LARHYSS Journal
Volume 19, Numéro 2, Pages 33-55
2022-06-20

Overview Of The Hydrogeology Of A Fractured Bedrock Aquifer. Chain Of Ougarta The Saoura - South-west Algeria

Authors : Merzougui Touhami .

Abstract

The Mount of' Ougarta, located in the south-west of Algeria, corresponds to an imposing geological entity which corresponds to the center of interest of the geology of the Saharan platform. In the northwestern part of the Algerian Sahara, between the coordinates: 0 ° 30 '- 5 ° 00' of the longitudes west and 28 ° 30 '- 31 ° 00' of the latitudes north, are situated the mounts of Ougarta. It is a vast zone of elongated reliefs NW - SE, over an area of 400 x 200km².The Ougarta Mounts are bordered to the north by Hamada du Guir and the Kem Kem Plateau, to the south by Hamada of Chammar and Touat, to the East by the great Western Erg and to the West by Hamada of the Draâ, ergs Iguidi and Chech. Its reliefs are carved by different erosion phases from the Permian to the Upper Jurassic. These Paleozoic soils are in the form of a succession of wide, synclinal, narrow, anticlinal folds elongated in the NW-SE direction, and are affected by fault systems; N140 °, N050 ° and N070 ° and N100 °. At the limits of this entity, the hydrographic network, dry in most of the time, is well taken in the landscape. This region contains Groundwaters that are little studied, indicating the existence of different catchments at the villages of Zéghamra, Ougarta, Tabelbala, Bou M'Haoued and Sebkha el Melah (sources, wells, boreholes). Taking into account the distinct lithologies of the Paleozoic (clay sandstones, black shales, limestones), it seems that the Cambro-Ordovician sandstones and quartzite represent the largest aquifer in the region of Ougarta, forming a multilayer system, the detail of which still to be found. These are fossil groundwater, fed during wet quaternary periods, as evidenced by Conrad's isotopic measurements, 1974. The present work aims to provide a structural and a hydrogeological overview of the Paleozoic terrains of the Ougarta Mounts. Groundwater quality in the Ougarta region is, in general, low mineralized, predominantly chlorinated; they are quickly loaded with sulphates on the boundaries of the free surface area.

Keywords

Aquifer, hydrogeology, structure, Ougarta, Cracked Socle, Paleozoic, Saoura.