Xinfengjiang Dam

The Xinfengjiang Dam (, also known as the Xinfeng Dam) is a gravity dam on the Xinfeng River, 8 km upstream of its confluence with the Dong River, and just west of Heyuan City in Guangdong Province, China. The dam's power station has a 292.5 MW installed capacity and its reservoir supplies water for farming along with drinking water to Guangzhou, Shenzhen and Hong Kong. Construction on the dam began in 1958, the first generator was operational in 1960 and the dam complete in 1962. The dam's reservoir-filling is attributed to several earthquakes within the project area including a 6.1-magnitude (Mw) on March 19, 1962.

Background
Construction on the dam began in 1958, a total of 1550000 m3 of earth was excavated at the construction site. On October 20, 1959 the reservoir behind the dam began to fill and in November there were several small earthquakes within the reservoir zone. When the water level reached 81 m above sea level (ASL) in May 1960, there were three to four earthquakes at a 3.1- and on July 18, when the water level 90 m ASL, a 4.3- earthquake occurred. On March 19, 1962 when the reservoir reached 110.5 m ASL there was a 6.1- earthquake with an epicenter 1.1 km downstream from the dam which destroyed several houses in the area. After the earthquake and as a precaution, cavities within the foundation were reinforced with concrete. This and other upgrades brought the dam to a 9.5--rated resistant design.

Design
The dam is a 105 m tall, 440 m wide gravity dam. Its crest width is 5 m and it has a structural volume of 1060000 m3 of concrete. Above the dam is a 5740 km2 drainage area and it withholds a reservoir of 13900000000 m3. The dam contains a surface controlled spillway with three floodgates, each with a 3800 m3/s maximum discharge capacity for a total of 11400 m3/s. The discharge tunnel on the dam's left bank has a 10 m diameter, is 778 m long and has a 1700 m3/s capacity. The dam's reservoir has a 3300000000 m3 flood storage capacity, rated for a once in a hundred-year flood. The dam's power station is located at its base (toe) and contains four Francis turbine generators. Three are rated at 72.5 MW and the fourth at 75 MW for a total design capacity of 292.5 MW but the power plant can operate at a maximum 315 MW after later upgrades.