Initiated in 2012, an agreement between INRA, AESN, AFB, FNPF, the government and EDF secures the scientific project until 2027. The studies are organized in three thematic areas:
- territorial dynamics and trajectories
- fluvial dynamics and water quality
- biocenosis, functioning and evolution
Territorial dynamics and trajectories
Main interrogations: How do inhabitants, valley, river and lakes’ users see the ecological restoration project of the Sélune River? Which criteria are decisive for its success? Which changes can be expected for agriculture and landscapes?
Landscape evolution is monitored through a photographic landscape observatory since 2013. It gathers 90 observation points scattered across the basin, photographed each season. The “Syndicat mixte du basin de la Sélune” (Mixed union of the Sélune basin) is a partner in these efforts.
On a wider scale, remote sensing (satellite imagery, drone and Lidar images) monitors landscape evolution since the 50s.
Investigations on agricultural practices, users’ representations of the territory combined with inhabitants’ speeches complete the analysis to understand bonds between agriculture and landscape in the Sélune valley but also to better constrain fears and expectations in respect to this restoration project.
Finally, the rising debate made of blockages, interruptions and struggles issued from the start of the dismantlement governance project was carefully analyzed. This conflict was compared to similar operations in northwestern France and on the eastern coast of the United States. Success or failure factors of such operations were therefore enlightened.
For more information: https://selune.hypotheses.org/
Fluvial dynamics and water quality
Dams are physical barriers to water flow, sediments transport and water chemistry. It is therefore necessary to have a good knowledge of these flows to understand changes associated to dams’ removal.
Particularly, flow’s origin and velocity should be assessed to better constrain the transfer processes, the role of hydrodynamic conditions and the seasonal or exceptional (floods) variability. Flow rate, turbidity and element contents are monitored thanks to automatic sensors spread up and downstream of the Sélune’s dams.
Finally, consequences on shape and stability of the riverbed are also part of the main interrogations following dams’ removal. Geomorphological dynamics and sediments transport are mainly followed through LIDAR imagery and electronic tracing (PIT-tag) of coarse elements.
These parameters are subject to a very close follow-up within the Sélune laboratory.
Biocenosis, functioning and evolution
The purpose is to understand biological processes in ecosystems restoration following dams’ removal. Aquatic photosynthetic organisms (phytoplankton, biofilm and macrophytes), aquatic macro-invertebrate (including crayfish), diadromous fishes migrating between rivers and ocean, and riparian vegetation are particularly scrutinized.
The spatial (up- and downstream of the dams, rivers and riverbanks) and temporal recolonization dynamics are subject to thorough monitoring within the Sélune Observatory.
The return of migrating species in the Sélune (salmo – Salmo salar, marine lampreys – Petromyzon marinus and fluviatile lampreys – Lampetra fluviatilis, shad Alosa sp. and eels Anguilla anguilla) shoud be spectacular while invasive species dispersal (such as crayfish Pacifastacus leniusculus) constitutes a key issue. Follow-ups are done through electrofishing, trapping, environmental DNA, acoustic cameras and radio tracking. Their distribution are monitored through electric fishing, trapping, environmental DNA, acoustic video cameras and radio tracking.
Finally, relationships between living entities, from microorganisms to fishes, are monitored. The goal is to identify complex mechanisms involving aquatic or riparian ecological communities’ reorganization after dams’ destruction.