Submerged breakwaters are widely used because of their economic, environmental, and aesthetic adv... more Submerged breakwaters are widely used because of their economic, environmental, and aesthetic advantages. However, sea level rise and excessive settlement cause a reduction in wave attenuation and breakwater efficiency. So, the rehabilitation of submerged breakwaters efficiency is considered one of the important issues in the field of harbor engineering and shore protection. Wave screens can be used for this purpose due to their considerable advantages, as their construction is inexpensive, easy and requires less material, time, and space. Also, they are considered an environmental friend solution as they do not obstruct water flow or fish passage. An experimental investigation was executed to determine the impact of the settlement of submerged breakwaters on their efficiency and investigate the influence of placing the wave screens above the breakwater to enhance its efficiency. The results showed that the reduction of the relative height of the breakwater by 10 % and 20 % decreases the efficiency by 10 % and 37.5% respectively. Also, the used single wave screen improved the efficiency by 19.3% and the screen porosity had a significant impact on the breakwater efficiency. However, the screen position had an insignificant influence on rehabilitation. In addition, the double wave screens increased the breakwater efficiency by 16.40%. Finally, placing the wave screen above the tested breakwater was better than using it in front of the breakwater and more economic.
Deep navigation channels have a great impact on adjacent beaches and crucial economic effects bec... more Deep navigation channels have a great impact on adjacent beaches and crucial economic effects because of periodic dredging operations. The navigation channel of the Damietta harbour is considered a clear example of the sedimentation problem and deeply affects the Northeastern shoreline of the Nile Delta in Egypt. The aim of the present study is to monitor shoreline using remote sensing techniques to evaluate the effect of Damietta harbour and its navigation channel on the shoreline for the last 45 years. Also, the selected period was divided into two periods to illustrate the effect of man-made interventions on the shoreline. Shorelines were extracted from satellite images and then the Digital Shoreline Analysis System (DSAS) was used to estimate accurate rates of shoreline changes and predict future shorelines evolution of 2030, 2040, 2050 and 2060. The Damietta harbour created an accretion area in the western side with an average rate of 2.13 m yr-1. On the contrary, the shoreline...
Navigation channel is one of the main components of any harbour that it facilitates the access of... more Navigation channel is one of the main components of any harbour that it facilitates the access of ships to harbour. Periodic maintenance is required to remove sediment trapped in navigation channel to maintain the required depth of channel. Maintenance costs vary from one harbour to another according to sediment volume and consume a considerable part of harbour income. So, sedimentation problem in navigation channel is considered a crucial issue according to economical and environmental point of view, which depends on geometric of navigation channel, hydrodynamic parameters and protection structures. Improvement of channel by deepening or widening the channel increases the sediment deposition. Also, improper design of protection structures made them insufficient. So many different solutions such as using open cycle pumping system or construct one way sand trap, extension of existing breakwater and changing orientation of channel were suggested to minimize sediment volume. However, Extension of existing breakwaters or using additional structures is considered the most practical solution that it is permanent, applicable alternative and doesn't need periodic cost. Damietta harbour on the northeastern of Nile delta in Egypt is a clear exampleof sedimentation problem, that navigation channel trapping a huge volume of sediment reached 2 million cubic meters per year, and requires high cost periodic maintenance. The conflict between recommended solutions and disadvantages of them prove that Sedimentation problem in Navigation channel of Damietta harbour needs more accurate study to find the proper way to solve the problem. Also, according to navigation channel improvement, these solutions either failed or had not examined. So, comprehensive study is needed to reach the optimum solution for the sedimentation problem ofDamiettanavigation channel problem especially in case of development.
Deep navigation channels have a great impact on adjacent beaches and crucial economic effects bec... more Deep navigation channels have a great impact on adjacent beaches and crucial economic effects because of periodic dredging operations. The navigation channel of the Damietta harbour is considered a clear example of the sedimentation problem and deeply affects the Northeastern shoreline of the Nile Delta in Egypt. The aim of the present study is to monitor shoreline using remote sensing techniques to evaluate the effect of Damietta harbour and its navigation channel on the shoreline for the last 45 years. Also, the selected period was divided into two periods to illustrate the effect of man-made interventions on the shoreline. Shorelines were extracted from satellite images and then the Digital Shoreline Analysis System (DSAS) was used to estimate accurate rates of shoreline changes and predict future shorelines evolution of 2030, 2040, 2050 and 2060. The Damietta harbour created an accretion area in the western side with an average rate of 2.13 m yr-1. On the contrary, the shoreline in the eastern side of the harbour retreated by 92 m on average over the last 45 years. So, it is considered one of the main hazard areas along the Northeastern shoreline of the Nile Delta that needs a sustainable solution. Moreover, a detached breakwaters system is predicted to provide shore stabilization at the eastern side as the implemented one at Ras El-Bar beach. Predicted shoreline evolution of 2060 shows a significant retreat of 280.0 m on average.
A series of laboratory experiments carried out to investigate wave screens influence on improveme... more A series of laboratory experiments carried out to investigate wave screens influence on improvement of submerged breakwaters efficiency which illustrated as a function of the transmission coefficient (Kt). Single and double horizontally slotted wave screens placed in seaward side of permeable rectangular submerged breakwater with different configurations to investigate geometrical parameters effect of wave screens on the transmission coefficient. The results of single screen showed that, the transmission coefficient (Kt) decreases as relative distance (Ws/d) between single screen and submerged breakwater increases. Also, when the porosity (P1) of wave screen decreases and relative submergence depth (dss/d) increases the transmission coefficient (Kt) decreases by about 5% and 4% respectively. For double wave screen the relative distance between submerged breakwater and the leeward side of double wave screen (Wd/d) and relative spacing (G/d) between the two wave screens have no significant effect on transmission coefficient (Kt). The wave screens improve the submerged breakwater efficiency by about (14 – 22 %) for the case study. The double wave screen showed better performance than single wave screen by about 8 %. Regression analysis used to develop equations predicting modified transmission coefficient (Ktm) for submerged breakwater fronted by single and double wave screens.
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