Itaipu dam and hydroelectric plant. Foz do Iguaçu, Brazil.

Dam – a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations.

Hydroelectric generator

  • North Sea Protection Works (Netherlands) – Unique in the world, this vast and complex system of dams, floodgates, storm surge barriers and other engineered works literally allows the Netherlands to exist. For centuries, the people of the Netherlands have repeatedly attempted to push back the sea — only to watch merciless storm surges flood their efforts, since the nation sits below sea level and its land mass is still sinking. The North Sea Protection Works consists of two monumental steps the Dutch took to win their struggle to hold back the sea.
  • Itaipu Dam – Five miles wide and requiring enough concrete to build five Hoover Dams, the Itaipu Dam spans the Parana River at the Brazil/Paraguay border. During its construction, workers shifted the course of the seventh largest river in the world by removing 50 million tons of earth and rock to dig a 1.3-mile bypass. The main dam, as high as a 65-story building, is composed of hollow concrete segments, while the flanking wings are earth and rock fill. Enough iron and steel was used at Itaipu to build 300 Eiffel Towers. Another marvel of Itaipu is its powerhouse — half a mile long, half underwater and containing 18 hydroelectric generators each 53 ft. across.
  • Venice’s high tech floodgates – In an effort to stem the rising tide, the Italian government is erecting 78 electromechanical flood gates to isolate the city and its surrounding lagoon. Although the project is immense in scale and ambition, it actually operates with relatively simple technology. The gates will be submerged at the boundary of the Venetian lagoon and the Adriatic Sea. When a high-tide is forecasted, compressed air will raise the gates to prevent the tides from rushing into the city.
  • Three Gorges Dam – a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in Yiling District, Yichang, Hubei province, China. The Three Gorges Dam is the world’s largest power station in terms of installed capacity (22,500 MW) but is second to Itaipu Dam with regard to the generation of electricity annually. Except for a ship lift, the dam project was completed and fully functional as of July 4, 2012, when the last of the main turbines in the underground plant began production. Each main turbine has a capacity of 700 MW. The dam body was completed in 2006. Coupling the dam’s 32 main turbines with two smaller generators (50 MW each) to power the plant itself, the total electric generating capacity of the dam is 22,500 MW.

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Engineering ideas

  • concrete, arch, gravity, floodgate, surge barrier, hydroelectric generator, electromechanical, compressed air

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  • Dam – Early dam building took place in Mesopotamia and the Middle East. Dams were used to control the water level, for Mesopotamia’s weather affected the Tigris and Euphrates rivers, and could be quite unpredictable.