Geotechnical Investigation of Namar Dam Site by Using Geophysical Tools, Riyadh, Saudi Arabia

Recently, some areas in the Kingdom witnessed collapse of dams, and in others enormous amount of water are being wasted due to the leakage across the dams due to defective structure (cracks and fissures) and bedrock cavities. Therefore, the necessity for geotechnical assessment of the dams and their sites has become very vital and is considered a fundamental step towards the proper protection and long-term performance of these dams. In this respect, geophysical tools are often the most cost-effective and rapid means because of their site accessibility, portability, noninvasiveness, and operator safety. Based on the expected hazards that threaten the existing dams in Riyadh area, the proposed research employed different geophysical techniques to be applied on Wadi Namar Dam site, which are often the most cost-effective and rapid means. Electrical Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT) and Ground Penetrating Radar (GPR) techniques were used for mapping bedrock topography, identifying near-surface karstic terrain and regions of potential weakness (e. g. , faults and fractures) in the study site.