Spatial Analysis of Sea Level Rise in Egypt's Northern Coast and Its Influence on the Geodetic Vertical Datum

Globally, the rise of sea level has become a well-known accepted fact due to the global warming associated with the climate changes. The development of costal areas requires information on the sea level rise in terms of magnitude and rate. Additionally, the mean sea level is of a specific interest to the geodetic and surveying communities since it represents the vertical geodetic datum for heights. A tide gauge dataset has been built by the Egyptian authorities containing tide measurements at several locations in the northern coasts of Egypt. The data have been analyzed, both statistically and spatially, in order to estimate and map the lateral variations of sea level over the Egyptian coasts. It has been found that the mean sea level rises westward as moving from Port Said to Alexandria. Geographic Information System (GIS) technology has been applied for the spatial analysis of the sea level variations, and surface and contour maps have been developed. It is recommended that the developed maps should be applied in any future study for estimating sea level rise hazardous impacts. Such procedures will produce more reliable judgment of this phenomena of the climate changes. Additionally, the variations of mean sea level both in time and in space should be considered, and hence a new precise definition for the national vertical geodetic datum should be carried out. This re-definition is fundamental for accurate surveying and mapping activities in Egypt. Main tasks of this modernization process are proposed.