Evaluation of Groundwater Vulnerability Using Soil and Hydrogeological Data in Parts of the Precambrian Oban Massif, Se Nigeria

Abstract Research on the vulnerability assessment of groundwater in the crystalline basement of the Oban Massif was carried out using soil and hydrogeological data. The parameters employed as input data included static water level (SWL), organic matter content (OMC), cation exchange capacity (CEC), aquifer media character (AMC), recharge (R), and soil type (ST). Results show groundwaters west of the massif (65% areal cover) to be the most vulnerable, with a decrease in vulnerability towards the eastern arm of the massif. The correlation matrix indicates SWL, OMC, and CEC as being significant factors that influence vulnerability ratings. Under current conditions, contamination indicators Cl- and NO3- show no contamination in relation to vulnerability ratings. The methodological approach and findings support the assessment model being quick and cheap, and can possibly be replicated in other areas where input data is available for assessment.