DIGUES

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.