SOLUTIONS PROPOSED FOR THE NAVIGATION PROBLEM DOWNSTREAM ZEFTA BARRAGES

Abstract

The Nile navigable Damietta branch extends between Cairo and Damietta open seaport on the Mediterranean. For safe navigation throughout the branch, a 2.30 m minimum flow depth (MFD) is required. A recovery project to improve the branch navigation was started in 1999 and completed in 2005. The project was to implement a 40 m wide navigable waterway. About 6.50 million m3 of bed materials had been removed from bottlenecks at $ 18.20 million cost. In 2003, the construction of a new lock of 150.0 m length, 17.0 m width and (1.50) m bed level was completed on Zefta Barrages (ZB) east side to meet the navigation requirements. The barrages are located at Km 119.625 downstream (D/S) El-Roda Gauge in Cairo. However, the resulting water stage (WS) D/S (ZB) during low discharges was insufficient to provide the MFD. Field studies were conducted to reveal the reasons. They found the branch flow carrying capacity had increased due to excessive dredging which caused a decline in WSs D/S (ZB). Analyzing the hydrologic and topographic conditions, two solution concepts were reached; either to raise the WS by 0.70 m or to lower the bed level of the diversion channel located D/S the new lock by 1.0 m. Therefore, this study aims to introduce solutions to overcome the problem. The solutions are to use a D/S rubber weir for raising the WS or construct a new lock within the D/S diversion channel for lowering the bed level or build new barrages with a new lock.