Orange River, South Africa

The Orange River, in the past also sometimes known as the Gariep or as the Grootrivier, is the major river of South Africa. The river was first discovered by Europeans in 1760 and named after the House of Orange, which was the Stadhouder of Holland between 1777-79. Another account of its naming suggests that it may have been called after the supposedly orangy colour of its water, as opposed to the colour of the water of the Vaal River ( 'vaal' being Afrikaans for pale or grey).

The Orange Rive rises in the Drakensberg in Lesotho, where it is known as the Senqu. From where the river leaves Lesotho, it flows westward for some 2200km to where it finally flows into the Atlantic Ocean at Alexander Bay. At the source of the Orange River the rain fall is approximately 2000mm per annum and decreases as the river flows westward. At its mouth the rainfall is less than 50 mm per annum. Evaporation, on the other hand, increases in a westerly direction.