Land Subsidence and Coastal Changes in Vicinity of the City of Rosetta, Nile Delta, Egypt Using Integrated Satellite and Ground-Based Techniques.

Abstract

Rosetta is a port city of the Nile Delta, 65 km east of Alexandria. The village is distinguished by its geographical location as the estuary of the Nile River and on the shore of the Mediterranean Sea. It is also historically distinguished as the original site for the discovery of one of the greatest heritage pieces in the world, the Rosetta stone at the village of Burj Rashid, which is currently in the British Museum. The construction of the High Dam reduces the natural mud deposits cause of the sinking and erosion of the crust there and the city experience variable high rates of erosion with accelerated coastal area lost on the last two decades.  This makes this city is very sensitive to any sea level rise.    Thus, Rashid is one of the most vulnerable coastal cities to the effects of climate change.  The present study provides the contribution of the modernized geodetic and satellite techniques to take part into determination the effect of Mediterranean Sea level rise and land subsidence on the city of Rosetta. To reach the proposed objective the study utilizes   Global Navigation Satellite System (GNSS), tide gauges and satellite altimetry and gravity data. GNSS data has been used to determine the rates of the horizontal and vertical movements of the studied region   and linking the rates of vertical movement of the Delta to the temporal change of the sea level variation of the Mediterranean Sea by tying GPS measurements to tide gauge data. On the other hand, determination of temporal local and regional sea level variation of the southern part of the Mediterranean Sea using tide gauge and satellite altimetry data. Finally, total mass variation and the tectonic settings of the shore line features has been figured out using recent satellite gravity data.   Permanent GNSS network along the Nile Delta shows variable rates of land subsidence, with the subsidence rate of the studied area of about 6mm/y. Satellite altimeter data together with tide gauge data confirm the Sea level rise acceleration on this region with an acceleration of about 7mm/y.  On the other hand, the selected region shows complicated pattern of mass variation, land subsidence and Sea Level Rise. Therefore, impact of climate change may be the biggest challenge in this region. On this context, accurate monitoring on the land subsidence and the sea level rise is of great importance to the climate change mitigation and the protection of this city.