Deep Aquifers Study Using Geo-Electrical Imaging for Drinking Water Borehole Installation in Nioronigué (Department of Ouangolodougou, Northern Côte d’Ivoire)

Abstract

Access to groundwater in bedrock areas, such as the locality of Nioronigué with a high human density, is often hindered by the discontinuous nature of aquifers and the geological complexity of the crystalline substrate. In response to the pressing demand for sustainable drinking water in Nioronigué, Northern Côte d’Ivoire, this study employs Electrical Resistivity Tomography (ERT) with a dipole-dipole array to map deep aquifers within an intricate crystalline basement. Four geophysical sections, 290 meters long and to depths of 105 meters, generated two dominant subsurface facies: conductive facies (<100 Ω·m) and resistive facies (>100 Ω·m). Of specific interest is profile 4, which included an extremely conductive anomaly at 60 - 200 m lateral distance and 90 m depth, coinciding with fig tree ( Ficus gnaphalocarpa ) markers and crossing anomalies in the other profiles—a good sign of a strong, water-filled zone. The best hydrogeological conditions, including high aquifer thickness and good geometry, are found at the suggested site for drilling at X = 150 m with a target depth of 50 - 75 m. Comparison with regional studies affirms the existence of productive aquifers commonly at depths between 40 - 70 m. This marks the efficiency of ERT in the delineation of fractured and altered areas, supporting precise borehole siting in basement rocks. The study provides a replicable geophysical procedure for groundwater exploration in impoverished regions facing demographic and climatic pressures.