The Authie Bay, a coastal boundary between Pas-de-Calais and the Somme, is a Picardy-type estuary. It consists of an accreting shoreline (the poulier, on the southern bank) and an opposite shoreline with sections undergoing significant erosion (the musoir, on the northern bank).

Between 1258 and 1862, as the Poulier (southern bank) gradually accreted, humans built dikes (locally known as “renclôtures”) to progressively reclaim cultivable land from the salt marshes. In contrast, the northern bank has experienced (and continues to experience) significant erosion, particularly pronounced and visible at the Anse des Sternes, in the dune massif between the Bois des Sapins and the Bec du Perroquet. As for the schorre (or salt marshes), it is expanding through a slow process of silting and infilling of the bay.

On the northern bank, erosion of the dune ridge raises concerns about a possible breach that could threaten the low-lying lands located behind it with flooding (see: Coastal Risk Prevention Plan). This erosion results from a combination of factors: the natural evolution of the Poulier/Musoir system under the influence of waves and wind, the shifting of the Authie river’s main channel within its bay, and various structures built by humans over the past centuries. The sea and the Authie continuously shape the coastline. This estuary is part of a PAPI (Flood Prevention Action Program) initiative. To anticipate sea level rise linked to climate change, different scenarios have been studied, promoting the adoption of adaptive management strategies:

• Identify the essential infrastructure needed to ensure people’s safety and locate it effectively.
• Reconnect certain polders with the estuary to better support the evolution of the coastline.
• Design the developments by taking into account their overall effects, so that protections established in one area do not exacerbate erosion elsewhere.

Project actions and outcomes

These complex sediment exchanges create a wide variety of natural habitats (dunes, polders, salt marshes, hedgerow meadows, ponds, etc.). This complementarity of habitats provides a resting place for migratory birds and supports numerous human activities.

Balancing the protection of property and people, the continuation of traditional uses (hunting, agriculture, fishing), eco-tourism development, and the preservation of natural spaces requires a collective effort.

The Conservatoire du Littoral (french coastal protection agency) is involved in the resilient development of the bay. It is gradually acquiring land whose topography offers natural protection complementary to the dike system defined in the Flood Prevention Action Program (PAPI). The strategy is to use dunes and marshes as buffer zones in front of the flood defenses. At the back of the bay, the repositioning of dikes will restore areas for marine floodwater expansion. Near the Bois des Sapins, the construction of a setback dike will protect the area from flooding in case of dune breach. However, to prevent the formation of such a breach, the dune ridge—stabilized by pine planting in the 1960s—must regain its natural mobility.

The repositioning of these dikes will impact current uses (agriculture, hiking, etc.). To this end, meetings are held with local stakeholders to assess the consequences of different development options on economic activities and to find solutions. A territorial project is to be co-created around these new structures to enhance this land-sea interface.

Presented within a landscape approach, the land acquisitions by the Conservatoire du Littoral and the works of local authorities allow for the development of walking loops around the bay. At La Mollière (an agricultural polder created in 1850 and acquired in 2002), the Adapto project aims to improve the ecological quality of the estuary by creating resting, nesting, and feeding areas for birds. A comprehensive visitor management plan around the bay will define the works to be undertaken in the coming years to develop eco-tourism in this protected natural area.

Chronology

• May 7, 2015: Scientific Council, presentation of the Adapto approach and recommendations regarding natural risk management in Authie Bay.
• September 30, 2016: Site visit with elected officials to review completed developments and projects around Authie Bay – Landscape approach to better understand the need for a comprehensive work on the bay, both along the seafront and inland.
• August 2018: Coordination meeting for the various projects around the bay.
• October 10, 2018: PAPI BSA Steering Committee – Presentation of the Adapto project to local stakeholders.
• November 28, 2018: On-site meeting with the Prefect of Pas-de-Calais.
• December 21, 2018: Establishment of a monitoring committee for the northern bank of Authie Bay – DDTM (lead), CA2BM, DREAL Risks, DREAL Nature, Conservatoire du Littoral.
• January 22, 2019: Marine Park – envisioning coordination between Marine Educational Areas and the Adapto educational project.
• March 6, 2019: Feedback and site visit in Normandy (Communauté de Communes de Coutances Mer et Bocage).
• March 11, 2019: Discussions on the action program around the bay with local stakeholders.
• March 14, 2019: Technical committee for urgent works at Authie Bay – DDTM (lead), CA2BM, DREAL Risks, DREAL Nature, Conservatoire du Littoral.

Located between the municipalities of Bastia and Penta di Casinca in Haute-Corse, the Golo Delta site stretches along nearly 30 km of coastline. It is a low, sandy formation with a lido that encloses the Biguglia lagoon. Its low profile and substrate make this area vulnerable to various coastal hazards, particularly extreme marine weather events. The richness, uniqueness, and pressures affecting these areas have led the Conservatoire du littoral to undertake land acquisition efforts covering nearly half of the coastline.

Along this coastline, the natural areas and significant economic interests must be understood and managed to organize their coexistence through the development of intention frameworks for integrated coastal zone management.

In some parts of this coastline, the environments are neglected, and the dune ridges are heavily weakened by natural impacts (storms and swell) and human pressures (buildings close to the shoreline and uncontrolled motorized use of the beaches). On Conservatoire-owned land, protective measures such as the installation of sand fences help address the issues of uncontrolled beach use and allow the dune ridges to rebuild and stabilize, restoring their natural function as barriers against saltwater intrusion.

Moreover, the Golo Delta site hosts remarkable biodiversity, including, for example, the presence of large-fruited prickly juniper, Hermann’s tortoise, and the European pond terrapin at the Mucchiatana site—species that are emblematic and of major heritage interest. Beyond these species, the delta’s geological history has also created notable wetland and coastal habitats, which are now recognized and protected as the Biguglia lagoon nature reserve, ZNIEFF sites, and Natura 2000 zones.

A study conducted by BRGM, based on shoreline evolution from 1948 to 2007, revealed different trends in coastline change across the site: some areas show sand accumulation and shoreline advancement towards the sea, while others are eroding, with local erosion rates near the Golo river mouth reaching up to 100 meters over 50 years. Using this historical analysis, BRGM projected the shoreline’s future evolution up to 2050.

The Conservatoire is actively promoting the Adapto approach among public and private stakeholders in the region, including raising awareness about responsible beach cleaning and supporting sustainable development efforts that consider long-term challenges.

Project actions and outcomes

The areas of reflection that have guided the development of the project for this site are numerous but compartmentalized (hydro-sedimentary functioning, naturalist monitoring, landscape components, etc.). These should be integrated and enhanced through a more holistic understanding. Furthermore, the site deserves local support to monitor environmental changes where natural dynamics are now freer to operate.

Forward-looking scenarios, informed by economic factors, will serve as a basis for dialogue with local stakeholders in the eastern plain (elected officials, associations, professionals, residents, and government services).

These steps are essential conditions for establishing robust, shared solutions.

Additionally, the Conservatoire will continue its efforts to protect the coastal area through land acquisition, dune ridge restoration work, and facilities to welcome the public.

Chronology

September 2018: Meetings with economic stakeholders (hospitality sector) of the study sites with the BRLi office. The goal was to present the results of the proposed development scenarios, the cost-benefit analysis, and the multicriteria analysis.

October 2018: Information meetings with residents of housing estates located on the dune ridge in the communes of Biguglia and Borgo: presentation of a technical plan for the restoration and protection of the coastal area, gathering participants’ feedback, and responding to their questions. Read the report.

February and March 2019: Presentation of technical restoration and coastal protection plans to the town halls of Furiani and Castellar di Casinca.

Spring 2019: Development works carried out as part of the Adapto project in the communes of Borgo and Venzolasca.

In the Bay of Mont-Saint-Michel, between the Bec d’Andaine and the Pignochet beach of Saint-Jean-le-Thomas, the intervention area within the project framework consists of a dune massif stretching 5 kilometers and the Claire Douve marsh located inland, spanning the communes of Saint-Jean-le-Thomas, Dragey-Ronthon, and Genêts, as well as the public maritime domain.

Since the 1950s, the sea has eroded more than 350 meters of the dunes bordering the beach on the northern part of the dune massif, while central and southern sectors have received significant sediment deposits. This configuration of dunes and back-dune marshes makes this site unique. It is classified as a Natura 2000 site, a ZNIEFF 1 zone (area of great biological or ecological interest), and partially listed as a UNESCO World Heritage site.

The site hosts many uses, which increase during the summer: beach activities, dune and marsh agriculture, horseback riding on the public maritime domain, hiking, including the passage of the long-distance hiking trail GR 223. This trail is threatened by severe erosion at certain points along its route.

Since the 1980s, parcels of land have been acquired by the Conservatoire du Littoral, with management entrusted to SyMEL (Mixed Syndicate for Coastal Spaces of Manche), particularly for site management work, usage agreements with agricultural operators, and relations with local stakeholders.

Fauna and flora

Regarding the flora, one can notably observe the Ophioglossum-leaved buttercup, bulbous rye-grass, lake bulrush, broad-leaved catchfly, and others.

The site is also a nesting area for many bird species such as the sand martin, reed warbler, spotted crake, and water rail. Located close to the Bay of Mont-Saint-Michel, the marsh plays an important role during wintering and pre-breeding migrations, especially for the wigeon, teal, black-tailed godwit, Eurasian spoonbill, and green sandpiper.

Located on the Caribbean coast of Martinique, the Bay of Fort-de-France is a strategic and dynamic area, characterized by dense coastal urbanization.

It is home to around 40% of Martinique’s population, as well as major commercial and transport infrastructures, particularly a port and an international airport, thus playing a central role in the island’s economic, social, and cultural life.

In addition to significant urban development, the Bay of Fort-de-France also includes large agricultural areas, notably dedicated to sugarcane cultivation, as well as vast natural spaces.

However, due to its low elevation, part of this territory is now exposed to marine flooding, and the agricultural lands are experiencing soil salinization, threatening the existing agricultural model.

The Fort-de-France mangrove, also known as the Génipa mangrove—the largest mangrove in Martinique—is a key element of the area and plays a crucial role in coastal protection and biodiversity preservation. It is home to several plant and animal species endemic to the island, including various types of mangroves and mahogany trees.

The southern part of the bay was assigned to the Coastal Protection Agency (Conservatoire du Littoral) in 2015, followed by the northern part in 2017.

Fauna and flora

It is possible to observe mangrove species such as Rhizophora mangle (red mangrove), Avicennia germinans (black mangrove), Laguncularia racemosa (white mangrove), and Conocarpus erectus (buttonwood or grey mangrove). Protected plant species include: Oncidium ceboletta (orchids), Ammania coccinea (scarlet ammania), and Zygia latifolia (river acacia). Two CITES-listed species (Convention on International Trade in Endangered Species of Wild Fauna and Flora): Swietenia macrophylla (Honduran mahogany) and Swietenia mahagoni (West Indian mahogany), as well as 153 plant species from the back-mangrove zone.

Local partners:

The Lancieux Bay is an area gradually reclaimed from the sea by humans (polder). Over the centuries, the successive construction of dikes (such as the Dike of the Monks, the Roche Dike, or the Beaussais Dike) and irrigation canals has made it possible to develop agriculture.

The landscape has thus been shaped according to human needs, alternating between salt meadows, vegetable farming, bocage pastures, apple orchards, cereal crops, and wet meadows.

The Conservatoire du littoral’s land ownership of the polder has made it possible to initiate a transition of agricultural land. By establishing permanent grasslands without inputs, the aim is to improve water quality and reduce economic pressures in a sensitive area.

The Lancieux Bay has retained a wild character, with a great diversity of natural landscapes, while still being inhabited and used by humans.

Between the 13th and 16th centuries, the Benedictine monks of the Abbey of Saint-Jacut built a dike, now known as the “Dike of the Monks.” It enabled the draining of the coastal marshes for agricultural use. Later, the Roche Dike (18th century) marked the extension of the polder to its current boundaries. The Beaussais marshes (Ploubalay polder), separated from the Lancieux polder by a watercourse, were drained through the construction of a dike in the early 19th century. These two adjacent polders form a coherent unit within the Lancieux Bay.

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

Project actions and outcomes

Climate change and rising sea levels are causing changes along the coastline. During high spring tides, the sea now reaches the tops of the dikes and sometimes overflows them during storms.

Since 2015, new approaches to land management have been explored in order to anticipate the effects of rising sea levels. A strategy of planned dike retreat over time is gradually giving back to the sea what humans had reclaimed.

Accepting the maritime nature of the bay means shifting the perspective of users—allowing the sea to reclaim some space and creating new areas for walking and recreation.

Allowing saltwater to enter the low-lying inland marshes in a controlled way provides a new area for sea expansion. This helps absorb part of the sea’s energy during storms and reduces the cost of building and maintaining protective infrastructure. The bay offers favorable conditions for this flexible approach to coastal management.

Several reconnection scenarios have therefore been evaluated for the Lancieux polder:

• Dike removal
• Creation of breaches
• Installation of water control structures (sluices)
• Natural (uncontrolled) tidal flooding

Thus, in the municipality of Lancieux, this transitional area makes it possible to envision a layered protection system based on:

• The restored historic Dike of the Monks, repurposed as a walking path;
• A new, limited-length dike providing protection for people and property between the Dike of the Monks and the urbanized areas;
• The controlled intrusion of saltwater into the area returned to the sea, creating a new salt meadow marsh that helps dissipate wave energy.

The aim here is to balance heritage, environmental concerns, and the use of natural spaces through a strategy of gradually supporting the landward retreat of the coastline.

Chronology

• July 27, 2011: Resolution by the Lancieux municipal council proposing a system of successive defense layers: relying on the Dike of the Monks and, if necessary, implementing a third dike to protect the campsite and nearby homes.
• 2015: Hazard study – Assessment of the dike’s condition and maintenance recommendations. Definition of the vulnerable area.
• 2016: Meetings with mayors and intermunicipal officials – concerns about how residents might receive the project. Desire to highlight the benefits of the project for local residents as well as for tourism. Growing awareness of the emerging challenges related to climate change, which the Community of Municipalities will have to address within the GEMAPI framework (flood risk and aquatic environment management).
• November 4, 2016: Presentation of the results of geomorphological and landscape university studies to elected officials of the Côte d’Emeraude. Questions raised about project funding and the interest in a reconnection initiative rather than simply allowing nature to take its course. Desire to include cost estimates and assess technical and legal feasibility for each scenario.
• November 15, 2016: Exchange day between elected officials from Val de Saire (Licco site, Normandy) and those from the Bay of Lancieux on adapting coastal territories to climate change.
• 2017: Studies on “Ecosystem services of a Slikke-Schorre complex” and “Biogeomorphology and evaluation of the storm attenuation service of the Lancieux Bay salt marsh” (EPHE study).
• November 21, 2016: Discussions with the municipality of Lancieux on establishing a DUP (Public Utility Declaration) to secure land control—key to advancing the Adapto project.
• November 6, 2017: COPIL (steering committee) meeting for the implementation of GEMAPI.
• July 11, 2018: Site management committee for Tertre Corlieu and Beaussais Marshes.
• August 8, 2018: Meeting with the mayor of Lancieux about land acquisitions and water management in the Lancieux marsh.
• November 2018: Acquisition of parcel AH 238.

The Loire Estuary site has a unique dimension: spanning over 5,500 hectares, it is characterized by a rich network of wetlands, part of which is used for agriculture—mainly livestock farming. Within this site, four areas are or will be part of the Adapto+ Loire Estuary initiative.

Corsept, the westernmost area on the south bank of the estuary between the communes of Paimboeuf and Saint-Brévin, underwent a series of actions carried out between 2022 and 2024 as part of the Adapto Estuary Corsept project. Studying the expected changes at the land-sea interface, this approach highlighted adaptation pathways to rising sea levels for these areas, which include hay meadows, pathways, and nearby buildings.

Lavau-sur-Loire is one of the three new areas integrated into the LIFE Adapto+ project. This site, covering around 2,700 hectares and encompassing the former islands of North Loire, is located 19 km from Saint-Nazaire and 33 km from Nantes. To the east are Massereau-Migron, including the former islands of South Loire, and the Percée de Buzay, together covering an additional 2,200 hectares. These sites are partly designated within the European Natura 2000 network. These three new sites, where changes are already noticeable (vegetation, landscapes, and evolving uses), will be subject to further study within the LIFE Adapto+ framework.

Fauna and flora

It is possible to observe many species across these four sites, such as the European otter, Alpine longhorn beetle, stag beetle, great crested newt, sea and river lamprey, twaite shad, European eel, several species of bats including the barbastelle, lesser horseshoe bat, and brown long-eared bat, as well as numerous bird species: black-winged stilt, pied avocet, golden plover, Eurasian spoonbill, black-tailed godwit, northern shoveler, marsh snipe, common shelduck, bluethroat, marsh harrier, aquatic warbler, and reed warbler…

Owned by the State since the late 19th century and currently managed by the National Forestry Office (ONF), the Luzéronde site is located in the northwest of the island of Noirmoutier and is part of the European Natura 2000 network of sites.

This site is a textbook example of a coastal dune in contact with a rock revetment. It consists of a dune ridge that protects extensive agricultural and aquaculture areas, as well as several urbanized zones located to the east (mostly private land), from flooding. This natural barrier currently varies in width from 80 meters in the northern part of the site to 20 meters in the south—the area adjacent to the Devin dike. In the event of a breach during major weather events, the island of Noirmoutier would be severely impacted.

The ONF, as owner and manager of the dune area, and the Community of Communes of the Island of Noirmoutier (CCIN), within the framework of GEMAPI, have been working together for several years to reduce risk on the southern part of the dune ridge.

The Life Adapto+ project aims to strengthen this previously initiated approach by improving the dune’s resilience through actions that enhance sediment exchanges at the dune foot and support managed retreat of the dune ridge (accompanied translation). This project relies on the expertise of partner organizations (Cdl, BRGM, CEREMA, Observatory of the Island of Noirmoutier, ONF) as well as the shared commitment of local stakeholders (CCIN, municipalities, etc.) to promote nature-based solutions to address the effects of climate change.

The findings could lead to the creation of new management tools with national and European relevance for similar configurations.

Fauna and flora

It is possible to observe Ammophila arenaria, Cakile maritima, Euphorbia paralias, Calystegia soldanella, the coastal Omphalodes, Eryngium maritimum, as well as the Western spadefoot toad (Pelobates cultripes), a reptile species endangered in mainland France.

The morphology of the Orne estuary, from Caen to the sea, was significantly altered following the construction of the canal in 1857. After passing through Caen, the Orne River splits into two straight lines that structure the surrounding landscape. These two watercourses—the Orne and the canal—flow between two agricultural and urban plateaus, shaping a variety of evolving landscapes. The western corridor, guided by the canal, conveys an industrial and port-related character. To the east, the river changes with the tides, feeding a rich natural heritage: the Bay of the Orne.

The river’s embankment led to the disappearance of salt marshes (schorre) over much of the site. The banks of the Orne were reclaimed (polderized) all the way to its mouth. The Cagny marsh dike was built in the 18th century, transforming the former meander and its salt meadows into grazed wet grasslands. The François Fields polder is the result of more recent embankment works (1960s) on a tidal flat. As a result, downstream from the Montalivet dam (in Caen), the lateral expansion zone for natural habitats and tidal flooding now remains along only about one-fifth of the river’s length.

In 2011, the Cagny marsh dike failed, causing flooding in low-lying areas. During high spring tides, the sea occasionally overtops the dike, forcing the temporary closure of the cycle path built along its crest. This calls for a reassessment of the dike’s future—and more broadly, of the land behind it.

Today, available data on this site indicate that maintaining these polders in their current state is not the only possible vision for the future of the area. In fact, the return of salt meadow vegetation in the François Fields sector offers clear benefits in terms of economy, biodiversity, and landscape.

On the Cagny marshes, the LiCCo program (Coastal and Climate Change), carried out from 2011 to 2014, provided valuable insight into the evolution of the Orne estuary. A collective reflection was launched with all local stakeholders on what the coastline of tomorrow could look like. Adapting this estuary in the context of climate change and rising sea levels is based on:

• A vision for 2050: the development of a larger, deeper estuarine area to increase climate resilience;
• A trajectory to 2025: implementation of concrete, localized projects to re-establish lateral floodplain connectivity and promote coastal mobility.

The Orne, heavily canalized, lacks sufficient space for flood expansion—raising the issue of opening up the polders and affected marshes.

Project actions and outcomes

At Sallenelles, the approach involves working with local stakeholders to define public access facilities during the re-flooding of the François Fields.

Regarding the Cagny marsh, a process of reflection and project definition needs to be initiated, starting with historical and landscape analyses, followed by the development of prospective scenarios. In a scenario involving sea level rise, erosion, and rising groundwater levels, the current Cagny marsh dike would become obsolete and lose its protective function. Based on this analysis, the Conservatoire du Littoral and the Calvados Departmental Council, which manages the natural areas, are working on an alternative to the existing cycle path.

If the maritime character of the marsh is restored, new walking, cycling, and boating routes would offer visitors new experiences. Starting from the Nature and Estuary House, these paths contribute to maintaining the site’s appeal at the heart of the bay. At the same time, a consultation process should be conducted with Normandie Cabourg Pays d’Auge, the Chamber of Agriculture, Safer, the Conservatoire du Littoral, and local farmers to plan the gradual adaptation of their working tools over the coming years for this scenario.

Preliminary Study for 2050: Download now

Furthermore, addressing climate change requires a broader perspective than just the mouth of the Orne estuary (the intervention area of the Conservatoire du Littoral). Restoring the maritime character of the Orne demands a well-considered strategy at the scale of the entire Orne River—from Caen to the sea. Planning adaptation through different stages up to 2050 involves the participation of various stakeholders:

• The Calvados Department (greenways, sensitive natural areas, etc.), the CPIE
• The City of Caen, the Communauté de commune Caen la Mer, the Communauté de commune Normandie Cabourg Pays d’Auge, and the municipalities located downstream of the estuary (GEMAPI, urban planning documents, urban development of the peninsula…)
• Ports of Normandy (master plan for port development)
• State services (Risk Prevention Plan).

Owned by the Conservatoire du Littoral since the 1990s, the Bastidon Pine Forest covers over 18 hectares within the municipality of Londe-les-Maures. Part of a pine woodland stretching along the coastal fringe, the site also includes a wetland area and agricultural land.

Managed by the municipality, this site comprises both public and private property, local and tourist leisure activities (port, beach, walking trails, camping). It is heavily frequented during the summer season, with approximately 150,000 visitors annually on the coastal path.

Remnants of military fortifications dating back to the German occupation from 1942 to 1944 remain along the seafront. A long concrete wall marks the coastline and attests to the steady retreat of the shoreline over several decades. The proposal is to study the conditions for renaturalizing the site by removing the various hardened coastal structures. These reflections are carried out with the aim of limiting erosion downstream of the site, as well as continuing the coastal restoration efforts initiated by the previous Life Adapto project (2017–2022) at the Vieux-Salins d’Hyères site. Separated by a campsite, the Bastidon Pine Forest and the Vieux Salins d’Hyères are contained within the same hydro-sedimentary unit. This approach is also planned within the framework of the bay contract for “Rade de Toulon and the Golden Islands.”

Fauna and flora

It is possible to observe typical coastal natural habitats such as Juncus acutus, halophilous wastelands with Elytrigia species, the Rosy Starling (Pastor roseus), the Eurasian Jay (Garrulus glandarius), saltwort grasslands, and wrack lines.

Local partners:

The Vieux Salins d’Hyères site was acquired by the Conservatoire du Littoral in 2001. The protected area covers 365 hectares, making it a major protected natural space in the Hyères harbor. Along with the Salin des Pesquiers, it bears witness to the former salt production activity that was a cornerstone of the local development of the Hyères harbor. The site’s governance is managed by the Conservatoire and its partners (the Toulon-Provence-Méditerranée Agglomeration Community (TPM), the municipality of Hyères, and the Port-Cros National Park).

The current management plan organizes hydraulic management of the site similar to the former functioning of the salt marshes, with the aim of optimizing ecological and ornithological quality. However, this configuration is challenged by several phenomena, notably erosion of the dune ridge to the south: coastline retreat, loss of Aleppo pines and shaded areas, beach scouring, and threats to the site’s hydraulic structures.

The rock armor present on part of the site limits erosion where it is installed but directly amplifies it downstream of the sediment transport, disrupting the hydro-sedimentary functioning at the bay scale.

Studies conducted by BRGM and Aix-Marseille University have shown that this coastal wetland is a favorable site for implementing adaptive management actions for the coastline and natural areas, such as the removal of rock armor from the coastline with a view to renaturation.

Following an initial phase of rock removal over 100 meters at the western end of the structure, the manager TPM launched a study in 2017 (Artelia) to define a management strategy for the coastal ridge. This study explores the following options:

• A protection scenario (hard protection with dikes, etc.),
• A scenario to accompany the site’s evolution according to hazards,
• A renaturation scenario with natural rebalancing of the coastline,
• A no-action scenario.

The steering committee ultimately decided to combine two scenarios: “renaturation of the coastline” and “accompanying the site’s evolution through ecological engineering operations.”

The works and the project for this site are part of two European projects: Marittimo (Franco-Italian Interreg 2017–2019) and adapto (2017–2021).

Project actions and outcomes

The overall project aims to restore a natural dynamic to the dune-beach system that forms the interface between the sea and the wetland. To achieve this, the plan is to remove the rock armor and then gradually adjust the facilities and public access according to the environment’s evolution.

The adapto actions will focus on organizing the follow-up to the major works carried out under the Marittimo project (removal of the rock armor).

This will include ensuring continuity of the coastal promenade during bad weather by creating an alternative path and monitoring the evolution of the lagoon ecosystem, including the Posidonia seagrass beds that fringe the beach.

More generally, the project will develop actions directed towards users, the local population, and elected officials to address their concerns and prepare future changes together.

Chronology

• February 2019: Contract awarded for the construction of the pedestrian path and for the rehabilitation of the dune cordon and rock removal.
• April 2019: Start of the works; presentation of the exhibition on the project created as part of the educational activity by CPIE Côte Provençale and site visit with around thirty participants.
• July 2019: Completion of the construction of the path and restoration of the dune cordon.
• September 2019: Contract awarded for the monitoring of seagrass beds and start of the study.
• October 2019: Completion of rock removal works over 340 meters of coastline.
• April 2020: Second monitoring campaign of the seagrass beds.
• August and October 2020: Social perception surveys conducted among site users.
• October 2020: Extension of rock removal over an additional 275 meters. The Vieux Salins coastline has thus been renatured over more than 600 meters.
• September 2020: Third monitoring campaign of the seagrass beds.
• November 2020: Field trips for 4 classes from Hyères primary schools: discovery of the Vieux Salins and land art workshop on the theme of natural and artificial evolution of the coastline.
• September 2021: Fourth monitoring campaign of the seagrass beds.