Open AccessRainfall and river flow trends for the Western Cape Province, South Africa
Author(s) -
Rakhee LakhrajGovender,
Stefan Grab
Publication year - 2019
Publication title -
south african journal of science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.317
H-Index - 61
eISSN - 1996-7489
pISSN - 0038-2353
DOI - 10.17159/sajs.2019/6028
Subject(s) - climate change , environmental science , period (music) , cape , climatology , range (aeronautics) , streamflow , geography , trend analysis , water resources , physical geography , hydrology (agriculture) , drainage basin , geology , oceanography , archaeology , geotechnical engineering , ecology , physics , materials science , cartography , machine learning , computer science , acoustics , composite material , biology
Climate change has the potential to alter the spatio-temporal distribution of rainfall, subsequently affecting the supply and demand of water resources. In a water-stressed country such as South Africa, this effect has significant consequences. To this end, we investigated annual and winter rainfall and river flow trends for the Western Cape Province over two periods: 1987–2017 and 1960–2017. Annual rainfall for the most recent 30-year period shows decreasing trends, with the largest magnitude of decrease at the SA Astronomical Observatory rainfall station (-54.38 mm/decade). With the exception of the significant decreasing winter rainfall trend at Langewens (-34.88 mm/decade), the trends vary between stations for the period 1960–2017. For the period 1987–2017, statistically significant decreasing winter trends were found at four of the seven stations, and range from -6.8 mm/decade at Cape Columbine to -34.88 mm/decade at Langewens. Similarly, the magnitudes of decreasing winter river flow at Bree@Ceres and Berg@Franschoek are greater for the more recent 30-year period than for 1960–2017. Correlation coefficients for Vilij@Voeliv rainfall and four river flow stations Berg@Franschoek, Bree@Ceres, Wit River@Drosterkloof and Little Berg@Nieuwkloof) are stronger for shorter periods (i.e. 1987–2017 and 2007–2017) than that for the longer period, 1960–2017. The Intergovernmental Panel on Climate Change emphasises the importance of studies to assist with model prediction uncertainties. To this end, our study expands the understanding of regional hydrological responses to rainfall change in the water stressed region of the Western Cape Province.