was the black sea catastrophically flooded in the early holocene abstract a catastrophic flooding of the black sea basin was proposed to have occurred during its reconnection to the ocean in the early holocene possible cultural consequences of the flood include the migration of neolithic farmers from around the black sea towards central europe as well as the creation of flood myths stratigraphic and paleo geomorphologic information from danube delta aided by radiocarbon ages on articulated mollusks constrain the level in the black sea before the marine reconnection to ca 30 m below the present sea level rather than 80 m or lower if the flood occurred at all the sea level increase and the flooded area during the reconnection were significantly smaller than previously proposed

the formation and evolution of the barrier islands of inhaca and bazaruto mozambique abstract the barrier islands of inhaca and bazaruto are related to the extensive coastal dune system of the mozambican coastal plain south east africa optically stimulated luminescence osl dating of key stratigraphic units indicates that accretion of sediment within these systems is episodic both islands appear to have been initiated as spits extending from structural offsets in the coastline superposition of significant quantities of sediment upon these spits during subsequent sea level highstands formed the core of the islands which were anchored and protected by beachrock and aeolianite formation at least two distinct dune building phases occurred during marine oxygen isotope stage mis 5 tentatively attributed to marine transgressions during sub stages 5e and 5c although some localized reactivation of dune surfaces occurred prior to the holocene large quantities of sediment were not deposited on either island during the low sea levels associated with mis 2 significant dune building and sediment reworking occurred immediately prior to and during the holocene though it is not clear whether these processes were continuous or episodic significant erosion of the eastern shoreline of bazaruto suggests that it is far less stable than inhaca and may suffer further large scale erosion a model is presented for the formation of barrier islands along the mozambican coastal plain

beach ridge plain evidence of a variable late holocene tropical cyclone climate north queensland australia abstract to date most studies of long term tropical cyclone records from beach ridge plains coral shell and sand have suggested that there has been little variation in the intensity of these events over the late holocene this study of a sand beach ridge plain in northeast queensland australia using sedimentary analysis and luminescence chronology suggests there has been considerable variation in both the intensity and frequency of tropical cyclones here since the mid holocene most of the previous beach ridge studies have been of relatively uniform elevation coral shingle shell and sand beach ridges within the plain here at rockingham bay the sediments are composed of coarse grained sand and there is considerable variation in ridge height and the number of ridges emplaced over different time intervals it may be that pure sand ridges provide a more sensitive record of variations in long term tropical cyclone climatology which in turn may contribute to a considerably improved understanding of the behaviour of this natural hazard

evidence for a transgressive barrier within a regressive strandplain system implications for complex coastal response to environmental change clastic depositional strandplain systems have the potential to record changes in the primary drivers of coastal evolution climate sea level and the frequency of major meteorological and oceanographic events this study seeks to use one such record from a southern brazilian strandplain to highlight the potentially complex nature of coastal sedimentological response to small changes in these drivers following a 2 to 4 m highstand at ca 5 8 ka in southern brazil falling sea level reworked shelf sediment onshore forcing coastal progradation smoothing the irregular coastline and forming the 5 km wide pinheira strandplain composed of ca 500 successive beach and dune ridges sediment cores grab samples and 11 km of ground penetrating radar profiles reveal that the strandplain sequence is composed of well sorted fine to very fine quartz sand since the mid holocene highstand the shoreline prograded at a rate of ca 1 to 2 m yr 1 through the deposition of a 4 to 6 m thick shoreface unit a 1 to 3 m thick foreshore unit containing ubiquitous ridge and runnel facies and an uppermost beach and foredune unit however the discovery of a linear 100 m wide barrier ridge with associated washover units a 3 to 4 m deep lagoon and 250 m wide tidal inlet within the strandplain sequence reveals a period of shoreline transgression at 3 3 to 2 8 ka during the otherwise regressive developmental history of the plain the protected nature of pinheira largely buffered it from changes in precipitation patterns wave energy and fluvial sediment supply during the time of its formation however multiple lines of evidence indicate that a change in the rate of relative sea level fall probably due to either steric or ice volume effects may have affected this coastline thus whereas these other potential drivers cannot be fully discounted this study provides insights into the complexity of decadal scale to millennial scale coastal response to likely variability in sea level change rates

morphology of the itapeva to tramandai transgressive dunefield barrier system and mid to late holocene sea level change the surface morphology of the transgressive dunefield barrier extending from itapeva to tramandai along the northern littoral of rio grande do sul is examined and an attempt is presented to link morphological changes across the barrier to holocene sea level changes the 4 5 km wide holocene barrier displays two typical morphologies an inner part dominated by large scale continuous alongshore overlapping dunefield phases comprising sand sheets dunes deflation plains and precipitation ridges and an outer part dominated by discontinuous medium to small scale triangular to lobate transgressive dunefield phases cut by both active and relict palaeo creeks or washouts holocene sea level in the region rose to c 1 to 3 m above present reaching a maximum around 5100 years bp and then progressively fell to the present level we argue that the effect on barrier development was to suppress the development of a drainage system during the rising and maximum stages and encourage the development of an organized drainage system in the form of regularly spaced washouts during the falling period and that this change in sea level from rising to falling therefore produced the large scale differences in barrier morphology copyright 2006 john wiley sons ltd

spatial patterns of sediment dynamics within a medium sized watershed over an extreme storm event abstract in this study we quantified spatial patterns of sediment dynamics in a watershed of 311 km 2 over an extreme storm event using watershed modeling and statistical analyses first we calibrated a watershed model dynamic watershed simulation model dwsm by comparing the predicted with calculated hydrograph and sedigraph at the outlet for this event then we predicted values of event runoff volume v peak flow q peak and two types of event sediment yields for lumped morphological units that contain 42 overland elements and 21 channel segments within the study watershed two overland elements and the connected channel segment form a first order subwatershed several of which constitute a larger nested subwatershed next we examined i the relationships between these variables and area a precipitation p mean slope s soil erodibility factor and percent of crop and pasture lands for all overland elements i e the small spatial scale sss and ii those between sediment yield q peak a p and event runoff depth h for the first order and nested subwatersheds along two main creeks of the study watershed i e the larger spatial scales lss we found that at the sss sediment yield was nonlinearly well related to a and p but not q peak and h whereas at the lss linear relationships between sediment yield and q peak existed so did the q peak a and q peak p relationships this linearity suggests the increased connectivity from the sss to lss which was caused by ignorance of channel processes within overland elements it also implies that sediment was transported at capacity during the extreme event so controlling sediment supply from the most erodible overland elements may not efficiently reduce the downstream sediment load

late pleistocene and holocene environmental change inferred from the cocha caranga sediment and soil records in the southeastern ecuadorian andes abstract late pleistocene and holocene vegetation climate and fire dynamics of mountain forest and paramo ecosystems as well as human impact are presented from the cocha caranga area at 2710 m elevation in the podocarpus national park southeastern ecuadorian andes palaeoenvironmental changes inferred from two sediment cores and a soil core were investigated by pollen spore algae and charcoal analyses during the transition from late pleistocene to early holocene between ca 14 500 to 9700 cal yr bp upper mountain forest vegetation expanded suggesting increasing temperature and moisture this expansion abruptly stopped with increasing fires at ca 9700 cal yr bp and open grassy vegetation became established the period from ca 9700 to 1300 cal yr bp of strong fire intensity indicate that vegetation components mainly weinmannia and myrica react sensitively to past probably human caused fires during the last few centuries modern vegetation established characterised by open grassy areas with forest patches and small mires the green algae botryococcus braunii isoetes and cyperaceae were used to identify lake level fluctuation to reconstruct holocene wet dry phases drier climatic conditions occurred from ca 9700 to 6900 cal yr bp and from ca 4200 to 1300 cal yr bp from ca 6900 to 4200 cal yr bp and from ca 1300 cal yr bp to modern times wetter climatic conditions occurred

human influence and the changing geomorphology of mediterranean deltas and coasts over the last 6000 years from progradation to destruction phase the present geomorphology of the mediterranean s coasts is largely a product of an intricate long term relationship between nature and human societies a cradle of ancient civilisations the mediterranean has seen its shores occupied by humans since prehistory and is therefore a particularly pertinent unit of analysis the morphotectonic context and other forcing agents e g climate shaped out a highly diversified coastal morphology and generated a sediment supply regime potentially favourable to the formation of numerous open coast deltas and bay head deltas in infilled rias as sea level stabilised during the mid holocene this supply of riverine sediment has also been the key agent in mediating human occupation of the mediterranean s clastic coasts expressions of this relationship have been extensively archived in clastic coastal deposits including base level deltaic and estuarine sedimentary sinks which comprise records to explore the interactions between geosystems and the human environment the stratigraphic sequences in these coastal sedimentary archives comprise in many places a clearly identified anthropogenic signature notably in ancient harbours some of which underwent extremely rapid silting up due to massive sediment sourcing generated by new agricultural practices from the neolithic onwards increasing human influence especially over the last 3000 years has been in turn an important driver of changes in sediment supply strongly modulating deltaic development pulses of sediment supply from catchments rendered vulnerable by human perturbations during the roman period resulted in a new cycle of inception of many other deltas and in rapid delta growth e g the ebro the po the arno and the ombrone another progradation dynamic during the little ice age at a time of strong rural population growth river discharge increases technological developments and urbanisation further consolidated delta growth understanding the life cycle of these deltas since their initial formation is in turn key to unravelling the relative role of natural and anthropogenic forcing agents rapid climate changes are deemed to have contributed through both the stripping of landscapes rendered fragile by human activities and active fluvial sediment transport to the coast but disentangling climate change effects from human impacts in the mediterranean remains a challenge the patterns of subsequent deltaic growth and delta morphodynamics reflect adaptations to pulsed sediment supply river discharge variations the microtidal fetch limited context of the mediterranean and direct engineering interventions the progradation dynamic of the roman period and little ice age contrasts markedly with the situation of common coastal destabilisation over the last two centuries particularly well documented for the last 50 years this period has been characterised by reduced sediment flux to base level geosystems due to catchment reforestation retenion within reservoirs fluvial regulation and dredging resulting in the erosion of deltas and barrier lagoon and beach dune systems large stretches of shoreline and narrow coastal plains have been massively engineered for coastal defence and protection against erosion but also for the construction of marinas leisure harbours and artificial beaches resulting in the emergence of veritable artificial seafronts these interventions have collectively and progressively raised societies to a pervasive and overarching position in the geomorphic stability instability of the mediterranean s coasts a situation that will be exacerbated by pressures from sea level rise paving the way for rampant coastal erosion and delta destruction

quantifying rates of coastal progradation from sediment volume using gpr and osl the holocene fill of guichen bay south east south australia guichen bay on the south east coast of south australia faces west towards the prevailing westerly winds of the southern ocean the bay is backed by a 4 km wide holocene beach ridge plain with more than 100 beach ridges the morphology of the guichen bay strandplain complex shows changes in the width length height and orientation of beach ridges a combination of geomorphological interpretation shallow geophysics and existing geochronology is used to interpret the holocene fill of guichen bay six sets of beach ridges are identified from the interpretation of orthorectified aerial photographs the ridge sets are distinguished on the basis of beach ridge orientation and continuity a 2 25 km ground penetrating radar gpr profile across the beach ridges reveals the sedimentary structures and stratigraphic units the beach ridges visible in the surface topography are a succession of stabilized foredunes that overlie progradational foreshore and upper shoreface sediments the beach progrades show multiple truncation surfaces interpreted as storm events the gpr profile shows that there are many more erosion surfaces in the subsurface than beach ridges on the surface the width and dip of preserved beach progrades imaged by gpr shows that the shoreface has steepened from around 2 9 to around 7 5 the changes in beach slope are attributed to increasing wave energy associated with beach progradation into deeper water as guichen bay was infilled at the same time the thickness of the preserved beach progrades increases slightly as the beach prograded into deeper water using the surface area of the ridge sets measured from the orthophotography and the average thickness of upper shoreface foreshore and coastal dune sands interpreted from the gpr profile the volume of holocene sediments within three of the six sets of beach ridge accretion has been calculated combining optically stimulated luminescence osl ages and volume calculations rates of sediment accumulation for ridge sets 3 4 and 5 have been estimated linear rates of beach ridge progradation appear to decrease in the mid holocene however the rates of sediment accumulation calculated from beach volumes have remained remarkably consistent through the mid to late holocene this suggests that sediment supply to the beach has been constant and that the decrease in the rate of progradation is due to increasing accommodation space as the beach progrades into deeper water changes in beach ridge morphology and orientation reflect environmental factors such as changes in wave climate and wind regime

high angle wave instability and emergent shoreline shapes 1 modeling of sand waves flying spits and capes 1 contrary to traditional findings the deepwater angle of wave approach strongly affects plan view coastal evolution giving rise to an antidiffusional high wave angle instability for sufficiently oblique deepwater waves with angles between wave crests and the shoreline trend larger than the value that maximizes alongshore sediment transport 45 a one contour line numerical model shows that a predominance of high angle waves can cause a shoreline to self organize into regular quasiperiodic shapes similar to those found along many natural coasts at scales ranging from kilometers to hundreds of kilometers the numerical model has been updated from a previous version to include a formulation for the widening of an overly thin barrier by the process of barrier overwash which is assumed to maintain a minimum barrier width systematic analysis shows that the wave climate determines the form of coastal response for nearly symmetric wave climates small net alongshore sediment transport cuspate coasts develop that exhibit increasing relative cross shore amplitude and pointier tips as the proportion of high angle waves is increased for asymmetrical wave climates shoreline features migrate in the downdrift direction either as subtle alongshore sand waves or as offshore extending flying spits depending on the proportion of high angle waves numerical analyses further show that the rate that the alongshore scale of model features increases through merging follows a diffusional temporal scale over several orders of magnitude a rate that is insensitive to the proportion of high angle waves the proportion of high angle waves determines the offshore versus alongshore aspect ratio of self organized shoreline undulations

landscape evolution during the late quaternary at the doce river mouth espirito santo state southeastern brazil article the sedimentary deposits of the deltaicplain of the doce and barra seca rivers southeastern brazil were studied by faciesanalysis pollenrecords 13 c c n analysis and ams 14 c dating today thisdeltaicplain isdominated by beach ridges and sandy terraces occupied by arboreal and herbaceous vegetation between 47 500 and 29 400 cal yr b p a deltaic system was developed in response mainly to eustatic sea level fall although the studied stratigraphic succession is compatible with the trend of global sea level fall the earlier sea level sug gested by the topographic position of these deltaic deposits was above the one expected during the mis3 stage a tectonic uplift likely occurred during the late quaternary and raised these deposits the post glacial sea level rise caused a marine incursion with invasion of embayments and broad valleys and it favored the evolution of an estuary with wide tidal mud flats occupied by mangroves between 7400 and 5100 cal yr b p the high river sand supply and or the relative sea level fall in the late holocene led to seaward and downward translation of the shoreline during normal forced regression producing progradational deposits with shrinkage of mangrove stands and expansion of marshes colonized by herbaceous vegetation therefore the stratigraphic architecture and evolution of the doce river deltaic plain suggest that fluvial sediment supply and relative sea level fluctuations related to quaternary global climatic changes and local tectonism exerted major controls on sedimentation through the variation of accommodation space and base level changes

the late holocene evolution of the black sea a critical view on the so called phanagorian regression abstract throughout its geologic history the black sea experienced major sea level changes accompanied by severe environmental modifications including geomorphologic reshaping the most spectacular changes were driven by the quaternary glaciations and deglaciations that reflect responses to milankovitch cycles of 100 and 20 ky periodicity major sea level changes were also considered for a shorter and more recent cyclicity the concept of the phanagorian re and transgression cycle supposedly with a minimum sea level stand of 5 6 m below its present position in the middle of the 1st millennium bc was established in 1963 by fedorov for the black sea region it was based on archaeological and palaeogeographical research conducted around the ancient greek colonies of the cimmerian bosporus in particular at the name giving site of phanagoria where underwater prospection had revealed the presence of a large number of submerged relics of the classical greek era analyses of sediment cores as well as 14c dated fossil coastal bars in the western and southern parts of taman peninsula show that contemporary coastal bars are related to different sea levels the dissymmetry can reach up to 6 m around 500 bc this and more evidence from drill cores confirms that on taman peninsula many of the apparent sea level changes are tectonically induced the subsidence may have been initiated by the release of gas from mud volcanoes inherited along anticline axes other observations around the black sea confirm that submerged archaeological sites correspond to areas where subsidence has taken places while the so called holocene highstand said to have been located above the present day sea level is associated with uplift areas triggered by the ongoing caucasus orogeny recent oceanographic research carried out in the black sea area shows that since the black sea was reconnected with the mediterranean sea i e 7500 14c bp at the latest both marine water bodies have been in equilibrium this fact and arguments from archaeology history hydrodynamics etc lead us to question the existence of the phanagorian regression it is important to note that none of the sea level curves established for the eastern mediterranean shows a comparable regression transgression cycle of several metres during the 1st millennium bc

evidence for storm dominated early progradation of castle neck barrier massachusetts usa abstract washovers dune scarps and flattened beach profiles with concentrations of coarse grained sediment or heavy minerals are the diagnostic geological signatures of large storms on barriers today it is clear that storms are a major force driving transgressive barriers onshore but what is not as well understood is the role these powerful erosive events play in the evolution of prograding barriers application of ground penetrating radar gpr and a combination of coring techniques have significantly improved our ability to image barrier architecture results of these studies reveal a more complex evolution than previously recognized it is now possible to precisely locate and map storm deposits within prograded barrier lithosomes a comprehensive study of northern castle neck massachusetts was performed using 15 km of gpr surveys a 120 m long seismic line 11 cores and several radiocarbon dates storm related layers are the most prominent horizons contained in the barrier stratigraphy the geometry and sedimentology of these layers closely resembles those of a present day post storm beach twenty closely spaced curvilinear heavy mineral layers imaged in the landward portion of the barrier suggest that the castle neck barrier was heavily influenced by storms during its initial phase of progradation beginning 4000 years bp approximately 1800 years bp two intense storms impacted the coast depositing two extensive coarse grained units these layers mimic the flat lying sand and gravel deposits that occur in front of a nearby eroding till outcrop following major storms the great number of storm deposits in the early history of castle neck is related to either a period of greater storm activity and or a slow rate of barrier progradation the occurrence and preservation of these earlier storm layers are likely a product of the exposure of nearby drumlins resulting in greater availability of iron oxide and ferromagnesian sands the supply of heavy mineral sands has gradually diminished as the barrier prograded and the proximal drumlin source was buried by beach and dune sands

young danube delta documents stable black sea level since the middle holocene morphodynamic paleogeographic and archaeological implications new radiocarbon and optical dates show that the holocene danube delta started to build out of a black sea embayment 5200 yr ago delta lobe development phases differ by as much as 5 k y from previously proposed ages the new chronology allows for a better understanding of the danube delta paleogeography includ ing the demise of istria the main ancient greek roman city in the region prior reconstructions of sea level in the black sea inferred fluctuations to 15 m in range however stratigraphy of beach ridg es in the delta shows that the relative black sea level for the past 5 k y was stable in the danube delta region within 2 m and 1 5 of the current level hydroisostatic effects related to a proposed catastrophic reconnection of the black sea to the world ocean in the early holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models the new sea level data suggest that submergence at several ancient settle ments around the black sea may be better explained by local fac tors such as subsidence rather than by basin wide sea level fluctuations

juxtaposed beach ridges and foredunes within a ridge plain wonga beach northeast australia abstract reports describing aeolian foredunes and wave derived beach ridges juxtaposed within a single coastal barrier complex are rare perhaps because morphological similarities make the two ridge types difficult to differentiate this study of an approximately 4500 year old sand ridge plain in northeast queensland australia using landform morphology sedimentology and luminescence chronology suggests that ridge plain development here has been interrupted along part of the sequence by localised alterations in coastal sedimentation a switch from coarse to fine grained sand supply along one part of the beach has caused the development of prograding foredunes in the northeastern sector of the sequence over the past 700 years contemporaneously coarser textured beach ridges have continued to form behind the remainder of the beach the result is a complex barrier where a single ridge plain contains both foredunes developed through high frequency low intensity events and beach ridges developed through high intensity low frequency events associated with intense tropical cyclones

wave climate coastal sediment budget and shoreline changes for the danube delta abstract since its formation approximately 12 000 years ago the coastal zone of the danube delta experienced alternating periods of accretion and erosion related to the natural process of lobe abandonment caused by river avulsion over the last 150 years the effects of human interventions modified these natural trends regulation of the danube river e g the iron gates barrages facilitating navigation and controlling river discharge construction and extension of the sulina entrance jetties and dredging of the sulina mouth bar for navigational purposes are examples of human interventions that influenced and still influence the actual state of the danube delta coastal zone most importantly these interventions diminished the quantity of sediments reaching the coast and consequently led to a severe retreat of the shoreline especially in the sulina sf gheorghe coastal sector to investigate and quantify the recent sediment budget and associated shoreline changes along the danube delta coastal zone we constructed a hindcast of the wave climate the alongshore transport capacity and the resulting sediment budget using a numerical coastline model on a local scale it was found that overwash plays an important role i e the observed evolution of sahalin spit island shows a cross shore landward migration that is much larger than could be explained by the calculated alongshore sediment transport gradients on a delta scale however the resulting alongshore sediment transport gradients and associated sediment budgets comply very well with the observations confirming the dominant role of wave induced alongshore transport and giving confidence in our predictions regarding the shoreline position for the next 25 and 50 years the results of this study indicate the potential for broader applicability of the model to other deltas especially those in wave dominated settings

formation of danube delta beach ridge plains and signatures in morphology abstract danube delta as most of the large deltas favours complex interactions between river sediment supply and marine dispersing forces which create complex configurations with concurrent morphologies i e river versus wave influenced or processes accretion versus erosion and even distinct landscapes for the same accretionary features strandplains with low monotonous beach ridges or covered by transgressive dunefields beach ridge plains brps are a common feature of the wave influenced deltaic lobes that are created by juxtaposition of succesive berms on the prograding sandy coasts with different shapes and sizes depending on the accretionary mechanisms and the accomodation space this study reports the formation and dynamics of danube delta brps based on numerical age determination osl and ams of the paleoshorelines topographic and geophysical gpr surveys and stratigraphic records by cores a chronological framework is established for all deltaic brps which points to the importance of formation timespan and growth rate as a consequence of sediment supply on the resultant morphology varying inter site from small brp formation time

geodynamic and hydro geological constraints regarding the extension of the prospective archaeo cultural area within the northern romanian coastal zone abstract an obvious discrepancy is noticed between the very few archaeological sites discovered until now on the danube delta plain area and the large number of such sites whose ages range from the middle paleolithic to the middle ages and more recently identified on its higher topography surroundings the combined effects of the regional subsidence of the coast and delta area with amplitudes of 2 to 4 mm y and of the secular mean sea level rise 0 5 1 0 mm y continuously change the land mean sea level relative relationship placing the prospective archaeo cultural layer corresponding to the late prehistory antiquity period at a burial depth which now exceeds 4 5 m this situation partly explains the limited success of the archaeological research carried out until now within the danube delta plain area and recommends a systematic use of the geophysical investigation methods in future the integrated interpretation of the coastal zone bathymetry and sedimentology mappings and of the shoreline geomorphological evolution in time highlights the sedimentary processes that presently shape the littoral study zone allowing to divide it in sectors where either sediments accumulation or erosion processes prevail the study draws attention to the impu ita c sla v danei and cosna vadu littoral sectors where the intense marine erosion of the shoreline and the adjacent seabed also imminently endangers their prospective archaeo cultural load

wave current interactions in a wave dominated tidal inlet 1 wave current interactions play a major role in the dynamics of shallow tidal inlets this study investigates these interactions at a natural inlet with a strong focus on current induced changes on wave propagation the analysis of hydrodynamic data collected at the albufeira lagoon portugal revealed spatiotemporal variations of water levels and wave heights along the inlet attributed to wave current interaction processes we compared the simulations of a coupled wave circulation modeling system computed with and without waves and propagated with and without current feedback the wave induced setup inside the lagoon represented 7 15 of the offshore significant wave height the accuracy of the wave s predictions improved when current feedback was included during ebb the currents increased the wave height at the mouth of the inlet up to 20 and decreased the wave height in the inlet up to 40 due to current induced refraction steepness dissipation and partial blocking during flood the currents decreased the wave height in the inlet up to 10 and increased the wave height at the exterior parts of the ebb shoal up to 10 due to current induced refraction these effects significantly attenuate seaward sediment fluxes during ebb and contribute to the sediment accretion in the inlet

wave influence in the construction shaping and destruction of river deltas a review abstract waves are an important agent in the construction shaping and destruction of river deltas notwithstanding the commonality of waves in oceans and seas wave influence on deltas varies considerably depending on the coastal morphology and nearshore bathymetry although there have been advances in understanding the way waves approaching a delta shape its shoreline much still remains to be known of the interactions between waves and river deltas deltas are built essentially from sediments supplied by rivers sand sized and coarser sediments may also be derived from nearby abandoned delta lobes or from older relict nearshore deposits transported by wave reworking and longshore currents alternatively delta erosion by waves can also release sediment that is redistributed alongshore or that accumulates offshore the extent to which bedload is supplied to and sequestered in or lost by deltas through waves and longshore transport strongly depends on interactions between waves and fluvial discharge at the river mouth these interactions and the mutual adjustments they engender are not only important in the overall balance between delta retreat progradation or aggradation but also in processes such as avulsion and channel switching as well as in the eventual survival of a delta in the face of sea level rise where waves are important fluvial liquid discharge is high and sediment supply is rich in bedload two important aspects are the blocking of waves and longshore currents by strong river discharge and the formation of bars at the river mouth field studies of the complex interactive processes prevailing where river flows encounter waves are however non existent and numerical modelling though promising hampered by scale constraints and the difficulty of replicating them and generating mouth bars in the presence of longshore currents this interaction influences the seaward extent of the delta mouth protuberance and its stability this protuberance then forming the regional shoreline template to which waves and longshore currents adjust longshore currents can redistribute wave reworked mouth bar deposits emplaced during strong river flow transport may be either divergent from the mouth or may be regionally unidirectional but wherein the symmetry of some deltas probably rare may be maintained by a strong river blocking effect on transport from the updrift flank the mouth protuberance may be such as to foster transport reversal counter drift at the delta margins that contributes to sediment sequestering within the delta these interactions largely contribute in shaping delta shorelines and together with the abundance of sediment supply and grain size determine the resultant wave formed shoreline barrier types which include spits more or less closely spaced beach ridges and barrier islands and cheniers in situations of punctuated progradation or retreat where several distributary mouths occur pronounced longshore variability in wave processes and wave induced sediment transport may ensue resulting in multiple drift cells that assure the retention of sand and coarse grained sediments within the delta waves can also be an important agent in the reworking and retreat of mud rich deltas that generally conform in morphology to the river dominated such as the mississippi or tide dominated such as the ganges brahmaputra or chao phraya types resulting in the episodic formation of sandy cheniers and beach ridges although sea level rise is likely to lead to enhanced wave reworking of deltas the possible prevalence of aggradation in lieu of progradation channel switching and avulsion and washover processes may contribute to the disorganization of waves and longshore transport fostering deltaic sequestering of sand and coarser sized sediment and delta survival the weakening of river discharges resulting from human activities will invariably lead however to enhanced wave reworking of deltas and to deltaic sediment redistribution by longshore currents the massive swing towards significant reductions in fluvial sediment supply today may signify the ultimate demise of many deltas in the coming decades through a process of delta shoreline straightening by waves in addition to accelerated sinking these various foregoing aspects of the relationship between waves and river deltas are reviewed here across a range of timescales and new interaction concepts proposed using numerous examples of deltas in the world and on the basis of case studies conceptual studies and numerical modelling studies in the literature spanning more than forty years

aeolian beach ridges and their significance for climate and sea level concept and insight from the levant coast east mediterranean abstract relict beach ridges of aeolian origin and associated soils are often used for inferring relative sea level and climate with contrasting results most studies link the aeolian coastal deposits to regressive phases some to high sea level stands and a few to intermediate relative sea level positions we interpret the apparent contradictions as indicating the lack of an over arching concept and the inconsistent usage of sea level related terms in this paper we present an integrated morpho sedimentological concept for a microtidal mid latitudinal coast and review existing data from the levant east mediterranean coast to evaluate the concept and to eliminate nomenclatural confusion a coastal depositional environment in a semi arid environment consists of shallow marine aeolian and alluvial facies which together form an aeolian beach ridge complex as a package of strata which respond simultaneously to sea level change a transgressive complex forms through reworking or overstepping of the coastal foredune and a regressive complex forms by downstepping under transgression the aeolian beach ridge represents the highstand deposit and its adjacent shallow marine sediment is the transgressive deposit under regression the complex represents the falling stage and the associated downdip surface marks the lowstand on the levant coast we find chronologically well constrained offlapping aeolian beach ridges as parts of six downstepping beach ridge complexes formed between 200 ka and 10 ka the complexes represent the falling stage systems tract fsst of a short lived 5th order depositional sequence when the shoreline shifted from a position close to the modern coastline to the shelf or below the shelf edge three of these fssts and their up dip and down dip super bounding surface together form the 4th order 100 ka sequence of the last interglacial glacial cycle the absence of transgressive highstand and lowstand systems tract is explained by the poor preservation potential due to the small sediment budget of the complex the falling stage complex has a high preservation potential because sediment source area increases while the sand drift potential remains above the local threshold on the levant coast sand delivery to the backshore continued during relative sea level falls for distances of up to 10 km between dune and coastline which is unprecedented in most modern analogues the significance of the dune soil succession for climate is limited because the dunes are governed by relative sea level change the vegetation response to changes in precipitation is non linear and the dune dynamics are characterised by low resilience and hysteresis

beach ridges definitions and significance abstract beach ridges frequent components of quaternary coastal plains and other coastal landforms have been cited as indicators of the positions of ancient seashores and associated sea levels numerous authors utilized the term beach ridge for active and relict usually wave built supratidal and or intertidal forms wind built ridges have been only occasionally included in the definition the term was applied also to submerged landward shifting eventually stranded bars a consistent redefinition of the term is highly desirable beach ridges should include all relict strandplain ridges whether dominated by wave swash built or by eolian lithosomes all active ridge like shore features regardless of dimensions morphology and origin are excluded because of the resistance of coarse clastic ridges to wave and wind erosion swash built gravel or coarse shell storm ridges may build several meters above the level of high tide swash built high berms even on pure sandy beaches exceed the highest tides during episodes of wind induced record water levels frequently but not always burying underlying low relief berm ridges of berm lithosomes sequences of relatively steep multiple foredunes are commonly named beach ridge plains the narrow subparallel relict foredunes that form these strandplains presently are designated as eolian beach ridges beach ridges thus are defined as relict semiparallel multiple wave and wind built landforms that originated in the inter and supratidal zones until separated from the shoreline by progradation sandy pebbly or shell enriched backshore berm ridges behind an active foreshore should not be considered beach ridges strandplain progradation is either continuous or with the inclusion of subtidal cat s eye ponds discontinuous contrary to claims transgressive cheniers do not represent true cheniers alone within their overall progradational context cheniers a special category of beach ridges bracketed by subtidal intertidal mudflats may be transgressive or regressive in character landward driven transgressive ridges should be designated beach ridges only after they are stabilized on intertidal flats when recognizable between clearly identifiable intertidal and overlying eolian intervals the horizontal interface between these lithosomes in beach ridges may help the reconstruction of ancient tide lake levels diagnostic sedimentary textures structures and fossils however often may be unavailable in the deposits along with various types of elevated terraces composed of raised marine deposits and certain coastal landforms of erosional origin that occur worldwide beach ridges of clearly proven wave built origin may also serve as indicators of ancient higher than present sea levels

morphological records of storm floods exemplified by the impact of the 1872 baltic storm on a sandy spit system in south eastern denmark beach ridge systems are important geo archives providing evidence for past wave climate including catastrophic storm flood events this study investigates the morphological impacts of the 1872 baltic storm flood on a beach ridge system sandy spit in south eastern denmark and evaluates the frequency of extreme storm flood events in the area over a longer time perspective this paper combines field studies of morphology and sedimentary deposits studies of historical maps digital terrain model ground penetrating radar profiles and luminescence dating sea water reached 2 8 m above mean sea level amsl during peak inundation and based on studies of the morphological impacts of the 1872 storm flood the event can be divided into four phases phase 1 increasing mean water levels and wave activity at the beach brought sediments from the beach intertidal bars and normal berm higher up in the profile and led to the formation of a storm berm phase 2 water levels further increased and sediment in the upper part of the profile continued to build up the storm berm phase 3 water levels now reached the top of the dune ridge and were well above the storm berm level sea water was breaching the dune ridge at several sites and wash over fans were generated until a level where the mean water level had dropped too much phase 4 the non vegetated wash over fans functioned as pathways for aeolian sand transport and relatively high dunes were formed in particular along the margins of the fan where aeolian sand was trapped by existing vegetation the studied beach ridge system records about 4500 years of accumulation the storm flood sediments described are unique suggesting that the 1872 baltic storm flood event was an extreme event thus studies of beach ridge systems form a new source for understanding storm surge risk copyright 2013 john wiley sons ltd

luminescence dating of quaternary sediments recent advances duller geoffrey 2004 luminescence dating of quaternary sediments recent advances journal of quaternary science 19 2 pp 183 192 rae2008

sequence of facies at a holocene storm dominated regressive barrier at praia de leste southern brazil abstract along the coast at praia de leste southern brazil 25 41 s latitude a positive sedimentary budget and a lowering of the sea level following the postglacial maximum has given rise to a progradational strandplain barrier that is 3 5 km wide sand quarries that lie 3 5 km from the present day coastline have provided material from exceptional outcrops of 75 of the sequence of holocene barrier facies five facies associations have been identified which correspond to the inner shelf the lower middle and upper shorefaces and the foreshore the architecture of the facies shows a regressive sequence that overlies an erosional surface and downlapping pleistocene sediments at praia de leste the facies association has a thickness of 14 m and is deposited between 2 m above and 12 m below mean paleo sea level the barrier corresponds to a coastal environment that is characterised by medium to low wave energy under the additional influence of episodic storm events the sequence at the praia de leste barrier differs from the sequence of clastic shoreline facies found elsewhere in two main ways the first difference is the high content of fine sediment and plant debris released at around the same time as the formation of the barrier from large estuarine systems and the second is the predominance on the middle and lower shorefaces of swaley cross stratified sand facies with abundant plant debris we also describe two further characteristics of the barrier at praia de leste first the swaley cross stratified sand represents a component of onshore transport that resulted in the accumulation of sediment transported from the shelf second the beach step has been well preserved thereby allowing the continuous tracing of seaward dipping low angle cross stratification to a sigmoidal cross stratified beach step sandy facies finally we have herein been able to improve the precision of the sequence of formation of the depth of the facies by making reference to paleo sea level during the formation of the barrier rather than to present day mean sea level

the evolution of an asymmetric deltaic lobe sf gheorghe danube in association with cyclic development of the river mouth bar long term pattern and present adaptations to human induced sediment depletion abstract the asymmetric sf gheorghe lobe is the only active lobe in the danube delta associated with a river mouth bar and related barrier islands and spits that has continuously displayed cyclic development during the last 1500 years during the early cycles the sf gheorghe distributary experienced a significant increase in sediment load by an order of magnitude as a result of the successive avulsions occurred 1 5 1 2 ka which redistributed more water and sediment captured from the neighboring branches of impu ita southern distributary of the sulina arm and dunav morphological and sedimentological analyses together with a newly obtained chronology throw light on the multiple ridgeset 10 structure of sf gheorghe lobe each of them excepting the first one following a common evolutionary pattern reflected by the cyclic succession of the recurring stages i subaqueous mouth bar building ii barrier island emergence and iii transformation into a barrier spit with several secondary spits the spits become encased into the muddy deltaic plain as narrow sandy ridges building out on the downdrift side of the lobe as a barrier marsh plain whereas the updrift side constantly accreted fed by longshore currents forming a classic beach ridge plain the size of each ridgeset increased exponentially with every new cycle due to the constant lengthening of the coastline as the downdrift side of the lobe advanced seaward through a series of progressively larger similar quadrilaterals yielding a corresponding geometric progression of the delta front size even though each newly formed ridgeset cycle had a longer lifespan the latest cycles lasting 4 5 times longer than the first ones 200 440 years versus 50 80 years the evolutionary model remained unchanged as long as the balance between wave and river borne sediments defined by the sedimentary index si remained constantly low si 0 1 whereas the mean advance rates of the river mouth remained constant at c 10 m year abrupt changes occurred within the last cycle since the beginning of the 20th century as a consequence of human induced depletion of sediment supplied by the danube flow and is mainly expressed by the complete cessation of the updrift coastal progradation and the prevalence of erosion in front of the river mouth these changes which engendered a threefold increase of the si 0 37 at present are reflected by the recent 1930s present river mouth dynamics characterized by cessation of its long term seaward expansion in favor of downdrift migration this is indicative of the transition of the sf gheorghe mouth from an asymmetric to a deflected wave influenced delta morphology whose current developments mark a significant change in the multicentennial cyclic evolutionary pattern the asymmetric to deflected transition reflects the net increase in the influence of wave driven sediment circulation on river mouth morphology corresponding to a critical si threshold of ca 0 2 0 2 asymmetric 0 2 deflected