A comprehensive investigation of storm surge-induced urban flooding in Macao during Typhoon Hato in 2017

A comprehensive understanding of the processes of storm surge and flooding induced by typhoons is crucial for the development of effective emergency plans and risk management strategies. This study employed the three-dimensional coastal ocean circulation model FVCOM to simulate the storm surge in the Pearl River Estuary (PRE) during Typhoon Hato in 2017. In addition, the storm surge predictions are integrated with the InfoWorks 2D-1D hydrologic network drainage model to study urban flooding in the Inner Harbor district in Macao for the first time. Typhoon's wind and pressure fields were reconstructed based on parametric models, and numerical experiments were conducted to investigate the effects of tide-surge interaction. A thorough comparison between observed and simulated wind and water levels demonstrated a high degree of agreement. The results reveal that nonlinear tide-surge interactions are not uniformly distributed across the PRE. In the Lingdingyang waters, the impact of tide-surge interaction on the total water level ranges from 1% offshore to 30% upstream. In the coastal waters near Macao, this impact varies from 5% to 25%, with a peak impact of 25% observed near Hac Sa Bay in Macao, indicating a significant influence of tide-surge interaction in this area. Predicted city flood levels during HATO are well-validated against field data. The Inner Harbor of Macao is identified as the zone most severely affected by flooding induced by storm surge, with the highest flood depths recorded at its northern and southern ends.