keywords: Gully erosion, RUSLE, Soil loss, soil texture, soil erodibility
The annual soil loss from gully site in Ogbeson area of Benin City was assessed using the Revised Universal Soil Loss Equation (RUSLE) coupled to an ArcMap 10.4. The study utilised monthly rainfall data for 19 years (20002018) from the Nigerian Meteorological Agency, Digital elevation model DEM and soil samples. The soil samples were collected along the chainage points of the gully to a depth of 0.3m using soil auger at 150-metre (m) distance apart. The dominant soils are sandy soils mostly sandy-loam and loamy-sand. The soil of the area is friable and highly erodible due to low soil organic matter content. The erodibility factor (K) is nearly uniform over the area at 0.002 ton ha −1 MJ −1 mm −1 . The mean annual soil loss rate was 0.71 tons/ha/year which is a lesser volume when compared to the rate of 0.541 tonha -1 yr -1 estimated for the study area in 2012. The low rate might be due to the current intervention measures to stabilize the gully under the Nigeria Erosion and Watershed Management Project (NEWMAP). However, the study still reveals an increasing rate of soil loss especially when compared with values from previous studies in other agro-climatic zones. The growing rate might be due to loss of vegetation associated with rising urbanization in the area. Therefore, further and consistent intervention and conservation measures are required to arrest the gully’s expansion. Such measures include reforestation, conservation of vegetation, creation of retention trenches and other engineering structures including regular maintenance of existing structures.