Long-term trends and variability in the microclimates of the uMngeni Catchment, KwaZulu-Natal, South Africa and potential impacts on water resources

The past few decades have produced a wealth of research investigating the extent and severity of global climate change. Patterns in climate variability and change have been studied at global, continental and regional scales. Trends observed at these larger spatial scales are expected to be observable at smaller scales, although research in this regard has been limited in South Africa. This study presents an investigation into the microclimatic trends of a key catchment in the KwaZulu-Natal province, South Africa, with particular focus on water resources. Long-term (1980–2017) historical daily meteorological data were analysed using the RClimDex software package as well as other multi-temporal regression and time series analyses. Results indicate an overall warming of the study sites between 1 and 4 °C century−1. Atmospheric water vapour pressure was found to be increasing significantly at three of the sites. Total annual rainfall, an important variable for water resources of the catchment, did not display significant change in the catchment but high levels of inter-annual variability were observed. The results of the study indicate that the catchment microclimate has changed, and is changing, but at different rates from global and continental estimates. The study emphasises the importance of catchment scale analyses using ground-based historical meteorological data.