A team of Swiss Federal Institute of Technology Lausanne (EPFL) engineers has completed proof-of-concept tests for the new 15-MW Massongex-Bex-Rhà´ne hydropower dam. The tests, involving a physical scale model and computer simulations, enabled the engineers to fine-tune their design.
Engineers at EPFL’s Platform of Hydraulic Constructions (PL-LCH) in Lausanne, Switzerland, tested the design. The tests began in November 2020 and were carried out on a scale model. They were used to calculate the design’s energy efficiency and make sure the dam will not impact the surrounding natural ecosystem, while reaching its hydroelectric potential. PL-LCH was commissioned by the company overseeing the MBR project.
The cantons of Vaud and Valais both granted operating permits for the new dam in September 2020, although some opponents have filed appeals.
By building and running tests on their scale model, the engineers will make sure the plant generates power from the river efficiently and with minimal disruption to the Rhà´ne’s natural river swells, sediment and fish populations. They used the test results to adjust the dam’s geometry so as to improve water flow and to study how sediment and floating objects will travel across the dam during swells.
The engineers’ model was built to 1:45 scale and measures about 5 x 12 m. It replicates around 550 m of the Rhà´ne river — 300 m upstream of the dam and 250 m downstream. It is made out of PVC except for the concrete river bed and banks. The engineers also added a mortar layer and gravel to the river bed and banks to simulate the rough natural texture. Gravel was also added to the water to model the sediment flowing in the river when it swells, as well as small pieces of wood to see how they would float across the dam.
“Our role is to make sure the dam, spillway, penstocks and outflow and discharge system work correctly from a hydraulic point of view,” says Giovanni De Cesare, a civil engineer and head of operations at PL-LCH. “We also developed a computer model of the dam so that we could run both physical tests and computer simulations. The computer simulations let us see the effects of changing the model’s structure, such as by adding groins to the existing river banks.”
Once it goes online in 2026, the hydropower plant is expected to generate 80 million kWh per year.
EPFL has over three decades of expertise in this area — the first studies it conducted for the MBR hydropower dam date back to 1987.