Multidisciplinary study of the Selune river restoration following the removal of two large dams
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SELUNE |
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Context and Issues
By disrupting ecological continuity, dams cause significant changes to the hydrological and thermal regimes, as well as the biological and biogeochemical flows of rivers. Among the various existing solutions, dam removal is proving to be an effective tool for restoring these continuities. However, dam removal can also cause ecological disturbances, the impact of which is difficult to predict.
This is the case of the Sélune, a coastal river in Normandy, on which two hydroelectric dams, the La-Roche-qui-Boit dam (16m high) and the Vezins dam (36m high), have now been removed. Their removal has been the subject of many political, ecological and social debates. It finally began in 2019 and was completed in 2022-2023. Removing these dams will reconnect 60 km of the Sélune and the entire upstream part of its catchment area. This corresponds to a total length of 975 km, if the river's many tributaries are taken into account.
Cases of restoration by removing dams are still relatively rare. Around the world, only a few restoration operations have been the subject of scientific monitoring. But still too few of them take into account the assessment of the initial state of the system. Yet knowledge of the initial state is essential for understanding the changes brought about by the restoration operation and their mechanisms at different scales. Furthermore, most of the scientific monitoring carried out focuses on a single aspect of restoration, whether biological, morphological, landscape or societal.
Since 2012, INRAE has been coordinating a multidisciplinary scientific programme to understand the mechanisms of this restoration throughout the Sélune catchment.
Objectives
The scientific programme on the Sélune began in 2012 and will continue until 2027. It is a multidisciplinary and multi-institutional research programme. Researchers are monitoring the ecological restoration of the river, in order to characterise the physical, chemical and biological processes involved and to support the societal changes that are about to take place. The scales of study are multiple, cascading from the landscape to chemical elements. The aim of this programme is to provide a comprehensive feedback and recommendations for river managers in the restoration of watercourses following the removal of large dams.
The aims of the programme are to:
- To analyse the mechanisms of ecological restoration of the river in this region in transition.
- To characterise the effects of restoring continuity to a valley by removing obstacles.
- To identify the societal and ecological costs and benefits associated with the return of a river ecosystem.
- To provide feedback on the fate of ageing dams worldwide.
- To make this pilot site a scientific benchmark.
Methods
This scientific program is multidisciplinary. It is organised around three main themes:
- Territorial dynamics and trajectories
- River dynamics and water quality
- Biocenoses, their functioning and evolution
The scientific program was developed in several stages, inseparable from the dam removal works and the political and local decisions relative to the dams. It is divided into 3 phases:
- The assessment phase - pre-dam decommissioning (2012-2018)
- The removal phase - dismantling the dams (2019-2022)
- The restoration phase - post-dam dismantling (2023-2027)
The scientific programme is based around various research projects, as well as an observatory. The Sélune observatory monitors biotic and abiotic parameters in the Sélune catchment area.
Results
Until now, scientists have worked on understanding how the river works with the dams. Current research also focuses on anticipating the changes brought about by the removal of dams. From 2023, research will focus on understanding how the river functions without the dams. By comparing these different phases, it will be possible to characterise the effects of dam removal and to identify the societal and ecological costs and benefits associated with the return of a river ecosystem.
Publications from the Sélune project are available on HAL: https://hal.inrae.fr/SELUNE
Scientific partners
- INRAE U3E (Unité Expérimentale d'Ecologie et d'Ecotoxicologie Aquatiques), Rennes, France
- UMR SAS (Sol, Agro et hydrosystème, Spatialisation), Rennes
- UMR ECOBIO (Ecosystèmes, Biodiversité et Evolution), CNRS, Université Rennes 1, Rennes
- UMR LETG (Littoral Environnement, Télédétection, Géomatique), CNRS, Université Rennes 2, Rennes
- UMR LAVUE Université Paris Ouest Nanterre
- UMR EVS (Environnement Ville Société), ENS de Lyon
- UMR BOREA (Laboratoire de biologie des organismes et des écosystèmes aquatiques), MNHN, Dinard
- Station marine de Dinard, CRESCO (Centre de Recherche et d’Enseignement sur les Systèmes Côtiers), MNHN-IFREMER, Dinard
- UMR LGP (Laboratoire de Géographie Physique : Environnements Quaternaires et Actuels), Université Paris Est Créteil Val de Marne
- UMR GEOSCIENCES, CNRS, Université de Rennes 1, Rennes
- UMR THEMA (Laboratoire Théoriser et Modéliser pour Aménager), Université Franche Comté
- UMR BAGAP (Biodiversité, Agroécologie et Aménagement du Paysage), Rennes
- UMR CARRTEL Thonon
- UMR COSTEL Université Rennes 2 (OSUR)
- UMR GEOPHEN Université de Caen
- UMR ECOBIOP (Ecologie Comportementale et Biologie des Populations de Poissons), Saint-Pée-sur-Nivelle
- ARMINES- Centre de Géosciences
- BRGM
- Asconit Consultants
- Ethnozi (consulting firm)
Publications issued from the project
RAULT, P. ACOU, A. AZAM, D. BARDONNET, A. BUORO, M. EVANNO, G. FEUNTEUN, E. LASNE, E. LAUNEY, S. NEVOUX, M. PREVOST, E. REVEILLAC, E RIVOT, E. ROBIN, E. ROUSSEL, J.-M. TRANCART, T. PETIT, E.J. (2019) .Dispersion et (re)colonisation du cours de la Selune et de ses affluents
ROUSSEL, J.-M. (2019) .Introductive talk of the International conference on dam removal
ROUSSEL, J.-M. COUDREUSE, J. FRAISSE, S. GORZERINO, C. HUTEAU, D. PAILLISSON, J.-M. PANNARD, A. PETIT, E.J. PISCART, C. POUPELIN, M. (2019) .Dam removal and aquatic ecosystem restoration: a food web perspective
FRAISSE, S. BAGLINIERE, J.-L. ROUSSEL, J.-M. (2019) .Dam Removal on the Selune River: the scientific program
ROUSSEL, J.-M. FRAISSE, S. BAGLINIERE, J.-L. (2019) .Dam removal on Selune River, France
FRAISSE, S. BAGLINIERE, J.-L. ROUSSEL, J.-M. (2018) .Effacement des barrages sur la Selune : Presentation d?un programme scientifique interdisciplinaire de suivi sur le long terme
FRAISSE, S. BAGLINIERE, J.-L. ROUSSEL, J.-M. (2018) .Dam removal on the Selune River (France): Implementation of the ecological restoration project
FRAISSE, S. BAGLINIERE, J.-L. ROUSSEL, J.-M. (2018) .Monitoring program of the dam removal on the Selune River (France)
THOMAS, O. GERMAINE, M. -A. (2018) .La restauration de la continuite ecologique des cours d?eau et la peche de loisir : heritages, changements et enjeux
PRONOST, Y. OURY, Y. RAVOT, C. BERNEZ, I. (2018) .Suivi de la recolonisation vegetale spontanee des berges remaniees de la Selune (Normandie, France) avant l?arasement de deux grands barrages : elaboration d?un protocole pour la mise en place de l?observatoire ORSER
RAVOT, C. LASLIER, M. WAYMEL, J. MULLER, I. HUBERT-MOY, L. DUFOUR, S. (2018) .Dynamiques vegetales jeunes sur les vases exondees du lac de Vezins (Manche) avant demantelement de grands barrages : potentialites d?une restauration ecologique passive et conservatoire d?une vallee renaissante
RAVOT, C. BERNEZ, I. (2018) .Renaturation des cours d?eau actuellement ennoyes (cours principal et affluents) et de leurs marges - Le fleuve Selune renaissant : dynamiques vegetales des vases exondees & potentialites de restauration ecologique passive et conservatoire
RAVOT, C. LASLIER, M. MULLER, I. HUBERT-MOY, L. DUFOUR, S. BERNEZ, I. (2018) .New Selune River (Normandy, France) margins following large dam removal: ecological restoration perspectives considering the successional vegetation dynamics of alluvial deposits
RAVOT, C. LASLIER, M. MULLER, I. HUBERT-MOY, L. DUFOUR, S. LE COEUR, D. RODRIGUEZ GONZALES, P.M. (2018) .Supporting management decision-making in the dam-free Selune River project (France): Taxonomic and functional successional patterns
LASLIER, M. RAVOT, C. RODRIGUEZ GONZALES, P.M. BERNEZ, I. HUBERT-MOY, L. DUFOUR, S. (2018) .Early successional vegetation patterns of alluvial deposits following dam removal: a functional approach
RAVOT, C. CASTAY, L. ZERMENO-RODRIGUEZ, A. LASLIER, M. THENAIL, C. ALIGNIER, A. DUFOUR, S. BERNEZ, I. (2018) .Journee technique du Projet Seripage : Etat des lieux pre-demantelement (2015-2018)
CASTAY, L. RAVOT, C. ZERMENO-RODRIGUEZ, A. LEROY, D. ALIGNIER, A. LASLIER, M. DUFOUR, S. BERNEZ, I. THENAIL, C. (2018) .Restitution du Projet Seripage : Etat des lieux pre-demantelement (2017-2018)
FORGET, G. BAGLINIERE, J.-L. MARCHAND, F. RICHARD, A. NEVOUX, M. (2018) .A new method to estimate habitat potential for Atlantic salmon (<I>Salmo salar</I>): predicting the influence of dam removal on the Selune River (France) as a case study
PETIT, E.J. ACOU, A. AZAM, D. BARDONNET, A. BARLOY, D. BENNEVAULT, Y. BESNARD, A.-L. BOLLIET, V. COSTE, P. COUDREUSE, J. DAROUX, A. EVANNO, G. FEUNTEUN, E. FORGET, G. GUILLARD, J. HUCHET, E. HUTEAU, D. LASSALLE, G. LAUNEY, S. LE QUILLIEC, P. MACEL, N. MANICKI, A. MARCHAND, F. MARTIGNAC, F. NEVOUX, M. OGER, A. OMBREDANE, D. PAILLISSON, J.-M. POUPELIN, M. REVEILLAC, E RAULT, P. RIVES, J. FRAISSE, S. BAGLINIERE, J.-L. (2017) .Dispersion et (re)colonisation du cours de la Selune et de ses affluents
LE LAY, Y. -F. GERMAINE, M. -A. (2017) .Deconstruire ? L?exemple des barrages de la Selune (Manche)
GERMAINE, M. -A. LESPEZ, L. (2017) .The Failure of the Largest Project to Dismantle Hydroelectric Dams in Europe? (Selune River, France, 2009-2017)
FRAISSE, S. ROUSSEL, J.-M. BAGLINIERE, J.-L. (2016) .Dams? removal in the Selune River (France): Overview of the related long-term research program
BAGLINIERE, J.-L. (2016) .Opening speech
DAROUX, A. BOULENGER, C. NEVOUX, M. MARTIGNAC, F. GUILLARD, J. OMBREDANE, D. BAGLINIERE, J.-L. (2016) .Biocenoses aquatiques, volet 2. Dispersion et recolonisation. Programme Selune, Phase pre-arasement
FRAISSE, S. BAGLINIERE, J.-L. ROUSSEL, J.-M. (2016) .Dam removal on the Selune River (France): Implementation and scientific program
BAGLINIERE, J.-L. FRAISSE, S. ROUSSEL, J.-M. (2016) .Effacement des barrages sur la Selune (France) : un programme interdisciplinaire sur le long terme
FRAISSE, S. ROUSSEL, J.-M. BAGLINIERE, J.-L. (2016) .Les reseaux trophiques et le fonctionnement des cours d'eau, impact des principales perturbations
FRAISSE, S. ROUSSEL, J.-M. BAGLINIERE, J.-L. (2016) .Monitoring program of the dam removal on the Selune River (France)
CAPLAT, P. EDELAAR, P. DUDANIEC, R. Y. GREEN, A. J. OKAMURA, B. COTE, J. EKROOS, J. JONSSON, P. R. LONDAHL, J. TESSON, S. V. M. PETIT, E.J. (2016) .Looking beyond the mountain: dispersal barriers in a changing world
PETIT, E.J. ACOU, A. AZAM, D. BARDONNET, A. BARLOY, D. BENNEVAULT, Y. BESNARD, A.-L. BOLLIET, V. BOULENGER, C. COSTE, P. COUDREUSE, J. DAROUX, A. EVANNO, G. FEUNTEUN, E. FORGET, G. GUILLARD, J. HUCHET, E. HUTEAU, D. LASSALLE, G. LAUNEY, S. LE QUILLIEC, P. MACEL, N. MANICKI, A. MARCHAND, F. MARTIGNAC, F. NEVOUX, M. OGER, A. OMBREDANE, D. PAILLISSON, J.-M. POUPELIN, M. REVEILLAC, E RAULT, P. RIVES, J. FRAISSE, S. BAGLINIERE, J.-L. (2015) .Dispersion et (re)colonisation du cours de la Selune et de ses affluents
FRAISSE, S. ROUSSEL, J.-M. BAGLINIERE, J.-L. (2015) .Dams? Removal in the Selune River (France): A long-term scientific and interdisciplinary program
FRAISSE, S. ROUSSEL, J.-M. BAGLINIERE, J.-L. (2015) .The Dam Removal in the Selune River (France): A Long-Term Interdisciplinary Program from the Particle to the Watershed Scale
FORGET, G. NEVOUX, M. MARCHAND, F. RICHARD, A. BAGLINIERE, J.-L. (2015) .Evaluation of new habitat areas suitable for salmon in the Selune River (Lower-Normandy, France) after the removal of big dams
GERMAINE, M. -A. LESPEZ, L. (2014) .Le demantelement des barrages de la Selune (Manche). Des reseaux d?acteurs au projet de territoire ?
FORGET, G. NEVOUX, M. RICHARD, A. MARCHAND, F. BAGLINIERE, J.-L. (2014) .Estimation des capacites de production en saumon du Bassin de la Selune apres la suppression des deux barrages de Vezins et de La Roche-Qui-Boit
People involved
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AMILIEN Flavie, Technician Phone : +33 2 23 48 56 69 Email : flavie.amilien@inrae.fr |
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BARLOY Dominique, Scientist Phone : +33 2 23 48 54 83 Email : dominique.barloy@institut-agro.fr |
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BERNEZ Ivan, Scientist Phone : +33 2 23 48 55 41 Email : ivan.bernez@institut-agro.fr |
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BESNARD Anne-Laure, Technician Phone : +33 2 23 48 54 43 Email : anne-laure.besnard(at)inrae.fr |
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CHEVE Manuel, Ingénieur de Recherche Phone : +33 2 23 48 54 40 Email : manuel.cheve@inrae.fr |
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COUDREUSE Julie, Scientist Phone : +33 2 23 48 55 43 Email : julie.coudreuse@institut-agro.fr |
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DÉZERALD Olivier, Scientist Phone : +33 2 23 48 54 46 Email : olivier.dezerald@inrae.fr |
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EVANNO Guillaume, Scientist Phone : +33 2 23 48 54 45 Email : guillaume.evanno*at*inrae.fr |
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FORGET Guillaume, Technician Phone : +33 2 23 48 56 25 Email : guillaume.forget@inrae.fr |
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GORZERINO Caroline, Scientist Phone : +33 2 23 48 70 37 Email : caroline.gorzerino@inrae.fr |
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LANOE Elven, Email : elven.lanoe@institut-agro.fr |
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LASNE Emilien, Scientist Phone : + 33 2 23 48 54 44 Email : emilien.lasne@inrae.fr |
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LAUNEY Sophie, Scientist Phone : +33 2 23 48 52 35 Email : sophie.launey@inrae.fr |
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LE BERRE Thomas, Technician Phone : +33 2 23 48 59 23 Email : thomas.leberre@institut-agro.fr |
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LE BRIS Hervé, Scientist Phone : +33 2 23 48 59 28 Email : herve.le-bris@institut-agro.fr |
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MARTIGNAC François, Scientist Phone : +33 2 23 48 56 25 Email : francois.martignac@inrae.fr |
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MICHELOT Armand, Technician Phone : +33 2 23 48 52 37 Email : armand.michelot@inrae.fr |
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NEVOUX Marie, Scientist Phone : +33 2 23 48 50 15 Email : marie.nevoux@inrae.fr |
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PETIT Eric, Scientist Phone : + 33 2 23 48 70 36 Email : eric.petit@inrae.fr |
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QUÉMÉRÉ Erwan, Scientist Phone : +33 2 23 48 52 34 Email : erwan.quemere@inrae.fr |
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ROUSSEL Jean-Marc, Scientist Phone : +33 2 23 48 57 75 Email : jean-marc.roussel@inrae.fr |
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SOISSONS Laura, Scientist Phone : +33 2 23 48 54 40 Email : laura.soissons@inrae.fr |
Partners
Funding and Support
Agence de l'eau Seine Normandie (AESN)
Office Français de la Biodiversité (OFB)