fluctuations of caspian sea level beyond climatic variations the continued rising mode since about 1978 in the level of the caspian sea cannot be ascribed to a change in the hydrologic balance that is governed solely by runoff precipitation and evaporation such a change fails to explain some of the chemical links k cl rb cl ca cl sr cl and k rb between kara bogaz and caspian sea waters a more realistic model must include a tectono hydrodynamic factor that allows for subsurface addition of saline water to caspian sea and kara bogaz waters the subsurface water component could be akin to the coastal thermal springs in the area but must dissolve some evaporite deposits in the subsurface before addition to the waters of the inland sea a budget calculation gives an estimate of 2 to 9 subterranean addition of saline water to the seawater such an addition could cause a rise in the level of the caspian sea from 63 to as much as 225 cm within the past 20 yr

reconstructions of deltaic environments from holocene palynological records in the volga delta northern caspian sea new palynological and ostracod data are presented from the holocene volga delta obtained from short cores and surface samples collected in the damchik region near astrakhan russian federation in the northern caspian sea four phases of delta deposition are recognized and constrained by accelerated mass spectrometry ams radiocarbon ages palynological records show that erosive channels dunes baer hills and inter dune lakes were present during the period 11 500 8900 cal bp at the time of the mangyshlak caspian lowstand the period 8900 3770 cal bp was characterized regionally by extensive steppe vegetation with forest present at times with warmer more humid climates and with halophytic and xerophytic vegetation present at times of drought the period 3770 2080 cal bp was a time of active delta deposition with forest or woodland close to the delta indicating relatively warm and humid climates and variable caspian sea levels from 2080 cal bp to the present day aquatic pollen is frequent in highstand intervals and herbaceous pollen and fungal hyphae frequent in lowstand intervals soils and incised valley sediments are associated with the regional derbent regression and may be time equivalent with the medieval warm period fungal spores are an indicator of erosional or aeolian processes whereas fungal hyphae are associated with soil formation freshwater algae ostracods and dinocysts indicate mainly freshwater conditions during the holocene with minor brackish influences dinocysts present include spiniferites cruciformis caspidinium rugosum impagidinium caspienense and pterocysta cruciformis the latter a new record for the caspian sea the holocene volga delta is a partial analogue for the much larger oil and gas bearing mio pliocene palaeo volga delta

the caspian lake history biota structure and function the elongate endorheic caspian lake has a north south orientation and its main freshwater inflow the volga river enters at the shallow north end two deep basins occupy its central and southern regions these facts lead to horizontal differences in temperature salinity and ecology nutrient levels and primary production are low historically lake level has fluctuated by 6 m but on the geological timescale fluctuations of 200 m have occurred the lake formed in the late miocene first went through a long shrinking phase expanded to three times its present size in the late pliocene and repeatedly rose and fell throughout the pleistocene with corresponding freshenings and salinizations the lake surface has remained below sea level since the last pleniglacial this dynamic history led to the assemblage of a set of euryhaline biota of tethyan and freshwater origin besides baltic elements that invaded with glacial meltwater endemism is as high as in lake baikal but typical marine groups are absent because the lake is oxygenated to the bottom its biota show a vertical zonation but without a true abyssal community suggesting cat o pollution of the volga ural and kura rivers and destruction of the spawning grounds of sturgeon signalling a forthcoming collapse of the world caviar market dumont 1995 the caspian is the endorheic terminus of the volga river which contributes 80 of its total inflow 237 km3 yr on average butorin 1979 with a range of 200 450 km3 the kura river is second in line and discharges only 16 8 km yr i the ural river is third with a discharge of 8 1 km yr i lake surface area situated below sea level is close to 400 000 km2 and lake volume is 78 000 km3 or 40 of the world s continental surface water here i attempt to provide insight into the nature of the caspian ecosystem including its eventful past i outline gaps in our knowledge and suggest research for the future

worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

late pleistocene to holocene evolution of the emba delta kazakhstan and coastline of the north eastern caspian sea sediment ostracods pollen and dinoflagellate cyst records six cores each approximately 10 m long of late pleistocene to holocene age were studied from the emba delta region in the north eastern caspian sea radiocarbon dates provide ages within the range of 47 820 to 12 020 cal bp for the middle sections and for post 1950 close to surface the ages fall within marine isotope stage mis 3 mis 2 and mis 1 with mis 4 also inferred four lithological units are present each separated by an erosional contact unit 4 is equated with mis 4 and consists of over consolidated east west trending aeolian sands deposited during the late pleistocene atelian lowstand unit 3 is equated with mis 3 and is a low energy shallow open water or lagoonal deposit based on ostracod faunas pollen from mesophilic trees is common confirming warm climatic conditions floristic elements such as engelhardia and carya were shared with east asia frequent taxodiaceae pollen occurs derived from glyptostrobus pensilis a seasonal freshwater swamp tree now found naturally only in isolated relict stands in east asia this suggests that the north eastern caspian region was a refugium supporting glyptostrobus swamp vegetation during mis 3 there is no evidence to indicate that these are reworked occurrences unit 2 consists of early khvalynian transgressive barrier sands and unit 1 of shoreface sands and muds of holocene age the late khvalynian highstand and the last glacial maximum lgm record are eroded by the mangyshlak unconformity after ca 12 500 cal bp the holocene interval contains frequent foraminifera and dinoflagellate cysts dinocysts of restricted marine affinity e g lingulodinium machaerophorum the dinocysts pterocysta cruciformis and impagidinium inaequalis are found commonly in the caspian sea for the first time results are compared with palynological and ostracod assemblages in surface samples from the eastern caspian sea coastal region

morphodynamic evolution self organisation and instability of coarse clastic barriers on paraglacial coasts abstract beaches and barriers on many mid to high latitude coasts comprise mixtures of fine and coarse clastic materials forming a distinctive morphodynamic environment in many cases the sediments are derived primarily from limited glacigenic deposits and the coasts are considered paraglacial over relatively long time scales decades to centuries coarse clastic barriers on such coasts show evidence of self organisation through large scale morphological evolution and facies differentiation this process involves gradual reworking partitioning and textural sorting of material toward transport minima long intervals of slow evolution are punctuated by episodes of rapid reorganisation involving breakdown of stable barrier structures and facies patterns remixing of sediment and accelerated migration of transgressive systems drift aligned systems develop longshore cell structure sometimes leading to breaching and segmentation and may evolve toward progressively greater swash alignment under appropriate circumstances swash aligned systems may experience catastrophic transformation when appropriate environmental triggers lead to threshold exceedance in the morphodynamics of the shore system adjacent barriers may show quite different behaviour depending on the antecedent states of individual coastal cells while appropriate parameterisations and sediment budget formulations allow us to model the long term evolution of some barrier structures the non linear dynamics that appear to dominate large scale behaviour may limit predictability the identification of stability threshold criteria remains an important research priority

caspian sea level from topex poseidon altimetry level now falling tide gauge measurements recorded between 1978 and 1993 indicate that the caspian sea level csl has been rising at an average rate of 12 cm yr during this 15 yr time span decadal csl changes are currently attributed to changes in river runoff and effective evaporation we have analysed three and a half years from january 1993 through august 1996 of altimeter range data from the topex poseidon mission over the caspian sea to estimate temporal variations in the sea level we show that the caspian sea level was still rising at a rate of 18 9 0 5 cm yr between january 1993 and july 1995 and that the northwestern caspian in the area of the volga delta was rising faster by 3 cm yr than the middle and south caspian however by mid 1995 the csl started to drop abruptly a trend still observed in 1996 the average sea level decrease recorded from mid 1995 amounts to 24 8 1 4 cm yr

sediment transport in the yellow sea and east china sea abstract eight survey cruises in different seasons have been conducted in the yellow sea ys and east china sea ecs during the period from 2000 to 2008 suspended sediment concentration ssc and hydrological data were collected during each cruise data analysis showed that total suspended sediment mass was approximately 0 18 109 tons in the surveyed area during spring and autumn seasons highly turbid waters were found in the shallow waters between the subei coast the changjiang estuary and the zhejiang coast with seasonal variations the investigation provided convincing evidence that suspended sediments were transported from the subei coast and the southern entrance of the yellow sea trough to the central ys muddy patches were found at the sea bed when tidal currents were too weak to erode the bottom sediments and water column stratification and eddies provided favorable conditions for trapping the fine grained suspended sediments the investigation indicated that the different front may have different effect on sediment transport during different seasons the front between the yellow sea cold water and the coastal water in the subei coast appeared to trap the high ssc sediments on the shallow water side of the front during summer the front along the zhejiang coast seemed to prevent suspended sediments from transport across the front due to circulation in the front zone and upwelling along the zhejiang coast during winter sediments were likely transported across the front to the central continental shelf of the ecs with the help of the downwelling and lateral ekman transport driven by monsoon winds

modulation of the semidiurnal cycle of turbulent dissipation by wind driven upwelling in a coastal embayment with two 25 hour series of turbulent microstructure and currents observations carried out in august 2013 during spring chaos 1 and neap tides chaos 2 we investigated the semidiurnal cycle of turbulent dissipation in an embayment affected by coastal upwelling ria de vigo nw iberia at the time of sampling the bay hosted a net wind driven bi directional positive exchange flow and thermal stratification turbulent kinetic energy tke dissipation e at the interface between upwelled and surface waters was enhanced by two orders of magnitude during the ebbs 10 6 w kg 1 with respect to the floods 10 8 w kg 1 this pattern was caused by the constructive interference of the shear associated with the upwelling and tidal currents the vertical structure of the tidal currents was consistent with a deformation of tidal ellipses by stratification which was tightly coupled to the intensity of upwelling this two pronged interaction resulted in a modulation of the semidiurnal cycle of turbulent dissipation by coastal upwelling thus as a result of the upwelling relaxation conditions experienced during chaos 1 depth integrated interior tke dissipation rates were higher by a factor of 2 compared to chaos 2 by using a simple model we determined that observed variations in turbulent mixing had a limited influence on the tidal variations of stratification which were dominated by straining and advection the mixing mechanism described here is potentially relevant for the ecology of upwelling bays as it can stimulate the transport of nutrients from deep upwelled waters to the sun lit surface layers where primary production takes place

late highstand patterns of shifting and stepping coastal barriers and washover fans late messinian sorbas basin se spain abstract the late messinian sorbas member up to 75 m thick consists in its type area of a parasequence set of three prograding coastal barriers sequences i iii associated with lagoon and washover sediments around the town of sorbas these strata can be studied exceptionally well due to absence of burrowing by raised messinian salinities and exposure along a network of up to 30 m deep canyons fifteen vertical sections were logged and carefully correlated this permits to reconstruct and discuss patterns of relative sea level movements between decimetres up to 15 m within a parasequence excellent examples of non tidal transgressive facies are characterized by lagoon and washover sediments instead of the usual combination of washover and tidal deposits channel and flood tidal delta implications for the sandstone connectivity are given the lower two sequences are deposited in a relatively large tectonically enhanced wedge shaped accommodation space they show both fining up deepening sequences followed by prograding coarsening up shoaling sequences and can be compared to the classical parasequences of the western interior basin usa progradation of sequence ii was interrupted by a major slide event most likely triggered by an earthquake which caused more than 400 m seaward slumping of a stretch of 1 km of coastal sands the architecture of sequence iii is more complex due to limited accommodation space characteristic for the late highstand so that this setting was very sensitive to sea level fluctuations this resulted in an intricate pattern of juxtaposed and superposed lagoonal muds washover fans and swash zones so called stranded coastal barriers occur which were left behind after seaward jump of the coastline over more than 1 5 km during forced regression the pattern of reconstructed sea level positions is well comparable to the sequential pattern shown by the correlated equivalents along the northern basin margin which belong to the so called terminal carbonate complex the problem of ranking the complex sequence iii as one or more parasequences and its consequences for cyclostratigraphy are shortly discussed two models of washover formation are given respectively during more rapid and more slow sea level rise the influence of synsedimentary folding on the location of barriers is discussed and also the source area of extra and intraclasts supplied to barriers and washovers after deposition of the sorbas member the sea withdrew from the sorbas basin probably as a result of the major downdrop in the mediterranean at the maximum isolation during the salinity crisis it is suggested that the semi enclosed setting of the basin resulted only in limited localized erosion in contrast to the deeper adjacent vera basin which was more open to the mediterranean

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

holocene oscillations of the caspian sea and forecasts based on palaeogeographical reconstructions abstract investigation of deltas and terraces adjacent to the caspian sea has indicated the pattern of holocene fluctuations in level since the initiation of the earliest holocene transgression the surface of the caspian sea has varied between 20 and 32 m below modern sea level six transgressive episodes are recognized in the holocene record separated by regressive episodes when the level fell below 28 m a s l the modal holocene level of the caspian sea is estimated at 28 2 m a s l beginning in 1929 water levels fell rapidly in the caspian sea reaching 29 m a s l the lowest value in 400 years in 1977 however the water level began to rise a trend which has continued to the present currently the caspian sea surface stands at approximately 27 m a s l throughout the past 2500 years the level has not exceeded 25 m a s l and it is not anticipated to exceed this value in the near future the fluctuations recorded since 1929 fall within the range of variations expected from natural environmental factors which have operated since the early holocene

a numerical investigation of circulation in the arabian gulf a three dimensional hydrodynamic model is developed to study the circulation in the arabian gulf the model contains realistic basin geometries and bathymetries of the arabian gulf and a good portion of the gulf of oman and is driven by monthly climatological winds evaporation and net ocean heat gain in both gulfs and the shatt al arab discharge it is found that the cyclonic circulation in the southern portion of the gulf is primarily driven by the evaporation induced freshening from the strait of hormuz in the northwestern corner of the gulf the shatt al arab discharge maintains the cyclonic circulation which would otherwise be anticyclonic the northwestward intrusion of fresher water along the iranian coast is weakened by northwesterly winds in winter but strengthens and extends almost to the head of the gulf in summer owing to the warming of the gulf of oman waters the development of the summer thermocline in the arabian gulf and diminishing winds the southward coastal current along the arabian coast is most prominent between the head of the gulf and qatar the model also predicts a strong southward coastal jet east of qatar which is primarily wind driven no similar coastal jet can be developed in the gulf of salwa west of qatar

small scale stratigraphy in a large ramp delta recent and holocene sedimentation in the volga delta caspian sea the volga delta differs from all other major deltas in the world by its extremely gentle onshore and offshore gradient f5 cm km and by being affected by the rapid sea level changes of the caspian sea at rates up to a hundred times the global sealevel rise this paper reports 1 the morphological and facies development of part of the lower delta during the last full sealevel cycle between 1929 and 1995 as monitored using remote sensing and field mapping and 2 the holocene development of the delta from outcrop data and augered transects during a sea level fall of 3 m between 1929 and 1977 rapid progradation of levees composed of fine sand took place along over 800 distributary channels along the delta front smaller distributaries became filled with clay and organics during the 3 m sea level rise from 1977 to 1995 aggradation occurred leading to deposition of silt and clay on the levees and minor filling of the flood basins sedimentation rates as established with 137 cs dating are up to 2 5 cm year total thickness of holocene deposits in the lower delta plain is 4 10 m

recent coastal evolution of the caspian sea as a natural model for coastal responses to the possible acceleration of global sea level rise abstract the caspian sea serves as an excellent natural laboratory for studies of coastal response patterns as it is highly variable in its water level over decadal and secular time scales coastal morphology presumably nearshore bottom slope and profiles of depositional coastal bodies or erosional scarps as well as rates and amplitudes of water level changes appear to be the most important factors of coastal response rates and patterns nearshore bottom slope determines not only shoreline retreat values according to the bruun rule but also the very patterns of coastal evolution for various morphological types of depositional coasts including deltaic coasts strict analytical prediction of coastal response to the accelerated sea level rise is yet to be solved analysis of every response pattern of depositional coasts to sea level changes requires a specific modification of the bruun rule however these equations should be regarded only as the means to estimate an order of magnitude of shoreline retreat or advance in many cases equations based on the bruun rule cannot be applied at all boundary conditions for each quantitative model should be thoroughly studied where possible longshore sediment drift sediment washover on to the landward slope of depositional coastal features and possible onshore or offshore aeolian sediment movement should be taken into account moreover applicability of the bruun rule based equilibrium approach will possibly diminish under the possible future acceleration of sea level rise

general spectral computations of the nonlinear shallow water tidal interactions within the bight of abaco abstract an iterative frequency time domain finite element tidal circulation model is applied to the bight of abaco in the bahamas to study the nonlinear interactions that occur between the various astronomical overtide and compound tide constituents the nonlinear origin of the significant shallow water constituents is determined by suppressing the various nonlinear terms in the shallow water equations furthermore the extend to which nonlinear constituents interact with and effect each other is studied in detail by suppressing the interaction of selected tides within the framework of the interative frequency time domain formulation it is found that second nonlinear interaction between the astronomical tides and the shallow water tides themselves can significantly affect overtide compound tides and even tides some important examples include i the m2 interaction with m6 which generates the m8 tide ii the significant reductions in m6 m8 and m10 responses respectively by 12 15 and 25 due to

sefidrud delta and quaternary evolution of the southern caspian lowland iran abstract the southern caspian sea lowland in iran forms a thick sedimentary prism produced by interactions of marine deltaic and fluvial processes during the late neogene and quaternary deltaic and fluvial deposits have been developed mainly by the sefidrud which is the largest river of the country its drainage area ca 61 600 km 2 includes nearly the entire alborz mountain range and forms deep valleys gorges and a large delta at the southern coast of the caspian sea the sefidrud delta is so large that it covers one third of the large guilan mazanderan plain both from an aerial and volumetric point of view consequently the drainage network of the sefidrud represents the quaternary evolution of northern iran and can be used to test the hypothesized evolution of the region the sefidrud delta has been investigated using many short and long cores satellite images and lithofacies maps and the results show that this delta complex 1680 km 3 consists of a covered lower part and exposed upper deltaic sequences the lower and upper parts of the complex were formed during the early pleistocene and late pleistocene respectively the upper exposed alluvial and deltaic sediments represent a total progradation of approximately 50 km forming three separate delta subsequences d1 3 of which the last one d3 is the modern sefidrud delta the modern delta is a wave dominated blanket like sediment cover ca 30 m thick and 1550 km 2 produced during the last three millennia it was formed by 30 km progradation of six juxtaposed lobes each lobe corresponds to a long term sea level fluctuation of the caspian sea the active lobe ca 50 km 2 has been forming since 1550 ad late pleistocene deltaic sequences d1 3 particularly the modern one d3 were produced by relatively fast deposition due to high volume sediment load of the sefidrud it is suggested that they were produced after the opening of the rudbar gorge by river capture that in turn six times enlarged the drainage area previous deltaic progradation and marine transgressions were relatively slow and the development of the whole lowland at the southern caspian sea lasted ca 1 1 2 ma bp

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

a modeling study of circulation and eddies in the persian gulf abstract the circulation and mesoscale eddies in the persian gulf are investigated using results from a high resolution 1 km hybrid coordinate ocean model hycom the circulation in the persian gulf is composed of two spatial scales basin scale and mesoscale the progression of a cyclonic circulation cell dominates the basin scale circulation in the eastern half of the gulf 52 55 e during march july this is primarily the consequence of density driven outflow inflow through the strait of hormuz and strong stratification a northwestward flowing iranian coastal current icc 30 40 cm s 1 between the strait of hormuz and north of qatar 52 e forms the northern flank of the cell between july and august the icc becomes unstable because of the baroclinic instability mechanism by releasing the potential energy stored in the cross shelf density gradient as a result the meanders in the icc evolve into a series of mesoscale eddies which is denoted as the iranian coastal eddies ice the ice have a

deep volcanic tremor and magma ascent mechanism under kilauea hawaii deep harmonic tremor originating at depths around 40 km under kilauea was studied using records accumulated since 1962 at the hawaii volcano observatory of the u s geological survey the deep source of the tremor was determined by onset times and confirmed by the relative amplitude across the island wide network of seismometers the period of tremor was conclusively shown to be determined by the source effect and not by the path or station site effect because the period would change considerably in time but maintained uniformity across the seismic net during the tremor episode the tremor appeared to be primarily composed of p waves we interpret the observed period and amplitude in terms of the stationary crack model of aki et al 1977 and find that the seismic moment rates for deep tremors are considerably larger than those for shallow tremors suggesting more vigorous transport for the former we propose a kinematic source model which may be more appropriate for deep tremor according to this model a measurable quantity called reduced displacement is directly proportional to the rate of magma flow a systematic search for deep tremor episodes was made for the period from 1962 through 1979 and the amplitude period and duration of the tremor were tabulated we then constructed a cumulative reduced displacement plot over the 18 year period the result shows a generally steady process which does not seem to be significantly affected by major eruptions and large earthquakes near the surface the total magma flow estimated from the reduced displacement is however one order of magnitude smaller than that estimated by swanson 1972 it may be that most channels transport magma aseismically and only those with strong barriers generate tremor

solar forced 2600 bp and little ice age highstands of the caspian sea abstract the level of the caspian sea the largest inland sea in the world has fluctuated capriciously in history with amplitudes up to 3 m in the last century to 25 m in the last millennium and to over 150 m since the last glacial there is little consensus about the causes and forecasts are contradictory mainly due to a lack of solid data about past sea levels before 1837 ad when instrumental observation started we studied the holocene turali barrier complex along the western caspian shore in dagestan russia barrier dynamics during the last 3 m sea level cycle in the past century show that only lagoonal deposits overridden by highstand barriers are suitable for dating former highstands in the holocene barrier complex we selected the most suitable sites for dating using ground penetrating radar gpr profiles outcrops and gravel pits we obtained 14 accelerator mass spectrometry ams 14c data on in situ double valved molluscs from highstand lagoonal deposits the results suggest that the last major highstands occurred around 2600 bp and in the little ice age and coincide with global cooling events associated with minima in solar activity this suggests that millennial precipitation changes in the volga river drainage basin are also forced by solar activity

late pleistocene and holocene sea level change and coastal paleoenvironment evolution along the iranian caspian shore the authors published by elsevier b v this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 4 0

pleistocene climatic stratigraphy and environments of the terek kuma lowland nw caspian sea region inferred from palynological paleomagnetic and rodent records of the long otkaznoye sediment sequence abstract the paper presents the results of a high resolution palynological paleomagnetic and microtheriological study of the pleistocene sediment sequence at otkaznoye in the eastern ciscaucasian foreland a sequence which is unique in its stratigraphic completeness and thickness 160 m the sequence includes loess paleosol alluvial and alluvial proluvial beds the detailed climatostratigraphic subdivision of the otkaznoye sequence allows a correlation of the established paleoclimatic record with the global marine isotope stages the past climatically induced variability in the landscape of the terek kuma lowland is reconstructed for all neopleistocene i e middle and late pleistocene interglacial and glacial periods and for some intervals during the later early pleistocene stages

development of the kura delta azerbaijan a record of holocene caspian sea level changes late holocene deposits of the kura delta indicate an alternating dominance of deltaic and shallow marine environments these major environment shifts are controlled by the high frequency sea level changes of the caspian sea the level of the caspian sea now at 27 m below global sea level gsl changes at rates of up to a hundred times as fast as global sea level allowing observation of sedimentary processes on a decadal scale that would take millennia in an oceanic environment the modern kura delta is a river dominated delta with some wave action along its north eastern flank and without tidal influence morphological and hydrological changes have been monitored for over 150 years continuing up to the present day using remote sensing imagery offshore sparker survey data onshore and offshore corings biostratigraphical analysis and radiometric dating enable a reconstruction of the holocene kura delta four phases of delta progradation alternating with erosional transgressive surfaces have been identified representing just as many cycles of sea level fall and rise the first cycle is represented by lowstand deposits truncated by a transgressive surface ts1 at ca 80 m below gsl ts1 is overlain by several metres of laminated clays and silts deposited during a late holocene forced regression h1 these deposits are truncated by the prominent reflector ts2 corresponding to the derbent lowstand around 1500 yr bp and subsequent transgression this transgressive surface is overlain by prograding shallowing upwards deposits h2 in turn truncated by a third transgressive surface ts3 correlated with a lowstand of ca 32 m below gsl the last phase h3 comprises an onshore progradational unit followed by an aggradational unit with an offshore veneer of clays and silts corresponding to the formation of the modern kura delta that started at the beginning of the 19th century

a full sea level cycle in 65 years barrier dynamics along caspian shores abstract the caspian sea being a closed basin shows much higher rates of sea level change up to 340 mm yr than the oceans it experienced a full sea level cycle with an amplitude of 3 m between 1929 and 1995 its coasts therefore present an attractive physical model to test predicted changes along oceanic coasts as a result of expected eustatic sea level rise and to validate sequence stratigraphical interpretations of ancient sediments along the wave dominated coasts with intermediate shore face slopes in dagestan low onshore bars were formed during the 1929 1977 sea level fall they represent minor short lived 1 2 years transgressive oscillations within the major regressional trend after the 1977 lowstand a prominent barrier lagoon system was formed which during the first phase of sea level rise 1977 1988 encroached landwards about 18 m each year by washover during storms continuous retreat between 1988 and 1995 however barrier size diminished lagoons widened and deepened apparently due to lack of coarse grained sediment supply discontinuous retreat the 1995 highstand prevented the barriers from being overstepped altogether sea level fall after 1995 again produced low bars without lagoons the caspian sea barrier coast demonstrates that for the formation of barrier lagoon complexes the combination of transgression and storms is essential barriers may show either continuous or discontinuous development at constant rate of sea level rise and constant offshore slope depending essentially on the availability of coarse grained sediments the rate of sea level rise as a factor in barrier behaviour cannot be viewed independently from barrier dimensions which in turn depend on wave base depth and maximum storm wave height relations between para sequence thickness and frequency and amplitude of sea level change in closed basins with an independent sea level regime may differ markedly from those in basins influenced by eustasy

natural and anthropogenic influences on depositional architecture of the ural delta kazakhstan northern caspian sea during the past 70 years abstract this paper focuses on the ural delta in the northern zone of the caspian sea an area with particular characteristics where intense influence from anthropogenic and natural factors exists which acts on the fragile delta system we built a database to integrate the data from the published sources bathymetric survey and recent images in the geographical information system gis environment the results were linked to the caspian sea level csl curve which had many variations changing the ural delta system s dynamics and in its architecture in addition the anthropogenic changes contribute to shaping the actual ural delta architecture through the link between the results and csl we reconstructed an evolution model for the ural delta system for the last century and identified three different architectures for the ural delta determined by the energy that acted on the system in the last century and by the anthropogenic changes this work identifies six different delta phases which are shaped by csl changes during the last 70 years and by anthropogenic changes the delta phases recognized are i a lobate delta phase shaped during high csl before 1935 ii natural elongate delta 1935 1950 formed during rapid csl fall iii anthropogenic elongate delta 1950 1966 formed during rapid csl fall and after the ural caspian sea canal construction which modified the sedimentary deposition on the delta iv anthropogenic elongate delta 1966 1982 shaped during low csl phase v anthropogenic elongate delta 1982 1996 formed during a rapid csl rise phase and vi anthropogenic elongate delta 1996 2009 shaped during high csl that represent the last phase and actual ural delta architecture

hydrology and circulation in the strait of hormuz and the gulf of oman results from the gogp99 experiment 1 strait of hormuz in october and early november 1999 the gogp99 experiment collected hydrological currentmeter tide recorder thermistor and drifting buoy data near the strait of hormuz data analysis provides the water mass structure in the strait persian gulf water pgw core is banked against the omani coast while indian ocean surface water iosw lies near the iranian coast these water masses are most often covered by a homogeneous surface layer thermohaline characteristics of the pgw core decrease substantially downstream from the persian arabian gulf to the gulf of oman pgw and iosw thermohaline characteristics and distribution also exhibit notable changes at periods shorter than a month as shown by repeated hydrological sections the tidal signal measured south of the strait by moored adcp and thermistor chains has predominant semi diurnal m2 and s2 and diurnal k1 components and possesses a complex vertical structure tidal intensification near the surface pycnocline is associated with noticeable internal waves at subtidal timescale mooring recordings confirm the water mass variability observed in the repeated hydrological sections the mixed layer also deepens substantially during the 1 month period finally trajectories of surface buoys drogued at 15 m exhibit reversals over periods characteristic of changes in wind direction

tidal spectroscopy of the english channel with a numerical model abstract the possibility of reproducing the complexity of tides in shallow water areas with a classical finite difference numerical model is examined this hydrodynamic model is two dimensional but incorporates topography nonlinear advection and quadratic bottom friction particular care is taken to prescribe sea surface elevations at the open boundaries a one month simulation of real tides is run with a simplified spectrum restricted to only 24 constituents corresponding to the nine main astronomical tides and their nonlinear significant interactions the results are analyzed by spectral decomposition elevations and vertically integrated currents and compared with observational data from the tide gages and current meters and with other solutions produced in the literature it is found that the dominant m2 constituent greatly influences the damping of the other constituents so that it is necessary to run them together for any correct simulation however the quadratic friction law introduced in

sensitivity of tidal bed stress distributions near bed currents overtides and tidal residuals to frictional effects in the eastern irish sea abstract a three dimensional nonlinear high resolution hydrodynamic model of the eastern irish sea is used to examine the influence of near bed viscosity and bottom friction upon the m2 tide and overrides in the region initially bed stress in the model is related to the depth mean current the formulation used in a classic two dimensional model the resulting hybrid two dimensional three dimensional model enables changes in current profile due to variations in eddy viscosity to he examined independently of those due to changes in bed stress also results from the model are compared with those from a three dimensional model with bed stress related to bottom current computed tidal elevations and surface currents are found to be fairly insensitive to the parameterization of bottom stress however tidal current profiles in the near bed region and maximum bed stress are found to be sensitive to variations in near bed viscosity and friction coefficient although reducing eddy viscosity in the near bed

tide induced residual current in a coastal lagoon of the gulf of california abstract the non linear tidal interactions in the narrow shallow coastal lagoon yavaros bay are investigated using a vertically integrated two dimensional numerical model the model sea surface elevations and currents are validated by comparison of computed tidal harmonics against those derived from harmonic analysis of the sea surface and current time series calculations show that tides become mixed mainly semidiurnal in the lagoon mk3 ms4 and m4 generated by advection and non linear continuity are the most energetic shallow water constituents a large half basin clockwise eddy was found whose source of energy is the m2 tidal energy flux the size of the shoal where the eddy occurs is almost the same as the maximum tidal excursion length 3 km

cooling magma model for deep volcanic long period earthquakes deep long period events dlp events or deep low frequency earthquakes deep lfes are deep earthquakes that radiate low frequency seismic waves while tectonic deep lfes on plate boundaries are thought to be slip events there have only been a limited number of studies on the physical mechanism of volcanic dlp events around the moho crust mantle boundary beneath volcanoes one reasonable mechanism capable of producing their initial fractures is the effect of thermal stresses since ascending magma diapirs tend to stagnate near the moho where the vertical gradient of density is high we suggest that cooling magma may play an important role in volcanic dlp event occurrence assuming an initial thermal perturbation of 400 c within a tabular magma of half width 41 m or a cylindrical magma of 74 m radius thermal strain rates within the intruded magma are higher than tectonic strain rates of 10 14 s 1 and produce a total strain of 2 10 4 shear brittle fractures generated by the thermal strains can produce a compensated linear vector dipole mechanism as observed and potentially also explain the harmonic seismic waveforms from an excited resonance in our model we predict correlation between the particular shape of the cluster and the orientation of focal mechanisms which is partly supported by observations of aso and ide 2014 to assess the generality of our cooling magma model as a cause for volcanic dlp events additional work on relocations and focal mechanisms is essential and would be important to understanding the physical processes causing volcanic dlp events

transgressive and regressive stratigraphies of coastal sand barriers in southeast australia abstract in recent years attempts have been made in southeast australia to document the stratigraphic characteristics of coastal sand barriers two basic arrangements of facies are distinguished those associated with transgressive depositional sequences and those associated with regressive sequences transgressive sequences either are formed during the postglacial marine transgression or are related to receding or transgressive barriers at present sea level in the former case complex interfingering of nearshore washover and lagoonal facies are evident in many areas these facies underlie those associated with regressive sequences which have formed since sea level has reached its present position ca 6000 6500 yrs ago examples of regressive sequences associated with both prograded and stationary barrier types occur in southeast australia here the thickness of nearshore facies in particular is commonly greater than equivalent units beneath barriers on coasts of lower energy and for less steep inner shelf gradients in the northern hemisphere the interplay of various factors within embayments has led to the development of several barrier types such as prograded stationary receded and episodic dune with some sedimentary characteristics in common with similar types recognized in other parts of the world e g texas delaware the netherlands barriers formed as a result of migrating spits and tidal inlets are not common in southeast australia

deposition and flux of sediment from the po river italy an idealized and wintertime numerical modeling study abstract recent studies of sediment dynamics and clinoform development in the northern adriatic sea focused on winter 2002 2003 and provided the data and motivation for development of a detailed sediment transport model for the area near the po river delta we used both idealized test cases and more realistic simulations to improve our understanding of seasonal sediment dynamics there we also investigated the relationship between physical processes and the observed depositional products e g the accumulation of sediment very near the po river distributary mouths sediment transport near the po river was evaluated using a three dimensional ocean model coupled to sediment transport calculations that included wave and current induced resuspension suspended sediment transport multiple grain classes and fluvial input from the po river high resolution estimates from available meteorological and wave models were used to specify wind wave and meteorological forcing model results indicated that more than half of the discharged sediment remained within 15 km of the po river distributary mouths even after two months of intensive reworking by winter storms during floods of the po river transport in the middle to upper water column dominated sediment fluxes otherwise sediment fluxes from the subaqueous portion of the delta were confined to the bottom few meters of the water column and correlated with increases in current speed and wave energy spatial and temporal variation in wind velocities determined depositional patterns and the directions of sediment transport northeasterly bora winds produced relatively more eastward transport while southwesterly sirocco winds generated fluxes towards both the north and the south eastward transport accounted for the majority of the sediment exported from the subaqueous delta most likely due to the frequent occurrence of bora conditions progradation of the po river delta into the adriatic sea may restrict the formation of the western adriatic coastal current increasing sediment retention at the po delta and reducing the supply of sediment to the apennine margin a positive morphodynamic feedback may therefore be present whereby the extension of the delta into the adriatic increases sediment accumulation at the delta and facilitates further progradation

numerical modelling of the tide induced residual current in the east china sea abstract a two dimensional nonlinear numerical model is used to study the residual current generated by tides in the east china sea ecs and the south huanghai sea shs first the principal semi diurnal lunar tide m and the tidal current are derived in these areas the results obtained with the model are strongly supported by observational results available then time induced residual flow is determined by using the currents generated by the tidal input the main features of the residual current in ecs and shs are presented by analyzing the calculated results some of the problems are discussed such as the cause of generating residual current and the contribution of the residual current to the observed current

implications of outcrop geology for reservoirs in the neogene productive series apsheron peninsula azerbaijan the neogene sediments of eastern azerbaijan and western turkmenistan contain significant hydrocarbon reserves in deltaic reservoirs sedimentary logging of these reservoirs at outcrop in azerbaijan has outlined four facies associations that encompass a range of paleoenvironments from alluvial braided river sandstones and conglomerates to delta front siltstones and mudstones the facies associations suggest a river dominated braid delta and are arranged into an architecture controlled by base level changes parasequences parasequence sets and sequence boundaries are key elements the facies associations and stratigraphic architecture together with outcrop observations of cementation and faulting are summarized in terms of four idealized reservoir models fluvial delta plain proximal delta front and distal delta front each reservoir model has distinctive grain size and shale distributions comparison of nearby oil fields with the studied outcrops suggests that the outcrops form good analogs from which to model reservoir architecture barriers and baffles to fluid flow reservoir heterogeneity and reservoir quality variations

modeling river delta formation a model to simulate the time evolution of river delta formation process is presented it is based on the continuity equation for water and sediment flow and a phenomenological sedimentation erosion law different delta types are reproduced by using different parameters and erosion rules the structures of the calculated patterns are analyzed in space and time and compared with real data patterns furthermore our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta the simulation results are then compared with geological records for the mississippi river

anthropogenic influence on recent evolution of shorelines between the conero mt and the tronto r mouth southern marche central italy abstract a study of the shoreline evolution during the last two centuries along the southern portion of the marche region between the promontory of the conero mountain and the tronto river mouth has been carried out on the basis of historical data and taking into account the effects of both natural events and anthropogenic interventions the research started with searching acquiring georeferencing and digitizing all the available maps surveyed from 1835 to the present the above data set has been used to implement a vector geodatabase containing the successive position and shape of shorelines with particular attention to the neighboring river mouths since transitional and beach deposits have been almost completely eroded during the last decades the adoption of traditional techniques of geomorphologic and sedimentological analyses has not been possible the results of the above analyses have been correlated with the main natural events and human interventions occurring during the considered time span the results of this comparison highlights that the evolution of river mouths and neighboring beaches mostly depends on deforestation carried out in their hydrographic basins in the study area the progradation of river mouths continued after the end of the little ice age ended around 1850 namely it has been observed that the retreat coincided with the start of reforestation and agricultural development in the 20 s of the last century during the following decades further interventions such as construction of dams and check dams extraction of sediments from thalwegs fillings modifications of stream paths abandonment of agricultural practices etc contributed to a severe reduction of river solid load with subsequent retreat of both river mouths and beaches thus making it necessary to protect them with artifacts

swarms of similar long period earthquakes in the mantle beneath mauna loa volcano abstract we present analyses of two swarms of long period lp earthquakes at 30 km depth that accompanied the geodetically observed 2002 2005 mauna loa intrusion the first lp earthquake swarm in 2002 consisted of 31 events that were precursory and preceded the start of mauna loa inflation the second lp swarm of two thousand events occurred from 2004 2005 the rate of lp earthquakes slowed significantly coincident with the occurrence of the december 26 2004 m w 9 3 sumatra earthquake suggesting that the seismic waves from this great earthquake may have had a dynamic triggering effect on the behavior of mauna loa s deep magma system using waveform cross correlation and double difference relocation we find that a large number of earthquakes in each swarm are weakly similar and can be classified into two families the relocated hypocenters for each family collapse to compact point source regions almost directly beneath the mauna loa intrusion we suggest that the observed waveform characteristics are compatible with each family being associated with the resonance of a single fluid filled vertical crack of fixed geometry with differences in waveforms between events being produced by slight variations in the trigger mechanism if these lp earthquakes are part of the primary magma system that fed the 2002 2005 intrusion as indicated by the spatial and temporal associations between mantle seismicity and surface deformation then our results raise the possibility that this magma system may be quite focused at these depths as opposed to being a diffuse network it is likely that only a few locations of mauna loa s deep magma system met the geometric and fluid dynamic conditions for generating lp earthquakes that were large enough to be recorded at the surface and that much of the deep magma transfer associated with the 2002 2005 intrusion occurred aseismically

anthropogenic effects on shoreface and shoreline changes input from a multi method analysis agadir bay morocco abstract in many situations the links between shoreline fluctuations and larger scale coastal change embracing the shoreface are not always well understood in particular meso scale years to decades sand exchanges between the shoreface and the shoreline considered as important on many wave dominated coasts are rather poorly understood and difficult to identify coastal systems where sediment transport is perturbed by engineering interventions on the shoreline and shoreface commonly provide fine examples liable to throw light on these links this is especially so where shoreface bathymetric datasets which are generally lacking are collected over time enabling more or less fine resolution of the meso scale coastal sediment budget agadir bay and the city of agadir together form one of the two most important economic development poles on the atlantic coast of morocco using a combined methodological approach based on wave current modelling bathymetric chart differencing determination of shoreline fluctuations and beach topographic surveying we highlight the close links between variations in the bed of the inner shoreface and the bay shoreline involving both cross shore and longshore sand transport pathways sediment budget variations and new sediment cell patterns we show that the significant changes that have affected the bay shoreline and shoreface since 1978 clearly reflect anthropogenic impacts notably blocking of alongshore sand transport by agadir harbour completed in 1988 and the foundations of which lie well beyond the depth of wave closure construction of the harbour has led to the creation of a rapidly accreting beach against an original portion of rocky shoreline updrift and to a net sand loss exceeding 145 000 m 3 year between 1978 and 2012 over 8 5 km 2 of the bay shoreface downdrift shoreline retreat has been further exacerbated by sand extraction from aeolian dunes and by flattening of these dunes to make space for tourist infrastructure digital elevation models of part of the bay beach between 2012 and 2014 confirm this on going sand loss these changes have involved the establishment of two divergent longshore bay sediment cells instead of the original single unidirectional cell a prospective view of these changes suggests that perturbation of longshore drift and the on going bay sediment budget deficit will eventual directly pose threats to the harbour access and to coastal tourism on which the economic growth of agadir has been built

dating modern deltas progress problems and prognostics 1 abstract radiocarbon dating is the method most frequently used to date holocene deltaic sequences but less than one quarter of 14c dates are within 500 years of predicted age such dates tend to be unreliable in other words often too old and commonly inverted upsection and core sample dates obtained near deltaic plain surfaces may be as old as mid to late holocene stratigraphic irregularities result primarily from downslope reworking of upland alluvial sediment with displacement of old carbon in the sediment that accumulates in lower valleys and deltaic plains use of dates that are too old results in inaccurately calculated rates most often too low of relative sea level rise and or land subsidence more reliable timing of deltaic sediment requires a multiple method dating approach including where possible identification of associated archaeological material developing an accurate dating strategy is a critical step for implementing reliable coastal protection measures needed for the rapi

effect of subseabed salt domes on tidal residual currents in the persian gulf geological studies in the persian gulf pg have revealed the existence of subseabed salt domes with suitable filtering of a high resolution pg seabed topography it is seen that the domes leave their signature in the seabed i e numerous hills and valleys with amplitudes of several tens of meters and radii from a few up to tens of kilometers it was suspected that the shark skin of the pg seabed may affect the tidal residual flow the interaction of tidal dynamics and these obstacles was investigated in a nonlinear hydrodynamic numerical tidal model of the pg the model was first used to characterize flow patterns of residual currents generated by a tidal wave passing over symmetric elongated and tilted obstacles thereafter it was applied to the entire pg the model was forced at its open boundary by the four dominant tidal constituents residing in the pg each tidal constituent was simulated separately results i e tidal residual currents in the pg as depicted by lagrangian trajectories reveal a stationary flow that is very rich in eddies each eddy can be identified with a topographic obstacle this confirms that the tidal residual flow field is strongly influenced by the nonlinear interaction of the tidal wave with the bottom relief which in turn is deformed by salt domes beneath the seabed different areas of maximum residual current velocities are identified for major tidal constituents the pattern of trajectories indicates the presence of two main cyclonic gyres and several adjacent gyres rotating in opposite directions and a strong coastal current in the northern pg

high precision relocation of long period events beneath the summit region of kilauea volcano hawai i from 1986 to 2009 long period 0 5 5 hz lp seismicity has been recorded for decades in the summit region of kilauea volcano hawai i and is postulated as linked with the magma transport and shallow hydrothermal systems to better characterize its spatiotemporal occurrence we perform a systematic analysis of 49 030 seismic events occurring in the kilauea summit region from january 1986 to march 2009 recorded by the 50 station hawaiian volcano observatory permanent network we estimate 215 437 p wave spectra considering all events on all stations and use a station averaged spectral metric to consistently classify lp and non lp seismicity we compute high precision relative relocations for 5327 lp events 43 of all classified lp events using waveform cross correlation and cluster analysis with 6 4 million event pairs combined with the source specific station term method the majority of intermediate depth 5 15 km lps collapse to a compact volume with remarkable source location stability over 23 years indicating a source process controlled by geological or conduit structure

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

the wandering of the volga delta a response to rapid caspian sea level change due to its very low gradient and absence of tide and surf the volga delta is an even more extreme example of the fluvially dominated type than the mississippi delta however it differs from all other large delta systems in that it borders a closed basin the caspian sea now at 26 m below global sea level caspian sea level is much more dynamic than that of the world oceans and rises at present about 1 5 cm yr a hundred time the eustatic rate within the quatemary sea level oscillations of at least 5 orders of magnitudes have been distinguished which seem grossly out of phase with eustatic sea level between the weichselian early khvalyn highstand of 50 m and the early holocene mangyshlak lowstand at 80 m the apex of the volga delta has wandered over 700 km alongstream the present day volga delta is not a highstand deposit but probably represents a minor transgression in a major regressional stage the delta does not show a coarsening upwards sedimentary sequence but consists of a weichselian transgressional fining upwards sequence topped by eolian deposits in which the delta distributary channels have been incised present day sedimentation is limited to a narrow fringe along the delta front and to deeper waters over 200 km offshore sea level changes outpaced aggradation to such an extent that volga sediment is spread over the whole north caspian plain sequence stratigraphical principles are difficult to apply because sea level cycles of five orders of magnitude are superimposed and because there is not enough sediment loading or tectonic subsidence to create sufficient accommodation space

anthropogenic influences on shoreline and nearshore evolution in the san francisco bay coastal system abstract analysis of four historical bathymetric surveys over a 132 year period has revealed significant changes to the morphology of the san francisco bar an ebb tidal delta at the mouth of san francisco bay estuary from 1873 to 2005 the san francisco bar vertically eroded an average of 80 cm over a 125 km 2 area which equates to a total volume loss of 100 52 million m 3 of fine to coarse grained sand comparison of the surveys indicates the entire ebb tidal delta contracted radially with the crest moving landward an average of 1 km long term erosion of the ebb tidal delta is hypothesized to be due to a reduction in the tidal prism of san francisco bay and a decrease in coastal sediment supply both as a result of anthropogenic activities prior research indicates that the tidal prism of the estuary was reduced by 9 from filling diking and sedimentation compilation of historical records dating back to 1900 reveals that a minimum of 200 million m 3 of sediment has been permanently removed from the san francisco bay coastal system through dredging aggregate mining and borrow pit mining of this total 54 million m 3 of sand sized or coarser sediment was removed from central san francisco bay with grain sizes comparable to the ebb tidal delta and its direct connection to the bay mouth removal of sediments from central san francisco bay may limit the sand supply to the delta and open coast beaches swan wave modeling illustrates that changes to the morphology of the san francisco bar have altered the alongshore wave energy distribution at adjacent ocean beach and thus may be a significant factor in a persistent beach erosion hot spot occurring in the area shoreline change analyses show that the sandy shoreline in the shadow of the ebb tidal delta experienced long term 1850s 1890s to 2002 and short term 1960s 1980s to 2002 accretion while the adjacent sandy shoreline exposed to open ocean waves experienced long term and short term erosion therefore the recently observed accelerating rates of bay sediment removal ebb tidal delta erosion and open coast beach erosion are all correlated temporally

processes reshaping the nile delta promontories of egypt pre and post protection abstract shoreline positions established from beach profile surveys combined with wave data are jointly analyzed as a function of their contribution to coastal processes to investigate the interaction between waves shoreline orientation and coastal structures along the nile delta promontories rosetta burullus and damietta repeated beach profile surveys along the promontory sectors 64 km long in total have been analyzed to determine rates of shoreline changes prior to construction 1971 1990 and after construction of protective structures 1990 2000 the behavior of coastline pre and post construction indicates that coastal erosion fronting protective structures has declined in the case of the seawalls at the tips of the rosetta and damietta promontories or has been partially replaced by sand accumulation in the case of detached breakwaters at baltim east of burullus promontory and at ras el bar west of the damietta promontory as a consequence downdrift erosion has been initiated in local areas adjacent to these structures in the direction of longshore sediment transport the 5 km long seawall protecting the rosetta promontory has stopped the dramatic erosion of this highly eroded area formerly shoreward retreated 88 m year with adverse local erosion at its west and east ends being 3 and 13 m year respectively similarly the 6 km long seawall built on the eastern tip of the damietta promontory still under construction has nearly stopped the severe erosion which was formerly 10 m year the detached breakwaters at both baltim and at ras el bar have accumulated sand at accretion rates of 37 and 14 m year respectively this sand accumulation is associated with downdrift erosion of 25 and 13 m year at baltim and ras el bar respectively results reaffirm that the original erosion accretion patterns along the nile delta promontories have been reshaped due to the massive protective structures built during the last decade this reshaping along the examined promontories is generally controlled by the temporal variability in the intensity and reversibility of wave directions and associated longshore currents coastline orientation and by the existing coastal protection structures

resonance and morphological stability of tidal basins the paper describes the concept of a network model for the morphological behaviour of a near resonant multiple inlet tidal basin as part of a model system which includes the barrier island coasts and the outer deltas it addresses the question whether a small interference somewhere in such a basin can have major effects on sediment transport and morphology elsewhere in the system in order to explain the basic ideas of the model only the main tidal constituent m2 and the associated topography induced residual current are considered not the overtides furthermore the model concerns only non cohesive sediment sand in spite of these simplifications the model concept is shown to be effective in that it results in a morphological evolution equation for each branch of the network and a picture of the influence of each branch on the resonance sensitivity of the system as a whole

rapid evolution of coastal lagoons in response to human interference under rapid sea level change a south caspian sea case study this research is part of the phd of the first author entitled evaluation of sefidrud delta south west caspian sea during the last millennium which was funded by brunel university london grant no r85104 the publication is a contribution to the inqua quicklakeh project no 1227 and to the european project marie curie climseas pirses ga 2009 247512

dynamics of coupled human landscape systems a preliminary dynamical analysis of landscapes and humans as hierarchical complex systems suggests that strong coupling between the two that spreads to become regionally or globally pervasive should be focused at multi year to decadal time scales at these scales landscape dynamics is dominated by water sediment and biological routing mediated by fluvial oceanic atmospheric processes and human dynamics is dominated by simplifying profit maximizing market forces and political action based on projection of economic effect also at these scales landscapes impact humans through patterns of natural disasters and trends such as sea level rise humans impact landscapes by the effect of economic activity and changes meant to mitigate natural disasters and longer term trends based on this analysis human landscape coupled systems can be modeled using heterogeneous agents employing prediction models to determine actions to represent the nonlinear behavior of economic and political systems and rule based routing algorithms to represent landscape processes a cellular model for the development of new orleans illustrates this approach with routing algorithms for river and hurricane storm surge determining flood extent five markets home labor hotel tourism and port services connecting seven types of economic agents home buyers laborers home developers hotel owners employers hotel developers tourists port services developer and port services owners employers building of levees or a river spillway by political agents and damage to homes hotels or port services within cells determined by the passage or depth of flood waters the model reproduces historical aspects of new orleans economic development and levee construction and the filtering of frequent small scale floods at the expense of large disasters

human induced changes in the geomorphology of the northeastern coast of the nile delta egypt abstract landsat enhanced thematic mapper imagery etm of 2002 and aerial photography of 1955 combined with published charts and field observations were used to interpret geomorphological changes in the coastal zone between kitchener drain and damietta spit in the northeastern nile delta previously recognized as a vulnerable zone to the effects of any sea level rise resulting from global warming the interpretation resulted in recognition of several changes in nine identified geomorphological land types beach and coastal flat coastal dunes agricultural deltaic land sabkhas fish farms manzala lagoon saltpans marshes and urban centers reclamation of vast areas of the coastal dunes and of manzala lagoon added about 420 km2 to the agricultural deltaic land about 48 km2 of sand dunes marshes sabkhas and salt pans have been converted to productive fish farms the main urban centers have expanded and new urban centers damietta harbor and the new damietta city have been constructed at the expense of vast areas of manzala lagoon coastal dunes and backshore flats as the consequence of human activities the size of manzala lagoon has been reduced to less than 50 short term shoreline changes along the coast of the study area established from beach profile survey spanning the years of 1990 to 2000 reveal longshore patterns of erosion versus accretion the rate of shoreline retreat has increased in the downdrift side of damietta harbor 14 m year whereas areas of accretion exist within the embayment of gamasa and in the shadow of ras el bar detached breakwater system with a maximum shoreline advance of 15 m year a sandy spit 12 km long has developed southeast of damietta promontory these erosion accretion patterns denote the natural processes of wave induced longshore currents and sediment transport in addition the impact of man made coastal protection structures

observations of deep long period dlp seismic events beneath aleutian arc volcanoes 1989 2002 abstract between october 12 1989 and december 31 2002 the alaska volcano observatory avo located 162 deep long period dlp events beneath 11 volcanic centers in the aleutian arc these events generally occur at mid to lower crustal depths 10 45 km and are characterized by emergent phases extended codas and a strong spectral peak between 1 0 and 3 0 hz observed wave velocities and particle motions indicate that the dominant phases are p and s waves dlp epicenters often extend over broad areas 5 20 km surrounding the active volcanoes the average reduced displacement of aleutian dlps is 26 5 cm2 and the largest event has a reduced displacement of 589 cm2 or ml 2 5 aleutian dlp events occur both as solitary events and as sequences of events with several occurring over a period of 1 30 min within the sequences individual dlps are often separated by lower amplitude volcanic tremor with a similar spectral character occasionally volcano tectonic earthquakes that locate at similar depths are contained within the dlp sequences at most aleutian volcanoes dlps appear to loosely surround the main volcanic vent and occur as part of background seismicity a likely explanation is that they reflect a relatively steady state process of magma ascent over broad areas in the lower and middle portions of the crust at mount spurr dlp seismicity was initiated by the 1992 eruptions and then slowly declined until 1997 at shishaldin volcano a short lived increase in dlp seismicity occurred about 10 months prior to the april 19 1999 eruption these observations suggest a link between eruptive activity and magma flux in the mid to lower crust and uppermost mantle

a review of the delta po evolution italy related to climatic changes and human impacts abstract climate changes and sea level rise are important issues especially for deltas such as the po delta italy the evolution of the po delta shows a succession in space and a superposition in time of complex environmental natural processes during the last few centuries anthropogenic action has played a major role the formation of the po delta began about 2000 years ago and has undergone many phases of development between 1500 ad and 1600 ad the venetian technicians diverted the po river course with these interventions the renaissance delta was cut off from the hydraulic network and the modern delta began to form until the middle of the 20th century progradation of the delta was noticeable due to the abundant sediment supply in the following decades coastal erosion occurred this was caused by the reduction of the solid supply of the po due to dam and barrier construction and to river bed excavation these and other interventions e g reclamation methane extractions from superficial ground water table have deeply modified the physical and ecological characteristics of the po delta the morphological characteristics of the po delta make the largest italian wetland particularly unstable and very fragile when subjected to human pressure furthermore the delta evidences multiple threats that will probably be exacerbated in the following decades by the effects of expected climatic changes only the application of careful policies concerning coastal defence flood mitigation anthropogenic subsidence reduction and salt wedge intrusion control will allow reduction of the present or predicted negative effects this paper reviews how natural and human factors have controlled the po delta through time and discusses management strategies taking into account the importance of the human factor and the potential effects of climatic changes

the modern po delta system lobe switching and asymmetric prodelta growth the modern po delta system comprising five main delta lobes has been investigated by integrating vhr seismic surveys recorded offshore from water depths as shallow as 5 m to the toe of the prodelta in about 30 m with accurate historical cartography extending back several centuries previous studies give sedimentological and geochronological information from precisely positioned sediment cores this combined historical and stratigraphic reconstruction of the modern po prodelta allows volumetric reconstructions indicating an average sediment load of 9 4 10 6 ty r 1 for po di pila and po di goro gnocca lobes this estimate is remarkably consistent with the total sediment load of 11 5 10 6 ty r 1 available for parts of the last century from a gauge station at the apex of the delta plain in pontelagoscuro these integrated stratigraphic studies allow to explain the key characters of the po delta system a the marked asymmetry of the whole delta prodelta system reflecting prevailing sediment dispersal to the south of each individual delta outlet b the shoreparallel overlapping of successive prodelta lobes fed by distinct river outlets of ever changing relative importance c the delta outlets being artificially forced in a fixed position so that natural avulsion is prevented and delta lobes undergo headland retreat leaving a marked erosion on the prodelta d the presence of prodelta lobes showing widespread bcut and fillq features ranging from 100 to 300 m and depths up to 4 5 m filled with massive silt to very fine sand offshore of short lived very active distributary channels e g po di tolle lobe and suggesting that in some particular interval short lived episodes of submarine erosion are induced by catastrophic increases in river discharge of natural origin or induced by human maintenance the seismic stratigraphy of the modern po delta documents that markedly distinct prodelta architectures form when a newly activated lobe is located updrift north in this case or downdrift south of the one that is retreating in the first case the abandoned lobe becomes sheltered by the new rapidly advancing one in the opposite case the retreating lobe is updrift and a substantial portion of the sediment is cannibalized and transported to the new lobe downdrift d 2005 elsevier b v all rights reserved

holocene evolution of the coast of holland abstract the holocene evolution of the coast of holland was controlled by the complex interaction of such diverse parameters as wave and tidal climate the rate of sea level rise and the morphology of the pre transgressional surface the latter in combination with the rate of sea level rise mainly determines the location of sediments sources and sinks while the hydrodynamic parameters mainly determine the rate and direction of sediment transport in the early holocene the low sea level in the shallow southern north sea strongly affected wave climate and tidal regime however the barrier and back barrier sedimentary record since 5000 14c yrs b p gives us no reason to assume major changes in these parameters since then so we conclude that breaks in barrier development are due to variations in rate of sea level rise inl combination with the morphology of the pre transgressional surface the transformation from an open tide dominated to a closed wave dominated coast which occurred in the subboreal period and the concomitant change in barrier movement from transgressive to regressive around 5000 yrs b p are the main events in the development of the coast of holland up to the middle ages the morphology of the pre transgressional surface gives a shoreline in the late atlantic which consists of two protruding headlands separated by a large tidal basin the southern headland is the alluvial plain of the rhine and the meuse the northern headland constitutes the moraines of the texel high the tidal basin in between is connected to the north sea by a large number of inlets the rate of sea level rise at that time 1 m century outran the supply of sediment to the tidal basin after 6000 yrs b p the rate of sea level rise decreased gradually whereas the rate of sediment supply remained constant this led to a gradual decrease in the tidal prisms of the inlets as the tidal basin was filled in with sediment shortly before 5000 yrs b p the first channels silted up and closed the last tidal channel disappeared around 3300 yrs b p leaving two inlets along the coast which were both connected to the river rhine the closure of the first inlets occurred at the same time as the barrier began prograding because 1 the rate of sea level rise diminished considerably 2 not all the sand supplied by longshore and cross shore transport disappeared into the tidal basin but instead could be used for barrier progradation and 3 ebb tidal deltas of the closed inlets provided major sand sources the prograding barrier sequence enclosed between the two headlands roughly forms a closed system using the relationships between tidal prism cross sectional area of inlets and volume of the ebb tidal delta and the results of modelling of longshore transport along the subboreal coast under present day wave conditions a simple sand budget for the coast of holland is given which shows that a large part of the sand now stored in the barrier sequence was obtained by cross shore transport from the north sea

modeling shore normal large scale coastal evolution abstract we present a model for the evolution of the shelf surface in response to marine sedimentary processes following morphodynamical theory the model presupposes a characteristic configuration of the shelf surface that in profile is a concave up exponential curve whose steeper inner limb is the shoreface the profile is seen as an equilibrium response to the variables of sedimentation the profile translates landward or seaward as sea level rises or falls but will do so in an state of dynamic equilibrium with the shape of the profile varying according to changes in 1 the rate of sea level change 2 the time averaged wave and bottom current conditions 3 the average allochthonous sediment supply rate and 4 the sediment grain size distribution the governing equations for the model include an equation for time averaged cross shore diabathic sediment flux and the sediment continuity equation p simulations of continental margin profiles show that profile adjustments affect mainly the coefficient of curvature of the profile an increase in the rate of sea level rise straightens the profile it decreases the slope of the shoreface but increases the shelf slope an increase in sediment input increases profile curvature the shoreface steepens while the shelf floor flattens an intensification of hydraulic climate straightens the profile in a manner similar to an increase in the sea level rise rate while an increase in grain size increases profile curvature as does an increase in sediment input

deep and shallow long period volcanic seismicity linked by fluid pressure transfer volcanic long period earthquakes are attributed to pressure fluctuations that result from unsteady mass transport in the plumbing system of volcanoes whereas most of the long period seismicity is located close to the surface the volcanic deep long period earthquakes that occur in the lower crust and uppermost mantle reflect the activity in the deep parts of magmatic systems here we present observations of long period earthquakes that occurred in 2011 2012 within the klyuchevskoy volcano group in kamchatka russia we show two distinct groups of long period sources events that occurred just below the active volcanoes and deep long period events at depths of 30 km in the vicinity of a deep magmatic reservoir we report systematic increases of the long period seismicity levels prior to volcanic eruptions with the initial activation of the deep long period sources that reflects pressurization of the deep reservoir and consequent transfer of the activity towards the surface the relatively fast migration of the long period activity suggests that a hydraulic connection is maintained between deep and shallow magmatic reservoirs the reported observations provide evidence for the pre eruptive reload of the shallow magmatic reservoirs from depth and suggest that the deep long period earthquakes could be used as a reliable early precursor of eruptions shallow volcanic earthquakes can aid eruption forecasts analysis of seismicity beneath the klyuchevskoy volcano group in russia reveals much deeper magma induced earthquakes that may serve as an early eruption indicator

formation and circulation of dense water in the persian arabian gulf 1 the nature and circulation of water masses in the persian arabian gulf hereinafter referred to as the gulf is investigated by examination of a historic database of hydrographic observations the densest water forms in winter at the northern end of the gulf rather than along the warmer southern and western coasts with the exception of small amounts of water directly above the seafloor most water flowing out of the gulf mixes across a density front that separates gulf deep water within the gulf from the indian ocean surface water iosw contrary to previous inferences the seasonally variable incursion of iosw into the gulf peaks in late spring this timing may be due to seasonal changes in sea surface slope driven by variations in evaporation rate in order to explain mooring results published elsewhere that show relatively small seasonal changes in the volume flux through the strait of hormuz hereinafter referred to as the strait we suggest that this flux is driven by the difference between the density of gulf deep water in the interior of the basin and water at comparable depths outside the gulf this density difference varies less than 15 during the year high rates of vertical mixing in the strait extend about 200 km westward in response to topographic constriction of tidal flows by islands and shoals