Rivers — Métropole 2017 — CD Carthage

The main concept of hydrographic cutting is the hydrographic entity defined by Circular No. 91-50. The hydrographic entity is a natural or managed watercourse, a natural or managed arm, an artificial waterway (channel,...), a body of water or a coastal line. The nature of a hydrographic entity is not constant throughout the entity. For example, a natural stream can be built on a part. All these changes can be identified by distinguishing sub-miliosities on the entity. Hydrographic entities are broken down into two types: — linear hydrographic entities or streams, — surface hydrographic entities corresponding to water bodies and linear entities whose wide areas (above 50 metres) are represented by surface elements. A surface hydrographic entity can be crossed by a watercourse, which will be named the main stream. Each entity is identified by a unique generic code at national level. This 8-position alphanumeric code consists of dashes and characters. For example, a watercourse that crosses several zones or subsectors will have a generic code in the format of the following generic codes “V12-4000” or “R5--0420” (see below for the construction rule). In addition, a hydrographic entity has a so-called principal name. Construction rule for the generic hydrographic entity code: Each hydrographic entity shall be assigned a unique 3-digit number (5, 6 and 7 characters) for the medium and the hydrographic area(s) to which it belongs: this is the number of the hydrographic entity. A hydrographic entity belonging to several zones shall retain its entity number in all the areas concerned. Two hydrographic entities of the same medium belonging to two different sub-mills will have separate entity numbers. The first four characters of the generic code correspond to all invariant codes of the hydrographic zones, the rest of the characters being replaced by ‘-’ dashes. For example, the “Viveronne” watercourse has the entity number: 050 and for middle code: 0. This watercourse is located within a single hydrographic area: P737. His generic code is therefore: P7370500 The entity number of the river “La Dronne” is: 025 and for middle code: 0. This stream crosses several hydrographic areas (even several subsectors): P746,P744, P742, P70, P734, P731, P730, P716, P715, P714, P711, P710, P702, P701, P700. Of these codes, only the two characters are invariant. His generic code is therefore: P7--0250 Similarly, Garonne has as its entity number: 000 and for middle code: 0. This course crosses several hydrographic sectors (starting with “0”. Its generic code is: 0---00000