ORANGE RIVER

river, one of the longest in southern Africa. The Orange River rises in the Lesotho Highlands as the Sinqu River and flows westward as the Orange River across the Republic of South Africa, along the southern edge of the Kalahari (desert), and through the Namib (desert) before draining into the Atlantic Ocean at Alexander Bay, South Africa. Along part of its upper course, the river forms the boundary between the South African provinces of Free State (north) and Eastern and Northern Cape (south), while along its lower course the river forms the border between Namibia (north) and South Africa (south). The Orange River is about 1,300 miles (2,100 km) long and drains an area of roughly 330,000 square miles (855,000 square km). The Orange River's upper course in Lesotho is steep and marked by numerous rapids. Its major tributary after it enters South Africa is the Caledon River. Below the confluence with its other main tributary, the Vaal River, the Orange flows alternately through deep gorges and broad valleys. Farther downstream, at Upington, the river splits into innumerable channels and spreads out to a width of nearly 4 miles (6 km) in places, and some 20 miles (32 km) below Kakamas the river forms the Augrabies Falls. The lowermost course of the river, from the Augrabies Falls to the sea, similarly alternates between deep gorges and more open valleys. The river makes one last great bend as it flows north along the Richtersveld before turning west to the coastal desert of the Namib, where it empties into the Atlantic Ocean. There are two distinct rainfall patterns in the river basin. Above the Vaal River confluence, the river receives an annual rainfall of 2832 inches (700800 mm), most of which falls in summer; below the Vaal confluence, rainfall decreases from 9 inches (230 mm) a year to less than 2 inches (50 mm) in the Namib. Temperatures increase in a westerly direction, resulting in a higher rate of evaporation along the river's lower course. There are some irrigated sections along the river, but there are no large towns. This situation remained little changed by The Orange River Project (begun 1962), which was designed to accumulate water at several large dams for diversion to the valleys of the Great Fish and Sunday rivers and to the cities of Port Elizabeth and Bloemfontein. Physical features of southern Africa. river in southern Africa, one of the longest rivers on the continent and one of the longest south of the Tropic of Capricorn. After rising in the Lesotho Highlands, less than 125 miles (200 kilometres) from the Indian Ocean, the river flows to the Atlantic Ocean in a generally westerly direction for some 1,300 miles. The Orange traverses the veld region of South Africa, after which it defines the southern limit of the Kalahari and bisects the southern Namib before draining into the Atlantic at Alexander Bay, S.Af. Along its course the river forms the eastern boundary of the South African province of Free State, as well as the boundary between Namibia and South Africa. The Orange Rivertogether with the Vaal, its principal tributaryforms a drainage basin with an area of at least 330,000 square miles (855,000 square kilometres). The western part of the basin is generally dry, flat, and unamenable to cultivation without irrigation. The river itself is of vital economic importance to the region through which it flows. Two projectsthe Orange River Project and the Lesotho Highland Project, both in various stages of constructionhave been designed to meet the water demand for irrigation, urbanization, and economic development in the central industrial areas of South Africa. Additional reading Works on the Orange River include Department of Water Affairs, Management of the Water Resources of the Republic of South Africa (1986); and Monica M. Cole, South Africa, 2nd ed. (1966). Phillip S. Hattingh Johann Cooks Study and exploration The first white man known to cross the river to the north bank was an Afrikaner elephant hunter, Jacobus Coetsee, who forded the Groot River, as it was then called, near the river mouth in 1760. Later expeditions across the river in the 18th century were led by the Afrikaner explorer Hendrik Hop; Robert Jacob Gordon, a Dutch officer; William Paterson, an English traveler; and the French explorer Franois Le Vaillant. They explored the river from its middle course to its mouth, and Gordon named it in honour of the Dutch house of Orange. Mission stations were established north of the Orange from the late 18th century. In 1813 John Campbell of the London Missionary Society traced the Harts River and from its junction with the Vaal followed the latter stream to its confluence with the Orange, which he explored as far as the Augrabies Falls. The source of the Orange was first reached by the French Protestant missionaries Thomas Arbousset and Franois Daumas in 1836. Throughout the 19th century, the Orange River marked the northern limit of British power in southern Africa. Beginning in the 1830s, the Boers crossed it in search of land and freedom from British rule; they named their first republicthe Orange Free Statefor the river. John H. Wellington Phillip S. Hattingh Johann Cooks The people and economy The high valleys of the Orange River's headwaters are uninhabited, though the adjacent plateaus are used by the southern Sotho (Basuto) people for grazing land. Between the Lesotho border and the town of Aliwal North, corn (maize) is cultivated, and this region is also used as pasturage for cattle and sheep. The dry shrub country farther downstream is in general suitable only for grazing. Irrigated sections, however, occur along the river's course; the largest such area is between Upington and the Augrabies Falls, downstream of the Boegoeberg Dam (located midway between Prieska and Upington), where cotton, alfalfa (lucerne), grapes, and dates are grown. While scattered farms stand within reach of the river's freshwater supply, there are no large towns along the riverbank. This situation remains little changed by the Orange River Project (see below): much of the water accumulated by its dams is diverted to the valleys of the Fish and Sundays rivers and to the cities of Port Elizabeth, Bloemfontein, and Kimberley. Transportation Navigation is impossible throughout the river's course because of its irregular flow, its constant interruption by falls and rapids, and the silting that occurs in its channels and at the river mouth. Many bridges cross the river along its course between Aliwal North and Oranjemund, the largest being at Upington.