Hydrogeochemical characterization and groundwater quality assessment: a case study of the alluvial aquifer in the Middle Western Cheliff (Algeria)

The Middle Western Cheliff plain hosts an important alluvial aquifer that is exploited for various uses including drinking water supply, irrigation and industry. This study aims to provide a hydrogeochemical characterisation of groundwater by using statistical methods and binary diagrams, as well as to evaluate the physico-chemical quality of groundwater by using the water quality index (WQI). Moreover, parametric indices such as SAR and %Na were used to evaluate the suitability of groundwater for irrigation. The hydrochemical approach based on results of 45 analyses of groundwater samples for the dry period 2019 enabled the determination of the most dominant chemical facies, which was chloride, sulphate, calcic and magnesium. The binary diagrams used indicated that the water-rock interaction and the evaporitic phenomenon are major geochemical processes that control the mineralisation of groundwater. The evaluation of groundwater quality for drinking water supply using WQI provided results with values ranging from 45.95 to 194.78, and above 60% of samples were classified into the category of excellent to good quality (WQI < 100), while the remaining 40% of water samples were classified in the category of poor quality for drinking (WQI > 100). However, the quality of groundwater is mostly acceptable for irrigation, mostly for plants with salinity-tolerant in drained soils.