Watercourse

Section of a stream of a few hundred metres to several kilometres. A reach change can be defined by the confluence of a tributary, changes in the morphology of the bed or of the valley or by changes in riverside vegetation, these variables reflecting changes in hydrology, chemical composition of water and disturbance regime.

Ratio between the total length of the watercourse in a river basin and the surface area of the latter. Drainage density is expressed in km/km2.

Statistics on characteristic flows. We can express the value of the classified flow not exceeded over n days per year on the average (DCNn) or the value of the classified flow exceeded over n days per year (DCXn).

Stream which discharges to the downstream part of a river basin the waters of a lake or of any other wetland.

Average flow over a year: it is most often obtained by adding the average daily flows of the year and by dividing the result by the number of days in the year.

Constitutive metrics of the Standardized Global Biological Index (IBGN), revealing the sensitivity of aquatic invertebrates to pollution (mainly organic).

All stagnant and running waters on the ground and all underground waters, and located upstream of the baseline used for the delimitation of territorial waters.

Identifier of a hydrographic structure, which can be a natural or developed watercourse, or a natural or developed section of a river, a man-made waterway (channel, etc), a body of water or a shoreline.

Hydraulic structure fed by water withdrawals from watercourses or bodies of water and mainly intended for navigation, drainage, irrigation or flow regulation.

Group of multispecies fish.