Effectiveness of hydrogeochemistry in determining groundwater quality in Ghardaïa (Algeria)

Groundwater is a strategic resource in Ghardaïa Province, northern Algerian Sahara, where arid conditions and increasing demand may accelerate mineralization and quality deterioration. This study evaluates groundwater quality using an integrated hydrochemical, spatial, statistical and index-based approach. Seventy-one groundwater wells were analyzed for pH, electrical conductivity (EC), major ions, total hardness and turbidity. The methodology combined normalized inorganic charge balance, inverse distance weighting, Piper and Schoeller-Berkaloff diagrams, Pearson correlation, principal component analysis, hierarchical cluster analysis and groundwater quality index (GWQI). Results reveal pronounced spatial hydrochemical heterogeneity, with elevated sulfate, chloride, sodium, calcium, magnesium and hardness mainly in central, western and south-central areas. Ca-Mg-Na-Cl-SO4, Na-Cl and Na-SO4 facies indicate mineral dissolution, evaporitic influence, evaporation and water-rock interaction, with possible anthropogenic inputs. GWQI indicates predominantly poor quality for irrigation and drinking, emphasizing targeted monitoring, treatment or blending and salinity-management practices for sustainable groundwater management.