Civil Engineering June 2022 | Vol 30 No 5

Civil Engineering June 2022 1 T he devastation that excessive rainfall can cause is still fresh in our minds following the recent floods in KwaZulu-Natal (KZN) and the Eastern Cape (EC). And if the first flood was not devastating enough, the poor folks in those areas were surprised by a second heavy rain period a few weeks later, adding damage to infrastructure and suffering for inhabitants. Flooding can, as witnessed in these areas, sig- nificantly hinder economic opportunities, transpor- tation of goods and services, as well as mobility and access to essential services, including health and education. One of the drivers blamed for the excessive rainfall is climate change. Climate change refers to long-term shifts in temperatures and weather patterns. According to the UN , “These shifts may be natural, such as through variations in the solar cycle. But since the 1800s, human activities have been the main driver of climate change, primarily due to burning fossil fuels like coal, oil and gas.” CLIMATE CHANGE IN SA In the South(ern) African context, the prediction is that our climate will drastically change. On average, tem- peratures in Africa are projected to increase by between 1.5 to 2 times the global rate and Southern Africa is projected to become drier. More than 40% of heat-related deaths in South Africa be- tween 1991 and 2018 were already attributable to climate change.* The CSIR published the Greenbook – adapting settlements for the future in 2019. The document uses recorded weather information from 1961 to 1990 along with a low and high mitiga- tion scenario to predict the future temperatures, fire risks, rainfall and wind speeds. The report warns that “climate change impacts are not to manifest only through changes in average temperature and rainfall patterns, but also through changes in the attributes of extreme weather events”, such as floods. This was earlier also projected by Engelbrecht et al. (2013) who predicted, “more intense thunderstorms to occur more frequently over South Africa.” For the period 2021 to 2050, the Greenbook report predicts that temperature will increase by 1°C to 2.5°C in the southern coastal regions, while in the interior regions of South Africa will see larger temperature increases of approximately 3°C, especially with low mitigation efforts, as is the case currently. For the period between 2070 and 2099, temperature increases are predicted to rise by another 2°C to 3°C in the southern coastal regions, and more than 4°C inland. The northern interior, in the low mitiga- tion scenario “may well see temperature increases in that period that exceed 7°C.” For the period 2021 to 2050, the effects include unprecedented high numbers of fire-danger days, heat-wave days and very hot days. During the period 2071 to 2099, the changes may hit “devas- tating proportions under low mitigation predic- tions, at least in terms of impacts on agriculture and livestock over the western interior and the Limpopo basin.” As indicated, climate change and rising temperatures also generate more extreme weather patterns. Average rain patterns in South Africa vary significantly. The Greenbook states that, “There is a pronounced west-east rainfall gradient over the country. Over the eastern escarpment and east coast, the simulated annual rainfall totals exceed 1 000 mm.” If the lack of climate mitigation perseveres in South Africa, it is expected that rainfall will increase over the central interior and the east coast (see Figure 1), for the period 2021 to 2050. The western interior, north- eastern parts, as well as the winter rainfall region of the south-western Cape are bound to become drier. The floods in KZN and the EC, as devastating as they were, could be considered early warning signs. Given the predictions, it is likely that more unpredictable weather conditions and floods are to follow, and not only in the regions mentioned. Furthermore, the described droughts will affect South Africa’s water and food availability. As the SAICE President I call on government to take climate change seriously and start climate mitigation actions immediately, so that water, in its many forms, does not become a curse to our nation. REFERENCES Engelbrecht C.J., Engelbrecht F.A. and Dyson L.L. 2013. High-resolution model projected changes in mid-tropospheric closed-lows and extreme rainfall events over southern Africa. Int J Climatol, 33, 173–187. doi:10.1002/joc.3420. James, R. and Washington, R. 2013. Changes in African temperature and precipitation associated with degrees of global warming. Climatic Change 117 859–872. DOI 10.1007/s10584-012-0581-7. *Additional references available on request. Prof. Marianne Vanderschuren SAICE President 2022 marianne.vanderschuren@uct.ac.za From the Pres ident ’ s desk Water in South Africa, blessing or curse? Figure 1 Medium simulated annual average rainfall changes (mm), for the low climate mitigation scenario (2021 to 2050 compared to the baseline period 1961 to 1990 at 8 km resolution) (Source: Engelbrecht (2019) in www.greenbook.co.za )