Long-term Coastal Evolution Research Articles

Sediment leakage on the beach and upper shoreface due to extreme storms

The quantification of sediment exchanges between the beach and the lower shoreface, although being still poorly understood, is required to adequately forecast long-term coastal evolution. The effect of extreme storms on the morphodynamics of the nearshore and the sediment budget of the coastal zone seems to be strongly conditioned by local parameters, which should be incorporated into studies of medium- and long-term coastal evolution. In the upper shoreface, the dynamics of shore-parallel bars in sandy coasts have been extensively studied, but their implications for the sediment budget remain controversial as it is unclear whether their evolution simply represents a morphological change or denotes an escape of sediment from the upper shoreface. In order to provide new knowledge to address these questions, fifteen topo-bathymetric surveys that extend from the emerged beach to 15 m water depth were carried out along 1 km of Castelldefels beach (Llobregat Delta, Barcelona, western Mediterranean Sea) during the period 2011–2022. Morphological variations on the shoreface are studied, volumetric changes are estimated and implications on sedimentary exchanges in the littoral profile are inferred. The largest morphological (volumetric) changes are caused by cross-shore displacements of the nearshore bars, usually onshore during fair-weather conditions and offshore during storms. Volumetric changes suggest that shoreline retreat and the erosion of the shallow section of the profile during the last decade provides sediment to both the distal upper shoreface and the lower shoreface. The resulting sediment budget in the profile is almost zero in absence of extreme storms, but becomes highly negative when including extreme storms events that cause a net offshore transfer of sediment from the upper to the lower shoreface and, probably, the inner shelf. The characteristics of the study area (morphology, sediments, waves, tides) and in-situ hydrodynamic measurements at the lower shoreface suggest that the main potential onshore transport mechanisms (velocity and acceleration skewness during low-mid energy event) are small, making a significant transfer of sediment from the lower shoreface towards the shallow beach area unlikely at interannual scales. Thus, the study area is an example of low-lying coastal stretch in which the potential long-term shoreline retreat caused by sea level rise cannot be fully compensated by the sediment supplied from the lower shoreface. Other mechanisms, such as sediment supplied by longshore transport, are needed to counteract this trend.

A multi-scale assessment of shoreline changes at an undeveloped beach in southern Brazil

This research aims to investigate shoreline variability at an undeveloped beach in southern Brazil on interannual and millennial scales. The long-term coastal evolution was investigated by GPR, whereas the interannual scale shoreline changes were analyzed by the Digital Shoreline Analysis System (DSAS). Simultaneously, a supervised Maximum Likelihood image classification was applied to the dune systems to differentiate vegetation from sand. The results show that the coastline in the Praia das Cabras region is retreating at different scales. The stratigraphic record in GPR shows that the coast has a retrogradational stacking pattern behavior in geological time. At the same time, the results obtained from the digital shoreline analysis revealed that the coast has suffered short-term erosion in the analyzed period, and this is attributed to natural causes. Another point is the higher values of erosion in the extreme parts of the study area, which are related to the presence of washouts. There is also a differentiation in the stage of the dunes and vegetation between the northern and southern parts of the stretch. The northern area is more densely vegetated and has a continuous foredune ridge with incipient dunes forming a ramp, whereas in the southern part, the vegetation is more dispersed, with interrupted dunes forming nebkhas. Between 2019 and 2023 there was a recovery of the dune field, by filling in the blowouts and minimizing the indentations, forming a more homogeneous foredune line.

The relevance of coastal sediment budgets to management of sandy wave-dominated shorelines, a case study of Twofold Bay, southeastern Australia

Coastal compartments provide a framework for considering sediment budgets by defining the boundaries between adjacent beaches or sections of coast with a common sediment source. Here we present Twofold Bay as an ideal field laboratory to test the coastal compartment management approach, and in particular, note the relevance of long-term coastal evolution to shorter term planning timescales. Twofold Bay on the New South Wales south coast, Australia, contains four main beaches (Aslings, Boydtown, Whale and Fisheries Beaches) and associated barrier systems. We present a range of existing geological and geomorphic information combined with new field data which demonstrate considerable variation in the Holocene evolution and sediment budget of these adjacent beaches. These data show three broad sediment types exist within Twofold Bay and its beach systems: Type 1 is a mature quartz-rich sand derived from the shelf. Type 2 is a fine carbonate-rich sand from local biogenic production, and Type 3 is a coarse-fine angular feldspathic sand sourced from the Towamba River which drains to Twofold Bay via the southern end of Whale Beach. Newly available high-resolution topography and bathymetry as well as sediment thickness maps, have enabled shoreface geometry and basement topography to be estimated seaward of each beach and reveal considerable variability between sites helping explain past shoreline behaviour. Several new optically stimulated luminescence (OSL) ages for Boydtown Beach, combined with existing ages, confirm two distinct phases of shoreline progradation, initially at 0.16 m/yr, and then over the past ∼1500 years, at 0.65 m/yr. The increase in progradation rate reflects sediment supply from the Towamba River via Whale Spit. While these two beaches have become interconnected, Aslings Beach and Fisheries Beach are dominated by sediment Type 1 and Type 2 respectively and have different evolutionary histories with Aslings Beach forming a stationary barrier while Fisheries has prograded at 0.15 m/yr over the past ∼4300 years according to a new set of OSL ages. The Holocene evolution of these four adjacent beaches has resulted from their differing sediment sources and budgets and is in accord with several available datasets of decadal shoreline changes. These results demonstrate that spatial variation in shoreline behaviour is driven by differences in sediment budget and that just as adjacent beaches have behaved differently in the past, so will they in the future. Understanding these drivers of shoreline change is imperative to effective coastal management and planning in the context of projected future sea-level rise and other anthropogenic pressures.

LONG-TERM, ENSEMBLE, DATA-ASSIMILATED SHORELINE CHANGE MODELING

We present an ensemble Kalman filter shoreline change model to predict long-term coastal evolution due to waves, sea-level rise, and other natural and anthropogenic processes responsible for sediment transport. The model utilizes ensemble simulations to improve both reliability (via data assimilation) and uncertainty quantification. Coastal change projections exhibit significant differences when simulated with and without ensemble wave conditions. Many long-term coastal change projections rely on a single realization of the future wave climate, often derived from atmospheric conditions simulated by a global climate model. Yet, the single realization approach does not account for the stochastic nature of future wave conditions across a variety of temporal scales (e.g., daily, weekly, seasonally, and interannually). Here, by applying ensemble time series of wave forcing conditions, we demonstrate a sizable increase in model uncertainty compared with the unrealistic case of model projections based on a single realization (e.g., a single time series) of wave forcing.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/V-VwC-cIiQ0

NEW SUSPENDED SAND CONCENTRATION MODEL FOR BREAKING WAVES

Process-based morphodynamic modelling suites (as well as other process-based models) are often considered to be inefficient and unsuitable for simulating medium- to long-term morphodynamics due to the various theoretical (e.g. robustness of sediment transport models) and practical (e.g. computational costs) limitations. In particular, a lack of knowledge of sediment transport processes and how they relate to hydrodynamics makes the application of short-term models to long-term coastal evolution challenging. Even the state-of-the-art coastal area modelling suites (such as Delft3D and MIKE21) consist of relatively simple physics, relying instead on numerous semi-empirical parameterizations, which are often poorly supported by measured data and/or physical process understanding. In particular, suspended sediment transport in the highly turbulent surf zone is poorly modelled under breaking wave conditions. Six existing suspended sand concentration (SSC) models were critically evaluated against four high-resolution datasets with field-scale breaking waves and co-located velocity and concentration measurements over multiple cross-shore zones (shoaling, breaking and inner-surf zones). A new improved concentration model was proposed based on a novel empirical relationship observed between local water depth and reference concentration, as well as latest process understanding and insights.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/2iBrnXs4b3M

Coastal geomorphic response to seasonal water-level rise in the Laurentian Great Lakes: An example from Illinois Beach State Park, USA

Hydrodynamic processes, such as fluctuating water levels, waves, and currents, shape coastlines across timescales ranging from minutes to millennia. In large lacustrine systems, such as the Laurentian Great Lakes, the role of water level in driving long-term (centuries to millennia) coastal evolution is well understood. However, additional research is needed to explore short-term (weeks to months) beach geomorphic response to fluctuating water level. Developing a process-focused understanding of how water level fluctuations shape coastal response across these shorter time scales is imperative for coastal management. Here, we present measurements of geomorphic response along a lacustrine beach ridge plain to seasonal water level fluctuations during a decadal high-stand in Lake Michigan water level. Frequent topographic change measurements revealed high spatial and temporal variability in geomorphic response to rising lake level. Sites immediately downdrift of shore protection began to erode immediately as lake level increased. The co-occurrence of peak seasonal lake levels and a modest increase in wave energy resulted in erosion and overwash at sites that resisted erosion during the initial seasonal rise in lake level. None of the sites in this study returned to their initial morphology following seasonal lake level rise. Given that peak water levels were nearly identical in 2017 and 2018, yet the majority of erosion at our sites occurred in 2017, we postulate that erosion associated with seasonal lake level rise is primarily a function of the change in annual maximum water level from year to year, rather than solely the elevation of the water level.

A Long-Term Coastal Evolution Model with Longshore and Cross-Shore Transport

Palalane, J. and Larson, M., 2020. A long-term coastal evolution model with longshore and cross-shore transport. Journal of Coastal Research, 36(2), 411–423. Coconut Creek (Florida), ISSN 0749-0208.This study encompasses the development of a long-term coastal evolution model with enhanced capabilities to simulate simultaneously the cross-shore and longshore evolution of the coast. The paper starts by reviewing the theory related to cross-shore and longshore sediment transport, which are the major components integrated in the model. Major advances were made by introducing modules to better account for dune erosion and overwash, dune buildup by wind, and exchange of sediment between the berm and the bar into an existing coastal evolution model. Then, the model performance was tested by simulating the evolution for a stretch of coastline corresponding to the conditions at Westhampton Beach (United States), first for a case with open boundaries representing a situation of dynamic equilibrium and then for the placement of a terminal groin causing advance of the shoreline, berm crest, and dune foot. Subsequently, the model was employed to simulate the combined cross-shore and longshore evolution along Macaneta Spit (Mozambique), and the results were compared with available data. Overall, the model succeeded in reproducing the expected combined cross-shore and longshore evolution at the selected case study sites. For the Westhampton Beach case, the model was able to qualitatively simulate the observed advance of the cross-shore dune system, following the placement of the terminal groin. For Macaneta Spit, the model reproduced the alongshore variation in cross-shore profile shape in response to the incident waves and water levels, as well as the net longshore sand transport pattern as identified in previous studies. In summary, the model produced reliable and robust predictions, showing the capability of running simulations for a period of decades in a few minutes on a personal computer.

Holocene coastal environmental change and ENSO-driven hydroclimatic variability in East Asia

Understanding the past natural behavior of coastal hydroclimates at multi-centennial time scales is essential for planning coastal strategies in preparation for anticipated climate change. We investigated the elemental and isotopic features of 10-m-long coastal sedimentary cores from Goheung Bay located on the southern coast of Korea to extract such natural variability. Based on the relationships among total organic carbon (TOC), total sulfur (TS) content, and their isotopic values (δ13CTOC and δ34STS), we reconstructed the long-term coastal evolution in the area and compared this with the reported Holocene sea level change. Time series data of the titanium (Ti)/aluminum (Al) ratio, as a proxy for riverine terrigenous input, revealed a strong link to terrestrial plant contribution, as indicated by δ13CTOC variability, suggesting past hydroclimatic change in the study area. The short-term variability of Ti/Al ratios correlated well with flooding events reconstructed for the Nakdong River in Korea. Moreover, periods in which the Ti/Al ratio was higher corresponded to those of stronger El Niño Southern Oscillation (ENSO) activity, suggesting ENSO-driven hydroclimatic changes in southern Korea. Especially, the periods of higher Ti/Al ratios during the late Holocene corresponded to a higher frequency of typhoon-driven overwash events along the southwestern coast of Japan. These similarities suggest that past freshwater input events along the southern coast of Korea were influenced considerably by typhoon-driven heavy rains during stronger ENSO activity. Spectral analysis of the Ti/Al ratios revealed significant periodicities of 1550, 780, 140, 120 and 105 years, suggesting centennial to millennial-timescale variability in hydroclimatic change and typhoon activity over East Asia.

Longshore Transport Variability of Beach Face Grain Size: Implications for Dune Evolution

This study investigates grain-size sorting through longshore transport processes and how it influences dune evolution.The analysis is based on a data set of 58 sediment samples distributed alongshore over a 6.5-km-long sandy beach in Angelholm, Sweden. Grain size differs significantly from north to south, where median grain size varies from about 0.4–0.15 mm. The long-term coastal evolution is derived from shoreline change analysis of a series of aerial photos from the1940s until today and from longshore sediment transport rates calculated on the basis of wave data simulated by the SWAN wave model employed in the Coastal Engineering Research Center (CERC) formula. The results show an almost unidirectional longshore transport from north to south; the beach is eroding in the northern part and accreting in thesouthern part. The McLaren model, a grain size–based model to predict transport direction, was tested against the grainsize data. The test indicated transport in the opposite direction. This result supports previous studies suggesting that the McLaren model has limited applicability for sandy beaches with a dominant longshore transport. The sediment sampleswere collected at the mid–beach face position in an area where sediment is supplied to the beach during accreting conditions. Sediment in the appropriate grain size to build dunes—at this beach, 0.2–0.3 mm—was found in the parts ofthe beach where the dunes are growing. In the eroding parts, the sediment was coarser, suggesting that the longshore transport influences the supply of sediment for aeolian transport. The gradients in longshore transport rate were also found to affect dune morphology; the dunes were higher in the eroding and stable parts of the beach and lower in the accreting parts.

DEVELOPING A SUSTAINED AND COORDINATED U.S. COASTAL RESEARCH PROGRAM

To address societal needs along the coast, a community of researchers from Federal agencies, academia, industry, & NGOs are developing a National science plan. The goal is to identify and address research priorities through better coordinated Federal activities to enhance funding sources, strengthen academic programs, and build a skilled workforce. This abstract describes a grassroots effort, initiated by researchers, that has led to meaningful engagement from the coastal community and swift action to build a National plan. The effort began in Mar 2014 when academic & Federal researchers, convened the Future of Nearshore Processes Workshop to develop a research vision to address societally-relevant coastal science challenges. They organized science needs in three broad research themes, 1) long-term coastal evolution 2) extreme events and 3) human and ecosystem health, identified a need to strengthen science infrastructure (e.g. observations and modeling) and recommended creation of a U.S. Coastal Research Program and Nearshore Advisory Council (NAC) to support the vision (Nearshore Processes Community 2015).

Spatial and temporal patterns of shoreline change of a 280-km high-energy disrupted sandy coast from 1950 to 2014: SW France

A dataset of 15 geo-referenced orthomosaics photos was generated to address long-term shoreline change along approximately 270 km of high-energy sandy coast in SW France between 1950 and 2014. The coast consists of sandy beaches backed by coastal dunes, which are only disrupted by two wide tidal inlets (Arcachon and Maumusson), a wide estuary mouth (Gironde) and a few small wave-dominated inlets and coastal towns. A time and spatially averaged erosion trend of 1.12 m/year is found over 1950–2014, with a local maximum of approximately 11 m/year and a maximum local accretion of approximately 6 m/year, respectively. Maximum shoreline evolutions are observed along coasts adjacent to the inlets and to the estuary mouth, with erosion and accretion alternating over time on the timescale of decades. The two inlet-sandspit systems of Arcachon and Maumusson show a quasi-synchronous behaviour with the two updrift coasts accreting until the 1970s and subsequently eroding since then, which suggests that shoreline change at these locations is controlled by allocyclic mechanisms. Despite sea level rise and the well-established increase in winter wave height over the last decades, there is no capture of significant increase in mean erosion rate. This is hypothesized to be partly the result of relevant coastal dune management works from the 1960s to the 1980s after a long period of coastal dune disrepair during and after the Second World War. This study suggests that long-term shoreline change of high-energy sandy coasts disrupted by inlets and/or estuaries is complex and needs to consider a wide range of parameters including, non-extensively, waves, tides, inlet dynamics, sea level rise, coastal dune management and coastal defences, which challenges the development of reliable long-term coastal evolution numerical models.

A Modeling Approach to Assess the Key Factors in the Evolution of Coastal Systems: the Ebro North Hemidelta Case

One-Line shoreline evolution models have been used as a tool to understand and forecast long-term coastal evolution. However, in some coastal environments, where the influence of the wind is important, the limitations of existing models preclude its direct application to characterize its effect on sediment transport processes. To fill this knowledge gap, we have developed a shoreline evolution model that includes the effect of wind on longshore sediment transport and accounts for beach-dune sedimentary exchange due to aeolian transport. The model produces quantitative estimates of sediment transport and exchanges rates alongshore, easing the assessment of the role of different forcing agents in coastline evolution. The model was applied to the Ebro north hemidelta coast. The results are used to discuss the relative importance of the wind interaction in the evolution of different coastline stretches. Aeolian sand transport at Riumar Beach could cause coastal erosion. At the rectilinear coast, aeolian exchange does not seem to influence the shoreline evolution but the wind-current interaction does. The model provides valuable data when considering the approach to be taken regarding conservation measures. Alongshore aeolian sediment transport can be useful when designing and placing aeolian sediment traps. Conservation of the Ebro north hemidelta coast needs to focus on increasing the river sediment supply. The application herein presented can be regarded as a first step in understanding wave and wind coupling effects in shoreline evolution.

Observation of Wave Transformation on Macro-tidal Rocky Platforms

ABSTRACT Poate, T.G.; Masselink, G; Austin, M.; Dickson, M.E., and Kench, P., 2016. Observations of Wave Transformation on Macro-Tidal Rocky Platforms. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 602–606. Coconut Creek (Florida), ISSN 0749-0208. Correctly predicting the transformation of ocean waves across rocky platforms has direct implications for cliff stability modelling, coastal defences and long-term coastal evolution. Wave transformation across rocky intertidal platforms is dependent on the morphological characteristics of the platform, including platform width, slope and roughness, and forcing characteristics, including wave and tide conditions. In this paper we present early observations from four field studies providing detailed measurements of wave processes across contrasting rocky platform sites with wave conditions between Hs = 0...

The Grand Popo beach 2013 experiment, Benin, West Africa: from short timescale processes to their integrated impact over long-term coastal evolution

ABSTRACT Almar, R., Hounkonnou, N., Anthony, E., Castelle, B., Senechal, N., Laibi, R., Mensah-Senoo, T., Degbe, G., Quenum, M., Dorel, M., Chuchla, R., Lefebvre, J-P, du Penhoat, Y., Laryea, W.S., Zodehougan, G., Sohou, Z., and Appeaning Addo, K., Kestenare, E., 2014. The Grand Popo beach 2013 experiment, Benin, West Africa: from short timescale processes to their integrated impact over long-term coastal evolution. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 651–656, ISSN 0749-0208. The first large nearshore field experiment in the Gulf of Guinea was conducted at Grand Popo Beach, Benin, in February 2013, on an open wave-dominated micro- to meso-tidal coast, located mid-way between Cotonou and Lome harbours. The overall project aims at understanding at multi-scale (from event to interannual) the causes of the dramatic erosion observed throughout the Bight of Benin, and caused by ...

Review of the long-term coastal evolution of North Oman - subsidence versus uplift

Review of the long-term coastal evolution of North Oman - subsidence versus uplift

Shoreline changes and high-energy wave impacts at the leeward coast of Bonaire (Netherlands Antilles)

Supralittoral coarse-clast deposits along the shores of Bonaire (Netherlands Antilles) as well as increased hurricane frequency during the past decade testify to the major hazard of high-energy wave impacts in the southern Caribbean. Since deducing certain events from the subaerial coarse-clast record involves major uncertainties and historical reports are restricted to the past 500 years, we use a new set of vibracore and push core data (i) to contribute to a more reliable Holocene history of regional extreme-wave events and (ii) to evaluate their impact on shoreline evolution. Multi-proxy palaeoenvironmental analyses (XRF, XRD, grain size distribution, carbonate, LOI, microfossils) were carried out using nearshore sedimentary archives from the sheltered western (leeward) side of Bonaire and its small neighbour Klein Bonaire. In combination with 14C-AMS age estimates the stratigraphy reflects a long-term coastal evolution controlled by relative sea level rise, longshore sediment transport, and short-term morphodynamic impulses by extreme wave action, all three of which may have significantly influenced the development of polyhaline lagoons and the demise of mangrove populations. Extreme wave events may be categorized into major episodic incidents (c. 3.6 ka [?] BP; 3.2–3.0 ka BP; 2.0–1.8 ka BP; post-1.3 ka [?] BP), which may correspond to tsunamis and periodic events recurring on the order of decades to centuries, which we interpret as severe tropical cyclones. Extreme wave events seem to control to a certain extent the formation of coastal ridges on Bonaire and, thus, to cause abrupt shifts in the long-term morphodynamic and ecological boundary conditions of the circumlittoral inland bays.

Hurricane-associated ebb-tidal delta sediment dynamics

Bathymetric surveys conducted before and after the 2005 hurricane season at Little Pass Timbalier in the Mississippi River delta plain, United States, demonstrate that 9.1 (±2.4) × 10 6 m 3 of sediment was eroded from a 47.9 km 2 area. Between the two surveys, Hurricanes Cindy, Katrina, and Rita passed within 300 km of the tidal inlet. Comparison of before and after bathymetric data sets shows that the distal portion of the ebb-tidal delta (ETD) was the site of 63% of the total erosion, locally resulting in 400 m of shoreface retreat. Shoaling (0.75–1.0 m) in the seawardmost portion of the ebb channel and erosion in the landward portion (~1.5 m) resulted in a 160 m landward shift of the inlet throat. Collectively, these processes forced the landward migration of the entire tidal inlet and ETD system. There has been considerable discussion about large volumes of mineral sediment deposited on the Mississippi River delta plain interior marsh surface as a result of hurricanes; however, the origin of this sediment is unknown. We identify the distal portion of an ETD as one possible sediment source and hypothesize that ETD and shoreface sediment is mobilized by hurricane waves and transported landward by surge-induced currents. Our results emphasize the role of frequent and intense hurricanes in long-term coastal evolution and as a mechanism for regional sediment retention within the transgressive system beyond typical barrier overwash processes.

Sustainable Coastal Zone Management: A Concept for Forecasting Long-Term and Large-Scale Coastal Evolution

Climate change exerts pressure on the coastal zone by altering sediment supply from the hinterland and rising sea levels. Human activity affects the dynamics of the coastal zone as well. Both natural and human-induced changes in variables that govern coastal dynamics have a profound effect on the long-term and large-scale evolution of the coastal zone. In this paper, we introduce a concept that addresses the components relevant in sustainable integrated coastal zone management. We illustrate that quantifying sediment budgets in the coastal zone might improve our understanding of long-term (>100 y) coastal evolution. The increasing attention within sustainable coastal management on sensitivity analyses of climate change impacts and socioeconomic activities in the coastal zone implies an increasing demand of probabilistic scenarios of coastal evolution spanning a time interval of ∼100 years. Within probabilistic scenarios of coastal evolution, the quantification of the coastal sediment budget cannot be discarded.

Shoreface morphodynamics along the Holland Coast

Abstract The morphodynamic behaviour of the shoreface of the Holland coast has been investigated over the medium- and large-scales (years to decades). This is a wave-dominated, uniform coastline backed by dunes and uninterrupted by tidal inlets. The work takes a data-orientated approach using the ‘long’ profiles in a data set extending over 32 years and covering 81 km of coast. These profiles are spaced every 1 km alongshore and extend to a maximum offshore distance of 3 km (approximately 16 m water depth). Previous work based upon cross-shore profiles suggests that there is a seaward limit to significant depth change, or activity, on the upper shoreface over the small- and medium-scales (termed ‘depth of closure’). Examination of the data set shows that the middle and lower shoreface is also morphologically active in many instances, with the activity increasing with timescale. Many profiles exhibit closure on the upper shoreface, and then reopen on the middle/lower shoreface, exhibiting morphological activity. This deeper shoreface morphodynamics appears to be related to onshore supply of sand to the active zone. Hence, the analysis shows that the upper, middle and lower shoreface are coupled, as widely assumed, and has widespread significance for understanding long-term coastal evolution.

Late Glacial to Holocene coastal changes of SE Rügen Island (Baltic Sea, NE Germany)

The aim of this study was to investigate the long-term coastal evolution of Monchgut peninsula (Rugen Island) on the non-tidal SW Baltic Sea coast. The geological setting of the barriers was determined by coring Late Pleistocene to Holocene deposits. The sediment succession starts with a Late Glacial till overlain by Late Pleistocene/Early Holocene sandy freshwater deposits of fluvial origin. There is no evidence that any early evolutionary stages of the Baltic Sea (i.e. Baltic Ice Lake, Ancylus Lake) reached the study area. In the Boreal, the landscape was characterized by W-E striking channels, interpreted as valleys of a river system. These valleys are up to 15 m deep. The Littorina transgression inundated the study area in the Early Atlantic. Our work indicates that the rate of sea-level rise was the most important factor controlling coastal evolution on Rugen Island. The rapid rising water level drowned the coastal area, while during the period of a moderate rise (~1 mm/yr) sediment was transported along the shore to accumulate as beach ridges and wind flats.