dune recovery after storm erosion on a high energy beach vougot beach brittany france abstract on 10th march 2008 the high energy storm johanna hit the french atlantic coast generating severe dune erosion on vougot beach brittany france in this paper the recovery of the dune of vougot beach is analysed through a survey of morphological changes and hydrodynamic conditions data collection focused on the period immediately following storm johanna until july 2010 i e over two and a half years results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre and post storm dune toe and reducing impacts of the storm surge dune recovery started in the month following the storm event and is still ongoing it is characterised by the construction of secondary embryo dunes which recovered at an average rate of 4 4 5 cm per month although average monthly volume changes varied from 1 to 2 m 3 m 1 these embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune these dune construction processes were facilitated by growth of vegetation on low profile embryo dunes promoting backshore accretion after more than two years of survey the sediment budget of the beach dune system showed that more than 10 000 m 3 has been lost by the upper tidal beach we suggest that seaward return currents generated during the storm of 10th march 2008 are responsible for offshore sediment transport reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross shore sediment redistribution inducing net erosion in the tidal zone

glacial interglacial variablity in the benguela upwelling system spatial distribution and budgets of organic carbon accumulation 1 modern sedimentary total organic carbon toc content as a proxy for surface water export production was mapped on the shelf and on the upper continental slope of the benguela upwelling system using 137 core tops shelf maxima in toc can be correlated with maxima in surface water productivity on the slope high toc contents are observed offshore from sites of strong modern upwelling estimates of modern toc mass accumulation rates mar show that approximately 85 of the total is accumulating on the shelf toc mar were calculated mapped and budgeted for the holocene and for the last glacial maximum lgm using 19 sediment cores from the continental slope during the lgm centers of deposition and production have migrated offshore with respect to their holocene positions toc accumulation on the continental slope was approximately 84 higher during the lgm than during the holocene possibly reflecting enhanced productivity the toc distribution patterns and sediment echo sounding data suggest that undercurrents strongly influence the sedimentation off namibia winnowing and focusing result in great lateral heterogeneity of sedimentation rates and sediment properties individual cores therefore do not necessarily reflect general changes in export production these results highlight the need for detailed regional studies based on a large number of sediment cores for highly heterogeneous high productivity areas in order to derive general statements on total fluxes

role of geological inheritance in australian beach morphodynamics the australian coast contains 10 685 beaches which occupy 49 of the 30 000 km coast and average 1 37 km in length their relatively short length is largely due to the presence of bedrock calcarenite and laterite which form boundaries to many of the beaches as well as occurring as rocks reefs and islands along and off the beaches this geological inheritance plays a major role in australian beach systems determining their length and through wave refraction and attenuation influencing beach location shape type morphodynamics and circulation which in turn influence sediment transport and the backing dune and barrier systems this paper uses a database covering every australian beach to review the role of headlands rocks and reefs on australian beaches major effects are the short average beach length reduction in breaker height resulting in lower energy beach types wave refraction resulting in increased beach curvature the presence of topographic rips on moderate and higher energy beaches and megarips during high wave conditions and the interruption of and or trapping of longshore sand transport leading to beach rotation

predicting coastal hazards for sandy coasts with a bayesian network abstract low frequency high impact storm events can have large impacts on sandy coasts the physical processes governing these impacts are complex because of the feedback between the hydrodynamics of surges and waves sediment transport and morphological change predicting these coastal changes using a numerical model requires a large amount of computational time which in the case of an operational prediction for the purpose of early warning is not available for this reason morphodynamic predictions are not commonly included in early warning systems ewss however omitting these physical processes in an ews may lead to potential under or over estimation of the impact of a storm event to solve this problem a method has been developed to construct a probabilistic bayesian network bn this bn connects three elements offshore hydraulic boundary conditions characteristics of the coastal zone and onshore hazards such as erosion and overwash depths and velocities the hydraulic boundary conditions are derived at a water depth of approximately 20 m from a statistical analysis of observed data using copulas and site characteristics are obtained from measurements this bn is trained using output data from many pre computed process based model simulations which connect the three elements once trained the response of the bn is instantaneous and can be used as a surrogate for a process based model in an ews in which the bn can be updated with an observation of the hydraulic boundary conditions to give a prediction for onshore hazards the method was applied to praia de faro portugal a low lying urbanised barrier island which is subject to frequent flooding using a copula based statistical analysis which preserves the natural variability of the observations a synthetic dataset containing 100 events was created based on 20 years of observations but extended to return periods of significant wave height of up to 50 years these events were transformed from offshore to onshore using a 2d xbeach roelvink et al 2009 model three bn configurations were constructed of which the best performing one was able to predict onshore hazards as computed by the model with an accuracy ranging from 81 to 88 and predict events with no significant onshore hazards with an accuracy ranging from 90 to 95 two examples are presented on the use of a bn in operational predictions or as an analysis tool the added value of this method is that it can be applied to many coastal sites 1 limited observations of offshore hydrodynamic parameters can be extended using the copula method which retains the original observations natural variability 2 the transformation from offshore observations to onshore hazards can be computed with any preferred coastal model and 3 a bn can be adjusted to fit any relevant connections between offshore hydraulic boundary conditions and onshore hazards furthermore a bn can be continuously updated with new information and expanded to include different morphological conditions or risk reduction measures as such it is a promising extension of existing ewss and as a planning tool for coastal managers

climate forcing of regionally coherent extreme storm impact and recovery on embayed beaches abstract the effective management of sedimentary coastlines demands a good understanding of the seasonal and inter annual cycles in beach volumes as well as the potential impact of extreme events this paper uses a 10 year time series 2007 2017 of supra and intertidal beach volume from exposed and cross shore transport dominated sites to examine the extent to which beach behaviour is coherent over a relatively large region 100 km stretch of coast and predictably coupled to incident wave forcing over the study period 10 beaches exposed to similar wave tide conditions but having different sediment characteristics beach lengths and degrees of embaymentisation showed coherent and synchronous variations in sediment volumes albeit at different magnitudes the sequence of extreme storms of the 2013 14 winter which represents the most erosive event over at least a decade along most of the atlantic coast of europe is included in the data set and three years after this winter beach recovery is still on going for some of the 10 beaches post storm beach recovery was shown to be mainly controlled by post storm winter wave conditions while summer conditions consistently contributed to modest beach recovery skilful hindcasts of regional changes in beach volume were obtained using an equilibrium type shoreline model shorefor davidson et al 2013 demonstrating that beach changes are coherently linked to changes in the offshore wave climate and are sensitive to the antecedent conditions the shorefor model can successfully be applied to exposed coastal areas dominated by cross shore sediment transport and can also be used as a relatively simple and regional tool for the future management of beaches where coherence in coastal response is observed furthermore a good correlation was found between the beach volume changes and the new climate index wepa west europe pressure anomaly castelle et al 2017b which offers new perspectives for the role and the use of climatic variations proxies to forecast coastline evolution

the extreme 2013 2014 winter storms hydrodynamic forcing and coastal response along the southwest coast of england the southwest coast of england was subjected to an unusually energetic sequence of atlantic storms during the 2013 2014 winter with the 8 week period from mid december to mid february representing the most energetic period since at least 1953 a regional analysis of the hydrodynamic forcing and morphological response of these storms along the sw coast of england highlighted the importance of both storm and site specific conditions the key factor that controls the atlantic storm wave conditions along the south coast of southwest england is the storm track energetic inshore wave conditions along this coast require a relatively southward storm track which enables offshore waves to propagate up the english channel relatively unimpeded the timing of the storm in relation to the tidal stage is also important and coastal impacts along the macro tidal southwest coast of england are maximised when the peak storm waves coincide with spring high tide the role of storm surge is limited and rarely exceeds 1 m the geomorphic storm response along the southwest coast of england displayed considerable spatial variability this is mainly attributed to the embayed nature of the coastline and the associated variability in coastal orientation on west facing beaches typical of the north coast the westerly atlantic storm waves approached the coastline shore parallel and the prevailing storm response was offshore sediment transport many of these north coast beaches experienced extensive beach and dune erosion and some of the beaches were completely stripped of sediment exposing a rocky shore platform on the south coast the westerly atlantic storm waves refract and diffract to become southerly inshore storm waves and for the southeast facing beaches this results in large incident wave angles and strong eastward littoral drift many south coast beaches exhibited rotation with the western part of the beaches eroding and the eastern part accreting 2015 the authors earth surface processes and landforms published by john wiley sons ltd

a field based classification scheme for gravel beaches a tripartite classification of gravel beaches based upon morphodynamic properties is proposed and demonstrated for 42 new zealand beaches the main advantage of this scheme is that it is based on simple visual classification that can be applied globally in the field and is underpinned by morphodynamic differences between the beach types the three types identified from the results are 1 pure gravel beach 2 mixed sand and gravel beach 3 composite gravel beach pure gravel beaches have steep slopes tan 0 08 0 24 and gravels extending from the storm berm to below mean low water spring tide level mixed sand and gravel beaches have moderate slopes tan 0 04 0 13 with sand and gravel entirely mixed both cross shore and at depth composite gravel beaches have a steep gravel berm fronted by a low angle intertidal terrace with overall beach slopes of tan 0 05 0 14 on composite beaches there is distinct hydrodynamic cross shore sorting of the sand and gravel component these broad types are tested using discriminant analysis and the three classes are shown to be highly significant f 16 24 df 8 p 0 00005 the key discriminating variables are iribarren number beach width average grain size and storm berm height

a new climate index controlling winter wave activity along the atlantic coast of europe the west europe pressure anomaly a pioneering and replicable method based on a 66 year numerical weather and wave hindcast is developed to optimize a climate index based on the sea level pressure slp that best explains winter wave height variability along the coast of western europe from portugal to uk 36 52 n the resulting so called western europe pressure anomaly wepa is based on the sea level pressure gradient between the stations valentia ireland and santa cruz de tenerife canary islands the wepa positive phase reflects an intensified and southward shifted slp difference between the icelandic low and the azores high driving severe storms that funnel high energy waves toward western europe southward of 52 n wepa outscores by 25 150 the other leading atmospheric modes in explaining winter averaged significant wave height and even by a largest amount the winter averaged extreme wave heights wepa is also the only index capturing the 2013 2014 extreme winter that caused widespread coastal erosion and flooding in western europe

coastal embayment rotation response to extreme events and climate control using full embayment surveys abstract barrier beach change in directionally bi modal wave climates presents an increasing challenge for coastal communities both in the short term storm events and decadal to centurial time scales long term evolution predicting and planning for subsequent variations requires understanding of the morphological response to changes in wave energy along with the atmospheric forces driving the wave climate in this paper multi method topo bathymetric surveys are used to assess the morphological change of a semi sheltered gravel barrier start bay devon uk total sediment budgets supra to sub tidal with spatially varying uncertainty levels indicate the embayment is closed one third of total sediment flux occurred in the sub tidal establishing the importance of sub tidal transport for this type of coastline our results demonstrate that under the predominance of a given wave direction rotation first occurs within sub embayments additional sustained and extreme energy levels are then required for full embayment rotation to occur with significant headland bypassing in this instance 6 105 m3 of gravel was transported alongshore during a 3 year sustained period of dominant southerly waves including a 1 50 year storm season full embayment rotation whilst 3 105 m3 was returned during a 2 year period of dominant easterly waves sub embayment rotation only a novel parameter is introduced that predicts beach rotation based on the directional wave balance in turn winter wave direction is shown to correlate with a combination of two climate indices given adequate predictions of relevant climate indices these findings constitute the basis of a generalisable method to predict and plan for future beach rotation on similar beaches globally

exploring the sensitivities of crenulate bay shorelines to wave climates using a new vector based one line model we use a new exploratory model that simulates the evolution of sandy coastlines over decadal to centennial timescales to examine the behavior of crenulate shaped bays forced by differing directional wave climates the model represents the coastline as a vector in a cartesian reference frame and the shoreface evolves relative to its local orientation allowing simulation of coasts with high planform curvature shoreline change is driven by gradients in alongshore transport following newly developed algorithms that facilitate dealing with high planform curvature coastlines we simulated the evolution of bays from a straight coast between two fixed headlands with no external sediment inputs to an equilibrium condition zero net alongshore sediment flux under an ensemble of directional wave climate conditions we find that planform bay relief increases with obliquity of the mean wave direction and decreases with the spread of wave directions varying bay size over 2 orders of magnitude 0 1 16 km the model predicts bay shape to be independent of bay size the time taken for modeled bays to attain equilibrium was found to scale with the square of the distance between headlands so that all else being equal small bays are likely to respond to and recover from perturbations more rapidly over just a few years compared to large bays hundreds of years empirical expressions predicting bay shape may be misleading if used to predict their behavior over planning timescales

the impact of waves and tides on residual sand transport on a sediment poor energetic and macrotidal continental shelf 2019 the authors the energetic macrotidal shelf off south west england was used to investigate the influence of different tide and wave conditions and their interactions on regional sand transport patterns using a coupled hydrodynamic wave and sediment transport model residual currents and sediment transport patterns are important for the transport and distribution of littoral and shelf sea sediments morphological evolution of the coastal and inner continental shelf zones and coastal planning waves heavily influence sand transport across this macrotidal environment median 50 exceedance waves enhance transport in the tidal direction extreme 1 exceedance waves can reverse the dominant transport path shift the dominant transport phase from flood to ebb and activate sand transport below 120 m depth wave tide interactions encompassing radiation stresses stoke s drift enhanced bottom friction and bed shear stress refraction current induced doppler shift and wave blocking significantly and nonlinearly enhance sand transport determined by differencing transport between coupled wave only and tide only simulations a new continental shelf classification scheme is presented based on sand transport magnitude due to wave forcing tide forcing and nonlinear wave tide interactions classification changes between different wave tide conditions have implications for sand transport direction and distribution across the shelf nonlinear interactions dominate sand transport during extreme waves at springs across most of this macrotidal shelf at neaps nonlinear interactions drive a significant proportion of sand transport under median and extreme waves despite negligible tide induced transport this emphasizes the critical need to consider wave tide interactions when considering sand transport in energetic environments globally where previously tides alone or uncoupled waves have been considered

video based nearshore bathymetry estimation in macro tidal environments abstract video based depth inversion through the linear dispersion relation for free surface waves using the cross spectral correlation analysis cbathy holman et al 2013 is applied for the first time in a highly energetic macro tidal environment in the south west of england at porthtowan this application of cbathy reveals two main issues 1 inaccurate depth estimations on inter camera boundaries when multiple cameras are used and 2 significantly less accurate depth estimates over the whole domain during spring tide compared to neap tide inaccuracies of around 35 of the local depths are found during spring tide these two issues are not only important in macro tidal environments the camera boundary issue has been reported in numerous video camera sites and the deviation in accuracy during tidal levels is a function of the tidal range in combination of the vertical camera position to overcome the two issues a camera boundary solution and a floating pixel solution meaning moving pixels in a horizontal plane as function of the tidal elevation are proposed here with the modifications cbathy is capable of estimating depths in the sub tidal zone with an accuracy in the order of 10 of the local depth irrespective to the local tidal regime however for the very upper part of the beach face less accurate results are found due to the reduced validity of the linear dispersion relation in that region due to the non linear behaviour of breaking waves and wave current interactions the improvements persist across all bathymetry survey campaigns at porthtowan and when compared to other well known argus video system sites the importance of the floating pixels is apparent

multi annual embayment sediment dynamics involving headland bypassing and sediment exchange across the depth of closure abstract predicting the future behavior of beach and nearshore systems requires an accurate delineation and understanding of coastal cell boundaries sediment transport pathways and sediment sources and sinks unfortunately there is a paucity of field datasets on beach and nearshore morphological change that extend fully from the top of the dunes to beyond the depth of closure to enable quantification of the sediment budget here for the first time we employ a total sediment budget approach examining a sandy and embayed beach located in the north coast of sw england to investigate inter and multi annual embayment scale sediment dynamics over a 10 year period that includes extreme storm erosion and post storm recovery we demonstrate that despite the deeply embayed nature of the beach the shoreline orientation roughly parallel to the dominant wave direction and the overwhelmingly cross shore forcing of the inter tidal beach volume the system is neither closed nor balanced the very significant net changes in the recorded sediment volume from dune top to depth of closure 14 5 m odn representing a loss of c 100 m3 m 1 during the extreme storm period and a gain of c 200 m3 m 1 during the recovery period indicate that significant sediment transport occurs seaward of the base of the terminating headlands and beyond the morphological depth of closure the results further indicate that the inter tidal region is partly uncoupled from the sub tidal region with the former region dominated by cross shore sediment fluxes whereas the subtidal region is also significantly affected by longshore sediment fluxes a conceptual model is presented that balances the observed volume changes with inferred fluxes forced by variations in total and alongshore wave power this study contradicts the general assumption that when sediment exits the inter tidal it rests undisturbed in the sub tidal waiting for a period of low moderate energy to bring it onshore the large sediment volumetric variations across the lower shoreface depth of 5 20 m which are of the same order of magnitude as but uncorrelated with those occurring in the inter tidal region are suggestive of an energetic longshore transport system across this deeper region it is possible that this transport system extends along the whole north coast of sw england and this finding may lead to a shift in understanding of sediment budgets along exposed and macrotidal embayments globally

observation and prediction of three dimensional morphology at a high energy macrotidal beach abstract three dimensional beach features such as crescentic sandbars and rip channels influence beach response to and recovery from storm waves as well as significantly affecting the safety and amenity provided by the surf zone for beach water users in this contribution temporal variations in subtidal and intertidal beach three dimensionality are observed at a high energy macrotidal beach and a simple equilibrium model is developed to predict the changes over multi year timescales a dataset of 5 5 years of quasi weekly bar measurements and quasi monthly intertidal surveys from perranporth beach cornwall uk were used to quantify seasonal to inter annual changes in three dimensionality the three dimensionality of the outer bar displayed significant annual periodicity with annual minima and maxima occurring in winter and spring respectively the lower intertidal beach displayed a similar periodicity but developed three dimensionality 1 4 months before the outer bar the model predicts increases or decreases in the scale of three dimensional features by examining the disparity between instantaneous wave conditions and a temporally varying equilibrium wave condition a tidally modulated wave power term determines the rate of morphological change negative feedback was found to be an important process governing the changes in three dimensionality while free morphological behaviour may drive three dimensional growth negative feedback exerts stability in the system making it inherently predictable using a temporally varying equilibrium value the model explained 42 and 61 of the overall variability in outer bar and lower beach three dimensionality respectively it skilfully predicted changes outside the training data range during the most energetic 8 week period of waves measured in the last 65 years off sw england in winter 2013 14 the model outperformed a simple baseline model a linear fit as well as a comparable linearized feedback model from the literature providing the first long term multi year predictions of seasonal to inter annual beach three dimensionality for a macrotidal beach

extreme erosion on high energy embayed beaches influence of megarips and storm grouping abstract megarips have long been recognised as an important yet poorly documented mechanism of beach erosion on high energy embayed beaches the persistence and cumulative effect of megarips during storm groups are described from three embayed beaches arrifana mt clerigo and amoreira exposed to high energy wave conditions in the mesotidal bedrock dominated southwestern coast of portugal morphological changes determined by topographic monitoring and supplemented by interpretation of digital imagery over two years revealed the development of storm induced megarips which exerted a major influence on beach erosion differences in megarip influence within and between beaches are related to embayment geometry and orientation which significantly influence the nearshore wave field rip location is topographically controlled being determined by alongshore variations in breaking wave height and obliquity along with interaction of wave driven circulation patterns and embayment nearshore topography moderate beach sand loss during individual storms was linked to the development of megarips with associated rip neck and feeder channels extreme erosion however occurred when megarips and feeder channels persisted during successive storms promoting continued erosion and seaward sediment export observations show that once initiated megarip channels persist for several months and continue to act as conduits for offshore sediment transport under non storm conditions the maintenance of such rip circulation systems driven by morphodynamic feedback reduces beach recovery ability until the rip neck and feeder channels are infilled

impact of a headland associated sandbank on shoreline dynamics abstract sandbanks can occur downdrift of headlands across embayments as a result of tidal currents and wave forcing and may present a potentially valuable resource of marine aggregate material large sandbanks can alter tidal flows and through refraction and dissipation increase or decrease wave exposure along the shoreline of an embayment the impact of offshore sandbanks on shoreline morphodynamics at varying timescales has not been rigorously investigated here we show for the first time that removing lowering or raising a headland associated sandbank can have a significant impact on longshore sediment transport a delft3d model of start bay and skerries bank uk validated on hydrodynamic observations was used to conduct the numerical experiments results indicate that removing or lowering the bank generally reduces dissipation and increases wave heights increasing longshore flux in the lee of the bank raising the bank generally has the opposite effect increasing dissipation and lowering flux under oblique waves the bank may protect the adjacent shoreline by refracting waves away from the coast shoreline flux for the region directly onshore of the bank acts as a continuous function of bank height r2 0 7 but correlations for distal regions are increasingly non linear or absent a raised bank would reduce transport rates to near zero across extensive sections of the bay reversing the long term net flux at points distal 5 km from bank from the bank location causing currently eroding regions to accrete our results demonstrate that moderate 5 m elevation changes to a sandbank will likely produce significant variations in wave power at the shoreline which will i modify the shoreline response for individual storms and ii substantially change shoreline morphology at decadal timescales from a broader perspective this study can be used to inform planning decisions involving naturally varying banks and or potential mining of sandbanks aiding shoreline protection strategies for locations with similar embayment sandbank configurations

identifying storm impacts on an embayed high energy coastline examples from western ireland abstract large sections of the western irish coast are characterised by a highly compartmentalised series of headland embayment cells in which sand and gravel beaches are backed by large vegetated dune systems exposure to modally high energy swell renders most of these beaches dissipative in character a mesotidal range c 3 5 4 5 m exists along much of the coast analysis of instrumental wind records from three locations permitted the identification of a variety of storm types and the construction of storm catalogues few individual storms were recorded at all three stations indicating a lack of regional consistency in storm record of the total storms recorded only a small percentage are potentially damaging onshore directed and even fewer span a high tide and thus potentially induce a measurable morphological response at the coast through a combination of historical records meteorological records field observations and wave modelling we attempt to assess the impact of storms quantifiable records of coastal morphology maps air photos and beach profiles are few in number and do not generally record responses that may be definitely attributed to specific storms numerical wave simulations and observations at a variety of sites on the west irish coast however provide insights into instantaneous and medium term decadal storm responses in such systems we argue that beaches and dunes that are attuned to modally high energy regimes require extreme storms to cause significant morphological impact the varying orientation of beaches a spatially nonuniform storm catalogue and the need for a storm to occur at high water to produce measurable change impart site specific storm susceptibility to these embayments furthermore we argue that long period wave energy attenuation across dissipative shorefaces and beaches reduces coastal response to distant storms whereas short period locally generated wind waves are more likely to cause major dune and beach erosion as they arrive at the shoreline unrefracted this apparently variable response of beach and dune systems to storm forcing at a decadal scale over a coastline length of 200 km urges caution in generalising regarding regional scale coastal responses to climatic change

role of wave forcing storms and nao in outer bar dynamics on a high energy macro tidal beach abstract outer sand bar dynamics on a high energy macro tidal beach were investigated using long term multi year field datasets of intertidal morphology and offshore bathymetry utilising a 15 year time series of argus video images five distinct outer bar types were identified mega rip longshore crescentic crescentic attached and welded the most common classification was crescentic attached with the outer bar oscillations being out of phase with the inner bar oscillations as would be expected for the shore normal wave approach at this site the outer bar had a typical amplitude of 0 5 1 m and a longshore wavelength of 600 m changes in outer bar morphology were related to measured and modelled nearshore wave data however the outer bar morphology changed over a much longer timescale monthly to annual than the daily to weekly variations in wave height and period an extended duration of energetic wave action was required to bring about an upstate bar transition to the longshore or mega rip state where the bar then remained arrested for a significant amount of time requiring several months of low wave conditions to induce a down state transition through crescentic to welded this slow morphological response is explained by extended relaxation times attributed to the large tidal range at the study site where the outer bar morphology is only active for part of the tidal cycle several hours around low tide the configuration and position of the outer bar were related the more upstate downstate bar types being associated with a more offshore onshore bar position the detrended outer bar position was significantly related to a forcing term based on wave power and disequilibrium of the dimensionless fall velocity with offshore onshore bar migration occurring when wave conditions were more less energetic that the antecedent conditions the upstate end member longshore or mega rip was attained sometime during the winter months for 14 out of the 16 years of monitoring the outer bar remained attached to the low tide shoreline over the winter 2005 2006 and 2010 2011 these two winters with incomplete upstate cycles were characterised by the lowest winter wave conditions and negative winter north atlantic oscillation nao indices suggesting that the winter nao is correlated with both beach state and nearshore bar configuration

beach response to a sequence of extreme storms abstract a sequence of daily beach surveys acquired over one month covering an area larger than 100 000 m 2 was analyzed to study morphological changes resulting from a cluster of storms the beach response was highly variable in both the cross and alongshore a cumulative storm effect was not observed despite one storm being characterized by a 10 year return period that had significant wave height h s of 8 1 m and a peak wave period t p of 17 s instead storms that can potentially cause significant erosion in terms of h s had a limited effect on the morphology because the large wave height was coupled to either neap tides normally incident short waves f 0 04 hz or low levels of infragravity 0 004 f

cold climate in the eastern australian mid to late permian may reflect cold upwelling waters a suite of ice rafted dropstones and glendonites throughout the permian succession of eastern australia indicates the cold climate associated with the late paleozoic ice age persisted longest in this part of gondwana paradoxically these cold climate indicators are preserved in transgressive and highstand facies and formed at mid to high latitudes at a time when paleofloral and sedimentological data suggest equable onshore environments during the intervening lowstands and temperate conditions at the pole these apparent inconsistencies suggest that eastern australia was anomalously cold in the context of post sakmarian gondwanan climates and the distribution of sedimentary indicators could indicate localized cooling by oceanographic processes modern upwelling of cold abyssal waters produces the specific physiochemical conditions necessary for ikaite for mation and is likely to have contributed to the development of glendonites in the eastern australian permian system such upwelling would have locally lowered surface water temperatures such that seasonal sea or river ice could form which rafted debris across the marine shelf and a cold water fauna could develop this hypothesis is supported by coupled atmosphere ocean models for the permian which suggest that wind systems may have driven upwelling along this section of the gondwanan coast colder conditions dissipated with the onset of the hunter bowen contractional event and the transformation of the basin system from an open marine shelf to a foreland basin this new hypothesis reconciles the prolonged deposition of cold climate indicators in the eastern australian permian with an apparent post sakmarian warming elsewhere in gondwana

coastal storm characterization and morphological impacts on sandy coasts the present work deals with storm classification using the storm power index and beach morphological response to storm events in the gulf of cadiz sw spain over the 1958 2001 period 377 events divided into five classes ranging from weak to extreme were characterized classes i weak and ii moderate accounted for 60 and 23 of events respectively class iii significant were 9 of the recorded events and classes iv severe and v extreme accounted for 5 and 2 respectively the probability of storm occurrence per year ranged from 93 for class i to 15 for class v in order to characterize beach response to storm events 214 beach profiles carried out with a monthly periodicity over the 1996 1998 period along the chipiona rota littoral were analysed as well as published data different beach types were observed i intermediate beaches underwent important vertical relief changes ranging from 0 3 m to 1 33 m associated with average slope changes from tan 0 06 to tan 0 03 ii the dissipative beaches were characterized by smaller and homogeneous foreshore vertical changes from c 0 36 m to 0 65 m according to the parallel retreat mechanism characterized by small slope variations from tan 0 025 to tan 0 035 and iii intermediate with rock shore platform experienced small morphological and foreshore slope variations related to both beach pivoting and parallel retreat mechanisms the most important morphological changes were due to the impact of usually weak and moderate events during october and november that produced berm erosion and upper foreshore lowering and the impact of severe significant and extreme events in december and january which produced dune escarpment overwash and or damage to coastal structures copyright 2011 john wiley sons ltd

storm response and beach rotation on a gravel beach slapton sands u k abstract continuous argus video data and fortnightly measurements of subaerial morphology were obtained over a 3 year period from a steep macrotidal gravel beach on the southwest coast of the u k concurrent wave and water level data were also collected enabling the correlation of the observed morphological changes to the hydrodynamic forcing wave conditions are generally low h s 0 5 1 m but the beach is affected by frequent storm wave activity c 15 storms per year with h s 2 4 m with waves either approaching from the south swell waves or from the east wind waves an assessment of the three dimensional morphological response of the beach to the two typical storm types was carried out by analysing the impact of 27 storms that occurred from april 2007 to april 2009 southerly storms cause accretion of the supratidal zone and erosion of the intertidal zone and a significant loss in overall beach volume easterly storms on the other hand induce supratidal erosion and intertidal accretion and a significant gain in overall beach volume during the intervening calm periods a small supratidal berm is constructed and a modest gain in overall beach volume occurs wave modelling indicated that opposing longshore energy fluxes occur for the different storm types with a northerly energy flux during southerly storms and a southerly flux during easterly storms weekly shorelines derived from the argus images revealed that the northern end of the beach widened by c 30 m and the middle beach receded by c 40 m over a relatively brief period a few months the occurrence of this beach rotation event is attributed to a higher frequency of southerly storms and or a lower frequency of easterly storms over this period thus the development and stability of the beach on annual time scales depend on the relative contributions of the two storm types and their sequencing longshore sediment transport lst rates derived from the data on beach morphological change were compared with several littoral drift formulae previously applied to gravel beaches the cerc equation with a proportionality factor k between littoral drift rate i l and longshore wave energy flux p l of k 0 054 yielded the best results

geomorphological control on boulder transport and coastal erosion before during and after an extreme extra tropical cyclone extreme wave events in coastal zones are principal drivers of geomorphic change evidence of boulder entrainment and erosional impact during storms is increasing however there is currently poor time coupling between pre and post storm measurements of coastal boulder deposits importantly there are no data reporting shore platform erosion boulder entrainment and or boulder transport during storm events rock coast dynamics during storm events are currently unexplored here we use high resolution daily field data to measure and characterize coastal boulder transport before during and after the extreme northeast atlantic extra tropical cyclone johanna in march 2008 forty eight limestone fine medium boulders n 46 and coarse cobbles n 2 were tracked daily over a 0 1 km2 intertidal area during this multi day storm boulders were repeatedly entrained transported and deposited and in some cases broken down n 1 or quarried n 3 during the most intense days of the storm eighty one percent n 39 of boulders were located at both the start and end of the storm of these 92 were entrained where entrainment patterns were closely aligned to wave parameters these data firmly demonstrate rock coasts are dynamic and vulnerable under storm conditions no statistically significant relationship was found between boulder size mass and net transport distance graphical analyses suggest that boulder size limits the maximum longshore transport distance but that for the majority of boulders lying under this threshold other factors influence transport distance paired analysis of 20 similar sized and shaped boulders in different morphogenic zones demonstrates that geomorphological control affects entrainment and transport distance where net transport distances were up to 39 times less where geomorphological control was greatest these results have important implications for understanding and for accurately measuring and modelling boulder entrainment and transport coastal managers require these data for assessing erosion risk 2016 the authors earth surface processes and landforms published by john wiley sons ltd

alongshore variation in the morphology of coastal dunes implications for storm response abstract the geomorphological impact of an extreme storm on a barrier island tends to be modeled using a single cross shore transect and dependent only on the elevation of the storm surge relative to the height of the dune the foredune line however is rarely uniform and can exhibit considerable variation in height and width alongshore at a range of length scales the purpose of this modeling study is to determine how alongshore variations in dune height affect barrier island response to extreme storms the mike21 wave and current model is used to predict the morphological response of matagorda peninsula texas in response to storm surges associated with dune scarping washover and inundation the extent and degree of dune scarping washover and shoreline erosion is predicted for each storm scenario with respect to the base morphology of the island and low pass filtered forms in which small scale topographic variance is removed results suggest that small variations in the height of an otherwise alongshore uniform foredune act as overwash conduits and are unstable leading to a more variable duneline that is more susceptible to change by subsequent storms the vertical development of the washover gaps in the duneline is limited and eventually replaced by a lateral expansion that erodes adjacent dunes and leads to a more uniform island elevation the loss of island elevation is greater for the original unfiltered alongshore profile but relatively uniform duneline is the most unstable and exhibits the greatest morphological change the different alongshore profile responses suggest that the impact of an extreme storm is sensitive to initial conditions and specifically the pre storm variability of the crest elevation alongshore this in turn suggests that the evolution of barrier islands is dependent on storm history until the variability in the duneline elevation reaches a maximum further study of barrier island response to storm sequencing with and without post storm recovery however is required to understand the evolution and form for the prototype island

storm impacts and shoreline recovery mechanisms and controls in the southern north sea abstract storm impacts play a significant role in shoreline dynamics on barrier coastlines furthermore inter storm recovery is a key parameter determining long term coastal resilience to climate change storminess variability and sea level rise over the last decade four extreme storms with strong energetic waves and high still water levels resulting from high spring tides and large skew surge residuals have impacted the shoreline of the southern north sea the 5th december 2013 storm with the highest run up levels recorded in the last 60 years resulted in large sections of the frontline of the north norfolk coast being translated inland by over 10 m storms in march and november 2007 also generated barrier scarping and shoreline retreat although not on the scale of 2013 between 2008 and 2013 a calm period recovery dominated barrier position and elevation but was spatially differentiated alongshore for one study area scolt head island no recovery was seen this section of the coast is being reset episodically landwards during storms by contrast the study area at holkham bay showed considerable recovery between 2008 and 2013 with barrier sections developing seaward through foredune recovery the third study area brancaster bay showed partial recovery in barrier location and elevation results suggest that recovery is promoted by high sediment supply and onshore intertidal bar migration at rates of 40 m a 1 these processes bring sand to elevations where substrate drying enables aeolian processes to entrain and transport sand from upper foreshores to foredunes we identify three potential sediment transport pathways that create a region of positive diffusivity at holkham bay during calm periods a general westward movement of sediment from the drift divide at sheringham sources the intertidal bar and foredune development at holkham bay however during and following storms the drift switches to eastward not only on the beach itself but also below the 7 m isobath sediment from the eroding barrier at brancaster bay and especially scolt head island also sources the sediment sink of holkham bay knowledge of foredune growth and barrier recovery in natural systems are vital aspects of future coastal management planning with accelerated sea level rise and storminess variability

southern north sea storm surge event of 5 december 2013 water levels waves and coastal impacts the storm surge event that affected the coastal margins of the southern north sea on 5 6 december 2013 produced the highest still water levels on record at several tide gauges on the uk east coast on east facing coasts south of the humber estuary and north facing norfolk water levels were higher than in the twentieth century benchmark surge event of 31 january 1 february 1953 maximum significant wave heights were highest off the north norfolk coast peak hs 3 8 m offshore 2 9 m inshore and lowest off the suffolk coast hs 1 5 1 8 m inshore comparable offshore wave heights in 1953 were 7 8 m and ca 3 m the lower wave heights and their short duration in 2013 explain both localised breaching overtopping and back barrier flooding associated with gravel ridges and relatively low earthen banks as well as the lack of failure in more highly engineered coastal defences on barrier coasts and within estuaries the signal of maximum runup was highly variable reflecting the modification of the tide surge wave signal by inshore bathymetry and the presence of a range of coastal ecosystems the landscape impacts of the december 2013 surge included the notching of soft rock cliffs and cliffline retreat erosion of coastal dunes and the augmentation or re activation of barrier island washover deposits whilst surge event related cliff retreat on the rapidly eroding cliffs of the suffolk coast lay within the natural variability in inter annual rates of retreat the impact of the surge on upper beach sand dune margins produced a pulse of shoreline translation landwards equivalent to about 10 years of normal shoreline retreat the study of east coast surges over the last 60 years and the identification of significant phases of landscape change such as periods of rapid soft rock cliff retreat and the formation of new gravel washovers on barrier islands points to the importance of high water levels being accompanied by high wave activity future developments in early warning systems and evacuation planning require information on the variable impacts of such extreme events

foredune morphological changes and beach recovery from the extreme 2013 2014 winter at a high energy sandy coast the beach dune response at truc vert sw france is analysed using dgps topographic surveys sampled every 2 4 weeks covering an alongshore distance of 1 5 km combined with wave tide and extreme water level hindcast and beach dune photographs during the 2013 2014 winter which was the most energetic since at least 1948 the beach dune system at truc vert eroded by approximately 180 m3 per beach width divided equally between beach and dune erosion beach and dune erosion was strongly variable alongshore with cuspate type rhythmic dune erosion scarps stripped of vegetation with a cross shore amplitude of 25 m the alongshore variable scarps were coupled with an alongshore variability in elevation of the beach with lower beach levels co located with the megacusp bays the following 10 months showed modest morphological beach and dune changes with for instance destabilisation of the scarped dune by trough blowouts scarp slumping and filling and seasonal beach berm dynamics the most profound morphological and vegetation changes occurred during the subsequent 10 months only 1 5 years after that winter the beach dune system at truc vert almost recovered to its pre winter volume but not to its pre winter foredune profile most of the sand volume recovery occurred during spring summer autumn 2015 when approximately 120 m3 m of sand naturally came back in the system the beach volume recovery rate was relatively steady and uncorrelated with wave conditions with rates twice as large across the megacusp bay profile as across the that of the megacusp horns during that period the widened and risen dry beach provided large fetch length enhancing onshore windblown transport and a rapid rising of the backshore the slumped and filled dune scarp which was providing a high barrier to aeolian transport from the beach to the dune since the 2013 2014 winter reformed as a dune ramp providing efficient conduit for beach dune delivery exchange of sediment by the end of the study this process favoured both natural revegetation into the scarp and incipient foredune formation despite the reinstatement of natural processes between the beach and the dune the dune foot was still located landward by more than 10 m on average with respect to its pre 2013 2014 winter position this study shows that even after the most severe winter over the last 68 years in terms of average wave energy arriving at the coast beach recovery can be a relatively fast process along high energy sandy beaches backed by large dunes in contrast foredune recovery which timing and magnitude can provide a proxy measure for the resilience of the system to climatic variability and change is a much slower process that can take years to decades

variations in the response of the dune coast of northern france to major storms as a function of available beach sediment volume a series of airborne topographic lidar data were obtained from may 2008 to january 2014 over two coastal sites of northern france bay of wissant and east of dunkirk these data were used with wind and tide gauge measurements to assess the impacts of storms on beaches and coastal dunes and particularly of the series of major storms that hit western europe during the fall and early winter of 2013 our results show a high variability in shoreline response from one site to the other but also within each coastal site coastal dune erosion and shoreline retreat occurred at both sites particularly on the coast of the bay of wissant where shoreline retreat up to about 40 m was measured however stability or even shoreline advance were also observed despite the occurrence of an extreme water level with a return period 100 years during the storm xaver in early december 2013 comparison of shoreline change with variations of coastal dune and upper beach volumes revealed only weak relationships our results nevertheless showed that shoreline behavior seems to strongly depend on the initial sediment volume on the upper beach before the occurrence of the storms according to our measurements an upper beach volume of about 30 m3 m 1 between the dune toe and the mean high water level is sufficient at these sites to protect the coastal dunes from storm waves associated with high water levels with return periods 10 years the identification of such thresholds in terms of upper beach width or sediment volume may represent valuable information for improving the management of shoreline change by providing an estimate of the minimum quantity of sand on the upper beach necessary to ensure shoreline stability in this region copyright 2016 john wiley sons ltd

the effects of storm clustering on beach profile variability abstract impacts of storms in reshaping coastlines are well known also the far greater impact of clusters of storms where storms occur at close succession has been noted in a number of previous studies in this paper we analyse and discuss the storm wave climate and the beach profile response to clusters of storms at narrabeen beach new south wales australia narrabeen beach is subjected to frequent storms all year round and the beach undergoes substantial variability as a result the impact of storm clusters with closely spaced individual storms reaching the beach is investigated by combining historic measurements of beach profile surveys and numerical modelling of storm induced beach change our analysis of storm power index of storm clusters and its correlation with the change in beach width reveals that the strengths of single storms in a storm cluster alone are not the reason for beach change but time interval between successive storms and the post storm recovery speed of the beach concerned also play important roles we have quantified and compared beach erosion return levels resulting from single storms and storm clusters it was found that beach erosion volumes resulting from storm clusters with two or more storms resemble potential beach erosion volumes induced by single storms of far higher return periods

coastal monitoring solutions of the geomorphological response of beach dune systems using multi temporal lidar datasets vendee coast france abstract three beach and dune systems located in the northeastern part of the bay of biscay in france were monitored over 5 years with a time series of three airborne lidar datasets the three study sites illustrate a variety of morphological beach types found in this region reproducible monitoring solutions adapted to basic and complex beach and dune morphologies using lidar time series were investigated over two periods bounded by the three surveys the first period between may 2008 and august 2010 is characterized by a higher prevalence of storm events and thus has a greater potential for eroding the coast than the second period between august 2010 and september 2013 during the first period the central and northeastern part of the bay of biscay was notably impacted by storm xynthia with water levels and wave heights exceeding the 10 year return period and 1 year return period respectively despite differences in dune morphology between the sites the dune crest dhigh and the dune base dlow are efficiently extracted from each dem based on the extracted dune base an original shoreline mobility indicator is built displaying a combination of the horizontal and vertical migrations of this geomorphic indicator between two lidar datasets a geomorphic change detection is also completed by computing dems of difference dod resulting in segregated maps of erosion and deposition and sediment budgets accounting for the accuracy of lidar datasets a probabilistic approach at a 95 confidence interval is used as a threshold for the geomorphic change detection showing more reliable results however caution should be taken when interpreting thresholded maps of changes and sediment budgets because some beach processes may be masked especially on wide tidal beaches by only keeping the most significant changes the results of the shoreline mobility and geomorphic change detection show a high variability in the beach responses between and within the three study sites explained mainly by beach orientation and local factors despite variable site specific mechanisms the recovery processes redistribute the available sand more on the upper parts of the beach producing significant deposition generally in the form of embryo dunes the monitoring of the beach and dune systems with airborne lidar datasets reveals that the three study sites show diverse behaviours during the first period likely associated with storms while the analysis show more homogenous beach responses during the second period likely associated with a recovery phase

simulated warm polar currents during the middle permian 1 during permian stage 6 wordian kazanian the pangaean supercontinent was surrounded by a superocean panthalassa an ocean general circulation model has been coupled to an atmospheric energy balance model to simulate the sensitivity of the wordian climate 265 million years ago to changes in greenhouse gas concentrations high latitude geography and earth orbital configurations the model simulates significantly different circulation features with different levels of greenhouse gas forcing ranging from a strong meridional overturning circulation in the southern hemisphere at low co2 concentration present level to more symmetric overturning circulation cells with deep water formation in polar latitudes of both hemispheres at high co2 concentration 8 times present level the simulated climate with 4 times present level co2 concentration agrees generally well with climate sensitive sediments and phytogeographic patterns the model simulates strong subtropical gyres with similarities to the modern south pacific circulation and moderate surface temperatures on the southern continent gondwana resulting from a strong poleward heat transport in the ocean an even more moderate climate is generated if high latitude land is removed from the southern continent so that ocean currents can penetrate into the polar regions of gondwana

erosion of rocky shore platforms by block detachment from layered stratigraphy the majority of shore platforms form in rocks that are characterised by layered stratigraphy and pervasive jointing plucking of weathered joint and bed bounded blocks is an important erosion process that existing models of platform development do not represent globally measuring platform erosion rates have focused on microscale 1 mm surface lowering rather than mesoscale 0 1 1 m block detachment yet the latter appears to dominate the morphological development of discontinuity rich platforms given the sporadic nature of block detachment on platforms observations of erosion from storm event to multi decadal timescales and beyond are required to quantify shore platform erosion rates to this end we collected aerial photography using an unmanned aerial vehicle to produce structure from motion derived digital elevation models and orthophotos these were combined with historical aerial photographs to characterise and quantify the erosion of two actively eroding stratigraphic layers on a shore platform in glamorgan south wales uk over 78 years we find that volumetric erosion rates vary over two orders of magnitude 0 1 10 m3 yr 1 and do not scale with the length of the record average rates over the full 78 year record are 2 5 m3 yr 1 these rates are equivalent to 1 2 5 3 mm yr 1 surface lowering rates an order of magnitude faster than previously published both at our site and around the world in similar rock types we show that meso scale platform erosion via block detachment processes is a dominant erosion process on shore platforms across seasonal to multi decadal timescales that have been hitherto under investigated

morphodynamic characteristics and classification of beaches in england and wales abstract the use of beach classification models has become widespread in literature in recent years beach classification models that recognise distinct modal beach states in response to environmental conditions are most widely used these models were developed largely in high energy micro to meso tidal sandy environments and subsequent attention has focussed on extending their use into other beach environments here the applicability of these traditional beach classification models to the highly diverse coastline of england and wales was assessed through collection of detailed morphodynamic characteristics of 92 beaches yielding a comprehensive multi variate data set containing morphological sedimentological and hydrodynamic information the complex and diverse study region incorporates beach morphology covering the full spectrum from reflective to dissipative and non barred to multi barred cluster analysis supplemented by mds ordination resulted in the identification of 9 distinct beach types traditional morphodynamic indices and rtr were found to be effective in discriminating between beach groups providing some support for the beach state models derived using information from australian beaches it was found that absolute wave energy wave power is important as well in controlling beach type for intermediate beaches a wave energy flux p h 2 t value of 3 kw m 1 was found to differentiate between beaches with p 3 kw m 1 and without p 1 three dimensional bar rip morphology a key component controlling recreational beach hazard levels observations presented here inform a beach classification model to be used as the basis for a national beach risk assessment programme beach classification models based on environmental parameters are by necessity simplifications and should be used as tools for understanding morphodynamic systems rather than beach type prediction

subaqueous mass flow origin for lower permian diamictites and associated facies of the grant group barbwire terrace canning basin western australia the intracratonic canning basin is western australia s largest sedimentary basin 400 000 km2 and has experienced repeated episodes of phanerozoic extension and subsidence resulting in deposition of a number of first order megasequences a major phase of basin extension and sedimentation grant group occurred in the late carboniferous early permian when australia lay at high palaeolatitudes facies analysis of 5000 m of drill core from 25 continuously cored wells in grant group strata on the fault bounded barbwire terrace in the northern canning basin identified three facies associations fas these record the predominance of fault generated subaqueous mass flow and sediment reworking the lowest association fa i up to 355 m thick rests unconformably on tilted older strata and consists of coarse grained subaqueously deposited sediment gravity flow facies these include fault generated breccias massive and graded sandstones and conglomerates deposited by turbidity currents and diamictites generated by mixing of different textural populations during downslope remobilization fa i is overlain abruptly by relatively fine grained deposits of fa ii up to 140 m thick which consist of laminated to thin bedded mudstone and sandstone turbidites recording an abrupt increase in relative water depths in turn these facies coarsen upwards and are transitional into shallow water swaley cross stratified and rippled sandstones of fa iii up to 125 m thick the overall stratigraphic succession probably records an initial phase of faulting and accommodation of coarse sediment fa i a subsequent phase of rapid subsidence increasing water depths and sediment underfilling fa ii and finally a regressive phase of shoreface progradation the occurrence of rare striated clasts in fa i suggests reworking of glacial sediment but no direct glacial influence on sedimentation can be identified

impact of the winter 2013 2014 series of severe western europe storms on a double barred sandy coast beach and dune erosion and megacusp embayments abstract the winter of 2013 2014 was characterized by a striking pattern of temporal and spatial extreme storm wave clustering in western europe the 110 km long gironde coast sw france was exposed to the most energetic wave conditions over the last 18 years the period was outstanding in terms of the available energy to move sediment and cause large scale erosion with the 2 month average significant wave height hs exceeding 3 6 m just below the 0 95 quantile and 4 distinct 10 year return period storms with hs 9 m these storm waves caused unprecedented beach and dune erosion along the gironde coast including severely damaged sea defences at the coastal towns at the end of the winter dune erosion scarp height was highly variable alongshore and often exceeded 10 m megacusp embayments were observed along the gironde coast with an average alongshore spacing of 1000 m in the south progressively decreasing to 500 m in the north with an average cross shore amplitude of 20 m while beach megacusps were previously observed to systematically couple to the inner bar along the gironde coast during low to moderate energy wave conditions severe storm driven megacusp embayments cutting the dune were found to be enforced and coupled to the outer crescentic bar a detailed inspection of the 1500 m long bimonthly topographic surveys of truc vert beach shows that in early january 2014 the outstanding shore normal incident storm swell hercules with hs and peak wave period tp peaking at 9 6 m and 22 s respectively triggered the formation of a localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m the subsequent storms progressively smoothed the megacusp by the end of the winter mostly through severe erosion of the megacusp horns because of the very long period 16 s

thresholds for storm impacts on an exposed sandy coastal area in southern portugal abstract storms are one of the most important phenomena responsible for coastal erosion their destructive power presents major challenges for coastal management and knowledge of their characteristics and associated consequences is therefore of paramount importance in this study thresholds for storm impacts are defined for a sandy coast in southern portugal faro beach ria formosa using two different approaches i hydrodynamic conditions associated with historical storm impacts i e infrastructural damage and ii computed maximum wave run up values r high compared with beach morphology damage thresholds are defined as limits above which the action of a storm exceeds beach front response capability and starts to act directly on human infrastructures according to method i four different thresholds were defined for individual storms directed from the sw the threshold is a significant wave height of 4 7 m with a storm duration of 2 days and for storms directed from the se is a significant wave height of 6 m with a storm duration of at least 2 days regarding storm groups for those directed from the sw the threshold is 2 storms lasting at least 2 days each with significant wave heights greater than 3 5 m whilst for those directed from the se the threshold is 3 short storms lasting 1 day each with significant wave height over 3 9 m the return period for the sw storm group threshold is just 1 7 years for method ii beach morphological parameters d high highest elevation of the frontal dune d low elevation of the dune base and tan f foreshore slope were determined for five chosen cross shore profiles along the study area and r high computed for different hydrodynamic conditions results were validated through field observations of storm impacts the lowest thresholds for overwash are along the central part of the study area where a dune crest is absent due to human occupation the highest thresholds for overwash are on those profiles where a frontal dune is well developed or a foredune ridge is present western and eastern parts of the study area this study presents a methodological strategy to compute realistic thresholds for storm impacts along faro beach based on historical datasets of hydrodynamics and storm impacts information the approach could be implemented in other coastal areas to provide a comprehensive assessment of the storm impact requiring only simple information like offshore storm hydrodynamics characteristics beach morphology and reports of coastal infrastructure damage

classification of beach response to extreme storms abstract extreme storms are responsible for rapid changes to coastlines worldwide during the 2013 14 winter the west coast of europe experienced a sequence of large storm induced wave events representing the most energetic period of waves in the last 60 years the southwest coast of england underwent significant geomorphological change during that period but exhibited a range of spatially variable and complex morphological responses despite being subjected to the same storm sequence here we use the 2013 14 storm response along the southwest coast of england as a natural field laboratory and explain this variability in storm response through the introduction and evaluation of a new classification of how sandy and gravel beaches respond to extreme storms cluster analysis was conducted using an unique data set of pre and post storm airborne light detection and ranging lidar data from 157 beach sites based on the net volumetric change dqnet and a novel parameter the longshore variation index lvi which quantifies the alongshore morphological variability in beach response four main beach response types were identified 1 fully exposed beaches that experienced large and alongshore uniform sediment losses dqnet 100 m3 m 1 2 semi exposed beaches that experienced medium alongshore uniform sediment losses dqnet 50 m3 m 1 3 sheltered short beaches that experienced limited net sediment change and alongshore variability in beach response and 4 sheltered long beaches that experienced considerable alongshore variability in beach response and large gross sediment change but limited net sediment change the key factors in determining the type of beach response are exposure to the storm waves angle of storm wave approach and the degree to which the beach is embayed these factors are universally applicable on many exposed coastlines worldwide so the response classification presented here is expected to be widely applicable

nearshore sediment pathways and potential sediment budgets in embayed settings over a multi annual timescale abstract embayed beaches constitute a large proportion of the world s rocky coastlines but there is a paucity of studies focusing on the longshore sediment exchange between embayed beaches separated by rocky stretches of coast here we investigate the nearshore sediment transport dynamics along a 15 km stretch of the embayed coastline of north cornwall sw england using delft3d numerical simulations coupled wave and tide are conducted to compute major circulation modes and sediment fluxes including order of magnitude for sediment bypassing between bays for a wide range of modal and extreme wave conditions results indicate that extreme events cause i multi embayment circulation and mega rip formation where an alongshore current is deflected offshore 0 7 m s 1 at 20 m depth in the down wave sectors ii large bypassing rates 103 104 m3 day 1 bypassing and iii exchanges extending to depths that exceed the base of the headlands accretionary phases over moderate high swell periods were associated with clockwise intra embayment circulation with simulated currents inducing redistribution towards the south in the long embayments 103 m3 day 1 longshore this circulation mode is combined with significant bypassing rates around the shallower and wider headlands 102 103 m3 day 1 predictions of sediment fluxes along the lower shoreface are based on the correlation between the modelled sediment fluxes and offshore wave conditions r 0 92 providing insights into the potential sediment budget over multi annual timescales hindcasted yearly bypassing rates around the headlands range between 103 and 105 m3 y 1 under an assumption of unlimited sediment supply with the bulk of the transport occurring mainly during high energy events hence the magnitude of the computed potential sediment fluxes presented here has implications for coastal evolution at longer timescales 10 years especially along sediment starved coastlines

role of waves and tides on depth of closure and potential for headland bypassing abstract depth of closure is a fundamental concept used to define the seaward extent of a morphodynamically active shoreface at a particular temporal scale the estimation of this limit in relation to the depth in front of the bounding headlands along embayed coastlines allows questioning whether embayments often deemed closed sediment cells experience more headland bypassing than expected wave based parameterisations developed for microtidal beaches are most widely used to estimate closure depth however a re evaluation of the concept for shorefaces influenced by geological control presence of headlands and or bedrock and strong tidal currents is appropriate here we use the macrotidal embayed and high energy coastline of sw england to identify the active nearshore limits with a multi method approach that includes observations of shoreface morphology and sedimentology offshore inshore wave formulations and bed shear stress computations we identify the basal limit of significant i e 0 14 m morphological change depth of closure doc and a maximum depth of extreme bed activity and sediment transport depth of transport dot observations of doc correspond closely to the values predicted by existing formulations based on inshore wave conditions 10 15 m for the study area relative to mean low water spring water level in this case the computed dot represented by the upper plane bed transition attained under extreme conditions exceeds 30 m depth in the study area the significant implication is that even though many headlands appear sufficiently prominent to suggest a closed boundary between adjacent embayments significant wave and tide driven sediment transport is likely to occur beyond the headland base during extreme events especially at low water levels the maximum depth for significant sediment transport dot was computed across a broad wave current parameter space further highlighting that tidal currents can increase this closure depth estimate by 10 m along macrotidal coastlines representing a 30 increase compared to tideless settings this work illustrates the importance of tidal currents in depth of closure calculations and challenges the notion that embayed beaches are generally closed cells as headland bypassing may be more wide spread than commonly assumed along exposed coastlines globally

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

predicting beach rotation using multiple atmospheric indices abstract shoreline change in the form of beach rotation can occur at event to decadal timescales especially in semi sheltered embayments with bi directional wave climates leading to enhanced coastal vulnerability under predictions of increased sea level rise previous studies have shown that phases of winter averaged atmospheric indices in the north atlantic correlate with variations in average winter wave height and dominant direction however predictions of a localised wave climate and beach rotation from individual climate indices has exhibited limited skill here we show that the combination of two major north atlantic climate indices the north atlantic oscillation nao and west europe pressure anomaly wepa improves the prediction of a wave power directionality index wdi known to correlate with beach rotation along the length of a headland bound gravel embayment results using a combination of nao and wepa improves predictions of wdi with an associated r2 of 0 66 when compared to 0 23 and 0 31 for nao and wepa individually hindcast wdiww3 and index predicted wdipred values of the wdi were shown to validate against measured beach rotation from 2008 to 2018 and modelled inshore potential longshore energy fluxes from 1980 to 2018 a long term historic time series of wdipred 1906 present was then hindcast using records of nao and wepa qualitative validation of long term beach rotation in response to the wdipred is achieved with proxy records of beach change in the form of oblique and aerial photography and topographic maps low frequency 60 years beach rotation is shown to follow phases of the detrended cumulative wdipred values over the period of 1906 to 2018 linked to the multi decadal fluctuations in detrended cumulative values of nao and wepa when examined in the context of millennial scale proxy nao records it is clear the recent centurial scale analysis does not capture past variability and duration this work has shown that 1 potential future season ahead forecasts of atmospheric indices may skilfully predict beach rotation in many regions with bi directional wave climates and 2 historical analysis highlights the potential past phases of extreme coastal realignment these new insights will lead to proactive and informed management from local authorities and coastal engineers

understanding and predicting the temporal variability of sediment grain size characteristics on high energy beaches abstract despite representing a key parameter when modelling morphology or sediment transport surface sediments are often assumed homogenous with grain size temporally constant this contribution uses a 6 year data set of monthly sediment samples to quantify the observed variability in intertidal beach sands at four energetic macrotidal locations north cornwall uk changes in grain size and sorting were related to periods of high steepness storm waves promoting a relatively rapid coarsening and an improvement in sorting and low steepness swell waves a fining and a reduction in sorting these temporal changes in intertidal grain size were coherently linked to the disequilibrium in wave steepness with peak coarsening occurring when the instantaneous wave steepness conditions vastly exceeded a temporally evolving antecedent time series using this concept a simple model is proposed that provides skilful predictions of the unseen variability in sediment grain size average r2 0 86 p

a comprehensive hydro geomorphic study of cliff top storm deposits on banneg island during winter 2013 2014 large clastic cliff top storm deposits called ctsds are one of the most remarkable signatures that characterizes extreme storm wave events on coastal cliffs hence the study of ctsds is of key importance for understanding and predicting the impacts of extreme storm wave events on rocky coasts or establishing proxies for storm intensity the present study uses new data including hydrodynamic measurements in both deep and intertidal waters and records of ctsds displacement and deposition across banneg island during the stormy winter 2013 2014 two drone based surveys were carried out in january 2013 pre storms and in april 2014 post storms in addition complementary field observations were carried out during the winter providing a comprehensive and detailed dataset concerning the hydrodynamic measurements nine pressure sensors deployed along four cross shore profiles on the western coast of the island recorded wave and water level conditions between december 2013 and april 2014 aerial orthorectified photographs and digital elevation model of differences provide a detailed spatial description of cliff erosion and the reworking of cliff top storm deposits after the storms 172 fresh scars corresponding to quarrying in the bed rock were localized above high spring tide water level 507 blocks were transported up to 40 m inland at altitudes of 8 to 14 m above mean sea level and the tracks of 170 of them were identified the water levels and wave parameters estimated from the pressure sensor measurements provided accurate information on the maximum water elevation reached during the largest storms at the sensor locations and were extrapolated to provide run up elevation along the four survey profiles for the whole winter 2013 2014 the results demonstrate that a large number of overwash episodes occurred at times of high tides and energetic waves these episodes generally correspond to morphological changes this study confirms the major role played by extreme storm wave events on ctsds quarrying transport and deposition on banneg island and clearly identify the events of major evolutions

coastal erosion rates of lava deltas around oceanic islands abstract rates of coastal erosion are needed for planning purposes and to improve understanding of how the shelves of islands develop ultimately becoming submerged banks near shore submarine platforms created by erosion of lava deltas of known age provide an opportunity to quantify erosion rates and to investigate how those rates vary between different types and ages of lava flows as well as how they vary with wave climate we have compiled data on deltas formed during historical and holocene eruptions age 6 ka from both a and p hoehoe lava flows and from diverse localities azores and hawaiian islands and ascension island near shore platforms were interpreted from multibeam sonar bathymetric light detection and ranging lidar and historical sounding data from them we estimated time averaged shoreline retreat rates from the seaward distances between the modern coastlines and the submarine platform edges the 35 interpreted platforms have rugged dipping surfaces left behind by erosion with an average gradient of 5 range 2 10 eroded distance of 436 m 78 1119 m and depth of platform edge of 25 m 5 56 m to evaluate the latter depths we computed seabed orbital speeds due to surface waves at the platform edges depths of platform edges correlate only modestly with those speeds suggesting that platform surfaces have adjusted to wave conditions with a wide range of particle sizes and hence thresholds of motion the largest retreat distances 800 m are associated with platforms of the central azores islands which are exposed to higher waves however retreat rates are highly varied 0 08 12 5 m yr and weakly correlated with measures of wave power suggesting that waves are only a secondary influence given that lack of correlation we suspect that the main factor contributing to variability arises from varied cliff resistance to erosion blocks between joints in lava flows and hence resistance to erosion vary greatly in size from the thicker and less densely jointed a flows to the thinner and shell like layered lavas in p hoehoe flows

extraordinary boulder transport by storm waves west of ireland winter 2013 2014 and criteria for analysing coastal boulder deposits abstract before and after photos of supratidal coastal boulder deposits cbd in the west of ireland show that storms in the winter of 2013 2014 transported boulders at elevations up to 29 m above high water and at inland distances up to 222 m among the clasts transported are eighteen weighing more than 50 t six of which exceed 100 t the largest boulder moved during those storms weighs a fairly astonishing 620 t the boulders moved in these recent storms provide pinning points for mapping storm wave energies on coasts their topographic positions mark elevations and distances inland reached by wave energies sufficient to dislocate those specific masses taken together the cbd data reveal general relationships that shed light on storm wave hydrodynamics these include a robust correlation inverse exponential between maximum boulder mass transported and emplacement height above high water the greater the elevation the smaller the maximum boulder size with a dependency exponent of about 0 2 times the elevation in metres there is a similar relationship although with a much smaller rate of change exponent 0 02 between boulder mass and distance inland which holds from the shoreline in to about 120 m coastal steepness calculated as the ratio of elevation to inland distance seems to exert the strongest control with an inverse power law relationship between maximum boulder mass and slope ratio the more gentle the topography the larger the moved boulders quantifying cbd dynamics helps us understand the transmission of wave energies inshore during high energy storm events the transported boulders documented here are larger than many of those interpreted to have been moved by tsunami in other locations which means that boulder size alone cannot be used as a criterion for distinguishing between tsunami and storm emplacement of cbd the biggest blocks up to 620 t are new maxima for boulder mass transported by storm waves we predict however that this record will not last long the 2013 2014 storms were strong but not extreme and there are larger boulders in these deposits that didn t move on this occasion bigger storms will surely move larger clasts and clasts at greater distances from the shoreline these measurements and relationships emphasise the extreme power of storm waves impacting exposed coastlines and require us to rethink the upper limits of storm wave energy at coasts

the response of three main beach types to tropical storms in south china abstract based on the observational data of 6 storms and 8 different beaches on the coasts of southern china the paper is concerned with the characteristics of storm effects on beaches with different morphodynamic types in south china a dissipative beach is very stable and has a weak response to tropical storms the storm induced morphological changes for this type of beach are characterized by erosion at the dune toe and minor changes on the beach face a low tide terrace beach has a strong response to storms with marked changes in the upper profile a barred beach usually experiences berm erosion swash bar smoothening and seaward bar migration during storms overwash may occur for the beach without backshore dune or protection in this paper backshore changes and the alteration of beach gradient in response to tropical storms are discussed with taking into account tidal influences a new morphodynamic parameter et is proposed in order to highlight the beach response intensity to storm action results show that the inherent morphodynamic properties have significant effects on the beach response to storm the more dissipative beach has a smaller response intensity and shows a moderate change in beach profile during a storm while a more reflective beach has a greater response intensity and changes markedly under storm conditions

morphological barrier island changes and recovery of dunes after hurricane dennis st george island florida abstract during the summer of 2005 hurricane dennis overwashed the eastern portion of st george island part of the northwest barrier island chain located along the florida panhandle in this paper lidar based morphological changes of the barrier island are analyzed along with the short term post storm recovery of secondary dunes results show that overwash from the storm surge removed nearly the entire foredune complex and the initial breaching probably occurred where the complex was either low or discontinuous in these locations beach widening was less in contrast approximately 10 m of beach widening occurred where foredunes were higher and continuous implying that more sediment was available for seaward transport during storm conditions the secondary dunes recovered at an average linear rate of 3 4 cm per month in the presence of vegetation although monthly averages varied from 1 5 to 1 4 m3 m and total volume changes varied from 17 9 to 16 4 m3 m for the duration of the study furthermore vegetation deterred dune migration thus favoring dune growth and reducing erosion due to wind in contrast the absence of vegetation inhibited dune growth insignificant changes in elevation occurred in areas of storm debris or lag deposit finally distributions of topographic gradients and curvature calculated numerically from pre and post storm lidar data are introduced as a potential tool in determining the relative post storm recovery of the dune field

coupling cross shore and longshore sediment transport to model storm response along a mixed sand gravel coast under varying wave directions abstract this paper investigates the profile response of a mixed sand gravel deltaic beach playa granada southern spain forced by storm waves from varying directions beach morphology was monitored over a 36 day period with variable wave conditions and profile response was compared to model predictions using the xbeach g model and a longshore sediment transport lst formulation xbeach g was applied over 2 day periods of low energy south westerly sw storm and south easterly se storm conditions and was coupled to lst using a parametric approach which distributes the lst across the swash surf and nearshore zones a calibrated wave propagation model delft3d was used to obtain the inshore conditions required to drive the xbeach g model and the lst formulation the storm response is clearly influenced by the free board difference between the height of the berm and the total run up and is also strongly dependent on storm wave direction with the sw storm eroding the surveyed area while the se storm induced beach accretion model results indicate that xbeach g on its own is capable of adequately reproducing the response of the beach under sw storm conditions b s s 0 95 but not under se storms due to the higher lst gradients at the study location the combination of xbeach g and lst fits the measured profiles reasonably well under both sw b s s 0 96 and se b s s 0 88 storms inspiring confidence in the coupled model to predict the storm response under varying wave conditions the combined xbeach g lst model was applied to the entire 6 8 km deltaic coastline to investigate the impact of extreme sw and se storm events and the model results reiterate the importance of cross shore and longshore sediment transport in driving coastal storm response at this location the approach proposed in this work can be extended to other worldwide coasts highly influenced by both cross shore and longshore sediment transport such as beaches with different coastline orientations and or forced by varying wave directions

grain size distributions on high energy sandy beaches and their relation to wave dissipation grain size and sorting represent two key parameters when characterising sediments or modelling beach morphology and sediment transport traditionally an average value for grain size or sorting is often assumed for the entire area determined from only a few sediment samples ignoring any spatial or temporal variability in sediment characteristics this contribution uses a data set of physical surface sediment samples from 53 beach locations around the south west peninsula of the united kingdom in addition to bi monthly high spatial resolution mean 240 samples digital grain size surveys from a high energy oceanic sandy beach perranporth north cornwall systematic spatial variations in grain size and sorting were consistently observed in the seaward direction across the intertidal zone of sandy beaches with grain sizes coarsening and sorting improving by up to 51 7 and 64 3 respectively this variability was deterministically related to the time averaged antecedent adjusted energy dissipated by breaking waves with the observed maximum grain sizes and sorting values correlating with the location of peak wave energy dissipation r2 0 998 p 0 01 this article is protected by copyright all rights reserved

extreme wave activity during 2013 2014 winter and morphological impacts along the atlantic coast of europe studies of coastal vulnerability due to climate change tend to focus on the consequences of sea level rise rather than the complex coastal responses resulting from changes to the extreme wave climate here we investigate the 2013 2014 winter wave conditions that severely impacted the atlantic coast of europe and demonstrate that this winter was the most energetic along most of the atlantic coast of europe since at least 1948 along exposed open coast sites extensive beach and dune erosion occurred due to offshore sediment transport more sheltered sites experienced less erosion and one of the sites even experienced accretion due to beach rotation induced by alongshore sediment transport storm wave conditions such as were encountered during the 2013 2014 winter have the potential to dramatically change the equilibrium state beach gradient coastal alignment and nearshore bar position of beaches along the atlantic coast of europe

drivers of alongshore variable dune erosion during a storm event observations and modelling abstract the ability to understand and predict alongshore variable sand dune erosion is key to better coastal management this study utilizes detailed observations immediately pre during and post storm topography waves and water levels collected over a 6 day period at the 3 6 km long narrabeen collaroy beach in south east australia to identify and explore drivers of the highly variable alongshore dune erosion caused by an east coast low storm in june 2011 key characteristics of the immediately pre storm subaerial morphology obtained by airborne lidar beach slope dune toe elevation dune height varied considerably alongshore daily airborne lidar surveys conducted at low tide indicated considerable temporal variability in the evolution of the subaerial beach profile despite considerable alongshore variability in the magnitude of modelled inshore wave heights during the storm it was instead observed that the predominant determinant of maximum dune erosion was the pre storm dune toe elevation a simple dune impact model forced with local alongshore variable inshore wave modelling was found to successfully predict up to 85 of the observed alongshore variability in dune erosion at this site with this erosion tidally modulated over the 6 days to time periods when the waves were directly impacting the dune importantly alongshore variation in wave height is shown to account for just 10 of the alongshore variability in dune erosion during this storm these results reconfirm that knowledge of the pre storm subaerial morphology in particular the elevation of the dune toe with respect to time varying water levels during a storm is a key driver of alongshore variability in the erosion response along dune backed sandy coastlines

morphodynamic variability of high energy macrotidal beaches cornwall uk abstract spatial data collected over three years are presented to assess the extent of morphological variability under seasonal and storm waves on two high energy macrotidal beaches on the north cornish coast of particular interest was the degree to which the beaches displayed bar rip morphology and a novel approach to quantify the three dimensionality of the beach based on the curvature of the bottom contours is adopted to identify and classify the three dimensional beach response to changes in the dominant forcing conditions morphologically the beaches range from dissipative to intermediate and are characterised by low tide bar rip morphology which plays a key role in the nearshore dynamics and beach safety real time kinematic rtk gps surveys were undertaken using an all terrain vehicle to measure the three dimensional 3d morphology in addition nearshore wave data in situ hydrodynamic measurements local tide gauges and argus video data allowed detailed analysis of process response mechanisms for long term yearly seasonal monthly storm weekly daily and tidal hourly morphological behaviour both sites exhibited net long term accretion derived from the intertidal beach volume throughout the survey period inter site similarity in beach response was observed in response to storm waves yet coupling between the seasonal wave climate and the beach morphology was not evident at either of the sites increased wave conditions exceeding hs 4 m during sustained storm events 50 h led to offshore transport from the beachface to the subtidal bar region post storm recovery was characterised by onshore transport and the development of substantial 3d low tide morphology under normal wave conditions hs 1 6 m the dominant 3d features smoothed out as channels in filled and bar prominence reduced over a period of 2 3 months overall the beaches exhibited a significant storm dominated morphological response cycle unlike the more familiar winter summer seasonal response

the extreme 2013 2014 winter storms beach recovery along the southwest coast of england abstract sand and gravel beaches naturally act as a coastal buffer absorbing wave energy and dynamically adapting to the seasonal and long term wave climate significant shifts in nearshore morphology can occur during extreme wave events which can have a significant impact on coastal vulnerability during the winter of 2013 14 the atlantic coast of europe received an unprecedented sequence of very energetic wave conditions 8 week mean offshore h s 4 4 m these events caused extensive physical beach and dune erosion and socio economic flooding damage to infrastructure impacts throughout the west coast of europe many monitored sites in the uk and france were in their most eroded state since morphological records began 5 10 years we consider the geomorphological significance of the storm response at 38 natural beaches in the southwest of england ranging from semi sheltered reflective gravel barriers to ultra dissipative exposed sand beaches with dunes the extent and patterns of post storm recovery are examined in detail at three beaches with characteristic storm response behaviours exposed sandy beaches were dominated by cross shore transport processes leading to significant loss of sediment offshore from the intertidal zone 200 m 3 m exposed gravel beaches were dominated by overwash with significant loss landward and semi sheltered sites exposed to more oblique wave forcing were dominated by a rotational response due to alongshore sediment redistribution due to these contrasting responses mechanisms and timescales for beach recovery displayed strong inter site and intra site variations in offshore and rotational cases the recovery processes were multi annual comprising seasonal to decadal signals and were intrinsically linked to the storm response mechanisms while permanent losses occurred when overwash dominated we show that post storm recovery does not necessarily occur during calm periods and that in many cases high energy wave events appear to be essential for recovery of sediment offshore and counter rotation our results highlight the significance of dominant climatic oscillations multi annual storm sequencing storm tracks and resultant variations in wave angle in controlling the impact that extreme wave events have on contrasting sand gravel beaches in exposed sheltered locations