Effects of land use and land cover changes on sediment yield dynamics in the Kessem watershed, Middle Awash sub-basin, Ethiopia

Land use and land cover (LULC) changes drive sedimentation, impacting water availability, agricultural productivity, and ecosystem sustainability. Previous studies in the Kessem watershed lack analysis of LULC change effects on sediment yield, particularly at the sub-watershed scale. This study addresses this critical gap by analyzing LULC transformations from 1994 to 2020 and examining their effects on sediment yield using the Soil and Water Assessment Tool. Three LULC maps (1994, 2007, and 2020) were classified using ERDAS IMAGINE 2014. Results showed that agricultural land is the dominant LULC class, with a 6.05% increase between 1994 and 2020 at the expense of grassland, forest, and shrubland. The SWAT model successfully simulated hydrological responses, showing Nash–Sutcliffe efficiency values of 0.79/0.77 for streamflow and 0.73/0.56 for sediment yield in calibration/validation. Eight out of 21 sub-watersheds faced severe soil erosion, covering 35.2% of the total area and contributing significantly to sediment yield. Sub-watershed four showed a 106.5% sediment yield increase (42.9 t ha−1 yr−1 in 1994 to 88.6 t ha−1 yr−1 in 2020) due to agricultural expansion on slopes ≥3%. Urgent watershed management strategies such as terracing, afforestation, and conservation agriculture are needed to mitigate soil erosion and sustain land productivity.