Huanglongtan Dam

The Huanglongtan Dam is a concrete gravity dam located on the Du River, a tributary of the Han River. It is located 25 km west of Shiyan in Hubei Province, China. The main purpose of the dam is hydroelectric power generation but it also provides for flood control. 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 tall, 371 m long and has a structural volume of 980000 m3. The dam's crest is 20 m wide and sits at an elevation of 252 m above sea level. Sitting at the head of a 11140 km2 catchment area, the dam withholds a reservoir of 1228000000 m3 of which 150000000 m3 is reserved for flood storage. Normal reservoir elevation is 247 m. The dam's spillway consists of six 12 m high and 10 m wide sluice 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-generators. The expansion power plant is located 200 m away from the original and contains 2 x 170 MW Francis turbine-generators.