Potentialités en eau des Grès Numidiens dans le Nord Sétifien

Abstract

The demand for water in semi-arid areas is increasing, with climate change, the amount of surface water is insufficient, hence the need to find solutions by exploiting underground sources. The study area is part of the Sétifian Highlands, a semi-arid region that has been experiencing water shortages in recent years. The underground aquifers in the Sétif region are mainly Jurassic limestones in the North, Cretaceous limestones in the south and Mio-Plio-Quaternary aquifers in the plains. These aquifers have variability in terms of quantity (limited for Moi-Plio-Quaternary layers) and quality (high hardness for other limestone layers). In this context the Numidians aquifer forms an alternative to meet the water needs in this region. In this work, field data, petrographic and hydrochemical analyzes were used to evaluate the water potential of the Numidian sandstones north of Setif. Two sandstone outcrops were chosen, one in the northeast in the Beni Aziz region and the other in the sandstone massif of Jebel Megriss not far from the town of Setif. The results show that the sources are abundant in the two regions with variable flow rates but which continuous flow. These sources feed the wadis of the region , then used by the villagers for the supply of drinking water and for agriculture. Hydrochemistry has shown that these waters are of very good quality and they meet the standards of potability. The petrographic analysis has shown that the sandstones present two types of porosity, one of crack and the other of interstices, the latter decreases going towards the depth until the porosity becomes very weak in contact with the Under-Numidian clays.