La restauration écologique du fleuve Rhône sous le double regard du sociologue et de l'écologue

Acté en 1998, le Programme décennal de restauration hydraulique et écologique du Rhône s'est fixé comme objectif principal d'augmenter les débits réservés dans les bras court-circuités du fleuve. Cet objectif était initialement pensé comme une action de restauration écologique de milieux naturels fortement perturbés. Un processus concomitant de concertations a plusieurs fois déplacé l'intérêt initial vers des projets d'élaboration d'un territoire fluvial, puis d'un outil de gestion contre les crues. L'approche interdisciplinaire appliquée, entre sociologie et écologie, interroge la capacité d'une telle action environnementale à aboutir à des résultats hybrides, relevant à la fois de l'amélioration d'un écosystème fluvial et d'un processus de gouvernance. / A ten-year physical and ecological restoration programme was defined for the Rhone River in 1998. Initially, one of its main objectives was to increase the minimum flow in several by-passed sections, with the clear goal of improving the fluvial habitat and the general ecological functioning of the river. A complex consultation process which brought together the hydropower industry, regional civil organisations, and local civil representatives was adopted to define more precisely the local measures to be taken. In the course of this process, the programme underwent a progressive change from purely ecological to more socially motivated outcomes such as improving amenity values and flood defence. We studied how increasing the minimum flow is a topic that can or cannot be discussed by the actors during the consultation process. For example, there is less discussion about the ecological value than about the economic value of the restoration programme between the hydropower industry and the local elected members. But, the various actors readily debate with the scientists about floods and sedimentary transport, linked with local knowledge. We applied a multidisciplinary approach, involving sociology and ecological sciences, to question the restoration programme and to analyse its hybrid results in terms of both the ecological and amenity values and at the same time to understand the governance process