This study provides an initial global estimate of the extreme water level values along the French metropolitan coastline. These results are to be refined locally with all available data and knowledge. The method used is based on a statistical analysis of the tide gauge observations available in the ports. It does not take into account wave observations. The results between ports are obtained by an interpolation method. The study produces at the reference ports the statistical estimates: - extreme values of high water surge in the Channel and Atlantic; - extreme values of water level for the whole of Metropolitan France. And a set of statistical estimation maps of extreme water level values along the coastline. The estimates provided go up to the 1,000-year return period. In view of the duration of observations used at the ports, the user must check whether estimates with a return period of more than 50 or 100 years are still valid 50 or 100 years still make sense.

This product includes the boundaries of tidal zones for French Channel, Atlantic and Mediterranean coasts in shapefile format. Information on the characteristics of tidal zones is available as part of the "Maritime Altimetric Reference Values" product.

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.

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : tidal range for mean spring tides for average atmospheric conditions..

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : maximal tidal range for average atmospheric conditions..

<strong>This data is not up to date with the order dated 30 August 2021 amending the order dated 23 November 1987 on ship safety, which now raises the limit for category 4 ships to 5 miles from the nearest coast.</strong> The navigation category allocated to a ship is indicated on its shipping license, together with any applicable restrictions. This limit was produced by Shom in application of section II.14 of article 1 of decree no. 84-810 amended on 30 August 1984. Navigation categories are defined in article 110.10 of the rules appended to the order of 23 November 1987 on shipping safety.

Limits defining ship classes based on their assigned operating maritime zones. These limits were produced by CEREMA in application of section II.14 of article 1 of decree no. 200945 amended on 30 August 1984. Navigation categories are defined in article 223.2 of the rules appended to the order of 23 November 1987 on shipping safety.

The “World Seabed Sediment Map” product contains geo-referenced digital data, describing the nature of the sediment encountered in different seas and oceans of the world. The objects are all surface areas and the description of an object includes in particular the nature of the sediment including rock-type bottoms.

The « Maritime Spatial Planning » product contains 2D areas vector objects representing the extent of the maritime spatial plan (« MSP Spatial Plan » layer) and the extent of the corresponding vocation zones (« MSP Zoning Element » layer), defined in each strategic façade document.

Wave forecasting models allow the representation of sea states based on a spectral resolution at the global scale or at the scale of ocean basins. This code calculates the evolution of the sea state by decomposing it into a wave spectrum that propagates in different directions and with different periods. During the propagation, the wave energy is increased or decreased by the effects of wind, breaking waves and energy exchanges between the different components. The wave forecasts available on data.shom.fr are calculated with 2 different types of models: MFWAM for the offshore domain (resolution from 0.5° to 0.1°) and Wavewatch III ® (WW3) for the coastal domain (resolution from 2' to 200m). MFWAM is a sea state forecasting model (wind wave and swell) derived from the third generation WAM code (WAMDI Group, 1988). Wavewatch III ® (WW3) is developed in a collaboration between the United States Weather Service (NOAA/NCEP), Shom, the University of Darmstadt in Germany, and other partners. The forecasts published on data.shom.fr are issued from the parameterization carried out and optimized by the Shom and Météo-France within the framework of the Homonim project (national coastal flood/wave/storm warning system).