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.

The Grand Radeau / Brasinvert site stretches along the sea and the banks of the Petit Rhône, to the west of the commune of Saintes-Maries-de-la-Mer. Included in the Camargue Regional Natural Park and the Camargue Biosphere Reserve, this remarkable natural area features a variety of landscapes: maritime shores, dune ridges, pine forests, salt marshes, and sansouïres (salt-tolerant coastal meadows). It is also part of the European Natura 2000 network.

On the right bank of the Petit Rhône, Grand Radeau / Brasinvert is separated from the village center by the river’s mouth. This location makes it a unique area where the main activity is extensive breeding of Camargue bulls and horse riding tours to explore the site. Hunting is practiced on the communal plot, and the entire site is subject to regulated tourist visits.

Furthermore, the site is subject to significant erosion: in the 1980s, this led to the installation of several hard coastal defenses along this sandy shore (groynes, rock-armored dikes), which today are deteriorating and increasingly vulnerable to the sea’s assaults.

Fauna and flora

It is possible to observe a remarkable assemblage of macrophytes including Althenia filiformis and Tolypella salina. The site also hosts breeding birds characteristic of the Camargue: Stone-curlew, Kentish plover, Spectacled warbler, Skylark, and Tree pipit. The Icard pond is an important site for the wintering of several species of ducks and geese.

Local partners:

Owned by the State and managed by the National Forests Office (ONF) since around 1880, the Carcans site is part of the Aquitaine coastal dune systems. This area is classified as a “natural zone,” meaning there are no public facilities, and it is also part of the European Natura 2000 network. It consists of an unvegetated dune along the ocean edge and forested areas further inland.

Today, the coastal dune is threatened with disappearance in some parts of Aquitaine due to increasing marine erosion over time. At the Carcans site specifically, the dune’s width has decreased from 138 meters in 1957 to 40 meters in 2021.

To try to preserve the dune and maintain the essential sediment exchanges between the beach and the dune, the ONF implemented a first trial of “controlled remobilization” in 2022. This method aims to use natural processes (wind, vegetation dynamics, etc.) to shift the dune and thereby maintain its width or even strengthen its resilience.

Following the example of “La Teste / Biscarrosse,” the Life Adapto+ project will address several technical questions about the site’s future: Will dune translation be sufficient to maintain it? How will the flora and fauna evolve on and near the site? Should intervention occur on the dune’s inland retreat to ensure the potential survival of the heritage vegetation of the grey dunes?

Fauna and flora

It is possible to observe the Ocellated Lizard (Timon lepidus), classified as a “vulnerable” species in the Red List of reptiles of Metropolitan France. The flora includes several species: Marram grass (Ammophila arenaria), Sea rocket (Cakile maritima), Sea spurge (Euphorbia paralias), Sea bindweed (Calystegia soldanella), Sea holly (Eryngium maritimum), Lyme grass (Elytrigia juncea), Curry plant (Helichrysum stoechas), and Thyme-leaved toadflax (Linaria thymifolia), among others.

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.

PState-owned and managed by the National Forestry Office (ONF), the La Teste-Biscarrosse site is part of the Atlantic coastal dune massifs of Aquitaine. Similar to Carcans, this area is classified as a “natural zone,” meaning it has no public facilities, and it is part of the European Natura 2000 network. It consists of an unvegetated dune along the oceanfront with forested areas in the background.

Following the major storms of the winter of 2013-2014, dune cliffs became widespread, and marine erosion of the beaches and dune bases intensified. As a result, the dune width is gradually decreasing.

To help preserve the coastal dune and maintain the essential sediment exchanges between the beach and dune, experimental works conducted in 2015 and then in 2020 have increased the transport of sand towards the back of the beach and allowed for the natural reshaping of the dune. This nature-based solution aims to create a new dynamic between the beach and the dune ridge.

Following the example of Carcans, the Life Adapto+ project will develop new management tools with national and European relevance for this type of similar setting.

Fauna and flora

The Ocellated Lizard (Timon lepidus), classified as a “vulnerable” species in the Red List of reptiles of Metropolitan France, can be observed here. The flora includes several species such as Marram Grass (Ammophila arenaria), Sea Rocket (Cakile maritima), Sea Spurge (Euphorbia paralias), Beach Morning Glory (Calystegia soldanella), Sea Holly (Eryngium maritimum), Lyme Grass (Elytrigia juncea), Everlasting Flower of the Dunes (Helichrysum stoechas), Thyme-leaved Toadflax (Linaria thymifolia), and others.

Over more than 420 hectares protected by the Conservatoire du littoral, the Lido de l’Or (Petit and Grand Travers) consists of natural environments of high ecological value such as dune ridges, salt marshes, and forested areas that require particular attention for biodiversity conservation. It is notably part of the European Natura 2000 network of protected sites.

Located between the urban areas of La Grande Motte and Carnon, this area is particularly fragile, subjected to strong pressures from both natural and human origins. While it experiences significant erosion effects on the Petit Travers, year-round tourist activity greatly contributes to the degradation of the coastal strip.

After extensive consultation, Petit Travers was the subject of an ecological restoration project in 2014. Between 2017 and 2022, the Life Adapto project helped to consolidate and share the experience of restoring Petit Travers and to develop a forward-looking, cross-sectoral vision for the Lido over the medium and long term.

Today, the ambition is to expand the project to cover the entire Lido, including Grand Travers. This project aims to better manage the multiple uses and the very high visitor numbers over the long term while improving visitor facilities, maintaining or even developing agricultural activity, implementing innovative forest plantation management solutions with the National Forestry Office (ONF), connecting the site to the river network, and restoring and opening to the public an 18th-century signal tower listed as a Historic Monument. In this context, the Life Adapto+ project is intended to provide decision-support tools to feed the project and anticipate updates to the site’s management documents through the lens of climate change adaptation.

Fauna and flora

It is possible to observe numerous bird species such as the Crested Lark, Blue Tit, Willow Warbler, Nightingale, Blackcap, and Green Woodpecker. During migrations, migratory passerines are also seen resting during stopovers. The flora is also extremely diverse, with over 150 species, including 21 considered to be of heritage value.

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.

In French Guiana, large mudbanks move along the coastline from east to west. When present, they dissipate wave energy, protect the coasts from erosion, and allow mangroves to develop. When absent, waves break directly on the beaches, causing stronger erosion. In this way, the coasts of French Guiana are highly dynamic and ever-changing.

Until the early 1980s, the coastline of Mana was made up of a mosaic of wetlands and mangroves along the shore. This area, called the “Savane Sarcelles,” was then converted into a large 5,000-hectare polder dedicated to rice cultivation, which led to the creation of new open wetland habitats rich in biodiversity.

Between 2000 and 2016, in the absence of a protective mudbank, the coast receded by one and a half kilometers.

In addition to these erosion problems, other constraints and difficulties arose that hastened the end of the large rice development project on the site: regulatory changes, changes in ownership, and various economic challenges.

This agricultural decline led to the closure of wetland habitats, which became less rich in biodiversity.

The Mana polder is known for its remarkable and unique ornithological richness at the scale of French Guiana. Each year, it hosts hundreds of thousands of birds from over 200 different species. Among these, migratory shorebirds represent the largest populations, and for them, conserving the Mana polder’s carrying capacity is a conservation issue of global importance.

Aware of these stakes, the Conservatoire is undertaking land management actions to protect this area and preserve its richness by implementing a site project based on diversified agricultural use, public access, and ecotourism development focused on birdwatching.

Project actions and outcomes

The Adapto program plans to implement several studies, some of which are essential for developing the site’s management plan. An example is the BRGM study aimed at modeling the medium-term projection of the coastline. This study will help define the boundary between the natural area, where a flexible coastal management approach will be tested, and the exploited area, thereby establishing an appropriate management strategy.

Maintaining open habitats through cattle grazing, combined with the restoration of the hydraulic network, will contribute to preserving wetlands favorable to birdlife. The ornithological richness of the rice fields gives them strong ecotourism potential. Birdwatching could eventually become the main activity in the former rice fields.

Chronology

2018

• July 5: Land acquisition of 1,500 hectares.
• September 3: Acquisition of a pre-emption right on an area of 2,200 hectares.
• September 14: First steering committee for the development of the management plan; a consortium of four consulting firms is responsible for its implementation.
• October 17: BRGM begins a study aimed at modeling the medium-term (50 years) projection of the coastline and the risk of marine flooding on the polder.
• November 19: Start of the landscape study in partnership with ENSP.
• November 28: First technical committee meeting; BRGM explains the vulnerability of the rice fields to erosion and marine flooding.

2019

• March 11 to 16: EUCC-France workshop in Guyana. Meeting between researchers, managers, and elected officials to exchange knowledge and management strategies for the Guyanese coastline. The Adapto project and results of the landscape study will be presented.
• May 13 to 17: Study trip to Camargue; stakeholders from the Mana territory and elected officials visit sites facing similar issues to Savane Sarcelles.
• May: Results of the BRGM study, on which the consulting firms in charge of the management plan will rely to finalize their diagnosis.
  June: Second steering committee for the management plan; consulting firms will present the results of their diagnosis.
  Workshop on agriculture with actors from the agricultural sector and project leaders to discuss allocation conditions and individual needs.
• July: Start of work to create the first public access to the sea.
• September: Implementation of educational activities in Mana primary schools in partnership with the Association for the Discovery of Nature in Guyana (ADNG).
• December: Third steering committee meeting presenting the project definition for the site.

A lido is a sandy coastal barrier that encloses a lagoon. The lido of Petit and Grand Travers, also called the lido de l’Or, separates the Étang de l’Or from the Mediterranean Sea, divides two highly urbanized areas (Carnon and La Grande Motte), but offers a succession of dune ridges, salt marshes, and forested areas of great ecological, landscape, and cultural value.
It is largely owned by the Conservatoire du littoral, which has been managing this site since 1976.

The Petit and Grand Travers lido site is part of a larger sedimentary unit (the Bay of Aigues Mortes), which is subject to ongoing erosion.
In 2008, the Hérault department carried out emergency works across this entire bay, where beaches and dune ridges were at risk of no longer fulfilling their role as a natural barrier against marine incursions. A large-scale replenishment operation was undertaken: one million cubic meters of sediment brought by the Rhône River were extracted and then deposited on four areas of the Bay of Aigues Mortes (with an estimated benefit of between 300,000 and 400,000 m³ for the Lido de l’Or).

The sustainable development program for the lido, studied and coordinated over ten years, resulted in 2015 in the renaturation of the dune and a complete reorganization of visitor facilities on the site. The key feature of this operation was the removal of a section of the road built on the dune, which allowed natural dynamics to resume.

Download the file (Rehabilitation of the Petit and Grand Travers Lido – Public presentation of the project 2014).

Petit Travers before work

Petit Travers after work

Project actions and outcomes

Among the range of approaches within the Adapto project, the Petit and Grand Travers site is one of the most advanced. The large-scale works carried out from 2003 to 2015 are the result of a shared commitment between the Conservatoire and its partners (the Hérault Department, the municipalities of Mauguio-Carnon and La Grande Motte, and the Pays de l’Or Agglomération).

This site will therefore provide valuable feedback for other sites within the network. A site narrative will help preserve the memory of the site’s history and organize a handover between different generations of stakeholders, building on the extensive consultation work that has been done. Furthermore, the site deserves ongoing local support to continue this dynamic of cooperation, maintaining its role as a pilot and innovative site in terms of flexible coastal management.

The project also plans to monitor the evolution of the environment under the influence of more flexible and spontaneous natural dynamics, as well as track users’ perceptions of the site in the context of using and appropriating a project of this kind. Finally, a forward-looking study will evaluate the relevance of different development scenarios for the Grand Travers, incorporating economic, biodiversity, landscape, environmental, societal, legal-economic, and administrative aspects.

Chronology

• December 2018: Adapto day in Occitanie, raising awareness among elected officials about a site developed for climate change adaptation: Le Petit et Grand Travers.
• 20 elected representatives from different areas attended and shared their experiences gained at Petit et Grand Travers.
• February 2019: Work by students from the Master’s program in Coastal and Marine Management at the University of Montpellier: collection of historical data generated during the consultation on the redevelopment project of the Lido de l’Or.
• May 2019: Aerial photo campaign using a kite.

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:

Located in the northeast of Cotentin between Barfleur and Cherbourg, the Val-de-Saire is a site with a remarkable landscape. It consists of rocky headlands, beaches with dune ridges behind which lie marshes, wet meadows, and heathlands. As such, the reefs and backshore marshes from Cap Lévi to Pointe de Saire are part of the European Natura 2000 network of sites.

The Conservatoire du littoral has been a major stakeholder on this site since 1983, when it made its first land acquisition. It currently owns more than 530 hectares in total. The maintenance and monitoring of its lands are entrusted to SyMEL (Syndicat Mixte des Espaces Littoraux de la Manche), which manages biodiversity monitoring and relationships with local stakeholders, notably agricultural operators inland through usage agreements.

The coastal area is typically frequented in the most accessible places for recreational activities (shore fishing, hiking, hunting, etc.), including the route of the long-distance hiking trail GR 223. This trail is threatened by significant erosion at certain points along its path.

Among concrete actions, the project aims to support local stakeholders in reconfiguring land uses by relying, among other things, on the measures implemented at the Fréval site (Fermanville) in the context of coastline retreat (notably the retreat of the coastal trail).

Fauna and flora

The Val-de-Saire plays an important functional role as a stopover site during migration, wintering, and nesting periods for many emblematic waterbird species. It is possible to observe the common shelduck, pied avocet, black-winged stilt, as well as three breeding species of plovers, which is remarkable at the departmental level. The backshore wetlands also host the great crested newt, and the dunes support a heritage plant species: sea kale.

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.