4. Conclusions
In this work, we develop a combined hurricane-circulation-inundation
model to quantify extreme coastal flooding induced by synthetic storms
under current and future sea levels in Shanghai, China. The main
conclusions are summarized as follows: 1) although the storm tide hazard
is high, Shanghai’s flood protection system is sufficient for preventing
majority of the city from severe flooding (> 100 years)
from storm tide under the current climate; 2) extreme “worst-case”
scenarios (> 5000 years) can generate unprecedented storm
tides (8 - 9 m) in Yangtze River Estuary or Hangzhou Bay, even under the
current climate; 3) future SLR will greatly increase Shanghai’s flooding
risk compared to the current state, with inundation two times and 20
times more likely to occur by mid- and late-21stcentury, respectively, and inundation depth and area to greatly
increases (e.g., 60-1360% increase in the inundation area for the
“worst cases” by 2100).
The present study contributes to a better understanding of extreme
coastal flooding from TC-induced storm tide and SLR in Shanghai and
unlocks the potential for estimating flood hazard evolution due to SLR
as well as storm change (e.g., Marsooli et al., 2019) in a changing
climate. The methodology is applicable to any coastal city that is
susceptible to TC surge flooding and rising sea level. However, since we
neglect wave effects on the water level, major seawall failure
mechanisms such as wave overtopping and breaching are not considered in
the present storm flood modeling; the inundation risk estimated herein
is likely a lower bound. Further work will include wave modeling and
dike reliability analysis (e.g., Yin et al., 2020) in the
climatological-hydrodynamic modeling to better quantify the flood risk
under both the current and future climate conditions.