shallow water turbulence modeling and horizontal large eddy computation of river flow by introducing the concept of sds subdepth scale turbulence to model three dimensional 3d turbulence with length scales less than the water depth and treating it explicitly with a proper separate modeling an sds 2dh model has been developed to simulate the evolution of horizontal large scale eddies in shallow water applying this model to river flows with transverse shear due to vegetation drag the horizontal large scale hls eddies were found to dominate horizontal momentum mixing the bottom friction and vegetation drag acting as sinks of vorticity play the key roles in the development of the horizontal large scale eddies and in reynolds stress generation the sds 2dh model can directly describe effects of flow geometry such as vegetation layer width on the large scale eddy development and hence predicts turbulence mixing better than the k e model

the subsidence history of conoco well 15 30 1 central north sea abstract the depth of deposition of the sediments from north sea well conoco 15 30 1 is determined using faunal and sedimentary evidence the effects of sedimentary load corrected for compaction and variations in water depth and sea level are removed to obtain the subsidence of the basement when covered by water only a crustal stretching and lithospheric thinning of 25 35 1 35 can account for both the initial fault controlled subsidence and the later uniform subsidence

spatially averaged open channel flow over rough bed in this paper it is suggested that the double averaged in temporal and in spatial domains momentum equations should be used as a natural basis for the hydraulics of rough bed open channel flows especially with small relative submergence the relationships for the vertical distribution of the total stress for the simplest case of 2d steady uniform spatially averaged flow over a rough bed with flat free surface are derived these relationships explicitly include the form induced stresses and form drag as components of the total stress using this approach we define three types of rough bed flows 1 flow with high relative submergence 2 flow with small relative submergence and 3 flow over a partially inundated rough bed the relationships for the double averaged velocity distribution and hydraulic resistance for all three flow types are derived and compared with measurements where possible the double averaged turbulent and form induced intensities and stresses for the case of regular spherical segment type roughness show the dominant role of the double averaged turbulence stresses and form drag in momentum transfer in the near bed region

a simple model for the formation of vegetated dunes a simple model for the dynamics of dunes associated with vegetation is proposed using the model the formation processes of transverse dunes parabolic dunes and elongated parabolic dunes are simulated according to two environmental factors i the amount of sand at the source ii the wind force the results have qualitative correspondence to the real counterpart and the simplicity of the algorithm and the consequent ease of handling this model provide us with wide applicability for the investigation of the complex interplay between vegetation and dunes copyright 2001 john wiley sons ltd

differential patterns of benthic foraminiferal extinctions near the paleocene eocene boundary in the north atlantic and the western tethys bathyal benthic foraminifera and stable isotopes from the caravaca and zumaya sections of spain indicate that the mass extinction near the paleocene eocene p e boundary upper planktic foraminiferal zone p6a was rapid coinciding with a negative 13c shift of 2 4 the onset of dark grey shale deposition and increased carbonate dissolution prior to the extinction event diverse benthic foraminiferal assemblages and high 13c values suggest the presence of a stable intermediate deep watermass rich in oxygen and saturated in calcium carbonate in both caravaca and zumaya sections after the extinction event small finely agglutinated haplophragmoides glomospira and thin walled epifaunal taxa nuttallides truempyi dominate in the north atlantic zumaya section this assemblage indicates sluggish circulation bottom waters undersaturated in calcium carbonate and dysaerobic conditions low oxygen conditions prevailed for the succeeding 400 kyr and are characterized by 1 2 fluctuations in benthic 13c in the western tethys caravaca section infaunal taxa buliminids dominate after the extinction event and prevailed through the succeeding 400 to 450 kyr of decreased 13c values indicating low oxygen conditions despite these common features benthic foraminiferal assemblages from these two sections exhibit significant differences during the extinction event at the zumaya section the extinction event occurred over less than 50 kyr and resulted in a sudden reduction in species richness after the 13c shift in contrast at the caravaca section species diversity declined gradually beginning prior to and in concert with the gradually declining 13c values this gradual change occurred over a period of 250 kyr and culminated in a 4 13c shift these differences in 13c values and benthic assemblages between caravaca and zumaya suggest that the p e oceanographic changes that triggered the benthic foraminiferal mass extinction exhibited its first manifestation in the tethys region

biostratigraphy and paleoceanography of the cretaceous seaway between norway and greenland abstract the narrow seaway between greenland and norway in cretaceous time was over 1500 km long and 300 km wide and partly of bathyal water depth during aptian through campanian it received a large volume of fine grained siliciclastic sediments with intercalated gravity flow sandstone wedges as a conduit for heat transport between the low latitudes and polar region atlantic watermasses particularly affected the eastern norwegian margin of this seaway despite its high latitude setting calcareous and few siliceous planktonic microfossils thus play an important role in regional stratigraphy and facies analysis and a majority of fossil events correlate to nw european basins the eastern margin sedimentary succession may be subdivided in several broad lithologic units 1 thin multicolored marly sediments of hauterivian barremian age with a shallow marine falsogaudryina nodosariid ostracod assemblage 2 dark mudstones and minor sands aptian early cenomanian in age with an upper bathyal agglutinated assemblage and monotypic hedbergella floods 3 thick mudstone facies with thin slope apron turbidite sands and an impoverished benthic planktonic assemblage of late cenomanian coniacian age deposited in an upper bathyal oxic dysaerobic environment where turonian sedimentation rates are low a planktonic foraminiferal assemblage with whiteinella hedbergella dicarinella and marginotruncana occurs 4 grayish laminated mudstones santonian campanian in age with local sands in the north a low diversity middle to upper bathyal benthic planktonic foraminiferal assemblage and an inoceramus prisms and radiolarian diatom flood a campanian agglutinated foraminiferal bloom also is known from the atlantic oceanic realm 5 more marly sediments of maastrichtian age with a low diversity planktonic benthic foraminiferal assemblage using the distribution of 1755 foraminiferal and dinoflagellate microfossil events in over 30 exploration wells a rasc ranking and scaling probabilistic zonation served as a template to build a cretaceous zonal model with 19 assemblage and interval zones including over 100 events variance analysis ranks 72 events according to reliability in correlation three new index taxa include uvigerinammina una and ammoanita globorotaliaeformis albian and fenestrella bellii campanian widespread planktonic flood events occur in late albian through early cenomanian early mid turonian late santonian earliest campanian and mid maastrichtian the result of northwards shifts of warmer water masses and disruptions in water stratification in the dysaerobic basins an earliest cretaceous hiatus separates jurassic from cretaceous strata ongoing block faulting coupled to thermal subsidence and global sealevel rise increased water depth in aptian albian time from neritic to bathyal and created sand accommodation space in dysaerobic restricted settings in cenomanian coniacian time sedimentation rates in the central basin increased 10 fold whereas paleo waterdepth did not deepen this relatively brief less than 10 m y tectonic episode resulting in deposition of deep water sands is tentatively linked to stress re orientation in the rockall area a widespread upper maastrichtian danian hiatus the result of shoulder uplift reflects break up prior to the onset of paleogene seafloor spreading in the norwegian sea

using geostatistics to elucidate temporal change in the spatial variation of aeolian sediment transport little is known about the spatial and temporal scales of variation in aeolian processes studies that aim to investigate surface erodibility often sample aeolian sediment transport at the nodes of a regular grid of arbitrary size few aeolian transport investigations have the resources to obtain sufficient samples to produce reliable models for mapping the spatial variation of transport this study reports the use of an innovative nested strategy for sampling multiple spatial scales simultaneously using 40 sediment samplers reliable models of the spatial variation in aeolian sediment transport were produced and used for ordinary punctual kriging and stochastic simulated annealing to produce maps for several wind erosion events over a 25 km 2 playa in western queensland australia the results support the existence of a highly dynamic wind erosion system that was responding to possibly cyclic variation in the availability of material and fluctuations in wind energy the spatial scale of transport was considerably larger than the small scale expected of the factors controlling surface erodibility thus it appears that transport cannot be used as a surrogate of erodibility at the scale of this investigation simulation maps of transport provided considerably more information than those from kriging about the variability in aeolian sediment transport and its possible controlling factors the proposed optimal sampling strategy involves a nested approach using ca 50 samplers copyright 2003 john wiley sons ltd

spatial temporal evolution of aeolian blowout dunes at cape cod abstract this paper explores historical evolution of blowouts at cape cod national seashore ccns usa a site that hosts one of the world s highest densities of active and stabilized blowouts the spatial temporal analysis of moving polygons stamp method is applied to a multi decadal dataset of aerial photography and lidar to extract patterns of two dimensional movement and morphometric changes in erosional deflation basins and depositional lobes blowout development in ccns is characterized by several geometric overlap and movement proximity responses including i generation and disappearance ii extension and contraction iii union or division iv clustering and v divergence by stabilization other possible movement events include migration amalgamation and proximal stabilization but they were not observed in this study generation events were more frequent than disappearance events the former were highest between 1985 and 1994 while the latter were highest between 2000 and 2005 high rates of areal change in erosional basins occurred between 1998 and 2000 3932 m2 a 1 the lowest rate 333 m2 a 1 between 2005 and 2009 and the maximum rate 4589 m2 a 1 between 2009 and 2011 union events occurred mostly in recent years 2000 2012 while only one division was observed earlier 1985 1994 net areal changes of lobes showed gradual growth from a period of contraction 1119 m2 a 1 between 1998 and 2000 to rapid extension 2030 m2 a 1 by 2010 which is roughly concurrent with rapid growth of erosional basins between 2005 and 2009 blowouts extended radially in this multi modal wind regime and despite odd shapes initially they became simpler in form more circular and larger over time net extension of erosional basins was toward ese 109 while depositional lobes extended sse 147 lobes were aligned with the strongest winter sand drift vector although their magnitude of areal extension was only 33 that of the basins these differences in extension responses likely result from more complex and evolving flow form interactions inside erosional basins historical photographs and ccns documents suggest that blowout evolution may be influenced by land use changes such as revegetation campaigns in 1985 that were followed by high blowout generation high magnitude regional storm events e g hurricanes also play a role the analytical framework presented provides a systematic means for two dimensional geomorphic change detection and pattern analysis that can be applied to other landscapes

field investigation of three dimensional flow structure at stream confluences 2 turbulence stream confluences are among the most highly turbulent locations in fluvial systems this paper examines the three dimensional structure of turbulence at three stream confluences in east central illinois the analysis focuses on the characteristics of turbulence both within the shear layer and in the ambient flow results show that at the upstream end of each confluence the shear layer occupies a limited portion of the flow cross sectional area but turbulence kinetic energy within this layer is 2 3 times greater than the turbulence kinetic energy of the ambient flow which has turbulence characteristics similar to those for flow in straight channels turbulence within the shear layer can be characterized as quasi two dimensional in the sense that large scale turbulence generated by transverse shear is predominantly two dimensional whereas small scale turbulence associated with bed friction is three dimensional spectral analysis suggests that the structure of fluid motion within the shear layer differs for confluences with symmetrical versus asymmetrical planforms the shear layer dissipates rapidly as flow enters the downstream channel even though a well defined mixing interface persists at downstream locations

deep sea trace fossils of the oligocene miocene numidian formation northern tunisia abstract twenty two ichnogenera and thirty one ichnospecies have been recorded in the oligocene miocene numidian formation of northern tunisia heterolithic successions of thin bedded turbidite sandstones and interchannel mudstones contain the most diverse trace fossil assemblages thick to very thick bedded structureless sandstones and conglomerates representing the fill of channel complexes contain a low diversity trace fossil assemblage the ichnoassemblage in the lower part of the formation oligocene which includes paleodictyon isp scolicia strozzii spirorhaphe isp cosmorhaphe isp and halopoa isp can be ascribed to the paleodictyon ichnosubfacies of the nereites ichnofacies the ichnoassemblage in the upper part of the formation miocene aquitanian including diplocraterion cf habichi scolicia vertebralis and ophiomorpha isp is interpreted as the shallower part of the ophiomorpha rudis ichnosubfacies of the nereites ichnofacies the notable switch in ichnofauna between the oligocene and lower miocene reflects variation in environmental and depositional conditions the common occurrence of trace fossils of the ophiomorpha rudis ichnosubfacies and diplocraterion cf habichi in the early miocene indicates an increase in energy level greater environmental disturbance and probable shallowing this is also confirmed by a corresponding decrease in the abundance and diversity of benthic foraminifera the integration of ichnological sedimentological and microfossil contents has allowed the distinction of two quite distinct geographical depositional settings within the numidian formation the first domain includes the numidian succession of the tabarka cap negro cap serrat and bouhertma areas which are characterised by distal turbidites showing the paleodictyon ichnosubfacies that is compatible with a lower bathyal depth in the oligocene and an upper slope depositional environment during the early miocene the second domain includes the ne part of mogod mountain e g the ras el korane jebel gattous zoukar which exhibit more proximal characteristics compatible with a probable slope canyon interpretation the southern margin of the kroumirie balta and zouza areas and sejnene area shows a distal setting compared with the ras el korane and jebel gattous zoukar areas it is ascribed to a mid to upper slope depositional environment during the oligocene to early miocene

quantifying spatial and temporal trends in beach dune volumetric changes using spatial statistics abstract spatial statistics are generally underutilized in coastal geomorphology despite offering great potential for identifying and quantifying spatial temporal trends in landscape morphodynamics in particular local moran s i i provides a statistical framework for detecting clusters of significant change in an attribute e g surface erosion or deposition and quantifying how this changes over space and time this study analyzes and interprets spatial temporal patterns in sediment volume changes in a beach foredune transgressive dune complex following removal of invasive marram grass ammophila spp results are derived by detecting significant changes in post removal repeat dems derived from topographic surveys and airborne lidar the study site was separated into discrete linked geomorphic units beach foredune transgressive dune complex to facilitate sub landscape scale analysis of volumetric change and sediment budget responses difference surfaces derived from a pixel subtraction algorithm between interval dems and the lidar baseline dem were filtered using the local moran s i i method and two different spatial weights 1 5 and 5 m to detect statistically significant change moran s i i results were compared with those derived from a more spatially uniform statistical method that uses a simpler student s t distribution threshold for change detection morphodynamic patterns and volumetric estimates were similar between the uniform geostatistical method and moran s i i at a spatial weight of 5 m while the smaller spatial weight 1 5 m consistently indicated volumetric changes of less magnitude the larger 5 m spatial weight was most representative of broader site morphodynamics and spatial patterns while the smaller spatial weight provided volumetric changes consistent with field observations all methods showed foredune deflation immediately following removal with increased sediment volumes into the spring via deposition at the crest and on lobes in the lee despite erosion on the stoss slope and dune toe generally the foredune became wider by landward extension and the seaward slope recovered from erosion to a similar height and form to that of pre restoration despite remaining essentially free of vegetation

techniques for gis modeling of coastal dunes coastal dunes present a unique problem to coastal scientists because of the dynamic nature of most coastal dune systems coastal dunes can change shape quickly and frequently due to storm generated winds and waves prevailing winds can transport significant amounts of sand throughout the dune system topographic and volumetric changes in a 150 40 m site on the outer banks of north carolina were assessed through a series of monthly field surveys conducted over a 1 year period from may 1997 to may 1998 this paper discusses the geographic information system gis methodology used for data acquisition and analysis and presents one methodology developed to measure 3 d dune morphodynamics using a 2 d and 3 d gis it serves as a guide for other coastal researchers who may have limited surveying or gis experience issues concerning sampling routine data density and grid cell size are discussed the methodology followed results in the production of a grid of interpolated elevation values that can be represented in a variety of ways including as topographic maps digital elevation models dem or two dimensional cross sections of the dune system the grid from the may 1998 survey is subtracted from the may 1997 grid to obtain elevation change information that in turn can be represented graphically the results of the analysis show that volumetric change over the 1 year period was dominated by erosion along the seaward face of the dune the monthly surveys show that this erosion was the result of two northeasters in january and february 1998 the loss of volume is partially compensated for by accumulation to the rear of the foredune ridge primarily in locations where blowouts facilitate aeolian transport of sediment from the beach the implication is that the dune system is eroding rapidly due to storm activity it also suggests that there is a mechanism for offsetting some of the volumetric loss through aeolian transport into the dune system

spatial characterization resolution and volumetric change of coastal dunes using airborne lidar cape hatteras north carolina the technological advancement in topographic mapping known as airborne light detection and ranging lidar allows researchers to gather highly accurate and densely sampled coastal elevation data at a rapid rate the problem is to determine the optimal resolutions at which to represent coastal dunes for volumetric change analysis this study uses digital elevation models dem generated from lidar data and spatial statistics to better understand dune characterization at a series of spatial resolutions the lidar data were collected jointly by the national aeronautics and space administration nasa the national oceanic and atmospheric administration noaa and the u s geological survey usgs dems of two study sites 100 200 m located in cape hatteras national seashore north carolina were generated using a raster based geographic information system gis changes in the dune volume were calculated for a 1 year period of time fall 1996 1997 at grid cell resolutions ranging from 1 1 to 20 20 m directional statistics algorithms were used to calculate local variance and characterize topographic complexity data processing was described in detail in order to provide an introduction to working with lidar data in a gis results from these study sites indicated that a 1 2 m resolution provided the most reliable representation of coastal dunes on cape hatteras and most accurate volumetric change measurements results may vary at other sites and at different spatial extents but the methods developed here can be applied to other locations to determine the optimum resolutions at which to represent and characterize topography using common gis and database software

assessing significant geomorphic changes and effectiveness of dynamic restoration in a coastal dune ecosystem article i nfo a shift from restoring coastal dunes as stabilized landscapes toward more morphodynamic ecosystems is un derway this paper uses results from a recent case study where invasive vegetation was removed from a coastal dune complex in western canada as a first step in a dynamic ecosystem restoration project spatial statistical methods used in the natural sciences to quantify patterns of significant spatial temporal changes are reviewed and the local moran s ii spatial autocorrelation statistic is explored for detecting and assessing significant changes cluster maps of positive depositional and negative erosional changes were used to derive statistically significant volumetric changes within discrete geomorphic units beach foredune trans gressive dune over one year following vegetation removal all units experienced net increases in sediment budgets compared to a pre restoration surface the beach experienced the highest episodic erosion and vol umetric change and greatest net annual sediment budget compared to the beach the annual sediment budget of the foredune was 19 whereas the transgressive dune was 33 the foredune recovered rapidly to initial erosion during restoration and subsequent natural events with consistently positive sediment volumes and attained a form similar to that pre restoration aeolian deflation and sand bypassing through the foredune was greatest in the two months following vegetation removal and peak accretion in the transgressive dune resulted from depositional lobes extending from the foredune smaller dunes migrating within the complex and growth of a precipitation ridge along the eastern margin several methodological and logistical considerations for detecting significant change in dynamic dune land scapes are discussed including sampling strategy design data normalization and control measures and incorpo rating uncertainty and inherent spatial relations within acquired datasets to ensure accuracy and comparability ofresults generally underutilizedincoastalgeomorphology spatialautocorrelation methods e g localmoran s ii are recommended over spatially uniform threshold approaches for the ability to detect local change processes and explore hypotheses on spatial temporal dynamics finally several key geomorphic indicators that are believed to aid in re establishing ecological conditions and processes that favor more resilient and natural dune ecosystems are identified for assessing the effective ness of dynamic restoration projects including increased aeolian activity enlarged active sand surface area positive sediment budgets increased dune morphodynamics improved geomorphic diversity and enhanced geomorphic resilience although limited in temporal scope the case study results show that the initial phase of the restoration treatment was effective in enhancing all indicators except for increasing sand surface area given decadal scale observations of climatic changes and longer term eco geomorphic trajectory toward stabi lization in the region however it is unlikely that the geomorphic effectiveness of this restoration effort will con tinue without continued frequent treatment interventions

numerical evaluation of the effects of planform geometry and inflow conditions on flow turbulence structure and bed shear velocity at a stream confluence with a concordant bed this study numerically investigates the effects of variations in inflow conditions and planform geometry on large scale coherent flow structures and bed friction velocities at a stream confluence with natural bathymetry and concordant bed morphology several numerical experiments are conducted in which either the kelvin helmholtz mode or the wake mode dominates within the mixing interface mi between the two confluent streams as the junction angle and alignments of the tributaries are altered in the kelvin helmholtz mode the mi contains mostly corotating vortices driven by the mean transverse shear across the mi while in the wake mode the mi contains counterrotating vortices forming by the interaction of the separated shear layers on the two sides of a zone of stagnant fluid near the junction corner a large angle between the two incoming streams is not necessary for the development of strongly coherent streamwise oriented vortical sov cells in the immediate vicinity of the mi results show that such sov cells can develop and produce high bed friction velocities even for cases with a low angle between the two tributaries and for cases where the downstream channel is approximately aligned with the axes of the two tributaries low curvature cases sov cells tend not to develop only when the incoming streams are parallel and aligned with the downstream channel junction angle of zero and the incoming flows produce a strong kelvin helmholtz mode under such conditions quasi 2 d mi vortices play the primary role in mixing and the production of high bed shear velocities simulations with and without natural bed morphology local bank line irregularities indicate that planform geometry and inflow conditions primarily govern the development of coherent flow structures but that bathymetric and bank line effects can locally modify details of these structures

barchan parabolic dune pattern transition from vegetation stability threshold 1 many dune fields exhibit a downwind transition from forward pointing barchan dunes to stabilized backward pointing parabolic dunes accompanied by an increase in vegetation a recent model predicts this pattern transition occurs when dune surface erosion deposition rates decrease below a threshold of half the vegetation growth rate we provide a direct test using a unique data set of repeat topographic surveys across white sands dune field and find strong quantitative support for the model threshold we also show the threshold hypothesis applied to a barchan dune results naturally in its curvature inversion as the point of threshold crossing progresses from the horns to the crest this simple general threshold framework can be an extremely useful tool for predicting the response of dune landscapes to changes in wind speed sediment supply or vegetation growth rate near the threshold a small environmental change could result in a drastic change in dune pattern and activity

foredune morphodynamics and sediment budgets at seasonal to decadal scales humboldt bay national wildlife refuge california usa abstract coastal foredunes are shore parallel ridges that form in the backshore and their morphodynamics are controlled partly by seasonal and spatial variations in the coastal onshore sediment budget that in turn are driven by oceanic and atmospheric processes and interactions including regional wave and wind regimes climatic variability events e g enso sediment availability beach characteristics e g width slope and vegetation type and cover in the backshore previous studies on shoreline change in northern california report only broad rates of erosion and accretion related to regional meteorological regimes this study presents a more detailed multi decadal to seasonal account of shoreline response and foredune morphodynamics along a 2 5 km stretch of coast in the humboldt bay national wildlife refuge hbnwr analysis of historical aerial photography 1939 2014 reveals trends in shoreline position that are coupled with more detailed assessments of foredune morphodynamics and seasonal scale volumetric changes from cross shore topographic profiles these findings set the historical context of foredune morphodynamics and allow exploration of the implications of seasonal meteorological variation on long term 75 year foredune evolution and development at the hbnwr dsas describes maximum foredune progradation in the north up to 0 51 m a 1 and maximum foredune retreat in the south up to 0 49 m a 1 aerial photograph analysis 2004 2014 shows statistically significant larger erosive features in the southern zone than in the northern and central zones seasonal volume calculations from cross shore profiles indicate statistically significant differences in alongshore transect elevation and foredune volume with larger elevations and volumes in the northern and central zones than in the southern combined with evidence of seasonal bidirectional littoral drift these data support a north to south gradient in sediment availability foredune position and resulting stages of established foredune development seasonal storm energies and climate forcing events introduce variability in erosive patterns but support the persistence of alongshore developmental stages future research should explore foredune morphodynamics on a smaller spatial scale and changes related to the presence absence of multiple vegetation assemblages

palaeocurrents and petrography of the gurnigel schlieren flysch a basin analysis abstract the late maastrichtian to middle eocene gurnigel schlieren flysch is analysed from the point of view of tectonic control on deposition facies show an alternation of abyssal plain oceanic slope trench fill channellized and non channellized sediments and finally lower slope deposits the facies evolution points to a sporadically active subduction trench environment a detailed picture of the sediment dispersal pattern is deduced from framework grain analysis feldspar and lithic fragment counts and conglomerate analysis on current oriented samples this picture includes 10 major and 3 minor depositional systems which varied in time and space variation was influenced by tectonic movements in the basin and source areas and by sea level changes smoothing out of late alpine deformation reveals a west east trending elongated basin geometry and sediment distribution pattern flow directions which do not fit with the model are discussed the eocene subduction related rotation of parts of the basin is suggested to have disrupted an initially coherent flow pattern the sequence was deposited within a remnant of the south penninic ligurian ocean in a trench environment bordered by a continental margin arc

palaeoenvironmental changes across the danian selandian boundary in the north sea basin abstract the danian selandian boundary 60 ma marks the cessation of 40 million years of carbonate deposition in the north sea basin and a shift to siliciclastic deposition on the basis of variations in lithology benthic and planktonic foraminifera and calcareous nannofossils in three cores from storebaelt in the eastern part of the north sea basin we have reconstructed the palaeoenvironmental changes across the boundary the benthic foraminiferal faunas belong to the midway type fauna they are extremely rich and more than 260 taxa have been recognized q mode cluster analysis groups the benthic assemblages into four biofacies which correspond fairly closely to lithological units correlation of the storebaelt records with marine palaeorecords from the danish basin and the north sea basin indicate that the transformation of the north sea from a carbonate to a siliciclastic basin occurred in four steps separated by relatively long stable periods the most important external factors involved in the change are firstly a drop in the relative sea level during the late danian leading to the disappearance of bryozoans from the north sea basin and to non deposition and erosion in many areas secondly coinciding with the danian selandian boundary an uplift of the scotland shetland area resulting in a massive input of siliciclastic deposits to the north sea basin thirdly during the early selandian inversion of the sorgenfrei tornquist zone and mesozoic basins in the southern and eastern part of the north sea basin resulted in a huge influx of reworked cretaceous chalk and an almost complete stop of carbonate production finally later in the early selandian in connection to a general sea level rise and a reduction in the gateway between the north sea basin and the tethys sea the sea bottom conditions became colder and more acidic this resulted in partial dissolution of the carbonates and the deposition shifted from marl to clay comparison with records from the western pyrenees the nile basin and the eastern north america suggests that sea level changes across the danian selandian boundary are primarily of eustatic nature

the application of lidar to investigate foredune morphology and vegetation abstract lidar light detection and ranging has been used to investigate coastal landform morphology evolution and change for almost a decade repeated airborne lidar surveys can provide the scientific community with significant observations of how shorelines have evolved which may then enable forecasts of future patterns of change however there have been few studies that have considered the application of this new technology to the specific study of foredune morphology and vegetation the accuracy and appropriateness of airborne lidar needs to be assessed particularly where the density of vegetation may obscure the underlying topography prior to interpreting derived geomorphic features this study i tests the vertical accuracy of airborne lidar in 37 foredune systems along the coast of south eastern australia and ii demonstrates that it can be used to describe foredune morphology and vegetation in considerable detail there was a strong correlation between the remotely sensed lidar derived elevation and field topographic and vegetation surveys r2 0 96 a protocol for obtaining foredune geomorphic and botanical parameters is described it enables widespread biogeomorphic characterisation along coasts for which lidar data is available which can benefit both coastal managers and researchers alike

geomorphic and sediment volume responses of a coastal dune complex following invasive vegetation removal this paper documents application of an established geostatistical methodology to detect significant changes in a foredune transgressive dune complex where parks canada agency pca implemented a dynamic restoration program to remove invasive marram grasses ammophila spp and enhance dynamic dune habitat for an endangered species detailed topographic surveys of a 10 320 m2 site in the wickaninnish dunes in pacific rim national park british columbia canada for the first year post treatment are compared to a pre restoration lidar baseline survey the method incorporates inherent spatial structure in measured elevation datasets at the sub landscape scale and models statistically significant change surfaces within distinct linked geomorphic units beach foredune transgressive dune complex seasonal and annual responses within the complex are discussed and interpreted all geomorphic units experienced positive sediment budgets following restoration treatment the beach experienced the highest differential volumetric change 1656 m3 and net sediment influx 834 m3 0 19 m3 m 2 mostly from supply to the supratidal beach and incipient dune this sediment influx occurred independent of the restoration effort and was available as a buffer against wave erosion and as supply to the landward dunes the foredune received 200 m3 0 13 m3 m 2 and its seaward profile returned to a similar pre restoration form following erosion at the crest from vegetation removal and scarping by high water events sediment bypassing and minimal change was evident at the mid stoss slope with appreciable extension of depositional lobes in the lee the transgressive dune complex experienced high accretion following restoration activity 201 m3 and over the year 284 m3 0 07 m3 m 2 mostly from depositional lobes from the foredune precipitation ridge growth along the downwind boundary and growth of existing lobes within the complex further integration of this methodology to detect significant geomorphic changes is recommended particularly for applications where sampling densities are limited or logistically defined copyright 2013 john wiley sons ltd

late cretaceous deep water agglutinated foraminiferal assemblages from the north atlantic and its marginal seas the stratigraphic and biogeographic distribution of more than 170 species of deep water agglutinated benthic foraminifers dwaf from the north atlantic and adjacent marginal seas has been compared with paleoenvironmental data e g paleobathymetry oxygenation of the bottom waters amount of terrigenous input and substrate disturbance six general types of assemblages in which deep water agglutinated taxa occur are defined from the turonian to maastrichtian times 1 high latitude slope assemblages 2 low to mid latitude slope assemblages 3 flysch type assemblages 4 deep water limestone assemblages scaglia type 5 abyssal mixed calcareous agglutinated assemblages 6 abyssal purely agglutinated assemblages latitudinal differences in faunal composition are observed the most important of which is the lack or extreme paucity of calcareous forms in high latitude assemblages east to west differences appear to be of comparatively minor importance most dwaf species occur in all studied regions and are thus considered as cosmopolitan biostratigraphic turnovers in the taxonomic content of assemblages are observed in the lowermost turonian mid campanian and in the upper maastrichtian to lowermost paleocene these datum levels correspond to inter regional and time constant paleooceanographic events which probably also affected the deep water benthic biota this allows us to use deep water agglutinated foraminifers for biostratigraphy in the north atlantic sequences deposited below ccd and to geographically extend the currently used zonal schemes which have been established in the carpathian and alpine areas

the application of computational fluid dynamics to natural river channels eddy resolving versus mean flow approaches in the last decade as computing power has increased there has been an explosion in the use of eddy resolving numerical methods in the engineering earth and environmental sciences for complex geomorphic flows where accurate field investigations are difficult to perform and where experiments may be difficult to scale these numerical approaches are beginning to give key insights into the nature of these flows eddy resolving methods such as large and detached eddy simulation les des may be contrasted with the time averaged three dimensional simulations that only really began to be applied seriously in geomorphology fifteen years ago while the potential of les for geomorphology has been examined previously des is a relatively recent method that deserves further consideration in this paper we explain the method and then utilise examples from meander and confluence flows as well as flow near the bed of a gravel bed river to highlight the improvements to both the representation of the mean flow and to the representation of time varying processes that result from the use of les des some suggestions are provided for the future use of such techniques in geomorphology

short term beach dune sand budgets on the north sea coast of france sand supply from shoreface to dunes and the role of wind and fetch abstract three experimental plots covering the transition from the upper beach to the dune on the north sea coast of france were monitored at various intervals over a period of 18 24 months via high resolution terrain surveys in order to determine inter site sand budget variability as well as patterns and processes involved in sand exchanges between the upper beach and dune the wind regime consists of a fairly balanced mix of moderate 80 of winds are below 8 m s onshore offshore and shore parallel winds sustained dune accretion over several years depends on the periodic local onshore welding of shoreface tidal banks that have developed in the storm and tide dominated setting of the southern north sea the only site where this has occurred in the recent past is calais where bank welding has created a wide accreting upper beach sand flat at this site significant sand supply from the subtidal sand bank reservoir to the upper beach flat occurred only once over the 18 month survey following a major storm the bulk of the sand deposited over this large flat is not directly integrated into the adjacent embryo dunes by onshore winds but is progressively reworked in situ into developing dunes or transported alongshore by the balanced wind regime thus resulting in alongshore stretching of the embryo dune system the leffrinckoucke site near belgium shows moderate beach dune mobility and accretion while the wissant site exhibits significant upper beach bedform mobility controlled by strong longshore currents that result in large beach budget fluctuations with little net budget change to the detriment of the adjacent dunes accretion at these two sites which are representative of the rest of the north sea coast of france is presently constrained by the absence of a shore attached sand bank supply reservoir while upper beach dune sand exchanges are further limited by the narrow wave affected upper beach the intertidal morphology of bars and troughs which segments the aeolian fetch and the moderate wind energy conditions the balanced wind regime limits net sand mobilisation in favour of either the beach or the dune and may explain the relatively narrow longshore morphology of the dune ridges bounding this coast

quaternary paleoceanography of the central arctic based on integrated ocean drilling program arctic coring expedition 302 foraminiferal assemblages the integrated ocean drilling program iodp arctic coring expedition acex hole 4c from the lomonosov ridge in the central arctic ocean recovered a continuous 18 m record of quaternary foraminifera yielding evidence for seasonally ice free interglacials during the matuyama progressive development of large glacials during the mid pleistocene transition mpt 1 2 0 9 ma and the onset of high amplitude 100 ka orbital cycles 500 ka foraminiferal preservation in sediments from the arctic is influenced by primary sea ice organic input and other environmental conditions and secondary factors syndepositional long term pore water dissolution taking these into account the acex 4c record shows distinct maxima in agglutinated foraminiferal abundance corresponding to several interglacials and deglacials between marine isotope stages mis 13 37 and although less precise dating is available for older sediments these trends appear to continue through the matuyama the mpt is characterized by nearly barren intervals during major glacials mis 12 16 and 22 24 and faunal turnover mis 12 24 abundant calcareous planktonic mainly neogloboquadrina pachyderma sin and benthic foraminifers occur mainly in interglacial intervals during the brunhes and very rarely in the matuyama a distinct faunal transition from calcareous to agglutinated foraminifers 200 300 ka in acex 4c is comparable to that found in arctic sediments from the lomonosov alpha and northwind ridges and the morris jesup rise down core disappearance of calcareous taxa is probably related to either reduced sea ice cover prior to the last few 100 ka cycles pore water dissolution or both

foraminiferal and palynological biostratigraphy and biofacies from a santonian campanian submarine fan system in the voring basin offshore norway abstract foraminiferal assemblages from a santonian campanian submarine fan system in the northwestern voring basin offshore norway were investigated with the primary objectives to document the stratigraphic ranges of foraminiferal taxa calibrated with dinoflagellate cysts and to interpret foraminiferal biofacies of different fan sub environments previously proposed based on the analysis of ichnofossils the assemblages are composed of deep water agglutinated foraminifera dwaf without carbonate cemented taxa dwaf taxa of high biostratigraphic value are absent but the complete agglutinated nature of the assemblages and the presence of gerochammina stanislawi and rectogerochammina eugubina are similar to those of the lower campanian fenestrella bellii zone of the norwegian sea more reliable dating was provided by palynology and the age of the interval is estimated to be santonian to campanian the inner to middle fan assemblages contain small numbers of specimens and consequently the species diversity and relative abundance of morphogroups are inconsistent deep infaunal forms may be more common in this sub environment but because the abundance is low this observation should be treated carefully in contrast the abundance and diversity of the assemblages of the overbank fringe and basin plain sub environments are fairly high their morphogroup composition is also similar and comparable to each other when the assemblage size is large the assemblage from the interval with suggested hydrothermal activity is similar to those from outside the channel sub environment the presence of bottom water currents possibly in the form of a western boundary current in the basin is suggested based on the abundant occurrence of tubular forms in the overbank fringe and basin plain sub environments

aeolian sand transport and deposition patterns within a large woody debris matrix fronting a foredune abstract sediment transport pathways and resulting erosion deposition patterns across beach foredune systems can be complex although a great deal is known about the effects of wind fetch surface moisture topographic forcing and vegetation cover the role of large woody debris lwd as a control on sediment redistribution across beaches is relatively understudied pieces of lwd act as non porous roughness elements that induce secondary flow circulation thereby creating unique sedimentation patterns that differ markedly from those over a flat beach large accumulations of lwd collectively have a bulk porosity that provides substantial sand trapping volume yet no studies to date have quantified the effect of lwd on aeolian sand transport results from a field study on a macrotidal beach on calvert island british columbia canada show that the lwd matrix alters the character of the turbulent boundary layer in a way that reduces sediment flux by 99 sand is trapped within the lwd matrix thereby interrupting sediment delivery from the nearshore to the foredune as such lwd has the potential to modulate rates of foredune recovery growth and evolution the relative importance of this effect depends on the density and arrangement of lwd as a fundamental control on aeolian sediment transport as well as on the magnitude and frequency of events that erode the beach periodically and re organize the lwd matrix

spatial and temporal structure of shear layer turbulence at a stream confluence 1 the shear layer that develops at the interface between converging flows is a prominent but poorly understood hydrodynamic feature at stream confluences to examine the spatial and temporal characteristics of turbulence and coherent turbulent structures within a shear layer three dimensional velocity measurements were obtained at a small stream confluence in illinois using two acoustic doppler velocimeters spaced at various separation distances results indicate that coherent structures can be readily identified through cross correlation analysis of the velocity time series for different measurement locations maximum correlations decrease relatively slowly over short separation distances but decrease rapidly for separation distances greater than about 2 times the flow depth convective velocities of coherent structures derived from the correlation analysis differ from local mean velocities and from spatially averaged mean velocities indicating that coherent structures evolve as they are transported along the shear layer a finding consistent with dye tracing experiments despite this evolution correlation and spectral analyses indicate that the frozen turbulence hypothesis holds for frequencies corresponding to length scales of at least some shear generated coherent vortices a domain of quasi two dimensional turbulence energy at low frequencies appears to be associated with large scale intrusions of fluid from one stream into the other along the mixing interface

morphological diversity and complex sediment recirculation on the ebb delta of a macrotidal inlet normandy france a multiple lidar dataset approach the shoreline in the vicinity of inlets can exhibit considerable variability in morphology in both space and time most studies on inlets and their adjacent shores have focused on the morphodynamics of sediment by passing mechanisms generated by longshore transport for the first time the morphology sedimentary features sediment budgets and patterns of evolution of the shoreline and ebb delta in a macrotidal inlet system have been investigated using seven lidar topographic surveys in normandy france over a period of 3 7 years fromfebruary 2009 to october 2012 the ebb delta shows strong development on the northern flank of the inlet expressed by a large sand spit and two types of superimposed dynamic sandy features eight long crested and highly mobile transverse bars and a large swash bar sand transport fromn s on the updrift beach feeds the growth of the distal part of the spit this sand supply is further augmented by the onshore movement of a large swash barwelding to the upper foreshore however the main topographic changes were induced by the northward migration of the transverse bars on the ebb platform this is driven by strong northward directed tidal currents parallel to the shore the bars exhibit a more complex morphology and dynamics along the seaward margin of the ebb delta where their mobility is controlled by wave action topographic measurements suggest a clear sand recirculation pattern in this morphodynamic model sand coming from the updrift upper beach is transported southward and deposited at the distal end of the spit where it serves to construct transverse bars close to the tidal inlet transverse bar migration ends in the wave exposed northern margin of the ebb delta where they are integrated into the shallow dissipative shoreface sand sink this sink nourishes the southward longshore transport to feed growth of the large swash bar and southward spit elongation this semi circular recirculation cell model involves an inversion of sand movement close to the inlet and emphasizes the combined role of tidal currents and waves in the large scale 3d ebb delta sediment dynamics in this macrotidal setting in contrast to the much more commonly reported alongshore sediment by passing mode of microtidal inlets

three dimensional structure of flow at a confluence of river channels with discordant beds this paper presents three dimensional data of the mean and turbulent structure of flow collected at a natural confluence of rivers with discordant beds to 1 describe the three dimensional flow field of a natural junction of channels 2 assess the role of changes in bed morphology occurring during transport effective events on the structure of flow at a confluence and 3 examine how the three dimensional structure of flow varies with changes in the ratio of momentum flux between the two confluent streams three dimensional measurements of velocity were reconstructed from the measurements obtained with an array of four two component electromagnetic current meters six detailed velocity profiles were taken at five cross sections in a wide range of flow conditions the mean field of flow is characterised by 1 the acceleration of flow in the downstream portion of the post confluence channel but by lower velocities upstream in the mixing layer area 2 a stagnation zone at the apex of the junction 3 a zone of flow deviation and strong fluid upwelling close to the avalanche face and at the margin of the tributary mouth bar and 4 reduced velocities over the depositional bar at the downstream junction corner the position and extent of these zones vary with changes in the ratio of momentum flux very high intensity of turbulence peaks up to 50 and turbulent kinetic energy were observed in the mixing layer region distortion of the mixing layer characteristic of flow where bed discordance is present between the two tributary channels was evident from mean and turbulent flow data this field study suggests that the effects of bed discordance on flow sediment transport and the resultant bed morphology must be incorporated into conceptual and numeric models of these sites of complex flow

response of bed morphology and bed material texture to hydrological conditions at an asymmetrical stream confluence changes in bed morphology and sedimentology at stream confluences in relation to specific hydrological events have not been documented extensively moreover few if any studies have investigated the effect of net hydrological conditions on channel change at a confluence over a period of many years repeat cross section surveys and sampling of bed material at a small asymmetrical stream confluence reveal the short term effects of hydrological variability on bed morphology and spatial patterns of bed material texture survey data over a 15 year period illustrate the long term response of channel morphology at the confluence to net hydrological conditions results confirm that this confluence is a dynamic fluvial environment involving shifts in the zone of scour and repeated deposition and erosion of a bar complex at the downstream junction corner as the discharge ratio changes in response to hydrological variability in the tributary streams persistent faster runoff response times of the lateral tributary compared to the main stem have resulted in long term net erosion of the channel bank opposite this tributary the documented morphological and sedimentological changes are consistent with and can be explained by results of experimental studies and by past investigations at this confluence that have documented changes in patterns of mean flow structure and turbulence in response to variation in the discharge ratio of contributing streams

vegetated mixing layer around a finite size patch of submerged plants 1 theory and field experiments 1 dynamics of a vegetated mixing layer around a patch of submerged plants was examined theoretically and experimentally in a lowland river theoretical analysis explored analogy with hydrodynamic mixing layers and introduced equations that describe expansion of the layers and alterations in mean flow field experiments provided empirical data for validation of the theory and examination of the effects of population density on the mixing layer dynamics detailed measurements assessed the structure of turbulent flow plant morphology biomechanical properties bending and streamlining due to interaction with the flow the theory was compared with the field experiments and an agreement was concluded it was found that near the upstream edge of the patch the vegetated mixing layer expands similar to the canonical mixing layers although its statistics scale on the velocity differential characteristic for the stabilized part downstream mean momentum flux reduces in magnitude and reverses in direction while turbulence became dominant this was observed to stabilize the velocity differential and increase the mean velocity of the layer that result in its limited growth described by a logarithmic function the population density of vegetation was found to control the flow in dense vegetation the analogy with mixing layers resembled best while in sparse vegetation the flow behaved similar to the boundary layers this theory can be used for quantitative assessment of seasonal effects in natural vegetated rivers because the population density of vegetation varies during the vegetation season the companion paper focuses on the structural properties of turbulence in the vegetated shear layers

agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal ne atlantic porcupine abyssal plain abyssal hills small topographic features rising above the abyssal seafloor 1000 m altitude have distinct environmental characteristics compared to abyssal plains notably the presence of coarser grained sediments as a result they are a major source of habitat heterogeneity in the deep sea the aim of this study was to investigate whether there is a link between abyssal hills and the test characteristics of selected agglutinated benthic foraminiferal species we analysed 1 the overall morphometry and 2 the granulometric and chemical elemental characteristics of the agglutinated tests of ten common foraminiferal species adercotryma glomerata ammobaculites agglutinans cribrostomoides subglobosus lagenammina sp 1 nodulina dentaliniformis portatrochammina murrayi three reophax sp and recurvoides sp 9 at four sites two on top of abyssal hills and two on the adjacent plain in the area of the porcupine abyssal plain sustained observatory northeast atlantic the foraminiferal test data were compared with the particle size distribution and elemental composition of sediments from the study sites in order to explore possible grain size and mineral selectivity we found differences in the visual appearance of the tests i e the degree of irregularity in their shape which was confirmed by morphometric analyses related to seafloor topography the agglutinated foraminifera selected different sized particles on hills and plains reflecting the distinct granulometric characteristics of these settings these characteristics incorporation of coarse particles test morphometry could provide evidence for the recognition of ancient abyssal hill environments as well as other palaeoceanographic settings that were characterised by enhanced current flow furthermore analyses of sediment samples from the hill and plain sites using wavelength dispersive x ray fluorescence wd xrf yielded different elemental profiles from the plains probably a result of winnowing on the hills although all samples were carbonate rich in contrast the majority of the agglutinated tests were rich in silica suggesting a preferential selection for quartz

dune phases as time transgressive phenomena manawatu new zealand abstract new zealand s most extensive holocene dunefield is situated in the manawatu and adjoining regions evidence collected from the area including 25 radiocarbon dates suggests that the dunefield developed in phases with the first probably initiated at the coast earlier than 6000 years ago the first phase may have ceased near the coastline around 4500 years ago but dunes continued to migrate until they reached 16 km inland ca 1600 years ago about 3500 years ago dunes again began migrating inland from the coast with some still active 400 years ago the time transgressive nature of transgressive dune deposits and the possible causes of the dune phases are discussed

analysis of coastal dune dynamics shoreline position and large woody debris at wickaninnish bay pacific rim national park british columbia large woody debris lwd and colonizing vegetation alter the sediment budgets and stability of coastal dune systems in british columbia lwd on beaches consists largely of historical escape logs f

turbulent flow structure at a discordant river confluence asymmetric jet dynamics with implications for channel morphology only a handful of field studies have examined turbulent flow structure at discordant confluences the dynamics of flow at such confluences have mainly been examined in the laboratory this paper reports results of a field based investigation of turbulent flow structure at a discordant river confluence these results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than two exhibits jet like characteristics scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet this jet like behaviour of the flow has important implications for morphodynamic processes at these types of confluences the highly energetic core of the jet at this discordant confluence is displaced away from the riverbed thereby inhibiting scour however helical motion develops adjacent to the jet particularly at high flows which may promote scour numerical experiments demonstrate that that the presence or absence of a depositional wedge at the mouth of tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence

estimating bed shear stress from remotely measured surface turbulent dissipation fields in open channel flows synoptic information on bed shear stress is necessary in predicting the transport of sediments and environmental contaminants in rivers and open channels existing methods of estimating bed shear stress typically involve measuring vertical profiles of streamwise velocity or reynolds stress and taking advantage of the logarithmic or the constant stress region respectively to determine friction velocity and subsequently bed shear stress while effective these methods yield local measurements of bed shear stress only direct measurements of bed shear stress can also be obtained through measurements with a drag plate however this method yields average shear stress information over the area of the plate and is impractical for large scale implementation in the field here we present a method capable of providing continuous synoptic measurements of bed shear stress over a large field of view a series of large scale particle image velocimetry lspiv and acoustic doppler velocimetry adv measurements were made in a variety of flows generated in a wide open channel facility turbulent dissipation is calculated on the free surface from the 2 d lspiv results and is correlated with near surface adv measurements of turbulent dissipation in the water column the adv results are consistent with the nezu 1977 established relationship for the vertical variation of turbulent dissipation in the water column knowledge of the correlation between free surface and near surface dissipation values coupled with nezu s 1977 relationship allow a robust and accurate estimate of friction velocity to be made and subsequently shear stress at the bed can be estimated this article is protected by copyright all rights reserved

recent developments in quantitative stratigraphy abstract during the past 10 years about 150 scientists in 25 countries have collaborated under the auspices of the international geological correlation programme project no 148 evaluation and development of quantitative stratigraphical correlation techniques this paper reviews mathematical methods of stratigraphical correlation mainly in biostratigraphy but also in chronostratigraphy and lithostratigraphy sequencing methods treat the relative order of stratigraphic events such as the highest occurrences of fossil taxa as observed in many sections intervals between successive events in an ordered sequence can be estimated and the results expressed in linear time if a subgroup of the stratigraphical events can be dated recently such methods have been used to develop a new deep water benthic foraminiferal zonation for the cenozoic strata of the central and viking grabens north sea several regional hiatuses of 2 to 5 m y in duration can be recognized and matched to changes in sea level the same methods have been used for automated isochron contouring with error bars in depth or time units in cenozoic and cretaceous basins off eastern canada such information may be used for automated basin history analysis time successive assemblages of fossils can be established by using multivariate methods applied to co occurrences of events or by the method of unitary associations in conjunction with graph theory on the overlap of stratigraphical ranges other methods for stratigraphical correlation reviewed in this paper include the composite standard method and estimation of the age of chronostratigraphical boundaries using maximum likelihood and cubic spline interpolations attractions of quantitative stratigraphy are the use of rigorous methodology which highlights many properties of the data the ability to handle large and complex data bases in an objective manner and statistical evaluation of the uncertainty in the results generally little conceptual orientation is required in order to use these methods and thereby gain more information from a particular dataset

evolution of a foredune and backshore river complex on a high energy drift aligned beach abstract this paper examines the multi decadal evolution of a foredune and backshore river complex on a wave dominated drift aligned coast at wickaninnish bay on southwestern vancouver island british columbia canada local shoreline positions are generally prograding seaward as fast as 1 46 m a 1 in response to rapid regional tectonic uplift and positive onshore sediment budgets the northern end of the foredune system has extended rapidly alongshore in response to net northward littoral drift despite these net accretional responses the beach dune system experiences relatively frequent return interval 1 53 years erosive events when total water levels exceed a local erosional threshold elevation of 5 5 m above regional chart datum geomorphic recovery of the beach dune system from erosive events is usually rapid i e within a year by way of high onshore sand transport and aeolian delivery to the upper beach this response is complicated locally however by the influence of a backshore river that alters spatial temporal patterns of both intertidal and supratidal erosion and deposition historic landscape changes and rates of shoreline positional change are derived from several years of aerial photography 1973 1996 2007 2009 2012 using the usgs digital shoreline analysis system dsas significant volumetric changes are also estimated from aerial lidar derived dems in 2005 2009 and 2012 and related morphodynamics are interpreted using a statistically constrained geomorphic change detection method results suggest that supratidal bar development overwash deposition and aeolian deposition on a low lying supratidal platform combined with alongshore extension of the foredune complex is forcing sandhill creek to migrate northward in the direction of beach drift in response the river actively erodes 1 24 m a 1 a bluff system landward of the channel which generates substantial sediment volumes 0 137 m3 m 2 a 1 that feed a large intertidal braided channel and delta system these local responses provide context for a conceptual model of the evolution of a wave dominated drift aligned beach foredune system that interacts with a backshore river this model may provide useful information to local park managers as erosion and sedimentation hazards threaten visitor safety and park infrastructure

dynamics of shallow lateral shear layers experimental study in a river with a sandy bed shallow lateral shear layers forming between flows with different velocities though essential for mixing processes in natural streams have been examined only in laboratory settings using smooth fixed bed channels this paper reports the results of an experimental study of a shear layer in a straight reach of a natural river where the layer in contrast to the two dimensional structure observed in the laboratory is highly three dimensional the study included pronounced transverse pressure gradients which influenced shear layer structure compared to flume experiments it also introduces an analysis that complements conventional theory on mixing layers the lateral velocity gradient between the flows downstream from a splitter plate placed in the river the principal controlling factor was adjusted for three experimental runs to determine the influence of different gradients on shear layer dynamics in each run detailed three dimensional measurements of mean and turbulent characteristics were obtained at five cross sections downstream from the splitter plate although experimental results agreed with conventional mixing layer theories with respect to turbulence the dynamics of the shear layers were dominated by the mean lateral fluxes of momentum after re examining the governing equations we developed a parabolic equation describing the shear layer evolution and several scaling relations for essential terms of the energy budget mean and turbulent lateral fluxes of momentum turbulent kinetic energy and dissipation rates the study also provides insight into the spectral dynamics of turbulence in the shear layer and clarifies previous observations reported for confluences in natural streams

turbulence structure in a river reach with sand bed measurements and analysis of the three dimensional turbulence structure in a straight lowland river reach are presented accurate measurements of velocity profiles were taken with an acoustic doppier velocimeter adv and a multichannel micropropeller based system it is shown that analytical expressions derived from investigations of laboratory open channel flows agree well with the measured data only in the central part of the river where flow can be considered weakly three dimensional at the same time clear differences of empirical parameters between river and laboratory flows are detected it was established that river turbulence is isotropic for spatial scales smaller than the river depth the data also allowed the detection and analysis of the turbulence anisotropy impact on the formation of secondary currents special attention is paid to the investigation of coherent structures their spatial scales were evaluated applying the conditional average procedure based on uw quadrant analysis on average the scales of ejection and sweep events are as large as 1 5 times the flow depth

early eocene climatic optimum environmental impact on the north iberian continental margin the early eocene climatic optimum which constituted the peak of the long term early cenozoic global warming had a significant impact on the environmental evolution of terrestrial and oceanic areas surprisingly however its influence on continental margins is poorly known new insights are provided from a sedimentological stable isotope mineralogical and micropaleontological study of an 1100 m thick lower middle eocene deep marine succession that accumulated on the north iberian continental margin the early eocene climatic optimum is represented by a 410 m thick interval characterized by scarcity of hemipelagic limestones abundance of dark marls which record a reduction in calcium carbonate content and an increase in kaolinite and the occurrence of conspicuous red layers with high siderite and pyrite content series of stratigraphically significant events frame the early eocene climatic optimum based on this analysis the environmental influence of the early eocene climatic optimum started at 52 6 ma and lasted 2 3 m y its onset is marked by rapid drops in 13c and 18o which record the addition of 13c depletedcarbon into the ocean atmosphere system for 80 k y and a concomitant warming a hotter climate and a perennial rainfall regime increased the supply of terrestrial clays organicmatter and iron oxides into the sea eventually these changes affected the deepsea bottom 270 k y after the onset of the early eocene climatic optimum creating conditions in which opportunistic benthic foraminifera thrived and leading to increased methanogenesis in the subsurface which caused the formation of siderite a subsequent gradual recovery culminated abruptly at 50 3 ma with a global cooling episode which is locally recorded by the accumulation of lowstand resedimentation deposits 2015 geological society of america

case study effect of submerged aquatic plants on turbulence structure in a lowland river interactions of aquatic plants with turbulent flows in fluvial systems have attracted considerable interest while there have been recent advances in theories that describe vegetation flow interactions in idealized laboratory flows their practical application is still problematic due to limited knowledge of effects caused by heterogeneously patchy distributed plants in naturally formed vegetative mosaics in rivers this paper reports on a study in a lowland river aimed at quantification and parameterization of vegetation effects on redistribution of mean and turbulent characteristics of the flow and their consequences for hydraulic resistance the measurements were carried out in summer on a river reach with a patchy mosaic dominated by submerged flexible aquatic plants and repeated at the same water level in early spring before the plants start growing this design of the study allowed for quantitative evaluation of the effects caused by flow plants interactions on bulk flow parameters at comparable submergences of riverbed roughness elements sediment grains and sand bars the study indicates that symmetrical quasi two dimensional open channel flow structure in unvegetated riverbed was transformed into highly fragmented complex flow pattern spatially arranged by patches and free paths in the mosaic despite complexities and three dimensionality of the flow normalized mean velocity profiles in the patches were satisfactory described by hyperbolic tangent function while flow in the free paths similarly to unvegetated channel was in a reasonable agreement with the conventional logarithmic law

chronostratigraphy of late neogene sediments in the southern north sea basin and paleoenvironmental interpretations a chronostratigraphic framework has been established for upper neogene sediments from the northern netherlands offshore sector southern north sea data of dinoflagellate cysts pollen and foraminifers from eight boreholes are integrated and the resulting biostratigraphic events are connected to an additionally retrieved paleomagnetic record the sedimentary succession comprises at the base late to middle miocene sediments and spans the piacenzian to gelasian stages from 3 6 to 1 8 ma including the paleomagnetic gauss matuyama boundary and the olduvai subchron sedimentation rates vary between 30 cm kyr in the lower part of the succession and reach up to 84 cm kyr in the upper part these rates are high enough to record short paleomagnetic events and for the first time the presence of the so called x event has been recorded and dated at around 2 44 ma in a sedimentary setting the name north sea event is proposed here the paleoclimatic and paleoenvironmental information pictures the onset of northern hemisphere glaciation and the subsequent intensification of glacial conditions with its impact on the north sea sea region the paleoenvironmental changes are characterised by a stepwise development and five successive intervals are distinguished during the first interval a warm climate and an open marine setting prevailed the second interval is characterised by dominantly cold climatic conditions with occasional warmer periods during the third interval the environment became restricted marine and a stable freshwater layering occurred which facilitated the development of sea ice in the shallow sea within the fourth interval extreme cold arctic conditions were predominant and shallowing continued the fifth interval shows fluvial to deltaic paralic conditions from then on facies differences from the nearby delta system overruled the basin wide signals at the studied location 2006 elsevier b v all rights reserved

paleo oceanography global ocean evolution paleoceanography one of the youngest branches of earth sciences is concerned with the development of oceanic circulation through geologic time this is a multifaceted and integrated endeavor since none of the subdisciplines is easily separated from the others the field is holistic in character and includes the history and effects of bottom intermediate and surface circulation patterns planktonic and benthonic biogeographic development and rates of organic evolution the history of biogenic productivity and dissolution and their effect on sediment distribution and the consequences of sea level change paleoceanography was largely born of the deep sea drilling project dsdp and continues to be nourished by it because problems are of global scope the appetite for new sediment core material is large and is being supplied by numerous expeditions of dsdp this article is a brief overview of a number of advances that have occurred in paleoceanography and related fields during the period from 1979 to 1982 because of page limitations all publications cannot be cited which is not meant to indicate any lack of importance

shallow mixing layer downstream from a sudden expansion abstractthis study aims at investigating the mixing layer located at the interface between the free stream and recirculation zone downstream from a sudden lateral open channel expansion specific a

biostratigraphy and paleoenvironments of the late oligocene in the north western transylvanian basin revealed by the foraminifera assemblages abstract the paleoenvironmental evolution and biostratigraphy of the oligocene vima formation from the north western transylvanian basin maramure county romania is presented based on planktonic and benthic foraminiferal assemblages the deposits were assigned to late rupelian early chattian ages more precisely the globigerina angulisuturalis chiloguembelina cubensis crz o4 and paragloborotalia opima hoz o5 biozones the ecological preference of benthic foraminifera and statistical treatment of the raw data set were used to identify relationships between assemblages and reconstruct the ancient environments paleobathymetrical estimates indicate a deposition of the sediments in outer shelf to upper bathyal settings the shelf is characterized by alternating well oxygenated bottom waters and poor oxygen content indicated by low oxygen tolerant taxa the upper bathyal assemblages dominated by tubular agglutinated foraminifera suggest oligotrophic environments periodically disturbed by turbidite currents while the whole agglutinated communities suggest undersaturated bottom waters in respect to calcium carbonate and possible depletion in oxygen content due to water column stratification paleoclimatic reconstructions based on planktonic foraminifera suggest cool to temperate surface water temperatures with boreal influences the younger deposits of the f nt nele section indicate a warming trend at the surface waters the aggradational to progradational stacking pattern of the identified high frequency sequences suggest a high stand systems tract under the control of the regional tectonics

relative and absolute sea level rise in western canada and northwestern united states from a combined tide gauge gps analysis 1 empirical studies and climate models suggest large variations of absolute sea level asl changes between oceanic basins such potential variations raise concern on the applicability of global mean asl predictions to specific regions and on estimates of relative sea level rsl hazards we address this issue for the western canada and northwestern united states coastline by estimating the 20th century asl rate using a combination of 34 colocated tide gauge and global positioning system gps stations the tide gauge data are quality controlled and corrected for spatially and temporally correlated sea level transients in order to derive robust rsl trends and standard errors reference frame and other gps specific issues are considered as part of the error budget in absolute gps vertical velocities our combined tide gauge gps analysis aligned to the international terrestrial reference frame 2000 indicates a northeast pacific asl rise of 1 8 0 2 mm a through the 20th century which is similar to accepted rates for the global eustatic mean for the period 1993 2003 we find a regional asl rate of 4 4 0 5 mm a consistent with satellite altimetry on the basis of the intergovernment panel on climate change assessment report 4 mean scenario and our assessment of coastal motions from gps and tide gauge data we derive a map of predicted 21st century rsl rise in western canada and the northwestern united states variations in coastal uplift strongly affect spatial rsl patterns subsidence of southern puget sound may significantly increase rsl rise in the seattle tacoma metropolitan area conversely tectonic uplift along parts of the outer west coast may reduce future rsl rise by up to 50 100

experimental investigation of shallow recirculating flows experiments were conducted to study the bed friction influence in the recirculating zone of a shallow open channel flow velocity measurements were made using a hot film anemometer the recirculating flow rate and the length of the recirculating zone were determined from the measurements and they are related to a horizontal length scale and a bed friction length scale for deep flows the results are independent of the bed friction length scale for shallow flows the results are independent of the horizontal length scale turbulence in the recirculating flows is generated on one hand by the bed friction and on the other hand by the transverse shear the bed generated component is proportional to the bed friction velocity the transverse component is confined to a transverse mixing region in the limit of shallow water depth when the flow is under strong bed friction influence both the transverse mixing region and the recirculating zone have the same length of about one friction length scale

what is real identifying erosion and deposition in context of spatially variable uncertainty abstract the ability to ascribe landscape change to specific processes and events depends on the ability to accurately measure change with confidence many studies simply compute the difference between two digital elevation models dems and do not quantify and propagate vertical uncertainty from multiple sources not accounting for the influence of uncertainty on the results represents a particular problem in situations where the uncertainty of one or both surfaces varies across space and the spatial distribution of uncertainty is not consistent through time using lidar data from 2009 and 2016 for follets island texas usa the purpose of this study is to present a probabilistic approach to dem change analysis that accounts for spatially variable uncertainty surfaces and their impact on the computed dem change the probability that a computed change is not an artifact of the uncertainty in either surface is determined by computing the area where the two uncertainty distributions overlap this overlapping area provides information about the likelihood that the observed change is influenced by uncertainty in both surfaces the described approach is a relatively simple method for propagating uncertainty in one or more datasets however it is not an approach to quantifying uncertainty rather this approach relies on uncertainty from one or more sources already having been quantified given its adaptability to different datasets the change probability cp approach has potential application in identifying areas of real change in disciplines beyond coastal geomorphology

geospatial analysis of a coastal sand dune field evolution jockey s ridge north carolina preservation and effective management of highly dynamic coastal features located in areas under development pressures requires in depth understanding of their evolution modern geospatial technologies such as lidar real time kinematic gps and three dimensional gis provide tools for efficient acquisition of high resolution data geospatial analysis feature extraction and quantification of change these techniques were applied to the jockey s ridge north carolina the largest active dune field on the east coast of the united states with the goal to quantify its deflation and rapid horizontal migration digitized contours photogrammetric lidar and gps point data were used to compute a multitemporal elevation model of the dune field capturing its evolution for the period of 1974 2004 in addition peak elevation data were available for 1915 and 1953 analysis revealed possible rapid growth of the dune complex between 1915 1953 followed by a slower rate of deflation that continues today the main dune peak grew from 20 1 m in 1915 to 41 8 m in 1953 and has since eroded to 21 9 m in 2004 two of the smaller peaks within the dune complex have recently gained elevation approaching the current height of the main dune steady annual rate of main peak elevation loss since 1953 suggests that increase in the number of visitors after the park was established in 1974 had little effect on the rate of dune deflation horizontal dune migration of 3 6 m yr in southerly direction has carried the sand out of the park boundaries and threatened several houses as a result the south dune section was removed and the sand was placed at the northern end of the park to serve as a potential source sand fencing has been an effective management strategy for both slowing the dune migration and forcing growth in dune elevation understanding the causes of the current movements can point to potential solutions and suggest new perspectives on management of the dune as a tourist attraction and as a recreation site while preserving its unique geomorphic character and dynamic behavior d 2005 elsevier b v all rights reserved

the late cretaceous early paleocene palaeobathymetric trends in the southwestern barents sea palaeoenvironmental implications of benthic foraminiferal assemblage analysis the late cretaceous foraminiferal assemblages from five wells drilled in the southwestern barents sea were analysed using morphogroup analysis in order to understand the palaeoenvironment and palaeobathymetry of the study area morphogroup analysis of assemblages in the upper cretaceous kveite formation suggests stable possibly middle to lower bathyal mesotrophic and relatively well oxygenated environments in the tromso basin during the late cretaceous the depositional setting of upper cretaceous kviting formation in the tectonically more stable hammerfest basin was probably shallower but still represents a deep water environment similar to that of the kveite formation a shallowing regional bathymetry in the southwestern barents sea is indicated by the general decreasing trend in the relative abundance of tubular forms and the species diversity of assemblages which reflects the regional late cretaceous paleocene uplift prior to the break up of the greenland norwegian sea changes in the relative abundance of morphogroups and in the main constituent in the cumulative length of tubular taxa from rhizammina to rhabdammina near the top of kveite formation agree with the possible existence of bottom water currents c 2011 elsevier b v all rights reserved

a paleoslope model of campanian to lower maestrichtian foraminifera in the north american basin and adjacent continental margin campanian to early maestrichtian benthic foraminiferal assemblages of the new jersey and delaware coastal plain and the baltimore canyon trough contain distinct bathymetric biofacies each occurring in adjacent settings to one another in a profile downdip toward the north american basin the assemblages are interpreted as representing inner shelf to uppermost middle bathyal environments of deposition 10 to 500 m water depth a unique biofacies which consists of predominantly arenaceous foraminifera in a lithology of dark lignitic shales is present in restricted intervals within the baltimore canyon region this biofacies probably developed under oxygen deficient conditions in middle shelf to upper bathyal paleodepths within the north american basin benthic foraminifers from campanian to lower maestrichtian sections at various dsdp sites indicate that deposition took place in middle bathyal to abyssal environments 500 m to more than 3000 m paleodepth a complete paleoslope profile shelf to abyssal is identified within the north american basin and adjacent continental margin the foraminiferal composition of this paleoslope is as follows gavelinella nelsoni g pinguis lenticulina pseudosecans cibicides harperi andpullenia americana characterize shore face to inner shelf regions of 10 to 50 m water depth species that show maximum development in middle shelf environments 50 to 100 m water depth includeclavulina trilatera hoeglundina supracretacea and nodosariids in the outer shelf 100 200 m water depth praebulimina carseyae gavelinella compressa g spissocostata coryphostoma plaitum andpullenia jarvisi predominate the upper bathyal environment of 200 500 m water depth is characterized by species such asarenobulimina subspherica dorothia oxycona verneuilina dickinsonensis n sp stensioina exculpta gracilis andgyroidinoides globosus pullenia cretacea gavelinella ammonoides g whitei g intermedia praebulimina reussi p cushmani pleurostomella subnodosa andstilostomella pseudoscripta are species common to the middle bathyal environment of 500 to 1500 m water depth species that characterize lower bathyal environments 1500 to 2500 m water depth includearagonia velascoensis reussella szajnochae osangularia utaturensis clavulina gabonica tritaxia aspera andspiroplectammina dentata many of the middle and lower bathyal indicator species extend into the abyssal realm 2500 m water depth where they are associated with more abundant species such asaragonia ouezzanensis reussella pseudospinulosa hyperammina elongata rhizammina indivisa andsaccammina complanata the resulting paleoslope model allows a more critical evaluation of the role played by benthic foraminiferal species in shelf slope and abyssal environments it also enhances the accuracy of estimating paleobathymetry especially in shelf regions of the campanian to early maestrichtian

effect of clay fraction on turbulence characteristics of flow near an eroded bank abstract stream bank erosion in the alluvial channel is a matter of great concern particularly for the irretrievable loss of fertile land this in effect has direct impact on the agriculture environment economy and social issues at large a series of laboratory experiments were carry out to study the turbulence structure over eroded bank topography modulation of mean turbulent flow characteristics and the benefaction of turbulent bursting structures to the total reynolds shear stress due to the changed geometry of the eroded bank wall are described for three different clay fraction variations a side looking micro acoustic doppler velocimeter adv was used to record the detailed high frequency velocity data near the bank wall to understand the coupled dynamics of flow and erosion on sediment water interface the information on clay and fine sand content of natural river bank was obtained from field observation results from the present study indicate that higher turbulence intensities and reynolds shear stress have prominent role in the removal of bank materials from the bank wall and continues the dislodgement of material from the bank face until mass failure quadrant analysis to the random velocity fluctuation in the vicinity of eroded stream bank shows that downstream bank material movement is strongly correlated to the presence of sweep events probability density function pdf kinetic energy fluxes and coefficients of skewness and kurtosis of velocity fluctuations show significant changes with the change in clay fraction of the bank material composition though the velocity spectral densities are in general observed to be similar for all the three different bank undercut depths for different clay fraction of bank however spectral energy shows signature of higher energy peak for lower clay fraction of the bank material

influence of sediment transport dynamics and ocean floor morphology on benthic foraminifera offshore fraser island australia abstract the extensive longshore sediment transport system along the se margin of australia transports yearly 500 000 m 3 of sand from the gold coast of southern queensland north towards fraser island fraser island which consists of 203 km 3 of quartz sand is presently not increasing in size and north of the island quartz sand is replaced by carbonate sand recent multibeam sonar seafloor imagery and sediment analysis has established that the transported sand is being diverted by strong ebb tidal flow over the continental shelf edge onto the tasman abyssal plain through a series of active gullies that incised the continental slope foraminiferal distribution patterns on the shelf and slope are closely linked to the variable ocean floor morphology and associated physical processes in sample locations outside the continental slope gullies areas unaffected by downslope sediment transport foraminiferal assemblages gradually change in accordance with bathymetric zones and their prevailing ecological parameters species diversity evenness the proportion of infaunal species and the abundance of agglutinated taxa all increase with depth assemblages within gullies of the clastic sand transport route are significantly different estuarine and shelf species are transported over the shelf break and mix with typical slope species along the transport path resulting in continued high species diversities as the sediment and faunal load enters the abyssal plain a faunal portion continues to travel within the capricorn sea valley to over 4000 m depth the erosional nature of gullies results in reduction of agglutinated species subtle topographic features such as ridges or levees within the canyon and deep sea valley act as protection from the main erosional sand transport pathway and support the presence of fragile and erect suspension feeders foraminiferal distribution patterns would have received an entirely different biofacies interpretation without linking them to ocean floor processes as revealed through multibeam sonar imagery

measurements and numerical simulations of the degree of activity and vegetation cover on parabolic dunes in north eastern brazil in this work we present measurements of vegetation cover over parabolic dunes with different degrees of activation along the north eastern brazilian coast we extend the local values of the vegetation cover density to the whole dune by correlating measurements with the relative brightness index c of high resolution quickbird panchromatic satellite images of the dune field we then introduce the vegetation data into a continuous model for vegetated dunes coupling sand erosion and vegetation growth and perform simulations of the evolution of the morphology and vegetation cover of parabolic dunes finally from the comparison of both the measurements and the simulation results we show that the model is able to predict the dune shape and the vegetation distribution of real parabolic dunes as result of the evolution of a blow out