On the political roles of freshwater science in studying dam and weir removal policies: A critical physical geography approach

Simon Dufour
Université Rennes 2 – CNRS UMR LETG, Rennes, France; simon.dufour@univ-rennes2.fr

Anne Julia Rollet
Université Rennes 2 – CNRS UMR LETG, Rennes, France; anne-julia.rollet@univ-rennes2.fr

Margot Chapuis
Université Côte d’Azur – CNRS UMR ESPACE, Nice, France; margot.chapuis@unice.fr

Mireille Provansal
CNRS UMR CEREGE – Université d'Aix Marseille, Aix en Provence, France; mireilleprovansal@wanadoo.fr

Romain Capanni
CNRS UMR CEREGE – Université d'Aix Marseille, Aix en Provence, France; romaincapanni@hotmail.fr

ABSTRACT: Over the last decade, dam and weir removal has been promoted to improve continuity along many river systems. However, such policies raise many socioecological issues such as social acceptability, integration of different river uses, and real impacts on river ecosystems. In this article, we illustrate how critical physical geography can help connect sociopolitical issues with biophysical processes. Our analysis is based on case studies located in different geographic contexts but in any case, a detailed understanding of biological or hydromorphological processes emphasises different social and political issues related to dam and weir removal. For example, riparian vegetation is usually ignored in dam-removal studies (unlike fish or macroinvertebrates) and its response to dam removal raises the issue of how different nonhuman actors are represented (or not) in the debate and weighed in the decision. An accurate understanding of sediment dynamics can also address the sociopolitical process because it identifies effective measures for reaching an objective such as the restoration of sediment fluxes. In our case studies, this understanding demonstrates that removal can be technically possible but ineffective or insufficient. From a sociopolitical perspective, this can increase the number of stakeholders (with diverse power relationships) that need to be included in the debate. We conclude that the diversity of sociopolitical issues associated with dam and weir removal is partially connected to the nature of biophysical processes and patterns and that neither aspect can be analysed separately.

KEYWORDS: Sediment transfer, riparian vegetation, dam removal, critical physical geography, France