Assessment of natural coastal hazards at Alexandria/Nile Delta interface, Egypt

Recent in situ fine-grid waterfront survey integrated with inland elevation, nearshore depth soundings and wave data are incorporated into procedures for determining natural hazards, which are prevailing or expected at Alexandria/Nile delta interface on the Mediterranean Sea of Egypt. The hazards being assessed include wave runup height, inundation distance, rates of sea-level rise and shoreline change rate. The lateral variation of the hazard values along similar to 133.8km which is the total length of the study coast helps with identifying six low-lying vulnerable spots with different potential hazards. Three vulnerable spots [2.3-2.5 m above mean sea level (msl)] are identified at Alexandria, specifically at the Eastern Harbor, Lauran and Mandara-Montaza beaches. In addition, three other low-lying spot areas are distinguished at Idku resort beach (1.0-1.5 m above msl) and on both sides of the western and eastern flanks of the Rosetta Nile promontory (1.0-1.2 m above msl). Detailed analysis of spatial and cross-shore transects generated from near shore/land elevation map marks contrasting elevations that vary from low-lying (- 3 m below msl) to high elevated carbonate ridges parallel to the shore (similar to 20 m above msl). The high-elevated coastal ridges underlying Alexandria's seafront-maximum elevation of 12 m above msl-in addition to other protection elements are acting together as a natural quasi-barrier to mitigate sea flooding that may in turn affect the historical low-lying depressions located east and southeast of the city.

Automated summary

An integrated survey incorporating fine-grid waterfront data, inland elevation, nearshore depth soundings, and wave data was conducted to assess natural hazards prevalent or anticipated at the Alexandria/Nile delta interface in Egypt. The study identified six low-lying vulnerable spots based on hazard values, with three spots in Alexandria and three in other areas along the coast. The analysis also showed contrasting elevations from low-lying areas to high coastal ridges that act as a natural barrier against sea flooding in Alexandria.