الفهرس 
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Abstract
In light of the Nile River’s importance to Egypt, this study investigates the cause of such morphodynamic changes, discusses the impact of dredging as a mitigation measure, and studies and predicts future morphological changes of the alternative solutions in the
research area using the two-dimensional SMS model and the “DELFT 3D” model. A
study area was chosen where data was available and impacts occurred (i.e., the area surrounding the 4th reach). The Bani-Suef Bridge region and the El-Menia Bridge region
were chosen to be investigated. The Bani-Suef Bridge is a prime example of
sedimentation within the navigation path, where an island was formed near the navigational vent downstream of the bridge. The existing structure, such as the ElMenia Bridge, can be sufficient to create problems for navigation. It was also
discovered that erosion happened on one side (the west side), while deposition occurred on the opposite side (the east side), which was where the navigation vent was located.For the Bani-Suef Bridge area, the model HEC-RAS was calibrated and then run to
predict the morphological changes under inquiry before and after the dredging project in terms of maximum and minimum flow for 10 and 20 years. At low water levels, the effective depth, water surface profiles, and velocity distributions were employed as indications to detect the presence of navigational bottlenecks. For 10 and 20 years, the dredging scenario reduced the rate of deposition by 23.1% and 25.9%, respectively. The study concludes that dredging is required to keep the river navigable and control increased sediment deposition. For the El-Menia Bridge, in simulation by the model HEC-RAS, three scenarios were evaluated before and after dredging operations for 2, 5,
and 10 years. When comparing the quantity of deposition before and after dredging, Over 2, 5, and 10 years, the sediment decreased by 38.3%, 31%, and 28.8%, respectively. As a result, dredging may be the best option for reducing sediment in the
navigation channel. To solve the problem, the dredging process must be repeated every
two years. To improve flow conditions, permanent regulation works such as spur dikes could prevent bed erosion and sedimentation throughout the study area. Also, the proposed alternatives to spur dikes were tested in order to improve the navigational conditions throughout the study area using the 2-D mathematical models. In the ElMenia region, one dike was constructed in the western part, 380 m upstream of the
bridge, which is the first. The second scenario was to build two dikes in the western section, approximately 130 and 380 meters upstream of the bridge’s axis. In the Bani-Suef region, one dike was constructed in the eastern part, 100 m downstream from the
bridge, which is the first. In the second scenario, two dikes were to be constructed in the eastern part, 100 and 650 meters downstream from the bridge’s axis. The mathematical models were calibrated and produced satisfactory results. The model “DELFT 3D” was
used to forecast the research area’s hydraulic characteristics and predict morphological changes under these two different scenarios. For each alternative tested, compare the
velocity distribution and shear stress versus those of the original flow conditions. The results from the mathematical models were presented in such a way as to illustrate the
influence of different scenarios. Using the suggested “DELFT 3D” model, In the BaniSuef region, without the use of dikes, the rate of deposition increased to 10 cm/year after two years. After using one dike, the deposition rate is almost 4 cm/year. When
using two dikes, the deposition rate tends to be low, and the erosion occurs at a rate of 4 cm/year. In conclusion, in the second scenario, the water depth affects the safety of river
navigation for boat crossings in the case of minimum flow. In the El-Menia region, after two years, the rate of deposition without the use of dikes rose to 7 cm/year. The deposition rate is almost 1 cm/year after using one dike. When two dikes are employed,
the deposition rate is low and the erosion rate is 3 cm/year. In conclusion, the second scenario is the best because the water depths are satisfied through the river’s east
channel at minimum flow, where the navigation path is located while slowing the rate of deposition. The study found that using the second scenario is better because it can improve the water depth at minimum flow. According to the analysis of the results, the second choice is the best and most ideal long-term solution to the navigational
bottlenecks.