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Case-Study Modelling Analysis of Hydrodynamics in the Nearshore of the Baltic Sea Forced by Extreme Along-shore Wind in the Case of a Cross-shore Obstacle

Sokolov A., Chubarenko B.

Archives of Hydro-Engineering and Environmental Mechanics

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2018

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Vol. 65, nr 3

163--176

EN

In the current study we use a three-dimensional model with hydrodynamic and spectral wave modules operating in a coupled mode to simulate the response of currents and wind wave fields to winds of 20–25 m/sec offshore of the protective structure of the Saint Petersburg Flood Prevention Facility Complex. The model was calibrated against field data, which allowed us to obtain a tool describing storm situations in the eastern part of the Gulf of Finland with a satisfactory accuracy. The numerical modeling showed that the protective dam did not have a noticeable effect on the levels of stormsurge, significantwave height, or current speed in areas seaward of the dam. The increase in erosion processes on the southern shore of the easternmost part of the Gulf of Finland in recent past has most probably been related to other factors. We found that if a west or south-west wind of at least 25 m/s blows over the Baltic Sea for at least 16 hours, the level of storm surges seaward of the dam may reach 3 or more meters. An artificial strengthening of the coastline and the creation of shore protection structures are recommended.

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Baltic Sea datums and their unification as a basis for coastal and seabed studies

Wolski T., Wiśniewski B., Musielak S.

Oceanological and Hydrobiological Studies

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2016

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Vol. 45, No. 2

239--258

EN

This paper presents examples of application of a common reference datum, such as NAP, within the elevation EVRS reference system for the Baltic Sea. A common reference datum allowed for setting the geographical pattern of occurrence of extreme sea levels in the Baltic Sea. The eastern Baltic coasts exposed to western air masses are vulnerable to extreme hydrological events (the Gulf of Finland, the Gulf of Riga and the Gulf of Bothnia). On the contrary, the Swedish coasts of the central and northern Baltic are the least threatened by extreme sea levels. The south-western coasts of the Baltic Sea (the Bay of Mecklenburg and the Bay of Kiel) cover the basins with the most frequent and the most severe storm falls and extremely low sea levels. Demonstration of the Baltic surface deformation magnitude during a storm event is another example of NAP application. The instantaneous height difference between the north-eastern and southwestern coasts was 356 cm, which resulted from the negative impact of pressure (water cushion) induced by a dynamic and deep low-pressure system moving through the Baltic Sea. The common reference datum allowed for visualization of the so-called 'theoretical water' distribution which has a wide application in the hydraulic engineering within the coastal zone. In addition, the study provides examples of differences that may be observed during storm events between the real sea-level data and the hydrodynamic model forecast. This is of great practical significance in terms of forecasting storm surges in the Baltic Sea.

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Extreme sea levels at selected stations on the Baltic Sea coast

Wolski T., Wiśniewski B., Giza A., Kowalewska-Kalkowska H., Boman H., Grabbi-Kaiv S., Hammarklint T., Holfort J., Lydeikaite Ž.

Oceanologia

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2014

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No. 56 (2)

259--290

EN

The purpose of this article is to analyse and describe the extreme characteristics of the water levels and illustrate them as the topography of the sea surface along the whole Baltic Sea coast. The general pattern is to show the maxima and minima of Baltic Sea water levels and the extent of their variations in the period from 1960 to 2010. A probability analysis is carried out on the annual sea level maxima and minima for 31 water level gauges in order to define the probability of occurrence of theoretical sea levels once in a specific number of years. The spatial distribution of sea levels for hundred-year maximum and minimum water levels is illustrated. Then, the number of storm surges for the accepted criteria are presented: these numbers increased in the 50-year period analysed. The final part of the work analyses some extreme storm events and calculates the static value and dynamic deformation of the sea surface by mesoscale, deep low-pressure systems.

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Erosion reasons and rate on accumulative Polish dune coast caused by the January 2012 storm surge

Łabuz T. A.

Oceanologia

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2014

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No. 56 (2)

307--326

EN

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 1.5 m amsl along the Polish coast. Land forms up to 3 m amsl were inundated. Beaches and low parts of the coast up to this height were rebuilt by sea waves attacking the coast for almost 12 days. 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 2.5 m3 per square metre with an average toe retreat of 1.4 m. 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 3.2 m or on lower ones covered by embryo dunes.

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Zastosowanie metody kopuli do dwuwymiarowej analizy wezbrań sztormowych w profilach wodowskazowych Świnoujście i Kołobrzeg

Ciupak M., Rokiciński K.

Zeszyty Naukowe Akademii Marynarki Wojennej

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2011

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R. 52 nr 4 (187)

15-34

PL

W artykule zastosowano metod. kopuli do dwuwymiarowej analizy wezbra. sztormowych. Wezbrania sztormowe scharakteryzowano dwuwymiarow. zmienn. losow.: maksymalnym poziomem morza ponad nape.nienie w profilach wodowskazowych .winouj.cie PM.WI i Ko.obrzeg PMKOL. Proba losowa zosta.a wyznaczona na podstawie zidentyfikowanych wezbra. sztormowych wzd.u. po.udniowych wybrze.y Ba.tyku w latach 1976.2000. Celem artyku.u by.o znalezienie najlepszego dwuwymiarowego rozk.adu prawdopodobie.stwa badanej zmiennej losowej (PM.WI, PMKOL). Badaniu poddano eliptyczn. kopul. gaussowsk. i archimedesowsk. jednoparametrow. Gumela-Hougaarda. Do badania zgodno.ci kopuli z zaobserwowanymi realizacjami zmiennej losowej (PM.WI, PMKOL) u.yto wspo.czynnika korelacji rang Spearmana. Najlepsz. zgodno.. uzyskano dla kopuli Gumbela-Hougaarda �Ďs = 0,9871.

EN

The copula method was applied to analyze 2D storm surges. Storm surges were described with 2D variable: the maximum water level above the filling level at Świnoujście PMŚWI and at Kołobrzeg PMKOL. The identified storm surges along of southern Baltic coasts in the period 1976–2000 were used to set the random sample. The aim of this paper is to find the best fit 2D probability distribution of the variable (PMŚWI, PMKOL). Two copula functions: elliptical Gaussian and Archimedean Gumbel-Hougaard copula were investigated. To verify copula conformity with the data observed the non-parametric dependence measure such as Spearman’s ńs was used. The best conformity was recorded for Gumbel-Hougaard copula ńs = 0,9871.