XVIII IWRA World Water Congress Beijing China 2023
Sub-theme 3: Building Resilience for Disaster Prevention and Mitigation
Author(s): Mr. Shikun Hu, School of Civil Engineering,Sun Yat-sen University
Mr. Shikun Hu, School of Civil Engineering,Sun Yat-sen University
Co-author(s): Prof. Bingjun Liu, School of Civil Engineering,Sun Yat-sen University, Mr. Zhinghong Deng, School of Civil Engineering,Sun Yat-sen University
Keyword(s): Coastal flood, Storm surge, Pearl River Estuary, Tides
Oral: PDFAbstractThe increase in coastal flood events caused by climate change exacerbates adverse effects on the estuaries. In order to obtain more accurate maximum water level forecasts and better defenses of seawall and riverbanks, it is necessary to study the existence of nonlinear effects among the drivers including the tide, typhoons and streamflow. ADCIRC+SWAN coupled model was simulated using various scenario simulations based on Super Typhoon Hato to quantify the nonlinear interactions of tide-storm-runoff during the storm surge. The results reveal that the three divers, including different (1)tide-surge phases, (2)typhoon tracks and wind speeds (3)upstream runoff, affect the extreme water levels. The tide-surge nonlinear effects contribute to the extreme water level at high tide falling but decrease at rising with 0.92m and -0.09m, respectively. Changes in tide-surge phases remain the most constructive factor controlling nonlinear effects, with the maximum contribution exceeding 50.46% of the extreme water level. As typhoon wind speeds intensify and upstream runoff flows increase, the nonlinear effects are amplified. Even at the river outlets, peak water levels from the compound floods are more than 25% higher than storm surges alone.The risk of coastal flooding increases with the interaction of storm surges and estuarine river systems. Therefore, it is essential to quantify and analyze their interactions during coastal compound floods.In addition to using the nonlinear water level to quantify the nonlinear impacts among the multi-drivers, the nonlinear indicators can be derived according to the distinct physical processes in the momentum equation to explain the nonlinear interactions further. Nonlinear effects are mainly generated by the convection terms from the tide-surge and upstream flood interactions in the estuarine rivers.Our simulations reveal that the convective term of multi-drivers in the river channels is the source of the nonlinear effect that is enhanced under compound flooding.The primary source of the nonlinear effects within the river network is the combined effects of the velocity of the tide, river inflow and surge.