Water supplies across Africa could be significantly depleted by climate change by the late 21st century, say South African geologists in a paper published online by Science today (3 March).
They say their findings underline the need to have effective water management systems across the continent, and particularly in rural areas whose normally year-round rivers are at risk of drying out in future.
Maarten de Wit and Jacek Stankiewicz of the Africa Earth Observatory Network in Cape Town found that three-quarters of African countries are at least partially in an "unstable" zone, where small reductions in rainfall could cause disproportionately large declines in river water.
They say the densely populated regions of southern Africa, large sections of the upper Nile and most of East Africa are "of particular concern".
For the South African city of Johannesburg, the researchers estimate that the ten per cent drop in annual rainfall predicted by climate models would reduce the surface water in rivers by nearly 20 per cent.
But in places such as Jendouba, Tunisia, or Tulear in Madagascar, the predicted ten per cent drop would dry up rivers entirely.
In Mogadishu, Somalia, climate change is predicted to increase rainfall by 20 per cent. Although this could increase water supplies ten-fold, this would not amount to much as the area gets so little rain to begin with.
Reference: Science doi: 10.1126/science.1119929 (2006)