Grande Dixence Dam

In brief

At 2,365 meters above sea level, in the Swiss Alps, the Grande Dixence is the tallest gravity dam in the world. This gigantic concrete wall holds back the meltwater of dozens of glaciers.

How does it work?

To fill this lake of 400 million cubic meters, the Swiss did a titanic job:

• Under the mountain, 100 kilometers of galleries collect the water of 35 glaciers, including those near Zermatt and the Matterhorn (a tooth-shaped mountain), to bring it to the lake.
• The water is then sent to the Bieudron power plant down a very high drop of 1,883 meters, one of the highest in the world for a plant of this type. It hits turbines among the most powerful in the world.

Key facts

• Height: 285 m, almost the Eiffel Tower (330 m with the antenna).
• Concrete: 15 million tonnes.
• The dam was built from 1951 to 1961 (the project was completed later); each winter, work stopped for months because of frost and snow.

Words to know

• Glacier: an enormous mass of ice that moves very slowly.
• Altitude: height above sea level.

Did you know? At the bottom of the lake lies an old dam, the Dixence dam, built in the 1930s. When the big dam was filled, the small one was swallowed up, and it still sleeps there!

Going further

The lake of the Grande Dixence is not filled only by the valley right behind the dam. A network of galleries and water intakes also collects water from torrents in several neighboring valleys, sometimes by pumping it, and brings it to the lake. A dam is therefore not always fed by "its" river alone.