Shoreline Retreat Research Articles

Short-term shoreline evolution trend assessment: A case study in Glefe, Ghana

The growing economic, social and ecological importance of coastal areas in Ghana has increased the challenges associated with sustainably managing the coastal resources. The coastal areas have become more prone and vulnerable to natural and human-made hazards such as coastal erosion. Shoreline retreat is recognised as a burgeoning threat because of global climate change and other anthropogenic activities that alter the natural processes sustaining beaches and coasts. This article describes an application of Real-time Kinematic-Global Positioning System (RTK-GPS) technology and digitising of shorelines from orthophotos to detect and analyse the spatial changes as well as quantify the result of shoreline change at Glefe, a suburb of Accra in Ghana. Shoreline positions from a 2005 orthophoto and a 2011 RTK-GPS survey were overlaid in MATLAB (Matrix Laboratory) and the average rate of change determined using the endpoint rate (EPR) method. The shoreline change rate determined for Glefe between 2005 and 2011 was 1.2 m/a ± 1.3 m/a, indicating a relatively high rate of erosion. Outcomes of the case study can be used as a basis for a sustainable integrated management plan for the coastal area.

Potential impacts of extreme storm surges on a low-lying densely populated coastline: the case of Dunkirk area, Northern France

Along the southern coast of the North Sea, a large proportion of the Flemish coastal plain consists of densely populated reclaimed land, much of which lying below mean high tide level. This is particularly the case along the northern coast of France, from Dunkirk to the Belgium border, where the shoreline consists of coastal dunes that protect low-lying reclaimed lands from marine flooding. This area is vulnerable and subject to several risks. Extreme weather conditions could induce strong surges that could cause (1) a shoreline retreat, (2) marine submersion and (3) land and/or urban flooding due to drainage problems of the polders. Highly energetic events such as the November 2007 storm could have had much more severe consequences especially if they occurred at high tide and/or during a spring tide. In the current context of global change and projected sea-level rise, it is then important for the local authorities to take into account the potential impacts and return periods of such events, in order to implement coastal risk policies prevention and management, to reinforce sea defense, increase pumping station efficiency and plan warning systems against marine submersion and polder flooding, which is not the case yet in Northern France.

Mixed Siliciclastic-Carbonate Upward-Deepening Cycles of the Upper Cambrian Inner Detrital Belt of Laurentia

Abstract High-resolution sedimentological and biostratigraphic data recently recovered from Upper Cambrian strata in the northern Rocky Mountain and central Appalachian regions reveal that meter-scale cycles of very different character developed synchronously during deposition of the basal subzones of the Ibexian Series in both the carbonate facies belt and the distal part of the inner detrital, mixed siliciclastic–carbonate facies belt of the Laurentian paleocontinent. A typical mixed siliciclastic–carbonate cycle in the Snowy Range Formation of Wyoming and Montana consists of the following lithofacies in ascending order: shale, shale with very thin grainstone interbeds, grainstone with subordinate thin shale interbeds, flat-pebble conglomerate, and (in some cycles) thrombolitic bioherms. Internal transitions between the constituent lithofacies are mostly gradational, but cycle boundaries are sharp with shale directly overlying flat-pebble conglomerate and/or thrombolitic boundstone. We postulate that these mixed siliciclastic–carbonate cycles developed in response to different depositional dynamics than meter-scale cycles developed in carbonate-belt facies. Specifically, cycles in the carbonate belt were produced largely by temporal variation in accommodation space, and associated filling of that space through progradation of the carbonate system and aggradation to sea level. In contrast, cyclic deposition within the inner detrital belt was controlled by variations in terrigenous sediment input and resulting effects on carbonate productivity. In this case, enhanced delivery of siliciclastic mud by rivers was triggered by regression and/or a shift to more humid climatic conditions. An upward increase of carbonate in the main part of the cycles reflects enhanced carbonate production in response to the reduction of terrigenous clay supply during shoreline retreat. Widespread cementation of fine grainstone substrates led to deposition of extensive beds of flat-pebble conglomerate, possibly in association with elevated sea-surface temperatures and enhanced storm intensity. Thrombolites formed at times of maximum transgression as microbial communities thrived in the absence of turbidity, colonizing the irregular surfaces of flat-pebble conglomerate beds. We thus interpret these wholly subtidal cycles to record full changes in paleobathymetry with the bulk of the cycles recording upward deepening, rather than shoaling associated with regression. Comparison with age-equivalent shoaling cycles of the Conococheague Formation of the carbonate belt of the Appalachian Mountains highlights the different depositional dynamics in the mixed siliciclastic–carbonate systems, and underscores the peril in extrapolation of depositional models derived from carbonate systems to mixed systems, regardless of age or paleogeographic setting.

The regeneration ecology of Empetrum nigrum, the black crowberry, on coastal heathland in Nova Scotia1This article is part of a Special Issue entitled “A tribute to Sam Vander Kloet FLS: Pure and applied research from blueberries to heathland ecology”.

The reproductive cycle of the black crowberry ( Empetrum nigrum L., Ericaceae) was investigated on exposed headlands on the Atlantic coast of Nova Scotia. At the main study site, Gaff Point, aerial photographs revealed a shoreline retreat rate from 1976 to 2011 (ca. 0.3 m·y–1), with a threefold increase in the rate of heath area loss in the last 10 years relative to the previous 25 years (1976–2001). Empetrum nigrum produces a large crop of berries and sets up seedlings via three main dispersers (gulls, passerines, and mink) at the sea edge and woodland margin. Laboratory study demonstrated that seed germination was scant and slow in the season of berry production but that it was rapid and substantial (mean 33%–50% from berry or scat) for seeds that incubated overwinter in berry or in scat. The largest seed bank coincides with the site of greatest berry production in the heath, but seedlings were not observed in its mat. Most of the scat rain (77%) is deposited at the shore edge and seedlings here are lost to coastal erosion over-winter. Spruce tree understories are the only safe sites for seedling establishment, and if these juveniles become adults of heathland formed after the death of edge trees, the crowberry has an ontogenetic niche shift adapted to climate change. A preliminary checklist is provided for conservation managers of coastal heaths.

A new GIS modelling of coastal dune protection services against physical coastal hazards

Coastal dune management presents a unique problem to coastal scientists, not only because of the dynamic and complex nature of coastal dune systems but also because of the protection service against many coastal hazards such as storm surges in low and flat coastal countries, shoreline retreat, and aeolian erosion. In order to evaluate such a service, a new GIS modelling of a coastal dune protection service has been carried out on Noirmoutier Island. It is based upon geoinformation coming from LIDAR, Spot satellite and aerial photography data processing. This paper discusses the Geographic Information System (GIS) methodology used for data acquisition and analysis and presents a methodology developed (i) to characterise and map dune shapes using geoindicators in order to highlight aeolian deflation, marine coastal erosion and marine submersion over the long-term and (ii) to set up a transferable and synthetic methodology. This methodology is based upon spatial syntheses computed in regular 50 m*400 m boxes built up landward from the shoreline. Each variable is integrated within each box. This allows to quantify (i) spatial occurrence of each variable and (ii) spatial coincidence of many variables within each box. Each protection service is underlying by a set of variables. The state of the protection service is then discussed and quantified and can be used by stakeholders to manage dunes in a safe way for society stakes.

Shoreline Analysis and Barrier Island Dynamics: Decadal Scale Patterns from Cedar Island, Virginia

Abstract Nebel, S.H.; Trembanis, A.C., and Barber, D.C., 2012. Shoreline analysis and barrier island dynamics: Decadal scale patterns from Cedar Island, Virginia. Aerial photography, topographic maps, high-resolution satellite imagery, and global positioning system (GPS) data were compiled in ArcMAP™ and analyzed using the Digital Shoreline Analysis System (DSAS) to determine decadal trends of shoreline movement on Cedar Island, Virginia. Shoreline retreat rates for Cedar Island had an alongshore average of −4.1 m/y based on simple endpoint analysis (1852–2007), while the short-term (1994–2007) retreat rates increased to −12.6 m/y. Retreat statistics were further calculated for the time intervals 1852–1910 (−5.1 m/y), 1910–62 (−3.5 m/y), 1962–80 (−3.9 m/y), 1980–94 (−6.5 m/y), 1994–2002 (−12.4 m/y), and 2002–06 (−13.8 m/y). This analysis indicates that retreat of the Cedar Island shoreline has been accelerating with a notable increase in rate within the years 1980 to 1994. Additionally, the shoreline data...

Sequence stratigraphy and controls on reservoir sandstone distribution in an Eocene marginal marine-coastal plain fairway, Taranaki Basin, New Zealand

Middle to Upper Eocene strata in Taranaki Basin, New Zealand, consist of terrestrial, marginal marine, shallow marine and offshore sediments deposited in a series of transgressive and regressive cycles within a passive margin setting. Coastal plain facies are largely confined to eastern and southern sides of the basin and marine mudstones to western and northern parts. Shoreface to fluvial sandstones within a NE–SW-oriented coastal facies belt form the pre-eminent petroleum reservoir fairway in Taranaki Basin, and provide the bulk of New Zealand production. The terrestrial coastal plain part of the succession also contains coal-rich proven source rocks.We have interpreted twelve depositional sequences (3rd and 4th order) within the Middle to Upper Eocene strata. The base of our study interval marks a relative transgression within the Middle Eocene, and is overlain by composite sequences and parasequences, represented by cyclically stacked packages. Overall regression occurs up to the top of the Middle Eocene, which is overprinted by intermittent, shorter-term transgressions. The overlying Upper Eocene strata are characterised by overall shoreline retreat with final transgression over the entire Taranaki Basin in the latest Eocene/Early Oligocene. Stratigraphic cyclicity within the terrestrial to shallow marine facies is noted from paleoenvironmental interpretations determined from well log, core, biostratigraphic and coal sulphur data. Whilst eustasy may have played a role in development of the Taranaki stratigraphy, tectonically-induced subsidence was probably the over-riding factor, especially in the Upper Eocene.Petroleum-producing reservoirs occur at several distinct horizons within the Middle to Upper Eocene succession, interpreted here to represent significant events during sequence development. Most reservoir sandstones were deposited as channelised facies following 3rd order lowstands. Sequence boundaries are interpreted at the base of many of these sandstone intervals, some of which may represent Type 1 boundaries developed as incised-valley systems.This regional study has used an integrated approach to show how sequence stratigraphy can be applied to a non-marine to shallow marine succession to assist with exploration and reservoir development. Through our recent and multi-disciplinary work, we have been able to discriminate subtle base level fluctuations and greater marine control of depositional architecture than has previously been recognised, with implications for source rock quality, fairway exploration, reservoir charge and production effectiveness.

Human Impact on Shoreline Evolution Along the Follonica Gulf (Southern Tuscany): How Tourism May Kill the Goose that Lays the Golden Eggs

CIPRIANI, L.E., FERRI, S., LAMI, G and PRANZINI, E., 2011. Human Impact on Shoreline Evolution Along the Follonica Gulf (Southern Tuscany): How Tourism May Kill the Goose That Lays the Golden Eggs. In: Micallef, A. (ed.), MCRR3-2010 Conference Proceedings, Journal of Coastal Research, Special Issue, No. 61, pp. 290–294. Grosseto, Tuscany, Italy, ISSN 0749-0208.Follonica Gulf beach is subject to widespread low-rate erosion, which started in the 19th Century due to river diversion for coastal marsh reclamation. Once rivers were re-directed to the coast; land subsidence induced by water extraction sustained erosion. From 1954 to 1984 mean shoreline retreat was approximately 9 m.In the 1960's, development of coastal tourism villages increased beach use and the need for house protection from storms. Detached breakwaters were built, trapping sand from adjacent coastal sectors. This induced shoreline progradation in protected sectors creating a wider beach, but unprotected coastal sectors experienced severe erosion. Stakeholders requested additional protection: the most developed area was gradually protected by detached breakwaters up to complete closure. Comparing the 2005 and 1954 shoreline positions, we see that out of the total length of approximately 21 km of coastline 8 km are accreting; less than 1 km is stable and over 12 km are eroding. Recently, a marina was built on the eastern margin of the study area; however wave diffraction at breakwater tip induced longshore transport and entrance siltation at the cost of western neighbouring beaches.Tourism industry stakeholders, whose economy is based on beach width and quality, were responsible for such coastal degradation, but now cooperate with local and regional administrations, accepting reduction in the use of hard defences - although shoreline realignment will end up penalising someone. Some detached breakwaters have been lowered to 50 cm below mean sea level, whereas others will undergo similar reshaping in the near future. The two oldest sets of coastal defence are now under study, in order to find solutions for a gradual return to more natural conditions. Changes to the marina configuration are being designed to prevent siltation, reaching a new equilibrium for the adjacent beach. We now realise that money spent for shore protection in some sectors would have maintained the 1950's shoreline position along the whole Gulf using beach nourishment, with no landscape deterioration.

A geotechnical and GIS based method for evaluating risk exposition along coastal cliff environments: a case study of the chalk cliffs of southern England

Abstract. The present work has established a methodology that allows the user to determine areas susceptible to shoreline recession and cliff instability. This methodology includes the development of a qualitative loss estimation system which utilizes geotechnical field mapping observations and shoreline retreat predictions to estimate the exposition of critical infrastructure to hazards posed by cliff collapse and retreat. The technique identifies hazardous areas along coastal cliff environments. The assessment was undertaken along the cliff section between Brighton Marina and Portobello, East Sussex, UK. The cliff line was divided into 22 sections according to the cliff's geology. Each of these sections was mapped and described with respect to the lithology and possible failures that could occur. Historical shoreline recession analysis was used for the prediction of future shoreline positions. The prediction of future shorelines was performed by using the Digital Shoreline Analysis System, extension of ESRI's ArcView 9.x. The analysis was based on historical maps and aerial photographs dating from 1873 to 2005. The long term average cliff recession rates clearly show that cliff retreat has declined through time due to the presence of coast protection and cliff stability measures. Although these measures have delayed cliff recession to a great extent, they have not eliminated it.

Shoreline retreat and sediment release in response to accelerating sea level rise: Measuring and modelling cliffline dynamics on the Suffolk Coast, UK

Contemporary and historic data for shoreline retreat are used to evaluate and test a range of models that predict shoreline response to accelerating sea level rise. Models are tested against the known record of sea level rise acceleration over the twentieth century on the cliffline position of a series of soft rock cliffs located along the Suffolk Coast, UK. These cliffs have experienced high retreat rates throughout the twentieth century (between 2 and 4.5 m a − 1 ). The shoreline response model most suited to such an assessment is the SCAPE model, with a close fit between actual and modelled shoreline positions. Retreating shorelines also have associated changes in alongshore elevation, an aspect of shoreline retreat that has attracted little attention. Recently acquired IfSar data now permit detailed and accurate assessment of ground elevation from which the elevation of future clifflines can be derived. Combining elevation data with future shoreline retreat, also predicted using the SCAPE model, enables future sediment release from the cliffs to be evaluated. The methodology has the ability to take into account alongshore variability in retreat rates, where previously most studies focus upon a single rate for a given shoreline. This paper thereby identifies behaviour based around “switching on”, “no change” and “switching off” in cliff systems. Volumes of sediment released in the twenty first century in response to accelerating sea level rise are likely to be considerable (up to 300 000 m 3 a − 1 ) for the Suffolk study area, and around an order of magnitude above the sediment release estimates for the early twentieth century under lower rates of sea level rise. The implications for shoreline protection offered from additional sediment in the nearshore zone are discussed.

Morphological response and coastal dynamics associated with major storm events along the Gulf of Lions Coastline, France

Along the coast, anticipating the different morphological responses induced by storm events is crucial for managers to evaluate coastal risks and to develop the best measures to mitigate them. In this paper, a methodology is developed to determine the best storm intensity parameter to derive storm thresholds for different morphological responses. The methodology is applied to the northern part of the Gulf of Lions coastline where storm events can induce important morphological changes. These include shoreline retreat, beach and dune erosion, significant migration of nearshore bars, overwashes and even breaches of coastal barriers, as well as damage to coastal defences and coastal infrastructure. In order to evaluate historical storm characteristics and impact, an extensive review was undertaken to obtain quantitative datasets (beach profiles, wave records), aerial photographs and more qualitative information on morphological evolution and coastal damage. Re-analysis of hydrodynamic and morphology data was undertaken, and hindcast wave modelling results were used to characterised storm intensities. The methodology developed to evaluate storm thresholds consists of obtaining morphological evolution indicators (evidence of breaching, overwash processes, volume variations and migration of morphological patterns) that can be directly linked to a storm event and its characteristics. Results demonstrate that in such a quasi-non-tidal wave-dominated environment, with intermediate double-barred beach shoreface morphology, major coastal changes occur following the maximum significant wave height reached during the storm, or else according to maximum wave run-up elevation regarding upper beach impact, a wave height dependant parameter. Inversely storm surge (and water level) alone, as well as total storm energy, do not explain any storm impact scale. Storm-specific datasets indicate that important morphological evolution is observed during moderate storm events (significant wave heights over 2.7m). Above this threshold, the morphological behaviour changes radically. The main characteristics are a rapid offshore migration of the nearshore bars and large deposition of sand on the upper beach. However, the major morphological changes are associated with even more energetic events. When the significant wave height reaches 5m, important impacts are observed: breaching and overtopping of natural coastal barriers, and severe dune erosion and impacts to coastal infrastructure on urbanised beaches. Qualitative observations show an important increase in damage when the storm waves reach 5m. The methods employed can be applied easily to any coastal segment and provide coastal managers with tools to evaluate different coastal evolution and coastal damage induced by storm events.

Climate change impacts on coastal and pelagic environments in the southeastern Bay of Biscay

The impacts of global climate change on the Basque coast and the pelagic systems within the southeastern Bay of Biscay are reviewed. Climate projections under greenhouse gas emission scenarios indicate that this area will experience changes in climate throughout the 21st century, including warming of surface air (especially heat wave episodes), intensification of extreme daily rainfall (10%), warming of the upper 100 m of the ocean layer (1.5 to 2.05°C), and sea level rise (SLR; 29 to 49 cm). Observations made in the bay throughout the 20th century for air temperature and mean sea level are in agreement with these projections. Trends in ocean-climatic historical observations within the area, including sea temperature, precipitation, upwelling/downwelling, turbulence and wave climate, are also reviewed. The main impacts on the coast are expected to be from SLR, especially in low-lying areas (mostly urbanised) within estuaries. Sandy beaches are also expected to undergo significant mean shoreline retreats of between 25 and 40% of their width. As the sea level rises, the natural migration of saltmarshes and intertidal seagrasses landward will be constrained, in most cases, by existing anthropogenic fixed boundaries. Empirical relationships between the distribution and dynamics of the long-term biological measures (plankton, primary production, benthos, and fisheries) on the one hand, and ocean-climatic variability on the other, indicate that pelagic and coastal water ecosystems will be affected by ocean warming, increased stratification, shifts in anomaly patterns and streamflow regimes. The largest uncertainties are associated with the lack of downscaled projections within the bay on ocean circulation, ocean-meteorological indices, wave climate and ocean acidification.

Beach and nearshore morphodynamic changes of the Tabarka coast, Northwest of Tunisia

Aerial photographs taken in the 1963 and 2001 and bathymetric charts, in conjunction with coastal processes are analyzed to assess changes in rate of shoreline position, seabed level, and seabed grain sizes along the Tabarka–Berkoukech beach at the north-western Tunisian coastline. The littoral cell of this beach, 12-km-long, is bounded by pronounced embayments and rocky headlands separated by sandy stretches. Although not yet very much undeveloped, this littoral is still experienced degradation and modification, especially along its shoreline, with significant coastal erosion at some places. Results obtained from analysis of shoreline position indicate that El Morjene Beach is experienced a landward retreat of more than −62 m, at a maximum rate of −1.64 m/year, whereas the El corniche beach is advanced about 16–144 m, at an average rate of 0.42 m–3.78 m/year. This beach accretion has been formed on the updrift side of the Tabarka port constructed between 1966 and 1970. Comparison of bottom contours deduced from bathymetric charts surveyed in 1881 and 1996 off the coastline between Tabarka Port and El Morjene Beach identifies erosional areas (sediment source) and accretionary zones (sediment sink). Erosion (0.87–4.35 cm/year) occurs between El kebir River Mouth and El Morjene beach, whereas accretion exists in the zone down wind of the port ranges between 0.87 and 5.21 cm/year. Morphological analyses of the shoreline and the seabed of the study nearshore area indicate that shoreline retreat corresponds to areas of seabed scour (sediment source) while shoreline accretion is associated with areas of seabed deposition (sediment sink). Furthermore, simulation of wave propagation using STWAVE model combined with grain size distributions of the seabed shows that fine sands are much dominated in depositional areas with low wave energy, whereas coarser sands in erosive zones with high wave energy. The results obtained suggest that the change of seabed morphology, wave height pattern and grain size sediment have a great influence on the modification of shoreline morphology and dynamics.

Historical changes in the shoreline and littoral processes on a headland bay beach in central Chile

We applied parabolic and logarithmic adjustments and methods of cartographic overlay to the sandy littoral of Concón bay (Central Chile) to determine the changes associated with the shoreline and their relation with littoral processes, in a typical bay on an active continental margin and with a microtidal regime. A set of historical reference points was built by means of aerial photographs and topographies for the period 1945–2008. Given the form of the shoreline, to the southern section of the bay we applied the classical logarithmic formula of Yasso (1965) and the functions incorporated in the Coastal Modeling System (Sistema de Modelamiento Costero, SMC) of the Universidad de Cantabria. In the northern section a method of map overlay was applied. The Oluca-SP model of the SMC was used to determine the influence of waves (refraction) on the types of changes of the shoreline. Information on waves (1985–2006), mean sea level (2001–2006) and variations in the mean size of beach sediment were used to relate the changes in the plan form of the bay. There has been little spatio-temporal variability in the shoreline of the bay over the last 65 years. The southern section had a mean shoreline retreat rate of − 0.55 m/year (1945–2008) in spite of the large variability produced in an estuary dominated by waves. The best adjustment was obtained with the logarithmic function. In the northern section the mean accretion rate was 0.39 m/year (1954–2008). The plan form and the historical changes of the shoreline are closely associated with the seasonal changes of the waves and the presence of rocky thresholds in the area. The mean sea level did not produce important effects in the types of change.

Oyster Reefs as Natural Breakwaters Mitigate Shoreline Loss and Facilitate Fisheries

Shorelines at the interface of marine, estuarine and terrestrial biomes are among the most degraded and threatened habitats in the coastal zone because of their sensitivity to sea level rise, storms and increased human utilization. Previous efforts to protect shorelines have largely involved constructing bulkheads and seawalls which can detrimentally affect nearshore habitats. Recently, efforts have shifted towards “living shoreline” approaches that include biogenic breakwater reefs. Our study experimentally tested the efficacy of breakwater reefs constructed of oyster shell for protecting eroding coastal shorelines and their effect on nearshore fish and shellfish communities. Along two different stretches of eroding shoreline, we created replicated pairs of subtidal breakwater reefs and established unaltered reference areas as controls. At both sites we measured shoreline and bathymetric change and quantified oyster recruitment, fish and mobile macro-invertebrate abundances. Breakwater reef treatments mitigated shoreline retreat by more than 40% at one site, but overall vegetation retreat and erosion rates were high across all treatments and at both sites. Oyster settlement and subsequent survival were observed at both sites, with mean adult densities reaching more than eighty oysters m−2 at one site. We found the corridor between intertidal marsh and oyster reef breakwaters supported higher abundances and different communities of fishes than control plots without oyster reef habitat. Among the fishes and mobile invertebrates that appeared to be strongly enhanced were several economically-important species. Blue crabs (Callinectes sapidus) were the most clearly enhanced (+297%) by the presence of breakwater reefs, while red drum (Sciaenops ocellatus) (+108%), spotted seatrout (Cynoscion nebulosus) (+88%) and flounder (Paralichthys sp.) (+79%) also benefited. Although the vertical relief of the breakwater reefs was reduced over the course of our study and this compromised the shoreline protection capacity, the observed habitat value demonstrates ecological justification for future, more robust shoreline protection projects.

The impact of the 2009-10 El Niño Modoki on U.S. West Coast beaches

[1] High-resolution beach morphology data collected along much of the U.S. West Coast are synthesized to evaluate the coastal impacts of the 2009–10 El Nino. Coastal change observations were collected as part of five beach monitoring programs that span between 5 and 13 years in duration. In California, regional wave and water level data show that the environmental forcing during the 2009–10 winter was similar to the last significant El Nino of 1997–98, producing the largest seasonal shoreline retreat and/or most landward shoreline position since monitoring began. In contrast, the 2009–10 El Nino did not produce anomalously high mean winter-wave energy in the Pacific Northwest (Oregon and Washington), although the highest 5% of the winter wave-energy measurements were comparable to 1997–98 and two significant non-El Nino winters. The increase in extreme waves in the 2009–10 winter was coupled with elevated water levels and a more southerly wave approach than the long-term mean, resulting in greater shoreline retreat than during 1997–98, including anomalously high shoreline retreat immediately north of jetties, tidal inlets, and rocky headlands. The morphodynamic response observed throughout the U.S. West Coast during the 2009–10 El Nino is principally linked to the El Nino Modoki phenomena, where the warm sea surface temperature (SST) anomaly is focused in the central equatorial Pacific (as opposed to the eastern Pacific during a classic El Nino), featuring a more temporally persistent SST anomaly that results in longer periods of elevated wave energy but lower coastal water levels.

Stratigraphic Architecture of a Net-Transgressive Marginal- to Shallow-Marine Succession: Upper Almond Formation, Rock Springs Uplift, Wyoming, U.S.A.

Abstract The upper part of the Almond Formation records the overall retreat of a wave-dominated shoreline and associated lagoons or bays. Exposures of these strata on the eastern flank of the Rock Springs Uplift, Wyoming, U.S.A., enable analysis of their stratigraphic architectures along sections oriented oblique to depositional strike. The upper Almond Formation comprises at least nine vertically stacked regressive–transgressive cycles. The regressive component of each cycle consists of thick (up to 22 m), laterally continuous wave-dominated shoreface and overlying coastal-plain deposits that occur in paleoseaward locations and have abrupt (< 400 m) paleolandward pinchouts. The transgressive component of each cycle consists of one or more bay-fill successions that occur in paleolandward locations and gradually thin in a paleoseaward direction. Transgressive bay-fill deposits in each cycle are thick (up to 18 m) and associated with preservation of surfaces that record, in progressively paleoseaward locations: initiation of a lagoon or bay (transgressive surface), erosional retreat of tidal-inlet channels (tidal ravinement surface) and the shoreface (wave ravinement surface), and marine flooding (marine flooding surface). This architecture records regression of a strandplain or wave-dominated delta, and subsequent transgression of a barrier island and spit with associated lagoon or bay. The occurrence of such thick and fully preserved bay-fill successions indicates that accretionary transgressive shoreline trajectories were developed. Strongly-aggradational-to-weakly-retrogradational stacking of successive regressive–transgressive cycles results in a layered stratigraphic architecture, with laterally continuous shoreface sandstone layers interbedded with bay-fill shale layers. Shoreface sandstones layers pinch out up-dip abruptly (< 400 m) into bay-fill shales and have limited vertical connectivity. Sandstones within bay-fill and coastal-plain deposits occur as small, laterally discontinuous bodies of variable geometry and connectivity. However, these sandstones may provide additional connectivity where they erode through bay-fill shales between two shoreface sandstone layers.

Dealing with erosion along the Danube Delta coast. The CONSCIENCE experience towards a sustainable coastline management

The most severe shoreline retreat (over 20 m/year) along the Danube Delta coast has been recorded in the coastal stretch confined by the Sulina branch (north) and Sahalin spit island (south). This erosive trend is caused by the natural evolution of some stretches of the Danube Delta coast, but strongly enhanced by the human activities. Human interventions result in the dramatic decrease in quantity of sediments reaching the coast and in the disruption of natural sediment circulation in the coastal area. EUROSION FP5 Project developed four concepts to be used in coastal studies: coastal sediment cell, coastal resilience, favourable sediment status and strategic sediment reservoir. The main objectives of this study regard the application of the CONSCIENCE methodology and test of the concepts in order to identify and understand the main threats for Sulina – Sahalin littoral cell, especially the coastal erosion one, as well as to provide a sound working methodology for coastal managers to deal with these threats. The sediment budget computed in previous studies, as well as the field observations, indicate a lack of sediments for the littoral cell (unfavourable sediment status). In order to asses the vulnerability of the coast to short term extreme events (especially storms), simulations of water level changes were performed and calibrated with the field observations. A processes based numerical model was used to simulate the storm induced water level variations and the main input data were the bathymetry of the active beach, wind direction and speed (storm scenarios) and the characteristics of water and air. The results show large water level increases for the central part of the study zone, especially for northern wind directions. The main solution proposed to deal the problems arising from a sediment-starved coast, vulnerable to the extreme events, is artificial nourishment. Two strategic sediment reservoirs were identified, both of them at the northern boundary of the cell: the sediments dredged periodically from Sulina mouth and the sediments accumulated in Musura Bay, just north of Sulina jetties. The transfer of these sediments towards the central part of the littoral cell Sulina – Sahalin would decrease the erosion rates to a natural level and restore the natural coastal resilience. The methodology developed in CONSCIENCE Framework and applied to Danube Delta coastal zone provided good results when problems and solutions for the coastal zone were to be identified and tested. This methodology and its related results can be applied by the local coastal managers to Sulina – Sahalin littoral cell, while this experience can be extended to other similar environments facing the same problems.

Sedimentary records of natural and artificial Huanghe (Yellow River) channel shifts during the Holocene in the southern Bohai Sea

Two gravity cores collected off the modern Huanghe (Yellow River) delta in the southern Bohai Sea were analyzed for grain size, the total organic carbon (TOC)/total nitrogen (TN) ratio, color diffraction, magnetic susceptibility, 14C dating and 137Cs and 210Pb isotope contents to clarify changes in the sedimentary environment during the Holocene. In particular, the effect of natural and artificial river-course shifts of the Huanghe on the Bohai Sea sediment was investigated. A peat layer, scouring surface and sharp changes in the grain size, TOC/TN ratio, sediment color ( L ⁎, a ⁎) and magnetic susceptibility were identified and are likely to be due to the early-Holocene sea-level rise resulting in environmental changes from coastal to shelf environments in the Bohai Sea. After the sea level reached its maximum at 6–7 ka BP, the lateral shifts in the river course of the Huanghe formed 10 superlobes, and superlobe 7 (11–1048 AD) and superlobe 10 (1855–present) of the Huanghe delta affected the core sites. The northern site of BH-239 has been more affected by the Huanghe since the middle Holocene. Notably, in the superlobe 10 period, the reshaping of the northern Huanghe delta due to an artificial river-course shift from northward to eastward in 1976 (e.g., a∼10 km shoreline retreat due to coastal erosion) was recorded in the core sediments, particularly in terms of the TOC/TN ratio, sediment color ( L ⁎ and a ⁎) and magnetic susceptibility, owing to the huge sediment supply from coastal erosion of the former river mouth area.

A Bayesian network to predict coastal vulnerability to sea level rise

Sea level rise during the 21st century will have a wide range of effects on coastal environments, human development, and infrastructure in coastal areas. The broad range of complex factors influencing coastal systems contributes to large uncertainties in predicting long‐term sea level rise impacts. Here we explore and demonstrate the capabilities of a Bayesian network (BN) to predict long‐term shoreline change associated with sea level rise and make quantitative assessments of prediction uncertainty. A BN is used to define relationships between driving forces, geologic constraints, and coastal response for the U.S. Atlantic coast that include observations of local rates of relative sea level rise, wave height, tide range, geomorphic classification, coastal slope, and shoreline change rate. The BN is used to make probabilistic predictions of shoreline retreat in response to different future sea level rise rates. Results demonstrate that the probability of shoreline retreat increases with higher rates of sea level rise. Where more specific information is included, the probability of shoreline change increases in a number of cases, indicating more confident predictions. A hindcast evaluation of the BN indicates that the network correctly predicts 71% of the cases. Evaluation of the results using Brier skill and log likelihood ratio scores indicates that the network provides shoreline change predictions that are better than the prior probability. Shoreline change outcomes indicating stability (−1 &lt; rate &lt; 1 m/yr) or erosion (rate &lt; −1 m/yr) tend to occur for two sets of input scenarios. Stable shoreline change rates occur mainly for low rates of relative sea level rise and occur in low‐vulnerability geomorphic settings. Rates indicating erosion result for cases where the rate of relative sea level rise is high and moderate‐to‐high vulnerability geomorphic settings occur. In contrast, accretion (rate &gt; 1 m/yr) was not well predicted. We find that BNs can assimilate important factors contributing to coastal change in response to sea level rise and can make quantitative, probabilistic predictions that can be applied to coastal management decisions.