Utility Mapping and Underground Infrastructure Survey Using Ground Penetrating Radar in Kano Metropolis

The accurate mapping of underground utilities is a critical safety and engineering requirement in Nigerian cities undertaking road rehabilitation, utility expansion, and construction excavation activities. This study evaluates the application of Ground Penetrating Radar for utility mapping and underground infrastructure survey in Kano Metropolis, addressing the city's extensive but poorly documented network of water pipelines, electricity cables, sewerage lines, and telecommunications conduits. GPR surveys using 400 MHz and 900 MHz antenna frequencies are conducted along transects on selected road corridors in the Fagge, Gwale, and Nassarawa districts. Detected subsurface anomalies are interpreted, georeferenced using GPS, and mapped in GIS to compile a preliminary underground utility inventory. Results are validated against utility layout drawings held by the Kano State Water Board, Kano Distribution Company, and PHED where available. GPR detection accuracy for metallic utilities exceeds 85 percent, while accuracy for plastic pipes is more variable depending on soil moisture and pipe depth. The study documents significant discrepancies between as-laid drawings and actual utility positions, with some features displaced by over two metres from recorded locations. Recommendations address mandatory pre-excavation utility surveys, incremental expansion of the GPR survey programme, and the establishment of a shared underground utility GIS register for Kano Metropolis. Keywords: GPR, underground utilities, Kano, utility mapping, geophysical survey.