Storm surge hydrographs from historical observations of sea level along the Dutch North Sea coast

This study provide insight into the characteristics and temporal patterns of historical storm surge events along the Dutch coast. The analysis focused on detecting storm surge events using two different thresholds: the 70th percentile (POT70, 0.08-0.10 m) and the 99th percentile (POT99, 0.8-1.1 m).

Some of the key findings from the study are as follows:

• Comprehensive analysis with POT70: POT70 allowed for a more detailed analysis, effectively identifying multi-peak events, while POT99 focused on peak surges but often missed crucial pre- and post-storm activities. This distinction underscores the importance of considering a broader range of surge characteristics in coastal management and impact assessments.
• Flexibility of POT70: The initial classification of POT70 provides a versatile library for surge analysis, allowing researchers to adjust thresholds and refine event selection to other study objectives.
• Two-peak events: Two-peak events were notably common, with the second peak occurring about two days after the first, often coinciding with low or rising tides.
• Regional variability: The northern stations experienced stronger surges than those in the south, as indicated by the wider range of event durations and higher values of surge peak magnitudes observed in the north.
• Surge complexity and variability: The findings highlighted the complex and variable nature of storm surge patterns along the Dutch coast, even though some degree of judgment was applied in the classification process.
• Challenging traditional hydrographs: The new approach challenges the traditional triangular hydrographs, which may oversimplify surge dynamics. This is especially important as climate change introduces new uncertainties.