Die Küste, 74 ICCE (2008), 31-44 
41 
nium scale, because long-term process such as sea-level fluctuations or neo-tectonics are the 
main driving forces there. Schwarzer and Diesing (2001) investigated the sediment dynam 
ics and geo-morphological changes on seasonal and annual scales in two different sandy 
nearshore areas of the south-western Baltic Sea. By using a new method called “tracer stick 
method”, they found a geographical variation of seasonal maximum mobility which moves 
offshore during the stormy winter conditions. However, the intense sediment mobility did 
not invoke substantial morphological changes in every case, especially with respect to sea 
sonality. 
3.3 Coast 
There are several types of coastlines along the south-western Baltic Sea. In general, Pleis 
tocene cliffs are alternating with Holocene barrier systems, mainly consisting of spits and 
lagoons. Large sections of these coastlines are retreating at an average rate of 0.2-0.3 m per 
year and maximum rates of up to 1.5 mper year (Schwarzer et ah, 2003; Ziegler and Hayen, 
2005). East of Rügen Island, the coastline turns towards a formation which looks as if equi 
librium conditions between erosion and accumulation predominate; however, even here the 
coast is eroding. Approximately 70 % of the coastline of the State of Mecklenburg-Vorpom 
mern, extending from Mecklenburg Bight to Oder Estuary, is under permanent retreat 
(Harff et ah, 2004). 
Natural sediment sources within the region are active cliffs and the seafloor, from which 
sediment is abraded (Schrottke, 2001). The erosion of the active cliffs is controlled by storm 
events combined with high water levels. The rate of retreat of the active cliffs of Schleswig- 
Holstein is 24 cm a~' on average (Ziegler and Hayen, 2005) and up to 30 cm a~' for the cliffs 
of Mecklenburg-Vorpommern. Schwarzer (2003) emphasizes that the nearshore processes 
have to be taken into consideration for a comprehensive understanding of coastal dynamics. 
The rates do not increase linearly with depth, but are highly dependent of the type of sub 
strate and wave dissipation. Material from cliff retreat and nearshore abrasion is transported 
by long-shore currents and is substantially involved in the formation of the Holocene barrier 
systems. Schrottke (2001) measured seafloor-abrasion rates of 2-5 cm a~' in water depths 
down to 6.5 m and at a distance from the shore of up to 300 m. In many cases, the amount of 
sediment supplied by seafloor abrasion is underestimated, sometimes completely neglected. 
Depending upon the composition of the Quaternary deposits and the exposure to the main 
wind and wave direction, such sediment supply can be of the same order of magnitude as the 
supply from the exposed parts of the retreating cliff (Schrottke and Schwarzer, 2006). 
4. References 
Ahrendt, K.: Entwicklung und Sedimenthabitus des Hörnum- und Vortrapptiefs. Meyniana, 44, 
1992. 
Ahrendt, K.: Ein Beitrag zur holozänen Entwicklung Nordfrieslands. Die Küste, H. 71, 2006. 
Antia, E. E.: Shoreface-Connected Ridges in German and U.S. Mid-Atlantic Bights: Similarities 
and Contrasts. Journal of Coastal Research, 12, 1996. 
Bayerl, K.-A.; Köster, R. u. Murphy, D.: Verteilung und Zusammensetzung der Sedimente im 
Lister Tidebecken. In: Gätje, C., Reise, K. (eds.). Ökosystem Wattenmeer, Springer, 1998. 
Berner, H.; Kaufhold, H.; Nommensen, B. u. Pröber, C.: Detaillierte Kartierung der Ober 
flächensedimente im mittleren und südlichen Nordfriesischen Wattenmeer. Meyniana, 
38, 1986.