Constructing the World’s Most Impressive Dams

Dams are built to control water flow by strategically placing earth, rock, and concrete structures as barriers. The water collected from dams is used for a variety of purposes, including agricultural irrigation and municipal water supplies. According to the Association of State Dam Safety Officials, most dams (31.3 percent) are built for recreational purposes, followed by fire and farm ponds, flood control, irrigation, and water supply.

Types of Dams

A dam’s design depends upon its purpose and location. For example, an arch dam is best for high, narrow gorges so that the arch of the structural shape provides strength. Gravity dams are often chosen for shallow, wide canyons. Alternatively, overflow dams block flow in a stream and harness water for generating power, to improve navigation, and to provide irrigation water.

Dam Construction

When designing and constructing a dam, these are the four basic steps that engineers follow:

1. Divert the water, typically through a tunnel, in the dam’s construction site. Place explosives in the drill holes and then remove broken rock until the tunnel is complete.
2. Use earth-moving equipment to build a dam upstream to cause the river to flow through the tunnel. Build another dam downstream to prevent water from flowing back into the construction area.
3. Remove loose rock from the river bed and construct a concrete footing to prevent leakage around the edges of the dam.
4. Coordinate dam construction with building the power station and intake works. Once the dam is complete, close the tunnel to allow a lake to form. Consider building dewatering outlets so that water could be released in case of emergency.

Dams around the World

As some of the largest constructions that humans have ever made, dams are clearly an amazing feat of engineering. These are some of the most impressive dams around the world:

• Hoover Dam, Nevada – Named after U.S. President Hoover, the Hoover Dam has been a National Historic Landmark since 1985. Over 100 people died during while constructing the dam, which stands at 221 meters high and 200 meters thick at the base.
• Three Gorges Dam, Sandouping, China – This is the world’s largest hydroelectric dam and the world’s single largest source of electricity. It’s also one of the most controversial dams in the world, as hundreds of villages had to be submerged and millions of people displaced during its 12-year construction period.
• Nurek Dam, Tajikistan – Standing at 300 meters tall, the Nurek Dam is the tallest dam in the world. It was completed in 1980 and is located on the Vakhsh River.
• The Netherlands North Sea Protection Works – This is a complex system of dams, floodgates, and storm barriers that allows the Dutch to hold back the North Sea. Two separate construction projects went towards protecting the area where the Meuse and Rhine Rivers flow into a delta.
• Syncrude Tailings Dam, Alberta, Canada – In 2001, this embankment dam was noted to be the largest earth structure in the world by volume of construction material. It is located north of Fort McMurray in Alberta and is utilized in the extraction of oil from the Athabasca Oil Sands.

Photo credits: Ville Miettinen and Kathy via Flickr