Timgad Basin is a part of the North-East Algerian Saharan Atlas. It is located at the northern of the Aurès Mountain. It is bordered in the North by Bou Arif, Amrane and Tagratine mountains, while in the South it is limited by Chelia, Rdam and Nerdi Bouhmar mountains. It is shaped as a synclinal gutter oriented East-West and covers an area of about 1000 Km2 . The climate is semi-arid (cold winter and hot summer) with average annual rainfall not exceeding 350 mm. The basin is composed by varied lithology, showing large folded structures down sloping towards the center, which favor groundwater storage. The Miocene sandstone aquifer is the most important. It is characterized by a wavy shape, which form series of shale-marl filling depressions. Recent wells drilled in the basin edges and center, put in evidence its artesian character. The piezometric survey shows a groundwater convergent flow oriented towards the basin east (Bou el Freis), likewise the sandstone aquifer is marked by the presence of a West-East drainage axis which separates the basin northern part characterized by a low reservoirs hydraulic capacity from the southern part distinguished by the groundwater relative abundance.