Water Quality in an Arid Weather Area, Case: Ground Water of Terminal Complex Algerian Southeast

Abstract

The region of Oued-Souf (SE Algeria) is characterized by the superposition of three aquifer layers, from top to bottom: the surface aquifer, the terminal complex aquifer (CT), and the intercalary continental aquifer (CI).

The terminal complex aquifer is the main source for drinking water supply and agricultural uses. The study of the chemical quality of these waters shows that they are non-potable, highly mineralized, and have major elements (sodium, magnesium, sulfate, chloride, and calcium) exceeding the standards recommended by the WHO and the Algerian standards for drinking water, so this is an obstacle to their use.

To highlight the origins of this mineralization, we used the hydro chemical tool. Thus, the chemical analyses in our possession were processed using the software «Statistica, which allowed us to carry out a principal component analysis (PCA). The latter showed a competition between sodium or magnesium chlorinated water and calcium bicarbonate water, rich in potassium. The thermodynamic simulation carried out showed a variation of the saturation indices, which do not exceed zero, for the waters of the CT complexes, thus indicating a sub-saturation of the waters with respect to the minerals. The mineralization starts with the breakdown of evaporates (gypsum and halite) and the exchange of bases. This shows how the outcrop formations affect the water quality.

The waters of the CT terminal complex aquifer are of poor quality for irrigation because their representation on the Richards diagram shows that they are arranged according to two classes, C4S2 and C4S3, and must be treated (dematerialized) before they are distributed to consumers.