prediction of cross shore sediment transport at different spatial and temporal scales abstract coastal sediment transport and associated morphological change can be examined at many spatial and temporal scales these scales range from instantaneous movement of single grains on a time scale of the local turbulence to seasonal and long term movement of large sand bodies such as longshore bars and tidal deltas researchers have begun to recognize that a first principles microscale approach to calculating long term and large scale megascale coastal change may not be possible or even adequate therefore new approaches are being sought to advance quantitative understanding and prediction of large scale coastal behavior the present paper opens with a discussion of compatible spatial and temporal scales for calculating sediment transport and morphology change motivation is given for the need to calculate morphologic change at scales greater than the typical one of microscale example calculations are made at different scales showing the assumptions and approximations of each the main conclusion is that calculations at different scales can be related and reconciled if limitations in prediction of initial and boundary conditions and in the fluid forcing are recognized

overtopping a truncated planar beach run up on a truncated impermeable beach is analysed theoretically and experimentally to find the volume of fluid associated with a single wave event that flows over the end of the beach the theoretical calculations investigate the motion using the shallow water equations and the fluid is allowed to flow freely over the end of the beach two models of wave events are considered dam break initial conditions in which fluid collapses from rest to run up and overtop the beach and a waveform that models swash associated with the collapse of a long solitary bore the calculations are made using quasi analytical techniques following the hodograph transformation of the governing equations they yield predictions for the volume of fluid per unit width that overtops the beach primarily as a function of the dimensionless length of the beach these predictions are often far in excess of previous theoretical calculations new experimental results are also reported in which the overtopping volumes due to flows initiated from dam break conditions are studied for a range of reservoir lengths and heights and for a range of lengths and inclinations of the beach without the need for any empirically fitted parameters good agreement is found between the experimental measurements and the theoretical predictions in regimes for which the effects of drag are negligible

beach cusp morphodynamics detailed measurements of three dimensional beach cusp morphology were made on a steep gradient low energy microtidal beach in perth western australia during the field campaign a variety of wave conditions and tidal ranges were experienced and these differing hydrodynamic conditions were reflected in a consistent pattern of morphological changes to the beach cusp system a useful parameter to delineate between trends of cusp destruction and re formation appeared to be the surf similarity parameter tan i0 l0 where h0 is offshore wave height l0 is deep water wave length and tan is beach gradient for 1 2 a small storm was experienced at the start of the field campaign period and resulted in considerable erosion of the beach face the cusp morphology across the lower beachface was destroyed but a subtle remnant of the pre storm cusp morphology was preserved on the upper beachface when cusps reformed after the storm under the influence of declining wave conditions they appeared at the same location and with the same dimensions as the pre storm cusp morphology hence it is considered that the cusp re formation was controlled more by the antecedent morphology than the hydrodynamic conditions this indicates that positive feedback between swash hydrodynamics and beachface morphology necessary to form beach cusps does not require a large variation in relief 1997 john wiley sons ltd

advances in swash zone research small scale hydrodynamic and sediment transport processes abstract extensive research efforts in the last decade have improved knowledge of swash zone processes this paper reviews and synthesizes from 2004 onward the research advances of small scale hydrodynamics and sediment transport processes considering field laboratory and numerical modeling efforts swash zone hydrodynamics are examined by means of shoreline motions fluid velocities pressure gradients flow structure bed shear stress friction coefficients and turbulence subsequently advances related to sediment transport mechanisms and morphological changes are described detailed descriptions of measuring techniques novel findings and the strengths and weaknesses of the different approaches are discussed the review also acknowledges the major advances in the development of instrumentation to collect highly resolved flow and sediment concentration measurements in direct proximity of the bed and the experimental framework for analyzing local dynamics on a wave by wave time scale e g dam break

development and morphodynamics of beaches on horizontal shore platforms on the microtidal southeast coast of brazil abstract the differences between beaches completely composed of sand and beaches underlain or fronted seaward by hard structures have been well addressed in the current literature considering their morphological and morphodynamic particularities trenhaile 2004 modeled the accumulation and dynamics of beaches on shore platforms on mesotidal and macrotidal coast although this model had not been verified or tested in the field it can be useful to understand coastal geomorphology therefore this study aims to apply the trenhaile 2004 model to beaches on horizontal shore platforms located on the microtidal coast of espirito santo brazil and validate it using local data for this the morphological and morphodynamic particularities of the studied beaches were considered when applying and interpreting the model results besides the trenhaile 2004 model variables the role of wave runup was considered in the upward growth of the berm and then in the beach height the model results and field data showed that the gradients and elevations of shore platforms in the study area are suitable to form the beaches while wider shore platforms seem to contribute to the development of wider beaches the platforms in the study area also influence accommodation space cross shore sediment exchanges and beach mobility field data was used to test the applicability of trenhaile s 2004 model in the study area the model was found to be a potentially useful tool in coastal management helping to understand coastal geomorphology

sand transport processes and bed level changes induced by two alternating laboratory swash events abstract sand transport processes and net transport rates are studied in a large scale laboratory swash zone bichromatic waves with a phase modulation were generated producing two continuously alternating swash events that have similar offshore wave statistics but which differ in terms of wave swash interactions measured sand suspension and sheet flow dynamics show strong temporal and spatial variability related to variations in flow velocity and locations of wave capture and wave backwash interactions suspended and sheet flow layer transport rates in the lower swash zone are generally of same magnitude but sheet flow exceeds the suspended load transport by up to a factor four during the early uprush the bed level near the inner surf zone is relatively steady during a swash cycle but changes of o cm s are measured near the mid swash zone where wave swash interactions lead to strongly non uniform flows the two alternating swash events produce a dynamic equilibrium with bed level changes up to a few mm induced by single swash events but with net morphodynamic change over multiple events that is two orders of magnitude lower most of the intra swash and the single event averaged bed level changes in the swash zone are caused by a redistribution of sediment within the swash the transport of sediment across the surf swash boundary is minor at intra swash time scale but becomes increasingly significant at swash averaged time scales or longer i e averaged over multiple swash events

morpho sedimentary dynamics of a micro tidal mixed sand and gravel beach playa granada southern spain abstract this paper addresses the changes in the morphology and sedimentology of a micro tidal mixed sand and gravel beach playa granada southern spain forced by wave and water level variations and human intervention through nourishment monthly and storm event driven beach surveys consisting of topographical measurements and sediment sampling in two selected areas were carried out over a one year period three prevailing sediment fractions sand fine gravel and coarse gravel and two end member morphological states of the upper beach profile convex with multiple berms and concave with a single storm berm were identified between them several transitional profiles were formed characterized by developing berms that progressively overlapped generating sediment variability both across the beach profile and with depth the results indicate that the total run up including water level reached during an event represents a more accurate threshold for differentiating between erosional and depositional conditions than wave height they also suggest that mixed sand and gravel beaches recover faster from storm erosion than sandy beaches the long term benefit of the artificial nourishment that took place at the end of the survey period was very limited and this is attributed to the too fine sediment used for the nourishment and its placement too high on the beach clearly nourishment interventions must take into account the natural sediment distribution and the profile shape to avoid rapid losses of the nourished sediment

morphodynamic evolution of a coastal lagoon entrance during swash overwash new field observations of beach berm growth resulting in the sub aerial closure of an intermittently closed and open lake or lagoon are presented these perched estuarine systems frequently exhibit ephemeral entrances that respond to process forcing almost instantaneously on a geomorphic timescale with closure by a supra tidal berm of depositional origin the observations were made following a mechanical opening of the entrance and show very rapid vertical growth of an initially low beach berm as a result of swash overtopping and sediment overwash very little simultaneous seaward progradation was observed sediment overwash volumes were obtained from survey data over a period of 12 days either side of spring tide and the observations also provide an accurate measure of swash sediment transport at the berm crest a process based parametric model is developed through robust parameterisations of wave run up wave run up distributions and sediment transport and is applied to predict the total overwash transport into and infilling the estuary entrance the model is tested against the field data and compares well with the observations while the field data are site specific the proposed modelling framework represents a first step in modelling the complex growth and recovery of natural beach berms in broad scale morphodynamic models

direct bed shear stress measurements in bore driven swash direct measurements of bed shear in the swash zone are presented the data were obtained using a shear plate in medium and large scale laboratory bore driven swash and cover a wide range of bed roughness data were obtained across the full width of the swash zone and are contrasted with data from the inner surf zone estimates of the flow velocities through the full swash cycle were obtained through numerical modelling and calibrated against measured velocity data the measured stresses and calculated flow velocities were subsequently used to back calculate instantaneous local skin friction coefficients using the quadratic drag law the data show rapid temporal variation of the bed shear stress through the leading edge of the uprush which is typically two four times greater than the backwash shear stresses at corresponding flow velocity the measurements indicate strong temporal variation in the skin friction coefficient particularly in the backwash the general behaviour of the skin friction coefficient with reynolds number is consistent with classical theory for certain stages of the swash cycle a spatial variation in skin friction coefficient is also identified which is greatest across the surf swash boundary and likely related to variations in local turbulent intensities skin friction coefficients during the uprush are approximately twice those in the backwash at corresponding reynolds number and cross shore location it is suggested that this is a result of the no slip condition at the tip leading to a continually developing leading edge and boundary layer into which high velocity fluid and momentum are constantly injected from the flow behind and above the tip region finally the measured stress data are used to determine the asymmetry and cross shore variation in potential sediment transport predicted by three forms of sediment transport formulae crown copyright c 2009 published by elsevier b v all rights reserved

observations of morphological change and sediment transport on a steep gravel beach abstract observations of morphological change and swash sediment loads concurrent with measurements of water level waves and currents were obtained during a spring to spring tidal cycle on a steep macrotidal gravel beach in southwest england the wave conditions experienced during the field experiment were relatively calm and the significant inshore wave height and period averaged 0 4 m and 6 s respectively incident frequency water motions dominated the hydrodynamics and the phasing between water surface elevation and cross shore and alongshore currents was inconsistent with standing edge wave motion morphological change was directly related to maxima in shoreline elevation and four modes of berm adjustment identified regression and rollover in response to falling and rising water levels respectively and removal and reformation during and after storms respectively swash processes transported substantial amounts of sediment at rates comparable to sand beaches and the net transport under modal wave conditions was estimated to be 1 kg per swash onshore per unit metre beach width steep hydrodynamic gradients induced by the abrupt slope breaks of the step and berm are one of the main causes of the large morphological variability characteristic of gravel beaches

hydrodynamics and sediment transport in the swash zone a review and perspectives the dominant hydrodynamic forcing and resulting sediment transport mechanisms in the swash zone are reviewed combined with a discussion of future measurement and modelling requirements the importance of swash zone processes in the overall behaviour of the nearshore littoral zone are identified with the paper subsequently focusing on aspects that directly relate to sediment transport on beaches the review considers analytical and numerical modelling work and both field and laboratory data the hydrodynamics of the swash zone are first discussed with reference to the surf zone boundary swash characteristics forcing mechanisms and shoreline oscillations subsequent sections consider more micro scale processes such as the internal flow kinematics turbulence the bed boundary layer and infiltration exfiltration through permeable beds the second part of the paper outlines the fundamental mechanics of sediment transport in the swash zone followed by a more detailed discussion of sediment transport modes induced by the dominant hydrodynamic conditions modelling concepts are reviewed and the strengths and weaknesses of different approaches identified a final summary and future modelling perspectives conclude the paper

recent advances in modeling swash zone dynamics influence of surf swash interaction on nearshore hydrodynamics and morphodynamics the role of the swash zone in influencing the whole nearshore dynamics is reviewed with a focus on the interaction between surf and swash zone processes local and global hydromorphodynamic phenomena are discussed in detail and a description of the overall swash zone operation is given the effects of swash zone boundary conditions are highlighted together with the importance of surf zone boundary conditions major emphasis is placed on illustrating the interactions of various hydrodynamic modes which in turn control the swash and surf zone morphology finally methods to account for swash zone processes in coastal models with different temporal and spatial resolutions are proposed

the daily scale entrance dynamics of intermittently open closed estuaries intermittently open closed estuaries ioce are a dynamic form of estuary characterised by periodic entrance closure to the ocean entrance closure is a function of the relative balance between on and offshore sediment transport with closures occurring during periods of low fluvial discharge whereby the estuary ebb tidal prism is reduced although the broad scale processes of entrance closure are becoming better understood there remains limited knowledge on channel morphodynamics during an individual closure event in this study the entrance dynamics of three ioce on the coast of victoria australia were monitored over a daily timescale following both artificial and natural openings the influence of changing marine and fluvial conditions on the relative sedimentation rate within the entrance channel was examined ioce in victoria showed two distinct modes of entrance closure a lateral accretion whereby the estuary gradually closes by longshore drift driven spit growth during low river flows and b vertical accretion where the channel rapidly aggrades under high 2 m near normal waves during storms when fluvial discharge and wave heights simultaneously increase large swells will not always close the mouth due to an increase in the ebb tidal prism the estuary water depth and the maximum channel dimensions following opening were not proportional to the opening duration with this being a function of the wave and fluvial conditions occurring following lagoon drainage based on the findings of this work implementing a successful artificial entrance opening is dependent on reduced onshore sedimentation rates which occur when wave energy is low 2 m hs relative to river flow copyright

mercury distributions and mercury isotope signatures in sediments of dongjiang the pearl river delta china abstract the pearl river delta prd is one of the most industrialized and urbanized regions in china in order to assess the pollution status of mercury hg in prd river system the distribution of total mercury hgt and methylmercury me hg in sediment from a large river named dongjiang dj was for the first time investigated hgt concentrations in sediment increased from the upstream to downstream of dongjiang area and at most sites of dj were significantly higher than the background values which suggested that the dj was contaminated with hg especially in the downstream of dj me hg concentrations in sediment of dj ranged from 0 56 to10 62 ng g and were significantly correlated with hgt and organic matter in order to determine the potential hg contamination sources typical sediments from different parts of dj were chosen for hg isotope analysis the results showed that the mass dependent fraction mdf in the sediments varied significantly 202hg 2 35 to 0 60 and the mass independent fraction mif in the sediments also varied considerably 199hg 0 02 to 0 27 the samples with the highest hgt located in the industrial area had the highest 202hg 1 14 to 0 60 measured values and insignificant mif 199hg 0 04 to 0 01 meanwhile the samples with the lowest hgt located in the background area had the lowest 202hg 2 16 to 1 55 and 199hg 0 20 to 0 27 measured values unlike the above two cases are the samples located in the urban area which have relative lower mdf 202hg 2 35 to 1 96 and small but significant mif 199hg 0 10 to 0 08 with relative higher hgt we demonstrated that the dominant hg sources in dj sediments could be categorized as the regional background urban and industrial sources in our study we demonstrated that hg stable isotope method could serve as an effective tool for tracing mercury contamination sources in the environment

experimental study of bore driven swash swash interactions on an impermeable rough slope abstract experimental measurements are obtained to investigate the detailed hydrodynamics of wave wave interactions in the swash zone two bores are generated using a double dam break mechanism and interact on a 1 10 impermeable rough slope measurements of the hydrodynamics are obtained via acoustic displacement sensors and a combined particle image velocimetry and laser induced fluorescent system two types of interactions are investigated wave capture with the second bore reaching the first one during the uprush and weak wave backwash interactions when interaction happens during the backwash of the first wave the relative strength of the bores at the initial shoreline and time between their arrivals determines the initial type of interaction however the type as well as the intensity of the interaction may vary throughout the swash zone for the same swash event during wave capture and weak wave backwash interactions the fluid of the first bore is advected upwards then mixed with the fluid of the second bore by intense shearing and highly turbulent vortices generated at the front of the second bore because of the relative velocity differences between the two bores the details of the hydrodynamics during interaction confirm the potential of swash swash interactions to suspend sediment and transport it shoreward or interrupt seaward sediment transport

the role of swash infiltration in determining the beachface gradient a numerical study on sand and gravel beaches the increase of the gradient of the beachface with increasing sediment size has been attributed to swash infiltration the present study uses a process based numerical model to examine in detail the role of swash infiltration in determining the beachface gradient it is found that swash infiltration increases the onshore asymmetry in the swash flow thereby enhancing onshore sediment transport and resulting in relatively steep beachface gradients however the accretionary effects of swash infiltration are only evident when the rate of infiltration is sufficiently large i e when the total infiltration volume over a wave cycle exceeds c 2 of the uprush volume this threshold is attained when the hydraulic conductivity exceeds 1 cm s which is approximately equivalent to a grain size coarser than 1 5 mm this finding suggests that the correlation between beachface gradient and sediment size observed on sandy beaches is not due to enhanced swash asymmetry caused by swash infiltration for gravel beaches however swash infiltration is likely to be the dominant factor in controlling the beachface gradient with increased hydraulic conductivity i e sediment size resulting in steeper beachface gradients c 2001 elsevier science b v all rights reserved

high frequency sediment level oscillations in the swash zone sediment level oscillations with heights of about 6 cm and shore normal lengths of order 10 m have been measured in the swash zone of a high energy coarse sand beach crests of oscillations were shore parallel and continuous alongshore the oscillations were of such low steepness height to length ratio approximately 0 006 that they were difficult to detect visually the period of oscillation ranged between 6 and 15 min and decreased landward across the swash zone the sediment level oscillations were progressive landward with an average migration rate in the middle to upper swash zone of 0 8 m min 1 migration was caused mostly by erosion on the seaward flank of the crest of an oscillation during a period of net seaward sediment transport thus the observed migration was a form migration landward rather than a migration involving net landward sediment transport the observed sediment level oscillations were different than sand waves or other swash zone bedforms previously described

swash zone sediment fluxes field observations abstract this paper describes newly obtained high frequency observations of beach face morphological change over numerous tidal cycles on a macrotidal sandy beach made using a large array of ultrasonic altimeters these measurements enable the net cross shore sediment fluxes associated with many thousands of individual swash events to be quantified it is revealed that regardless of the direction of net morphological change on a tidal time scale measured net fluxes per event are essentially normally distributed with nearly equal numbers of onshore and offshore directed events the majority of swash events cause net cross shore sediment fluxes smaller than 50 kg m 1 and the mean sediment flux per swash event is only o 1 kg m 1 leading to limited overall morphological change however much larger events which deposit or remove hundreds of kilograms of sand per meter width of beach occur at irregular intervals throughout the course of a tide it was found that swash swash interactions tend to increase the transport potential of a swash event and the majority of the swash events that cause these larger values of sediment flux include one or more interactions the majority of the larger sediment fluxes were therefore measured in the lower swash zone close to the surf swash boundary where swash swash interactions are most common despite the existence of individual swash events that can cause fluxes of sediment that are comparable to those observed on a tidal time scale frequent reversals in transport direction act to limit net transport such that the beach face volume remains in a state of dynamic equilibrium and does not rapidly erode or accrete

beach face and berm morphodynamics fronting a coastal lagoon this study documents two different modes of berm development i vertical growth at spring tides or following significant beach cut due to substantial swash overtopping and 2 horizontal progradation at neap tides through the formation of a proto berm located lower and further seaward of the principal berm concurrent high frequency measurements of bed elevation and the associated wave runup distribution reveal the details of each of these berm growth modes in mode i sediment is eroded from the inner surf and lower swash zone where swash interactions are prevalent the net transport of this sediment is landward only resulting in accretion onto the upper beach face and over the berm crest the final outcome is a steepening of the beach face gradient a change in the profile shape towards concave and rapid vertical and horizontal growth of the berm in mode 2 sediment is eroded from the lower two thirds of the active swash zone during the rising tide and is transported both landward and seaward on the falling tide sediment is eroded from the inner surf and transported landward to backfill the zone eroded on the rising tide the net result is relatively slow steepening of the beach face a change of the profile shape towards convex and horizontal progradation through the formation of a neap berm the primary factor determining which mode of berm growth occurs is the presence or absence of swash overtopping at the time of sediment accumulation on the beach face this depends on the current phase of the spring neap tide cycle the wave runup height and indirectly offshore wave conditions and the height of the pre existing berm a conceptual model for berm morphodynamics is presented based on sediment transport shape functions measured during the two modes of berm growth c 2006 elsevier b v all rights reserved

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

laboratory investigation of the bruun rule and beach response to sea level rise abstract rising sea levels are expected to cause widespread coastal recession over the course of the next century in this work new insight into the response of sandy beaches to sea level rise is obtained through a series of comprehensive experiments using monochromatic and random waves in medium scale laboratory wave flumes beach profile development from initially planar profiles and a 2 3 power law profile exposed to wave conditions that formed barred or bermed profiles and subsequent profile evolution following rises in water level and the same wave conditions are presented experiments assess profile response to a step change in water level as well as the influence of sediment deposition above the still water level e g overwash a continuity based profile translation model ptm is applied to both idealised and measured shoreface profiles and is used to predict overwash and deposition volumes above the shoreline quantitative agreement with the bruun rule and variants of it is found for measured shoreline recession for both barred and bermed beach profiles there is some variability between the profiles at equilibrium at the two different water levels under these idealised conditions deviations between the original bruun rule the modification by rosati et al 2013 and the ptm model predictions are of the order of 15 and all these model predictions are within 30 of the observed shoreline recession measurements of the recession of individual contour responses such as the shoreline may be subject to local profile variability therefore a measure of the mean recession of the profile is also obtained by averaging the recession of discrete contours throughout the active profile the mean recession only requires conservation of volume not conservation of profile shape to be consistent with the bruun rule concept and is found to be in better agreement with all three model predictions than the recession measured at the shoreline

discussion of measurement of wave by wave bed levels in the swash zone by ian l turner paul e russell tony butt coastal eng 55 2008 1237 1242 this paper is a discussion of turner et al measurement of wave by wave bed levels in the swash zone the discussion highlights previous work on the same topic that in fact demonstrated swash by swash measurements of total net sediment transport but which was not presented by turner et al the discussion highlights the advantages and disadvantages of the two measurement methods and the problem of longshore sediment motion which can introduce errors c 2008 elsevier b v all rights reserved

geological evolution of the marine selenium cycle insights from the bulk shale δ82 76se record and isotope mass balance modeling bulk 82 76se values of representative marine shales from the paleoarchean to the present day vary between approximately 3 and 3 with only local deviations beyond this range this muted se isotope variability in the shale record contrasts with the relatively large fractionations associated with abiotic and microbial se oxyanion reduction seen in experimental studies long term temporal trends in the bulk shale data do not directly correlate with changes in redox conditions of the global ocean although a minor but significant shift towards more negative formation averaged 82 76se values appears to track oxygenation of the deep ocean at the end of the proterozoic we hypothesize that extensive 82 76se variability in the shale data was suppressed due to the early emergence of biological assimilatory uptake and the resulting persistence of low seawater se concentrations coupled with small authigenic se outputs throughout most of geological time in the modern ocean se is an essential micronutrient with a relatively short residence time of about 11 500 yrs the marine se cycle is dominated by assimilation into biomass and subsequent recycling in the water column and surface sediments i e processes that result in only minimal isotopic fractionation we suggest that similar processes dominated back through the geological record to archean times our model shows that paleoceanographic information could in principle be extracted from proxy data on the se isotopic composition of seawater once isotopic differences can be readily discerned between individual sedimentary se pools

variable swash motions associated with foreshore profile change variations in swash motions over a temporally changing foreshore surface are examined over the first tidal cycle following the onset of a storm using high resolution video observations obtained at duck north carolina a dramatic example of profile adjustment was observed where nearly 1 m of vertical change occurred over a 4 hour time period swash edge excursion measurements during this study compare favorably with predictions from standard equations describing ballistic motions of an object on a plane slope under quadratic friction and showed no strong asymmetries between uprush and backwash that might explain the profile adjustment instead these unique observations showed a tendency toward a predictable equilibrium between swash motions and profile response where the stability condition relates foreshore slope to incident wave period and initial uprush velocity using the ballistic equations under these conditions the foreshore adjusts to minimize the difference between swash duration and incident wave period on the basis of this finding a simple morphodynamic model for changes in foreshore slope as a function of swash and surf conditions is presented and allows prediction of the transition from an erosive to stable condition

suspended sediment transport and beach dynamics induced by monochromatic conditions long waves and wave groups abstract this study presents the analysis of the water surface elevation velocity and suspended sediment concentration measurements obtained at a large wave flume under mobile bed conditions the wave reproduced erosive and accretive conditions and included monochromatic short waves perturbed with a free long wave bichromatic and random conditions each tested condition started from a handmade 1 15 slope and lasted for an approximate time period of 2 4 h 6 runs of the selected wave condition to compare the different beach profile developments and in particular the events that control sediment transport in the swash and surf zones all erosive tested conditions produced a shoreline retreat and a bar at the breaking area whose development in time is directly correlated to the length of the breaking area on the other hand not all accretive conditions present a shoreward transport and random conditions do not seem to alter the initial profile the processed data show the suspended sediment event control produced by the existence or absence of wave backwash interactions in the swash zone the existence of these interactions and their number within the wave group will be a key parameter in controlling the sediment stirring water velocity magnitudes and therefore the suspended sediment fluxes in the inner surf and outer swash

dynamics of multiple intertidal bars over semi diurnal and lunar tidal cycles north lincolnshire england multiple intertidal bars are common features of wave dominated sandy beaches yet their short term 1 month and small scale 1 km morphology and dynamics remain poorly understood this study describes the morphodynamics of multiple intertidal bars in north lincolnshire england during single and lunar tidal cycles under two contrasting conditions first when significant wave height was 0 5 m and second when significant wave height frequently exceeded 1 m the relative importance of swash surf and shoaling processes in determining morphological change was examined using detailed field observations and a numerical model the beach featured four intertidal bars and both cross shore and longshore bar morphology evolved during the field investigation particularly under medium to high wave energy conditions numerical modelling suggests shoaling processes are most common on the seaward two bars under calm wave conditions hs 0 5 m and that surf zone processes become more common during neap tides and under more energetic hs 0 5 m conditions surf processes dominate the inner two bars though swash influence increases in a landward direction the numerical modelling results combined with low tide survey data and high resolution morphological measurements strongly suggest changes in the intertidal bar morphology are accomplished by surf zone processes rather than by shoaling wave or swash processes this is because shoaling waves do not induce significant sediment transport to have any morphological effect whereas swash action generally does not have enough scope to act as the swash zone is much narrower than the surf zone it was found however that the absolute rate of morphological change under swash action and surfzone processes are of similar magnitudes and that swash action may induce a significant amount of local morphological change when the high tide mark is located on the upper bar making this process important for bar morphodynamics copyright 2007 john wiley sons ltd

berm formation and dynamics on a gently sloping beach the effect of water level and swash overtopping berm formation and morphological development of the beach face have been observed during a neap neap tidal cycle on the gently sloping and accreting beach at vejers denmark during the field campaign an intertidal bar migrated onshore and stabilized as a berm on the foreshore a new intertidal bar occurred on the lower beach face migrated onshore on the rising tide and finally merged with the pre existing berm as the tide continued to rise the new berm translated further onshore as an intertidal bar to the uppermost part of the foreshore the sediment transport during the berm transition was onshore directed in the upper swash and offshore directed in the lower swash this berm development can be described through both the neap berm ridge and runnel and berm ridge development concepts proposed by hine sedimentology 1979 26 333 351 and all three stages were observed during only three tidal cycles the main factors controlling this fast transformation were the gentle slope of the cross shore profile rapid water level translation rates substantial swash overtopping of the berm and low infiltration rates despite the onshore migration of intertidal bars and berm formation no net foreshore accretion took place during the field campaign this was largely due to the formation of rip channels with strong rip currents cutting through the intertidal bars and the berm which acted as a sediment drain in the profile

a parametric model for dry beach equilibrium profiles abstract predictions of dry beach morphologies are extensively required in coastal research for multiple purposes e g dune erosion forecasting inundation heights determination and beach fill design optimization in this paper we introduce and test a parametric model that describes the equilibrium shape of the dry beach in the cross shore direction i e an equation for the dry beach equilibrium profile the model consists of a three parameter equation formed by two terms an exponential that defines the foreshore and berm morphology plus a linear term that defines the slope from the berm to the landward limit as a planar far field behaviour the three morphological parameters that shape the equation are related to the nearshore wave climate hs and tp and the sediment characteristics d50 in a form which is consistent with previous knowledge of dry beach morphodynamics thus proposing the runup driver h l 1 2 and the dimensionless fall velocity as the fundamental variables defining the equation parameters we tested the predictive capacity of the model against an independent data set from narrabeen beach which depending on longshore location and the time of year offers beach modal states ranging from dissipative to reflective the exponential term of the equation correctly explains the foreshore and berm morphology under mean wave climate and the linear term predicts the slope of the asymptotic planar segment all with good correlation coefficients 0 95 between modelled cross shore transects and observations the proposed model helps in defining the main shapes of subaerial beach profiles over the long term and it may also be useful as a coastal management tool for predicting dry beach morphologies

bed level fluctuations in the inner surf and swash zone of a dissipative beach abstract a field study was conducted on a dissipative beach to quantify inner surf and swash zone bed level change during periods of inundation and throughout a tidal cycle elevation changes were acquired at millimeter resolution with a new conductivity concentration profiler that allowed quantification of the bed level throughout the duration of the wave swash cycle and also during periods of bed exposure bed level change spectra showed the highest energy at low frequencies even though event scale net bed level changes were observed to exceed the tidal scale net bed level change net bed level change for individual events was nearly normally distributed with most individual events displaying little or no net bed level change large erosion and accretion events with bed level elevation magnitudes that exceeded net tidal elevation change occurred with similar frequency the similarity between the frequency of large erosion and large accretion events suggests that a few events may be ultimately responsible for the observed net elevation change over the tidal cycle the large events displayed different hydrodynamic characteristics erosion events had longer duration onshore directed flow and higher maximum onshore directed velocity magnitude than offshore directed velocity magnitude the opposite was found for accretion events that had longer duration offshore directed flow and a higher maximum offshore directed velocity magnitude than onshore directed velocity magnitude

short term morphodynamics of non storm overwash abstract overwash is an important process in barrier island evolution and its effects on the barrier morphology and sedimentology have been widely studied however the short term sediment dynamics of overwash processes are not well known due to the lack of specific field studies this paper presents field data that clarify the sedimentary dynamics of overwash processes on different washover morphologies and determine the factors leading to non storm overwash occurrence two fieldwork campaigns were undertaken during overwash events go 1 winter of 2001 and go 3 winter of 2003 on western barreta island algarve portugal the fieldwork included measurements of oceanographic conditions overwash flows morphology variations mixing depth and sediment transport paths using tracers the sediment dynamics induced by overwash varied according to the washover morphology washover plain versus washover lobe the sediment transport inside the washover plain was different for the two fieldwork campaigns average mixing depth of 13 cm for go 1 and 6 cm for go 3 however it had similar main stages stage 1 crest accretion stage 2 onshore transport and stage 3 dynamic equilibrium the sediment transport inside the washover lobe can be characterised by one onshore flow stage with erosion of the mouth and channel and accretion on the washover fan the main factors governing the occurrence of non storm overwash in the study area were the combined occurrence of 1 typical winter waves 2 spring high tides 3 washover crest below the high tide level 2 m and 4 absence of prominent beach berm this study proved that when the proper conditions are generated non storm overwash has sediment transport comparable to storm overwash and therefore may be significant for barrier evolution further field studies of overwash are needed principally for more detailed overwash flow velocity measurements high frequency morphologic surveys and barrier groundwater measurements

tidal asymmetry in suspended sand transport on a macrotidal intermediate beach abstract time series of nearbed horizontal flow velocities and suspended sediment concentrations obtained from a colocated electromagnetic current meter emcm and optical backscatter sensor obs respectively are used to examine the relative importance of steady and fluctuating components to the total sediment transport over a full tidal cycle on a macrotidal intermediate beach spurn head uk fluctuating sediment fluxes are decomposed into gravity and infragravity contributions using co spectral techniques the relative importance of the oscillatory gravity and infragravity and steady mean transport components to the total sediment transport is analysed throughout the tidal cycle a continuum of 34 discrete suspended sediment cross shore velocity co spectra are computed over a full tidal cycle for the obs and emcm measurements 0 10 m above the bed these net transport spectra vary greatly both with cross shore location and tidal state in particular a marked asymmetry in transport processes is evident between the flood and ebb tides with high levels of sediment resuspension and transport occurring on the ebbing tide approximately two hours after high water just seaward of the breakpoint at this time the dominant transport was directed offshore co spectral peak 0 04 kg m 2 s at incident wave frequency typical patterns are observed in transport spectra outside the surf zone and within the inner surf zone outside the narrow surf zone cross shore transport spectra show weak offshore transport co spectral peak 0 002 kg m 2 s associated with bound long waves and stronger onshore transport co spectral peak 0 006 kg m 2 s at incident wave frequencies conversely co spectra computed within the inner surf zone show the offshore sediment fluxes spectral peak 0 010 kg m 2 s at infragravity frequencies to be greater in magnitude than the corresponding onshore transport co spectral peak 0 008 kg m 2 s occurring at incident wave frequencies

sandbar and beach face evolution on a prototype coarse sandy barrier abstract on steep beaches the cross shore movement of sand in response to erosive storm waves and accretive swell waves can lead to temporal changes between a barred winter profile and a non barred summer profile with a pronounced berm in the upper swash zone despite recent improvements in predicting berm formation and evolution within process based morphodynamic models substantial demand for improvement in understanding swash processes and associated surf swash sand exchange remains here we analyze bed level data collected on a near prototype 4 5 m high and 75 m wide sandy beach median grain diameter d50 430 m with a lagoon situated at its landward side in particular we distinguish between surf swash sand exchange time scale of tens of minutes to hours the net effect of single and multiple swash events on the entire beach face time scale of a few seconds to hours and instantaneous bed variability at 3 cross shore locations within individual swashes during erosive waves hs 0 8 m tp 8 s sand on the initially 1 15 planar profile was predominantly eroded from the inner surf zone to be deposited in the outer surf zone as a sandbar indicating minimal surf swash sand exchange subsequent accretive waves hs 0 6 m tp 12 s caused substantially larger surf swash sand exchange the pre existing sandbar migrated onshore and decayed with the sand ending up on the beach face in a prominent up to 0 7 m high steep 1 6 berm we found the dynamics of the berm to be governed primarily by wave conditions and the antecedent morphology with ground water gradients of additional importance when morphodynamic feedback between swash flow and the berm is small the observed bed level change within a swash and averaged over a swash event could be substantial several centimeters during all wave conditions but the net i e averaged over multiple swash events bed level change was strongly suppressed because erosive and accretionary swashes nearly balanced in addition the local beach face slope could be instantaneously 25 steeper or shallower than the median slope or the initial or final slope we anticipate that our data will stimulate new model development as to increase the range of conditions and settings in which morphodynamic models can be applied realistically and reliably

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

a novel method for tracking individual waves in the surf zone a new method to obtain information on individual waves as they travel shoreward is described the wave tracking method involves analysis of synchronous water level records obtained from a shore normal transect of pressure transducers pts the method is illustrated here using data from field deployments inside the surf zone although the method could equally be applied outside the surf zone as a wave travels shoreward along the instrument transect it appears in the pt records at a progressively later time serial cross correlation techniques are used to shift each record in time so that each wave in the first record aligns approximately with the corresponding wave if it exists in subsequent records from along the transect a local minima analysis power et al 2010 is used to delimit individual waves in each record and then parameters of interest can be determined for each wave at each pt location the wave tracking method provides the evolution of these parameters for a single wave as it travels to shore and they can be analysed as a function of distance or local water depth the utility of the method is illustrated with case studies including the evolution of wave height and the evolution of the ratio of wave height to water depth for surf zone waves

measurements and modelling of the advection of suspended sediment in the swash zone by solitary waves novel laboratory experiments and numerical modelling have been performed to study the advection scales of suspended sediment in the swash zone an experiment was designed specifically to measure only the sediment picked up seaward of the swash zone and during bore collapse the advection scales and settling of this sediment were measured during the uprush along a rigid sediment free beach face by a sediment trap located at varying cross shore positions measurements were made using a number of repeated solitary broken waves or bores approximately 25 of the pre suspended sediment picked up by the bores reaches the mid swash zone 50 of the horizontal run up distance indicating the importance of the sediment advection in the lower swash zone the pre suspended sediment is sourced from a region seaward of the shoreline still water line which has a width of about 20 of the run up distance an eulerian lagrangian numerical model is used to model the advection scales of the suspended sediment the model resolves the hydrodynamics by solving the non linear shallow water equations in an eulerian framework and then solves the advection diffusion equation for turbulence and suspended sediment in a lagrangian framework the model provides good estimates of the measured mass and distribution of sediment advected up the beach face the results suggest that the correct modelling of turbulence generation prior to and during bore collapse and the advection of the turbulent kinetic energy into the lower swash is important in resolving the contribution of pre suspended sediment to the net sediment transport in the swash zone c 2009 elsevier b v all rights reserved

sediment transport and beach morphodynamics induced by free long waves bound long waves and wave groups new laboratory data are presented on the influence of free long waves bound long waves and wave groups on sediment transport in the surf and swash zones as a result of the very significant difficulties in isolating and identifying the morphodynamic influences of long waves and wave groups in field conditions a laboratory study was designed specifically to enable measurements of sediment transport that resolve these influences the evolution of model sand beaches each with the same initial plane slope was measured for a range of wave conditions firstly using monochromatic short waves subsequently the monochromatic conditions were perturbed with free long waves and then substituted with bichromatic wave groups with the same mean energy flux the beach profile changes and net cross shore transport rates were extracted and compared for the different wave conditions with and without long waves and wave groups the experiments include a range of wave conditions e g high energy moderate energy low energy waves which induce both spilling and plunging breakers and different turbulent intensities and the beaches evolve to form classical accretive erosive and intermediate beach states the data clearly demonstrate that free long waves influence surf zone morphodynamics and promote increased onshore sediment transport during accretive conditions and decreased offshore transport under erosive conditions in contrast wave groups which can generate both forced and free long waves generally reduce onshore transport during accretive conditions and increase offshore transport under erosive conditions the influence of the free long waves and wave groups is consistent with the concept of the relative fall velocity h wst as a dominant parameter controlling net beach erosion or accretion free long waves tend to reduce h wst promoting accretion while wave groups tend to increase the effective h wst promoting erosion

intermittently closed open lakes and lagoons their global distribution and boundary conditions abstract intermittently closed open lakes and lagoons icolls are a particularly dynamic form of estuary characterised by periodic entrance closure to the ocean closure occurs when a subaerial sand berm stabilises across the entrance channel during times of low fluvial discharge icolls are of global importance as they provide valuable ecological habitats for many species and are associated with a wide range of management issues due to their cycle of entrance closure and opening icolls are found to be more widespread globally than previously described with 1477 of these estuaries being identified in this study this constitutes an estimated 3 of the world s estuaries and 15 of all estuaries along microtidal coastlines icolls are concentrated along microtidal to low mesotidal coastlines in the mid latitudes and predominantly on coasts with temperate climates this distribution is related to greater wave heights as driven by high intensity winds and a longer fetch distance the highest proportion of icolls are present in australia 21 all global icolls south africa 16 and mexico 16 in australia a comparison with fluvial input found that it is less important than marine processes in determining icoll formation and that icolls are associated with a relative tidal range of

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