Evaluation of sea-level rise influence on tidal characteristics using a numerical model approach: a case study of a southern city coastal area in Vietnam

The regional dynamics of the coastal area in Ho Chi Minh City affected by the river and sea hydrodynamic factors are incredibly complex. These factors such as tides, waves, and river flow strongly influence the process of accretion-erosion in both estuary and coastal areas. In this study, the characteristic changes in four main tidal constituents (K1, O1, M2, and S2) influenced by sea-level rise are investigated using a numerical model in the curvilinear coordinate system. The 2050 and 2100 sea-level rise scenarios are considered to evaluate the change in tidal harmonic constants and tidal ellipses. The results show that the amplitude of the four constituents significantly increases; however, there is a declining trend in the tidal phase for both the 2020 and 2100 scenarios. As the highest value in amplitude, the M2 constituent indicates that the tidal regime is the dominant semidiurnal tide in the study area. Despite a smaller amplitude than the M2 constituent, K1 has a higher value than both the O1 and S2 constituents. Tidal ellipses in the study area indicate the orientation of the major axes parallel to the shoreline, and the offshore axes that move clockwise are more circular than those in the river mouth. The strongest semidiurnal M2 velocity of ellipses in the Dong Tranh Gulf ranges from 0.6 to 0.7�m/s in 2020 and records an increase of 0.046�m/s in 2050 and 0.082�m/s in 2100. Most tidal ellipse velocities gradually increase under the influence of sea-level rise in 2050 and 2100. � 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.