Abstract: The characteristics of the tidal and residual currents were investigated via the harmonic analysis based on the 31-day duration current observations at S station near the main channel of Tianjin Port. Effects of the local wind on the surface residual currents were explored in combination with the simultaneous wind velocities data. It is found that: (1)Tianjin Port belongs to the weak-current sea area, and the average velocity of the surface currents is about 31.4 cm/s. The current velocity generally decreases from the top to the bottom, and the main current direction is along the northwest-southeast. (2)The sea area is dominated by the regular semidiurnal tidal currents with a significant to-and-fro movement. The dominant tide component is M₂, and the shallow water tide is also remarkable over there. The flood currents velocities are larger than the ebb currents. (3)The average residual currents during the observation period are between 2.8 cm/s and 13.8 cm/s. The current velocity decreases as the depth increases, and the main current direction is along the northwest. The residual currents in the surface layer of the station are dramatically affected by the local wind, and the southeast wind shifts the residual currents to northwest.

Key words: Tianjin Port, harmonic analysis, tidal currents, residual currents