Increased extreme coastal water levels due to the combined action of storm surges and wind-waves

The dependence between extreme storm surges and wind-waves is assessed statistically at the global scale using the outputs of two numerical models consistently forced with the same atmospheric fields. We show that 55% of the world coastlines face compound storm surge-wave extremes. Hence, for a given level of probability, neglecting these dependencies leads to underestimating extreme coastal water levels. Dependencies are dominant in mid-latitudes and are likely underestimated in the tropics due to limited capabilities of numerical models to simulate tropical cyclones. Furthermore, we show that, in half of the areas with dependence, the estimated probability of occurrence of coastal extreme water levels increases significantly when it is accounted for. Translated in terms of return periods, this means that along 30% of global coastlines, extreme water levels expected at most once in a century without considering dependence between storm surges and waves become a 1 in 50-year event.

MARCOS Marta;  ROHMER Jeremy;  VOUSDOUKAS Michail;  MENTASCHI Lorenzo;  LE COZANNET Goner;  AMORES Angel; 

2019-07-05

AMER GEOPHYSICAL UNION

JRC115871

0094-8276 (online),   

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL082599,    https://publications.jrc.ec.europa.eu/repository/handle/JRC115871,   

10.1029/2019GL082599 (online),