ASSESSMENT OF AQUIFER VULNERABILITY TO CONTAMINATION USING A MODIFIED “LAHBUD” MODEL (“AHBD” METHOD) WITHIN FEDERAL UNIVERSITY OYE-EKITI

Abstract

Groundwater vulnerability to contamination risk of the peculiarities of Basement Complex terrain underlain with a major rock type has been studied at Federal University of Oye-Ekiti, Ekiti State, Southwestern Nigeria using remote sensing and integrated geophysical methods. Modelling of the study region took into account of forty (40) Vertical Electrical Sounding (VES) points. Landsat 8 and aeromagnetic data were processed for lineament extraction and composite lineament density generation. Four parameters which include depth to Aquifer (A), Hydraulic conductivity (H), Bedrock relief (B) and lineament Density (D) were identified to affect aquifer vulnerability of the region. The Multi-Criteria Decision Analysis (MCDA) in the context of Analytical Hierarchy Process (AHP) was employed for weights of 0.5436 (A), 0.2442 (H), 0.1359 (B) and 0.0763 (D) allocated to each of the parameters accordingly. Normalization of the assigned weight and its consistency was carried out (9.7%). The aquifer vulnerability map (“AHBD” model) of the region was developed. The area was classified into low, moderate and high aquifer vulnerability zones. “AHBD” model was validated with geochemical parameters and the result showed 76% of agreement which justified reliability of the model and the methodology used. Human and constructional activities should be controlled around the high vulnerability zones.