bluuebunny/crossref_metadata_2025 huggingface dataset:
FIELD STUDY OP SURATHKAL BEACH
Authors: Rao P. Suryaprakasa , Kassim P.
Published: February 2019

Beach profile observations and sediment sampling were carried out for six months at frequent intervals to study the seasonal changes of the beach. Iht study is helpful in bringing out the qualitative and quantitative changes of the beach under varying wave and tide conditions. Useful information is obtained and presented regarding i) the maximum rate of erosion 11) the total quantity of material eroded iii) the critical wave steepness values which changed from depositing to eroding nature and iv) the sediment characteristics of the beach.
SEDIMENT DISTRIBUTION AND ITS RELATIONS TO CIRCULATION PATTERNS IN BOLINAS BAY, CALIFORNIA
Authors: Wilde P. , Yancey T.
Published: February 2019

Grain size and heavy mineral analyses of 6 cliff, 12 beach, and 44 marine sediment and rock samples from Bolmas Bay and its surrounding drainage area were done as part of a long term study of sediment transport on the continental shelf off Central California Sediments in the bay are predominately very fine sands Some samples, particularly adjacent to Duxbury Reef on the west, have a coarse sand to pebble component The primary mode of the marine samples is in the range 088 to 125 mm, whereas, the primary mode for beach material is from 175 to 25 mm The range of median diameters of the marine samples is from 07 to 14 mm The median diameters show a trend of decreasing grain size seaward parallel to the depth contours except opposite the entrance to Bolmas Lagoon where a tongue of relatively coarser material cuts across the depth contours The range of other statistical parameters are (1) sorting coefficient 1 10 to 1 41, (2) skewness 0 83 to 1 18, and (3) kurtosis 0 15 to 0 32 Our sediment studies indicate (1) The heavy mineral assemblage is predominantly green hornblende with secondary amounts of hypersthene and augite Glaucophane and jadeite occur in locally high concentrations near shore (2) The pattern of distribution of the heavy minerals shows (a) a tongue of high concentrations of minerals with a granitic source extending northwest from the San Francisco Bar, (b) flanked on the north and northeast by increasing landward concentrations of Franciscan metamorphic minerals (3) The major source of heavy minerals is the San Francisco Bar Secondary contributions come from Bolmas Lagoon and the adjacent cliffs (4) The circulation in the Bay is primarily counterclockwise, produced by a combination of wave refraction around Duxbury Reef and the tidal Coast Eddy Current The tidal influence, however, of Bolmas Lagoon is restricted to about one mile from the lagoon mouth.
PRESSURE OF WAVES AGAINST VERTICAL WALLS
Authors: Plakida M.E.
Published: February 2019

This paper is concerned with the study of the breaking wave pressure exerted upon the breakwater of the vertical type. The method of calculation of the wave pressure, named the quasistatical method, is based with the theory of the impact of the water jet en the vertical plane and some new results of the experimental data. The formulas for the calculation of the pressure distribution of the breaking wave and the surf wave on the vertical wall are given.
EQUILIBRIUM RANGE SPECTRA IN SHOALING WATER
Authors: Ijima Takeshi , Matsuo Takahido , Koga Kazutami
Published: February 2019

In shoaling water on sloping beach, waves break by hydraulic instability due to the finiteness of water depth, so that frequency spectra of waves in surf zone must have any limiting form similar to the equilibrium spectrum given by Phillips(l958) In this paper, authors haze derived an equilibrium form of spectra for surf waves from the limiting wave condition at constant water depth by Miche(l944) and from breaking wave experiments on sloped bottom by Iversen(l952) The results arc compared with surf wave spectra obtained from field observations by means of stereo-type wave meter devised by the authors(1968). By means of this spectrum and by deep water wave spectra for various wind conditions, significant wave heights and optimum periods of limiting waves m surf ^one are calculated.
PLUNGING WAVE PRESSURES ON A SEMI-CYLINDRICAL TUBE
Authors: Jen Yuan , Lin Pang-Mou
Published: February 2019

Laboratory tests were made on a 6-inch diameter semi-cylindrical tube simulating a prototype concrete structure designed to be placed parallel to the coastline in the surf zone to intercept offshore transport of beach materials and thus preserving the beach The model beach was of fixed bed type with a slope of 1 to 15 The crest elevation of the tube was set at the still water level for most of the test runs and the sloping beach intersected a flat channel bottom at a depth of 20 75".
LOADINGS ON LARGE PIERS IN WAVES AND CURRENTS
Authors: Wang Hsiang
Published: February 2019

Through scale-model tests, the forces, moments, and the pressure distributions, including impact pressures, were determined for large diameter piers extending through large-amplitude wave system in which current strengths vary Tests were performed at 1/100 scale, simulating piers of the bridge for the Northumberland Strait Crossing, Canada These piers are partially cylindrical with a base diameter of 100 feet Close to the surface, where the wave action is greatest, they are conical Waves up to 25 feet and current up to 4 knots have been reproduced m the laboratory, according to Froude similitude The tests results fully support the known concept that, when the pier diameter is large in comparison with the wave length, mertial force becomes dominant Generally, the presence of current, either with or against the wave tram, results in a decreasing wave force Semiempirical relations were developed for force predictions that require the experimental determination of a singular coefficient.
SOME EXPERIMENTS WITH SAND-FILLED FLEXIBLE TUBES
Authors: Jakobsen Per Roed , Nielsen Arne Hasle
Published: February 2019

Experiments with the use of long sand-filled flexible plastic tubes ("Sand sausages") have been carried out for coastal protection purposes at several exposed locations along the Danish coasts since 196T In general the results have been encouraging Several methods have been used to fill the tubes with sand A simple inexpensive hydraulic method for easy filling of almost impermeable tubes on site has been developed by model and prototype experiments with promising results As a result of the experiments it seems likely that sand-filled tubes may be used with advantage as temporary structures, 1 e for full-scale pilot investigations and to solve acute problems, or they may be incorporated in more permanent structures.
Complete Proceedings - Single PDF Download
Authors: Johnson J. W.
Published: February 2019

The Twelfth Conference on Coastal Engineering marks the twentieth year since the first conference was held at Long Beach, California, in October 1950 It appears appropriate at this time to present a brief history of the research councils which have sponsored these conferences over the years.
IMPACT OF RANDOM WAVE SPECTRA ON STOKES DRIFT IN COASTAL CURRENT MODELING
Authors: Imai Yuki , Ninomiya Junichi , Mori Nobuhito
Published: February 2019

The wave-induced velocity, known commonly as Stokes drift, plays an important role on upper ocean current system. However, in general, the depth profile tends to be estimated using a regular wave approximation like calculation from significant wave height in order to simplify the modeling. Breivik et al. (2014) proposed an improved Stokes drift profile to considering random waves but discussed limited to deep water. This study proposes a novel treatment of Stokes drift on random waves to consider full directional spectra and the approximated treatment is introduced into coupled ocean-wave model to apply for the depth-limited region. To validate the proposed treatment, Stokes drift velocity derived from the treatment is theoretically and empirically compared with some derived from regular wave approximation. Finally coastal current simulation is performed for Kii channel of Japan focusing on Tanabe bay by the coupled model with two-way-nesting scheme.
COASTAL FLOODING, WAVE OVERTOPPING AND BEACH GROUNDWATER INTERACTIONS
Authors: Gallien Timu , Delisle Marie-Pierre
Published: February 2019

Coastal flooding is a significant humanitarian and socioeconomic hazard (e.g., Nicholls, 2010). Global mean sea levels are expected to rise over the coming century and mean higher high water (MHHW) and mean high water (MHW), peak levels that drive coastal flooding, show upward trends in many locations (Mawdsley et al., 2015). Significant coastal flooding will occur by 2050 (e.g., Tebaldi et al., 2012; Sweet and Park, 2014). Wave overtopping is primary driver of coastal flooding. Low-lying urbanized sand spits, backed by an estuary are particularly vulnerable to sea level rise. Recent field observations suggest distinct feedbacks between wave overtopping, beach groundwater levels and backshore vulnerability.
OBSERVATIONS OF CANOPY FLOW STRUCTURE AND FRICTIONAL VELOCITY OF CORAL COLONIES IN DONGSHA ATOLL
Authors: Huang Zhi-Cheng , Hsu Wen-Yang , Yang Jay
Published: February 2019

Understanding the hydrodynamics is important for biological, ecological, and biogeochemical processes in coral reef systems. The near-bed flow motion affects the benthic organism distributions, morphological evolution, larvae settlement, and nutrient uptake. The near-bed flow structures have been characterized as planar boundary-layer flows when the bottom roughness scale created by benthic organisms is much smaller than the water depth. On the other hand, when the bottom roughness scale becomes much larger, the resistance drag forces caused by these canopy elements should be considered (Rosman and Hench, 2011). The form drag of the multiple coral colonies generates turbulent wakes, enhances turbulent mixing, and changes the flow structure (Huang, 2015). Many laboratory and modeling studies have reported the drag parameterization and the flow structure for unidirectional flows through submerged canopy or vegetation (e.g., Finnigan, 2000; among many others). However, the vertical flow structures of the canopy layer caused by coral colonies (bommies) are rarely reported in fields. Here we present field measurements of flow structure over coral colonies using acoustic Doppler velocimetry (ADV) and pulse-coherent Doppler velocity profiler (PCADP) techniques. The measured current profiles and turbulence are used to study the flow dynamics in the canopy-layer created by coral colonies.
THEORETICAL AND EXPERIMENTAL STUDY OF THE DAM-BREAK WAVE TIP REGION
Authors: Liu Haijiang , Deng Xiaohu
Published: February 2019

Dam-break flow has direct relationship with many coastal engineering problems, such as swash movement and tsunami event. Plenty of studies have been conducted on this topic. In terms of theoretical analysis, initiating from the classic Ritterâ€™s solution, various approaches have been applied, e.g., the method of characteristics, the perturbation method, and the parametric substitution. As for the physical test, significant improvement has been achieved with the development of measuring instruments. Nevertheless, clear understanding on the hydrodynamic features of the wave tip region, where the bottom resistance and flow viscosity play important roles, is still far beyond enough.
EFFECT OF MACRO-ROUGHNESS ELEMENTS ON TSUNAMI INUNDATION: SINK TERM FORMULAE FOR DEPTH-AVERAGED NUMERICAL MODELS
Authors: Leschka Stefan , Krautwald Clemens , Oumeraci Hocine
Published: February 2019

Tsunami propagation and inundation are commonly simulated using large-scale depth-averaged models. In such models, the quadratic friction law with a selected Manningâ€™s coefficient is generally applied to account for the effect of bottom surface roughness in each computational element. Buildings and tree vegetation in coastal areas are usually smaller than the computational element size. Using empirical Manningâ€™s coefficients to account for such large objects is not physically sound and, particularly in tsunami inundation modelling, this may result in large uncertainties. Therefore, an improved understanding of the processes associated with the hydraulic resistance of the so-called macro-roughness elements (MRE) is required. Relevant parameters such as shape, height and arrangement of the MRE should be investigated through laboratory experiments or numerical tests using a well-validated three-dimensional CFD model. Given the correlation of such parameters to the MRE-induced hydraulic resistance, empirical formulae were developed and directly implemented as sink terms in depth-averaged numerical solvers such as non-linear shallow-water (NLSW) models.
NUMERICAL FLOW MODELING AROUND OKINAWA FROM CORAL REEF AREA TO OPEN OCEAN
Authors: Shiraki Yoshiaki , Suzuyama Katsuyuki , Shibaki Hidenori , Kuwae Takashi , Sakieda Masaki
Published: February 2019

Coastal area along the Okinawa sea is formed from coral reefs. In the area, coastal flows are generated by various factors of tide, wave, wind, river discharge and so on. In the offshore areas, oceanic currents including the Kuroshio also influence the coastal flows, because of the openness. Thus, the flow pattern becomes complicated by such external forces. To simulate the flow pattern of the Okinawa sea by numerical flow modeling, the model needs to deal with the various external forces from shallow coral reef area to deep open ocean. Additionally, steep slope exists in the offshore end of coral reef. In such region, we have to be careful because flow simulation is likely unstable. This study intends to develop the numerical flow model which is applicable to the Okinawa sea, and its performance has been tested in the several sea areas. In addition, field observations were carried out to investigate the flow phenomena and to verify the model accuracy. The result of filed observation and its comparing with the simulation is shown.
COASTAL FLOODING-INDUCED DEBRIS MOTION
Authors: Nistor Ioan , Goseberg Nils , Stolle Jacob , Shibayama Tomoya , Mikami Takahito
Published: February 2019

Extreme coastal events such as the 2004 Indian Ocean Tsunami, the 2011 Tohoku Tsunami as well as the 2005 Katrina and 2012 Sandy hurricanes demonstrated that, hydrodynamic loading aside, debris loading represents a major factor in the extreme loading conditions experienced by inland infrastructure. While extreme hydrodynamic loading due to coastal flooding events has been the object of intense research over the past decade, few studies dealing with debris impact due to coastal flooding have been conducted. Post-tsunami forensic engineering field investigations conducted by the authors (Nistor et al. 2005; Shibayama et al., 2006; Nistor et al. 2010) or other researchers (Chock et al. 2012, Sato et al. 2014;) revealed that debris loading and debris damming have a significant effect on the structural integrity of buildings and infrastructure in general, especially in high-density urban areas. Current design guidelines (FEMA P-55, 2011; FEMA P-646, 2012) and the new ASCE-7 Chapter 6 - Tsunami Effects and Loads suggest conservative estimations of the debris spatial spreading based on limited sets of field data to assess debris impact potential (Chock et al., 2012; Naito et al., 2014). The primary objective of this study was to investigate the spatial and temporal displacement of floating debris due to rapid coastal flooding in a built-in port environment using two novel different measuring techniques: (1) high-accuracy video debris detection and tracking system and (2) a real-time locating â€œsmartâ€ sensor-tracking system. Results are compared with prescriptions of the ASCE7 Chapter 6 pertaining to debris motion.
EXPERIMENTAL MODELING OF TSUNAMI BORE IMPINGEMENT ON A SIMPLIFIED COASTAL BUILDING
Authors: Chuang Wei-Liang , Chang Kuang-An , Kaihatu James , Cienfuegos Rodrigo , Mokrani Cyril
Published: February 2019

Numerous laboratory efforts were devoted to improve our understanding to the process of tsunami wave-structure interaction and provide valuable data to validate numerical and analytical models. However, the highly turbulent and multiphase nature of tsunami bores makes the study of their impacts very challenging. Many experimental studies (e.g., Shafiei et al. 2016) employed wave gauges to measure the bore height and estimate the bore front velocity based on shallow water equations. Considering the complexity of the flow and its impact with structures, the conversion between the bore height and the bore velocity is far from straightforward. Therefore, this study attempts to apply the bubble image velocimetry (BIV, Ryu et al. 2005) technique to directly measure the flow velocities during the tsunami bore impact. A tsunami wave, that breaks on a sloping beach, propagates inland as a form of bore, and impinges on a rigid structure, is considered as the scenario of interest. The objective is to perform a comprehensive investigation on the borestructure interaction by examining the fluid velocity, impact pressure, and surge force during the impact event with various structure headings.
FLOW CHARACTERISTICS IN SWASH OF TRANSIENT LONG WAVES
Authors: Pujara Nimish , Liu Philip L.-F.
Published: February 2019

The flow of water on a beach is of fundamental importance in coastal engineering. It controls the sediment transport and hence beach morphology. It also affects coastal structures through forces imparted on them and coastal flooding when beach overtopping occurs. The most common approach to numerically model this flow is to use depth-averaged equations (also known as shallow water equations). However, there is a lack of fundamental understanding of the flow produced by different transient wave forms. A better understanding would lead to better validation of numerical models. It would also allow engineers to more easily evaluate fluid forces on coastal structures and the risks of beach overtopping without the need to carry out expensive numerical simulations.
COMBINED EFFECT OF STORM SURGE AND OVERLAND FLOW ON FLOODING IN A COASTAL URBAN AREA
Authors: Tahvildari Navid , Sahu Akash , Shen Yawen , Morsy Mohamed , Goodall Jonathan
Published: February 2019

The coastal regions in the U.S. East Coast and the Gulf of Mexico are under the risk of storm surge and precipitation-driven flooding. The adverse impacts of climate change including sea level rise (SLR), potential increase in intensity and frequency of extreme storms, and increase in precipitation intensity increases the vulnerability of coastal communities to flooding. The common practice for flood hazard assessment in urban coastal areas can result in some errors as the effect of storm surge and overland flow are not considered simultaneously. In this study, we combine the results of two hydrodynamic models, one for overland flow and the other for storm surge inundation, to develop an improved approach for flood hazard assessment.
LARGE-SCALE EXPERIMENTS ON WAVE-INDUCED SHALLOW TURBULENT COHERENT STRUCTURES
Authors: Kalligeris Nikos , Lynett Patrick J.
Published: February 2019

There are numerous reports of large-scale "whirlpools" being generated in the near-shore during tsunami events (Borrero et al., 2015). These features, termed tsunamiincluded turbulent coherent structures (TCS), form due to flow separation at sharp coastline features. During the 2011 Tohoku tsunami, the generation of a large-scale TCS was captured at port Oarai in a helicopter footage (Lynett et al., 2012). The TCS was spinning for tens of minutes, entraining boats in the high-speed rotational flow, until it was washed away by the next incoming wave. TCS generation can potentially control the hazard for small amplitude tsunami waves in ports and harbors (Borrero et al., 2015; Kalligeris et al., 2016).
CONSIDERATION OF STORM SURGE CAUSED BY HURRICANE IRMA BASED ON STOC-WRF COUPLING MODEL
Authors: Arikawa Taro , Seki Katsumi , Haga Takuto , Fujiwara Kazuhiro
Published: February 2019

Hurricane Irma occurred in the Atlantic Ocean in 2017. It has developed to Category 5, the maximum wind speed is about 82.7 [m/s], minimum central pressure is about 914 [hPa]. Because there is concern that the risk of storm surge due to global warming is increasing, it is important to predict storm surge for prevention of the disasters. For that purpose, it is important to construct a method that can predict local area phenomena. Therefore, in this study, to achieve that purpose, a methodology of downscaling the mesoscale data is developed by using the STOC-ML and WRF, and the applicability is verified to the storm surge due to Irma. In addition, wave set up is also estimated using SWAN and the characteristics of Irma is considered.
TSUNAMI GENERATION BY EARTHQUAKES: SEABED TOPOGRAPHY AND INERTIAL EFFECTS
Authors: Dalrymple Robert A. , Derakhti Morteza
Published: February 2019

In this presentation, we examine the effects of the shape and height of a moving bed on the generated surface gravity waves using the 3-D Smooth Particle Hydrodynamic model, GPUSPH (HÃ©rault et al., 2010). Further, we investigate the relative importance of the inertial effects on the general characteristics of the generated Tsunami in the near- and far-field for various rates of the bed displacement, ranging from creeping to impulsive regimes. The sensitivity of the inertial effects on the shape of the moving bed is also discussed. Finally, the characteristics of the acoustic waves generated during the various bed displacement scenarios are examined.
VORTEX FORCE ANALYSIS OF WAVE-DRIVEN NEARSHORE CIRCULATION
Authors: Derakhti Morteza , Dalrymple Robert A.
Published: February 2019

In this presentation, we examine 3-D structure of nearshore circulation driven by short-crested wave breaking using the 3-D Smooth Particle Hydrodynamic model, GPUSPH (HÃ©rault et al., 2010). The alongshore variation of incident wave field has been imposed by using the method of intersecting wave trains proposed by Dalrymple (1975). We use the 3-D vortex force formalism to analyze the various forcing mechanisms of the observed circulation. Of particular interest is the relative importance of the vortex force compared with the other wave-averaged forces. The accuracy of the depth-averaged vortex force based on the formulation of Smith [2006] is also examined.
GENERATION OF UNUSUALLY LARGE RUNUP EVENTS
Authors: Li Chuan , Ã–zkan-Haller Tuba , GarcÃ­a-Medina Gabriel , Holman Robert A. , Ruggiero Peter , Jensen Treena , Elson David , Schneider William R.
Published: February 2019

We present an examination of unusually large runup events that were observed on January 16, 2016 on the west coast of the United States. Although these events resemble small tsunamis, no earthquake or significant atmospheric disturbances were observed during this time. Coincidental observations of long and rapidly increasing peak wave periods and moderately large wave heights both on- and off-shelf suggest that long and large swells generated by distant storms were possibly the cause of these events.
OPTICAL MEASUREMENTS FOR LABORATORY OBSERVATIONS OF TSUNAMI RUN-UP ON CONICAL ISLANDS
Authors: Rivera Peter , Keen Adam , Lynett Patrick J.
Published: February 2019

Recent studies and observations suggest that small islands near the mainland do not offer protection against tsunamis and may in fact amplify the run-up. The goal of this study was to better understand how the combined effect of small islands and reefs affects tsunamis runup on a planar beach. Optical measurements were carried out to study the run-up characteristics. The study was carried out in the Tsunami Wave Basin at the O.H. Hinsdale Wave Research Laboratory, Oregon State University. Two Panasonic AW-HE60 cameras where used to track run-up on the shore. Through camera calibration we obtain the cameraâ€™s parameters which are used to undistort the image and obtain reliable run-up measurements. Using a total station ground control points where collected to rectify the images and obtain â€˜real world coordinatesâ€™ from the videos. The approach of Rueben et al. (2011) was used to track the wave fronts from the video data.
NUMERICAL STUDY OF NEARSHORE HYDRODYNAMICS UNDER STORM WAVE CONDITIONS IN HUJEONG BEACH, EAST COAST OF KOREA
Authors: Chang Yeon S. , Do Jong Dae , Ahn Kyungmo , Jin Jae-Youll
Published: February 2019

In this study, we present the results of numerical model study to simulate the hydrodynamic conditions observed in Hujeong Beach in the east coast of the Republic of Kore from December, 2016 to January, 2017 during which several extratropical cyclones hit the area causing extreme wave conditions. Three acoustic instrumentation systems were moored from the coast to a location outside the surf zone where the water depth was ~8m to measure waves, currents and suspended sediment concentrations. For the numerical model, we employed the CADMAS-SURF Raynolds-Averaged Navier-Stokes (RANS) model to generate the wave conditions over the region of the field experiment.
DEBRIS AND VESSEL TRANSPORT DUE TO TSUNAMI CURRENTS IN PORTS AND HARBORS
Authors: Ayca Aykut , Lynett Patrick J.
Published: February 2019

The focus of the discussion will be on the debris and vessel transport capacity of the tsunami induced currents in ports and harbors. The tsunami events in the past 15 years proved that understanding these processes within the port/harbor basin has paramount importance in safety, recovery and the long-term resilience planning of the facilities; as all of these depend on the ability of structures or infrastructure to resist damage and the capability of harbors to become functional after the event.

This endeavor requires an accurate representation of the flow field around the floating objects. Particularly, when the size of an average container ship is considered among with itsâ€™ fairly high draft to depth ratio, the interaction between flow and the vessels gets stronger. Therefore, in this study, the developed numerical tool, which is coupled with a 2HD nonlinear shallow water model, takes the interaction between the flow and the objects into account, and provides accurate results in a computationally efficient way.

We will also present example simulation results of a numerical modelling study aimed at providing the quantitative guidance on maritime tsunami hazards in ports and harbors. This information can be used in pre-disaster recovery planning with the identification of the safe mooring spots or where the debris will likely accumulate after future tsunamis. Whilst the harborâ€™s ability to resist damage is a function of reducing the exposure to hazardous conditions as well as the maintaining/upgrading the structures/infrastructure within the harbors.
EXPERIMENTAL STUDY ON TRANSPORT CHARACTERISTICS OF COASTAL BOULDERS BY TSUNAMI AND HIGH WAVES
Authors: Kiso Satoshi , Yasuda Tomohiro , Mori Nobuhito , Kennedy Andrew
Published: February 2019

Boulders made of coral limestone transported shoreward have been observed many times in the tropics and subtropical coastal zones, and are called storm boulders or tsunami boulders. They can become lasting evidence of historical mega-tsunami or super typhoon occurrence during the past hundreds to thousands of years, even if no literature record remains. In recent years, a large number of surveys have been conducted worldwide, and the existence of large boulders has been found in several areas such as the Pacific Ocean, the Caribbean Sea, the Atlantic Ocean, and other regions. Since there is limited observational record of their detailed motion, movement limit, and spatial distribution of transport by gigantic tsunami or storm waves, detailed movement mechanisms are still poorly known. This increases the difficulty of developing a model of boulder transport, and interpreting field observations. These hydrodynamic conditions are also directly related to structural loads of interest to engineers and planners. This study aims to measure transport characteristics of coastal boulders through a series of experiments in a tsunami-wave laboratory flume.
EFFECTS OF HYPERCONCENTRATION-RELATED DRAG REDUCTION ON TIDAL PROPAGATION IN THE QIANTANG ESTUARY
Authors: Li Wei , Su Zhenghua
Published: February 2019

The Qiantang Estuary (QE) in the east coast of China is famous for its hyperconcentrated tidal bore with the highest sediment concentration up to about 80 kg/m3 (Pan et al., 2013). Recent research for some European estuaries has indicated that hyperconcentrated environment may affect tidal propagation through hydraulic drag reduction, resulting in an enlarged tidal range and even a regime shift in the estuary (Winterwerp and Wang, 2013). However, this water-sediment interactions have not been considered in the tidal prediction of the Qiantang Estuary in the past. Instead, a bed roughness even smaller than that of glossy glass has often been used to fit the observed tidal data in the mathematical modelling.

Therefore, the present study aims to reveal whether the hyperconcentration-related drag reduction can explain the mechanism of very small bed roughness in the Qiantang Estuary and to what extent it can affect the tidal propagation especially for the tidal range. First, an analytical model is used to predict the tidal range along the QE (from Wenyan to Ganpu stations) for different methods of bed friction. Then, mathematical modelling is conducted to shed light on the processes of tidal wave propagation for the corresponding approaches. The results of the two models are compared together with the field observations to further verify the ability of the analytical model and the significance of the effects of hyperconcentration-related drag reduction.
EFFECT OF FRICTION IN TSUNAMI INUNDATION MODELING
Authors: Sogut Deniz Velioglu , Yalciner Ahmet Cevdet
Published: February 2019

Bottom friction is an important parameter in tsunami inundation and should be included in the numerical simulations in order to reach reliable results. This study shows that smaller friction leads to larger runup values in the simulations and the runup distance of large amplitude waves is more friction sensitive. The analyses are conducted using FLOW 3D, a three-dimensional numerical model efficient in solving free surface flows, and using three experimental benchmark problems, which are commonly used to validate numerical models in coastal engineering.
NUMERICAL WAVE DISSIPATION OVER IDEALIZED MARSH PLATFORM
Authors: Holzenthal Elizabeth , Hill David F.
Published: February 2019

Combined tidal and wave events are simulated over an idealized marsh environment to quantifiably characterize the cross-shore attenuation of wave height as a function of bottom roughness and submergence depth. Dissipation calculated by the numerical model is compared with existing analytically derived parametric wave height decay models. We propose an alternative two-parameter dissipation model that better captures the limited decay of wave attenuation over a kilometer of propagation. The results suggest that cross-shore decay rates are sensitive to incident wave conditions as well as bottom roughness.
BATTLING THE BERING SEA: ST GEORGE ISLANDâ€™S BERM BREAKWATER
Authors: Blackmar Philip , McPherson Ronald
Published: February 2019

St. George Island, Alaska is located in the Bering Sea more than 320 kilometers (200 miles) north of the nearest Aleutian Island. During original design and construction of the fishing harbor at St. George Island in the early 1980â€™s, stone large enough for a conventional breakwater was not available to quarry on the island, so the project utilized a berm breakwater approach with the available local stone. The long-term performance and service life of the berm breakwaters is reviewed in this paper. Construction of the berm breakwater was completed in 1987 and the breakwaters remained functional for nearly 20 years with little maintenance. In the winter of 2015/2016, approaching 30 years since initial construction, significant damage occurred during a winter storm. Repairs utilized a berm breakwater approach similar to the original design. Repairs were completed in 2 phases due to the short construction seasons at the project site.
PREDICTION OF FORMATION OF RECURVED SAND SPIT USING BG MODEL
Authors: Serizawa Masumi , Uda Takaaki , Miyahara Shiho
Published: February 2019

The morphological features of recurved sand spits were studied by selecting recurved sand spits in Namibia, Sandy Hook on the US east coast, and Graswarder spit in Germany. The elongation of a recurved spit was predicted using the BG model (a model for predicting three-dimensional beach changes based on Bagnoldâ€™s concept). A recurved spit was formed in Case 1 when waves were incident at angles of 45Â° and -30Â° with a duration ratio of 0.85:0.15. The width of the recurved sand spit in Case 1 increased with the elongation of sand spit, and the overall shape became similar to the expanded bird wing, which well explains the configuration of a recuved sand spit formed in Namibia. In Case 2 when waves were obliquely incident at angles of 45Â° and -45Â° with the same duration ratio as in Case 1, a sand spit extended straight, which well resembles Graswarder spit in Germany.
EFFECTS OF DESALINATION ON HYDRODYNAMIC PROCESS IN PERSIAN GULF
Authors: Lee Wonhyun , Kaihatu James M.
Published: February 2019

Desalination is a significant source of potable water to the Persian Gulf (simply, the Gulf) region. At present, the Gulf countries are the biggest users of seawater desalination with over 50% of the worldâ€™s installed capacity. While, as ground- and surface water sources may become scarce or endangered in the Middle East and North Africa (MENA) region, water desalination activities are expected to continue growing in quantity and capacity, particularly in the Gulf region. However, it is not yet clear what the environmental effects are of increased brine discharge to the nearshore and offshore environments, as reliance on mass exchange through the Strait of Hormuz may be insufficient for necessary levels of flushing. To study this, a three-dimensional characterization of the Gulf has been developed using the Delft3D-FLOW hydrodynamic model. This model was used to obtain the hydrodynamics and flow transporting characteristics in the Gulf. In addition to meteorological and oceanographic forcing, the seasonal discharges of four major rivers and numerous desalination plants in the Gulf region were considered to the modeling system. Field measurements from Texas A&M University at Galveston (TAMUG) Microstructure Group in 2013 provided the validation for the model. The maximum 4.21 ppt and 4.32â„ƒ increases in salinity and temperature, respectively, due to the brine discharge of desalination were obtained at the adjacent area to six desalination plants in the Gulf.
A NEW FULLY-AUTOMATIC PROCEDURE FOR THE IDENTIFICATION AND THE COUPLING OF THE OVERTOPPING WAVES
Authors: Formentin Sara Mizar , Zanuttigh Barbara
Published: February 2019

This contribution presents a new procedure for the automatic identification of the individual overtopping events. The procedure is based on a zero-down-crossing analysis of the water-surface-elevation signals and, based on two threshold values, can be applied to any structure crest level, i.e. to emerged, zero-freeboard, over-washed and submerged conditions. The results of the procedure are characterized by a level of accuracy comparable to the human-supervised analysis of the wave signals. The procedure includes a second algorithm for the coupling of the overtopping events registered at two consecutive gauges. This coupling algorithm offers a series of original applications of practical relevance, a.o. the possibility to estimate the wave celerities, i.e. the velocities of propagation of the single waves, which could be used as an approximation of the flow velocity in shallow water and broken flow conditions.
EFFECTS OF WATER LEVEL VARIATIONS ON THE STABILITY OF ROCK ARMOURED SLOPES
Authors: Van Gent Marcel R.A. , Zwanenburg Suzanna A.A. , Kramer Jan
Published: February 2019

Physical model tests on the stability of rock armoured slopes have been performed to demonstrate the importance of water level variations during a storm, due to a tide or a storm surge. For the stability of rock armoured slopes also the importance of the sequence of storms at various water levels has been studied. The test results indicate that a smooth sinusoidal water level variation leads to an increase in damage compared to the same wave conditions at a constant water level. Furthermore, a stepwise approach of the sinusoidal water level elevation leads to other results than the approach with a continuous water level variation, whereas the continuous water level variation resembles the peak of a storm or the tidal water level variation better than a stepwise approach. If storms with different water levels attack the armour layer, the damage is generally smaller than if all storms attack the armour layer at the same water level. Furthermore, the results have been discussed based on earlier analyses where the statistics of rock armoured slopes have been addressed and the importance of the length effect has been illustrated using a method to apply results from physical model tests to real structures.
EMPIRICAL AND NUMERICAL MODAL ANALYSIS OF COASTAL AREAS PRONE TO TSUNAMI RISK
Authors: Bellotti Giorgio M. , Romano Alessandro
Published: February 2019

In this paper the Empirical Orthogonal Function (EOF) method and the k-f spectral technique are applied to extract from experimental data related to landslide-tsunamis propagating around the coast of a conical island, the wave modes that contribute to the wave field. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It is shown that it is possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important.
A HYBRID METHOD TO COMBINE WAVE PENETRATION AND LOCAL WAVE GROWTH IN LARGE HARBOR BASINS
Authors: Van Vledder Gerbrant
Published: February 2019

This paper describes a hybrid method to determine the wave conditions in large harbor basins were wave propagation and local wave growth by wind are both of relevance. The method was developed to include the effects of diffraction and wind wave growth in the assessment of design wave conditions that so far cannot be computed within one wave model. The diffraction effects are computed with a phase-resolving wave penetration model, and the wind effect is computed with a phase averaged spectral wave model. The method accounts for the effect the local wind wave growth occurs on top of the penetrating wave field. To isolate the wind wave growth, two model runs are performed with the phase-average model. One run includes wind forcing, whereas in the other run wind forcing is switched off. Subtracting the results of both methods isolates the local wave growth. The method is illustrated with a hypothetical example for the Port of IJmuiden, located along the North Sea coast of the Netherlands. In addition, an overview is given of the physical processes relevant for the determination of design wave conditions in large harbor basins. The assumptions of the hybrid method are discussed and recommendations are given for further improvements.
POSSIBILITY OF OFFSHORE DISCHARGE OF NOURISHMENT SAND IN TERMS OF SAND VOLUME AND GRAIN SIZE COMPOSITION
Authors: Ishikawa Toshinori , Uda Takaaki , San-nami Toshiro , Hosokawa Jun-ichi , Tako Tetsuyuki
Published: February 2019

On the Shonan coast facing Sagami Bay, part of the nourishment sand was considered to be transported offshore, devaluing the effect of beach nourishment. Beach changes after the beach nourishment were investigated using the Narrow Multi-Beam survey data, which have been collected since 2002. Analysis of the sand volume and grain size composition in the subareas showed that the effect of the beach nourishment on the deposition of fine sediment in the offshore zone was negligible, and that the fine material in the offshore zone was mainly brought from the erosion of the river mouth terrace.
WAVE MODELLING IN A COMPLEX ESTUARY: STUDY IN PREPARATION OF FIELD MEASUREMENT CAMPAIGN EEMS-DOLLARD ESTUARY
Authors: Oosterlo Patrick , Van der Meer Jentsje W. , Hofland Bas , Van Vledder Gerbrant
Published: February 2019

This paper considers the Eems-Dollard estuary in the north of the Netherlands, which is part of the shallow shelf sea the Wadden Sea. This estuary is a highly complex area with tidal flats and deep channels and is characterised by an offshore directed wind, posing a challenge to wave prediction models. As little measurements are available, a measurement campaign is set up to provide field data for verifying and improving these wave models. The paper presents the locations that are most suited for wave measurements in the estuary, insight in the performance of the phase-averaged numerical wave model SWAN, and insight in the processes that play a role in the area around the corner of the Eemshaven. Furthermore, it presents insight into the reliability and applicability of SWAN in this highly complex area. An analysis of propagation effects is performed, as well as a comparison between the SWAN version as used for the Dutch dike safety assessment and the newest version, used for development, which includes the state of the art parameterisations of the physics. Furthermore, modelling is done for a schematised version of the area around the corner of the Eemshaven, considering several different model settings. Large differences occur in the results between the two SWAN versions. These differences are studied in more detail, and the causes of these differences are identified.
A NUMERICAL MODEL OF CROSS-SHORE BEACH PROFILE EVOLUTION: THEORY, MODEL DEVELOPMENT AND APPLICABILITY
Authors: Tabasi Mohammad , Soltanpour Mohsen , Jayaratne Ravindra , Shibayama Tomoya , Okayasu Akio
Published: February 2019

A practical numerical model was developed to simulate cross-shore profile evolution at two coastal sites in Iran. The model consists of three sub-models for calculating wave and current, sediment transport, and bed level changes. Validation and calibration of the model was carried out using the measured field data on the north and south coasts of Iran, where historic measurements of cross-shore beach profiles and wave conditions have been recorded. The model is formulated for calculating cross-shore sediment transports in and outside the surf zone by the product of time-averaged suspended sediment concentration under three different mechanisms and undertow velocity. The comparisons between the model results and field data show reasonable agreement for both coastal sites and will be capable of applying it to other coastal sites with modifications to the free parameters.
NUMERICAL SIMULATION OF THREE-DIMENSIONAL FLOW AROUND HARBOR DUE TO TSUNAMI USING FAVOR METHOD AND WENO SCHEME
Authors: Kajikawa Yuki , Kuroiwa Masamitsu , Otani Naohiro
Published: February 2019

In this paper, a three-dimensional (3D) tsunami flow model was proposed in order to predict a 3D flow field around a harbor accurately when tsunami strikes. In the proposed numerical model, the Cartesian coordinate system was adopted, and the Fractional Area/Volume Obstacle Representation (FAVOR) method, which has the ability to impose boundary conditions smoothly at complex boundaries, was introduced into the governing equations in consideration of applying the estimation to actual harbors with complex shape in the future. Moreover, the fifth-order Weighted Essentially Non- Oscillatory (WENO) scheme, which is a technique for achieving high accuracy even if the calculation mesh is coarse, was applied to discretization of the convection terms of the governing equations. In order to verify the validity of the model, it was applied to a large-scale laboratory experiment with a scale model of harbor. Comparisons between the simulated and experimental results showed that the model was able to reproduce the time variation of the flow field with sufficient accuracy. Moreover, the simulated results showed that a complex 3D flow field with some vertical vortex flows was generated around a harbor when tsunami struck.
SCOUR AT THE TOE OF ROCK ARMOURED STRUCTURES
Authors: Den Bieman Joost P. , Jacobsen Niels G. , Van Gent Marcel R. A.
Published: February 2019

In this work, a CFD model (OpenFOAM) is extended to allow for the exchange of sediment between the inside of porous structures and the outside. This exploratory extended model is applied to simulate the morphological change around and under toe structures, as are often used in rock armoured coastal structures. Both the dimensions of the toe structure and the hydraulic loading are varied to investigate their effect on the simulated scour.
STABILITY COMPARISON OF 9 MODERN PLACED BLOCK REVETMENT TYPES FOR SLOPE PROTECTIONS
Authors: Breteler Mark Klein , Provoost Yvo , Van Steeg Paul , Wolters Guido , Kaste Dorothea , Mourik Gijsbert
Published: February 2019

Placed block revetments are constructed to withstand the wave forces on dikes, especially in regions where rip rap is not locally available, such as the Netherlands. The blocks are placed adjacent to each other on a filter layer to form a relatively closed and smooth surface, which is easy to walk on. Large-scale test in the Delta Flume of Deltares have been carried out to compare the stability of nine types of block revetments, presently on the market in the Netherlands (Klein Breteler, 2016). All tests have been performed with a comparable test setup and test program. The test program consisted of three series of tests. The first two series were short duration tests of 1000 waves with two different wave steepnesses, in which the wave height was increased step-by-step until damage occurred. The third test series was a long duration test lasting for 26 hours, or until damage occurred. The results of the tests have been used to quantify a correction factor in the calculation method. This correction factor, or stability factor, makes that the calculation method gives the same results as the Delta Flume tests, taking a safety margin into account. In this way the type-specific stability of each type of block revetment was better included in the calculation method.
AVERAGE AND WAVE-BY-WAVE OVERTOPPING PERFORMANCE OF STEEP LOW-CRESTED STRUCTURES
Authors: Gallach-SÃ¡nchez David , Troch Peter , Kortenhaus Andreas
Published: February 2019

Wave overtopping is a key process in coastal protection. The assessment of the wave overtopping rates is an important aspect in the design of coastal structures. In this paper, the focus is on steep low-crested structures, which include structures with steep slopes up to the limit case with vertical structures, with small relative freeboards up to the case with zero freeboards. This type of structures is of use for coastal protection in the case of sea level rise within climate change process and for overtopping wave energy converters. A literature review of the overtopping knowledge available for steep low-crested structures is carried out, identifying a knowledge gap. To fill this knowledge gap, 2D hydraulic model tests were performed at the wave flume of the Department of Civil Engineering at Ghent University, measuring wave conditions and the overtopping performance. Average and individual wave overtopping were analysed and compared to existing prediction formulae. Inaccuracies in the existing prediction formulae are detected and studied, and enhanced prediction formulae are presented for the average overtopping and the probability distribution of the individual overtopping volumes. The new prediction formulae improve the accuracy of wave overtopping volumes for steep low-crested structures range while maintaining the accuracy for other types of structures. The improved understanding of the overtopping behaviour allows a safer design of coastal structures.