Coinciding storm surge and wave setup: A regional assessment of sea level rise impact

Coastal locations around the world face the multifaceted challenge of rising sea levels, posing threats to coastal communities, particularly during storm surges and high wave conditions. We have examined the dynamics of sea-level fluctuations along Denmark’s coastline, with focus on wave-induced phenomena, such as wave setup. We analysed wave data from DMI’s operational model spanning from 2006 to 2022, as well as climate projections that extend until the middle of the 21st century. We conducted an analysis of the 2% exceedance of the significant wave height maxima during specific time frames (denoted “storm days”) and “storm surge conditions” (the maximum sea level within a 30-year period). We found that the impact of climate change on extreme wave events was insignificant when focusing solely on the wave component, but heightened wave setup during “storm surge conditions” along the north-western coasts of Jutland. In this area, there is a notable increase in wave setup due to longer swells, ranging from 5 to 10 cm, by the mid-century, which is double the current wave setup in the region. Interestingly, other parts of the country did not show significant changes in wave setup. This regional variation highlights the nuanced impact of wave-induced processes on sea level dynamics and underscores the need for tailored adaptation strategies targeting specific vulnerable zones.