CE03 - Interactions homme-environnement

DIGUES (Dykes, Interactions, Management, Uses, Environment and Scenarios): what transitions in maritime and river embankment systems in France in the 21st century, between uses, landscape, nature and protection? – DIGUES

DIKES

What transitions in maritime and river embankment systems in France in the 21st century between uses, landscape, nature and protection?

General objectives and main issues :

France is at a turning point in the relationships between society and its 9,000 km of sea and river dykes. Long seen as merely technical features providing flood defence, dykes are now viewed more holistically to include also uses, the landscape and nature. From 2018 onwards, responsibility for flood protection will be devolved to the local authorities (with the GEMAPI regulation). Supporting local stakeholders in this context of change will mean looking at the full range of issues and reflecting on the various dyke management orientations, some of which are new in France, from closing to opening, raising to lowering, and from artificialization to ecological restoration. This will require us to consider the complete embankment system – not only the dykes but the embanked territories that they protect too, along with the pre-dyke area. The first objective of our consortium is to establish new proposals for the future of dykes and to assess the conditions for feasibility and acceptability of these proposals. These could take several directions, or a combination of orientations, in the areas of hard or soft flood defence, vegetation management, public access and patrimonialization. These proposals and their conditions will be delivered in the form of transition scenarios for embankment systems. Based on the scenarios established site by site, in fluvial (Loire, Marais Poitevin and Seine & Marne) and coastal environments (Dives, bays of Veys and Authie), we will build generic, reproducible scenarios. Given the methodological challenge it involves, the production of these scenarios is also one of the project’s objectives. The third objective is to test the ‘tools’ that will help us build the scenarios: role play, landscape mediation, comparison and history.

To achieve the scientific objectives of the program, a plurality of human and social sciences have been called upon. Each of them has a specific role to play: physical geography and ecology will focus on questions of defense and nature; landscapers will work more specifically on landscape issues; uses will be studied by several disciplines; finally, the question of GEMAPI will be the subject of a study in political science.
Specific methods will be associated with each of these disciplines. We will use traditional methods of data collection in the form of observations and field surveys (topographic and biogeographic measurements), or through social surveys (semi-structured interviews and questionnaire). Certain methods constitute both data collection and facilitation methods, which will help us construct the transition scenarios of French containment systems in the 21st century (landscape mediation, comparison between environments and between sites, study of archives history, determination of willingness to pay, implementation of a role play).
In addition, collaboration with local stakeholders and exchanges of good practices with managers and engineers, if possible from the Netherlands and England, will help us to refine our scenarios.

Main results :

Two years after the start of the program, data collection is underway, or even completed, and landscape mediation and participatory simulation procedures have been launched in the Marais Poitevin and the Marshes of the Dives.

We also carried out a multi-criteria comparison of experts from our seven study sites, with regard to the four issues of the program (defense, nature, landscape and uses), themselves evaluated in five criteria (each broken down into four modalities). This quantitative method complements the qualitative study we carried out at each site. The results show that we have chosen relevant study sites because other issues than just defense against flooding are currently taken into consideration. Two groups stand out among our sites. In the first, the combination of issues of nature and issues linked to uses predominates, which are either on an equal footing (Marais poitevin, Baie des Veys, Uxeloup), or dominated by issues of nature (Baie d'Authie) with landscape or defense issues set back (respectively bay of Authie; Marais poitevin - bay of Veys). A second group gives the opposite image: defense issues are important there, associated either with landscape issues (Seine, Jargeau), or with issues linked to uses (Dives), while nature issues can be very low ( Seine and Jargeau). This quantitative study clearly highlights the need for a global consideration of dikes and for attention to the interaction of their issues, still largely underestimated. This underestimation is confirmed by social surveys and field surveys and by the analysis of the word «dike (s)« in the newspaper Le Monde, from 1944 to the present day.

Taking better account of the multi-functionality of dikes will make it possible to respond simultaneously to societal demands (more nature, diversification of uses, help with the introduction of the GEMAPI competence, etc.) and to the imperatives of climate change.

At the end of the programme, we will be able to characterize possible trajectories for embankment systems - particularly towards softer management methods, partially based on nature -, and assess their level of acceptability depending on the population and environment type, the issues at stake, the possible orientations and the facilitation methods. We will also be able to evaluate the sustainable quality of the embankment systems in the territories; these systems are no longer seen as merely technical features and are now viewed from several angles. Finally, the programme will help bolster France’s position in European debates on dykes, showing that it can provide new input on the acceptability of innovative solutions, defined using an approach that goes beyond the economic and safety aspects.

CONFERENCES :

- Bertrand F., Goeldner-Gianella L., Les systèmes d'endiguements littoraux en France entre adaptation et innovation, OCEANEXT, 2e Conférence internationale pluridisciplinaire 3-5 juillet 2019, Nantes.

- Goeldner-Gianella L., La dépoldérisation dans les marais littoraux d'Europe occidentale et de France : quelles entraves sociales et quelles solutions ?, Colloque international Adaptation des marais littoraux au changement climatique, 27-29/11/18, La Rochelle.
maraislittoraux.myportfolio.com/lydie-goeldner-gianella

- Gautier E., 2020. Digues, Interactions, Gestion, Usages, Environnement et Scénarios –Trajectoire d’une levée en milieu rural. Etablissement Public Loire, échanges recherche-gestion oct. 2020 / Intégration environnementale des infrastructures de protection contre les inondations.

- Gautier E., Ferradou L., Cavero J., Virmoux C., Douillard T., 2020. Trajectoires des systèmes d’endiguement – Le cas d’une levée ligérienne de milieu rural, 20e colloque des Zones Ateliers.

- Pernet A., 2020, « Sédimenter les expériences, des monts du Forez au Marais mouillé », Webinaire Le paysage au cœur des démarches participatives, réseau paysage Nouvelle-Aquitaine, 10 décembre 2020.

DIGUES: What transitions in maritime and river embankment systems in France in the 21st century between uses, landscape, nature and protection?

France is at a turning point in the relationships between society and its 9,000 km of sea and river dykes. Long seen as merely technical features providing flood defence, dykes are now viewed more holistically to include also uses, the landscape and nature. From 2018 onwards, responsibility for flood protection will be devolved to the local authorities (with the GEMAPI regulation). Supporting local stakeholders in this context of change will mean looking at the full range of issues and reflecting on the various dyke management orientations, some of which are new in France, from closing to opening, raising to lowering, and from artificialization to ecological restoration. This will require us to consider the complete embankment system – not only the dykes but the embanked territories that they protect too, along with the pre-dyke area. The first objective of our consortium is to establish new proposals for the future of dykes and to assess the conditions for feasibility and acceptability of these proposals. These could take several directions, or a combination of orientations, in the areas of hard or soft flood defence, vegetation management, public access and patrimonialization. These proposals and their conditions will be delivered in the form of transition scenarios for embankment systems. Based on the scenarios established site by site, in fluvial (Loire, Marais Poitevin and Seine & Marne) and coastal environments (Dives, bays of Veys and Authie), we will build generic, reproducible scenarios using interdisciplinary study and facilitation methods, while collaborating with local stakeholders and exchanging best practices with British and Dutch engineers. Given the methodological challenge it involves, the production of these scenarios is also one of the project’s objectives. The third objective is to test the ‘tools’ that will help us build the scenarios: role play, landscape mediation, comparison and history. In terms of results, we will be able to 1) characterize possible trajectories for embankment systems, and 2) assess their level of acceptability depending on the population and environment type, the issues at stake, the possible orientations and the facilitation methods. 3) We will also be able to evaluate the sustainable quality of the embankment systems in the territories; these systems are no longer seen as merely technical features and are now viewed from several angles. 4) Finally, the programme will help bolster France’s position in European debates on dykes, showing that it can provide new input on the acceptability of innovative solutions, defined using an approach that goes beyond the economic and safety aspects. Three barriers need to be lifted. 1) To make sure that the diversity of sites, messages and disciplinary approaches involved in the programme does not become a handicap, we will take a cross-disciplinary approach wherever possible and, during the seminars, set aside time to cross the intermediary results and build scenarios. 2) We will also need to take down the socio-political barriers that may emerge in the event of a major hydrological crisis or that are included in a survey or scenarios that evoke fairly unacceptable techniques: we will have to explain that our methodology is open and impartial, and that our scenarios are scientific proposals and not obligations. 3) We will need to move from the particular to the general to progress from the sited scenarios to generic scenarios They will reproducible because we will be able to identify which variables lead, in theory, to which scenario, and determine which scenarios are possible in a territory and under what conditions.

KEYWORDS: dyke, landscape, scenarios, multi-stakeholder approach, ecosystems/socio-economic systems interactions, sustainable management.
PARNERS: LGP, LAREP, PRODIG, LADYSS, CRH, LIENSs.

Project coordinator

Madame Lydie GOELDNER-GIANELLA (Laboratoire de Géographie Physique : Environnements Quaternaires et Actuels)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LGP Laboratoire de Géographie Physique : Environnements Quaternaires et Actuels
LAREP Laboratoire de recherche en paysage
CRH-UMR8558 Centre de recherches historiques
LADYSS Laboratoire dynamiques sociales et recomposition des espaces
PRODIG Pole de recherche pour l'organisation et la diffusion de l'information géographique
LIENSs Littoral, Environnement et Sociétés

Help of the ANR 509,998 euros
Beginning and duration of the scientific project: December 2018 - 48 Months

Useful links

Explorez notre base de projets financés

 

 

ANR makes available its datasets on funded projects, click here to find more.

Sign up for the latest news:
Subscribe to our newsletter