31 Oct Difference Between Dam and Barrage
At first glance, you may confuse a barrage and a dam. Both are built across large bodies of water to control the water level. However, they have very different construction processes and uses. We’ve put together some fast facts about the difference between a dam and a barrage and you’ll also learn about the largest dam that exists in the world today. Can you guess which country it’s in?
What is a Dam?
A dam is a barrier that is constructed across a river valley or water source.
A dam creates a deep reservoir of water that can be stored and used at a later date. These uses can include irrigation, water supply or even electricity generation. A dam is usually an impressive feat of construction, as its sheer height is what keeps the water from moving up and over it. Unlike a barrage, a dam is built for the sole purpose of storing water and to raise the level of water contained within it.
What is a Barrage?
A barrage is a type of dam; however, instead of being a massive concrete wall that the water can’t flow over, the barrage is full of gates.
These gates are opened and closed to directly control the amount of water that passes through it. Having a barrage instead of a dam means that the flow of water can be kept stable for its intended purpose, such as irrigation to nearby cities, towns, or farmlands. Unlike a dam, the water stored behind a barrage depends on the height of its gates and not the height of the entire wall. The flow and level of water are easily monitored because the gates can be easily manipulated.
A barrage is constructed when water doesn’t need to be stored but rather diverted. For this reason, the barrage is usually built across a flat and relatively slow-moving river. Unlike a dam, which will raise waters nearly to its height, a barrage will only raise the water level by a few feet. This is also useful for navigation, because a barrage can increase the depth of a river by a few feet.
A dam is built with numerous spillways that allow excess water to flow through it to the river below. This keeps the dam from being overtaken when the reservoir or lake reaches the top of the dam.
Dams have gates just as barrages do, but the difference is that dams have the gates and sluices at the top to prevent flooding and spillage.
In barrages, there are gates from the top down to the bed of the river. This allows for a greater capacity of storage and controlling the flow of water. Barrages are particularly common in rivers that see a large amount of flooding.
The Largest Dam in the World
The largest dam in the world is the Three Gorges Dam in China. The Three Gorges Dam stretches across the Yangtze River and is a whopping 1.4 miles wide and 630 feet tall. The dam can hold back more than five trillion gallons of water.
The Three Gorges Dam gets its name from the three gorges at the foot of the nearby Wu Shan Mountains. The project itself has always been shrouded in controversy when its construction in 1992 displaced 1.13 million people that were living in the 244 square miles that was subsequently flooded by the dam. The floodwaters flooded entire towns, farmland and even historical sites. Not only that, but the sheer weight of the water has reportedly been eroding the shores of the river.
Landslides and toxic buildup are cited as growing concerns around the dam, but the government and industry say it’s necessary to support growing energy demands in China. Deadly flooding on the Yangtze River is also controlled by the dam. During the 2010 typhoon that struck the area, the Three Gorges Dam withstood 18,492,043 gallons of water per second.