LINEAMENT MAPPING FOR GROUNDWATER MODELING IN THE OBAN MASSIF AND ENVIRONS, SOUTHEASTERN NIGERIA, USING ENHANCED LANDSAT TM AND GEOGRAPHIC INFORMATION SYSTEM TECHNIQUES

Automated lineament extraction techniques were used in modeling groundwater potential from enhanced landsat TM imagery in Oban massif and environs. Thematic maps of lineament, lineament density and reclassified lineament density map were produced from lansat thematic mapper. Software, such as PCI Geomatica, LINDENS and spatial analyst were used to compute lineaments, lineament density and rose diagram. Arc GIS9.2 was used to reclassify the lineament map into zones favourable for groundwater occurrence. Results show that lineament density can be classified into five main classes in the area as sparse, light, moderately dense, dense and very dense, which correspond with poor, fair, moderate, good and very good zones suitable for groundwater occurrence respectively. Rose diagram indicates predominant lineament distributions in the NNE-SSW and E-W directions, which suggest a strong relationship with the Pan African orogeny. The basement exhibits poor lineament density, suggesting low water storage potential, while the sedimentary region reflects better water potential than the basement area. Follow up geophysical and hydrogeophysical investigations in the area should be concentrated around zones delineated as good to very good groundwater stability ranges. Geo eye and SPOT imagery can also be employed in lineament studies in the area due to their smaller resolution range.