Institution d’Aménagement de la Vilaine

Institution d’Aménagement de la Vilaine (FA) is located in Brittany, the west of France, and involved in the freshwater pilot. The institute is, among others, responsible for the management of the Arzal dam, which is located at the outlet of the Vilaine basin (10,000 km²). The dam was built in 1970 to avoid floods that are caused by high river discharges and high sea levels. The dam also created a large water reservoir (50 hm3), which plays a central role in water supply for drinking and irrigation, sailing and fish by-passing. Mainly during the summer seasons, the management of the reservoir faces several challenges. One of the key problems is that the current system for preventing salt intrusion causes high freshwater losses. In addition, future water inflows and particularly the intensity and duration of low-flow or severe drought periods are uncertain. This raises the question: what is the best strategy for allocation of water among different users in case of restricted water availability?

In the DROP project the institute foresees the following measures:

  •  The design of a lock at the Arzal dam (including a physical model, detailed plans and evaluation of efficiency) for preventing salt intrusion and freshwater losses.
  • Development of an integrated tool for inflow and water quality management to support drought adaptation and decision making in the Arzal water reservoir (on the basis of existing hydrological forecasting tools and meteorological scenarios).

Pitch of Jean-Pierre Arrondeau – projectleader

For the implementation of the freshwater pilot, the institute closely collaborates with Water Authority Eifel-Rur (Germany). Drought experts of both organizations participate in six exchanges during which potential measures are designed, discussed and evaluated. The governance team of the DROP project will visit the region twice to define and evaluate the regional governance setting for drought adaptation measures.

For more information about this partner, visit the website of Institution d’Aménagement de la Vilaine