Preparation of Papers in Two-Column Format for the Proceedings of the 2004 Sarnoff Symposium

Authors’ personal version: Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium. 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862

PAPERS FROM THE 7TH IEEE/OES BALTIC INTERNATIONAL SYMPOSIUM "CLEAN AND SAFE BALTIC SEA AND ENERGY SECURITY FOR THE BALTIC COUNTRIES” (ED. - ALBERT J. WILLIAMS 3RD) IS PUBLISHED IN IEEE XPLORE DIGITAL LIBRARY

Reference to the paper:

Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium "Clean and Safe Baltic Sea and Energy Security for the Baltic countries". 12–15 June 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862

Authors’ personal version of the paper

HYDRODYNAMIC CONDITIONS NEAR THE NORTHERN SHORE OF SAMBIA PENINSULA (THE BALTIC SEA) AS A BASIS OF GEOTEXTILE DEBRIS TRANSPORT ANALYSIS

Andrei Sokolov1,2([email protected]), Boris Chubarenko1([email protected]), Georg Umgiesser3,4 ([email protected])

Abstract Storm winds with direction from western quarter have a negative impact on the shore of the Sambia Peninsula (South-Eastern Baltic). Cliffs and dunes are partly protected against erosion by different constructions including geotextile. Most of them are located at the northern shore of the Sambia Peninsula, namely, near Svetlogorsk and Pionerskiy towns. Consequtive, storm by storm, forcing destroys the protective constructions, geotextile pieces are spread over surrounding area and the debris of them pollute the sea. The aim of the study was to find out what winds produce the most significant threat for erosion and therefore form the initial conditions for transport of geotextile debris alongshore. Numerical simulations by SHYFEM model calibrated against the field data was used to analyze the structure of near shore hydrodynamics. It was supposed that a threat for coastal erosion is proportional to wind and wave induced sea level run-up and speed of coastal currents. Simulations showed that winds of the northwest and even western directions could potentially cause the maximum erosion at the northern shore of the Sambia Peninsula. These winds may lead to the sea level rise up to 0.3-0.5 m and speed of currents up to 0.7-0.8 m/s and more (at winds of 20 m/s). Keywords: Baltic Sea, coastal zone, numerical simulations, storm surge, coastal currents, wind waves, geotextile debris Affiliations: 1Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia; 2Immanuel Kant Baltic Federal University, Kaliningrad, Russia; 3Klaipeda University, Klaipeda, Lithuania; 4ISMAR-CNR, Venezia, Italy

1. Introduction are formed between a shoreline and first wave The Baltic Sea is a non-tidal sea, so extreme water breaker cause active sediment transport [3]. The sea levels here are related to storm events, which are level rise due to storm surge amplifies a destructive manifested as surges in sea level. A strong storm action of waves and currents to the beach, dune and surge occurs as a result of the impact of strong cliff. Cliffs and dunes at the northern part of Sambia onshore wind and decrease of atmospheric pressure Peninsula near Svetlogorsk, Pionerskiy (Fig. 1) and at the sea surface. If these two main origins are some other locations are protected by constructions coupled with some additional factor, the rise of the which include geotextile. Consecutive, storm by sea level could be catastrophic. For example, in storm, forcing destroys the geotextile parts of the January 2012 storm surge occurred on the protective constructions. Geotextile pieces are background of increased values of mean sea level, spread out over surrounding area and the debris of related to flooding of saline water from the North them pollute the sea. Intensive currents generated Sea to the Baltic Sea [1]. The overall rise of the water between the first wave breaker and the shoreline level near the northern shore the Sambia peninsula lead to active transport of the geotextile debris. was more than one meter. Very high storm surges The aim of this study was to analyze what have also been recorded on German and Polish winds produce the most significant threat for erosion shores, where increasing water levels have destroyed and therefore form the initial conditions for transport dune and cliff systems [2]. For the German shore of of geotextile debris alongshore. It was supposed that the Baltic Sea, a dangerous storm surge is usually a threat for coastal erosion is proportional to wind considered to be an increase in sea level of at least and wave induced sea level run-up and speed of 100 cm above the mean level. The Polish shore coastal currents. In particular, the following protection services describe a storm surge as a questions were addressed: dynamic rise in sea level above the warning level (70 - what wind directions do form maximum storm cm above the mean level) and the alarm level (100 surge and nearshore current speed in the vicinity cm above the mean level). of Svetlogorsk and Pionerskiy (potential sources of Stormy winds with direction from north-west the pollution by geotextile on the northern shore quarter have a negative impact on the shore of the of the Sambia Peninsula); Sambia Peninsula (South-Eastern Baltic). In particular, - what is the dependence between sea level surge it concerns the northern part of Sambia peninsula (as well as nearshore current speed) and the wind where the main resorts (Svetlogorsk and speed for these most dangerous directions? Zelenogradsk) are located. Intensive currents, which Authors’ personal version: Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium. 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862

Fig. 1 Map of the Baltic Sea (http://www.nationsonline.org/oneworld/map/Baltic-Sea-map.htm) and a computational domain. ADCP – location of the field station IBW PAN, which data were used for calibration. 1 and 2 – points of sources of potential pollution by a geotextile near Svetlogorsk and Pionerskiy respectively

2. Method time; ζ is the free surface elevation; H is the water Simulations were performed using a free available depth; f is the Coriolis parameter. The terms X and Y (http://www.ismar.cnr.it/shyfem) SHYFEM finite- take into account the effect of wind stress and other element hydrodynamic model [4–7], which was nonlinear parameters. R is the friction term which developed by ISMAR-CNR. For the simulation, a two- can be written as follows: dimensional formulation of the SHYMEM model was u 2 + v2 R = g (4) used. It is based on the resolving of the following C 2 H equations in the shallow water approximation: Here u and v are velocity components in x and y ∂U ∂V − fV + gH + RU + X = 0 directions respectively; C is the Chezy number. ∂t ∂x One of the most important features of the SHYFEM model is using of a semi-implicit algorithm (1) for the time integration. The use of this algorithm ∂V ∂V + fU + gH + RV + Y = 0 (3) allows to get results with acceptable accuracy and ∂t ∂y rather short computational time. It is especially important when the computational domain is pretty (2) large. A detailed information of the SHYFEM model, ∂V ∂U ∂V + + = 0 equations and numerical solution technic is given in ∂t ∂x ∂y [7]. Here U and V are the depth-averaged velocity components in x and y directions respectively; t is the Authors’ personal version: Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium. 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862

The model setup Polish Academy of Sciences (IBW PAN) [10]. The The computational domain covered the South part of ADCP device was mounted about 200 m from the the Baltic Sea (Fig. 1). According the finite element shore at a depth of about 4.5 m. near the Lubiatowo method, an irregular grid with triangular elements Field Station belonging to IBW PAN (point ADCP in Fig. was used for simulations. It allowed to introduce a 1, 54.8° North and 17.8° East). The ADCP device smooth coastline and focus on the areas that are the recorded current velocities at the horizons 0.4 and most interesting and important, namely, the 2.4 meters above the bottom. The wind data used for northern shore of the Sambia Peninsula. The typical calibration were obtained by the IBW PAN Lubiatowo scale of finite elements near the shore was 100-150 meteorological station. m, the same scale for the elements in the open sea The calibration results are shown in Fig. 2. We was about several kilometers. chose data recorded from 01.10.2006 to 16.10.2006 All boundaries of the simulation area are for the calibration. Such choice based on several closed, and wind is the only driving force in the reasons. Firstly, we had continuous and pretty long model. It is supposed that the wind speed and data series without any interruptions. Secondly, the direction are similar in all the computational area. direction of currents during this period was mainly Bathymetric data from [8, 9] are used for the along the shore. Thirdly, we had two noticeable computational domain. maximums of the speeds of the currents (about 0.5- All simulations have been carried out with a 0.7 m/s) with opposite directions: to the east (06- time step of 300 s. Other main simulation parameters 07.10.2006) and to the west (14.10.2006). If the are the following: values are positive, it means that the water transport - constant bottom friction within the all domain, is eastward. If they are negative, it means that the the Strickler coefficient of 32 m1/3/s (default in water transport is westward. SHYFEM); The curve (1) represents the field data, ADCP - the wind is uniform, i.e. the wind speed and measurements at the horizon 2.4 m above the direction were equal for all points inside the bottom; the curve (2) represents SHYFEM numerical domain; solution. Wind data are shown at the top of the - constant wind friction, the drag coefficient was figure in the form of arrows directed accordingly. The 02.5x10–3 (default in SHYFEM); strongest observed wind (about 18 m/sec) was on - zero initial conditions for currents and surface 06.10.2006. elevation. It can be noticed that simulations and Simulation results for current velocity measurements have a moderate agreement: typical components and sea levels were stored in binary files differences (absolute values) are less than 0.2 m/s for three specific points marked 1, 2 and ADCP (see and maximal differences are about 0.3 m/s. A fig.1). The ADCP point was used for the calibration Pearson correlation coefficient between (see below). Point 1 is located about 200 m seaward measurements and SHYFEM simulations is 0.75. It the shoreline (sea depth is about 5 m) near a seems that tendencies of changing of hydrodynamic potential source of the pollution by geotextile in the conditions are tracking more or less adequately: calm vicinity of Svetlogorsk. Point 2 is located about 200 m weather and windy weather periods have distinct seaward the shoreline (sea depth is about 4 m) near differences. Directions of longshore currents are a potential source of the pollution by geotextile in tracking as well, but in general the result is not the vicinity of Pionerskiy. perfect: the model overestimates low currents and underestimates high currents. Besides, we can see Calibration of the model noticeable oscillations in SHYFEM results which are Calibration of the utilized model setup was based on not present in the field data. Anyway we suppose a field data, which were recorded by the Acoustic that the calibration result allows to use SHYFEM Doppler Current Profiler in the measurements model setup for coastal simulations. fulfilled by the Institute of Hydro-Engineering of the Authors’ personal version: Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium. 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862

Fig. 2. Alongshore current speed, field data and simulation results (01–16 October 2006)

Scenario analysis under winds with a speed of 20 m/s and SW, W, NW, The calibrated set-up of the model SHYFEM was used N and NE directions are presented in the Table 1. The first to simulate the quasi steady state solutions for maximum surface elevations (about 0.5 m for points currents under the forcing of steady wind of 20 1 and 2) are observed when the wind is from North- m/sec of five different wind directions (SW, W, NW, West direction. The current speed is about 0.5 m/s N, NE). Then two wind directions the most dangerous for points 1 and 2 under these conditions. The from the point of view of potential erosion of cliffs maximum current speed is corresponded to the wind and dunes near Svetlogorsk and Pionerskiy were is from West direction and is equal to about 0.6 m/s selected, and for them wind of five wind grades (5, for the point 1 and 0.7 m/s for the point 2. The 10, 15,20, 25 m/sec) were simulated. In total 15 maximum surface elevation is 0.4 m for the point 1 scenarios of steady wind forcing were simulated. and is 0.5 m for the point 2 under these conditions. Detailed results for a depth-averaged current speed We can suppose that winds from North-West and and a surface elevation are presented for the sites 1 West directions are the most dangerous from the (sea depth about 5 m) and 2 (sea depth about 4 m). point of view of potential erosion of cliffs and dunes near Svetlogorsk and Pionerskiy. The maximum surface elevation and structure Results of the currents fields under these two selected winds (from North-West and West directions) are Wind speed 20 m/s. Different wind directions illustrated by Fig. 3 and 4. Depths-averaged velocities of currents and the maximum sea level elevations at the points 1 and 2

Table 1. Elevations and Currents for winds of various directions and speed of 20 m/s Wind direction South-West West North-West North North-East Point 1 2 1 2 1 2 1 2 1 2 Surface elevation, m 0.2 0.3 0.4 0.5 0.5 0.5 0.3 0.3 -0.2 -0.3 Current speed, m/s 0.5 0.6 0.6 0.7 0.5 0.5 0.2 0.3 0.5 0.6

(a) (b)

Fig. 3 Fields of the surface elevation (a) and current velocities (b) near the northern shore of the Sumbia Peninsula under the North-West wind. Dotted line marks the location of counter currents

(a) (b)

Fig. 4 Fields of the surface elevation (a) and current velocities (b) near the northern shore of the Sumbia Peninsula under the West wind

For North-West wind we can see a structure of The maximum rise in level (about 0.6–0.7 m) is currents with circulations and counter currents. On in a middle part of the Curonian Spit. At points 1 and the north shore of the Sambia Peninsula, in the area 2 the level rise is about 0.5 m. from the Cape Taran to the root of the Curonian Spit Under the West wind the eastward alongshore the eastward flux of waters is observed. Speeds of flux of the waters from the north-east part of the currents are defined by a local relief of the shore: in Sambia Peninsula to the Curonian Spit is observed. the coves which are in a wind shadow the speed are Currents follow the local morphology. The greatest 0.3–0.5 m/s while it reaches 0.8 m/s near the capes. speeds (0.8–0.9 m/s) are reached at capes of On the west shore of the Sambia Penisula the northern part of the Sambia Peninsula. The speeds southward flux of waters exists. Speeds of currents simulated at the point 1 and 2 are 0.6 m/s and 0.7 rather smoothly decrease from 0.6–0.8 m/s to 0.3 m/s respectively. These values are the greatest ones m/s in the south of the area. At the root of the in comparison with another wind directions. Curonian Spit a convergence zone with complex Maximum level rise (over 0.7 m) is attributed counter currents is observed. The counter flows to the center of the Curonian Spit, it reaches 0.4 m merge together and form a powerful jet flowing and 0.5 m at points 1 and 2 respectively. towards the bigger depth. Speeds of currents in this The results obtained in this study using the area are about 0.2–0.3 m/s and currents are not SHYFEM simulation are in a satisfactory agreement alongshore, but are directed substantially with the simulations performed under the other perpendicularly to the shoreline. model (MIKE) [11]. So even we didn’t achieve exact values of simulated variables (current and water Authors’ personal version: Sokolov A., Chubarenko B., Umgiesser G. Hydrodynamic conditions near the northern shore of Sambian Peninsula (the Baltic Sea) as a basis of geotextile debris transport analysis. 7th IEEE/OES Baltic International Symposium. 2018, Klaipėda, Lithuania. IEEE Xplore Digital Library, 2018. Pp. 1-6. https://doi.org/10.1109/BALTIC.2018.8634862 level), we may be sure in tendencies and qualitative under NW and W winds (Fig. 5a). Whereas the consistency between nature and SHYFEM simulations. dependences of the surface elevation against the wind speed are significantly nonlinear (Fig. 5b). These Dependence of current speed and surface elevation on dependencies can approximately be presented by the the wind speed for NW and W winds equation L = a ⋅W 2 , where L is the surface elevation; To illustrate the dependence of current speed and W is the wind speed; a is a parameter. The value of surface elevation on the wind speed we shall present the parameter a varies between 0.0011 and 0.0013. the results of scenarios of wind of 20 m/sec. The current speed grows linearly with the wind speed

(a) (b)

Fig. 5 Current speed (a) and surface elevation (b) against the wind speed. Legend: the symbol 1 indicates point 1), while the symbol 2 indicates point 2 (see Fig. 1). NW indicates North-West wind; W indicates West wind.

Conclusions References Simulations showed that winds from the North-West 1 Sokolov, A.N., B.V. Chubarenko, K.V. Karmanov, and from the West could potentially cause the “Hydrodynamic conditions in a coastal zone of maximum erosion at the northern shore of the the Vistula spit and Sambia Peninsula: storm Sambia Peninsula. If the points 1 and 2 are event of January,” Transactions of Kaliningrad considered, these winds may lead to the sea level rise State Technical University, vol. 43, pp. 67–77, up to 0.4–0.5 m and speed of currents up to 0.6–0.7 2012. [In Russian]. m/s (at winds of 20 m/s). 2 Wolski, T., Wiśniewski, B., Giza, A., Kowalewska- The spatial structure of currents shows that Kalkowska, H., Boman H., Grabbi-Kaiv, S., debris of geotextile materials will be transported Hammarklint, T., Holfort, J., Lydeikaite, Z. eastward from their sources in Svetlogorsk and “Extreme sea levels at selected stations on the Pionersk, but for NW wind this transport will be cut Baltic Sea coast,” Oceanologia, vol. 56 (2), pp. by divergence structure at the root of the Curonian 259–290, 2014. Spit, and the material can be washed out from 3 Massel S.R. Hydrodynamics of Coastal Zones. nearshore to the bigger depths. Elsevier Science & Technology, Oceanography Series, vol. 48, 1989, 336 p. Acknowledgments 4 Umgiesser, G. “Modeling the Venice Lagoon,” The modelling was supported via RFBR grant 18-55- International Journal of Salt Lake Research, vol. 6, 76002 (ERANET-Rus joint project EI-Geo), the pp. 175–199, 1997. environmental data was collected within State 5 Ferrarin, C. & Umgiesser, G. “Hydrodynamic Assignment of FASO Russia 0149-2018-0012/0149- modeling of a coastal lagoon: the Cabras lagoon 2019-0013. in Sardinia, Italy,” Ecological Modeling, vol. 188, pp. 340–357, 2005. 6 Ferrarin, C., A. Razinkovas, S. Gulbinskas, G. Umgiesser, L. Bliudziute, “Hydraulic regime-based

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