Understanding the factors controlling groundwater mineralization is essential for the sustainable management of water resources in semi-arid environments. This study investigates the hydrogeochemical functioning of the Chemora Plain aquifer (Northeastern Algeria), where a central structural relief divides the plain into two hydrogeological compartments. Groundwater samples were analyzed using conventional hydrochemistry, mineral saturation indices, stable isotopes (δ¹⁸O and δ²H), and principal component analysis (PCA). Electrical conductivity, water hardness, and major ion distributions reveal contrasting hydrochemical evolution between the southern recharge zone and the northern discharge zone affected by evaporation and longer groundwater residence times. Saturation indices indicate near-equilibrium conditions with carbonate minerals (calcite and dolomite) and persistent undersaturation with respect to gypsum, anhydrite, and halite, suggesting continuous evaporite dissolution rather than precipitation. Stable isotope compositions confirm the meteoric origin of groundwater and indicate limited evaporation in the southern sector compared with stronger evaporative enrichment in the northern compartment. PCA further highlights distinct hydrochemical signatures while revealing partial hydraulic communication across the structural discontinuity. These findings demonstrate that tectonic compartmentalization exerts a major control on groundwater circulation, mineralization, and recharge processes in the Chemora aquifer, providing useful information for groundwater management in semi-arid regions.