How Winter Storms Shape the Baltic Coast: Small Washover Fans in the Gulf of Gdańsk

What is it about?

Strong winter storms can push seawater over beaches and dunes, leaving behind thin layers of sand known as washovers. Although these features are small, they record past flooding events and reveal how coasts respond to extreme weather. We studied two protected sites on the southern Baltic Sea coast, Poland. Using historical aerial photographs, modern drone mapping, and ground-penetrating radar, we documented more than 240 small washover fans that formed during storm surges over the last 15 years. Our measurements show that even modest storms can transport sand far inland and create deposits that follow predictable size–shape relationships. The internal layering of these deposits reveals how water and wind moved the sand during and after each storm. We also compared the timing of washover formation with long-term climate records and found links to natural shifts in North Atlantic weather patterns.

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Photo by Annie Spratt on Unsplash

Photo by Annie Spratt on Unsplash

Why is it important?

Understanding these small storm-driven landforms matters for two reasons. First, they are natural archives that help scientists reconstruct past flooding and improve forecasts of future coastal hazards. Second, they highlight how beaches and dunes can remain resilient: the same storms that erode the coast also rebuild it by moving sand inland. By monitoring washover growth, managers can detect early signs that a shoreline is losing its ability to recover from storms. This research demonstrates that even low-energy, semi-enclosed coasts such as the Gulf of Gdańsk are shaped by powerful but infrequent storms—and that their subtle sandy deposits can reveal the history and future of coastal change.