The Jinshuitan Dam is an arch dam

Arch dam

An arch dam is a type of dam that is curved and commonly built with concrete. The arch dam is a structure that is designed to curve upstream so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes...

 on Longquan Creek, a tributary of the Oujiang River in Zhejiang Province, China. It is located about 47 km (29 mi) southwest of Lishui. The dam and power station were completed in 1988 and serve several purposes to include hydroelectric power generation, water supply, flood control 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...

. It is the first dam of the Oujiang River cascade to be constructed and creates the second largest lake in Zhejiang.

Background

Construction on the dam began in October 1981 and the river was closed the same month in 1983. In 1986, the reservoir began filling and reached conservation storage level. On 7 April 1987, the first generator went online and by 31 December 1988, the other three generators in the power station were commissioned.

Design

The dam is a double-curvature (variable radius) type with a height of 102 m (335 ft), crest width of 5 m (16 ft) and base width of 24.6 m (81 ft). Sitting at the head of a 2761 km² (1,066 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...

, the dam creates Xiangong Lake which has a capacity of 13930000000 cubic metre. The lake covers a surface area of 34 km (21 mi) and is 66 km (41 mi) in length. The dam has two 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...

s that lie on either side of the power station. Each spillway has a shallow and an intermediate opening. The shallow openings have a maximum discharge of 3122 m3/s while the intermediate can discharge 2638 m3/s. The power station is located at the base of the dam and contains the six 50 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 which are each supplied with water via a 4.5 m (15 ft) diameter 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....

. Between the power station and the east spillway, there is a boat/raft lift to move small vessels and lumber from the river below into the reservoir.