The Menzel Bourguiba Aquifers (Northeast Tunisia): Mineralization Characteristics

The migratory flow of the population toward large cities, and the growth of industrial and agricultural activities in recent years, have caused an increase in demand for the phreatic aquifer of the Menzel Bourguiba basin in Northeast Tunisia. These excessive demands have resulted in high mineralization of the groundwater and degradation of its hydrochemical quality (salinization). The objectives of this short paper are to follow the spatial evolution of the hydrochemical quality of the groundwater and to interpret the processes of mineralization. Indeed, geochemical and statistical approaches were applied to groundwater samples collected from 18 wells and 17 boreholes during the campaign in October 2019. The results of the analyzed samples indicate groundwater pollution with high concentrations of nitrate. The analyzed hydrochemical facies show the predominance of two major water types in the study area. The first, located upstream of the studied basin, is of moderate salinity, SO4–Cl–Ca rich with the recently renewed part. The second type is highly mineralized and Na-Cl rich. The statistical analyses, the calculated saturation indexes, and the correlation between the major elements results indicate that groundwater mineralization is controlled by rock–water interaction, dissolution, precipitation processes, and ionic exchange mechanisms. This work provides technical support for developing strategies to preserve groundwater availability and protect water quality.