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.

A flow obstruction is a water-related structure that causes a change in surface water flow (in thalwegs, minor and major river beds, and marine inundation zones). Only artificial obstructions (resulting from human activity) are taken into account. The data presented is taken from the ObstEcoul_FXX data layer published by SANDRE, spatially restricted to the Sélune watershed. The data retrieved was updated on 07/30/2024 from the above-mentioned feed and reprocessed to complete the type of obstacle with a “nature” field representing an aggregation of the types identified on the following values: “Dam”, “Spout”, “Dike”, “Bridge”, ‘Weir’ and “Not specified”. The aggregation implemented to populate the “nature” field is as follows: 1/ retrieval of the types of obstacles present in the watershed (source data field “CdTypeOuvr”). 2/ Retrieve the associated labels in the SANDRE reference: https://api.sandre.eaufrance.fr/referentiels/v1/nsa/284.csv?outputSchema=SANDREv3.1 3/ Filter these labels to populate the new “nature” field: - if the label contains “dam” then ‘nature’ is initialized to “Dam” - if the label contains “buse” (pipe), then “nature” is initialized to ‘Buse’ - if the label contains “digue” (dyke), then “nature” is initialized to “Digue” - if the label contains “pont” (bridge), then ‘nature’ is initialized to “Pont” - if the label contains “weir,” then “nature” is initialized to ‘Weir’ - if the label contains “not specified” (initially empty code), then “nature” is initialized to “Not specified” The other fields offered in the dataset are taken from the original SANDRE feed but have been renamed. The correspondence is provided in the associated data dictionary.

This project assesses the impact of restoring connectivity between fish populations following the removal of dams on the Sélune River. It is based on the calculation of a genetic fragmentation index for five fish species. Data: - Genetic analysis and F-index

The opening of the dams should impact the functioning of Atlantic salmon populations migrating up the Sélune River and its tributaries. Restoring the river's ecological continuity will alter population flows by allowing amphihaline sea trout to migrate further upstream and native trout to move downstream and upstream of the dams. The trout population is monitored at a network of stations covering the entire Sélune basin using an abundance index, which is carried out every two years before 2021 and every year 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 FDAAPPMA35). This dataset provides individual biometric data on Atlantic salmon caught during PAS fishing sessions in the Sélune watershed, by station and by fishing session.

In a nutshell: This research project focuses on the social and geographical dimensions of the ecological restoration of the Sélune River. Its objective is to assess the current state of the landscapes, land uses, and practices in the Sélune Valley (and more specifically in the gorge section) prior to the removal of the dams, and then to monitor the changes brought about by the removal: the state of both material transformations (land use, practices, visitor traffic) and conceptual transformations (perceptions, discourse) of the territory in order to assess the impacts of this project and thereby measure its success from the users’ perspective (quality of life, regional development, practices, etc.) to understand, using the example of the Sélune, the difficulties in gaining acceptance and ownership of such a project by various local stakeholders, as well as the challenges related to its definition and implementation. Methods used: surveys, questionnaires, analysis of the local press, photography Data: - A collection of photographs (~40) covering the entire Sélune Valley to track changes in the landscape - Historical photographs and postcards. Photographs will be annotated and geotagged - Inventory of land uses (fishing, recreation, lodging, etc.), analysis of visitor traffic in the gorges, and mapping - Semi-structured interviews will be conducted with representatives of user groups (to gather their opinions) - Text analysis (using Alceste or WordMapper software) of transcribed interviews - Collection of residents’ opinions and assessment of their satisfaction with the project - Corpus of articles published in the regional daily press to track the history of reactions - Collection of information disseminated via other media platforms such as blogs, forums, and websites by various stakeholder groups, particularly fishermen, environmentalists, and opponents of the clearing - Codification of the corpus followed by a lexical and semantic analysis using the TXM platform

This project aims to develop and apply a non-invasive method for monitoring migratory fish flows in the Sélune River. The development of this method is based on the analysis of images and videos taken by a hydroacoustic camera positioned in the watercourse.

In partnership with ANR Reppaval, the Syndicat Mixte du bassin de la Sélune has begun implementing a photographic observatory of the landscapes of the Sélune basin. This is a photographic itinerary consisting of viewpoints spread across the entire territory, where photographs will be taken regularly. The aim is to monitor changes in the landscape, particularly in relation to the Sélune restoration project. The layer shows the location of the sites on the photographic itinerary that are directly affected by the Sélune restoration work: lakes and dams.