Sea Level Dynamics and Coastal Erosion in the Baltic Sea Region (original) (raw)
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Sea level fluctuation and shoreline evolution on decadal time scale, Lithuanian Baltic Sea coast
Journal of Coastal Research, 2014
Fluctuations in sea level are reflected in shoreline dynamics. Depending on the nature of the change, the coast is dominated by either erosion or accumulation processes. However, despite considerable attention to this subject, few works have been dedicated to the direct research of coastal development dependence on these determining factors. The objective of this paper was to assess the impact of sea level fluctuations on shoreline dynamics based on coastal monitoring data. The monitoring of coastal dynamics has been carried out since 2002. Annual shoreline displacement was determined based on the obtained data. In addition to morphometric data, sea level data from the Klaipėda gauge station from 2002-2012 were used. The results showed that the long-term tendency of shoreline displacement was not uniform. From 2002-2012, a shoreline recession of the mainland coast was observed, whereas accumulation processes prevailed in the Curonian Spit. Also, a trend of rising sea level was observed from 2002-2012. No significant correlation between shoreline displacement and sea level on a decadal time scale was found. This may be due to the fact that the long-term trend in sea level was negligible and had no distinct impact on coastal dynamics. Short-term changes in sea level, on the other hand, have had a greater impact on coastal dynamics. A good correlation between the shortterm change in yearly sea-level and shoreline displacement was observed.
… of climate and …, 2007
Coastline changes are the result of the interaction between geosystems and climate. Vertical isostatic movement of Earth’s crust competes with the eustatic sea-level variation controlled by changing climatic conditions. The resulting relative sea-level variation has a vital impact on the anthroposphere along the sea coast. This interrelation can be studied in an exceptional manner on the southern Baltic Sea. Here, isostasy and eustasy have shaped the picture of the coastal areas since the last glaciation. The northern Scandinavian part has been uplifting constantly since the last deglaciation, causing a regression of the sea. In contrast, in the south, the Littorina transgression has initiated land loss due to the glacio-isostatically sinking coast. Human populations living along the coast since Mesolithic time have reacted by relocating settlements. This migration is well documented and preserved at the Wismar Bight, Germany, by submarine archaeological remnants. Dates of samples from ancient coastlines, supported by geostatistical methods to estimate sediment transport processes, allow us to model the paleogeographic settings on a local scale using maps. By projecting the investigated processes into the future, scenarios of predicted coastline evolution can be modeled. Extrapolated isostatic measurements and sea-level data derived from IPCC (Intergovernmental Panel on Climate Change) scenario A for the next 800 yr are superimposed in order to estimate areas that may sink below the sea level.
… Geological Institute Special Papers Selected full …, 2003
The relative sea level curve was developed for the southern Baltic area, based on a set of 314 radiocarbon datings of different terrestrial and marine sediments, collected at 163 sites located in the Polish part of the Southern Baltic and in the adjacent coastal land area. When developing the curve, relicts of various formations related to the shoreline evolution as well as extents of erosional surfaces, determined from seismoacoustic profiles, were taken into account. During Late Pleistocene and Early Holocene, i.e. between 13.0 and 8.5 ka BP, the southern Baltic sea level rose and fell three times, the amplitude of changes extending over 25-27 m. In some extreme cases, the sea level was falling at a rate of up to about 100-300 mm/a, the rate of rise accelerating to about 35-45 mm/a. In the Late Boreal, c. 8.5 ka BP, the Baltic-its water level by about 28 m lower than the present one-became permanently connected with the ocean. Until the onset of the Atlantic, the sea level had risen to about 21 m below the present sea level (b.s.l.). During 8.0-7.0 ka BP, the sea level was rising, at a rate of about 11 mm/a, to reach 10 m b.s.l. Subsequently during the Atlantic, until its end, the sea level rose to 2.5 m b.s.l., the rate of rise slowing down to about 2.5 mm/a. During the first millenium of the Subboreal, the sea level rose to about 1.3-1.1 m b.s.l., to become-on termination of the Subboreal-about 0.6-0.7 m lower than present. During the Subatlantic, the sea level changes were slight only. The glacio-isostatic rebound began c. 17.5 ka BP, to terminate c. 9.2-9.0 ka BP. The total uplift during that time amounted to about 120 m. The maximum uplift rate of about 45 mm/a occurred c. 12.4-12.2 ka BP. Within the period of c. 9.0 to c. 7.0 ka BP, the southern Baltic experienced forebulge migration, a subsequent subsidence ensuing from c. 7.0 to c. 4.0 ka BP. As from c. 4.0 ka BP, the Earth crust in the area regained its equilibrium. In Late Pleistocene and Early Holocene, the southern Baltic shoreline displaced rapidly and substantially several times, the displacement rate ranging from several tens of metres to a few kilometres per year. The displacement processes involved the seafloor surfaces located at present at 25 to 55 m b.s.l., the shoreline migrating over distances of 30-60 km away from the present coastline. In Middle Holocene, the shoreline moved southwards over a distance ranging from about 60 km in the Pomeranian Bay to about 5 km in the Gulf of Gdañsk. The shoreline location approached the present one at the final phase of the Atlantic. Late Holocene was the period when coast levelling processes were prevailing, the shoreline becoming gradually closer and closer to its present setting.
Special Paper 426: Coastline Changes: Interrelation of Climate and Geological Processes, 2007
Coastline changes are the result of the interaction between geosystems and climate. Vertical isostatic movement of Earth's crust competes with the eustatic sea-level variation controlled by changing climatic conditions. The resulting relative sea-level variation has a vital impact on the anthroposphere along the sea coast. This interrelation can be studied in an exceptional manner on the southern Baltic Sea. Here, isostasy and eustasy have shaped the picture of the coastal areas since the last glaciation. The northern Scandinavian part has been uplifting constantly since the last deglaciation, causing a regression of the sea. In contrast, in the south, the Littorina transgression has initiated land loss due to the glacio-isostatically sinking coast. Human populations living along the coast since Mesolithic time have reacted by relocating settlements. This migration is well documented and preserved at the Wismar Bight, Germany, by submarine archaeological remnants. Dates of samples from ancient coastlines, supported by geostatistical methods to estimate sediment transport processes, allow us to model the paleogeographic settings on a local scale using maps. By projecting the investigated processes into the future, scenarios of predicted coastline evolution can *deceased.
Sea level variability at the Lithuanian coast of the Baltic Sea
2006
The aim of the paper is to analyse the sea level variability at the Lithuanian coast during the last 100 years using all data available in Lithuania. The analysis, based on sea level data of the Klaipėda Strait for 1898-2002, clearly shows that the long-term sea level increased by about 13.9 cm. Furthermore, it is remarkable that the increase is not found to be linear during the study period. Only a negligible increase is found at every Lithuanian tide gauge until World War II. Starting from the middle of the last century the increase in sea level is more pronounced having a rate of about 3 mm per year since the 1970s. This rise leads to manifold practical problems concerning activities in the coastal areas. The water rise will intensify the intrusion of salty water into the Curonian Lagoon slowly changing the ecosystems in its northern part. The reasons behind this rise are related to enhanced and more frequent advection of warm and moist maritime air masses during the cold season (October-March). This is coupled with intensified air flow from the west with increasing air temperatures followed by rise in water temperatures and thermal expansion of sea water, the global rise of the sea level also playing an important role. The annual mean sea level fluctuation is found to be linked with the winter North Atlantic Oscillation (NAO) index. When the NAO index is positive during winter, the dominating and enhanced westerly flow across the North Atlantic advects relatively warm maritime air over northern Europe. These strong westerly winds cause more frequent flooding events in the southeastern part of the Baltic Sea at the Lithuanian coast.
Mechanisms of variability of decadal sea-level trends in the Baltic Sea over the 20th century
Earth System Dynamics Discussions
Coastal sea-level trends in the Baltic Sea display decadal-scale variations around a centennial trend. These long-term centennial trends are likely determined by climate change and centennial vertical land movements. In this study, we analyse the spatial and temporal characteristics of the decadal trend variations and investigate the links between coastal sea-level trends and atmospheric forcing on decadal time scale. This investigation mainly focuses on the identification of the possible impact of an underlying factor, apart from the effect of atmospheric circulation, on decadal sea-level trend anomalies. <br><br> For this analysis, we use monthly means of long tide gauge records and gridded sea-surface-height (SSH) reconstructions. The SSH time series are constructed over the past 64 years and based on tide-gauge records and satellite altimetry. Climatic data sets are composed of the North Atlantic Oscillation (NAO) index, the Atlantic Multidecadal Oscillation (AMO) in...
Changes in extreme sea-levels in the Baltic Sea
Tellus A, 2014
A B S T R A C T In a climate change context, changes in extreme sea-levels rather than changes in the mean are of particular interest from the coastal protection point of view. In this work, extreme sea-levels in the Baltic Sea are investigated based on daily tide gauge records for the period 1916Á2005 using the annual block maxima approach. Extreme events are analysed based on the generalised extreme value distribution considering both stationary and time-varying models. The likelihood ratio test is applied to select between stationary and nonstationary models for the maxima and return values are estimated from the final model. As an independent and complementary approach, quantile regression is applied for comparison with the results from the extreme value approach. The rates of change in the uppermost quantiles are in general consistent and most pronounced for the northernmost stations.
Marine Geology, 2003
Sedimentological and morphological changes on the upper and lower shoreface during relatively stable sea-level highstand conditions have been investigated in the Pomeranian Bight, southern Baltic Sea, at time scales ranging from storm events to millennia. In order to cover that variety of time scales, different methods have been applied. Seasonal variations in the morphology of the upper shoreface were measured accurately using the tracer stick method. The ratio of breaking waves and energy dissipation due to wave breaking are the main forces controlling redeposition on the upper shoreface with the depth of disturbance up to three times the net change. The impact of single storm events can be observed from sidescan sonar mosaics to remain on the decadal scale. Aerial photographs covering the upper shoreface show that the location of gates, channel-like systems where water masses move offshore created during storm events, also remain stable over decades. Sedimentological and geomorphological variations and changes on the lower shoreface are only measurable on the century to millennium scale because the main driving forces are longlasting processes like sea-level fluctuations or neotectonics. Data on these scales have much more uncertainty in their relationship to forcing functions than data at shorter time scales. Because the effects of coastal processes active on different time scales can interact, comprehensive understanding of large-scale coastal behavior requires investigations from short events to long-term processes. ß