There is a real threat of increased flooding and possible damage to infrastructure, with climate change said to be affecting the intensity of rainfall, according to experts at the University of Pretoria (UP).
UP researchers Charlotte McBride, Andries Kruger and Liesl Dyson have investigated whether there are observable changes in the probability of significant to extreme daily rainfall in South Africa.
They found the amount of rain in certain parts of South Africa has increased or become more extreme over the past 50 years.
“One of the consequences of human-induced climate change is the increase in frequency and/or intensity of some weather and climate extremes. These can include heatwaves, heavy rainfall, floods, droughts and tropical cyclones,” said McBride.
“South Africa is focused on flooding, as this is what is happening at the moment.”
However, during 2018 — when Cape Town was about to run out of water — public attention was focused on drought.
“The increases in the water-holding capacity of the atmosphere equate to about 7% per degree of warming. With more moisture available, the nature of rainfall events is likely to become more intense, with increased rainfall rates,” the researchers found.
“Changes in extreme rainfall patterns are thought to be highly regionalised.”
They mapped out areas where higher rainfall is experienced.
“Some stations over the eastern parts showed increases of more than 100mm in the later period compared to the early period, when considering the one in 50 and one in 100 years return period values. For example, the Letaba district rainfall station in Limpopo experienced an increase of more than 35%,” said McBride.
“Another example is Hlobane in KwaZulu-Natal, where the one in 50 and one in 100 years values have doubled. This means these areas and others highlighted in the research, such as the western interior and southern parts of the country, are likely to experience more extreme rainfall, which is probably a feature of climate change over those areas.”
South Africa is projected to become warmer and thus experience an increase in the occurrence of droughts.
“There is a lot of work being done internationally and in South Africa on climate change using numerical weather prediction data,” said Dyson, associate professor in meteorology at UP.
“These results are based on what we know has happened over the past century and show that in general, rainfall extremes are becoming more probable and therefore increasing in South Africa.
“Researchers using numerical weather prediction data could also use these results to verify the models they use to capture the current situation accurately, thereby placing a higher value on the reliability of projections in the future.”