In general terms, the country can be divided into two basic drainage systems: the Orange River as one system, and all the other rivers comprising the other. These two systems are divided by the Great South African Escarpment, extending from the Richtersveld in the north-west of the country, south past the Cape Folded Mountains, eastwards to the Drakensberg and finally northwards to Tzaneen in the Northern Province. The Orange River drains from the interior of the country to the west.

All the other rivers drain from the coastal side of the escarpment to the ocean in western, southern and eastern directions. In the north the tributaries of the Olifants River disregard the escarpment, and a watershed has formed on the Witwatersrand, resulting in rivers such as the Crocodile and the Olifants flowing northwards into the Limpopo River.

The drainage areas of South Africa are also referred to as the primary catchments, and constitute the catchment areas of all the major rivers in the country. These drainage regions comprise areas of which the topography is such that all water deposited in the catchments will, except for evaporation and retention in the system, eventually end up in the main river flowing from that same catchment.

Primary river catchments such as the Orange, Vaal and Limpopo catchments are subdivided into contributing secondary catchments. They are, in turn, subdivided into even smaller tertiary catchments, which are finally subdivided into quarternary catchments, the smallest catchment units used in the management and planning of water resources at a national level.

 

Plastic pollution There are various uses for plastic bags, which means that plastic has extremely wide-ranging impacts on the environment. The careless disposal of plastic bags may block storm water drains, which may cause flood damage in urban areas, especially in a country like South Africa where heavy thunderstorms often occur. block the porosity of the soil and cause problems with groundwater recharge. disturb the soil microbe activity. kill animals once it has been ingested. cause visual pollution, which may have a very negative impact on the quality of tourist experiences and the quality of the environments where people live. Plastic bags and other plastic products also pose a serious hazard to the marine environment. When dumped, abandoned or lost in marine environments plastic items not only look unattractive, but can harm the environment in various ways: Serious impacts arise from entanglement of marine animals in plastic debris and from the ingestion of plastic by aquatic organisms. Marine debris poses a threat to humans when divers, ships or boats become embroiled in debris. Beaches and waterfronts are becoming littered with plastic garbage, which is detrimental to tourism and requires costly cleanup procedures. What you can do to reduce plastic pollution? Carry your own cloth bag or rucksack when shopping. Do not accept plastic bags as far as possible. When purchasing your monthly groceries, put the grocery items direct into the trolley and transfer these items to cardboard boxes or other more durable containers for easy transportation. Reuse plastic bags.