Nokwethaba MAKHANYA, University of Cape Town, South Africa
Babatunde ABIODUN, University of Cape Town, South Africa
Piotr WOLSKI, University of Cape Town, South Africa
Climate change possibly intensifies hydrological droughts and reduces water availability in river basins. Despite this, most research on climate change effects in southern Africa has focused exclusively on meteorological droughts. This study projects the potential effect of climate change on the future characteristics of hydrological droughts in the Limpopo River Basin (LRB). The study uses a combination of regional climate model simulations (from the Coordinated Regional Climate Downscaling Experiment, CORDEX) and hydrological simulations (from the calibrated Soil and Water Assessment Tool Plus model, SWAT+) to project the impacts at four global warming levels under the RCP8.5 future climate scenario. The Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Precipitation Index (SPI) was used to detect meteorological droughts. The Soil Water Index was used to define agricultural drought, while the Water Yield Drought Index, the Surface Run-off Index, and the Streamflow Index were used to characterize hydrological drought. The simulations project a future increase in temperature and potential evapotranspiration over the basin but with no significant trend in precipitation. However, a decrease in all hydrological variables is projected over most parts of the basin, especially over the eastern part of the basin. The simulations predict that meteorological droughts, agricultural droughts, and hydrological droughts would become more intense and severe across the basin. SPEI-drought has a greater magnitude of increase than SPI-drought, and agricultural and hydrological droughts have a magnitude of increase that is part-way between the two. As a result, this research suggests that future hydrological droughts over the LRB could be more severe than the SPI-drought projection predicts but less severe than the SPEI-drought projection. This research can be used to mitigate the effects of potential climate change on basin hydrological drought.
Mots clés : Limpopo River Basin|Drought|Hydrological Modelling|Climate Change|CORDEX
A104447NM