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At first glance, you might confuse a barrage with a dam. Both are constructed across large bodies of water to control the water level. However, they have very different construction processes and uses. Here are some quick facts about the differences between a dam and a barrage, and you'll also learn about the largest dam in the world today. Can you guess which country it's in?
A dam is a barrier constructed across a river valley or water source to create a deep reservoir of water. This stored water can be used for various purposes, including irrigation, water supply, and electricity generation. Dams are impressive feats of construction, relying on their sheer height to prevent water from flowing over them. Unlike a barrage, a dam is built solely for the purpose of storing water and raising the water level within it.
A barrage is a type of dam, but unlike a massive concrete wall that prevents water from flowing over, a barrage is equipped with gates. These gates can be opened and closed to directly control the amount of water passing through. Using a barrage instead of a dam allows for stable water flow, which is useful for purposes like irrigation to nearby cities, towns, or farmlands. The water stored behind a barrage depends on the height of its gates rather than the height of the entire structure. The flow and level of water are easily monitored because the gates can be easily adjusted.
A barrage is constructed when water needs to be diverted rather than stored. Therefore, it is usually built across a flat and relatively slow-moving river. Unlike a dam, which raises water levels nearly to its height, a barrage raises the water level by only a few feet. This feature is also useful for navigation, as it 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 is the Three Gorges Dam in China. Spanning the Yangtze River, this massive structure is 1.4 miles wide and 630 feet tall, capable of holding back more than five trillion gallons of water.
The Three Gorges Dam is named after the three gorges at the foot of the nearby Wu Shan Mountains. Its construction, completed in 1992, has been controversial, as it displaced 1.13 million people living in the 244 square miles that were subsequently flooded. The floodwaters inundated entire towns, farmland, and historical sites. Additionally, the weight of the water has reportedly been eroding the river's shores.
Landslides and toxic buildup are cited as growing concerns around the dam. However, the government and industry argue that it is necessary to support China's growing energy demands. The dam also helps control deadly flooding on the Yangtze River. During a typhoon in 2010, the Three Gorges Dam withstood an influx of 18,492,043 gallons of water per second.
