Impact of Climate Change on Precipitation in Zambeze River Basin in Southern Africa

摘要

The Intergovernmental Panel on Climate Change (IPCC) concluded that there is a consensus that the increase in atmospheric greenhouse gases will result in climate change, which will cause the sea level to rise, increase frequency of extreme climatic events such as intense storms, heavy rainfall events and droughts. This will increase the frequency of climate-related hazards, causing loss of life, social disruption and economic hardships. There is less consensus on the magnitude of change of climatic variables, nonetheless several studies have shown that climate change will have an impact on the availability and demand for water resources. Southern Africa lies in one of the regions of the world that is most susceptible to climate variability and change. In southern Africa, climate change is likely to affect nearly every aspect of human well-being, from agricultural productivity and energy use to flood control, municipal and industrial water supply as well as wildlife management, since the region is characterized by highly spatial and temporally variable rainfall, and in some cases, scarce water resources. This study presents the future change projection in precipitation under RCP2.6, RCP4.5 and RCP8.5 scenarios of the CanESM2 outputs using the Statistical Downscaling Model (SDSM) for 50 stations in Zambeze River basin during the two future periods: near future (2031-2060) and far future (2071-2100). For assessment of climate change, the baseline period (1979-2013) was partitioned into two periods for SDSM calibration (1979-1996) and validation (1997-2013). The results show that SDSM was not a very robust method for the simulation of precipitation for this study area, the model could not replicate observed precipitation very well. This is due to its conditional nature and high variability in space. The results also showed that there is a decrease in monthly precipitation during wet period (October-March) and an increase during the dry period (April-September). The upward monthly increase in projected precipitation expected is in August (300%, 325%) with RCP4.5 and maximum decrease in March (38%) with RCP4.5 for all scenarios for NF and FF respectively, and the projected annual precipitation is expected to decrease with time for all scenarios. It was observed that the maximum decrease will range from 7-21.8% for near future (NF) and 2-21% for far future (FF).