Ecology & Ecosystem health lab UMR 0985 INRA-Agrocampus Ouest, RENNES (FRANCE)

Dam Removal on the Sélune River: the Scientific program

Stéphane Fraisse, Jean Luc Baglinière & Jean-Marc Roussel

1- Biological fluxes

Diadromous Species on the Sélune River : Atlantic salmon European Eel Sea Trout River Lamprey Sea Lamprey Allis Shad Twait Shad

The reasons for dismantling

Forget et al., 2018

% of suitable habitat accessible for salmon in the Selune Basin

23%

77%

upstream

downstream

1993 Catastrophic emptying of the reservoirs

The reasons for dismantling

2- Sediment fluxes

3- Water quality

Bloom of toxic Cyanobacteria on the Sélune River

The reasons for dismantling

Bellmore et al. 2016

Increase in dam removals since the 90’s

Science and dam removals

70% of removed dams studied: no initial state

180 articles – 137 dams removed

Science and dam removals

0

50

100

150

sans données pré-effacement avec données avec pré-effacement

Without data before removal

With data before removal

42

19

1

13

1

9

0 29

14

3

2

0

1

0

3

high

Aquatic biocenosis

Landscape ecology Human Sciences

Hydrogeomorphology

Dams removed studied (n=137)

103

34 low

Science and dam removals

2012-2027: a 15 years scientific program

initial state restoration

2012 2018 2027 2021

removal

-> describe processes underlying the restoration of the river and its valley after dam removal -> provide scientific knowledge for future dam removal projects

Scientific comitee (External scientists)

Coordination group

Steering comitee (INRA, EDF, Water Agency, State,

Fishing national federation)

Scientists

2012-2027: a 15 years scientific program

The scientific program: 3 thematic areas + 1 observatory

Sélune River Observatory

Territorial dynamics and trajectories

Fluvial dynamics and water quality

Biocenosis Functioning and Evolution