South Africa is faced with two major challenges: limited water resources; and the need to ensure that the benefits of those resources are distributed equitably. Present population growth trends, and water availability and usage behaviors indicate that the country will exceed the limits of its economically usable, land-based water resources by 2050. Increase in variability of storm-flow and dry spells is a threat to water security. By 2050, the frequency of storm-flow events and dry spells is projected to increase, especially in the east, but reduce in the west. Median annual stream-flow is projected to increase in the east and decrease in the west over the same time period. Decline in run-off will add to the cost of providing water. It is estimated that just a 10% decline in run-off could double the cost of new water schemes, especially dams, in South Africa. Rising temperatures in the country will lead to more erratic weather, more flooding and greater rainfall variability. Higher temperatures will increase evaporation from dams and rivers, and will reduce run-off on the ground, so that less of the water that falls reaches the rivers and dams. In addition, inter-basin transfer schemes, high levels of assurance of supply to key sectors of the economy and extensive local reticulation networks require extensive pumping, with rising energy costs.
This section provides insights into projected climate change impacts on various hydrological indicators.