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Climate change in South Africa is expected to result in increased temperatures and decreased rainfall in much of the country. Figure 1 shows that most of the country will receive less rain, apart from Lesotho and the Eastern Cape Drakensberg.
These changes will directly impact on available water resources as evaporation losses increase, and river run-off and groundwater recharge decrease and become more variable. We expect more extreme events, such as floods and droughts, which will also require better disaster management.
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| Figure 1: Predicted future changes in precipitation (Schulze et al, 2005) |
South African water resources are already under stress. Figure 2 (based on Department of Water Affairs data) shows that most of the catchments in the country already use more water than they have available on an annual basis. This means that we are highly vulnerable to any decrease in rainfall.
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| Figure 2: 2005 Annual water balance in SA catchments.
Source: DWAF Water Situation Assessment Model |
The picture is slightly less bleak for groundwater resources (Figure 3), and over-use is more restricted to the Northern Cape and Klein Karoo. Most water stored in catchments is stored in aquifers underground, therefore groundwater can provide an important buffer against more uncertain rainfall in the future.
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| Figure 3: Balance of mean annual groundwater use vs recharge (%).
Source: DWAF GRA2, 2005 |
Adaptation to climate change will require an improved understanding of our water balance, water demand management, as well as strengthening engineering and community based capacity to respond to new water supply challenges.
References
- DWAF, 2005. Groundwater Resource Assessment (GRA) Phase 2.
- Schulze, et al. 2005. Climate Change and Water Resources in Southern Africa: Studies on Scenarios, Impacts, Vulnerabilities and Adaptation. Water Research Commission, Pretoria, RSA, WRC Report 1430/1/05. Chapter 9, p152.
By Christine Colvin, David Le Maitre & Daleen Lötter
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