Effect of nonlinear tide-surge interaction in the Pearl River Estuary during Typhoon Nida (2016)

Abstract. Storm surge is one of the most significant marine dynamic disasters affecting the coastal areas worldwide. An in-depth study of its mechanisms is crucial for improving forecasting skills and implementing better prevention measures. In this study, a numerical model based on the Advanced Circulation Model (ADCIRC) was used to investigate the characteristics of storm surges and the mechanisms of tide-surge interaction in the Pearl River Estuary (PRE) during Typhoon Nida (2016). Three different types of model runs were conducted to distinguish water level variations caused by astronomical tides, storm surges, and tide-surge interactions. The results indicated that storm surges are primarily modulated by tides through tide-surge interactions. The nonlinear effect is mainly generated by the nonlinear local acceleration term and convection term from the tide-surge interactions in the study area. However, they are predominantly governed by the nonlinear wind stress term and bottom friction term in shallow water regions such as the northern part of Qi’ao Island and Shenzhen Bay. Additionally, variations in the y component of the nonlinear momentum terms are more significant than those in the x component. To investigate the impact of tidal phase on surge response to Typhoon Nida, we altered the landfall timing to introduce variations in PRE characteristics. The results shows that the contribution ratio of each nonlinear term changes little, their magnitudes fluctuate depending on the timing of landfall.