Groundwater Pollution Index Evaluation Test Using Electrical Conductivity in a Semi-arid Quaternary Aquifer (Kousseri-Cameroon, Lake Chad Basin): Multivariate Statistical Analysis Approach

Abstract

The shallow quaternary aquifer of the Lake Chad Basin is an important source of drinking water supply and irrigation in the city of Kousseri. Electrical Conductivity (EC), Total Dissolved Solids (TDS) and pH were measured in situ in samples from 161 boreholes, while 8 boreholes selected based on EC spatial variation—were used to determine the concentrations of major cations and anions in groundwater. The pH values ranged between 6.94 and 9.97 with an average of 7.74 ± 0.45 which indicates that the groundwater of the study area is acidic to alkaline. TDS, representing the hydrochemical properties of groundwater, ranges from 45 to 144 mg/L with an average of 76.52 ± 20.16 mg/L. These values indicate that the groundwater of the study area is fresh (TDS < 1000 mg/L). EC of groundwater ranges from 94 to 296 µS/cm with an average of 151.32 ± 40.54 µS/cm. The Pollution Index (PI) determined on 8 points varies between 2.96 and 4.67. This index presents a relationship according to a polynomial model with the corresponding EC values. Substantial differences in EC and PI values are observed in the groundwater of boreholes, which may indicate local contamination.