Impacts of Possible Climate Change and Variability on the Water Resources of Southern African: A Regional Modelling Approach

Abstract

An attempt is made in this chapter to present the results of a modelling study assessing the impact of possible climate change on the water resources of the Southern African Development Community (SADC) region, by consideration of the rainfall–runoff processes and the IPCC climate change scenarios. Adaptation mechanisms as well as abatement strategies and vulnerabilities over the region are highlighted. The study involves coupling global climate models with a GIS-based hydrological model to simulate the availability of water resources in Southern Africa under the current and post-climatic change conditions. Model inputs are the parameter values for the hydrological model, which are derived from the global datasets at 0.5° grid cells representing the region. The other inputs to the model are the climate variables of the 1961–1990 baseline climatology and the corresponding General Circulation Model (GCM)-derived climate for the 2050s. Water resources availability in the region in terms of river runoff, soil moisture and evapotranspiration is simulated using the hydrological model and a set of three GCM-derived climate change scenarios. The 1961–1990 model simulated mean annual runoff reveals mixed patterns of high and low runoff across the SADC countries. Although relatively small changes in runoff simulations are prevalent among the three climate change scenarios, it is evident from this study that there is a general decrease in runoff across the region reaching up to 20% under both the core and the dry scenarios for the 2050s. Uncertainties in simulated river flow change and variability in the region is discussed is in this chapter, along with possible adaption mechanisms for mitigating the impacts of climate change and variability.