Mapping of the bathymetry of the bay of Lorient

This mapping is the result of a collaboration with the Musée-Sousmarine, which allowed Lorient Agglomeration to model the Rade de Lorient accurately. Christophe Cérino, Doctor and Research Engineer, Director of the Research House at the University of South Brittany is the permanent head of operation, responsible for the implementation of cartographic resources. The measurements available can be compiled with those of ports and beaches and thus form an overall background. Bathymetric data are used by technicians to calculate sediment accumulation and location in harbours or estimate the decline in sand levels on beaches. The material used by the Underwater Museum also makes it possible to determine the nature of the seabed, which is complementary to our surveys. Areas can be drawn precisely for fine expertise. Sediment movements are important in the rade. This mapping is intended to be evolutionary. **Collection context** Olex software platform. Map system allowing the 2D and 3D generation of the relief of underwater backgrounds. The Underwater Museum is equipped with differential equipment whose real-time accuracy is in the order of the meter and capable of simultaneously receiving the transmission of 14 satellites for optimal point positioning. The work ladder consists of one square metre cells. When the vessel navigates and passes within the geographical framework of a cell, the OLEX system checks the quality of the positioning information as well as that of the probe before recording the bathymetric coast, thus ensuring maximum reliability. The more a maritime area is covered, the more comprehensive the mapping becomes. **Collection method** Star Arvor type 250 As (7.5 m — 230 hp) * 1 Simrad ES60 Prospector * 1 Simrad probe EA400 * 1 Combined Transducer 38/200 KHz * 1 Sidescan 200 KHz Transducer * 1 differential GPS (WAAS/EGNOS) Thales Mobile Mapper * 1 differential GPS (WAAS/EGNOS) Furuno GP37 Pro * 2 VHF For more information, see [the metadata on the Isogeo catalog](https://open.isogeo.com/s/0bd17a2a330842c68ec4a412d1df6824/AiCyPK6W8fg012l-vHV0s5tPry5b0/r/845e04d21fb14b9d86a3694a652be411).