Responses of wave and storm surge induced by the extreme tropical cyclone Hato (1713) to sea level rise in shelf–bay–channel multi-scale domains

This paper presents an example of investigations on the responses of extreme tropical-cyclone-induced wave and storm surge to projected future sea level rise in shelf–bay–channel multi-scale domains. A tide–surge coupling hydrodynamics model and a surface wave model, both using the same computational grid with a high spatial resolution, are developed individually and applied to respectively simulate the storm surge and typhoon wave in a shelf–bay–channel multi-scale domain refining from South China Sea to narrow coastal channels around Macao in the west of Pearl River Estuary. The computational grid has a spatial resolution gradually refining from about 14 km at the open boundary to a highest value of 30 m in the coastal channels around Macao. The Super Typhoon Hato (No. 1713), which has caused catastrophic losses, is considered as an example of extreme tropical cyclone events. The models are well validated and applied to simulate the changes of Hato-induced wave and storm surge in four pre-defined sea-level-rise scenarios. In the four scenarios of sea level rise, the peak height of Hato-induced wave enlarges linearly with the rising sea level in most of the multi-scale domains, notably along the shelf open coasts and bay outlet. In contrast, the peak surge varies insignificantly along the bay outlet and even decreases remarkably in a quadratic function within the narrow channels. These findings suggest that the contribution of waves to extreme sea levels during tropical cyclones may intensify if the mean sea level rises and it varies in shelf–bay–channel multi-scale domains, which should be carefully taken into consideration in coastal hazard assessments.