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Gravity dam

Updated on 06/09/2018
Définition
Sens technique
A rather old dam, made of a block of solid material (concrete or masonry) heavy enough to withstand the water pressure.
Source
according to the French Committee of Dams and Reservoirs

Impoundment dam

Updated on 06/09/2018
Définition
Sens technique
Structure built for the storage of water for replenishing low water levels or supplying channels.
Source
according to Voies navigables de France (French Waterways)

Underground dam

Updated on 06/09/2018
Définition
Sens technique
A groundwater impoundment structure built across underground water channels. The underground dams are built in the sub-soil. They store water in geological formations, retain groundwater and require pumping facilities to make water usable.
Source
according to the Japanese Ministry of the Environment

Arch dam

Updated on 06/09/2018
Définition
Sens technique
Dam with a complex design, which is thin and resistant to the hydraulic pressure by bracing the rocky sides of a valley. These dams are particularly suitable for narrow valleys.
Source
according to the French Committee of Dams and Reservoirs

Hydrological balance

Updated on 06/09/2018
Définition
Sens technique
Accounting of the changes in water resources (stream flows, groundwater level, effective rainfall) of an area (for example a catchment area) based on meteorological, piezometric or hydrological information.
Source
according to AFB

River hydraulics

Updated on 06/09/2018
Définition
Sens technique
Branch of Hydraulics which mainly deals with the free surface flow of water in natural or artificial streams (e.g. canals). River hydraulics is necessary for the design, development and construction of hydraulic structures, such as dikes, sills and weirs.
Source
according to Wikipedia

Torrential hydraulics

Updated on 06/09/2018
Définition
Sens technique
Branch of hydraulics relating to flows in areas with steep slopes.
Source
according to Water torrents & mountain rivers

Hydrological profile

Updated on 06/09/2018
Définition
Sens technique
Methodology, based on the study of stream flows, which allows assessing the water inflow that is specific to any section of the river.
Source
according to Michel Deshaies (geographer)

Green algae

Updated on 27/02/2019
Définition
Sens commun

Chlorophyllous aquatic plant having no leaves, no roots, no vessels, no flowers, no seeds, whose main photosynthetic pigments are chlorophylls a and b. As the name suggests, they are usually green in color.

Source
d'après dictionnaire Larousse
Sens technique

Algae phylum whose sometimes exclusive major pigment is chlorophyll β, associated with carotene and xanthophyll. Their only reproductive organs are sporocysts and gametocysts. Their plastids elaborate starch as in the Phanerogamous. It includes three classes: Chlorophyceae, Zygophyceae and Charophyceae.

Source
d'après dictionnaire encyclopédique des sciences de la nature et de la biodiversité

Watercourses fragmentation

Updated on 13/07/2018
Définition
Sens technique

Fragmentation of a watercourse into several fragments, due to natural or artificial obstacles (i.e. sills, dams, weirs, etc), which may lead to a disruption into the ecological continuity, preventing the free movement of species or the smooth sediments flow.

Source
according to AFB and IOWater

Headward erosion

Updated on 20/07/2020
Définition
Sens technique

Phénomène d’érosion qui se propage de l’aval vers l’amont d’un cours d’eau : dans le cas d’un déficit sédimentaire sur un tronçon aval, le cours d’eau, pour retrouver sa pente d’équilibre, va prélever en amont les sédiments nécessaires. Cette dynamique de rééquilibrage, souvent causée par la rectification du cours d’eau ou l’extraction trop importante de granulats dans son lit, se poursuit tant que le cours d’eau n’a pas retrouvé une pente d'équilibre, et peut provoquer un phénomène d‘incision. S'oppose à l'érosion progressive.

Source
d'après Jura Natura Services

Fluvial dynamics

Updated on 04/07/2018
Définition
Sens technique
Part of potamology (branch of hydrology that deals with rivers and their regime) which deals with the flow in watercourses and the impact on the bed material of the forces that it brings into play.
Source
According to Rhine-Meuse Water Agency

Flood control

Updated on 13/07/2018
Définition
Sens technique
Action of limiting a peak flow, either by storage in a specific reservoir, or by expanding the flood plain.
Source
According to Rhine-Meuse Water Agency

Database on thematic mapping of the Water Agencies

Updated on 13/07/2018
Définition
Sens technique

A set of geographic layers presenting hydrographic objects for the French territory. This includes cutting the territory into "hydrographic areas" (river basins) as well as watercourses and bodies of water, and the codification of these objects. The Carthage database (Database on thematic mapping of the Water Agencies) was developed by IGN, the Water Agencies and the Ministry for the Environment and is based on the hydrographic layer of the CARTO database. The National Service for Water Data and Reference-dataset Management (Sandre) disseminates this geo-referenced dataset through its data catalogue and cartographic Atlas.

Source
According to the Ministry for the Environment

Curage vieux fonds, vieux bords

Updated on 13/07/2018
Définition
Sens technique
French expression used in old regulations and local practices that specify the conditions and frequency with which the cleaning obligation must be fulfilled by every riverside resident of a non-state-owned watercourse by article 98 of the Rural Code. It is a routine maintenance of the stream by the riverside resident or his rightful owner. Sometimes called "vifs fonds - vieux bords".
Source
According to the Rural Code

Hydrographic sector

Updated on 13/07/2018
Définition
Sens technique
Part of a hydrographic region and the second order of the hydrographic division of the French territory. This hydrographic division indeed includes all four parts of the French territory hierarchized according to increasing hydrographic areas: Hydrographic Region (1st order), hydrographic Sector (2nd order), hydrographic Sub-sector (3rd order), hydrographic area (4th order). A sector is divided into a maximum of 10 sub-sectors and a sub-sector is cut into a maximum of 10 hydrographic areas.
Source
According to AFB and IOWater

Hydrographic sub-sector

Updated on 13/07/2018
Définition
Sens technique
Part of a hydrographic sector and the third order of the hydrographic division of the French territory. This hydrographic division indeed includes all four parts of the French territory hierarchized according to increasing hydrographic areas: Hydrographic Region (1st order), hydrographic Sector (2nd order), hydrographic Sub-sector (3rd order), hydrographic area (4th order). A sector is divided into a maximum of 10 sub-sectors and a sub-sector is cut into a maximum of 10 hydrographic areas.
Source
According to AFB and IOWater

Hydrographic area

Updated on 13/07/2018
Définition
Sens technique
The hydrographic division includes all four parts of the French territory hierarchized according to increasing drainage systems: Hydrographic Region (1st order), hydrographic Sector (2nd order), hydrographic Sub-sector (3rd order), hydrographic area (4th order). A sector is cut into a maximum of 10 sub-sectors and a sub-sector is cut into a maximum of 10 hydrographic areas.
Source
According to AFB and IOWater

Biotope

Updated on 13/07/2018
Définition
Sens technique

Space characterized by climate, geographical, physical, morphological and geological factors, ... in constant or cyclic equilibrium and occupied by organisms that live in specific association (living communities). This is the non-living component (abiotic) of the ecosystem.

Source
According to the Ministry for the Environment and AFB

Assigned flow

Updated on 13/07/2018
Définition
Sens technique

According to the Water Act of 1992, "when hydraulic development works, other than those conceded or authorized and intended or resulting in the regulation of the flow of a non-State owned watercourse or for increasing its flow during low-flow periods, all or part of the artificial

Source
According to the Ministry for the Environment and AFB

Annual flow

Updated on 13/07/2018
Définition
Sens technique
Average flow over a year: it is most often obtained by adding the average daily water flows of the year and by dividing the result by the number of days in the year.
Source
According to the Ministry for the Environment and AFB

Reference or basic low water flow

Updated on 13/07/2018
Définition
Sens technique

Legal reference flow, defined as the monthly low-flow recurring every five years (or frequency of 1/5, i.e. occurring one year in five), known by the acronym QMNA 5 (frequency 1/5).

Source
According to the Ministry for the Environment and AFB

Low water flow

Updated on 06/09/2018
Définition
Sens technique
Minimum stream flow calculated in a given time step during low water periods. For a given year, we will talk about: daily low water flow, low water flow on n consecutive days, monthly low flow - average daily flow in a low-flow month (QMNA). With several years of observation, the statistical processing of series of low flows allows calculating a low- flow frequency. For example, the five-year low water flow (or QMNA 5) is a monthly flow that occurs on average once every five years. The QMNA 5 is the reference low water flow for the implementation of the water policy.
Source
according to the Ministry of the Environment and AFB

Warning level (or threshold) flow

Updated on 13/07/2018
Définition
Sens technique

"Threshold" value of the flow that triggers the first restrictions for some activities. These measures are taken at the initiative of the prefectural authority in connection with a crisis cell and in accordance with a crisis plan. Below this threshold, one of the functions (or activities) is compromised. To partially restore this function, it is necessary to limit temporarily another: withdrawal or discharge (first restriction measures)…

Source
According to the Ministry for the Environment and AFB