Abstract:
This study dealt with the influence of climate variability on flood and drought cycles and implications on
rainy season characteristics in Luvuvhu River Catchment (LRC) in Limpopo of South Africa. Extreme
weather events resulting in hazards such as floods and droughts are becoming more frequent due to
climate change. Extreme events affect rainy season characteristics and hence have an influence on water
availability and agricultural production. Annual temperature was obtained from Water Research
Commission for stations 0723485W, 0766628W and 0766898W from 1950-2013 were used to show/or
confirm if there is climate variability in LRC. Daily rainfall data was obtained from SAWS for stations
0766596 9, 0766563 1, 0723485 6 and 0766715 5 were used to detect climate variability and determine
the onset, duration and cessation of the rainy season. Streamflow data obtained from the Department of
Water and Sanitation for stations A9H004, A9H012, and A9H001 for at least a period of 30 years for
each station were used for climate variability detection and determination of flood and drought cycles.
Influence of climate variability on floods and droughts and rainy season characteristic were determined in
the area of study. Trends were evaluated for temperature, rainfall and streamflow data in the area of study
using Mann Kendall (MK) and linear regression (LR) methods. MK and LR detected positive trends for
temperature (maximum and minimum) and streamflow stations. MK and LR results of rainfall stations
showed increasing trends for stations 0766596 9, and 0766563 1 whereas stations 0723485 6 and
0766715 5 showed decreasing trends. Standardized precipitation index (SPI) was used to determine floods
and droughts cycles. SPI results have been classified either as moderately, severely and extremely
dry or, moderately, very and extremely wet. This SPI analysis provides more details of
dominance of distinctive dry or wet conditions for a rainy season at a particular station. Mean
onset of rainfall varied from day 255 to 297, with 0766715 5 showing the earliest onset compared to the
rest of the stations. Cessation of rainfall for most of the hydrological years was higher than the mean days
of 88, 83 and 86 days in 0766596 9, 0766563 1 and 0723485 6 stations. Mean duration of rainfall varied
from 102 to 128, with station 0766715 5 showing shortest duration of rainfall. The results of the study
showed that the mean onset, duration and cessation were comparable for all stations except 0766715 5
which had lower values. The study also found that climate variability greatly affects onset, duration and
cessation of rainfall during dry years. This led to late onset, early cessation and relatively short duration
of the rainfall season. Communities within the catchment must be educated to practice activities
such as conservation of indigenous plants, reduce carbon dioxide emissions.
