Significances of Deep Seated Lineament in Groundwater Studies around Ilesha, Southwestern Nigeria

Abstract

This research show the significance of deep seated lineament in  groundwater investigation around Ilesha, Osun State in a basement complex terrain using satellite imagery remotely sensed and aeromagnetic dataset. This hydrogeological investigation involved the extraction of lineaments from Landsat Thematic Mapper (TM) satellite imagery and aeromagnetic lineament of the area. The processed image revealled lineaments trending in approximately NE-SW direction; also, Landsat and aeromagnetic lineament trends tend to agree in the study area, suggesting real continuous fractures at depth. Lineament density maps were produced from the generalized lineament trends in the area. The lineament analysis has been effectively done in a GIS environment and the results justified that deep seated lineament (aeromagnetic lineament) is more significances in term of groundwater studies. Moreover, if surface (landsat) lineament is the only available information, it should be superimposed on topographical map for proper clarification and justification and also follow up by ground truthing. The lineament density maps of the study area were generally classified into very low, low, moderated, high and very high in term of their groundwater significances. The results from boreholes drilled across the entire study area, were used to validate the accuracy of the lineament density maps.