Research article Quarterly Journal of Engineering Geology and Hydrogeology https://doi.org/10.1144/qjegh2020-036 | Vol. 54 | 2020 | qjegh2020-036

Coastal processes in the Russian Baltic (eastern Gulf of Finland and area)

Daria Ryabchuk1*, Alexander Sergeev1, Evgeny Burnashev2, Viktor Khorikov1, Igor Neevin1, Olga Kovaleva1, Leonid Budanov1, Vladimir Zhamoida1 and Aleksandr Danchenkov3,4 1 A.P. Karpinsky Russian Geological Research Institute, 74 Sredny pr., St Petersburg 199106, 2 State Budgetary Institution of Kaliningrad “Baltberegozaschita”, Khutorskaya st. 1, Svetlogorsk 238560, Russia 3 Shirshov Institute of Oceanology, Russian Academy of Sciences, 36 Nahimovskiy prospekt, Moscow 117997, Russia 4 I. Kant Baltic Federal University, 14 Nevskogo A. str., Kaliningrad 236016, Russia DR, 0000-0003-2266-8688; AD, 0000-0002-1710-3757; AD, 0000-0002-1710-3757 * Correspondence: [email protected]

Abstract: The results of both onshore and offshore monitoring of the coastal zone in the Russian Baltic reveal the high intensity and recent acceleration of coastal dynamics caused by an increasing frequency of extreme hydrodynamic events and anthropogenic impacts on the diverse geology. Stable coasts dominate in the eastern Gulf of Finland, but the local rate of shoreline recession is up to 2.0 m a−1, reaching 5 m in one extreme storm event. The coastal zone of the Kaliningrad area is diverse. The western coast of the Sambia Peninsula is controlled by anthropogenic influences linked to the exploitation of geological resources. The beaches advance when the supply of artificial sediments from opencast mines increases, whereas the shoreline retreat reaches 10–20 m a−1 when the input is interrupted. Active landslides and beach degradation dominate along the northern coast of the Sambia Peninsula. Large areas of pre-Quaternary deposits, outcrops and boulders in the nearshore provide evidence of sediment deficiency offshore. The coastal geological hazards are dependent on climate. A comprehensive understanding of the main trends in climate change is important for predicting and mitigating future damage to the coastal infrastructure and for selecting adaptation strategies. Thematic collection: This article is part of the Mapping the Geology and Topography of the European Seas (EMODnet) collection available at: https://www.lyellcollection.org/cc/EMODnet Received 11 February 2020; revised 18 May 2020; accepted 2 July 2020

The is an intra-European, transboundary water basin. The Baltic, to +10 mm a−1 at the top of the (Harff et al. surrounding are densely populated and the drainage area is 2017). The impact of waves on the coastal zone of the Baltic Sea highly developed economically (Fig. 1b). Geological mapping of differs significantly depending on the geographical position, the floor of the Baltic Sea is one of the most interesting and shoreline configuration and wave fetch. challenging tasks in the EMODnet-geology project because the The coastal zone of the Russian Baltic consists of two distinct seamless maps are compiled by ten partner institutions from nine areas: the easternmost part of the Gulf of Finland and the SE Baltic countries, each with a long history of different mapping approaches within the Kaliningrad area (Fig. 1b). The southern coast of the and classification techniques. From the perspective of the Russian Gulf of Finland experiences similar processes to the EMODnet-geology Work Package 4 (Coastal Behaviour), the adjoining Estonian shores, whereas the skerries of the NW resemble most remarkable feature of the Baltic Sea is its great variety of much of the Finnish coast of the Gulf. The coasts in the Kaliningrad coastal types. These are a result of differences in the geological area consist of the high cliffs of the Sambia Peninsula and two structure of the various regions of the Baltic area and the diversity of significant sediment accretion bodies: the , shared with land movement, with sinking southwestern and uplifting north- to the SW, and the , the northeastern half of eastern coastal areas (Harff et al. 2011). The main geological which lies in . Both segments of the Russian Baltic are features of the Baltic Basin are controlled by its position between characterized by intense coastal erosion, with a wide spectrum of the Fennoscandian crystalline shield, represented by Precambrian landslides evident on the coastal cliffs of the Sambia Peninsula. magmatic and metamorphic rocks, and the East European Platform, The coastal areas and beaches of the two parts of the Russian characterized by Phanerozoic sedimentary cover, the thickness of Baltic are highly valuable from the perspective of both recreation which increases by up to several kilometres from NE to SW (Šliaupa and nature protection and are under great pressure from anthropo- and Hoth 2011). The hard metamorphic and magmatic rocks of the genic activity. The urgent need for an effective coastal protection Scandanavian Shield outcrop along the northern coasts of the Gulf strategy is recognized by the local authorities and is in the early of Finland, the Gulf of Bothnia and the western Baltic Proper. stages of development. Such a strategy needs to be based on a clear Quaternary deposits are widespread along the southern Baltic scientific understanding of natural coastal processes, taking into coasts, but, in the areas where these are eroded, the coastal cliffs are consideration both marine and geological factors and identifying the composed of relatively easily erodible Ordovician and Devonian (in main trends in the current and future evolution of the shoreline. Estonia) and Paleogene–Neogene (in the SE Baltic, including the Our work aimed to identify the main trends in the evolution of the Kaliningrad area) sedimentary rocks. The rates of glacio-isostatic coastline and to calculate the rates of shoreline retreat or advance, rebound along the Baltic coast vary from −1.5 mm a−1 in the SE mapping the coastal geology and identifying hotspots of coastal

© 2020 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License (http://creativecommons.org/ licenses/by/4.0/). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics

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Fig. 1. (a) Morphogenetic classification and coastal dynamics of the Eastern Gulf of Finland. The measuring points are points of retrospective analyses of coastal escarpments and beach positions based on remote sensing data (rates in units of ma−1); relict uplifted Holocene marine terraces are terraces formed during the maximum of Holocene transgressions (Lake Ancylus and the Littorina Sea) and are mostly covered by sand; coastal types are morphogenetic coastal types (see Table 1). (b) Location map of the study area. FPF, St Petersburg Flood Protection Facility.

erosion. Our aim was to link the occurrence of different lithologies dynamics of the Kaliningrad Region have been continued since with different coastal behaviours, revealing the natural and 1972 by the Agency of Coastal Engineering, later reorganized as the anthropogenic driving forces of coastline dynamics, and to Bureau Baltberegozashita (Boldyrev et al. 1990; Ryabkova 2000; propose a strategy for coastal management and protection. Boldyrev and Ryabkova 2001). There is a long history of previous research in this region, with the Hydrological studies carried out by the ABIO RAS from 1980 to first scientific investigation of the geology and coastal processes of the late 1990s classified the near-bottom currents from the shoreline the SE Baltic published at the beginning of the twentieth century. to the outer boundary of the coastal zone and determined the Abromeit et al. (1900) described the geomorphological features of existence of sediment transport towards the east (Babakov 2002). the coastal zone and the problem of dune stability. Tornquist (1914) The most recent overview of the coastal geology was presented by considered the problems of sediment drift and the impact of storms Zhindarev et al. (2012). on the Curonian Spit. Based on field observations during the winter The Laboratory of Coastal Systems of ABIO RAS has conducted storm of 9–10 January 1914, he showed that the coastal system may coastal monitoring studies along the shores of the Kaliningrad area lose twice as much material during a single extreme storm event as it since the year 2000. Numerous annual cross-shore profiles have accumulates over a whole year. Data on the geological structure of been measured using permanent concrete benchmarks as fixed the Quaternary deposits and erratic blocks of Cretaceous rocks near points to calculate the rates of coastal erosion (Bobykina and the Curonian Spit were published in 1919 (Wichdorff 1919). Boldyrev 2008). The coastal zone and nearshore bottom dynamics The first map of the Quaternary deposits of the Kaliningrad of the Curonian Spit were analysed by Zhamoida et al. (2009). Region was compiled by Vereisky in 1946 (Vereisky 1946). The geology and geomorphology of the Eastern Gulf of Finland Complex hydrogeological investigations between 1958 and 1967 (EGoF) coasts have been studied since the 1920s (Yakovlev 1925; enabled the development of onshore geological, hydrogeological Markov 1931). Coastal processes were first investigated by and geomorphological maps at a scale of 1:200 000 (Zagorodnyh researchers from the University of Leningrad in the 1970s and Kunaeva 2005). The first aerial survey of the SE Baltic coastal (Barkov 1989). An overview of the geology, geological history zone was carried out by the Atlantic Branch of the Institute of and the first classification of the coasts of the EGoF area was Oceanology (ABIO RAS) in 1960 (Boldyrev et al. 1990). Repeated presented by Raukas and Hyvärinen (1992). The first geological bathymetric measurements – accompanied by sediment sampling, description of the Russian coast of the Gulf of Finland was beach levelling, geomorphological observations by scuba divers, published by K. Orviku in 1992 (Orviku and Granö 1992). The sampling of suspended sediment and measurements of hydro- authors of the current paper have discussed some aspects of coastal dynamic parameters (waves and current) – were carried out at the zone dynamics (e.g. Ryabchuk et al. 2011a, b, 2014; Spiridonov same time (Aibulatov et al. 1966). Further studies of the coastal et al. 2011; Kosyan et al. 2013; Sergeev et al. 2018). The current

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Table 1. Parameters of coastal dynamics for different coastal types of the Eastern Gulf of Finland based on the classification of Shepard (1948)

Average rate of cross-shore Average rate of longshore Legend coastal dynamics (m a−1) dynamics (spits, sand waves) − No. Coastal type Description (number of measurements) (m a 1) (number of spits) 1 Skerries Primary coasts: drowned glacial erosion coasts. 0.05 (2) 0 Embayed coasts consist of hard rocks 2 Sand accretion alluvial coast Primary coasts: river deposition coasts. Coasts of 0.1 (6) 0 deltas and estuaries 3 Moraine (boulder) erosion Primary coasts: glacial deposition coasts. Coasts −0.1 (69) 18 (2) coast with local pockets of consist of moraine deposits developed following coarse-grained beaches erosional processes 4 Erosion-dominated coast on Secondary coasts: wave erosion coasts. Permanently −0.25 (43) 47 (3) Holocene marine terrace, straightening coasts consisting of soft Holocene straightening deposits, erosional processes are developed within marine palaeoterraces 5 Erosion-dominated coast on Secondary coasts: wave erosion coasts. −0.5 (4) 30 (1) Holocene marine terrace, Straightening of coasts is finished, coasts consist straightened of soft Holocene deposits, erosional processes are developed within marine palaeoterraces 6 Sand accretion coast Secondary coasts: marine depositional coasts. 0.2 (9) 16 (1) Accumulative processes are dominant as a result of sediment inflow 7 Sand accretion coast with Secondary coasts: marine depositional coasts. −0.7 (5) 14 (4) cuspate foreland Movement of beach sand spits is observed combined with accumulative processes 8 Technogenic coast (with hard No natural development of coasts due to coastal protection technogenic impact (coastal protection) structures)

paper presents the first regional study based on a combination of and georeferenced (WGS-84, Baltic System of Heights 1977) along comprehensive geological and geomorphological datasets and the 145 km of coastline. Measurements are carried out both seaward results of long-term coastal monitoring. and landward from the ground marks, with the datasets including the distance between the ground mark and the base and edge of the Materials and methods coastal escarpment, the foredune base and the shoreline. Comparative analyses of the results allows different parameters of Fieldwork the coastal zone dynamics to be distinguished. The precision of the measurements is at the centimetre scale, not exceeding several The Russian Geological Research Institute (VSEGEI) has carried centimetres. As a result, a significant dataset has been collected for out geological mapping and research since the 1980s and there has the last ten years (2008–18) for all coasts and for a period of 19 years been annual state (federal) monitoring of the geological environ- (2000–18) for most of the representative coastal segments. These ment of the Russian Baltic since 2011. The Regional Program of St data can be used to analyse the main dynamic trends of the coast to Petersburg City Coast Protection Strategy development was carried identify the key driving forces (e.g. storm activity and frequency) out in 2015–16. The main methodological approach of coastal zone and to calculate the sensitivity and vulnerability of the coast in monitoring combines methods of onshore monitoring (e.g. remote relation to the geological properties. Coastal monitoring also sensing data (RSD), observations, levelling, terrestrial laser includes the analysis of RSD, aerial laser scanning, aerial scanning (TLS), unmanned aerial vehicle surveys, ground penetra- photographic surveys, the technical monitoring of coastal protection tion radar and profiling) and offshore surveys (e.g. sub-bottom constructions, bathymetric surveys and sediment sampling of the profiling, sidescan sonar profiling, sediment sampling and nearshore bottom, together with analyses of geodesic, hydrome- submarine video survey; for some areas, also multibeam profiling). teorological, geological, environmental and hydrotechnical surveys Offshore research has mapped the nearshore bottom to reveal areas and scientific publications. of bottom erosion and an absence of recent sediment cover (sands or gravel). Engineering geological studies of coastal transects, from Retrospective analyses of topographic maps, aerial – the shoreline to cliff edge, were carried out by VSEGEI in 2015 19. photographs and RSD Five transects were monitored annually in the Kaliningrad coastal zone and three in the EGoF. Research included sediment sampling Topographic maps at a scale of 1:25 000, based on late nineteenth for grain size analysis, the determination of physical and mechanical century surveys and published in the early twentieth century, were properties, and strength testing of clays with portable penetrometer used to determine the long-term trends of changes in the coastline of and field vane tests. the EGoF. Digitization and geographical information system (GIS) Annual monitoring measurements have also been undertaken in analyses (ArcGIS 10.0) of 89 topographic map sheets at a scale of the SE Baltic by the State Budgetary Institution of Kaliningrad 1:50 000, published in the 1960s and covering most of the studied Region (‘Baltberegozaschita’) and the Atlantic Branch of the P.P. coastal areas, allowed us to trace specific relict coastal accretion Shirshov Institute of Oceanology (ABIO RAS). Seventy regular forms that are currently located at different altitudes to reveal ground marks were established in 2000–02 for repeat measurements changes in the coastline. Georeferencing of these maps was carried and the number was increased to 285 marks in 2008. Monitoring out based on the position of the same objects (buildings, roads) that includes measurements of the lithology, sediment characteristics have been preserved since that time. We digitized four archival and the relief of submarine coastal slope, beach and foredune topographic maps published in 1908 and corrected in 1926 at a scale dynamics. The 285 ground marks are installed at 500 m intervals of 1:25 000 (Gr. Dirschkeim, Rauschen, Neukuhren, Palmnicken;

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(Geographisches Institute 1908a, b, c, d)) to analyse the long-term 2017). The northern coast, from the Finnish–Russian boundary to coastal transformation of the Kaliningrad coasts. The results of the Beriozovy Archipelago, consists of skerries, with numerous retrospective analyses showed the high accuracy of the topographic islands and small barrow bays formed by igneous and metamorphic maps, allowing us to trace the position of the coastal escarpment and rocks and partly covered by till. The most widespread type of coast, to calculate its rate of retreat relative to modern satellite images from formed as a result of the erosion of Late Pleistocene moraine, is 2013 (available via Google Earth). characterized by erosion scarps fronted by boulder benches in the The recent coastal dynamics of the EGoF were studied using nearshore zone. Our results indicate that the embayed coasts are satellite imagery available via Google Earth for most parts of the straightening as the result of the accumulation of sediment. Sand coast. We used Landsat 1–7 images (cell size 80–30 m) for the accretion coasts with wide (50–150 m), stable sand beaches are period 1984–2005 and high-resolution satellite images with cell observed in Narva Bay and in front of Sestroretsk town. The size of several tens of centimetres for the period 2005–18. We used easternmost part of the studied coasts, within the mouth of the Neva aerial photographs from 15 August 1939 for analyses of RSD for the River, has been largely transformed by technogenic processes. coastal dynamics of Kotlin Island. We used high-resolution aerial About 70% of this coast (82 km over 118 km of shoreline) consists photographs from 1990 to analyse the southern coast of the Gulf of of embankments, coastal protection structures and other techno- Finland near Bolshaya Izhora village. Analyses of the full set of genic constructions. The St Petersburg Flood Protection Facility satellite images enabled us not only to fix the initial and final points (FPF) (Fig. 1) has played an important part in the recent evolution of of the position of the coastline, but also to identify the dynamics of the coastline. its transformation in relation to its geological composition, Hazardous floods have threatened the population of St Petersburg including the formation, mobility and destruction of sand spits since its foundation and the earliest plans to protect the city date and bars. The analyses for some of the most dynamic coastal areas from just after the catastrophic flood of 1824. In 1858, in his report are also based on annual field observations, levelling and to the Russian Geographical Society, E. Tillo presented eight retrospective analyses of very high-resolution satellite images different potential projects for the defence of St Petersburg from available from earlier published studies (Leont’ev et al. 2011; floods (Tillo 1893). One of these proposed projects was developed Ryabchenko et al. 2018; Sergeev et al. 2018). in 1824–27 by Pierre Dominic Basen. There was no further development until after the Second World War, when discussions Terrestrial laser scanning began again at a new, more technical level. As a consequence, construction work on a huge hydrotechnical structure, the FPF, The TLS data were collected for the Sambia Peninsula coast in began in 1979. The construction of the FPF was interrupted in the August 2016 and August 2017 using the TOPCON GLS-1500 1990s as a result of the need to carry out an ecological risk system. The accuracy of the determination of distances and angles assessment, but it was continued in the late 2000s. The FPF, one of was 4 mm for 150 m of measurements and the angular accuracy was the largest hydrotechnical constructions in the Gulf of Finland (total −5 2.9 × 10 rad. The scanning system was equipped with a sensor length 25.4 km, height 6.4 m above the average long-term water system for self-calibration and the elimination of levelling errors, a level), has been fully functional since 2011 (Ryabchuk et al. 2017). collimator and a rotation system that started before each launch and The FPF consists of 11 dams, six water sluices and two did not require manual calibration (Topcon Inc. 2010). Co- navigation gates (https://dambaspb.ru/#intro). Its function is registration of the TLS data was performed by the back-sight important in the protection of the city of St Petersburg from method using the target installed on the tripod and the GNSS flooding, but in the 1990s there was a discussion about its possible receiver TOPCON GR-5. Differential correction was obtained from impact on the environmental status of the EGoF and Neva Bay in the internal network of the base stations. Digital elevation models particular. Consideration was given to the risk of increasing the were developed using ArcGIS 10.0 with the Natural Neighbor tool pollution of water and bottom sediments with hazardous substances, for the linear interpolation of point data to compare the results of the such as heavy metals, as a result of the interaction of the FPF with TLS point clouds. The GRID cell size was set at 0.1 m. waste water from St Petersburg. Testing and monitoring of the TLS was carried out in the EGoF coasts over the time period bottom sediments revealed no negative impact of the FPF, but 2012–17 by Alpha-Morion Ltd using the RIEGL VZ-400 system instead indicated a generally decreasing trend in the concentration of from 12 stable points (scan positions). Geodetic referencing to the hazardous substances since the 1980s (Ryabchuk et al. 2017). This local coordinate system SK64 and the Baltic System of Heights decrease in heavy metal concentrations was attributed to decreasing 1977 was established using a Trimble R8 and the Javad Legacy-E anthropogenic loads in the 1990s and, since the 2000s, the efforts of satellite. Post-processing was performed using Pinnacle software. the VODOKANAL State Enterprise to improve water treatment in The horizontal and vertical fixes of the position marks were made St Petersburg (www.vodokanal.spb.ru/en). using a LEICA TS06 Ultra (2″) total station. Low coasts dominate within the EGoF. The average height of the recent marine terrace is 1–2 m, with the exception of 30 m high cliffs Data management and GIS occurring in unconsolidated sediments near Krasnaya Gorka village. The coasts of the EGoF are exposed to the influence of multi- The results of the annual monitoring are collated as GIS maps. The directional waves. The most dramatic impact on the coasts is caused by results received in the frame of coastal monitoring in the SE Baltic westerly and southwesterly waves associated with the prevailing wind are integrated within the Informational System of Kaliningrad direction (Ryabchuk et al. 2011a), with the coasts of the Kurortny Region using an online resource (www.bbz39.ru/ipas) for the region, Lebyazhye village, Kotlin Island and Narva Bay being the development of a state coast protection strategy. most vulnerable. The wave energy along these coasts increases during the autumn and winter (Kovaleva et al. 2017) when the unprotected Results and exposed coasts can retreat significantly. However, the erosive Eastern Gulf of Finland effects of the waves may be mitigated by the stable ice cover that usually forms in late November (Soloshchuk 2010), thus reducing the The Russian part of the Gulf of Finland shoreline, not accounting erosional consequences associated with surge storm events. The for the islands, is c. 520 km long (Fig. 1). A key feature of the EGoF waves and currents induce the normal longshore and cross-shore is a very low rate of uplift (0 to +3 mm a−1) and a near-zero rate of transport of sediments during calm periods in spring and summer, recent sea-level change (Gordeeva and Malinin 2014; Harff et al. which does not significantly reshape the beach profiles.

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Based on RSD analyses, the coasts of the EGoF can be segment. The average rate of coastline retreat was 0.25–0.5 m a−1, subdivided into four types:(1) erosion-dominated (foredune reaching 1.2–1.6 m a−1 on the more exposed parts of the coast erosion or retreat of the coastal escarpment); (2) accumulative (Fig. 2b). The maximum rate of erosion of up to 2 m a−1 was (beach aggradation, stable foredune); (3) intense longshore sand recorded on the most western part of the island (Ryabchenko et al. drift sufficient to develop sand spits and longshore sand waves; and 2018). (4) stable (skerries and technogenic) (Fig. 1). Combined analyses of The coast to the west of Lebyazhye village (on the southern coast monitoring observations and RSD have enabled the identification of of the Gulf of Finland) differs from the neighbouring shores by the the most dynamic parts of the EGoF coast as the shores of the presence of an active coastal cliff up to 15–20 m high and composed Kurortny district of St Petersburg, the western coast of Kotlin Island of sandy sediments and boulder sandy loams (silty clay with and the southern coast of the Gulf between Lebyazhye and Bolshaya boulders). Boulders and coarse-grained sand prevail on the surface Izhora villages. of the beach. The lower part of the cliff is composed of sub- The average rate of retreat of the coastal escarpment within horizontal layers of boulder–pebble deposits. Several of these layers erosion-dominant coasts is 0.25 m a−1. This increases locally to can be traced along the cliffs because of their large boulder content. 1.5–2.0 m a−1 and, during severe storms, the escarpment can retreat The upper part of the cliff is composed of layers of sand, pebbles landward by up to 5 m per storm (Ryabchuk et al. 2014). Such high- and gravel. The geotechnical properties of deposits are shown in magnitude erosional events have recently become more frequent Figure 3. and have been observed four times since 2004. The coastal area of Repeated TLS surveys of the beach surface and coastal cliff in Kurortny district is exposed to the greatest erosion under the impact 2016 and 2017 showed that slope erosion occurs primarily due to of westerly and southwesterly storms. The longest series of levelling intense landslides triggered by surplus rainfall. The volume of measurements of the beach cross-sectional profile and the results of material displaced downslope reached 5.8 m³ for each metre of repeated TLS surveys for Komarovo village showed that the average shoreline. An analysis of satellite images from 2005 to 2018 showed annual rate of erosion of the beach-face escarpment from 1988 to that the edge of the coastal escarpment retreated landward by 13 m 2018 was 0.9 m a−1 (Sergeev et al. 2018). This long-term rate of (c. 0.8 m a−1). Sand accretion is observed locally, mainly near the erosion masks significant annual variations, whereby there may be mouths of rivers, and results in the formation of stable beaches up to 0 m of erosion over several consecutive calm years, followed by 5 m 100 m wide. There is no advancing sand beach within the study during an extreme storm event. Similarly, following a series of area. storms in 2011, the coastal cliff retreated landward by up to 6.5 m. The dynamics of the spit coast are the most active. Several small We calculated the volume of sand as a difference between the beach short-term sand spits (up to 100 m long) shifting in an easterly surfaces for each year using only TLS data collected annually from direction at an average rate of 30–60 m a−1 were observed within the 2012 to 2017. The total balance showed a reduction in beach northeastern coast of the Gulf of Finland between 2013 and 2018 sediments of 413 m³ along a 90 m segment. The average loss of (Fig. 1). Much larger sand spits up to 1100 m long and 200 m wide sand as a result of storms over this five-year period was 4.5 m³ per occur on the southern coast near Bolshaya Izhora village (Ryabchuk metre of shoreline. et al. 2011b). The special features of the geological structure of the Analysis of RSD for the western coast of Kotlin Island over a time coastal zone here include a sufficient volume of sand material, period of 76 years, using aerial photographs from 15 August 1939 produced by onshore and offshore erosion of the Holocene sand and a high-resolution satellite image from 2015, shows that the terrace, which has resulted in the development of dynamic forms of alongshore transport of sand material and alignment of the coastal coastal relief referred to as ‘alongshore sandy waves’ (Leont’ev contours are dominant here, with the intense erosion of capes and et al. 2011). The shoreline contour of the seaward edge of the the filling of small bays. The capes were eroded and sediment contemporary marine sand spit is characterized by a smooth curving accumulation was observed in the eastern part of this coastal shape. An important feature of the observed large sand cusps,

Fig. 2. (a, b) Photographs of coasts and (c) areas of erosion and accumulation on the shoreline of Kotlin Island digitized from aerial photographs on 15 August 1939 and satellite image in 2015 (Ryabchenko et al. 2018).

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Fig. 3. Monitoring (2016–19) of coastal cross-section of the southern coast of the Eastern Gulf of Finland near Lebyazhye village. (a) Description of cross- section (2018) with positions of samples. (b) Aerial photograph taken by an unmanned aerial vehicle. (c) Model of coastal relief with slope angles.

longshore sand waves, is an increase in their size, both length and nearshore of Kotlin Island and the submarine periphery of some amplitude, in an easterly direction. The amplitude of the cusps capes. The results of these investigations have revealed a deficit of increases to the east from 15 to 100 m with straight shoreline nearshore sediments (Ryabchuk et al. 2011a; Ryabchenko et al. segments down-drift. Comparison of RSD and annual field 2018) and the results presented here support close links between the monitoring results showed that, over the period of observations sediment balance offshore and the onshore rate of coastal erosion. from 2011 to 2018, the annual alongshore displacement of the ‘ ’ – −1 waves reached 8 20 m a (Fig. 4). Although the beach is eroded SE Baltic from the west side of the protruding section of the coast (‘waves’), the whole sand wave feature is migrating along the coast in an The coasts of the Kaliningrad sector of the SE Baltic can be easterly direction. Similar coastal forms are observed along the genetically subdivided into the erosion-dominated Sambia western shore of Kotlin Island. The development of these longshore Peninsula shore and two accretion-dominated spits: Vistula and sand waves is explained by the fact that the prevailing waves, Curonian. Ten different coastal subtypes can be distinguished based induced by westerly winds, are propagated almost parallel to the on their morphology and recent processes trends (Petrov 2010). shoreline. The shape of the shoreline of the Sambia Peninsula (Fig. 5), with The nearshore areas of the most heavily eroded segments of the an alternation of capes and bays, is caused by long-term selective EGoF coastal zone are fully covered by sidescan sonar profiling erosion of the coastal cliffs, which are composed of unconsolidated surveys. These surveys have revealed the occurrence of vast areas of sandy and clayey Paleogene, Neogene and Quaternary deposits boulder–pebble sediments, dominating at water depths of 0–5m, (Zhindarev et al. 2012). The height of the cliffs decreases gradually along the northern coasts of the outer Neva Bay estuary, the in the eastern and southern directions from 55 to 5–10 m. The

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Fig. 4. Longshore sand waves and spit development near Bolshaya Izhora village. (a) Transformation of coastline in 1990–2019 based on aerial photography and analyses of satellite images. (b) Aerial image of the eastern part of the hooked spits.

escarpments of both the western Sambia Peninsula, south of Cape Author Team 2015). A pronounced annual pattern of wind waves is Taran, and the northern Sambia, east of the Cape, are dissected by observed: a decrease in wave height during the spring–summer numerous ravines. period (0.6–0.7 m) and an increase in the autumn–winter period Cross-sections of the coastal escarpment show that the cliffs (0.8–0.9 m) (Rózynskí 2010; Zaitseva-Pärnaste et al. 2011). Storm consist of alternating, relatively thin (1–10 m) layers of variable waves (>2 m high) occur in <5% of all observations (Kelpšaitėet al. grain size sands, sandy loams (silts), clayey loams (silty clays), clays 2008). Southwesterly waves (1.4–1.8%), to which both the northern and coarse-grained sediments. The geotechnical properties of these and western coasts of the Sambia Peninsula are exposed, have the layers differ slightly, but they are predominantly unconsolidated and highest frequency. Typical wave periods are 3–6s(Kahma et al. easily erodible (Figs 6 and 7). 2003; Soomere 2008). There has been a significant increase in the The cliff near the village of Donskoye has a very heterogeneous occurrence of southwesterly winds from 15 to 25% during the last structure. Unconsolidated deposits of different grain sizes form four decades, associated with a positive North Atlantic Oscillation many layers. The sands, as shown in Figure 6, vary in grain size index (Kelpšaitėet al. 2011). The air pressure is higher than average from silty sands to coarse-grained sands. The clay layers of the cliff over the southern part of the North Atlantic or lower than average are thin with a moisture content of 23–26% and a density of 1.87– over the northern part of the North Atlantic when the North Atlantic 2.02 g cm−3. The cemented sands of the upper part of the cliff, Oscillation index is positive (Dailidienėet al. 2006). The modern where the slope angle reaches 90°, are characterized by the highest evolution of the Sambia Peninsula coasts is driven by a complex level of hazard from mass movements. system of currents, controlled by winds, their direction and the The cliff in Filino village (Fig. 7) is composed mainly of morphology of the underwater slopes (Babakov 2002). The most medium-grained sandy sediments, which are densely folded in the severe erosional events, accompanied by the transfer of nearshore lower part of the cliff, forming a vertical wall. The sands of the sediments, are observed during short, but intense, storms of 1–2 upper part of the cliff are more friable. The top 3–4 m are days duration. The beach systems are partly regenerated between represented by silt with a high content of boulders and pebbles, a these storm events (Boldyrev et al. 1990). low moisture content (16.2%) and a density of 2.11 g cm−3. Both the northern and western coasts of the Sambia Peninsula are The wave activity in the SE Baltic Sea is caused by the shallow characterized by active sediment dynamics (Fig. 5). The western water and a semi-closed position and is determined by the direction coast of the Sambia Peninsula is an outstanding example of a of the winds and the interaction of waves with the seafloor (BACC positive anthropogenic impact on shoreline evolution, whereby

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Fig. 5. (A) Schematic diagram of morphogenetic classification and coastal dynamics of Sambia Peninsula. 1–7, morphogenetic coastal types (legend in Table 2); 8, measuring points of Baltberegozaschita; 9, points of retrospective analyses of coastal escarpment and beach position according to remote − sensing data (rates of escarpment shift in m a 1) with photographs of the coastal cliffs of the northern coast of Sambia Peninsula. a, b, landslides and erosion processes; c, glacial dislocations of Quaternary deposits; d, e, panoramic view of the geological structures of the coastal cliffs of Svetlogorsk town. Q, Quaternary deposits; N, Neogene deposits; P, Paleogene deposits. (B) Location map of the study area.

large volumes of sediment are provided to the coast from mining south of Okynevo (Fig. 8). Since 1958 the amber mining factory, activities. Early twentieth century topographic maps show an located onshore in Yantarny settlement, annually dumped 1.5– embayed shoreline. The shoreline was embayed to c. 150 m near 4.5 Mt of clayey sand mining waste from the extraction of amber Sinyavino settlement, c. 700 m near Yantarny and c. 300 m to the into the Baltic Sea (Bass and Zhindarev 2007; Bobikina and

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Fig. 6. Monitoring (2016–19) of coastal cross-section of the western coast of Sambia Peninsula near Donskoye village. (a) Representative description of cross-section (2018) with positions of samples. (b) Aerial photograph taken by unmanned aerial vehicle. fg, fluvio glacial deposits; N1, early Neogene. (c) Model of coastal relief with slope angles.

Karmanov 2009). This dumped material was incorporated into Sambia Peninsula, illustrating the sensitivity of the coastal zone to cross-shore and longshore sediment drift. By the 1970s it had technogenic impacts. The sediment supply from even small onshore resulted in the formation of an 800 m wide and 5.5 km long dumps, c. 100–200 m long, can initiate progradation of the coastline anthropogenic accretion terrace and local foredune belt along the of up to 15–20 m per year and any attempt to illegally mine amber shoreline between Yantarny and Sinyavino. The volume of can trigger an acceleration of erosion. Landsat images for the study sediment accumulated in the terrace was c. 50 Mm3 of sand. As a area from 1984 indicate that a wide technogenic terrace still existed result, the coastal cliffs have become inactive and overgrown by at that time. Coastal erosion had decreased the width of the terrace by vegetation. Sediment dumping moved to Pokrovskaya Bay from 2005, the sand spit was completely destroyed and an anthropogenic 1971 and the anthropogenic accretion terrace between Yantarny and lagoon adjoined the Baltic Sea. The position of the shoreline was Sinyavino has begun to erode. The dumping of 20 Mm3 of similar to that in 1936, with the exception of Sinyavino Bay, where it sediments into Pokrovskaya Bay between 1971and 1986 resulted in was positioned 150–200 m seaward. Sediment dumping from the the total filling of the bay, shifting the shoreline to what was amber factory resumed in 2007, with sediment volumes of 0.5– previously 9–10 m water depth and forming a protective beach in 1.2 Mm3 annually. This reduced the retreat of the coastline to the front of Pokrovskoye. south of Pokrovskoye village to 0.8–2.5 m a−1. Sediment dumping was suddenly halted in 2000 due to the Over the last ten years the average rate of coastal erosion of the introduction of environmental restrictions. Coastal erosion has Sambia Peninsula has been 0.5 m a−1, but the rate and patterns of subsequently intensified along the whole western coast of the coastal dynamics differ significantly. The coast between the Baltic

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Fig. 7. Monitoring (2016–19) of coastal cross-section of the northern coast of Sambia Peninsula near Filino village. (a) Representative description of cross-section (2018). (b) Aerial photograph taken by unmanned aerial vehicle. (c) Digital terrain model of the coast with slope angles.

Channel and Taran Cape can be divided into more than ten (Table 3). As a result of the high value of coastal land and intense segments with different dynamics, with rates of shoreline shift from erosion (average rate of shoreline retreat 0.25 m a−1 and maximum −8.2 to +2.8 m a−1 (Fig. 5). Recent rates of coastal erosion along rate up to 1.4 m a−1), the total length of coastal protection structures most part of the western coast of the Sambia Peninsula are locally on this stretch of coastline is 10.7 km. However, unlike the western very high. coast, the technogenic impact on the northern coast of the Sambia The recent rate of retreat of the coastal escarpment in the southern Peninsula has not changed the main trends of the natural processes. part of Pokrovskaya Bay reached 2.5 m a−1 (2008–18), whereas the The coastal areas to the west of Filino village are susceptible to long-term rate is 1.4 m a−1 (1936–2013). The coastal escarpment of large landslides, several hundred metres in diameter, as a result of Cape Peschany retreated by 6–16 m between 2008 and 2018, with the combination of the heterogeneous cliff geology and hydrogeol- an average rate of retreat over this recent period of 0.6–1.6 m a−1 ogy. Dense ferruginized Paleogene sandstones crop out in the lower and a longer term rate of 0.4–0.5 m a−1 (1936–2013). sections of the coastal cliffs (up to 10–12 m), whereas the upper part The technogenic terrace of Sinyavino Bay, formed by mining consists of unconsolidated Neogene sandy clay (Fig. 5b). The waste from the amber factory, is eroded according to monitoring predominant process is cliff destruction caused by debris flows and levelling and retreated at a rate of 8.2 m a−1 in 2008–18, although landslides, together with erosion at the toe of the cliff. The long- the coastal escarpment here is stable. The maximum rates of coastal term rate of retreat of the coastal escarpment is 0.1 m a−1 (1936– retreat are observed near Donskoye village. The 15 m high 2013) and instrumental measurements from 2008 to 2018 have escarpment to the north of Donskoye shifted landward by 80– shown the same rate of erosion. This is because a complex coastal 100 m along 800 m of the coastline. The recent and longer term protection project was implemented in Filino Bay from 1987 to erosion rates are similar: 1.1 m a−1 in the time period 2008–18 and 1991. The slope itself was engineered to a new shape, large volumes 1.1–1.3 m a−1 from 1936 to 2013. of sediment were used for beach nourishment and wave absorbers An analysis of TLS results enabled us to demonstrate a were constructed in the backshore. The programme included mechanism for the destruction and retreat of the coastal escarpment. reshaping the height of the cliff up to 44–47 m. The most eroded The escarpment is characterized by steep slopes and cliffs up to part of the cliff, composed of Neogene sands, was removed and the 40 m high. TLS measurements for the 40 m high cliffs with steep residual material (2.3 Mm3) was dumped in the nearshore. This (70–87°) slopes in the southern part of Donskoye village were made increased the width of the beach to the west of the dumping site at from 11 scan stations in August 2016 and 10 scan stations in August Filino Bay by up to 140 m along a c. 2.5 km segment and the beach 2017 (Fig. 9). Analysis of the digital elevation model allowed us to at Primorye village was widened to 110 m. This sand also entered obtain the volume of changes that occurred at this site over one year the longshore transport system and maintained the net sediment

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Fig. 8. (a) Comparison of 1:25 000 scale topographic map (1936) and high- resolution satellite image (Bing Maps, 2013): 1, coastal line; 2, cliff edge. (b) Aerial photograph of technogenic terrace in Pokrovskaya Bay (2019).

balance of Svetlogorsk Bay for the next five years (Boldyrev and intense landslides and surface runoff flow processes. Mass Ryabkova 2001). movement and erosional processes are very rapid within the The geological structure of the coastal zone between Filino coastal zones of Otradnoye village and Svetlogorsk town. and Otradnoye villages is very different, with local capes formed Several coastal segments were straightened by various types of of glacial till thought to be the remains of an end-moraine hard coastal protection structures in the 1960s to 1980s, but these structure (Zhindarev et al. 2012). Glacial tectonics and selective have had a less positive effect since the beginning of the 2000s. denudation along this stretch of coast have resulted in the The longer term (1936–2013) rate of retreat of the coastal formation of several valleys perpendicular to the recent escarpment is up to 0.3 m a−1. Recent coastal protection shoreline. At the present time these valleys are associated with measures have stabilized the escarpment.

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Fig. 9. (a) Three-dimensional rendering of the frontal elevation of the surveying cliff in 2016 generated from more than seven million survey points. (b) Three- dimensional rendering of the frontal elevation of the surveying cliff at 2017 generated from over seven million survey points. (c) Digital elevation model of the difference between the 2016 and 2017 surveys representing the annual changes in volume. (d) Linear difference (m) of cliff crest positions obtained from terrestrial laser scanning point cloud.

The height of the coastal cliffs decreases between Svetlogorsk recreational point of view, segments of the coast of both Russian and Rybnoye villages as a result of the occurrence of a wide sectors of the Baltic Sea. Moreover, a comparative study of longer palaeoriver valley and the longer term rate of retreat of the term and recent rates of erosion in the SE Baltic Sea and monitoring coastal escarpment reaches 0.2 m a−1 (1936–2013), while the observations in the EGoF coastal zone show a recent acceleration of recent rate is reduced to 0.9 m a−1 (2008–18). The recent rate of coastal erosion within most parts of the study area. The geological retreat decreases to 0.3 m a−1 to the east, towards the Cape and geomorphological factors determine the long-term evolution of Kupalny escarpment, which consists of sandy and clayey loam the coastal zone. The most important prerequisite for the relatively (silty clay), although the longer term rate remains at 0.2 m a−1. rapid coastal erosion in the Russian Baltic is the geological The long pier of Pionersky harbour, perpendicular to the composition and properties of the coastal deposits. shoreline, has caused the formation of a stable sandy beach to The coasts of the EGoF mostly consist of easily erodible the east of the construction. Mass movement and erosion Quaternary deposits (clays and sands). They have evolved under an processes are very active from Pionersky to Cape Gvardeisky, overall deficit of sediment in the nearshore region, which is partially with the exception of local areas with coastal protection augmented by numerous boulder belts formed as a result of the structures. Here, the longer term rates of retreat of the coastal erosion of glacial till. The coastal cliffs of the SE Baltic are escarpment are 0.4–0.7 m a−1 (1936–2013) and recent rates have composed of unconsolidated sandy and clayey Paleogene, Neogene increased to 0.9 m a−1 (2008–18). and Quaternary deposits. The relatively small thickness of the layers Offshore research on the marine periphery of the Sambia (1–10 m), the changeable grain size composition (alternating clayey Peninsula has revealed the wide distribution of boulder bottom and sands, sands and sandy clays, clays and coarse-grained sediments) pre-Quaternary deposits and a lack of sand material in the nearshore, and multiple points of spring water discharge from three aquifers in so there is limited potential for the onshore movement of sand to Neogene deposits predetermine the conditions for active mass maintain beach volumes (Petrov and Lygin 2014). movements. Coastal erosion, coupled with surplus rainfall, is one of the most important triggers of landslides. The main driving forces of Discussion and recommendations for coastal protection the cliff landslides are wave erosion at their foot, frost weathering and precipitation. Fluvial processes, in which temporary waterways Analyses of archive maps, RSD and monitoring measurements in the coastal ledge, fed by precipitation, produce channels, wash reveal high erosion rates within the most valuable, from a away material and cause instability of the gulley walls. The results of offshore investigations have shown a significant deficit of sediment Table 3. Volume of yearly changes in the coastal cliffs as a result of different in the nearshore of both study areas; this is one of the most important processes causes of active coastal erosion. Total Landslides Ravine Analysis of extreme water levels for the whole Baltic Sea showed

2 that the amplitude could reach 3 m for the SE Baltic and 3.5 m for Area (m ) 5920 5111 809 the EGoF for the period 1960–2010. The EGoF experiences the 3 − − − Volume of changes (m ) 2426 2213 213 most dangerous storms as a result of particular atmosphere Volume of negative changes (m3) 4751 4421 330 movements (Wolski et al. 2014). The geographical distribution of Volume of positive changes (redeposition) (m3) 2325 2208 117 − − the storms across the Baltic Sea shows a higher occurrence of storms Rate of annual negative changes ((m3 m 2)a 1) 0.76 0.75 0.77 − − (>300 for the period 1960–2010) in the EGoF than in the SE Baltic Rate of annual changes ((m3 m 2)a 1) −0.5 −0.42 −0.68 (100–200 for the same time period) (Wolski et al. 2014).

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We analysed archival wind data (velocity, direction, gusts) and storm wave generation to demonstrate these changes. Waves more

2.9 (7) – 1.1 (26) than 1 1.2 m high were accepted as the threshold for coastal storm 8.2 (12) − − − 0.8 (11) waves (Boccotti 2000). Data from Kronshtadt meteorological −

0.1 (8) 0.1 (8) station (https://rp5.ru) for the EGoF for the period 2010–19 − − showed that storm events of >6 h duration with wind speeds >5 m s−1 were sufficient to produce storm waves 1–1.2 m high

0.3; maximum (Ryabchuk et al. 2011a)(Fig. 10a). There was no significant − increase in storm activity during this period and the maximum storm ) (number of measurements for 1

− frequency of 30% occurred in 2019, with an average number of storm events in the EGoF of 16% per year. Data from the D6 platform station in the SE Baltic for the period 0.24; minimum 0.7; maximum 0.1; minimum 0; maximum 2.6; minimum 1.9; maximum 1.4; minimum

18) – − − − − 2010 19 showed that storm events >6 h duration with wind speeds – >12 m s−1 were required to produce storm waves higher than 1– ean) 1.2 m (Bobykina and Stont 2015; Figure 10b). There was no significant increase in the occurrence of storm events in the SE Baltic in the time period 2010–19. The peak number of events over Average (mean) 0; minimum 0; maximum the period 2008 Average (mean) Rate of cliff dynamics (m a ten years was observed in 2014 (2%). The average occurrence for intense events was 0.7% per year. An increase in the frequency of strong storm events has been noted for both the SE Baltic Sea and the Gulf of Finland in recent decades (Soomere et al. 2007; Ryabchuk et al. 2011a; Wolski et al. 2014; BACC Author Team 2015; Bobykina and Stont 2015). They occur up to four times in every ten years for the EGoF, whereas in the second half of the twentieth century such events occurred only once in every 25 years (Barkov 1989). The impact of this increased storm activity on the coasts of the SE Baltic Sea is reflected in the destruction of coastal protection structures and flooding of inland territories as a result of the erosion of the foredune ridge (Stont and Bobykina 2013; Ryabchuk et al. 2011a; Danchenkov and Belov 2019; Danchenkov et al. 2019; Stont et al. 2019). Based on the VSEGEI monitoring observations, the most extreme erosion events in the EGoF are controlled by a specific combination of long-lasting westerly or southwesterly storms, which bring high waves to the area in question, high water levels and an absence of stable sea ice during such events. A drastic reduction in beach material was observed after extreme erosion events in the Gulf of Finland (Eelsalu et al. 2015; Sergeev et al. 2018). Based on the TLS data used to assess sand losses after storms, the depth of beach and foredune sediments was reduced by up to 0.9–1.2mina single autumn–winter storm event (Sergeev et al. 2018). Wave activity is still the major driver of coastal processes in the SE Baltic (Kelpšaitėet al. 2011). The Sambia Peninsula has historically been considered as a source for bidirectional alongshore sediment flows (Harff et al. 2017). Most of the storms are associated with west–NW–north wind directions, the frequency of which is increasing (Kurennoy and Kelpšaitė2014) and for which the fetch length is at a maximum for this part of the sea. The wave heights in the shallow water along the cliffs of Sambia Peninsula can reach significant values as a result of the large bottom slopes (0.01– processes transport from the northern part of the coast Secondary coasts: wave-straightened coastsSecondary coasts: wave-straightened coasts. Ravine erosion as a main relief-formed factor accelerates negative Average (mean) 0; minimum 0; maximum Secondary coasts: wave-straightened coasts. Accumulation of material on the coasts occurs by longshore sediment 0.2 rad), whereas the dissipation of wave energy is much more significant in the accumulation region of Pokrovskoye settlement where the slopes have much lower angles (0.005 rad). Thus steeper bottom slopes, caused by sediment deficits on the underwater coastal slope, lead to a greater energy content of storm waves. These, combined with surge phenomena, increase erosion on the shores of Sambia Peninsula. Nearshore sand mining, which took place in the nearshore in the 1960s–1990s, and damage to the coastal dunes are the main negative technogenic factors in the evolution of the coastline. The construction of the St Petersburg FPF was an important anthropo- material erosion coast genic factor influencing coastal dynamics. The sea-level is a crucial factor influencing the intensity of coastal erosion. The main aim of Parameters of coastal dynamics for different coastal types of the southeastern Baltic based on the classification of Shepard (1948) the FPF is to decrease the water level within Neva Bay during floods. Closing the FPF gates prevents a rise in sea-level within 1 Active erosion cliff Secondary coasts: wave-straightened coasts. Active cliff is at the back of a beach Average (mean) 23 Active erosion cliff4 with landslide toe Active erosion cliff with ravine Stable erosion cliff Secondary coasts: wave-straightened coast. Stabilized cliff, no current process observed Average (mean) 5 Eroded technogenic nourished coast Secondary coasts: wave-straightened coast. Main input of material is initiated by the amber factory Average (m 6 Progradating technogenic nourished 7 Hydroengineering facilities Stable technogenic coasts Table 2. Legend No. Coastal type Description Neva Bay during hazardous westerly cyclones, but at the same time

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Fig. 10. Occurrence of storm events in (a) the Eastern Gulf of Finland and (b) the SE Baltic.

the water level on the outer side of the FPF (to the west of the wave-breakers within the most heavily eroded and most valuable construction) is higher than under natural conditions. As a result, the coastal segments. Unfortunately, realization of the Program has influence of the FPF on coastal stability varies with location. Neva been postponed due to legislation and financial problems. Bay has been much better protected from erosion since the FPF began operation in 2011. By contrast, the coastline outside the FPF Conclusions has experienced more severe effects from waves associated with increased water levels outside the FPF during storm surges. A comparative analysis of historical data (since 1936) and recent The earliest coast protection measures in the EGoF, which aimed coastal monitoring measurements for the last ten years shows an −1 to stop erosion and protect sandy beaches, began at the end of the acceleration of coastal retreat of up to 1.4–1.6 m a in both Russian nineteenth century. The hard engineering structures, mostly groynes sectors of the Baltic Sea. This activation of hazardous exogenous emplaced perpendicular to the shoreline and sea walls without sand geological processes in coastal zones during the last decade is nourishment, were not effective as a result of the deficit of sediment. related to climatic changes and sediment deficits. A combination of Most of the structures are badly damaged and have intensified beach tectonic (vertical movement of the Earth’s crust), geological erosion with, in some instances, a full loss of sand material both on (geotechnical properties of coast-forming deposits) and geomor- land and offshore. As a consequence, they have not protected the phological factors controls the long-term evolution of the coastal coast and have, in fact, reduced its recreational value. The first Coast zone. The coasts of the EGoF and the coastal cliffs of the Russian Protection Plan for the most eastern part of the Gulf of Finland, the SE Baltic are mainly formed of easily destructible clastic deposits of General Scheme of Coast Protection, was developed in the late different grain sizes (clay, silty sand and mixed sediments). Coastal 1980s, but was not realized. The only successful attempt at the erosion at the toe of the slope – coupled with surplus rainfall, protection of this part of the coast was an experimental beach numerous groundwater outlets and frost weathering – is the main nourishment scheme in Komarovo village in 1988 (Sergeev et al. trigger of landslides. Anthropogenic influences have recently 2018). The effect of that sand nourishment is now depleted. become an important factor, both negatively and positively affecting The first coastal protection structures along the Sambia Peninsula the evolution of the coastline, and comparable in potency to natural coast, mostly groynes perpendicular to the shoreline, were processes, especially in the Kaliningrad Region. constructed before the Second World War. Their effectiveness has The short-term, but most extreme, erosion in the coastal zone decreased over time, together with a growing deficiency of sediment is associated with long-duration storms combined with higher in the nearshore. Hard coastal protection constructions (sea walls) levels of surge water. Such storms occur most frequently during have been the main method of minimizing erosion since the 1960s. the autumn–winter period and cause significant erosion where These constructions have prevented some emergency situations in stable sea ice is absent. The frequency of such storm events has the coastal resorts, but, at the same time, they have initiated a deficit recently increased as a result of the warming climate. Monitoring of sediment that has decreased the width of the beach and of coastal geological processes and forecasting of the main accelerated the erosion of the adjoining coastal segments. trends in the evolution of the Baltic coast of Russia are very The results generated in this study were recently incorporated into important in informing plans for coastal protection measures and the Coast Protection plans of Kaliningrad Region and St Petersburg to help ensure the future sustainable development of Russia’s City. The coasts of the Sambia Peninsula can be protected using coastal territories. complex engineering structures – that is, sand nourishment with the construction of artificial beaches to prevent the impact of storms on Scientific editing by Cherith Moses; James Lawrence the base of the escarpment and to compensate for the deficit of sediment; wooden groynes perpendicular to the shoreline to Acknowledgements This paper was prepared within the frame of the decrease the erosion of the artificial beaches and gabions at the EMODnet-geology project. We are grateful to the reviewers for very useful and base of the coast escarpment and stabilization of its slope to prevent important comments and to Cherith Moses for helping to improve the English in landslides. These complex coastal protection measures started in the our paper. resort towns of Zelenorgadsk and Svetlogorsk in 2016–19 within the framework of the development of the State Program of Author contributions DR: conceptualization (lead), investigation Kaliningrad Region. (equal), methodology (equal), writing – original draft (lead), writing – review The St Petersburg City Marine Coast Protection Program was and editing (equal); AS: conceptualization (equal), data curation (equal), investigation (equal), methodology (lead), software (equal), visualization developed in the EGoF in 2015–16. This is based on both the Master (lead), writing – original draft (supporting), writing – review and editing Plan of St Petersburg city and the analyses of distribution of coastal (supporting); EB: investigation (equal), methodology (equal), writing – original erosion hotspots, erosion rates, coastal zone geology and morph- draft (equal); VK: data curation (equal), investigation (supporting), methodology (supporting), writing – original draft (supporting); IN: data curation (equal), ology, and existing coastal protection constructions. The Program investigation (equal), methodology (equal); OK: investigation (supporting), has identified five areas of high priority for coastal protection within writing – original draft (supporting), writing – review and editing (equal); LB: Kurortny district (to the west of the FPF), two areas on the west data curation (equal), investigation (equal); VZ: conceptualization (equal), investigation (equal), writing – review and editing (equal); AD: data curation coast of Kotlin Island and six areas within Neva Bay. The key mode (equal), investigation (equal), methodology (equal), writing – original draft of coastal protection is sand nourishment, together with groynes or (supporting), writing – review and editing (supporting)

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Funding Analysis of the coastal dynamics of the Eastern Gulf of Finland was Kelpšaite,̇ L., Herrmann, H. and Soomere, T. 2008. Wave regime differences supported by the Russian Science Foundation Project No. 17–77–20041. along the eastern coast of the Baltic Proper. Proceedings of the Estonian Analysis of the coastal dynamics of the Kaliningrad area was carried out with the Academy of Sciences, 57, 225–231, https://doi.org/10.3176/proc.2008.4.04 support of the state assignment of IO RAS (Theme No. 0149–2019–0013) and Kelpšaite,̇ L., Dailidiene,̇ I. and Soomere, T. 2011. Changes in wave dynamics at EMODnet-geology project. the south-eastern coast of the Baltic Proper during 1993–2008. Boreal Environment Research, 16, 220–232. Kosyan, R., Krylenko, M., Ryabchuk, D. and Chubarenko, B. 2013. Russia. In: Pranzini, E. and Williams, A. (eds) Coastal Erosion and Protection in All data generated or analysed during this Data availability statement . Routledge, London, 19–33. study are included in this published article. Kovaleva, O., Eelsalu, M. and Soomere, T. 2017. Hot-spots of large wave energy resources in relatively sheltered sections of the Baltic Sea coast. Renewable and Sustainable Energy Reviews, 74, 424–437, https://doi.org/10.1016/j.rser. References 2017.02.033 Abromeit, J., Bock, P. and Jensch, A. 1900. Handbuch des Deutschen Kurennoy, D. and Kelpsaite, L. 2014. Comparison of wind wave properties in Dünenbaues. P. Parev, Berlin. Neva Bay and based on modeled data. Paper presented at the – Aibulatov, N.A., Dolotov, Y.S., Orlova, G.A. and Yurkevitch, M.G. 1966. Some IEEE/OES Baltic International Symposium (BALTIC), Tallinn, 1 7, https:// features of flat sand coast dynamics [in Russian]. In: Investigations of Hydro- doi.org/10.1109/BALTIC.2014.6887857 ’ and Morphodynamic Processes of the Sea Coastal Zone. Nauka, Moscow, Leont ev, I.O., Ryabchuk, D.V., Sergeev, A.Y. and Sukhacheva, L.L. 2011. On 38–103. the genesis of some bottom and coastal features in the Eastern Gulf of Finland. – Babakov, A.N. 2002. Spatiotemporal Structure of Coastal Currents and Oceanology, 51, 688 698, https://doi.org/10.1134/S0001437011040102 Sediment Transportation in the Coastal Zone of the South-Eastern Baltic Markov, K.K. 1931. Development of the Relief in the North-Western Part of the Sea. PhD Thesis, AB IO RAS, Kaliningrad. Leningrad District [in Russian]. Geolizdat, Leningrad. BACC Author Team 2015. Second Assessment of Climate Change for the Baltic Sea Orviku, K. and Granö, O. 1992. Contemporary coasts. In: Raukas, A. and Basin. Springer International , Cham, https://doi.org/10.1007/978-3-319-16006-1 Hyvärinen, H. (eds) Geology of the Gulf of Finland. Valgus, Tallinn, 219–238. Barkov, L. 1989. About lithodynamics of coastal zone and bottom of the eastern Petrov, O.V. (ed.). 2010. Atlas of Geological and Environmental Geological Gulf of Finland [in Russian]. Vestnik of the Leningrad University, 28,25–32. Maps of the Russian Area of the Baltic Sea. St Petersburg. Bass, O.V. and Zhindarev, L.A. 2007. Technogenesis of sandy beaches coastal Petrov O.V. and Lygin A.M. (eds) (2014) Information Bulletin on Status of Near- zones of enclosed seas. Geomorphology, 4,17–24, https://doi.org/10.15356/ shore Geological Environment of Barents White and Baltic Seas in 2013 [in 0435-4281-2007-4-17-24 Russian]. VSEGEI. Bobikina, V.P. and Karmanov, K.V. 2009. Coastal dynamics of the Gdansk Bay Raukas, A. and Hyvärinen, H. (eds) 1992. Geology of the Gulf of Finland [in apex and connections with anthropogenic influence. In: Kozyreva, E.A. and Russian]. Valgus, Tallinn. Khabidov, A.Sh. (eds) Development of Artificial Territories in Coastal Zones Rózynski,́ G. 2010. Wave climate in the Gulf of Gdansḱ vs. open Baltic Sea near of Seas, Lakes and Water Storage Reservoirs. SB RAS, Novosibirsk, 119–124. Lubiatowo, Poland. Archives of Hydroengineering and Environmental Bobykina, V. and Boldyrev, V. 2008. Tendency in shore dynamics in the Mechanics, 57, 167–176. according to five years monitoring information. In: Integrated Ryabchenko, V.A., Leontyev, I.O., Ryabchuk, D.V., Sergeev, A.Y., Dvornikov, Management, Sustainable Development Indicators, Spatial Planning and A.Y., Martyanov, S.D. and Zhamoida, V.A. 2018. Mitigation measures of Monitoring of the South-Eastern Baltic Coastal Regions. Kaliningrad, 46–47. coastal erosion on the Kotlin Island’s shores in the Gulf of Finland, the Baltic Bobykina, V.P. and Stont, Z.I. 2015. Winter storm activity in 2011–2012 and its Sea. Fundamentalnaya i Prikladnaya Gidrofizika, 11,36–50, https://doi.org/ consequences for the southeastern Baltic coast. Water Resources, 42, 10.7868/S207366731802003X 371–377, https://doi.org/10.1134/S0097807815030021 Ryabchuk, D., Kolesov, A., Chubarenko, B., Spiridonov, M., Kurennoy, D. and Boccotti, P. 2000. Wave Mechanics for Ocean Engineering. Elsevier Soomere, T. 2011a. Coastal erosion processes in the eastern Gulf of Finland Oceanography Series, 64. Elsevier Science, Amsterdam. and their links with geological and hydrometeorological factors. Boreal Boldyrev, V.L. and Ryabkova, O.I. 2001. Dynamics of coastal processes of the Environment Research, 16, 117–137. Kaliningrad region, Baltic Sea. Proceedings of the Russian Geographical Ryabchuk, D., Leont’yev, I., Sergeev, A., Nesterova, E., Sukhacheva, L. and Society, 133,41–48. Zhamoida, V. 2011b. The morphology of sand spits and the genesis of Boldyrev, V.L., Lashenkov, V.M. and Ryabkova, O.I. 1990. Storm deformation longshore sand waves on the coast of the eastern Gulf of Finl and. Baltica, 24, of coasts of the Kaliningrad region, Baltic Sea. Issues of Coastal Dynamics 13–24. and Paleogeography of the Baltic Sea Coastal Zone, 1,97–129. Ryabchuk, D., Zhamoida, V., Sergeev, A., Kovaleva, O., Nesterova, E. and Dailidiene,̇ I., Davuliene,̇ L., Tilickis, B., Stankevicius,̌ A. and Myrberg, K. 2006. Budanov, L. 2014. The Coastal Erosion Map for Different Climate Change Sea level variability at the Lithuanian coast of the Baltic Sea. Boreal Scenarios. Compilation – Methodology and Results. St Petersburg, http:// Environment Research, 11, 109–121. cliplive.infoeco.ru/dl/Mineral/reports/Annex%205%20Coastal%20Erosion% Danchenkov, A.R. and Belov, N.S. 2019. Morphological changes in the beach- 20Metodology.pdf foredune system caused by a series of storms. Russian Journal of Earth Ryabchuk, D., Vallius, H. et al. 2017. Pollution history of Neva Bay bottom Sciences, 19, https://doi.org/10.2205/2019ES000665 sediments (eastern Gulf of Finland, Baltic Sea). Baltica, 30,31–46, https://doi. Danchenkov, A., Belov, N. and Stont, Z. 2019. Using the terrestrial laser org/10.5200/baltica.2017.30.04 scanning technique for aeolian sediment transport assessment in the coastal Ryabkova, O.I. 2000. Nature management and tasks of coastal protection in zone in seasonal scale. Estuarine, Coastal and Shelf Science, 223, 105–114, Kaliningrad Region shores [in Russian]. In: Vanceva, L.G. (ed.) Physical https://doi.org/10.1016/j.ecss.2019.04.044 Geography of the Ocean and Nature Management at the Turn of XXI Century. Eelsalu, M., Soomere, T. and Julge, K. 2015. Quantification of changes in the Kaliningrad State University, Kaliningrad, 49–64. beach volume by the application of an inverse of the Bruun rule and laser Sergeev, A., Ryabchuk, D., Zhamoida, V., Leont’yev, I., Kolesov, A., Kovaleva, scanning technology. Proceedings of the Estonian Academy of Sciences, 64, O. and Orviku, K. 2018. Coastal dynamics of the eastern Gulf of Finland, the 240–248, https://doi.org/10.3176/proc.2015.3.06 Baltic Sea: toward a quantitative assessment. Baltica, 31, https://doi.org/10. Geographisches Institute 1908a. Palmnicken, Melßtischblatt 139. Topographic 5200/baltica.2018.31.05 map 1:25 000, Reichsuniversität Posen Geographisches Institute, corrected in Shepard, F. 1948. Submarine Geology. Harper & Brothers. 1922, individual additions 1928. Šliaupa, S. and Hoth, P. 2011. Geological evolution and resources of the Baltic Geographisches Institute 1908b. Gr. Dirschkeim, Melßtischblatt 103. Sea area from the Precambrian to the Quaternary. In: Harff, J., Björck, S. and Topographic map 1:25 000, Reichsuniversität Posen Geographisches Hoth, P. (eds) The Baltic Sea Basin. Springer, Berlin, 13–51. Institute, corrected in 1922. Soloshchuk, P.V. 2010. Changes in the climate and ice conditions in the Gulf of Geographisches Institute 1908c. Rauschen, Melßtischblatt 104. Topographic Finland–the Neva Bay–the Neva river water system in the autumn-winter map 1:25 000, Reichsuniversität Posen Geographisches Institute, corrected in period in the past 15 years. Scientific Notes of the Russian State 1922. Hydrometeorological University, 14,34–41. Geographisches Institute 1908d. Neukuhren, Melßtischblatt 105. Topographic Soomere, T. 2008. Extremes and decadal variations of the northern Baltic Sea wave map 1:25 000, Reichsuniversität Posen Geographisches Institute, corrected in conditions. In: Pelinovsky, E. and Kharif, C. (eds) Extreme Ocean Waves. 1922. Springer, Dordrecht, 139–157, https://doi.org/10.1007/978-1-4020-8314-3 Gordeeva, S. and Malinin, V. 2014. Gulf of Finland Sea Level Variability. RSHU Soomere, T., Kask, A., Kask, J. and Nerman, R. 2007. Transport and distribution Publishers, St Petersburg. of bottom sediments at Pirita Beach. Estonian Journal of Earth Sciences, 56, Harff, J., Björck, S. and Hoth, P. (eds). 2011. The Baltic Sea Basin. Springer, 233–254, https://doi.org/10.3176/earth.2007.04 Berlin. https://doi.org/10.1007/978-3-642-17220-5 Spiridonov, M., Ryabchuk, D., Zhamoida, V., Sergeev, A., Sivkov, V. and Harff, J., Deng, J. et al. 2017. What determines the change of coastlines in the Boldyrev, V. 2011. Geological hazard potential at the Baltic Sea and its coastal Baltic Sea? In: Harff J. Furmanczyk K., Von Storch H. (eds) Coastline zone: examples from the Eastern Gulf of Finland and the Kaliningrad area. In: Changes of the Baltic Sea from South to East. Springer, 15–35. Harff, J., Björck, S. and Hoth, P. (eds) The Baltic Sea Basin. Springer, Berlin, Kahma, K., Pettersson, H. and Tuomi, L. 2003. Scatter diagram wave statistics 337–364, https://doi.org/10.1007/978-3-642-17220-5 from the northern Baltic Sea. MERI–Report Series of the Finnish Institute of Stont, Z. and Bobykina, V. 2013. About the winter storm activity of 2011–2012 Marine Research, 49,15–32. and its implications for the Curonian Spit. In: Volkogon, V.A. (ed.) Problems

Downloaded from http://pubs.geoscienceworld.org/qjegh/article-pdf/doi/10.1144/qjegh2020-036/5194850/qjegh2020-036.pdf by guest on 27 September 2021 16 D. Ryabchuk et al.

of Studying and Protecting the Natural and Cultural Heritage of the Wolski, T., Wisniewski,́ B. et al. 2014. Extreme sea levels at selected stations on “Curonian Spit” National Park, Kaliningrad State Technical University the Baltic Sea coast. Oceanologia, 56, 259–290, https://doi.org/10.5697/oc. (KSTU), Kaliningrad, 126–134. 56-2.259 Stont, Z., Ulyanova, M., Krek, E., Churin, D. and Gubareva, D. 2019. Storm Yakovlev, S.A. 1925. Relief and Sediments of Leningrad Area, Leningrad activity during autumn-winter period of 2018-2019 in the southeastern Baltic [in Russian]. Sea. KSTU News, 53,61–71. Zagorodnyh, V.A. and Kunaeva, N.A. 2005. Geology and Mineral Resources of Tillo, E.I. 1893. Project of St. Petersburg Flood Protection. Reports of Russian Kaliningrad Region, Kaliningrad (Yantarny Skaz), Kaliningrad [in Russian]. Geographical Society, XXV,2. Zaitseva-Pärnaste, I., Soomere, T. and Tribštok, O. 2011. Spatial variations in the Topcon Inc. 2010. Instruction manual. Laser Scanner GLS-1500. Topcon, wave climate change in the Baltic Sea. Journal of Coastal Research, 195–199. Tokyo. Zhamoida, V.A., Ryabchuk, D.V., Kropatchev, Y.P., Kurennoy, D., Boldyrev, Tornquist, A. 1914. Die Wirkung der Sturmflüt vom 9 bis 10 Januar 1914 auf V.L. and Sivkov, V.V. 2009. Recent sedimentation processes in the coastal Samland und Nehrung. Schriften der Physikalisch-Ökonomischen zone of the Curonian Spit (Kaliningrad region, Baltic Sea). Zeitschrift der Gesellschaft zu Königsberg, 245–246. Deutschen Gesellschaft für Geowissenschaften, 160, 143–157, https://doi.org/ Vereisky, N.G. 1946. Explanatory note to the geological map of Quaternary 10.1127/1860-1804/2009/0160-0143 deposits of the Kaliningrad region of the RSFSR and adjacent areas of Poland Zhindarev, L.A., Ryabkova, O.I. and Sivkov, V.V. 2012. Geology and 1946. State archives of Kalinigrad region. geomorphology of sea coasts. In: Sivkov, V.V., Kadzhoyan, Y.S., Wichdorff, v. H.H. 1919. Geologie der Kurischen Nehrung. vertrieb bei der Pichuzhkina, O.E. and Feldman, V.N. (eds) Oil and Environment of the Preussischen geologischen, Landesanstalt. Kaliningrad Region. Vol. II, The Sea. Terra Baltica, Kaliningrad, 19–36.

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