bluuebunny/crossref_metadata_2025 huggingface dataset:
OPTIMUM CONDITION FOR STABILTY OF AN ARTIFICIAL BEACH WITH A GRAVEL FILTER LAYER UNDER IRREGULAR WAVE ACTION
Authors: Tsujimoto Gozo , Hosoyamada Tokuzo , Kakinoki Tetsuya
Published: October 2012

The safety of a fail-safe artificial beach was studied. Beach profile changes and the onshore-offshore distribution of the sand particle size were measured in a water flume. Under the action of erosive waves, sand particles are deposited on the run-up area. Because of the increasing permeability of the filter layer, the beach profile can be in equilibrium. A filter layer promotes the sorting of sand particles, and depositional waves deposit coarse sediments on the onshore side and fine sediments on the offshore side for an erosive-type beach. A filter layer has the potential to change the beach profile without requiring changes in the water level. The permeability of a filter layer has greater effect on the water velocities and water surface in the stage of run- down than in the stage of run-up.
MODELING BIOGEOMORPHOLOGICAL INTERACTIONS IN UNDERWATER NOURISHMENTS
Authors: Borsje Bas , Kruijt Maurits , Werf Jebbe van der , Hulscher Suzanne , Herman Peter
Published: October 2012

To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-Îµ equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.
SORTING AND SELECTIVE MOVEMENT OF SEDIMENT ON COAST WITH STEEP SLOPE- MASUREMENTS AND PREDICTION
Authors: San-nami Toshiro , Uda Takaaki , Serizawa Masumi , Ishikawa Toshinori
Published: October 2012

"Conveyer belts† carrying gravel and fine sand have developed on the Shimizu coast. After the construction of an L-shaped groin to protect the Hagoromo-no-matsu sandy beach located at the northern part of the Shimizu coast, these conveyer belts split into two, inducing longshore and offshore transport, because the seabed topography markedly changes and submarine canyons with a steep offshore slope develop immediately north of the L-groin. Coarse material is transported alongshore and fine material is discharged offshore. Material movement is investigated on the basis of bathymetric survey data and the depth distribution of the grain size of the seabed material. The effect of extending four breakwaters to control the movement of gravel and to stabilize the shoreline downcoast of the L-groin is predicted using the contour-line-change model. The optimum arrangement of breakwaters, along with beach nourishment, is numerically predicted.
QUANTITATIVE PREDICTION OF SAND DISCHARGE INTO SUBMARINE CANYON OFF MORITO RIVER ON SEISHO COAST, JAPAN
Authors: Furuike Kou , Uda Takaaki , Serizawa Masumi , San-nami Toshiro , Ishikawa Toshinori
Published: October 2012

On the Seisho coast, submarine canyons have developed very close to the shoreline and the discharge of fluvial sediment of the Sakawa River into the submarine canyons has been reported, resulting in the net loss of sand into the offshore zone. The beach topography under dynamically equilibrium conditions owing to the sediment supply from the river and the sand loss into the submarine canyons during several thousand years was reproduced using the contour-line-change model considering the grain size composition. Long-term beach changes around the submarine canyons were accurately predicted and the effect of beach nourishment using a mixture of fine and coarse materials was investigated.
WIND TUNNEL STUDY OF SAND TRANSPORT ON SURFACES COMPOSED OF BI-MODAL GRAIN-SIZE DISTRIBUTION
Authors: Harikai Souichi , Kubota Susumu , Hotta Shintaro
Published: October 2012

The transports rates on a sandy bed that grain sizes were bi-modally distributed were experimented in a wind tunnel. The results showed that the transport rate followed a power law and the power was 2.5, and that the threshold shear velocities were the same or somewhat larger than those of the large diameter sand in the mixture.
SAND TRANSPORT BY SURFACE WAVES: CAN STREAMING EXPLAIN THE ONSHORE TRANSPORT?
Authors: Kranenburg Wouter , Ribberink Jan , Uittenbogaard Rob
Published: October 2012

In wave flumes an onshore boundary layer current is present that is not present in oscillating flow tunnels. We investigate numerically the hypothesis that this streaming explains the measured increase of onshore directed sediment transport in flumes over tunnels. In the formulation and validation of the model special attention has been given to the wave-generated net current profile. From model experiments we conclude that the additional current indeed contributes to onshore transport, but can not be the full explanation of the measured differences in transport rates. Other contributing mechanisms are the amplification/reduction of the fall velocity by vertical sediment advection (only relevant for fine grains) and the amplification/reduction of the concentration at maximum onshore/offshore velocity by intra-wave gradients in horizontal sediment flux. The latter contributes, for the investigated cases, to onshore transport with comparable order as the boundary layer current. These conclusions are relevant for further development of parameterizations of wave-induced sediment transport for morphodynamic models.
MODEL FOR PREDICTING BATHYMETRIC AND GRAIN SIZE CHANGES BASED ON BAGNOLD'S CONCEPT AND EQUILIBRIUM SLOPE CORRESPONDING TO GRAIN SIZE COMPOSITION
Authors: Noshi Yasuhito , Uda Takaaki , Serizawa Masumi , Kumada Takayuki , Kobayashi Akio
Published: October 2012

A model for predicting bathymetric and grain size changes considering the equilibrium slopes corresponding to each grain size and its composition was incorporated into the BG model proposed by Serizawa et al. (2007). The model was applied to predict the beach changes at Kemigawa Beach. The cross-shore sorting of sand, in which the grain size gradually decreases with increasing depth, and the formation of a gradually changing longitudinal slope were accurately reproduced. The model was also applied to predict the selective accumulation of fine sand in a navigation channel after dredging and its impact on the nearby coast.
THE DEPENDENCE OF SUSPENDED SAND CONCENTRATION ON THE DEGREE OF STORM DEVELOPMENT
Authors: Kos'yan Ruben , Grune Joachim , Divinsky Boris , Podymov Igor , Vincent Chris , Oumeraci Houcine , Ahmari Alireza
Published: October 2012

The basic purpose of the present research is the establishment of connections between surface waves' spectral characteristics and laws of the bottom material suspension. The basic method is the laboratory experiment that allows controlling the interconnected dynamic parameters of the water environment and processes of bottom deposits transport. It is shown, that observed suspension laws physical preconditions are the nonlinear intrawave interactions and hence the redistribution of waves spectral energy in frequency area.
WAVE BOUNDARY LAYER HYDRODYNAMICS DURING ONSHORE BAR MIGRATION
Authors: Henriquez Martijn , Reniers Ad , Ruessink Gerben , Stive Marcel
Published: October 2012

To study onshore bar migration and the accompanying intra-wave sediment transport a wave flume experiment was conducted. The wave flume had a rigid bottom with a single bar profile. The focus of the experiment was to measure the hydrodynamics in the wave bottom boundary layer. The results show that the skewness of bottom stress is not only related to wave skewness but also to wave asymmetry.
TIME-AVERAGED TURBULENT MIXING AND VERTICAL CONCENTRATION DISTRIBUTION OF HIGH-DENSITY SUSPENSIONS FORMED UNDER WAVES
Authors: Yan Bing , Zhang Qing-He , Lamb Michael
Published: October 2012

We analyzed oscillating flow data from U-tube experiments by Lamb et al. (2004) and found that the time-averaged turbulent kinetic energy (TKE) near bed decreased exponentially with height above the bed in high-density-suspension (HDS) flows under waves, and that the ratios of TKE distributions in the streamwise, cross-stream, and vertical dimensions were constant. Based on the finite-mixing-length theory, a semi-theoretical time-averaged suspended sediment concentration model for HDS was developed. To avoid the stability problems with the numerical solution, a simplified model was also formulated through combing the apparent Fickian diffusivity and the damping function. The comparison between the calculated results and measurements shows both models consider the effect of the sediment-induced stratification well.
SIMULATION OF SORTING SEDIMENTATION IN THE CHANNEL OF HUANGHUA HARBOR BY USING 3D MULTI-SIZED SEDIMENT TRANSPORT MODEL OF EFDC
Authors: Zhang Qinghe , Tan Feng , Han Tao , Wang Xiaoyuan , Hou Zhiqiang , Yang Hua
Published: October 2012

Huanghua Harbor, located in the south-west coast of Bohai Bay, China, has frequently encountered severe channel siltation with sorting sedimentation along the channel during storm events since its construction. For prediction of channel siltation, a 3D numerical model of multi-fraction sediment transport based on the coupling of modified EFDC model and SWAN model is developed to investigate the sediment transport. It is shown from simulated results that the sorted sedimentation in the channel was well simulated in storm events, and the high sediment concentration near sea bed for silty coast during storm process can also be basically reflected by the model.
ANALYSIS OF TEMPORAL VARIATIONS IN TURBIDITY FOR A COASTAL AREA USING THE HILBERT-HUANG-TRANSFORM
Authors: Kato Shigeru , Larson Magnus , Okabe Takumi , Aoki Shin-ichi
Published: October 2012

Turbidity data obtained by field observations off the Tenryu River mouth were analyzed using the Hilbert-Huang Transform (HHT) in order to investigate the characteristic variations in time and in the frequency domain. The Empirical Mode Decomposition (EMD) decomposed the original data into only eight intrinsic mode functions (IMFs) and a residue in the first step of the HHT. In the second step, the Hilbert transform was applied to the IMFs to calculate the Hilbert spectrum, which is the time-frequency distribution of the instantaneous frequency and energy. The changes in instantaneous frequencies showed correspondence to high turbidity events in the Hilbert spectrum. The investigation of instantaneous frequency variations can be used to understand transitions in the state of the turbidity. The comparison between the Fourier spectrum and the Hilbert spectrum integrated in time showed that the Hilbert spectrum makes it possible to detect and quantify the cycle of locally repeated events.
AIRBORNE LIDAR BATHYMETRY APPLIED TO COASTAL HYDRODYNAMIC PROCESSES
Authors: Long Bernard , Aucoin Françis , Montreuil Stéphane , Robitaille Valérie , Xhardé Régis
Published: October 2012

In this study, the possibility to get sedimentological (density, compaction) and hydrodynamical (suspended sediment concentration, turbulence) information from ALB surveys is demonstrated. ALB laser reflectance was found to be higher on the lee-side and on the crest of the ripple bedform than in the trough and on the stoss-side. Moreover, laser reflectance was also found to be higher on "active† subtidal dunes, located within the depth of action of the waves, than on deeper "passive† bedforms. Based on lab experiments conducted in a hydraulic flume under X-ray CT-Scanner, these observations were related to sediment compaction and suspended sediment.
SHORT-TERM SWASH ZONE BEACH PROFILE CHANGE MODEL FOCUSING ON BERM FORMATION AND EROSION
Authors: Suzuki Takayuki , Kuriyama Yoshiaki
Published: October 2012

A short-term swash zone beach profile change model focusing on berm formation and erosion was proposed using a 2.5-year data set of beach profiles and offshore waves. The investigation area was set from the maximum wave run-up position to the shoreline position at the mean tide level. The model was applied for the calculation of three months beach profile change. The results revealed that the model well predicts the beach profile change including the berm formation and erosion in a qualitative sense. Also, the variation trend of the calculated beach slope at the shoreline position of the mean tide level show a good agreement with that of the observed beach slope.
THE EFFECT OF LONGSHORE TOPOGRAPHIC VARIATION ON OVERWASH MODELLING
Authors: McCall Robert Timothy , Plant Nathaniel , Van Thiel de Vries Jaap
Published: October 2012

This paper describes an application of the XBeach model to investigate the effect of longshore topographic variance on overwash. The model is used to simulate the morphological response of an eight- kilometer section of Santa Rosa Island, Florida, due to Hurricane Ivan (2004). The influence of longshore scales in the bed elevation is investigated by comparing the morphological response of the reference simulation to the morphological response of six sensitivity simulations in which the initial bed elevation was modified to remove longshore topographic variance. It is shown that the morphological response of the foreshore-foredune area to Hurricane Ivan is not influenced strongly by the initial longshore bed variance. The morphological response of the back barrier and the back barrier bay to Hurricane Ivan is influenced by features on the back barrier with longshore length scales of 100 - 500 meters, which hamper the flow across the island during inundation overwash. It is noted that these results may vary for other overwash regimes.
APPLICATION OF XBEACH TO MODEL STORM RESPONSE ON A MACROTIDAL GRAVEL BARRIER
Authors: Ruiz de Alegria-Arzaburu Amaia , Williams Jon J , Masselink Gerhard
Published: October 2012

The process-based XBeach numerical model has been used to simulate storm-induced morphological response on a macrotidal gravel barrier located in southwest UK. Using well-established parameterisation to define all relevant hydrodynamic, groundwater and sediment processes, the model was applied in 1D mode to simulate observed storm-induced beach profile responses. Investigations showed that the morphological response of the beach was best modelled using a total drag coefficient, CD, of 0.007, and a hydraulic conductivity, K, of 0.05ms-1. Results obtained from simulations with and without beach groundwater highlighted the need to account for groundwater effects when modelling morphological changes on gravel beaches. The model has been found unable of reproducing the formation of a berm, thus, beach recovery conditions cannot be modelled. This is mainly attributed to the fact that XBeach models long waves rather than individual waves, and thus it cannot simulate individual swash events that contribute to onshore sediment transport and berm accretion. However, the model is shown to provide good estimates of post-storm gravel beach/barrier profiles, and to define the threshold for overwash occurrence. Both attributes have utility in a range of practical coastal engineering and management applications.
MODELLING INFILTRATION ON GRAVEL BEACHES WITH AN XBEACH VARIANT
Authors: Jamal Mohamad Hidayat , Simmonds David J. , Magar Vanesa , Pan Shunqi
Published: October 2012

Coarse-grained beaches are particularly prevalent in the UK, composed of accumulations of either gravel, or mixed sand and gravel sediments. Understanding and predicting their morphological behaviour in response to short-term and long-term forcing has been the subject of recent research. Despite the focus on sandy beaches, it is important to understand that the balance of processes that govern different behaviour between sandy and gravel beaches. In this study we show how a public domain numerical model, XBeach, developed for sandy environments (Roelvink et al., 2009) can be modified for use in predicting the cross-shore profile changes of gravel beaches. Improvements investigated here include: use of Lagrangian interpretation of velocity in place of Eulerian for driving sediment movement; incorporation of Packwood's (1983) pragmatic model of infiltration in the unsaturated area of the swash region; introducing of new morphological module based upon Soulsby's (1997) sediment transport equation for waves and currents. These changes are suggested in order to significantly improve the application of this model to gravel beaches, especially with regard to swash velocity asymmetry which is responsible for development of the steep accretionary phase steep berm above waterline. The results from the model agree well with the measured experimental data and improve upon the results presented by Pedrozo-Acuña et al. (2006).
SEDIMENT EXCHANGE BETWEEN THE SUB-AQUEOUS AND SUB-AERIAL COASTAL ZONES.
Authors: De Vries Sierd , De Schipper Matthieu , Stive Marcel , Ranasinghe Roshanka
Published: October 2012

The coastal system consists of a sub-aqueous and a sub-aerial zone which can be separated by a border. At this border sediment exchange takes place from one zone to the other. This paper hypothesizes that conditions and therefore sediment exchange at this border are dependent on active profile characteristics. To analyze morphological developments due to combined marine and aeolian processes data acquired at a measurement site located along the southwest Holland coast is exploited. Based on the monthly morphological profile measurements the border between the marine and aeolian zone is determined. It is found that during accretive conditions the vertical location of this border, and with that the conditions near the border, is dependent not on the foreshore slope of the surf/swash zone as expected but on the slope of the entire active profile.
STORM BEACH BUFFER REQUIREMENT FOR STORM WAVES FROM A TROPICAL CYCLONE
Authors: Lee Fang Chun , Lin Wen Hua , Hsu John R.-C.
Published: October 2012

Storm beach buffer, being different from the coastal set back currently in place in many countries in the world, is the provision of a sufficient beach width to safe guard against the onslaught of a fierce storm. The extent of this requirement is tentatively assessed using the SBEACH module in the CEDAS package. The inputs for the SBEACH module include berm width, medium sand grain diameter, beach slope, design water level and wave conditions; while the outputs consist of a range of characteristic parameters for the change in beach profile, especially berm erosion and bar formation resulting from a storm of different return periods. After having systematically performed a series of numerical studies, we may conclude that: (1) Berm erosion increases and bar becomes further offshore as the storm return period increases on a beach with identical sand grain size (i.e., non-dimensional fall velocity), or as sand grain dimension reduces; (2) Higher storm waves result in a larger bar to form quicker and cause wave breaking on the bar crest which could reduce the wave energy and limit the extent of the subsequent berm erosion; (3) Empirical equations can be derived to calculate the storm beach buffer width; and (4) A larger buffer is required for a beach with smaller sand grain, in order to effectively absorb the storm wave energy. The results presented in this paper can be used to assist in a beach nourishment project for shore protection and the design of a recreational beach.
THE EFFECT OF THE LONGSHORE DIMENSION ON DUNE EROSION
Authors: Thiel de Vries Jaap van , Dongeren Ap van , McCall Robert , Reniers Ad
Published: October 2012

The effect of the longshore dimension on dune erosion is examined numerically with a 2DH process-based model XBeach. Exploratory simulations are presented to examine longshore effects due to directionally spread waves, longshore variation in topography and longshore variation in bathymetry. The simulations reveal that alongshore sediment exchange during a storm surge affects the cross-shore development of the foreshore and can locally increase or decrease storm impact on dunes substantially. This finding illustrates that dune erosion on natural coasts (which are never cylindrical or subject to longcrested waves) is an inherent 2D process for which 1D cross-shore models do not suffice without further assumptions.
EXPERIMENTAL ANALYSIS OF EROSIVE COHESIVE COASTLINE MORPHOLOGY
Authors: Caplain Bastien , Astruc Dominique , Regard Vincent , Moulin Frédéric
Published: October 2012

Laboratory experiments have been performed in a wave flume to investigate the coastal cliff recession under regular waves forcing. The different processes of the cliff erosion cycle are described and we focus on bottom evolution, which seem mostly depend on the surf similarity parameter Î¾. We observed steep planar (Î¾ > 0.7), gentle planar (0.5 < Î¾ < 0.7) and bared (Î¾ < 0.5) profiles. We noticed different sandbar dynamics including either steady or unsteady self-sustained oscillating states. Then we estimate the role of the self-organized material on the cliff recession rate. We show that the cliff erosion increases with the wave energy flux and is stronger for a gentle planar profile than for a bared profile of bottom morphology. However, the cliff recession rate as a function of the cliff height is not monotonic due to a different dynamics of bottom morphologies.
MORPHOLOGICAL DEVELOPMENT OF THE RIF AND THE ENGELSMANPLAAT, AN INTERTIDAL FLAT COMPLEX IN THE FRISIAN INLET, DUTCH WADDEN SEA
Authors: Wang Zheng Bing , Oost Albert P.
Published: October 2012

The Rif and the Engelsmanplaat form together a supra- to intertidal flat-complex at the fringe of the ebb-tidal delta and the back barrier area in the Frisian Inlet, located between the Dutch Wadden Sea Islands Ameland and Schiermonnikoog. The complex divides the Frisian Inlet into the Pinkegat Inlet in the west and the Zoutkamperlaag Inlet in the east. During the last decades the Engelsmanplaat has been suffering from serious erosion. This paper presents a study meant to find the causes for the recent erosion, especially to answer the question if the erosion is related to the human interferences in the area. The study is based on literature survey, data analysis and modelling of hydrodynamic processes. It is concluded that the recent erosion fits into the pseudo-cyclic development of the intertidal flat complex. However, the period of erosion may have been longer than normal and the rate of erosion may have been higher than normal. It is also concluded that such abnormal development is probably effects of the closure of the Lauwerszee in 1969 and not due to land subsidence caused by gas mining.
NUMERICAL MODEL OF 3D MORPHODYNAMIC AFTER OFFSHORE NOURISHMENT
Authors: Kuroiwa Masamitsu , Shibutani Yoko , Matsubara Yuhei , Kuchiishi Takayuki , Abualtyef Mazen
Published: October 2012

A three-dimensional model of morphodynamics after offshore nourishment was developed. In the presented model, the 3D beach evolution model that is not only after nourishment but also taking into account the nourishment process of injected sand material. In order to consider the injected process of sand, the computation using the advection-diffusion equation for suspended sediment concentration was adapted in the model. The presented model was applied to an idealized beach with two groins in order to investigate the performance of the model, and then, the model was applied to a field observation result for shoreface nourishment carried out at the Egmond aan Zee in the Netherlands. Finally, the applicability of the presented model was discussed from the computed results.
SAND ACCUMULATION IN WAVE-SHELTER ZONE OF OHARAI PORT AND CHANGE IN GRAIN SIZE OF SEABED MATERIALS ON NEARBY COAST
Authors: Matsu-ura Takeo , Uda Takaai , Kumada Takayuki , Sumiya Michio
Published: October 2012

Beach changes around Oharai Port facing the Pacific Ocean were investigated using bathymetric survey data collected over 25 years between 1979 and 2004. Between the south and offshore breakwaters of Oharai Port, 1.50×106 m3 of fine sand was deposited in this period, i.e., at an annual rate of 6.0×104 m3/yr, which was originally supplied from the Naka River 3 km north of the port. Also in the wave-shelter zone of the offshore breakwater south of the port, 7.0×106 m3 of fine sand was deposited between 1979 and 2004 at an annual rate of 2.8×105 m3/yr, which was transported by the northward longshore sand transport induced from outside to inside the wave-shelter zone of the offshore breakwater, resulting in severe beach erosion on the south coast outside the wave-shelter zone. Taking into consideration the fact that sand transport to the Kashimanada coast is now completely obstructed by the port breakwaters, sand bypassing and sand back passing to the coast from the sand deposition zone of Oharai Port are required.
PHYSICAL MODELING OF SCOUR AROUND TRIPOD FOUNDATION STRUCTURES FOR OFFSHORE WIND ENERGY CONVERTERS
Authors: Stahlmann Arne , Schlurmann Torsten
Published: October 2012

As a step to further develop the share of renewable energies, the first German offshore test site alpha ventus has been installed in the North Sea in 2009 in water depths of 30 m, where experience shall be gained and made available for
future offshore wind farms. Regarding converter foundations in deep water, it is well known that in most cases scour phenomena occur around the structures. Due to the complexity of the tripod foundations, significant knowledge gaps in scour progression in general and especially in detail as well as its probable effects on the stability and durability are given. Therefore, investigations on scouring phenomena around complex foundation structures like the tripod are
carried out within the research project. The investigation method consists of a unique combination of local scour monitoring as well as physical and numerical modeling, whereas the physical modeling part was carried by means of 1:40 laboratory tests and 1:12 large-scale physical model tests in wave flumes. The results show that scours around the tripod foundation do not only occur directly around the foundation piles, but also in the near-field of the structure. Compared to first in-situ measured scours in the test site, at least a good qualitative agreement of the modeled scour depths and evolutions could be shown.
MODELING MORPHOLOGICAL EVOLUTION IN THE VICINITY OF COASTAL STRUCTURES
Authors: Nam Pham Thanh , Larson Magnus , Hanson Hans
Published: October 2012

A numerical model of beach topography evolution was developed. The model includes five sub-models: random wave transformation model, surface roller model, wave-induced current model, sediment transport model, and morphological change model. The model was validated by two unique high-quality data sets obtained from experiments on the morphological impact of a detached breakwater and a T-head groin in the basin of the Large-scale Sediment Transport Facility (LSTF) at the US Army Corps of Engineer Research and Development Center in Vicksburg, Miss. The simulations demonstrated that the model well reproduced the wave conditions, wave-induced currents, and morphological evolution in the vicinity of the structures.
LONG-TERM APPROACH FOR MORPHODYNAMIC PROCESSES IN TIDAL MARSH-WATERCOURSES
Authors: Donner Monika , Pasche Erik , Nehlsen Edgar
Published: October 2012

Tidal marsh-watercourses form a significant link between marine and fluvial environment. As consequence bi-directional forces due to asymmetric tides and inland runoff deform morphodynamic processes with presence of cohesive and organic sediment. In combination with the high inter-tidal area proportion and additional anthropogenic deformations special requirements for the long-term approach restrict existing methods. This paper exposes significant processes in tidal marsh-watercourses based on a research study. The identified processes were integrated into a specified long-term approach taking these special requirements into account. By using a numerical model the range of uncertainty for different impacts were considered and results in a long-term riverbed evolution.
PREDICTION ON MORPHOLOGICAL RESPONSE OF DREDGED SAND-BORROW PITS
Authors: Lu Qimiao , Nairn Robert B.
Published: October 2012

Dredged pits in coastal zones are generally required for sand borrows for beach nourishment. The morphological response of borrow pits is important to evaluate future environmental impacts and potential impacts to adjacent seabed infrastructure such as pipelines. This paper will present the development of a simple concept model for the prediction of morphological response of dredged pits. A 3D hydrodynamic and sediment transport model was applied to verify the developed simple concept model. The case study for a sand-borrow pit on the offshore of Louisiana at the Atlantic coast of USA will be updated. The strengths and limitations of the developed model will be also discussed.
INFLUENCE OF TURBULENCE CLOSURE ON ESTUARINE SEDIMENT DYNAMICS AND MORPHODYNAMICS
Authors: Amoudry Laurent , Souza Alejandro
Published: October 2012

Turbulence significantly impacts hydrodynamics, mixing and sediment dynamics in coastal environments. We employ a three-dimensional model, the Proudman Oceanographic Laboratory Coastal Ocean Modeling System (POLCOMS), to investigate the effects of implementing various turbulence closure schemes on sediment dynamics and morphodynamics. This model is applied to an idealized estuary, which is represented by a straight rectangular basin. A simple tidal flow is forced at one end and a constant river flow is imposed at the other. Most of the turbulence closure schemes employed are implemented via coupling to the General Ocean Turbulence Model (GOTM). Their effects are also compared to the impact of different erosion parameterizations on the numerical results and observed for different sediment properties.
A CASE STUDY OF HYDRODYNAMIC AND MORPHOLOGICAL MODELING OF A RE-MIGRATING INLET
Authors: Sorourian Soroush , Banijamali Babak
Published: October 2012

The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be used as the basis of a fishery port site selection study. The Tang inlet, located on the south-eastern shores of Iran, has so far been experiencing a cyclic migration with a return period of approximately a decade. In order to grasp the essence of the morphological behavior of the inlet, a two-fold site monitoring campaign was performed, consisting of a shoreline evolution study using aerial & satellite imagery for the outside of the bay as well as a sedimentation pattern comparison based on past hydrographical survey results for the inside of the bay utilizing ArcGIS software. Subsequently, numerical modeling of the inlet comprising of nearshore wave transformation, tidal regime of the bay, one-line coastline evolution and two-dimensional sediment transport within the bay was carried out utilizing MIKE 21 package. Ebb channel switching from a westerly to an easterly orientation is deemed to occur due to self-suffocation as a result of the presence of an existing offshore rock formation, as well as the salient making potential of the rock system. On the other hand, the closure of the east-facing channel is mainly attributed to diffraction currents due to Monsoon southerly waves helped by sedimentation load from inside the bay system due to floods & ebb currents.
ASSIMILATING MODELS AND DATA TO ENHANCE PREDICTIONS OF SHORELINE EVOLUTION
Authors: Long Joseph W. , Plant Nathaniel G.
Published: October 2012

A modeling system that considers both long- and short-term process-driven shoreline change is presented. The modeling system is integrated into a data assimilation framework that uses sparse observations of shoreline change to correct a model forecast and to determine unobserved model variables and free parameters. Application of the assimilation algorithm also provides quantitative statistical estimates of uncertainty that can be applied to coastal hazard and vulnerability assessments. Significant attention is given to the estimation of four non-observable quantities using the data assimilation framework that utilizes only one observable process (i.e. ,shoreline change). The general framework discussed here can be applied to many other geophysical processes by simply changing the model component to one applicable to the processes of interest.
ANALYSIS ON PERFORMANCE OF THE EMERGENCY NOURISHMENT PROJECT AT WEST BEACH OF BEIDAIHE, CHINA
Authors: Yang Yanxiong , Zhang Jiabo , Kuang Cuiping , Zhang Yu , He Lulu , Pan Yi , Liu Shuguang
Published: October 2012

Beach erosion is prevalent on China's 18,000 km-long coastline, which has been aggravating due to urban development, river-damming and soil and water conservation projects since late 1970s. Beach erosion threatens the health of beaches of bathing places throughout the world. An effective way to defense the beach erosion is beach nourishment. In this paper, the study on an experimental beach nourishment project, which was conducted to provide data and experience for a large-scale project, was detailed. Field survey was conducted to study the performance of the project. Before and after the project, 8 monitoring profiles had been kept measuring along with the berm positions. The beach profile measurement indicates that after a little retreat the beach got relatively equilibrium, while the berm measurement shown a broadened intertidal zone getting stable eventually. In a word, the filled beach was eroded a little but finally got relatively stable in the survey period.
INCREASED OVERTOPPING SECURITY OF DYKES: A POTENTIAL FOR COMPENSATING FUTURE IMPACTS OF CLIMATE CHANGE
Authors: Niemeyer Hanz Dieter , Kaiser Ralf , Berkenbrink Cordula
Published: October 2012

Anticipated acceleration of sea level rise in combination with expected higher set-up of storm surges will require strengthening of coastal protection structures. Dykes e. g. must then be heightened according to the existing design rules taking only hydrodynamical loads into consideration. Alternatively the development of new design rules taking both hydrodynamical loads and the strength of the available soil for the construction of a dyke might allow the explo-ration of up to now undetected safety margins. In order to explore these possibilities the German Coastal Engineering Research Council has provided the funds for a research project targeting these aims. First results of this project are presented in this paper on the background of achieved improvements for the determination of design wave run-up on coastal and estuarine sea dykes.
ON THE EFFECT OF CURRENT ON WAVE RUN-UP AND WAVE OVERTOPPING
Authors: Lorke Stefanie , Bruning Anja , Van der Meer Jentsje , Schuttrumpf Holger , Bornschein Antje , Gilli Stefano , Pohl Reinhard , Spano Miroslav , Å˜íha Jaromír , Werk Stefan , Schlutter Flemming
Published: October 2012

Intention of the project FlowDike-D is to quantify the impacts of current and wind on wave run-up and wave overtopping and to consider these processes in existing design formulae for estuarine, river and sea dikes. Physical model tests were carried out in the shallow water basin at DHI (Hørsholm/Denmark) for two different dike geometries (1:3 and 1:6 sloped dike). The paper introduces the model setup and test programme followed by a short description of the applied instrumentation. The test results for wave run-up and wave overtopping with oblique and non-oblique wave attack, but without current, correspond well with existing formulae from the EurOtop-Manual (2007). The influence of current parallel to the dike combined with different angles of wave attack on wave overtopping and wave run-up has been quantified. A distinction was made between wave attack with and against the current.
LARGE SCALE WAVE IMPACTS ON A VERTICAL WALL
Authors: Hofland Bas , Kaminski Mirek , Wolters Guido
Published: October 2012

This paper treats new large scale measurements of pressure fields on a vertical wall under wave impacts. These measurements were done in collaboration with the Joint Industry Project Sloshel, aimed at sloshing in LNG tanks. Measurements are presented with a relatively high spatial and temporal resolution. The impacts are created by wave focussing at the wall. By changing the focal point with respect to the wall, the impact type was altered. The influence of the impact type on the pressures and forces on the wall at large scale is thus studied.
2D LARGE-EDDY SIMULATION OF WATER-WAVE IMPACT DURING VIOLENT OVERTOPPING EVENTS
Authors: Lu Xin , Zou Qingping , Reeve Dominic E
Published: October 2012

In this work a newly developed numerical model was employed to conduct comprehensive numerical modeling to investigate the waves overtopping at a vertical seawall, and the associated impact pressures with a certain breaking wave condition. The objective is to qualitative and quantitative understanding of individual violent wave overtopping events on seawalls.
CALCULATION OF PERMEABILITY PARAMETER OF PERFORATED WALL
Authors: Suh Kyung-Duck , Kim Yeul Woo , Ji Chang-Hwan
Published: October 2012

The friction coefficient in the permeability parameter of a perforated wall has been estimated on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To validate the proposed formula, the reflection and transmission coefficients calculated by using the formula are compared with the experimental data for various types of structures including a perforated wall. It is also shown that the proposed formula can be used for irregular waves as well.
HYDRAULIC PERFORMANCE OF ELASTOMERIC BONDED PERMEABLE REVETMENTS AND SUBSOIL RESPONSE TO WAVE LOADS
Authors: Oumeraci Hocine , Staal Tijl , Pfoertner Saskia , Kudella Matthias , Schimmels Stefan , Verhagen Henk Jan
Published: October 2012

Elastomeric bonded permeable revetments, also called PBA (Polyurethane bonded aggregate) revetments, are highly porous structures made of mineral aggregates (e.g. crushed stones) which are durably and elastically bonded by polyurethane (PU). Despite their numerous advantages as compared to conventional revetments and the large experience available from more than 25 pilot projects, physically-based design formulae to predict their hydraulic performance, wave loading and response are still lacking. Therefore, the present study aims at improving the understanding of the processes involved in the interaction between wave, revetment and foundation, based on large-scale model tests performed in the Coastal Research Centre (FZK), Hannover/Germany, and to provide prediction formulae/diagrams. This paper is focused on the prediction of the hydraulic performance (wave reflection, wave run-up and run-down) and the response of the sand core (pore pressure and effective stress) beneath the revetment for a wide range of wave conditions, including the analysis of an observed failure due to transient soil liquefaction.
REASSESSING RELIABILITY BASED ON SURVIVED LOADS
Authors: Schweckendiek Timo
Published: October 2012

The reliability of flood defenses is often dictated by large uncertainties in the hydraulic loading and the structural resistance. Additional information decreases uncertainty, however, acquiring it is often costly. One source of information, even though in many cases readily available, is hardly used - survived loads. This article shows how data on survived load conditions can be incorporated in reliability analysis by means of Bayesian techniques. The theory is illustrated by simple and realistic examples. In contrast to other sources of information, reassessing structures using survived load data always leads to higher reliability or lower probability of failure. Furthermore, attention is given to the expected development of failure in time. This may be relevant for situations, where the safety requirements of a structure are stated in terms of a design or inspection period. For both, re-assessing reliability based on (one time) survived loads as well as the expected
increase of reliability in time, the examples show significant impact. Use of this knowledge, may, consequently, safe cost of construction or reinforcement.
PRESSURE DISTRIBUTIONS ON A VERTICAL BREAKWATER: EXPERIMENTAL
Authors: Perez Dulce Maria , Correa Mariana , Ortega Miguel , Clavero María , Losada Miguel Angel
Published: October 2012

This work studies the horizontal and uplift pressure distributions over a caisson founded on porous materials, and their dependence on the stone diameter and the height of the foundation. For this, tests at a wave flume with an idealized composite breakwater of rectangular section, varying the depth of the foundation of the caisson and the diameter of the stones, were carried on. Eight resistive gauges and eight pressures sensors were used to measure free surface elevations and horizontal and uplift pressure variation, respectively. Results show that: 1) there exist a "saturation† of the reflection coefficient for B/L>0.4, being B the width of the dike and L the wave length, 2) by using the total wave height measured at the toe of the dike in the analysis, the dispersion of the results is significantly reduced; 3) dimensionless run-up and pressures obtained using total wave height mainly depends on the reflection regime and on the relative height of the foundation; 4) maximum uplift and horizontal forces are not always in phase, and three regimes are identified depending on which force dominates; and 5) the relation between the dimensionless forces with the total wave height at the toe of the dike depends mainly on the reflection regime and on the relative foundation height.
SIMULATION OF IRREGULAR WAVE PRESSURE ON PERFORATED BREAKWATERS
Authors: Chen Xuefeng , Li Yucheng , Long Liu
Published: October 2012

In this paper, the wave pressures on the perforated caissons breakwaters are investigated. The front wall of the perforated caissons is usually perforated above a certain water level considering the stability of the structure, and the chamber of the perforated caisson is filled with rock. Based on the RANS and k-ï¥ equations, the numerical method to simulate the interaction of the irregular wave with the perforated breakwaters is researched. Moreover, the wave pressures distribution on the front perforated wall and the back wall are discussed through the numerical calculations, respectively. Then, the simplified formulas to compute the wave pressures on the different position of perforated caisson are obtained from experimental data by using the least-squares method.
EXPERIMENTAL RESEARCH ON PORE PRESSURE ATTENUATION IN RUBBLE-MOUND BREAKWATERS
Authors: Vanneste Dieter F.A. , Troch Peter
Published: October 2012

The paper describes the pore pressure measurements in a small scale breakwater model performed at Ghent University, Belgium. Two phenomena related to the pore pressure distribution within the breakwater are discussed: the amount of energy dissipation through the armour and filter layer (represented by the 'reference pressure') and the exponential pore pressure attenuation inside the core of the breakwater. The test results are compared with results from literature and with the empirical damping model presented by Burcharth et al. (1999) and Troch (2000). Magnitudes of the reference pressures are found to be strongly dependent on the wave steepness. The pore pressure attenuation obtained from the present experiments shows to be in accordance with the empirical damping model. A suggestion is made for a better prediction of the damping coefficient by eliminating the influence of the wave height in the empirical damping model.
OBLIQUE WAVE ATTACK ON CUBE AND ROCK ARMOURED RUBBLE MOUND BREAKWATERS
Authors: Wolters Guido , Van Gent Marcel
Published: October 2012

Stability formulae for armour layers of rubble mound breakwaters are usually being applied assuming perpendicular wave attack. Often it is assumed that for oblique wave attack the reduction in damage compared to perpendicular wave attack is small. This seems however a very conservative assumption. Wave basin tests at Deltares provide information to assess the effects of oblique waves on the stability of rock slopes and cube armoured rubble mound breakwaters. This includes cubes in a single layer and cubes in a double layer. The results show that the few available formulae that include wave obliquity underestimate the effects of oblique wave attack; the observed damage to breakwaters with armour layers of rock and cubes is lower and therefore new stability increase factors and mass reduction factors have been developed. The tests were performed for wave directions between perpendicular (0ï‚°) and 70ï‚°. The results show that large potential savings in diameter and mass can be obtained for large angles of wave obliquity.
MODELS FOR PROFILE CHANGE OF RUBBLE MOUND REVETMENT AND PERFORMANCE EVALUATION
Authors: Ota Takao , Matsumi Yoshiharu , Hirayama Takayuki , Kimura Akira
Published: October 2012

This study deals with modeling for profile change due to damage progression of rubble mound revetment. The model profiles based on the experimental results consist of three datum points and two sine curves corresponding to the degree of deformation of the revetment. The model profiles agree well with the measured profiles. The model profiles are also used in other experiments and a time-averaged numerical model to examine the change of performance due to damage progression. The reflection coefficient and overtopping rate are taken as performance indices. The measured reflection coefficient decreases slightly, but the overtopping rate increases with damage progression of the revetment. The computed reflection coefficient is almost constant and the overtopping rate shows opposite tendency to the experimental result.
STABILITY OF CUBIPOD ARMOURED ROUNDHEADS IN SHORT-CRESTED WAVES. A COMPARISON BETWEEN CUBIPOD AND CUBE ARMOUR STABILITY
Authors: Burcharth Hans Falk , Lykke Andersen Thomas , Medina Josep R.
Published: October 2012

The paper presents a comparison of the stability of concrete cube armour and Cubipod armour in a breakwater roundhead with slope 1:1.5, exposed to both 2-D (long-crested) and 3-D (short-crested) waves. The model tests were performed at the Hydraulics and Coastal Engineering Laboratory at Aalborg University, Denmark. The model tests

showed that Cubipod armour is more stable than cube armour when exposed to longer waves (steepness approx. 0.025) and has equal stability to cubes in shorter waves. The Cubipod armour layer contained due to its high porosity approximately 6-17% less concrete than the cube armour layer. Therefore, it was concluded that per used volume of

concrete the Cubipods perform better than the cubes.