Integrating climate and regional causative factors in erosion risk mapping: evidence from the Isuikwuato region, Nigeria

Soil erosion is a major environmental problem in southeastern Nigeria, resulting from heavy rainfall, geology, topography, and land-use activities. This study modified the Coordination of Information on the Environment (CORINE) erosion risk model to assess erosion susceptibility in the humid tropical Isuikwuato region, Abia State, Nigeria. The model integrated land-use/land-cover, soil properties, lithology, topography, and climatic variables within a Geographic Information System (GIS). Lithology replaced the original stoniness parameter to account for local geological controls on erosion susceptibility. Landsat imagery, Shuttle Radar Topography Mission (SRTM) data, geological and soil maps, field soil samples, and long-term rainfall and temperature records were used in the assessment. Land-use/land-cover classification achieved an overall accuracy of 86% and a Kappa coefficient of 0.81. The erosion risk assessment classified 50.47% of the study area as most resistant, 29.15% as resistant, 12.01% as marginally resistant, and 8.38% as not resistant. Model validation using the Area Under the Curve (AUC) produced a value of 74.41%, indicating satisfactory agreement between predicted erosion patterns and field observations. The modified model improves the representation of spatial differences in erosion susceptibility and supports erosion control, soil conservation, watershed management, and land-use planning in Isuikwuato and similar environments in southeastern Nigeria.