Case study:Restoration of the river continuity on the Touques Basin

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Location: 49° 20' 36.31" N, 0° 6' 4.60" E

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Project overview

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Status	In progress
Project web site
Themes	Flood risk management, Habitat and biodiversity, Hydromorphology
Country	France
Main contact forename	Yannick
Main contact surname	Salaville
Main contact user ID
Contact organisation	Fédération de pêche du Calvados
Contact organisation web site	http://www.federation-peche14.fr/
Partner organisations	Direction départementale de l’agriculture et de la forêt (DDT), conseil supérieur de la pêche (now National Agency for Water and Aquatic Environments - Onema)
Parent multi-site project
This is a parent project encompassing the following projects	No

Restoration of free movement of migratory fish in the basin of the Touques between 1980 and 2009 (Arnaud Richard, Onema)

Project summary

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Several actions are performed to restore river continuity. Obstacles (weirs, sluices, dams) are opened, removed or fitted with fish passes.

Before the first fishway on the Calonne in 1982, some fifteen or so obstacles in the Touques basin had already been dismantled or opened to facilitate flood evacuation. Almost 30 years on, 71 other obstacles have been redeveloped, i.e.:

• 33 weirs removed, lowered or opened including the removal of the Lisieux flap gate dam (implementation: 2007, project owner: commune of Lisieux - see the corresponding example from the collection).

• 38 weirs equipped with fish passes including a multi-species fishway on the Breuil-en-Auge dam (implementation: 1999, project owner: Fishing federation of Calvados) and the development of 4 fish passes on the Cirieux (implementation: 2008, project owner: commune of Saint-Désir)

As progress has been made, grants received by project owners have supported this programme: The Ministry of the Environment, Conseil supérieur de la pêche (CSP - now Onema), the départements of Calvados, Orne and Eure, the fishing federations of Calvados and Orne, European funds. Currently: the Seine-Normandie and the Region of Basse-Normandie water agency

Monitoring surveys and results

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Counting of sea trout travelling upstream at Breuilen-Auge has been carried out since 2001. This monitoring is implemented under an agreement with the owner of the dam and of the fishway.

Reproduction areas accessible to sea trout have increased sharply, thanks to improvements works carried out over the past 30 years. The proportion of accessible surfaces thus increased from 15% before 1982 to 86% in 2009. The sea trout travelling upstream monitored at the Breuil-en-Auge fishway represented 2,500 fish in 2001 and more than 6,000 in 2008, a figure confirmed in 2009 with over 5,500 sea trout. As the monitoring station was located upstream to many tributaries, the current Touques stock is therefore now 10,000 sea trout, making it not only the number one river in France for sea trout but also one of the best in all of Europe. These very good results are accompanied by a significant rise in fishing tourism.

The scale of these actions and their results make the Touques basin a benchmark for continuity in the Seine-Normandie basin.

The Touques axis is completely open to migration, but there are still a dozen or so more obstacles upstream of the tributaries. There are several projects under way. The most penalizing obstacle lies in the middle part of the Calonne. This obstacle, devoid of fish passes despite the regulatory obligations, neutralises the efforts already made upstream in the Eure département due both to the obstruction of upstream fish migration but also damage caused by the turbine on fish returning to the sea.

Lessons learnt

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Image gallery

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Orville dam on the upper Touques before and after its removal (Arnaud Richard, Onema).

Breuil-en-Auge fishway (Arnaud Richard, Onema).

Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name WFD water body codes FRHR275 and FRHR277 FRHR276, FRHR279, FRHR278 WFD (national) typology WFD water body name Pre-project morphology Reference morphology 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 10 - 50 m Average bankfull channel width (m) 1515 m <br />0.015 km <br />1,500 cm <br /> Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category 1 - 10 m³/s Mean annual discharge (m3/s) 99 m³/s <br />9,000 l/s <br /> Average channel gradient category 0.001 - 0.01 Average channel gradient 0.003 Average unit stream power (W/m2) 17.652617.653 W/m² <br /> Project background Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed Total cost category 1000 - 5000 k€ Total cost (k€) 37003,700 k€ <br />3,700,000 € <br /> Benefit to cost ratio Funding sources Ministry of the Environment, Conseil supérieur de la pêche (CSP - now Onema), the départements of Calvados, Orne and Eure, the fishing federations of Calvados and Orne, European funds, Seine-Normandie, Region of Basse-Normandie water agency 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 Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Flood risk management Hydromorphology Continuity of sediment transport, Continuity for organisms, Freshwater flow regime Biology Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications removal of sluices, removal of dams, Creation of fish passes, Weir removal, Weir lowering Floodplain / River corridor Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description http://www.onema.fr/sites/default/files/EN/EV/publication/rex TouquesGB.pdf All information on this page is copied from the AFB, the French organisation for biodiversity. Supplementary Information Edit Supplementary Information