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Water from the Sahara

Dr Alan MacDonald talks about North Africa's groundwater reserves

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Aquifers below the Sahara may hold plenty of water but accessing reserves is not easy. (GETTY IMAGES)
Aquifers below the Sahara may hold plenty of water but accessing reserves is not easy. (GETTY IMAGES)

Groundwater is an issue that has been in the news a good deal here in the Middle East, and that’s largely because there isn’t a great deal left of it. The UAE earlier this year announced that the export of groundwater would be banned following grave concerns that freshwater reserves would be depleted within five years. With sky-high per capita water consumption – Abu Dhabi’s figure is 550 litres of water per day, per person, compared to a world average of around 190 litres – there is perhaps little wonder that fears of bone dry aquifers led to such a decision. With such a shortage in the wider region, a report that shows that the volume of North African reserves is extensive has caught attention around the world.

Researchers from the British Geological Survey and University College London have produced the first quantitative maps of the African continent’s aquifer storage and potential borehole yields. This research has shown that the groundwater volume across Africa is 0.66 million km3 - an estimated 100 times that of the estimated renewable freshwater sources. More significant still for those with a particular MENA interest, the research has shown that North African countries hold by far the largest groundwater volumes.

Dr Alan MacDonald, principal hydrogeologist at the British Geological Survey and one of the report’s authors, explains the findings. “The groundwater held in the North African sedimentary basins is amongst the largest groundwater resource in the world. Our estimates for the basins are similar to previous estimates from individual studies – and in North Africa these aquifers have been studied for decades – but the information is rarely known about outside of the scientific community.”

The information in question relates particularly to Libya, Algeria, Egypt and Sudan, where the largest groundwater estimates have been made. The report shows Algeria has a best-estimate of 91,900 km3 of groundwater storage, Libya 99,500 km3, whilst Egypt is estimated to hold 55,200 km3. Moreover the report suggests that the majority of sedimentary stores that can accommodate high yielding boreholes are also in the North African countries.

Accessing the resources is less straightforward however, with significant reserves often far from population centres and too deep to make abstraction simple.

“The man-made river project in Libya is the best example of the water being used. This abstracts large volumes of groundwater and pipes it to the coast. However, it is very expensive to develop these water resources. Water levels are often deep – 200 metres or more – so very deep boreholes need to be drilled which is highly expensive. The water is also not in the places where most people need it so the water will require pumping over great distances. In many cases it may be more cost effective to leave the water in the ground.”

If access is a problem, the question of sustainability is also an issue. Saharan aquifers in particular, perhaps not unexpectedly, do not get regular recharges.

“The sustainability aspect is important. The Saharan aquifers were recharged between 5 and 10,000 years ago, and they are not currently recharged. As a result, any abstraction of the water will deplete this fossil reserve. Before considering abstraction, careful and detailed studies would be required to find out how long the water would last, and what the side effects would be, to protect the investment, other users and future generations.”

A theme that seems quickly apparent then is that simply having groundwater resources – even extensive groundwater resources – does not spell an end to water shortage issues. There is a constant need to ensure that available resources are used sustainably and applied with local requirements in mind.

Dr Macdonald concludes “There are high costs associated with developing these water resources. I would suggest always looking first to develop local groundwater resources that you know are currently recharged and are close to the point of need.”
 

 

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