Geomatics Applied to Update the Geological Map of the Benoue Upstream Watershed (BUW)

All hydrogeological exploration work is predicated upon a comprehensive geological assessment of the watershed. Consequently, an initiative was undertaken to update the geological map of the Benoue upstream watershed (BUW), with the objective of facilitating future characterization of the aquifers in this basin. To this end, Landsat OLI and SRTM satellite images of paths 155 and 055 were employed to discriminate the lithology through the use of multiple methods, including color composition, principal component analysis (PCA), band ratio, and MNF analysis. In Addition, borehole logs, when examined through their cross-sections, facilitated the establishment of these correlations. The results of the processing operations are then compared with the Ngaoundere East geological map (1961) in order to provide guidance with regard to lithological discrimination, and with the 2021 geological map. To corroborate the final rendering, a field campaign is conducted to geolocate the geological formations at critical points and superimpose them on indices obtained through processing, thus facilitating the final perfection of the map. In total, six geological facies have been mapped at a scale of 1:50,000, forming the basis for future work.