Climate change exerts a significant influence on terrestrial and aquatic environments on a global scale. The ongoing global warming has increased sea levels, raising concerns about potential alterations to the characteristics of tides, waves, and ocean currents in coastal regions. This research employs a harmonic analysis framework and uses three distinct methods—Simple Moving Average (SMA), Empirical Mode Decomposition (EMD), and Ensemble Empirical Mode Decomposition (EEMD)—to scrutinize the phenomenon of sea-level rise (SLR). The simulations conducted in this study reveal that the estimated SLR, as determined by SMA, has an approximate value of 17.677 mm/year, occurring alongside an average SLR rate of 0.982 mm/year. EMD analysis yields an SLR estimate of around 54.878 mm, with a computed mean annual SLR of 3.049 mm/year. Applying EEMD results in an estimated SLR of roughly 57.730 mm, with a computed mean annual SLR of 3.207 mm/year. Among these methods, the EEMD analysis identifies the highest SLR, reaching 57.730 mm.