scaling and parametrization of clear sky solar radiation over complex topography 1 solar radiation at the land surface is influenced by slope aspect shadows and obstruction of the sky all of which vary over a wide range of length scales in regions of complex topography with important consequences for the surface energy balance atmospheric models however generally assume the surface to be flat on subgrid scales for four areas in north america ranging in latitude from 39 n to 69 n and in topography from rolling to mountainous we simulate spatial patterns of clear sky incoming solar radiation it is found that distributions of slope components and variations in shaded area with solar elevation can be approximated by simple functions that scale to each of the areas studied from these results parametrizations are developed for averages standard deviations and distributions of direct beam and diffuse solar radiation results from these parametrizations and from a modified form of a simpler parametrization presented previously compare well with statistics from the spatial simulations the only topographic input required by the parametrizations is the standard deviation of slope components this parameter is again found to have simple scaling relationships with the resolution and extent of the underlying elevation grid and with the standard deviation of elevation

late pleistocene and holocene paleoenvironments of the north pacific coast abstract unlike the north atlantic the north pacific ocean probably remained free of sea ice during the last glacial maximum lgm 22 000 to 17 000 bp following a eustatic low in sea level of ca 120 m at 19 000 bp a marine transgression had flooded the bering and chukchi shelves by 10 000 bp post glacial sea level history varied widely in other parts of the north pacific coastline according to the magnitude and timing of local tectonism and glacio isostatic rebound glaciers covered much of the continental shelf between the alaska peninsula and british columbia during the lgm maximum glacier extent during the lgm was out of phase between southern alaska and southern british columbia with northern glaciers reaching their outer limits earlier between 23 000 and 16 000 bp compared to 15 000 14 000 bp in the south glacier retreat was also time transgressive with glaciers retreating from the continental shelf of southern alaska before 16 000 bp but not until 14 000 13 000 bp in southwestern british columbia major climatic transitions occurred in the north pacific at 24 000 22 000 15 000 13 000 and 11 000 9000 bp rapid climate changes occurred within these intervals including a possible younger dryas episode an interval of climate warmer and drier than today occurred in the early holocene cooler and wetter conditions accompanied widespread neoglaciation beginning in some mountain ranges as early as the middle holocene but reaching full development after 3000 bp

shoreline response to submerged structures a review abstract submerged coastal structures are widely perceived to be capable of providing beach protection without the adverse impacts including loss of beach amenity and aesthetic considerations often associated with more conventional structures such as revetments and groynes in addition there is growing interest in the concept that the layout and cross section of submerged coastal protection structures can be optimised to also enhance local surfing conditions however as submerged structures have only rarely been adopted for beach protection the shoreline response to these structures is not well understood at present therefore this review of the available published literature was undertaken with the aim of investigating the environmental and structural parameters governing shoreline response to submerged structures gleaned from the results of field laboratory and numerical studies undertaken to date the review reveals that contrary to expectations a majority of the submerged structures constructed to date have resulted in shoreline erosion in their lee furthermore the key environmental and structural parameters governing the mode i e erosion or accretion and the magnitude i e size of salient of shoreline response to submerged structures are yet to be identified although submerged coastal structures offer the potential for low aesthetic impact incorporating multi function design until the response of the adjacent shoreline to submerged structures is better resolved their use is likely to remain relatively limited

lobal interactions rheologic superposition and implications for a pleistocene ice stream on the continental shelf of british columbia abstract data on structures stone striae clast pavements fabrics morphology provenance and matrix grain size of four pre late wisconsinan diamictons are presented from the lower accessible part of an 855 m long sea cliff at cape ball east coast of graham island queen charlotte archipelago british columbia the data indicate that an ice stream crossed the continental shelf from the british columbian mainland to the queen charlotte islands local queen charlotte piedmont ice coalesced with the western edge of the cordilleran ice sheet resulting in northward flow deflection along the east coast of graham island generally consistent structural and stone data indicate that diamictons were deposited as primary subglacial tills and that subglacial dynamics and rheologic conditions were complex two of the tills can be traced continuously over the cape ball section which provides a north south transect oblique to ice flow each of the two tills reveals five major changes in rheology and genesis ranging from a strong lodgement component to dominantly deformation mainly by subglacial squeeze flow true end member tills are rare and in almost all places the tills are hybrids that formed within a continuum of till forming processes commonly involving stone rotation and superposition of structures and rheologic states this could have occurred mainly in response to fluctuating till pore water content along the transect two dimensional stretches of contrasting till types probably represent a three dimensional patchwork of contrasting till rheologies and pore waters if patches of ductily deforming till were common and or widespread they could have accounted for much of the movement of cordilleran ice over glaciomarine mud on the continental shelf when sea level was much lower than present deforming probably saturated muddy till reconstituted glaciomarine would have possessed negligible shear strength resulting in a thin rapidly moving glacier most likely an ice stream that reached cape ball but failed to remove the record of previous glacial events the ice stream probably issued out of the mainland s skeena valley which is aligned with cape ball and is approximately the size of valleys in antarctica that today conduct small outlet glaciers and ice streams evidence for this and other ice streams on the northwestern continental shelf of north america imply that destabilization and rapid decay of the western edge of the cordilleran ice sheet may have been accomplished by a combination of ice streams sea level rise and extensive calving

morphological response and coastal dynamics associated with major storm events along the gulf of lions coastline france abstract along the coast anticipating the different morphological responses induced by storm events is crucial for managers to evaluate coastal risks and to develop the best measures to mitigate them in this paper a methodology is developed to determine the best storm intensity parameter to derive storm thresholds for different morphological responses the methodology is applied to the northern part of the gulf of lions coastline where storm events can induce important morphological changes these include shoreline retreat beach and dune erosion significant migration of nearshore bars overwashes and even breaches of coastal barriers as well as damage to coastal defences and coastal infrastructure in order to evaluate historical storm characteristics and impact an extensive review was undertaken to obtain quantitative datasets beach profiles wave records aerial photographs and more qualitative information on morphological evolution and coastal damage re analysis of hydrodynamic and morphology data was undertaken and hindcast wave modelling results were used to characterised storm intensities the methodology developed to evaluate storm thresholds consists of obtaining morphological evolution indicators evidence of breaching overwash processes volume variations and migration of morphological patterns that can be directly linked to a storm event and its characteristics results demonstrate that in such a quasi non tidal wave dominated environment with intermediate double barred beach shoreface morphology major coastal changes occur following the maximum significant wave height reached during the storm or else according to maximum wave run up elevation regarding upper beach impact a wave height dependant parameter inversely storm surge and water level alone as well as total storm energy do not explain any storm impact scale storm specific datasets indicate that important morphological evolution is observed during moderate storm events significant wave heights over 2 7 m above this threshold the morphological behaviour changes radically the main characteristics are a rapid offshore migration of the nearshore bars and large deposition of sand on the upper beach however the major morphological changes are associated with even more energetic events when the significant wave height reaches 5 m important impacts are observed breaching and overtopping of natural coastal barriers and severe dune erosion and impacts to coastal infrastructure on urbanised beaches qualitative observations show an important increase in damage when the storm waves reach 5 m the methods employed can be applied easily to any coastal segment and provide coastal managers with tools to evaluate different coastal evolution and coastal damage induced by storm events

effect of hydrodynamics and bathymetry on video estimates of nearshore sandbar position remote sensing of wave breaker patterns clearly visible as high intensity bands in time exposure video images has become a powerful tool to obtain large scale kilometers and long term years time series of nearshore sandbar position however intensity based bar crest positions xi differ from directly measured positions xb by a time varying distance x which is of o 10 m and depends on the offshore wave height h0 the water level 0 and the bathymetry itself the effect of these parameters on x was investigated from simultaneous video observations and bathymetric surveys obtained in the double barred system at egmond aan zee netherlands and from wave model predictions assuming that the roller energy represents image intensity when the wave field over a bar was predicted to be nonsaturated xi was observed and predicted to move offshore as either 0 decreased or h0 increased under saturated conditions x only responded to changes in 0 additional model investigations showed that an increase in outer bar crest depth similar to that observed during interannual bar behavior significantly reduced the x variability at the outer bar and increased the x variability at the inner bar implications of our observational and model findings for studying sandbar position from video imagery are outlined

shoreline response to multi functional artificial surfing reefs a numerical and physical modelling study the results of a series of 2dh numerical and 3d scaled physical modelling tests indicate that processes governing shoreline response to submerged structures such as artificial surfing reefs are different from those associated with emergent offshore breakwaters unlike the case of emergent offshore breakwaters where shoreline accretion salient development is expected under all structural environmental conditions the principal mode of shoreline response to submerged structures can vary between erosive and accretive depending on the offshore distance to the structure the predominant wave incidence angle and structure crest level also have important implications on the magnitude of shoreline response but not on the mode of shoreline response i e erosion vs accretion based on the results obtained here a predictive empirical relationship is proposed as a preliminary engineering tool to assess shoreline response to submerged structures

rip currents mega cusps and eroding dunes abstract dune erosion is shown to occur at the embayment of beach mega cusps o 200 m alongshore that are associated with rip currents the beach is the narrowest at the embayment of the mega cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune to undercut the dune and to cause dune erosion field measurements of dune beach and rip current morphology are acquired along an 18 km shoreline in southern monterey bay california this section of the bay consists of a sandy shoreline backed by extensive dunes rising to heights exceeding 40 m there is a large increase in wave height going from small wave heights in the shadow of a headland to the center of the bay where convergence of waves owing to refraction over the monterey bay submarine canyon results in larger wave heights the large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale the strongly refracted waves and narrow bay aperture result in near normal wave incidence resulting in well developed persistent rip currents along the entire shoreline the alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95 confidence the alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95 confidence therefore it is concluded the mega cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega cusp

exploiting remote imagery in an embayed sandy beach for the validation of a runup model framework storm surge and wave runup are key determinants of the potential for beach overwashing during storm events however the prediction and quantification of wave runup on embayed beaches is strongly influenced by particular characteristics e g irregular morphology low tides absence of swell etc which differ from those on open beaches and have rarely been investigated in literature in the present paper a model framework aimed at predicting wave induced runup on an embayed sandy beach is validated by means of measurements derived from a video monitoring station recently installed in south italy during two storm events in 2016 the numerical approach employs meteocean forecasted waves within swan and swash models in both 2 d and 1 d mode the combination of multibeam and d rtk surveys with unmanned aerial vehicle uav imagery provides high resolution depth grid m 0 015 particularly required in shallow waters where wave hydrodynamics is highly influenced by the bottom the results show and discuss the agreement between video measurements and 2 d predictions of runup a sensitivity analysis of the manningfls roughness factor is needed in 1 d simulations the accuracy of the empirical formulas in predicting wave runup in an embayed beach is also investigated showing mainly an overestimation of the observations

late pleistocene terrestrial deposits on the continental shelf of western canada evidence for rapid sea level change at the end of the last glaciation a paleosol with in situ rooted plant remains has been found in a core at a water depth of 95 m on the central continental shelf of british columbia fluvial sediments associated with the paleosol are sharply overlain by lagoonal or shallow pond sediments these in turn are overlain by shallow marine ediments radiocarbon dates on wood fragments and root recovered from the cored sediments indicate that relative sea level was at least 95 m lower 10 500 yr b p and that the core site was rapidly transgressed by the sea shortly thereafter this rapid transgression was contemporaneous with an equally rapid regression at the heads of fiords on the british columbia mainland to the east the two are probably genetically linked and a result of late pleistocene deglaciation and the migration and collapse of a glacial forebulge our evidence indicates that large areas of the british columbia continental shelf were subaerially exposed 11 10 ka this may have facilitated the southward migration of early humans from beringia into mid continental north america at the end of the pleistocene

queen charlotte area cenozoic tectonics and volcanism and their association with relative plate motions along the northeastern pacific margin cenozoic relative plate interactions along the queen charlotte margin based on published models for the north america and northeast pacific plates are related to the tectonic and igneous history of the region plate motion models indicate convergence and subduction prior to the eocene since that time there has been transcurrent motion with varying small amounts of oblique extension or compression assuming that the pacific america farallon triple junction was to the south of the region a late miocene or early pliocene about 4 ma to present period of oblique convergence is well resolved the present queen charlotte fault zone along the west coast of the islands may have initiated more recently within the cenozoic transcurrent regime a period of oblique extension in the mid tertiary 36 20 ma in one model is supported by a variety of volcanic and tectonic evidence a small plate motion change at about 20 ma may have resulted in the transfer of the yakutat terrane from the north america plate to the pacific plate and the resulting motion of the terrane northwestward to its present position along the margin of alaska the onset of tertiary masset volcanism that is extensive on the queen charlotte islands corresponds within a few million years to the time of major plate reorganization at 43 ma that has tectonic expression around the entire pacific basin the period of most extensive masset volcanism and plutonism appears to correlate with the model oblique extension in the mid tertiary for one model the geochemistry and physical volcanology of the masset volcanic s are indicative of an extension regime the main syntectonic deposition in the queen charlotte basin skonun formation as inferred from seismic reflection and well data also appears temporally correlated with this time interval of oblique extension a variety of data including plate models dikes normal faults basin subsidence crustal thickness from seismic refraction and present and paleo heat flow indicate mid tertiary crustal extension of at least 20 in the queen charlotte region with up to 150 up to 2 5 in the main queen charlotte basin posttectonic basin subsidence and deposition may correlate with the model time interval of general transcurrent or oblique convergence motion from 20 to 4 ma more recent shortening deformation observed in outcrop and seismic sections of the northern parts of the basin may correlate with plate model oblique convergence from 4 ma to the present the latter convergence is associated with underthrusting that formed a trough or trench and an accretionary sedimentary prism off the west coast of the queen charlotte islands and with inferred uplift and erosion of the western part of the islands

shoreline response to a single shore parallel submerged breakwater submerged breakwaters sbws are becoming a popular option for coastal protection mainly due to their low aesthetic impact on the natural environment however sbws have rarely been employed for coastal protection in the past and therefore their efficacy remains largely unknown the main objective of the present study was to investigate the structural and environmental conditions that govern the mode of shoreline response i e shoreline erosion vs shoreline accretion to sbws the relative importance of the key structural and environmental parameters governing the response mode to a single shore parallel sbw is investigated through a combination of theoretical analysis and numerical modelling using physical considerations a theoretical response function model is derived under several simplifying assumptions including parallel depth contours linear wave theory shore normal waves and no wave current interaction numerical modelling is undertaken with the mike21 model suite to simulate the depth averaged velocity fields without morphological updating due to waves acting on a single shore parallel sbw located on a schematised beach with parallel depth contours in total 92 coupled wave current simulations were undertaken the results indicate that the mode of shoreline response to the sbw can be expressed in terms of the two non dimensional parameters h b h 0 and s b h b 3 2 l b h b 2 a 3 h b 1 2 variables defined in the text c 2010 elsevier b v all rights reserved less

beach nourishments at coolangatta bay over the period 1987 2005 impacts and lessons abstract erosion of the southern gold coast beaches se queensland australia was exacerbated after the extension of the tweed river training walls in the early 1960s to achieve the objective of restoring and maintaining beach amenity significant nourishment works have been undertaken in coolangatta bay over the past 30 years particularly under the tweed river entrance sand bypassing project tresbp since 1995 a number of nourishment campaigns and the implementation of a permanent sand bypass system in 2001 have resulted in significant changes of coolangatta bay morphology the present case study investigates the influence of both wave climate and nourishment works on the area extending from the updrift snapper rocks area to downdrift kirra beach swan spectral wave model is implemented at coolangatta bay area and forced by the global wave model ww3 to estimate wave forcing and the potential natural longshore drift entering in coolangatta specific transects extracted from accurate bathymetric surveys are used to investigate and quantify coolangatta bay sedimentation for the period 1987 2005 a network of argus video stations provides high sample rate information on the shoreline evolution results show that over the past 10 years coolangatta bay has infilled rapidly sedimentation reached up to 6 m in some areas between 1995 and 2005 with beach width increasing by 200 m at kirra beach rapid seaward shoreline migration is consistent with the intense over pumping of sand relative to the natural potential to move sand alongshore the nourishment strategy used during this project has successfully delivered large amounts of sand to the southern gold coast embayment although it has been up to now controversial from many community perspectives the artificial sand bypassing process proved to be much more efficient than depositing the dredged sand in the nearshore area which requires a significant period of low energy condition in order for the deposited sediment to migrate shoreward and weld to the shore this case study confirms that when carefully undertaken sand bypassing is a sustainable and flexible soft engineering approach which can work in concert with natural processes

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

rapid sea level change and coastal evolution on the pacific margin of canada a rapid regression occurred off the northern pacific margin of canada approximately between 14 600 and 12 500 14c years b p contemporary with the deglaciation of the continental shelf primarily due to the rapid isostatic rebound sea level had reached a maximum lowering of greater than 150 m and remained low until approximately 12 400 14c years b p after which a rapid transgression occurred at 12 500 14c years b p the shelf tilt across the northern pacific margin of canada ranged between 50 m of submergence at prince rupert on the british columbia mainland to greater than 150 m of emergence on the western edge of the queen charlotte islands this regressive transgressive cycle lasted only from 5200 to 5500 14c years a result of the development and collapse of a glacioisostatic forebulge sediment supply wave action and tidal current energy are the primary factors that controlled the coastal response to these late quaternary relative sea level changes plate tectonics on the other hand played a secondary role in coastal evolution during deglacial regression extensive glacial outwash and glaciomarine deposition occurred except on the outer coast where sediment was transferred to the shelf break during the transgression of the shelf the sediment supply was primarily restricted to the erosion of the previously deposited deglacial deposits resulting in the formation of drowned wave cut terraces spit platforms and modification of estuarine environments as the sea level rose in steps the present unconsolidated coastline is mostly erosional during the most recent enso event the sea level rise of up to 0 4 m resulted in as much as 12 m of coastal retreat

quantification of sand bar morphology a video technique based on wave dissipation a technique is presented to remotely measure the scales and morphology of natural sand bars based on the preferential dissipation of wind waves and swell over the crests of the bar photographic or video images are recorded and statistical uncertainties associated with incident wave height modulations removed by averaging time exposures ground truth testing of the technique was carried out as part of the superduck experiment in october 1986 the time exposures generally provided a good mapping of underlying morphology allowing detection of the bar and determination of cross shore and longshore length scales however during high waves persistent surface foam obscures the relationship of image intensity to local dissipation modeled theoretically by dissipation of a random wave field and an enhancement technique of image differencing must be done to remove the bias errors in the estimate of bar crest distance from the shoreline are generally less than 35 but this value depends on the geometry of the particular bar logistic simplicity and quantitative capabilities make this technique very attractive

coupling mechanisms in double sandbar systems part 2 impact on alongshore variability of inner bar rip channels double sandbar systems are common morphological features along sandy wave dominated micro to meso tidal coastlines in the companion paper we demonstrated how various alongshore inner bar rip channel patterns can develop through morphological coupling to an alongshore variable outer bar the simulated coupling patterns are however scarcely observed in the field instead inner bar rip channels more often possess remarkably smaller and more variable alongshore length scales suggesting that coupling mechanisms do not play a substantial role in the overall double sandbar dynamics here we use a numerical model to show that the relative importance of self organization and morphological coupling changes in favour of the latter with an increase in waterdepth variability along the outer bar crest furthermore we find that the typical alongshore variability in inner bar rip channel scale is indicative of a mixture of self organization and morphological coupling rather than self organization alone morphological coupling may thus be more important to understanding and predicting the evolution of inner bar rip channels than previously envisaged copyright 2010 john wiley and sons ltd

late quaternary geology and geochronology of the central continental shelf of western canada piston cores and high resolution seismic profiles from queen charlotte sound have yielded new information on the late quaternary history of this part of the western canada continental shelf cores in three major troughs goose island mitchell s and moresby up to 130 km apart sample a similar sedimentary sequence this sequence comprises five units the lowest unit a which is up to 40 m thick is a laminated to massive mud containing coarse ice rafted debris deposited between pre 13 6 ka and 12 9 ka during deglaciation of queen charlotte sound this unit is overlain by a sequence of stratified sediments units b1 b3 up to 20 m thick deposited during the transition from the pleistocene to the holocene unit b1 directly overlies and is similar to unit a but lacks ice rafted detritus unit b2 is sandy mud locally gravelly deposited during a period of lagging and winnowing from about 12 9 to 10 2 ka when sea level in queen charlotte sound was lower relative to the land than it is today unit b3 is a laminated to massive mud similar to unit b1 deposited when water depths in queen charlotte sound rapidly increased at the end of the pleistocene due to the combined effect of eustatic sea level rise and forebulge collapse the sedimentary sequence is capped by up to 10 m of mud unit c which is more organic rich and contains more clay than any of the other units it was accumulating under present day conditions as early as 9 7 k y ago

paleogeography glacially induced crustal displacement and late quaternary coastlines on the continental shelf of british columbia canada abstract subsequent to the last glacial maximum lgm complex isostatic adjustments resulted from deglaciation eustatic sea level change tectonic faulting and a relatively thin flexible lithosphere in the queen charlotte islands qci region a geostatistical interpolation model charts the sequence of evolving landscapes and displays temporal changes in the magnitudes and extent of crustal flexure that accompanied forebulge development on the late quaternary northeast pacific continental shelf between 14 2 and 8 7 ka bp wavelength and forebulge amplitude are consistent with thermal modeling implying low upper mantle viscosity and thin elastic lithospheric thickness beneath queen charlotte qc sound and hecate strait glacial ice 690 m thick began retreating from dixon entrance after 14 5 ka bp 14c years ago and prior to 12 6 ka bp permitting over 100 m of crustal uplift in northern hecate strait a forebulge persisted in hecate strait and qc sound from 13 2 until after 9 7 ka bp implying fixed glacial ice on the british columbia bc mainland until 10 ka bp paleogeographic reconstructions show two emergent ice free terrains one extending eastward from the qci and the other in qc sound by 11 7 ka bp a landbridge connected the bc mainland and the qci

post glacial sea levels on the western canadian continental shelf evidence for rapid change extensive subaerial exposure and early human habitation grounded piedmont type glaciers inundated and isostatically loaded the deep troughs which indent the western canadian continental shelf as far west as the shelf edge glaciers do not appear to have covered the offshore banks east of the queen charlotte islands haida gwaii ice retreated from the shelf at approximately 13 500 14c yr b p rapid emergence of the crust followed the ice retreat and resulted in a relative fall of sea level at 10 400 14c yr b p relative sea level on the continental shelf was more than 100 m below that of today and large areas of the queen charlotte basin were subaerially exposed eustatic sea level rise coupled with subsidence of a glacioisostatic forebulge allowed sea levels to rise very rapidly and reach the present shoreline on the queen charlotte islands haida gwaii by about 9100 14c yr b p dated shoreline deposits shells submerged wood remnants and barnacles on stone tools at elevations between 110 m and 14 m suggest a sea level rise of 6 3 cm per year between 12 200 and 11 000 calender years our reconstructions of the paleogeography and paleoenvironments suggest a hospitable environment for human habitation existed in areas that are now submerged stone tools excavated from intertidal deposits support this interpretation significant local variations in the depth of synchronous shorelines are described and attributed to localized differences in isostatic load the documented rates of crustal adjustment are much greater than those used in conventional geophysical forebulge models regional high resolution seismic reflection data 3400 line km shows little evidence for post glacial faulting and suggest that most crustal adjustments appear to have been isostatically rather than tectonically driven subaerial exposure and subsequent sea level transgression were the dominant post glacial processes that determined the morphology texture and paleoenvironment of the western canadian continental shelf

morphodynamic response of nearshore bars to a shoreface nourishment abstract the autonomous nearshore bar behaviour along the barrier island of terschelling the netherlands is characterised by the presence of net seaward cyclic migrating sand bars generated near the shoreline in 1993 a perturbation of the cyclic bar system was introduced by the implementation of a 2 mm 3 shoreface nourishment supplied to the nearshore bar zone filling up the trough between the middle and outer bar the morphodynamic response of the nearshore bars to the nourishment perturbation is investigated using a bathymetric data set with an alongshore extent of 12 km and sampled for 10 years bar behaviour is quantified in terms of bar crest position in relation to morphometric parameters such as bar depth height width and volume along with a pronounced development of a three dimensional bar system unseen in the autonomous behaviour the nearshore bars exhibited a 6 7 year arrest in their migrational behaviour during which bar morphology remained stable at immediate pre nourishment morphometric values at the subsequent onset of bar movement bars resumed their migration at a rate predicted by autonomous behaviour in parallel development with morphometric parameters along their predicted trends it is shown that the observed onshore transport of nourished sediment in the 6 7 year arrest results from a gradual deepening of troughs cross shore sediment transport modelling is used to assess the effect of the nourishment on yearly averaged onshore short wave nonlinearity and offshore undertow sediment transport rates the gradual reappearance of the pre nourishment bar trough morphology is shown to engender a normalisation in the cross shore distribution of sediment transport rates to pre nourishment rates

controls of local geology and cross shore longshore processes on embayed beach shoreline variability 10 shoreline variability along the 3 6 km long narrabeen beach embayment in se australia is 11 investigated over a 5 year period we apply the one line shoreline change model lx shore 12 which couples longshore and cross shore processes and can handle complex shoreline 13 planforms non erodible emerged headlands and submerged rocky features the model 14 skilfully reproduces the three dominant modes of shoreline variability which are by 15 decreasing order of variance cross shore migration rotation and a third mode possibly 16 related to breathing model results confirm previous observations that longshore processes 17 primarily contribute to the rotation and third modes on the timescales of months to seasons 18 while cross shore processes control the shoreline migration on shorter timescales from hours 19 storms to months additional simulations simplifying progressively the bathymetry show 20 how the inherent geology strongly modulates the spatial modes of shoreline variability the 21 offshore central rocky outcrop is found to limit the rotation in contrast the submerged rocky 22 platforms that extend from the headlands enhance the shoreline rotation mode and increase 23 alongshore variability of the cross shore migration mode owing to increased alongshore 24 variability in wave exposure offshore wave transformation across large scale submerged 25 rocky features and headland shape are therefore critical to contemporary shoreline dynamics 26 2

understanding coastal morphodynamic patterns from depth averaged sediment concentration this review highlights the important role of the depth averaged sediment concentration dasc to understand the formation of a number of coastal morphodynamic features that have an alongshore rhythmic pattern beach cusps surf zone transverse and crescentic bars and shoreface connected sand ridges we present a formulation and methodology based on the knowledge of the dasc which equals the sediment load divided by the water depth that has been successfully used to understand the characteristics of these features these sand bodies relevant for coastal engineering and other disciplines are located in different parts of the coastal zone and are characterized by different spatial and temporal scales but the same technique can be used to understand them since the sand bodies occur in the presence of depth averaged currents the sediment transport approximately equals a sediment load times the current moreover it is assumed that waves essentially mobilize the sediment and the current increases this mobilization and advects the sediment in such conditions knowing the spatial distribution of the dasc and the depth averaged currents induced by the forcing waves wind and pressure gradients over the patterns allows inferring the convergence divergence of sediment transport deposition erosion occurs where the current flows from areas of high to low low to high values of dasc the formulation and methodology are especially useful to understand the positive feedback mechanisms between flow and morphology leading to the formation of those morphological features but the physical mechanisms for their migration their finite amplitude behavior and their decay can also be explored

video monitoring of sandbar shoreline response to an offshore submerged structure at a microtidal beach abstract in early 2013 an 800 m long and 12 m wide submerged breakwater with its crest in 2 m depth was implemented at the wave dominated barred beach of sete se france to fight against erosion and submersion hazards daily video images from april 2011 to april 2016 covering an alongshore distance of 3 5 km are used to analyse the response of both the sandbar s and the shoreline to the structure implementation results show that the breakwater had a profound impact on the nearshore system both shoreward of the structure and well away from it alongshore a progressive rotation and linearisation of the sandbar was observed shoreward of the submerged breakwater this resulted in the splitting of the sandbar adjacent to the structure during a net offshore sandbar migration event driven by a severe storm in december 2013 the typical formation of a salient or tombolo was not observed instead shoreline coupled to the sandbar geometry which resulted in a slight seaward migration of the shoreline in front of the structure overall this study highlights that the role of the sandbar is critical to shoreline response to the implementation of breakwaters on barred beaches

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

microfracturing and regional stress field a study of the preferred orientations of fluid inclusion planes in a granite from the massif central france abstract a study of the deformation of a granitic massif indicates a relationship between palaeostress fields and the geometry of microfractures as defined by fluid inclusion trails that is healed microfractures a statistical study of the distribution of the trails leads to the following conclusions trails exhibit several distinct preferred orientations on the scale of a grain which may be observed in many samples the orientations of the trails are similar to those of micro and mesoscale fractures in the granite and the dominant trail direction is parallel to the main direction of regional shortening thus fluid inclusion trails are mode i cracks which can be used as excellent markers of palaeostress fields

longshore realignment of shore parallel sand bars at wanganui new zealand abstract the disconnection and realignment of shore parallel nearshore sand bars in the longshore direction is a recently identified morphological behaviour which is referred to as bar switching this phenomenon has been observed in data from multi bar coasts in the netherlands in north carolina on the east coast of the usa and on the west coast of the new zealand north island this paper identifies the characteristics of bar switching along a 6 km stretch of coast at wanganui new zealand analysis of a 6 3 yr record of image based morphological data identified nine periods or episodes of bar switching switching occurred within transition zones which had longshore lengths between 500 and 1000 m episodes occurred throughout the study period at intervals ranging from 0 to 64 weeks mean 25 weeks episode duration ranged from 8 to 27 weeks mean 14 weeks episodes tended to occur sequentially at centres located 2000 3000 and 4400 5200 m from the nearby wanganui river mouth which marks the southeastern boundary of the study area two types of switching episodes were identified shoreward propagating episodes originate in the outer surf zone and the location of switching then moves landward by contrast stationary episodes begin and remain within the mid surf zone episodes of bar switching are characterised by strong longshore currents peak significant wave height values that are usually greater than the 1 exceedence level 3 2 m and significant wave heights above the 5 exceedence level 2 6 m for at least 4 5 of the switching period while high energy conditions are necessary for bar switching to occur such energy levels do not always result in this type of morphological behaviour antecedent morphology and other hydrodynamic factors may also play important roles in the morphodynamics of bar switching

spatial and temporal patterns of shoreline change of a 280 km high energy disrupted sandy coast from 1950 to 2014 sw france abstract a dataset of 15 geo referenced orthomosaics photos was generated to address long term shoreline change along approximately 270 km of high energy sandy coast in sw france between 1950 and 2014 the coast consists of sandy beaches backed by coastal dunes which are only disrupted by two wide tidal inlets arcachon and maumusson a wide estuary mouth gironde and a few small wave dominated inlets and coastal towns a time and spatially averaged erosion trend of 1 12 m year is found over 1950 2014 with a local maximum of approximately 11 m year and a maximum local accretion of approximately 6 m year respectively maximum shoreline evolutions are observed along coasts adjacent to the inlets and to the estuary mouth with erosion and accretion alternating over time on the timescale of decades the two inlet sandspit systems of arcachon and maumusson show a quasi synchronous behaviour with the two updrift coasts accreting until the 1970s and subsequently eroding since then which suggests that shoreline change at these locations is controlled by allocyclic mechanisms despite sea level rise and the well established increase in winter wave height over the last decades there is no capture of significant increase in mean erosion rate this is hypothesized to be partly the result of relevant coastal dune management works from the 1960s to the 1980s after a long period of coastal dune disrepair during and after the second world war this study suggests that long term shoreline change of high energy sandy coasts disrupted by inlets and or estuaries is complex and needs to consider a wide range of parameters including non extensively waves tides inlet dynamics sea level rise coastal dune management and coastal defences which challenges the development of reliable long term coastal evolution numerical models

onshore sandbar migration in the surf zone new insights into the wave induced sediment transport mechanisms we present a novel process based morphodynamic model which includes transport processes due to both velocity and acceleration skewness and a new formulation for intrawave motions that successfully simulates observations of onshore sandbar migration results confirm findings of previous studies in which each process was considered separately and in which sediment transport was computed from the observed water motion however our results indicate that accounting for the joint action of both velocity and acceleration skewnesses causes major improvement of the modeled onshore bar migration and is essential to accurately model the evolution of the entire cross shore bottom profile when compared with observations we also demonstrate that the morphodynamics in the shoaling zone are dominated by velocity skewness bed shear stresses while sediment transport induced by acceleration skewness pressure gradients controls the morphodynamics in the inner surf zone

morphodynamic response of a two barred beach to a shoreface nourishment abstract the response to a shoreface nourishment of the two bar system at noordwijk the netherlands is analyzed based on a daily data set of time exposure video images collected during about 6 years complemented with topographic and bathymetric surveys the 1 7 mm 3 nourishment implemented as a 3 km alongshore bump seaward of the outer bar migrated more than 300 m onshore in 4 years before losing its integrity furthermore the nourishment interrupted the autonomous seaward migration of both bars for the entire duration of the study period and allaying earlier fears did not intensify the three dimensional patterns in the bars such as the crescentic plan shape and rip channels the nourishment did result in clear head effects on both flanks with the bar becoming discontinuous and the flank section decaying or becoming attached to an offshore located bar while the section of bar landward of the nourishment became attached to a landward located bar this sequence of morphologies is known as bar switching each switching episode took almost one year to complete and can therefore not be ascribed to individual wave events we suspect that shoreface nourishments enhance the possibility of bar switching by creating alongshore variability in the position and depth of the outer bar and in its cross shore migration rate and direction the noordwijk nourishment did not influence the shoreline position as its trend did not undergo distinctive variations after 1998 differences in the response of the noordwijk sandbars to the shoreface nourishment compared with other dutch nourishments are attributed to the location and size volume per unit length of the nourishment with respect to the sandbars and to the median grain size of the nourished material

submerged late quaternary terrestrial deposits and paleoenvironment of northern hecate strait british columbia continental shelf canada abstract stratigraphic and paleoenvironmental analyses of sediments recovered from cores on the western canadian continental shelf indicate that areas of the north central shelf were subaerial and supported terrestrial vegetation during the regional late wisconsinan deglaciation paleoecological analyses of now submerged shelf sediments reveal a late quaternary treeless environment locally covered by wet sedge tundra samples from a coeval onshore section on eastern graham island indicate that a dwarf shrub tundra with mosses and willows also occupied lowland areas on the queen charlotte islands between 13 and 14 ka ice free subaerial conditions persisted for a period of at least 3200 years on some parts of the emergent shelf between 13 2 and 10 ka during the same time period clay rich glaciomarine sediment with ice rafted debris was accumulating in the troughs of the shelf low relative sea levels during deglaciation on the continental shelf adjacent to the eastern queen charlotte islands suggest that late wisconsinan ice was thin and limited in extent in this area the presence of a habitable lowland environment during this time interval strengthens the view that a coastal migration of humans from beringia was possible along portions of the exposed continental shelf

a record of past ocean atmosphere radiocarbon differences from the northeast pacific a record of the 14c age differences between atmosphere and the mixed layer of the northeast pacific ocean was obtained from 58 radiocarbon measurements on shells and associated wood from coastal sediments in british columbia this series of mixed layer reservoir ages spans the holocene and extends into the period of the younger dryas cold event in the north atlantic and surrounding regions the data reflect the extent of upwelling in the northeast pacific and thus constrain models of carbon cycling and ocean circulation most of the reservoir ages are only slightly less than than the present preindustrial value of about 800 years and may be identical when probable sampling errors are taken into account either the north pacific reached a state close to its present mode of circulation at or before the end of the younger dryas or a different circulation fortuitously produced a similar reservoir age our results support the hypothesis that slow changes in atmospheric radiocarbon concentrations over the holocene arose from 14c production rate changes data corresponding to a radiocarbon age of around 6400 years b p give a reservoir age of 1200 years if this result is confirmed it indicates a much greater variability for the holocene ocean circulation than was previously believed possible

late quaternary paleoenvironments of northwestern north america implications for inland versus coastal migration routes abstract although the long held normative view of new world colonization relies on entrance through an interior ice free corridor by terrestrially adapted big game hunters a recently demonstrated human presence in southern chile dating prior to the existence of the corridor route implies different colonization scenarios which must be seriously considered a renewed focus of archaeological and paleoecological research on early post glacial landscapes in northwestern north america has revitalized the ice free vs coastal corridor controversy geological findings from glacial geology and paleo sea levels support the possibility of coastal migration from beringia to the pacific northwest between about 14 000 and 10 000 bp and preliminary paleoecological data suggest that the coastal landscape was in part vegetated and probably able to support a terrestrial fauna including humans the same cannot be said about the ice free corridor

analysing decadal scale crescentic bar dynamics using satellite imagery a case study at anmok beach south korea abstract understanding long term sandbar dynamics can be crucial for informed coastal zone management but is often hampered by data availability to increase the number of sandbar observations available from bathymetric surveys this study proposes and evaluates a method to manually extract the sandbar location using freely available satellite imagery for the case study of anmok beach in south korea validation of the satellite extracted sandbar locations against 9 in situ measurements shows good agreement with errors well within the pixel resolution of the satellite imagery i e 30 m for landsat missions the applicability of the method is constrained to locations where 1 the cross shore crescentic length scales are larger than the image resolution 2 frequent wave breaking and clouds are absent and 3 the water clarity is sufficient to enable the manual extraction of the sandbar crest line using the additional sandbar observations from the satellite imagery significantly increases the temporal extent and resolution of the dataset for anmok beach this allows the study of sandbar characteristics dynamics and impacts of human interventions to an extent that would not have been possible without the satellite imagery within the study period 1990 2017 it is found that the sandbar maintains a persistent crescentic pattern that is only altered during prolonged and very intense storm conditions the cumulative alongshore migration of the sandbars is investigated and found to be in the order of hundreds of meters over the 27 years study period comparing the sandbar characteristics prior and after the construction of gangneung port shows that both the amplitudes and wavelengths of the sandbar crescents near the port have decreased after its construction

time of maximum late wisconsin glaciation west coast of canada new data from a deep sea core in the eastern north pacific ocean indicate that the western margin of the late wisconsin cordilleran ice sheet began to retreat from its maximum position after 15 600 yr b p ice rafted detritus is present in the core below the 15 600 yr b p level and was deposited while lobes of the cordilleran ice sheet advanced across the continental shelf in queen charlotte sound hecate strait and dixon entrance the core data are complemented by stratigraphic evidence and radiocarbon ages from quaternary exposures bordering hecate strait and dixon entrance these indicate that piedmont lobes reached the east and north shores of graham island part of the queen charlotte islands between about 23 000 and 21 000 yr b p sometime thereafter but before 15 000 16 000 yr b p these glaciers achieved their greatest late wisconsin extent radiocarbon ages of late glacial and postglacial sediments from queen charlotte sound hecate strait and adjacent land areas show that deglaciation began in these areas before 15 000 yr b p and that the shelf was completely free of ice by 13 000 yr b p

late quaternary geology of eastern graham island queen charlotte islands british columbia a reconnaissance study of quaternary sediments exposed in coastal bluffs on eastern graham island has revealed the presence of two major till units each of which is underlain by glaciomarine stony mud outwash sand and gravel and laminated to massive silt and sand of undetermined origin sediment units below the surface drift are older than the radiocarbon dating limit sediments above this drift provide a nearly continuous record of geologic events from before 16 000 years bp until the present stratigraphic evidence and radiocarbon dates indicate that 1 late wisconsin glaciation of the coastal lowlands of graham island was weak and of short duration and 2 a period of low sea levels during late pleistocene time was followed by a transgression that culminated about 7500 8000 years ago when the sea was about 15 m higher relative to the land than at present marine regression during middle and late holocene time produced wave cut scarps wave cut benches overlain by littoral sediments bars spits and beach and dune ridges