Modelling Coastline Change of the Darss-Zingst Peninsula with Sedsim - The Baltic Sea Basin - page 282

14.1 Introduction
Coastlines are changing through time and space, controlled by climate and
geological processes. Climate steers the hydrography, either by wind and storms
triggering waves and surges or by the thermal-adjusted mass balance between
continental ice and marine water. This overlaps with geological parameters, because
in times of transitions between glacials and interglacials a change of this balance
results in high magnitudes of glacioisostasy (Miettinen 2004 ) . Tectonics caused
by processes within the earth's interior are a morphogenetic factor too, influencing
the coastline shift. A quantification of coastline changes requires the combination
of data about isostasy and eustasy with digital elevation models. In a first step,
regional scenarios for the Baltic Sea, presented by Meyer ( 2003 ) and Rosentau et al.
( 2007 ) , take this into consideration. However, on a local scale sedimentary dynam-
ics like erosion, transport, and accumulation play an important role too (Lehfeldt
and Milbradt 2000 , Harff et al. 2009 ) . Therefore an extended approach for mod-
elling coastline change is required, integrating sedimentary dynamics with eustasy
and isostasy.
Here, this integration was accomplished by the modelling software package
Sedsim (Tetzlaff and Harbaugh 1989 , Martinez and Harbaugh 1993 ) . The program
simulates the behaviour of coastal sediments with respect to eustasy and isostasy
during geological and short time periods (Li et al. 2004 ) . Sedsim is a forward mod-
elling tool, depending on defined initial conditions. Before the implementation of
experiments for the geological past, in a first stage Sedsim was used for validation
experiments on the basis of recent initial conditions. With assumptions about the
development of the future sea level during the next 840 years (Voß et al. 1997 ) and
different parameter set-ups, various coastline scenarios have been calculated with
Sedsim. These experiments are located at the southern Baltic Sea coast, in the area
of the Darss-Zingst peninsula. This structure, shaped by longshore sediment trans-
port, is an excellent example for modelling as it is typical for many young Holocene
formations along the southern and southeastern Baltic Sea. The results of the mod-
elling are not predictive, instead they have to be considered as case scenarios. A
reasonable evaluation of the simulations is a precondition for modelling the past on
longer geological periods, based on reconstructed palaeo data sets.
14.2 Area of Investigation
The Darss-Zingst peninsula is located at the southern coast of the Baltic Sea
(Fig. 14.1 ) . It is part of Mecklenburg-Vorpommern, the most northeastern state
of Germany. The peninsula has an area of about 160 km 2 . The distance from the
Fischland in the west to the Bock Island in the east is 40 km on average, while the
north-south length is approximately 20 km. The elevation is very low with maxima
of 15 m in the Altdarss and Fischland areas. Generally, elevations of 0.5-2 m are
common. The surrounding water is also shallow with water depths not exceeding
4 m in the lagoons sheltered by the peninsula.