Les barrages sont à l’origine de modifications significatives du régime hydrologique, de la température de l’eau et des flux biologiques et biogéochimiques. C’est le cas des barrages de Vezins et de la Roche qui Boit, présents sur le cours principal de la Sélune, et d’autres plus petits obstacles qui fragmentent le bassin versant de la Sélune. Cette couche représente les barrages hydroélectriques de la Sélune, avec les batiments associés, en lien avec la production électrique. La géométrie de ces polygones est issue de plusieurs sources : BD Topo, OpenStreetMap (de 2019), complétée par photointerprétation. Des informations extraites du livre « Quand les rivières reprennent leur cours – Notes sur l’effacement de barrages et de seuils, sur la Sélune et ailleurs » ont été ajoutées pour décrire l'état (en service ou arasé), la nature et les caractérisques physiques de ces barrages.

The removal of the dams on the Sélune River is the subject of a scientific program launched in 2012, in which environmental parameters are monitored in order to provide real feedback on this restoration operation. In 2019, a data observatory was set up to collect and process these parameters (biotic and abiotic). The data acquired from 2012 and at least until 2027 will be centralized using an information system (IS) called SISelune. SISelune aims to assist scientists associated with the Sélune program and make the data accessible to all. Watercourses are linear hydrographic entities, linked to a main place name and broken down into hydrographic sections. These watercourses are extracted from the Topage database covering the study area. Codes that can be used within the Sélune program have been added, as well as codes from the former hydrographic reference system (Carthage database).

Macrophytes are a group of aquatic plants. They are at the base of the food chain and can provide a habitat for many other species. As part of the Sélune Observatory, pilot stations have been set up along the main course of the Sélune, distributed from upstream to downstream of the hydroelectric dams. Three stations are located in the former reservoirs of the dams, while the other two, known as the reference stations, are outside the area of influence of the former dams (one downstream and the other upstream). At these stations, the aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. The parameters monitored are the specific composition and cover, at 8 stations in the main course located upstream, downstream and in the neolotic zones of the macrophyte communities. The monitoring frequency consists of one annual campaign for stations outside reservoirs (S0, S1 and S5) and two annual campaigns (spring/autumn) for neolotic stations (S2, S3.4, S4.1 and S6). The protocol used is the sampling protocol for macrophytes and bryophytes in accordance with standard NF T90-395 (October 2003), which defines the IBMR. The taxa are sampled for laboratory identification. This layer shows the location of the study sectors used for macrophyte monitoring, as well as the campaigns carried out and the mesology identified during these different campaigns.

Macrophytes are a group of aquatic plants. They are at the base of the food chain and can provide a habitat for many other species. The relative abundance of different species is used to calculate an environmental quality index (IBMR). As part of the Sélune observatory, pilot stations have been set up along the main course of the Sélune, distributed from upstream to downstream of the hydroelectric dams. Three stations are located in the former reservoirs of the dams, while the other two, known as reference stations, are outside the area of influence of the former dams (one downstream, the other upstream). At these stations, aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. The parameters monitored are specific composition and cover, at 8 stations in the main course, located upstream, downstream and in neolotic areas of macrophyte communities. The monitoring frequency consists of one annual campaign for stations outside reservoirs (S0, S1 and S5) and two annual campaigns (spring/autumn) for neolotic stations (S2, S3.4, S4.1 and S6). The protocol used is the sampling protocol for macrophytes and bryophytes in accordance with standard NF T90-395 (October 2003), which defines the IBMR. Taxa are sampled for laboratory identification. This layer gives the value of the IBMR and EQR (normalized) index at a station for a campaign, as well as information concerning the robustness of this index, the quantities of taxa used to calculate these indices and also information in terms of the proportion of major floristic groups (heterotrophs, algae, bryophytes, pteridophytes, helophytes, phanerogrames, floating vegetation and submerged vegetation).

The removal of the dams of the Sélune is the subject of a scientific programme initiated in 2012 in which environmental parameters are monitored in order to provide real feedback on this restoration operation. In 2019, a data observatory was set up to ensure the collection and processing of these parameters (biotic and abiotic). The data acquired from 2012 and at least until 2027 will be centralized through an information system (IS), called SISelune. SISelune aims to help scientists involved in the Sélune programme and make data accessible to all. The Sélune scientific programme has a reference system, composed of points. These points can be used by all program actors to more easily identify any location within the study area. The points are created along the rivers, with an approach "Point kilométrique" (every 100m, going from upstream to downstream). Each of these points has a unique code, corresponding to the association of the watercourse (designated by a short code) and the distance to the source or confluence. Since 2025, each of these points has also been characterized by its position in the watershed (downstream, upstream, ...) in relation to the zone determined by the former dams and their reservoirs, as well as their distance from the sea in 2 forms (LTM: Limite Transversale à la mer / Transverse Sea Limit and LSE: Limite Salure des eaux / Water salinity limit).

The opening of the dams should impact the functioning of Atlantic salmon populations migrating up the Sélune and its tributaries. Restoring the river's ecological continuity will alter population flows by allowing Atlantic salmon to migrate further upstream and downstream of the dams. The Atlantic salmon population is monitored at a network of stations covering the entire Sélune basin using an abundance index, which was carried out every two years before 2021 and annually since then. Field campaigns comply with the fishing protocol developed by INRAE and OFB. The aim of this method is to estimate the abundance of juvenile Atlantic salmon (Salmo salar) at a station (or sector). This protocol targets juveniles of the year (aged 0+) whose abundance reflects the renewal of generations within the population (or recruitment) and survival after the embryonic development phases under gravel and the first months of life in the open environment. Field campaigns are carried out by INRAE and the Manche d'Ille-et-Vilaine Federation for Fishing and the Protection of the Aquatic Environment (FDAPPMA50 and FDAPPMA35). This dataset provides the locations of these study sectors for IAS fishing sessions in the Sélune watershed by fishing session.

Macrophytes are a group of aquatic plants. They are at the base of the food chain and can provide a habitat for many other species. The relative abundance of different species is used to calculate an environmental quality index (IBMR). As part of the Sélune observatory, pilot stations have been set up along the main course of the Sélune, distributed from upstream to downstream of the hydroelectric dams. Three stations are located in the former reservoirs of the dams, while the other two, known as reference stations, are outside the area of influence of the former dams (one downstream, the other upstream). At these stations, aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. The parameters monitored are specific composition and cover, at 8 stations in the main course, located upstream, downstream and in neolotic areas of macrophyte communities. The monitoring frequency consists of one annual campaign for stations outside reservoirs (S0, S1 and S5) and two annual campaigns (spring/autumn) for neolotic stations (S2, S3.4, S4.1 and S6). The protocol used is the sampling protocol for macrophytes and bryophytes in accordance with standard NF T90-395 (October 2003), which defines the IBMR. Taxa are sampled for laboratory identification. This layer gives Taxon identification is based on version v17 of the TAXREF reference. The dataset is currently under embargo.

The re-establishment of the river continuum of the Sélune after the levelling of the dams will enable the colonization of the upstream part of the basin which was previously inaccessible to trout. As a result, monitoring of amphihaline fish populations on the Sélune is carried out on the main river and its tributaries, both upstream and downstream of the former dams. These enable us to understand the dynamics of these common trout populations before, during and after dam removal. Regarding the trouts, the inventory is carried out using the VIGITRUITE® protocol. This is a standardized protocol for estimating the abundance of juvenile trout (Salmo trutta) in rivers. It is based on sampling per unit effort, a unit fixed at 5 minutes of effective fishing, and thus delivers abundances in numbers of juveniles per 5 minutes. Abacuses for converting abundances into densities are available, and a guide to interpreting densities, from low to excellent, is proposed. Compared with traditional inventories, this protocol enables a smaller number of people to be mobilized in the field. The protocol applies to watercourses up to 8 m wide and never more than 60 cm deep. It has been validated on granite and limestone rivers in Brittany and Normandy. VIGITRUITE® specifically targets juveniles of the year (0+) and yearlings (1+). The 0+ abundance provides information on generation replacement (or recruitment), useful for population demographic monitoring. The abundance of 0+ and 1+ is also a reflection of the quality of the trutticole habitat, and of specific attacks on its integrity (pollution, sedimentation, fragmentation in particular). It is a diagnostic tool for trout populations and their river habitats. This protocol is applied in September of the years in question: every 2 years between 2012 and 2020, then every year from 2021 to 2027. The year 2020 is special because of the COVID. For more information on acquisition conditions, please refer to the Sélune biocenosis observatory reports, the links to which are provided in this document. This dataset provides juvenile trout abundance data (0+, 1+ and cumulative), by station and fishing session.

Continuous monitoring stations for hydrological, physical, chemical, and sedimentary parameters have been installed on the Sélune River as part of the scientific program to monitor the removal of the Sélune dams. Measurements have been taken at least hourly since 2014. Since 2019, these stations have been under the responsibility of the Sélune Observatory, which is in charge of monitoring environmental parameters (biotic and abiotic). The physical and chemical parameters measured at all stations include turbidity, water level, and conductivity. At some stations, pH and dissolved oxygen or chlorophyll concentration are also measured. This layer provides the corrected measurements from the hydrological measurement stations. This layer provides corrected measurements from the SIGNY, LA-ROCHE-QUI-BOIT, VIREY, and DORIERE (only until October 2020) hydrological measuring stations.

Continuous monitoring stations for hydrological, physical, chemical, and sedimentary parameters have been installed on the Sélune River as part of the scientific program to monitor the removal of the Sélune dams. Measurements have been taken at least hourly since 2014. Since 2019, these stations have been under the responsibility of the Sélune Observatory, which is in charge of monitoring environmental parameters (biotic and abiotic). The physical and chemical parameters measured at all stations include turbidity, water level, and conductivity. At some stations, pH and dissolved oxygen or chlorophyll concentration are also measured. This layer provides raw measurements from the SIGNY, LA-ROCHE-QUI-BOIT, VIREY, and DORIERE (only until October 2020) hydrological measuring stations.