Wushe Dam

Wushe Dam is a gravity dam forming Wushe Reservoir, also called Wanda Reservoir  and Bihu , on the Wushe Creek , a tributary of the Zhuoshui River, located in Ren-ai Township, Nantou County, Taiwan. The dam was completed in 1960 after seven years of construction, and serves mainly to generate hydroelectric power.

Background
When Taiwan was under Japanese rule in 1934, hydroelectric plants were constructed at Sun Moon Lake to generate power from the fall of the Zhuoshui River. The Japanese also sought to build power stations upstream on Wushe Creek and Wanda Creek, the two main tributaries that combine to form the Zhuoshui. A reservoir would be required to control the flow of water to the power stations and serve the dual purposes of flood control and trapping sediment. In 1939, construction began on a 97 m high concrete gravity dam on the Wushe Creek.

When World War II broke out in 1941, industrial resources were increasingly diverted to the war effort and construction was halted in 1944 with only the power plants and 6 percent of the dam complete. After the war, Taiwan Power Company (Taipower) took over the project with aid from the United States Agency for International Development. The U.S. Bureau of Reclamation consulted on a re-design which increased the dam height to 114.6 m. Construction resumed in May 1953. The reservoir first filled in 1957, and the project was officially completed in August 1960, at a cost of NT$376,077,000.

Construction details
The dam is a curved concrete gravity structure with a height of 114.6 m and length of 205 m. The crest elevation is 1005.84 m, and supports a 7 m roadway. Altogether, the dam contains 349000 m3 of concrete. The spillway consists of two radial gates with a capacity of 5670 m3/s. The dam controls runoff from an area of 219 km2, and is operated to reduce flood peaks on the Zhuoshui River by up to 2520 m3/s.

The Wushe Reservoir's normal water level is 1004.6 m, with a flood level of 1005.0 m, and covers an area of 2.84 km2. Nominal capacity in 1957 was 146000000 m3, with a useful capacity of 91000000 m3. However, like many reservoirs of Taiwan, it has suffered heavily from siltation, especially after Typhoon Morakot in 2009. The current useful capacity is estimated at no more than 54390000 m3.

Power station
The Wanda Power Station is located about 2 km downstream and was the only part of the project to be completed before the construction halted due to World War II. In 1943, it began generating power using water from Wanda Creek, which joins with the Wushe Creek here to form the Zhuoshui River. The three Pelton turbines installed at the time are known as unit G3 and have a capacity of 15,000 kilowatts (KW).

In 1957 generating units G1 and G2 were put into service, using water from the Wushe reservoir at a gross head of 109.7 m. G1 and G2 have a capacity of 20,700 KW each. In 2012 unit G4 was installed, providing an additional capacity of 19,700 KW. All three units are powered by vertical-axis Francis turbines, and generate about 182 million kilowatt hours (KWh) per year.

The Songlin Power Station is located downstream and generates power from the combined outflow of G1 through G4. It consists of two Francis turbines powering two 20,900 KW generators.

In 2012 Taipower began an overhaul of the power station, installing three new generators and upgrading a fourth. On September 13, 2013 the installation was completed, replacing aged equipment that had been in use since the late 1950s.