Wu River (Yangtze tributary)
The Wu River () is the largest southern tributary of the Yangtze River. Nearly its entire length of runs within the isolated, mountainous and ethnically diverse province of Guizhou. The river takes drainage from a watershed. The river flows through the Liupanshui, Anshun, Guiyang (the capital), Qiannan, and Zunyi Districts of Guizhou. All nine regions of the province have at least partial drainage to the river. Course. The river begins as the "Sancha" in western Guizhou and flows eastwards about . It then bends north, west and south in a reach called the Yachi, and receives the Nanming  River from the right. After the Yachi reach, the Wu makes a broad arc northeast through central Guizhou, picking up fifteen major tributaries including the Yu, Furong and Ya Rivers and flowing through several large hydroelectric dams. It then crosses the border into the provincial-level municipality of Chongqing, flows past Wushan, Badong and Zigui, and empties into the Yangtze River at Fuling, some east-northeast of Chongqing, in the Wu Gorge of the Three Gorges of the Yangtze. Part of the lower course of the river is flooded by the reservoir of Three Gorges Dam. History. Many small river  towns along the Wu, such as Gongtan, date back to as early as 200 A.D. Fuling is regarded as the first major town to be built on the river. The city was the capital of the ancient Ba state in the Sichuan area. During the Qin Dynasty, the region was brought under Chinese control. The Wu Gorge is also known as "Golden Helmet and Silver Armor Gorge". The name originates from a helmet-shaped rock formation above the river and a silver-colored cliff of slate. Another name for Wu Gorge is "Iron Coffin Gorge". River modifications. The Wu River  has been extensively developed for hydroelectricity generation. , dams along the river had a combined capacity of 8,500 megawatts (MW). Much of this development is extremely recent, as power generation in 2010 was over four times of that in 2005. Most dams on the river were constructed and owned by the Wujiang Hydropower Corporation. The largest dam, the Goupitan Dam, was completed in 2011. Aside from producing power, dams on the Wu River also provide flood control and hydraulic head for irrigation operations. The lower reaches of the river are heavily polluted because of poor sewage systems and dumping of agricultural  waste – so much that it is not even considered suitable for irrigation and industrial purposes. About of the river's lower course forms an arm of the Wu Gorge (Big Gorge or Second Gorge) of the Three Gorges, now submerged in up to of water from Three Gorges Reservoir. In late 2008, geological instabilities caused landslides with volumes of . It is speculated that the former slide is part of a larger unstable slope with as much as . The latter slide caused a wave that swamped boats up to away. The 10 dams on the river that are either completed, under  construction or planned, , are listed below from downstream to upstream. Navigation. In the 1950s, local governments began an ambitious project to increase the navigability of the Wu River. The lower of the river were dredged of sediment and hundreds of sets of rapids were destroyed by explosive charges. Navigation on the upper river, in contrast, reflects the difficulty of traversing the Yangtze in the Three Gorges region before the construction of Three Gorges Dam. With the creation of the reservoir behind this dam, navigation on the lower reaches of the Wu has increased significantly. Bridges. There are many spectacular bridges  along the course of the Wu River. These include (from mouth heading upstream):