static bay beach concept for scientists and engineers a review abstract headland bay beach hbb is one of the most prominent physiographic features on the oceanic margin of many countries in the world under the influence of a predominant swell its curved periphery in natural environment may reach static equilibrium and remains stable without sediment supply from updrift and or a riverain source within its own embayment coastal scientists and engineers have attempted to develop mathematical expressions to quantify this ideal bay shape since the 1940s as the scenario with depleting sediment supply has become a common reality on many parts of the world coastline in more recent time some coastal engineers have advocated a rational approach to mimicking the static bay shape found in nature in order to mitigate beach erosion as well as for coastal management nowadays many useful applications have emerged since the publication of the parabolic bay shape equation pbse developed for static equilibrium planform sep in late 1980s the advance in modern computer technologies and international collaboration has further facilitated the exchange of knowledge and applications of this static bay beach concept sbbc this paper reviews the progress on the research in hbb made by geographers and geologists since the 1940s together with the involvement of coastal engineers working on shore protection and management from the 1960s aided by software mepbay developed in 2003 for the pbse several practical examples are demonstrated in this paper for the stability verification of natural and man made bay beaches shore protection mitigating downdrift erosion of a harbour design of recreational bay beach as well as for environmental impact assessment limitations on and clarifications for engineering applications based on the sbbc are also discussed in this paper

discussion of wave energy distribution and morphological development in and around the shadow zone of an embayed beach by c j daly k r bryan c winter coastal engineering vol 93 p 40 54 abstract the computational results presented by daly et al 2014 regarding the rotation of a pocket beach in response to varying wave directionality are discussed in the context of analytical results of a stochastic parabolic bay formula

wave energy distribution and morphological development in and around the shadow zone of an embayed beach abstract background the curved shoreline shape of embayed beaches is one of its most notable characteristics and can be described using the parabolic bay shape equation pbse wave diffraction in and around the shadow zone is often regarded as the primary forcing mechanism leading to the prominent curvature of the shoreline however wave climate variables wave direction directional spreading and wave height are shown to be influential in redistributing wave energy throughout the bay and in the shadow zone methods in this study a process based morphological model delft3d is used for hydrodynamic and morphodynamic simulations of a schematic embayed beach wave forcing conditions are systematically varied between a mixture of time invariant and time varying cases results the role of diffraction is shown to be dominant only when the wave conditions are both narrow banded 30 otherwise as little as 6 variation in wave direction within a 90 range can account for the shoreline curvature in and around the shadow zone conclusion the degree to which wave direction and directional spreading vary through time therefore has a large effect on the equilibrium orientation and shoreline planform of the bay

an integrated approach to coastal erosion problems in northern tuscany italy littoral morphological evolution and cell distribution abstract occupation of the coast has significantly increased in recent decades mostly due to a greater demand for recreation and tourism today erosion threatens many human made structures and activities requiring an integrated approach for the understanding of coastal dynamics and identification of alternatives to associated problems this study investigates a 64 km long coastal physiographic unit in the northern microtidal littoral of tuscany italy vertical aerial photographs and direct field surveys were used to retrieve changes in shoreline position over 1938 1997 and 1997 2005 time intervals significant beach accretion was observed during the first period updrift of carrara 84 m and viareggio 280 m harbours and at marina di pietrasanta 100 m whereas severe erosion occurred downcoast of carrara harbour 130 m at marina dei ronchi and on the northern side of arno river mouth 400 m similar trends were observed between 1997 and 2005 beach slope between the 1997 shoreline position and the closure depth correlated well with the distribution of erosion accretion patterns from the 1938 1997 period slopes were lower in eroded areas than at sites under accretion longshore distribution of erosion accretion patterns was controlled by coastal compartmentalisation three of the main littoral cells were mostly formed by natural limits i e punta bianca promontory marina di pietrasanta the arno river mouth and the port of livorno several sub cells were created within these cells due to the introduction of human made structures such as carrara and viareggio harbours which formed artificial fixed limits that allowed the transport of sediments exclusively fines in one direction only results will help improve the understanding of coastal processes and manage littoral sediment transport in a sustainable manner this will reduce the need for structural interventions such as breakwaters and groynes which in the past decades prevented coastal retreat at local scale but shifted erosion downdrift leading to degradation of the investigated area and requiring continuous maintenance

relationship between beach morphodynamics and equilibrium profiles in this paper a new beach equilibrium formulation that treats the shoaling portion of the profile independently from that of the breaking portion is proposed the two portions are matched at the breaking point the formulation considers wave reflection from the beach and the tidal variation of the sea level both profiles are represented by a similar expression that depends on two parameters a and c which account for wave dissipation and b and d which account for beach reflection the parameters are then calibrated using over 50 profiles from 13 beaches along the spanish coast

on the applicability of empirical formulas for natural salients to sardinia italy beaches abstract the paper presents an empirical analysis of the shoreline response to natural obstacles either submerged reefs and islands distributed along the sardinian italy coastlines exposed to different wave and wind climates the study focuses on salient morphological features whose geometrical properties have been acquired through an extensive field and image derived survey the current analysis has been used to propose geometric predictive formulas for stable salients that overcome some limitations affecting previous works a semi probabilistic method based on well known rate of change statistics is also presented to verify the equilibrium condition of salients analysis results suggest that site specific wave transmission in the lee of submerged reefs requires a range of salient limiting b s ratio values broader than those presented in the literature b being the length of the obstacle and s the distance between undisturbed beach and obstacle the b s ratio has been proved to be the main dimensionless variable for predicting salient amplitude and basal width in particular the proposed predictive equation suggests an erosion condition for some combinations of b sand the 8 times rule appears not to be applicable to natural salients

role of geological inheritance in australian beach morphodynamics the australian coast contains 10 685 beaches which occupy 49 of the 30 000 km coast and average 1 37 km in length their relatively short length is largely due to the presence of bedrock calcarenite and laterite which form boundaries to many of the beaches as well as occurring as rocks reefs and islands along and off the beaches this geological inheritance plays a major role in australian beach systems determining their length and through wave refraction and attenuation influencing beach location shape type morphodynamics and circulation which in turn influence sediment transport and the backing dune and barrier systems this paper uses a database covering every australian beach to review the role of headlands rocks and reefs on australian beaches major effects are the short average beach length reduction in breaker height resulting in lower energy beach types wave refraction resulting in increased beach curvature the presence of topographic rips on moderate and higher energy beaches and megarips during high wave conditions and the interruption of and or trapping of longshore sand transport leading to beach rotation

distribution and transport of hydrocarbons in surface sediments of the alaskan outer continental shelf abstract surface sediments from the outer continental shelf of alaska were analyzed for hydrocarbons as part of an environmental survey sponsored by noaa blm sediments were collected from the proposed oil lease areas of beaufort sea southeastern bering sea norton sound navarin basin gulf of alaska kodiak shelf and lower cook inlet data on normal and branched alkanes and di and triterpenoids from capillary gas chromatography gc and gas chromatography mass spectrometry gc ms indicate that the area displays little evidence of petroleum hydrocarbons i e seeps except at a few isolated stations beaufort sea sediments have the highest hydrocarbon budget whereas kodiak shelf sediments have the lowest the molecular markers of the hydrocarbons are of a mixed marine autochthonous and terrestrial allochthonous origin norton sound and cook inlet sediments contain the highest levels of terrigenous lipids and kodiak shelf the lowest the abundance of alkenes implies that relatively low oxidizing conditions exist in some of the depositional areas studied suggesting that extraneous petroleum hydrocarbons introduced into these sediments would be expected to have a relatively long residence time the distribution of polynuclear aromatic hydrocarbons pah is complex and shows a pyrolytic origin the data on perylene strongly favor the hypothesis that it is performed from terrigenous precursors and transported into the marine environment with no apparent in situ generation polynuclear aromatic hydrocarbons of diagenetic origin are probably dominant in gulf of alaska and kodiak shelf sediments two stations north of kalgin island in lower cook inlet and one in southeastern bering sea show typical weathered petroleum distribution of n alkanes and triterpenoids probable pathways of transport and fate of petroleum hydrocarbons in case of an oil spill are also briefly discussed

modeling of 500 year tsunamis for probabilistic design of coastal infrastructure in the pacific northwest abstract this paper describes the development of tsunami scenarios from the national seismic hazard maps for design of coastal infrastructure in the pacific northwest the logic tree of cascadia earthquakes provides four 500 year rupture configurations at moment magnitude 8 8 9 0 and 9 2 for development of probabilistic design criteria a planar fault model describes the rupture configurations and determines the earth surface deformation for tsunami modeling a case study of four bridge sites at siletz bay oregon illustrates the challenges in modeling of tsunamis on the pacific northwest coast a nonlinear shallow water model with a shock capturing scheme describes tsunami propagation across the northeastern pacific as well as barrier beach overtopping bore formation and detailed flow conditions at siletz bay the results show strong correlation with geological evidence from the six paleotsunamis during the last 2800 years the proposed approach allows determination of tsunami loads that are consistent with the seismic loads currently in use for design of buildings and structures

numerical modeling of the tensile fracture reactivation under the effects of rock geomechanical properties and heterogeneity during co2 storage the injection of co2 into aquifers increases fluid pressure and induces a change of the geomechanical state this is expected to be a cause of fracture reactivation which is an important issue for the safety of co2 storage using the geomechanics module fracture reactivation which was induced by tensile failure was considered for the investigation of a potential co2 leakage numerical simulations were conducted to analyze the effects of the rock geomechanical properties on the fracture reactivation in a two dimensional system and then the properties of fracture propagation were extended to the different rock types hard shale and weak shale in a three dimensional system changes of the stress state rock deformation and the pressure build up induced by co2 injection were examined when a rock has a high young s modulus effective stress decreases rapidly leading to an earlier fracture reactivation the total reduction of effective stress in the rock with a low poisson s ratio was less than that of the rock with a high poisson s ratio the magnitude of pressure build up is lower in the high permeability rock so that the fracture propagates more slowly hard shale s caprock is more favorable than that of weak shale for co2 storage because fractures are opened later retarding the co2 leakage the injected co2 flows through a preferable region with reactivated fractures in the heterogeneous caprock this study broadens our perception of the mechanical behavior that is induced by co2 injection and it could be helpful for the precise safety assessment of co2 storage projects

artificial intelligence and headland bay beaches headland bay beaches are a typical feature of many of the world s coastlines their curved planform has aroused much interest since the early days of coastal engineering modelling this characteristic planform is a task of great interest not least in relation to projects of coastal structures whose effects on the shoreline must be studied from the planning stages in this work artificial intelligence is applied to this task in particular artificial neural networks anns unlike conventional planform models they are not based on a given mathematical expression of the shoreline curve instead they learn from experience from a number of training cases how the planform of a headland bay beach is shaped with due regard to the obliquity of incident waves three artificial neural networks with different input output structures are implemented and subsequently trained with a number of bays once trained they are tested for validation on other headland bay beaches finally the most performing neural network is compared with a state of the art planform model

exploring the sensitivities of crenulate bay shorelines to wave climates using a new vector based one line model we use a new exploratory model that simulates the evolution of sandy coastlines over decadal to centennial timescales to examine the behavior of crenulate shaped bays forced by differing directional wave climates the model represents the coastline as a vector in a cartesian reference frame and the shoreface evolves relative to its local orientation allowing simulation of coasts with high planform curvature shoreline change is driven by gradients in alongshore transport following newly developed algorithms that facilitate dealing with high planform curvature coastlines we simulated the evolution of bays from a straight coast between two fixed headlands with no external sediment inputs to an equilibrium condition zero net alongshore sediment flux under an ensemble of directional wave climate conditions we find that planform bay relief increases with obliquity of the mean wave direction and decreases with the spread of wave directions varying bay size over 2 orders of magnitude 0 1 16 km the model predicts bay shape to be independent of bay size the time taken for modeled bays to attain equilibrium was found to scale with the square of the distance between headlands so that all else being equal small bays are likely to respond to and recover from perturbations more rapidly over just a few years compared to large bays hundreds of years empirical expressions predicting bay shape may be misleading if used to predict their behavior over planning timescales

morphological impacts of the chilean megathrust earthquake mw 8 8 on coastal wetlands of high conservation value abstract the subduction earthquake mw 8 8 on february 27th 2010 which affected chile s south central coast 37 s produced a co seismic uplift of 1 4 m in coastal tubul raqui wetland area with abrupt morphological changes in order to determine the magnitude of the changes in this area of high conservation value salt marsh morphological features were identified and quantified by mapping the changing extent of the coverage of morphological features before 2009 and after 2011 2012 the tectonic disturbance rectified satellite images of seven study sites were created for the three years using google earth images and processed in arcgis the results indicate a total decline of 31 7 in the area of the morphological features and the emergence of 1 25 km2 of dried area salt pans and tidal creeks were severely affected with more than 90 loss in contrast there was a slight recovery of the tubul and raqui main river channel 12 and the tidal channels 8 5 between 2011 and 2012 mainly in the area near the river mouth the salt marsh cover by spartina densiflora showed slight variation after the co seismic uplift 14 6 demonstrating high tolerance in the face of high impact natural disturbances the changes and later evolution may be explained mostly by the action of the seismic cycle in subduction zones continuing to monitor state of the recovery of the salt marsh and other similar environments may help to understand the true role that the seismic cycle plays in the dynamics of coastal ecosystems as well as its incidence in the recovery process

mid to late holocene shoreline reconstruction and human occupation in ancient eretria south central euboea greece few studies have aimed to reconstruct landscape change in the area of eretria south central euboea greece during the last 6000 years the aim of this paper is to partially fill in this gap by examining the interaction between mid to late holocene shoreline evolution and human occupation which is documented in the area from the late neolithic to the late roman period with discontinuities evidence of shoreline displacements is derived from the study of five boreholes maximum depth of 5 25 m below the surface drilled in the lowlands of eretria based on sedimentological analyses and micro macrofaunal identifications different facies have been identified in the cores and which reveal typical features of deltaic progradation with marine lagoonal fluvio deltaic and fluvial environments in addition a chronostratigraphy has been obtained based on 20 ams 14c radiocarbon dates performed on samples of plant remains and marine lagoonal shells found in situ the main sequences of landscape reconstruction in the plain of eretria can be summarized as follows a marine environment predominated from ca 4000 to 3200 cal bc and a gradual transition to shallow marine conditions is observed ca 3200 3000 cal bc due to the general context of deltaic progradation west of the ancient city subsequently from ca 3000 to 2000 cal bc a lagoon occupied the area in the vicinity of the temple of apollo and the settlement s development was restricted to several fluvio deltaic levees thus severely limiting human activities in the plain from ca 2000 to 800 cal bc a phase of shallow marine presence prevailed and constrained settlement on higher ground forcing abandonment of the major part of the plain finally since the eighth century bc the sea has regressed southward and created the modern landscape

application of the equilibrium planform concept to natural beaches in northern ireland the equilibrium planform concept epc for bayed beaches has achieved wide currency in coastal morphodynamics the north coast of ireland comprises a series of discrete headland embayment beaches within which waves and currents recycle a finite sediment volume it is therefore an ideal setting in which to explore the applicability of the concept application of the approach to 9 embayment beaches on the north coast of ireland provides some insights into the application of the concept the planform of some beaches does correspond to that predicted while others do not those whose measured planform does not correspond to the predicted planform can be interpreted through a difficulty in identifying the wave diffraction point b disequilibrium on the beach sediment scarcity or excess c geological control of beach morphology the subjectivity in selecting the diffraction point renders alternative explanations difficult and reduces the utility of the approach on natural shorelines where significant irregularities render identification of such points difficult

uncertainty in the application of the parabolic bay shape equation part 1 abstract this paper aims to quantify the uncertainty in the application of the parabolic bay shape equation pbse for a bay in static equilibrium by means of expert elicitation a database was generated consisting of the position of the control points that determine the static equilibrium planform sep the elicitation consisted of two parts in part 1 22 expert volunteers were asked to place the three control points that determine the sep on a vertical aerial photograph of taquaras taquarinhas bay a morphologically stable bay in the south of brazil approximately 1800 m in width and with an indentation of 750 m the distribution of the location of the sep along four evenly spaced 200 m profiles in the southern part of the bay was determined the overall bias of the location of the sep calculated over the four profiles was in the order of 41 m landward and the average standard deviation was 116 m these parameters increased when moving alongshore toward the curved section of the bay this means that the uncertainty in the application of the pbse is dependent on the particular point of interest along the bay in part 2 of the elicitation 30 volunteers participated this time the consequence of the placement of the control points the corresponding sep was visible comparing the results from parts 1 and 2 it was observed that when volunteers were directly confronted with the result of the placement of the control points a plotted sep a much smaller variation in the position of the sep occurred this implies that when feedback on the result is provided the pbse is a more robust method

observations of morphological change and sediment transport on a steep gravel beach abstract observations of morphological change and swash sediment loads concurrent with measurements of water level waves and currents were obtained during a spring to spring tidal cycle on a steep macrotidal gravel beach in southwest england the wave conditions experienced during the field experiment were relatively calm and the significant inshore wave height and period averaged 0 4 m and 6 s respectively incident frequency water motions dominated the hydrodynamics and the phasing between water surface elevation and cross shore and alongshore currents was inconsistent with standing edge wave motion morphological change was directly related to maxima in shoreline elevation and four modes of berm adjustment identified regression and rollover in response to falling and rising water levels respectively and removal and reformation during and after storms respectively swash processes transported substantial amounts of sediment at rates comparable to sand beaches and the net transport under modal wave conditions was estimated to be 1 kg per swash onshore per unit metre beach width steep hydrodynamic gradients induced by the abrupt slope breaks of the step and berm are one of the main causes of the large morphological variability characteristic of gravel beaches

generalities on static equilibrium bays abstract previous methods of determining the curved waterlines of bays which form on the coasts around the world have involved the logarithmic spiral this has been applied to unstable bays which could erode back to a limit termed static equilibrium for which the constant in the spiral could be related to the obliquity of the wave crests to the control line joining the upcoast headland to the downcoast extremity of the bay it is shown that this applies mainly to the shadow zone behind the upcoast headland and not to the full bay periphery and does not have a fixed centre a new method is proposed utilising arcs from the point of wave diffraction to the shoreline whose lengths and angles to the wave crest line are related to those of the control line data and curves are presented for the static equilibrium shape by which the stability can be tested they thus predict the waterline for the case of no sediment supply either from littoral drift or rivers debouching into the bay an indentation ratio can also be derived to test stability

a quasi experimental setting of coarse clast transport by the 2010 chile tsunami bucalemu central chile abstract on 27th february 2010 a mw 8 8 earthquake occurred in central chile causing a tsunami that severely affected the central chilean coast in this study we present sedimentological data of the 2010 chile tsunami from the coastal town of bucalemu in central chile the tsunami deposited both fine grained sediments as well as cobbles and boulders the location offers a quasi experimental setting for coarse clast transport because an artificial pile of cobbles and boulders was piled there for construction purposes some days before the tsunami therefore the pre tsunami transport setting and transport distances are well defined additionally a local flow depth of ca 2 m and flow speed of ca 5 6 m s are deduced from eyewitness reports and video recordings the cobbles and boulders have been transported up to 155 m from the pile in landward direction the size of the quarried clasts was restricted to max 0 3 m3 and 720 kg bigger boulders were not available at the location even though calculations show that the tsunami would have been capable to transport them calculations of flow speeds required for the initialization of transport in different modes such as sliding rolling or saltation indicate that all clasts that were moved by the tsunami in landward direction were entrained by the flow given a minimum observed speed of 5 6 m s with 65 being transported by rolling and 35 by saltation the transported clasts are arranged in three groups positioned in morphological depressions on the coastal plain a landward fining trend is not present the arrangement of clasts originating from a pile and being deposited in distinctive groups entails that the landward transport of cobbles and boulders is a function of repeated entrainment transport and deposition by several waves of the tsunami wave train consequently we interpret the clast distribution as a result of a combination of the number of individual waves of the tsunami wave train their respective energies the local topography and the pre transport setting of a clast pile which releases wedged clasts with each successive wave

a study of caprock hydromechanical changes associated with co2 injection into a brine formation a numerical study of hydromechanical changes during a deep underground injection of supercritical co2 in a hypothetical brine aquifer caprock system is conducted the injection process is simulated using a newly developed computer model for multi phase analysis of co2 and brine water flow coupled with heat transfer and rock deformations in this modeling co2 is injected at a constant rate over a 10 year period at a depth of 1 300 1 500 m the injection zone is overlain by a 100 m thick caprock located at 1 200 1 300 m which in one of the studied cases is intersected by a vertical fault the hydraulic mechanical as well as hydromechanical responses caused by the injection are studied this includes the spread of the co2 plume effective stress changes ground surface uplift stress induced permeability changes and mechanical failure analysis the analysis shows that most hydromechanical changes are induced in the lower part of the caprock near its contact with the injection zone whereas the sealing mechanism of the upper part may remain intact despite an injection pressure close to the lithostratic stress value

beach changes from sediment delivered by streams to pocket beaches during a major flood abstract the significance of sediment delivered via storm associated stream discharge in altering sediment characteristics beach form and volume is evaluated on pocket beaches with different basin characteristics and wave exposures the focus is on changes on three beaches on elba island italy caused by a flood event in september 2002 that had an estimated recurrence interval of 200 years beach profiles and foreshore sediment samples were gathered in 1999 and 2000 to identify pre storm characteristics in september 2002 to reveal the immediate effects of the storm and in 2003 and 2004 to reveal post storm recovery foreshore sediments were finer and better sorted and contained no pebbles prior to the flood coarsening of the sand and granule fraction was evident after the flood along with pebble accumulations especially near major streams mean size sorting values and percent pebbles one and two years after the flood were generally greater than pre flood conditions but less than immediately after the flood beach profiles reveal conspicuous erosion immediately after the flood when sediment delivered by streams is transported to subaqueous deltas thereafter sediment moves onshore and alongshore to adjacent beaches to restore subaerial volumes the location of streams within a compartment relative to the location of capes and headlands is important in determining the movement of sediment added to the beach by streams the sites are all sheltered from the highest energy waves from the west facilitating longshore transport to the west where the largest stream is located at the east end of a compartment sediment discharged from it is source material for the downdrift beaches to the west where the largest stream is at the west end of the compartment the ability to supply sediment to the beaches to the east is restricted hence broad scale geologic controls headlands and capes enhance or diminish the ability of streams to influence beach change throughout the pocket the inability of beaches on two of the sites to migrate landward due to human development of uplands will be an issue in the future lack of sediment to replenish beaches through erosion of the upland places increased emphasis on the role of coastal streams in the beach sediment budget changing watershed attributes to allow more sediment discharge during high energy low frequency events e g devoting more land to agriculture would be a way of helping to restore beach sediment

hydrocarbons in the sediments of port valdez alaska consequences of five years permitted discharge abstract hydrocarbons have been investigated in the sediments of port valdez alaska after three to five years of oil terminal operation with a routine daily discharge of 170 kg of petroleum residue in an otherwise undeveloped area surficial benthic sediments 0 5 cm and core segments down to 30 cm have been analyzed information about total hydrocarbons unresolved complex mixture normal alkanes pristane phytane hopanes and polycyclic aromatic hydrocarbons indicates that petroleum biogenic hydrocarbons and combustion derived aromatic hydrocarbons are present in sediments around the terminal at concentrations up to 218 g g 1 dry sediment the vertical horizontal and temporal distributions of anthropogenic hydrocarbons indicate that most of the sedimentary hydrocarbon accumulation has occurred within 1 km of the terminal a simple calculation suggests that less than 3 of the total oil discharged during routine operations of the terminal has entered the sediments of port valdez for comparison sediment hydrocarbon accumulation associated with a nearby small boat harbor was also examined

uncertainty in the application of the parabolic bay shape equation part 2 abstract this paper attempts to highlight issues that are relevant in the application of the parabolic bay shape equation pbse to a non equilibrium bay for this case the bay of imbituba in southern brazil was chosen the construction of a breakwater to shelter the port of imbituba in the south of the bay was accompanied by an increase in sedimentation to the port area from an eroding downdrift beach superimposed plots of the coastline of the bay of imbituba from different years confirm a general trend of accretion of the southern part of the bay accompanied with a retreat of the coastline in the northern part after the application of the pbse it became clear that the breakwater caused a change in the equilibrium state of the bay between 1947 and 2001 the bay of imbituba has changed from a dynamic equilibrium to a natural beach reshaping or self reshaping the tendency of the sedimentation of the southern part of the bay can be explained by the sep associated with the new updrift diffraction point tip of the breakwater the seaward position of the sep predicts a need for additional sediment in order to achieve a stable plan form

an insight into headland sand bypassing and wave climate variability from shoreface bathymetric change at byron bay new south wales australia abstract the headland sand bypassing mechanisms in the eastern australian longshore sand transport system are investigated at cape byron in response to wave climate variability the mechanisms are interpreted from shoreface bathymetric change between surveys in 1883 2002 and 2011 ce they involve a split in the sand transport to follow a nearshore path along the inner bar and a cross embayment path connecting the up coast and down coast outer bars the relative magnitude of the net sand transported via the two pathways is controlled by a rotation in directional wave conditions two bypassing mechanisms were interpreted i a predominantly cross embayment transport during unimodal east southeast wave climate such as those interpreted for the period prior to 1883 and ii a split transport between the inner nearshore and cross embayment paths during a bimodal dominant south south easterly and sub dominant east north easterly wave climate such as in the 2000s the net sand transport bypassing cape byron was dominated by a connected outer bar system prior to 1883 and conversely a stronger inner bar system during the 1960s to 2000s this is manifest in the 10 rotation in seabed morphology and shoreline planforms these changes are in accordance with decadal climate variability described by the interdecadal pacific oscillation ipo the switching between headland sand bypassing mechanisms on interannual to decadal timescales determines the geometry of the bypass strand with the downcoast littoral zone and has important implications for understanding the shoreline rotation and the application of the headland bay beach concept to predicting planform curvature in open compartments

application of the parabolic bay shape equation to sand and gravel beaches on mediterranean coasts reply to the comments of d e reeve abstract the authors wish to focus on certain aspects which had not been discussed previously in schiaffino et al 2012 these aspects cover the methodology adopted to obtain the coefficients proposed for the parabolic bay shape equation and the approach adopted for the evaluation of their applicability and reliability for sand and gravel beaches in particular results concerning shoreline variability as regards control point and wave direction are submitted

neural network modelling of planform geometry of headland bay beaches abstract the shoreline of beaches in the lee of coastal salients or man made structures usually known as headland bay beaches has a distinctive curvature wave fronts curve as a result of wave diffraction at the headland and in turn cause the shoreline to bend the ensuing curved planform is of great interest both as a peculiar landform and in the context of engineering projects in which it is necessary to predict how a coastal structure will affect the sandy shoreline in its lee a number of empirical models have been put forward each based on a specific equation a novel approach based on the application of artificial neural networks is presented in this work unlike the conventional method no particular equation of the planform is embedded in the model instead it is the model itself that learns about the problem from a series of examples of headland bay beaches the training set and thereafter applies this self acquired knowledge to other cases the test set for validation twenty three headland bay beaches from around the world were selected of which sixteen and seven make up the training and test sets respectively as there is no well developed theory for deciding upon the most convenient neural network architecture to deal with a particular data set an experimental study was conducted in which ten different architectures with one and two hidden neuron layers and five training algorithms 50 different options combining network architecture and training algorithm were compared each of these options was implemented trained and tested in order to find the best performing approach for modelling the planform of headland bay beaches finally the selected neural network model was compared with a state of the art planform model and was shown to outperform it

morphological response of a sandy shoreline to a natural obstacle at sa mesa longa beach italy abstract a case study is presented of a comprehensive analysis of the shoreline stability of a salient primary response in the lee of an emergent natural reef at sa mesa longa beach sardinia italy the analysis combines sources of information at different levels of detail and accuracy field surveys conducted with a gps unit remotely sensed imagery geometrical and shape predictive formulas and simulations with a 2d wave current sediment transport numerical model the morphological simulation results for the primary response agree qualitatively with field observations and predictions from empirical formulas the accuracy of a simplified wave energy model in defining the littoral sediment cell compared to the more detailed results of the morphological model is also investigated although the analysis has some limitations as highlighted in the paper the results appear to be promising in terms of applying the analysis to fragile morphologies in the lee of natural reefs in the mediterranean sea

variability of shore and shoreline evolution shore and shoreline evolution both due to natural and human induced causes or factors can be variable over a wide range of different temporal and or spatial scales our capability to understand and especially predict this variability is still limited this can lead to misinterpretation of coastal change information which hampers informed decision making and the subsequent design and implementation of soft engineering interventions collecting and describing example observations of shore and shoreline variability is one way to support and improve such human intervention this paper describes causes and factors for the variability and the resulting possible evolutions of wave dominated shores and shorelines which are illustrated by a number of case studies the new element of this work is that the variability is described in terms of a range of different time and space scales which helps to structure such analysis however it is difficult to generalise the results for arbitrary situations especially on decadal time scales scientific and engineering improvements require more quantitative insight into the physical mechanisms behind the free and forced shore behaviour responsible for the variability

shoreline dynamics and beach rotation of artificial embayed beaches abstract artificially embayed beaches are an increasingly common environment in retreating and urban coasts the study of embayed beaches usually focuses on the concept of some equilibrium configuration of the shoreline caused by the wave approach and the location of protection structures but detailed studies of their shoreline dynamics are scarce the study reported herein monitored the shoreline dynamics of three artificial embayed beaches in barcelona city during a three year period using an argus video system to examine the behaviour of the emerged beach in order to assess the main factors affecting the shoreline and to analyze the processes causing beach rotation at different time scales the length and degree of protection of the three beaches were different and so were their morphological behaviours two of the beaches presented a general retreating trend with rapid abrupt displacements of the shoreline caused by oblique wave incidence during storm events and to the effects of beach nourishment after nourishment slower changes at the beaches determined beach evolution which was also influenced by the formation of long lasting megacusps the third beach the most protected one showed an accretionary trend no formation of megacusps and episodes of beach rotation related to the gradual recovery of the beach after storm events it is concluded that factors controlling the evolution of barcelona city beaches are associated with both natural processes and man induced actions resulting in a more complex pattern than would be expected for small embayed beaches beach rotation appears as a key process for understanding the morphodynamics of embayed beaches it occurs as a fast response to storms but also as a medium term adaptation of the shoreline configuration to morphological changes in the beach or to the recovery of a more stable orientation after storm events and man made changes in the beach orientation resulting from nourishment or sand relocation

toward understanding tectonic control on the mw 8 8 2010 maule chile earthquake the maule earthquake of 27th february 2010 m w 8 8 affected similar to 500 km of the nazca south america plate boundary in south central chile producing spectacular crustal deformation here we present a detailed estimate of static coseismic surface offsets as measured by survey and continuous gps both in near and far field regions earthquake slip along the megathrust has been inferred from a joint inversion of our new data together with published gps insar and land level changes data using green s functions generated by a spherical finite element model with realistic subduction zone geometry the combination of the data sets provided a good resolution indicating that most of the slip was well resolved coseismic slip was concentrated north of the epicenter with up to 16 m of slip whereas to the south it reached over 10 m within two minor patches a comparison of coseismic slip with the slip deficit accumulated since the last great earthquake in 1835 suggests that the 2010 event closed a mature seismic gap slip deficit distribution shows an apparent local overshoot that highlight cycle to cycle variability which has to be taken into account when anticipating future events from interseismic observations rupture propagation was obviously not affected by bathymetric features of the incoming plate instead splay faults in the upper plate seem to have limited rupture propagation in the updip and along strike directions additionally we found that along strike gradients in slip are spatially correlated with geometrical inflections of the megathrust our study suggests that persistent tectonic features may control strain accumulation and release along subduction megathrusts c 2012 elsevier b v all rights reserved

application of the parabolic bay shape equation to sand and gravel beaches on mediterranean coasts abstract the equation most commonly used to describe the bay planform was proposed by hsu and evans 1989 and it was obtained through empirical analysis of sand beach planforms in the last decade interest in gravel sediments increased owing to their greater stability on beaches compared with sand sediments due to the differences between the morphodynamics of sand and gravel beaches which is strictly influenced by their different hydraulic characteristics it was necessary to create a predictive instrument for this beach type as well therefore in this study the standard hsu and evans equation 1989 was modified in order to make it applicable not only to sand beaches but also to gravel beaches the shoreline was computed according to a parabolic model in polar coordinates whose coefficients are considered linearly dependent on the wave direction and related to the beach type the estimation of the free parameters of the model was performed according to a statistical analysis of a shorelines data set of mediterranean sand and gravel embayed beaches

heterogeneous plate locking in the south central chile subduction zone building up the next great earthquake abstract we use global positioning system gps velocities and kinematic finite element models fe models to infer the state of locking between the converging nazca and south america plates in south central chile 36 s 46 s and to evaluate its spatial and temporal variability gps velocities provide information on earthquake cycle deformation over the last decade in areas affected by the megathrust events of 1960 m w 9 5 and 2010 m w 8 8 our data confirm that a change in surface velocity patterns of these two seismotectonic segments can be related to their different stages in the seismic cycle accordingly the northern 2010 segment was in a final stage of interseismic loading whereas the southern 1960 segment is still in a postseismic stage and undergoes a prolonged viscoelastic mantle relaxation after correcting the signals for mantle relaxation the residual gps velocity pattern suggests that the plate interface accumulates slip deficit in a spatially and presumably temporally variable way towards the next great event though some similarity exist between locking and 1960 coseismic slip extrapolating the current decadal scale slip deficit accumulation towards the 300 yr recurrence times of giant events here does neither yield the slip distribution nor the moment magnitude of the 1960 earthquake this suggests that either the locking pattern is evolving in time to reconcile a slip deficit distribution similar to the 1960 earthquake or that some asperities are not persistent over multiple events the accumulated moment deficit since 1960 suggests that highly locked patches in the 1960 segment are already capable of producing a m 8 event if triggered to fail by stress transfer from the 2010 event

morphological response to storms in an embayed beach having limited sediment thickness abstract the morphological response of a wave dominated embayed beach to large storms was investigated via field data collection and numerical simulation hydrodynamic and morphological field data collected in haeundae beach facing sse in the south eastern corner of korea were analysed during the southerly storm waves i e almost shore normal direction the upper part sediments of the beach were eroded and redistributed to the surf zone meanwhile easterly storm waves transported sediment from east to west resulting in coastline advancement in the west and retreat in the east in order to investigate the morphological response of the beach with limited sediment availability under storm conditions the numerical model xbeach was used with the assumption of unlimited sediment availability the southerly storms led to overestimation of sediment transports and unrealistic erosion and deposition patterns in the middle part of the beach in contrast the model results with the option of sediment layer thickness showed good agreement with the erosion and deposition patterns analysed from field data this suggests that sediment availability can be one of the key factors in determining the morphological response in a wave dominated embayed beach where sediment supply from neighbouring beaches or rivers is limited

geochemistry of c25 and c30 biogenic alkenes in sediments of the narragansett bay estuary abstract the distributions of a series of structurally related c 25 and c 30 biogenic alkenes in sediments of the narragansett bay estuary have been determined the suite of alkenes detected differs both quantitatively and qualitatively from those previously reported in other estuanne and coastal regions four c 25 mono and dienes and one c 30 diene comprise 73 91 of the total alkenes in all surface upper 2 5 5 cm sediments analyzed however significant geographic variations exist in the relative abundance of these five compounds throughout the estuary a comparison of alkene concentrations with 13 c of the bulk sedimentary organic matter has shown that the geographic variations of some alkenes reflect the distribution of marine organic matter suggesting a marine source for these compounds the distributions of other alkenes are not similarly correlated in particular concentrations of the c 30 diene are relatively constant and exhibit no dependence on the origin of organic matter in these sediments this distribution implies an in situ production of this alkene throughout the estuary analysis of several sediment cores reveals that alkene concentrations are generally highest at the surface and decrease to low constant values within the upper 25 cm an exception is the subsurface concentration of one c 25 diene which exhibits an increase at the same depth in two separate upper bay cores

coupled reservoir geomechanical analysis of the potential for tensile and shear failure associated with co2 injection in multilayered reservoir caprock systems coupled reservoir geomechanical simulations were conductedto study the potential for tensile and shear failure e g tensilefracturing and shear slip along pre existing fractures associated withunderground co2 injection in a multilayered geological system thisfailure analysis aimed to study factors affecting the potential forbreaching a geological co2 storage system and to study methods forestimating the maximum co2 injection pressure that could be sustainedwithout causing such a breach we pay special attention to geomechanicalstress changes resulting from upward migration of the co2 and how theinitial stress regime affects the potential for inducing failure weconclude that it is essential to have an accurate estimate of thethree dimensional in situ stress field to support the design andperformance assessment of a geological co2 injection operation moreover we also conclude that it is important to consider mechanical stresschanges that might occur outside the region of increased reservoir fluidpressure e g in the overburden rock between the co2 injectionreservoir and the ground surface

on the influence of wave directional spreading on the equilibrium planform of embayed beaches abstract equilibrium beach formulations are engineering tools for estimating a response of beaches in the long term they aim at defining the final orientation of a beach on a scale of years and thus they are used for evaluating the shoreline response due to human interference ports breakwaters protection works etc several equations can be found in the literature for obtaining the static equilibrium planform sep of headland bay beaches hbbs one such being the parabolic bay shape equation pbse the sep is strongly dependent on the location of the down coast control point po which is the downdrift limit from which the pbse is applicable the literature recommends the determination of the po point by means of the direction of the mean wave energy flux at the diffraction point however when this is applied to equilibrium embayed beaches in zones with a wide variability of wave climate directionality and or in cases where the diffraction point is located far from the equilibrium shoreline this approach is no longer valid and thus the resulting planform shape does not properly fit the sep for such conditions this paper investigates the methodology for locating the po point of the sep for such cases exploring the role of wave climate directional spreading employing 44 hbbs in spain and latin america it correlates the planform shape in the long term with the directional variability of the wave climate at the diffraction point additionally an extensive series of numerical simulations using a spectral wave model was carried out to model the combined effects of refraction diffraction in the lee of a breakwater defining the part affected by the coastal structure under different wave conditions the results clarify the importance of wave directional spreading in locating the po indicating that the wider the directional spreading the farther the po point on the shoreline moreover the farther the diffraction point from the coast the smaller the part of the beach affected by the coastal barrier a new formula has been derived to locate the down coast control point po of the parabolic part of the shoreline corresponding to the pbse as a function of the directional variance of the wave climate and the location of the diffraction point the model produced good results with r2 0 9117 and a rmse 1 8297 in estimating the location of the po point in various natural and man made beaches with different degrees of wave directionality

historical changes in the shoreline and littoral processes on a headland bay beach in central chile abstract we applied parabolic and logarithmic adjustments and methods of cartographic overlay to the sandy littoral of concon bay central chile to determine the changes associated with the shoreline and their relation with littoral processes in a typical bay on an active continental margin and with a microtidal regime a set of historical reference points was built by means of aerial photographs and topographies for the period 1945 2008 given the form of the shoreline to the southern section of the bay we applied the classical logarithmic formula of yasso 1965 and the functions incorporated in the coastal modeling system sistema de modelamiento costero smc of the universidad de cantabria in the northern section a method of map overlay was applied the oluca sp model of the smc was used to determine the influence of waves refraction on the types of changes of the shoreline information on waves 1985 2006 mean sea level 2001 2006 and variations in the mean size of beach sediment were used to relate the changes in the plan form of the bay there has been little spatio temporal variability in the shoreline of the bay over the last 65 years the southern section had a mean shoreline retreat rate of 0 55 m year 1945 2008 in spite of the large variability produced in an estuary dominated by waves the best adjustment was obtained with the logarithmic function in the northern section the mean accretion rate was 0 39 m year 1954 2008 the plan form and the historical changes of the shoreline are closely associated with the seasonal changes of the waves and the presence of rocky thresholds in the area the mean sea level did not produce important effects in the types of change

a simple equilibrium model for predicting shoreline change abstract this contribution describes the development calibration and verification of a 1 d behaviour orientated shoreline prediction model the model primarily encapsulates shoreline displacement forced by wave driven cross shore sediment transport hysteresis effects are shown to be important and are included in the model whereby present shoreline change is influenced by past hydro morpho dynamic conditions the potential magnitude of shoreline change increases with incident wave power and the degree of disequilibrium the latter disequilibrium term eq is expressed in terms of the time evolving equilibrium eq and instantaneous dimensionless fall velocities and dictates the direction of shoreline movement following wright et al 1985 the equilibrium fall velocity is defined as a function of the weighted antecedent conditions and is a proxy for the evolving beach state the decay rate of the weighting function used to compute eq is a model free parameter determined by calibration against measured data which physically reflects the degree of observed memory of the system the decay in amplitude of this weighting function with time is controlled by a memory decay term where the weighting reaches 10 1 and 0 1 at 2 and 3 days prior to the current calculation time the model is applied to two multi year 6 years data sets incorporating hourly wave and weekly shoreline measurements from two contrasting energetic sites in se australia the first is the relatively dissipative straight gold coast qld and the second is a more intermediate embayed beach at narrabeen nsw the model shows significant skill at hindcasting shoreline change at both sites predicting approximately 60 of the total shoreline variability the gold coast shoreline is dominated by a strong seasonal signal conversely at the narrabeen embayment shoreline variability and morphology is more dynamic responding at storm frequency evidence suggests that there is a strong coherence between the shoreline position and morphodynamic state and that both have response times characterised by it is hypothesised that optimised values in the shoreline model physically relate to the efficiency of sediment exchanges between the shoreface and offshore bars and the prevalence of one or two dimensional horizontal circulation the general success of this new shoreline model for hindcasting the observed shoreline behaviour at two distinctly different open coast sites suggests that this approach may be suitable for broader application

headland bay beaches revisited an example from sandy hook new jersey abstract a variety of models have been successfully employed to describe the development of a crenulate logspiral type headland bay beach the success of these models has been attributed to the sheltering effect of the headland which results in a systematic distribution of wave energy for a short distance downdrift of the headland the decreasing influence of the headland on waves is thought to result in the curvilinear shoreline planform that is quantitatively described by a logarithmic or exponential function field data from south beach sandy hook new jersey were examined in an area which has historically exhibited a curvilinear headland bay beach and which was in the process of redeveloping such a configuration when data were collected the alongshore distribution of mean grain size beachface slope and an index reflecting slope and grain size showed no systematic trend there was no evidence of a systematic influence of the headland on wave energy it is suggested that the ubiquitous headland bay landform arises as a result of a general distance decay function away from the headland distance decay functions are typically curvilinear and easily fitted by logarithmic or exponential models not only wave processes but other factors such as sediment supply may be distributed as a distance decay function with respect to the headland resulting in a headland bay configuration

morphological recovery of beach severely damaged by the 2011 great east japan tsunami abstract the great east japan tsunami which occurred on 11 march 2011 the 2011 tsunami caused significant changes to the coastal and estuarine morphology along the sendai coast miyagi prefecture japan the recovery process which took place subsequently after the tsunami is investigated using aerial photographs bathymetry data and empirical orthogonal function eof method results from the aerial photograph analysis indicate that the shoreline was in the dynamic equilibrium condition in the period before the tsunami period 1 the recovery of the shoreline was very fast in the period of two years post event period 2 however it was more stable for the period of the next 4 5 years period 3 the analysis on the bathymetry data indicates that besides the sediment supply from adjacent coasts eroded sediment of the offshore seabed was transported onshore and led to a mass recovery of the shoreline at the lagoon areas the littoral system of the sendai coast also changed significantly between the periods before and after the tsunami as well as between periods 2 and 3 the sediment deposited inland and in the lagoon areas is perceived as the main reason that caused the retreat inwardly of about 70 m 80 m of the shoreline after the tsunami regarding the eof analysis the reflected coastal processes of the first three dominant components from the eof analysis for two shoreline data sets after the tsunami can be explained in period 2 the morphological recovery at severely damaged areas lagoons was the most dominant process whilst the second one was the cross shore variety of shoreline which was the most dominant process preceding tsunami the contribution rate of the first and second components in period 2 is about 4 times different in the period of the next 4 5 years period 3 the cross shore variety of shoreline which was induced by high waves came back to be the most dominant process whilst the second component reflects the longshore sediment transport these two dominant components are similar to the ones before the tsunami the contribution rates of the first two components before and after the tsunami are relatively close as well that confirms that the coastal processes have returned back to the conditions before the tsunami this is an important finding which is deduced from this study because a strong tsunami such as the 2011 tsunami could have been a major disturbance tipping the normal cross long shore variability of shoreface water interface towards a different regime

a process based shape equation for a static equilibrium beach planform abstract coastal erosion is a major problem for shorelines everywhere in the world in order to mitigate beach stability problems it is necessary to determine the equilibrium shape of the beach planform current equilibrium planform shape equations are only valid under certain simplifications for instance they are unable to predict the effect of nearshore islands and or rocky bottoms as well as the effect of several diffraction points the aim of this paper is to present a new process based shape equation that is able to overcome those limitations and estimate the static equilibrium shoreline of complex bathymetry beaches the equation is based on the hypothesis that a pocket beach gets its static equilibrium planform when the mean surf zone longshore velocity averaged over a period of time is null v 0 in every point along the beach based on this hypothesis the direction of the shoreline that nulls the mean surf zone longshore velocity along the beach is evaluated therefore the shape equation is based on the longshore current velocity formula the new equilibrium shape equation is applied to two spanish beaches namely milagro beach and cala millor beach milagro beach has a very smooth bathymetry and the parabolic shape equation developed by hsu and evans 1989 is able to predict the equilibrium shoreline cala millor is more complex it has some rock outcrops along the beach and the parabolic shape equation does not work the equilibrium shape equation presented in this paper simulates the equilibrium shoreline of both beaches successfully with a high r2 around 0 96 between the modelled shoreline and the real shoreline in both case studies

numerical modeling of crenulate bay shapes a numerical model is developed to compute the shoreline planform in a crenulate bay beach the new model combines polar and cartesian coordinates and can be used effectively to compute a hooked zone shoreline in the lee of upcoast headland the model is calibrated using laboratory data with an incident wave angle ranging from 25 to 60 the results of calibration and verification suggest that the ratio of the sediment transport parameters by wave and longshore current in this model is close to unity and the computed shoreline planforms for the hooked and unhooked zones are in good agreement with the ones measured especially when a bay is close to static equilibrium in addition the bay shape calculated by the present model is similar to that given by the well known empirical parabolic equation for a bay in static equilibrium the process of bay shape development from a straight beach to a static equilibrium bay is studied using laboratory experiments and the present numerical model the temporal variations in the computed longshore sediment transport at different locations within a bay beach are analyzed from this the decrease in the sediment transport becomes apparent while a bay beach changes its shape from straight toward a state of equilibrium based on this experience it may be concluded that the present numerical model can produce a temporal change in the shoreline planform of a crenulate bay beach from a transition state to static equilibrium subject to seasonal wave action

modelling of embayed beach equilibrium planform and rotation signal abstract embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries which deeply affect equilibrium beach planform and shoreline dynamics we use lx shore a state of the art shoreline change model coupled with a spectral wave model to address embayed beach shoreline dynamics driven by longshore sediment transport processes the model is applied to different idealized embayed beach configurations including variations in headland lengths the model simulates a large range of equilibrium embayed beach planforms and associated spatial and temporal modes of shoreline variability for short headlands enabling occasional headland sand bypassing both embayed beach curvature and maximum erosion at the upwave side of the embayment increases with increasing headland length beach curvature also increases with increasing headland length for headlands long enough to prevent any headland sand bypassing in contrast at the same time embayed beach becomes increasingly curved and symmetric with maximum localised erosion within the embayment decreasing in intensity when there is no headland sand bypassing rotation signal decreases in amplitude and becomes increasingly symmetric with increasing headland length the modal time invariant directional spreading of incident waves is critical to embayed beach behaviour with the envelope and variance of cross shore shoreline change and time averaged shoreline curvature all increasing with decreasing modal directional spreading embayed beach rotation characteristic timescale increases with increasing embayed beach length while the narrower the embayment the smaller the cross shore amplitude of shoreline variability our simulations provide new insight into the influence of embayment characteristics and incident wave conditions on equilibrium planform and shoreline dynamics of embayed beaches this work also implies that the degree of potential headland sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed beach dynamic planform configuration

predictive model of three dimensional development and deformation of a river mouth delta by applying contour line change model a predictive model of the three dimensional development and deformation of a river mouth delta is developed this model enables the prediction of not only the shoreline change but also the three dimensional long term topographic changes around a river mouth and offshore sand transport can be taken into account when the sea bottom slope exceeds a critical value given by the angle of repose of sand numerical simulation of three cases of initial beach slopes is carried out and compared the calculated and actual beach changes measured around the fuji and tenryu river mouths are compared it is concluded that calculated results can reproduce real phenomena measured around river mouths qualitatively

planform and mobility in the meaipe maimba embayed beach on the south east coast of brazil the meaipe maimba embayed beach mmeb on the south east coast of brazil has been subject to anthropogenic pressures since the 70 s in this study we discuss the adequacy and contribution of the parabolic planform model to determine the planform and variability of the mmeb taking into consideration variation in wave conditions the role of different controlling conditions on the planform variability is analyzed as well as the morphological and planform mobility mmeb exhibited a new configuration in response to the construction of a harbor which interrupted the longshore sediment transport after four decades three particular morphodynamic sectors have been recognized along the beach the central sector is more exposed to normal wave incidence and cross shore processes predominate the northern and southern sectors are influenced by wave diffraction processes around the headlands and port respectively in the northern sector the presence of secondary headlands and inner islands imposed a geomorphological control on beach morphology and coastal processes the use of the parabolic planform model provided useful insights for the assessment of potential planform mobility since the decadal shoreline evolution combined with beach profiles and sediment characteristics allowed understanding of the beach mobility processes and supported the interpretation of modeling results

a numerical shoreline model for shorelines with large curvature abstract this paper presents a new numerical model for shoreline change which can be used to model the evolution of shorelines with large curvature the model is based on a one line formulation in terms of coordinates which follow the shape of the shoreline instead of the more common approach where the two orthogonal horizontal directions are used the volume error in the sediment continuity equation which is thereby introduced is removed through an iterative procedure the model treats the shoreline changes by computing the sediment transport in a 2d coastal area model and then integrating the sediment transport field across the coastal profile to obtain the longshore sediment transport variation along the shoreline the model is used to compute the evolution of a shoreline with a 90 change in shoreline orientation due to this drastic change in orientation a migrating shoreline spit develops in the model the dimensions of the spits evolving in the model compare favorably to previous model results and to field observation of the skaw spit in the north of denmark

the 2010 mw 8 8 maule megathrust earthquake of central chile monitored by gps large earthquakes produce crustal deformation that can be quantified by geodetic measurements allowing for the determination of the slip distribution on the fault we used data from global positioning system gps networks in central chile to infer the static deformation and the kinematics of the 2010 moment magnitude m w 8 8 maule megathrust earthquake from elastic modeling we found a total rupture length of 500 kilometers where slip up to 15 meters concentrated on two main asperities situated on both sides of the epicenter we found that rupture reached shallow depths probably extending up to the trench resolvable afterslip occurred in regions of low coseismic slip the low frequency hypocenter is relocated 40 kilometers southwest of initial estimates rupture propagated bilaterally at about 3 1 kilometers per second with possible but not fully resolved velocity variations

headland bay beach planform and tidal range a neural network model abstract an artificial neural network model of headland bay beach planform is presented and developed it differs from conventional models in two fundamental respects first the knowledge of the problem is not input to the model in the form of a given planform equation but is acquired by the model itself from a series of examples of headland bay beaches in the course of a training process in other words the model learns second the new model takes into account tidal range a significant factor influencing sediment transport the artificial neural network is a multilayer perceptron trained with the bayesian regularisation algorithm for the selection of the optimum network architecture a thorough experimental study involving 240 neural networks is carried out the model with the selected network architecture is trained and validated on a data set comprising 29 headland bay beaches and shown to outperform a conventional headland bay beach planform model the model is then applied to investigate the relation between tidal range and headland bay beach planform for this purpose the non dimensional planforms corresponding to two values of the maximum tidal range tr 0 5 m and 4 5 m under different wave obliquities q0 40 50 and 60 are simulated for the smallest wave obliquity 40 the shoreline curves for both tidal ranges practically overlap for greater wave obliquities the larger tidal range is found to produce a greater bay indentation the difference increasing with wave obliquity these results improve our understanding of headland bay beach morphology and in particular of the manner in which it varies between meso macrotidal and microtidal conditions due to the tidal modulation of the sediment transport vectors or its absence respectively

on the relation between the direction of the wave energy flux and the orientation of equilibrium beaches abstract the equilibrium beach planform concept has been widely used in recent years as an engineering tool for modeling shoreline changes designing new beaches and for stability studies of existing ones it defines the final shape of a beach on a scale of years which is important for solving erosion problems and for the design of nourishment projects throughout the literature the planform final shape hereinafter denoted as the static equilibrium beach orientation sebo is obtained based on the direction of the mean wave energy flux of whole waves impinging on the coast this paper investigates the effect of beach sediment size and the shape of the directional distribution sdd of the energy flux of the wave climate on the direction that dictates the sebo the study employs field data from 32 beaches along the spanish coast and available long term databases of directional wave climates initiation of sediment motion due to wave action is taken into account in order to filter the directional wave climate to consider only waves that are capable of moving the sediment the results indicate that the direction of the mean energy flux of filtered waves is more appropriate for the determination of the sebo than that of whole waves additionally the results confirm the importance of both the filtration process of the local directional wave climate and the usage of the whole directional spectra in stability studies and coastal engineering practice

beaches downcoast of harbours in bays abstract in spite of beach berms being removed during each storm sequence the waterline may be retained constant either by a constant supply of littoral drift or static equilibrium bays being formed between headlands the construction of salients behind offshore breakwaters may be at the expense of the adjoining coast which resembles the ubiquitous bay shapes formed between headlands that can be either in dynamic or static equilibrium this is the same silting situation in the lee of breakwaters extending from the coast where beach erosion results downcoast ports constructed upcoast of a bay in dynamic equilibrium can have their breakwaters so located that the bay can become statically stable in the case of the bay being already in static equilibrium breakwater extension often causes massive accretion in its lee and concomitant erosion further downcoast thus demanding prodigious expense for beach protection installations appropriate procedures are now suggested to minimise this undesirable effect of beach erosion associated with the construction and extension of breakwaters to ports upcoast of a bay

shoreline accretion and sand transport at groynes inside the port of richards bay the south western shoreline along the entrance channel inside the port of richards bay has experienced continued erosion four groynes were constructed to stabilise the shoreline monitoring of shoreline evolution provided valuable data on the accretion adjacent to two of the groynes and on the sediment transport rates at these groynes tides beach slopes winds wave climate current regime and sand grain sizes were documented the one site is moderately protected from wave action while the other is protected according to the wiegel wiegel r l 1964 oceanographical engineering prentice hall inc englewood cliffs nj classification the shoreline accreted progressively at the two groyne sa t 0 065 m day and 0 021 m day respectively the shorelines accreted right up to the most seaward extremity of the groynes equilibrium shorelines were reached within about 3 5 years to 4 years which compare well with other sites around the world the mean wave incidence angle is large and was found to be about 22 the median sand grain sizes were 0 33 mm and 0 37 mm the groynes acted as total traps the beach surveys were extended to an adequate depth and cross shore sediment transport did not cause appreciable net sand losses into the entrance channel the net longshore transport rate along the study area which is north westbound is only slightly lower than the gross longshore transport the actual net longshore transport rates are 18 000 m 3 year and 4 600 m 3 year respectively at the two groynes a rocky area limits the availability of sand at one

wave climate and morphosedimentary characteristics of the kenitra bouknadel sandy coast morocco the bouknadel kenitra 20 km sandy coastline is of strong interest from the perspectives of beach amenity tourism and erosion issues this section of the moroccan coastline has only received little attention in the literature so far and morphosedimentary characteristics as well as wave climate are poorly understood the present paper provides the first extensive description of both wave climate and alongshore variability in the morphosedimentary behavior of these wave dominated beaches combined with accurate topographic surveys 9 year long global wave model output time series and subsequently driven empirical longshore drift formula and shoreline change measurements from aerial photographs results show that the coast is mainly exposed to high energy low steepness nw waves mostly during the october march period generated in the north atlantic by eastward traveling low pressure systems given the shoreline orientation northward and southward longshore drift components generated by this wave regime nearly balance in contrast the lower energy higher steepness n nw wave regime april september period contributes to an overall quantity of sand being transported southward similar to the yearly averaged net longshore drift beaches are mostly of the double barred intermediate type the southern beaches exhibit persistent rhythmic sandbars and rather steep beachface while the northern beaches are close to the dissipative state despite all the beaches are exposed to the same wave regimes beach states predicted using the dean s number roughly match these observations while previous studies elsewhere had shown that inherited geological factors may overwhelm contemporary dynamics in the determination of beach states here differences are attributed to coastal protection works that appear to be important additional determinants of beach morphology

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

effects of reservoir size and boundary conditions on pore pressure buildup and fault reactivation during co 2 injection in deep geological reservoirs the excessive burning of the fossil fuels has caused severe global climatic changes such as increasing the global temperature causing initiation of the wild fire rising the sea level increasing the floods storms amount of rain and snow one of the effective global mitigation strategies is sequestration of huge quantity of co2 deep below the ground level for a long period of time an important issue is to ensure the permanency and safety of the sequestration process due to the associated pore pressure buildup it is necessary to have correct estimates of the pore pressure buildup ground uplift and re activation of any existing fault during the process of co2 injection and long term storage in this investigation the effects of reservoir size and boundary conditions are investigated by means of geomechanical modeling of the deep biyadh sandstone reservoir in saudi arabia currently carbon dioxide is not injected into the actual biyadh reservoir in this investigative modeling co2 is injected for an injection period of ten years using a single injection well at the center of the reservoir the developed modeling scheme for a single injection well has been extended further to include multiple injection wells for multiple injection wells the reservoir size and locations of injection wells are varied to evaluate their effect on the pore pressure buildup and ground uplift the reservoir stability analysis has been performed using mohr coulomb failure criterion for both small and large reservoir models with the same injection parameters the simulation results demonstrated that pressure buildup and ground uplift are relatively higher for reservoirs with small sizes and closed boundaries while in the case of large sizes and open boundaries the pore pressure buildup and ground uplift are relatively lower moreover the effect of the reservoir size and boundary conditions on the reactivation of faults during co2 injection has been evaluated the stability analysis performed in this study shows that injecting co2 into larger size reservoir is safer as compared to smaller size reservoir injecting co2 with multiple injection wells will cause pore pressure buildup of huge magnitudes the modeling results show that suggesting a representative volume for the reservoir during co2 injection can under estimate the pore pressure buildup and fault re activation that can cause the reservoir failure and leakage of the stored co2

sediment supply to beaches cross shore sand transport on the lower shoreface many beaches have been built by an onshore supply of sand from the shoreface and future long term coastal evolution critically depends on cross shore sediment exchange between the upper and the lower shorefaces even so cross shore sediment supply remains poorly known in quantitative terms and this reduces confidence in predictions of long term shoreline change in this paper field measurements of suspended sediment load and cross shore transport on the lower shoreface are used to derive a model for sediment supply from the lower to the upper shoreface at large spatial and temporal scales data collection took place at five different field sites that exhibit a wide range of wave conditions and sediment characteristics data analysis shows that both suspended sediment load and cross shore sediment transport scale with the grain related mobility number which ranged up to 1000 in the measurements while the effect of orbital velocity skewness is more limited a 1 year long simulation of sediment transfers between the lower and the upper shorefaces on a natural beach compares well with transport rates estimated from long term bar migration patterns and aeolian accretion on the same beach

shoreline change analysis and its application to prediction a remote sensing and statistics based approach abstract shoreline change analysis and prediction are important for integrated coastal zone management and are conventionally performed by field and aerial surveys this paper discusses an alternative cost effective methodology involving satellite remote sensing images and statistics multi date satellite images have been used to demarcate shoreline positions from which shoreline change rates have been estimated using linear regression shoreline interpretation error uncertainty in shoreline change rate and cross validation of the calculated past shorelines have been performed using the statistical methods namely regression coefficient r 2 and root mean square error rmse this study has been carried out along 113 5 km of coast adjoining bay of bengal in eastern india over the time interval 1973 to 2003 the study area has been subdivided into seven littoral cells and transects at uniform interval have been chosen within each cell the past and future shoreline positions have been estimated over two time periods of short and long terms in three modes viz transect wise littoral cell wise and regionally the result shows that 39 of transects have uncertainties in shoreline change rate estimations which are usually nearer to cell boundaries on the other hand 69 of transects exhibit lower rmse values for the short term period indicating better agreement between the estimated and satellite based shoreline positions it is also found that cells dominated by natural processes have lower rmse when considered for long term period while cells affected by anthropogenic interventions show better agreement for the short term period however on regional considerations there is not much difference in the rmse values for the two periods geomorphological evidence corroborates the results the present study demonstrates that combined use of satellite imagery and statistical methods can be a reliable method for shoreline related studies

on the application of static equilibrium bay formulations to natural and man made beaches crenulate shaped bays are common features found all around the world the most widely used formulation for representing this kind of bay is the parabolic approach proposed by hsu and evans institution of civil engineers proc london england 87 1989 556 who suggested a methodology to test and predict the stability of static equilibrium shapes in natural and man made bays based on an analytical model of null drift current and using an empirical approach a modified methodology is proposed the new procedure is able to locate the downcoast starting point of the static equilibrium beach from which the parabolic plan form of hsu and evans is valid this methodology is applied with good results to different natural and man made beaches along the atlantic and mediterranean coasts of spain including tombolo shaped beaches

dynamic equilibrium planform of embayed beaches part 2 design procedure and engineering applications abstract the design of equilibrium beach systems employing beach nourishment techniques in conjunction with coastal support structures has received increased interest from coastal engineers in recent years one such solution to remedy coastal erosion problems is to design an equilibrium pocket beach in order to stabilize the shoreline such coastal landforms may exist in nature in static or dynamic equilibrium states the concept of the static equilibrium planform sep has received much more attention from coastal engineers than that paid to the dynamic equilibrium planform dep this paper presents a design procedure for embayed beaches in dynamic equilibrium which have a specific net littoral drift rate the proposed methodology employs the net sediment transport rate passing through the bay together with the time series of the wave climate impinging on the beach in order to compute the angle d this angle represents the difference in degrees between the direction of the mean wave energy flux at the diffraction point ef and the orientation of the dynamic equilibrium beach db to be utilized in a newly derived dep formula to predict the shoreline shape in the long term the procedure was applied and validated using prototype bays in dynamic equilibrium with different net sediment transport rates along the brazilian coast producing good results furthermore it was employed as a tool to investigate the influence of changes in the net annual littoral drift rate on the dep shape in a case study along the spanish coast taken together these confirm its utility as a valuable tool for coastal management and engineering practice

post earthquake coastal evolution and recovery of an embayed beach in central southern chile abstract earthquakes and tsunamis are significant factors for change along active margin shores and influence coastal evolution the chilean coast was affected in 2010 by a subduction earthquake with a magnitude of mw 8 8 and also by a trans pacific tsunami which generated violent geomorphologic changes and damaged homes following these events the magnitude of the changes which affect chile s central southern coast 37 s and the role of subduction earthquakes in coastal evolution on a historical scale were investigated at lebu bay an embayed beach data were generated for variations in time and space along the shoreline topographical and bathymetric changes in the bay and for morphodynamic littoral processes logarithmic and parabolic models were applied to the shoreline along with map overlays in order to determine changes the shoreline processes were analyzed based on statistics for waves tides and sediment transport for pre and post tsunami conditions an average accretion rate of 2 80 m year 1984 2010 was established for the shoreline with a strong trend towards accretion in the last 30 years a parabolic function best represented the general form of the shoreline although the presence of a river in the concave zone affected the fit in this sector two factors controlled historical changes on the beach one of anthropic origin in addition to the earthquake and tsunami on february 27th 2010 the post earthquake recovery was fast and currently the beach is in a stable condition despite the inter seismic subsidence process previous to the event this coastal system showed a high resilience in the face of coastal geomorphological changes induced by high impact natural disturbances however the opposite occurred in relation to changes induced by anthropogenic disturbances

sand budgets at geological historical and contemporary time scales for a developed beach system saco bay maine usa abstract saco bay hosts one of the largest sand beach and salt marsh systems in northern new england usa unsuccessful remedies for chronic beach erosion have generated controversy and differing theories regarding 1 the source s of sand to the bay 2 the sand transport paths and 3 the role of jetties in beach erosion we constructed a sand budget for the bay by evaluating the past and present sand transport pathways fluxes and reservoir volumes side scan sonar and bottom samples were employed to map the offshore areas seismic reflection profiles and vibracores were used to measure the volume of offshore sand on land ground penetrating radar and cores constrained the sand volume and stratigraphy time series maps and aerial photographs provided data on historical sand movement and current meters and recent harbor dredge data allowed contemporary sand movement to be estimated in the saco river estuary at the present time 56 million m3 of sand reside in the shoreface and 22 million m3 of sand are beneath the barrier beach and dunes the saco river has been the major source of sand to the bay providing an estimated 10 000 16 000 m3 of sand per year the net direction of sand movement is to the north where river derived sand has historically fed growth of barrier spits construction of the north jetty at the saco river mouth profoundly altered the prehistoric patterns of sand movement and storage in the bay causing the northward migration of almost 6 million m3 of sand between 1867 and 1955 contemporary dredging of tidal inlets involves sand volumes approximately equal to the influx of sand delivered by the saco river

slip distribution of the february 27 2010 mw 8 8 maule earthquake central chile from static and high rate gps insar and broadband teleseismic data 1 the shallow depth underthrust earthquake of february 27 2010 mw 8 8 ruptured the subduction plate interface in central chile between 34 s and 38 s we retrieve the spatial and temporal distribution of slip during this mega earthquake through a joint inversion of teleseismic records insar and high rate gps hrgps data additionally our model is shown to agree with broadband surface waves rupture initiated at about 32 km depth and propagated bilaterally resulting in two main slip zones located ssw and nne of the hypocenter nucleation did not take place within or at the edge of one of these main asperities but in between during the first 30s slip propagated predominantly southwards later on the rupture evolved more slowly and more symmetrically eventually the northern asperity became predominant with maximum slip reaching about 20 m most of the seismic moment was released within 110s a relatively short time explained by the bilateral propagation the overall average rupture velocity is 2 6 km s but propagation occurred initially faster towards the south 3 2 km s large slip did not reach the trench a result consistent with the moderate size of the tsunami down dip rupture stopped at about 50 km depth in agreement with the lower limit of the locked zone inferred by ruegg et al 2009 from pre seismic gps data

limited overlap between the seismic gap and coseismic slip of the great 2010 chile earthquake the mw 8 8 chile earthquake on 27 february 2010 occurred in a broad region where tectonic loading has been accumulating since the great 1835 earthquake a joint inversion of tsunami and geodetic data suggests that the 2010 earthquake rupture only partly overlapped with the zone of preseismic locking

a new model for predicting three dimensional beach changes by expanding hsu and evans equation the empirical bay shape model proposed by hsu and evans in 1989 for predicting the static planform of a pocket beach is expanded to enable the calculation of three dimensional beach changes on a pocket beach with a seawall the original formulation was developed on the basis of a second order regression analysis unlike the one line model of shoreline changes the model of hsu and evans does not require repeated calculations of the wave field and shoreline position because it was derived on the assumption of null sediment movement within a pocket beach in static equilibrium hence without the need of applying the continuity condition of total sand volume in the calculation the expanded model proposed by the present authors satisfies the total sand budget on a pocket beach by taking into account the concept of depth change due to longshore sand transport model tests were carried out and the new model was further applied to the beach changes at kemigawa on the northeast of tokyo bay in chiba prefecture as well as at oarai in ibaraki prefecture japan on both locations seawall has been installed as countermeasures against beach erosion where wave sheltering effect of the main breakwater and beach changes in front of the seawall has also been observed with this expansion the present model can be applied to predict the three dimensional beach changes on a coast with seawall on a pocket beach

far field tsunami simulations of the 1755 lisbon earthquake implications for tsunami hazard to the u s east coast and the caribbean article i nfo the great lisbon earthquake of november 1st 1755 with an estimated moment magnitude of 8 5 9 0 was the most destructive earthquake in european history the associated tsunami run up was reported to have reached 5 15 m along the portuguese and moroccan coasts and the run up was significant at the azores and madeira island run up reports from a trans oceanic tsunami were documented in the caribbean brazil and newfoundland canada no reports were documented along the u s east coast many attempts have been made to characterize the 1755 lisbon earthquake source using geophysical surveys and modeling the near field earthquake intensity and tsunami effects studying far field effects as presented in this paper is advantageous in establishing constraints on source location and strike orientation because trans oceanic tsunamis are less influenced by near source bathymetry and are unaffected by triggered submarine landslides at the source source location fault orientation and bathymetry are the main elements governing transatlantic tsunami propagation to sites along the u s east coast much more than distance from the source and continental shelf width results of our far and near field tsunami simulations based on relative amplitude comparison limit the earthquake source area to a region located south of the gorringe bank in the center of the horseshoe plain this is in contrast with previously suggested sources such as marques de pombal fault and gulf of cadiz fault which are farther east of the horseshoe plain the earthquake was likely to be a thrust event on a fault striking 345 and dipping to the ene as opposed to the suggested earthquake source of the gorringe bank fault which trends ne sw gorringe bank the madeira tore rise mtr and the azores appear to have acted as topographic scatterers for tsunami energy shielding most of the u s east coast from the 1755 lisbon tsunami additional simulations to assess tsunami hazard to the u s east coast from possible future earthquakes along the azores iberia plate boundary indicate that sources west of the mtr and in the gulf of cadiz may affect the southeastern coast of the u s the azores iberia plate boundary west of the mtr is characterized by strike slip faults not thrusts but the gulf of cadiz may have thrust faults southern florida seems to be at risk from sources located east of mtr and south of the gorringe bank but it is mostly shielded by the bahamas higher resolution near shore bathymetry along the u s east coast and the caribbean as well as a detailed study of potential tsunami sources in the central west part of the horseshoe plain are necessary to verify our simulation results

development of a river delta a case study of cimanuk river mouth indonesia this paper describes delta development processes with particular reference to cimanuk delta in indonesia cimanuk river delta the most rapidly growing river delta in indonesia is located on the northern coast of java island the delta is subject to ocean waves of less than 1 m height due to its position in the semi enclosed java sea in the indonesian archipelago the study has been carried out using a hydrodynamic model that accounts for sediment movement through the rivers and estuaries as an advanced approach to management of river deltas a numerical model namely mike 21 is used as a tool in the management of cimanuk river delta from calibration and verification of hydrodynamic model it was found that the best value of bed roughness was 0 1 m for the sediment transport model the calibration parameters were adjusted to obtain the most satisfactory results of suspended sediment concentration and volume of deposition by comparing the computed and observed data in the calibration the best values of critical bed shear stress for deposition critical bed shear stress for erosion and erosion coefficient were 0 05 n m 2 0 15 n m 2 and 0 00001 kg m 2 s 1 respectively the calibrated model was then used to analyse sensitivity of model parameters and to simulate delta development during the periods 1945 1963 and 1981 1997 it was found that the sensitive model parameters were bed shear stresses for deposition and erosion while the important model inputs were river suspended sediment concentration sediment characteristics and hydrodynamic the model result showed reasonable agreement with the observed data as evidenced by field data the mathematical model proves that the cimanuk river delta is a river dominated delta because of its protrusion pattern and very high sediment loads from the cimanuk river it was concluded that 86 of sediment load from the cimanuk river was deposited in the cimanuk delta copyright 2008 john wiley sons ltd

comment on application of the parabolic bay shape equation to sand and gravel beaches on mediterranean coasts by schiaffino et al 2011 abstract the authors have provided an interesting proposal for modifying existing methods for predicting the shape of equilibrium bays they have proposed separate formulae for sand and gravel beaches based on an analysis of beaches across the mediterranean and an optimised fitting procedure this discussion explores the applicability of the proposed model in the context of the uncertainties in specifying the key parameters

morphodynamics of structurally controlled headland bay beaches in southeastern brazil a review abstract this paper presents a comprehensive review on the interaction between hydrodynamic processes beach morphology and sedimentology at large scale coastal behaviour along the coastline of santa catarina between laguna and sao francisco island a microtidal east coast swell environment with headland and bay geomorphologies the parabolic bay shape equation has proven to be a convenient and practical tool for studying the stability of the headland bay beaches tombolos and salients in santa catarina the beaches exhibit different patterns of sediment removal as a function of the degree of beach curvature in highly curved beaches there is a well developed shadow zone and a range of morphodynamic conditions from a sheltered low energy beach adjacent to the downdrift headland to a high energy exposed beach on the straight end of the headland bay beach the less curved beaches instead tend to show more uniform behaviour since they are directly exposed to incident waves there is no obvious relationship between average wave height and mean grain size showing the importance of sediment source to characterize the sedimentary distribution patterns in the study area the analysis of beaches showed that beach morphodynamics and sequence profiles for a bay headland coast in a microtidal east coast environment is a function of geological inheritance e g distance between headlands and orientation nearshore and inner shelf morphology coastal plain morphology and sediment source and hydrodynamic factors wave conditions oceanic wave exposure and relative tidal range

dynamic equilibrium planform of embayed beaches part 1 a new model and its verification abstract equilibrium beach formulations are useful tools for diagnosing and managing coastal engineering problems providing solutions for beach erosion problems headland bay beaches hbbs can be used as equilibrium coastal systems for stabilizing coastlines and mitigating erosion problems these embayed beaches may exist in a state of static or dynamic equilibrium throughout the literature several equations can be found for obtaining the static equilibrium planform sep of headland bay beaches hbbs with almost negligible net littoral drift rates however the formulations used to define the dynamic equilibrium planform dep of embayed beaches with specific net sediment transport rates are scarce and based on a limited number of studies this paper proposes a new derived formula for obtaining the planform shape of hbbs in dynamic equilibrium conditions the formula represents a general form of the parabolic bay shape equation pbse with modified coefficients as a function of both the wave obliquity and the net littoral drift rate passing through the bay q the angular difference d between the direction of the mean wave energy flux at the diffraction point of the headland and the beach orientation down coast is also incorporated in the proposed formula the model was verified against natural hbbs in dynamic equilibrium with different net littoral drift rates along the brazilian coast producing good results

a simple relationship for crenulate shaped bay in static equilibrium a crenulate shaped bay is always formed on a sedimentary coast between headlands the planform of bays in static equilibrium has received attentions since 1940s a number of empirical models and formulations have been proposed to describe it however many researchers and practitioners commented that inconvenience and uncertainties might be encountered in determining the two parameters of these models i e the control line of bay and the incident wave obliquity this study shows that the parallel indentation of a crenulate shaped bay to its upcoast headland could be taken as an intrinsic parameter in the description of the bay planform with a straight downcoast segment this approach leads to a simple formula of the shape of such bayed beaches the proposed relationship is verified with the data of bayed beaches in many parts of the world

land level changes produced by the mw 8 8 2010 chilean earthquake we observed vertically displaced coastal and river markers after the 27 february 2010 chilean earthquake moment magnitude mw 8 8 land level changes range between 2 5 and 1 meters evident along an approximately 500 kilometers long segment identified here as the maximum length of coseismic rupture a hinge line located 120 kilometers from the trench separates uplifted areas to the west from subsided regions a simple elastic dislocation model fits these observations well model parameters give a similar seismic moment to seismological estimates and suggest that most of the plate convergence since the 1835 great earthquake was elastically stored and then released during this event

central chile finally breaks chile is the site of some of the largest earthquakes in the world on average a magnitude 8 earthquake occurs there every 10 years or so these earthquakes take place in the subduction zone either as interplate ruptures at the interface between the south american and nazca plates or as intraplate events within the subducted nazca plate a few times in every century massive plate interface earthquakes break several hundred kilometers in a single shock this is what happened on 27 february 2010 when a major earthquake magnitude 8 8 occurred in the maule and biobio regions in central chile see the first figure this region had last experienced a major subduction earthquake in 1835 when darwin 1 visited the area as part of his voyage on the beagle his description of the earthquake inspired many seismologists and historians of chilean earthquakes 2 3

hydrocarbons in bivalve mollusks of port valdez alaska consequences of five years permitted discharge petroleum hydrocarbons were investigated in mytilus edulis and macoma balthica at six intertidal sites in port valdez alaska after three to five years of oil terminal operation information about the concentrations of total hydrocarbons unresolved complex mixture normal alkanes isoprenoids olefins hopanes and polycyclic aromatic hyrocarbons shows that petroleum accumulation in these bivalve mollusks is greatest at the valdez municipal boat harbor and a crude oil terminal which has been permitted to discharge 170 kg oil day 1 accumulation two to ten fold less were observed at 3 km from the terminal and boat harbor the temporal trends in petroleum hydrocarbon concentrations in m edulis and m balthica reflect the effects of selective retention and depuration of different hydrocarbon classes as well as variation in hydrocarbon sources it is not clear whether the petroleum concentrations in port valdez bivalves had reached steady state by 1982 the final sampling time reported here

rocky coasts their role as depositional environments abstract the role of rocky coasts as depositional environments has been generally neglected by rock and depositional coast workers although rock coasts can be hostile sedimentary environments they frequently host a variety of deposits consisting of mixes of boulders and megaclasts to sand and cobbles these deposits include pockets of sand and pebble trapped in topographic depressions or at the foot of scarps and cliffs isolated boulders pocket beaches trapped between headlands and sand to boulder beaches in shallow bays exposed to strong wave action the tectonic setting which is reflected in the degree of geological heterogeneity alongshore together with the wave regime and other elements of the morphogenic environment help to determine the amount and mobility of the sediment and consequently whether it plays an essentially abrasional or protectional role many beaches have a resistant rock foundation which will modulate their response to rising sea level and possibly increased storminess during this century wave refraction and temporal and spatial changes in sediment abrasional and protectional efficacy influence the development of crenulated planforms on coasts with a high degree of geological heterogeneity and possibly on more geologically homogeneous coasts with longshore variations in cliff height or in the amount of sediment theory suggests that these coasts may develop equilibrium planforms with uniform rates of erosion in bays and on headlands or they may undergo a series of cyclical transformations involving alternating increases and decreases in the depth of the bays relative to the headlands