Sanmenxia Dam
Encyclopedia
The Sanmenxia Dam is a concrete gravity dam on the middle-reaches of the Yellow River
near Sanmenxia
on the border Shanxi and Henan Province, China
. The dam is multi-purpose and was constructed for flood and ice control along with irrigation, hydroelectric power production and navigation
. Construction began in 1957 and was completed in 1960. It is the first major water control project on the Yellow River and was viewed as a major achievement of the new People's Republic of China
. Subsequently, its image was printed on the country's bank notes. However, due to sediment accumulation in the reservoir, the dam was later renovated. The effects from sediment
, which include flooding upstream, have placed the dam at the center of controversy and criticism-related arrests by the Chinese government.
and swiftly approved that same year while preliminary construction began soon after. Under Soviet Union
supervision, construction ceremoniously began on 13 April 1957. Construction on the left-bank cofferdam
began in June 1957 and excavation was completed a year later along with the pouring of the left-bank foundation. In October 1958, construction on the right-bank cofferdam was initiated and the river was closed by November 1958. In June 1960, the reservoir was at full pool and the dam crest reached its design elevation of 353 m (1,158 ft) ASL in April 1961. The dam's generators were commissioned between 1973 and 1975. The dam was the first major water project on the Yellow River and constructed with manual labor. Upon completion, it was hailed as an engineering success for the new republic and its image was printed on Chinese banknotes.
-accumulation threatened the benefits of the dam. The Yellow River carries more sediment than any other in the world. During the 18 months after the river was closed, 1.8 billion metric tons of sediment had accumulated in the reservoir. Only 7% of the sediment-load was released downstream and the reservoir lost 17% of its capacity below a 335 m (1,099 ft) ASL elevation. Navigation and farmland were threatened upstream along with the relocation of an additional one million people. Despite the dam's 12 deep-sluices and alterations in the release of water, silt continued to build in the reservoir, particularly in the back waters. Responding to the potential crisis, a meeting was held in December 1964 with Premier Zhou Enlai
. At the meeting, it was decided to reconstruct the dam's outlet works
for improved discharges and silt control. The renovation was carried out immediately and in two stages. The first stage included the installation of two tunnels on the dam's left bank at an elevation of 290 m (951 ft) ASL along with converting four penstock
s into flushing pipes. The flushing pipes began operating in 1966 and the tunnels in 1967 and 1968. In the second stage, eight bottom sluices were added to the left side of the dam which became operational between 1970 and 1971. Silt balance was achieved in 1970. Two more bottom sluices began operating in 1990 along with another in 1999 and the final in 2000.
upstream. Chinese engineer Zhang Guangdou
described the project as a "mistake" in 2004 and remarked how hydrologist Huang Wanli had been sent to hard labour for opposing the project. Other engineers oppose the dam's existence but their silence is attributed to government reprisals. In August 2010, Chinese journalist Xie Chaoping was detained for writing The Great Migration, a book that criticized the dam and the government's handling of it. The next month, the book's printer, Zhao Shun, was also arrested. Xie was later released on bail.
and withholds a reservoir
with a 16200000000 cubic metre capacity. The reservoir covers a surface area of 2350 km² (907 sq mi) and stretches 246 km (153 mi) upstream to Longmen
. The dam supports a power station that can hold up to eight turbines but currently only seven are installed. Five 50 MW and 75 MW Francis turbine
-generators make up the arrangement for a total installed capacity of 400 MW.
Yellow River
The Yellow River or Huang He, formerly known as the Hwang Ho, is the second-longest river in China and the sixth-longest in the world at the estimated length of . Originating in the Bayan Har Mountains in Qinghai Province in western China, it flows through nine provinces of China and empties into...
near Sanmenxia
Sanmenxia
-Administration:The prefecture-level city of Sanmenxia administers one district, two county-level cities and three counties.*Hubin District*Lingbao City*Yima City*Lushi County*Shan County*Mianchi County*Sanmenxia Development Zone...
on the border Shanxi and Henan Province, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. The dam is multi-purpose and was constructed for flood and ice control along with irrigation, hydroelectric power production and navigation
Navigability
A body of water, such as a river, canal or lake, is navigable if it is deep, wide and slow enough for a vessel to pass. Preferably there are few obstructions such as rocks or trees to avoid. Bridges must have sufficient clearance. High water speed may make a channel unnavigable. Waters may be...
. Construction began in 1957 and was completed in 1960. It is the first major water control project on the Yellow River and was viewed as a major achievement of the new People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. Subsequently, its image was printed on the country's bank notes. However, due to sediment accumulation in the reservoir, the dam was later renovated. The effects from sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
, which include flooding upstream, have placed the dam at the center of controversy and criticism-related arrests by the Chinese government.
History
In response to centuries of flooding on the Yellow River, engineers initially proposed the Sanmenxia Dam in early 1935. In 1954, the Yellow River Planning Board was established and oversaw a survey of the river with help from Soviet engineers. The Soviet engineers recommended a dam at the Sanmenxia site. Original plans for the dam called for a maximum reservoir level 360 m (1,181 ft) above sea level (ASL). This would have required the relocation of 870,000 and the flooding of 3500 km² (1,351 sq mi). The design was revised to a maximum level of 340 m (1,115 ft) ASL which required the relocation of 400,000 people and flooded much less area. In 1955 the Comprehensive River Basin Planning Report officially proposed the project. The report was submitted to the National People's CongressNational People's Congress
The National People's Congress , abbreviated NPC , is the highest state body and the only legislative house in the People's Republic of China. The National People's Congress is held in the Great Hall of the People, Beijing, capital of the People's Republic of China; with 2,987 members, it is the...
and swiftly approved that same year while preliminary construction began soon after. Under Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
supervision, construction ceremoniously began on 13 April 1957. Construction on the left-bank cofferdam
Cofferdam
A cofferdam is a temporary enclosure built within, or in pairs across, a body of water and constructed to allow the enclosed area to be pumped out, creating a dry work environment for the major work to proceed...
began in June 1957 and excavation was completed a year later along with the pouring of the left-bank foundation. In October 1958, construction on the right-bank cofferdam was initiated and the river was closed by November 1958. In June 1960, the reservoir was at full pool and the dam crest reached its design elevation of 353 m (1,158 ft) ASL in April 1961. The dam's generators were commissioned between 1973 and 1975. The dam was the first major water project on the Yellow River and constructed with manual labor. Upon completion, it was hailed as an engineering success for the new republic and its image was printed on Chinese banknotes.
Sediment and renovation
Soon after completion, sedimentSediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
-accumulation threatened the benefits of the dam. The Yellow River carries more sediment than any other in the world. During the 18 months after the river was closed, 1.8 billion metric tons of sediment had accumulated in the reservoir. Only 7% of the sediment-load was released downstream and the reservoir lost 17% of its capacity below a 335 m (1,099 ft) ASL elevation. Navigation and farmland were threatened upstream along with the relocation of an additional one million people. Despite the dam's 12 deep-sluices and alterations in the release of water, silt continued to build in the reservoir, particularly in the back waters. Responding to the potential crisis, a meeting was held in December 1964 with Premier Zhou Enlai
Zhou Enlai
Zhou Enlai was the first Premier of the People's Republic of China, serving from October 1949 until his death in January 1976...
. At the meeting, it was decided to reconstruct the dam's outlet works
Outlet works
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream...
for improved discharges and silt control. The renovation was carried out immediately and in two stages. The first stage included the installation of two tunnels on the dam's left bank at an elevation of 290 m (951 ft) ASL along with converting four penstock
Penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
s into flushing pipes. The flushing pipes began operating in 1966 and the tunnels in 1967 and 1968. In the second stage, eight bottom sluices were added to the left side of the dam which became operational between 1970 and 1971. Silt balance was achieved in 1970. Two more bottom sluices began operating in 1990 along with another in 1999 and the final in 2000.
Controversy and arrests
Impacts from sediment accumulation continued after renovation and also drew increasing criticism. The sediment has caused severe flooding on the Wei RiverWei River
The Wei River is a major river in west-central China's Gansu and Shaanxi provinces. It is the largest tributary of the Yellow River and very important in the early development of Chinese civilization....
upstream. Chinese engineer Zhang Guangdou
Zhang Guangdou
Zhang Guangdou is a world-known specialist in hydraulic engineering, a professor at Tsinghua University, and a member of the Chinese Academy of Sciences and Chinese Academy of Engineering.-Biography:...
described the project as a "mistake" in 2004 and remarked how hydrologist Huang Wanli had been sent to hard labour for opposing the project. Other engineers oppose the dam's existence but their silence is attributed to government reprisals. In August 2010, Chinese journalist Xie Chaoping was detained for writing The Great Migration, a book that criticized the dam and the government's handling of it. The next month, the book's printer, Zhao Shun, was also arrested. Xie was later released on bail.
Design
The dam is a 106 m (348 ft) tall and 713 m (2,339 ft) long concrete gravity type. It sits at the head of a 688400 km² (265,793 sq mi) catchment areaDrainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
and withholds a reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
with a 16200000000 cubic metre capacity. The reservoir covers a surface area of 2350 km² (907 sq mi) and stretches 246 km (153 mi) upstream to Longmen
Mount Longmen (Shanxi)
Lóngmén Shān, Mount Longmen or Longmen Mountain is a mountain in Shanxi province, China. In March-April 2010, the Wangjialing coal mine flood occurred here.-Geography:...
. The dam supports a power station that can hold up to eight turbines but currently only seven are installed. Five 50 MW and 75 MW Francis turbine
Francis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
-generators make up the arrangement for a total installed capacity of 400 MW.