ABSTRACT
Groundwater is one of the major sources of water. It is affected by a number of natural and anthropogenic factors. As groundwater use has increased, issue associated with the quality of groundwater resources have likewise grown in importance. In this study, leachate contaminant transport, groundwater quality assessment and geospatial modelling using Inverse Distance Weighting were employed to evaluate the properties of groundwater around the vicinity of a dumpsite in Benin City, Edo State.
The Dipole–Dipole array which is a 2-D imaging technique that involves the measurement of lateral and vertical variations in apparent resistivity of the subsurface earth was employed to study the transport of leachate contaminant around the study area. Based on the flow direction of the contaminants, eight (8) boreholes were studied and groundwater samples were collected for analysis, Various ground water quality parameters such as pH, turbidity, total suspended solids (TSS), Electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), phosphate, nitrate, sulphate, total solids (TS), sodium, potassium, calcium, magnesium, iron, lead, cadmium, zinc and chloride from eight (8) boreholes of known coordinates were investigated. Thereafter, the weighted average index method was employed to estimate the water quality index (WQI) of each sampled borehole,
From the contaminant transport analysis, the presence of leachate was identified at 20m to 30m of horizontal distance at 0m to 5m depth with resistivity of 57.5Ωm, 40m to 50m of horizontal distance at 10m to 20m depth with resistivity of 95Ωm to 135Ωm and 70m to 145m of horizontal distance at 0m to 10m depth with resistivity of 45.4Ωm to 116Ωm. The topsoil was observed to be highly contaminated with leachate at 70m to 145m of horizontal distance but the leachate could not migrate very deep into the subsoil because of the presence of lateritic Clay which is highly impermeable. The groundwater quality assessment revealed a lot of variability in the groundwater quality ranging from (29.67; Excellent water) to (135.57; Poor water quality)
