Geoscience Reference
In-Depth Information
Chapter 7
Coastlines of the Baltic Sea - Zones
of Competition Between Geological Processes
and a Changing Climate: Examples
from the Southern Baltic
Jan Harff and Michael Meyer
Abstract
Relative sea level change is, besides the geological buildup and hydro-
graphic parameters, the main controlling factor in shaping the coastlines on the
centennial timescale and beyond. Vertical displacement of the earth's crust and
eustasy serve as main components driving the relative sea level (RSL) change dur-
ing the Quaternary. Whereas the eustatic change mirrors mainly climatic factors,
the vertical displacement of the earth's crust has to be regarded in former glaciated
areas as a result of glacio-isostatic adjustment superimposed by the regional tec-
tonic regime or land subsidence due to local factors. A simple model is applied
to reconstruct the palaeogeographic development of a coastal area and to generate
future projections as coastline scenarios. For the hindcast relative sea level curves
have to be compared with recent digital elevation models. For future projections
data of vertical crustal displacement received from gauge measurements and eustatic
changes based on climate scenarios have to be superimposed. The model has been
applied to the Baltic Basin, considered as a natural laboratory for coastal research
as it is extending from the uplifting Fennoscandian Shield to the subsiding southern
Baltic lowlands. Subsidence, climatically driven sea level rise, and meteorologically
induced coastal flooding provoke permanent coastal retreat at the southern sinking
coasts. Predictions of coastal hazards are made with the model by using neotecton-
ical data and long-term sea level change data superimposed with extreme sea level
data measured during the storm surge in November 1872.
Keywords
Sea level
·
Climate
·
Eustacy
·
Isostacy
·
Coastline history
·
Hazard
·
Future projection
