The Council for Scientific and Industrial Research (CSIR) launched its highly anticipated Green Book, which provides decision-support to municipalities to adapt settlements across the country in light of projected climate change impacts.
The Green Book, co-funded with the Canadian International Development Research Centre, proposes a basket of mutually-supportive adaption interventions is integrated into a range of local planning instruments to adapt settlements to climate change risks in the future.
Water supply and climate change risks
South Africa has a highly complex and integrated bulk supply system consisting of dams and inter-basin transfers. Water supply is considered to be one of the principal mechanisms for the realisation of climate change impacts on society because water availability is directly related to changes in precipitation, temperature and evaporation. In addition, water is critical for livelihood support, health, economic growth and development. South Africa has developed a high level of skills in water resources planning. For example, stochastic time-series simulations are used to design the bulk water system to a high level of assurance of supply, which is then managed through the analysis of complex water resources system models for balancing demand and supply.
Climate change presents a number of risks to South Africa’s water resources, including changes in precipitation, changes in streamflow, declining water quality, as well as droughts, flooding and wildfire. The Green Book analyses these risk factors and translates them into the risks that municipalities will face as regards to providing water. Streamflow changes, for example, will impact the amount of water that flows into the rivers under future climate change scenarios, and in some cases, this could lead to less water supply in certain towns.
With an average rainfall of only 450mm/year, and significant annual and seasonal variability, South Africa is a water-scarce country. Rainfall also varies over 1900mm in the east of the country and in the mountainous areas to almost zero in the west and north-west. Conversion of rainfall to runoff is also low with an average mean annual runoff (MAR) of only 40mm, one-seventh
of the global average of 260mm per year. Like precipitation, runoff is highly variable in both space and time.
Demand for water is not evenly distributed, with most of the major water demand centres located far from the available water resources. The City of Johannesburg, for example, which is the major economic hub of the country to meet current and future demands. The International Commission of Large Dams (ICOLD) ranks South Africa sixth in the world in terms of the number of dams and we have a highly developed and complex bulk water supply infrastructure system that is capable of moving water from one part of the country to another.
A proactive approach to water resources planning, as well as investment in critical infrastructure, provides some reliability in the system despite highly variable precipitation and streamflow. This is critical to the economic development of South Africa and can also provide resilience to climate change impacts, provided it continues to be managed effectively.
If you are involved in settlement planning and disaster risk reduction be sure to check out the newly launched Green Book by the CSIR.