A STUDY: WATER SECURITY AND CLIMATE CHANGE RISKS FOR MUNICIPALITIES This study (done in support of the CSIR Greenbook) presents a first order assessment of current and future water security risks for municipalities across South Africa, as a result of both expected climate change impacts as well as future population growth scenarios up to 2050. By Dr James Cullis
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opulation growth and economic development coupled with the likely impacts of climate change pose serious water security challenges for municipalities across South Africa. While large parts of Southern Africa are likely to experience drying conditions as a result of the impacts of climate change, it is not all doom and gloom from a water security perspective. Due to variability in the impacts of climate change, some areas of South Africa could see some potential benefits, while other areas will almost definitely be losers. Particular hotspots of concern are: • the south-west of the country, due to the likelihood of decreasing rainfall and increasing population growth • to a lesser extent, the extreme north of the country, due to increasing temperatures and additional population growth partly driven by increasing regional migration. Conversely, the eastern part of the country is expected to see a possible average increase in rainfall. Even in areas considered to be winners due to the potential for increasing precipitation, there is still likely to be increasing risks due to greater inter-annual variability and greater intensity of rainfall events and associated flooding. A study done as part of the Long-Term Adaptation Scenarios (LTAS) research programme
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IMIESA May 2022
showed that 30% of bridges, 19% of dams and 29% of powerline crossings have a high to very high risk of an increase in design capacity floods. It must be noted, however, that some towns – particuarly rural ones – are likely to also experience a decline in population, particularly due to urban-rural migration or if local industries close or proposed developments do not materialise, which could reduce the overall water security challenge even in a drying climate.
A general climate change risk equation A general risk equation was developed to determine the current and future water supply vulnerability for all municipalities across South Africa. It combines both the anticipated climate change impacts on water availability and development risks (due to an increase in population and an associated increase in water demand). The general risk equation recognises that risk is not just based on the direct exposure to climate change (for example, the change in precipitation or run-off) but is also dependent on the vulnerability of each town in terms of its current and future water demand and water supply options. Future water supply risk is therefore affected by both the availability of water – either from surface or groundwater
Dr James Cullis, water resource engineer and expertise leader: Sustainability Consulting, Zutari
sources that are impacted differently by climate change – and by changes in demand, driven primarily by population dynamics, but also affected by increasing temperatures and climate change. The relative change will vary between towns and cities based on their location and future development potential, and must be taken into consideration for planning purposes. This is a first order estimate of the relative future water security risks for all local municipalities across South Africa. Given the high-level nature, several assumptions have been made that would differ from more focused analysis of individual water supply systems. As a result, it should not be taken as the final climate change risk profile for any specific individual local municipality, but rather as an indication of overall trends and highlighting key issues to be investigated further. Additional analysis is required specifically as regards the unique nature of the water supply system to each individual municipality, particularly when integrated with a regional or bulk water supply system.
