Investigation of sea level variations in Antalya-I (1935-1977) and Antalya-II (1985-2005) tide gauge stations

In the countries, having seashores, sea level measurements conducted at the tide gaugestations run for practical and scientific purposes are also commonly used in the field ofgeodesy in addition to oceanographic applications. Sea level changes constantly due tothe factors like climate (pressure, temperature, wind, etc.), orbital movements, (theperiodic inflections of the moon and the sun), the melting of glaciers, and tectonicmovements. It is estimated that while global sea level increased 10-20 cm in the lastcentury, and the increase will be 40-60 cm in this century. In the light of theseestimations, the flooding risk of the residential areas at the seashores is important in termsof socioeconomic point in the countries having seashores. Determination of sea levelchanges is also important for the datum of the vertical control networks of countries.In this study, the validation of ANTALYA-I and ANTALYA-II tide gauge stations wascarried out by scientific methods, and seasonal and long-term sea level changes werestudied, using hourly sea level data. Average sea level and velocity with seasonal changes(annual and semi-annaual) were calculated by the Least Square Method, an equation ofwhich the mathematics model is a harmonic function. In this study, where the data ofANTALYA-I and ANTALYA-II tide gauge stations were analysed both seperately andtogether, the average sea level velocity of ANTALYA-I (1935-1977) tide gauge stationwas found 1.00 ± 0.3 mm/year and that of ANTALYA-II (1985-2005) tide gauge stationwas measured 4.4 ± 0.7 mm/year. As a result of combined analysis of both station?sdata, it was found that average sea level velocity belonging the years 1935-2005 was 0.2± 0.1 mm/year.Keywords: Tide gauge station, sea level variations, tide, trend, harmonic analysis.