Application of Water Quality Index to Assess the Potability of the Phreatic Aquifer in Ouargla (Algeria)

Abstract

Groundwater is essential for sustainable development and drinking water supply in the Saharan regions. This work aims to assess the quality of water for domestic use and the hydrogeochemical characteristics of the phreatic aquifer of the Ouargla. Forty-two (42) wells capturing the phreatic aquifer are sampled and analyzed. The parameters analyzed are pH, EC, TDS, cations and anions. The water’s potability was evaluated using the Water Quality Index (WQI) method, using the main physicochemical parameters that have potential adverse effects on human health. The results obtained show three classes: the poor class (14.29%), the very poor class (19.04%), and the non-potable class (66.67%). The analysis of the Piper and the Gibbs diagrams, the Pearson correlation matrix and the diagrams of relationship between the major elements, as well as the indices of saturation of the main minerals, shows that the groundwater samples were arranged into two groups; Ca-Mg-SO4-Cl (38.5%) and Na-Cl (61.5%), the geochemical processes occurring in the aquifer mainly include the dissolution of halite, gypsum, the cation exchange between water and clay minerals and anthropogenic inputs.