A Study of Land Use and Gully Erosion in Nekede Community, Owerri West, Imo State, Nigeria Using the GIS

Abstract

Land use and gully erosion incidence in Nekede community, Owerri Imo state was studied using some digital tools of the GIS and remote sensing. The Nigeria sat. 2 imagery sourced from the National Space Research and Development Agency (NASRDA) was acquired from the Landsat ETM sensor with a resolution of 30m. Landsat TM and ETM data obtained had cloud cover of less than 20%. The images were geo-referenced to a Universal Transverse Mercator (UTM) grid using the software to allow compatibility and comparison with other data sets. The Shuttle Radar Topography Mission (SRTM) 30m DEM of the study area was downloaded from the CIAT-CSI SRTM website. These data were projected to the UTM coordinates system and clipped to the extent of the study area. The Normalized Difference Vegetation Index (NDVI) was equally used to show some details since a ratio of red and near infra-red bands from a remotely-sensed image-greenness can be defined. Results are that the colour differences found in a large part of the south-west indicated built-up but were much earlier in time covered by dense forest cover which the inhabitants cleared in the process of urbanization and agricultural activities exposing the fragile soil to heavy rainfall and concentrated run off. The high speed of the surface runoff leads to rapid washing away of the soil and weakening the soil strata bringing in effect gullies. Land use zoning using digital GIS and remote sensing models in monitoring land use/cover changes following existing master plans was among others recommended.