Yangtze(redirected from Chang Jiang)
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Chang (chăng) or Yangtze (yăngˈsēˈ, yängˈdzŭˈ), Mandarin Chang Jiang, longest river of China and of Asia, c.3,880 mi (6,245 km) long, rising in the Tibetan highlands, SW Qinghai prov., W China, and flowing generally E through central China into the East China Sea at Shanghai. The Chang and its tributaries drain more than 750,000 sq mi (1,942,500 sq km). The river passes through one of the world's most populated regions and has long been used as a major trade and transportation route.
The Chang's turbulent upper course, called the Jinsha or Kinsha, is roughly half its total length and flows southeast through forested, steep-walled gorges 2,000–4,000 ft (610–1,220 m) deep. After receiving the Yalong River, its first great tributary, at the Sichuan-Yunnan border, the Chang turns NE toward the Sichuan basin. At Yibin, on the western edge of the Sichuan basin, the river becomes the Chang proper and is joined by the “four rivers of Sichuan” (Min, Tuo, Fou, and Jailing). There is a hydroelectric power plant at Chongqing, on the basin's eastern edge.
Leaving the Sichuan basin, the Chang receives the Wu River and flows through the gorges that extend from Fengjieh to Yichang; temples and pagodas are perched on prominent hills along the gorges. The Three Gorges Dam, 30 mi (48 km) west of Yichang (constructed 1994–2006), is the world's largest concrete structure and hydroelectric station; its construction also flooded the spectacular gorges. The Gezhouba Dam near Yichang also regulates seasonally fluctuating water levels and harnesses the river's hydroelectric potential.
East of Yichang, the Chang enters the lake-studded middle basin of Hubei, Hunan, and Jiangxi provs., a rich agricultural and industrial region; Wuhan, at the confluence of the Han and Chang, is the principal city. The huge Dongting and Poyang lakes, which receive the Yuan, Zi, and Xiang rivers and the Gan River, respectively, are linked by numerous channels with the Chang and serve as natural overflow reservoirs. Now shallow because of sedimentation, the lakes are less effective as regulators of the Chang's flow. Dikes protect large areas of the river's middle basin from floodwaters. Although the Chang does not often experience the devastating floods that characterize the Huang He (Yellow River), it has occasionally caused wide damage; great floods occurred in 1931, 1954, and 1998. The fertile middle basin is China's most productive agricultural region; rice is the main crop.
The river enters the East China Sea through the extensive, ever-expanding delta region of Anhui and Jiangsu provs. Dikes have been built to reclaim coastal marshes and create additional farmland. The Chang carries its greatest volume during the summer rainy season. It is navigable for oceangoing vessels to Wuhan, c.600 mi (970 km) upstream; during the summer high-water period, Yichang, c.1,000 mi (1,610 km) upstream, is the head of navigation.
The South-to-North Water Diversion Project transfers water from the Chang and its tributaries to the Huang He, which often runs dry from overuse, and to Beijing, Tianjin, and other northern cities and provinces. The eastern route brings water from the lower Chang to the Huang He, Shandong prov., Tianjin, and other areas utilizing in part sections of the Grand Canal, and a central route connects the Han (a tributary of the Chang) to the Huang He, Beijing, Tianjin, and other areas. A third, western route, linking the headwaters of the Chang to those of the Huang He, is planned.
(also Ch’ang Chiang or Blue River), the largest river in China and Eurasia. The Yangtze is 5,800 km long and drains an area of 1,808,500 sq km (according to some data, 5,980 km or 1,827,000 sq km).
The river rises from the glaciers of the Tanglha and Kukushihli ranges in the central part of the Tibetan Highlands. The upper course, called the Ulan Muren, flows in a broad, marshy valley.
As it descends from the Tibetan Highlands and crosses the Sino-Tibetan Mountains, the Yangtze, called Kinsha Kiang (Chinsha Chiang) here, flows through narrow, deep gorges, forming numerous rapids. After emerging from the Sino-Tibetan Mountains, the middle Yangtze flows along the southern edge of the Szechwan Basin, where it has a slow current and reaches a width of 300–500 m. While crossing the basin’s mountainous eastern edge, the river forms three gorges, with a total length of about 100 km, in which it narrows to 120–200 m, with depths sometimes reaching 100 m. This segment of the river is called Sanhsia. The lower course, called Ch’ang Chiang, the most widely used name in China, flows primarily across plains (Chianghan and the southern part of the North China Plain) in a well-worked valley, forming many branches and channels. The main channel is 1–2 km wide, with depths of 20–30 m. The river empties into the East China Sea primarily through two channels, forming a delta with an area of about 80,000 sq km.
There are many lakes in the valley of the Yangtze, and they play a significant part in regulating the flow of the lower course. The largest lakes are Tungt’ing Hu and P’oyang Hu. The principal tributaries, the Yalung, Min, Kialing, and Han (Izuiho), enter the Yangtze from the left.
The river is fed primarily by the summer monsoon rains; the upper course is also fed by melting mountain snows and glaciers. During the summer high stage, the rise in the river’s water level in the Szechwan Basin exceeds 20 m, while in the lower course it is 10–15 m. In the gorges, signs of floods have been observed 40 m above the lowest level, which occurs in the winter. The mean flow rate near the mouth is 34,000 cu m per sec (according to some data, about 22,000), and the annual runoff is estimated at 1,070 cu km, making the Yangtze the world’s fourth largest river. The lower Yangtze is influenced by ocean tides, which penetrate a distance of 750 km upstream, to the city of Chiuchiang. The Yangtze carries 280–300 million tons of sediment a year to its mouth, which contributes to the rapid growth of the delta (an average of 1 km every 35—40 years). Throughout most of its course, the river is brownish yellow, and consequently the name “Blue River,” given by Europeans, is inaccurate. On the plains of the lower Yangtze a significant amount of sediment is deposited in the channel, causing silt to accumulate, as a result of which the channel is higher than the adjacent land. To prevent the flooding of the adjacent plains, a series of dikes, measuring about 2,700 km in length and up to 10–12 m in height, have been built on the banks of the Yangtze and a number of its tributaries. In the lower Yangtze, the dikes and water distribution structures have reduced but not eliminated the threat of flooding; major floods occurred in 1870, 1896, 1931, 1949, and 1954. Most of the Yangtze does not freeze in the winter; ice forms only in the headwaters and in sections where the current is slow.
The waters of the Yangtze and its tributaries are used extensively for irrigation, primarily in the Szechwan Basin and in areas along the lower course. The river is navigable for a length of 2,850 km, to the foot of the Sino-Tibetan Mountains. Seagoing vessels with displacements of up to 10,000 tons can travel as far as Wuhan. The Grand Canal crosses the lower Yangtze. Fishing has developed extensively in the basins of Lakes Tungt’ing, P’oyang, and Tai (common carp, silver carp, grasscarp, black carp). The rivers of the Yangtze River basin have enormous hydroelectric power potential, estimated at 217 million kilowatts. A large hydroengineering complex is under construction (1981) in the gorges of Sanhsia. Major cities on the river are Ipin, Chungking, Wuhan, and Nanking; the seaport of Shanghai is near the mouth of the river.
REFERENCEMuranov, A. P. Reka Yantszy. Leningrad, 1959.
A. P. MURANOV