Spatial Analysis of Environmental Risk Zones in Bayelsa State, Nigeria: A GIS-Based Assessment for Sustainable Land Use Planning

Abstract

This study assessed the spatial distribution of environmental risk zones in Bayelsa State, Nigeria, using Geographic Information Systems (GIS) techniques to support environmental management and sustainable development planning. The study was motivated by increasing environmental challenges, including flooding, wetland degradation, shoreline erosion, and climate-related hazards, which continue to threaten livelihoods and infrastructure across the Niger Delta region. Four objectives guided the study: to determine the spatial distribution of environmental risk zones, quantify the extent of each risk category, examine the dominance of risk categories, and evaluate their implications for environmental management. A GIS-based spatial analytical design was adopted, integrating Landsat 8 OLI imagery, the SRTM 30 m DEM, CHIRPS rainfall, SoilGrids soil texture, JRC Global Surface Water and official administrative boundary data. Seven environmental variables were weighted using the Analytic Hierarchy Process (AHP) and combined by weighted linear overlay into a composite risk index, which was classified into High, Moderate, Low, and Very Low risk zones. Low Risk Zones occupied 4,580 km² (46.9%) of the 9,760 km² analysed area, Moderate Risk Zones covered 2,432 km² (24.9%), Very Low Risk Zones accounted for 1,500 km² (15.4%), and High Risk Zones occupied 1,248 km² (12.8%). A chi-square goodness-of-fit test showed that the distribution departs significantly from an equal-area distribution (χ² = 2,821.4, df = 3, p < 0.001), and the share of High Risk Zones was significantly lower than an equal share of 25% (z = −27.9, p < 0.001). The study concludes that GIS-based risk zoning identifies vulnerable locations and provides useful information for land-use planning and disaster risk reduction, while noting that results depend on data resolution, the AHP weighting scheme and the absence of independent ground validation. The study recommends prioritising restoration in High Risk Zones, continuous GIS monitoring in Moderate Risk Zones, sustainable land-use practices in Low Risk Zones, and integration of risk maps into development planning and policy.