At sites with steep valleys of strong rock, even greater savings of material can be made by using arch dams, which transfer the pressure of the water to the sides of the alley. Cabora Bassa Dam, completed in 1975, on the Zambezi River in Mozambique, is 525ft (160m) high and used just over a million tons of concrete, which is only about a quarter of the amount needed for a gravity dam in the same position.
Most often, the arch dam is made of concrete and placed in a “V”-shaped valley. The foundation or abutments for an arch dam must be very stable and proportionate to the concrete. There are two basic designs for an arch dam: constant-radius dams, which have constant radius of curvature, and variable-radius dams, which have both upstream and downstream curves that systematically decrease in radius below the crest. A dam that is double-curved in both its horizontal and vertical planes may be called a dome dam. Arch dams with more than one contiguous arch or plane are described as multiple-arch dams.
Picture Credit : Google
