Application of GIS in Environmental Impact Assessment for Road Infrastructure Projects in Ogun State

Geographic information systems offer powerful tools for improving the spatial precision and analytical rigour of environmental impact assessments, particularly for linear infrastructure projects that traverse heterogeneous ecological and social landscapes. This study examines the application of GIS in environmental impact assessment processes for road infrastructure projects in Ogun State, South West Nigeria, evaluating current practice and identifying opportunities for enhanced integration. A case study approach was applied to three road projects for which completed environmental impact assessment reports were available, comparing the scope and quality of spatial analysis contained in approved reports against best practice standards. Practitioner surveys involving 25 certified environmental impact assessment consultants operating in Ogun State assessed current GIS capabilities, training needs, and institutional barriers to adoption. Findings indicate that GIS application in reviewed impact assessments is limited to basic project location mapping, with limited use of spatial overlay analysis for sensitive receptor identification, cumulative impact assessment, or alternatives analysis. Consultants cite inadequate GIS training, absence of updated baseline digital data, and cost pressures in consultancy fees as the primary barriers. The study demonstrates the value-added of multi-criteria GIS-based alternatives analysis using a demonstration exercise on one of the case study routes. Recommendations address mandatory GIS competency standards for Federal Ministry of Environment-listed consultants, establishment of a national environmental baseline geospatial data repository, and state-level environmental impact assessment training investments. Keywords: GIS, environmental impact assessment, road infrastructure, Ogun State, spatial analysis.