Flood Risk Mapping in Lokoja Using GIS and Hydrological Data

Lokoja, situated at the confluence of the Niger and Benue rivers in Kogi State, North Central Nigeria, is among the most flood-prone urban centres in the country. This study produces a flood risk map for Lokoja metropolis by integrating hydrological, topographic, and land use data within a GIS framework. Digital elevation model data from the Shuttle Radar Topography Mission is used to delineate watershed boundaries and derive flow accumulation and slope parameters. Historical flood event records obtained from the Nigerian Hydrological Services Agency are geo-referenced and analysed alongside rainfall data from the Nigerian Meteorological Agency. Proximity to water bodies, drainage density, soil permeability, and impervious surface coverage serve as input variables in the weighted overlay analysis. Results classify approximately 31 percent of the urban area as high-risk, particularly low-lying areas in Ganaja and Felele communities along the riverbank. The study demonstrates how GIS-based spatial modelling can support disaster preparedness and emergency response planning. Recommendations are directed at the Kogi State Emergency Management Agency and municipal planning authorities to prioritise drainage infrastructure investment in identified risk zones. Keywords: flood risk, GIS, Lokoja, hydrological modelling, Niger-Benue confluence