Hydrology

Mean annual discharge calculated over a period of observation long enough to be representative of the measured or reconstructed flow rates. It is frequently referred to as inter-annual module or module. It allows characterizing the flow of a "mean" year.

Imagery of the movement of ocean water generated by the effect of the rotation of the Earth. Some currents move on the surface, when the transported water is hot (as in the "Gulf Stream" in particular), or deep, when water is cold (e.g. the "Arctic and Antarctic" currents).

Movement of an oceanic water body.

Current caused by the movement of water volumes during the tidal cycle.

Mass of solids passing through a given cross section of a watercourse per time unit. The sediment discharge includes dissolved matters, suspended solids and riverbed materials. These materials are moved in the riverbed according to different transport laws: thrust, suspension, saltation. Sediment discharge and liquid flow are the two main variables of river dynamics.

Full filling up of the riverbed. The bankfull discharge is responsible for the formation and dynamics of flow facies and morphological alterations of the watercourse. It is the liquid flow for which the transported sediment discharge is maximal. We thus speak of morphogenetic flow. For many streams the bankfull discharge is a 1 to 3 year

Volume of water passing through a cross section of a watercourse per time unit. The flow rates of watercourses are expressed in m3/s with at least three significant figures (e.g. 1.92 m3/s, 19.2 m3/s, 192 m3/s) or for small streams in l/s. The national HYDRO database stores measurements of water levels coming from 3,500 measuring stations (including 2,400 that are currently in service) and used to calculate instantaneous, daily and monthly flow rates in a large number of French streams. Liquid flow and sediment discharge are the two main variables of river dynamics.

Phenomenon characterized by a more or less abrupt rise in the level of a watercourse, related to a flow growth. Flood is not always an overflow of the riverbed. Floods are also characterized by their return period: the five-year flood (frequency one year out of 5 - Return period 5), the ten-year flood (frequency one year out of 10 - Return period 10), the hundred-year flood (frequency, one year out of 100 - return period 100). Seasonal floods are natural phenomena. They are essential to maintaining the diversity of water systems and services provided by nature.

Describes a set of intersecting channels in a wide floodplain, or a delta, well endowed with all kinds of distributaries and cut-offs separated by shoals. The term, borrowed from the medical language, is used in hydrology only as an adjective: we indeed speak of an anastomosed river

All materials (pebbles, gravel, sand) deposited by running water in floodplains, especially during floods.