A large model to test the dam project in Chablais
llustration of the future dam in its environnement © 2021 RTS
Presentation of a dam project on the Rhône between Bex and Massongex. RTS / 12h45 / 1 min.
In discussion for 40 years, the dam project on the Rhône between Bex (VD) and Massongex (VS) has just taken a step towards its realization with tests as close as possible to reality on a model. But it does not convince environmental organizations.
The planned development is a power station-dam called "low fall", as one meets on the Aare or the Rhine. A scale model of this hydroelectric bearing projected in the Chablais was created at EPFL to ensure the feasibility of the project.
"This physical modelling is first used to realize the dam and power plant concept," explains Giovanni De Cesare, Director of the PL-LCH hydraulic construction platform at EPFL, on Thursday at 12:45 pm." Then there’s optimization: you have to change a little bit to make it work better. And in the end, systematic tests are made of all the imagined load cases - floods, floating wood, low as well as high levels, normal exploitation".
Consumption of 20'000 households
This dam, which could be launched in 2026, will completely cross the river, with a power plant and a water intake located on the left bank of the Rhône. They will turbinate the water and return it directly downstream of the landing.
"It is estimated that the annual production will be around 80 million kilowatt hours," stresses Julien Derivaz, director of the company MBR SA. "This represents approximately the consumption of 20'000 households."
"Not the needs for tomorrow’s Switzerland"
But environmental organisations are not convinced by the project. They opposed the granting of water rights concessions by the cantons of Vaud and Valais last September.
"Today, what Switzerland lacks is winter energy, it’s high-tech energy," says WWF Valais Secretary-General Marie-Thérèse Sangra. "There, we have a project that will make energy run-of-the-river, that means all year round. These are not the energy needs of tomorrow’s Switzerland. So, yes, there is some skepticism about this project. '
However, WWF is not completely closed to the project. The organization is asking for guarantees on sediment loading and the transit of fish fauna, elements that this physical model of EPFL will allow to refine.