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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.
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.
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.
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.
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.
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.
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
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).
"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)…