Deep groundwater in the Sahara

Northern aquifer system is charging?

An article of  Liberte-Algerie   by Rabah Said dated April 28, 2016 elaborated on the Sahara underground water lakes.  Until recently, these Deep groundwater in the Sahara were considered strictly fossil, meaning non renewable. Yet, according to a study by the ‘Institut de Recherche pour le Développement’ (IRD-France)   published in Geophysical Research letters, the groundwater of the Northern Sahara aquifer system are renewed.

Rainfall being rare and evapo-transpiration too much to significantly fill deep groundwater.  The IRD-France researchers assert that “in reality, the tablecloths of the aquifer system of the Northern Sahara, their exact name, are still supplied.  Their fill charging exists and could be quantified: rain precipitation and water runoffs bring in to the system an average of 1.4 km³ per year, or about 2 mm per year on the surface to recharge.  “Over the period from 2003 to 2010, the annual recharge even reached 4.4 km³ in some years, equivalent to 6.5 mm per year”.

The scientists analysed the data provided by the satellite mission GRACE (Gravity Recovery and Climate Experiment) of NASA and the German Aerospace Center.  These data have allowed researchers to estimate the evolution of the volume of stored water and to deduce the aquifer recharge, once withdrawals in groundwater are taken into account.  The average recharge of 1.4 km³ per year is 40%, 2.75 km³ in total collected each year, according to data from the Observatory of Sahara and Sahel (OSS).  In fact 60% of annual withdrawals are not offset. Therefore there is over-exploitation, but it can be managed with fewer constraints.

This article originally in French titled The blue gold of the desert .  It is a vivid description of the water hidden in the desert…

Aquifers in Northern Sahara
Aquifers in Northern Sahara

A scientific magazine reading and ‘voila!’ that I came across a fascinating map, there is of water buried in the desert, a true inland sea… A treasure which is buried and which sleep under our feet since millions of years…

The richness of a civilization will soon be measured in litres.  We hear that the lack of water will be the cause of wars in the not very distant future and that the possession of this resource will be a priceless trophy for some time…

It should be remembered that, on the 1.4 billion cubic kilometers * water found on the planet, only 2.5% is fresh water, and that the rest can be made potable at the cost of operations of desalination extremely costly and complex that very few Governments can afford. The amount of water in the world doubles every 20 years but there are many factors that lead us to ask ourselves whether it will be enough to quench the thirst of all humans: population growth, unthinking use of the resource in agriculture, uncontrolled exploitation of water courses, etc. According to the statistics that 85% of the water consumed are used by 12% of the population. (*: Knowing that one cubic kilometer equals one billion litres of water)

 

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