rapid erosion of a small southern california beach fill abstract a winter storm eroded a small 160 000 m3 beach fill at torrey pines state beach in southern california the fill constructed in april 2001 was a 600 m long flat topped berm extending from a highway revetment seaward about 80 m terminating in a 2 m tall near vertical scarp the size distributions of the preexisting and fill beach sand were similar median 0 2 mm a total of 56 cross shore transects were surveyed between the revetment and 8 m water depth biweekly along 2 7 km of the beach centered on the fill area during summer and fall the incident significant wave heights measured 1 km offshore of the fill usually were below 1 m the scarp was not overtopped and the fill did not change greatly the beach face alongshore of the fill accreted consistent with the usual seasonal cycle in southern california during a storm 3 m significant wave height in late november erosion began when wave uprushes overtopped the scarp and reached the relatively flat elevated fill where the overwash flowed alongshore to initially small depressions that channeled the flow seawards the offshore flow rapidly deepened and widened the channels which maintained steep vertical faces and eroded by slumping thirty hours after the storm began the shoreward end of the eroded channels had retreated to the highway revetment leaving uneroded sand peninsulas protruding seawards 50 m from the revetment and elevated 1 75 m above the surrounding beach erosion of the beach adjacent to the fill was much less variable alongshore than within the fill region during the next few days the peninsulas eroded almost completely

u pb zircon geochronology of eclogites from the scandian orogen northern western gneiss region norway 14 20 million years between eclogite crystallization and return to amphibolite facies conditionsthis article is one of a series of papers published in this special issue on the theme of geochronology in honour of tom krogh reconstructing tectonic histories involving continental collision subduction and exhumation at plate tectonic rates of 1 cm year requires precise u pb zircon geochronology the western gneiss region has exceptional exposures of high pressure hp and ultra high pressure uhp rocks the strategy adopted here involved sampling eclogite and associated late unstrained pegmatites to acquire the time of eclogite crystallization and subsequent exhumation respectively the oldest eclogite sampled is 415 1 ma from layered probably uhp eclogite at tevik averoya also with a garnet hornblende assemblage at 410 1 ma the flem gabbro eclogite margin with implied uhp conditions is 410 2 ma hornblende eclogite at seth lepsoya never at uhp is 412 2 ma these compare to devonian ages of 401 1 ma for overgrowths on proterozoic baddeleyite in selnes gabbro 402 2 ma for coesite eclogite at hareidlandet 405 400 ma for coesite eclogite at flatraket and 405 2 ma for near uhp eclogite at hjelmeland

evaluating proxies for estimating subaerial beach volume change across increasing time scales and various morphologies proxies such as changes in beach profiles and shoreline positions are commonly used in management and research for estimating changes in subaerial beach volume however the accuracy of these proxies across increasing time scales and complex morphologies is unclear volume changes associated with along beach morphologic variability may not be captured well by changes in profiles while volume changes associated with across beach morphologic variability may not be captured well by measuring shoreline change this study assesses the impacts of morphologic variations associated with beach cusps and nourishment material on volume change estimates from profiles and shoreline change at 0 5 to 3 5 year time periods results indicate that profiles spaced 150 m apart and the shoreline change proxy will likely estimate volume change inaccurately over periods 1 year at beaches that are consistently eroding or accreting and contain cusps however over longer time periods 1 3 5 years estimates of volume change from both proxies improved at those types of beaches volume changes at the edges of nourishment areas are not captured well by profiles when the nourishment material is graded to a ramped morphology which minimizes across beach morphologic variability the shoreline change proxy does accurately estimate volume changes both proxies estimate volume changes inaccurately at beaches where volume changes oscillate between erosion and accretion on both short and long time scales because the magnitude of small scale changes in volume from the formation and erosion of morphologic features such as cusps and berms will always be similar to the longer term net volume change this study suggests that decadal records of shoreline change which are commonly developed using aerial photography can be used to help identify the best proxy for estimating volume change however recent anthropogenic modifications that impact patterns of beach sedimentation including nourishment terminal groins and inlet channel dredging makes decadal records less useful copyright 2013 john wiley sons ltd

statistical simulation of wave climate and extreme beach erosion abstract recent developments in extreme values modelling have been used to develop a framework for determining the coastal erosion hazard on sandy coastlines this framework quantitatively reproduced the extreme beach erosion volumes obtained from field measurements at narrabeen beach australia this encouraging finding was achieved using kriebel and dean s kriebel d l and dean r g 1993 convolution method for time dependent beach profile response journal of waterway port coastal and ocean engineering 119 2 204 226 simple beach erosion and accretion model the method includes allowances for joint probability between all basic erosion variates including wave height period and direction event duration tidal anomalies and event spacing a new formulation for the dependency between wave height and period has been developed it includes the physical wave steepness limitation event grouping where significantly more erosion can occur from two closely spaced storms is handled by temporally simulating the synthetic wave climate and the resulting beach erosion and accretion

influence of storm sequencing on breaker bar and shoreline evolution in large scale experiments abstract new large scale experiments on the influence of storm sequencing on beach profile evolution are presented the experiments comprised three sequences that commenced from the same initial beach profile each sequence consisted of two storms of different energy with each storm followed by a recovery phase a specific focus of the experiments was the influence of storm chronology as well as the influence of the recovery wave energy and duration on beach evolution the breaker bar and the shoreline are studied as indicators for the beach response both evolve towards an equilibrium location for each wave condition where the breaker bar reaches its equilibrium much faster than the shoreline overall no enhanced beach erosion due to storm sequencing is observed despite a similar cumulative wave power of the three sequences the final beach configuration of each sequence seems to be determined by the last wave condition instead of previous storms however storm sequencing is important when the beach profile has not yet fully recovered before being disrupted by the subsequent storm in this case the second storm does not necessarily cause further erosion but can result in onshore sediment transport and hence form part of the recovery the bulk onshore sediment transport as well as the shoreline recovery rate vary depending on the wave condition and the profile disequilibrium and show a maximum value for a recovery condition with an intermediate wave energy the very low energy condition that was performed for a long duration 24 hours generated a near stationary beach profile with typical features of a reflective beach

beach erosion and recovery during consecutive storms at a steep sloping meso tidal beach this study analyses beach morphological change during six consecutive storms acting on the meso tidal faro beach south portugal between 15 december 2009 and 7 january 2010 morphological change of the sub aerial beach profile was monitored through frequent topographic surveys across 11 transects measurements of the surf swash zone dimensions nearshore bar dynamics and wave run up were extracted from time averaged and timestack coastal images and wave and tidal data were obtained from offshore stations all the information combined suggests that during consecutive storm events the antecedent morphological state can initially be the dominant controlling factor of beach response while the hydrodynamic forcing and especially the tide and surge levels become more important during the later stages of a storm period the dataset also reveals the dynamic nature of steep sloping beaches since sub aerial beach volume reductions up to 30 m3 m were followed by intertidal area recovery 2 z 3 m with rates reaching 10 m3 m however the observed cumulative dune erosion and profile pivoting imply that storms even of regular intensity can have a dramatic impact when they occur in groups nearshore bars seemed to respond to temporal scales more related to storm sequences than to individual events the formation of a prominent crescentic offshore bar at 200 m from the shoreline appeared to reverse the previous offshore migration trend of the inner bar which was gradually shifted close to the seaward swash zone boundary the partially understood nearshore bar processes appeared to be critical for storm wave attenuation in the surf zone and were considered mainly responsible for the poor interpretation of the observed beach behaviour on the grounds of standard non dimensional morphological parameters copyright 2011 john wiley sons ltd

storm impact on the seasonal shoreline dynamics of a meso to macrotidal open sandy beach biscarrosse france abstract a three year dataset 2007 2010 of shoreline and sandbar positions derived from video observations of an open sandy beach biscarrosse france is analyzed to explore the impact of storms on the seasonal shoreline dynamics the results indicate that a clear seasonality is observed in the offshore significant wave height and in the occurrence of winter storm events that are defined as periods with significant wave height greater than 4 m lasting at least 12 h data indicate that the range of variation of the inner sandbar positions 120 m is two and a half times larger than the range of variation of the shoreline position correlation analyses suggest that the offshore conditions do not conclusively explain the position of the inner bar shoreline positions show a clear seasonal pattern displaying a stable position occurring in february and july providing evidence of seasonal recovery although analysis of storm activity indicates that the number and intensity of storms is highly variable over the three years the biscarrosse data show that rapid erosion can be observed also under moderate conditions and that beach recovery after the storm season can be relatively rapid

analysis of observed two and three dimensional nearshore bar behaviour abstract shore parallel sandbar systems often exhibit considerable quasi regular alongshore variations such as crescentic plan shapes therefore morphological change in such systems commonly consists of two and three dimensional variability the former is related to overall on offshore bar migration whereas the latter is induced by the horizontal amplitude growth migration or length scale change of the quasi regular topography in this paper we used a six week data set of bathymetric surveys and video images of breaking induced foam to quantify short term days weeks two and three dimensional variability in the bar crest position of the double barred beach at egmond aan zee netherlands the alongshore uniform response was computed as the mean of each bar crest line whereas the alongshore non uniform behaviour was characterised by the amplitude around each mean a more sophisticated description of the inner bar data set was provided by complex empirical orthogonal function ceof analysis the first complex mode containing about 85 of the variance in the data set corresponded to the amplitude growth and longshore migration of an approximately 600 m long alongshore non uniformity the longshore migration rate varied between 0 and 150 m day and was found to be well related to the longshore component of the offshore wave energy flux the second complex mode explained about 10 of the variance and largely described the alongshore averaged cross shore bar migration the ceof results suggest that short term variability in bar crest position is largely due to changes in the quasi regular topography and not to alongshore uniform on offshore oriented behaviour

storm sequencing and beach profile variability at hasaki japan abstract beach profile evolution under storm sequence forcing presents an emerging research topic that has only been investigated at a limited number of sites the occurrence and effects of storm sequencing on beach profile evolution are studied at hasaki beach japan using weekly beach profile and two hourly offshore wave measurements during the 25 year study period the supratidal beach at hasaki is subjected to long term accretion and steepening while the shoreline shows a long term oscillation in addition oscillations of the supratidal beach volume and the shoreline at semi annual and annual intervals are identified which are largely controlled by the variability of the wave height hasaki beach is subjected to frequent storms that often cluster in sequences especially during the extra tropical cyclone season january to march the majority of storms and sequences generate erosion of the beach above the low water level but some also lead to recovery despite a tendency for storms and storm sequences with larger power to cause more erosion the present data does not demonstrate increased beach erosion by storm sequences following these findings the tendency of the beach to evolve towards equilibrium and the importance of the antecedent beach morphology are demonstrated

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

observations of wave run up and groundwater seepage line motions on a reflective to intermediate meso tidal beach abstract swash sw and ground water seepage line gwsl motions have been recorded at an exposed meso tidal reflective to intermediate beach using a coastal video monitoring system during a 15 month period the monitoring period allowed the collection of imagery under a wide variety of wave and beach morphological conditions and sw and gwsl velocities were extracted on a wave by wave basis the continuous double bounded kumaraswamy kw probability distribution is proposed to parameterize the sw and gwsl height distributions and since the distribution shape of the latter was shown to be influenced by the tidal elevation generic tidal elevation dependent kw pdfs are proposed the beach face slope more than any other factor tested was found to apply certain control to the mean uprush backwash and gwsl velocities the results also indicate that in reflective to intermediate beaches the gwsl lies between the mean and 2 exceedance swash elevation with the occurrence of swash running above a saturated beach face being controlled by the tidal gradient and the significant wave height

circulation of modified circumpolar deep water and basal melt beneath the amery ice shelf east antarctica antarctic ice sheet mass loss has been linked to an increase in oceanic heat supply which enhances basal melt and thinning of ice shelves here we detail the interaction of modified circumpolar deep water mcdw with the amery ice shelf the largest ice shelf in east antarctica and provide the first estimates of basal melting due to mcdw we use subice shelf ocean observations from a borehole site am02 situated 70 km inshore of the ice shelf front together with open ocean observations in prydz bay we find that mcdw transport into the cavity is about 0 22 0 06 sv 1 sv 106 m3 s 1 the inflow of mcdw drives a net basal melt rate of up to 2 0 5 m yr 1 during 2001 23 9 6 52 gt yr 1 from under about 12 800 km2 of the north eastern flank of the ice shelf the heat content flux by mcdw at am02 shows high intra annual variability up to 40 our results suggest two main modes of subice shelf circulation and basal melt regimes 1 the ice pump high salinity shelf water circulation on the western flank and 2 the mcdw meltwater driven circulation in conjunction with the ice pump on the eastern flank these results highlight the sensitivity of the amery s basal melting to changes in mcdw inflow improved understanding of such ice shelf ocean interaction is crucial to refining projections of mass loss and associated sea level rise

effects of storm clustering on beach dune evolution abstract impacts of storm clustering on beach dune morphodynamics were investigated by applying the state of the art numerical model xbeach to formby point sefton coast uk the adopted storm cluster was established by analysing the observed winter storms from december 2013 to january 2014 using a storm threshold wave height the first storm that occurred during this period is regarded as exceptionally intense and the occurrence of such a cluster of events is very unusual a 1d model was setup for the highly dynamic cross shore at formby point after initial calibration of the model parameters against available post storm profile data the model was used for the simulation of the storm cluster it was assumed that no beach recovery occurred between adjacent storms due to the very short time intervals between storms as a result the final predicted post storm profile of the previous storm was used as the pre storm profile of the subsequent storm the predicted evolution during each storm was influenced by the previous storms in the cluster due to the clustering effect the bed level change is not proportional to the storm power of events within the cluster as it would be in an individual storm case initially the large storm events interact with the multi bared foreshore enabling the subsequent weaker storms to influence the upper beach and lower dune system this results in greater change at the dune toe level also during less severe subsequent storms it is also shown that the usual water level threshold used to define dune erosion is over predicted by about 1 m for extreme storm conditions the predicted profile evolution provides useful insights into the morphodynamic processes of beach dune systems during a storm cluster using formby point as an example which is very useful for quantifying the clustering effects to develop tools for coastal management

comparison of storm cluster vs isolated event impacts on beach dune morphodynamics two dimensional numerical simulations were used to investigate the impacts of storm clustering on the beach dune evolution of the sefton coast liverpool bay uk a storm cluster consisting of a series of closely spaced seven events was identified using observed wave and surge data during the 2013 2014 winter period first event in this cluster is regarded as exceptionally intense and the occurrence of seven storms within a very short time period is unique the xbeach coastal area model was used to simulate beach change from 1 the storm sequence clustered events and 2 the same storms considering them as isolated events offshore metadata was transformed to the nearshore area using the delft3d and swan models resulting evolution was first compared with the available post storm profiles measured at a number of locations along the sefton coast analysis of the clustered and isolated simulations showed the effect of clustering on the sefton beach dune system when compared to the impact of isolated events occurring on a fully recovered beach system morphological change occurred during each storm in the cluster was influenced by the preceding storm s such that the evolution is not proportional to the storm power of the event as it would be for isolated events both storm cases resulted in heavy erosion at formby point i e central of the sefton coast and accretion in the north and south the cluster prevented system recovery with the area of erosion continually extending south along the coast compared with that in isolated events the initial storm within the cluster caused large bed level changes in the nearshore ridge runnel system enabling the subsequent storms to penetrate further south the local convex geometry of the sefton coast is found to have more influence on the beach dune morphodynamics than the clustering effect this study enhances the understanding beach dune response to storm clusters to interpret observed morphological changes and to develop tools for sustainable coastal management particularly in the sefton coast and generally in similar systems worldwide

the impact of temperate reefs on 34years of shoreline and vegetation line stability at yanchep southwestern australia and implications for coastal setback coastal setbacks are used to protect populations and infrastructure and involve determining baselines and historic trends in shoreline movements assessing these movements can be difficult on coasts with especially complex geomorphology such as due to rock and coral reefs reefs are often assumed to provide coastal protection and stability however little is known about the spatial variability of beach dynamics on beaches with reefs over inter annual and decadal time scales spatial variability in inter annual vegetation line and shoreline stability was assessed on three adjacent beaches at yanchep southwestern australia using 34 years 1974 2008 of aerial photographs over 96 of the study area beach width narrowed over the 34 years this trend was statistically significant on 83 of the middle beach 43 of the northern beach and only 29 of the southern beach the maximum mean annual change in beach width was 1 7 m yr 1 at the south end of the southern beach the first mode of the empirical orthogonal function eof explained 45 of the variability alongshore and correlated significantly p 0 05 with the 90th percentile of annual wave height and annual mean sea level beach rotation and reef controlled currents resulted in cellular beach morphodynamics and vegetation line and shoreline movements varied greatly alongshore on one occasion the beach widened by more than 50 m inter annually while other areas eroded by 50 m the southern beach that was fronted by the most continuous and highest supratidal section of reef was the most temporally variable even the vegetation line here moved by up to 20 m inter annually so cannot be assumed to be a stable baseline for setback the impact of reefs on inter annual shoreline and vegetation line stability should be considered in future guidelines for determining coastal setback

video observations and model predictions of depth induced wave dissipation time averaged video observations of the nearshore zone show the process of wave breaking as one or more white alongshore bands of high intensity corresponding to the preferential location of breaking wave dissipation on one or more sandbars across a known depth profile similar bands of dissipation can be predicted with existing wave transformation models based on the wave energy balance this opens up possibilities for estimating bathymetry from video observations by processing observed intensities into a model predicted proxy of wave dissipation and the inverse modeling of this dissipation proxy into depth the objectives of this paper are 1 to present a technique for processing time averaged cross shore image intensity profiles into profiles that solely contain the contribution due to wave breaking and 2 to empirically determine which modeled wave dissipation proxy relates best to the cross shore shape of the obtained breaking induced intensity the processing technique involves the removal of background illumination and noise and most importantly a correction for white foam that after being generated in the breaking process remains floating at the water surface this foam thus contributes to high image intensities but is not predicted by wave transformation models based on video and bathymetric data collected at the double barred beach at egmond aan zee the netherlands and a standard wave transformation model containing the wave and roller energy balances we find that the modeled cross shore distribution of the dissipation of the energy of the surface roller the white aerated mass of water at the breaking wave front matches the observed cross shore shape of breaking induced intensity well other hypothesized dissipation proxies result in a larger 10 m seaward bias in the locations of maximum breaking induced intensity and model predicted dissipation or do not predict the cross shore change in the area below the breaking induced intensity bands correctly

thresholds for morphological changes on an exposed sandy beach as a function of wave height a sandy beach in the south of portugal faro beach ria formosa was surveyed from the dune crest seaward to 15 m depth 20 times over a period of 26 months wave time series between surveys were analysed to obtain relationships between wave height and vertical profile variations and to define wave thresholds for important morphological changes results show that the active zone of the profile lies between 5 m above and 10 4 m below mean sea level and that there are clear cross shore differences in the vertical variability of the profile based on the pattern of vertical variability the profile was divided into four cross shore sectors a berm 20 80 m from the profile origin b sub tidal terrace 80 170 m c long shore bar 170 360 m and d 360 700 m the relationship between the modulus of the maximum vertical change in each sector and the 99th percentile of significant wave height between surveys was always significant calculated thresholds for significant wave height generating important morphological changes were 2 3 m in sector a 3 2 m in sectors b and c and 4 1 m in sector d copyright 2010 john wiley sons ltd

storm driven variability of the beach nearshore profile at duck north carolina usa 1981 1991 the us army corps of engineers field research facility frf at duck north carolina has collected approximately biweekly beach nearshore profile data to 8 m depth and associated wave data since 1981 sediment budget analysis was used to examine the medium scale years to a decade variability of the beach nearshore profile from 1981 to 1991 significant changes occurred during four groups of energetic storm events during february march of 1983 1987 1989 and december 1989 each group was comprised of at least two storms within a period of less than 39 days both with hmo 4 m during each storm group offshore sediment movement caused a distinct outer bar to migrate offshore and grow in size resulting in an abrupt increase in the volume of sediment on the upper shoreface the net profile changes were much larger than the changes due to single storms and the cumulative effect of the storms can be considered as one event during these events the first storm appears to have a destabilizing effect on the profile which has insufficient time to recover before the second and subsequent storm s as a result several storms in quick succession are able to have a large impact on the morphology the intervening periods between the groups of storm events termed fairweather conditions lasted up to 4 years they are characterized by slow but steady sediment redistribution averaging 33 m3 m 1 year 1 from the upper shoreface 5 m depth toward the shore while the total sediment volume was effectively constant the onshore feed of sediment was not significantly affected by individual storms during the fairweather conditions these two processes of 1 morphologic change during groups of storm events and 2 the steady onshore feed of sediments from the shoreface during fairweather conditions appear to play an important role on medium and long term profile evolution at least at duck

dynamics of single barred embayed beaches abstract the dynamics of single submerged sandbars of two artificial embayed beaches la barceloneta and bogatell barcelona nw mediterranean has been studied with a video recorded data set of 4 3 years the alongshore averaged cross shore migration the orientation with respect the shoreline and the sinuosity of the barlines have been analyzed and related to wave conditions alongshore sediment transport and shoreline variability in general the submerged bars follow the general cyclic morphological behaviour observed in natural beaches switching among the four intermediate morphodynamic states but the studied beaches can be arrested during long periods of low wave conditions the dominant up state transition in barcelona beaches during storms is the transition toward the rhythmic bar and beach state the complete morphodynamic reset longshore bar and trough state only occurring during extreme wave events the cross shore migration of bars is dominated by the weekly and interannual components the interannual component shows an onshore bar migration trend at both beaches in contrast with the net offshore migration observed in multibarred open beaches bar disposition is located progressively seaward in the dominant alongshore transport direction i e oblique with respect to the shoreline at la barceloneta beach shoreline and barline orientations change consistently and a significant correlation between the accumulated alongshore sediment transport and the associated change in bar orientation has been found suggesting that alongshore transport can play a significant role in barline orientation finally bar sinuosity increases during eastern storms in both beaches this indicates that the formation of crescentic bars occurs for approximately shore normal waves some of the differences observed in bar morphology and mobility in the two studied beaches are related to their different level of protection with respect to the incident waves beach indentation

storms and shoreline retreat in the southern gulf of st lawrence abstract storms play a major role in shoreline recession on transgressive coasts in the southern gulf of st lawrence gsl southeastern canada long term relative sea level rise off the north shore of prince edward island has averaged 0 3 m century over the past 6000 years 0 2 m century over 2000 years this has driven long term coastal retreat at mean rates 0 5 m a but the variance and details of coastal profile response remain poorly understood despite extensive sandy shores sediment supply is limited and sand is transferred landward into multidecadal to century scale storage in coastal dunes barrier washover deposits and flood tidal delta sinks charlottetown tide gauge records show mean relative sea level rise of 3 2 mm a 0 32 m century since 1911 a further rise of 0 7 0 4 m is projected over the next 100 years when differenced from tidal predictions the water level data provide a 90 year record of storm surge occurrence combined with wind wave hindcast and sea ice data this provides a catalogue of potentially significant coastal storms we also document coastal impacts from three recent storms of great severity in january and october 2000 and november 2001 digital photogrammetry 1935 1990 and shore zone surveys 1989 2001 show large spatial and temporal variance in coastal recession rates weakly correlated with the storm record in part because of wave suppression or coastal protection by sea ice large storms cause rapid erosion from which recovery depends in part on local sand supply but barrier volume may be conserved by washover deposition barrier shores with dunes show high longshore and interdecadal variance with extensive multidecadal healing of former inlet and overwash gaps this reflects recovery from an episode of widespread overwash prior to 1935 possibly initiated by intense storms or groups of storms in the latter half of the 19th century with evidence from the storms of 2000 2001 this points to the importance of storm clustering on scales of weeks to years in determining erosion vulnerability as well as the need for a long term large scale perspective in assessing coastal stability the expected acceleration in relative sea level rise together with projections of increasing storm intensity and greatly diminished winter ice cover in the southern gsl implies a significant increase in coastal erosion hazards in future

seasonal morphological response of an open sandy beach to winter wave conditions the example of biscarrosse beach sw france abstract 18 months of at least bi weekly topographic surveys have been conducted on a 700 m stretch of the meso to macro tidal biscarrosse beach france here we focus on the impact of the short term dynamics of the beach a few days on the seasonal winter response of the beach the beach was surveyed intensively during two winter seasons and the results indicate that despite similar pre winter morphology but very contrasting energy levels the first winter season being 1 7 times more energetic than the second winter season the sediment budgets over the two winter periods were very similar as well as the cross shore dynamics of the extracted proxies associated with the dune foot and the berm the data collected suggest that this may be explained by the sequence of erosion recovery events driven by hydrodynamic conditions as the water level and energetic conditions and sediment transport thus during the first winter post storm recovery was effectively driven by energetic conditions while during the second winter inter storm conditions did not allow the initiation of recovery in between the storms apart from the control from wave conditions the seasonal beach response is also discussed within the framework of storm chronology and tidal range

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

fifty years of coastal erosion and retrogressive thaw slump activity on herschel island southern beaufort sea yukon territory canada abstract patterns of coastal erosion in the arctic differ dramatically from those coasts in more temperate environments thick sea ice and shore fast ice limit wave based erosional processes to a brief open water season however despite this permafrost coasts containing massive ice ice wedges and ice bonded sediments tend to experience high rates of erosion these high rates of erosion reflect the combined thermal mechanical processes of thawing permafrost melting ground ice and wave action climate change in the arctic is expected to result in increased rates of coastal erosion due to warming permafrost increasing active layer depths and thermokarst rising sea levels reduction in sea ice extent and duration and increasing storm impacts with the most ice rich permafrost in the canadian arctic the southern beaufort sea coast between the tuktoyaktuk peninsula and the alaskan border is subject to high rates of erosion and retrogressive thaw slump activity under many climate change scenarios this area is also predicted to experience the greatest warming in the canadian arctic this paper presents results of a remote sensing study on the long term patterns of coastal erosion and retrogressive thaw slump activity for herschel island in the northern yukon territory using orthorectified airphotos from 1952 and 1970 and an ikonos image from 2000 corrected with control points collected by kinematic differential global positioning system and processed using softcopy photogrammetric tools mean coastal retreat rates of 0 61 m yr and 0 45 m yr were calculated for the periods 1952 1970 and 1970 2000 respectively the highest coastal retreat rates are on north west facing shorelines which correspond to the main direction of storm related wave attack during the period 1970 2000 coastal retreat rates for south to south east facing shorelines displayed a distinct increase even though these are the most sheltered orientations however south to south east facing shorelines correspond to the orientations where the highest densities of retrogressive thaw slumps are observed differences in rates of headwall retreat of retrogressive thaw slumps and coastal erosion results in the formation of larger thermokarst scars and the development of polycyclic thaw slumps on south to south east exposures the number and the total area of retrogressive thaw slumps increased by 125 and 160 respectively between 1952 and 2000 as well the proportion of active retrogressive thaw slumps increased dramatically polycyclic retrogressive thaw slumps appear to develop in a periodic fashion related to retrogressive thaw slump stage and maximum inland extent

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