Investigation of Geophysical Methods for Assessing Seepage and Internal Erosion in Embankment Dams: Interpretation of Self-Potential Data for Dam Seepage Investigations

This report details the interpretation of self-potential (SP) data generated by subsurface fluid flow, with an emphasis on dam seepage investigations. Practical guidelines for the interpretation of SP data are provided, with a focus on the current state of practice in dam seepage investigations. The report includes a comprehensive review of available interpretation techniques, including qualitative, analytical and numerical methods. Particular emphasis is placed on the use of analytical (geometric source) modeling methods to evaluate SP anomalies. These methods provide a simple and efficient means of estimating the location and depth of current sources that give rise to the observed SP data, which may be linked to fluid flow in the subsurface. Numerical modeling methods are described, which involve calculating the SP response based on a subsurface seepage model. These methods enable the study of more complex systems and require a more comprehensive analysis of a given field site. As with most geophysical methods, the interpretation of SP data is non-unique, and must be constrained by integrating all available site information, hydraulic data and geophysical data. This volume marks one of a series of reports on the subject of geophysical methods and their use in assessing seepage and internal erosion in embankment dams.