Integration of remote sensing, GIS and 2D resistivity methods in groundwater development

Abstract

An integration of remote sensing, geographical information system (GIS) and 2D resistivity techniques was used to evaluate the groundwater potential of Obafemi Owode local government area (LGA) in Ogun State, southwestern Nigeria. A composite Landsat 7 image was used to produce land use and lineament of the study area. Advanced space-borne thermal emission and refection radiometer (ASTER) data were used to generate slope and drainage density. The study adopted modifed drastic model for groundwater potential, integrating six parameters which are land use, lineament density, slope, drainage density, geology and soil map. The contribution of each theme to groundwater potential was weighted and ranked using ArcGIS 10.2 software. The groundwater potential zone of the study area delineated fve distinct zones which include very high (196.39 km2), high (334.64 km2), moderate (481.76 km2), low (298.46 km2) and very low (95.73 km2). Eight zones were delineated for further study. A total of 4.8 line km of 2D resistivity profles were investigated in one of the designated zones labeled “area D” based on the groundwater potential map. Pole–dipole and dipole–dipole arrays used reveal fve geoelectric layers within the study area. The 2D inverse models of resistivity variation with depth suggest the occurrence of potential carbonate and silicate aquifers. To verify the interpreted results within the “high” groundwater potential zone, a well was drilled on traverse 1. A potential water-bearing aquifer was encountered at a depth of 75 m. The groundwater potential map of the study area was tested with fve existing wells, and the result was impressive. The outcomes from this study show that the high potential zones would play a key role in future expansion of drinking water and irrigation development in the study area.