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    •         A list of almost 40 000 obstacles, including dams, locks, weirs, mills no longer in operation, etc., on French rivers has been drawn up to date. Obstacles are the cause of major transformations in the morphology and hydrology of aquatic environments and have a profound negative impact on the operation of ecosystems. They notably damage the diversity and quality of aquatic environments, create discontinuities, block the travel of migratory species, limit access to available habitats and disturb natural sedimentation processes.

ONEMA and the "Grenelle de l'environnement" commitments

Prevention of chemical pollution | Management of water resources | The blue corridor

3) The blue corridor

Commitment 73 I Green and blue corridor

    The "Grenelle de l'environnement" meetings on biodiversity and natural environments produced the concept of the blue corridor, similar to the green corridor linking large natural areas or serving as buffer zones. The blue corridors comprising rivers and water bodies, as well as continuous planted zones along and around them, are the means, with the green corridors, to create territorial continuity, considered an absolute priority.

Onema will contribute to mapping continuities and discontinuities on the national level over the next two years and to setting up regional corridors over the 2009-2012 period.

Commitment 112 I Acquire 20 000 hectares of wetlands to counter "artificialisation"

    Wetlands, which constitute exceptional reservoirs of biodiversity at the interface between aquatic and land environments, lie at the heart of the blue-corridor concept. They also play a role in protecting against flooding and are a natural self-cleansing system. Their preservation and restoral are required to prevent deterioration in water quality and to meet the qualitative and quantitative goals set for water in the river basin management plan for each hydrographic district. With the Water agencies, Onema is setting up the criteria for wetlands that could then be designated for priority purchases during a programme covering the years 2009-2015.

Commitment 113 I Grassy banks and planted buffer zones at least 5 metres wide along rivers and water bodies listed in urban-planning documents

     The grassy strips and planted buffer zones along rivers (riparian vegetation) are necessary conditions for the quality of aquatic habitats. They constitute a refuge and zone for the circulation of species. Their creation, or preservation, is also encouraged to intercept runoff and thus limit the transfer of polluting substances from cultivated fields to aquatic environments.

With Cemagref, Onema is working on a method to diagnose the effectiveness of buffer zones. In addition, Onema personnel inspect non-treated zones along rivers, in conjunction with the regional plant-protection services.

Commitment 114 I Restore continuity for freshwater ecosystems and eliminate the worst obstacles

An inventory of river obstacles in France

      The goal of the inventory carried out by Onema with several partners is to assess the degree to which each obstacle blocks the movement of species and sediment. It will identify the worst obstacles that will then receive priority status for their elimination or for the installation of systems to effectively reduce ecological fragmentation. A national data base will centralise all information on the obstacles. One part of the data (national code, precise geographical coordinates, essential characteristics) will serve as the shared base for the various stakeholders in water issues and territorial planning. A second part will be reserved for stakeholders in restoration and policing activities. It will include technical information required to determine the risks of ecological fragmentation.

Restore ecological continuity

With the Water agencies and the river-basin DIRENs, Onema participates in changes made to the river-basin management plans, notably concerning identification of biologically rich areas, in anticipating the revised river classifications, in the science-advice work on changes in the goals for water bodies and in preparing implementation of the programmes of measures. On the local level and particularly in the sub-basin management plans, Onema works to raise awareness of the need to restore ecological continuity and to encourage the emergence of public management capabilities to carry out the projects.

Commitment 55 I Develop renewable forms of energy taking environmental requirements into account

A public/private research programme to save the European eel

     In conjunction with efforts to restore ecological continuity, Onema is setting up a partnership with French hydroelectric producers to better understand the behaviour of eels and the impact of installations, notably hydroelectrical installations, on eel migrations and mortality. Observations and experiments are carried out in the field and in the lab to develop effective and operational means to modify installations. With a budget of almost 5 M€, in which Onema provides one quarter, this R&D programme will be included in the Eel management plan for France. The partners are Onema, Electricité de France, Compagnie nationale du Rhône, Société hydroélectrique du Midi (SHEM, a subsidiary of Electrabel, Suez group) and France Hydroélectricité. The steering committee is chaired by Onema.