INTERACTION BETWEEN TIDE AND STORM SURGE USING MIKE21 NUMERICAL MODEL

Tóm tắt

The study of the relationship between tides and storm surges is important for forecasting sea level rise during storms to support flood prevention and response in coastal areas. The paper focuses on assessing the existence of nonlinear tide-surge interactions. Observational water level data measured at the hydrographic station are used to calibrate the MIKE21 model. Boundary conditions are changed under different scenarios in order to simulate water level variations including pure tidal level fluctuations, wind-pressure-induced surge levels and the total water levels with various wind fields during Typhoon Washi occurring both earlier and later than in reality. Statistical results show that in Hon Dau with a tidal magnitude of about 3.6m, the storm surge peak tends not to coincide with high tide but occurs near low tide with increasing height, reaching its highest point within about 1 hour around low tide and its lowest point within about 3-4 hours after high tide. These results again confirm the existence of the nonlinear interaction between tides and storm surges. The maximum total water level is mainly influenced by tides and occurs near high tides, while the storm surge component caused by the wind pressure field varies in the opposite direction.