The article analyses the water quality of the Lower Cretaceous aquifer in the Beni-Ounif syncline. To this end, 42 samples were taken for physico-chemical analysis and 28 for microbiological analysis in March, May and October 2017 from 14 sampling points. The results of physico-chemical analysis were processed by multi-variety statistical analysis methods: principal component analysis (PCA) and hierarchical cluster analysis (HCA) coupled to hydro chemical methods: Piper diagram.
The PCA allowed us to explore the connections between physico-chemical parameters and similarities between samples and to identify the most appropriate physico-chemical elements to describe water quality.
The HCA allowed us to classify the sampling points according to the similarity between them and thus reduce them for the next follow-up analysis.
Waters of the syncline are characterized by medium to low mineralization (320 < EC < 7600 μS∙cm–1 and 200 < RS < 4020 mg∙dm−3) and hardness of between 22 and 123°f. Only 19% of the samples show NO3 concentrations exceeding the Algerian standards.
Microbiologically, the study reports the presence of bacteria: coliforms (<8 CFU∙0.1 dm−3), Streptococcus D (<1100 CFUꞏ0.1 dm–3), Clostridium sulphito-reducer of vegetative form (<90 CFUꞏ0.02 dm–3) and sporulate (<4 CFUꞏ0.02 dm–3), total aerobic mesophilic flora at 22°C (<462 CFUꞏ0.001 dm–3) and at 37°C (<403 CFUꞏ0.001 dm–3). It must be noted that no presence of thermo-tolerant coliforms is observed.