DATE2018-04-09 01:11:15
AUTHORSM Said (1), T El-Geziry (2)
  1. National Institute of Oceanography and Fisheries, Alexandria, Egypt
  2. National Institute of Oceanography and Fisheries, Alexandria, Egypt
ABSTRACTThe present work is based on hourly sea level data taken from six tide-gauges distributed over the Egyptian Mediterranean coast. The periods of data are different for each location with the longest records (30 years) at Alexandria and the shortest records (4 years) at Mersa Matruh. These data are used to calculate the tidal characteristics, spatial variations of the mean sea level, annual rates and its seasonal variations. The astronomical tidal constituents are calculated using t_tide package which works under the Matlab Environment. The present study focused only on the 12 major tidal components. Despite the weakness of the observed astronomical tides along the coast, the M2 constituent is still the key player in the observed variations in the astronomical tides. Tides are of semidiurnal type with a maximum M2 amplitude value of 13 cm at Port Said and a minimum one of 6 cm at Sidi Abdel-Rahman west of Alexandria. The results of the present study revealed that, the highest HHWL occurred at Port Said (87 cm) and the lowest LLWL occurred at Mersa Matruh (23 cm). The mean sea level along the coast increases from west to east with a difference of 35 cm between its western and eastern extremities. The sea level rate is varied between a minimum of 1.0 mm/yr in the west and a maximum of 6.4 mm/yr in the east with an average rate of 3.4 mm/yr. This rate is higher than the rates of the global and whole Mediterranean basins and is less than the rate of the eastern Mediterranean. Moreover, the rate of sea level rise is higher eastern region than the western region. The sea level examines a seasonal trend with usual low values in spring season and high ones in summer. The seasonal variations tend to be mostly affected by the air pressure scheme and wind regime over the study area. Land subsidence is another factor, which must be considered upon investigation of sea level variability along the Egyptian Mediterranean coast. However, this needs to be verified and concluded through more robust actual geological observations and analyses