Case study:Restoration of the previous riverbed of the Dadon
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site|
|Themes||Habitat and biodiversity, Hydromorphology, Monitoring, Water quality|
|Main contact forename||Regis|
|Main contact surname||Talguen|
|Main contact user ID|
|Contact organisation||Syndicat mixte interdépartemental d’aménagement du Chéran|
|Contact organisation web site|
|Parent multi-site project|
| This is a parent project
encompassing the following
The Dadon is one of the last free flowing tributaries of the Lower Cheran. The Dadon watershed is concerned with two areas of industrial activities ( Alby -sur- Cheran and Rumilly) on its downstream sector, the rest of the watershed is occupied by farm land (55 % of the area ) and forest (13 % ).
The main pressure factors on the Dadon are the following:
- accidental pollutant releases in the industrial areas;
- organic pollution from farms and food processing factories;
- over-widening, straightening and embankment of its course, causing habitat depletion and lowering of the water table in its downstream stretch.
These factors greatly reduced the initially existing connections between the Dadon and the Cheran, thereby significantly lowering the ecological value of this naturally rich confluence area.
The main goals of the project were to restore the original riverbed of the Dadon, and to diversify flows and habitats, especially increasing water depths at low water flows. It was also aimed to stabilize banks and restore riparian vegetation. The works consisted of three steps:
- 2004 (involved length 350 m): rock sills and groynes to promote diversification of habitats; construction of vegetated log cribwalls, associated with geotextile to ensure bank stabilization (the restoration of a natural lateral dynamics was not part of project goals); creation of a narrower and meandering river bed;
- 2006 (involved length 475 m, downstream the previous stretch): the stream is returned in its original sinuous bed, as it was before the 90’s;
- 2009 (involved length 175 m, further downstream): introduction of blocks, stone sills, wooden groynes.
The works were carried out within the framework of the river contract brought by the Syndicat Mixte Interdépartemental d’Aménagement du Chéran (SMIAC). The local angling association strongly supported the action.
Monitoring surveys and results
The first results of the post-work monitoring are in overall terms encouraging. An improvement of the quality of habitats and of the macro-benthic population was demonstrated. The fish population shows some improvement, although the goal to restore a structured trout population is not yet met. From a social point of view, the operation was very well accepted.
Catchment and subcatchment
Select a catchment/subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos