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.

Litto3D marine part is a unique and continuous land-sea database which can provide 3D models of the shape and location of french coastal terrain. Surveys are carried out by airborne lidar bathymetry over the sea side and airborne lidar topography over the land side up to 400m inland. Litto3D marine part digital models are available in two formats: a set of 3D points and a qualified terrain mesh. The product "Litto3D marine part - Nouvelle-Aquitaine 2020-2022" covers the geographical area from the Sèvre Niortaise to the Spanish border.

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.

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

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..

The Histolitt® coastline corresponds to the high tide line with an astronomic tidal coefficient of 120 and in normal weather conditions (no sea breeze and no low pressure systems likely to raise sea level). The Histolitt® coastline models this theoretical input as a series of 2D polylines. In mainland France, it is recommended to use the land-sea limit product which replaces this Histolitt® coastline. There is no land-sea limit in the French overseas areas for the moment.

<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.

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.

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.