Application of Remote Sensing, GIS and Hydrogeophysics to Groundwater Exploration in parts of Lagos Metropolis: A case study of Oshodi/Isolo LGA

Abstract

Productivity through groundwater is quite high as compared to surface water, but groundwater resources have not yet been properly exploited. The present study is used to delineate various groundwater potential zones for the assessment of groundwater availability in Lagos metropolis using remote sensing and GIS and hydrogeophysics techniques. Landsat 8, SRTM, geological, soil, and rainfall data were used in the study to prepare various thematic maps, viz., geomorphological, slope, soil, lineament density, rainfall and land use maps. On the basis of relative contribution of each of these maps towards groundwater potential, the weight of each thematic map have been selected and assigned to each map. Hydrogeophysics investigation using Vertical Electric Sounding (VES) was applied to validate the remote sensing and GIS results. All the thematic maps have been registered with one another through ground control points and integrated using the weighted overlay method in GIS for computing groundwater potential index. Based on the methological approach, the ground water potential zones were delineated. The results showed that there are five categories of groundwater potential zones within the study area in which percentage values were contained in each of the categories thereby making major portion of the study area “high” and “moderate” prospect while a few scattered areas have “low” prospect. The very high potential areas are mainly concentrated along the River Alluvium while the “very low” prospect are majorly where there is sand and clay. The best groundwater potential zone is in the southern part due to the presence of fractures, swamp soils which have high infiltration ability and the presence of waterbody which is chiefly accountable for the groundwater recharge in any area. The VES data showed the depth of the aquifer for good water and the polluted aquifer within the study area.