LAND USE/LAND COVER DYNAMICS AND ASSESSMENT OF SOIL EROSION USING REMOTE SENSING AND GIS TECHNIQUES: A CASE OF SILE WATERSHED, GAMO ZONE, SNNPR, ETHIOPIA

Abstract

Soil erosion is wide spread and serious throughout the Ethiopian highlands. It is also a major watershed problem in many developing countries causing significant loss of soil fertility, loss of productivity and environmental degradation. This research has, therefore, been carried out to quantify the major land use/land cover dynamics over the past thirty years and assessment of soil erosion using remote sensing and geography information system techniques in the Sile watershed. For the land use/land cover dynamics calculation three satellite images such as Landsat Thematic Mapper 1989, Landsat Enhanced Thematic Mapper Plus 2003 and Landsat8 2018 has been utilized. As a result the rate soil erosion risk and land use land cover map of 1989, 2003 and 2018 of the study area was generated. Rainfall data, soil data, Digital Elevation Model data and satellite image were used as input data sets to generate revised universal soil loss equation factor values. Raster calculator was used to interactively calculated soil loss rate and prepare soil erosion risk map. The result showed that extent in the classification, the plantation land use/land cover type was generalized to other classes, but, as evident in the field observation, forest is highly diminished due to cultivation. The forest cover has been declining since the year 1989 in the order of 14.2% for 2003 and 12.5% for 2018 and the annual soil loss of the watershed ranges from 0.00 to 393.49 ton per hector per year and the mean annual soil loss rate is 55.7 ton per hector per year. Among the six sub-watersheds, three such as SWS1, SWS3 and SWS5 were predicted to experience annual soil loss of more than the watershed’s average 55.7 ton per hector per year; whereas three sub-watersheds SWS2, SWS4 and SWS6 were estimated annual soil losses were less than the average.