Adapto: towards a flexible management of the coastline - Authie Bay

Authie Bay (Cities of Berck, Groffliers, Waben, Conchyl le Temple, Quend, Fort-Mahon) – France

Project leader: Conservatoire du Littoral

Dates : 2018-2022

Classification

Risks

Solutions

Actors

Costs

Summary

The Adapto project seeks to demonstrate by example the value of flexible management of the coastline as a solution for adapting coastal territories to climate change.  It is a project financed by the European Union’s Life programme and supported by the Conservatoire du Littoral and the Bureau de Recherches Géologiques et Minières. 

In France, it is deployed in 10 pilot areas, including the Baie d’Authie site in the Hauts de France. The Authie Bay is an estuary consisting of an accreting shoreline and an opposite shoreline with strongly eroded sections. The combination of the natural evolution of the site, the movements of the river and the various facilities built over the centuries raises fears of a possible breach in the dune belt that could submerge the low-lying areas behind it. In the north, about 8,030 people are in the protected zone, while in the communes south of the bay, 3,250 households, 376 businesses and 2,593 hectares of agricultural land have been identified in the submersible zone immediately behind the dikes.

As part of the Flood Prevention Action Programme (PAPI) and in anticipation of tising sea levels, the adaptive management of the coastline has been decided. The Conservatoire du Littoral is gradually acquiring land whose topography offers natural protection, such as dunes and marshes. The aim is to integrate the new protection works with the natural elements, to enhance the landscapes of the bay and at the same time to maintain environmentally sound agricultural activities. 

The actions carried out are as follows: (1) Historical and prospective analysis of landscape evolution; (2) Acquisition of land whose topography offers natural protection; (3) Ecological development of the Mollière polder (Groffliers); (4) Modelling of submersion hazards according to different coastline management scenarios; (5) Mapping of natural habitats and analysis of their possible evolution; (6) Establishment of an ecological quality indicator; (7) Economic evaluation of the different coastline management scenarios; (8) Analysis of the social perception of users and residents; (9) Development of decision-making tools (multi-criteria analysis) and consultation on possible development scenarios; (10) Educational activities with schoolchildren, elected representatives, users and coast guards (11) Exchange of experiences with other sites and capitalisation on the adopted approach.

Actions

As part of the Flood Prevention Action Programme (PAPI), this project contributes to facilities development in line with natural habitats management and elaborates a comprehensive tourism plan around the bay to develop eco-tourism in this unspoiled environment.

The strategy consists in using the dunes and marshes as buffer zones ahead of the structures. At the bottom of the bay, the relocation of dykes should restore maritime flood expansion zones, thus reconnecting some polders with the estuary to better assist shoreline evolution.

Pursued in a landscaping approach, Conservatoire du Littoral’s land acquisitions combined with local communities’ efforts make it possible to envision pathway loops around the bay. 

On the Mollière site (an agricultural polder created in 1850 and acquired in 2002), the Adapto project plans to increase the estuarine ecological quality by designing resting, nesting and breeding areas for birds while conceiving the dyke to allow visitors to observe this area of undisturbed ornithological quality, and maintain it through eco-pasture.

As part of the Adapto project, the Conservatoire du Littoral is deploying a series of educational actions:

  • Development and deployment of an educational programme for primary and secondary school classes 
  • Raising awareness and developing tools for the department’s rangers

The project is also committed to organising events to report and communicate the results of the project to practitioners, elected officials and the general public at the local and regional levels. Likewise, consultative workshops are regularly organised with the local population. 

It also participates in national actions to capitalise on and put into perspective the other Adapto sites’ experiences.

The Conservatoire du Littoral is carrying out on-site research actions such as historical and prospective analysis of the evolution of the landscapes; hydraulic studies on the saltwater ridge; mapping of the natural habitats and their prospective evolution; economic assessment of the different coastal management scenarios; updated analysis of the social perception of the users; as well as developing decision-making tools (economic and multi-criteria analyses) around possible long-term evolution scenarios.

It is also working on the implementation of an ecological quality indicator. This research project, carried out in partnership with the National Museum of Natural History as part of the Adapto project, aims to develop an ecological quality indicator tailored for natural coastal environments. This indicator should allow the description of the reconnection impacts on the ecological quality of natural coastal areas and the monitoring of their evolution. It is pivotal for the Conservatoire du Littoral and its managers that intend to improve the environmental quality of the coast. It also entails the provision of answers to the concerns expressed by various environmental stakeholders about the potential negative impacts of marine reconnection on species relying on these ‘soft’ environments.

Outcomes

As there are still relatively few depoldering initiatives in France, the 10 Adapto program sites offer great potential for feedback.

The Conservatoire du Littoral owns the entire site of ecological restoration located on the Groffliers polder and at the top-tier dyke. 

The Conservatoire du Littoral helps local communities to define suitable spaces for environmental compensation activities in the vicinity of the new structures created. This support is also provided to reflect on the management of the buffer zones and the development of ecotourism and cultural activities in relation to these new landscapes.

Importance of popularising and widely disseminating the results of the monitoring carried out on the site to local stakeholders, in order to strengthen the social acceptability of management policies.

Partners

Technical partners: Conservatoire du Littoral, EDEN 62, Syndicat Mixte Baie de Somme-Grand Littoral Picard (SMBS-GPL), Bureau de Recherches Géologiques et Minières, Muséum National d’Histoire Naturelle, CPIE Val d’Authie, State services, municipalities and inter-municipalities, economic stakeholders, inhabitants

Financial partners: European Union, Office Français pour la Biodiversité, Fondation de France, Total Foundation

Resources