The Panjiakou Dam is a concrete gravity dam on the Luan River

Luan River

The Luan River is a river in China. It flows northwards from its source in the province of Hebei into the province of Inner Mongolia, and then flows southeast back into Hebei to its mouth on the Bohai Sea. Its length is about 600 km. One subsidiary of the Luan River is the Yixun He, which...

 in Qianxi County

Qianxi County, Hebei

Qianxi County is a county of Hebei, China. It is under the administration of Tangshan City.-Administrative Divisions:The only subdistrict is Lixiang Subdistrict Towns:...

, Hebei Province, China. The primary purpose of the dam is to provide water for the cities of Tianjin

Tianjin

' is a metropolis in northern China and one of the five national central cities of the People's Republic of China. It is governed as a direct-controlled municipality, one of four such designations, and is, thus, under direct administration of the central government...

 and Tangshan

Tangshan

"唐山"redirects here. For an alternative name of China, see Names of China#TangTangshan is a largely industrial prefecture-level city in Hebei province, People's Republic of China. It has become known for the 1976 Tangshan earthquake which measured 7.8 on the Richter scale and killed at least...

, located to the south. The dam also provides flood control and its power plant has an installed capacity of 420 MW which includes a 270 MW pumped storage power station.

Background

Construction on the first stage of the project began in 1975 and the single 150 MW generator was operational in 1981. In 1984, the first stage was complete and in the same year, construction on the second stage began. This consisted of the lower reservoir and pump-generators for the pumped storage power station. In 1989, the lower reservoir began to impound and in 1993, the pump-generators were operational. Water supplied by the dam is used for industrial, agricultural and municipal needs in Tianjin and Tangshan. When the Panjiakou Reservoir was filled, it submerged the town of Panjiakou under 50 m (164 ft) of water. Located in the hills above the town is a section of the Great Wall, part of which was submerged as well. The submerged section ran through Panjiakou pass and a portion can be seen on a small island off the reservoir's edge at 40°25′51"N 118°16′12"E, particularly during droughts when the reservoir holds less water. The scenery around the reservoir is a popular tourist destination and with the surrounding terrain, it is often called "Qianxi Little Three Gorges".

Design and operation

The Panjiakou Dam is a 107.5 m (353 ft) tall and 1040 m (3,412 ft) concrete gravity dam. The dam's reservoir has a capacity of 2930000000 cubic metre and surface area of 67 km² (26 sq mi). Of the reservoir's capacity, 1950000000 cubic metre is active (or "useful") for power generation and water supply. The dam sits of the head of a 33700 km² (13,012 sq mi) catchment area

Drainage 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...

 which constitutes 75 percent of the Luan River basin. The dam's spillway

Spillway

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...

 is located on its left face and contains 18 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. It has a maximum discharge capacity of 40400 m3/s. To the right of the spillway is the power house which contains one 150 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....

 generator and three 90 MW reversible Francis turbine pump generators. Located 5.5 km (3 mi) downstream is the lower reservoir dam. It is a gravity type and has a height of 28 m (92 ft) and length of 1010 m (3,314 ft). It creates the lower reservoir with a storage capacity of 36180000 cubic metre of which 10000000 cubic metre can be used for pumped storage power generation. When the pumped storage capability is used, the Panjiakou Reservoir serves as the upper reservoir and water is released down to the three pump generators for power production. It is subsequently discharged into the lower reservoir. This occurs during periods of high peak power demand. When power demand is low, usually at night when electricity is cheaper, the turbines of the pump generators reverse and pump water back into the upper reservoir. This process repeats as needed. A small power plant on the lower reservoir dam contains two 5 MW Kaplan turbine

Kaplan turbine

The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by the Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to achieve efficiency over a wide range of flow and...

bulb-generators.