Responses of soil erosion and sediment yield to land use/land cover changes: In the case of Fincha'a watershed, upper Blue Nile Basin, Ethiopia

Abstract

BackgroundLand use/land cover change (LULCC) exacerbates the global environmental changes through affecting ecosystem services. Soil erosion, which is the most significant global environmental problems caused mainly by LULCC, negatively affects agriculture and water resources development projects by increasing siltation of a reservoirs. As such, up-to-date and reliable information on the LULCC, trends, and its impacts on soil erosion and sedimentation is highly required. However, such an integrated study that uses high spatial earth observation data is limited in most basins of Ethiopia including the Fincha'a watershed. This study was, therefore, to quantify changes in LULC and its impacts on soil erosion by integrating RUSLE model and geospatial technologies. MethodsFor this study, spatial datasets such as Landsat TM, ETM+, and OLI/TIRS satellite images, satellite rainfall, soil, and digital elevation model (DEM) datasets were employed. As such, land use/land cover maps of the 1991, 2006, and 2021 were produced using the supervised image classification techniques of maximum likelihood algorithm. In addition, the impacts of changes in LULC on soil erosion were assessed by changing the C-and P-factors and keeping the other parameters constant. ResultsThe result showed increasing cultivated land, settlement land, and waterbody at the expenses of forest land, shrub land, and grassland. In response to the changes in LULC, the mean annual soil loss increased from 34.5 t ha−1year−1 during the 1991 to 46.4 t ha−1year−1 during the 2006 and to 58.7 t ha−1year−1 during the 2021 year. The result further shows that about 29,180.1 ha (7.6 %), 40,095.6 ha (10.5 %), and 40,969.0 ha (10.7 %) of the watershed were severely eroded during the 1991, 2006, and 2021 years, respectively. Likewise, increasing sediment yield from 1991 (6.7t ha−1year−1), 2006 (8.5t ha−1year−1), and to 2021 (10.3 t ha−1year−1) were observed. ConclusionThe increased soil erosion and sedimentation negatively affects water resource availability and agricultural production. Therefore, proper land management systems should be employed in the watershed to minimize the off-site and on-site effects of soil erosion.