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How the Gornerli project is using valuable glacier meltwater sensibly

In the case of hydropower, the backbone of Switzerland’s energy supply, a “yes” vote on the Electricity Act would prioritise the implementation of the 16 Hydropower Round Table projects. By far the most important of these is the Gornerli multi-purpose reservoir near Zermatt. As well as supporting security of supply, this multi-purpose reservoir could also use the run-off water from the Gorner Glacier in a number of ways. Here, we get the expert insights of Professor Emmanuel Reynard from the University of Lausanne.

Professor Reynard, you and your team at the University of Lausanne are researching the multifunctionality of alpine hydropower infrastructure. What exactly does this mean?

Most dams in Switzerland were built for a single purpose: to generate power. When the concessions were granted, some longstanding uses of water were protected, such as irrigating meadows in the Valais. Over time, the reservoirs have been granted additional uses, such as supplying drinking water or producing artificial snow. The dams have also been incorporated into flood protection concepts. Some uses, such as climbing the dam wall, use the infrastructure rather than the water. We’re studying the multifunctionality of the alpine dams from different angles: the history of the multiple uses of water, when the new uses emerged, the perceptions of the role of water and energy by different stakeholder groups, as well as institutional aspects of multifunctional water management, in particular the role of concessions.

The Gornerli project is considered the largest and most important of Switzerland’s 16 Hydropower Round Table projects. How would you assess the project’s multifunctionality and what value would it add?

This project clearly has great potential for energy production due to the vast volume of water in the catchment area. It also plays an important role in managing hydrological risks in the Matter Valley. It serves as a drinking water and irrigation reserve for the municipalities of Zermatt, Täsch and Randa. As the structure is incorporated into the Grande Dixence storage power plant, it could supply Lac des Dix with water.

What role does the Gornerli project play in generating hydropower?

The water from the new lake will be pumped into the main Grande Dixence collector, so there’s no need to build a new power station. Currently, 146 million cubic metres of water flows in from the Gornera, 115 million cubic metres of which is taken from the Z’Mutt plant. Thanks to the new dam, all the water will be able to flow into the Grande Dixence. This will make a significant contribution to winter energy production, which is one of the key objectives of the new Electricity Act. The Gornerli dam alone would produce a third of the additional winter electricity envisaged by the Hydropower Round Table projects.

The Gornerli project is also considered crucial for flood protection in Zermatt and the Matter Valley. To what extent will it reduce the risk?

Zermatt is a highly urbanised area, with residential buildings very close to the river, making them extremely vulnerable. Peak flooding during thunderstorms, intense snowmelt or the sudden, uncontrolled discharge from an underground glacial lake, as happened with the Triftbach in July 2019, pose a major risk to the town. The construction of a reservoir upstream would act as a retention structure, thus reducing the risk. 

The glaciers represent an important water reservoir. As they continue to melt, it will become increasingly important in the future to ensure a secure supply of drinking and process water in the region. What contribution can Gornerli make to this?

The construction and networking of water reservoirs is one of the keys to adapting water management to climate change. Due to their large capacities, alpine reservoirs constitute important infrastructure for the integrated management of water resources. With this in mind, the construction of a new reservoir near Zermatt can only have a positive impact on integrated water management. But we must not forget that true integrated management not only needs to ensure a long-term water supply, but also optimise the demand for water, in particular through organisational measures and water savings. 

About

Emmanuel Reynard is Full Professor of Physical Geography at the University of Lausanne. One of his main areas of research is alpine water resource management. He and his team are currently working on a project on the “Multifunctionality of alpine hydropower infrastructures”. Alpiq is co-financing the project but is not involved in the actual research.

About the project

The Gornerli project is the largest from the hydropower round table as it would supply 650 GWh of additional winter energy and 200 GWh of additional production - enough to supply around 140,000 households with electricity for a year. This means it would be able to supply a third of the additional hydropower needed in Switzerland during winter by itself. The project is implemented by Grande Dixence AG, in which Alpiq is the majority shareholder. The municipality of Zermatt, the municipalities of the Matter valley, all other concession municipalities of the Grande Dixence and other partners are all closely involved in the project and are in favour of it. 


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