Nabil Ismail, Moheb Iskander, Walid El-Sayed


This paper presents an assessment of the performance of a shoreline revetment; M. Ali Seawall, placed to protect the land behind against flooding and overtopping at coastal site, within Abu Qir Bay, East of Alexandria along the Nile Delta coast. Coastal zone management of the bay coastline is of utmost significance to the protection of the low agricultural land and the industrial complex located in the rear side of the seawall under the current and progressive effects of climate change. The latest storm in December 2010, which hit the Nile Delta and which was the severest in the last decades showed that generated surges, up to 1.0 m as well as a maximum of 7.5 m wave height in the offshore of Alexandria presented a major natural hazard in coastal zones in terms of wave run up and overtopping. The storm, fortunately, resulted in a partial and modest flooding of the zone behind the seawall particularly in the beach segment, located in the middle of the seawall. This research project aims to the design review of the seawall which was first constructed in 1830 to protect the lowland agricultural area, 2.0 m below mean sea level, and was rehabilitated in 1981 as part of the Master Plan of the Nile Delta Coastal Zone Management. The seawall was further upgraded in 2009; one year before the 2010 storm. The paper will give an overview of the seawall design and its upgrades and the current conducted hydrodynamic analyses to estimate wave height distributions, wave run up and overtopping over the seawall and its beach segment. Use has been made of the in-house modified ImSedTran-2D model as well as universal design standards as EurOtop (2008). Based on the results for worst design scenarios, recommendations are given to increase the height of the seawall cap, to strengthen the beach top and back slope with a facility to drain storm water to increase coastal resilience behind the seawall. Comparison of the predicted overtopping with the observed wave overtopping volumes during the 8hrs-2010 storm, allowed the verification of the used universal design tools. Impact of precise estimate of storm and barometric surge as well as seawall armor roughness and shapes on overtopping rates are highlighted.


storm surges; coastal flooding; coastal resilience; seawalls; climate change

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