Hydrogeochemical characterization and appraisal of groundwater suitability for drinking purposes using water quality index (WQI) in Aksum town and surrounding areas, Tigray, Ethiopia

ABSTRACT The study area, located in central Tigray, Ethiopia, covers 234.5 km2 and primarily relies on groundwater as its main water source. As water quality concerns grow, detailed studies on groundwater hydrogeochemistry and its suitability for consumption remain insufficient. This study investigates groundwater hydrogeochemistry and evaluates its quality for drinking purposes. In May 2020, 19 water samples were collected from various locations and analyzed for physicochemical parameters, to gain insights into groundwater quality and its influencing factors. Hydrogeochemical classification utilized ionic ratios, Piper and Schoeller diagrams, statistical methods, and water quality assessment via the water quality index (WQI). The findings revealed Ca2+ > Mg2+ > Na+ + K+ and HCO3− > SO42− > Cl− as predominant ions, with Ca–Mg–SO4–HCO3 dominating. Gibbs diagrams and scatter plots revealed water–rock interaction and silicate dissolution as key hydrogeochemical factors, supplemented by ion exchange processes and human activities. Total dissolved solid and electrical conductivity exhibited a strong correlation and were moderately correlated with the major ions. The WQI ranged from 25.6 to 215.94, averaging 69.09, classifying groundwater as excellent (15.8%), good (78.9%), and very poor (5.3%) for drinking use. These insights provide valuable input to maintain the optimal use of groundwater resources in the area.