The Huanglongtan Dam is a concrete gravity dam located on the Du River, a tributary of the Han River. It is located 25 km (16 mi) west of Shiyan

Shiyan

Shiyan is a prefecture-level city in northwestern Hubei province, People's Republic of China.-Geography:The Wudang Mountains run approximately east-west through the territory of the "Prefecture-level city" of Shiyan, crossing several of its county-level divisions...

 in Hubei Province, China. The main purpose of the dam is hydroelectric power generation but it also provides for flood control

Flood control

In communications, flood control is a feature of many communication protocols designed to prevent overwhelming of a destination receiver. Such controls can be implemented either in software or in hardware, and will often request that the message be resent after the receiver has finished...

. It was constructed between 1969 and 1976 and support a 510 MW power station.

Background

The Huanglongtan Dam and two other projects on the river (Songshuling and Pankou Dams) were surveyed in 1954 and final designs were prepared in 1964. Construction on Huanglongtan, the first of the projects to be implemented, began in April 1969. The original 85 MW generators were commissioned in 1974 and the dam was complete in 1976. The entire project was accepted by the state in 1978. In 1980, the dam experienced a 50-year flood with river flow peaking at 11500 m3/s. The flood inundated the power station as the dam was not prepared for the inflow. This was due to mis-communication within the basin and a lack of a proper hydrological forecast system. In May 2003 the dam's power plant underwent an expansion which included the installation of two new 170 MW Francis turbines along with a new power house and water delivery system. The first of the two generators was operational at the end of 2004 and the project complete in 2005.

Design

The concrete gravity dam is 107 m (351 ft) tall, 371 m (1,217 ft) long and has a structural volume of 980000 m³ (1,281,792 cu yd). The dam's crest is 20 m (66 ft) wide and sits at an elevation of 252 m (827 ft) above sea level. Sitting at the head of a 11140 km² (4,301 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 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...

 of 1228000000 cubic metre of which 150000000 cubic metre is reserved for flood storage. Normal reservoir elevation is 247 m (810 ft). 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...

 consists of six 12 m (39 ft) high and 10 m (33 ft) wide sluice

Sluice

A sluice is a water channel that is controlled at its head by a gate . For example, a millrace is a sluice that channels water toward a water mill...

 gates and has a maximum discharge capacity of 11200 m3/s. The dam's original power station is located just downstream on the left bank of the river and contains 2 x 85 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. The expansion power plant is located 200 m (656 ft) away from the original and contains 2 x 170 MW Francis turbine-generators.