Author(s): Nabil M. Ismail
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Keywords: No Keywords
Abstract: The aim of this research project is to determine coastal processes contributing to the impacts associated with seawall-hard structures which are placed to mitigate coastal erosion on river delta coastlines. The prime case study addresses the seawalls constructed in 1990 at the Rosetta headland in response to the severe modifications and retreat of the Nile delta coastline after the operation of the Aswan High Dam in1964. The analysis was conducted on the basis of the field data of the morphological changes of the delta coastline. Use has been made of recent satellite remote sensing data for the Rosetta headland in 2005,2007 and 2009 and the results of the numerical prediction of GENESIS. Further, the study attempts to identify the spatial extent of the coastline reshaping as a prerequisite to successful coastal zone management. The analysis of the field data indicated an increase of scour depth and increases of the long shore and offshore sediment transport rates in front of the seawalls. A semi-theoretical estimate of the cross shore sediment transport rate at the seawall was obtained and confirmed by field data. Furthermore scale analysis of hydrodynamics of the combined river-wave flow yields a wave-current momentum index for the expected reshaping length scale of the coastline after seawall construction.
Year: 2009