Reservoirs increasingly vital for flood protection

The Grande Dixence dam, here the gravity dam (1951-1961), collects water from 35 glaciers in Valais. Grande Dixence

Reservoirs are not solely used for electricity generation; they are becoming crucial for flood protection.

The planned “Gornerli” power plant, situated above Zermatt at the base of the Gorner Glacier, exemplifies this dual purpose. Designed with flood protection in mind, the reservoir will not only generate energy but also serve as a retention basin during storms.

+Our science newsletter: Swiss research in a global context. Our newsletter presents the latest developments in a bite-size format. Stay curious.

The “Gornerli” project is a practical implementation of this idea. Professor Robert Boes, a hydrology expert at the federal technology institute ETH Zurich, explains that modern reservoir designs incorporate flood protection by ensuring they are never completely filled, allowing for additional water collection during storms.

Visualisation of the planned “Gornerli” dam with a height of 85 metres, which is to be built in the gorge that was exposed after the glacier melted. made available

Existing hydropower plants in the Alps already help mitigate flooding. However, since these plants primarily focus on electricity production, they are often quite full, depending on the season. Professor Boes suggests that setting a maximum water level at these facilities could enhance their protective function.

Dangerous glacial lakes

The integration of electricity production and flood protection will likely become even more critical in the future, especially in light of climate change. Professor Emeritus Wilfried Häberli of Glaciology warns that the current situation in the Alpine region is unprecedented and will likely persist, necessitating preparedness for new risks.

Melting glaciers are forming glacial lakes, which pose a danger if landslides trigger tidal waves. One possible solution is constructing a dam further down the valley, though Professor Häberli points out the reluctance to finance such projects for potentially rare events. Consequently, the concept of multi-purpose facilities—reservoirs that serve both electricity generation and flood protection—has been developed.

Political action needed

Switzerland leads scientifically in this area, but political action is essential to establish the necessary framework, Häberli urges. “We have the fundamental knowledge and know where these lakes are forming. Immediate planning is crucial,” he emphasises.

Adapted from German with DeepL/amva