TARIM RIVER

Wade-Giles romanization T'a-li-mu Ho, Pinyin Tarim He, chief river of the Uighur Autonomous Region of Sinkiang, extreme northwestern China. It lies immediately north of the Plateau of Tibet. The river gives its name to the great basin between the Tien Shan and Kunlun mountain systems of Central Asia. It flows for most of its length through the Takla Makan Desert. The word tarim is used to designate the bank of a river that flows into a lake or that is undifferentiable from the sands of a desert. This is a characteristic hydrographic feature of many rivers that traverse the sands of the Takla Makan Desert. Another characteristic of the rivers of the Tarim Basin, including the Tarim itself, is their active migrationi.e., the shifting of their beds and banks. The Tarim is formed by the confluence of the K'a-shih-ka-erh (Kashgar) and Yarkand rivers in the far west; flowing northeastward from this confluence, the river is then joined some 230 miles (370 km) downstream by the A-k'o-su and the Ho-t'ien (Khotan) rivers. Only the A-k'o-su River flows for the entire year. It is the Tarim's most important tributary, supplying 7080 percent of its water volume. The name Tarim is used below the Ho-t'ien River confluence. The total length of the Yarkand-Tarim river system is 1,261 miles (2,030 km), although, as the Tarim frequently changes its channel, the length tends to vary over the years. Prior to the completion of reservoirs and irrigation works in the mid-20th century, the Tarim's waters eventually reached Lop Nor (now a salt-encrusted lake bed). The river's waters now drain intermittently into T'ai-t'e-ma (Taitema) Lake, which is located about 100 miles (160 km) southwest of Lop Nor. The area of the Tarim River Basin is about 215,000 square miles (557,000 square km). A considerable part of the Tarim's course is unformed, following no clearly defined riverbed. The water volume of the lower course of the river diminishes as a result of extensive evaporation and water-diversion schemes. The Tarim's low-water period is from October through April. The spring and summer high waters begin in May and continue through September as the snows melt on the distant Tien Shan and Kunlun mountains. The Lower Tarim Basin is an arid plain composed of alluvium and lake sediments and is bordered by massive mountain ranges. The basin is the driest region of Eurasia. The predominant part of it is occupied by the Takla Makan Desert, whose sand area exceeds 105,000 square miles (270,000 square km). In addition, there are several comparatively small sand massifs with areas of from 300 to 1,700 square miles (780 to 4,400 square km). Sand dunes are the predominant relief. Precipitation in the Tarim Basin is extremely scanty, and in some years it is nonexistent. In the Takla Makan Desert and in the Lop Nor basin, the average annual total of precipitation is about one-half inch (12 mm). In the foothills and in several other areas of the river's basin, the precipitation amounts to from 2 to 4 inches (50 to 100 mm) a year. In the Tien Shan it is much wetter, precipitation often exceeding 20 inches (500 mm). Maximum temperatures in the Tarim Basin are about 104 F (40 C). The Tarim River freezes over every year from December through March. Vegetation in the Tarim Basin is mainly located along the river and its branches. There, at the edge of the sands, shrublike vegetation and stunted trees, especially wormwood, are found. A thin forest of poplar grows in the Tarim River valley. Underbrush consists of willows, sea buckthorn, and dense growths of Indian hemp and Ural licorice. The Tarim River is rich in fish, and animal life on the river and the surrounding desert is varied. The valley and lakes of the Tarim are a stopover for many migratory birds. Despite the Chinese government's promotion of large-scale irrigation, oasis agriculture remains the mainstay of the scattered settlements in the region. Grains, cotton, silk, fruits, and wool are the chief agricultural products, and Khotan jades are the only other important item. Little is exported from the basin, but local surpluses find a market among travelers passing through when conditions permit.