the southeast indian ridge between 88 e and 118 e variations in crustal accretion at constant spreading rate the temperature of the mantle and the rate of melt production are parameters which play important roles in controlling the style of crustal accretion along mid ocean ridges to investigate the variability in crustal accretion that develops in response to variations in mantle temperature we have conducted a geophysical investigation of the southeast indian ridge seir between the amsterdam hotspot and the australian antarctic discordance 88 e 118 e the spreading center deepens by 2100 m from west to east within the study area despite a uniform intermediate spreading rate 69 75 mm yr 1 the seir exhibits the range in axial morphology displayed by the east pacific rise and the mid atlantic ridge mar and usually associated with variations in spreading rate the spreading center is characterized by an axial high west of 102 45 e whereas an axial valley is prevalent east of this longitude both the deepening of the ridge axis and the general evolution of axial morphology from an axial high to a rift valley are not uniform a region of intermediate morphology separates axial highs and mar like rift valleys local transitions in axial morphology occur in three areas along the ridge axis the increase in axial depth toward the australian antarctic discordance may be explained by the thinning of the oceanic crust by 4 km and the change in axial topography the long wavelength changes observed along the seir can be attributed to a gradient in mantle temperature between regions influenced by the amsterdam and kerguelen hot spots and the australian antarctic discordance however local processes perhaps associated with an heterogeneous mantle or along axis asthenospheric flow may give rise to local transitions in axial topography and depth anomalies

normal faulting and the topographic roughness of mid ocean ridge flanks the ocean floor on the flanks of mid ocean ridges is covered by abyssal hills topographic features elongated perpendicularly to the direction of relative plate motion these topographic features are interpreted as normal fault blocks and or volcanic constructions that originated near the ridge axis and were later rafted onto the ridge flanks by seafloor spreading the purpose of this paper is to quantify the topographic roughness of a profile perpendicular to the strike of a number of normal faults given a fault population and a mechanical model for the response of the lithosphere to faulting we obtain expressions for the variation in root mean square roughness with profile length and for the power spectral density of a profile given three parameters a fault density number of faults per unit length crossed by the profile an average squared fault scarp height and a characteristic length of flexure to keep matters simple we make a number of assumptions and approximations namely that the lithosphere behaves as an elastic plate that faults have an infinite length and a vertical dip that the response of topography to a number of faults is simply the sum of the responses to each fault and that faults have random locations and scarp heights independently chosen from some statistical distribution the theory predicts that the roughness length relationship power spectral density should follow power laws for scales wavelengths less than a characteristic scale proportional to the length scale of flexure we compare the predictions of the theory with actual measurements of mid ocean ridge flank roughness and find good first order agreement in particular we use independent estimates of fault densities average squared fault scarp heights and flexural length scales to predict the topographic roughness of the east pacific rise and we find that normal faulting can explain all the observed topographic roughness nevertheless there are some differences between predictions and observations these differences are likely to be due to processes other than faulting that create topographic relief e g volcanism and to spatial correlations of fault scarp heights despite these shortcomings the approach presented here provides a first step in understanding the topographic roughness signal by quantifying the contribution of the geological processes that generate surface relief

comparison of ground water flow model particle tracking results and isotopic data in the mojave river ground water basin southern california usa abstract flow path and time of travel results for the mojave river ground water basin southern california calculated using the ground water flow model modflow and particle tracking model modpath were similar to flow path and time of travel interpretations derived from delta deuterium and carbon 14 data model and isotopic data both show short flow paths and young ground water ages throughout the floodplain aquifer along most the mojave river longer flow paths and older ground water ages as great as 10 000 years before present were measured and simulated in the floodplain aquifer near the mojave valley model and isotopic data also show movement of water between the floodplain and regional aquifer and subsequent discharge of water from the river to dry lakes in some areas it was not possible to simulate the isotopic composition of ground water in the regional aquifer away from the front of the san gabriel and san bernardino mountains because recharge in these areas does not occur under the present day climatic conditions used for calibration of the model

direct measurements of floodwater infiltration into shallow alluvial aquifers the relationship between floodwater infiltration and groundwater recharge of a shallow alluvial aquifer in a hyper arid desert was studied in the arava valley israel the study implemented an experimental system that simultaneously monitors all three hydrological domains controlling the recharge process 1 floodwater stages on land surface 2 water content variations in the deep vadose zone and 3 groundwater response to the infiltration this experimental system makes use of a new technique for installing flexible time domain reflectometry probes for continuous monitoring of the vadose zone moisture profiles water infiltration was monitored in controlled infiltration experiments and during a natural flood the monitoring setup allowed real time tracking of the wetting front propagation velocities and assessment of water fluxes through the vadose zone the results revealed a complex infiltration process that includes matrix and preferential flow together with lateral flow

historic and ancient tsunamis uncovered on the jalisco colima pacific coast the mexican subduction zone research on extreme wave events such as tsunamis using the geological record in areas of infrequent and or small magnitude earthquakes can aid in extending the long term history and recurrence intervals of large events this information is valuable for risk management and community preparedness in coastal areas here we investigate tsunami deposits on the jalisco coast of mexico that overlies the subducting rivera plate under the north american plate an area due for a large thrust earthquake and potential tsunami here we apply a full battery of rock magnetic analyses that also include a detailed ams study and other typically applied proxies in tsunami deposits research we present evidence to demonstrate that anomalous sand units with sharp basal contacts at la manzanilla tenacatita bay and el tecuan shore sites on the jalisco coast may be the products of tsunamis generated by known historical ms 8 2 earthquake of 3 june 1932 and other earlier tsunamigenic earthquakes a sandy unit with a sharp basal contact flame structures at the base rip up clasts at la manzanilla and four sand units with sharp basal contact overlying buried soils at el tecuan together with other proxies such as magnetic properties and others suggest tsunami deposits 210pb dating of sediments slightly above the upper sand layer indicate an age a d 1935 11 at el tecuan historical accounts of tsunami inundation at both sites provide further evidence that this is most probably the result of the 3 june 1932 tsunami hence this study may provide the first evidence of a tsunami triggered by this earthquake and also of three probable predecessors further evidence of at least three earlier tsunamis that occurred since the fifteenth century is also evident in the stratigraphy these events may correspond to events listed in historical archives namely the 1563 1816 and or the 1818 events

using multiple environmental proxies and hydrodynamic modeling to investigate late holocene climate and coastal change within a large gulf of mexico estuarine system mobile bay alabama usa abstract a high degree of uncertainty exists for understanding and predicting coastal estuarine response to changing climate land use and sea level conditions leaving geologic records as a best proxy for constraining potential outcomes with the majority of the world s population focused in coastal regions understanding how local systems respond to global regional and even local pressures is key in developing mitigation adaptation and management plans the geomorphology of mobile bay in southeast alabama usa has evolved considerably e g bayhead delta back stepping over the late holocene in response to global and regional sea level and climate change smaller scale geomorphic changes e g spit and beach ridge development have also had a significant influence on the evolution of the estuary organic matter characteristics inorganic sediment geochemistry benthic microfossils and pollen in a 3500 cal yr bp sediment sequence recovered in a gravity core 20gc from bon secour bay a small sub bay in the southeast corner of mobile bay record time varying marine influence increases in marine influence during 3500 to 2300 cal yr bp and 1930 to 1160 cal yr bp are defined as zones with high density and pre dominantly calcareous foraminiferal species abundant sand 10 and more marine like geochemical signatures which contrast the low density and pre dominantly agglutinated foraminiferal and more terrestrially influenced estuarine muds observed in other intervals of the sedimentary record 2300 1930 and 1160 400 cal yr bp and the modern bay hydrodynamic models constrained by geomorphic boundary conditions for the time 3500 cal yr bp consistent with the most prominent marine influenced sediment provide insight to potential coastal configuration that might have permitted such marine water intrusion into the bay of several scenarios evaluated a breach in morgan peninsula produces tidal circulation within the basin supportive of persistent marine incursions in the bay between 3500 to 2300 cal yr bp the findings show that slight variations in coastal configuration can have broad scale effects on bays and estuaries with consequences that may relate to water quality vertebrate and invertebrate habitat and coastal vulnerability to episodic events like extra tropical storms

hurricane records on the south carolina coast can they be detected in the sediment record abstract more than 40 short cores were collected from 10 localities in the myrtle beach to mcclellandville coastline of south carolina the localities were selected on the basis of whether or not they should have a well preserved record of recent hurricanes most notably hugo which occurred in september 1989 of the 40 cores collected results from two sites are presented here as examples price s inlet a non tidal intra beach ridge area which was directly in the path of the eyewall of hugo and sandpiper pond which is a coastal non tidal pond near murrells inlet about 50 75 km north of where the main landfall of hurricane hugo but still in the area of high storm surge these cores were analyzed for percentage organic carbon visual observations x rays and microfossils the microfossils were used to differentiate marine non marine sequences in the non tidal inlets and identify reworked sediments by means of displaced benthic foraminifera cores were dated using pb 210 techniques that provide resolution for the last 100 yr in price s inlet the hugo effect was most pronounced with an 8 cm thick sand layer containing many nearshore foraminifera showing transport from offshore in sandpiper pond we could see the trace of hugo from the offshore foraminifera contained in sediments sandwiched between the freshwater intervals both before and after hugo however there was little detectable trace in the x rays or sedimentology of this core to indicate a storm event hence we can recognize a range of responses for hurricanes in the form of different types of sediment layers and microfossil assemblages in these non tidal areas depending on where the impact point is on the coast here we are able to distinguish at least two types of signals from the same storm which has significant implications for detecting these events in the pre historic record and determining their paleo periodicity

sediments deposited by the 2004 indian ocean tsunami along the malaysia thailand peninsula stratigraphy grain size distribution and foraminiferal assemblages of pre tsunami and tsunami sediment from the indian ocean tsunami at five sites along the malaysia thailand peninsula were analyzed to gain information on tsunami sediment source and deposition style between three and five stratigraphic units were identified at each site and contained between one and three fining upward sequences reflecting waning flow or pre backwash deposition coarser sand layers reflecting uprush high energy flow separated the fining upward sequences with the exception of one site sungai burong which contained a coarsening upward sequence all contacts between the pre tsunami and tsunami sediment were sharp or erosional medium and coarse sand dominated all of the tsunami sediment deposits and often contained shell fragments foraminiferal assemblages were able to differentiate pre tsunami sediment from tsunami sediment where no lithological or grain size distribution change was evident between two and four foraminiferal zones were identified at each of the five sites and provided estimates of sediment source and wave characteristics

tracing groundwater components by chemical isotopic and physical parameters example schinznach switzerland dissolved ions stable and radioactive isotopes and physical data obtained from hydrologically related samples may be processed as anonym and as specific tracers answers are obtained to questions pertaining to the number and proportions of inter mixing water types the properties of each end member its recharge altitude depth of circulation nature of the rocks passed and mode of flow the methodology of the data processing is demonstrated on observations made over one year on a spring and a well at the spa of schinznach switzerland two end members are identified 1 warm 39 c saline up to 85 meq l 1 total dissolved ions circulating at a depth of over 640 m and passing through gypsum anhydrite and halite bearing rocks and 2 colder 21 2 c fresher 30 meq l 1 total dissolved ions circulating at a depth of 240 m passing through a sequence of gypsum anhydrite bearing carbonate rocks and flowing in a karstic mode both water types are recharged at an average altitude of 550 100 m a s l a value used in identifying the recharge area the existence of a separate hotter water body at greater depth is possible

anthropogenic controls on overwash deposition evidence and consequences accelerated sea level rise and the potential for an increase in frequency of the most intense hurricanes due to climate change threaten the vitality and habitability of barrier islands by lowering their relative elevation and altering frequency of overwash high density development may further increase island vulnerability by restricting delivery of overwash to the subaerial island we analyzed pre hurricane sandy and post hurricane sandy 2012 lidar surveys of the new jersey coast to assess human influence on barrier overwash comparing natural environments to two developed environments commercial and residential using shore perpendicular topographic profiles the volumes of overwash delivered to residential and commercial environments are reduced by 40 and 90 respectively of that delivered to natural environments we use this analysis and an exploratory barrier island evolution model to assess long term impacts of anthropogenic structures simulations suggest that natural barrier islands may persist under a range of likely future sea level rise scenarios 7 13 mm yr whereas developed barrier islands will have a long term tendency toward drowning

the importance of extratropical and tropical cyclones on the short term evolution of barrier islands along the northern gulf of mexico usa abstract data are presented indicating the complexity and highly variable response of beaches to cold front passages along the northern gulf of mexico in addition to the impacts of tropical cyclones and winter storms within the past decade an increase in the frequency of tropical storms and hurricanes impacting the northern gulf has dramatically altered the long term equilibrium of a large portion of this coast a time series of net sediment flux for subaerial and nearshore environments has been established for a section of this coast in florida and to a lesser extent mississippi the data incorporate the morphological signature of six tropical storms hurricanes and more than 200 frontal passages data indicate that 1 barrier islands can conserve mass during catastrophic hurricanes e g hurricane opal a strong category 4 hurricane near landfall 2 less severe hurricanes and tropical storms can promote rapid dune aggradation and can contribute sediment to the entire barrier system 3 cold fronts play a critical role in the poststorm adjustment of the barrier by deflating the subaerial portion of the overwash terrace and eroding its marginal lobe along the bayside beach through locally generated high frequency steep waves and 4 barrier systems along the northern gulf do not necessarily enter an immediate poststorm recovery phase although nested in sediment rich nearshore environments while high wave energy conditions associated with cold fronts play an integral role in the evolution and maintenance of barriers along the northern gulf these events are more effective in reworking sediment after the occurrence of extreme events such as hurricanes this relationship is even more apparent during the clustering of tropical cyclones it is anticipated that these findings will have important implications for the longer term evolution of barrier systems in midlatitude microtidal settings where the clustering of storms is apparent and winter storms are significant in intensity and frequency along the coast

evaluating the recharge mechanism of the lower kuiseb dune area using mixing cell modeling and residence time data summary a mixing cell approach was extended by a method incorporating mean cell residence times derived from 14c to further constrain and validate the modeling results this extended approach was used to model the groundwater system of the lower kuiseb dune area in namibia the kuiseb river is a 560 km long ephemeral river that crosses the namib desert from east to west transmission losses from the riverbed during flood events are an important source of groundwater recharge to the underlying aquifer system the lower kuiseb area is located in a hyper arid region with annual precipitation less than 25 mm yr hydrochemical data from 13 wells in the area were used in the mixing cell model mcm end members were identified as sources for the groundwater found in the lower kuiseb including inflow from the crystalline basement plateau north of the kuiseb as well as floodwater from the kuiseb river a conceptual groundwater recharge and flow model was developed and then inverse mixing cell modeling was carried out using hydrochemical tracers this approach generally allows for several possible solutions after completing the inverse modeling a forward mixing cell model was developed by varying the mean residence time of each cell to fit calculated 14c data to the measured 14c data this new approach joins previously developed methods solely based on conservative mixing or residence time optimization based on the results of the model the fraction of floodwater in different sections of the lower kuiseb groundwater systems was calculated ranging from 61 to 98 2 in addition to floodwater groundwater inflow from the crystalline basement north of the kuiseb was shown to contribute to the lower kuiseb aquifer accounting for salinization during periods without flooding

factors responsible for the limited inland extent of sand deposits on leyte island during 2013 typhoon haiyan previous geological studies suggest that the maximum inland extent of storm induced sand deposits is shorter but their thickness is larger than those of tsunami induced sand deposits however factors that determine the maximum extent and thickness of storm deposits are still uncertain we conducted numerical simulations of storm surge waves and sediment transport during typhoon haiyan in order to understand the distribution and sedimentary processes responsible for storm deposits numerical results showed that wave induced currents slightly offshore were strong but attenuated rapidly in the inland direction after wave breaking therefore sediments were not transported far inland by waves and storm surge consequently the maximum inland extent of storm deposits was remarkably shorter than the inland extent of inundation we also revealed that vegetation roughness coefficient and typhoon intensity greatly affect the calculation of maximum extent and thickness distribution of storm deposits as the duration of wave impact on a coast is relatively long during a storm hours compared to minutes for a tsunami sediments are repeatedly supplied by multiple waves therefore storm deposits tend to be thicker than tsunami deposits and multiple layers can form in the internal sedimentary structure of the deposits we infer that limitation of the sand deposit to within only a short distance inland from the shoreline and multiple layers found in a deposit can be used as appropriate identification proxies for storm deposits

lake sediment record of late holocene hurricane activities from coastal alabama coastal lake sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late holocene time frederic a category 3 hurricane that struck the alabama coast on the gulf of mexico in 1979 left a distinct sand layer in the nearshore sediments of lake shelby as a result of storm tide overwash of beaches and dunes sediment cores taken from the center of lake shelby contain multiple sand layers suggesting that major hurricanes of category 4 or 5 intensity directly struck the alabama coast at ca 3 2 3 0 2 6 2 2 1 4 and 0 8 ka 14 c yr with an average recurrence interval of 600 yr the alabama coast is likely to be struck by a category 4 or 5 hurricane within the next century

faulting patterns near 19 30 s on the east pacific rise fault formation and growth at a superfast spreading center 1 structural mapping from high resolution sonar and bathymetric data collected near 19 30 s on the southern east pacific rise epr reveals multiple packets of small closely spaced outward dipping faults that form antithetic to larger inward dipping faults the mean spacing and height of inward dipping scarps are 1 6 and 1 9 times greater than those of outward dipping faults and the median spacing and height of inward dipping scarps are 2 0 and 1 7 times greater respectively accordingly inward dipping faults are less abundant 35 45 but accommodate more 50 55 of the roughly 4 0 strain although previous studies have shown that epr fault populations exhibit exponential size frequency distributions one dimensional throw and spacing data from the 19 30 s region are not described well by this model the first major 40 m scarp height fault is observed within 1 4 km of the ridge crest and invariably dips inward further off axis a transition from greater inward dipping to greater outward dipping fault abundance constrains the minimum half width of the active plate boundary zone to be 5 15 km inspection of additional data sets from 16 and 18 30 s indicates a pattern of large inward dipping faults with associated hanging wall deformation similar to that observed in the 19 30 s region this pattern is distinct from the horst and graben morphology observed along the fast spreading northern epr the pervasive hanging wall deformation observed on the flanks of the southern epr suggests master fault geometries that are more sharply curved or kinked at depth relative to their abyssal hill equivalents on the northern epr boundary element modeling indicates the pattern and geometry of faulting observed along the southern epr is consistent with fault nucleation above a shallow sill like magma chamber with internal overpressure since the influence of the sill on fault growth is strongly dependent on the depth of the sill the different patterns of faulting observed along the northern and southern epr may reflect the small difference in axial magma chamber depth between these two regions with a slightly shallower chamber beneath the southern epr

chenier plain development in northern sierra leone west africa abstract the coast of northern sierra leone between the scarcies and mellacoree estuaries forms a prograding muddy holocene plain comprising two separate as yet undated clusters of sand cheniers the general coastal morpho stratigraphy and available data on regional climatic and sealevel history suggest that alternations between muddy progradation and chenier cluster formation have been controlled by a probable conjunction of several factors including the local geomorphic framework a climatically induced change in mud supply and relative sealevel oscillations since the middle holocene the inner chenier cluster was apparently elaborated under conditions of efficient wave action over a deep largely unfilled mellacoree estuary and at a time of reduced mud availability it peters out seaward probably in response to several factors including an increase in mud supply from the upland a negative sealevel pulse resulting in higher rates of mud export from accreted inner tidal flats increased muddy sedimentation over a shallower nearshore zone and attenuated wave action as a result of energy capture by accreted estuarine shoals the outer cluster which partly fringes the coast was formed in a mayor embayment representing the terminus of longshore sand drift it is suggested that its formation may have been favoured by a higher sealevel resulting in efficient winnowing of sands from subtidal muds a greater propensity for accretion of tidal flats landwards and consequently a lower mud supply to the foreshore although the timing of muddy progradation and chenier formation has not been determined the foregoing interpretation suggests a complex sequence of events reflecting as much the influence of local morphodynamic factors as external factors

a backbarrier overwash record of intense storms from brigantine new jersey abstract analysis of aerial photographs and historic charts indicates that the barrier beach at brigantine nj has migrated landward 300 to 400 m since 1869 primarily as a result of overwash during hurricanes and winter storms a series of vibracores from the backbarrier salt marsh reveals a millennial scale stratigraphic record of overwash deposition carbon 14 c 14 and cesium 137 cs 137 radioisotopic methods were used to date overwash deposits washovers the ages of recent washovers are consistent with deposition during intense storms in 1938 1944 1950 and 1962 an additional overwash deposit recovered in five of the sediment cores was likely deposited by an intense hurricane strike in 1821 or possibly in 1788 two prehistoric overwash fans were likely deposited by intense storms striking the new jersey coast in the 7th to 14th centuries and 6th to 7th centuries a d the landward barrier migration indicates that the older overwash sediments were likely transported a considerably greater distance than the more recent overwash fans the greater distance of transport may indicate that the prehistoric storms that deposited overwash fans across the study site were more intense than the most intense storm to strike this coast in the historic period the hurricane of 1821 the spatially variable occurrence of overwash deposition at this site points to a need for multisite stratigraphic surveys of extensive stretches of the coast in order to develop reliable records of past intense storm frequency from backbarrier environments

sediment transport due to extreme events the hudson river estuary after tropical storms irene and lee 1 tropical storms irene and lee in 2011 produced intense precipitation and flooding in the u s northeast including the hudson river watershed sediment input to the hudson river was approximately 2 7 megaton about 5 times the long term annual average rather than the common assumption that sediment is predominantly trapped in the estuary observations and model results indicate that approximately two thirds of the new sediment remained trapped in the tidal freshwater river more than 1 month after the storms and only about one fifth of the new sediment reached the saline estuary high sediment concentrations were observed in the estuary but the model results suggest that this was predominantly due to remobilization of bed sediment spatially localized deposits of new and remobilized sediment were consistent with longer term depositional records the results indicate that tidal rivers can intercept at least temporarily delivery of terrigenous sediment to the marine environment during major flow events

magnitude of hurricane ike storm surge sedimentation implications for coastal marsh aggradation there is a paucity of information on the regional distribution and magnitude of hurricane storm surge sedimentation this study assesses the spatial extent and magnitude of hurricane ike s 2008 storm surge sedimentation and discusses implications for the role of hurricanes in marsh aggradation the characteristics of the storm surge deposit including thickness inland penetration volume and mass were determined for 15 transects across marshes bordering the gulf of mexico in south eastern texas and south western louisiana the deposit is up to 0 85 m thick extends up to 3 6 km inland and has an estimated volume of about 13 7 million m3 and an estimated mass of about 16 2 million metric tons this level of sedimentation is one to two orders of magnitude larger than other potential sources of marsh sedimentation including annual riverine inputs and inputs from alongshore sediment transport the study findings add support to a growing body of evidence that hurricanes may be the predominant sediment source for long term aggradation of many coastal marshes bordering the gulf of mexico copyright 2012 john wiley sons ltd

source conveyance and fate of suspended sediments following hurricane irene new england usa hurricane irene passed directly over the connecticut river valley in late august 2011 intense precipitation and high antecedent soil moisture resulted in record flooding mass wasting and fluvial erosion allowing for observations of how these rare but significant extreme events affect a landscape still responding to pleistocene glaciation and associated sediment emplacement clays and silts from upland glacial deposits once suspended in the stream network were routed directly to the mouth of the connecticut river resulting in record breaking sediment loads fifteen times greater than predicted from the pre existing rating curve denudation was particularly extensive in mountainous areas we calculate that sediment yield during the event from the deerfield river a steep tributary comprising 5 of the entire connecticut river watershed exceeded at minimum 10 40 years of routine sediment discharge and accounted for approximately 40 of the total event sediment discharge from the connecticut river a seriesof surface sediment corestaken in floodplainponds adjacent to the tidalsec

a compartmental mixing cell approach for the quantitative assessment of groundwater dynamics in the otway basin south australia abstract transient groundwater fluxes as calculated by a groundwater flow model modflow are used as input into a compartmental mixing cell cmc model to simulate the transport of hydrochemical and isotopic species in regional groundwater systems good agreement between modeled and measured concentrations of solutes in groundwater provides greater confidence in estimating aquifer parameters for the flow model the cmc model is currently developed for multi layered groundwater systems and allows for both recharge to the uppermost aquifer and upward or downward leakage between individual aquifers the combination of the cmc approach and modflow allows chemical and hydraulic data to be analysed simultaneously to allow for improved conceptualization of the groundwater system the use of transient fluxes reflects the temporal scale and variability of the chemical tracers as well as the temporal variability of hydraulic conditions the model is applied to a transect in the gambier embayment of the otway basin in south australia to quantify mixing between two main aquifer systems this groundwater system is hydraulically connected to the ocean in the west and as a result would have been affected by sea level changes over the last 30 000 yr radiocarbon simulations helped to quantify a major zone of downward leakage to the confined aquifer with modeled rates of leakage ranging 2 9 mm yr

trends in research on beaches and dunes on sandy shores 1969 2019 abstract trends in research on morphologic changes on beaches and foredunes on sandy shores are identified from the 1960s to the present research during this period evolved from early descriptive explanation and classification of profile change to instrumented field investigations to modelling of landform change at larger scales research efforts have become increasingly more collaborative with increasing use of field instrumentation data acquisition systems and remote sensing rich datasets are resulting in more comprehensive computational models human altered systems are of increasing interest but knowledge of these systems lags far behind knowledge of natural systems research is becoming more relevant to societal needs as the vulnerability of coastal populations increases the need for investigation of understudied or unexplored environments including human altered ones is ongoing many basic research issues remain but future studies would profit from the development of new models rather than validating or reconfiguring old models collaboration between geomorphologists and engineers may open up research opportunities particularly in modifying beaches and dunes built for shore protection to provide natural values in restricted space application of models to enhance knowledge of effects of sea level rise and coastal storms would be useful to managers developing resiliency plans

definition of groundwater flow patterns by environmental tracers in the multiple aquifer system of southern arava valley israel abstract the present paper describes a model for identification and semi quantitative evaluation of the different water bodies replenishing groundwater in the southern arava rift valley the potential sources of recharge into the alluvial aquifer of the valley were assessed by multivariable cluster analysis of environmental tracers such as dissolved ions and stable isotopes this data was also used to determine the flow pattern to the valley and within its alluvial aquifer to the natural outlet of the red sea spatial variations in the chemical compositions of groundwater and of their isotopic ratios are explained as the result of differential rates of replenishment of various water bodies flowing to the arava the alluvial aquifer of the southern arava valley is recharged by the following water bodies 1 lateral subsurface flow caused by infiltration of water from flash floods occurring in the neighbouring mountain massifs 2 upward and lateral groundwater flow from sandstone and carbonate aquifers in the negev and edom mountains and 3 leakage from deep seated brine reservoirs a complete groundwater flow pattern based upon hydrological hydrochemical and isotopic data is presented in a compartmental configuration

community infrastructure and repository for marine magnetic identifications magnetic anomaly identifications underpin plate tectonic reconstructions and form the primary data set from which the age of the oceanic lithosphere and seafloor spreading regimes in the ocean basins can be determined although these identifications are an invaluable resource their usefulness to the wider scientific community has been limited due to the lack of a central community infrastructure to organize host and update these interpretations we have developed an open source community driven online infrastructure as a repository for quality checked magnetic anomaly identifications from all ocean basins we provide a global sample data set that comprises 96 733 individually picked magnetic anomaly identifications organized by ocean basin and publication reference and provide accompanying hellingerformat files where available our infrastructure is designed to facilitate research in plate tectonic reconstructions or research that relies on an assessment of plate reconstructions for both experts and nonexperts alike to further enhance the existing repository and strengthen its value we encourage others in the community to contribute to this effort

the sedimentary record of the 2005 hurricane season from the mississippi and alabama coastlines abstract the instrumental record of hurricane activity is too short to fully capture the occurrence of the rare but most destructive hurricanes therefore obtaining a record of present and past landfalling hurricanes and their extent of geological and ecological impacts is one means to assess future risk reveal the spatial and temporal variability of hurricane activity and decipher its relationship with global climatic changes we rapidly dispatched survey teams to collect the readily available but perishable data of hurricanes katrina and rita storm surge from two salt marshes in mississippi and one salt marsh in alabama in mississippi we recorded hurricane katrina storm surge heights greater than 7 5 m north american vertical datum 88 navd88 with inland extents in excess of 700 m whereas in alabama the maximum recorded storm surge was 3 43 m navd88 at one salt marsh in mississippi we recorded the maximum inland extent and elevation of maximum penetration of hurricane rita as 370 m and 3 43 m navd88 respectively we observed a three dimensional distribution of hurricane induced storm surge deposits that tapered landward overlying salt marsh sediment there was a sharp or erosional boundary between the pre storm surge and storm surge sedimentary units which was accompanied by a change in color and lithology the overlying storm surge sediment unit was coarser than the pre storm surge unit with a lower organic content the thickness of the hurricanes katrina and rita storm surge sediments ranged from 9 to 13 cm and approximately 7 cm respectively foraminiferal analyses revealed a virtual absence of tests within the storm surge sediments whereas abundant agglutinated foraminifera were found in the underlying salt marsh deposits

the holocene transgression into the estuarine central basin of the odiel river mouth cadig gulf sw spain lithology and faunal assemblages abstract six estuarine facies were distinguished recording the holocene history of sea level rise relating according to the start and development of the holocene transgression which flooded the coast of huelva facies 2 gravels facies 3 grey clayey silts facies 5 well sorted sands facies 4 silty sands facies 5 black clayey silts and facies 6 red muds this group overlies neogene sediments facies 1 three faunal assemblages open bay ob central estuary ce and wave domination wd including remains of macrofauna foraminifers and ostracods plus depositional features are identified in a sedimentological log constructed from a borehole with a continuous core sunk in the central basin of the odiel river estuary huela coast sw spain the ob assemblage requires shallow and protected zones controlled by low energy tidal currents the ce assemblage is located within an intertidal zone where reworked marine forms of foraminifers ostracods and scattered macrofauna co exist with small estuarine foraminifers and ostracods the wd assemblage comprises tests of marine macrofauna with fractured shells plus large marine foraminifers and estuarine ostracods during the first stage of continuous sea level rise 8720 260 bp to 5390 155 bp estuarine accretion high energy tidal currents and wave action took place successively allowing the development of the ob ce and wd assemblages the second stage 5390 155 bp to present with a stabilized sea level comprised a vertical decrease of energy with tidal currents favouring deposition in shallow tidal channels and marsh zones leading to less energetic ce assemblages within the estuarine central basin high sediment supply resulted in deposition during this stage which shows a regressive nature

foraminifera as an indicator of overwash deposits barrier island sediment supply and barrier island evolution folly island south carolina abstract micropaleontological analysis of four vibracores from back barrier marshes of folly island south carolina detected intervals of storm deposited sediment individual washover intervals were not detectable from lithology alone but only in conjunction with associated foraminifera washovers contained more modern offshore and oligo miocene genera and total calcareous foraminifera than background marsh samples the presence of tertiary foraminifera in the back barrier cores from folly island supports the hypothesis that much of the sediment for barrier island migration is derived from offshore foraminiferal analyses of back barrier cores were also used to calculate relative bioturbation rates by the method of officer and lynch officer c b lynch d r 1983 mixing sedimentation rates and age dating for sediment cores mar geol 46 261 278 eqs 10 14 in all cores the current depositional environment correlated well with the expected mixing parameter g the highest mixing parameter greatest signal attenuation was recorded in a core from a low marsh creek side environment whereas the lowest mixing parameter least smearing of signal was recorded in a high marsh core

quantitative assessment of the flow pattern in the southern arava valley israel by environmental tracers and a mixing cell model abstract this paper demonstrates the implementation of a novel mathematical model to quantify subsurface inflows from various sources into the arid alluvial basin of the southern arava valley divided between israel and jordan the model is based on spatial distribution of environmental tracers and is aimed for use on basins with complex hydrogeological structure and or with scarce physical hydrologic information however a sufficient qualified number of wells and springs are required to allow water sampling for chemical and isotopic analyses environmental tracers are used in a multivariable cluster analysis to define potential sources of recharge and also to delimit homogeneous mixing compartments within the modeled aquifer six mixing cells were identified based on 13 constituents a quantitative assessment of 11 significant subsurface inflows was obtained results revealed that the total recharge into the southern arava basin is around 12 52 10 6 m 3 year 1 the major source of inflow into the alluvial aquifer is from the nubian sandstone aquifer which comprises 65 75 of the total recharge only 19 24 of the recharge but the most important source of fresh water originates over the eastern jordanian mountains and alluvial fans

multi variable mixing cell model as a calibration and validation tool for hydrogeologic groundwater modeling abstract agricultural irrigation can make substantial changes to groundwater systems this study focuses on an arid area in northern nevada where 100 yr of extensive irrigation has occurred in particular the impacts of long term agricultural activities on the groundwater fluid balance geochemistry and potential changes to the water quality of a nearby river were investigated the study conducted in the fernley basin in western nevada utilized two different modeling approaches to construct a conceptual model that honors both the chemical and physical aspects of the basin groundwater flow regime a multi variable mixing cell model was constructed to represent the hydrochemical approach while a modflow model was constructed to represent the hydrogeological model a geochemical and isotopic analysis of the basin and its margin groundwater was conducted to identify all of the water sources that potentially flow through the basin and all water bodies within the basin those water bodies and sources were incorporated into a mixing cell model that allowed delineation of the general flow lines connecting the different water bodies within the basin with their sources the mixing cell model results were used to calibrate the hydrogeological model until a general agreement between the flow lines of both models was achieved the calibration of the hydrogeologic model included adjustments of the hydraulic conductivities and the use of various interpolation methods the study showed that parallel application of two different modeling approaches the mixing cell model along with a hydrogeological model provides an excellent tool for the validation of the conceptual model moreover it allowed calibration of the hydrogeologic model not only to the water heads as usually done in hydrogeological models but also to the general flow lines that honors the basin geochemistry

interplay between faults and lava flows in construction of the upper oceanic crust the east pacific rise crest 9 25 9 58 n the distribution of faults and fault characteristics along the east pacific rise epr crest between 9 25 n and 9 58 n were studied using high resolution side scan sonar data and near bottom bathymetric profiles the resulting analysis shows important variations in the density of deformational features and tectonic strain estimates at young seafloor relative to older sediment covered seafloor of the same spreading age we estimate that the expression of tectonic deformation and associated strain on old seafloor is 5 times greater than that on young seafloor owing to the frequent fault burial by recent lava flows thus the unseen volcanically overprinted tectonic deformation may contribute from 30 to 100 of the 300 m of subsidence required to fully build up the extrusive pile layer 2a many longer lava flows greater than 1 km dam against inward facing fault scarps this limits their length at distances of 1 2 km which are coincident with where the extrusive layer acquires its full thickness more than 2 of plate separation at the epr is accommodated by brittle deformation which consists mainly of inward facing faults 70 faulting at the epr crest occurs within the narrow 4 km wide upper crust that behaves as a brittle lid overlying the axial magma chamber deformation at greater distances off axis up to 40 km is accommodated by flexure of the lithosphere due to thermal subsidence resulting in 50 inward facing faults accommodating 50 of the strain on the basis of observed burial of faults by lava flows and damming of flows by fault scarps we find that the development of layer 2a is strongly controlled by low relief growth faults that form at the ridge crest and its upper flanks in turn those faults have a profound impact on how lava flows are distributed along and across the ridge crest

600 year sedimentary archive of hurricane strikes in a prograding beach ridge plain southwestern louisiana abstract this study tests a novel approach to paleotempestology substituting the lateral time depth of a prograding beach ridge plain for the vertical time depth of an aggrading coastal lake pond lagoon swamp or marsh trenching and coring of a beach ridge plain in southwestern louisiana revealed six sand beds and one shell bed interpreted as hurricane washover deposits the sand beds are readily distinguished from enclosing marsh sediments by their higher sand content lower organic content and contrasting microfossil assemblages based on the modern analogs of hurricanes audrey 1957 rita 2005 and ike 2008 and consideration of nearby landfalling hurricanes in the historical record it was determined that the storm intensity threshold of the study site is equivalent to a category 3 hurricane there is a wide variation in hurricane strike frequency between this site and other sites bordering the gulf of mexico this variation results from differences in site sensitivity and the nature of geologic or geochemical proxies used to derive hurricane strike records the approach demonstrated by this study could have applicability at other sites around the world where beach ridge plains are subject to tropical cyclone strikes

reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern florida from lake sediment records abstract sediment cores from western lake provide a 7000 yr record of coastal environmental changes and catastrophic hurricane landfalls along the gulf coast of the florida panhandle using hurricane opal as a modern analog we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity few catastrophic hurricanes struck the western lake area during two quiescent periods 3400 5000 and 0 1000 14 c yr b p the landfall probabilities increased dramatically to ca 0 5 per yr during an hyperactive period from 1000 3400 14 c yr b p especially in the first millennium a d the millennial scale variability in catastrophic hurricane landfalls along the gulf coast is probably controlled by shifts in the position of the jet stream and the bermuda high

sea level and storm control on the evolution of a chenier plain firth of thames new zealand abstract geological controls on the evolution of the miranda chenier plain firth of thames new zealand are investigated using high resolution stratigraphic information obtained from geophysical surveys two previous studies of the miranda chenier plain have provided disparate conceptual models of its development over the holocene one study evokes sea level oscillations to form individual cheniers while the other offers an alternate model based on the observed transgression of the modern chenier both studies agree that sea level has dropped between 4000 and 1000 years bp but the elevation of the highstand and nature of the fall are contentious this paper extends previous interpretations using data obtained from ground penetrating radar surveys and historical aerial photographs stratigraphic interpretation of the continuous high resolution sub surface radar data was used to infer a sea level curve for miranda these data enable four new inferences 1 sea level fell from 2 m around 4000 years ago mid holocene highstand to present about 1000 years ago 2 falling sea level influenced chenier spacing with the onset of alongshore rather than across shore chenier plain development coinciding with the termination of sea level fall after the formation of ridge six 3 all cheniers initially transgressed producing similar resultant spit morphologies but the evolution of the more recent ridges 1 5 differed from older ridges 6 13 in that transgression occurred over embayed tidal flat sediments while the older cheniers stabilized on foreshore mudflats and 4 storms exert an important control in initiating chenier genesis the miranda chenier plain is a site of global significance for understanding chenier evolution in this study the high level of subsurface detail unimagined in past decades presents greater insight into the morphology and stratigraphy of the chenier ridges shedding new light on the role of sea level and storms on the evolution of the plain

estimation of spatial recharge distribution using environmental isotopes and hydrochemical data ii application to aravaipa valley in southern arizona u s a abstract in part i a mathematical model was developed to estimate the spatial distribution of annual recharge rates into an aquifer using environmental isotopes and hydrochemical data in part ii the model is applied to real data from the aravaipa valley in southern arizona these data suffer from a paucity of hydrologic information but contain numerous isotopic and hydrochemical analyses the model is able to extract from the available data both qualitative and quantitative information about recharge into and flow through the shallow unconfined aquifer in the valley the model shows that this aquifer is replenished primarily by lateral recharge from the pediments and the tributary stowe gulch basin as well as by upward leakage from the underlying confined aquifer recharge from the aravaipa creek is relatively minor lateral recharge from the eastern pediments into the unconfined aquifer exceeds that from the western pediments by a factor of two the western pediments are a major source of recharge for the confined aquifer these results are tentative because independent means to verify them are currently lacking we are encouraged however that the mass balance errors of water and dissolved constituents do not exceed 4 and that the flow rate obtained from darcy s law at one location within the unconfined aquifer in which transmissivity is known agrees with model prediction while chemical reactions are ignored in the model some of the isotopic and chemical species show sufficient spatial variability due to mixing to justify the approach this is supported by analyses of equilibrium water mineral interactions conducted by wateqf

crestal overtop and washover sedimentation on a fringing sandy gravel barrier coast carnsore point southeast ireland abstract storm sedimentation on a fringing sandy gravel barrier system in southeast ireland is examined recent wave overtopping and overwashing during severe onshore storms have resulted in a distinctive pattern of crest and backbarrier sedimentation this is not easily matched with available models of washover sedimentation drawn from the barrier islands of the eastern united states beach crest overtopping occurs at heights up to 6 m mhws and is related to the development of upper beach swash ramps that are plastered against storm wave eroded dune scarps located at the barrier crest ramp sediments comprise coarse basal beach gravels overlain by coarsening upward units and finally topped by distinctive seawarddipping fine grit coarse sand couplets in places where ramps reach the dune cre t overtopping swash has deposited a fine marine gravel veneer

the effect of tides and storms on the sediment transport across a dutch barrier island under natural conditions barrier islands might grow vertically and migrate onshore under the influence of long term sea level rise sediment is transported onshore during storm induced overwash and inundation however on many dutch wadden islands dune openings are closed off by artificial sand drift dikes that prevent the influx of sediment during storms it has been argued that creating openings in the dune row to allow regular flooding on barrier islands can have a positive effect on the sediment budget but the dominant hydrodynamic processes and their influence on sediment transport during overwash and inundation are unknown here we present an xbeach model study to investigate how sediment transport during overwash and inundation across the beach of a typical mesotidal wadden sea barrier island is influenced by wave tide and storm surge conditions firstly we validated the model xbeach with field data on waves and currents during island inundation in general the xbeach modelperformed well secondly we studied the long term sediment transport across the barrier island we distinguished six representative inundation classes ranging from frequently occurring low energy events to infrequent high energy events and simulated the hydrodynamics and sediment transport during these events an analysis of the model simulations shows that larger storm events cause larger cross shore sediment transport but the net sediment exchange during a storm levels off or even becomes smaller for the largest inundation classes because it is counteracted by larger mean water levels in the wadden sea that oppose or even reverse sediment transport during inundation when taking into account the frequency of occurrence of storms we concludethat the cumulative effect of relatively mild storms on long term cross shore sediment transport is much larger than that of the large storm events

storms and shoreline configuration abstract spectral analysis of the 1962 great atlantic coast storm penetration overwash along the outer banks of north carolina and fenwick island maryland reveals along the coast periodicities ranging in wavelength from 14 km to 15 km periodicities with similar wavelengths exist in long term mean rates of change of the shoreline and storm surge penetration line this suggests the location and magnitude of storm deposits and storm hazards along the atlantic coast are systematically distributed

erosional and depositional characteristics of regional overwash deposits caused by multiple hurricanes regional scale washover deposits along the florida gulf and atlantic coasts induced by multiple hurricanes in 2004 and 2005 were studied through coring trenching ground penetrating radar imaging aerial photography and prestorm and poststorm beach profile surveys erosional and depositional characteristics in different barrier island sub environments including dune field interior wetland and back barrier bay were examined over the eroded dune fields the washover deposits are characterized by an extensive horizontal basal erosional surface truncating the old dune deposits and horizontal to slightly landward dipping stratification over the marshes in the barrier island interior the washover deposits are characterized by steep tabular bedding with no erosion at the bottom overwash into the back barrier bay produced the thickest deposits characterized by steep prograding sigmoidal bedding no significant erosional feature was observed at the bottom washover deposits within the dense interior mangrove swamp demonstrate both normal and reversed graded bedding the washover deposits caused by hurricanes frances 2004 and jeanne 2004 along the southern florida atlantic coast barrier islands are substantially different from those along the northern florida barrier islands caused by ivan 2004 and dennis 2005 in terms of regional extension erosional features and sedimentary structures these differences are controlled by different overall barrier island morphology vegetation type and density and sediment properties the homogeneity of sediment along the northern florida coast makes distinguishing between washover deposits from ivan and dennis difficult in contrast along the atlantic coast barrier islands the two overwash events as demonstrated by two phases of graded bedding of the bimodal sediments are easily distinguishable

an unusual holocene fan shaped subaqueous prograding body at the back of the cies islands ridge ria de vigo nw spain geomorphology facies and stratigraphic architecture abstract the internal structure of a new subaqueous sedimentary body with a 3d morphology of a fan was studied using an interdisciplinary approach based on geophysical geomorphological sedimentological and radiocarbon data the genesis of the sedimentary body is controlled by two main factors 1 the presence of a basement ridge that constitutes the cies archipelago acting as a barrier that protects the ria from high energy marine events and 2 the w sw swell direction under stormy conditions which sweeps the sediment from the platform and introduces it into the ria through the narrow entrance between faro and san martino islands the sedimentary body that has grown inside the ria under low energy conditions progrades in a landward direction from the shelf to the ria sedimentological analysis indicates that the facies associations are coarse grained bioclastics in the proximal areas of this body changing laterally to mixed fine grained sediment in its distal parts the combination of geophysical and radiocarbon data leads us to establish the beginning of the progradation of the sedimentary body subsequent to the younger dryas cold event associated with the holocene sea level rise the seismic analysis of the high resolution seismic records allows us to recognize five main clinoform sets inside the subaqueous prograding sedimentary body which can be attributed to sea level changes during the holocene

off axis volcanism at the east pacific rise detected by uranium series dating of basalts recent detailed surveys of the east pacific rise have revealed the complexity of the volcanic and magmatic processes occurring along and across fast spreading ocean ridge crests1 7 in parallel with geological and geochemical investigations it is now possible to investigate the temporal and spatial pattern of volcanism at ocean ridges by dating young basalts using mass spectrometric uranium series disequilibria methods8 11 here we use 238u 230th and235u 231pa ages for basalts to quantify the spatial extent of young volcanism and crustal accretion at 9 31 n on the east pacific rise most of the ages are younger than would be expected based on off axis distance and spreading rate we infer from these anomalously young ages that most of the dated basalts on the crestal plateau were erupted 0 5 2 km outside the axial summit caldera with some volcanism occurring as far as 4 km off axis melts erupted outside the axial summit caldera can have crustal residence times and magmatic supply systems that differ from those of axial lavas

contrasting styles of hurricane irene washover sedimentation on three east coast barrier islands cape lookout north carolina assateague island virginia and fire island new york abstract storm surge and wind driven waves generated by hurricane irene which made landfall on the u s east coast on august 27 2011 resulted in overwash of sandy barrier islands from north carolina to new york state overwash has significant impacts on barrier island geomorphology it represents a sediment pathway into island interiors a component of island sediment budgets and can cause considerable aggradation of backshore surfaces important for potentially offsetting the effects of rising sea level this study describes the morphology texture and microfossil content of hurricane irene washover deposits at three contrasting barrier island sites cape lookout north carolina assateague island virginia and fire island new york at all three sites run up overwash occurred wherein waves were sufficient to overtop parts of the beach system and transport sediment inland however at fire island overwash was restricted by a higher elevational threshold to low spots in the beach system coinciding with pre existing breaches in foredunes the result was the formation of isolated thinner low volume washover fans at assateague island and cape lookout lower elevational thresholds allowed waves to overtop longer continuous sections of beach systems resulting in the formation of laterally continuous thicker larger volume washover terraces overall the deposits lacked consistent trends in thickness and texture such as thinning and fining inland reflecting a progressive reduction in overwash competence thickness and texture of the deposits were both spatially variable and probably reflect infilling of low points on the former surface and the influence of beach and foredune sediment sources all the washover deposits were essentially barren of foraminiferal microfossils supporting the textural evidence that the adjacent beach and foredunes were the predominant sediment sources

a hydrogeological and hydrochemical explanation of the groundwater composition under irrigated land in a mediterranean environment algarve portugal in the campina de faro in the south of portugal agricultural practices have a large impact on groundwater composition these practices involve pumping of water for irrigation from combinations of large diameter shallow wells noras and small diameter deep boreholes furos excess irrigation water returns to the aquifer and mixes with water from the regional groundwater flow system this irrigation return flow is concentrated by strong evapotranspiration and by flushing of fertilisers the concentration increase induces cation exchange whereby ca on the soil exchanger is replaced by na the mixing in the aquifer allows application of a mixing cell model which may then be used to calculate transmissivities from the cl mass balance the calculations are complicated by the time variant behaviour of cl and the method is adjusted to calculate the change of chloride in time results from the calculations appear to be in good agreement with hydrochemical observations

quantification of groundwater recharge in the city of nottingham uk groundwater is an important and valuable resource for water supply to cities in order to make full and wise use of the asset value a clear understanding of the quantities and sources of urban groundwater recharge is needed the water supply and disposal network is often an important source of recharge to urban groundwater through leakage from water mains and sewers an approach to establishing the spatial and temporal amounts of the three urban recharge sources precipitation mains and sewers is developed and illustrated using the nottingham uk urban aquifer a calibrated groundwater flow model is supplemented by calibrated solute balances for three conservative species cl so4 and total n thus providing four lines of evidence to use in the recharge estimation nottingham is located on a triassic sandstone aquifer with average precipitation of 700 mm year using the models current urban recharge is estimated to be 211 mm year of which 138 mm year 40 is from mains leakage and 10 mm year 100 is from sewer leakage the wide confidence intervals result from the scarcity of historical field data and the long turnover time in this high volume aquifer and should be significantly lower for many other aquifer systems

the efficacy of stream power and flow duration on geomorphic responses to catastrophic flooding abstract geomorphologists have long studied the impacts of extreme floods yet the association between the magnitude of flow parameters discharge velocity shear stress or stream power and resulting geomorphic effectiveness remains vague and non deterministic attempts have been made to include flow duration and total expenditure of stream power in combination with peak unit stream power as important variables but there has been minimal exploration of this hydraulic combination taking advantage of tropical storm irene s rapid track through eastern vermont usa in late summer 2011 this paper presents the array of geomorphic responses to a short duration time to peak of

lidar time series analysis of a rapidly transgressing low lying mainland barrier caminada headlands louisiana usa abstract coastal barriers are the first line of defense against storm surge and wind wave induced hazards their response to such events therefore require continual assessment airborne lidar surveying is a valuable remote sensing technique used to assess the dynamics of coastal dunes driven by the impacts of storms and the subsequent recovery processes different from previous research conducted on this topic where pre and post storm surveys are employed to analyze the effects of isolated extreme events this study makes use of a 15 year lidar survey time series of the caminada moreau headlands the caminada moreau headlands located in louisiana usa on the gulf of mexico s northern coast is a low gradient low elevation mainland barrier which is rapidly eroding due to sediment deprivation alongshore sediment transport relative sea level rise and cumulative storm impacts the time period analyzed from 1998 to 2013 was notable for the number and intensity of hurricanes and tropical storms making landfall in the region the analyses of the lidar data show that while storms have frequently overwashed and destroyed the dunes natural dune recovery has managed to maintain a nearly stable alongshore averaged dune volume on the other hand change in dune crest elevation in the most vulnerable stretches of the coastline has not kept pace with sea level rise the analyses herein further suggest that for low elevation dunes which rapidly transition into backbarrier wetlands the relative quantity of subaerial land surface area to open water directly landward of the duneline is an influential parameter affecting barrier shoreline morphodynamics

proxy records of holocene storm events in coastal barrier systems storm wave induced markers abstract extreme storm events in the coastal zone are one of the main forcing agents of short term coastal system behavior as such storms represent a major threat to human activities concentrated along the coasts worldwide in order to better understand the frequency of extreme events like storms climate science must rely on longer time records than the century scale records of instrumental weather data proxy records of storm wave or storm wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia this review provides a detailed state of the art compilation of the proxies available from coastal barrier systems to reconstruct holocene storm chronologies paleotempestology the present paper aims i to describe the erosional and depositional processes caused by storm wave action in barrier and back barrier systems i e beach ridges storm scarps and washover deposits ii to understand how storm records can be extracted from barrier and back barrier sedimentary bodies using stratigraphical sedimentological micro paleontological and geochemical proxies and iii to show how to obtain chronological control on past storm events recorded in the sedimentary successions the challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm chronologies using these various proxies are discussed and future research prospects are outlined