Adapting a water intake to climate challenges

Over the years the water intake of the Vissoie auxiliary generator, owned by Forces Motrices de la Gougra (FMG), has suffered regular damage from bad weather. Past maintenance and interventions have focused on adapting the structure, in particular extending the water intake. This approach was intended to compensate for the gradual collapse of bed of the Navizence downstream and ensure the plant functions properly.

General view of the water intake after the bad weather in June 2024

Shortening, widening, anti-scour wall

In June 2024 further flooding of the river severely damaged the water intake, highlighting the need for a longer-lasting structural solution. A rebuilding project was carried out between October and December 2025. The main objective was to strengthen the structure given new hydraulic and climate constraints, to improve its lifespan.

The main work carried out was:

• shortening the downstream part of the water intake to improve its stability and response to flooding and to reduce the potential for damage.
• creating a deep wall downstream to provide effective protection against scour.
• widening the water intake to optimise its operation and hydraulic capacity.

This allows a buffer basin to form naturally downstream of the water intake as floods occur, without the risk of destabilising the structures.

Rebuilding the downstream ramp, with its anti-scour wall

Ready for the years to come

The water intake is now fully operational again. It is also more resistant to natural hazards and will be able to do its job in the long term. The rebuild marks an important step in securing the facility and illustrates HYDRO's commitment to adapting its customers' infrastructure to the current climate challenges.

Water intake in operation, after rebuilding work