The DTM is a compilation of multibeam echosounder surveys acquired in 2013. The resolution is 1/64 arc-minutes (~30m). Surveys are located on the Capbreton Submarine Canyon (France) with depths from -4.7m to -344.9m. Depths are referenced to the Lowest Astronomical Tide and the coordinates are expressed into the WGS84 reference frame. The surveys which compose the DTM are S201306500-09 and S201306500-11. Data and metadata associated to these surveys are available on the website http://diffusion.shom.fr/pro/lots-bathy.html. The DTM is not to be used for navigation.

The regional bathymetric Atlantic – Channel – North-Sea DTM has a resolution of 0.001° (~111m). Its geographic coverage includes the Bay of Biscay, the English Channel and a part of the North Sea. The DTM extends from the coast to the continental slope (about of 4800m deep). This DTM is produced in the framework of the HOMONIM project which aims at improving operational forecast capabilities for the national coastal flood warning system. This DTM is offered openly on the Shom diffusion website (http://diffusion.shom.fr/produits/bathymetrie/mnt-facade-atl-homonim.html). http://dx.doi.org/10.17183/MNT_ATL100m_HOMONIM_WGS84

Shom is the national referent for the level of the sea in situ on all areas under French jurisdiction. In this capacity, he assures under the acronym REFMAR different coordination functions in the collection and dissemination of public data related to water level observations, in order to promote their use in multiple applications within the framework of international recommendations.

Litto3D provides 3D, continuous sea-land description of French coastal areas. Data is acquired by airborne topo-bathymetric LiDARs. Litto3D products come in 3D point clouds and digital terrain models formats. The product "Litto3D - Nouvelle-Aquitaine 2020-2022" covers the geographical area from the Charente-Maritime to the Spanish border. For the maritime part, the data produced by Shom extend offshore down to signal extinction, approximatively 20 depth when environmental conditions are optimal. On land, the data are truncated at a limit that ensures the product retain its coastal character.

Bathymetric datasets are an extraction of surveys belonging to the Shom public database. For depth up to 50m, the vertical precision of soundings varies from 30cm to 1m and the horizontal precision varies from 1 to 20m. In deep ocean, the vertical precision is mainly around 1 or 2% of the bottom depth. It is sometimes more, it depends on the technology used. The data are referenced to ZH which is assimilated to LAT. Data are corrected for sound velocity variations. <br /> October 27 2025 version

The update of the coastal topo-bathymetric DEM of the Pertuis charentais at a resolution of 0.0002° (~ 20 m) was carried out in the third phase of the HOMONIM project. The DEM extends from the terrestrial domain to about 60 meters depth over all the pertuis (pertuis Breton, pertuis d’Antioche and pertuis of Maumusson). The DEM is intended to be implemented in hydrodynamic models in order to produce forecasts as accurate as possible of water heights and sea states at the coast to improve the relevance of the Wave-Submergence Vigilance. This product is available with either the Lowest Astronomic Tide (LAT) or the Mean Sea Level (MSL) as a vertical reference.

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.

Bathymetric datasets are an extraction of surveys belonging to the Shom public database. For depth up to 50m, the vertical precision of soundings varies from 30cm to 1m and the horizontal precision varies from 1 to 20m. In deep ocean, the vertical precision is mainly around 1 or 2% of the bottom depth. It is sometimes more, it depends on the technology used. The data are referenced to ZH which is assimilated to LAT. Data are corrected for sound velocity variations. <br /> October 27 2025 version

Impulsive or transient sounds of short duration and of high intensity constitute one of the criteria for defining good ecological status for descriptor 11 relating to the pressure of noise generated by human activities within the framework of the MSFD (D11C1). Good ecological status for sound energy is achieved when the risks of acoustic disturbance, excess mortality from sound exposure and reduction in communication distances of mysticetes are cumulatively low or moderate. For this, the spatial distribution, the temporal extent and the acoustic levels of the sources of anthropogenic impulsive sound must not exceed the levels harmful to the populations of marine animals. These criteria are evaluated at the scale of the marine sub-region for the “English Channel and North Sea”, “Celtic Seas” and “Western Mediterranean” regions; and at the scale of the "North" and "South" subdivisions in the "Bay of Biscay" sub-region. One of the indicators selected for the evaluation of criterion D11C1 is the spatial distribution of impulse emissions (D11C1.2). The pressures considered for the evaluation of the criterion are: acoustic emissions from air guns; acoustic emissions from impulsive sources other than air guns; emissions from non-impulsive (transient) sources; underwater explosions; emissions due to pile driving. The data used for the calculation of this indicator are declarative emissions data traced by the operators of the activities generating impulsive noise.

Geographic information layer including the Transverse limit of the sea - mainland France, French Guiana, Martinique and Guadeloupe. This layer must be considered as an initial version to be validated locally by the competent services. Shom actively seeks out any information which could complete and improve the precision of this layer. The streams and rivers listed correspond to those mentioned in the applicable regulations and/or by a competent Government service. An inventory of existing legal and geographic information was drawn up prior to production in the form of an enquiry targeting services during the second half of 2014. The source legal text and a summary of digital conversion processes is available for each boundary proposed.Updated july 2018