Doubling of coastal flooding frequency within decades due to sea-level rise

Abstract

Global climate change drives sea-level rise, increasing the frequency of coastal flooding. In most coastal regions, the amount of sea-level rise occurring over years to decades is significantly smaller than normal ocean-level fluctuations caused by tides, waves, and storm surge. However, even gradual sea-level rise can rapidly increase the frequency and severity of coastal flooding. So far, global-scale estimates of increased coastal flooding due to sea-level rise have not considered elevated water levels due to waves, and thus underestimate the potential impact. Here we use extreme value theory to combine sea-level projections with wave, tide, and storm surge models to estimate increases in coastal flooding on a continuous global scale. We find that regions with limited water-level variability, i.e., short-tailed flood-level distributions, located mainly in the Tropics, will experience the largest increases in flooding frequency. The 10 to 20 cm of sea-level rise expected no later than 2050 will more than double the frequency of extreme water-level events in the Tropics, impairing the developing economies of equatorial coastal cities and the habitability of low-lying Pacific island nations.

Understanding epistemic uncertainty in large-scale coastal flood risk assessment for present and future climates

“…Finally, the selection of uncertainty sources can be deemed subjective, as with any nonexhaustive analysis (Uusitalo et al, 2015), and in the following paragraphs we try to underline the aspects which could be interesting for further investigation in future research. The accuracy of ESL projections is affected by the atmospheric and ocean model resolution (Cavaleri and Bertotti, 2004;Calafat et al, 2014) as well as including (or not) nonlinear interactions between ESL components (Arns et al, 2015) and waves in the analysis (Serafin and Ruggiero, 2014;Vitousek et al, 2017). Previous studies have further shown that ESLs can be over-predicted if the model does not consider shoreline retreat under SLR (Du et al, 2018;Idier et al, 2017;Pickering et al, 2017) or storm-induced inundation (Bertin et al, 2014).…”

Investigating compound flooding in an estuary using hydrodynamic modelling: a case study from the Shoalhaven River, Australia

“…A limitation of exposure to riverine flooding through an opening of Shoalhaven Heads appears to increase the tidal range as well as the exposure to storm tides and wave action. As this exposure to marine flooding drivers is likely to increase in the context of climate change and sea-level rise (Hinkel et al, 2014;IPCC, 2014;Vitousek et al, 2017), it should not be augmented by permanently opening the entrance.…”

“…An increase in sea level is expected to exacerbate storm-surge-related risks to coastal communities, because the frequency and extent of coastal flooding is likely to increase (IPCC, 2014;Vitousek et al, 2017). The impacts of a storm surge may further intensify when it coincides with a high spring tide (Pugh, 2004) and/or riverine flooding (Lewis et al, 2013a;Zheng et al, 2013).…”

Modelling Extreme Wave Overtopping at Aberystwyth Promenade

“…Therefore, suggesting coastal flooding events, such as the ones that occurred during the winter period of 2013-2014, are likely to become more frequent ( [4][5][6][7][8]). Being able to fully understand the extreme coastal flooding events that occurred during the winter period of 2013 and 2014 will help build understanding required for coastal flood forecasting, risk assessment, and hazard mapping.…”