The Role of Surveying and Mapping in Erosion Management and Control: Case of Omagba Erosion Site, Onitsha Anambra State, Nigeria

摘要

Erosion has been described as the washing away of the top soil as a result of the actions of agents such as water and wind. Gully erosion, being the predominant in Southern Nigeria, is also a type of environmental degradation with a lot of disastrous consequences caused mainly by flood as a result of high precipitation, which is fallout of climate change. It can be determined, especially in terms of extent and scope, monitored and controlled. Surveyors’ contributions through provision of the necessary data, which includes, the topographic map of the area, DTM, catchment and watershed information, both centreline and cross sectional profiles of the resultant gully, the plan view of the gully and its tributaries, etc., for the research and design works on erosion control, have been examined. The data provided was also used for the computation of the volume of runoff from the catchment passing through the gully channel as well as the appropriate slope that would reduce the flow speed. Keywords: Watershed, Catchment, runoff, DTM.