Lancieux bay

Côtes d’Armor (22)

The Lancieux Bay was gradually gained by man over the sea (polder). Over the centuries, the construction of dykes (Dyke of the Monks, Dyke of La Roche or Beaussais Dyke) and irrigation canals have allowed the development of agriculture.

The landscape has been made up over time according to the needs of the local community, alternating between salt meadows, vegetable farming, bocage meadows, apple orchards, cereal farming or wet meadows.

With the Conservatoire du littoral as the new landlord, turning to new agricultural activities started. The objective of creating permanent meadows without inputs is to improve water quality and reduce economic stakes in an environmentally sensitive area.

The Lancieux Bay has kept a wild character with a great diversity of natural landscapes despite being inhabited and used by man.

Between the 13th and 16th centuries, the Benedictine monks of the Abbey of Saint-Jacut built a dyke, today called Dyke of the Monks. It allowed them to dry up the marsh for agricultural use. Later, the Dyke of La Roche (18th century) extended the polder to its current limits. The site of the Beaussais Marsh (Ploubalay polder), separated from the Lancieux polder by a stream, was dried up by the construction of another dyke in the early 19th century. These two contiguous polders form a coherent whole in Lancieux Bay.

The Dyke of the Monks is the oldest heritage element of the site and represents a valuable testimony to the development of the land-sea interface over the past centuries.

The Adapto project for the site:

Global warming and sea level rise are causing changes on the coast. Today, during spring tides, the sea reaches the top of dykes and sometimes overflows them during storms.

Since 2015, reflection has been conducted on new forms of developments in order to anticipate the impacts of sea level rise. A strategy of a gradual dyke retreat will restore the earliest area that the sea used to cover.

To accept the maritime character of the bay is to transform the conception of its users and make them accept to give some space back to the sea and to create new areas for promenading.

Letting saltwater in the hinterland marshes while controlling it provides a new expansion area for the sea, absorbing some of its energy during storms, and reduces the cost of the construction and maintenance of protection works. The bay presents favourable conditions for adaptive coastal management. Several reconnection scenarios have therefore been evaluated for the Lancieux polder:

  • The levelling of the dyke
  • The creation of breaches
  • The implementation of hydraulic management by lock
  • Spontaneous submersions

In the town of Lancieux, this transition space allows to consider a protection system based on several measures:

  • The rehabilitation of the old Dyke of the Monks for pedestrians;
  • A new, limited-length dyke protecting goods and people between the Dyke of the Monks and urbanized areas;
  • The infiltration of salt water into the area covered by the sea, creating a new marsh of salt meadows that dissipates marine energy.

The aim here is to balance different issues through a strategy of progressive managed realignment: heritage, environment and the use of natural areas.

Site chronicle

27th July 2011: Decision of the City Council of Lancieux to create a protection system based on several measures: to rely on the Dyke of the Monks and, if necessary, to build a third dyke to protect the camping site and the houses.

2015: Hazard study - Diagnosis of the state of the structure and recommendations for maintenance. Definition of the vulnerable area.

2016: Meetings with mayors and inter-communal elected officials: worries regarding the opinion of the inhabitants on the project. Request to highlight the benefits of the project for inhabitants and tourism. Awareness raising on the upcoming issue of climate change on which the Community of Communes will have to work in the context of the GEMAPI law (managing aquatic environments and flood prevention).

4th November 2016: Presentation of the results of the geomorphological and landscape university studies to elected officials of the Emerald Coast. Questioning about the funding of the project and the interest of undertaking a reconnection action rather than letting nature do its work. Request to have an estimate and a technical and legal feasibility study for each scenario.

15th November 2016: Day of exchanges between the Norman elected officials of the Val de Saire (LiCCo site) and the elected officials of the Lancieux Bay on the adaptation of coastal regions to climate change.

2017: "Ecosystem services of a Slikke-Schorre complex" + "Biogeomorphology and estimation of the Lancieux Bay salt marsh attenuation service" (EPHE study).

21st November 2016: Meetings with the City Council of Lancieux to issue a declaration of public utility to control land, a key element for the progress of the adapto project.

6th November 2017: Steering committee for the establishment of the GEMAPI.

11th July 2018: Site management committee of the Tertre Corlieu and Beaussais Marsh.

8th August 2018: Meeting with the Mayor of Lancieux regarding land purchase and hydraulic management of the Lancieux Marsh.

November 2018: Purchase of the parcel AH 238.

29th March 2019: Steering committee of the Lancieux Bay.

Ligne de temps

14th century Construction of the Dyke of the Monks, 54 hectares (130 acres).
1749 Construction of the Dyke of La Roche, 46 hectares (110 acres) were drained
Early 19th century Construction of the Dyke of Ploubalay, 75 hectares (185 acres) were drained
1929 Major thunderstorm flooding the land upstream of the Dyke of the Monks. Breaches opened in the Dyke of the Monks to facilitate the evacuation of rainwater towards the sea.
1962-1963 Submersion of the Ploubalay polder following a breach.
1983 First intervention area of the Conservatoire du Littoral on Tertre Corlieu.
1985 Submersion of the Ploubalay polder following a breach.
1990 Submersion of the Ploubalay polder following a breach
1992 Definition of an intervention area in Ploubalay, the Beaussais Marsh.
1994 First acquisitions in the Ploubalay polder by the Conservatoire du Littoral.
The maintenance of the Dyke of Ploubalay became too expensive for farmers.
1996 Breach and submersion of parcels in Ploubalay. Restoration of the dyke.
December 2004 Natura 2000 classification of the site composed of Lancieux Bay, Arguenon Bay, St Malo archipelago and Dinard.
2006 Breach and submersion of parcels in Ploubalay. Restoration of the dyke.
2008 Breach and submersion of parcels in Ploubalay. Restoration of the dyke.
May 2013 Creation by the Direction of Territories and the Sea (DDTM) of the Côtes-d'Armor department of a map of the areas exposed to the risk of submersion.
2014 Breach and submersion of parcels in Ploubalay. Restoration of the dyke.
Summer 2014 The whole Ploubalay Marsh, except the inhabited area, is purchased by the Conservatoire du littoral.
2015 The salt marsh increased by 25 hectares (60 acres) between 1952 and 2015.
June 2018 Storms flooding the Lancieux polder.
Interdiction d’accès au site du marais de Beaussais du 16 au 20 octobre 2020
15 octobre 2020

Interdiction d’accès au site du marais de Beaussais du 16 au 20 octobre 2020

En raison des grandes marées du 16 au 20 octobre 2020, l'accès au site du marais de Beaussais est interdit.

Lancieux bay in pictures

Lancieux bay in pictures

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