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Article

Assessment of Coastal Morphology on the South-Eastern Baltic Sea Coast: The Case of Lithuania

by
Ilona Šakurova
*,
Vitalijus Kondrat
,
Eglė Baltranaitė
,
Erika Vasiliauskienė
and
Loreta Kelpšaitė-Rimkienė
Marine Research Institute, Klaipėda University, Universiteto Ave. 17, LT-92294 Klaipėda, Lithuania
*
Author to whom correspondence should be addressed.
Water 2023, 15(1), 79; https://doi.org/10.3390/w15010079
Submission received: 29 November 2022 / Revised: 20 December 2022 / Accepted: 23 December 2022 / Published: 26 December 2022
(This article belongs to the Special Issue Coastal Planning and Sediment Management Perspectives)
Browse Figures
Versions Notes

Abstract

:
The Port of Klaipėda, located at the Klaipėda strait, divides the Lithuanian coast into two different geomorphological parts: southern—the coast of the Curonian Spit, and northern—the mainland coast. Port jetties interrupt the main sediment transport path along the South-Eastern Baltic Sea’s coast. Port of Klaipėda reconstruction in 2002 and the beach nourishment project which started in 2014 significantly influenced the northern part of the coast, which led to changes in the coastal zone evolution. The measurements in various periods are essential for cross-shore profile elevation to analyze seabed morphology and sedimentation patterns. These data highlight our understanding of the scale and timing of seabed erosion or sedimentation processes scale and timing. This study evaluates the impact of anthropogenic pressure and natural factors on coastal geomorphology and dynamics. In order to assess the latter changes, the cross-shore profile evolution and sediment budget were analyzed as well as nearshore bathymetry changes. The data illustrated a changing picture of the entire shore profile—on land and underwater.

1. Introduction

The unique relief of the Baltic Sea coast is and has always been formed by two main natural elements—the sea and the wind. Therefore, most coastal relief forms are related to their geological activity [1,2,3]. Depending on the sea level, wave parameters, underwater currents, and several other natural and often anthropogenic factors are forming wider and/or narrower beaches [1,2]. The litho- and morpho-dynamics processes play an important role in the shore formation mechanism. On land, they are mainly determined by aeolian processes, while at sea and on the beach, by hydrodynamic processes [2,3,4].
The coastal zone is under constant change and environmental pressure from various natural processes (sea level rise, increased storminess, shifting hydrometeorological conditions) and anthropogenic activities (port activities, dredging, coastal protective measures, coastal tourism) [5]. At the end of the 20th century, the anthropogenic impact became an independent geological factor affecting many coast formation processes [2,6]. Changes in the Lithuanian coastal area are related to human activity and natural factors [2,7]. Stronger storms, more intensive sand discharge from the coastal zone, rising global sea levels, development and dredging of the port area, and expansion of the recreational zone are the most common factors that are considered to mitigate the pressure affecting the coastal zone nowadays [2,7,8].
Aside from the natural factors and the various human activities to consider, a vast institutional framework and a set of national policies are in place to be satisfied in accordance with the major world climate action agreements: the Paris Agreement under the 1992 United Nations Framework Convention on Climate Change (UN-FCCC), the UN agreements on Disaster Risk Reduction (Sendai) and Finance for Development (Addis Ababa), and the Sustainable Development Goals (SDGs). Therefore, a holistic approach, coordinated policies, and cross-sector planning are crucial to ensure sustainable territory management and avoid or reduce trade-offs between mitigation and adaptation to climate change [9].
The characteristics of coastal morphodynamic processes—the interaction between bathymetry (topography) and hydrodynamics—largely determine the volume distribution during sediment transport [5]. Sediment budget and geology determine the morphology and dynamics of coasts, which affects the nature and health of coastal systems [10,11]. Human activities affecting sediment dynamics along the coast and inland can alter naturally occurring patterns of erosion and accumulation [10,11]. Of the various beach types around the world, sandy beaches are the most heavily used and geomorphologically complex, and the shoreline is constantly changing due to the interaction between natural and anthropogenic factors causing the erosion or accretion processes occurrence [11]. Although coastal geomorphology depends on complex processes in nature, knowledge of wind–wave climate [12,13,14], the correspondence of interactions with sediment particles, and a better understanding of coastal dynamics on the spatiotemporal scale make coastal evolution easier to predict [5,15].
Bathymetry data are important for analyzing seabed morphology and sedimentation patterns [16,17,18,19]. From the variation of bathymetry data, seabed erosion or sedimentation could be detected and evaluated [20]. The Baltic Sea has unique geomorphic, hydrographic, and hydrodynamic characteristics that shape the seafloor landscape and influence coastal zone dynamics [21,22]. Anthropogenic pressure among natural factors affecting the Baltic Sea seabed morphology is important to consider. The most significant human activities are harbor constructions, dredging, various cable and pipeline projects, and renewable energy constructions. This can cause coastal erosion or alter underwater mass direction [23], negatively affecting some areas of the Baltic Sea. Therefore, such risk factors should be considered before any construction work is undertaken [8,23,24].
Understanding the variability of the entire cross-shore profile, which includes on land and underwater parts, is crucial for sustainable coastal management, as it allows for a more accurate application of different coastal engineering operations: (i) coastal nourishment [25,26,27], (ii) design of coastal protection structures [24,27,28,29], (iii) coastal sediment balance calculations [23,24]. Cross-shore profiles and their calculations are used to evaluate longshore sediment transport rates and develop and predict erosion and accretion volumes [30]. Although it is challenging to observe changes in a swash zone (transitional area of the coastal profile) that is the most dynamic part of the coastal profile, a better understanding of sediment transport processes in the nearshore zone is necessary [31,32].
The main objective of this paper is to evaluate the impact of anthropogenic pressure and natural factors on cross-shore profile changes at the sandy, high-energy coast. In order to assess the changes in coastal geomorphology, the cross-shore profile evolution, the granulometric composition of sediments, and hydrometeorological data were analyzed as well as nearshore bathymetry changes. The data provided a changing picture of the entire shore profile—on land and underwater.

2. Materials and Methods

2.1. Study Site

The Lithuanian coast (90.6 km) of the Baltic Sea (Figure 1) represents a generic type of almost straight, relatively high-energy, actively developing coasts that (1) contain a large amount of fine, mobile sediment, (2) are open to predominating wind and wave directions, and (3) are exposed to waves from a wide range of directions [7,33]. The specific two-peak directional structure of predominant winds has created a subtle balance of litho-dynamical processes on the Lithuanian coast [34,35]. This balance has changed during the last 50 years [36]. The shore is more actively eroded now, leading to the deterioration of recreational space, and endangering different coastal engineering structures and other infrastructure objects in the coastal zone [7,8].
The Port of Klaipėda, located at the Klaipėda strait (the SE Baltic Sea), divides the Lithuanian coast into two geomorphologically different sites—southern and northern [3]. The southern part of the Lithuanian coast includes the Curonian Spit coast, which consists of sandy sediments and represents accumulation processes on the nearshore [2]. The distribution of the sandy sediments is mainly affected by longshore sediment transport, in which the main path is from south to north [37,38].
The northern part of the Lithuanian coast is the mainland coast, which extends north from the Port of Klaipėda jetties. This part of the Lithuanian coast is more geologically diverse than the southern part [2,7]. In the northern part of the mainland coast (Palanga–Būtingė), sandy sediments prevail, forming mainly in the Littorina and Post-Littorina seas [2,39]. The southern part of the mainland coast (Giruliai, Nemirseta, Melnragė) consists of the moraine (glacial deposits) and coarse sand (Figure 2 and Figure 3) [2,39].

2.2. Hydrometeorological Data

The hydrometeorological data of mean wind speed (m/s) and direction (degrees) of 1993–2021, as well as mean wave height (m) and direction (degrees) data of 1993–2019 used in this study, were processed in Origin Pro 2021 software for statistical analysis and graphing [40]. These data were obtained from the Marine Environment Assessment Division of the Environmental Protection Agency (EPA), Lithuanian Hydrometeorological Service under the Ministry of Environment, Palanga Aviation Meteorological Station, and the Port of Klaipėda administration. The data were initially collected at the Klaipėda meteorological stations on the Baltic Sea coast, Palanga Aviation Meteorological station in Lithuania, and the port area (Figure 1). Klaipėda meteorological station is located near the Port of Klaipėda jetties. As constructions surround it, there is no direct access to the Baltic Sea. The height above sea level is 6.2 m.

2.3. Cross-Shore Profile Evolution

Cross-shore profiles along the study area were measured from the shoreline to the dune crest. In total, 40 profiles every 500 m were measured. Data were collected using an Emlid Reach RS+ RTK GNSS receiver with centimeter precision and a dual-band GPS receiver, Leica 900. Moreover, cross-shore profile data were obtained from the Lithuanian Geological Survey, covering the 1993–2022 period.
The cross-shore profiles were used to calculate a volume by applying the following equation [41]:
v 1 = ∑ p = 1 n ( S I ) L
where p is the cross-shore profile, S is a surface, I is an extrapolation between two profiles, and L is the linear part of the coast concerned by the calculation to get the m3/m linear alongshore variations.

2.4. Beach Sediment Sampling and Processing

Historical sediment data for 1993–2003 were obtained from the Lithuanian Geological Survey (Bitinas 2004). Sediment samples for 2003–2022 were collected in line with the Lithuanian Geological Survey methodology at 3 points in every cross-shore profile: the dynamic shoreline, the middle part of the beach, and the foredune. The collected sediment samples were processed in the laboratory using a set of nineteen sieves in the following fractions: >2500; 2500–2000; 2000–1600; 1600–1250; 1250–1000; 1000–800; 800–630; 630–500; 500–400; 400–315; 315–250; 250–200; 200–160; 160–125; 125–100; 100–80; 80–63; 63–50; <50 µm. In the second step, the obtained data were calculated using the GRADISTAT add-in in the Excel program [42]. The latter Excel add-in applied the Udden (1914) [43] and Wentworth (1922) [44] sediment size classification scale to calculate the grain size and distribution of sediments.
In this research, the historical grain size data until 2003 were used alongside the classification provided by the Lithuanian Geological Survey and the Udden (1914) [43] and Wentworth (1922) [44] classification-based data starting from 2004. To ensure data integrity and comparability, transitioning between the two classifications adjustment was made to use the following grain size: 2500–2000 very fine gravel; 2000–1000 very coarse sand;1000–500 coarse sand; 500–250 medium sand; 250–100 fine sand; 100–50 very fine sand; <50 silt [42].

2.5. Bathymetric Data

The bathymetric data for 1993–2022 were procured from the Port of Klaipėda administration with a 0.5 m grid resolution and the Lithuanian Geological Survey with a 1.5 m grid resolution. The provided data were collected with a Kongsberg EM2040C multibeam echo sounder following Standards for Hydrographic Surveys S-44 of the International Hydrographic Organization [45]; the depth data were processed using the hydrographic data recording and processing software Hypack Max (HYSWEEP).
In addition, nearshore bathymetry data were collected in 2022 using 3-frequency Deeper Sonar. Elevations were observed on cross-shore transects extending from the shoreline to ~6 m depth. Measurements were made in the mainland part of the study area, 10 km north of the northern jetty.
The triangular irregular network (TIN) was created using obtained data from a point cloud dataset in Global Mapper 2022 [46] to represent the studied surface morphology. This method connects 3D (X, Y, Z) point features into a network of triangles. From there, the program ran interpolation over the triangular faces using the feature elevation and slope values to generate an elevation grid layer. Then, the digital elevation model (DEM) was extracted and used to create a bathymetric surface to calculate volume comparing a studied period (1993, 2003, 2022) surface grids [47,48]. The Path Profile tool generated a cross-section of the analyzed surface to more accurately assess bathymetric features and seabed elevation changes. Elevation changes in 446 profiles every 50 m along the studied coast were calculated in the total.

3. Results

The bathymetry data were used to evaluate changes in the underwater bottom slope and calculate sediment volume changes. The GPS survey data from cross-shore profile measurements were used to estimate sediment volume changes in the beach area. Both data sets allowed to evaluate the alteration of sediment volume in a coastal zone. In order to identify the possible impact of the Port of Klaipėda reconstruction on coastal evolution, the study period was divided into two sections: 1993–2003 before reconstruction and 2003–2022 after the elongation of the port jetties. Hydrometeorological data were also analyzed for these periods separately.
According to calculations performed by Global Mapper (Figure 3) for the period 1993–2022, the net volume on the mainland coast was −429,631.47 m3, while on the Curonian Spit coast, it was −2,615,669.7 m3. Before Klaipėda seaport reconstruction, 1993–2003, the net sediment volume on the mainland coast was 348,070.61 m3, and on the Curonian Spit −4,633,217.1 m3. In the period after reconstruction, 2003–2022, sediment loss increased compared to the previous period to −1,520,535.2 m3 on the mainland coast. However, sediment loss decreased on the Curonian Spit respectively to −553,413.63 m3.
During the study period of 1993–2022 on both the Curonian Spit and the mainland coasts, average loss of sediments Q = −1148.98 m3/profile ± 294.29 m3/profile was observed. The average velocity of sediment volume change on the mainland was q = −0.02 (m3/m)/year ± 0.004 (m3/m)/year, while on the Curonian Spit coast, an average velocity of volume change was q = −0.03 (m3/m)/year ± 0.01 (m3/m)/year.
In order to represent geomorphological changes in the Lithuanian coastal zone, profiles from Karklė, Giruliai, Melnragė I, Smiltynė I, and Smiltynė II were chosen (Figure 4). In the period 1993–2022, in profile from Karklė (Figure 4), sediment loss was observed that reached −1253.68 m3/profile. Overland to the shoreline (0 m isoline), the observed profile volume changed a 30.74 m3/profile. In comparison, the underwater part to the −10 m depth experienced a sediment loss of −1290.84 m3/profile. In the most dynamic part, sediment accumulation was observed from 0 to −2.5 m depth, and sediment volume was 101.61 m3/profile.
In the profile from Giruliai (Figure 4), the total change in sediment volume was 94.34 m3. Overland sediment volume increased to 20.23 m3. In the swash zone, from 0 to −2.5 m depth, the sediment volume was 187.5 m3. However, the underwater part from −2.5 to −10 m depth experienced a loss of sediments, and the change reached −126.98 m3. The loss of sediment prevailed in profile from Melnragė I (Figure 4) and reached −159.51 m3. In the land part of the profile, the observed sediment volume change was −71.45 m3. From 0 to −2.5 m depth, the profile lost −62.45 m3 of sediments; in total, the underwater part of the profile lost −83.94 m3 of sand.
The positive shore formation processes were observed in the profile from Smiltynė I (Figure 4). Here, volume of sediment increased by 113.26 m3. Overland sediment volume increased by 29.79 m3. An accumulation was observed in a swash zone from 0 to −2.5 m depth, and the total change was 330.71 m3. In the remaining underwater part, to −10 m depth, sediment volume decreased by −203.44 m3. The total sediment volume change in profile from Smiltynė II (Figure 4) was −2089.22 m3. However, the overland part of the profile experienced an increase in sediment volume and reached 60.30 m3. From 0 to −2.5 m depth, sediment volume in this profile decreased by −20.58 m3; from −2.5 to −10 m depth, the sediment loss was −2134.14 m3.
According to hydrometeorological data analysis, during 1993–2021, westerly, south-westerly, and southerly winds prevailed in a study area, while during 1993–2019, wave directions were west and southwest (Figure 5). Throughout the study period, the prevailing wind speeds of 2–4 m/s and 4–6 m/s was observed, while the mean wave height was between 0–0.5 m and 0.5–1 m.
In 1993–2003, the sediment volume in the profile from Karklė (Figure 4) decreased by −1071.84 m3. Overland part of the profile to the shoreline, the volume of sediments increased by 30.37 m3/profile. The volume change reached −1287.77 m3/profile in the underwater part to −10 m depth. However, from 0 to −2.5 m depth, sediment volume changed by 95.45 m3/profile. The total change of sediment volume in the profile from Giruliai (Figure 4) was 77.23 m3. Overland sediment volume increased by 20.19 m3. The increase of sediment volume was observed underwater from 0 to −2.5 m depth and reached 185.29 m3. In contrast, the underwater part from −2.5 to −10 m experienced sediment loss of −125.85 m3. In the Melnragė I (Figure 4) profile, the sediment volume increase was observed and reached 913.66 m3. Overland, the volume of sediments in this profile increased by 58.62 m3. The sediment loss was observed from 0 to −2.5 m depth and reached −35.25 m3. However, in total, the sediment volume of the underwater part of the profile increased by 851.22 m3.
The volume of sediments in profile from Smiltynė I (Figure 4) increased by 428.31 m3. The overland part of the profile represents the accumulation process; here, sediment volume increased by 71.61 m3. In the swash zone of the profile (from 0 to −2.5 m depth), the sediment volume increased by 358.49 m3/m. In the rest of the underwater profile (to −10 m depth), the sediment volume changes reached 328.65 m3. In the profile from Smiltynė II (Figure 4), the total change in sediment volume was −1853.24 m3. However, the accumulation process prevailed on land; the total increase in sediment volume reached 206.74 m3. A total of −2066.66 m3 of sand was lost in the underwater part. From 0 to −2.5 m isobath profile lost −51.71 m3, and from −2.5 to −10 m, −2016.50 m3.
In 1993–2003, the wind direction slightly shifted to southerly directions, and an increase in the southeast directions of the waves were observed. The 2–4 m/s wind speed still prevailed. However, the increase in wind speed was observed at 4–6 m/s and 6–8 m/s. The 0–0.5 m mean wave height prevailed in all directions, and waves higher than 0.5 m were observed in the south, west, and northwest directions (Figure 6).
Between 2003 and 2022, the profile from Karklė (Figure 4) experienced a sediment loss of −166.82 m3/profile. However, on land up to the 0 m isobath (shoreline), the profile changed by 0.40 m3/profile. In the underwater part up to −10 m depth, the change in sediment volume was −147.96 m3/profile, and from 0 to −2.5 m isobath volume change in the profile was 1.47 m3/profile. The total change of sediment volume in the profile from Giruliai (Figure 4) was 101.07 m3. Overland, the volume changed to −1.60 m3. In the underwater part of the profile, from 0 to −2.5 m isobaths, the total amount of sediment decreased by −6.59 m3. However, the underwater part from −2.5 to −10 m isobath experienced an increase, which reached 110.32 m3. In the profile from Melnragė I (Figure 4), the total sediment volume change reached −1072.98 m3. Overland, the profile experienced a change of −65.36 m3 of sediments. From 0 to −2.5 m isobath profile lost −202.30 m3 of sand, in the total underwater part of the profile lost −1011.98 m3 of sand.
In the profile from Smiltynė I (Figure 4), the sediment volume changed by −277.19 m3. Overland, the loss of sediments was observed and reached −34.61 m3. From 0 to −2.5 m isobaths in the underwater part, sediment loss reached −17.5 m3. In the rest of the underwater profile, up to −10 m, the total sediment volume changed by −225.23 m3. In the profile from Smiltynė II (Figure 4), the total change in sediment volume was −251.13 m3. On land, the total change in sediment volume reached −96.69 m3. In total, −153.98 m3 of sand was lost in the underwater part, from 0 to −2.5 m isobaths, profile lost −4.07 m3 of sand, and from −2.5 to −10 m depth, −149.99 m3.
In the most recent decade of 2003–2022, the wind direction shifted to the south and southeast directions, and waves from westerly and south-westerly directions were observed. The prevailing wind speed was 2–4 m/s and 4–6 m/s, while the mean wave height was 0–0.5 m and 0.5–1 m (Figure 7).
Granulometric analysis was performed on the profiles by sampling at three points: the dynamic shoreline, the mid-beach, and the foredune (Figure 8). On the mainland coast, sediment type and sorting were dominated by well-sorted medium sand, slightly very fine gravelly coarse sand, slightly very fine gravelly medium sand, and very fine gravelly fine sand. The D50 size varied from 231.6 to 712.0 µm. On the Curonian Spit coast, sediment type and sorting were dominated by very well-sorted fine sand, well-sorted fine sand, and moderately well-sorted medium sand. The D50 size varied from 194.7 to 274.4 µm.
Profiles from Karklė, Giruliai, and Melnragė I represent the mainland coast, and according to grain size distribution since 2003, the sand is evenly distributed in the profiles but indicates a higher concentration of finer particles. At the same time, profiles from Smiltynė I and Smiltynė II represent the Curonian Spit coast. According to the grain size distribution, visible particles coarsen, indicating an occurring erosion process.

4. Discussion

The analyzed data allowed us to describe the evolution of coastal geomorphology affected by anthropogenic pressure (tourism, seaport activities, hydro-technical structures) and natural factors such as changes in hydrometeorological conditions.
The authority of the Port of Klaipėda, in 2014–2018, ordered 237.78 × 103 m3 of sand to be dumped on the nearshore of Melnragė and Giruliai beaches at 4–6 m depth [7] (Figure 1). This amount of sand was extracted while deepening the Klaipėda strait and used to nourish the mainland coast affected by erosion processes. Coastal erosion on the mainland coast is associated with local hydrodynamic conditions and hydro-technical constructions, mostly seaport jetties. On average, wave-induced longshore sediment transport is caused by the angular distribution of winds, and the position of the shoreline is northwards along the Curonian Spit and the Lithuanian mainland coast [37,38]. This prevailing sediment flow pattern means that changes in sediment availability or transport patterns along with these areas substantially affect the sediment budget northwards from Klaipėda. While sediment flows along the spit predominantly occur under natural conditions, further sediment transport to the mainland coast of Lithuania is blocked by jetties and breakwaters of Port of Klaipėda, out–flowing currents from Klaipėda Strait, and dredging of the port entrance channel [33,37]. Therefore, on the Curonian Spit coast, the predominant coastal process is accumulation, while on the mainland coast, erosion prevails [7].
The regime shift in wind direction discussed in previous works by authors [7] indicates morphological changes in the coastal zone. The morphology of most sandy beaches changes under wave conditions and is generally highly variable at the seasonal scale, with winter erosion and summer accretion [49]. In the Lithuanian coastal zone, wind-driven waves are observed [50]. Therefore, the shift in hydrometeorological conditions could alter the predominant sediment transport direction as well as the transported volume of sediments, and the erosion and accumulation processes could alternate.
The frequency of occurred wind speeds during the study period revealed the increased number of 2–4 m/s and 4–6 m/s wind speeds, which means lower wind speeds have an equal or more significant influence on the hydrodynamic processes that determine coastal geomorphology and development. Winds of those speeds continuously affect the shore, leading to a slower shore regeneration process.
Grain size distribution is a natural result of sediment transport processes, primarily related to the effects of erosion and accumulation [51,52]. Throughout the study period of 2003–2022, the grain size of the sediments on the mainland coast slightly became finer and evenly distributed in the profiles. This could be related to the beach replenishment work performed by the Port of Klaipėda Authorities. However, sediments became coarser on the Curonian Spit coast during 2003–2022. This observation proves the statement made by authors in earlier works where coastal erosion on both coasts has been detected by analyzing shoreline evolution [7].
The detection of changes in volumes of sediment during the study period was possible due to the analysis of bathymetry and cross-shore elevation data. The results revealed that in the period of 2003–2022, after the reconstruction of the Port of Klaipėda in 2002, both the Curonian Spit and the mainland coasts experienced the loss of sediments on land and underwater. This led to a steepening of underwater slopes and narrowing beaches on both coasts. The sediment loss after the seaport reconstruction is linked to the hydro-technical constructions and their configuration changes. The position of the north jetty of the Port of Klaipėda was changed, and the entrance channel has narrowed, causing the alteration in nearshore hydrodynamics and sediment circulation [53]. Throughout the entire study period from 1993 to 2022, steepening of the underwater bottom profile was observed in the nearest proximity to the Port of Klaipėda jetties (Figure 3); waves, therefore, reach the shore with higher energy. On the social aspect, such changes could be contradictory for beachgoers as a narrow beach could be less attractive for sunbathers that frequent recreational areas of the coastal zone. However, the strong winds are most favorable for extreme sports that are widely practiced along the coast.
Research in sediment transport both improves knowledge and provides diagnoses to decision-makers. Initially developed for civil engineering, this topic has been recognized as a scientific field. Science, to serve society, must make it possible to assess environmental hazards and vulnerability and identify early warning signs of critical transitions, and the general society should perceive sediment dynamics as a critical matter requiring attention [49]. Therefore, it is necessary to understand the involved processes better and to monitor and analyze the evolution of sediment budgets to adapt the information to be transferred to decision-makers in suitable forms for strategic planning [49,54].

5. Conclusions

In this study, the use of bathymetric data and cross-shore profiles to calculate elevation changes underwater as well as to estimate sediment volume and overland changes revealed that during a study period of 1993–2022, loss of sediments on both the Curonian Spit and the mainland coasts was on an average Q = −1148.98 m3/profile. After the Port of Klaipėda reconstruction, 2003–2022, sediment loss increased compared with the period before the renewal of jetties, and the net sediment volume on the mainland coast was −1,520,535.2 m3. Nevertheless, sediment loss decreased on the Curonian Spit coast, and the net sediment volume was −553,413.63 m3, verifying that the position and construction of the hydro-technical structures influence sediment flow along the coast.
Together with anthropogenic factors, hydrometeorological conditions are the key driver for coastal development tendencies. The evaluation of the coastal profile indicates a tendency for steepening of the underwater profile next to the jetties, causing the waves to reach the shore with higher energy. Recreational activities in the coastal zone are not among contributing factors of change. They are, however, under the direct influence of changes and highly dependent on planners’ decisions on how to adapt and mitigate the influencing ones.
The results of this study emphasize the need for monitoring sediment dynamics in the coastal zone to provide customized coastal development management methods such as beach nourishment or hard construction. Observing coastal processes specifies a need for strategic coastal management plans and demonstrates the current adapted tools work.

Author Contributions

Conceptualization, I.Š. and V.K.; methodology, I.Š. and V.K.; software, V.K.; validation, I.Š. and V.K.; formal analysis, I.Š.; investigation, I.Š.; data curation, I.Š., V.K. and E.B.; writing—original draft preparation, I.Š.; writing—review and editing, E.B. and L.K.-R.; visualization, V.K. and E.V.; supervision, L.K.-R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was partly funded by the Baltic Research Program (EEA Financial Mechanisms 2014–2021) project “Solutions to current and future problems on natural and constructed shorelines, eastern Baltic Sea” (EMP480).

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Acknowledgments

We would like to thank the Port of Klaipėda Authority for supporting this research and providing data.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Overview of the study site. ST1—Palanga Aviation meteorological station, ST2—Klaipėda meteorological station, ST3—Port of Klaipėda station.
Figure 1. Overview of the study site. ST1—Palanga Aviation meteorological station, ST2—Klaipėda meteorological station, ST3—Port of Klaipėda station.
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Figure 2. Geomorphological map of the study area.
Figure 2. Geomorphological map of the study area.
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Figure 3. Klaipėda district municipality’s coast (a) Karklė; Klaipėda city municipality’s official beaches: (b) Giruliai, (c) Melnragė I, (d) Smiltynė I, (e) Smiltynė II.
Figure 3. Klaipėda district municipality’s coast (a) Karklė; Klaipėda city municipality’s official beaches: (b) Giruliai, (c) Melnragė I, (d) Smiltynė I, (e) Smiltynė II.
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Figure 4. Elevation changes of the coastal zone on the Curonian Spit (A) and the mainland (B) coasts.
Figure 4. Elevation changes of the coastal zone on the Curonian Spit (A) and the mainland (B) coasts.
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Figure 5. The wind rose diagram for wind direction, and wind speed (m/s) from 1993 to 2021, and wave rose diagram for wave direction and mean wave height (m) from 1993 to 2019, the frequency distribution of wind speed (m/s) from 1993 to 2021, and frequency distribution of wave height (m) from 1993 to 2019.
Figure 5. The wind rose diagram for wind direction, and wind speed (m/s) from 1993 to 2021, and wave rose diagram for wave direction and mean wave height (m) from 1993 to 2019, the frequency distribution of wind speed (m/s) from 1993 to 2021, and frequency distribution of wave height (m) from 1993 to 2019.
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Figure 6. The wind rose diagram for wind direction and speed (m/s) from 1993 to 2003, a wave rose diagram for wave direction and mean wave height (m) from 1993 to 2003, the frequency distribution of wind speed (m/s) from 1993 to 2003, and frequency distribution of waves height (m) from 1993 to 2003.
Figure 6. The wind rose diagram for wind direction and speed (m/s) from 1993 to 2003, a wave rose diagram for wave direction and mean wave height (m) from 1993 to 2003, the frequency distribution of wind speed (m/s) from 1993 to 2003, and frequency distribution of waves height (m) from 1993 to 2003.
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Figure 7. The wind rose diagram for wind direction and speed (m/s) from 2003 to 2021, a wave rose diagram for wave direction and mean wave height (m) from 2003 to 2019, the frequency distribution of wind speed (m/s) from 2003 to 2021, and frequency distribution of wave height (m) from 2003 to 2019.
Figure 7. The wind rose diagram for wind direction and speed (m/s) from 2003 to 2021, a wave rose diagram for wave direction and mean wave height (m) from 2003 to 2019, the frequency distribution of wind speed (m/s) from 2003 to 2021, and frequency distribution of wave height (m) from 2003 to 2019.
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Figure 8. Grain size composition of surface sediments at profiles from Karklė, where a—dynamic shoreline, b—mid-beach, and c—foredune; Giruliai, where a—dynamic shoreline, b—mid-beach, and c—foredune; Melnragė I, where a—dynamic shoreline, b—mid-beach, and c—foredune; Smiltynė I, where a—dynamic shoreline, b—mid-beach, and c—foredune; Smiltynė II, where a—dynamic shoreline, b—mid-beach, and c—foredune, throughout 2003 (red line), 2012 (orange line), and 2022 (yellow line) years.
Figure 8. Grain size composition of surface sediments at profiles from Karklė, where a—dynamic shoreline, b—mid-beach, and c—foredune; Giruliai, where a—dynamic shoreline, b—mid-beach, and c—foredune; Melnragė I, where a—dynamic shoreline, b—mid-beach, and c—foredune; Smiltynė I, where a—dynamic shoreline, b—mid-beach, and c—foredune; Smiltynė II, where a—dynamic shoreline, b—mid-beach, and c—foredune, throughout 2003 (red line), 2012 (orange line), and 2022 (yellow line) years.
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MDPI and ACS Style

Šakurova, I.; Kondrat, V.; Baltranaitė, E.; Vasiliauskienė, E.; Kelpšaitė-Rimkienė, L. Assessment of Coastal Morphology on the South-Eastern Baltic Sea Coast: The Case of Lithuania. Water 2023, 15, 79. https://doi.org/10.3390/w15010079

AMA Style

Šakurova I, Kondrat V, Baltranaitė E, Vasiliauskienė E, Kelpšaitė-Rimkienė L. Assessment of Coastal Morphology on the South-Eastern Baltic Sea Coast: The Case of Lithuania. Water. 2023; 15(1):79. https://doi.org/10.3390/w15010079

Chicago/Turabian Style

Šakurova, Ilona, Vitalijus Kondrat, Eglė Baltranaitė, Erika Vasiliauskienė, and Loreta Kelpšaitė-Rimkienė. 2023. "Assessment of Coastal Morphology on the South-Eastern Baltic Sea Coast: The Case of Lithuania" Water 15, no. 1: 79. https://doi.org/10.3390/w15010079

APA Style

Šakurova, I., Kondrat, V., Baltranaitė, E., Vasiliauskienė, E., & Kelpšaitė-Rimkienė, L. (2023). Assessment of Coastal Morphology on the South-Eastern Baltic Sea Coast: The Case of Lithuania. Water, 15(1), 79. https://doi.org/10.3390/w15010079

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