South Africa is an arid country with only 8.6% of the rainfall available as surface water. This is one of the lowest conversion ratios in the world. The mean annual runoff (MAR) for South Africa is estimated at some 50 million m3 a-1. This is not distributed evenly throughout the country, with the Eastern seaboard having some 80% of the country’s runoff, whilst the western regions tend to have low runoff. Nor is it consistent over time, with great variability between years. Similar to surface waters, South Africa’s groundwater resources are relatively limited compared to world averages.
The scarcity of freshwater resources and highly variable hydrological conditions have led to every major river in South Africa being regulated in order to ensure adequate water supply for development. However, because of the spatial variability of water resources and the scarcity of water throughout the country, in many catchments the need for water exceeds the supply. This situation is likely to worsen as the discrepancies between water requirements and availability in other water-scarce catchments increase.
The scarcity of water is compounded by pollution of the surface- and ground-water resources. Typical pollutants of South Africa’s freshwater environment include industrial effluents, domestic and commercial sewage, acid mine drainage, agricultural runoff, and litter. As many of these sources are spreadout across the country, it is difficult to estimate the magnitude of the pollution problem. However, Western Cape, Eastern Cape, KwaZulu-Natal and the Vaal rivers have major problems with Total Dissolved Solids (TDS), and most of South Africa’s rivers have an eutrophication problems.
State of the Environment – South Africa