"You never miss the water till the well runs dry" is an old idiom that is becoming a harsh reality for the Middle East and North Africa region and globally. Water scarcity is now this century's imminent greatest problem, a clear and present danger. This is no surprise considering 85 percent of the world’s population lives in the driest half of the planet. The United Nations estimates that, already, 6 to 8 million people die annually from the consequences of disasters and water-related diseases, with a child dying from a water-related illness every 21 seconds.

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.

[MARSEILLES] Hydropower could supply all of Africa's electricity needs if cross-border cooperation was stepped up, according to a UN report launched last week (12 March) at the World Water Forum in Marseilles, France.