Nubian Sandstone Aquifer System

Fossil water aquifer system in northeastern Africa

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 northeastern Africa. The NSAS covers a land area spanning just over two million km2, including northwestern Sudan, northeastern Chad, southeastern Libya, and most of Egypt.

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