Dredging as a tool to enhance river transport in Damietta branch was conducted since 1999. About six million meter cubic of bed material was removed with a total cost of 60 million Egyptian pounds. The navigation channel has an average width of 40 m. However, the last 12 km of the route to Damietta port is via an artificial canal of water depth of 4 m and channel width of 40 m at bed level which is sufficient for two way traffic for container vessels. The waterway design specification has guaranteed a minimum water depth for navigation of 2.3 m for uninterrupted period of 365 day a year. A navigation hazards represented by a drop in the design water level was evident in 2006. The drop of water level was threatening the satisfaction of 2.3 m water depth in some days within the year. This was attributed that the channel carrying
capacity was increased after the dredging process. This study aims at improving the navigation condition downstream Zefta barrage, Damietta branch by installing permanent regulation structure such as weirs. The
weirs will enhance heading up of water in the weir back water zone to solve some of navigation bottlenecks.
A one dimensional mathematical model (SOBEK) was used to simulate a study reach of 134 km downstream Zefta. Low discharge of 3 mm3/day is used as critical cases to represent a number of bottleneck locations of 165 and 75 respectively. The weirs are simulated in three locations according to the intensity of
the bottlenecks. Different crest level for the weirs is tested. The number of simulated cases is twelve. The model enables the simulation of the hydraulic structures along the branch such as Zefta and Damietta barrages. The study concluded that the weir installation has resulted in solving some of navigation bottlenecks vary between 22 to 88%. The study recommended to combine between different regulation
work (dredging and weir installation) to get the best results from the economical point of view. Ship transport activity can be put off when the required water depth is not available. Specific type of ships with less draft can also be used during the hazard periods. The clearance can be less than 0.5 m according to the
environmental conditions and the number of ships in the waterway.
Key words: Navigation, dredging, permanent structures, Weirs, navigation hazards, Damietta, and mathematical model |
