The work presented here aims to carry out a physical characterisation of the soils in order to understand their hydrodynamic behaviour and estimate the susceptibility of each group of soils to microbiological pollution. The field work associated with the laboratory work consisted of monitoring the hydrodynamic behaviour of previously identified and selected well waters, measuring the permeabilities of the soil samples and analysing the bacteriological parameters of the sampled well waters. At the end of this work, the piezometric data show a dominant SE-NW and ENE-OSW flow direction. The water levels do not vary significantly between the wet and dry seasons. The granulometric analysis of the soils reveals CU>3 showing a spread out granulometry with very low permeabilities of the order of 1.58×10−7 m/s and moderately high permeabilities of the order of 1.86×10−5 m/s. The microbiological data show pollution of human origin with a high bacterial load in the rainy season represented by a maximum of 240 CFU of E. coli exceeding the WHO standards for drinking water. The majority of the polluted samples come from soils developed on granites and basalts which are the most susceptible to pollution making the groundwater vulnerable.

The purpose of this work was to show that the change in land use impacts the quality of free groundwater and therefore the health of the population in the city of Bafoussam. Using GIS by supervised classification, the land use map was made showing domination of the land by housing at about 42.23%, followed by agricultural areas at about 32.65% and green space representing 25.18%. The socio-economic diagnosis by the guided survey showed that 62.5% of the population consumes CAMWATER water with malaria as the dominant water-related disease. The collection of water samples analysed by the colorimetric and photometric assay has allowed us to obtain a dominant water facies of the chloride and sulphate–calcium–magnesium type. The mapping of areas potentially vulnerable to pollution by ArcGIS 10.8 software presents the low-lying areas, downstream of agricultural sites, close to industries and neighbourhoods with strong urban disorder as the most vulnerable to pollution and therefore retained as actors of diffuse groundwater pollution in the city of Bafoussam. Thus, the change in land use and the increase in agglomeration degrade the quality of groundwater in this city.