Seepage detection in earth-filled dam from self-potential and electrical resistivity tomography

Abstract

Earth-filled dams are prone to serious erosion and seepage by water flow. Anomalous seepage is a threat to the stability of dam structures and is a common hydrogeological hazard in engineering. It is of great significance to clarify seepage paths for targeted remediation. In this paper, we present the joint use of self-potential (SP) and electrical resistivity tomography (ERT) methods to characterize the seepage paths in an earth-filled dam, where there is already evidence of abnormal seepage. The ERT provides effective information on the resistivity structure of the dam. The SP data aims to invert electrokinetic current sources generated by the seepage. The results reveal that the seepage of the dam generates streaming potentials, which result in a negative SP anomaly with an amplitude of 50–80 mV at the surface. Based on electrokinetic current sources from SP data and resistivity structures, we reconstruct three seepage paths, which coincide well with field borehole information. This case demonstrates the effectiveness of combining SP and ERT for characterizing the seepage path of dams.