Case study:Restoration of the surface flows of two temporary tributaries of the upstream Clauge

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Location: 47° 5' 39", 5° 43' 15"
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Project overview

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Status Complete
Project web site
Themes
Country France
Main contact forename Vincent
Main contact surname Pietra
Main contact user ID
Contact organisation Office National de Forêts
Contact organisation web site
Partner organisations
Parent multi-site project

Case_study:LIFE

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encompassing the following
projects
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Project summary

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The Sommière du Moulin rivulet and the Verne Fendue rivulet are temporary tributaries of the upstream Clauge. The River Clauge flows over 35 kilometres before joining the River Doubs. For 70% of its length, it crosses the Forêt de Chaux. The forest’s hydrographic network includes 460 km of streams, only a tenth of which are permanently fed. In 1950, foresters started draining, straightening and cleaning out around a hundred kilometres of rivers in the forest of Chaux, with a view to cleaning up these plots. The rapid removal of high water levels then caused major regressive erosion. The streams cut deeper channels and the river habitats became homogenised, leading to reduced crayfish populations. Since the 1970s, the drying out of the river stream system has been observed and the limits at which the flows are permanent have moved several hundred metres downstream and has been observed a tendency towards dieback, especially in oak trees. Part of the Chaux forest is included in the Natura 2000 site. This site was chosen for a project to reconstitute water reserves. The original meandering bed was restored by eliminating the straight bed via a series of watertight “plugs”. At the same time, a narrow, shallow and sinuous furrow was dug in order to initiate the meandering course, which will only be completed when the original course and the connection with the downstream meander are no longer visible. This “groove” only acts as a guide in order to channel the flow away from the straight channel: therefore, it is essential for it to be smaller than the supposed dimensions of the meandering bed. In the medium term, the straight bed segments and remaining ditches should be partially obliterated by the accumulation of organic matter (woody debris and leaves). In order to encourage this natural process, the removal of debris, jams and blockages from the stream beds, and even any maintenance of the riverside vegetation, are prohibited.

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Lessons learnt

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Image gallery


The straight bed of a tributary of the Clauge in 2005, prior to the remeandering works.
A tributary of the Clauge in January 2009 after the remeandering works.
Example of a watertight plug used to eliminate the straight bed which will be fi lled in naturally and progressively (June 2009).
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Catchment and subcatchment

Catchment

River basin district France-Comté
River basin Clauge

Subcatchment

River name Clauge
Area category
Area (km2)
Maximum altitude category
Maximum altitude (m)
Dominant geology
Ecoregion Central Highlands
Dominant land cover Woodland
Waterbody ID



Site

Name Morvan Regional Natural Park
WFD water body codes FRDR621
WFD (national) typology
WFD water body name
Pre-project morphology Entrenched
Reference morphology Sinuous
Desired post project morphology
Heavily modified water body true
National/international site designation
Local/regional site designations
Protected species present
Invasive species present
Species of interest
Dominant hydrology Quick run-off, Groundwater, Ephemeral
Dominant substrate
River corridor land use Woodland
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient 00:01
":01" can not be assigned to a declared number type with value 0.
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 3000 m
3 km
300,000 cm
Project started 2005/01/01
Works started 2007/10/01
Works completed 2008/01/01
Project completed
Total cost category 50 - 100 k€
Total cost (k€) 100 k€
100,000 €
Benefit to cost ratio
Funding sources Regional Council of Burgundy, Water Agency of the Rhone, Mediterranean Region, Corsica Region, Seine-Normandy Water Region, EU LIFE Programme

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design Université de Franche-Comté
Stakeholder engagement and communication
Works and works supervision 50 - 100 k€ 100 k€
100,000 €
ONEMA
Post-project management and maintenance ONEMA
Monitoring Université of France-Compté



Reasons for river restoration

Mitigation of a pressure
Hydromorphology Channel pattern/planform, Connection to groundwaters, Flow velocities, Substrate conditions
Biology Fish: Abundance, Fish: Age structure, Invertebrates: Taxonomic composition
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern Re-meandering, Re-meandering of tributaries
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Connection to groundwaters Yes Yes Yes Improvement

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish: Species composition Yes Yes Improvement
Invertebrates: Taxonomic composition Yes Yes Improvement

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



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Additional links and references

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Supplementary Information

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