Assessment of Erosion Susceptibility Using Remote Sensing in Anambra State

Gully erosion constitutes one of the most severe land degradation challenges confronting communities across Anambra State in South East Nigeria, with recurring episodes displacing settlements and destroying farmland. This study employs remote sensing and geographic information systems to assess erosion susceptibility across selected local government areas in Anambra State, drawing on multi-temporal satellite imagery to document erosion progression. Landsat 8 OLI and Sentinel-2 imagery were processed using spectral indices including the Normalised Difference Vegetation Index and Bare Soil Index to delineate erosion-affected zones. Digital elevation model data from the Shuttle Radar Topography Mission were used to derive slope, aspect, and drainage density parameters that influence erosion dynamics. A multi-criteria evaluation framework integrating lithological maps, soil erodibility data, and rainfall intensity was applied to generate susceptibility maps classified into low, moderate, high, and very high risk categories. Field validation was undertaken to verify the accuracy of remotely sensed classifications. Results indicate that communities underlain by friable Nanka Sands exhibit markedly higher susceptibility owing to low cohesion and high infiltration capacity of the formation. The susceptibility maps produced are envisioned as planning tools for the Anambra State Environmental Protection Agency and relevant agencies managing gully remediation programmes. This study contributes spatial data essential for landscape management and climate adaptation planning. Keywords: erosion susceptibility, remote sensing, gully erosion, Anambra State, GIS.