Geochemistry and Water Quality Assessment of Continental Intercalary Aquifer in Ouargla Region (Sahara, Algeria)

Abstract

Groundwater is vital for all living beings and the socio-economic development of arid regions. The present study evaluated the pertinence of groundwater of the continental intercalary (CI) aquifer in the Ouargla region for domestic and agricultural purposes. Sixteen (16) water samples were collected and analyzed for physical parameters, major cations and anions. The appreciation of groundwater potability was compared with the WHO (2017) standards. Agricultural water quality was evaluated using the Irrigation Water Quality Index (IWQI) method and the study of irrigation parameters: EC, SAR, SSP, PI, KR, PS and MAR. The results show that the CI waters are dominated by mixed Ca-Mg-Cl type (56.3%) and Ca-Cl type (43.7%). Natural rock-water interactions, including silicate weathering, evaporite dissolution and cation exchange, were the dominant processes controlling the mineralization of CI waters. According to WHO (2017), EC (100%), T (100%), TDS (100%), Na+ (87.5%), K+ (100%), Ca2+ (12.5%), Mg2+ (18.75%), SO42- (100%), and TH (100%), samples exceed the permissible limit, indicating that most of the groundwater samples do not have good quality for drinking purposes. The calculated IWQI showed that 31.25% of the water samples were in the good category and 68.75% in the doubtful category.