Fengman Dam
Encyclopedia
The Fengman Dam is a concrete gravity dam
Dam
A dam is 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 are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

 20 km (12 mi) from Jilin City
Jilin City
Jilin City is the second largest city of Jilin province in Northeast China. At the 2010 census, 4,414,681 people resided within its administrative area of and 1,975,803 in its built up area...

 on the Second Songhua River
Second Songhua River
The Second Songua River is a tributary of the Songhua River in Jilin Province, China. The river meets the Songhua and Nen Rivers near Songyuan and has several tributaries to include the First Dao, the Second Dao, Huifa, Yinma, Yitong and Lafa Rivers. It is interrupted by the Baishan, Hongshi and...

 in Jilin 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 main purposes of the dam are hydroelectric power generation and flood control. Construction of the dam began in 1937 and was complete in 1953. Northeast China Grid Company Limited, the dam's owner, plans on rebuilding it in the future.

History

Construction on the Fengman Dam began in 1937 under the Japanese during their occupation of parts of China during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. In November 1942, the reservoir behind the dam began to fill and by March 1943, the first generators were operational. Still lacking floodgate
Floodgate
Floodgates are adjustable gates used to control water flow in flood barriers, reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow entirely as part of a levee or...

s, the dam was not entirely complete after the Japanese occupation in 1953. In 1959, the eighth and final generator of the first stage was installed, bringing the power station's installed capacity to 552.5W. Between 1970 an 1979, a tunnel was installed on the left bank of the dam and it was later converted into a flood discharge tunnel in 1991. In 1988, the second stage of construction began which included the installation of a ninth and tenth turbine. This was complete in 1992 and the plant's total installed capacity was 722.5 MW. From 1993 to 1998, the third stage of constructed on the dam was carried out, bringing the power station to a final installed capacity of 1002.5 MW.

Reservoir

The Fengman Reservoir, also known as Songhua Lake, has a capacity of 11460000000 cubic metre of which 5350000000 cubic metre is active or "useful" storage and 2670000000 cubic metre is used for flooding. The reservoir is narrow, 180 km (112 mi) long, and has a surface area of 550 km² (212 sq mi). Normal reservoir level is 261 m (856 ft) above sea level, minimum is 242 m (794 ft) and a maximum of 267 m (876 ft). The drainage or catchment area is 42500 km² (16,409 sq mi) of which 19000 km² (7,336 sq mi) is controlled by the Baishan Dam
Baishan Dam
The Baishan Dam is an arch-gravity dam on the Second Songhua River near the town of Baishanzhen, Huadian, Jilin Province, China. The purpose of the dam is hydroelectric power generation and flood control...

, 11600 km² (4,479 sq mi) is located within the Daogou area and 11900 km² (4,595 sq mi) is controlled by the Hongshi Dam. Annual rainfall in the reservoir zone is 500 millimetre - 1020 millimetre with 60-90 percent falling between July and September each year. Average mean runoff is 426 m3/s, maximum mean is 737 m3/s while the minimum mean is 164 m3/s. Maximum instantaneous runoff during flooding can reach 22800 m3/s while during ice season, it can be as low as 10 m3/s.

Design

The Fengman dam is a 91 m (299 ft) high and 1080 m (3,543 ft) long concrete gravity dam which is divided into 60 18 m (59 ft)sections. Sections 1-8, 20 and 32-60 are non-overflow while 9-19 contain the 11 crest overflow spillways. Sections 21-31 contain the ten intakes and 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 for the power plant which rest at their base, the dam's toe. The dam's crest spillway has a 9240 m3/s capacity while the 683 m (2,241 ft) long, 9.2 m (30 ft) diameter flood discharge tunnel on the left bank has a 1186 m3/s capacity.
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