Estimation of the Volume of Soil Loss Due to Gully Erosion in Iwogban Urban Catchment Area in Ikpoba-Okha Local Government in Benin City, Edo State, Nigeria

Abstract

Soil erosion is an important morphological process contributing to land degradation in humid tropical environments. Information on soil loss is essential for selecting appropriate control measures to reduce on-site soil loss and its off-site effects, especially in-built environments. The objective of this study was, therefore, to estimate the volume of soil loss due to gully erosion in the Iwogban urban catchment area in Ikpoba-Okha local government in Benin City, Edo State, Nigeria, using the Revised Universal Soil Loss Equation (RUSLE) Model in the Geographic Information System GIS) environment. The result showed that about 30.2895 tons/ac/yr of soil is lost in the watershed, which exceeds the RUSLE tolerance value (T-value). If the computed soil loss exceeds the T-value, erosion is considered excessive, and improved erosion control is needed. Morphologically, the gully is u-shaped and highly active at the gully's head and side walls. Effective management practices such as re-channelizing the watercourse, partial reclamation of the gully head, introduction of vegetative cover, and afforestation are highly recommended.