ANTHROPOGENIC CONTRIBUTION TO GULLY INITIATION AND PROPAGATION IN SE NIGERIA
Several large gully systems are currently active in Abia, Anambra, Enugu, and Imo States of SE Nigeria. Poor design and construction of roadside drainage is a major cause of gully erosion. Improper termination of drains and blockage of drains by silt and debris causes the water to overflow. This erodes the sides and ends of drains, undercuts them, and causes their collapse. The resulting unregulated water flow causes rapid development and advance of gullies. Footpaths and trails with foot and wheeled traffic disrupt vegetation cover and are sites of increased compaction of surface soils. The compacted paths are less permeable, and serve as channels for surface water, giving rise to localized erosion and initiation of gullies. Annual advances of gully heads by up to 60 meters were documented.
The project, Gully Erosion, Nigeria, involved University of Windsor Earth Sciences, Windsor, Ontario, Canada, and two Nigerian universities, the Nnamdi Azikiwe University, Awka, and the University of Port Harcourt, Port Harcourt. The International Development Research Centre, Ottawa, Canada, funded the project.