Environmental Sensitivity Index Mapping and Assessment of Gully Erosion Sites in Anambra State –Nigeria.

摘要

This research focuses on the environmental sensitivity index mapping and assessment of gully erosion sites in Anambra State. It was motivated by the increasing destruction of lives and properties in Anambra State through gully erosion menace and the need to identify the geographical locations and magnitude of these sites in addition to factors responsible with a view to proffer solutions. It pursues map production as a way to visually display the locations of these gully sites. Gully sites in Anambra States were identified through literature and field investigations. Geographic positioning system (GPS map 78) equipment was employed to obtain the coordinates of the sites. Digital camera was used to take photographs of identified sites. Factors responsible for the gully formations were obtained through literature and field investigations. The coordinates of the gully sites were plotted on the geo-referenced map of Anambra State to indicate the geographic locations of the sites. The gully sites were categorized into four using: (i) depth of the gully site, (ii) length of the gully, and (iii) level of destruction of lives and properties so far, as criteria. Results obtained showed that there are 166 gully sites in Anambra State, categorized into (i) Most severely, (ii) severely, (iii) moderately, and (iv) slightly gully sites. It identified both natural and anthropogenic factors such as nature of the landscape, soil, rocks and surface water; demographic factors, bad control measures and poor appreciation of erosion problems among others as being responsible for gully erosion menace in Anambra State. The research recommends tree planting campaigns, control of soil and sheet erosion early enough, development control measures and environmental education among others as solutions to gully erosion problems in the State. Keywords: Gully erosion, Erosion, Environmentally Sensitive Areas, Index mapping, Anambra State maps