Hydrographic Areas — Metropolis 2017 — BD Carthage

Circular No 91-50 of 12 February 1991 on hydrographic coding and spatial identification of surface aquatic environments in metropolitan France defines the hydrographic zone as follows: &L' the entire French territory is divided into elementary zones called hydrographic zones. Their boundaries are based on those of topographical watersheds (in whole or in part)". A zone is a partition of & a subsector that can have up to 10. It is entirely within a river basin boundary and serves, along with other elements, for the delimitation of various programming or regulatory areas such as the Water Planning and Management Schemes, the sensitive areas, the water bodies mentioned in the European Framework Directive of 23 October 2000. A hydrographic area covers, in part or in whole, the territory of one or more municipalities. Conversely, the territory of ' a commune is either fully included within a hydrographic zone or split between several zones. Different scenarios of the river basin area may exist: a — The main water course of the hydrographic zone takes its source at the inside of the zone: C' is an upstream zone whose contour corresponds to that of the topographical watershed of the course of the main water at the exit point of the zone. B — The hydrographic area is crossed by the main watercourse and the downstream point pk; is not 1000: it is an intermediate watershed, C — The hydrographic area is crossed by the main watercourse whose downstream point corresponds to pk 1000: it is the downstream zone of the catchment area, D — The hydrographic area is on the edge of the coastline. Three scenarios: *or it is a main water course that has its source in the area: this is the case (a), * or this downstream area is the last intermediate basin before the mouth of the main river: it is then case c), * or the area includes a line of the coastline comprising the mouth of the coastal river and areas drained by &rus" throwing directly into the sea, e — The area has no surface flow but nevertheless receives endoreic water upstream. The list of river basin areas shows two specific cases: — To avoid the creation of border hydrographic regions, five hydrographic zones located on the borderline with Italy or #x27; Spain (codes Y670 and Y680 corresponding to two upstream ends of the Po basin, S910, S911 and S912) have been attached to the coastal hydrographic regions (codes S and Y) of the basin districts on which they depend, — Although the hydrographic logic would require that the zone U204 (sub-basin of the Jougnena basin belonging to the Rhine basin) be attached to the district of Rhin-Meuse basin, it is nevertheless attached to the electoral district of Rhône-Méditerranée-Corse (hydrographic region " Saône") given the small size of this area and its remoteness from the Rhine-Meuse basin, — Although the hydrographic logic would require the areas of sector D0 (Sambre Basin in France) to be assigned to Region B (Meuse Basin) they are administratively attached to the Artois Picardie Basin district in view of the remoteness of the Meuse and Sambre basins in France and the confluence of these two rivers which occurs abroad. __Origin__ Updated by l'IGN following requests from Agences de l'Water according to an annual cycle. The consolidated version is then sent to the Sandre __Partner organisations__ Ash, Agence de l'eau Adour-Garonne, Agence de l'eau Artois-Picardie, Agence de l'eau Loire-Bretagne, Agence de l'eau Rhine-Meuse, Agence de l'Rhone-Méditerrannée water and Corsica, Agence de l'eau Seine-Normandie __Links annexes__ * [see scenario d' geographical exchange of the hydrographic reference](http://www.sandre.eaufrance.fr/urn.php?urn=urn:sandre:scenario-d-echanges-geographique:eth:FRA:::ressource:1:) * [see the interactive dictionary on Sandre website](http://id.eaufrance.fr/ddd/ETH/2002-1#ZoneHydro) * [see Dictionary & Hydrographic Reference (ETH)"](http://www.sandre.eaufrance.fr/?urn=urn:sandre:notice:dictionnaire::theme:ETH:ressource:2002-1:::html) [See this page on geo.data.gouv.fr](https://geo.data.gouv.fr/fr/datasets/9dc8e89dab2d3a86e4d280b4ee209352b14981f9)