The construction of the Beni-Suef Bridge, spanning 550 meters over the Nile River, resulted in sediment accumulation and hindered navigation. This study investigates the causes of the morphodynamic changes and explores the impact of dredging as a mitigation measure through the area which extended of approximately 2.60 downstream the previous bridge. A one-dimensional numerical model (HEC-RAS) was employed, utilizing bathymetric surveyed cross-sections from 1982, 2002, and 2004, along with discharge data from downstream Assuit Barrage and water levels from upstream Delta Barrage as boundary inputs. The model was calibrated and validated using measured water and bed levels. Sediment properties and bed composition were incorporated based on samples collected by the Nile Research Institute. Three distinct sediment load formulas were utilized to identify the most suitable one for accurately capturing the physical characteristics of the studied area. After validation, the model was utilized to forecast cross sections for 10 and 20 years, in case of with and without dredging scenarios. The dredging approach was aligned with the navigation requirements in the study region. The study reveals that the Ackers-White sediment formula showed the closest match with minimal differences in deposition and erosion compared to other formulas. Besides, the study area is predominantly experiencing deposition, which is projected to continue in the future. In addition, the predicted sediment volumes were concentrated at the beginning of the study area in both scenarios. The findings indicate also that most deposition occurred in the initial ten years approaching a state of morphodynamic equilibrium. Moreover, the results showed that dredging reduced rates of sedimentation by 23% and 26% after 10 and 20 years, respectively, which provide an effective solution for mitigating sedimentation along the navigation path in the study area. |
