OB RIVER

Ships docked at the port of Salekhard on the lower Ob River, northwestern Siberia. great river of Russia, flowing across western Siberia in a winding course northwestward from its sources in the Altai Mountains of Central Asia to its outlet through the Gulf of Ob into the Kara Sea of the Arctic Ocean. The length of the Ob is calculated at 2,268 miles (3,650 km), from the source of the Ob proper (the confluence of the Biya and Katun rivers) to the head of its gulf on the Kara Sea, or as 3,362 miles (5,410 km), from the source of its greatest tributary, the Black Irtysh, to the end of the gulf. The river's other major tributaries include the Chulym, Ket, Vakh, Vasyugan, Kazym, and Northern (Severnaya) Sosva. Together they drain a basin of approximately 1,150,000 square miles (about 2,975,000 square km); there are more than 1,900 rivers within the drainage basin. The West Siberian Plain covers about 85 percent of the Ob basin, the rest of which is occupied in the south by the terraced plains of Torghay and the small hills of northernmost Kazakstan, and in the southeast by the Kuznetsky Alatau, the Salair Range, the Mountains of Shoria, and, behind them, the Altai Mountains. From south to north the basin represents a geographic cross section of central and northern Asia; in the far south, around Lake Zaysan, there is arid semidesert; in the central regions of the West Siberian Plain swampy coniferous forest known as taiga, with very large expanses of marshland, dominates; and in the north there are vast stretches of icy, treeless plains known as tundra. The average annual discharge of the Ob River is 448,500 cubic feet (12,700 cubic m) per second. Most of the water comes from the melting of seasonal snow and from rainfall; along the middle and lower Ob spring and summer floods may last four or five months. The entire length of the river is generally frozen solid by the end of November, with the upper reaches remaining so for some 150 days, the lower reaches for 220 days. The Ob provides one of western Siberia's principal means of communication and is navigable during iceless months, serving as both an import and export route. The Ob's total hydroelectric potential is large, estimated at some 250 billion kW-hr. The Ob and Yenisey river basins and their drainage networks. river of Russia. One of the greatest rivers of Asia, the Ob flows north and west across western Siberia in a twisting diagonal from its sources in the Altai Mountains to its outlet through the Gulf of Ob into the Kara Sea of the Arctic Ocean. It is a major transportation artery, crossing territory at the heart of Russia that is extraordinarily varied in terms of physical environment and the character of its peoples. Even allowing for the barrenness of much of the region surrounding the lower course of the river and the ice-clogged waters into which it discharges, the Ob drains a region of great economic potential and has been the subject of considerable long-term development planning. The Ob proper is formed by the junction of the Biya and Katun rivers, in the foothills of the Siberian sector of the Altai, from which it has a course of 2,268 miles (3,650 kilometres). If, however, the Irtysh River is regarded as part of the main course rather than as the Ob's major tributary, the maximum length, from the source of the Black (Chorny) Irtysh in China's sector of the Altai, is 3,362 miles (5,410 kilometres), making the Ob the seventh longest river in the world; another 500 miles can be added to this total if the Gulf of Ob is included. The catchment area (excluding the Gulf of Ob) is approximately 1,150,000 square miles (2,975,000 square kilometres). The Ob's catchment area constitutes about half of the drainage basin of the Kara Sea; it is the sixth largest catchment area in the world. Additional reading The Ob River is described in broad geographic surveys of North Asia that provide information on physical features and on economic, social, and cultural conditions: Paul E. Lydolph, Geography of the U.S.S.R., 5th ed. (1990); Michael T. Florinsky (ed.), McGraw-Hill Encyclopedia of Russia and the Soviet Union (1961), with short articles on the individual rivers; S.V. Kalesnik and V.F. Pavlenko (eds.), Soviet Union: A Geographical Survey (1976; originally published in Russian, 1972); and Great Rivers of the World (1984), published by the National Geographic Society. M.I. L'vovich, Reki SSSR (1971), is a well-known work treating the hydrologic characteristics of the main rivers of the former U.S.S.R. Lev Konstantinovich Davydov, Gidrografiia SSSR, vol. 2 (1955), provides detailed studies of regional hydrology and hydrography. G.V. Voropaev and A.B. Avakian (eds.), Vodokhranilishcha i ikh vozdeistvie na okruzhaiushchuiu sredu (1986), examines the influence of water reservoirs on the environment. Robert Paul Jourdan, Siberia's Empire Road: The River Ob, National Geographic, 149(2):145181 (February 1986), describes the life of the peoples of the area, the environment, and the economic situation. Schemes for large-scale water transfer are described in several articles by Philip P. Micklin: A Preliminary Systems Analysis of Impact of Proposed Soviet River Diversions on Arctic Sea Ice, Eos, 62(19):489493 (1981), focusing on the possible impact on the Kara Sea, into which the Ob drains, The Vast Diversion of Soviet Rivers, Environment, 27(2):1220, 4045 (March 1985), and The Status of the Soviet Union's North-South Water Transfer Projects Before Their Abandonment in 198586, Soviet Geography, 27(5):287329 (May 1986). Philip P. Micklin