Researchers have found that Africa 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”.
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