A multi-criteria decision analysis for groundwater potential evaluation in parts of Ibadan, southwestern Nigeria

Abstract

Multi-criteria decision analysis based on Saaty’s analytical hierarchy processing technique has been used to establish groundwater potential distribution pattern across some highly populated parts of Ibadan metropolis in southwestern Nigeria. The technique weighted and ranked seven sets of thematic hydrological parameters derived from Landsat 8 OLI satellite imagery, 143 vertical electrical sounding (VES) geophysical data, and geological and topographical data. Filtered and enhanced Landsat 8 OLI satellite imagery, quality-checked and inverted VES data, and categorized geological and other ancillary data were analyzed and used to generate lineaments, subsurface geoelectric parameters and other terrain information employed to extract thematic hydrogeological parameters used to characterize the subsurface in terms of groundwater potential. Weighted, normalized and ranked derived thematic hydrogeological parameters (lineament density, drainage density, coefficient of anisotropy, aquifer thickness, overburden thickness, aquifer resistivity and lithology) were employed to generate groundwater resource potential map. The map delineates the study area into very low (6.5%), low (41.0%), medium (38.1%), high and very high (14.4%) groundwater resource potential zones. Regions underlain by quartzite/quartz schist rocks present medium-to-high groundwater resource potential, while regions underlain by migmatite and granite gneiss rocks mostly have very low–low groundwater resource potential. This study indicates that variation in groundwater resource potential across Ibadan situated within the basement complex terrain is mostly influenced by the heterogeneity of subsurface geology which varies rapidly in terms of rock distribution and associated hydrogeological indices.