Integrated use of electrical resistivity tomography and ground penetration radar for identifying subsurface sinkholes in Rufa Graben, Central Riyadh

Abstract

Two-dimensional electric resistivity tomography and ground-penetrating radar (GPR) study was carried out in the eastern Rufa Graben, Riyadh area. Dipole–dipole configuration was used with a total length of 360 m and an electrode spacing of 5 m. In addition, the same number of ground-penetrating radar profiles was conducted in the same location of the electrical resistivity tomography (ERT) profiles. The goal of this study was to map and delineate the subsurface karstic features in the study area such as sinkholes, cavities, and fractured zones. The two methods showed the efficiency to detect the near-surface cavities and their distribution in the study area. The detected cavities were of different sizes. The air-filled cavities have appeared in ERT sections as anomalies that have high resistivity values while the cavities filled with wet clay were characterized with low-resistivity values. In GPR sections, the karstic features were seen by either hyperbola diffractions or uplift and discontinuity in horizontal reflection events. The results obtained from this study will contribute in solving the geotechnical problems for any expected future constructions planned to be done in the study area.