the sea level fingerprint of west antarctic collapse recent projections of sea level rise after a future collapse of thewest antarctic ice sheet for example the fourth intergovernmental panel on climate change assessment report assume that meltwater will spread uniformly that is eustatically across the oceans once marine based sectors of the west antarctic are filled a largely neglected 1977 study predicted that peak values would be 20 higher than the eustatic in the north pacific and 5 to 10 higher along the u s coastline we show with use of a state of the art theory that the sea level rise in excess of the eustatic value will be two to three times higher than previously predicted for u s coastal sites

coupling instrumental and geological records of sea level change evidence from southern new england of an increase in the rate of sea level rise in the late 19th century 1 we construct a high resolution relative sea level record for the past 700 years by dating basal salt marsh peat samples above a glacial erratic in an eastern connecticut salt marsh to test whether or not the apparent recent acceleration in the rate of sea level rise slr is coeval with climate warming the data reveal an average slr rate of 1 0 0 2 mm year from about 1300 to 1850 a d coupling of the regional tide gauge data 1856 to present with this marsh based record indicates that the nearly three fold increase in the regional rate of slr to modern levels likely occurred in the later half of the 19th century thus the timing of the observed slr rate increase is coincident with the onset of climate warming indicating a possible link between historic slr increases and recent temperature increases

geomorphic and stratigraphic analysis of fire island new york abstract barrier islands along the east coast of the united states are believed to be migrating landward in response to sea level rise modes and rates of displacement of fire island along the south shore of long island n y were investigated through geomorphic and stratigraphic analyses inlet processes are principally responsible for bayshore sediment accretion and hence landward displacement while overwash has contributed to increasing the island s elevation portions of marsh areas covered by washover deposits were often raised above the tidal level permitting colonization by barrier flat vegetation photographic analysis showed that only the 1938 hurricane resulted in bayshore accretion by washover a small amount at one locality most of the bayside marshes formed on relict flood tidal delta shoals former inlet sites are characterized by typical geomorphic features including relict inlet ridges indentation of the bay shoreline wide marsh plains and relict flood tidal delta islands in the bay historical records and relict inlet features indicate that as much as 85 of the area has been affected by inlet activity the geomorphic and vegetative data supported by the stratigraphic interpretations showed that the western section of fire island n y is migrating landward more slowly than the eastern section of the barrier chain this trend is probably due to hurricane tracks and to an increased sediment supply to the western part barrier migration is occurring continuously over geologic time but considered on a short term basis displacement is sporadic and related to inlet processes over the past 1000 years fire island has experienced shoreface erosion as well as bayshore erosion and submergence

simulation of large scale coastal change using a morphological behaviour model abstract quantitative simulation of large scale coastal behaviour lscb is possible using a model based only on principles of sand mass conservation and geometric rules for shoreface and active sand body morphology dynamic processes are subsumed into a set of parameters that define the geometry of the active cross shore profile which in turn can represent an entire coastal cell the parameters together with a set of local behaviour rules governing adjustments at discrete points along the profile provide a simple formulation that is constrained by sediment mass balance to yield emergent numerical solutions for profile kinematics the emergent qualities of this shoreface translation model are exemplified in simulation experiments on changes to sand deposits on the southeastern australian coast and shelf during the post glacial marine transgression in another example the model is used to simulate lscb over engineering time scales at an idiosyncratic site both examples illustrate the over riding importance of small residual sand movements that accumulate through time to cause lscb in comparison to gross sand movements the residuals are too small to measure directly or predict on the basis of available theory exploratory inverse simulation provides a quantitative method for side stepping these limitations the shoreface translation model therefore is used as a tool to explore possible forms of coastal behaviour through an approach that incorporates available data along with theoretical considerations validation is not strictly possible for this type of inverse approach so the degree to which a simulation reproduces observed features in nature is a measure of its success

monitoring overwash using water level loggers resolves frequent inundation and run up events abstract long term months to years data on barrier island overwash are lacking but necessary for the proper parameterization of models addressing island response to rising sea levels increased storminess and anthropogenic changes here we present a method for recording overwash events that requires little maintenance and can endure storms this technique uses water level data loggers suspended in shallow wells that are anchored deeply into the ground the loggers are placed close to the highest elevation of the barrier island along a cross shore transect and record high resolution 1 cm and high frequency 2 minute water level measurements we developed a schema for differentiating between tidal fluctuations in groundwater run up overwash and inundation overwash based on the pattern of water level changes interpretations were validated using trail cameras aimed at the well and programmed to take a photograph every 5 min during daylight hours there were some data gaps in the record caused by siltation of the logger in the well repairing a corroded severed cable that was suspending the logger and limited logger data storage we constructed a year long record of overwash frequency and magnitude from october 2012 2013 that included 43 distinct overwash events at a washover fan that initially formed in august of 2011 on onslow beach nc usa the record revealed a shift in overwash intensity at the study site reflecting both changing water levels and changing barrier morphology the high number of overwash events that occurred at the washover fan 14 months after its initial formation is likely not unique to this site however overwash frequency needs to be measured along other shorelines using this method

anthropogenic controls on overwash deposition evidence and consequences accelerated sea level rise and the potential for an increase in frequency of the most intense hurricanes due to climate change threaten the vitality and habitability of barrier islands by lowering their relative elevation and altering frequency of overwash high density development may further increase island vulnerability by restricting delivery of overwash to the subaerial island we analyzed pre hurricane sandy and post hurricane sandy 2012 lidar surveys of the new jersey coast to assess human influence on barrier overwash comparing natural environments to two developed environments commercial and residential using shore perpendicular topographic profiles the volumes of overwash delivered to residential and commercial environments are reduced by 40 and 90 respectively of that delivered to natural environments we use this analysis and an exploratory barrier island evolution model to assess long term impacts of anthropogenic structures simulations suggest that natural barrier islands may persist under a range of likely future sea level rise scenarios 7 13 mm yr whereas developed barrier islands will have a long term tendency toward drowning

simulating the evolution of coastal morphology and stratigraphy with a new morphological behaviour model geombest abstract a new morphological behaviour model is used to simulate evolution of coastal morphology associated with cross shore translations of the shoreface barrier and estuary the model encapsulates qualitative principles drawn from established geological concepts that are parameterized to provide quantitative predictions of morphological change on geological time scales order 10 3 years as well as shorter time scales applicable for long term coastal management order 10 1 to 10 2 years changes in sea level and sediment volume within the shoreface barrier and estuary drive the model behaviour further parameters defining substrate erodibility sediment composition and time dependent shoreface response constrain the evolution of the shoreface towards an equilibrium profile results from numerical experiments are presented for the low gradient autochthonous setting of north carolina and the steep allochthonous setting of the washington shelf simulations in the currituck region of north carolina examined the influence of sediment supply substrate composition and substrate erodibility on barrier transgression results demonstrate that the presence of a lithified substrate reduces the rate of barrier transgression compared to scenarios where an erodible sand rich substrate exists simulations of the washington coast 20 km north of the columbia river confirmed that the model can reproduce complex stratigraphy involving regressive and transgressive phases of coastal evolution results suggest that the first major addition of sediment to the shelf occurred around 12 900 years ago and resulted from the rapid addition of sediment volume from the columbia river attributed to the missoula floods this was followed by a period where little or no sediment was added 12 400 9100 bp and a third period when most sediment was added to the shelf 9100 bp to present from the columbia river comparing results from each setting demonstrates an indirect control that substrate slope has on shoreface transgression rates shoreface transgression is shown to be sensitive to the rate of estuarine sedimentation with the sensitivity increasing as substrate slope decreases

pleistocene glacial and interglacial stratigraphy of new england long island and adjacent georges bank and gulf of maine provisional correlations of quaternary deposits of new england long island georges bank and the gulf of maine fig 1 chart 1 are based on 14c dates and amino acid racemization estimated aare ages borehole records and stratigraphic sections shallow seismic profiles and biostratigraphic analyses obtained since publication of summaries by schafer and hartshorn 1965 muller 1965 and pratt and schlee 1969 stratigraphic units record at least three and possibly four middle pleistocene and late pleistocene glaciations and intervening nonglacial episodes in the southern coastal zone fig 2 where continental glacial and marine nonglacial units are intercalated subsurface seismic units on georges bank may record two additional glaciations of middle pleistocene and early pleistocene ages most of the stratigraphic units shown in chart 1 are informal units and many of the informal stratigraphic names have not been adopted by all workers either for older units of the largely abandoned four glaciation chronology advocated by fuller 1914 woodworth and wigglesworth 1934 kay 1964a and flint 1971 or for local units of wisconsin age the stratigraphic units and limiting dates are grouped in chart 1 according to their positions in major lowland areas that controlled the configurations of ice lobes and other sectors of the ice sheet during late wisconsin deglaciation

trends in research on beaches and dunes on sandy shores 1969 2019 abstract trends in research on morphologic changes on beaches and foredunes on sandy shores are identified from the 1960s to the present research during this period evolved from early descriptive explanation and classification of profile change to instrumented field investigations to modelling of landform change at larger scales research efforts have become increasingly more collaborative with increasing use of field instrumentation data acquisition systems and remote sensing rich datasets are resulting in more comprehensive computational models human altered systems are of increasing interest but knowledge of these systems lags far behind knowledge of natural systems research is becoming more relevant to societal needs as the vulnerability of coastal populations increases the need for investigation of understudied or unexplored environments including human altered ones is ongoing many basic research issues remain but future studies would profit from the development of new models rather than validating or reconfiguring old models collaboration between geomorphologists and engineers may open up research opportunities particularly in modifying beaches and dunes built for shore protection to provide natural values in restricted space application of models to enhance knowledge of effects of sea level rise and coastal storms would be useful to managers developing resiliency plans

the role of overwash on a mid atlantic coast barrier island the importance of storms and their overwash in barrier island transgression is assessed quantitatively by determining net sediment budgets of four representative assateague island washover sites for the 1982 83 season the results show that most of the annual accretion occurred during one large storm which had a return interval of 10 to 15 years the combined effects of eight subsequent storms with return intervals of less than 2 5 years accounted for less sedimentation change due to eolian redistribution was insignificant

rollover drowning and discontinuous retreat distinct modes of barrier response to sea level rise arising from a simple morphodynamic model we construct a simple morphodynamic model to investigate the long term dynamic evolution of a coastal barrier system experiencing sea level rise using a simplified barrier geometry the model includes a dynamic shoreface profile that can be out of equilibrium and explicitly treats barrier sediment overwash as a flux with barrier behavior primarily controlled by the maximum potential overwash flux and the rate of shoreface response the modeled barrier system demonstrates four primary behaviors height drowning width drowning constant landward retreat and a periodic retreat height drowning occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep pace with sea level rise on the other hand width drowning occurs when the shoreface response rate is insufficient to maintain the barrier geometry during overwash driven landward migration during periodic barrier retreat the barrier experiences oscillating periods of rapid overwash followed by periods of relative stability as the shoreface resteepens this periodic retreat which occurs even with a constant sea level rise rate arises when overwash rates and shoreface response rates are large and of similar magnitude we explore the occurrence of these behaviors across a wide range of parameter values and find that in addition to the maximum overwash flux and the shoreface response rate barrier response can be particularly sensitive to the sea level rise rate and back barrier lagoon slope overall our findings contrast with previous research which has primarily associated complex barrier behavior with changes in external forcing such as sea level rise rate sediment supply or back barrier geometry

barrier dynamics and landward migration with holocene sea level rise barrier beaches islands and spits have become the subject of mounting interest1 2 due to human development on these land forms it is commonly thought that barrier beaches continuously migrate landward in response to sea level rise often by over wash processes maintain mass through time and that these processes are occurring at a rate commensurate with human 100 yr time frames while some barriers are naturally migrating quite rapidly3 4 other barriers decidedly are not here i present data which illustrate that many us atlantic coast barriers are not evolving over the short term in accordance with generally accepted hypotheses and argue that the presumed norm may actually be the exception

a unifying framework for shoreline migration 2 application to wave dominated coasts 1 the bruun rule widely used to predict transgression due to sea level rise on decade to century timescales based on a fixed nearshore profile neglects the influence of inland topography and substrate lithology leading to physically unreasonable predictions on longer timescales we use a new approach the shoreline exner equation to model shoreline transgression on wave dominated coasts over timescales of decades to millennia our results show that interactions between nearshore processes and inland topography neglected by bruun style models drive morphologic evolution which modulates shoreline retreat analytical solutions suggest that while short term shoreline retreat will sometimes follow the bruun rule long term transgression will always follow the slope of the inland topography moreover our results show that the slope of the inland landscape relative to the nearshore slope exerts a first order control on coastal morphology such that steep coasts tend to form cliff backed beaches while gentle coasts tend to form barrier island lagoon systems however compositional variations between the inland landscape and nearshore system can alter this pattern

complexities in barrier island response to sea level rise insights from numerical model experiments north carolina outer banks using a morphological behavior model to conduct sensitivity experiments weinvestigate the sea level rise response of a complex coastal environment to changes ina variety of factors experiments reveal that substrate composition followed in rankorder by substrate slope sea level rise rate and sediment supply rate are the mostimportant factors in determining barrier island response to sea level rise we find thatgeomorphic threshold crossing defined as a change in state e g from landward migratingto drowning that is irreversible over decadal to millennial time scales is most likely tooccur in muddy coastal systems where the combination of substrate composition depth dependent limitations on shoreface response rates and substrate erodibility mayprevent sand from being liberated rapidly enough or in sufficient quantity to maintain asubaerial barrier analyses indicate that factors affecting sediment availability such aslow substrate sand proportions and high sediment loss rates cause a barrier to migratelandward along a trajectory having a lower slope than average barrier island slope therebydefining an effective barrier island slope other factors being equal such barrierswill tend to be smaller and associated with a more deeply incised shoreface therebyrequiring less migration per sea level rise increment to liberate sufficient sand to maintainsubaerial exposure than larger less incised barriers as a result the evolution of larger lessincised barriers is more likely to be limited by shoreface erosion rates or substrateerodibility making them more prone to disintegration related to increasing sea level riserates than smaller more incised barriers thus the small deeply incised north carolinabarriers are likely to persist in the near term although their long term fate is less certainbecause of the low substrate slopes that will soon be encountered in aggregate results point to the importance of system history e g previous slopes sediment budgets etc in determining migration trajectories and therefore how a barrier island will respondto sea level rise although simple analytical calculations may predict barrier responsein simplified coastal environments e g constant slope constant sea level rise rate etc our model experiments demonstrate that morphological behavior modeling is necessary toprovide critical insights regarding changes that may occur in environments havingcomplex geometries especially when multiple parameters change simultaneously

an evolving research agenda for human coastal systems within the broad discourses of environmental change sustainability science and anthropogenic earth surface systems a focused body of work involves the coupled economic and physical dynamics of developed shorelines rapid rates of change in coastal environments from wetlands and deltas to inlets and dune systems help researchers recognize observe and investigate coupling in natural non human morphodynamics and biomorphodynamics this same intrinsic quality of fast paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities in many coastal communities beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies including beach replenishment groynes revetments and seawalls as cycles of erosion and mitigation iterate coastline change and economically driven interventions become mutually linked emergent dynamics of two way economic physical coupling is a recent research discovery having established a strong theoretical basis research into coupled human coastal systems has passed its early proof of concept phase this paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human coastal systems 1 codifying salient individual and social behaviors of decision making in ways that capture societal actions across a range of scales thus engaging economics social science and policy disciplines 2 quantifying anthropogenic effects on alongshore and cross shore sediment pathways and long term landscape evolution in coastal zones through time including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices e g construction of buildings and artificial dunes bulldozer removal of overwash after major storms and 3 reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management future research into human coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common pool resources from computational efficiency and new techniques in numerical modeling and from the growing catalog of high resolution geospatial data for natural and developed coastlines around the world

bioturbation into a recently emplaced deep sea turbidite surface as revealed by210pbexcess 230thexcess and planktonic foraminifera distributions abstract this study concerns the surface of a single distal turbidite emplaced on the madeira abyssal plain a few hundred years ago the vertical and horizontal homogeneity of the unit and the low pelagic sediment accumulation rate enable a ready identification of the post emplacement signals of near surface bioturbation data have been gathered to define 210 pb excess 230 th excess and pelagic foraminifera profiles with depth these are used as constant input flux tracers and treated by models conventionally used to determine bioturbation parameters the mixed layer depths 7 11 cm bioturbation coefficients 0 08 0 18 cm 2 y 1 and inventory data 10 23 dpm cm 2 derived from the 210 pb excess data in five out of six cores are similar to those previously observed elsewhere with the same model in the deep sea under steady state sediment accumulation conditions although the mixed layer depths are similar for all three tracers the 210 pb excess bioturbation intensities are larger by a factor of 3 than those estimated from 230 th excess profiles and about an order of magnitude larger than those from the foraminifera profiles it is suggested that the conventional 210 pb excess model and those for other short lived tracers probably over estimate the intensity of biomixing of foraminifera for palaeontological and related geochemical purposes

sedimentary evidence of intense hurricane strikes from new jersey nine vibracores from the backbarrier marsh at whale beach new jersey reveal three large scale overwash deposits associated with historic and prehistoric storms the uppermost and smallest overwash fan was deposited in the ash wednesday northeaster of march 5 8 1962 a second more substantial overwash fan between 100 and 35 cm depth dates to the late eighteenth or early nineteenth century this fan was most likely deposited during the 1821 hurricane the only intense hurricane to make landfall in new jersey in the past 350 yr a third larger overwash fan between 200 and 300 cm depth was deposited between a d 1278 and 1438 and is likely the result of a prehistoric intense hurricane strike the combination of historical and stratigraphic evidence indicates that two intense hurricanes winds 50 ms 21 have likely made landfall on the southern new jersey coast in the past 700 yr resulting in an annual landfall probability of 0 3

reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern florida from lake sediment records abstract sediment cores from western lake provide a 7000 yr record of coastal environmental changes and catastrophic hurricane landfalls along the gulf coast of the florida panhandle using hurricane opal as a modern analog we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity few catastrophic hurricanes struck the western lake area during two quiescent periods 3400 5000 and 0 1000 14 c yr b p the landfall probabilities increased dramatically to ca 0 5 per yr during an hyperactive period from 1000 3400 14 c yr b p especially in the first millennium a d the millennial scale variability in catastrophic hurricane landfalls along the gulf coast is probably controlled by shifts in the position of the jet stream and the bermuda high

geology of microtidal coastal lagoons rhode island abstract the coastal lagoons of rhode island are contained behind narrow 200 300 m wide barrier spits in a microtidal wave dominated environment the major depositional environments within the lagoons are 1 flood tidal deltas 2 subtidal storm surge platforms and 3 back lagoon low energy basins the pathways of sediment influx into the coastal lagoons are 1 tidal inlets breachways 2 temporary storm surge channels cut through the barrier spits and 3 overwash transport of sand that crosses the spits and builds into the lagoons sediment transport in the lagoons is caused by currents generated by windshear within the lagoon basins and by storm surge generated flow both of which may be additive to tidal currents lagoonal sedimentation was initiated in ninigret pond approximately 4100 b p based on radiocarbon dating as low energy basins developed on an uneven pleistocene glaciofluvial surface tidal delta sedimentation began approximately 2500 b p the continued existence of the lagoons is dependent on rate of infill and barrier retreat versus rate of sea level rise based on long term sea level rise past 2500 years calculations indicate that the lagoons will decrease in size as sediment influx exceeds the rate of inundation

overwash and aeolian processes on a u s northeast coast barrier abstract a field investigation of overwash aeolian processes and vegetative response was undertaken to obtain the first quantitative data of this kind for the new england area the new england blizzard of 1978 february 6 7 resulted in massive overwashing of nauset spit cape cod massachusetts volumetric determinations showed that as much as 400 m3 of overwash sand per meter of dune breach was transported across the barrier during this event with deposition thicknesses of 1 65 m above the living salt marsh although considerable amounts of sand were deposited by overwash much of this sediment was redistributed through aeolian processes during interstorm periods approximately half the sediment deposited by the 1978 northeaster was blown back to the beach by offshore winds and an equal amount accumulated in the peripheral dunes at distinct fan features large barren washover flats can remain unvegetated for long periods of time where the substrate is continually affected by overwash and aeolian transport these areas eventually become the loci of new major barrier dunes through the revegetation process initiated by drift line deposits

inundation of a barrier island chandeleur islands louisiana usa during a hurricane observed water level gradients and modeled seaward sand transport large geomorphic changes to barrier islands may occur during inundation when storm surge exceeds island elevation inundation occurs episodically and under energetic conditions that make quantitative observations difficult we measured water levels on both sides of a barrier island in the northern chandeleur islands during inundation by hurricane isaac wind patterns caused the water levels to slope from the bay side to the ocean side for much of the storm modeled geomorphic changes during the storm were very sensitive to the cross island slopes imposed by water level boundary conditions simulations with equal or landward sloping water levels produced the characteristic barrier island storm response of overwash deposits or displaced berms with smoother final topography simulations using the observed seaward sloping water levels produced cross barrier channels and deposits of sand on the ocean side consistent with poststorm observations this sensitivity indicates that accurate water level boundary conditions must be applied on both sides of a barrier to correctly represent the geomorphic response to inundation events more broadly the consequence of seaward transport is that it alters the relationship between storm intensity and volume of landward transport sand transported to the ocean side may move downdrift or aid poststorm recovery by moving onto the beach face or closing recent breaches but it does not contribute to island transgression or appear as an overwash deposit in the back barrier stratigraphic record the high vulnerability of the chandeleur islands allowed us to observe processes that are infrequent but may be important at other barrier islands

response of wave dominated and mixed energy barriers to storms wave dominated and mixed energy barriers are extremely dynamic landforms responding to processes operating over a spectrum of time scales ranging from daily to monthly fluctuations related to storm and post storm conditions to century to millennium scale evolution driven by relative sea level change two types of storms are of particular relevance warm core tropical and cold core extratropical cyclones both are responsible for generating very large waves highly energetic surf zone dynamics and sediment transport elevated inshore water levels and extensive morphological responses all cyclones are affected by climate change which governs their frequency intensity and tracks barrier storm response is primarily governed by maximum storm runup and barrier morphology as conceptualised in abby sallenger s storm impact scale model sallenger 2000 this model defines four storm impact regimes and includes erosive as well as accretionary responses on the erosion side the swash regime drives bar and berm flattening the collision regime is marked by dune scarping and beach lowe the overwash regime leads to dune scouring and channel incision and the inundation regime may result in barrier destruction on the deposition side storm berms and beach ridges may form and accrete in the swash and collision regimes localised vertical beach and barrier accretion are associated with the collision and overwash regimes and washover deposition takes place in the overwash and inundation regimes site specific factors play a key role in moderating the morphological response and include storm characteristics type duration and track longshore sediment supply upwelling downwelling currents coastal setting and inner shelf topography the response of a barrier to a tropical or extratropical cyclone can however not be considered in isolation and has to be appreciated in a longer temporal context involving morphological preconditioning due to antecedent wave and water level conditions additionally a simple process response approach of the cause and effect type is inappropriate and a more complex conceptual framework involving thresholds feedbacks resilience and vulnerability will need to be adopted a useful way to visualise and conceptualise more complex storm behaviours and the longer term vulnerability of barriers is the resilience trajectory which maps out the changes in barrier geometry elevation and width over various time scales from weeks to years or even longer and under varying forcing conditions including changes in storminess and sea level rise an increased understanding of barrier response to storms and sequences of storms is required to better quantify long term barrier response to climate change high resolution and comprehensive decadal records of barrier response to storms are a prerequisite to achieve this ambition linking site specific coastal settings hydrodynamic drivers and morphological responses and allowing the recognition of recovery and impact dominated phases the enhanced insights in barrier response to extreme events must then be incorporated into improved coastal response models to help predict the impacts of future climate change on wave dominated and mixed energy barriers around the world 2013 elsevier b v

spatial distribution of hydrocarbon reservoirs in the west korea bay basin in the northern part of the yellow sea estimated by 3 d gravity forward modelling

700 yr sedimentary record of intense hurricane landfalls in southern new england five intense category 3 or greater hurricanes occurring in 1635 1638 1815 1869 and 1938 have made landfall on the new england coast since european settlement historical records indicate that four of these hurricanes 1635 1638 1815 and 1938 and hurricane carol a strong category 2 storm in 1954 produced significant storm surges 3 m in southern rhode island storm surges of this magnitude can overtop barrier islands removing sediments from the beach and nearshore environment and depositing overwash fans across back barrier marshes lakes and lagoons in a regime of rising sea level accumulation of marsh lake or lagoon sediments on top of overwash deposits will preserve a record of overwash deposition we examined the record of overwash deposition at succotash salt marsh in east matunuck rhode island and tested the correlation with historical records of intense storms aerial photographs taken after hurricanes in 1954 and 1938 show overwash fans deposited at the site analysis of 14 sediment cores from the back barrier marsh confirmed the presence of these fans and revealed that 4 additional large scale overwash fans were deposited within the marsh sediments the four overwash fans deposited since the early seventeenth century at succotash marsh matches the historical record of significant hurricane induced storm surge these fans were most likely deposited by hurricanes in 1954 1938 1815 and either 1638 or 1635 radiocarbon dating of two prehistoric overwash fans indicated that these were deposited between a d 1295 1407 and 1404 1446 and probably represent intense hurricane strikes in the past 700 yr at least 7 intense hurricanes struck the southern rhode island coast and produced a storm surge that overtopped the barrier at succotash marsh

quantifying overwash flux in barrier systems an example from martha s vineyard massachusetts usa abstract coastal barriers are particularly susceptible to the effects of accelerated sea level rise and intense storms over centennial scales barriers are maintained via overtopping during storms which causes deposition of washover fans on their landward sides understanding barrier evolution under modern conditions can help evaluate the likelihood of future barrier stability this study examines three washover fans on the undeveloped south shore of martha s vineyard using a suite of vibracores ground penetrating radar high resolution dgps and lidar data from these data the volumes of the deposits were determined and range from 2 1 to 2 4 10 4 m 3 two of these overwash events occurred during hurricane bob in 1991 the water levels produced by this storm have a calculated return interval of 28 years implying an onshore sediment flux of 2 4 3 4 m 3 m yr the third washover was deposited by a nor easter in january 1997 which has a water level return interval of 6 years suggesting a flux of 8 5 m 3 m yr these onshore fluxes are smaller than the erosional flux of sediment resulting from shoreline retreat suggesting that the barrier is not in long term equilibrium a result supported by the thinning of the barrier in recent years

numerical modeling and field evidence of coastal overwash in southern new england from hurricane bob and implications for paleotempestology 1 in this paper we examine the use of coastal overwash modeling in conjunction with geological proxy techniques to provide a more comprehensive tool for paleotempestology southern new england which lies in the path of north tracking hurricanes has been a prime location for paleotempestological studies hurricane bob of 1991 is the most recent landfall in this region and has the most comprehensive data for model assessment and validation using the hurricane track central pressure and radius of maximum wind as input a collection of four interoperable model components simulates the meteorological conditions astronomical tides and storm surge ocean and coastal waves and the surf zone processes and runup onto dry land the computed surface pressure winds waves and water levels give very good agreement with data from weather stations moored buoys and tide gauges near the track and in the zone of maximum wind the validated wave conditions and storm water levels define the boundary conditions for coastal overwash modeling and the results show strong correlation with aerial photographs and sedimentary records at five sites near the landfall the results provide modern analogs for the interpretation of early hurricane landfalls in southern new england that lack an instrumental record reconstruction of paleohurricanes will require geological proxy data at multiple locations for the multivariate inverse analysis with uncertain paleotopography and storm characteristics

reply to the discussion by dillenburg et al on evidence for a transgressive barrier within a regressive strandplain system implications for complex response to environmental change

a simple model for the spatially variable coastal response to hurricanes abstract the vulnerability of a beach to extreme coastal change during a hurricane can be estimated by comparing the relative elevations of storm induced water levels to those of the dune or berm a simple model that defines the coastal response based on these elevations was used to hindcast the potential impact regime along a 50 km stretch of the north carolina coast to the landfalls of hurricane bonnie on august 27 1998 and hurricane floyd on september 16 1999 maximum total water levels at the shoreline were calculated as the sum of modeled storm surge astronomical tide and wave runup estimated from offshore wave conditions and the local beach slope using an empirical parameterization storm surge and wave runup each accounted for 48 of the signal the remaining 4 is attributed to astronomical tides indicating that wave driven process are a significant contributor to hurricane induced water levels expected water levels and lidar derived measures of pre storm dune and berm elevation were used to predict the spatially varying storm impact regime swash collision or overwash predictions were compared to the observed response quantified using a lidar topography survey collected following hurricane landfall the storm averaged mean accuracy of the model in predicting the observed impact regime was 55 4 a significant improvement over the 33 3 accuracy associated with random chance model sensitivity varied between regimes and was highest within the overwash regime where the accuracies were 84 2 and 89 7 for hurricanes bonnie and floyd respectively the model not only allows for prediction of the general coastal response to storms but also provides a framework for examining the longshore variable magnitudes of observed coastal change for hurricane bonnie shoreline and beach volume changes within locations that experienced overwash or dune erosion were two times greater than locations where wave runup was confined to the foreshore swash regime during hurricane floyd this pattern became more pronounced as magnitudes of change were four times greater within the overwash regime than in the swash regime comparisons of pre storm topography to a calm weather survey collected one year after hurricane floyd s landfall show long term beach volume loss at overwash locations here the volume of sand eroded from the beach was balanced by the volume of overwash deposits indicating that the majority of the sand removed from the beach was transported landward across the island rather than being transported offshore in overwash locations sand was removed from the nearshore system and unavailable for later beach recovery resulting in a more permanent response than observed within the other regimes these results support the predictive capabilities of the storm scaling model and illustrate that the impact regimes provide a framework for explaining the longshore variable coastal response to hurricanes

sedimentary records of intense storms in holocene barrier sequences maine usa coastal morphological geophysical ground penetrating radar gpr and sedimentological data document extreme storm events along the sandy barriers of maine s south central hunnewell and flat point barriers and southwestern saco bay barriers coastal compartments the hunnewell barrier contains four equally spaced buried storm scarps behind the exposed scarp of the blizzard of 1978 a 100 year storm that eroded more than 100 m of shoreline causing extensive property loss these scarps dip 3 5j steeper than the normal beachface slope and consist of sands with more than 50 heavy minerals the heavy minerals produce distinct subsurface reflections that facilitate the location of buried supratidal parts of storm scarps and the mapping of ancient poststorm shoreline positions the imaged scarps likely formed within the past 1 5 2 0 ka bp the flat point barrier consists of a prograded sequence overlain by a laterally extensive seaward thinning layer of freshwater peat and capped by aeolian sands this stratigraphy suggests that the bog varied in size through time contracting during overwash events and aeolian deposition and expanding across washover sheets during extended periods of barrier stability the main overwash event accompanied by barrier planation and wetland expansion may be linked to the first historical storm in new england the great colonial hurricane of 1635 evidence of near modern and mid holocene storm events along saco bay includes washover units and marsh ridges washovers interfinger with saltmarsh peat that ranges in age from 4 5 ka bp to modern the presence of isolated sandy ridges behind existing and former tidal inlets reflects overtopping of marshes and high intertidal mudflats during major storms radiocarbon ages indicate that this process took place at different locations along the saco bay barrier complex from 3 to 1 ka bp d 2004 elsevier b v all rights reserved

proxy records of holocene storm events in coastal barrier systems storm wave induced markers abstract extreme storm events in the coastal zone are one of the main forcing agents of short term coastal system behavior as such storms represent a major threat to human activities concentrated along the coasts worldwide in order to better understand the frequency of extreme events like storms climate science must rely on longer time records than the century scale records of instrumental weather data proxy records of storm wave or storm wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia this review provides a detailed state of the art compilation of the proxies available from coastal barrier systems to reconstruct holocene storm chronologies paleotempestology the present paper aims i to describe the erosional and depositional processes caused by storm wave action in barrier and back barrier systems i e beach ridges storm scarps and washover deposits ii to understand how storm records can be extracted from barrier and back barrier sedimentary bodies using stratigraphical sedimentological micro paleontological and geochemical proxies and iii to show how to obtain chronological control on past storm events recorded in the sedimentary successions the challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm chronologies using these various proxies are discussed and future research prospects are outlined