AMU DARYA

Tajik Daryoi Amu, Turkmen Amyderya, Uzbek Amudaryo, ancient name Oxus River one of the longest rivers of Central Asia. It is formed by the confluence of the Vakhsh and Panj (Pyandzh) rivers and flows west-northwest to its mouth on the southern shore of the Aral Sea. In its upper course the Amu Darya forms part of the border between Afghanistan (south) and Tajikistan, Uzbekistan, and Turkmenistan (north). In its lower course the river forms part of the boundary between Uzbekistan (northeast) and Turkmenistan (southwest). The Amu Darya has a length of 879 miles (1,415 km), but its length is 1,578 miles (2,540 km) if measured from the remotest sources of its headstream, the Panj River in the Pamirs. The river was traditionally known to the Western world from Greek and Roman times as the Oxus and was called Jayhun by the Arabs. It allegedly derives its present name from the city of Amul, which is said to have occupied the site of modern Chrjew in Turkmenistan. Well known as it was in antiquity and to the Arabian geographers of the 2nd and 3rd centuries, the Amu Darya nevertheless received but little attention until the reign of Peter I of Russia. Though the first relatively authentic map of the river was made in 1734, systematic research of the river was begun only at the end of the 19th century. At the end of the 1920s a map of the entire Amu Darya basin was published in Tashkent. The Amu Darya's basin extends for 600 miles (950 km) from north to south and for more than 900 miles (1,450 km) from east to west. It borders on the Syr Darya basin in the north, on the Tarim Basin in the east, and on the Indus and Helmand river basins in the south. Of the basin's total area of 179,700 square miles (465,500 square km), only half belongs to the regions whence the river is fedthat is to say, to the mountain ranges to the east. Hydrologically, the Amu Darya's basin consists of two units: a mountainous zone of nourishment and a lowland zone of depletion. The Amu Darya's headwaters rise in the mountains of Tajikistan and Afghanistan, among the permanent snows and glaciers of the Pamirs (with the adjacent Alay Range to the northwest) and the Hindu Kush, where elevations range from 16,400 to 23,000 feet (5,000 to 7,000 m). The river's two principal upstream extensions, the Panj (including the Pamir and other source streams) and Vakhsh rivers, follow a westerly course. The river receives the name Amu Darya only below the confluence of the Panj with the Vakhsh. Not far below this junction the Amu Darya is joined by three additional tributaries: from the left (south) by the Qonduz River and from the right (north) by the Kofarnihon (Kafirnigan) and Surkhan rivers. After leaving the highland zone, the river veers to the northwest to cross the arid Turan Plain, where it forms the boundary between the Karakum Desert to the southwest and the Kyzylkum Desert to the northeast. There the Amu Darya loses much of its water to irrigation, evaporation, and seepage. In its once-extensive delta the Amu Darya branched into a number of tributaries that emptied into the Aral Sea. A massive diversion of water from the main stream and from its tributaries was undertaken by the Soviet regime in the decades after World War II in order to provide irrigation for cotton and other crops grown in the river's basin. The main section of the Karakum Canal was completed in the 1960s to carry water from the Amu Darya at Kerki, Turkmenistan, westward to Mary and Ashgabat. The diversion of its waters for irrigation increased the Amu Darya's level of salinity and left less water to enter the Aral Sea, which consequently began shrinking. By the 1990s the discharge of the Amu Darya into the Aral Sea stopped for one to three months in most years. Most of the lakes and bogs in the Amu Darya delta dried up, and its wetlands shrank to only a tiny percentage of their former size. Junipers and poplars grow down to the river's edge in the mountain regions, where sweetbrier and blackberries also abound. Willows, buckthorn, poplars, and oleasters predominate lower down. The trees along the river's lowest reaches once formed an impenetrable tangle at the river's reed-covered delta, but salt- and drought-resistant plants are now the predominant flora there. Few bird and fish species remain in the depleted and polluted waters of the lower Amu Darya and its delta. Animals once plentiful along the riverbanks include boar, wildcat, jackal, fox, and hare. The Amu Darya is largely dependent on the waters of its principal tributaries, the Panj and the Vakhsh, the greater part of whose flow derives from melting snow and ice. The Amu Darya's water volume increases from March to May, when snow melts on the plains and rainfall increases, and the flow is further augmented in June, July, and August as the ice and snow of the mountain ranges thaw. The flow gradually abates from September to February. During winter, ice forms along the banks of the river's upper reaches, and its lower sections may freeze completely for more than two months. As the ice floes begin to disperse in February and March, they jam the river downstream. In its upper course the river's flow is stable; in its lower course it is much less so, and the amount of sediment suspended in the water is very high. Even before its diminished lower reaches were closed to navigation, little transport was conveyed by the Amu Darya because of its unstable riverbed and shoals. A complex system of dams was erected from the mid-20th century, mainly on the lower course, to provide for irrigation and to protect the cultivated fields from floods. A giant (984-foot [300-metre]) dam and hydroelectric station was constructed on the Vakhsh River at Norak (Nurek), Tajikistan, in the 1970s and '80s, but a similar dam at Rogund (Rogun), Tajikistan, was severely damaged by floodwaters in the early 1990s.