Investigating epikarst using low-frequency GPR: example from the Gran Sasso range (Central Italy)

A realistic 3D view of the epikarst is key to understanding karst groundwater phenomena. Ground penetrating radar proved to be highly effective for investigating the epikarst of a sinkhole located in the Gran Sasso karst range (central Italy). Two different low-frequency antennae (100 MHz bistatic shielded and 40 MHz bistatic unshielded) were used. The radar signal interpretation was correlated with field observations of the epikarst and borehole data. Two radar anomaly surfaces were identified, which were correlated with the top and bottom of the epikarst surface. The shape of the two surfaces correlates well with the surface topography of the study sinkhole and with the orientation of its main joints and karren. The work indicated that such a 3D reconstruction could be usefully applied to karst aquifer vulnerability studies.