the hydrology of piermont marsh a reference for tidal marsh restoration in the hudson river estuary new york abstract the topography hydroperiod water table and selected edaphic characteristics are described for piermont marsh an irregularly flooded tidal marsh in the hudson river estuary new york usa despite variations in microtopography overall the marsh is flat and although the observations were conducted at a high point in the estuary s 18 6 year metonic cycle its surface was only inundated 10 12 times a month observations of spatial differences in the saturated hydraulic conductivity and surface infiltration rates are also discussed edge portions of the marsh are characterized by a slightly higher more uniform more structured less organic and less hydrologically conductive substrate than found in the marsh interior preferential flow is facilitated by macropores in the creekbank wall the water table is close to the marsh surface for a lesser percentage of the lunar month in the marsh edge when compared to the interior where it is almost always within 10 cm of the surface the extent to which the spatial variability of these hydrologic characteristics determines the marsh s ability to provide various ecosystem services is also discussed and the implications of these observations on tidal marsh restoration efforts briefly presented

deriving mechanisms and thresholds for cliff retreat in soft rock cliffs under changing climates rapidly retreating cliffs of the suffolk coast uk abstract understanding changing thresholds and mechanisms for retreat in soft rock cliffs is important under changing climates this can be achieved through combining detailed field observation long term process and morphological monitoring and numerical modelling the cliffs of the suffolk coast southern north sea have exhibited long term 1883 2010 recession rates of 3 5 m a 1 rising to 4 7 m a 1 in the period 1993 2010 annual to biannual ground survey data and the application of gis techniques to digitised records of changing shoreline position from historic maps and aerial photography reveal considerable decadal scale variations in cliff recession within which are nested inter annual fluctuations in rates of retreat archival datasets on significant periods of onshore winds and their interaction with high water levels including the incidence of storm surges and rainstorm events are used to determine thresholds for cliff base erosion and its propagation upwards through the cliff profile in addition the geo slope dynamic coupled hydrology stability model is used to establish thresholds for cliff face failures driven by variations in rainfall inputs retreat mechanisms are complex governed by cliff geology both as a primary control on suction loss and through its interaction with basal marine conditions the study allows a general model of cliff retreat for soft rock cliffs to be put forward whereby a resistant basal platform is overlain by more erodible weakly and moderately cemented sands and gravels in this model the varying balance between marine and terrestrial forcing factors are reflected in low 7 m a 1 modes of cliff retreat

coastal management and sea level rise abstract the predicted rise in sea level due to global warming has given rise to much speculation as to the impact on erosion and accretion rates at the coast as well as increases in hazards to coastal users this paper focuses on the spatial adjustments that coastal landforms will exhibit in response to changing energy gradients both normal to and parallel to the shore these adjustments in many cases will take the form of the migration of landforms in order that they maintain their position within the coastal energy gradient prediction of the rates of such migration will be fundamental to the future management of the changing coastal environment the paper discusses the impact of sea level rise on the two basic coastal landform assemblages those in estuaries and those on the open coast and then goes on to examine the effect on ebb tidal deltas that are located at the critical junction between estuaries and open coasts in each case the rates of landform migration under an accelerated sea level rise are predicted and compared with existing rates using examples from the east coast of britain assuming a sea level rise of 6 mm year the paper predicts that estuaries will migrate landwards at rates of around 10 m year open coast landforms can exhibit long shore migration rates of 50 m year while ebb tidal deltas may extend laterally along the shore at rates of 300 m year the implication for the management of such dynamic coastal systems including such issues as coastal defence and conservation are discussed

understanding coastal change using shoreline trend analysis supported by cluster based segmentation abstract shoreline change analysis is a well defined and widely adopted approach for the examination of trends in coastal position over different timescales conventional shoreline change metrics are best suited to resolving progressive quasi linear trends however coastal change is often highly non linear and may exhibit complex behaviour including trend reversals this paper advocates a secondary level of investigation based on a cluster analysis to resolve a more complete range of coastal behaviours cluster based segmentation of shoreline behaviour is demonstrated with reference to a regional scale case study of the suffolk coast eastern uk an exceptionally comprehensive suite of shoreline datasets covering the period 1881 to 2015 is used to examine both centennial and intra decadal scale change in shoreline position analysis of shoreline position changes at a 100 m alongshore interval along 74 km of coastline reveals a number of distinct behaviours the suite of behaviours varies with the timescale of analysis there is little evidence of regionally coherent shoreline change rather the analyses reveal a complex interaction between met ocean forcing inherited geological and geomorphological controls and evolving anthropogenic intervention that drives changing foci of erosion and deposition

role of geomorphic and hydraulic parameters in governing pore water seepage from salt marsh sediments 1 a numerical boundary integral equation model has been used to study the effects of marsh geomorphology and hydraulic parameters on the seepage of pore water into tidal channels and its subsequent recharge by tidal inundation in general the results show that regardless of the geomorphic configuration the locus of maximum seepage flux occurs at or near the intersection of the creek bank and the channel water surface over a tidal cycle typically two thirds of the total seepage discharge occurs through the creek bank with only about a third discharging from the channel bottom in most cases the volume of seepage discharging through the creek bank exceeds by a factor of two or more that emanating from the channel bottom of the creek bank discharge up to half may occur through the seepage face that develops above the tide line at tidal stages below mean tide the ratio of creek bank to bottom seepage only approaches unity when the thickness of the aquifer beneath the bottom is similar to or greater than the width of the channel bottom and the ratio of conductivity to specific yield exceeds 0 5 for given hydraulic parameters total seepage volume varies directly with creek bank slope and aquifer thickness whereas these factors are inversely related to the ratio of the two seepage components channel bottom width on the other hand has no influence on total seepage volume but greatly increases the component ratio as the width approaches zero since most of the seepage discharge is derived from sediments within several meters of the creek bank variations in seepage discharge driven by variations in marsh geomorphology might play a role in the productivity of creekside cord grass several hypotheses are offered and discussed regarding the effects of geomorphology on creekside productivity these results also indicate that placement of seepage meters only on the channel bottom will not give samples or measures representative of the total seepage

tide induced seawater groundwater circulation in shallow beach aquifers summary in this paper we investigated the tide induced seawater groundwater circulation in shallow beach aquifers using the finite element model marun the numerical solutions were generalized using a dimensionless formulation from a dimensionless tidal period and a dimensionless beach slope of 10 we obtained results that apply to a wide range of beach permeabilities from 10 4 m s to 10 3 m s beach slopes from 3 16 to 31 6 tidal amplitude 0 3 m 2 m and period diurnal or semidiurnal the numerical simulations demonstrated the following the maximum darcy velocity always occurs at the intersection of the watertable and the beach surface the offshore beach groundwater is almost stagnant compared with the onshore groundwater flow which may explain the previous observations that the major portion of the seaward groundwater seepage usually occurs in the shallow part of the submerged beach the outflow from the seepage face accounts for 41 97 average 55 of the outflow from the intertidal zone the amount of seawater infiltrating into the intertidal zone in a tidal cycle increases with the beach permeability and decreases when the inland recharge increases and ranges from 35 5 m 3 yr 1 m 1 to 505 8 m 3 yr 1 m 1 for all the cases considered smaller beach slopes smaller inland freshwater recharges and or greater beach permeability lead to larger saltwater plumes in the intertidal zone of the beach the results are in line with the existing results of field observations and numerical simulations by previous researchers a 2008 elsevier b v all rights reserved

a numerical study of nighttime ionospheric variations in the american sector during 28 29 october 2003 variations of nighttime f2 peak height hmf2 over the american sector during the 28 29 october 2003 storm period were investigated using the national center for atmospheric research thermosphere ionosphere electrodynamics global circulation model the model was generally able to reproduce the ionospheric variations on 28 29 october 2003 observed by the ionosondes a series of controlled model simulations were subsequently undertaken to examine the effects of electric fields and neutral winds on the ionosphere the numerical experiments suggest that the dramatic nighttime increase of hmf2 on the storm day 29 october is mainly caused by traveling atmospheric disturbances tads from the high latitudes of the northern hemisphere however the electric field plays an important role in causing the elevation of hmf2 in the equatorial region the prompt penetration electric field ppef associated with the southward component of the interplanetary magnetic field bz is westward on the nightside whereas when bz reverses and becomes northward the ppef is westward in the premidnight and turns to eastward in the postmidnight these ppefs greatly affect the low latitude ionosphere during storm time on 28 october even though the bz disturbance was weak with a short duration of southward bz the tads from the southern hemisphere can propagate to the northern hemisphere and result in the corresponding oscillations in the nightside hmf2

the extreme 2013 2014 winter storms hydrodynamic forcing and coastal response along the southwest coast of england the southwest coast of england was subjected to an unusually energetic sequence of atlantic storms during the 2013 2014 winter with the 8 week period from mid december to mid february representing the most energetic period since at least 1953 a regional analysis of the hydrodynamic forcing and morphological response of these storms along the sw coast of england highlighted the importance of both storm and site specific conditions the key factor that controls the atlantic storm wave conditions along the south coast of southwest england is the storm track energetic inshore wave conditions along this coast require a relatively southward storm track which enables offshore waves to propagate up the english channel relatively unimpeded the timing of the storm in relation to the tidal stage is also important and coastal impacts along the macro tidal southwest coast of england are maximised when the peak storm waves coincide with spring high tide the role of storm surge is limited and rarely exceeds 1 m the geomorphic storm response along the southwest coast of england displayed considerable spatial variability this is mainly attributed to the embayed nature of the coastline and the associated variability in coastal orientation on west facing beaches typical of the north coast the westerly atlantic storm waves approached the coastline shore parallel and the prevailing storm response was offshore sediment transport many of these north coast beaches experienced extensive beach and dune erosion and some of the beaches were completely stripped of sediment exposing a rocky shore platform on the south coast the westerly atlantic storm waves refract and diffract to become southerly inshore storm waves and for the southeast facing beaches this results in large incident wave angles and strong eastward littoral drift many south coast beaches exhibited rotation with the western part of the beaches eroding and the eastern part accreting 2015 the authors earth surface processes and landforms published by john wiley sons ltd

modelling waves and surges during the 1953 storm waves and sea levels have been modelled for the storm of 31 january 1 february 1953 problems in modelling this event are associated with the difficulty of reconstructing wind fields and validating the model results with the limited data available from 50 years ago the reconstruction of appropriate wind fields for surge and wave models is examined the surges and waves are reproduced reasonably well on the basis of tide gauge observations and the sparse observational information on wave heights the maximum surge coincided closely in time with tidal high water producing very high water levels along the coasts of the southern north sea the statistics of the 1953 event and the likelihood of recurrence are also discussed both surge and wave components were estimated to be approximately 1 in 50 year events the maximum water level also occurred when the offshore waves were close to their maximum the estimation of return period for the total water level is more problematic and is dependent on location a scenario with the 1953 storm occurring in 2075 accounting for the effects of sea level rise and land movements is also constructed suggesting that sea level relative to the land could be 0 4 0 5 m higher than in 1953 in the southern north sea assuming a rise in mean sea level of 0 4 m

coastal cliff behaviour observations on the relationship between beach levels and recession rates abstract beaches dissipate wave energy and regulate the frequency that the cliff foot is subject to wave attack the relationship between beach levels and cliff recession rates has been established for pleistocene soft rock cliffs along the north norfolk and suffolk coasts uk the results suggest that over a decadal timescale there is a non linear increase in the average recession rate as the beach profile area above high water mark hwm decreases small changes in beach level can result in significant differences in the recession rates the impact of a unit change in beach level on the recession rate depends on the initial beach level on a year by year basis it is possible to divide the beach level and recession relationship into a series of zones with characteristic types of behaviour at low beach levels there is high to extremely high recession with considerable variability whereas at high beach levels there is almost zero recession with limited variability it is concluded that historical recession rates are the product of both the past forcing events and changes in cliff beach state extrapolation of historical rates can be extremely unreliable unless it is supported by an understanding of the dynamic behaviour of the cliff beach system and the energy inputs over the observation period

hydrogeological characterization of an altered wetland summary spatiotemporal changes in the hydrogeology of the hula altered wetland may influence the water quality of lake kinneret which provides up to 30 of the potable water for the state of israel the main objectives of this work were to study the groundwater flow characteristics in this wetland and assess the potential impact on downstream water quality we constructed variograms of hydraulic heads computed decision tree models of major ions and determined the hydraulic conductivity k and 2 h 18 o ratios to ascertain the spatial and vertical distribution of hydrogeological parameters we also performed large scale field experiments 1 km 2 to assess the connectivity between the waterways and the wetland s aquifer the aquifer is fragmented by three parent materials deep peat shallow peat marl complex and marl the decision tree based model the isotopic ratios and k determinations suggest that the deep peat subaquifer is composed of one homogeneous layer characterized by low k 0 001 m d 1 the two other subaquifers consist of three hydrostratigraphic layers i the vadose zone ii a layer with well developed macropores at a depth of 1 5 4 m and iii an aquitard layer at a depth of 4 15 m the temporal head fluctuations the high k values of the second layer 170 m d 1 and the large volume of water flowing into and out of the two subaquifers during large scale field experiments all attest to excellent connectivity with the waterways these results support the concept of critical source area which claims that most of the p loss in a catchment derives from small areas in which specific p release and transport mechanisms coincide with high connectivity we conclude that the high connectivity of this mediterranean altered wetland to waterways coupled with the high p release that has occurred in recent years following soil flooding provides the loading mechanism that partially explains the observed p increase in the jordan river

fluxes of water and solute in a coastal wetland sediment 2 effect of macropores on solute exchange with surface water abstract we investigated interactions between sediment physical structure and solute transport in an intertidal coastal wetland two distinct pore size classes in the sediment were identified macropores had effective diameters greater than 100 m and a normalized volume of 5 matrix pores had effective diameters smaller than 100 m and were the volumetrically dominant pore size class 95 we found that infiltration and evaporation driven water fluxes were segregated between macropores and matrix pores respectively which had the effect of enhancing diffusive effluxes of chloride from the sediment to surface water chloride was highly concentrated relative to seawater in matrix porewater but was comparatively dilute in macropores concentration differences in pore size classes declined with depth until indistinguishable below 10 cm the segregated chloride distribution can be explained if recharge to the sediment occurred by downward infiltration in macropores and discharge occurred by an upward flux in matrix pores to satisfy evapotranspiration without disturbance by the downward infiltration flux in macropores upward advection of chloride in matrix pores and evapoconcentration increased chloride concentrations in matrix pores to a level well above the concentration in seawater the resulting high concentrations of chloride in matrix pores induced a large diffusive efflux of chloride into surface water that was sufficient to balance new input of chloride by infiltration of seawater in macropores 0 085 mmol cl cm 2 day transport models that were constrained by water balance measurements at the field site explained both the exponential form of the vertical distribution of chloride in matrix pores and the rate of change in storage of chloride in sediment porewater over a 1 month period we conclude that segregation of water and solute fluxes in two pore size classes strongly influences sediment salinity of coastal wetlands which has direct bearing on primary productivity of dominant vegetation and on exchange of dissolved nutrients and contaminants between intertidal wetlands and open water

decadal and seasonal development of embryo dunes on an accreting macrotidal beach north lincolnshire uk embryo dunes are often ephemeral but can develop to become established coastal foredunes in 2001 a patch of embryo dunes 13 11 m2 appeared on a beach in north lincolnshire uk and had expanded to over 3600 m2 by 2011 the rate of expansion is linked to storm occurrence where expansion is slowed during years with a higher incidence of storm surges from july 2009 october 2010 seasonal changes in dune field topography were determined using terrestrial laser scanning tls data vegetation is important in the development of embryo dunes but can cause errors in tls data tests evaluating the impact of vegetation on the tls data suggest the minimum elevation value from the tls point cloud within a 0 05 m grid cell gives a good approximation of the ground surface digital elevation models dems of the dunes constructed using filtered data showed the embryo dunes underwent a classic seasonal cycle of erosion during the winter and accretion during the summer for example from october 2009 to april 2010 over 375 m3 of sediment was eroded from the dunes whereas during spring and summer 2010 the dune field gained over 600 m3 of sand the overall magnitude of change in dune height and volume from season to season exceeded the errors associated with the construction of the dem from the tls data and the vegetation filtering process which suggests tls can be useful for documenting topographic change in vegetated dunes after 10 years the patch of embryo dunes is still expanding but has not yet merged with more established foredunes to landward aeolian process measurements indicate that at present the embryo dunes do not prevent sand from reaching the foredunes however the rate of foredune progradation has slowed concurrently with the expansion of the embryo dune field copyright 2013 john wiley sons ltd

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

understanding the variability of an extreme storm tide along a coastline correctly determining the peak storm tide height along the coastline and expressing the associated natural variability is essential for a robust prediction of coastal flood risk a new approach is proposed that calculates a storm tide relationship relative to a tide gauge by using a storm surge model to describe the natural spatial variability based on the features of a large number of very high storm tides two historic flood events 1953 and 2007 were used to validate this characteristics approach along the east anglia coastline u k and predicted water levels were found to be in good agreement with tide gauge observations root mean squared error of 36 cm especially when compared to the method of assuming a storm tide of constant return period root mean squared error of 59 cm detailed observations of storm tide height between tide gauge locations are rare therefore synthetic aperture radar sar was employed to calculate the lidar geo referenced storm tide height along the north somerset coastline of the bristol channel u k two sar observed extreme storm tide events were used to validate the characteristics approach between tide gauges root mean squared error of 1 2 m and 0 7 m and indicated the presence of localised wave effects to the observed storm tide height that could have a significant effect to flood risk estimates

contrasting behavior of the f2 peak and the topside ionosphere in response to the 2 october 2013 geomagnetic storm in this study the ionospheric observations from ionosondes ground based gps receivers gravity recovery and climate experiment grace and metop a satellites and fabry perot interferometer over the asian australian sector have been used to investigate the responses of the f2 peak and the topside ionosphere to the 2 october 2013 geomagnetic storm particularly during the recovery phase the comparison between the multiple simultaneous observations revealed a contrasting behavior of the topside ionosphere and the f2 peak in east asia during the recovery phase the upward looking total electron content from low earth orbit leo satellites did not undergo such depletions as seen in the region near the f2 peak and they even showed increases furthermore the simulation results of the thermosphere ionosphere electrodynamics general circulation model are used to explore the possible mechanisms responsible for the observed features the model results and observations suggested that the contrasting behavior of the f2 peak and the topside ionosphere is mainly associated with the enhancement of the equatorward winds albeit the disturbed electric fields could play an important role in producing it

glacial deposits in great britain and ireland with the increasing awareness of environmental problems there is a growing desire for a de tailed understanding of superficial deposits in general and glacial deposits in particular this is because these sediments have a profound influence on groundwater protection waste management and nature conservation they are also of vital importance to civil engineering because they provide the foundation for as well as the materials extracted to build our roads and buildings the greater part of the british isles was glaciated at least once during the quater nary era in the regions subjected to glaciation glacial deposits underlie much of the present land surface although there have been many recent publica tions on various quaternary geological topics the present volume is the first dedicated to a detailed assessment of the glacial deposits of britain and ireland after introductory chapters presenting the glacial history the sedimentary sequences in 24 critical regions are discussed these regions include all of ireland the gla ciated area of great britain and the adjoining offshore region of the north sea the controver sial evolution of the irish sea basin during the last glaciation is discussed from various view points a collection of critical topics presented in the later part of the book range from the classification of glacigenic landforms and de posits to the results of geophysical geotechnical and geochemical analyses the book includes 368 figures 40 tables and 51 colour photographs a detailed index and a list of over 1000 references with 45 contributions by 48 scientists this volume represents a truly contemporary view of this field of research to gether with its companion volume the glacial deposits in north west europe this book pro vides an excellent textbook for the advanced student or the amateur as well as an indispen sible source and guidebook for the professional scientist

reconstructing and understanding the impacts of storms and surges southern north sea coastal barriers are ubiquitous globally and provide a vital protective role to valuable landforms habitats and communities located to landward they are however vulnerable to extreme water levels and storm wave impacts a detailed record of sub annual to annual decadal and centennial rates of shoreline retreat in frontages characterised by both high 3 m and low 1 m dunes is established for a barrier island on the uk east coast for four storms 2006 2013 we match still water levels and peak significant wave heights against shoreline change at high levels of spatial densification the results suggest that at least in the short term shoreline retreat of typically 5 8 m is primarily driven by individual events separated by varying periods of barrier stasis over decadal timescales significant inter decadal changes can be seen in both barrier onshore retreat rates and in barrier extension rates alongshore whilst the alongshore variability in barrier migration seen in the short term remains at the decadal scale shoreline change at the centennial stage shows little alongshore variability between a region of barrier retreat at 1 15 m a 1 and one of barrier extension a data mining approach synchronising all the variables that drive shoreline change still water level timing of high spring tides and peak significant wave heights is an essential requirement for validating models that predict future shoreline responses under changing sea level and storminess

controls of soil pipe frequency in upland blanket peat 1 soil pipes were surveyed in 160 british blanket peat catchments using consistent application of ground penetrating radar soil pipes were found in all catchments the mean frequency of piping was 69 per kilometer of surveyed transect land management moorland gripping appears to exert the most important control on hillslope pipe frequency in blanket peats management practice in peatlands may therefore induce more rapid subsurface erosion carbon loss and landform denudation via enhanced preferential flow topographic position is also important with topslopes having greater pipe frequencies than footslopes followed by midslopes with lowest frequencies slope gradient however is not a significant factor in controlling blanket peat pipe frequency i propose that peat structural properties inherited from the way a blanket peat develops on a hillslope strongly control pipe network development this is manifested in the way slope position appears to control pipe frequency aspect appears not to influence pipe frequency in blanket peats except that it does play a weak role in catchments with annual precipitation 1500 mm here southwesterly facing slopes tend to have more frequent piping

temporal and spatial variations in recession rates and sediment release from soft rock cliffs suffolk coast uk high rates of coastal retreat characterise the weakly cemented plio pleistocene rocks and sediments which form much of the cliffed coastline of east anglia southern north sea the accurate establishment of sediment losses from these cliffs has a regional significance as these sediments are important in maintaining beaches and nearshore bank systems and in feeding nearshore sediment transport pathways however the high spatial and temporal variability of cliff failure processes in such materials necessitates fine scale integration of alongshore variations in cliff retreat over a series of well established time periods to accurately define cliffline recession rates and sediment volume inputs to the nearshore system this study applied the dsas digital shoreline analysis system within the gis software package arcmap to digitised georeferenced positions of former shorelines obtained from historic maps and aerial photographs after 1992 for the sections of benacre southwold and dunwich minsmere on the suffolk coast of east anglia uk transects were cast every 10 m alongshore producing very high spatial resolution upon which to assess shoreline retreat over 1000 transects along 11 km of shoreline long term 1883 2008 mean shoreline retreat rates varied between 2 3 3 5 m a 1 benacre southwold and 0 9 m a 1 dunwich minsmere for six cliffed subunits within these larger coastal sections spatial variations in cliffline recession rates for shorter time intervals at ca 20 year intervals within this longer 125 year period were established the combination of recession rates with photogrammetric methods of obtaining cliff top elevation at the same spatial resolution available using aerial photographs and digital terrain models along with cliff sediment composition allowed the calculation of sediment volumetric inputs from cliff retreat in the period 1992 2008 re assessment of the magnitude and location of sediment inputs into the nearshore zone their interaction with regional sediment transport and the growth of inshore bank systems as well as the implications for contemporary and near future coastal management strategies are discussed with reference to this section of the suffolk coast

a statistical dynamical method for predicting long term coastal evolution abstract a new approach to the problem of predicting long term coastline evolution is described the cumulative effect of shoreline processes is inferred by inverting an extended form of one line equation results from the inversion process are then used to predict future coastal evolution on the basis of past historical changes the data required are charts showing the historical changes in coastline position by way of validation the model is applied to a region on the east coast of the united kingdom where a 12 year forecast is made and compared against recent aerial survey data the results are encouraging and suggest that the method has a predictive capability suitable for strategic studies of regional shoreline evolution

variability and predictability of the north atlantic wave climate wave climate across the ocean basins can be described using satellite altimetry here we concentrate on the north atlantic region waves in the north atlantic are strongly seasonal and peak in the winter season the northeastern sector of the atlantic and adjoining shelf seas also exhibit exceptionally high interannual variability in the winter with monthly average significant wave height varying by up to a factor of 2 from one year to the next the strength and geographical distribution of variability is broadly consistent throughout the winter months december march a large fraction of these wave height anomalies is associated with a single pattern of pressure anomalies that resembles the north atlantic oscillation nao a predictor based on nao dependence is trained from relatively recent satellite data and then tested against earlier satellite and in situ data the predictor is successful in large areas of the north atlantic confirming a robust relationship between wave height anomalies and the nao over the last few decades a substantial rise up to 0 6 m in monthly mean wave heights on the northeastern atlantic during the latter part of the twentieth century is attributable to changes in the nao substantial residual anomalies in wave heights exist after the influence of the nao has been subtracted these are partly explained by a second pair of north atlantic patterns in wave height anomalies and sea level pressure anomalies this east atlantic pattern is particularly influential in midwinter and affects the southern part of the northeastern sector including the region of seven stones light vessel

environmental hydrogeology of the southern sector of the samborombon bay wetland argentina the samborombon bay wetland is located on the west margin of the rio de la plata estuary in the province of buenos aires argentina this paper analyses the geological geomorphologic soil and vegetation characteristics of the southernmost sector of this wetland and their influence on surface water and groundwater the study area presents three hydrologic units coastal dunes sand sheets and coastal plain coastal dunes and sand sheets are recharge zones of high permeability with well drained non saline soils and a few surface water flows changes in the water table are related to rainfall groundwater in coastal dunes is ca mg hco3 to na hco3 and of low salinity 590 mg l groundwater in sand sheets is mainly na hco3 with a salinity of about 1 020 mg l the coastal plain exhibits medium to low permeability sediments with submerged saline soils poorly drained groundwater is na cl with a mean salinity of 16 502 mg l a surface hydrological network develops in the coastal plain surface water levels near the shoreline are affected by tidal fluctuations far from the shoreline water accumulates because of poor drainage both sectors have na cl water but the former is more saline human intervention and sea level rise may affect the wetland severely

beach response to shore parallel breakwaters at sea palling norfolk uk abstract the effects of four offshore breakwaters built between 1993 and 1995 at sea palling norfolk uk on beach morphology are discussed the structures were built during the first phase of a multi phase construction programme and are expected to provide long term protection for sea palling and 6000 ha of low lying land against tidal inundation through the provision of a wide beach in front of the existing seawall and dunes the results presented here span all stages of breakwater construction during phase 1 beach level changes were monitored during the period from 1995 to 1999 a geographical information system gis was used to calculate differential surfaces between surveys in order to investigate local patterns of accretion and erosion and to determine volume changes between consecutive surveys additional data collected by the environment agency since 1991 were analysed to investigate beach and bathymetry changes prior to the construction of the breakwaters in association with periodic nourishment programmes the scheme has been locally successful in retaining recharged sediment on the beach but the extent of the salients prevents to a great extent the south eastward littoral drift as a result effects on the beaches both down and up drift of the breakwaters have been considerable the continuing increase in beach volume indicated that by january 1999 equilibrium had not been reached

conceptualising and mapping coupled estuary coast and inner shelf sediment systems whilst understanding and predicting the effects of coastal change are primarily modelling problems it is essential that we have appropriate conceptual frameworks for 1 the formalisation of existing knowledge 2 the formulation of relevant scientific questions and management issues 3 the implementation and deployment of predictive models and 4 meaningful engagement involvement of stakeholders important progress continues to be made on the modelling front but our conceptual frameworks have not evolved at a similar pace accordingly this paper presents a new approach that re engages with formal systems analysis and provides a mesoscale geomorphological context within which the coastal management challenges of the 21st century can be more effectively addressed coastal and estuarine system mapping cesm is founded on an ontology of landforms and human interventions that is partly inspired by the coastal tract concept and its temporal hierarchy of sediment sharing systems but places greater emphasis on a hierarchy of spatial scales this extends from coastal regions through landform complexes to landforms the morphological adjustment of which is constrained by diverse forms of human intervention crucially cesm integrates open coastal environments with estuaries and relevant portions of the inner shelf that have previously been treated separately in contrast to the nesting of littoral cells that has hitherto framed shoreline management planning cesm charts a complex web of interactions of which a sub set of mass transfer pathways defines the sediment budget and a multitude of human interventions constrains natural landform behaviour conducted within a geospatial framework cesm constitutes a form of knowledge formalisation in which disparate sources of information published research imagery mapping raw data etc are generalised into usable knowledge the resulting system maps provide a framework for the development and application of predictive models and a repository for the outputs they generate not least flux estimates for the major sediment system pathways they also permit comparative analyses of the relative abundance of landforms and the multi scale interactions between them finally they articulate scientific understanding of the structure and function of complex geomorphological systems in a way that is transparent and accessible to diverse stakeholder audiences as our models of mesoscale landform evolution increase in sophistication cesm provides a platform for a more participatory approach to their application to coastal and estuarine management

sedimentary records of coastal storm surges evidence of the 1953 north sea event the expression of storm events in the geological record is poorly understood therefore stratigraphic investigations of known events are needed the 1953 north sea storm surge was the largest natural disaster for countries bordering the southern north sea during the twentieth century we characterize the spatial distribution of a sand deposit from the 1953 storm surge in a salt marsh at holkham norfolk uk radionuclide measurements core scanning x ray fluorescence itrax and particle size analyses were used to date and characterise the deposit the deposit occurs at the onset of detectable 137cs coeval with the first testing of nuclear weapons in the early 1950s the sand layer is derived from material eroded from beach and dunes on the seaward side of the salt marsh after the depositional event accumulation of finer grained silt and clay materials resumed this work has important implications for understanding the responses of salt marshes to powerful storms and provides a near modern analogue of storm surge events for calibration of extreme wave events in the geological record

assessment of submarine groundwater discharge in the intertidal zone of laizhou bay china using electrical resistivity tomography abstract coastal zones are the most sensitive and vulnerable ecological environments in the world submarine groundwater discharge sgd is an important pathway for material transport between land and sea in the low lying coastal plains of coastal zones in the present study electrical resistivity tomography was used to monitor submarine groundwater discharge in the intertidal zone the salinity change ratio was derived using archie s law and manheim s equation and was used as an index to describe the dynamic discharge process a model of the seawater circulation process in the multilayer coastal aquifer system was established the model contains a window area between the upper unconfined and lower confined aquifer and a highly permeable channel in the upper silt layer the results of the study provide a theoretical basis and technical support for the rapid assessment of sgd in low lying coastal plains and will assist in the management of coastal zone environments

the impact of sea level rise and climate change on inshore wave climate a case study for east anglia uk in coastal areas offshore wave propagation towards the shore is influenced by water depth variations due to sea bed bathymetry tides and surges considering implications of climate change both on atmospheric forcing and sea level rise a simple methodology involving numerical modelling is implemented to compute inshore waves from 1960 to 2099 simulations take into account five scenarios of linear sea level rise and one climatic scenario for storm surges and offshore waves the methodology is applied to the east anglia coast uk extreme event analysis is performed to estimate climate change implication on inshore waves and the occurrence of extreme events it is shown for this coastal region that wave statistics are sensitive to the trend in sea level rise and that the climate change scenario leads to a significant increase of extreme wave heights in the northern part of the domain for nearshore points the increase of the mean sea level alters not only extreme wave heights but also the frequency of occurrence of extreme wave conditions

longitudinal variations of topside ionospheric and plasmaspheric tec the upward looking ionospheric total electron content tec from the metop a and tsx satellites during 2008 2015 has been used to systematically study the longitudinal variations of the topside ionosphere and plasmasphere the results of this study are summarized as follows 1 there are significant longitudinal variations in the topside ionosphere and plasmasphere at low latitudes the tec maximum during the june solstice over the western and central pacific ocean corresponds to a tec minimum at the same location during the december solstice but the opposite behavior occurs over south america and the atlantic ocean 2 during the solstices the relative longitudinal variations in the geomagnetic equatorial region do not have a strong dependence on local time and solar activity 3 the tec in the winter hemisphere decreases with increasing solar activity especially at higher altitudes and at night the topside tec depletion with solar activity depends on longitude 4 the solstice like longitudinal pattern lasts much longer than the equinox like patterns with the june solstice pattern lasting the longest furthermore the equinox like longitudinal patterns occur in march when expected whereas they extend from the autumnal equinox until the end of october 5 the longitudinal variations of upward looking tec are different from the corresponding longitudinal variations of electron densities around the f2 peak and orbital altitudes this indicates that the topside ionosphere structure is strongly influenced by the physical processes in the topside region rather than being a pure reflection of the ionospheric f2 peak structure

crab burrows as conduits for groundwater surface water exchange in bangladesh groundwater recharge affects water budgets and groundwater quality on the deltas and floodplains of south and southeast asia rain and flooding rivers recharge groundwater during the monsoon irrigated rice fields and surface water bodies recharge aquifers during the dry season groundwater throughout the region is severely contaminated by arsenic and recent research suggests that quantifying and characterizing recharge is important to understand whether recharge flushes or mobilizes arsenic from aquifers at a field site in bangladesh we found that burrows of terrestrial crabs short circuit low permeability surface sediments providing the primary conduit for recharge we combine field observations along with a model that couples isotope and water balances to quantify the effect of crab burrows on aquifer recharge given the wide distribution of burrowing crabs and the surficial geology we suggest that crab burrows provide widespread conduits for groundwater recharge

a simulation study of the equatorial ionospheric response to the october 2013 geomagnetic storm the ionospheric observation from ionosonde at sao luis 2 5 s 44 2 w 6 68 s dip latitude around the magnetic equator showed that the nighttime ionospheric f2 layer was uplifted by more than 150 km during the october 2013 geomagnetic storm the changes of the f2 peak height hmf2 at the magnetic equator were generally attributed to the variations of vertical drift associated with zonal electric fields in this paper the thermosphere ionosphere electrodynamics general circulation model tiegcm simulation results are utilized to explore the possible physical mechanisms responsible for the observed increase of hmf2 at sao luis the tiegcm generally reproduced the changes of f2 peak electron density nmf2 and its height hmf2 during the main and recovery phases of the october 2013 storm a series of controlled simulations revealed that storm time hmf2 changes at the magnetic equator are not purely associated with the changes of electric fields horizontal plasma transport due to meridional winds and thermospheric expansion also contributed significantly to the profound increase of nighttime hmf2 observed at sao luis on 2 october moreover the changes of meridional winds and neutral temperature in the equatorial region are associated with storm time travelling atmospheric disturbances originating from high latitudes

storm impacts and shoreline recovery mechanisms and controls in the southern north sea abstract storm impacts play a significant role in shoreline dynamics on barrier coastlines furthermore inter storm recovery is a key parameter determining long term coastal resilience to climate change storminess variability and sea level rise over the last decade four extreme storms with strong energetic waves and high still water levels resulting from high spring tides and large skew surge residuals have impacted the shoreline of the southern north sea the 5th december 2013 storm with the highest run up levels recorded in the last 60 years resulted in large sections of the frontline of the north norfolk coast being translated inland by over 10 m storms in march and november 2007 also generated barrier scarping and shoreline retreat although not on the scale of 2013 between 2008 and 2013 a calm period recovery dominated barrier position and elevation but was spatially differentiated alongshore for one study area scolt head island no recovery was seen this section of the coast is being reset episodically landwards during storms by contrast the study area at holkham bay showed considerable recovery between 2008 and 2013 with barrier sections developing seaward through foredune recovery the third study area brancaster bay showed partial recovery in barrier location and elevation results suggest that recovery is promoted by high sediment supply and onshore intertidal bar migration at rates of 40 m a 1 these processes bring sand to elevations where substrate drying enables aeolian processes to entrain and transport sand from upper foreshores to foredunes we identify three potential sediment transport pathways that create a region of positive diffusivity at holkham bay during calm periods a general westward movement of sediment from the drift divide at sheringham sources the intertidal bar and foredune development at holkham bay however during and following storms the drift switches to eastward not only on the beach itself but also below the 7 m isobath sediment from the eroding barrier at brancaster bay and especially scolt head island also sources the sediment sink of holkham bay knowledge of foredune growth and barrier recovery in natural systems are vital aspects of future coastal management planning with accelerated sea level rise and storminess variability

can sand dunes be used to study historic storm events knowing the long term frequency of high magnitude storm events that cause coastal inundation is critical for present coastal management especially in the context of rising sea levels and potentially increasing frequency and severity of storm events coastal sand dunes may provide a sedimentary archive of past storm events from which long term frequencies of large storms can be reconstructed this study uses novel portable optically stimulated luminescence posl profiles from coastal dunes to reconstruct the sedimentary archive of storm and surge activity for norfolk uk application of posl profiling with supporting luminescence ages and particle size analysis to coastal dunes provides not only information of dunefield evolution but also on past coastal storms in this study seven storm events two major were identified from the dune archive spanning the last 140 years these appear to correspond to historical reports of major storm surges dunes appear to be only recording at least at the sampling resolution used here the highest storm levels that were associated with significant flooding as such the approach seems to hold promise to obtain a better understanding of the frequency of large storms by extending the dune archive records further back to times when documentation of storm surges was sparse

tidal effects on sea water intrusion in unconfined aquifers abstract a variable density groundwater model is used to analyse the effects of tidal fluctuations on sea water intrusion in an unconfined aquifer it is shown that the tidal activity forces the sea water to intrude further inland and it also creates a thicker interface than would occur without tidal effects moreover the configuration of the interface is radically changed when the tidal fluctuations are included this is because of the dramatic changes in the flow pattern and velocity of the groundwater near the shoreline for aquifer depths much larger than tidal amplitudes the tidal fluctuation does not have much effect on how far the sea water intrudes into the aquifer nevertheless a significant change in the configuration of concentration contours because of the effect of tidal fluctuations is observed this change is more noticeable at the top of the aquifer near the water table than at the bottom of the aquifer and is caused by the infiltration of salt water into the top of the aquifer at higher tidal levels a flatter beach slope therefore intensifies this phenomenon the interface configurations do not change noticeably over the course of a tidal cycle neglecting tidal fluctuation effects results in an inaccurate evaluation of the water table elevation at the land end of the aquifer although no distinguishable difference is seen between the water tables near the shoreline where the landward boundary condition is a constant head the effects of tidal fluctuations on sea water intrusion are more pronounced than for cases where the landward boundary condition is a specified flux also it is shown that the effects of tidal fluctuations are more significant for a sloping beach than for a vertical shoreline and the salt water intrudes further inland for the sloping case

southern north sea storm surge event of 5 december 2013 water levels waves and coastal impacts the storm surge event that affected the coastal margins of the southern north sea on 5 6 december 2013 produced the highest still water levels on record at several tide gauges on the uk east coast on east facing coasts south of the humber estuary and north facing norfolk water levels were higher than in the twentieth century benchmark surge event of 31 january 1 february 1953 maximum significant wave heights were highest off the north norfolk coast peak hs 3 8 m offshore 2 9 m inshore and lowest off the suffolk coast hs 1 5 1 8 m inshore comparable offshore wave heights in 1953 were 7 8 m and ca 3 m the lower wave heights and their short duration in 2013 explain both localised breaching overtopping and back barrier flooding associated with gravel ridges and relatively low earthen banks as well as the lack of failure in more highly engineered coastal defences on barrier coasts and within estuaries the signal of maximum runup was highly variable reflecting the modification of the tide surge wave signal by inshore bathymetry and the presence of a range of coastal ecosystems the landscape impacts of the december 2013 surge included the notching of soft rock cliffs and cliffline retreat erosion of coastal dunes and the augmentation or re activation of barrier island washover deposits whilst surge event related cliff retreat on the rapidly eroding cliffs of the suffolk coast lay within the natural variability in inter annual rates of retreat the impact of the surge on upper beach sand dune margins produced a pulse of shoreline translation landwards equivalent to about 10 years of normal shoreline retreat the study of east coast surges over the last 60 years and the identification of significant phases of landscape change such as periods of rapid soft rock cliff retreat and the formation of new gravel washovers on barrier islands points to the importance of high water levels being accompanied by high wave activity future developments in early warning systems and evacuation planning require information on the variable impacts of such extreme events

a 150 year record of coastline dynamics within a sediment cell eastern england abstract coastal sediment cells reflect processes operating at a range of scales but it is the medium spatial and temporal scales decades to centuries that are of greatest interest for coastal management this paper focuses on coastline position change within a single sediment cell over 150 years where the geomorphology includes cliffs beaches and saltmarshes the focus is the east coast of england from flamborough head to gibraltar point although the updrift sector of this sediment cell has been studied for well over a century the downdrift sector has attracted significantly less attention using topographic profiles bathymetric profiles aerial photographs and historical maps we mapped coastline erosion and accretion using the digital shoreline analysis system dsas and calculated volumetric changes for different morphometric units rapid erosion of the updrift holderness cliffs has been counterbalanced with accretion on beaches along the downdrift lincolnshire coast the amount of accretion in lincolnshire corresponds to around 29 of the volume of sediment eroded from holderness much of the eroded cliff material is likely to be deposited temporarily into nearshore and offshore sand banks before being redistributed by cross shore currents an exploration of storm surge impact on long term erosion and accretion rates showed no clear relationship between storm surge frequency and change in coastline position however this may be in part due to the relative timing of storm occurrence and data acquisition the jenkinson daily weather type classification was found to be a reasonable proxy for the occurrence of strong onshore winds which may offer scope for further investigation of the role of forcing factors over time periods beyond the length of the meteorological and tidal station records winter north atlantic oscillation phase was not a good indicator of storminess on the east coast of england but may be a useful proxy for quiescence

observed mean sea level changes around the north sea coastline from 1800 to present this paper assesses historic changes in mean sea level around the coastline of the north sea one of the most densely populated coasts in the world typically such analyses have been conducted at a national level and detailed geographically wider analyses have not been undertaken for about 20 years we analyse long records up to 200 years from 30 tide gauge sites which are reasonably uniformly distributed along the coastline and 1 calculate relative sea level trends 2 examine the inter annual and decadal variations 3 estimate regional geocentric sometimes also referred to as absolute sea level rise throughout the 20th century and 4 assess the evidence for regional acceleration of sea level rise relative sea level changes are broadly consistent with known vertical land movement patterns the inter annual and decadal variability is partly coherent across the region but with some differences between the inner north sea and the english channel data sets from various sources are used to provide estimates of the geocentric sea level changes the long term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1 5 0 1 mm yr for the entire north sea region the trend is slightly higher for the inner north sea i e 1 6 0 1 mm yr and smaller but not significantly different on the 95 confidence level for the english channel i e 1 2 0 1 mm yr the uncertainties in the estimates of vertical land movement rates are still large and the results from a broad range of approaches for determining these rates are not consistent periods of sea level rise acceleration are detected at different times throughout the last 200 years and are to some extent related to air pressure variations the recent rates of sea level rise i e over the last two to three decades are high compared to the long term average but are comparable to those which have been observed at other times in the late 19th and 20th century

the gravity recovery and climate experiment mission overview and early results 1 the grace mission is designed to track changes in the earth s gravity field for a period of five years launched in march 2002 the two grace satellites have collected nearly two years of data a span of data available during the commissioning phase was used to obtain initial gravity models the gravity models developed with this data are more than an order of magnitude better at the long and mid wavelengths than previous models the error estimates indicate a 2 cm accuracy uniformly over the land and ocean regions a consequence of the highly accurate global and homogenous nature of the grace data these early results are a strong affirmation of the grace mission concept

the extreme 2013 2014 winter storms beach recovery along the southwest coast of england abstract sand and gravel beaches naturally act as a coastal buffer absorbing wave energy and dynamically adapting to the seasonal and long term wave climate significant shifts in nearshore morphology can occur during extreme wave events which can have a significant impact on coastal vulnerability during the winter of 2013 14 the atlantic coast of europe received an unprecedented sequence of very energetic wave conditions 8 week mean offshore h s 4 4 m these events caused extensive physical beach and dune erosion and socio economic flooding damage to infrastructure impacts throughout the west coast of europe many monitored sites in the uk and france were in their most eroded state since morphological records began 5 10 years we consider the geomorphological significance of the storm response at 38 natural beaches in the southwest of england ranging from semi sheltered reflective gravel barriers to ultra dissipative exposed sand beaches with dunes the extent and patterns of post storm recovery are examined in detail at three beaches with characteristic storm response behaviours exposed sandy beaches were dominated by cross shore transport processes leading to significant loss of sediment offshore from the intertidal zone 200 m 3 m exposed gravel beaches were dominated by overwash with significant loss landward and semi sheltered sites exposed to more oblique wave forcing were dominated by a rotational response due to alongshore sediment redistribution due to these contrasting responses mechanisms and timescales for beach recovery displayed strong inter site and intra site variations in offshore and rotational cases the recovery processes were multi annual comprising seasonal to decadal signals and were intrinsically linked to the storm response mechanisms while permanent losses occurred when overwash dominated we show that post storm recovery does not necessarily occur during calm periods and that in many cases high energy wave events appear to be essential for recovery of sediment offshore and counter rotation our results highlight the significance of dominant climatic oscillations multi annual storm sequencing storm tracks and resultant variations in wave angle in controlling the impact that extreme wave events have on contrasting sand gravel beaches in exposed sheltered locations

toarcian extreme warmth led to tropical cyclone intensification abstract models predict that tropical cyclone intensity should increase on a warming planet observing this relationship remains however a difficult task since no clear trend is yet emerging from the anthropogenic record the geological past offers the opportunity to study this relationship by looking at episodes of extreme warmth such as the toarcian oceanic anoxic event t oae early jurassic ca 181 ma in this study we document an increase in the occurrence of storm related deposits during the onset of the t oae in the tide dominated high atlas basin of morocco associated with a drastic deepening of the mean storm weather wave base the palaeolatitude of the high atlas basin 18 north during the early jurassic rules out winter storms as the driving mechanism behind the formation of these deposits and points to a dramatic intensification of tropical cyclone intensity during the t oae global warming these new results combined with the previously reported ubiquitous appearance of storm deposits during the t oae in tropical seas of the western tethyan area support the concept that the globally averaged intensity of tropical cyclones will increase in the coming century due to the anthropogenic climate change

hydrochemical and isotopical evidence of ground water salinization processes on the coastal plain of samborombon bay argentina summary salinization in coastal areas of the province of buenos aires argentina is a controlling factor of water quality and limits its exploitation for human uses and local ecological values coastal plains such as the one in the southern part of samborombon bay have a tidal morphology consisting of fine sediment deposits tidal channels and aeolian sand sheets each of them playing a hydrological role in this paper we describe the hydrological processes in the samborombon bay coastal plain using hydrochemical and isotopical data to provide evidence of salinization processes specific ionic relationships for surface and ground water samples from each formation are differ from those of sea water isotopic data also reveal infrequent participation of sea water in the coastal area water samples showing an evaporation trend in both surface and ground water we conclude that salinization has its origin in the occurrence of gypsum and halite as well as other chlorides from the coastal plain deposits rainfall recharge continental water inputs evaporation and long residence times define the hydrochemical and isotopical features of ground water which shows no signs of present sea water contribution sand sheets constitute local aquifers with lower salinity content continental surface waters as well as rainfall drainage via tidal channels have a dominant effect on surface water hydrochemistry notwithstanding tidal oscillations exploitation of water resources is thus limited to regionally extended aeolian sand sheet formations and to surface waters specifically those related to contributions of freshwater discharge from inland areas

a new analytical solution of tidal water table fluctuations in a coastal unconfined aquifer this paper presents a new perturbation solution of the non linear boussinesq equation for one dimensional tidal groundwater flow in a coastal unconfined aquifer built upon the work of parlange et at parlange j y stagnitti f starr j l braddock r d 1984 free surface flow in porous media and periodic solution of the shallow flow approximation j hydrol 70 251 263 the solution adopts a new perturbation parameter that is by definition less than unit and thus is applicable to a wider range of physical conditions within the constraint of the boussinesq approximation this approach avoids a secular term in the third order perturbation equation of parlange et at 1984 enabling the derivation of the third and higher order solutions in comparison with a numerical exact solution the new perturbation solution is shown to be slightly more accurate than that of parlange et at 1984 with the second order approximation the obtained third order solution exhibits considerable improvement in accuracy in relatively simple analytical forms the present perturbation solution will help to understand better the non linear characteristics of tidal water table fluctuations as modeled by the non linear boussinesq equation in coastal unconfined aquifers c 2007 elsevier b v all rights reserved

oceanographic processes and sediment mixing on a sand flat in an enclosed sea manukau harbour new zealand abstract studies of oceanographic and sedimentary processes on intertidal sand flats in an enclosed sea were undertaken to gain a better understanding of the factors controlling the mixing and dispersal of sediment bound contaminants field investigations included a 90 day process experiment during which wind waves tidal currents tides depth of disturbance and sand flat morphology were measured and 27 months of sand flat profile monitoring sediment entrainment by strong spring tidal currents is restricted to the middle and lower regions of the sand flat which are inundated during the peak tidal flows the upper 2 3 cm of sediment is re worked across the middle and upper sand flat by mild storm wave events h s 70 cm which occurred four times during the 90 day experiment numerous ridges and runnels in the upper sand flats are wave formed features and are maintained by the lack of currents of sufficient magnitude to re work the features the ridge and runnel morphology is testimony to large infrequent storm events which re work the sediment to depths of 20 cm such storms are an important mechanism for the release of contaminants and were recorded on 3 occasions in the 27 month profile record

response of wave dominated and mixed energy barriers to storms wave dominated and mixed energy barriers are extremely dynamic landforms responding to processes operating over a spectrum of time scales ranging from daily to monthly fluctuations related to storm and post storm conditions to century to millennium scale evolution driven by relative sea level change two types of storms are of particular relevance warm core tropical and cold core extratropical cyclones both are responsible for generating very large waves highly energetic surf zone dynamics and sediment transport elevated inshore water levels and extensive morphological responses all cyclones are affected by climate change which governs their frequency intensity and tracks barrier storm response is primarily governed by maximum storm runup and barrier morphology as conceptualised in abby sallenger s storm impact scale model sallenger 2000 this model defines four storm impact regimes and includes erosive as well as accretionary responses on the erosion side the swash regime drives bar and berm flattening the collision regime is marked by dune scarping and beach lowe the overwash regime leads to dune scouring and channel incision and the inundation regime may result in barrier destruction on the deposition side storm berms and beach ridges may form and accrete in the swash and collision regimes localised vertical beach and barrier accretion are associated with the collision and overwash regimes and washover deposition takes place in the overwash and inundation regimes site specific factors play a key role in moderating the morphological response and include storm characteristics type duration and track longshore sediment supply upwelling downwelling currents coastal setting and inner shelf topography the response of a barrier to a tropical or extratropical cyclone can however not be considered in isolation and has to be appreciated in a longer temporal context involving morphological preconditioning due to antecedent wave and water level conditions additionally a simple process response approach of the cause and effect type is inappropriate and a more complex conceptual framework involving thresholds feedbacks resilience and vulnerability will need to be adopted a useful way to visualise and conceptualise more complex storm behaviours and the longer term vulnerability of barriers is the resilience trajectory which maps out the changes in barrier geometry elevation and width over various time scales from weeks to years or even longer and under varying forcing conditions including changes in storminess and sea level rise an increased understanding of barrier response to storms and sequences of storms is required to better quantify long term barrier response to climate change high resolution and comprehensive decadal records of barrier response to storms are a prerequisite to achieve this ambition linking site specific coastal settings hydrodynamic drivers and morphological responses and allowing the recognition of recovery and impact dominated phases the enhanced insights in barrier response to extreme events must then be incorporated into improved coastal response models to help predict the impacts of future climate change on wave dominated and mixed energy barriers around the world 2013 elsevier b v

the role of paleochannels in groundwater seawater exchange relict fluvial channels that are infilled with high permeability sediments act as preferred pathways for groundwater flow and solute transport in coastal regions such paleochannels can provide a hydraulic connection between freshwater aquifers and the sea facilitating saltwater intrusion landward or freshwater discharge offshore although paleochannels have been implicated in several instances of saltwater intrusion there has been little direct study of these channels to confirm their role in this work simulation modeling of a general multi layered coastal plain aquifer setting indicates that when a paleochannel breaches a confining unit offshore submarine groundwater discharge of intermediate salinity occurs this discharge is largely concentrated along the margins of the channel conversely seawater inflow occurs along the channel axis resulting in higher salinity in the middle of the channel relative to the flanks chirp seismic and electromagnetic data collected offshore wrightsville beach nc usa confirm these simulation results and indicate fresher porewater along channel flanks and slightly higher porewater salinity along the channel axis hence paleochannels contribute to the spatial variability in submarine groundwater discharge by serving as conduits of focused fluid exchange simulations also reveal that the freshwater saltwater transition zone is closer to land below paleochannels than in locations with a continuous confining unit this indicates that such channels are likely to be significant modes of saltwater intrusion into confined aquifers when excess freshwater extraction occurs on land

understanding spatio temporal barrier dynamics through the use of multiple shoreline proxies abstract at the coast risk arises where and when static human developments are situated within dynamic surroundings barrier islands are often sites of heightened coastal risk since they frequently support substantial human populations and undergo extensive morphological change owing to their low lying form and persistence in energetic hydrodynamic and meteorological conditions using the mixed sand gravel barrier of blakeney point this study argues that to avoid an only partial understanding of coastal zone processes it is necessary to make use of multiple shoreline proxies capturing processes operating both at different timescales and different cross shore positions here five shoreline proxies were extracted from three data sources shoreline error was quantified and compared to observed shoreline change rates to establish proxy specific appropriate timescales for shoreline change analysis the map derived mean high water line at blakeney point revealed landward retreat of 0 61 m a 1 over the past 130 years with a shift from drift towards swash alignment of the barrier since 1981 over the past 24 years the high water line ridge line and vegetation line reveal proxy specific response to management regime change the termination of barrier reprofiling of the eastern section of the barrier has resulted in increased sediment release to the downdrift barrier terminus buffering retreat there at the expense of the updrift section the vegetation line represents an effective proxy for storm driven overwash with maximum shoreline retreat during surge events of 172 m illustrating a strong event driven component to barrier morphodynamics by comparison to the other proxies the lidar light detection and ranging derived mean high water line offers relatively limited insights into barrier dynamics emphasising the importance of multi proxy approaches in the face of technological advance we demonstrate the continued importance of critical attention towards the dependencies that exist between shoreline proxy selection and the processes that can be observed as a result

was magnetic storm the only driver of the long duration enhancements of daytime total electron content in the asian australian sector between 7 and 12 september 2017

nature based flood protection the efficiency of vegetated foreshores for reducing wave loads on coastal dikes this paper analyses the effect of vegetation on wave damping under severe storm conditions based on a combination of field measurements and numerical modelling the field measurements of wave attenuation by vegetation were performed on two salt marshes with two representative but contrasting coastal wetland vegetation types cordgrass spartina anglica and grassweed scirpus maritimus the former is found in salty environments whereas the latter is found in brackish environments the measurements have added to the range with the highest water depths and wave heights presented in the literature so far a numerical wave model swan has been calibrated and validated using the new field data it appeared that the model was well capable of reproducing the observed decay in wave height over the salt marsh the model has been applied to compute the reduction of the incident wave height on a dike for various realistic foreshore configurations and hydraulic loading conditions additionally the efficiency of vegetated foreshores in reducing wave loads on the dike has been investigated where wave loads were quantified using a computed wave run up height and wave overtopping discharge the outcomes show that vegetated foreshores reduce wave loads on coastal dikes significantly also for the large inundation depths that occur during storms and with the vegetation being in winter state the effect of the foreshore on the wave loads varies with wave height to water depth ratio on the foreshore the presence of vegetation on the foreshore extends the range of water depths for which a foreshore can be applied for effective reduction of wave loads and prevents intense wave breaking on the foreshore to occur this research demonstrates that vegetated foreshores can be considered as a promising supplement to conventional engineering methods for dike reinforcement

evidence for the sediment circulation along the coast of east anglia abstract mccave 1978 suggested that based on sediment budget considerations and coarsening of sand size away from cliff sources the nesses on the east anglian coast of england are sites where sediment is lost to the shoreline this view is directly opposed to that of robinson 1966 1980 who believed that material reached the beach from offshore at nesses largely through the effect of residual currents the present paper examines these two opposing views mainly in the light of recent data from the easton bavents aldeburgh area of east anglia it is concluded that neither argument is proven although it is more probable that nesses are places where sediment is lost from the foreshore rather than gained from offshore the variability of trends between one ness and another and at different sites offshore implies that generalisations may not be valid

sediment supply and barrier dynamics as driving mechanisms of holocene coastal change for the southern north sea basin the combined effects of climate change and human impact lead to regional and local coastal responses that pose major challenges for the future resilience of coastal landscapes increasing the vulnerability of communities infrastructure and nature conservation interests using the suffolk coast southeast england as a case study we investigate the importance of sediment supply and barrier dynamics as driving mechanisms of coastal change throughout the holocene litho bio and chronostratigraphic methods are used to decipher the mechanisms of coastal change from the record preserved within coastal stratigraphy results suggest that local coastal configuration and sediment supply were the most influential in determining coastal change during the mid and late holocene against a background control of sea level rise the importance of sedimentological and morphological factors in shaping holocene coastal changes in the southern north sea basin must therefore be considered when using the database of evidence from this region as an analogue for future change under accelerated sea level rise

sea level changes river activity soil development and glaciation around the western margins of the southern north sea basin during the early and early middle pleistocene evidence from pakefield suffolk uk this paper outlines evidence from pakefield northern suffolk eastern england for sea level changes river activity soil development and glaciation during the late early and early mid dle pleistocene mis 20 12 within the western margins of the southern north sea basin during this time period the area consisted of a low lying coastal plain and a shallow offshore shelf the area was drained by major river systems including the thames and bytham changes in sea level caused sev eral major transgressive regressive cycles across this low relief region and these changes are identi fied by the stratigraphic relationship between shallow marine wroxham crag formation fluvial cromer forest bed and bytham formations and glacial happisburgh and lowestoft formations sediments two separate glaciations are recognised the happisburgh mis 16 and anglian mis 12 glaciations and these are separated by a high sea level represented by a new member of the wroxham crag formation and several phases of river aggradation and incision the principal driving mechanism behind sea level changes and river terrace development within the region during this time period is solar insolation operating over 100 kyr eccentricity cycles this effect is achieved by the impact of cold climate processes upon coastal river and glacial systems and these climatically forced processes obscure the neotectonic drivers that operated over this period of time british geological survey natural environment research council copyright 2005 reproduced with the permission of bgs nerc published by john wiley sons ltd

role of stratigraphy in governing pore water seepage from salt marsh sediments 1 numerical modeling experiments have been used to study the effects of marsh stratigraphy on the seepage of pore water into tidal channels if the mud sand contact lies at the elevation of the channel bottom and the hydraulic conductivity of the basal sand is at least an order of magnitude greater than the overlying mud the locus of maximum seepage shifts from the tide line as in a purely mud marsh to the toe of the creek bank the ratio of creek bank seepage to bottom seepage also shifts from greater than to less than one furthermore as the ratio of the hydraulic conductivities of sand to mud increases the ratio of the total seepage from the sand mud marsh to that from a pure mud marsh increases in a nonlinear fashion reaching an asymptotic limit of about 20 at a conductivity ratio of about 1000 if the mud sand boundary is progressively lowered so that mud also lies beneath the channel the seepage dynamics gradually revert toward those of a purely mud marsh the ecological implications of these results for regularly flooded low marshes are discussed

influence of the geologic and geomorphologic characteristics and of crab burrows on the interrelation between surface water and groundwater in an estuarine coastal wetland the interrelation between surface water and groundwater in intertidal flats is often studied through mathematical models in many cases these models need to be supported by an integral analysis of the geologic geomorphologic hydrologic and biological characteristics of the environment that are to be obtained from field surveys the marshy environment of the river ajo in the samborombon bay wetland argentina is a typical example of an estuarine coastal zone geologic and geomorphologic surveys were carried out as well as measurements of surface water and groundwater level changes as a response of the aquifer to tidal forcing the banks of the river ajo are either scarped with storm flats or mildly sloped with intertidal flats and numerous crab burrows sediments are mainly silty clayey with low permeability and lie over silty sandy layers at the erosion scarps the tidal wave enters the aquifer as a sub horizontal flow through the pore space of the sediments the tidal range in the aquifer depends on the lithological characteristics of the sediments and on the side changes of their hydraulic conductivity the rise of the water table at high water and its subsequent fall are nearly sinusoidal with a period similar to that of the tide at the river at the intertidal flats instead the tidal wave enters the aquifer mainly as a sub vertical flow through the crab burrows as the crab burrows are not interconnected they are not distinct pathways for preferential flow therefore the groundwater flux into the river is very slow during low water and the recovery of the water table takes a long time the tidal influence upon the water table on both kinds of banks affects only a narrow strip of the aquifer not only are the characteristics of the marshy environment of the river ajo representative of most of the samborombon bay wetland they can also be extended to other similar coastal wetlands to help preserve these invaluable environments

late holocene vertical land motion and relative sea level changes lessons from the british isles vertical land motion caused by continuing glacial isostatic adjustment is one of several important components of sea level change and is not limited just to previously glaciated regions a national scale analysis for the british isles shows an ellipse of present day relative uplift relative sea level fall 1 2 mm a 1 broadly centred on the deglaciated mountains of scotland the pattern of three foci of relative subsidence 1 mm a 1 results from the additional interactions of the deglacial meltwater load on the atlantic basin and the continental shelf and the signal due to far field ice sheets at a local scale sediment compaction can more than double the rate of relative land subsidence relative land level change the negative of relative sea level change is not the same as vertical land motion there is a spatial pattern in the difference between relative land level change and vertical land motion with differences at present of approximately 0 1 to 0 3 mm a 1 around the british isles and 2 5 to 1 5 mm a 1 globally for the wider scientific and user community whether or not the differences are considered significant will depend upon the location time frame and spatial scale of the study that uses such information copyright 2011 john wiley sons ltd

assessment of beach and dune erosion and accretion using lidar impact of the stormy 2013 14 winter and longer term trends on the sefton coast uk abstract an important question for coastal management concerns the importance of individual storms and clusters of storms on longer term beach sediment budgets beach and dune erosion and coastal flood risk between october 2013 and march 2014 a series of deep atlantic low pressure systems crossed the northeast atlantic and strong winds high waves and high water levels affected many coastal areas in the uk and other parts of western europe net dune recession of up to 12 1 m occurred around formby point on 5 december 2013 the highest water level ever recorded at liverpool 6 22 m odn coincided with waves of hs of 4 55 m and tp of 9 3 s in liverpool bay wave trimming of the dune toe occurred along the entire length of the sefton coast but significant dune erosion occurred only where the upper beach between the mean high water spring tide level and the dune toe was

morphodynamic behaviour of a nearshore sandbank system the great yarmouth sandbanks u k offshore sandbanks provide a major source of sediment and may have a significant impact on the evolution of the nearby shoreline the prediction of sandbank evolution is extremely important for coastal engineers and managers however it is evident from the existing literature that additional investigations into the evolution of offshore sandbanks are needed the present paper describes qualitative and quantitative investigations of the evolution of the great yarmouth sandbanks a depth integrated tidal model has been used to calculate the residual currents arising from the sequence of sandbank configurations observed from historic charts over a 150 year period tidal simulations were performed with a nested model covering the southern north sea and great yarmouth zone east coast of the uk simulations were carried out for a period corresponding to several spring neap cycles to calculate residual currents and were compared directly with field measurements model calibration and validation was performed against published tidal elevation charts based on many observations tidal predictions and field measurements these detailed comparisons have been used to determine the errors in the model predictions overall the performance of the model is considered good the model output has been analysed to investigate qualitative links between the sandbank configuration and the residual flow statistics the results demonstrate that the long term changes in sandbank morphology can be explained from the pattern of tidal residual currents

holocene land and sea level changes in great britain analysis of more than 1200 radiocarbon dated samples that constrain relative sea levels in great britain over the past 16 000 yr provides estimates of current land level changes negative of relative sea level change maximum relative land uplift occurs in central and western scotland ca 1 6 mm yr 1 and maximum subsidence is in southwest england ca 1 2 mm yr 1 sediment consolidation arising from autocompaction as the sediment accumulates and from land drainage increases the subsidence in areas with thick sequences of holocene sediments with an average effect equivalent to at least an extra ca 0 2 mm yr 1 land subsidence but more in parts of southeast england 0 5 1 1 mm yr 1 modelled changes in tidal range during the mid to late holocene in eastern england suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified the effect is most significant for large coastal lowlands the fenland and humber ca 0 5 and 0 6 mm yr 1 that were tidal embayments during the mid to late holocene

laboratory investigation of coastal beach erosion processes under storm waves of slowly varying height abstact storm induced large coastal waves are a predominant driver for coastal erosion problems but the physical processes of storm erosion have not been fully understood due to some technical difficulty in simulating storm waves with timely varying heights in the laboratory and collecting storm beach profiles in the field in this study novel series of experiments are proposed to study sandy beach processes under coastal storm conditions in a laboratory wave flume of 60 m long 3 m wide and 1 5 m high two water depths of h 0 5 m and h 0 7 m were used to investigate beach response under low and high tidal levels two initially uniform plane beach slopes of tan 1 15 for dissipation beach and tan 1 5 for reflection beach were used to study beach profile changes additionally intermediate beach tan 1 10 was also experimentally investigated under regular waves in another wave flume of 30 m long 0 6 m wide and 1 m high non intrusive instrumentation of high resolution cameras was used to record time series photo images on beach profile evolution in spatial resolution of 0 2 cm and a temporal resolution of 0 1 s image analyzing techniques were also developed to transform the recorded photo images to digital data on both beach and water surface profiles in analyzing the collected data it is found that the variation of storm wave height results in changes of wave breaking point and also sediment transport direction before and after the wave breaking point sediment transport direction was found to move onshore initially under small storm waves and then a sand bar was generated and a certain portion of sediment also moved offshore under large waves but such monotonic relationship between sediment transport and wave forcing could transform as morphology feedback and phase lags between wave orbital fluid velocity and sediment concentration the wave energy flux at the breaking point is shown to be suitable parameter in predicting beach mass change or storm erosion rate while the dimensionless sediment settling velocity parameter may not be a suitable criterion for predicting beach erosion or accretion under storm waves

interaction between continental and estuarine waters in the wetlands of the northern coastal plain of samborombon bay argentina on the samborombon bay coastline located in the rio de la plata estuary in buenos aires province argentina a complex hydrological system has developed at the interface between continental and estuarine water where significant wetlands develop the main hydrogeological units namely the shell ridges the tidal plain and the marsh areas have been identified using geomorphological criteria water table hydrochemical and isotopic data have been used to determine their hydrological features as well as those of the streams and canals evaporation processes in particular have been considered when depicting chemical and isotopic changes in surface waters in streams and marsh areas the shell ridges represent a hydrogeological unit in which rainwater is stored constituting a lens shaped freshwater aquifer in this unit just as in the tidal plain carbonate dissolution and ion exchange are the main processes regulating water chemistry on the other hand in the marsh and surface waters processes such as mixing with estuarine water and evaporation predominate these processes control water fluxes and the salinity of the wetland areas and consequently their ability to preserve the existing biodiversity this study shows the importance of knowledge of hydrochemical processes in any proposal concerning the management and preservation of this type of wetland

a preliminary study of thermosphere and mesosphere wind observed by fabry perot over kelan china a fabry perot interferometer fpi system was deployed in kelan 38 7 n 111 6 e center china in november 2011 which observes the airglows at wavelengths of 892 0 nm 557 7 nm and 630 0 nm from oh and oi emissions in the upper atmosphere to derive the wind and temperature at heights around 87 km 97 km and 250 km respectively from late 2011 through 2013 a series of more than 4500 measurements at each height are validated according to manufacture data quality criteria by using these data the morphology of wind in the mesosphere and thermosphere is investigated in this study preliminary results are as follows 1 as for the diurnal variation meridional and zonal winds at heights of 87 km and 97 km which are derived through 892 0 nm and 557 7 nm airglows usually range from 50 m s to 30 m s and 50 m s to 50 m s respectively with typical random errors of about 6 10 m s at 87 km and 2 3 m s at 97 km meridional winds usually are northward at dusk southward at middle night and back to northward at dawn and zonal winds usually are eastward at dusk westward at middle night and back to eastward at dawn the monthly mean winds are in good agreement with those of hwm93 results meridional and zonal winds at a height of 250 km which are derived through 630 0 nm nightglow range from 110 m s to 80 m s with typical random errors of about 8 10 m s meridional winds usually are northward at dusk southward at middle night and back to northward at dawn and zonal winds usually are eastward at dusk zero at middle night and westward at dawn and they are also well consistent with hwm93 results 2 as for the seasonal variation meridional winds at the heights of 87 km and 97 km have a visible annual variation at 12 17 lt and with a little semiannual variation at all other hours but the zonal winds at the heights of 87 km and 97 km have a semiannual variation all night the seasonal dependence of the winds both meridional and zonal winds at the height of 250 km is generally annual but isolated cases of semiannual variation are observed 3 the horizontal winds at 250 km evidently respond to the two storms of july 2012 apparent enhancement of the velocity of the southwestward wind but no other obvious storm effects can be found from the winds at 87 km and 97 km during the same period