Hydrogeochemical processes, water–rock interactions, and the suitability of groundwater in a semi-arid region, Northeastern Algeria
Nadia Benmerabet, Nassima Sedrati, Larbi Djabri
Abstract
ABSTRACT Understanding groundwater geochemical evolution is crucial for sustainable water management, particularly in Algeria's semi-arid regions, where water scarcity is a major challenge. Sixty-five groundwater samples were collected and analyzed in March 2021 from the study area to identify hydrogeochemical processes, water–rock interactions, and groundwater suitability for drinking and irrigation. Results indicate significant variations in mineralization, with over 90% of samples highly mineralized, reaching 31,700 µS/cm. The abundance of major ions was Na2+ > Ca2+ > Mg2+ > K+ for cations and Cl− > HCO3− > SO42− > NO32− for anions. Most samples are classified as very hard-brackish or hard-brackish, with Ca-Mg-Cl-SO4, Na-Cl, and Ca-Mg-HCO3 as the main water types. The increase in salinity is primarily due to geogenic processes, with some anthropogenic influence. Water–rock interactions and evaporation are the key factors controlling groundwater chemistry, with the dissolution of halite, gypsum, anhydrite, calcite, and dolomite playing a major role. Additionally, cation exchange and silicate weathering are prevalent processes in the groundwater system. Saturation index analysis reveals that anhydrite, gypsum, and halite are unsaturated, whereas aragonite, dolomite, and calcite are saturated. Regarding usability, over 73% of groundwater samples require treatment before drinking, while more than 80% are suitable for irrigation.