'Huge' water resource exists under Africa

 

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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."

 

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  • rate this
    0

    Comment number 386.

    This is not a "discovery".Only a better map of what has been known for thousands of years.What we now do with it is crucial for the wellbeing of Africans. The "west" should supply expertise and engineering philanthropically to liberate the nations of this VAST continent so that the peace and prosperity is THEIRS NOT OURS! In the long run the stability of Africa will be to the benefit of all.

  • rate this
    0

    Comment number 385.

    Return the Hydrologic cycle to Africa agreed, but extracting the ground water is not the answer. Unless the entire cycle can be made it will prove worthless. Supplement with coastal desalination plants to irrigate land, return vegetation to arid parts to stop the advancing deserts, this needs billions of litres of water. Why argue that ground water is 100 times that of surface, it's a known fact.

  • rate this
    0

    Comment number 384.

    In the space of 200yrs, every 20,000 years Sahara goes from desert to grass land with lakes & rivers, due to the Earth tilting & the monsoon belt shifting. re Nat. Geographic......
    Climate change nothing to do with C02 by the way.
    Hope they use the water wisely not just to boost population & more hungry mouths.

  • rate this
    +1

    Comment number 383.

    "This is great news"? - What narrative within this development discourse will this turn into? Will there now be a surge of fleeting NGO's wanting to tap into this resource or monopolized by state intervention? Either way these are the best 'models' for utilizing this new resource, but it's important that the focus is on the agency of those who require it, rather than the structure of governance.

  • rate this
    0

    Comment number 382.

  • rate this
    0

    Comment number 381.

    @322

    Agreed, using aquifers that take hundreds or thousands of years to refill, for major development would be extremely foolish.. unsustainable use of aquifers is a significant problem, not just in Africa but elsewhere as well -
    http://www.eea.europa.eu/themes/water/water-resources/impacts-due-to-over-abstraction
    .. such resources should be carefully monitored and parsimoniously managed

  • rate this
    0

    Comment number 380.

    #369.United Dreamer

    #313. dedcef01

    it's great they found this resource, but the real problem to be addressed is too many people for the water!"

    If that's actually true how come there isn't masses of people dying of thirst?

    You use much more water growing crops than you actually drink. Among subsistence farmers water shortage tends to show as famine, as crops fail.

  • rate this
    +1

    Comment number 379.

    Africa is surrounded by water, they need water treatment plants that turn sea water into drinkable water . Hand outs is not what they need ,they need investment. If we keep having childrens in need day every year n ads on tv decade after decade then obviously just giving money isn't working.

    I welcome the day when childrens in need is stopped and instead have an investment day.Knowledge is key.

  • rate this
    +1

    Comment number 378.

    @305 - they exclude the following which have higher pop densities than England:

    Monaco
    Gibraltar
    Malta
    The Vatican State
    Jersey
    Guernsey
    San Marino

    Flanders and Wallonia are separate entities under Belgian law, and Flanders also has a higher population density than England.

  • rate this
    -1

    Comment number 377.

    It is time that the people of Africa stopped placating to the west and deal with this great news in a positive african manner. There is no need to follow in the western philosophy of we'll worry about tomorrow, tomorrow, but Intellectually figure out a green and viable way to access the water that suits Africa needs. Some posts are down right rude towards Africans!

  • rate this
    +2

    Comment number 376.

    374. Tsunami
    You're too funny - troll-tastic!

  • rate this
    0

    Comment number 375.

    And how many weapons wil this resource buy?

  • rate this
    -1

    Comment number 374.

    I couldn't give two hoots about africa but this is a great opportunity for British companies to make some money. Engineering firms could make a kiling as could logistics companies etc etc. Not to mention the finance opportunities for banks.

    That is what is really important here & let's hope UK companies are not slow to react.

  • rate this
    0

    Comment number 373.

    "up until now groundwater was out of sight and out of mind"

    Really ?? That's what we have been using in my house in south-west Nigeria, For any homes were there is no connection to the water corporation, you either drill a borehole or you dig a well. It's nothing new.

    The map may be a new thing though.

    The question it raises is " what will we fall back on after its depletion ?"

  • rate this
    0

    Comment number 372.

    By calling it "Huge", I hope, that Africa does not exploit and waste this valuable natural resource. It needs to be developed and managed properly to guarantee it's long-term sustainability. These aquifers have taken more than 5,000 years to recharge and wasteful practices in excess of their recharge rates could damage the precious resource.

  • rate this
    -1

    Comment number 371.

    Who remembers the never ending charity appeals to help Africa obtain water?And the number of years the TV Adverts have run?
    Who really thinks the problem will be solved?
    Donations will be needed for years to come.
    Unless ...maybe?....
    There is a profit in this discovery..for someone.

  • rate this
    0

    Comment number 370.

    This Water is not renewable-like"endangerredlogic"points out-it should be left alone,maybe only in times of drought a well Controlled,Limited use.
    Not let Private Corporates get their Hands on it,they only intressted in Fast Money

  • rate this
    0

    Comment number 369.

    "313. dedcef01

    it's great they found this resource, but the real problem to be addressed is too many people for the water!"

    If that's actually true how come there isn't masses of people dying of thirst?

  • rate this
    0

    Comment number 368.

    331.Tsunami of Logic
    2 Hours ago

    The world could comfortably sustain a population double it's current size if all available land is farmed intensively.


    +++
    Before or after subtracting an aea of land equal to the area used for housing the present population?

  • Comment number 367.

    This comment was removed because the moderators found it broke the house rules. Explain.

 

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