Ground-penetrating radar imaging of subsurface karst features controlling water leakage across Wadi Namar dam, south Riyadh, Saudi Arabia

Abstract This article presents a study conducted at the Wadi Namar dam in southern Riyadh, Saudi Arabia, using ground-penetrating radar (GPR) to investigate underlying karst features influencing water leakage. Through the acquisition of 38 GPR profiles downstream of the dam, the investigation reveals diverse structural irregularities primarily within the Jubaila carbonate rocks beneath the dam. The processed GPR data delineated vertical fractures dissecting the carbonate bedrock, as well as parallel sheet-like lateral fracture zones. These features enhance groundwater permeability, facilitating both vertical and lateral flow, thus impacting water leakage from the dam. Additionally, the presence of dissolution and karstic cavity structures is indicated by high-resolution GPR reflections, potentially acting as underground water reservoirs. The findings underscore the significance of karst features in governing water seepage at the dam site, emphasizing the importance of geological and geophysical investigations for dam safety and management.