Geophysical Investigation of Oba Earth-Fill Dam Embankment using Electrical Resistivity Method

Abstract

Continual post-construction checks on dam embankment are inevitable to forestall the possible catastrophes associated with its structural failure. In view of this, electrical resistivity (ER) surveys involving vertical electrical sounding (VES) and dipole-dipole profiling were conducted along the Oba dam embankment as a part of routine deformation monitoring for any possible seepage(s) around the dam embankment. Thirty-one vertical electrical soundings and thirty-five dipole-dipole horizontal profiling data were carried out on a 350 m long (west-east trending) traverse established along dam embankment. The iterated VES curves were mainly KH-type suggesting that Oba dam embankment is underlain by four geoelectric layers; topsoil (caprock), fill (granite materials), core (plastic-clay/wet clay) and basement bedrock with resistivity values range of between 53-249 Ωm, 205-1084 Ωm, 15-124 Ωm and 281-1375 Ωm, respectively. The dipole-dipole 2-D resistivity structure along the dam embankment showed no evidence of structural distress/weakness within the underlying sequences. Therefore, by integrating results obtained from geoelectric section and 2D resistivity structure based on the layer resistivity/ lithological composition of the core materials (15-124 Ωm/plastic clay/clay/sandy clay), Oba earth-fill dam embankment integrity was good to very good indicating no seepage zone(s).

Subsurface Identification using Resistivity Method for Infrastructure Planning in Benowo Area, Surabaya City

“…One of the geophysical methods that can be applied to map subsurface conditions is the geoelectrical resistivity method [7], [8]. Resistivity method is used to determine the subsurface rock's resistivity values distribution [9], [10].…”