Key Points:
  1. An integrated statistical-hydrodynamic method is developed to estimate tropical cyclone-induced coastal flood inundation hazard.
  2. The mainland Shanghai is found to be well protected by high-standard seawalls.
  3. However, Shanghai is expected to be increasingly at risk due to future sea level rise.
Key Words: Topical Cyclone, Storm Tide, Inundation, Sea Level Rise, Flood Protection, Shanghai
Plain Language Summary: Coastal flooding associated with tropical cyclones (TCs, also called typhoons in the Northwest Pacific Basin) is often the most devastating and costliest of natural hazards. Struck by a number of strong TCs in recorded history, Shanghai may be highly vulnerable to coastal flooding due to its location within the Yangtze River delta, low-relief topography and high-density population. However, given the limited historical data, observation-based analysis is insufficient to capture the potential extreme events. In this study, we use a synthetic storm model to generate large numbers of TC events that are physically plausible but may have never occurred in the past. Storm tide and the resultant coastal flooding induced by each TC are further simulated with a coupled circulation-inundation model. Results suggest that Shanghai may encounter extreme storm tide flooding with very low possibilities under the current climate condition. With the protection of seawall, the city is generally immune to extensive flooding, except the low-lying and poorly-protected coastal floodplain and estuarine island, Chongming. However, future sea level rise will induce a significantly increased flood risk in Shanghai over the 21st century.