ABSTRACT:- About two third of the population in the North of Togo lives in rural and semi-rural areas, depends on groundwater for drinking, for domestic and agricultural uses. Hydrochemical and statistical methods investigation are carried out on the groundwater of the basement aquifer system in the North of Togo in order to determine the mineralization water process. Chemical analysis were made at Laboratory of Water Chemistry (LCE) at University of Lomé according to AFNOR methods. The quality of groundwater has been conducted by using multivariate statistical and spatial analyses. Major chemical elements show that this aquifer system is composed by fresh water dominated by the Ca-Mg-HCO3 and Ca-HCO3 water types (about 93%). According to hydrochemical and multivariate statistical analysis, groundwater mineralization is caused by the silicates weathering related to the residence time of water in the aquifer, anthropogenic activities in urban environment and agricultural area, soil CO2 diffusion and cation exchange process.

Keywords:- Birrimian aquifer, Hydrochemical, multivariate statistical analysis, mineralization water process.