The Nubian Sandstone Aquifer System (NSAS) is the world’s largest known fossil water aquifer system. It is located underground in the Eastern end of the Sahara Desert and spans the political boundaries of four countries in north-eastern Africa. The aquifer is largely composed of hard ferruginous sandstone with great shale and clay intercalation, having a thickness that ranges between 140-230 meters. The groundwater is of meteoric origin (the term meteoric water refers to water that originated as precipitation; most groundwater is meteoric in origin). Many groundwater aquifers and surface bodies of water traverse borders and boundaries without regard to politics, those that don’t are frequently interrelated with the larger regional hydrologic system and are thus interconnected to surface or groundwater in neighboring states.

 

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