Identification and Characterization of Pollution Plumes from Illegal Dumps Using Electrical Resistivity Tomography in the City of Ouagadougou, Burkina Faso, West Africa

Abstract

Illegal dumps have a major impact on the environment, particularly through groundwater pollution caused by leachate in the form of a pollution plume. Indeed, the pollution plume consists of various ionic pollutants, notably dissolved trace metals, whose presence in the soil or groundwater alters the electrical characteristics of the environment. The objective of this study is to characterize the pollution plume from the illegal dumpsites at Goundrin and Yamtenga in the municipality of Ouagadougou (Burkina Faso) using the electrical resistivity tomography method. This method allows for the determination of the medium’s electrical parameters (electrical resistivity and conductivity), a parameter that indicates a material’s ability to resist the flow of electric current. The application of this method revealed the presence of a pollution plume by defining its geometry (lateral extent, depth, and thickness). Indeed, the electrical resistivity tomography profiles positioned to intersect the direction of groundwater flow indicate the presence of resistivity anomalies with very low electrical resistivity values ranging from 3 to 15 Ωm. These anomalies correspond to a pollution plume that reaches depths of approximately 20 m in some areas, with a thickness of 2 to 20 m and a lateral extent of 5 to 90 m. These results also made it possible to identify clay zones acting as a barrier that slows the migration of the pollution plume in the direction of groundwater flow while limiting its infiltration into the groundwater aquifer.