The rate of dunes erosion on the Southern Baltic Sea coast under the influence of the Marie and Nadine double storm in January 2022

The paper discusses the conditions for development and the course of the double storm surge caused by the Marie and Nadine cyclones in January 2022. Smaller surges that preceded the main large one have also been presented. The volume of coastal dune erosion caused by storm surges, including the sea level height and wave run-up were analysed, as was the influence of the ratio of beach height to run-up and the volume of dune erosion. The results were obtained based on field measurements of the changes in the morphology of the coast and the waterfront on various sections of the Polish coastline. The dune retreat after selected surges was calculated. The largest dune erosion occurred after the Marie and Nadine storms. The maximum sea level was 1.28 m AMSL. At that height, the water run-up on the coast reached 3-3.2 m AMSL. Mean erosion, defined as the retreat of the dune base, was 4.3 m. However, it was higher in sections where the beach was lower than the water run-up during surges and ranged from 4 to 8 m. Dune erosion reaching up to 8 m occurred on so-called cape sections, where the direction of the coastline changes. The factors that influenced the volume of dune erosion were the different levels of the sea and run-up, as well as the coast’s exposure to waves and the beach height.