| Wu River | |
| Name Other: | Sancha, Yachi |
| Name Etymology: | Named for 12 peaks of Wu Mountain |
| Map: | Wujiangrivermap.png |
| Subdivision Type1: | Country |
| Subdivision Name1: | China |
| Subdivision Type2: | State |
| Subdivision Name2: | Guizhou |
| Subdivision Type4: | District |
| Subdivision Name4: | Chongqing |
| Subdivision Type5: | Cities |
| Subdivision Name5: | Wushan, Badong, Zigui, Fuling |
| Length: | 1150km (720miles) |
| Discharge1 Location: | Gongtan[1] |
| Discharge1 Min: | 272m3/s |
| Discharge1 Avg: | 1108m3/s[2] |
| Discharge1 Max: | 3340m3/s |
| Source1: | Sancha |
| Source1 Location: | Western Guizhou |
| Mouth: | Yangtze River |
| Mouth Location: | Fuling, Eastern Chongqing Municipality |
| River System: | Yangtze River system |
| Basin Size: | 80300km2 |
| Tributaries Left: | Liuchong River, Furong River |
| Tributaries Right: | Nanming River, Yu River (Hubei), Ya River |
The Wu River is the largest southern tributary of the Yangtze River. Nearly its entire length of 1150km (720miles) runs within the isolated, mountainous and ethnically diverse province of Guizhou. The river takes drainage from a 80300km2 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.
The river begins as the Sancha in western Guizhou and flows eastwards about 350km (220miles). It then bends north, west and south in a 300km (200miles) 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 50miles 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.[3]
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".
The Wu River has been extensively developed for hydroelectricity generation., dams along the river had a combined capacity of 8,500 megawatts (MW).[4] 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 232m (761feet) Goupitan Dam, was completed in 2011.[5] Aside from producing power, dams on the Wu River also provide flood control and hydraulic head for irrigation operations.[6]
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.[7]
About 40km (30miles) 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 30m (100feet) of water from Three Gorges Reservoir. In late 2008, geological instabilities caused landslides with volumes of 20000m250000m2. It is speculated that the former slide is part of a larger unstable slope with as much as 100000m2. The latter slide caused a wave that swamped boats up to 2km (01miles) away.[8]
The 10 dams on the river that are either completed, under construction or planned,, are listed below from downstream to upstream.[9] [10]
In the 1950s, local governments began an ambitious project to increase the navigability of the Wu River. The lower 480km (300miles) 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.
There are many spectacular bridges along the course of the Wu River. These include (from mouth heading upstream):