Investigation into increasing short-duration rainfall intensities in South Africa
Date
2015-04
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Water Research Commission
Abstract
Extreme storms in South Africa and specifically in the Western Cape have been responsible for widespread destruction to
property and infrastructure, even leading to displacement and death. The occurrences of these storms have been increasingly
linked to human-induced climate change that is expected to cause more variable weather. Studies on climate circulation
models for future climate conditions project that rainfall in the Western Cape and wider South African region is to become
more intense and extreme. Sub-daily rainfall for 3 stations in the Western Cape and 4 stations in the rest of South Africa were
analysed in order to determine if any trends towards more intense and extreme rainfall are observed and whether the trend is
unique to the Western Cape or indicates a wider trend. This study explores this expectation by using historical short-duration
rainfall (less than 24 h) for 7 stations in the Western Cape and South African region. Digitised autographic and automatic
weather station 5-min rainfall data were combined to extend the effective record length. Both the magnitude and frequency
of occurrence of rainfall events were analysed to assess if rainfall intensities are showing any evidence of increasing over time.
For the magnitude of rainfall events, extreme value theory was applied to non-stationary sequences, using both a parametric
and non-parametric approach for both event maxima and peaks over threshold modelling. The frequency analysis entailed
measuring the frequency of exceedance of rainfall events over a certain threshold value. Both the magnitude and frequency
analysis indicated that the combination of the two record types influenced the results of some of the stations, while the others
showed no consistent evidence of changing rainfall intensities. This led to the conclusion that, from the available observed
short-duration record, no evidence was found of trends or indications of changes in rainfall intensities.
Description
CITATION: Du Plessis, J. A. & Burger, G. J. 2015. Investigation into increasing short-duration rainfall intensities in South Africa. Water SA, 41(3):416-424, doi:10.4314/wsa.v41i3.14.
The original publication is available at http://www.wrc.org.za/Pages/default.aspx
The original publication is available at http://www.wrc.org.za/Pages/default.aspx
Keywords
Climate change -- South Africa -- Western Cape, Short duration rainfall -- South Africa -- Western Cape, Rain and rainfall -- South Africa -- Western Cape, Climatic extremes -- South Africa -- Western Cape
Citation
Du Plessis, J. A. & Burger, G. J. 2015. Investigation into increasing short-duration rainfall intensities in South Africa. Water SA, 41(3):416-424, doi:10.4314/wsa.v41i3.14.
Du Plessis, J. A. & Burger, G. J. 2015. Investigation into increasing short-duration rainfall intensities in South Africa. Water SA, 41(3):416-424, doi:10.4314/wsa.v41i3.14.
Du Plessis, J. A. & Burger, G. J. 2015. Investigation into increasing short-duration rainfall intensities in South Africa. Water SA, 41(3):416-424, doi:10.4314/wsa.v41i3.14.