Detecting land use and land cover changes and quantifying soil erosion and sediment export using GIS and remote sensing in the GERD catchment, Ethiopia

Understanding soil loss, sediment export, and land use patterns is critical for sustainable land management in the Abbay, where poor land management accelerates erosion, reduces agricultural productivity, and threatens reservoir capacity. This study aimed to detect land use/land cover changes between 2011 and 2021, and quantify soil sediment export in the Grand Ethiopian Renaissance Dam catchment. Landsat imagery, Digital Elevation Model, CHIRPS rainfall data, and soil data were used. To generate the LULC map, a supervised image classification technique was employed. The RUSLE model and sediment delivery ratio were used to estimate soil erosion and sedimentation, respectively. During the study period, land conversion led to a substantial increase in water and built-up areas, replacing forest and grazing lands. Forest and grassland areas declined from 23.7 to 9.6 % and 30.2–20.3 %, respectively, while water bodies, shrubland, and built-up areas increased. Radical increases were observed in coverage of water bodies and built-up areas. Soil loss varies from zero in plains to over 50 t ha −1 yr −1 in steep terrain, with total soil loss decreasing slightly from 875,368.6 t yr −1 in 2011 to 845,621.6 t yr −1 in 2021. Despite this, sediment export increased by 18.4 %, from 0.14 to 0.16 t ha −1 yr −1 , indicating enhanced sediment transport from critical source areas. These results reveal that although overall erosion slightly declines, land use/land cover changes intensified sediment delivery, particularly in the upper catchments. Accordingly, implementing targeted bio-physical conservation measures is essential to reduce erosion, rehabilitate degraded land, and manage reservoir siltation, particularly in the upstream sub-catchments.