The article summarises results of studies conducted along the Baltic Sea sandy coasts by scientists involved in coastal dune research, and presents an attempt to describe the types and distribution of dune coasts. The Baltic Sea coasts feature lower and higher foredunes. The lowland behind the coastal dune belt is covered by wandering or stabilised inland dunes – transgressive forms, mainly parabolic or barchans. The source of sediment for dune development includes fluvioglacial sands from eroded coasts, river-discharged sand, and older eroded dunes. Due to the ongoing erosion and coastal retreat, many dunes have been eroded, and some are withdrawing onto the adjacent land. There are visible differences between the south-eastern, western, and northern parts of the Baltic Sea coast with respect to dune development. The entire southern and eastern coast abounds in sand, so the coastal dunes are large, formerly or currently wandering formations. The only shifting dunes are found at the Polish and the Russian–Lithuanian coasts on the Łebsko Lake Sandbar as well as on the Vistula and Curonian Spits. The very diverse shoreline of the south-western coast experiences a scarcity of larger sandy formations. Substantial parts of the Baltic Sea sandy coasts have been eroded or transformed by humans. The northern part of the Baltic Sea coast features mainly narrow and low sandy coasts (e.g. in Estonia). Further north, sandy dunes are virtually absent.

The Polish coast is a non-tidal area; its shores are affected mainly by autumn-winter storm surges. Those of 6 and 14 January 2012 are representative of the forces driving the erosion of normally accumulative sections of coastal dunes, monitored by the author since 1997. The sea level maximum during these two storm surges reached 1.2 to 1.5m amsl along the Polish coast. Land forms up to 3m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12days. Quantitative analyses of the morphological dynamics of the coastal dunes are presented for 57 profiles located along the coast. Only those accumulative sections of the Polish coast are analysed where sand accumulation did occur and led to new foredune development. The mean rate of dune erosion was 2.5m3 per square metre with an average toe retreat of 1.4m. Erosion understood as dune retreat was greater when a beach was lower (correlation coefficient 0.8). Dune erosion did not occur on coasts with beaches higher than 3.2m or on lower ones covered by embryo dunes

Zarys treści: Na podstawie pomiarów morfologicznych klifu i plaży oraz dokumentacji fotograficznej ustalono współczesne tempo erozji klifu w miejscowości Trzęsacz w latach 1997-2017. Zarejestrowane zmiany geodynamiczne klifu powiązano z cyklicznymi czynnikami sprawczymi: spiętrzeniami sztormowymi i opadami deszczu. Ponadto przedstawiono historyczne zmiany morfodynamiczne klifu i niszczenia kościoła w oparciu o dostępne publikacje, mapy i fotografie. Od 2003 r. ruinę chroni ścianka szczelna z gabionów-klif w tym miejscu jest nieaktywny. Od 2010 r. podnóże klifu Wybrzeża Trzebiatowskiego od Niechorza do Trzęsacza osłonięte jest opaską, to zatrzymało znaczną erozję rejestrowaną na całym odcinku do 2009 r. Ustalono, że zabieg ten nie chroni przed cofaniem krawędzi klifu, wynoszącym do 0,1 m a-1 tuż przy ruinie kościoła. Na ostatnim 200-stu metrowym odcinku bez opaski średnie tempo cofania krawędzi wynosi 0,4 m a-1 .

Based on observations spanning 21 years (2000–2020), the article studies the effects of storm surges on the shore of the Świna Gate Sandbar in the southern part of the Pomeranian Bay (southern Baltic Sea). Impacts of selected maximum storm surges in each year were assessed with respect to morphological data collected on the beach and the foredune. The data included parameters of beach-dune erosion as measured along a beach transect before and after each surge. Differences and trends in the shore erosion were related to the sea level (SL), duration of a storm surge [highest storm sea level (H_SL) > 1 m], wind-wave sector and wave run-up. The relationships were explored using a simple correlation analysis. The most serious erosion was observed during the heaviest surges [H_SL > 1.3 m above the mean sea level (AMSL)], with a wave run-up higher than 3.2 m AMSL. Such surges occurred at about 2-year intervals. The average SL during a surge was 1.2 m AMSL, with a run-up of 2.6 m AMSL. The beach and the lower part of the shore, below that level, were eroded each year. The heaviest surges resulted in an average 5.2 m and 7.0 m dune retreat on the high-beach-accumulative shore and on the low-beach-erosive shore, respectively. The dune was not eroded when the beach height exceeded the wave run-up. The heaviest surges eroded away 12–14 m³ of the beach sand volume. The shore erosion was found to be related to the storm surge duration, the maximum SL, the run-up and the beach height prior to the surge.