Case study:Restoration of the Charentonne in the Serquigny public garden

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Location: 49° 6' 32", 0° 42' 57"
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Project overview

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Status Complete
Project web site
Themes Habitat and biodiversity, Monitoring, Social benefits, Spatial planning
Country France
Main contact forename Franck
Main contact surname Perraudin
Main contact user ID
Contact organisation Mairie de Serquigny
Contact organisation web site
Partner organisations
Parent multi-site project
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encompassing the following
projects
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Project summary

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In Serquigny, the Charentonne is an urban river split into several strongly altered channels, due to hydropower production. The arm where the restoration works were carried out is fed by a weir upstream and underwent several dredging operations that left it overwidened, with a very low slope, morphologically homegeneous and affected by significant eutrophication. It is now located in a public garden of the town and within the Natura 2000 site "Risle, Guiel, Charentonne". The weir was restored in order to ensure a minimum flow of 300 L/s and a fish pass was installed. Accumulated fine sediments were extracted and used to create vegetated terraces, protected with bioengineerng techniques; a narrower, low flow channel was recreated, with higher slope.

Monitoring surveys and results

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Lessons learnt

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Catchment and subcatchment

Catchment

River basin district Seine-Normandie
River basin

Subcatchment

River name Charentonne
Area category 100 - 1000 km²
Area (km2) 513 km²
51,300 ha
Maximum altitude category
Maximum altitude (m)
Dominant geology
Ecoregion
Dominant land cover
Waterbody ID



Site

Name Serquigny public garden
WFD water body codes FRH61-0400
WFD (national) typology HER1-9 / HER2-57
WFD water body name
Pre-project morphology High width:depth
Reference morphology
Desired post project morphology
Heavily modified water body
National/international site designation EU - Special Area of Conservation
Local/regional site designations
Protected species present
Invasive species present
Species of interest
Dominant hydrology Artificially regulated
Dominant substrate
River corridor land use
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) 0.529
0.529 m³/s
529 l/s
Average channel gradient category
Average channel gradient 0.002619
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 230 m
0.23 km
23,000 cm
Project started 2001/01/01
Works started 2005/09/01
Works completed 2006/03/01
Project completed
Total cost category 100 - 500 k€
Total cost (k€)
Benefit to cost ratio
Funding sources General Council of the Eure, Agency of Seine-Normandy Water

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design 100 - 500 k€ General council of Eure and Lafosse &Fils SARL Bertrand Morandi
Stakeholder engagement and communication Agency of Seine-Normandy Water Franck Perraudin
Works and works supervision
Post-project management and maintenance
Monitoring 1 - 10 k€ 6892 k€
6,892,000 €



Reasons for river restoration

Mitigation of a pressure Riparian development
Hydromorphology Channel pattern/planform, Flow velocities, Structure & condition of riparian zones
Biology Invertebrates: Abundance
Physico-chemical
Other reasons for the project Landscape enhancement, Bank erosion


Measures

Structural measures
Bank/bed modifications Coir rolls, Bank reprofiling
Floodplain / River corridor Riparian planting, Protect/restore riparian zone
Planform / Channel pattern Re-meandering
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

Biological quality elements

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

Physico-chemical quality elements

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

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



Additional documents and videos


Additional links and references

Link Description
http://www.restauration.georiv.fr/resources/charentonne cs.pdf Description in the French database GeoRiv (in French)

Supplementary Information

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