Dams are built to control, block, or divert the flow of rivers or other water bodies. Based on their structural design, dams are generally classified into four main types – Gravity Dams, Arch Dams, Buttress Dams, and Embankment Dams. In this article, we will explore what a Gravity Dam is and take a look at some famous examples from around the world.
What is a Gravity Dam?
Gravity Dams are designed and constructed in such a way that the weight of the dam structure is able to resist external forces. The main forces acting on a Gravity Dam include water pressure and uplift pressure.
Water pressure acts horizontally toward the downstream side, while uplift pressure acts vertically upward from beneath the dam’s foundation.
Uplift pressure is the pressure exerted by water as it seeps through the body of the dam or its foundation. It can reduce the effective weight of the dam, which is why proper drainage and foundation design are crucial.
Gravity Dams are typically built using concrete or masonry, although modern dams are most often constructed with concrete. These dams require strong, stable rock foundations to bear their immense weight. While the initial construction cost is generally high, Gravity Dams are known for their long lifespan and low maintenance requirements.
Some Gravity Dams have an arch-like structure. These are called Arch-Gravity Dams, as they combine the characteristics of both gravity and arch dams. A famous example is the Hoover Dam in the United States, built across the Colorado River.
(Also read: Types of dams | Advantages and disadvantages of dams)
Some famous Gravity Dams
Grande Dixence Dam
The Grande Dixence Dam, located in Hérémence, Switzerland, is the tallest gravity dam in the world. Made of concrete, it stands at an impressive height of 285 meters (935 feet). Completed in 1961, the dam stores water for several hydroelectric power stations. The combined installed capacity is approximately 2,069 MW.
Hoover Dam
The Hoover Dam, located in the United States, is an arch-gravity dam constructed on the Colorado River, at the border between Nevada and Arizona. Standing 221.4 meters (726 feet) tall, the dam supplies water to a hydroelectric power plant with an installed capacity of 2,080 MW.
Sardar Sarovar Dam
The Sardar Sarovar Dam, located in Gujarat, India, is a large concrete gravity dam built on the Narmada River. With a height of 163 meters (535 feet) and a length of over 1.2 kilometers, it is one of the largest dam structures in the world in terms of the volume of concrete used. The Dam has a total installed power generation capacity of 1,450 MW.