Impact of the interaction of surge, wave, and tide on the surge and wave on the northern coast of Vietnam for a marine storm surge and wave forecast system

The present study highlights the importance of the interaction of storm surges, waves, and tides in predicting surge and wave height in the operation of an early warning system on the northern coast of Vietnam through a series of numerical experiments amplifying typhoon intensity. First, the coupled model of surge and wave was validated by simulating the surge and wave of Typhoon Doksuri (2017). Then, we carried out a series of numerical experiments using the nine idealized typhoons, varying the drop rate of central pressures but keeping other parameters of the typhoon’s track, moving speed, and size. The results show that the storm surge becomes higher on the neap tidal condition, while it becomes lower on the spring tide. The storm wave gets higher on the spring tide. However, the behavior of the differences in the peak wave heights on the three tidal conditions is also similar to the storm surge. The tidal condition is highly distinguished in the heights of storm surges and waves under severe and super typhoons. The wave impact on the surge level and wave, considering the wave-dependent drag and the wave-induced radiation stress, amplifies the surge and wave heights as the typhoon intensity increases. In the neap tidal condition, the wave impact amplified the peak surge level to 1.4 m (32.7 %) along the super typhoon track compared to excluding it. In addition, the storm surge effect enlarges as the typhoon intensity increases, amplifying the wave height to 0.95 m (24.4 %) along the typhoon track on the spring tidal condition.