Characterization of the alteration profile of fractured aquifers in the agnibilekrou department (east of Cote D’Ivoire)

This study focuses on improving knowledge of the geometry and structure of the alteration profile of the various composite parts of aquifers in the Agnibilékrou department (East Côte d'Ivoire). The interpretation of the vertical electrical soundings and the drilling logs showed a strong variation in the thicknesses of alteration ranging from 2 to 70 m. The alterites are approximately 33 m, 45 m and 50 m respectively at Siakakro, N’guessankro and Mossikro. They generally consist of topsoil, alteration clays and schistose clays. Due to the mineralogical composition and the structure of the geological formations, the alteration is less pronounced in the granites (0 to 20 m) than in the schists (20 to 70 m). Water inflows are more observed for alterites thicknesses between 10 m and 30 m in granites and between 30 m and 40 m in schists. Between 60 m and 80 m thick, the frequency of water inflows is more significant in the granites than in the schists. The largest flows are provided by boreholes with alterites thicknesses less than 30 m in granitic rock while in schistous rock, they could come from alterites thicknesses between 30 m and 60 m. This study therefore highlights the importance of alteration in understanding the hydrodynamics of fractured aquifers in the basement.