Geohydrological study of weathered basement aquifers in Oban Massif and environs Southeastern Nigeria: using Remote Sensing and Geographic Information System Techniques

Abstract

The focus of this research is to model the geohydrology of the precambrian Oban Massif using geospatial techniques. Groundwater control indicators such as geology, geomorphology, drainage density, lineament density, land use / land cover and slope steepness were derived from landsat ETM + imagery, ASTER DEM and SRTM DEM. Image processing software such as ENVI 3.2, ARC GIS9.2 and PCI Geomatica were used for image processing , digitizing and lineament density computation respectively. Weighted averages of the groundwater controlling factors were used to produce thematic maps of geology, lineament density, drainage density, slope steepness, land use/land cover and geomorphological units. The thematic maps were overlaid in a GIS environment to model the ground water potential map of the area. Arc GIS, Arc View and Map Info were used for geographic Information System analysis. ERDAS imagine 8.6 and ENVI 4.2 were used for georeferencing, image analysis and coordinate transformation. ASTER DEM was used for analysis of geomorphology. For vegetation, discrimination in land cover / land use mapping band 4: 3: 2 for landsat ETM + was used. Unsupervised was used to have a general idea of the area. Supervised classification was used for final land use/ land cover mapping. Result show that geology, lineament density, and slope steepness are the most influential groundwater controlling factors of groundwater potential. Their degree of influence can be summarized as geology > lineament density> slope>geomorphology>drainage density>land use / land cover. From the groundwater potential map, four groundwater potential zones: very good, moderately good, fair and poor. Successful boreholes drilled in the groundwater favourable potential areas should be reticulated to the neighbourhood with poor groundwater potentials to salvage groundwater problem in the study area.