Contribution of SAR/RADARSAT-1 and ASAR/ENVISAT images to geological structural mapping and assessment of lineaments density in Divo-Oume area (Côte d’Ivoire)

Access to drinking water and management of water resources are still a real issue in Côte d'Ivoire’s granitic and volcano-sedimentary basement regions. This situation is due to the combination of many factors including poor knowledge of hydrogeological environment. The present study assess the fractures’ network that has affected the Precambrian basement aquifer of Divo-Oume area by making a structural mapping and studying the spatial distribution of lineaments. For this purpose, the study exploits the contribution of radar images. Manually and without using directional filters, 7886 lineaments with variables lengths, have been derived from both RADARSAT-1 and ASAR images. The validation approach was based on the comparison between the orientations of the lineaments of the current study and those of the previous ones, and on the analysis of the distance between the nearest lineament and the well. This approach has shown that the lineaments would mostly correspond to fractures and they would be involved in the occurrence of groundwater. The analysis of lineaments orientations distribution revealed heterogeneity of directions and predominance of NW-SE and NE-SW families’ directions. The cumulative lineaments density map and one related the number of lineaments cross-points density revealed the spatial heterogeneity of fractures network which seem to be controlled by geomorphology, geological formations and lithology contacts. The results obtained from different thematic maps are useful for the context of setting up of high yield hydraulic drilling programs and the implementation of water resources management tools.