Geochemical study of groundwater in the Oued El Hatiba Basin, pre-Saharan Atlas, eastern Algeria

ABSTRACT The Oued El Hatiba basin, located at the eastern boundary of the Aures massif, constitutes the main massif of the pre-Saharan Atlas in eastern Algeria. Geologically, the basin features a succession of marls at the base, overlain by Cretaceous limestones, covered by Plio-Quaternary sediments composed of alluvium and sand. The Babar Dam is situated in this basin, draining an area of 567 km2 along the Larab wadi. It is intended for irrigation of surrounding lands and the supply of potable water to neighboring communities. The analysis of major element concentrations from various sampled water points reveals that the waters exhibit dominant facies: chloride-calcium (48.88%), sulfate-calcium (24.44%), bicarbonate-calcium (15.55%), magnesium bicarbonate (08.88%), and magnesium chloride (02.22%). These chemical facies are determined by the aridity of the climate, water-rock interaction, dissolution, and mineral precipitation, mediated by cationic exchanges throughout the water flow towards its outlet. Calculation of mineral saturation indices in the water indicates that only carbonate minerals tend to precipitate, notably as calcite and dolomite, while evaporitic minerals (gypsum and halite) tend towards dissolution. A principal component analysis (PCA) was conducted on a data table consisting of eight (08) variables and 50 individuals. The analysis was extended to two factors, explaining 75.38% of the variance.