Orange River

Orange
Gariep, Oranje, Senqu
River
Sunset over the Orange River near Upington in the Northern Cape
Countries	Lesotho, South Africa, Namibia
Tributaries
- right	Caledon River, Vaal River, Fish River (Namibia)
Landmarks	Gariep Dam, Augrabies Falls
Source	Thaba Putsoa
- location	Maloti Mountains (Drakensberg), Lesotho
- elevation	3,350 m (10,991 ft)
Mouth	Alexander Bay
- location	Atlantic Ocean
Length	2,200 km (1,367 mi)
Basin	973,000 km2 (375,677 sq mi)
Discharge
- average	365 m3/s (12,890 cu ft/s)
The course and watershed of the Orange River, Caledon River and Vaal River. This map shows a conservative border for the watershed. Specifically, the Kalahari basin is excluded, as some sources say it is endorheic. Some other sources using computational methods show a basin which includes parts of Botswana (and hence of the Kalahari).

The Orange River (Afrikaans/Dutch: Oranjerivier) is the longest river in South Africa. It rises in the Drakensberg mountains in Lesotho, flowing westwards through South Africa to the Atlantic Ocean. The river forms part of the international borders between South Africa and Namibia and between South Africa and Lesotho, as well as several provincial borders within South Africa. Except for Upington, it does not pass through any major cities. The Orange River plays an important role in the South African economy by providing water for irrigation, as well as hydroelectric power. The river was named by Robert Jacob Gordon after the Dutch Royal House. Other names include Gariep River (used by the Khoi people), Groote River or Senqu River (used in Lesotho). The official name, however, is the Orange River.

The Orange rises in the Drakensberg mountains along the border between South Africa and Lesotho, about 193 km (120 mi) west of the Indian Ocean and at an altitude of over 3,000 m. While in Lesotho, the river is known as the Senqu and parts of it freeze in winter, because of the high altitude there. This creates droughts downstream of it which mainly affects goat and cattle production.

The river then runs westward through South Africa, forming the south-western boundary of the Free State province. In this section the river flows first into the Gariep Dam (the largest in the country), and later into the Vanderkloof Dam. From the border of Lesotho to below the Van der Kloof Dam the river bed is deeply incised. Further downstream the land is flatter, and the river is used extensively for irrigation.

At the western point of the Free State, southwest of Kimberley, the Orange meets with its main tributary, the Vaal River, which itself forms much of the northern border of the province. From here the river flows further westward through the arid wilderness of the southern Kalahari region and Namaqualand in the Northern Cape Province to meet with Namibia at the 20th degree of east longitude. From here it flows westward for 550 km, forming the international border between the province and Namibia's ǁKaras Region. On the border, the river passes the town of Vioolsdrif, the main border post between South Africa and Namibia.