Risk of compound flooding, which can result when rapid sea level rises associated with storms occur along with heavy rains, is currently concentrated along Mediterranean countries but will greatly increase for Northern European in the future as the climate warms, according to a new modeling study. This is the first study of compound flooding to consider future changes that could result from combined geographic shifts in precipitation, storm surges, waves and tides. The hazard of compound flooding is not usually included in coastal flooding risk analyses, even though storm surges and extreme precipitation runoff are related. What's more, coastal cities are expected to further grow in the coming decades, underscoring an urgent need to assess future compound flooding probability - which other analyses have overlooked. E. Bevacqua et al. modeled the probability of high sea levels and heavy precipitation occurring simultaneously along European coasts both in the present and under a future business-as-usual climate change scenario. Assuming a warmer future climate, the researchers found the probability of compound flooding risk is likely to increase heavily along the west coast of Great Britain, northern France, the east and south coast of the North Sea, and the eastern half of the Black Sea. The Bristol Channel and the Devon and Cornwall coast in the UK, as well as the Dutch and German North Sea coast, are considered hot spots, with compound flooding events likely to occur more than once every six years. The threat is even worse near Noorderzijlvest in the Netherlands, where the compound flooding risk is expected to triple, and around Bergen on the Norwegian coast, where it may increase by fivefold.
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Science Advances