Evaluating the joint use of GPR and ERT on mapping shallow subsurface features of karst critical zone in southwest China

The soils and underlying weathered carbonate rock in karstic regions play an important role the infiltration, storage, retention of water nutrients. Because significant heterogeneity karst, use individual geophysical techniques is often not sufficient for unambiguous assessment irregular distributions fractures. In this study, ground penetrating radar (GPR) electrical resistivity tomography (ERT) are jointly used with additional observations to delineate shallow subsurface structure two exposed profiles. results show that ERT effective detecting soil–rock interfaces, even terrain fracture structures, such as a funnel-shaped doline, rocks large contrast. Although may be able sense presence extensive fracturing, it cannot detect small aperture Joint different frequencies GPR antenna (e.g., 100 500 MHz study) allowed detection most fractures at depths study sites. However, forward modeling typical features illustrates data resolve any reflection signals vertical fractures, so vertically enlarged filled by seen from images. Moreover, uncertainties interface between or bedrock limit identification irregularly distributed structure. Despite limitations techniques, combination enhances delineation soil–bedrock network, which can allow enhanced geological interpretation karst areas.