layer thicknesses and velocities of wave overtopping flow at seadikes abstract seadikes often fail due to wave overtopping and a failure of the landward slope therefore these aspects have to be taken into account for the design of seadikes in present design the calculation of the crest height of seadikes is essentially based on using a design water level and the corresponding wave run up height an average overtopping rate is generally considered for wave overtopping which can not account for the stresses and other effects due to extreme individual overtopping events landward slope design is more or less based on experience it can be concluded from failure analysis that dike failures on the landward slope are rather initiated by individual overtopping events in particular by the related overtopping flow velocities and layer thicknesses which are relevant for the prediction of erosion infiltration and slip failure therefore overtopping flow velocities and layer thicknesses are required in addition to average overtopping rates as hydraulic boundary conditions for the geotechnical stability analysis of seadikes the objective of the present paper is the theoretical and experimental determination of overtopping flow velocities and layer thicknesses on the seaward slope the dike crest and the landward slope of a seadike overtopping parameters are derived on the basis of small scale model tests which are required for the design of the landward slope and to avoid dike failures by wave overtopping in the future for the prediction of the layer thicknesses and the velocities of the overtopping flow on the seaward slope the dike crest and the landward slope a set of theoretical formulas is derived and validated by hydraulic scale model tests

tracking paleozoic evolution of the south korean peninsula from detrital zircon records implications for the tectonic history of east asia abstract the southern part of the korean peninsula preserves important records of the paleozoic evolutionary history of east asia here we present shrimp u pb ages of detrital zircon grains from paleozoic metasedimentary successions okcheon and joseon supergroups yeoncheon group taean formation and pyeongan supergroup that are incorporated into the major phanerozoic mountain belts okcheon and hongseong imjingang belts in south korea providing new insights for provenances and paleotectonic evolution of the south korean peninsula during paleozoic time the zircon ages from our samples display two distinct spectra patterns in their presence absence of neoproterozoic and or paleozoic populations our results together with the available data from the korean peninsula suggest that 1 the early to middle paleozoic successions in the okcheon belt were deposited in continental margin setting s formed by neoproterozoic intracratonic rifting 2 the middle paleozoic metasedimentary rocks in the imjingang belt can be interpreted as molasse and flysch sediments along an active continental margin 3 the late paleozoic to early triassic taean formation along the western gyeonggi massif represents a syn to post collision deltaic complex of a remnant oceanic basin and 4 the late paleozoic to possibly early triassic pyeongan supergroup in the okcheon belt might represent a wedge top and or foreland basin the spatial and temporal discrepancy between the south korean peninsula and the central china orogenic belt during paleozoic might reflect lateral variations in crustal evolution history along the east asian continental margin during the paleo tethyan ocean closure

distribution of individual wave overtopping volumes on mound breakwaters abstract conventional mound breakwaters are usually designed to withstand low mean wave overtopping discharges and a low proportion of overtopping waves pow existing formulas to estimate pow and maximum individual wave overtopping volume are usually based on tests with high pow this study is focused on mound breakwaters subjected to pow

a new method to estimate the overtopping and overflow discharge at over washed and breached dikes abstract most of the experience collected on wave overtopping is concentrated on emerged or zero freeboard structures and only few experiments are available on over washed dikes the experience on submerged crest conditions is principally related to rubble mound structures and limited to the wave reflection and transmission processes the existing tools for the prediction of the average wave overtopping discharge q at dikes are therefore targeted to represent overtopped structures leading to cautious estimates at over washed dikes and unrealistic overestimations in case of catastrophic scenarios such as breached dikes this paper proposes a new conceptual and practical method for the prediction of q that is valid for both over washed and fully breached dikes it consists of three physically based formulae whose coefficients are fitted on a new numerical database of smooth structures under variable wave attack the predictions are compared with the new numerical results and the data and the tools available from the literature i e experimental data formulae and neural network the new method gives a more realistic representation of the overtopping and overflow processes reducing significantly the overestimation in case of breaching and being at least as accurate as the existing tools in case of over washing

contrasting sources for glacial and interglacial shelf sediments used to interpret changing ice flow directions in the larsen basin northern antarctic peninsula abstract marine sediment cores from the former larsen a ice shelf area reveal three lithological units deposited during ice sheet advance and retreat from the continental shelf the uppermost unit 1 consists of a diatom bearing silty clay with sparse ice rafted debris ird clasts include rock types which can all be matched to onshore outcrops along the eastern side of the antarctic peninsula most clasts are very angular angular or subangular the clasts in this unit are interpreted as supraglacial or englacial debris deposited below an ice shelf distal from the grounding line and or by icebergs in an open marine setting during the holocene in the underlying units 2 and 3 clast lithologies are quite different and mainly comprise cretaceous and jurassic sedimentary rocks these lithologies were derived locally from the continental shelf the larsen basin rather than the limited onshore outcrops of the 2750 clasts studied in units 2 and 3 most are subrounded or subangular and some are striated unit 2 is interpreted as being deposited beneath an ice shelf proximal to the grounding line unit 3 is interpreted as subglacial diamict deposited by grounded ice flowing across the shelf during the last glacial period the availability of sedimentary rocks at the seabed may have facilitated the development of a deforming till layer with low shear strength i e soft or deformation till within unit 3 there are no consistent differences in clast composition or roundness between the deformation till which was probably deposited at the base of an ice stream and an underlying till with high shear strength i e stiff till on the inner shelf where the bedrock lies very close to the seabed clast composition in the subglacial diamicts affords a way of identifying the presence of mesozoic stratigraphic units the contrasting provenance of the coarse fraction between unit 1 and units 2 and 3 is used to interpret ice sheet basal thermal regime and produce a conceptual model of changing palaeo flow directions between glacial and interglacial periods grain roundness and petrology are shown to be a potent method for interpreting different glacial interglacial processes and environments

an analytical model of wave overtopping flow velocities on dike crests and landward slopes abstract an accurate description of the maximum flow velocity across flood protective structures is necessary in order to determine the stability of the landward slope and the amount of cover erosion in this paper two new formulas are derived to describe the change in the maximum overtopping flow velocity along the dike crest and the adjacent landward slope these formulas are coupled in an effort to accurately predict the velocities in wave overtopping events this analytical model is validated using 244 data points from flume tests and 300 data points from field tests on river dikes in the netherlands the modelled flow velocity shows good agreement with the measured flow velocity with a nash sutcliffe efficiency factor varying from 0 49 to 0 87 also the derived formulas are compared with existing formulas for wave overtopping flow velocities and overall showed a better performance for a wide range of geometries and covers

geodynamics of heterogeneous gold mineralization in the north china craton and its relationship to lithospheric destruction abstract the north china craton ncc hosts some of the world class gold deposits on the globe which can be classified into distinct types as the jiaodong type explosive breccia type and skarn type the jiaodong type gold deposits were formed at ca 120 130 ma both in the margins and interior of the ncc two explosive breccia gold deposits formed at ac 180 ma and 120 ma and are located in the southern margin and the interior of the ncc important skarn gold deposits of ca 128 ma formed within the interior of the ncc although the formation and distribution of these gold deposits are temporally and spatially heterogeneous they are commonly related with the lithospheric destruction of the ncc the interplay of several factors such as basement architecture inhomogeneous decratonization crust mantle interaction mantle dynamics magmatic characteristics high heat flow and massive flux of deep derived ore forming fluids operated in generating the gold endowment all the three types of gold systems are closely related with granitoid plutons and different types of dykes the magmas for which were sourced from the lower crust near the moho discontinuity and involved the mixing and mingling of felsic and mafic magmas the ore forming fluids display prominent magmatic signature and were largely derived from deep domains with probable input from the asthenosphere mantle the heterogeneous distribution of the giant gold systems in the ncc was geodynamically controlled by the destruction of the craton the regions at the confluence of two or three precambrian micro continental blocks are generally characterized by thinned lithosphere and high heat flow constituting the potential sites of giant gold deposits the mantle beneath these regions shows em2 characteristics implying the involvement of subducted oceanic components the magmatic intrusions associated with the gold systems crystallized under high oxygen fugacity conditions and were rich in volatiles

numerical simulation of wave overtopping at coastal dikes and low crested structures by means of a shock capturing boussinesq model abstract in this paper a shock capturing numerical model based on the combined solution of boussinesq and nonlinear shallow water equations is applied to the simulation of wave runup overtopping and wave train propagation over impermeable emerged and low crested structures in order to improve the performances of the scheme at wet dry interfaces a numerical treatment is introduced to provide well balancing of advective fluxes and source terms one and two dimensional test cases are presented to validate the performances of the model under both regular and irregular wave conditions

probability distribution of individual wave overtopping volumes for smooth impermeable steep slopes with low crest freeboards abstract several studies showed that the probability distribution of the wave by wave individual overtopping volumes of traditional sea defense structures is described by a weibull distribution with a shape factor b 0 75 those structures typically feature relatively large crest freeboards for the particular design applications of overtopping wave energy converters and smooth dikes in severe storm conditions knowledge is required on the probability distribution of the individual overtopping volumes of smooth structures with relatively low crest freeboards this study contributes to a better knowledge on that distribution by analyzing the individual overtopping volumes obtained from new experiments on smooth structures with relatively small crest freeboards 0 10

an analysis of the downward flushing flow on the crest of a levee under combined wave and surge overtopping abstract in extreme storm conditions a levee would be subject to a combination of wave overtopping and surge overflow namely combined wave and surge overtopping which is easier to induce catastrophic levee failures than common wave overtopping one of the significant differences between combined wave and surge overtopping and wave overtopping is that downward flushing flows are formed on the levee crest during combined wave and surge overtopping due to plunging breakers downward flushing flow might induce lining damage and thus lead to the failure of levees in this paper the downward flushing flow on the levee crest are investigated based on the measurements of full scale flume tests on combined wave and surge overtopping firstly the occurrence probabilities and velocity magnitudes of downward flushing flow are analyzed on the basis of the time series of instantaneous two dimensional flow velocity measured on the levee crest a general portray of the downward flushing flow is given based on the analysis furthermore the individual downward flushing flow processes induced by individual waves are distinguished from the time series of flow velocity and studied in different flow directions empirical formulae are proposed to estimate the occurrence probabilities mean velocities and velocity distributions of individual downward flushing flow processes the results can provide references for laboratory and field tests on levee linings under extreme overtopping conditions

the building of an archean microcontinent evidence from the north china craton abstract continents on the early earth are considered to have been built through the accretion of microterranes oceanic arcs and plateaus the north china craton ncc envisaged in recent models as a collage of several microblocks which were amalgamated along multiple zones of ocean closure during the late neoarchean provide a typical case to investigate the origin and amalgamation of microcontinents through convergent margin processes here we report a suite of magmatic rocks developed at the periphery of one of these microblocks the jiaoliao block that forms part of the composite eastern block of the ncc we integrate our new data with those from various parts of this microblock to elucidate the mechanism of continent building in the archean we present petrological geochemical and zircon u pb geochronological and lu hf isotopic data from the magmatic suite that belongs to the yishui complex geochemically the felsic units of the suite straddle from monzonite through granodiorite to granite with dominantly metaluminous affinity magnesian composition and arc related features the metagranites ttg gneisses and charnockites are characterized by negative nb ta anomalies and positive k and pb anomalies the diorites and gabbros display negative anomalies of th u nb ta and zr hf and positive anomalies at ba pb and sm with negative eu anomalies and minor positive ce anomalies attesting to arc related features in the tectonic discrimination diagrams the rocks plot in the volcanic arc field indicating arc related origin in subduction setting zircon grains from all the rocks display core rim texture with the cores showing magmatic crystallization and the narrow structureless rims corresponding to metamorphic overgrowth the magmatic zircons from the metagranites show upper intercept ages or 207 pb 206 pb weighted mean ages of 2505 29 ma and 2569 20 ma to 2513 27 ma those from the ttg gneisses show 2535 17 ma to 2546 39 ma from charnockites display 2543 20 ma 2555 15 ma and diorite and gabbro show 2587 15 ma and 2516 13 ma respectively the zircon rim ages of 2472 23 ma 2457 35 ma 2545 30 ma and 2511 35 ma suggest the timing of metamorphism ca 2 55 2 45 ga magmatic zircons with slightly older ages of ca 2 73 ga 2 64 ga also occur suggesting multiple magmatic pulses the lu hf isotopic data show positive ehf t values ranging from 0 2 to 5 7 for metagranites with hf model ages of 2602 2815 ma t dm and 2658 3002 ma t dm c whereas for ttg gneisses the positive ehf t values are up to 6 5 and display dominant mesoarchean hf model ages with limited early neoarchean hf model ages charnockite samples show positive ehf t values 2 3 5 7 and display the hf model ages ranging from 2601 ma to 2772 ma t dm and 2658 ma to 2904 ma t dm c diorite and gabbro also show positive ehf t 2 3 6 9 and yield hf model ages of 2625 2788 ma t dm and 2647 ma to 2903 ma t dm c the hf isotopic data indicate that the magmas were derived from neoarchean mesoarchean juvenile sources integrating our data with those from the entire jiaoliao microblock reveals vestiges of hadean crust involved in building the eoarchean nucleus of this microblock vigorous convergent margin processes ranging from mesoarchean to late neoarchean with multiple pules of arc magmatism associated with subduction tectonics led to further growth of continental crust culminating in paired high temperature and high pressure metamorphism during late neoarchean early paleoproterozoic transition

individual wave overtopping volumes on mound breakwaters in breaking wave conditions and gentle sea bottoms abstract mound breakwaters are usually designed to limit the mean wave overtopping rate q or the maximum individual wave overtopping volume vmax however rarely do studies focus on wave overtopping volumes on breakwaters in depth limited breaking wave conditions this study analyzes 2d physical tests on mound breakwaters with relevant overtopping rates 0 33 rc hm0 2 83 and three armor layers cubipod 1l rock 2l and cube 2l in depth limited breaking wave conditions 0 20 hm0 hs 0 90 and with two bottom slopes m 1 25 and m 1 50 the 2 parameter weibull distribution was used to estimate vmax vmax ghm0t012 with coefficient of determination r2 83 3 in this study the bottom slope m 1 50 and m 1 25 did not significantly influence vmax or the number of overtopping events now during the design phase of a mound breakwater q is required to use the methods given in the literature to estimate vmax thus q must be estimated for design purposes when measured q is not available in this study clash neural network clash nn was used to estimate q with r2 63 6 if the 2 parameter weibull distribution proposed in this study is used to estimate vmax with q estimated using clash nn the prediction error of vmax is r2 61 7 with the method presented in this study the ratio between estimated and measured vmax falls within the range 1 2 to 2 90 error band when q is estimated with clash nn the new estimators derived in this study provide good predictions of now and vmax with a method simpler than those in the literature on overtopped mound breakwaters in depth limited breaking wave conditions on gentle sea bottoms 1 50 m 1 25

prediction model of the collapse of bank slope under the erosion effect of wind induced wave in the three gorges reservoir area china during the storage period of the three gorges reservoir the bank erosion caused by wind induced wave is getting more serious especially for the crushed stone soil bank the continuous wave scouring and erosion destabilize the bank slope and even induce the occurrence of landslides based on the energy conservation theory the bank slope will reach a stable state after continuous wave erosion regarding this this paper derives the prediction formula of the stable slope angle and erosion width when the wave erodes the crushed stone soil bank slope model tests on bank slopes with different dry densities and different crushed stone contents under the action of waves were conducted to observe the erosion process of wave induced crushed stone soil bank slope and verify the proposed prediction formula the results show that under the action of wave erosion erosion ridge and collapse steep angle would form at the upper edge of the bank slope and the controlling factors of this process are the dry density of the crushed stone soil and the wave energy when the content of crushed stone soil gradually increases the ability of the bank slope to resist wave erosion weakens at first and then gradually strengthens comparing the erosion stable slope angle obtained from the model tests with the calculated results using the proposed prediction formula a linear relationship could be observed indicating that the proposed prediction formula is reliable for further analysis

spatial distribution of wave overtopping water behind coastal structures spatial distribution of random wave overtopping water behind coastal structures was investigated using a numerical model based on reynolds averaged navier stokes solver rans and volume of fluid vof surface capturing scheme rans vof the computed spatial distributions of wave overtopping water behind the structure agree well with the measurements by pullen et al 2008 for a vertical wall and lykke andersen and burcharth 2006 for a 1 2 sea dike a semi analytical model was derived to relate spatial distribution of wave overtopping water behind coastal structures to landward ground level velocity and layer thickness on the crest this semi analytical model agrees reasonably well with both numerical model results and measurements close to coastal structures our numerical model results suggest that the proportion of wave overtopping water passing a landward location increases with a seaward slope when it is less than 1 3 and decreases with a seaward slope when it gets steeper the proportion of wave overtopping water passing a landward location increases with landward ground level and overtopping discharge it also increases with the product of incident wave height and wavelength but decreases with increasing relative structure freeboard and crest width we also found that the extent of hazard area due to wave overtopping is significantly reduced by using a permeable structure crown findings in this study will enable engineers to establish the extent of hazard zones due to wave overtopping behind coastal structures

extreme coastal responses using focused wave groups overtopping and horizontal forces exerted on an inclined seawall abstract total wave group overtopping and maximum horizontal force responses are investigated for an idealised seawall dike on a plane beach subject to compact focused wave attack using both laboratory and numerical wave flumes the wave group interactions have very short durations such that extraneous reflections from the wavemaker arrive long after the main interaction these short test durations facilitate the use of large ensembles of tests to explore the sensitivity of overtopping and force responses to variations in focus location phase angle at focus and linear focus wave amplitude the scope of the laboratory wave flume tests is broadened by accurate numerical simulation based on a 1dh hybrid boussinesq nlsw model for a given focus location and linear focused wave amplitude variations in phase lead to an order of magnitude change in the group overtopping volume substantial increases in overtopping volume owing to the use of linear wavemaker theory compared to second order theory are also observed these observations have implications for phase independent empirical relationships derived using linear paddle signals in physical experiments examination of the incidence of wave groups parametrically optimised for maximum and minimum overtopping volumes indicates that the overtopping volume may be optimised by minimising reflections of pre overtopping waves within the group while maximising the amplitude of the first overtopping bore numerical predictions of horizontal seawall forces are obtained using fluid impulse derivatives and hydrostatic pressures obtained from the shallow water model within the shallow water model framework hydrodynamic force contributions included in the fluid impulse method are observed to be small relative to the hydrostatic pressure force the parametric dependence of the horizontal non impulsive forces on the seawall is very similar to that of the overtopping volumes with clear bands of large values observed as a function of phase and focus location for a given amplitude this suggests that the parametric optimisation of focused wave groups is a robust method for the investigation of multiple coastal responses such as overtopping forces and runup

wave run up and overtopping reduction by block revetments with enhanced roughness abstract block revetments that are placed in special patterns in a way that lower standard sets are surrounded by sets of higher protruding units have been studied by means of physical model tests this paper focuses on prediction formulae for the wave run up and wave overtopping reduction by means of special pattern block revetments this reduction is significant and leads to lower crest levels of dikes reducing or limiting crest levels without reducing safety is often a preferred solution in areas where dikes form an integral part of the existing area and where raising dikes will lead to social drawbacks or a negative impact on the landscape

intra oceanic arcs of the paleo asian ocean abstract the paper reviews and integrates geological geochronological geochemical and isotope data from 21 intra oceanic arcs ioa of the paleo asian ocean pao which have been identified in the central asian orogenic belt the world largest accretionary orogeny the data we discuss structural position of intra oceanic arc volcanic rocks in association with back arc terranes and accretionary complexes major periods of intra oceanic arc magmatism and related juvenile crustal growth lithologies of island arc terranes geochemical features and typical ranges of nd isotope values of volcanic rocks four groups of ioas have been recognized neoproterozoic early cambrian early paleozoic middle paleozoic and late paleozoic the neoproterozoic early cambrian or siberian group includes eleven intra oceanic arcs of eastern and western tuva sayan southern siberia russia northern and southwestern mongolia and russian altai the early paleozoic or kazakhstan group includes selety urumbai bozshakol chingiz and baydaulet aqastau arc terranes of the kazakh orocline the middle paleozoic or southern group includes six arc terranes in the tienshan orogen chinese altai east kazakhstan west junggar and southern mongoia only one late paleozoic intra oceanic arc has been reliably identified in the caob bogda in the chinese tienshan probably due to pao shrinking and termination the lithologies of the modern and fossil arcs are similar although the fossil arcs contain more calc alkaline varieties suggesting either their more evolved character or different conditions of magma generation of special importance is identification of back arc basins in old accretionary orogens because boninites may be absent in both modern and fossil ioas the three typical scenarios of back arc formation active margin rifting intra oceanic arc rifting and fore arc rifting were reconstructed in fossil intra oceanic arcs some arcs might be tectonically eroded and or directly subducted into the deep mantle therefore the structural and compositional records of fossil intra oceanic arcs in intracontinental orogens allow us to make only minimal estimations of their geometric length life span and crust thickness

modelling of velocity and turbulence fields around and within low crested rubble mound breakwaters abstract a description of the progress achieved within delos environmental design of low crested coastal defence structures eu project in the modelling of wave interaction with low crested structures lcs is presented in this paper emphasis is put on the description of the near field flow especially the velocity and turbulence distribution around and inside lcs as required by other researchers in the project two dimensional varans and three dimensional les numerical modelling has been considered the two dimensional model has been extensively validated with delos laboratory data as shown in garcia et al garcia n lara j l losada i j 2004 2 d numerical analysis of near field flow at low crested breakwaters coastal engineering elsevier 51 10 991 1020 a system of flow recirculation is included in both the experimental and numerical set ups for a correct description of the 2dv velocity field in the vicinity of the structure further validation is presented in this paper laboratory tests on two values of crest width have been simulated in order to analyse relevant near field flow features related to a variation of the geometric configuration of the structure the width of the breakwater crest is seen to significantly influence the wave breaking induced flow pattern at the structure magnitudes such as turbulent kinetic energy tke tke dissipation rate shear stresses and reynolds stresses are computed around and inside the breakwater the three dimensional model numerical results are compared with results of wave basin experiments showing a good agreement for instantaneous free surface numerical results of the flow over the breakwater and around the breakwater head are also presented

character of clasts in glaciomarine sediments as an indicator of transport and depositional processes weddell and lazarev seas antarctica abstract the gravel component in marine sediments on the continental margin of antarctica is almost entirely from transport by grounded ice ice shelves ice tongues and icebergs about 2000 gravel clasts from about 40 sites were examined for roundness zingg shape and krumbein sphericity surface characteristics like faceting striations and other specific glacigenic shapes were recorded as well as lithology the samples were from both shallow and deep waters along 1500 km of the antarctic margin bordering the eastern weddell sea and lazarev sea in addition onshore observations were made in ice marginal areas at schirmacher oasis few systematic differences in clasts shape in modern sediments could be detected among the various glaciological environments variation in shape within a given environment is greater than that between different environments abrasion of clasts at the interface between glacier and bedrock before transport into the ocean is less important than in temperate regions this reflects the cold thermal regime of antarctic glaciers a view confirmed by the similarity in shape of debris from basal ice and from sandy basal tills at schirmacher oasis more angular debris was recovered off grounded ice margins in coats land but given the absence of supraglacial sources this debris seems to be the product of rock fracturing at a relatively dry frozen ice bed more than half and sometimes nearl all the clasts are faceted faceting roundness and sphericity are independent of lithology in contrast striae on clasts are strongly dependent on lithology few gneissic clasts have striae but nearly half the clasts of fine grained basic igneous or metavolcanic rocks are striated each area studied has a distinct population of rock types of limited variety suggesting that deposition is predominantly from the nearest land ice source and that mixing of sediment with that from far traveled icebergs is unimportant

2d numerical simulation of large scale physical model tests of wave interaction with a rubble mound breakwater abstract experimental measurements on a large scale multi layered breakwater model are used to extensively validate a numerical model for wave interaction with permeable coastal structures built in a generic multiphysics cfd code flow 3d a novel contribution to this code is the implementation of the piston type wave maker with active wave absorption the use of active absorption is crucial to maintain an accurate and stable incident wave field in the validation test series with long duration due to the nonbreaking wave conditions the model setup is simplified to two dimensions and single phase laminar flow in the clear fluid region the validation includes a verification of the incident wave field and a detailed study of the hydrodynamics of the flow field within the breakwater the evolution of experimentally measured free surface elevations in and outside the breakwater shows a good agreement with numerical predictions numerical results of pore pressure height throughout the breakwater core are generally corresponding well with experimental values except for a limited zone near the free surface where a clear reduction of the pore pressure is measured due to the effect of air entrainment this validation study using large scale model tests proves that this model and by extension the nowadays standard branch of vof based navier stokes models are a useful tool in predicting wave interaction with permeable coastal structures the study also reveals that it is possible to achieve a level of accuracy that can be considered sufficient for engineering applications even when using some model simplifications in particular those related to the treatment of the aerated turbulent flow on and inside the armor layer

neogene glacigenic debris flows on james ross island northern antarctic peninsula and their implications for regional climate history detailed sedimentological and microtextural analyses of newly discovered late neogene diamictites and other coarse grained facies mostly sandwiched between hyaloclastite of the james ross island volcanic group and cretaceous sandstone and mudstone indicate deposition mainly by glacigenic debris flows the deposits on james ross island northern antarctic peninsula constrain the depositional setting ice bed dynamics and regional palaeoclimate the sequences on james ross island vary in age but are mainly late miocene and pliocene unlike neogene sedimentary sequences elsewhere in antarctica those on james ross island are unusually well dated by a combination of 40ar 39ar and 87sr 86sr analyses on fresh interbedded lavas and pristine bivalve molluscs respectively the sr isotopic ages of the debris flows cluster around 4 74 4 89 5 44 5 78 and 6 31 ma and probably date relatively warm periods in the northern antarctic peninsula region when the bivalves lived under ice poor or seasonally ice free conditions the bivalves are often remarkably well preserved lack adhering lithified sediment and in at least two locations are large mainly unfragmented and sometimes articulated suggesting that they were alive immediately prior to their incorporation in subaqueous debris flows at the margins of an advancing glacier these fossiliferous glacigenic debris flows signify episodes of ice expansion during relatively warm periods or interglacials of the late miocene and pliocene the james ross island glacigenic sedimentary successions attain thicknesses of up to 150 m and extend over 4 km laterally the high volume of glacigenic sediment delivery implicit in the james ross island successions indicates that a series of dynamic ice fronts crossed the region during the late miocene and pliocene epochs associated evidence in the form of clast abrasion including striations and faceting and bedrock erosion is indicative of basal sliding and subglacial sediment deformation active at the ice bed interface and wet based temperate or polythermal regimes prior to remobilisation the evidence further suggests two local ice caps on james ross island during the warm periods as well as ice overriding by the antarctic peninsula ice sheet from the west and northwest

breaking waves over a mild gravel slope experimental and numerical analysis 1 an experimental and numerical study of the effects of a gravel slope on wave shoaling and breaking is presented herein in the laboratory experiments fluid velocities pressure and water surface elevations were measured experiments were conducted for both spilling and plunging breakers and for gravel slopes with different gravel sizes since gravel slopes caused additional energy dissipation wave heights in the shoaling zone as well as at the breaking point were reduced on the other hand the mean free surface setup inside the surf zone increased it was also observed that the gravel slope had a stronger influence on the vertical profile of undertow under spilling breaker than on that under a plunging breaker moreover the undertow became weaker over a gravel slope with a larger gravel size outside the surf zone turbulent velocities near the gravel slope were relatively high because of the bottom roughness and percolation inside the surf zone turbulence generated by wave breaking dominated over the gravel bed generated turbulence the vertical flow induced by the gravel slope changed the turbulence pattern only at cross sections very close to the shoreline numerical simulations of the wave breaking processes over a gravel slope were performed the numerical model was tested by comparing numerical results with experimental data the model accurately simulated the mean flow quantities the magnitude of turbulence and turbulence characteristics were also simulated reasonably well

numerical analysis of the interaction of irregular waves with two dimensional permeable coastal structures abstract this paper will address the validation and application of a volume of fluid method for coastal structures under the influence of normal incident irregular wave fields several physical processes will be addressed as part of the validation process namely i wave reflection from permeable and impermeable structures ii wave transformation over a small shoal iii wave damping inside of a permeable structure iv the resulting wave induced internal setup and v wave induced forces the numerical model will be validated against a multiple of experimental data sets for two dimensional coastal problems the impact of air relief gaps on the modelled wave induced pressures on a crest wall is analysed for the two dimensional layout of the structure this is analysed to study the importance of the cushion effect from the incompressible air phase subsequent to the validation of the numerical model the internal setup in permeable coastal structures is given separate attention a combination of an analytical prediction of the magnitude of the internal setup and numerical results is used to derive numerically based empirical formulae for the magnitude and the time scale of the internal setup the formulae include the effects of wave height wave period material properties of the coastal structure and the dimensions of the structure the numerical model is based on the openfoam cfd toolbox

numerical modelling of short and long wave transformation on a barred beach abstract this work aims to demonstrate an advancement towards the integrated modelling of surf zone hydrodynamics by means of a vof type numerical model cobras uc based on the reynolds averaged navier stokes equations in this paper the numerical model is adapted and validated for the study of nearshore processes on a mildly sloping beach the model prediction of wave energy transformation and higher order statistics skewness and asymmetry are in good agreement with detailed laboratory observations from a barred beach boers m 1996 simulation of a surf zone with a barred beach report 1 wave heights and wave breaking tech rep 96 5 comm on hydrol and geol eng dept of civil engineering delft university of technology moreover the numerical model allows us to study the low frequency motions inside the surf zone it is found that in order to achieve a satisfactory simulation of both short and long wave transformation the numerical model must achieve i the simultaneous second order wave generation and absorption ii the energy transfer between triad of components iii the short and long wave energy dissipation inside the surf zone and iv the wave reflection at the shoreline comparisons between numerical and experimental results demonstrate the model capability to satisfactorily simulate all the aforementioned processes

a numerical model of wave overtopping on seadikes this paper describes the development of a numerical model for wave overtopping on seadikes the model is based on the flux conservative form of the nonlinear shallow water equations nlsw solved with a high order total variation diminishing tvd roe type scheme the goal is to reliably predict the hydrodynamics of wave overtopping on the dike crest and along the inner slope necessary for the breach modelling of seadikes besides the mean overtopping rate the capability of simulating individual overtopping events is also required it is shown theoretically that the effect of wave breaking through the drastic motion of surface rollers in the surfzone is not sufficiently described by the conventional nonlinear shallow water equations neglecting wave setup from the mean water level and thus markedly reducing the model predictive capacity for wave overtopping this is significantly improved by including an additional source term associated with the roller energy dissipation in the depth averaged momentum equation the developed model has been validated against four existing laboratory datasets of wave overtopping on dikes the first two sets are to validate the roller term performance in improving the model prediction of wave overtopping of breaking waves the last two sets are to test the model performance under more complex but realistic hydraulic and slope geometric conditions the results confirm the merit of the supplemented roller term and also demonstrate that the model is robust and reliable for the prediction of wave overtopping on seadikes

marine geological constraints for the grounding line position of the antarctic ice sheet on the southern weddell sea shelf at the last glacial maximum abstract the history of grounded ice sheet extent on the southern weddell sea shelf during the last glacial maximum lgm and the timing of post lgm ice sheet retreat are poorly constrained several glaciological models reconstructed widespread grounding and major thickening of the antarctic ice sheet in the weddell sea sector at the lgm in contrast recently published onshore data and modelling results concluded only very limited lgm thickening of glaciers and ice streams feeding into the modern filchner and ronne ice shelves these studies concluded that during the lgm ice shelves rather than grounded ice covered the filchner and ronne troughs two deep palaeo ice stream troughs eroded into the southern weddell sea shelf here we review previously published and unpublished marine geophysical and geological data from the southern weddell sea shelf the stratigraphy and geometry of reflectors in acoustic sub bottom profiles are similar to those from other west antarctic palaeo ice stream troughs where grounded ice had advanced to the shelf break at the lgm numerous cores from the southern weddell sea shelf recovered sequences with properties typical for subglacially deposited tills or subglacially compacted sediments these data sets give evidence that grounded ice had advanced across the shelf during the past thereby grounding in even the deepest parts of the filchner and ronne troughs radiocarbon dates from glaciomarine sediments overlying the subglacial deposits are limited but indicate that the ice grounding occurred at the lgm and that ice retreat started before 15 1 corrected 14c kyrs before present bp on the outer shelf and before 7 7 corrected 14c kyrs bp on the inner shelf which is broadly synchronous with ice retreat in other antarctic sectors the apparent mismatch between the ice sheet reconstructions from marine and terrestrial data can be attributed to ice streams with very low surface profiles similar to those of ice plains that had advanced through filchner trough and ronne trough at the lgm considering the global sea level low stand of 130 m below present a low surface slope of the expanded lgm ice sheet in the southern weddell sea can reconcile grounding line advance to the shelf break with limited thickening of glaciers and ice streams in the hinterland this scenario implies that ice sheet growth in the weddell sea sector during the lgm and ice sheet drawdown throughout the last deglaciation could only have made minor contributions to the major global sea level fluctuations during these times

forces on a vertical wall on a dike crest due to overtopping flow abstract wave overtopping a sea dike may pose a threat to people and property however knowledge of the overtopping features in particular overtopping flow loads are not well understood the aim of this study was to understand the overtopping process on a dike crest and to develop an empirical formula for the resulting overtopping flow impact loads on a wall as a function of the property of the incoming waves and dike geometry characteristics in this paper we propose a new descriptor the overtopping momentum flux in order to predict the impact loads to validate the proposed empirical function a series of physical scale model tests was conducted in these experiments we measured the overtopping flow loads on a vertical wall at different locations on a dike which were induced by broken waves a correction coefficient for the wall effect on the initial flow depth and an empirical initial flow depth coefficient for a broken wave were determined these empirical coefficients allowed for an interpretation of the overtopping process of a broken wave from dike toe up to the front of the wall on the dike

numerical analysis of wave overtopping of rubble mound breakwaters abstract the paper describes the results of a two dimensional 2 d numerical modelling investigation of the functionality of rubble mound breakwaters with special attention focused on wave overtopping processes the model cobras uc is a new version of the cobras cornell breaking waves and structures based on the volume averaged reynolds average navier stokes varans equations and uses a volume of fluid technique vof method to capture the free surface the nature of the model equations and solving technique provides a means to simulate wave reflection run up wave breaking on the slope transmission through rubble mounds overtopping and agitation at the protected side due to the combined effect of wave transmission and overtopping also two dimensional experimental studies are carried out to investigate the performance of the model the computations of the free surface and pressure time series and spectra under regular and irregular waves are compared with the experimental data reaching a very good agreement the model is also used to reproduce instantaneous and average wave overtopping discharge comparisons with existing semi empirical formulae and experimental data show a very good performance the present model is expected to become in the near future an excellent tool for practical applications

impacts on a storm wall caused by non breaking waves overtopping a smooth dike slope abstract will coastal towns survive the rising pressure or better the rising sea level in future decades waves overtop dikes and the overtopping flow on the crest of the dike can cause damage wave impacts from these overtopping flows already became of interest in coastal engineering the past few years but very little literature and almost no design formulae are available yet for irregular waves this paper gives such design formulae for practical use experimental modeling at three different scales small middle and large scale has been carried out to measure such impacts the tested geometry was a smooth sloping dike only non breaking waves with a promenade at crest level and a storm wall at the end of this promenade the outcome of this paper are three methodologies to a calculate wave impact forces on such a storm wall as a function of the hydraulic parameters b determine the weibull distribution of all impacts in one test with the shape and scale parameters also linked to the hydraulic parameters and c to provide an indirect approach to calculate the impact forces on the storm wall in this last approach the distribution of the individual overtopping waves are linked to the distribution of the overtopping flow parameters which are then linked to the distribution of the impact forces finally the empirical formulae from the aforementioned three methodologies are compared analogies and differences are discussed and guidance is provided to design storm walls against post overtopping impact forces results show that forces from waves overtopping the dikes are in the order of 20 to 40 kn m prototype scale in the dimensionless freeboard rc hm0 range of 1 to 2 this is much lower compared to impact forces on vertical walls as calculated by the shore protection manual

laboratory experiments on low crested breakwaters abstract new unique laboratory experiments on low crested structures lcss have been performed within the delos project the experiments were carried out in three european laboratories aiming at extending and completing existing available information with respect to a wide range of engineering design properties such as structural stability wave and current flows and wave transmission 3d wave basin tests were performed to provide information especially about the wave obliquity where almost no research has been done before flow velocities inside and close to the surface of structures were studied in a wave channel at small scale and scale effects regarding wave transmission and reflection were studied in a wave channel at a large scale facility the paper describes the experiments and associated databank with respect to objectives test program set ups and measurements results guidelines and recommendations elaborated from the tests are included in the other companion papers of the coastal engineering special issue on delos

detailed investigation of overwash on a gravel barrier abstract this paper uses results obtained from a prototype scale experiment barrier dynamics experiment bardex undertaken in the delta flume the netherlands to investigate overwash hydraulics and morphodynamics of a prototype gravel barrier gravel barrier behaviour depends upon a number of factors including sediment properties porosity permeability grain size and wave climate since overwash processes are known to control short term gravel barrier dynamics and long term barrier migration a detailed quantification of overwash flow properties and induced bed changes is crucial overwash hydrodynamics of the prototype gravel barrier focused on the flow velocity depth and discharge over the barrier crest and the overwash flow progression across and the infiltration through the barrier during the bardex experiment overwash peak depth 0 77 m velocity 5 m s 1 and discharge max 6 m 3 m 1 were high especially considering the relatively modest wave energy significant wave height 0 8 m conversely to schemes found in the literature average flow depth did not linearly decrease across the barrier rather it was characterised by a sudden decrease at the crest a milder decrease at the barrier top and then propagation as a shallow water lens over the backbarrier the barrier morphological evolution was analysed over a series of 15 min experimental runs and at the timescale of individual overwash events overall the morphological variation did not result from an accumulation of many small consistently erosive or accretionary events but rather the mean bed elevation change per event was quite large 10 mm and the overall morphology change occurred due to a small imbalance in the number of erosive and accretionary events at each location two relationships between overwash hydrodynamic variables were deduced from results 1 between overwash flow depth and velocity a power type relation was obtained and 2 a linear relation was observed between overwash flow depth and maximum overwash intrusion distance across the barrier top i e overwash intrusion findings from this study are useful to enhance the knowledge of overwash processes and also have practical applications on the one hand results shown here can be use for the validation of overwash predictive models and additionally the simple empirical relations deduced from the dataset can be used by coastal managers to estimate overwash intrusion distance which in turn can assist in the location of areas under risk of overwash and breaching

modelling of waves and currents around submerged breakwaters abstract recent experimental data collected during the delos project are used to validate two approaches for simulating waves and currents in the vicinity of submerged breakwaters the first approach is a phase averaged method in which a wave model is used to simulate wave transformation and calculate radiation stresses while a flow model 2 dimensional depth averaged or quasi 3d is used to calculate the resulting wave driven currents the second approach is a phase resolving method in which a high order 2dh boussinesq type model is used to calculate the waves and flow the models predict wave heights that are comparable to measurements if the wave breaking sub model is properly tuned for dissipation over the submerged breakwater it is shown that the simulated flow pattern using both approaches is qualitatively similar to that observed in the experiments furthermore the phase resolving model shows good agreement between measured and simulated instantaneous surface elevations in wave flume tests

wave runup and wave overtopping measurements using a laser scanner abstract the use of a standard laser scanner to measure several hydraulic responses of coastal structures is examined to this end measurements of full scale wave runup on a dike slope in the old delta flume are described and analyzed measurements of the wave runup height with a laser scanner are compared to measurements based on visual observation the signal intensity of the laser reflection is additionally used in the determination of the wave runup height virtual wave overtopping volumes and mean overtopping discharge are determined by considering the maximum water volume above a certain virtual crest level on the dike slope for each runup event the mean wave overtopping discharge that is determined in this manner compares well to accepted formulas for overtopping the technological applicability of the technique is described including postprocessing methods and estimates are made of the accuracy that can be achieved

meltwater intensive glacial retreat in polar environments and investigation of associated sediments example from pine island bay west antarctica abstract modern pine island and thwaites glaciers which both drain into pine island bay are among the fastest changing portions of the cryosphere and the least stable ice streams in antarctica here we show that the uppermost sediment unit in pine island bay was deposited from a meltwater plume a plumite during the late stages of ice sheet retreat 7 8 6 k cal yr bp and argue that this deposit records episodes of meltwater intensive sedimentation the plumite is a hydraulically sorted glacially sourced draping deposit that overlies proximal glacimarine sediments and thickens towards the modern grounding line the uppermost sediment unit is interpreted as a product of non steady state processes in which low background sedimentation in large bedrock carved basins alternates with episodic purging of sediment laden water from these basins the inner part of pine island bay contains several basins that are linked by channels with a storage capacity on the order of 70 km 3 of stagnant water and significant sediment storage capacity purging of these basins is caused by changes in hydraulic potential and glacial reorganization the sediment mobilized by these processes is found here to total 120 km 3 this study demonstrates that episodes of meltwater intensive sedimentation in pine island bay occurred at least three times in the holocene the most recent episode coincides with rapid retreat of the grounding line in historical time and has an order of magnitude greater flux relative to the entire unit we note that the final phase of ice stream retreat in marguerite bay was marked by a similar sedimentary event and suggest that the modern thwaites glacier is poised for an analogous meltwater intensive phase of retreat

toe berm design for very shallow waters on steep sea bottoms abstract the toe berm is a relevant design element when rubble mound breakwaters are built on steep sea bottoms in breaking conditions different design formulas can be found in the literature to predict the damage caused to submerged toe berms placed on gentle bottom slopes however these formulas are not valid for very shallow waters in combination with steep sea bottoms where toe berms receive the full force of breaking waves to guarantee breakwater stability in these conditions new design formulas are needed for toe berms to this end physical model tests were carried out and data were analyzed to characterize rock toe berm stability in very shallow water and with a bottom slope m 1 10 based on test results a new formula was developed with three parameters to estimate the nominal diameter d n 50 of the toe berm rocks water depth at the toe h s deep water significant wave height h s0 and deep water wave length l 0p

maximum overtopping forces on a dike mounted wall with a shallow foreshore abstract the impact force induced by waves overtopping a dike with a vertical wall on its crest and with a shallow foreshore seaward of the dike was studied to this end physical model tests were performed in a wave flume at a typical scale of 1 25 the goal of this study was to develop a method to estimate the maximum forces on the wall during a known storm peak the time series of water depth at toe of the dike flow thickness at seaward edge of the dike crest and impact forces were measured an empirical generalized pareto distribution is verified as the best distribution for the extreme overtopping wave forces

wave overtopping and piling up at permeable low crested structures the paper aims at providing a simple model for evaluating piling up overtopping filtration and rip currents for low crested structures the model is essentially based on mass and momentum balance and on resistance laws that relate piling up and mass fluxes a procedure is suggested and validated against 2d and 3d experimental data this procedure is innovative with respect to existing formulations since it applies both to emerged and submerged structures and it simultaneously accounts for structure permeability return flow through gaps and dissipative effects

laboratory study of combined wave overtopping and storm surge overflow of a levee combined wave overtopping and storm surge overflow of a levee with a trapezoidal cross section was studied in a two dimensional laboratory wave flow flume at a nominal prototype to model length scale of 25 to 1 the goal of this study was to develop design guidance in the aftermath of hurricane katrina time series of water depth at two locations on the levee crown and flow thickness at five locations on the landward side slope were measured along with horizontal velocity near the landward edge of the crown new equations are presented for average overtopping discharge distribution of instantaneous discharge and distribution of individual wave volumes equations are also given for mean flow thickness rms wave height mean velocity and velocity of the wave front down the landward side slope

hydrodynamic and morphodynamic response of isolated and multiple low crested structures experiments and simulations abstract low crested structures for beach defence purposes are frequently configured in the form of cells this paper investigates the hydrodynamic and morphological response of such defence schemes by means of laboratory experiments and numerical simulations experiments were carried out at the large mobile bed basin of the laboratorio di idraulica costiera of the politecnico di bari it tests peculiarity is the simultaneous simulation of three different types of lateral confinement a channel representative of an indefinitely long structure and two areas with narrow and wide gaps representative of a common scheme and of an almost isolated structure respectively submerged zero freeboard and emerged conditions were tested a typical storm of the northern adriatic sea was reproduced by 6 wave attacks water level and currents were measured in front and behind the structures at gaps and roundheads results focusing on rip current intensities and piling up are presented and discussed an extensive plan view of wave intensities and flow patterns inside the basin is provided through numerical simulations with mike 21 numerical suite the sand bed was surveyed along 30 profiles covering the narrow gap area and the isolated structure roundheads for the submerged conditions tests 15 of these profiles and the shoreline position were monitored after each step of the simulated storm average and maximum values of local erosion at the structure toe are presented time evolution of erosion at gaps is related to the main hydrodynamic variables through bijker sediment transport formula evaluation of volume changes in the protected area shows that sand is in average trapped behind the barriers being transported offshore from gaps and returning inshore over the crest the observed and reconstructed transport mechanism is a combination of bed load and suspended transport the latter being slightly more important bed level changes are well predicted by morphodynamic simulations performed with mike 21 cams

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

provenance and dispersal of glacial marine surface sediments in the weddell sea and adjoining areas antarctica ice rafting versus current transport abstract mineralogical and granulometric properties of glacial marine surface sediments of the weddell sea and adjoining areas were studied in order to decipher spatial variations of provenance and transport paths of terrigenous detritus from antarctic sources the silt fraction shows marked spatial differences in quartz contents in the sand fractions heavy mineral assemblages display low mineralogical maturity and are dominated by garnet green hornblende and various types of clinopyroxene cluster analysis yields distinct heavy mineral assemblages which can be attributed to specific source rocks of the antarctic hinterland the configuration of modern mineralogical provinces in the near shore regions reflects the geological variety of the adjacent hinterland in the distal parts of the study area sand sized heavy minerals are good tracers of ice rafting granulometric characteristics and the distribution of heavy mineral provinces reflect maxima of relative and absolute accumulation of ice rafted detritus in accordance with major iceberg drift tracks in the course of the weddell gyre fine grained and coarse grained sediment fractions may have different origins in the central weddell sea coarse ice rafted detritus basically derives from east antarctic sources while the fine fraction is discharged from weak permanent bottom currents and or episodic turbidity currents and shows affinities to southern weddell sea sources winnowing of quartz rich sediments through intense bottom water formation in the southern weddell sea provides muddy suspensions enriched in quartz the influence of quartz rich suspensions moving within the weddell gyre contour current can be traced as far as the continental slope in the northwestern weddell sea in general the focusing of mud by currents significantly exceeds the relative and absolute contribution of ice rafted detritus beyond the shelves of the study area

numerical study of combined overflow and wave overtopping over a smooth impermeable seawall abstract a numerical wave flume is used to investigate the discharge characteristics of combined overflow and wave overtopping of impermeable seawalls the numerical procedure computes solutions to the reynolds averaged navier stokes equations and includes the generation of an irregular train of waves the simulation of wave breaking and interaction with a sloping impermeable wall the numerical model is first tested against published experimental observations approximate analytical solutions and empirical design formulae for the cases of pure overflow and pure overtopping a sequence of numerical experiments simulating combined overflow and overtopping are described the results are used to determine empirical discharge formulae of the form used in current practice

coastal flooding from wave overtopping and sea level rise adaptation in the northeastern usa abstract in the northeastern united states flooding arising from wave overtopping poses a constant threat to coastal communities during storm events the purpose of this study is to construct a novel integrated atmosphere ocean coast and overtopping drainage modeling framework based on the coupled tide surge and wave model swan adcirc to assess risk and facilitate coastal adaptation and resilience to flooding in a changing climate in this region the integrated modeling system was validated against the field observations of water level wave height and period during the january 2015 north american blizzard the water level collected by a sensor in the avenues basin behind the seawall in scituate massachusetts were combined with the basin relationship between basin area and water level given by the usgs lidar data to obtain the field measurements of wave overtopping water volume in order to verify the model predictions at the storm peak the significant wave height was increased by 0 7 m at the coast by tide and surge the wave setup along the coast varied from 0 1 m to 0 25 m depending on the coastline geometry the interaction between tide surge and waves increased the wave overtopping rate by five folds mainly due to the increased wave height at the toe of the seawall the wave overtopping discharge would approximately double in an intermediate sea level rise scenario of 0 36 m by 2050 for a storm like the january 2015 north american blizzard the wave overtopping discharge would increase by 1 5 times if the seawall crest elevation was raised by the same amount as sea level rise as an adaptation strategy an increase of 0 9 m in the seawall crest elevation instead of 0 6 m currently planned by the town is required to bring the wave overtopping discharge to the current level under a 0 36 m sea level rise scenario this result is primarily due to larger waves arriving at the seawall without breaking in the presence of larger water depth

wave transmission and reflection at low crested structures design formulae oblique wave attack and spectral change abstract a part of the delos research focused on wave transformation at low crested structures called lcs this paper gives a summary of all results wave transmission on rubble mound structures has been subject for more flume tests in the delos programme and simultaneously an existing database has been increased extensively by receiving data from other researchers in the world this new database consists of more than 2300 tests and has been used to come up with the best 2d wave transmission formula for rubble mound lcs although not necessarily new as existing ones have been evaluated oblique wave attack on lcs was a second objective within delos results were analysed leading to new empirical transmission formulae for smooth lcs and to conclusions on 3d effects for both rubble mound and smooth lcs the spectral shape changes due to wave transmission and this change has been subject of analysis for all new test data described above although analysis has not been finished completely former assumptions on spectral change were more or less confirmed finally some analysis was performed on reflection at lcs and a first formula was derived to take into account the effect that wave overtopping or transmission reduces reflection and must be dependent on the crest height of the structure

validated coastal flood modeling at imperial beach california comparing total water level empirical and numerical overtopping methodologies abstract flood extent field observations collected during a winter storm h s 1 8 m t p 14 s coinciding with a spring high tide are used to evaluate the accuracy of static bathtub and hydrodynamic coastal flood modeling methodologies static models rely on empirically calculated wave setup or runup and simply compare total water level twl to land elevation the dynamic model resolves temporally variable overtopping rates overland flow urban features and storm system drainage swan a numerical wave model transformed deep water buoy spectra to the nearshore static twls were calculated using swan output and an empirical runup model numerical xbeach and empirical eurotop overtopping models parameterized with survey data and swan bulk wave statistics estimated temporally variable overflow rates along representative transects for overland flow model input xbeach model mode hydrostatic nonhydrostatic boundary depth and random realizations significantly affected overtopping rates nonhydrostatic mode estimated order of magnitude larger overflow volumes suggesting the importance of incident waves particularly in near threshold conditions boundary depth and random realizations varied overflow rates approximately fourfold field observations showed static twl models performed poorly maximum runup substantially overestimated flood extent and setup predicted no flooding all dynamic models reasonably predicted flood extent despite significant overflow volume differences backshore topography and flow dynamics are important flood extent controls accurate near threshold coastal flood predictions require dynamic overland flow modeling parameterized with temporally variable overtopping estimates and site specific beach and backshore topography

uncertainties in the physical modelling of the wave overtopping over a rubble mound breakwater the role of the seeding number and of the test duration abstract this paper presents an experimental study on the variability in the wave overtopping discharge on a simple rubble mound breakwater caused by different random starting phases and different lengths of incident wave sequences sharing the same energy density spectrum a total of 153 small scale laboratory tests were carried out in the wave flume of the roma tre university rome italy to simulate 8 different spectra producing different levels of overtopping the seeding of the random number generator used for the starting phases distribution was changed a number of times for each repetition of the same wave condition the experiments allowed the quantification of how the variability in the wave overtopping grows with the dimensionless freeboard the experimental confidence intervals have been calculated and compared with those provided by the eurotop manual eurotop 2007 the role of the length of the tested wave sequence was also investigated a sensitivity analysis carried out on the partial overtopping time series has pointed out that shorter time series at least 500 waves can be used for overtopping tests by obtaining a comparable accuracy in average overtopping discharge with respect to the recommended 1000 waves series

simulation of wave overtopping by an incompressible sph model the paper presents an incompressible smoothed particle hydrodynamics sph model to investigate the wave overtopping of coastal structures the sph method is a grid less lagrangian approach which is capable of tracking the large deformations of the free surface with good accuracy the incompressible algorithm of the model is implemented by enforcing the constant particle density in the pressure projection the sph model is employed to reproduce a transient wave overtopping over a fixed horizontal deck and the regular irregular waves overtopping of a sloping seawall the computations are validated against the experimental and numerical data and a good agreement is observed the sph modelling is shown to provide a promising tool to predict the overtopping characteristics of different waves the present model is expected to be of practical purpose if further improvement in the spatial resolution and cpu time can be adequately made

wave load on submerged quarter circular and semicircular breakwaters under irregular waves abstract laboratory experiments were conducted to investigate the characteristics of wave loading on submerged circular front breakwaters due to irregular waves the wave force spectrum for a semicircular breakwater is similar to that for a quarter circular breakwater the dimensionless peak wave force for irregular waves is less than that for regular waves the performance of our theoretical wave load model is improved significantly by incorporating the effect of wave transmission and flow separation a rans vof model was used to investigate the effect of local hydrodynamic disturbances by submerged breakwaters on the pressure distribution around the breakwater and total wave load the numerical results reveal that wave induced vortices at the structure have a substantial influence on the wave loading on the submerged quarter circular breakwater but not on the semicircular breakwater a parametric analysis is required to further improve the relationship between wave loads and the vortices

a 2d numerical model of wave run up and overtopping a two dimensional 2d numerical model of wave run up and overtopping is presented the model called ott 2d is based on the 2d nonlinear shallow water nlsw equations on a sloping bed including bed shear stress these equations are solved using an upwind finite volume technique and a hierarchical cartesian adaptive mesh refinement amr algorithm the 2d nature of the model means that it can be used to simulate wave transformation run up overtopping and regeneration by obliquely incident and multi directional waves over alongshore inhomogeneous sea walls and complex submerged or surface piercing features the numerical technique used includes accurate shock modeling and uses no special shoreline tracking algorithm or shoreline coordinate transformation which means that noncontiguous flows and multiple shorelines can easily be simulated the adaptivity of the model ensures that only those parts of the flow that require higher resolution such as the region of the moving shoreline receive it resulting in a model with a high level of efficiency the model is shown to accurately reproduce analytical and benchmark numerical solutions existing wave flume and wave basin datasets are used to test the ability of the model to approximate 1d and 2d wave transformation run up and overtopping finally we study a 2d dataset of overtopping of random waves at off normal incidence to investigate overtopping of a sea wall by long crested waves the data set is interesting as it has not been studied in detail before and suggests that in some instances overtopping at an angle can lead to more flooding than at normal incidence

discriminating glacier thermal and dynamic regimes in the sedimentary record abstract this paper provides a description and evaluation of the sedimentary facies and environments associated with a range of glacier thermal and dynamic regimes with additional consideration given to the tectonic context new and previously published data are evaluated together and are presented from modern terrestrial and marine glacial sedimentary environments in order to identify a set of criteria that can be used to discriminate between different glacier thermal regimes and dynamic styles in the sedimentary record sedimentological data are presented from a total of 28 glaciers in 11 geographical areas that represent a wide range of contemporary thermal dynamic and topographic regimes in the context of landsystems representatives from terrestrial environments include temperate glaciers in the european alps patagonia new zealand the cordillera blanca peru cold glaciers in the dry valleys of antarctica and the antarctic peninsula region and polythermal valley glaciers in svalbard northern sweden the yukon and the khumbu himal nepal the glaciomarine environment is illustrated by data from cold and polythermal glacier margins on the east antarctic continental shelf and from a polythermal tidewater glacier in svalbard along with general observations from temperate glaciers in alaska these data show that temperate glacial systems particularly in high relief areas are dominated by rockfall and avalanche processes although sediments are largely reworked by glaciofluvial processes debris in polythermal glaciers is both thermally and topographically influenced in areas of moderate relief debris is mainly of basal glacial origin and the resulting facies association is dominated by diamicton in high relief areas such as the himalaya the debris load in polythermal glaciers is dominated by rockfall and avalanche inputs resulting in extensive accumulations of sandy boulder gravel cold glaciers are dominated by basal debris entrainment but sediments are little modified from the source materials which are typically sandy boulder gravel from older till and sand from glaciofluvial glaciolacustrine and aeolian sources similar facies associations but with different facies geometry and thickness occur in equivalent glaciomarine settings application of these concepts can aid the interpretation of glacier thermal regime and hence palaeoclimate in quaternary and ancient glacial systems

efficient and robust wave overtopping estimation for impermeable coastal structures in shallow foreshores using swash abstract estimation of wave overtopping over the crest of coastal structures is crucial to design effective and cost efficient countermeasures against storms semi empirical formulas are often used for wave overtopping assessment but they are not always applicable for complex structures which exist in reality e g a storm wall on a dike in a shallow or very shallow foreshore detailed numerical models such as eulerian and lagrangian rans models have potential to simulate overtopping of complex coastal structures with good accuracy however such models require significant computational resources the use of such models is often not feasible for the design of coastal structures which often requires multiple iterations and model runs over a reasonably long period of time e g wave trains with 1000 individual waves in this paper we investigated the applicability of the simplified depth integrated wave transformation model swash for wave overtopping estimation of impermeable coastal structures in shallow foreshores the validation results demonstrate the capability of swash to predict mean wave overtopping discharge with good accuracy compared to results from four different overtopping experimental campaigns comprising 124 individual cases the overall performance of swash to estimate mean wave overtopping discharge is as accurate as those obtained by semi empirical equations in literature however in order to obtain accurate mean wave overtopping discharge with the swash model the incident wave properties at the toe of the dike need to be accurately reproduced for cases where this is not possible a correction method is proposed in this paper detailed validation of the instantaneous wave overtopping also shows a good agreement with physical model data in one example a single intensive overtopping event was not well resolved by the swash model and the instantaneous wave overtopping was under predicted however this did not contribute significantly to the mean wave overtopping discharge an additional advantage of the swash model is that specific coastal structure geometries can be modelled in swash if they are not covered by semi empirical equations even in a case with rapidly varied flow e g vertical wall on a dike the model shows sufficient robustness in this paper the details on the swash model configuration and post processing methods are outlined to enable the reader to reproduce reliable wave overtopping estimation over impermeable coastal structures in shallow foreshores

distributions for wave overtopping parameters for stress strength analyses on flood embankments a process based assessment of the probability of failure of a flood embankment as well as an assessment of the consequences of failure of an embankment require insights into the stresses on the landside slope of an embankment these assessments are hindered by the empirical nature of the wave overtopping parameters failure initiation is often linked to an allowable mean overtopping discharge which forms the input for the overtopping volumes distribution the high level of uncertainty associated with predicting the mean overtopping discharge therefore leads to high levels of uncertainty in predicting wave overtopping volumes the mean overtopping discharge is thereby not directly related to run up parameters this paper addresses these issues by presenting new distributions for the velocity discharge depth volume and shear stresses at the crest for those waves that overtop which have been derived from the wave run up parameters the proposed distributions are independent on the mean wave overtopping discharge and the large inaccuracies associated with predicting this the proposed method has the added benefit of being able to express overtopping parameters in terms of each other the paper also provides a method for determining the change in these random overtopping values along the landside slope thereby facilitating a direct comparison between wave overtopping events and overflow events

estimation of time varying discharge and cumulative volume in individual overtopping waves abstract the time variation of discharge per unit dike length in an overtopping wave is characterized by a rapid increase to a maximum discharge that can be several times greater than the mean discharge followed by a slower decrease in discharge until overtopping for that wave ceases measurements of wave overtopping acquired during the european small scale flowdike experiments were analyzed to identify individual overtopping waves using a two step supervised procedure that combines the best features of automated wave determination augmented with manual error correction and validation the result was a well vetted data set of 5799 individual overtopping waves represented by time series of flow depth and velocity near the seaward edge of the dike crest the model dikes had planar seaward dike slopes of either 1v on 3h or 1v on 6h instantaneous discharge time series were calculated as the product of the flow thickness and velocity time series in this paper the two parameter weibull probability density function is adopted to represent the time variation of instantaneous discharge in an overtopping wave values of the weibull scale factors a and shape factors b are obtained through nonlinear best fitting of the weibull equation to all 5799 waves best fits were also performed for the simpler rayleigh version of the weibull equation when b 2 an empirical equation was developed for scale factor a in terms of predicable parameters of the overtopping waves the shape factor b could not be successfully parameterized but it was found that the shape factors are narrowly distributed about the rayleigh value of b 2 predictions of time varying discharge made using the weibull equation with b 2 i e rayleigh equation are assessed in terms of the root mean square errors between predictions and measurements the estimates are reasonable for most of the waves the capability to estimate the time varying discharge in individual overtopping waves will improve the art of full scale wave overtopping simulation and the resulting empirical equations will contribute to methodologies aimed at quantifying the resiliency of dike erosion protection

a simplified physically based model for coastal dike and barrier breaching by overtopping flow and waves abstract the simplified physically based breach model dlbreach has been developed to simulate the overtopping breaching of coastal dikes and barriers which can occur either from the sea side or the bay side the breaching process is divided into two stages intensive breaching and general inlet evolution in which the flows are calculated using the weir flow equation and the keulegan equation respectively the keulegan equation is a simplified energy equation for steady nonuniform flow with local head loss due to channel contraction and expansion revised herein by adding the wind driving force empirical formulas are adopted to calculate phase averaged wave overtopping discharge wave setup and wind setup setdown the wave overtopping discharge is combined with the surge overflow discharge and the wave setup and wind setup setdown are added to the sea and bay water levels for the hydrodynamic and sediment routing alongshore sediment is considered as a source boundary condition for the non equilibrium sediment transport model at the breach the model has been tested using the 94 field experiment of sea dike breaching by overflow in the zwin channel estuary a laboratory experiment of sea dike breaching initiated by wave overtopping and a field observation of the eight day breaching and closure event of the mecox inlet at eastern long island of new york during sept 10 18 1985 the model results agree generally well with the measurements

numerical simulation of wave overtopping of coastal structures using the non linear shallow water equations a one dimensional high resolution finite volume model capable of simulating storm waves propagating in the coastal surf zone and overtopping a sea wall is presented the model amazon is based on solving the non linear shallow water nlsw equations a modern upwind scheme of the godunov type using an hll approximate riemann solver is described which captures bore waves in both transcritical and supercritical flows by employing a finite volume formulation the method can be implemented on an irregular structured boundary fitted computational mesh the use of the nlsw equations to model wave overtopping is computationally efficient and practically flexible though the detailed structure of wave breaking is of course ignored it is shown that wave overtopping at a vertical wall may also be approximately modelled by representing the wall as a steep bed slope the amazon model solutions have been compared with analytical solutions and laboratory data for wave overtopping at sloping and vertical seawalls and good agreement has been found the model requires more verification tests for irregular waves before its application as a generic design tool

a shape and compositional analysis of ice rafted debris in cores from iodp expedition 323 in the bering sea abstract sediment cores recovered during iodp expedition 323 in the bering sea northern pacific contained numerous ice rafted debris ird clasts up to 85 mm in length the physical properties including roundness and sphericity of 136 clasts from the working half of the cores a subsample of the total clast number were analysed and their composition determined using standard petrographic techniques after removal of pumice and possible fall in derived material from the clast population a total of 86 clasts from the original collection were considered to be ird while roundness and sphericity vary greatly in the clast population the ird are predominately discoid in shape with oblate prolate indices typically between 5 and 5 there are four time periods over the approximately 4 5 ma sample interval 0 36 0 67 ma 0 82 1 06 ma 1 54 1 77 ma and 3 28 ma where there are no ird in the sample set for sites of the bering slope suggesting that these times may have been ice free most clasts show some rounding and are likely to have spent time on beaches with wave action wave action on beaches suggests periods of no ice or only seasonal sea ice the low roundness values of other clasts however suggest they underwent little working and therefore the presence of glaciers or more permanent sea ice at times in those locations the abundance of rounded and unfaceted clasts as ird suggests a lack of large ice sheets in the area during cool periods clast composition of the ird is divided into four broad groups basalt and andesite granite and metamorphic sedimentary and felsic volcanic the granite and metamorphic and more mature sedimentary lithologies are most likely derived from the alaskan continental margin while the extrusive igneous clasts could be derived from a variety of volcanic sources surrounding the bering sea both emergent now or emergent at times of lower sea level there is only a poor correlation with ird abundance and marine isotope stages mis for the time period 2 mm transported by sea ice may not be a good indicator of past climate conditions

distribution of individual wave overtopping volumes in shallow water wave conditions abstract this paper contributes to a better knowledge on the distribution of individual wave overtopping volumes in shallow water wave conditions results from new two dimensional physical model tests on typical rubble mound breakwater geometries indicate that the formulae by besley 1999 are underestimating the number of individual overtopping waves in non rayleigh distributed shallow water wave conditions additionally the proposed shape factors by franco et al 1994 van der meer and janssen 1994 victor et al 2012 in the two parameter weibull distribution which is normally used for describing individual wave overtopping volumes have been seen to over predict the largest overtopping volumes in depth limited waves correction terms based on the incident wave height distributions are introduced in the present paper to modify the existing formulations by besley 1999 franco et al 1994 van der meer and janssen 1994 and victor et al 2012 the modifications significantly improve the predictions of the largest overtopping volumes in shallow water wave conditions

2 d numerical analysis of near field flow at low crested permeable breakwaters abstract this paper describes the capability of a numerical model named cornell breaking waves and structures cobras lin p liu p l f 1998 a numerical study of breaking waves in the surf zone journal of fluid mechanics 359 239 264 liu p l f lin p chang k a sakakiyama t 1999 numerical modeling of wave interaction with porous structures journal of waterway port coastal and ocean engineering 125 322 330 liu p l f lin p hsu t chang k losada i j vidal c sakakiyama t 2000 a reynolds averaged navier stokes equation model for nonlinear water wave and structure interactions proc coastal structures 99 169 174 based on the reynolds averaged navier stokes rans equations to simulate the most relevant hydrodynamic near field processes that take place in the interaction between waves and low crested breakwaters the model considers wave reflection transmission overtopping and breaking due to transient nonlinear waves including turbulence in the fluid domain and in the permeable regions for any kind of geometry and number of layers small scale laboratory tests were conducted in order to validate the model with different wave conditions and breakwater configurations in the present study regular waves of different heights and periods impinging on a wide crested structure are considered three different water depths were tested in order to examine the influence of the structure freeboard the experimental set up includes a flow recirculation system aimed at preventing water piling up at the lee of the breakwater due to overtopping the applicability and validity of the model are examined by comparing the results of the numerical computations with experimental data the model is proved to simulate with a high degree of agreement all the studied magnitudes free surface displacement pressure inside the porous structure and velocity field the results obtained show that this model represents a substantial improvement in the numerical modelling of low crested structures lcs since it includes many processes neglected previously by existing models the information provided by the model can be useful to analyse structure functionality structure stability scour and many other hydrodynamic processes of interest

overtopping layer thickness and overtopping flow velocity on mound breakwaters abstract mound breakwater design is evolving owing to rising sea levels caused by climate change and social concern regarding the visual impact of coastal structures the crest freeboard of coastal structures tends to decrease while overtopping hazard increases over time pedestrian safety when facing overtopping events on coastal structures has been assessed considering the overtopping layer thickness olt and overtopping flow velocity ofv this paper proposes a new method to estimate the olt and ofv on mound breakwater crests during extreme overtopping events based on 123 2d small scale physical tests of conventional low crested mound breakwaters with a single layer cubipod and double layer rock and cube armors the new method to estimate olt exceeded by 2 of incoming waves is based on formulas given in literature for dikes but adapted and calibrated for mound breakwaters the formula to estimate the ofv exceeded by 2 of incoming waves is based on the correlation between the statistics of the olt and ofv considering an empirical coefficient calibrated for each type of armor layer exponential and rayleigh distribution functions are proposed for estimating the olt and ofv with exceedance probabilities under 2 although the statistics of olt and ofv depend on similar variables contrary to intuition specific olt and ofv corresponding to the same overtopping event appear to be independent

wave reflection from coastal structures in design conditions based on an extensive database of more than 4000 data this paper analyses wave reflection for various types of coastal structures in design conditions such as smooth rock and armour unit slopes a new simple formula has been developed that relates the reflection coefficient to the breaker parameter and seems to fit all kinds of revetment materials by changing two coefficients these coefficients depend only on the correct roughness factor provided by recent research on overtopping discharges the effects on reflection due to composite slopes and to low crests are also examined and proper extensions of the formula are provided 2008 elsevier b v all rights reserved