'Huge' water resource exists under Africa


Related Stories

Scientists say the notoriously dry continent of Africa is sitting on a vast reservoir of groundwater.

They argue that the total volume of water in aquifers underground is 100 times the amount found on the surface.

The team have produced the most detailed map yet of the scale and potential of this hidden resource.

Writing in the journal Environmental Research Letters, they stress that large scale drilling might not be the best way of increasing water supplies.

Across Africa more than 300 million people are said not to have access to safe drinking water.

Demand for water is set to grow markedly in coming decades due to population growth and the need for irrigation to grow crops.

Africa aquifer map

Freshwater rivers and lakes are subject to seasonal floods and droughts that can limit their availability for people and for agriculture. At present only 5% of arable land is irrigated.

What is ground water?

When water falls as rain or snow, much of it either flows into rivers or is used to provide moisture to plants and crops. What is left over trickles down to the layers of rock that sit beneath the soil.

And just like a giant sponge, this ground water is held in the spaces between the rocks and in the tiny inter-connected spaces between individual grains in a rock like sandstone.

These bodies of wet rock are referred to as aquifers. Ground water does not sit still in the aquifer but is pushed and pulled by gravity and the weight of water above it.

The movement of the water through the aquifer removes many impurities and it is often cleaner than water on the surface.

Now scientists have for the first time been able to carry out a continent-wide analysis of the water that is hidden under the surface in aquifers. Researchers from the British Geological Survey and University College London (UCL) have mapped in detail the amount and potential yield of this groundwater resource across the continent.

Helen Bonsor from the BGS is one of the authors of the paper. She says that up until now groundwater was out of sight and out of mind. She hopes the new maps will open people's eyes to the potential.

"Where there's greatest ground water storage is in northern Africa, in the large sedimentary basins, in Libya, Algeria and Chad," she said.

"The amount of storage in those basins is equivalent to 75m thickness of water across that area - it's a huge amount."

Ancient events

Due to changes in climate that have turned the Sahara into a desert over centuries many of the aquifers underneath were last filled with water over 5,000 years ago.

The scientists collated their information from existing hydro-geological maps from national governments as well as 283 aquifer studies.

The researchers say their new maps indicate that many countries currently designated as "water scarce" have substantial groundwater reserves.

However, the scientists are cautious about the best way of accessing these hidden resources. They suggest that widespread drilling of large boreholes might not work.

Dr Alan MacDonald of the BGS, lead author of the study, told the BBC: "High-yielding boreholes should not be developed without a thorough understanding of the local groundwater conditions.

"Appropriately sited and developed boreholes for low yielding rural water supply and hand pumps are likely to be successful."

With many aquifers not being filled due to a lack of rain, the scientists are worried that large-scale borehole developments could rapidly deplete the resource.

Man filling jerry can African water supplies may be more resilient to climate change than was thought

According to Helen Bonsor, sometimes the slower means of extraction can be more efficient.

"Much lower storage aquifers are present across much of sub-Saharan Africa," she explained.

"However, our work shows that with careful exploring and construction, there is sufficient groundwater under Africa to support low yielding water supplies for drinking and community irrigation."

The scientists say that there are sufficient reserves to be able to cope with the vagaries of climate change.

"Even in the lowest storage aquifers in semi arid areas with currently very little rainfall, ground water is indicated to have a residence time in the ground of 20 to 70 years." Dr Bonsor said.

"So at present extraction rates for drinking and small scale irrigation for agriculture groundwater will provide and will continue to provide a buffer to climate variability."

The publication of the new map was welcomed by the UK's secretary of state for international development, Andrew Mitchell.

"This is an important discovery," he said. "This research, which the British Government has funded, could have a profound effect on some of the world's poorest people, helping them become less vulnerable to drought and to adapt to the impact of climate change."


More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites


This entry is now closed for comments

Jump to comments pagination
  • rate this

    Comment number 246.

    //Alan Walker
    1 Minute Ago
    @Drunken Hobo

    We also forgot about the masses of people in the UK and the US who deem it appropriate to have as many kids as possible so the state will provide them with more welfare benefits//

    I don't forget them - they are a serious problem, like immigrants.

  • rate this

    Comment number 245.

    Well I wish that Africans now can in some way extract this water sensibly so that the problem of drought can be lessen in Africa. I think people should stop being so negative about this continent all the time. Well-intentioness and positive encouragement are what they need.

  • rate this

    Comment number 244.

    I just hope that Africe can exploit its own resources for the benefit of its own people, rather than for the benefit of the West or China. We don't want them using their precious water to grow aubergines to be sold out of season to the UK middle classes whilst their own people starve to death. China is already milking Africa dry of its mineral resources. It's high time Africa's ship came in.

  • rate this

    Comment number 243.

    @207 'stennylfc'.
    Good point. It makes no sense to produce and bottle Coca Cola, that you mention, in any country short of clean drinking water for it's own population.

    No, I'm not anti-business. Employment is important. However, millions of tons of plastic bottles full of precious water flavoured by a sugar syrup is not progress in nations with shortages of clean/safe drinking water.

  • rate this

    Comment number 242.

    Since England is the 3rd most densely populated country in the world & has a 25% population increase projected by 2050 (source ONS & EC Eurostat) I think we are guilty of killing a lot of African people by consuming the food & water resources they need just to live; we justify it in the name of 'trade'. eg During the Somalia Kenya drought - Kenyan fresh produce was on sale in our supermarkets.

  • rate this

    Comment number 241.

    Unfortunately, many of the governments in Africa are unable or unwilling to help the villages in need of water. To access the ground water foreign aid will have to be responsible for constructing and maintaining the wells and pumps in these villages.

    Please consider helping out at places like water.org

  • rate this

    Comment number 240.

    Africa is underpopulated

    We have this good news of huge water resources and the first response is Africa bashing

    It seems people prefer to make up their own version of reality rather than
    look at the numbers

    Most people I talk to think that Africa is overpopulated and they think its
    a fact and few of them have ever looked at the statistics

    well educated and yet still oblivious

  • rate this

    Comment number 239.

    @Drunken Hobo

    We also forgot about the masses of people in the UK and the US who deem it appropriate to have as many kids as possible so the state will provide them with more welfare benefits, i know a few families like that and neither of them are religous in anyway.

  • rate this

    Comment number 238.

    This is great news as a result of the work by BGS. So how is Africa going to manage this resource, especially the ancient water in North Africa. Once its gone, its gone forever. I can envisage large scale irrigation, supporting crops and further population growth. There needs to be a serious long term plan to help make this water work for Africa.

  • rate this

    Comment number 237.

    What exactly will this 'solve'? It will lead to wars, for the easiest-to-extract aquifers. It will also remove a natural ceiling on population growth, in a region that is already out of control and frequently suffering from famine. For goodness sake, stop bringing children into a world which cannot sustain them. And sustenance means food, water, shelter, jobs AND freedom from war!

  • rate this

    Comment number 236.

    Oil, Gold, Diamond, Copper, Livestock, Fish, Cotton, Cacoa, Coffee...
    Rich Africa, Poor Africans and Monopolistic Companies......

  • rate this

    Comment number 235.

    185. haraboji,thanks for this confirmation of what I pointed out in my #177.But what you do not point out is that the water was found and first tapped by the efforts of a British oil exploration company.

  • rate this

    Comment number 234.

    many people and organisations have tried and failed to help Africans who really suffer due to the corrupt nature of the tiny minority in charge of the states in most need. They can have all the water reserves they need but until stable non-corrupt governments are in place the man on the street will not see the benefits of these discoveries - which is an absolute travesty of the highest order.

  • rate this

    Comment number 233.

    @ bdyke04
    "For those of you who keep looking down on Africa, its time will come"

    Suprising that your comment is the lowest ranked. Some do not want to see Africa progress? How disappointing. But you are correct. A lot of us Africans are gettn ready (with our PhDs & expertise).Your prediction will come true! We will make d world better for EVERYONE, we will NOT discriminate. Sceptics, watch us!

  • rate this

    Comment number 232.

    The problem is over population. What the masses cannot see is how exponential growth works. Take an empty discarded fizzy drinks bottle. A pair of bacteria divide and multiply in it by 2 every minute. They start at noon and by midnight the bottle is full of bacteria.
    What time is the bottle half empty? most say 6pm (tut tut), Answer - one minute to midnight. Relate this to our population, hmmmm

  • rate this

    Comment number 231.

    i think Gadaffi knew this already

  • rate this

    Comment number 230.

    @216.Drunken Hobo

    I know 7 billion people on a planet that is struggling to support it, i ahte to say it, but do you think the planet is trying to tell us somethng with all these natural disasters?

    Religion has given us 9/11 and very questionable ethic of catholic priests. Science has given us great discoveries and inventions, and at the same time tradgedies and horrors. 'mon the science

  • rate this

    Comment number 229.

    Here we go again with population
    Only 5% of arable land is irrigated
    So far this supports the current levels of population
    Imagine if 30% of arable land was irrigated
    wouldn't that likely extra food support double the african population?
    Population control is the most unimaginative and uninspired solution to sustainability
    It is intellectually lazy and shows a failure to apply basic math

  • rate this

    Comment number 228.

    I'm betting that this water will be quickly tapped, quickly used, then the problem will be worse than it is now. Ground water is very slow to replenish. This has been 'learned' in the farming history of Australia, but most people aren't aware of it.

  • rate this

    Comment number 227.

    216.Drunken Hobo
    I'm not religious but in a defence of Christianity, I'll say that alot of the overpopulation occurs in Muslim Africa. People in third world countries have lots of children because their children have a habit of dying young. This is a common theme in the history of any nation/region - Europe included.


Page 8 of 20


More Science & Environment stories



BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.