Behold the Grande Dixence Dam in Valais, Switzerland, the tallest gravity dam in the world with a height of 935 feet (285 m):
Here are a bunch of photos from the ground to give you a better sense of scale and height. Helicopter tour here. The hydroelectric dam generates power for more than 400,000 Swiss homes. Most of the water comes from Alpine glaciers when they melt during the summer.
So what’s a gravity dam exactly? CivilEblog, a civil engineering blog platform, explains:
A gravity dam is a massive sized dam fabricated from concrete or stone masonry. They are designed to hold back large volumes of water. By using concrete, the weight of the dam is actually able to resist the horizontal thrust of water pushing against it. This is why it is called a gravity dam. Gravity essentially holds the dam down to the ground, stopping water from toppling it over.
Gravity dams are well suited for blocking rivers in wide valleys or narrow gorge ways. Since gravity dams must rely on their own weight to hold back water, it is necessary that they are built on a solid foundation of bedrock.
The other types of dams outlined in the post are Earth, Rockfill, Arch, Buttress, Steel, and Timber.
(See all Orbital Views here)