence of the Waves-Submersion monitoring programme. This product is available with the Lowest Astronomic Tide (LAT) or the Mean Sea Level (MSL) as a vertical datum.