productivity collapses in the arabian sea during glacial cold phases 1 productivity in the arabian sea is one of the highest in the world it is controlled by seasonally reversing monsoonal wind driven upwelling of nutrient rich deeper waters which fuel phytoplankton growth the detailed history of upwelling induced productivity in the eastern arabian sea is unknown here we present paleoproductivity records from a composite sediment core at the millennial scale during the last 80 kyr b p these records are based on relative abundance counts of planktonic foraminifera and organic carbon contents which are shown to mainly vary in concert the eastern arabian sea upwelling induced productivity was higher in the glacial period than in the holocene but it fell repeatedly on millennial timescales these productivity declines occurred during cold events in the north atlantic region with the most pronounced changes prevailing during the heinrich events hence seasonal monsoon winds that drive upwelling induced productivity in the east were weak when the north atlantic was cold these weak winds resulted in stratification of the water column comparable to today s arabian sea stratification in the intermonsoonal period combining the new eastern with published western arabian sea results shows that the entire biological factory was severely diminished during the north atlantic heinrich events and the seasonal productivity change in the arabian sea monsoon system was reduced with year round low productivity

early pliocene vegetation changes forced by eccentricity precession example from southwestern romania repetitive changes in early pliocene marine and continental sediments were forced by astronomical cycles eccentricity precession and related to low amplitude climatic fluctuations as demonstrated at capo rossello and monte san nicola sicily this work aims to establish if such climatic fluctuations have also controlled changes in the vegetation during the warm early pliocene high resolution pollen analysis of the lupoaia section sw romania provides evidence of a clear response owing to its location within a delta system which constitutes a reliable area for pollen deposition near the carpathians i e capable of registering all the vegetation ecosystems from edaphic coastal associations up to the highest altitudinal belts and owing to its southeastern european longitude probably where warm humid air masses arrived regularly making the region a highly favourable refuge for thermophilous plants eccentricity appears to have controlled fluctuations in temperature development of thermophilous elements during eccentricity minima and descent of altitudinal trees during eccentricity maxima while precession appears to have forced changes in humidity expansion of cypress swamps related to precession maxima and spread of herbaceous marshes requiring more humidity related to precession minima with respect to increased precipitation and run off

wave induced mean flows in vertical rubble mound structures abstract waves impinging on rubble mound breakwaters and seawalls induce a mean flow within the breakwater analogous to the so called undertow within the surf zone here using a plane wave approximation kh

experiments and computations of solitary wave forces on a coastal bridge deck part ii deck with girders abstract solitary wave induced forces on a two dimensional model of a coastal bridge are investigated by conducting laboratory experiments and performing cfd computations experimental parameters included four water depths five wave amplitudes four submergence depths and three elevations above the still water level swl for a total of 118 cases submergence depths and elevations are chosen such that the bridge model may be fully submerged partially inundated or fully elevated above the swl euler s equations are solved by use of the cfd program openfoam to compute the wave forces it is found that the forces calculated by openfoam are in close agreement with the laboratory measurements in most cases the effect of formation of entrapped air pockets on the wave forces is studied by including air pressure relief openings on the deck of the model this paper is a companion to part i under the same title the forces on the deck with girders are compared with those on the flat plate given in part i to examine the role of girders on the forces the solitary wave forces are further studied computationally by changing the number of girders in different submergence depths

late quaternary paleoproductivity and deep water circulation in the eastern south atlantic ocean evidence from benthic foraminifera abstract two late quaternary sediment cores from the northern cape basin in the eastern south atlantic ocean were analyzed for their benthic foraminiferal content and benthic stable carbon isotope composition the locations of the cores were selected such that both of them presently are bathed by north atlantic deep water nadw and past changes in deep water circulation should be recorded simultaneously at both locations however the areas are different in terms of primary production one core was recovered from the nutrient depleted walvis ridge area whereas the other one is from the continental slope just below the coastal upwelling mixing area where present day organic matter fluxes are shown to be moderately high recent data served as the basis for the interpretation of the late quaternary faunal fluctuations and the paleoceanographic reconstruction during the last 450 000 years nadw flux into the eastern south atlantic ocean has been restricted to interglacial periods with the strongest dominance of a nadw driven deep water circulation during interglacial stages 1 9 and 11 at the continental margin high productivity faunas and very low epibenthic 13c values indicate enhanced fluxes of organic matter during glacial periods this can be attributed to a glacial increase and lateral extension of coastal upwelling the long term glacial interglacial paleoproductivity cycles are superimposed by high frequency variations with a period of about 23 000 yr enhanced productivity in surface waters above the walvis ridge far from the coast is indicated during glacial stages 8 10 and 12 during these periods cold nutrient rich filaments from the mixing area were probably driven as far as to the southeastern flank of the walvis ridge

tidal dynamics of the water table in beaches tidal motions of the water table height inside a sloping beach are investigated via field measurements and theoretical considerations only the movements forced by the tide are considered so a beach with negligible wave activity was chosen for the field measurements the data show that even in the absence of precipitation the time averaged inland water table stands considerably above the mean sea level also the water table at a fixed point inside the beach is far from sinusoidal even though its variation is forced by an essentially sinusoidal tide this latter effect is due to the boundary condition along the sloping beach face which acts as a highly nonlinear filter the observed behavior of the water table is explained in terms of perturbation extensions to the classical deep aquifer solution one extension deals with the nonlinearity in the interior the other with the boundary condition at the sloping beach face

petrography and geochemistry of oligocene bituminous coal from the jiu valley petrosani basin southern carpathian mountains romania abstract belt samples of oligocene chattian bituminous coal from 10 underground mines located in the jiu valley hunedoara county petrosani basin romania have been examined and analyzed for proximate and ultimate analysis major minor and trace element chemistry organic petrography and vitrinite reflectance the mineral chemistry and mode of occurrence of trace elements also have been investigated using sem and electron microprobe techniques twenty coal beds occur in the jiu valley and most of the samples are from bed no 3 the most productive bed of the dilja uricani formation of oligocene age the petrosani basin oriented sw ne is 48 km long 10 km wide at the eastern part and 2 km wide at the western part the coal mines are distributed along the center of the valley generally following the jiu de vest river reflectance measurements indicate that the rank of the coals ranges from high volatile b to high volatile a bituminous overall rank decreases from the southwest to the northeast in bed no 3 r max varies from 0 75 in the northeast to 0 93 in the southwest although most oligocene coals in romania and adjacent countries are lignite in rank the jiu valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the alpine orogenic event the coals are all dominated by vitrinite resinite and funginite are important minor macerals in most of the coals pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest siderite occurs as nodules and masses within the macerals generally vitrinite dolomite and calcite occur as fracture fillings plant cell fillings and in other authigenic forms late stage fracture fillings are siderite dolomite calcite and ankerite in one instance two populations of siderite 35 and 45 wt feo plus ankerite fill a large fracture late stage pyrite framboid alteration is ni and cu bearing with ni rich pyrite hydrated ni fe sulfate chalcopyrite and rare pentlandite and clausthalite some of the mines sampled in 2001 have been closed as romania has undergone severe economic and environmental reforms in preparation for its 2007 entry into the european union eu romania s continued efforts to adapt to a market economy within the environmental and economic constraints of the eu make this collection of data valuable as the eventual fate of the other mines in jiu valley is unknown

a comparison of intuitive and objective interpretations of miocene plant assemblages from north bohemia abstract an extensive corpus of semi quantitatively described geobotanical analyses from the early miocene of north bohemia has been examined by parametrical and non parametrical multivariate statistical methods the results of these analyses have been compared with traditional geobotanical interpretations that are based on uniformitarian assumptions the statistical analyses show that there are patterns of relationships inherent in the raw geobotanical analyses that are very similar to the traditional interpretations but the statistical analyses define seventeen groups where tradition recognises eight the objective picture from the statistical study however throws a fresh perspective on the familiar evidence and implies that montane colline and riparian forest associations often sub divided on edaphic lines can be recognised in addition to the lowland marsh ecologies implicit in a major brown coal deposit the present day ecological patterns recognisable in ecosystems more than twenty million years old suggest that most of the components retained their ecological preferences throughout this time the statistical analyses offer fresh insights into aspects of the processes transporting the specimens to their place of burial the success of the statistical analyses indicates that the methods used are potentially capable of identifying ecological associations in older geological systems

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

efficient computation of surf zone waves using the nonlinear shallow water equations with non hydrostatic pressure abstract a numerical method for non hydrostatic free surface irrotational flow governed by the nonlinear shallow water equations including the effects of vertical acceleration is presented at the aim of studying surf zone phenomena a vertical boundary fitted grid is used with the water depth divided into a number of layers a compact finite difference scheme is employed for accurate computation of frequency dispersion requiring a limited vertical resolution and hence capable of predicting the onset of wave breaking a novel wet dry algorithm is applied for a proper handling of moving shoreline mass and momentum are strictly conserved at discrete level while the method only dissipates energy in the case of wave breaking the numerical results are verified with a number of tests and show that the proposed model using two layers without ad hoc assumptions enables to resolve propagating nonlinear shoaling breaking waves and wave run up within the surf and swash zones in an efficient manner

pollen record and integrated high resolution chronology of the early pliocene dacic basin southwestern romania an integrated stratigraphic study has been performed on four early pliocene fssections in the western dacic basin including the long reference section of lupoaia based on the integration of mediterranean nannoplankton assemblages the regional lignite stratigraphy records of large and small mammals large climatic fluctuations according to pollen grains and climatostratigraphic relationships at the european scale it has been possible to establish a magnetostratigraphic correlation of the different sections to the geomagnetic polarity time scale gpts this correlation suggests that all normal episodes of the early pliocene from thvera to cochiti chrons are recorded hence the complete pollen record covers an almost continuous time span from about 5 33 to 4 30 ma in addition the regional dacian romanian stage boundary in the dacic basin is located in the nunivak c3n 3n episode with an age of 4 55 0 05 ma our chronologic calibration combined with high resolution pollen data results in a detailed record of paleoclimate in which the 100 kyrs and 400 kyrs eccentricity cycles are clearly identified

palaeoproductivity and associated changes in the north eastern indian ocean since the last glacial evidence from benthic foraminifera and stable isotopes abstract here we present the first detailed planktonic and benthic 13c records and benthic foraminiferal assemblage records from the north eastern indian ocean to decipher the palaeoceanographic changes during the last 56 kyr we identified three different palaeoceanographic stages clearly differentiated by significant variations in the benthic foraminiferal assemblages and 13c records the results of this study indicate that productivity was generally higher during the glacial periods than during the holocene comparison of the benthic foraminiferal assemblage distributions and planktonic and benthic 13c records show a significant correlation between productivity and the bottom water oxygenation on glacial interglacial timescales productivity gradually increased during the period between 56 and 27 5 kyr during this period the dominance of melonis spp and oridosalis umbonatus were correlated with conditions of intermediate to high surface productivity and moderate bottom water oxygenation increased higher equatorial productivity and low bottom water oxygenation during the period between 27 5 and 15 kyr are supported by planktonic 13c and faunal records during this period the dominance of benthic foraminifera assemblages characterised by uvigerina peregrina indicates sustained continuous phytodetritus flux to the seafloor from enhanced surface water productivity and relatively low bottom water oxygenation the absence or minimal occurrences of high productivity indicating u peregrina the dominance of intermediate to low productivity indicating fauna and relatively low planktonic 13c records suggest low productivity and active deep water oxygenation after 15 kyr concurrent river discharge and rising sea levels during this period are indicated by negative 18o of g ruber at the site

numerical modelling of the erosion and deposition of sand inside a filter layer abstract this paper treats the numerical modelling of the behaviour of a sand core covered by rocks and exposed to waves the associated displacement of the rock is also studied a design that allows for erosion and deposition of the sand core beneath a rock layer in a coastal structure requires an accurate prediction method to assure that the amount of erosion remains within acceptable limits this work presents a numerical model that is capable of describing the erosion and deposition patterns inside of an open filter of rock on top of sand the hydraulic loading is that of incident irregular waves and the open filters are surface piercing due to the few experimental data sets on sediment transport inside of rock layers a sediment transport formulation has been proposed based on a matching between the numerical model and experimental data on the profile deformation inside an open filter the rock layer on top of a sand core introduces a correction term in the exner equation the continuity equation for sediment and change in bed level the correction term originates from the fact that the sand can only be deposited in the pores of the filter material the numerical model is validated against additional data sets on the erosion and deposition patterns inside of an open filter a few cases are defined to study the effect of the sinking of the filter into the erosion hole the numerical model is also applied to several application cases the response of the core material sand to changes in the wave period and wave height is considered the effect of different layouts of the filter is studied in order to investigate the effect of different filter profiles on the resulting erosion finally it is studied how much the design of a hydraulically closed filter can be relaxed to obtain a reduction in the design requirements of the filter thickness while the deformation to the sand core remains acceptably small

wave induced pressures in porous bonded revetments part ii pore pressure just beneath the revetment and in the embankment subsoil abstract this paper considers pore pressure distribution in the embankment subsoil beneath pba revetments based on the results of the parameter study using the new validated cfd csd model system waveporegeofoam described in the companion paper part i which focusses on wave induced pressures on pba revetments alcerreca huerta and oumeraci 2016 in this issue in this paper part ii a general overview is first provided on the numerical parameter study especially on the model setup for the extraction of data related to the wave induced pore pressures in the sand core beneath pba revetments secondly wave induced pore pressure just beneath the revetment is analysed considering peak pressure magnitude its location beneath the revetment and their spatial distribution afterwards a process analysis of the results of the parameter study is performed for the wave induced pore pressure distribution in the sand core formulae are developed for the prediction of the pore pressure distribution just beneath the revetment and of the damping of peak pore pressures in the sand core subsequently a comparative analysis of the proposed formulae and the approach of de groot et al 2006 for the assessment of pore pressure in a porous seabed is made showing a very good agreement between both results finally implications and recommendations for engineering applications and for further research are drawn from the results

soil stability analysis for wave induced momentary liquefaction beneath porous bonded revetments abstract the highly porous revetments made of polyurethane bonded aggregates pba are an ecologically friendly alternative to conventional revetments for protection against coastal erosion no information has yet been reported for these structures on failures from field applications however a well documented collapse of a pba revetment observed in large scale tests gwk tests and a first stability analysis were reported by oumeraci et al 2010 2012 based on these results a methodology is proposed for stability analysis of the embankment subsoil beneath pba revetments against momentary liquefaction considering the results of the comprehensive parametric study alcerreca huerta 2014 using a recently developed cfd csd computational fluids dynamics computational solid dynamics model waveporegeofoam alcerreca huerta and oumeraci 2016a 2016b it will be shown that the proposed stability analysis is able to reproduce the failure observed in the gwk tests so that it can be applied for pba revetment under field conditions in this paper the failure observed in the gwk tests is first briefly reported followed by a description of the numerical parametric study using the validated waveporegeofoam model in order to extend the conditions tested in gwk then the processes underlying soil liquefaction of pba revetments are outlined showing that the excess pore pressure development in the sand core beneath pba revetments is crucial the latter is therefore examined and a formula to predict excess pore pressures in terms of the wave conditions is developed moreover a methodology for the stability analysis of the soil beneath the revetment against soil liquefaction is proposed and implemented to reproduce the failure observed in the gwk tests finally the main results are summarized and implications for further research are drawn

an experimental and numerical study of floating breakwaters abstract breakwaters are used to provide sheltered areas for loading and unloading of ships and coastal protection often the breakwaters are bottom mounted such as rubble mound breakwaters however there can be several advantages to use a floating breakwater fb therefore the objective of this paper is to study the effect of two different damping mechanisms of a floating breakwater three basic cross sections of fbs were tested and analysed in 2d a regular pontoon rg a regular pontoon with wing plates attached wp and a regular pontoon with wing plates and porous media attached to the sides wp p100 the damping of the fb motions was due to wave radiation and viscous damping the viscous damping originated mainly from vortex generation around the edges of the structure and due to energy loss inside the porous material attached to the vertical sides of the floating breakwater attaching wing plates to the floating breakwater significantly reduced the motion which was also anticipated when the porous sides were attached the motion of the fb increased compared to the wp cross section but the wave transmission was reduced the possibility for incorporating the effect of the damping in the radiation diffraction code wamit was assessed the study showed that the cross section with wing plates reduced the motions of the breakwater to the largest extend while the cross section with wing plates and porous media attached to the sides reduced the reflection and transmission most effectively

numerical prediction of integrated wave loads on crest walls on top of rubble mound structures abstract wave loads on crest walls on top of rubble mound structures determine the size of these crest walls for the design of crest walls some design guidelines exist but their validity is limited to particular designs of the cross section berm no berm toe armour layout protruding crest element etc the present work addresses the validation of openfoam waves2foam for the prediction of integrated forces on crest wall elements against a new set of experimental data in order to obtain a numerical model that can be applied for a wider field of application than the existing empirical guidelines one key concern for the accurate modelling of wave loads is the spurious entrapment of air between the water surface and structural elements the solution developed for this problem is a boundary condition that allows for air ventilation while enforcing a predefined head loss characteristic compared to the existing technique of introducing small meshed tubes through the structure the new method does not lead to excessive time step limitations and is therefore more efficient a practical case was accelerated by a factor 20 the new boundary condition is validated against experimental data of forces on bridge decks with girders subsequently the numerical model is validated against experimental data for loads on crest wall elements from new experiments conducted in a wave flume the comparison between numerical and experimental data is made both in the time domain and as probability of exceedance special emphasis is given to the openness of the faces of the crest wall to mimic the effect of mixing of water and air during the wave impact finally the validated model is applied to evaluate the forces on crest walls as a function of the elevation of the crest wall with respect to the still water level this effect is of interest since the level of the crest wall element is only tested to a limited extent in laboratory experiments and the bottom face was mainly wetted or submerged during these tests existing empirical formulations the numerical results are compared to an empirical design formulation pedersen 1996 and conclusions on the general applicability of this particular empirical design formulation are presented the effect of the shape of the wave spectrum on the resulting forces is investigated in a preliminary fashion

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

large scale dune erosion tests to study the influence of wave periods article i nfo large scale physical model tests were performed to quantify the effects of the wave period on dune erosion attention was focussed on 2d cross shore effects in a situation with sandy dunes and extreme water levels and wave conditions besides profile measurements detailed measurements in time and space of water pressure flow velocities and sediment concentrations were performed in the near near shore area it was concluded that a longer wave period leads to a larger dune erosion volume and to a larger landward retreat of the dune face tests with double peaked wave spectra showed that the influence of the spectral shape on dune erosion was best represented by the tm 1 0 spectral mean wave period better than the peak wave period tp the effect of the wave period on dune erosion was implemented in a dune erosion prediction method that estimates erosion volumes during normative storm conditions for the dutch coast more details of the measurements and additional analyses of physical processes are described in an accompanying paper by van thiel de vries et al van thiel de vries j s m van gent m r a reniers a j h m and walstra d j r submitted for publication analysis of dune erosion processes in large scale flume experiments in this volume of coastal engineering

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

a short term establishment of forest fen habitat during pliocene lignite formation in the ptolemais basin nw macedonia greece the intermontane basin of ptolemais is part of a major tectonic trench located in nw greece and includes around 65 of greek coal reserves the upper xylite layer uxl is a distinct lignite layer being 3 6 m thick and outcropping in the upper part of the pliocene lignite bearing sequence at the notio field and tomeas eksi mines of ptolemais compared with the xylite rich lithotypes the matrix lithotypes within uxl contain more ash micropetrographic studies suggest that the upper xylite layer is rich in huminite 90 textinite dominates in the xylite rich lithotypes while attrinite dominates in the matrix lithotypes the liptinite content is 10 while inertinite rarely occurs palaeobotanical determination revealed that the xylite rich coal originated from coniferous vegetation specifically from glyptostrobus europaeus the occurrence of g europaeus as a coal forming element is significant because though this kind of vegetation was common in many greek coals of miocene age this is the first time it has been recorded from the pliocene this study suggests that the upper xylite layer is autochthonous according to coal facies diagrammes peat accumulated under pure telmatic conditions in a relatively wet forest fen both herbaceous and arboreal vegetation contributed to peat formation

rans vof modelling of the hydraulic performance of the lowreb caisson abstract the lowreb caisson is an innovative multi chambered low reflection structure that incorporates inner weirs at each dissipative chamber to promote wave energy dissipation it was designed to be applied either as external caisson breakwater or as low reflection quay wall in this paper the openfoam cfd numerical package was used to implement a rans vof numerical model of the lowreb caisson concept which was then validated using results from experimental tests in a two step approach qualitatively by comparing the wave structure interaction on both physical and numerical models and quantitatively by comparing the reflection coefficients determined from the results of the numerical model simulations and those from the physical model tests once validated the numerical model was used to carry out a comprehensive study of the hydrodynamic behavior of the lowreb caisson aiming the understanding of the wave energy dissipation mechanisms and the assessment of its hydraulic efficiency with respect to wave reflection under an extended range of hydrodynamic conditions e g water levels wave heights and wave periods the numerical study confirmed the importance of the inner weirs on the wave energy dissipation the hydraulic efficiency of the lowreb caisson was found to be highly influenced by the combined effect of the wave period and water level however the influence of the wave height is not negligible in general energy dissipation increases with the wave height overall the lowreb caisson presents its best performance for the high and mean water level conditions with all the values of the reflection coefficient below 70 and most of them in the range 30 60 the worse results obtained for the lower water level were attributed to the difficulties that waves have to overtop the weirs and enter the dissipative chambers for this water level in addition streamlines velocity and vorticity fields enabled obtaining important insights on the wave energy dissipation processes that take place during the wave structure interaction which results in the development of several vortices not only inside the dissipative chambers but also in front of the structure

new developments in the upper pliocene pleistocene stratigraphic units of the dacian basin eastern paratethys romania abstract as a result of multidisciplinary investigations carried out in the last two decades the knowledge of the pliocene and quaternary stratigraphy from dacian basin has increased considerably new lithostratigraphic units were revealed for example trajkovo fm romanian vl deni fm v n tori fm pleistocene and other units have been reassessed izvoarele fm tulucesti fm romanian a new biozonation based on molluscan fauna from the late pliocene nsm11 nsm12 and pleistocene qm1 qm9 deposits made possible a more accurate subdivision and cronostratigraphical assignments and correlations many localities with romanian mammal associations lupoaia dr nic podari tetoiu leu etc were reviewed adding new taxa in the faunal list with implications for accurately establishing host deposit ages these studies together with bio magnetostratigraphic investigations led to revision of the romanian stage boundaries and subdivisions pelendavian valahian and to outline several new pleistocene chronostratigraphic units the argedavian dinogetian ilfovian stages and milcovian uzunian netindavian musaisian substages finally one major achievement consisted in the pliocene pleistocene boundary relocation in the dacian basin in agreement with its new position at 2 6 ma in the mediterranean realm

paleoceanography of the southern agulhas plateau during the last 150 ka inferences from benthic foraminiferal assemblages and multispecies epifaunal carbon isotopes benthic foraminiferal assemblages and the carbon isotope composition of the epifaunal benthic foraminifera epistominella exigua and fontbotia wuellerstorfi have been investigated along core md02 2589 located at the southern agulhas plateau 41 26 03 s 25 15 30 e 2660 m water depth this study aims to evaluate changes in the benthic paleoenvironment and its influence on benthic 13c with a notable focus on e exigua a species associated with phytodetritus deposits and poorly studied in isotope paleoceanographic reconstructions the benthic foraminiferal assemblages 63 m show large fluctuations in species composition suggesting significant changes in the pattern of ocean surface productivity conceivably related to migrations of the subtropical convergence stc and subantarctic front saf low to moderate seasonality and relatively higher food supply to the seafloor are indicated during glacial marine isotope stages mis 6 4 and 2 and during mis 3 probably associated with the northward migration of the saf and confluence with the more stationary stc above the southern flank of the agulhas plateau the lowest organic carbon supply to the seafloor is indicated from late mis 5b to mis 4 as a consequence of increased influence of the agulhas front af and or weakening of the influence of the stc over the region episodic delivery of fresh organic matter similar to modern conditions at the core location is indicated during mis 5c mis 5e and at termination i comparison of this paleoenvironmental information with the paired 13c records of e exigua and f wuellerstorfi suggests that organic carbon offsets 13c of e exigua from ambient bottom water 13cdic while its 13c amplitude on glacial interglacial timescales does not seem affected by changes of organic carbon supply to the seafloor this suggests that this species calcifies preferentially during the short time span of the year when productivity peaks and phytodetritus is delivered to the seafloor therefore e exigua while offset from 13cdic potentially more faithfully records the amplitude of ambient bottom water 13cdic changes than f wuellerstorfi notably in settings such as the southern ocean that experienced substantial changes through time in the organic carbon supply to the seafloor

benthic foraminiferal response to late glacial and holocene sea level rise and rainfall variability off east africa analogous to west and north africa east africa experienced more humid conditions between approximately 12 and 5 kyr bp relative to today while timing and extension of wet phases in the north and west are well constrained this is not the case for the east african humid period here we present a record of benthic foraminiferal assemblages and sediment elemental compositions of a sediment core from the east african continental slope in order to provide insight into the regional shallow indian ocean paleoceanography and east african climate history of the last 40 kyr during glacial times the dominance of a benthic foraminiferal assemblage characterized by bulimina aculeata suggests enhanced surface productivity and sustained flux of organic carbon to the sea floor during heinrich stadial 1 h1 the nuttallides rugosus assemblage indicates oligotrophic bottom water conditions and therefore implies a stronger flow of southern sourced aaiw to the study site during the east african humid period the saidovina karreriana assemblage in combination with sedimentary c n and fe ca ratios suggest higher river runoff to the indian ocean and hence more humid conditions in east africa between 8 5 and 8 1 kyr contemporaneous to the globally documented 8 2 kyr event a severe reduction in river deposits implies more arid conditions on the continent comparison of our marine data with terrestrial studies suggests that additional moisture from the atlantic ocean delivered by an eastward migration of the congo air boundary during that time period could have contributed to east african rainfall since approximately 9 kyr the gaining influence of the millettiana millettii assemblage indicates a redevelopment of the east african fringe reefs

simulating waves and their interactions with a restrained ship using a non hydrostatic wave flow model this paper presents a numerical model to simulate the evolution of waves and their interactions with a restrained ship that is moored in coastal waters the model aims to be applicable at the scale of a harbour or coastal region while accounting for the key physical processes that determine the hydrodynamic loads on the ship its methodology is based on the non hydrostatic wave flow model swash which provides an efficient tool to simulate the nonlinear dynamics that govern the nearshore wave field in this work we propose a new numerical algorithm that accounts for the presence of a non moving floating body to resolve the wave impact on a restrained ship the model is validated through comparisons with an analytic solution a numerical solution and two laboratory campaigns the results of the model data comparison demonstrate that the model captures the scattering of waves by a restrained body furthermore it gives a reasonable prediction of the hydrodynamic loads that act on a restrained container ship for a range of wave conditions importantly the model captures these dynamics efficiently which demonstrates that it retains this favourable property of the non hydrostatic approach when a floating body is included the findings of this study suggest that the model provides a promising new alternative to simulate the nonlinear evolution of waves and their impact on a restrained ship at the scale of a realistic harbour or coastal region

environmental distribution of recent benthic foraminifera on the northeast united states continental slope several bathymetrically consistent recent benthic foraminiferal biofacies have been recognized from the continental slope south east of cape cod faunal assemblages are dominated by globobulimina bulimina upper slope less than 1 000 m and uvigerina peregrina lower slope uppermost rise water depths between 1 000 and 2 500 m the globobulimina bulimina assemblage coincides with the oxygen minimum zone this agrees with the occurrence of globobulimina in mediterranean sapropels organic rich sediments deposited under anoxic conditions previous studies have noted the association of u peregrina with bathyal water depths deep water temperatures of 3 to 4 c and water of low oxygen content however correlations between abundance of u peregrina and water depth or temperature are not the same everywhere and no correlation with dissolved oxygen in the water column is seen on the united states continental slope and rise the highest abundances of u peregrina coincide with maxima of organic carbon and silt within the slope sediments this suggests that the distribution of u peregrina in this region may be influenced more by low oxygen in the sediments rather than by low oxygen content of the overlying water

flow and bed shear stresses in scour protections around a pile in a current abstract transport of bed sediment inside and beneath the scour protection may cause deformation and sinking of the scour protection for pile foundations this may reduce the stability of the mono pile and change the natural frequency of the dynamic response of an offshore wind turbine installed on it in an unfavourable manner using physical models and 3d computational fluid dynamic cfd numerical simulations the velocity and bed shear stresses are investigated in complex scour protections around mono piles in steady current in the physical model the scour protections consisted of an upper cover layer with uniformly distributed coarse stones and a lower filter layer with finer stones for the numerical simulations the flow 3d software was used the scour protection layers were simulated with different numerical approaches namely regularly arranged spheres porous media or their combinations hybrid models numerical simulations with one or four layers of cover stones without filter layer were first computed three additional simulations were then made for a scour protection with a cover layer and a single filter layer finally a simulation of a full scale foundation and scour protection was made with porous media approach based on the physical and numerical results a method to determine the critical stones size to prevent motion of the base sediment is established and compared to a full scale case with sinking of scour protection horns rev i offshore wind farm denmark it is also found that the cfd simulations are capable of calculating the flow velocities when the scour protection is represented by regular arranged spheres while the turbulence in general is underestimated the velocity can also be calculated using porous media flow approach but the accuracy is not as good as for spheres the deviation is more severe for more complex scour protections in general computational models provide valuable information for the prediction and design of scour protections for offshore wind farms

numerical simulation of wave induced scour and backfilling processes beneath submarine pipelines abstract a fully coupled hydrodynamic morphodynamic numerical model is presented and utilized for the simulation of wave induced scour and backfilling processes beneath submarine pipelines the model is based on solutions to reynolds averaged navier stokes equations coupled with k turbulence closure with additional bed and suspended load descriptions forming the basis for sea bed morphology the morphological evolution is updated continuously rather than being based e g on period or other time averaging techniques simulations involving wave induced scour over the range of keulegan carpenter number 5 6 kc 30 demonstrate reasonable match with previous experiments both in terms of the equilibrium scour depth as well as the scour time scale wave induced backfilling processes are additionally studied by subjecting initial conditions taken from scour simulations with larger kc to new wave climates characterized by lower kc values the simulations considered demonstrate the ability of the model to predict backfilling toward expected equilibrium scour depths based on the new wave climate in line with experimental expectations the simulated backfilling process is characterized by two stages 1 an initial re distribution phase involving re organization of sediments in the immediate vicinity of the pipeline potentially followed by 2 a more lengthy backfilling evolution toward equilibrium scour depth the simulated backfilling time scales are of the same order of magnitude as in experiments though the multi stage process complicates a more systematic characterization the simulated sequences of scour and backfilling achieved within the present work are estimated to represent temporal durations of up to approximately 12 h at full practical scales

investigations on the porous media equations and resistance coefficients for coastal structures abstract this paper considers the flow in porous media that occurs in coastal and offshore engineering problems over the past decades numerous formulations of flow equations for porous media have been presented the present work re examines the porous media equations of the most recent form and corrects some shortcomings which were identified the applied type of porosity models relies on empirical resistance coefficients which often need to be measured or calibrated only few examples of calibration for numerical models which are present in the literature often applied the same experimental results in this study new calibration cases were introduced to the calibration procedure in order to achieve a better understanding of the variation of the resistance coefficients hereby the coefficients were determined with a better description over the entire parameter space for the resistance coefficients than previously found in the literature constant values for the resistance coefficients for a broad range of flow conditions were recommended based on the new calibrations the model was validated for the main physical processes that occur in wave structure interaction in coastal structures including three dimensional wave structure interaction run up run down and pressure damping regular and irregular wave conditions and evaluation of overtopping simple two and three dimensional uniform caisson structures and breakwater layouts were investigated the model was implemented in the open source cfd library openfoam and has been made publicly available to the engineering community as part of the wave generation framework waves2foam