Geomorphological analysis of the continental slope of the Bay of Biscay based on a 100m Data Terrain Model (DTM). This DTM is a synthesis of data acquired during sea surveys ZEE 1, ZEE 2, Sedimanche, Sedifan 1, Sedifan 2, EssNaut 2009, EssReson08, ValidOp, BOBGeo 1, BOBGeo 2, EssInf.

The geomorphological classification was developed for the geomorphological maps at a scale of 1.100,000 in the framework of the European FP7 project Coralfish (Bourillet  J-F. (Coord.), de Chambure L., Loubrieu B., 2012. Sur les traces des coraux d'eau froide du golfe de Gascogne. 8 cartes bathymorphologiques et géomorphologiques au 1/100.000. Cold water corals of the Bay of Biscay: 8 bathymorphological and geomorphological maps at 1:100,000., Editions Quae ed.).

It is base on geostatistical methods (de Chambure L., Bourillet, J-F., Bartel, C., 2013, Geomorphological classification in Bay of Biscay. Morpho-sedimentary mapping of the seabed in selected areas. Rapport INT. Ifremer-REM/GM/LES, 51p.).

Parameters, directly derived from the bathymetry (average depth, regional and local slope, …) allow the delimitation of the main physiographic sectors (megageoforms) such as shelf, slope and continental rise.

More complex parameters (drainage networks, thalwegs, weighted distance to the nearest thalweg) point out the geological structures : on the northern continental margin of theBay of Biscay, canyons are major elements of the shape of the sea floor (Bourillet et al., 2006). These parameters are used to differentiate canyons to interfluves areas.

Meso and macrogeoforms (km and 10xkm) are then classified within the canyon areas (river bed, flank, fall, gully, …) and the interfluve areas (crest, terrace, escarpment, …) and their connectivity is checked. These geoforms are also identified accordoing to the CMECS standard, Coastal and Marine Ecological Classification Standard (Madden, C, et al., 2008. Coastal and Marine Ecological classification Standard. NOAA and NatureServe. 77p. ; Greene, H.G., et al., 2007a. Construction of digital potential marine benthic habitat maps using a coded classification scheme and its application. In: B.J. Todd and H.G. Greene (eds.), Mapping the seafloor for habitat characterization. Geol. Assoc. Can. Spec. Pap. 47, pp. 141-155).

Shapefile was built from geostatistical interpretation DTM (Isatis software) using conversion tool "Raster to polygon" from ArcGIS software with the option "simplify polygons" ticks.