Vulnerability of groundwater investigation around dumpsite in Ughelli and environs in Delta State using remote sensing and geophysical methods.

Abstract

The increasing number of dumpsites in Nigerian cities is attributed to urban population growth and industrial development. In the Ughelli area of Delta State, several large-scale landfills threaten local geology and groundwater through toxic waste seepage. This study sought to identify subsurface and groundwater pollution within and around two major landfills in Ughelli and neighboring areas using Vertical Electrical Sounding (VES) and remote sensing techniques. Fifteen VES stations were surveyed with a Schlumberger configuration and a maximum electrode spacing of 100 meters. Data from the VES studies were analyzed using IX1D software. Geoelectric parameters, including longitudinal conductance (S), transverse unit resistance (Tr), longitudinal resistance (ρL), and transverse resistivity (ρt), were calculated from the resistivity values. The estimated parameters ranged from 0.07 to 1229 mhos for S, 2.79 to 20126.83 Ωm² for Tr, 1.88 to 3929.04 Ω-m for ρL, and 3.3 to 3758.98 for ρt. Remote sensing was also used as a reconnaissance tool to assess subsurface lithology vulnerability. The results identified three to five geoelectric layers, predominantly of the HK curve type. Further analysis of S indicated that VES 9 and 13, located near waste dumps, are more susceptible to leachate flow compared to other VES points in the study area. Sensing data suggest that regions with higher drainage densities or porosity exhibit faster subsurface leachate movement and a greater risk of groundwater contamination, aligning with findings from other studies.