Case study:Restoration of the Bellegarde hydraulic annex and sediment recharge of the Ain River

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Location: 46° 0' 29", 5° 17' 57"
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Project overview

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Status Complete
Project web site
Themes Environmental flows and water resources, Habitat and biodiversity, Hydromorphology
Country France
Main contact forename Elisabeth
Main contact surname Favre
Main contact user ID
Contact organisation Conservatoire régional des espaces naturels Rhône-Alpes (CREN)
Contact organisation web site http://www.cren-rhonealpes.fr/
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
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Project summary

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The Ain river flows for 195 km from its source in the Jura Mountains to its confluence with the Rhone, upstream of Lyon. Throughout its length, it presents very rich aquatic ecosystems. Between 1945 and 1980, the river Ain was modified: from a braided riverbed to a single channel. This change is accelerated by the development of hydroelectric plants, bank protections, dikes ... thereby reducing the intake of solid materials from upstream and banks. Due to the deficiency of solid materials, the incision is strongly stepped. Thus, the incision causes paving of the riverbed downstream of the structures and led to the disconnection of the hydraulic annexes with the alluvial groundwater. The lower Ain valley is included in one of the Natura 2000 site and the restoration of the hydraulic annexes of the Ain River is carried out with a Life Project. The Bellegarde hydraulic annex (a pond) is chosen because it is located in an area with a low flow dynamic and where the river is paved. The restoration of this pond may also allow a sediment recharge of the river. The first step is the identification of the functional parts of the pond and the parts to restore. Cleaning and milling operations are carried out on a hectare. A lowering of the bottom of the pond is also realized. The materials removed, 18 000 m3 of pebbles, are directly redeposited in the riverbed. These will be taken by the current. The 6700 m3 of fine materials are scattered on the river banks.

Monitoring surveys and results

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The rewetting of the entire pond (3.2 hectares) is effective. The reconnection with the groundwater has been rapidly produced. Due to the slow response of the different compartments, some monitoring results are still unknown.

Lessons learnt

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Image gallery


The Bellegarde pond, before restoration: heavily wooded and almost dry.
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Catchment and subcatchment

Catchment

River basin district Rhône - Méditerranée
River basin Rhône-Mediterranean

Subcatchment

River name Ain
Area category
Area (km2)
Maximum altitude category
Maximum altitude (m)
Dominant geology
Ecoregion Western Highlands
Dominant land cover
Waterbody ID



Site

Name Bellegarde
WFD water body codes FRDR484
WFD (national) typology
WFD water body name
Pre-project morphology Single channel
Reference morphology Braided
Desired post project morphology
Heavily modified water body No
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
Average bankfull channel width category
Average bankfull channel width (m) 15
15 m
0.015 km
1,500 cm
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s) 122
122 m³/s
122,000 l/s
Average channel gradient category
Average channel gradient 0.13
Average unit stream power (W/m2) 10369.268
10,369.268 W/m²


Project background

Reach length directly affected (m) 1450
1,450 m
1.45 km
145,000 cm
Project started
Works started 2006/11/02
Works completed 2006/11/25
Project completed
Total cost category
Total cost (k€) 59.7
59.7 k€
59,700 €
Benefit to cost ratio
Funding sources Union européenne 50 %, État (20, 5 %), Agence de l’eau (10 %), conseil régional (10 %), conseil général (7, 6 %), fédération des chasseurs de l’Ain et syndicat de la basse vallée de l’Ain (1, 9 %).

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design 8.5
8.5 k€
8,500 €
syndicat de la basse vallée de l’Ain (SBVA)
Stakeholder engagement and communication
Works and works supervision 56.25
56.25 k€
56,250 €
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure
Hydromorphology Connection to groundwaters, Substrate conditions
Biology Fish, Invertebrates
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
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
[[]] Yes Yes No No No Awaiting results
Connection to groundwaters No Yes No No No Improvement

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish No No No No No Awaiting results

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
[[]] Yes Yes No No No Awaiting results

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Riparian vegetation Yes Yes No No No Improvement


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://www.bassevalleedelain.com

Supplementary Information

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