Origin and Age of the surface water and groundwater of the Ouargla basin-Algeria

The chemical and isotopic data of groundwater and surface water of the Ouargla basin have been examined the relation and the spatial models that could be useful to determine the vertical and genetic relation between the mass water, recharge zones, directions of groundwater flow and geochemical processes. The surface distributions of water types and some chemical and isotopic data are discussed in this paper, as are the apparent relationships between constituents. The hydrogeological and geochemical implications and characteristics of the observed data are presented as well. The saturation indices for the selected minerals discussed below were calculated using the PHREEQC geochemical package (Parkhurst, 1995) [1]. The objective of this work is to apply isotopic and hydro-chemical techniques to determine the chemical features of the water and the state of saturation, the origin, the ages and the mechanisms of supply of surface water and recharge of deep aquifers in the region of Ouargla. The basin of Ouargla is located in the North-East of the Algerian Sahara, presents an area of 95 000 ha; characterized by a very arid climate. Hydrochemically, water quality is very degraded, the chemical features are almost homogeneous. The 180 and 2H contents of groundwater are highly enriched and show a highly evaporated character on the majority of the surface water and are thus distinguished from the waters of two deep aquifers. On the surface a mixture between the different tanks has been demonstrated by the isotopes (180 and 2H). The 14C and 3H activities of the surface water at the basin scale show quite variable activities confirm the existence of several recharging episodes over time and validate the mixture evidenced by stable isotopes. For the terminal complex 14C activities are very low and show a decrease in the direction of flow. (C) 2019 The Authors. Published by Elsevier Ltd.