Types of Rivers

The water supply in the river determines its type. 

1.  Permanent (or perennial) rivers are always flowing even if the level fluctuates.  This is common in wet areas.  These rivers mostly run into the sea.  Only half South Africa’s rivers are permanent.

2.  Periodic rivers are fed by groundwater only in the rainy season when the water table is higher than the level of the riverbed.  These are seasonal rivers.  This is common in drier areas.  Many periodic rivers never reach the sea but can empty into inland drainage basins. 

3.  Episodic rivers never receive groundwater and only flow when there is an episode of heavy rain.

When a river like the Orange (or Gariep) flows through a wet area and then a dry area, it is known as an exotic river.  Because the Orange carries such a large volume of water, it flows through a very long distance of the dry Northern Cape and still drains into the ocean.  The Nile is also exotic, as it flows through the Nubian and Arabian deserts.

In South Africa nearly half the rivers are temporary.  The permanent rivers are mostly in the east and south-west ie Western Cape, Eastern Cape, Kwa-Zulu Natal, Gauteng, Mpumalanga, Limpopo, North-West Province. 

The rest of the country is dry and hot. (eg: Karoo, Kalahari and Namaqualand) Rivers are episodic in these areas.