Geoelectric and Geotechnical Soil Characterization at the School of Engineering, Kogi State Polytechnic, Lokoja, Nigeria.

This study examined waterlogging issues at Kogi State Polytechnic, Lokoja, Nigeria, by correlating resistivity measurements with geotechnical data. A 2D dipole-dipole electrical resistivity survey with 5-meter electrode spacing was conducted along three profiles. The data were inverted to interpret subsurface layers. Geotechnical tests, including grain size analysis and Atterberg limits, were interpreted along the profiles to analyze soil properties. The resistivity data identified distinct subsurface layers: the topsoil showed low resistivity between 11.3 and 21.8-Ohm meters, representing loose soils like sand and clay. A second layer (5-8 meters deep) had resistivity values between 20.9–121 Ohm meters, suggesting more compacted materials like clay. The third layer (6-11 meters deep) had resistivity between 60–338 Ohm meters and is interpreted as the weathered basement, while the deepest layer exhibited high resistivity (120–13,918 Ohm meters), indicating solid basement rock. Geotechnical tests revealed the presence of sand, clay, and silt. In addition, they showed varying plasticity and liquid limits: Profile 1 (PL = 26%, LL = 38%), Profile 2 (PL = 52%, LL = 58%), and Profile 3 (PL = 18%, LL = 23%). Profiles 1 and 2 had moderate plasticity, while Profile 3 had a much lower plasticity index of 5%. The inference from these results is that waterlogging is mainly due to prolonged wet seasons. However, if rainfall persists, the presence of clay and silt makes lithology a key factor. Ongoing monitoring and multidisciplinary research efforts are essential for refining the current understanding of the waterlogging process.