Impact of land use land cover change on soil erosion risk in limu seka watershed of didessa sub basin‚south west Ethiopia

Abstract

Land Use/ Land Cover Change (LU/LCC) is one of the major human induced global changes. Information on LU/LC change and its impact on soil erosion risk in the watershed is essential for proper understanding of how land was being used in the past, what type of changes have occurred and are expected in the future. This study was carried out to analyze impacts of LU/LCC on soil erosion risk in the Limu-seka watershed of Didessa sub basin during the last three decades (1978 to 2019).Satellite image of Landsat4 TM of 1987, Landsat7 ETM+ of 2002, Landsat8 OLI TIRS of 2019 were analyzed using ERDAS IMGINE 2015 and Arc GIS 10.3.1 software. The LU/LC changes were classified in to five classes using supervised classification methods and field observations and interview were also conducted. The impact of LU/LCC on soil erosion risk in the study area was assessed using RUSLE model integrated with satellite remote sensing and GIS. The LU/LC change during these three decades show that agricultural land was increased from 22,516 ha (17.3%) in 1987 to 67,981.6 ha (52.33%) in 2019 while dense forest land was decreased from 54,308.06 ha (41.2%) in 1987 to 8,236.7ha (7.69%) in 2019. These indicate a sharp increase in cultivated land and decrease in forest land. The settlement was also increased from 2.8% in 1987 to 10.59% in 2019. Grazing fields and sparse forest decreases from 11.9% to 8% and from 26% to 22.8% respectively in the study area. The RUSLE model result showed that the rate of soil loss varied from 0 to 604 ton/ha/year in 1987, from 0 to 668 ton/ha/year in 2002 and was increased to 0-1211.9 ton/ha/year in 2019.