Assessment of Groundwater Quality for Drinking Purposes Using a Water Quality Index (WQI) and Multivariate Statistical Analysis: A Case Study in Seriana Region, Batna Province, Algeria

Groundwater is widely regarded as a safe and reliable drinking water source in many regions of Africa. However, human pressures have led to its quality deterioration and degradation. This study evaluates groundwater suitability for human consumption in a semi-arid region using a Water Quality Index (WQI) and applies multivariate statistical analysis to identify key hydrogeochemical processes. The area of interest is the Seriana region (Batna Province, Algeria), an inner alluvial plain, constituted of Quaternary aeolian-alluvial deposits. The plain is surrounded by Cretaceous and Jurassic limestones and dolostones of the Saharan Atlas. Sabkhas and salty deposits are widely present in the plain. Water samples were collected from twelve wells in June 2019, and their physicochemical parameters were analysed. The measured parameters are generally below the threshold values set by the World Health Organization for drinking water quality. Exceptions are observed for Ca2+, Mg2+, Na+, K+, HCO3–, Cl–, SO42–. These parameters exceed the thresholds in 10, 12, 1, 1, 9, 3, and 1 sample(s), respectively. Three hydrochemical facies are identified: mixed cations, Mg-HCO3 and Na-Cl. Samples are classified into three water quality classes based on WQI: good (5/12), poor (6/12) and very poor (1/12) quality. Rock-water interaction, mainly dominated by Mg2+ and SO42– and secondarily by Ca2+ and HCO3–, and evaporation processes or evaporites dissolution, dominated by Na+ and Cl–, are the main hydrogeochemical processes. Nitrates affect groundwater quality, despite concentrations below the drinking-water guideline value. In conclusion, over half of the groundwater in the region is of poor quality and unfit for human consumption without treatment, presenting potential health hazards. We recommend treating groundwater at the household or community reservoir level before distribution, alongside organising public health awareness campaigns to promote the use of proper sanitation technologies.