The effect of nonlinear factors on tide-surge interaction: A case study of Typhoon Rammasun in Tieshan Bay, China

Abstract

The interaction of tides and storm surges can significantly modify the final levels reached by storm surges that threaten coastal areas. In this paper, numerical experimental results are presented that examine tidal influence on storm surges. This is done using a two-dimensional ADCIRC (Advanced Circulation Model) applied to the effects of Typhoon Rammasun (July 2014) on Tieshan Bay, China. The results show that, without considering tidal forcing, there is an underestimation of positive surge levels, while negative surge levels are overestimated. It is also shown that the prevailing wind direction and shape of Tieshan Bay affect the distribution of storm surges. The nonlinear residual levels caused by tide-surge interaction can reach 0.94 m at the top of the bay when peak negative storm surge levels occur, with nonlinear levels increasing from the outside to the head of the bay. Through the derivation of mathematical terms, a direct relationship between the nonlinear residual levels and the dynamic influencing factors is established. Further, it is demonstrated that the combination of wind stress and bottom friction terms and advection terms play leading roles in the derivations, whereas terms related to local acceleration and Coriolis force contribute little to the nonlinear levels. The combination of wind stress and bottom friction terms and advection terms show complex spatial and temporal variation.