Under Africa there is water to irrigate the entire continent

  • 2012

Matt McGrath, Apr 20 (BBC) .- Appearances are deceiving. We usually think that Africa is by nature dry. But only on the surface: according to scientists, the total volume of water in underground aquifers throughout the continent is 100 times the amount found on the surface. A team of researchers developed the most detailed map that has been made of the scale and potential of these hidden resources.

The study was published in the journal Environmental Research Letters and emphasizes that large-scale drilling may not be the best way to increase water supplies. Solution for people and agriculture It is estimated that in all of Africa more than 300 million people do not have access to drinking water. The demand for water is destined to grow considerably in the coming decades due to population growth and the need for irrigation for crops. Freshwater rivers and lakes are subject to seasonal floods and droughts that may limit their availability for people and agriculture.

Currently, only 5% of the arable land is irrigated. Now the scientists carried out, for the first time, an analysis of the water that is hidden in the aquifers beneath the surface of the entire continent. Researchers from the British Geological Survey (BGS) and University College London (UCL) mapped in detail the amount and potential yield of this groundwater resource across the continent. Helen Bonsor, of the BGS and one of the authors of the work, says that so far the groundwater has been lost sight of. She hopes that these new maps will open the door to new alternatives. "Where there is more underground water storage is in northern Africa, in the large sedimentary basins of Libya, Algeria and Chad, " he said. The amount of storage in those basins is equivalent to a thickness of 75 meters of water, which is a huge amount. more than 5, 000 years ago. And its conservation has to do with the solidity of an area as vast as the one that, over the centuries, has developed in the Sahara desert.

The scientists collected information from current hydrogeological maps of national governments, as well as from 283 studies of aquifers. And they say that the maps they developed with it indicate that several countries currently referred to as "water scarce" have a substantial reserve of groundwater. The drilling dilemma However, scientists are cautious about the best way to access these hidden resources. They suggest that diffusion drilling of large wells may not work. Alan MacDonald, lead author of the study, told the BBC: “A deep drilling of the wells should not be done without a knowledge of the local groundwater conditions. "It is likely that surface drilling holes in places suitable for rural water supply and hand pumps will succeed." With not many aquifers full due to lack of rain, scientists are worried that large well drilling could deplete the resource quickly.

According to Helen Bonsor, sometimes the slowest means of extraction may be the most efficient. "In much of sub-Saharan Africa there are deep storage aquifers, " he said, "but our work shows that, with careful exploration and construction, there is enough groundwater in Africa to focus on surface drilling and thereby meet the demand."

Scientists say there are enough reserves to cope with the vagaries of climate change. "Even in low-storage aquifers in semi-arid areas where it rains very little today, water has a soil retention time of 20 to 70 years." Dr. Bonsor said. “So at the current rate of extraction, groundwater provides and will continue to provide a mattress for climate variability for consumption and for small-scale irrigation.” Rsos_hidricos.shtml

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