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A dam is a barrier across flowing water that obstructs, directs or slows down the flow, often creating a reservoir, lake or impoundments. Most dams have a section called a ''spillway or weir'' over which, or through which, water flows, either intermittently or continuously, and some have hydroelectric power generation systems installed. Dams are considered "installations containing dangerous forces" under International Humanitarian Law due to the massive impact of a possible destruction on the civilian population and the environment. Dam failures are comparatively rare, but can cause immense damage and loss of life when they occur. In 1975 the failure of the Banqiao Reservoir Dam and other dams in Henan Province, China caused more casualties than any other dam failure in history. The disaster killed an estimated 171,000 people〔Osnos, Evan. "Faust, China, and Nuclear Power," ''The New Yorker'', Wednesday October 12, 2011. Retrieved at http://www.newyorker.com/online/blogs/evanosnos/2011/10/faust-china-and-nuclear-power.html on October 12, 2011〕 and 11 million people lost their homes. In 2012 a dam in northern state of Rio de Janeiro, Brazil failed forcing thousands of people from homes. The water broke through the dam protecting the town of Campos de Goytacazes. Officials described the situation as race against time to evacuate people before the area becomes flooded. Since this incident, the Brazil government has set up early warning systems to ensure people evacuate before floods strike.〔Brazil dam burst forces thousands from homes. (2012, January 5). BBC. Retrieved from, ==Main causes of dam failure== Common causes of dam failure include: : * Sub-standard construction materials/techniques (Gleno Dam) : * Spillway design error (South Fork Dam, near failure of Glen Canyon Dam) : * Geological instability caused by changes to water levels during filling or poor surveying (Malpasset Dam). : * Sliding of a mountain into the reservoir (Vajont Dam – not exactly a dam failure, but caused nearly the entire volume of said reservoir to be displaced and overtop the dam) : * Poor maintenance, especially of outlet pipes (Lawn Lake Dam, Val di Stava dam collapse) : * Extreme inflow (Shakidor Dam) : * Human, computer or design error (Buffalo Creek Flood, Dale Dike Reservoir, Taum Sauk pumped storage plant) : * Internal erosion, especially in earthen dams (Teton Dam) : * Earthquakes 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dam failure」の詳細全文を読む スポンサード リンク
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