Risk assessment of coastal flooding disaster by storm surge based on Elevation-Area method and hydrodynamic models: Taking Bohai Bay as an example

The future inundation by storm surge on coastal areas are currently ill-defined. With increasing global sea-level due to climate change, the coastal flooding by storm surge is more and more frequently, especially in coastal lowland with land subsidence. Therefore, the risk assessment of such inundation for these areas is of great significance for the sustainable socio-economic development. In this paper, the authors use Elevation-Area method and Regional Ocean Model System (ROMS) model to assess the risk of the inundation of Bohai Bay by storm surge. The simulation results of Elevation-Area method show that either a 50-year or 100-year storm surge can inundate coastal areas exceeding 8000 km²; the numerical simulation results based on hydrodynamics, considering ground friction and duration of the storm surge high water, show that a 50-year or 100-year storm surge can only inundate an area of over 2000 km², which is far less than 8000 km²; while, when taking into account the land subsidence and sea level rise, the very inundation range will rapidly increase by 2050 and 2100. The storm surge will greatly impact the coastal area within about 10–30 km of the Bohai Bay, in where almost all major coastal projects are located. The prompt response to flood disaster due to storm surge is urgently needed, for which five suggestions have been proposed based on the geological background of Bohai Bay. This study may offer insight into the development of the response and adaptive plans for flooding disasters caused by storm surge.