Hydrographic Zones — Guyana 2015 — BD Carthage

Circular No. 91-50 of 12 February 1991 on hydrographic codification and spatial identification of surface aquatic environments in metropolitan France defines the hydrographic zone as follows: “The whole French territory is divided into elementary zones called hydrographic zones. Their boundaries are based on those of the topographic watersheds (in whole or in part)”. A zone is a partition of a subsector that can include up to 10. It is entirely within a river basin boundary and serves, together with other elements, to delineate various programming or regulatory areas such as the Water Planning and Management Schemes, sensitive areas, 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 municipality is either fully included within a hydrographic zone or split between several zones. Different scenarios of the hydrographic area may exist: a — The main watercourse of the hydrographic zone has its source within the area: it is an upstream area whose contour corresponds to that of the topographic catchment area of the main stream at the exit point of the area. B — The hydrographic area is crossed by the main watercourse and the downstream pk is not 1000: it is an intermediate watershed, C — The hydrographic area is crossed by the main stream whose downstream point corresponds to pk 1000: this is the downstream area of the catchment area, D — The hydrographic area is on the shoreline. Three scenarios: * or it is a main stream that has its source in the area: this is then case (a), * or this downstream area is the last intermediate basin before the mouth of the main river: this is then case (c), * or the area includes a coastal line with the mouth of the coastal river and areas drained by “ruses” directly entering the sea, e — The area does not have surface discharge but nevertheless receives endoreic streams located upstream. The list of hydrographic areas shows two specific cases: — To avoid the creation of frontier hydrographic regions, five hydrographic zones on the border border with Italy or Spain (codes Y670 and Y680 corresponding to two ends upstream of the Po basin, S910, S911 and S912) have been linked to the coastal hydrographic regions (codes S and Y) of the basin districts on which they depend, — Although the hydrographic logic would require the zone U204 (sub-basin of the Jougnena belonging to the Rhine basin) to be attached to the Rhine-Meuse basin district, it is nevertheless attached to the district of Rhône-Méditerranée-Corse (Regional Region “Saône”) given the small size of this area and its remoteness from the Rhine-Meuse basin, — Although the hydrographic logic would require that the areas of sector D0 (Sambre basin in France) be allocated to region B (Bassin de la Meuse) they are administratively linked 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 operating abroad.