The Vaal River
Vaal River, a river in South Africa. It is the chief tributary of the Orange River. The name is the Dutch word for "yellow." The Vaal's source is in the Drakensberg range in Mpumalanga Province, near the Swaziland border. The river flows 750 miles (1,200 km) southwestward to its junction with the Orange. It forms most of Free State's northern border. The Vaal is a major source of hydroelectric power and water for irrigation.