Kurobe Dam

The Kurobe Dam or Kuroyon Dam, is a variable-radius arch dam on the Kurobe River in Toyama Prefecture on the island of Honshū, Japan. It supports the 335 MW Kurobe No. 4 Hydropower Plant and is owned by Kansai Electric Power Company. At 186 metres (610 ft) high, it is the tallest dam in Japan. It was constructed between 1956 and 1963 at a cost of ¥51.3 billion yen. The project was a difficult engineering feat for the rapidly growing post-World War II Japan, and claimed the lives of 171 people.

The Kurobe Dam is a 492 m (1,614 ft) long and 186 m (610 ft) high variable-radius (dome) arch dam. The dam is 39.7 m (130 ft) wide at its base, 8.1 m (27 ft) wide at its crest and contains 1,582,845 m3 (2,070,283 cu yd) of concrete. The dam is flanked and supported by two "wing" dams; the one on the left bank is 69 m (226 ft) long and the right is 56 m (184 ft). The dam withholds a reservoir with a capacity of 199,285,175 m3 (260,655,168 cu yd) of which 148,843,000 m3 (194,679,000 cu yd) is live (active or "useful") storage. The reservoir also has a catchment area of 188.5 km2 (72.8 sq mi) and surface area of 3.49 km2 (1.35 sq mi). The dam's spillway is located on its crest and contains 10 11.5 m (38 ft) wide uncontrolled openings with a maximum discharge capacity of 906 m3/s (32,000 cu ft/s). Three other openings exist in the dam's orifice which consist of 1.5 m (4.9 ft) diameter pipes, two of which can discharge a maximum of 88 m3/s (3,100 cu ft/s) each and the third 44 m3/s (1,600 cu ft/s). The dam's crest elevation is 1,454 m (4,770 ft) above sea level while the reservoir's normal operating level is 1,448 m (4,751 ft) and low level is considered 1,338 m (4,390 ft). The dam's power station, Kurobe No. 4, is located underground and contains four generators which are powered by Pelton turbines for a total installed capacity of 335 MW and average annual generation of 1 billion kWh. The power station is 22 m (72 ft) wide, 33 m (108 ft) high and 117 m (384 ft) long. The penstock serving water to the power station is 10,909.6 m (35,793 ft) long and utilizes a maximum effective hydraulic head of 545.5 m (1,790 ft) while transferring a maximum of 72 m3/s (2,500 cu ft/s) to the turbines. The plant's surge chamber is 145.6 m (478 ft) long and 5 m (16 ft) high.