Spatial Mapping of Flooding Risk Zones in Lokoja, the Confluence Town of Kogi State

Lokoja, the capital of Kogi State situated at the confluence of the Niger and Benue Rivers in Nigeria's North Central geopolitical zone, occupies a geographically unique but hydrologically precarious position that exposes significant portions of its urban fabric to recurring flood events of varying magnitude. This study produces spatial flood risk maps for Lokoja using an integrated approach combining hydrological modelling, topographic analysis, and socioeconomic vulnerability assessment. SRTM digital elevation data at 30-metre resolution were used to delineate flood-prone areas below the 100-year return period flood elevation, calculated using historical discharge records from the Niger River at Lokoja Gauge Station maintained by the Nigeria Hydrological Services Agency from 1960 to 2023. Land cover data from Sentinel-2 classification were integrated to assess exposure of built-up areas, farmland, and critical infrastructure to flood hazard zones. Social vulnerability was assessed through household surveys with 350 respondents in six riverine communities, capturing asset ownership, insurance coverage, awareness of flood risk, and evacuation preparedness. Results classify 23 percent of Lokoja's urban area as high flood risk, including densely populated communities in Old Town, Adankolo, and Ganaja. The catastrophic 2012 flood, which inundated over 60 percent of Lokoja, is identified as the benchmark event driving current vulnerability perceptions. Flood risk communication, early warning dissemination, and structural flood protection along critical river frontages are recommended as priority interventions. Keywords: flood risk mapping, Lokoja, Niger-Benue confluence, North Central Nigeria, GIS.