The application of an expert knowledge-driven approach for assessing gully erosion susceptibility in the subtropical Nigerian savannah

• Main Authors: Gideon, Didams, Mustafa, Firuza Begham, Victor, Idakwo
• Format: Article
• Published: Wiley 2021
• Subjects: QE Geology
• Online Access: http://eprints.um.edu.my/27219/

This study assessed gully erosion susceptibility in Southern Gombe State, Nigeria. The objectives of the study were to: (1) prepare gully inventory of Southern Gombe State, (2) apply the Analytical Hierarchy Process to assess the contribution of gully erosion predisposing factors, and (3) produce a gully erosion susceptibility map of Southern Gombe State. Based on geomorphological study involving interpretation of Google Earth images and field surveys, 127 gullies were identified and 13 gully erosion predisposing factors assumed to influence gully erosion susceptibility were selected. Identified gullies were randomly split into training (89 or 70 per cent) and validation (38 or 30 per cent) datasets. The contribution of each gully erosion predisposing factor was obtained using the Analytical Hierarchy Process. The results indicated that slope (0.130), stream density (0.121), and distance from stream (0.121) play crucial roles in gully erosion susceptibility. By overlaying the gully erosion susceptibility factor maps, a gully erosion susceptibility map was created. A natural break method was then used to classify gully erosion areas into relatively safe (6.04 km(2)), less susceptible (3332.46 km(2)), moderately susceptible (1811.49 km(2)), highly susceptible (1146.35 km(2)), and extremely susceptible (1726.77 km(2)) categories. Field verification confirmed that the map accurately classified 92.11 per cent of the validation datasets, signifying the Analytical Hierarchy Process as a reliable method for gully erosion susceptibility assessment. The created gully erosion susceptibility map can assist land planners to identify critical gully erosion areas where prevention and mitigation actions should be implemented.