Analysis and Monitoring of Groundwater Vulnerability and Quality in the Sudano-Sahelian Zone: Case of the Yagoua Rice-Growing Basin, Cameroon

Abstract

The main aim of this study is to determine whether the groundwater in the Yagoua rice-growing basin is of satisfactory quality for human consumption. A pollution vulnerability map of the study area was first produced using the modified DRASTIC method. The area was then subdivided according to the vulnerability map results to guide sampling, and finally, the groundwater of the basin was classified. Intrinsic vulnerability mapping showed that the study area is dominated by very low to low vulnerability classes, covering 97% of the total area. The basin was divided into three zones based on vulnerability: zone 1 corresponds to the very low vulnerability class, zone 2 to the low vulnerability class, and zone 3 to the medium vulnerability class. Physicochemical analysis results indicated that iron is the major element, with concentrations well above the maximum allowable limit. The Piper diagram showed that 60% of the analyzed water has a calcium-magnesium bicarbonate facies. The Water Quality Index (WQI) reveals that 53% of the study area has non-potable groundwater, linked to high iron content. Groundwater in the Yagoua rice-growing basin is unfit for human consumption and requires prior treatment. Modelling shows that, higher permeability and deeper wells or water table generally have older groundwater and less vulnerability to pollution.