“…Increasingly, however, geophysical techniques are being used to provide more direct evidence about the geological setting of a karst system. Survey techniques, such as ground penetrating radar and electrical resistivity tomography (ERT), provide an efficient means of describing the karst structure, mapping karst conduits (Carrière, Chalikakis, Sénéchal, Danquigny, & Emblanch, ; Martínez‐Moreno et al, ), and defining the soil–rock interface (Chalikakis, Plagnes, Guerin, Valois, & Bosch, ). Such geological evidence is crucial for delineating hydraulic structures, such as complex subsurface drainage networks in the karst, which can link local fissure and fracture networks with the dominant large conduit systems (Binley et al, ; Chalikakis et al, ; Hartmann et al, ).…”