Ground Penetrating Radar Investigation of Subsurface Utilities and Buried Structures in Enugu Urban Centre

Urban infrastructure management in Enugu metropolis is increasingly challenged by the lack of updated records for subsurface utilities and buried structures, which contributes to accidental damage during excavation and road rehabilitation. This study applies ground penetrating radar (GPR) to detect, map, and characterize subsurface utilities and buried structures in selected high-traffic areas of Enugu urban centre. GPR data were acquired along twelve traverses using a MALA ProEx system equipped with 250 MHz and 500 MHz antennas. Data processing involved signal dewow filtering, background removal, gain function application, and migration. Reflectors in the resulting radargrams are interpreted on the basis of hyperbolic diffraction patterns, amplitude contrasts, and depth estimates. Buried pipe systems, primarily water and drainage conduits, were identified at depths ranging from 0.4 m to 2.1 m. Anomalies consistent with abandoned buried structures and rubble infill were detected in several locations within the historic core of the city. Utility crossings and pipe joints are clearly imaged on the migrated sections and confirmed against available records where they exist. The 500 MHz antenna provided higher resolution imaging suitable for shallow features, while the 250 MHz antenna offered improved penetration for deeper targets. The mapped utility network provides actionable information for municipal infrastructure management and reduces excavation risk. This study demonstrates the applicability of GPR in the challenging urban geologic setting of southeastern Nigeria and recommends its institutionalization in city infrastructure management protocols.

Keywords: ground penetrating radar, subsurface utilities, urban infrastructure, hyperbolic diffraction, Enugu