Quantification of the nonlinear interaction among the tide, surge and river in Pearl River Estuary

Abstract

The increase in storm surge and compound flood events caused by climate change exacerbates adverse effects on the estuaries. The ADCIRC + SWAN coupled model was simulated using various scenario simulations based on Super Typhoon Hato to quantify the nonlinear interactions of tide-surge-river during extreme events. The results reveal that three drivers, including (1) tide-surge phases, (2) typhoon tracks and wind speeds (3) upstream runoff, affect the extreme water levels by different nonlinear interactions. 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. The tide-surge nonlinear residual water level contributing to the extreme water level at high tide falling can reach 0.92 m. The nonlinear effects are exacerbated as typhoon wind speeds and upstream discharges increase. Peak water levels from the compound floods are more than 25% higher than storm surges alone at the river outlets. The nonlinear effects are mainly generated by the convection terms from the tide-surge-river interactions in the estuarine rivers.