Environmental restoration of the river Drac / PAPI Drac

Revenir à un fonctionnement plus naturel de la rivière

Located upstream of the city of Grenoble, the Drac is a mountain river which, over the decades, has been the subject of numerous developments, particularly hydropower.

Under the pressure of urban development, its course has been greatly impacted. Today, as part of a flood prevention action programme (PAPI), a return to a more natural river flow is being considered, both to improve flood absorption and to restore the area’s biodiversity.


As part of the flood prevention action programme (PAPI) run by Symbhi (Isère basin Agency), the Drac will undergo major changes in the 35km stretch of its course from Notre-Dame-de-Commiers, upstream of Grenoble, to Saint-Egrève downstream, where it meets the River Isère. While the main target of this programme is to improve the protection of people and property against flooding, the way in which this is achieved is part of a very contemporary sustainable approach that places great importance on the natural flow of rivers and the preservation of their biodiversity. Experience has shown that channelling rivers, cutting off their loops and narrowing their beds are not the best long-term solutions.

As a member of the consortium, Artelia is playing a major key role in the study of these new developments on the Drac, which aim to restore a natural morphological erosion dynamic while relying on re-meddling, expansion, sediment transport and ecosystem development processes… Using hydraulic and hydrosedimentary models, our teams are currently studying the best way of restoring the width of the minor bed, recreating braids to facilitate its flow and enable better sediment management, and removing the heavily vegetated banks resulting from the artificialization of the watercourse, which currently hinder flood evacuation. Part of this programme also involves recreating areas of good ecological functioning. Various species are to be replanted over an area of almost 10 hectares to consolidate the banks and recreate biological corridors in which animals can move more easily.

Artelia is mobilising its numerous skills in hydraulics and hydrosedimentation, hydrogeology, geotechnics, flood management, the environment and civil engineering to find the best development solutions. The balance of the project is all the more sensitive given that, over the 35 km, the Drac flows through a protected natural area, a water catchment area that is essential for supplying the conurbation’s drinking water, and various urbanised and industrialised areas.