The water quality index and hydrochemical characterization of groundwater resources in Hafar Albatin, Saudi Arabia

The main objectives of this study were to: evaluate and compare the treated and untreated groundwater quality in Hafar Albatin, Saudi Arabia for drinking purpose using water quality index (WQI), study the suitability of untreated groundwater for irrigation purpose, and investigate hydrochemical processes that control the groundwater chemistry. The WQI calculations required several physiochemical water parameters including EC, pH, Ca2+, Mg2+, Na+, K+, Cl−, SO42−, and NO3−. The results showed that more than 47 % of the untreated wells considered unsuitable (class V), 39 % considered very poor water (class IV), and 14 % considered poor water (class III) for drinking purposes. The treatment of groundwater improved its quality to poor (class III) and even good (class II). Approximately 64 % of all treated waters were of good quality; however, the rest remained poor. Most studied untreated groundwaters were considered unsuitable for irrigation due to salinity hazards; however, no sodicity hazards were anticipated. US salinity laboratory diagram revealed that the groundwater samples were grouped into five categories; 53.6 % of water samples were distributed in category C4–S2 highlighting very high salinity hazards and medium sodium hazards class. Durov and Piper diagrams revealed that the majority of investigated waters were sodium chloride and calcium sulfate–chloride water type. The Gibbs’s diagram revealed that the chemical weathering of rock-forming minerals and evaporation are influencing the groundwater quality. The hydrochemical modeling indicated that all water samples were undersaturated for halite and 89 % of water samples were saturated for anhydrite and gypsum.