Case study:Remeandering of the Mardereau stream at Sorigny

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Location: 47° 14' 28.04" N, 0° 41' 47.85" E
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Project overview

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Status Complete
Project web site
Themes Flood risk management, Habitat and biodiversity, Hydromorphology, Social benefits, Water quality
Country France
Main contact forename David
Main contact surname Laurendeau
Main contact user ID
Contact organisation Syndicat intercommunal d’aménagement de la vallée de l’Indre (SAVI)
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
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Project summary

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The Mardereau stream is a small tributary of the Indre river. The catchment is dominated by crops and the intensification of agricultural pressures since 1941 has resulted in the creation of an extensive drainage network of and the disappearance of wetland habitats. Soil sealing in the watershed is increasing due to the proximity of the town of Tours. As a result the flood risk management issue is very relevant. At Sorigny the Mardereau was straightened, dredged and, in the upstream part, cemented. Under the leadership of the Syndicat Intercommunal d’Aménagement de la Vallée de l’Indre (SAVI), a pilot restoration project has been realized. Works carried out included remeandering and plantation of riparian vegetation, together with some local biongeneering measures.

Monitoring surveys and results

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Lessons learnt

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Image gallery


The Mardereau stream before restoration, in January 2009.
The Mardereau stream after restoration, in April 2009.
Students participating in plantation of ripisylve, in February 2009.
The Mardereau stream in August 2009, four months after restoration. Riparian vegetation has recolonized the riverbanks.
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Catchment and subcatchment

Catchment

River basin district Loire-Bretagne
River basin Loire

Subcatchment

River name Mardereau
Area category
Area (km2) 8.58.5 km² <br />850 ha <br />
Maximum altitude category
Maximum altitude (m)
Dominant geology
Ecoregion Western Plains
Dominant land cover Intensive agriculture (arable)
Waterbody ID



Site

Name Sorigny
WFD water body codes FRGR2158
WFD (national) typology
WFD water body name
Pre-project morphology Single channel
Reference morphology Actively meandering
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest
Dominant hydrology
Dominant substrate
River corridor land use Intensive agriculture (arable)
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
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 230230 m <br />0.23 km <br />23,000 cm <br />
Project started
Works started 2009/03/01
Works completed 2009/03/31
Project completed
Total cost category
Total cost (k€) 1919 k€ <br />19,000 € <br />
Benefit to cost ratio
Funding sources 100 % Syndicat intercommunal d’aménagement de la vallée de l’Indre

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision 1919 k€ <br />19,000 € <br /> 100 % Syndicat intercommunal d’aménagement de la vallée de l’Indre
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure canalization of the stream
Hydromorphology Channel pattern/planform
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Riverbank revegetation, Introducing stones
Floodplain / River corridor
Planform / Channel pattern Re-meandering
Other
Non-structural measures
Management interventions
Social measures (incl. engagement) Engagement with schools, Student Education
Other Local support


Monitoring

Hydromorphological quality elements

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

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Invertebrates Yes Yes No No No
Phytoplankton No Yes No No No

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
Public opinion No Yes No No No


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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