Researchers at the University of Pretoria have found that the amount of rainfall in certain parts of South Africa has increased or become more extreme over the past 50 years or so. These investigations were part of a study led by Charlotte McBride of the South African Weather Service and a PhD candidate in UP’s Department of Geography, Geoinformatics and Meteorology. “With more moisture available, the nature of rainfall events is likely to become more intense with increased rainfall rates. However, changes in extreme rainfall patterns are thought to be highly regionalised”. To investigate if rainfall patterns are changing, the researchers analysed the daily time series of 70 manual rainfall stations between 1921 and 2020. This was divided into an early sub-period (1921 to 1970) and a later period (1971 to 2020). After comparing the rainfall figures in these two periods, it became evident that most rainfall stations showed an increase in their 1–50 and 1–100-year return period values. The two periods had more or less the same number of rain days (more than 1mm), but the rainfall amounts on any given rain day for certain parts of the country increased or became more extreme in the latter period. “We then mapped the change between the two periods as a ratio for each station. This gave us an idea of where areas are experiencing higher or lower rainfall values for the specific return periods”
