Researchers have found thatAfrica has huge reserves of water underground, which they estimate are more than a hundred times the annual renewable freshwater resources.
Their findings, published in the academic journal Environment Research Letters, show that the largest reserves are in aquifers in the north African countries of Libya, Algeria, Egypt, Chad and Sudan.
The scientists used existing data, but for the first time this data was collated to give a continent-wide picture. They estimate that there are 0.66 million cubic kilometres of groundwater storage under Africa.
However, the researchers emphasise that it is important to take into consideration the rate at which this stored water can be replenished.
Whilst the largest reserves lie across the arid region of north Africa, these were filled five thousand years ago when the region was much wetter. There is plenty of water under this area, about seventy five meters deep, but whatever is taken out is not replenished.
Other factors to be taken into account are the geological characteristics of the underground water reservoirs. For example, if the groundwater is very deep underground it cannot be accessed by hand pump.
The researchers find that “for many African countries appropriately sited and constructed boreholes will be able to sustain community handpumps and for most of the populated areas of Africa, groundwater levels are likely to be sufficiently shallow to be accessed using a handpump”.
One of the report’s authors, Helen Bonsor of the British Geological Survey, told AIM that it is not appropriate to downscale the report’s findings, and that their work does not deal with the quality of the water stored. It thus does not deal with the issues of salinization or contamination, although she said that in general the stored water is purer than surface water. She stressed that the report is intended to encourage debate and more local research.
There is certainly a large amount of water under Mozambique, and the paper estimates that there are 6,290 cubic kilometres of groundwater stored under the country, with particularly large reserves under Maputo province.
The groundwater in Mozambique is replenished at a rate of between 25 and 100 millimetres per year, and is stored relatively close to the surface. The paper shows that the aquifer productivity for much of Mozambique is high.
The British Geological Survey has also been undertaking a one year research project funded by the British government’s Department for International Development, looking at the resilience of African groundwater to climate change.
That research found that “groundwater possesses a high resilience to climate change in Africa and should be central to adaptation strategies”.