Abstract:
This study used the Soil and Water Assessment Tool (SWAT) model together with regional climate
downscaled (RCD) data from the CORDEX (Africa project), to assess the local seasonal precipitation
variability in the upper middle catchment (UMC) of the Olifants River basin. The study results, based
on two scenarios (RCP4.5 and RCP8.5), showed a wider monthly and seasonal variability of
precipitation. The study also indicated a strong decreasing trend of east-to-west direction of spatial
precipitation, with most precipitation concentrated in the eastern part of the study area. Within the
western part of the UMC, we also noted another decreasing trend of precipitation from south-tonorth
with northern areas of the study area receiving the least amount of precipitation. This study
has also revealed a considerable general reduction of future seasonal precipitation especially in the
mid-term period (2021–2050). The general reduction in future seasonal precipitation, combined with
the increasing temperatures in the area, may exacerbate the drought conditions and reduction in
streamflow of the main river (Olifants) and its tributaries, consequently having a negative impact on
the economic activities in the basin.
