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<p>Soil erosion and silt deposition have caused significant problems in the Ethiopian highlands, particularly in the Upper Blue Nile Basin (UBNB), reducing the service life of reservoirs in the region. To develop effective mitigation strategies, it is essential to understand the sediment yield in the region and identify the hotspot areas. The Modified Universal Soil Loss Equation in Soil and Water Assessment Tool Plus (SWAT Plus) was used to simulate streamflow and sediment yield and identify the hotspot spatiotemporal variability of sediment yield in the UBNB at different reservoir catchments. The QSWAT Plus model is implemented by utilizing the digital elevation model, climate and weather generation data, land use, soil type, and slope of the UBNB. The Sobol tool algorithm, part of the SWAT Toolbox’s calibration and uncertainty analysis programs, is used to calibrate and verify streamflow and sediment yield monthly. The model exhibited satisfactory performance across all the watersheds studied. The Kessie watershed exhibited significant spatiotemporal variation in sediment yield. The spatial variation of sediment output across different catchments within the watershed ranged from 0 to 67.6t/ha/yr. 42.04% of the watershed area is a critical erosion region and 39.48% of the watershed is sub critical region. This significant spatial variability in sediment yield is attributed to a combination of human activities and environmental factors in the region. The extremely high sediment yield values observed in the parts of the watershed have serious negative consequences for the longevity and functioning of numerous reservoirs located in the Ethiopian highlands. Approximately 90% of the total yearly sediment load was recorded during the winter season. According to the simulation results, implementing filter strips, terraces, and contour procedures within the watershed could drastically lower watershed sediment yield by 58.67%, 93.685%, and 64.46%, respectively. The chosen best management practices (BMPs) have proven to be very effective in reducing sediment discharge in watershed-vulnerable areas. Based on the percentage reduction in sediment, it was concluded that terracing was the most effective strategy for the affected subbasins compared to other watershed management approaches. This study found that BMPs are effective at reducing sediment transport and could be used to reduce reservoir sedimentation in the UBNB.</p>

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Spatiotemporal sediment yield variability in the Upper Blue Nile Basin, Ethiopia

  • 期刊论文

  • 发表日期：

    2025年3月10日

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  • Bayu Geta Bihonegn,
  • Admasu Gebeyehu Awoke

摘要

Soil erosion and silt deposition have caused significant problems in the Ethiopian highlands, particularly in the Upper Blue Nile Basin (UBNB), reducing the service life of reservoirs in the region. To develop effective mitigation strategies, it is essential to understand the sediment yield in the region and identify the hotspot areas. The Modified Universal Soil Loss Equation in Soil and Water Assessment Tool Plus (SWAT Plus) was used to simulate streamflow and sediment yield and identify the hotspot spatiotemporal variability of sediment yield in the UBNB at different reservoir catchments. The QSWAT Plus model is implemented by utilizing the digital elevation model, climate and weather generation data, land use, soil type, and slope of the UBNB. The Sobol tool algorithm, part of the SWAT Toolbox’s calibration and uncertainty analysis programs, is used to calibrate and verify streamflow and sediment yield monthly. The model exhibited satisfactory performance across all the watersheds studied. The Kessie watershed exhibited significant spatiotemporal variation in sediment yield. The spatial variation of sediment output across different catchments within the watershed ranged from 0 to 67.6t/ha/yr. 42.04% of the watershed area is a critical erosion region and 39.48% of the watershed is sub critical region. This significant spatial variability in sediment yield is attributed to a combination of human activities and environmental factors in the region. The extremely high sediment yield values observed in the parts of the watershed have serious negative consequences for the longevity and functioning of numerous reservoirs located in the Ethiopian highlands. Approximately 90% of the total yearly sediment load was recorded during the winter season. According to the simulation results, implementing filter strips, terraces, and contour procedures within the watershed could drastically lower watershed sediment yield by 58.67%, 93.685%, and 64.46%, respectively. The chosen best management practices (BMPs) have proven to be very effective in reducing sediment discharge in watershed-vulnerable areas. Based on the percentage reduction in sediment, it was concluded that terracing was the most effective strategy for the affected subbasins compared to other watershed management approaches. This study found that BMPs are effective at reducing sediment transport and could be used to reduce reservoir sedimentation in the UBNB.