INVESTIGATION OF GULLY EROSION USING ELECTRICAL RESISTIVITY METHOD AND REMOTE SENSING TECHNIQUES IN UGBOWO, UNIBEN, BENIN CITY, EDO STATE, NIGERIA
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Abstract
This study examines gully erosion in Uniben, Ovia North East Local Government Area in Benin City, Edo State, Nigeria, using a combination of remote sensing and electrical resistivity approaches. Using the Wenner-Schlumberger array, fourteen profiles were used for 2D Electrical Resistivity Imaging (ERI), and RES2DINV was used to analyze the results. The Inverted 2D Resistivity structure from the study region is used to portray the data in this model in a color-coded manner.The section's vertical scale represents the depths, measured in meters, and its horizontal scale represents the lateral distance. A maximum spread of 200 meters was modelled, and all profiles were examined down to a comparable depth of 39.6 meters. The 2-D resistivity structure
analysis indicates that alluvium, laterite, and clay are present in the first four layers near the surface (12.6 – 31.9 m), and that this presence increases significantly as one descends (31.9 –39.6 m) to suggest that sand (alluvium and Laterite) may be the primary cause of the gully in the area. By integrating geoelectric sections derived from the 2D data, the study delineates the lithostratigraphy of the study area, predominantly identifying sand formations down to a depth of approximately 27 meters.
Moreover, the research includes the application of remote sensing techniques to monitor gully development over time and estimate the extent of gully erosion in the area. It encompasses Digital Elevation Models, as illustrated by heat maps, that employ the Normalized Difference Vegetation Index (NDVI) to evaluate the vulnerability of gully erosion in the studied region. The five zones on the NDVI maps are red, yellow, and green, respectively, denoting places that are very vulnerable to gully erosion, areas that are moderately prone, and areas that are less susceptible. NDVI data were calculated for each season during a four-year period, giving a multi-dimensional picture of the environmental changes in the area.
analysis indicates that alluvium, laterite, and clay are present in the first four layers near the surface (12.6 – 31.9 m), and that this presence increases significantly as one descends (31.9 –39.6 m) to suggest that sand (alluvium and Laterite) may be the primary cause of the gully in the area. By integrating geoelectric sections derived from the 2D data, the study delineates the lithostratigraphy of the study area, predominantly identifying sand formations down to a depth of approximately 27 meters.
Moreover, the research includes the application of remote sensing techniques to monitor gully development over time and estimate the extent of gully erosion in the area. It encompasses Digital Elevation Models, as illustrated by heat maps, that employ the Normalized Difference Vegetation Index (NDVI) to evaluate the vulnerability of gully erosion in the studied region. The five zones on the NDVI maps are red, yellow, and green, respectively, denoting places that are very vulnerable to gully erosion, areas that are moderately prone, and areas that are less susceptible. NDVI data were calculated for each season during a four-year period, giving a multi-dimensional picture of the environmental changes in the area.
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