Adapto: towards a flexible management of the coastline - Île Nouvelle

Île Nouvelle (Cities of Blaye and Saint-Genès de Blaye) – France 

Dates : 2017-2022

Project leader: Conservatoire du Littoral

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. This project is being financed by the European Programme Life, and carried out by the Conservatoire du Littoral and the Bureau de Recherches Géologiques et Minières.

In France, this project is being deployed across 10 pilot territories, including the site of Île Nouvelle in the Gironde Estuary. By the time the Conservatoire du Littoral acquired the Île Nouvelle in 1991, the island formerly farmed for wine and cereal had gradually been renatured. For nearly 10 years, this site has been a laboratory of flexible management of the coastline, a symbol of adaptation to climate change, and a demonstration of the benefits offered by nature. During the Storm Xynthia in 2010,  a breach at the northwestern side of the island in the dam system reconnected the northern part of the island to the estuary, permitting the flexible management of the coastline. In the southern part of the island, the management of water levels is now controlled, making the public reception and the enhancement of ecological potential possible. Adapto’s objective for this site is to draw on the knowledge and experience gained from the island management over the past decade and to continue to reflect on the long-term evolution of the site, taking into account the impacts of climate change.

The actions carried out are as follows: (1) Knowledge sharing with other locations and capitalizing on the approach carried out; (2) Educational work with schools, elected officials, civilians and coast guards; (3) Historical and prospective analysis of the evolution of landscapes; – Evaluation of the ecosystem services provided by the reconnection of Île Bouchaud; (4) Establishment of an ecological quality indicator; (5) Analysis of the social perception of users and residents; (6) Development of decision support tools (economic and multi-criteria analyses) regarding potential long-term evolution scenarios.

Actions

For nearly ten years, this site has been a laboratory of flexible coastal management, has become a  model of climate change adaptation and a magnificent demonstration of natural benefits.

In 2010, following the Xynthia storm, the northern part of the island has been reconnected. Since then, the area has been left to free evolution and is the subject of numerous scientific studies, notably on its flora and fauna. On the southern part of the island, the management of water levels is controlled to combine public access with the development of the ecological potential.

The Conservatoire du Littoral undertakes comprehensive actions to strengthen skills and share knowledge. These include national actions to capitalise on and put into perspective the other Adapto sites, as well as feedback and communication events related to the results of the project for practitioners, elected representatives and the general public at the local and regional levels. Finally, the Conservatoire du Littoral implements educational actions such as :

  • Development and deployment of an educational programme for primary and secondary school classes 
  • Awareness-raising and development of tools for the department’s rangers (animator’s kit)
  • Creation of an exhibition (kakemonos format) on the past evolution and future of the island

The Conservatoire du Littoral is carrying out on-site research actions such as historical and prospective analysis of the evolution of the landscapes; 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 impact of reconnection projects 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 the species relying on these soft environments. 

Specifically, on the site of Île Nouvelle, another research project led in partnership with INRAE is underway to assess the ecosystem services provided by the marine reconnection. This research project uses capacity matrices to evaluate ecosystem services. More precise estimates, based on fishing campaigns, are carried out on the feeding capacities for fish and shellfish. This project should provide scientific elements to local decision-makers on the benefits of having left (and keeping it that way) this area in free evolution. It also provides food for thought for other Adapto sites, particularly given the analyses of the economic impacts of nature-based solutions (in comparison with rigid management strategies).

Outcomes

As there are still relatively few depoldering initiatives in France, this site, which has been reconnected for more than ten years and has been monitored extensively, has a great potential for feedback. 

For the time being, the evolution of the site is quite positive, whether being in terms of recreating an estuarine-type habitats or developing populations of fish and bird species.

The Conservatoire du Littoral owns the site for its entire surface area. This means that the Conservatoire du Littoral and the manager can provide support over a long period of time, from the time agricultural activity ceased (in 1997), to the implementation of renaturation actions in the 2000s, to the free development of the site facilitated by the absence of economic and human stakes, and finally to the development of the island’s ecotourism and cultural potential since 2015. 

Specific estuarine context, with a high rate of sedimentation (influence of the muddy plug and the current/tide dynamics).

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, Department Council of Gironde, Bureau de Recherches Géologiques et Minières, INRAE, Museum National d’Histoire Naturelle , CPIE Médoc, CAUE Gironde, State services, municipalities and inter-municipalities, economic actors, local populations

Financial partners: European Union, Nouvelle Aquitaine Region, Adour Garonne Water Agency, French Biodiversity Office (OFB), Fondation de France, Total Foundation

Resources