Physicochemical and isotopical characterization of groundwater in the basin of Guelma, North-East of Algeria

Water quality is an important criterion for evaluating the suitability of water for drinking and domestic purpose. The main objective of this study was to investigate the physicochemical characterization of groundwater for drinking water consumption. Ten captured sources were selected from three aquifers including the Guelma Mio-Plio-Quaternary alluvial basin; the Senonian Heliopolis Neritic limestone aquifer, and the Eocene limestones of Ras El Agba-Sellaoua aquifer. The analyses concerned the periods of high water in May 2017 and low water in August 2017. Twelve parameters were determined for the water samples: pH, T (°C), EC, Ca2+, Mg2+, Na+, K+, Cl−, HCO3−, SO42−, NO3−, TH (hydrotimetric degree), TAT (total alkalinity titration). The interpretation of the various analytical results allowed the determination of the chemical facies and the classification of the groundwater aquifers as follows: (i) in the alluvial layer, the gypsiferous marl substratum and the clays of the three terraces (high, medium and low) have given the water a chlorinated calcium chemical facies in the east part of the study area and travertines feeding partly alluvial layer, and have given a bicarbonated calcium water facies in the west, (ii) in the Senonian of Heliopolis limestone and Eocene carbonate formations of Ras El Agba-Sellaoua, the chemical facies are calcium bicarbonate. Water isotopes (δ18O and δD) helped to determine the origin of groundwater. Overall, the groundwater in the area is hard and has significant to excessive mineralization. It is progressively degraded in the direction of flow, especially in the Guelma alluvial aquifer.