INFLUBIO

Biodiversity management within the framework of transformation and maintenance of waterway infrastructures, in a context of ecological crisis
ITTECOP Apr 2017
Projet: Recherche
Achevé

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Gabrielle
BOULEAU
/ Organisation: IRSTEA Bordeaux
gabrielle.bouleau@irstea.fr

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Synthèse
Rapport final

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Biodiversity management within the framework of transformation and maintenance of waterway infrastructures, in a context of ecological crisis

This INFLUBIO research report studies how the mechanisms for taking biodiversity into account are understood by the actors involved in the Seine-North Europe Canal project, based on work on the categories used to govern the material realities (wetlands, protected species, wooded areas, etc.) that we call motives.

The Seine North Europe Canal (CSNE) project was launched in the 1990s but its realization was still uncertain when we started our research project in 2017. The last canal built in the region and which we have taken as a point of comparison is the Canal du Nord, completed in 1965 before the major environmental laws. The new canal is subject to an impact study, a water law impact note and the implementation of the avoid, reduce, compensate sequence for the preservation of biodiversity. As such, the project avoids the Somme valley by means of a canal bridge. It reduces the impact on the water by making the canal completely watertight, a reservoir dam filled in winter by pumping into the Oise, and a siphon system to limit losses through locks. It reduces the loss of biodiversity by providing lagooned banks on part of the canal's length. Finally, it plans to restore the Tortille river and the wetlands of the Oise to compensate for the residual loss of biodiversity.

Presented as a major project to mitigate climate change through modal shift, supported by the European Union and creating jobs in a disadvantaged region, CSNE has received little public criticism. The actors who participate in its environmental observatory are rather satisfied to see some of their proposals included in the project.  The other environmental actors have difficulty in grasping all the information on the project and its impacts and are afraid of taking responsibility for a further postponement of the project by voicing their criticisms. For all these reasons, biodiversity is relegated to the background of the project and the associated fears are little relayed in public debates.
We conducted 31 semi-directive interviews with 29 people involved as experts or spokespersons in the governance of biodiversity in the field studied. In the course of our survey, we also interviewed stakeholders on the governance of biodiversity on the Canal du Nord. This allowed us to benefit from feedback on an already existing canal, but also to understand what is at stake in the management of environmental issues within the framework of the Seine Nord Europe Canal as a canal built on no existing watercourse and of a relatively new length.
It emerges from this survey that the stakeholders perceive biodiversity both through environmental realities enshrined in law (established motives) and other realities (contours under debate) linked to the project whose definition (temporality, scale, location, contour) poses a problem because they could impact established motives or which, according to the stakeholders, give rise to hopes or concerns.

As regards the established motives, the stakeholders trust contractual tools for managing farmland, hedges and paths, but for the management of forests, watercourses and wetlands, legislative tools are the most frequently mentioned. The WFD, SAGEs and SDAGEs are very rarely cited by the stakeholders interviewed as instruments for the governance of wetlands and watercourses. In the field studied, there is no emblematic protected species that would federate opposition to the canal. The Symbiose association is carrying out political work to bring together the interests of preserving agricultural land with the preservation of biodiversity. On the wetlands, compensation for the loss of biodiversity in these environments remains a divisive issue.

The contours under debate concern the project itself, whose temporality is often questioned, the biodiversity promised by the canal (living canal and lagoon banks) and its maintenance, the location and operation of multimodal platforms (areas of economic activity, nature of goods flows, river share, road share, locally produced share, outlets), hydrological resources (underground and surface) and their quality in relation to the needs and operation of the canal, the crossability of the canal and the fragmentation of habitats, the landscape of the worksite (right-of-way, embankments, cuttings), the management and knowledge of the spaces concerned by the compensatory measures over time, the reality of modal shift and the energy balance of the canal, incidents in the life of the canal (invasive species, drowning, leaks, waste) and the modification of runoff or mudflows following the digging of the canal or the land development that will accompany it. These realities are considered to be only partially managed by the instruments of public action.

Our analysis has made it possible to classify these concerns according to the type of actors, their interests and their positions vis-à-vis the project (for, against, in negotiation).

Taking into account the interdependencies between these motives and contours under debate, we constructed three biodiversity alert scenarios that highlight the uncertainties about the cost of maintaining the constructed biodiversity, the uncertainties about water resources in the face of climate change and the risk of a rebound effect on road traffic and intensive agriculture. We have collected the responses that the contracting authority intends to provide to these alerts in order to build a more integrated and optimistic scenario.