Présentations Colloques

Oral Presentation
8.07
Session 8.07: Hydrogeophysics: innovative non-invasive technologies for groundwater resources exploitation and management
Fatoba Julius
INTEGRATED USE OF GEOELECTRICAL IMAGING AND HYDROCHEMICAL METHODS IN ASSESSMENT OF THE IMPACT OF SOLID WASTE ON THE GROUNDWATER AT ABULE-EGBA DUMPSITE, LAGOS, NIGERIA
Solid waste dumpsites usually pose a serious threat of polluting the surrounding groundwater. To this end, the Abule – Egba solid waste dumpsite in Lagos, Southwestern, Nigeria, was investigated by using geoelectric resistivity methods to ascertain leachate plume generation , migration and its impact on the surrounding soil and groundwater. 2-D resistivity imaging using Dipole-Dipole array was carried out along the major profile in the site in order to delineate the plume and possible trend of migration. Six VES locations were also occupied along the 2-D resistivity imaging profile. The 2-D resistivity imaging data were interpreted by Dipro software while VES data were interpreted by partial curve matching and 1-D computer modeling. **The results of the 2-D resistivity imaging revealed very low resistivity values ranging from 13 ohm-m to 72 ohm-m , which is diagnostic of a medium that is saturated by conductive fluid presumably a medium polluted by leachate. This result correlates well with results of the VES technique that show resistivity values varies from 5 ohm-m to 25 ohm-m at the leachate affected zones. The geoelectrical parameters are compared to results of groundwater samplings at the site and to results from the borehole logs, which confirmed that the low resistivity layer is sand formation that is highly polluted by leachate generated from the dumpsite. In addition to this, the results of geochemical analysis from the groundwater samples are above the World Health Organisation (WHO) permissible limits for potable water. **
Nigeria