morphodynamics along a micro tidal sea breeze dominated beach in the vicinity of coastal structures abstract the present study investigates the seasonal and interannual morphodynamics on a micro tidal sea breeze dominated tropical beach located in the northern yucatan peninsula mexico the coastal dynamics in the study area are controlled by both local sea breeze and synoptic central american cold surge cacs scale atmospheric events however the net westward littoral drift is dominated by more persistent sea breeze events the field study was conducted along a 2 km stretch of sandy beach located in the vicinity of two coastal structures one hundred beach surveys 2000 beach profiles were undertaken between may 2015 and june 2019 on a weekly and bi weekly basis to investigate beach morphodynamics empirical orthogonal function eof analysis of the morphological features are used to identify the dominant modes of beach variability the first and second spatial eof modes explain the beach long term trend and rotation respectively the first spatial mode is highly influenced by the presence of the structures for all morphological features the second spatial mode associated to beach rotation shows accretion erosion eastward westward of the structures during spring summer fall winter months field observations were employed to correlate the beach response with physical parameters i e water level and wave parameters the long term trend of the shoreline and subaerial volume show no significant correlations with the physical parameters whereas the temporal mode of the high water contour presents a step like behavior which is correlated to the still water level on the other hand beach rotation is highly correlated to the seasonal variability of wave parameters field observations suggest that increase of cacs events activity and water level during el nino 2015 2016 winter season enhanced decreased the beach rotation translation implying a high beach sensitivity to climate variability in this region

decoupling spatial and temporal patterns in short term beach shoreline response to wave climate this paper describes the use of a combined approach which merges numerical models and remote video techniques to derive the spatial and temporal patterns in short term beach shoreline forcing response to wave climate on a microtidal low energy sandy beach shorelines are obtained after applying an artificial neural network ann to daily raw video images the data comprise directional hydrodynamic conditions propagated from deep water to 10 m depth and video derived daily shorelines over the span of one year and a half the spatial and temporal variability of the beach is split by empirical orthogonal function eof decomposition time series exploration between eof and wave height shows a decoupling in spatial shoreline response to wave climate with a more immediate effect in cross shore sediment transport than in alongshore sediment transport the first eof which accounts for the cross shore variability is significantly correlated with wave height averaged for the previous four days while the second eof which explains the alongshore beach variability correlates with the averaged waves of the previous 7 days

rip spacing and persistence on an embayed beach 1 four years of daily time exposure images from an embayed beach were examined to study the spacing persistence and location preferences of rips in a natural rip channel system a total of 5271 rip channels was observed on 782 days occurrence statistics showed no evidence of the preferred location pattern associated with standing edge waves trapped in an embayed beach the histogram of rip spacing the primary diagnostic observable for most models was well modeled by a lognormal distribution mean spacing of 178 m however spacings were highly longshore variable time mean of the standard deviation longshore mean of rip spacing was 39 so they are of questionable merit as a diagnostic variable storm driven resets to the longshore uniform condition required by most models occurred only four times per year on average making rip generation models relevant to only a small fraction of the system behavior rip spacings after the 15 observed reset events were uncorrelated with bar crest distance the lifetime of the 324 individual rip channel trajectories averaged 45 6 days rips were equally mobile in both longshore directions but the coefficient of variation of rip migration rates was large even for high migration rates the mean migration rate was well correlated to a proxy for the longshore current r2 of 0 78 thus there is no significant evidence that the formation spacing and migration of rip channels on this beach can be explained by currently existing simple models moreover the alongshore uniform initial conditions assumed by these models are rare on palm beach making the models generally inapplicable

geologically constrained morphological variability and boundary effects on embayed beaches abstract headlands rock outcrops and engineering structures impact beach and nearshore dynamics of coastal embayments inducing boundary effects that constrain the lateral and vertical beach variability this study analyses morphological change in six embayed beaches with diverse levels of exposure to wave action and various degrees of geological control in the mesotidal coast of southwestern portugal the aim is to identify whether geological boundaries constrain the morphological behaviour of embayed beaches and assess whether their effects can be decoupled from datasets of morphological change topographic data obtained over a two year period on each of the six embayments were analysed using empirical orthogonal functions eof to decompose temporal and spatial variability in the datasets first and second mode eigenfunctions were explored using time variable linear correlation analysis with several nearshore parameters that include hydrodynamic variables sedimentary and geometric characteristics of each embayment in order to derive forcing response relationships our results demonstrate that natural geological boundaries constrain the morphological behaviour of embayed beaches producing conspicuous alongshore variability in all embayments localised responses induced by lateral and vertical boundary interference with beach and nearshore dynamics include beach rotation topographically controlled rip circulation and restrained profile fluctuation spatial decoupling in cross and longshore responses is accompanied by a temporal decoupling in response times both of which are slower in more constrained embayments from 1 day in exposed embayments to 1 week or more in the most sheltered ones normalised wave power was correlated at the 99 confidence level with the primary mode of morphological variability at most embayments which represent 67 to 94 of the variance in the datasets this correlation stresses the importance of combined parameterization of wave and tide forcing in process response relations between hydrodynamics and morphological change for mesotidal coastal environments lateral and vertical geological boundaries exert their effects fundamentally by restraining longshore sediment transport inducing cellular surf zone circulation and by impacting cross shore sediment transport it is postulated that decreasing sediment abundance and substrate depth intensify vertical boundary effects while higher indentation and wave obliquity enhance the effects of lateral boundaries

daily morphological changes determined by high energy events on an embayed beach a qualitative model this paper examines the daily morphological responses of sununga beach an embayed beach located on the south eastern brazilian coast to storms in the south atlantic ocean the main mechanisms and timing of beach erosion and accretion the relationship between wave height and direction and beach volume changes are considered to establish a qualitative model for short term embayed beach morphological changes the methodology consisted of daily topographic surveys during the month of may in 2001 2002 and 2003 using an rtk gps real time kinematics global positioning system weather and wave model results were used to correlate hydrodynamics and beach morphology the results indicate that the morphodynamics of sununga beach are characterized by a process of beach rotation which occurred more or less clearly during all three surveys unlike what has been commonly described in the literature for longer time intervals and alternations of fair and stormy weather the beach rotation processes on sununga beach occurred under conditions of moderate to high wave energy change wave heights greater than 2 m an integrated evaluation of the behaviour of the meteorological aspects together with beach morphology enabled us to recognize that extra tropical cyclones were the most important agent in remobilizing the beach planform whether in beach rotation or in cross shore erosion copyright 2010 john wiley sons ltd

dynamics of the douro estuary sand spit before and after breakwater construction abstract the douro estuary sand spit nw portugal is an important natural defence against the impact of storm events aiming to improve navigation safety a breakwater was built to stabilise the spit in 2001 a monitoring programme was set up to understand the dynamics of the sand spit and later to evaluate breakwater efficiency on stabilising the spit s shape and volume nine years of periodic accurate 3d digital elevation models obtained from kinematic differential global positioning system surveys were used to assess spatial and temporal changes in the spit morphology before and after the breakwater construction temporal and spatial spit dynamics were further related to river discharge flows wave action and wind energy although the breakwater had a stabilising effect on most of the spit s area and volume it caused a clear change in the morphology of the spit s head and in the previously observed patterns of erosion and accretion before breakwater construction erosion was significantly correlated with extreme river discharge and wind conditions accretion was significantly correlated with extreme wind conditions and spit area and volume at 1 2 m elevation with extreme wave conditions after breakwater construction these correlations were not found but the eastern inland face of the spit and particularly its southern part became more susceptible to the observed extreme river discharge flows wave and wind conditions the instability in the se part of the spit may pose a threat to an existing local nature reserve furthermore before breakwater construction the spit often breached during severe floods favouring river discharges the strengthening of the spit after breakwater construction may reduce the likelihood of breaching and lead to more severe flood effects in the estuary

the southern oscillation index wave climate and beach rotation short embayed beaches bounded by headlands are a common feature along the southern and central coastline of new south wales australia many of these embayed beaches have experienced severe erosion at their southern end over the last decade previous studies have suggested that this erosion may be the result of an oscillatory medium term phenomenon known as beach rotation the present study was undertaken with the objectives of 1 establishing definitive links between the southern oscillation index soi wave climate and beach rotation and 2 determining the physical processes governing beach rotation data from two similar new south wales beaches were analysed using time series analysis techniques and image processing techniques using argus video images in this study the results indicate that the northern end of this type of beach accretes during el nino phases while the southern end erodes resulting in a net clockwise rotation of the beach the opposite occurs during la nina phases resulting in a net anti clockwise rotation of the beach the beach response at the northern and southern ends lags soi trend shifts by 3 and 17 months respectively waves are predominantly incident from the southeast during both el nino and la nina phases offshore wave height is positively correlated with the soi while offshore wave direction is negatively correlated with the soi on average the number of storms per year doubles from el nino to la nina based on these links between beach width fluctuations soi and incident wave conditions a conceptual model of beach rotation is presented the model describes the combinations of cross shore and longshore sediment transport and hydrodynamic processes that are expected to result in the observed clockwise and anti clockwise beach rotation during el nino and la nina phases respectively

generalities on static equilibrium bays abstract previous methods of determining the curved waterlines of bays which form on the coasts around the world have involved the logarithmic spiral this has been applied to unstable bays which could erode back to a limit termed static equilibrium for which the constant in the spiral could be related to the obliquity of the wave crests to the control line joining the upcoast headland to the downcoast extremity of the bay it is shown that this applies mainly to the shadow zone behind the upcoast headland and not to the full bay periphery and does not have a fixed centre a new method is proposed utilising arcs from the point of wave diffraction to the shoreline whose lengths and angles to the wave crest line are related to those of the control line data and curves are presented for the static equilibrium shape by which the stability can be tested they thus predict the waterline for the case of no sediment supply either from littoral drift or rivers debouching into the bay an indentation ratio can also be derived to test stability

a rare landform yerkopru travertine bridges in the taurids karst range turkey two examples of travertine bridges are observed at 8 to 15 m above stream level in the lower zamanti basin eastern taurids turkey yerkopru 1 and yerkopru 2 bridges are currently being deposited from cool karstic groundwaters with log pco2 10 2 atm the surface area and the total volume of travertine in yerkopru 1 bridge are 4350 m2 and 40 000 m3 whereas the values for yerkopru 2 are 2250 m2 and 20 000 m3 respectively the interplay of hydrogeological structure local topography calcite saturated hanging springs algal activity and rapid downcutting in the streambed appear to have led to the formation of travertine bridges aeration through cascades and algal uptake causes efficient carbon dioxide evasion that enhances travertine formation algal curtains aid lateral development of travertine rims across the stream model calculations based on a hypothetical deposit in the form of a half pyramid implied that lateral development should have occurred from both banks of the stream in the yerkopru 1 bridge whereas one sided growth has been sufficient for yerkopru 2 the height difference between travertine springs and the main stream appears to be a result of pleistocene glaciation during which karstic base level lowering was either stopped or slowed down while downcutting in the main stream continued copyright 2002 john wiley sons ltd

a video based technique for mapping intertidal beach bathymetry abstract measuring the location of the shoreline and monitoring foreshore changes through time are core tasks carried out by coastal engineers for a wide range of research monitoring and design applications with the advent of digital imaging technology shore based video systems provide continuous and automated data collection encompassing a much greater range of time and spatial scales than were previously possible using field survey methods a new video based technique is presented that utilises full colour image information which overcomes problems associated with previous grey scale methods which work well at steep reflective sites but are less successful at flatter dissipative sites identification of the shoreline feature is achieved by the automated clustering of sub aqueous and sub aerial pixels in hue saturation value hsv colour space and applying an objective discriminator function to define their boundary i e shoreline within a time series of consecutive geo referenced images the elevation corresponding to the detected shoreline features is calculated on the basis of concurrent tide and wave information which is incorporated in a model that combines the effects of wave set up and swash at both incident and infragravity frequencies validation of the technique is achieved by comparison with dgps survey results to assess the accuracy of the detection and elevation methods both separately and together the uncertainties associated with the two sub components of the model tend to compensate for each other the mean difference between image based and surveyed shoreline elevations was less than 15 cm along 85 of the 2 km study region which corresponded to an horizontal offset of 6 m the application of the intertidal bathymetry mapping technique in support of czm objectives is briefly illustrated at two sites in the netherlands and australia

rapid erosion of soft sediments by tidewater glacier advance taku glacier alaska usa 2 0 0 1 m a 1 1940 2005 at l 3 km h 350 m and 1 5 0 2 m a 1 1952 2005 at l 1 5 km h 250 m detailed mapping over a 4 km 2 area of the terminus revealed a deeply incised channel in line with a major outlet stream glaciofluvial processes must play the dominant role in the subglacial erosion and removal of these unlithified sediments citation motyka r j m truffer e m kuriger and a k bucki 2006 rapid erosion of soft sediments by tidewater glacier advance taku glacier alaska usa geophys res lett 33 l24504 doi 10 1029 2006gl028467

short term changes in the plan shape of a sandy beach in response to sheltering by a nearshore mud bank cayenne french guiana montjoly is a headland bound embayed sandy beach in cayenne french guiana that shows long term plan shape equilibrium in spite of periodic changes in accretion and erosion that alternately affect either end of the beach these changes are caused by mud banks that move alongshore from the amazon the mechanisms involved in changes in the plan shape of the beach in response to the passage of one of these mud banks were monitored between 1997 and 2000 from airborne video imagery and field work the beach longshore drift to the northwest driven by the incident easterly to northeasterly swell usually affecting this coast became temporarily reversed as the mud bank migrating from east to west initially sheltered the southeastern end of the beach the difference in exposure to waves engendered a negative wave height gradient alongshore towards the southeast resulting in the setting up of a cell circulation and counter active longshore drift from the exposed northwestern sector to the southeast sand eroded from the exposed sector accumulated first in the southeastern and then the central sectors of the beach the effect of increasing beach sheltering by the mudbank moving west is highlighted on the videographs by an arrested pattern of beach shoreline development the videographs show hardly any changes in beach plan shape since january 1999 due to sheltering of the beach from wave attack by the mud bank it is expected that the eroded sector will recover in the future as the mud bank passes leading to re establishment of the northwesterly sand drift this temporally phased bi directional drift within the confines of the bounding headlands results in a rare example of mud bank induced beach rotation and probably explains the long term equilibrium plan shape of montjoly beach copyright 2002 john wiley sons ltd

morphological changes beach inundation and overwash caused by an extreme storm on a low lying embayed beach bounded by a dune system nw mediterranean abstract the geomorphological evolution of a low lying micro tidal sandy beach in the western mediterranean pals beach was characterized using airborne light detection and ranging lidar data data were collected in prior to and six months after the impact of an extreme storm with a return period of approx 50 years with the aim of characterizing the beach s response to the storm the use of repeated high resolution topographic data to quantify beach geomorphic changes has allowed assessment of the accuracy of different proxies for estimating beach volume changes results revealed that changes in the shoreline position cannot accurately reproduce beach volume changes on low lying beaches where overwash processes are significant observations also suggested that volume estimations from beach profiles do not accurately represent subaerial volume changes at large profile distances on beaches with significant alongshore geomorphological variability accordingly the segmentation of the beach into regularly spaced bins is proposed to assess alongshore variations in the beach volume with the accuracy of the topographic data the morphological evolution of pals beach during the study period showed a net shoreline retreat 4 m and a significant sediment gain on the subaerial beach 7 5 m 3 m the net gain of sediment is mostly due to the impact of the extreme storm driving significant overwash processes that transport sediment landwards increasing volume on the backshore and dunes the increase of volume on the foreshore and the presence of cuspate morphologies along the shoreline also evidence post storm beach recovery observed morphological changes exhibit a high variability along the beach related to variations in beach morphology changes in the morphology and migration of megacusps result in a high variability in the shoreline position and foreshore volume changes on the other hand larger morphological changes on the backshore and larger inundation distances occur when the beach and the dunes are lower favouring the dominance of overwash the observed storm induced morphological changes differ from predicted beach storm impacts because of spatial and temporal variations in the beach morphology suggesting that detailed morphological parameters and indicators used for predicting beach vulnerability to storms should be regularly updated in order to represent the pre storm beach conditions finally observed morphological changes in pals bay evidenced a different behaviour between natural and urban areas with better post storm beach recovery on natural areas where the beach is not artificially narrowed

analysis of the effects of different storm events on shoreline dynamics of an artificially embayed beach a five year dataset of argus derived mean intertidal positions has been analysed to characterize the shoreface variability in a beach protected by a system of groynes and a parallel low crested structure lido di dante ravenna italy for the period 2004 2009 84 intertidal beach bathymetries and shorelines at the zero sea level were used as indicators to assess beach changes in between a number of selected surveys and to determine characteristic patterns of the beach response to storm events from different directions variations in the shoreline at the zero sea levels have been quantified and analysed in conjunction with nearshore wave conditions and provenance linked to storm events these fall into two categories 1 storm events occurring during bora north eastern wind conditions and 2 storm events occurring during scirocco south eastern wind conditions the results show that apart from main beach advances of the whole protected beach due to nourishments periodically carried out a marked variability is observed among the four sub cells into which the shoreface behaviour has been separately analysed in particular a dependence of beach rotation in the artificially embayed area on the substantially bi directional wave climate has been shown bora and scirocco storm events produce shoreline rotation in counterclockwise and clockwise directions respectively due to the occurrence of longshore currents in the opposite direction in the nearshore an attempt was made to correlate the shoreface dynamics for the main rotation events 14 selected ones to the wave attack intensity as the total energy flux due to storm events a relationship seems to occur for each storm category between the shoreline displacements estimated for each sub cell and the total energy flux computed for inter survey periods supporting the occurrence of a link between the observed morphological changes and the hydrodynamic forcing associated with storm events in the five year monitoring period copyright 2011 john wiley sons ltd

shoreline dynamics and beach rotation of artificial embayed beaches abstract artificially embayed beaches are an increasingly common environment in retreating and urban coasts the study of embayed beaches usually focuses on the concept of some equilibrium configuration of the shoreline caused by the wave approach and the location of protection structures but detailed studies of their shoreline dynamics are scarce the study reported herein monitored the shoreline dynamics of three artificial embayed beaches in barcelona city during a three year period using an argus video system to examine the behaviour of the emerged beach in order to assess the main factors affecting the shoreline and to analyze the processes causing beach rotation at different time scales the length and degree of protection of the three beaches were different and so were their morphological behaviours two of the beaches presented a general retreating trend with rapid abrupt displacements of the shoreline caused by oblique wave incidence during storm events and to the effects of beach nourishment after nourishment slower changes at the beaches determined beach evolution which was also influenced by the formation of long lasting megacusps the third beach the most protected one showed an accretionary trend no formation of megacusps and episodes of beach rotation related to the gradual recovery of the beach after storm events it is concluded that factors controlling the evolution of barcelona city beaches are associated with both natural processes and man induced actions resulting in a more complex pattern than would be expected for small embayed beaches beach rotation appears as a key process for understanding the morphodynamics of embayed beaches it occurs as a fast response to storms but also as a medium term adaptation of the shoreline configuration to morphological changes in the beach or to the recovery of a more stable orientation after storm events and man made changes in the beach orientation resulting from nourishment or sand relocation

an equilibrium model to predict shoreline rotation of pocket beaches a novel and simple beach evolution model for estimating shoreline rotation at sandy pocket beaches is presented the model is based on the assumption that the instantaneous changes to the planview shape of the shoreline depend on the long term equilibrium planview shape two years of shoreline observations extracted from video images of three artificially embayed beaches of barcelona and hourly wave timeseries are used to validate the model numerical model results and field observations show an excellent agreement with an rmse less than 1 5 m the model successfully reproduced the shoreline response over a range of scales months and years because of its simplicity and its computational efficiency the model provides a powerful tool to understand the dynamics regulating the evolution of pocket beaches and predict temporal patterns in beach rotation

morphological response to storms in an embayed beach having limited sediment thickness abstract the morphological response of a wave dominated embayed beach to large storms was investigated via field data collection and numerical simulation hydrodynamic and morphological field data collected in haeundae beach facing sse in the south eastern corner of korea were analysed during the southerly storm waves i e almost shore normal direction the upper part sediments of the beach were eroded and redistributed to the surf zone meanwhile easterly storm waves transported sediment from east to west resulting in coastline advancement in the west and retreat in the east in order to investigate the morphological response of the beach with limited sediment availability under storm conditions the numerical model xbeach was used with the assumption of unlimited sediment availability the southerly storms led to overestimation of sediment transports and unrealistic erosion and deposition patterns in the middle part of the beach in contrast the model results with the option of sediment layer thickness showed good agreement with the erosion and deposition patterns analysed from field data this suggests that sediment availability can be one of the key factors in determining the morphological response in a wave dominated embayed beach where sediment supply from neighbouring beaches or rivers is limited

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

observations of shoreline sandbar coupling on an embayed beach we analyse a seven year dataset 1999 2005 of shoreline and sandbar variations derived from video observations at the embayed tairua beach new zealand to explore sandbar shoreline coupling and to determine how this coupling is related to alongshore averaged sandbar shoreline separation and beach rotation our results quantify the coupling between the sandbar and the shoreline which is directly related to the reduced separation between the sandbar and the shoreline using a simple predictive shoreline model we show that this behaviour is related to the energy of the incoming waves our observations are obtained from a headland enclosed beach and show aspects of the morphological state that relate to the existence of headlands that are not considered in the wright and short beach state classification both the sandbar and shoreline at tairua beach rotate relatively quickly 1 month during the winter storm events when the storms are accompanied by strong alongshore components gradually returning during the summer months the sandbar shoreline coupling length scale is controlled by this rotation with large wavelengths occurring when the sandbar is strongly rotated

a shoreline evolution model considering the temporal variability of the beach profile sediment volume sediment gain loss abstract the prediction of shoreline variability along sandy coastlines is a valuable skill for a broad range of coastal engineering applications currently there are multiple proposals in the literature for equilibrium cross shore shoreline evolution models based on a constant equilibrium condition correlated with the shoreline position the aim of this paper is to present an extension of an existing equilibrium shoreline evolution model adding a rate of change component which in turn modifies the relationship between the equilibrium shoreline position and the incident wave energy as a function that advances or retreats over time the proposed model is applied to two study sites on the spanish coast on the one hand one and a half years of shoreline position data obtained from a video camera system at nova icaria beach catalonia are used to evaluate the shoreline evolution during a period of sediment contribution which is attributed to a sand bypass coming from bogatell beach on the other hand 16 years of shoreline position data acquired from beach profile surveys in campo poseidon huelva are used to reproduce the shoreline evolution taking into account the trend of sediment loss due to sediment drift alongshore the results obtained from both study sites using the proposed model show overall good performance the model successfully represents the general shoreline erosion accretion oscillations and the progressive trend of sediment gains or losses through the evolutionary relationship between the equilibrium shoreline position and the incident wave energy

intertidal beach change during storm conditions egmond the netherlands abstract the processes responsible for sediment transport and morphological change in the intertidal zone of natural beaches are not well known consequently factors determining whether the intertidal beach erodes accretes or remains stable in the face of significant wave impact and the mechanisms behind the elusive concept of equilibrium beach slope are poorly understood a field experiment was designed to measure suspended sediment transport in the swash and inner surf zone through successive tidal cycles in the intertidal zone at egmond beach the netherlands using a stack of fiberoptic backscatter sensors ufobs 7 the experimental period comprised three large storm events including an extreme storm with offshore significant wave heights in excess of 7 m surveys spanning a 1 km long section of the beach as well as observations from an argus video camera system showed that gently sloping shoreline salients megacusps were highly stable in position and displayed only minor slope adjustments through the storm period whereas steeply sloping embayments were eroded significantly the sediment transport measurements at a shoreline salient indicated that the subdued net beach response was because offshore sediment transport occurring under surf zone conditions at high tide was compensated by onshore sediment transport at low tide when swash zone processes dominated such temporally varying tidally modulated sediment transport rates and directions are suggested to be able to maintain a quasi equilibrium intertidal beach slope and the results indicate that a negative feedback existed between initial beach slope and net sediment transport patterns

medium timescale beach rotation gale climate and offshore island influences abstract beach profile surveys gale climate and atmospheric variations were utilized to assess medium timescale morphological change at south sands tenby west wales due to beach aspect in relation to offshore islands gale wave height decreased as wave direction rotated eastwards r 0 83 and westwards r 0 88 similarly wave heights were in attuned to variations in positive r 0 68 and negative r 0 72 nao index showing a wave height reduction occurred during weakly negative positive or transitory phases morphological change was attuned to atmospheric variation at a 2 year timelag shelter from offshore islands is given to waves from the predominant southwesterly direction and was confirmed by negligible correlation with south sands morphology however outside the shelter of these offshore islands correlation was found between south eastward rotating wave directions 135 180 and morphological change which resulted in southern and central beach erosion and accretion to the north with a southwesterly rotation 243 256 the opposite was true beach rotation expressed by volume change within the sub aerial zone had a negative phased relationship between beach extremities r 0 94 and a timelagged association within the intertidal zone r 0 55 analyses resulted in the development of two medium timescale rotation models based on incident wave direction and climatic variability results have global implications for headland bays in the lee of offshore islands as well as macro tidal beach areas and consequently similar models could inform local regional and national beach management strategies

planview geometry and morphological characteristics of pocket beaches on the catalan coast spain abstract coastal planform studies are a relevant initial stage before launching detailed dynamic field experiments the aim of this study is to define the planform characteristics of 72 catalan pocket beaches natural and man made and to determine their sheltering effect embaymentization and their status of equilibrium planform measurements were performed on sigpac 1 5000 orthophoto sets and wave climate was provided by puertos del estado wana model planform parameters were applied and coastal planview indexes were determined the study shows that the catalan pocket beaches display a wide range of indentation suggesting that no single structural tectonic or morphological control dominates their planform the man made pocket beaches typically display indentations which are smaller than those shown by natural pocket beaches headland spacing and beach area are positively correlated the more indented bays are the shorter their beaches become low indented pocket beaches are the widest and the longest ones deep indentation contributes towards beach protection and energy dissipation which counteracts rip efficiency and inhibits the formation of mega rips pocket beaches often show gradual and moderate alongshore changes in texture and beach morphology one third of the catalan pocket beaches are sediment starved i e 60 and more of their embayed shorelines are deprived of beach sediments examination of the status of equilibrium demonstrates that most of the catalan pocket beaches are in an unstable mode with indentation ratios that are unrelated to the wave obliquity

natural variability of shoreline position observations at three pocket beaches we investigated the variability of shoreline position of three adjacent pocket beaches at barcelona city nw mediterranean over a period of two years daily measurements of shoreline position were extracted from high resolution video images and used to determine shoreline variability using empirical orthogonal function analysis we determine two dominant modes of shoreline variability for all beaches analysed the mode that explains most of the variability around 70 describes the beach plan form rotation which primarily occurs at the seasonal scale the cross shore translation of the beach profile is described by the 2nd mode which explains around 30 both types of shoreline movement have been related to the previous nearshore conditions this relationship was explored standardizing the translation rotation of the shoreline and comparing it with time averages of the cross shore energy flux efcsh and the energy flux direction efd averages over 7 to 12 days of efcsh were significantly correlated to the translation movement plan form rotation was well described by 28 to 40 day averaging of efd comparing results from the three beaches we determined that the time required to average the previous wave conditions depends on the beach characteristics beach length and sediment grain size in such a way that the greater the length of the beach and its sediment grain size the slower its response

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

a reevaluation of coastal embayment rotation the dominance of cross shore versus alongshore sediment transport processes collaroy narrabeen beach southeast australia 1 over 30 years of wave and beach survey data at collaroy narrabeen beach in southeast australia are analyzed to investigate the extent to which shoreline variability within this coastal embayment is dominated by shoreline oscillations due to cross shore sediment exchange or shoreline rotations due to alongshore exchange between the beach s extremities offshore wave data are derived from both buoy measurements and era 40 reanalysis data eof analysis of the monthly shoreline data suggests that the dominant mode of shoreline variability 60 of variability is an onshore offshore sediment exchange that is greater at the more exposed northern end of the beach than at the predominantly sheltered southern end this mode is primarily associated with variability in wave energy storms which by the nature of the wave climate of this region chiefly occurs from the south southeast the secondary mode of shoreline variability 26 of variability is a rotational signal between either end of the beach which coincides with 24 of the offshore wave climate shifting between the south southeast and east as well as changes in the wave period and wave energy storms a distinct annual cycle is identified in this rotation signal it is concluded that alongshore sediment transport processes associated with embayment rotation is more subtle than previously thought and a refined conceptual model of coastal embayment variability in this region is presented highlighting the dominance of cross shore sediment exchange processes

on the application of static equilibrium bay formulations to natural and man made beaches crenulate shaped bays are common features found all around the world the most widely used formulation for representing this kind of bay is the parabolic approach proposed by hsu and evans institution of civil engineers proc london england 87 1989 556 who suggested a methodology to test and predict the stability of static equilibrium shapes in natural and man made bays based on an analytical model of null drift current and using an empirical approach a modified methodology is proposed the new procedure is able to locate the downcoast starting point of the static equilibrium beach from which the parabolic plan form of hsu and evans is valid this methodology is applied with good results to different natural and man made beaches along the atlantic and mediterranean coasts of spain including tombolo shaped beaches

shoreline evolution in an embayed beach adjacent to tidal inlet the impact of anthropogenic activities abstract embayed beaches are widely distributed around the world their shoreline evolution is controlled primarily by the upstream headland and prevailing wave conditions tidal inlets are also ubiquitous in sandy coasts they are quite dynamic and act as a sediment source or sink depending on the sediment transport pattern and budget an embayed beach may develop downstream of a tidal inlet if a protruding headland is formed at the inlet owing to either natural processes or human construction in this study gaolong bay located downstream of a tidal inlet qinglan inlet in wenchang city hainan island china is used as an example to examine the effects of an upstream tidal inlet on the evolution of an embayed beach emphasis is placed on the impact of anthropogenic activities such as landfilling and jetty construction historical remote sensing data were collected and the evolution of the shoreline from 1998 to 2018 was analyzed the shoreline change pattern in gaolong bay was identified with the empirical orthogonal function eof method and the mechanisms behind these changes were explored with a coupled current wave sediment transport modeling system our results indicate that the construction of an artificial peninsula and a jetty beside the inlet channel dramatically changed the evolution of the gaolong bay shoreline defying the classical expectation of shoreline retreat downdrift of a tidal inlet a clockwise shoreline rotation was prevalent in gaolong bay with the shadow zone accreting and the distal zone retreating along with an overall shoreline propagation translation the static equilibrium shoreline planform model model of equilibrium of bay beaches mepbay was further used to predict the future evolution of the shoreline this study demonstrates that an embayed beach downdrift of a tidal inlet can exhibit a complex response to human interventions at the inlet and highlights the necessity of considering adjacent shoreline changes when assessing the impact of inlet stabilization

sediment transport along an artificial shoreline the strand townsville ne queensland australia construction measures to stabilise or spatially extend coastlines have become a routine measure in urbanised coastal zones this study quantifies beach profile changes and sediment transport along an artificial beach in townsville ne queensland the strand was transformed from a single degraded shoreline into a shoreline with five embayments or pocket beaches split by four artificial rocky headlands in 1998 the modified shoreline has had an impact on the local and regional northward long shore sediment pathway creating local shifts in sand sediment deposition and erosion occur at the same time at different parts of the pocket beaches collected offshore sediments show that little artificial sand is transported more than a few meters seaward in the south eastern part of the strand while substantial and long ranging export i e tens to hundreds of meters occurs in the north western area this is mainly the result of the breakwaters south of the strand which impacts the predominant northward long shore sediment transport induced by the dominant south easterly winds

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

seagrass berm deposition on a mediterranean embayed beach abstract seagrass leaf litter is commonly found along shores all around the world the mediterranean sea is not an exception and along the sandy shore wide and thick deposits of leaf litter can be found the deposition of these structures has not yet been studied our aim is to clarify the depositional erosive process of seagrass leaf litter on a mediterranean beach a video image system consisting of a camera and a video camera was used to investigate the dynamics of the deposition of seagrass litter on beaches time exposure images proved useful in investigating the seagrass berm deposition over the monitored period by using the eof analysis while videos are used to describe every deposition and erosion cycle the deposition of seagrass berms occurred from late october to early april while during the rest of the year the beach was free of litter the first deposition occurred in october when seagrass litter was available on the submerged bay domain the seagrass berm erosion occurred after several peaks of wind speed while the deposition started when the wind speed increases and the waves start to break near to the shoreline the deposition of the leaf litter on the beach starts as a strandline at the landward edge of the wave action and proceeds seaward up to the shoreline litter residue eroded away by the waves and floating in the inner surf zone can be redeposited in little patches at the end of an erosion cycle in conclusion leaf litter may be relevant to berm formation and litter floating in the inner surf zone and in the lower swash zone is part of the materials exchanged between submerged and emerged beach

annual and interannual changes on a reef fringed pocket beach kailua bay hawaii abstract historical aerial photographs and topographic survey sheets are used to establish a 70 year shoreline history 1926 1996 for kailua beach oahu hawaiian islands the shoreline has migrated seaward over this period at an average rate of 0 5 m yr with a maximum net accretion along the beach of 58 7 m and a maximum net erosion of 13 2 m net accretion has taken place even while sea levels have risen on the order of 0 1 m semi annual and monthly beach profile surveys 1995 1999 at seven transects reveal short term variations of shoreline position sand volume and beach shape a relationship between beach width and corresponding sand volume fluctuations established from the beach profile data is applied to the historical shoreline change data to establish a history of sand volume fluctuations results show that kailua has experienced a net accretion of 673 000 m3 of sand over the period 1926 1996 with average annual rates of volume change varying between 6 8 m3 m yr and 0 1 m3 m yr the most recent period 1989 1996 shows a net volume increase of 41 000 m3 given the lack of sand inputs at the ends of the beach exchange with offshore deposits is a likely mechanism for long term accretional trends seasonal fluctuations in kailua beach morphology dominate the variability with a response to seasonal wave state that varies along the length of the beach in magnitude and sign at least four alongshore zones are observed with the first and third zones exhibiting high low sand volumes during the summer winter and the second and fourth zones exhibiting opposite behavior with high low volumes during the winter summer although seasonal sand accumulation varies along the beach the overall beach profile is largely maintained moreover changes in sand volume occur in phase over the subaqueous and subaerial sections of the beach this behavior suggests that longshore rather than cross shore sand transport is important at annual time scales a simple seasonal transport pattern is proposed to account for these observed fluctuations which depends in part on the topography of the offshore reef

distribution and sources of organic matter in size fractionated nearshore sediments off the barcelona city nw mediterranean abstract continental shelves are recognized to play a key role in the biogeochemical cycle of carbon linking terrestrial and marine carbon reservoirs in this study we investigate the physical and biogeochemical processes that control the source transport and fate of organic carbon oc in the continental shelf off barcelona city in the nw mediterranean sea surface sediment samples were collected from depths of 10 40 m during late summer and autumn 2012 grain size and biogeochemical parameters such as oc its stable isotope 13 c total nitrogen tn and oc tn ratios were analysed in size fractionated sediments the influence of environmental factors over the study area was determined using hydrological and oceanographic time series together with video images of the barcelona coast line and nearshore region we have found a wide range of oc contents from 0 13 to 8 68 depending on water depth and sediment particle size the highest oc concentration was always found in the clay fraction 63 m that contained terrestrial plant debris wave activity discharge of the besos river and the espigo de ginebra outfall were the main mechanisms controlling the sorting of sediments by their grain size and thus the distribution of oc in the inner shelf off barcelona in addition we observed that the organic matter in clay particles was progressively degraded seawards probably because these particles remain suspended in the water column much more time compared to those that are heavier and therefore they are exposed for longer time periods to oxygenated conditions both oc tn ratios and 13 c values found suggest that the organic matter preserved was predominantly land supplied

rocky coasts their role as depositional environments abstract the role of rocky coasts as depositional environments has been generally neglected by rock and depositional coast workers although rock coasts can be hostile sedimentary environments they frequently host a variety of deposits consisting of mixes of boulders and megaclasts to sand and cobbles these deposits include pockets of sand and pebble trapped in topographic depressions or at the foot of scarps and cliffs isolated boulders pocket beaches trapped between headlands and sand to boulder beaches in shallow bays exposed to strong wave action the tectonic setting which is reflected in the degree of geological heterogeneity alongshore together with the wave regime and other elements of the morphogenic environment help to determine the amount and mobility of the sediment and consequently whether it plays an essentially abrasional or protectional role many beaches have a resistant rock foundation which will modulate their response to rising sea level and possibly increased storminess during this century wave refraction and temporal and spatial changes in sediment abrasional and protectional efficacy influence the development of crenulated planforms on coasts with a high degree of geological heterogeneity and possibly on more geologically homogeneous coasts with longshore variations in cliff height or in the amount of sediment theory suggests that these coasts may develop equilibrium planforms with uniform rates of erosion in bays and on headlands or they may undergo a series of cyclical transformations involving alternating increases and decreases in the depth of the bays relative to the headlands