page_title: Zengwen Dam
section_title: Reservoir
hierarchical_section_title: Zengwen Dam / History / Reservoir
caption_attribution_description: 中文（繁體）‎: 2012年1月30日，自觀景樓遠眺曾文大壩。
context_page_description: Zengwen Dam, also spelled Tsengwen Dam, is a major earthen dam in Dapu Township, Chiayi County, Taiwan on the Zengwen River. It is the third tallest dam in Taiwan, and forms Zengwen Reservoir, the biggest reservoir in Taiwan by volume. The dam stores water for irrigation of the Chianan Plain, Taiwan's most productive agricultural region, and provides flood control along the Zengwen River which flows through Tainan City. The dam supports a 50 megawatt hydroelectric power station.
context_section_description: On March 2, 1973 with construction on the dam 96 percent complete, the first diversion tunnel was plugged; on April 28, 1973, the second tunnel was blocked, allowing the reservoir to begin storing water. The filling was approximately five months ahead of schedule, enabling water to be stored for the 1973 irrigation season rather than beginning in 1974 as originally planned. The Zengwen reservoir is the largest lake in Taiwan, with an initial design capacity of 708,000,000 cubic metres (574,000 acre⋅ft), and a surface area of 1,700 hectares (4,200 acres) when full, more than twice that of Sun Moon Lake. The full water level is 227 metres (745 ft) above sea level.
  Although the main purpose of the Zengwen reservoir is irrigation, it is also operated for flood control during the typhoon season. If the Central Weather Bureau issues a typhoon warning, and the reservoir level is higher than the flood-control pool, the gates may be opened to drain the extra water ahead of time, to reduce the risk of a sudden uncontrolled overflow that might endanger lives and property downstream.
  The reservoir has allowed an increase of 270,000,000 cubic metres (220,000 acre⋅ft) of water per year for irrigation and industry, and another 120,000,000 cubic metres (97,000 acre⋅ft) of drinking water. This makes possible the irrigation of an additional 66,000 hectares (160,000 acres) of land, while improving the reliability of supply for already existing farmland. It also allows for boats to access remote villages in Dapu township, which prior to the dam's construction could only be reached by winding mountain roads.
  The Zengwen Reservoir Management Bureau was established on January 1, 1974 to coordinate operations of the dam and reservoir. On January 23, 1998 the bureau was combined with other reservoir administrations in southern Taiwan, to form the Southern Region Water Resources Office.
caption: Zengwen Reservoir
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