A dam is an artificial barrier to a course of water that serves to regulate the flow of a natural waterway, protect a stretch of coast or a port, or form a basin or reservoir for a hydroelectric power plant.
Dams feature an intake, tunnels or channels, overflow measures for excess water and outflow. They can be a few dozen meters tall up to hundreds of meters tall: structures over 15 meters high or with a reservoir volume (maximum storage capacity) over a million cubic meters are generally considered large dams.
The highest dam in the world is currently Jinping -1, on the Yalong River in China, at 305 meters high. This will be surpassed by the Rogun Dam in Tagikistan, coming in at 335 meters high once its construction is complete. The dam with the highest water flow is the Kariba Dam, on the Zambezi River, between Zambia and Zimbabwe: it’s 128 meters high and 579 meters long, for a capacity of 185 billion cubic meters.
Types of Dams
Dams can be divided into two main categories: gravity dams and arch dams.
Gravity dams: generally, these have a triangular or trapezoidal vertical section, and a horizontal section with a straight, or sometimes curved, axis. The dam’s stability and resistance to hydrostatic pressure rely solely on the weight of the structure.
Arch dams: convex in shape, most of the hydrostatic pressure of the reservoir water is transferred to the side abutments of the dam itself and so to the sides of the valley or mountain where it is located. Because of these characteristics, arch dams are generally constructed across relatively narrow valleys with rocky sides, or in any case, where there are stable natural supports.