Mapping of Active Landslide Zones Using GIS in Ekiti State, South West Nigeria

Landslide occurrences in the hilly terrain of Ekiti State, South West Nigeria, have caused property damage and fatalities in recent years, underscoring the need for systematic hazard mapping to guide land use planning and disaster risk management. This study employs geographic information systems to map active and potentially unstable landslide zones across the Ekiti highland terrain, integrating multiple thematic data layers relevant to slope instability. A digital elevation model derived from the Shuttle Radar Topography Mission was processed to generate slope gradient, slope aspect, plan curvature, and topographic wetness index maps. Geological and soil maps were digitised and incorporated to characterise lithological and geotechnical controls. Normalised Difference Vegetation Index and land cover maps derived from Sentinel-2 imagery were used to assess vegetation cover as a stabilising factor. Field reconnaissance was conducted to inventory existing landslide scars, tension cracks, and mass movement deposits, which were used to validate the spatial model. A bivariate statistical analysis using frequency ratio was applied to identify conditioning factor combinations associated with observed failures. The resulting landslide susceptibility map classifies the study area into five susceptibility zones ranging from very low to very high. This map is communicated to the Ekiti State Emergency Management Agency for integration into disaster risk reduction plans. Keywords: landslide mapping, GIS, susceptibility zonation, Ekiti State, slope instability.