Tidal Dynamics Analysis of the Positive Feedback Mechanisms in Compound Flooding

When two or more weather extremes occur at the same time or in close succession, the magnitude of the caused flooding event was found disproportional to the superposition of the individual ones and this phenomenon, which raises a rising concern in recent years, is named compound flooding. Researchers have attempted to address the issue by analyzing the capacity reduction of the drainage system, the saturation of the soil moisture, the storm surge magnitude, etc, but the mechanism that compound event triggers the change of the tidal dynamics has not been fully elucidated to the author's knowledge. Here, we develop an analytical framework for the estuary dynamics and enforce a storm surge and a high river discharge, separately or combined, through the boundary conditions and applied to an idealized estuary. The study is targeted at analyzing the nonlinear positive feedback mechanism in the tidal dynamics to reveal the deep cause of the exacerbated compound flooding effect. The analytical results will be validated against a numerical model. More details will be reported in the presentation.