Climate Change Impact on Hydrological Regimes and Extreme Events in Southern Africa

Climate change is expected to exacerbate current stresses on water resources resulting from population growth, economic factors and land use changes, impacting on the availability of water resources and the sustainability of local ecosystems. In southern Africa, changes in the intensity, frequency and duration of weather extremes have resulted in recurrent droughts, floods, tropical cyclones among other phenomena. For example, the El Nino-Southern Oscillation effect has intensified in the past four decades (1900–2010) resulting in increased frequency of floods and droughts in Southern Africa. Furthermore, the projected increase in the frequency of droughts is likely to reduce flows and water storage. On the other hand, some regions may experience an increase in the frequency and magnitude of extreme precipitation events associated with flooding (and extreme high flows). Countries like Mozambique, South Africa, Malawi and Zimbabwe are already experiencing recurrent floods and droughts. Projected increases in the frequencies and magnitudes of such events through to 2050, coupled with rising populations in the region, suggests that the vulnerability of weather-sensitive sectors, particularly water resources and agricultural production will increase. This will affect aquatic ecosystems, water supply, irrigation, leisure, and hydropower generation. The implications of these findings are as follows: (1) Water availability is likely to be compromised, (2) Water management measures are likely to be tightened. (3) Dependence on rain-fed agriculture is likely to increase food insecurity for most southern African countries as a result of reduced agricultural production. (4) Similarly, electricity generation is likely to be reduced due to increased droughts and enhanced evapotranspiration as a result of the high temperatures. It is thus concluded that southern Africa is deemed to be a particularly vulnerable region on the African continent, as multiple biophysical, political and socioeconomic stresses interact to heighten the region’s susceptibility to climate change and variability and constrain its adaptive capacity. Thus, there is need to increase resilience of ecosystems and communities in light of the anticipated changes in hydrological regimes and extreme events.