Asian and Pacific Coasts 2009

The following sections are included:

• PREFACE

• Committee

• CONTENTS

We describe the theories for two types of wave-power absorbers that can have a wide bandwidth of high efficiency. One is a compact array of small buoys supported by a large platform. Because each buoy is much smaller than the wavelength, inertia is negligible hence the buoys are not resonated. However the efficiency of the array has a relatively broad frequency band. We shall show that such an array can be more advantageous than a single large buoy of the same total volume. The second devise is an oscillating water column attached either to a, thin breakwater or to a cliff-like coast. We show that the system has an added inertia that varies with the wavenumber as a N-shaped curve. If the volume of chamber above the interior water surface is suitably chosen, the compressible air serves as a negative spring that broadens the efficiency bandwidth.

Harmful algal blooms and red tides can lead to beach closures, dissolved oxygen depletion and fish kills, and shellfish contamination. Coastal algal blooms are complex hydro-biological phenomena that are notoriously difficult to predict. We present herein a simple algal bloom forecast model that is derived from deterministic water quality modeling and field observational experience. Algal bloom occurrence is predicted as a function of vertical hydrodynamic stability and nutrient availability. The model requires minimal field measurements as input and is highly suited for operational forecasts. Predictions of the model are compared with field observations. The development of a near real time early warning system for forecasting the likelihood of algal blooms and red tides for fisheries management is presented.

Reef connectivity based on source-sink relationship between distant coastal ecosystems is a key for enhancing resilience of coastal ecosystems by, e. g., properly setting and managing marine protected areas (MPAs). This paper introduces recent example of the studies by the author's group for clarifying larval dispersal processes as the key to understand reef connectivity and their relationship with characteristics of currents like eddy development.

A Tidal Power Plant (TPP) is being constructed at the middle part of the existing Sihwa Lake dike located near the southern Incheon Port in Korea. The project, which will continue until 2010, is to harness the largest tidal energy in the Kyeonggi Bay, the eastern Yellow Sea. The present paper outlines the overall project with current progress of construction. The Sihwa TPP when it is completed will have the largest installed capacity so far.

Due to the rapid economic development along the coastal area of Bohai Bay, serious contamination and deterioration of the eco-environment has been manifested as a result of intensified exploitation activities. In this paper, the hydrodynamic characteristics of water exchange and wave-induced alongshore current of Bohai Bay have been analyzed by numerical simulation. The distributions of major pollutants and plankton in space and time series were investigated. An eco-hydrodynamic model was set up to simulate the N, P nutrients and plankton ecosystem in the coastal waters of Bohai Bay, consisting of a hydrodynamic sub-model and an eco-system sub-model. The results agreed with the measured data. By using numerical simulation, the impacts of coastal exploitation on eco-environment of Bohai bay coastal water have been analyzed, including sea-reclamation, sluice build, and seawater desalination. In the end, the further development of numerical simulation of aquatic eco-environment for coastal water has been introduced.

Traditional methods for environmental management of marine reclamation works close to sensitive habitats have generally not provided the level of control necessary to ensure preservation of these habitats. Obtaining the level of control necessary to assure authorities and NGOs of compliance with environmental quality objectives requires quantifiable compliance targets covering multiple temporal and spatial scales. Of equal importance are effective and rapid response mechanisms, to allow feedback of monitoring results into compliance targets and work methods. This paper describes the successful implementation of comprehensive Environmental Monitoring and Management Plans (EMMP), based upon such feedback principles, which allow reclamation activities to proceed in close proximity to Singapore's most important marine habitats under third party scrutiny. Specific focus is placed on describing the methods utilized to quantify compliance with daily spill budget targets and how such targets and compliances are assessed. To improve reliability, the spill budgets take into account specific habitat tolerance limits for varying magnitudes and durations of sediment loading. Refinements to sediment plume models were undertaken to enhance their ability to hindcast impacts from the contractors' complex reclamation schedules. Methods for segregation of impacts and assessment of cumulative impacts were also integrated into the hindcast procedures. Finally, the paper describes the updating of tolerance limits and confirmation of spill budgets via targeted habitat monitoring. To date, the EMMPs have been able to document compliance of the works to all pre-project environmental quality objectives at a level of reliability that cannot be refuted by third parties. This has minimized the developers' and contractors' exposure to public complaints and liabilities associated with environmental impacts. The EMMPs have thus allowed the reclamation activities to proceed in an efficient manner, whilst ensuring protection of the environment.

Investigation of the evacuation process from tsunami attack is quite important for coastal town planning against tsunami disaster. Reproduction of imminent situation in a real disaster is impossible in ordinary evacuation training. For this reason, a numerical simulation is an effective tool to investigate the evacuation process in tsunami attack. We have been developed the DEM-base human behavior model to simulate an evacuation behavior. In the present study, a disaster prevention planning against tsunami in a small model town is conducted from the viewpoint of appropriate setting of evacuation places.

It is known that the electromagnetic waves occur when fault layers pressed strongly before earthquakes start. Five electric terminals are buried in lengths 20m and 40m from North to South and East to West in Tagajo campus of Tohoku-Gakuin University. The underground electromagnetic direct current waves, Ultra Low Frequency ULF are measured in this equipment. It is found that the electromagnetic waves move on a large scale before earthquakes occur and two kinds of characteristic waves are observed from two different earthquakes.

The survey result reported that Kr. Ritting Bridge suffered no damages although the tsunami was very high, while Lueng Ie Bridge slid approximately 3m although the tsunami was small. We conducted several field investigations around Northwest coast of Sumatra, and the surveys made the detailed numerical simulation around a structure possible. Our numerical simulation showed that the flow velocity at Lueng Ie Bridge was larger than that of Kr. Ritting Bridge. In order to understand whether the girder slide occurred or not, we defined a Safety Factor (S.F.). S.F. of Kr. Ritting Bridge was big enough, and that of Lueng Ie Bridge was small. Hence there was possibility that Lueng Ie Bridge was slide because the horizontal wave force exceeded the resistant force.

Because a container on apron can drift and collide with coastal structure when a tsunami or a storm surge comes to a harbor, it is important to predict the behavior of container to reduce damages, however, tracking of the motion of container is difficult in a numerical model using a computational grid. Therefore, in this study, the behavior of drifting container due to tsunami is simulated by using the particle method, in which a moving object is easily treated, and the applicability of this model is examined.

The hydraulic experiments have been carried out for estimating tsunami wave force through water level, velocity, force and pressure measurements. Model of building was placed at several points with certain distance from shoreline. Wave force had been estimated by assuming as hydrostatic forces which only consider inundation depth while wave velocity data used as hydrodynamic forces assumption. Force estimation through integrating wave pressure had been conducted at almost all element on exposed area to ensure the effect of model's breadth on magnitude of wave force (not only on the middle). However gap of time lag occurred certainly on each line of measurement points have been found. Therefore, precise estimation of wave force through wave pressure measurement seems very difficult. Present study data were compared to the past of available design guidelines for tsunami forces (Asakura et.al.2000) and some available data from past experiments (Yeom et.al.2007-2008) which had analyzed in order to check the validity of some tsunami wave force estimation methods. Some modification equations that refer to function of maximum inundation depth, maximum velocity and run up distance from shoreline are proposed for more considerable agreement of tsunami wave forces estimation.

In this paper we describe the basic ideas of a so-called Variational Boussinesq Model which is based on the Hamiltonian structure of gravity surface waves. By using a rather simple approach to prescribe the profile of vertical fluid potential in the expression for the kinetic energy, we obtain a set of dynamic equations extended with one additional elliptic equation for the amplitude of the vertical profile. All expressions in the energy contain at most first order derivatives, which makes a numerical implementation with finite elements relatively easy. The applicability of the code is illustrated for two different applications in this paper. One application deals with tsunami simulations, for which we show the phenomenon of tsunami waveguiding before the coast of Lampung in Indonesia. Another application deals with simulations of coastal waves entering the small harbour of Cilacap on the south-coast of Java, Indonesia; we will show that the simulations indicate a resonance phenomenon in the small inner harbour.

Coastal areas in Sri Lanka were devastated by the December 2004 Indian Ocean tsunami. The authors conducted a site survey of the disaster in the southern city of Matara from October to December, 2005. The survey included interviews and questionnaires, investigation of the geometry and damages to buildings, and the topography of the study area, with the aim of obtaining data for the establishment of a tsunami disaster prevention system, through the use of numerical simulation. Based on the site surveys and simulation, a vulnerability function was formulated for building damages caused the by the tsunami in Sri Lanka.

A series of hydrodynamic experiments were conducted to investigate the solitary wave interaction with a slotted barrier model and a single cylinder in a wave flume. Water particle velocities under solitary wave were measured and compared with theoretical values. Wave forces were measured and hydrodynamic coefficients were investigated and compared; Results showed that, for multiple cylinders, drag coefficients decreased as incident wave height increased; inertia coefficients were much scattered and not given in this report. The drag coefficient values for a single cylinder showed different tendency with those of the slotted barrier model (multiple cylinders). These two situations were not comparable because of the blockage effect.

The horizontal and vertical components of tsunami fluid force acting on a bridge beam are measured through hydraulic experiments. The wave pressure on the bridge beam is also measured. The authors show that the vertical component of the tsunami fluid force is as large as the horizontal component of the tsunami fluid force in several cases and that the wave pressure on a bridge beam is larger in the cases where the crest of larger incident waves hits the bridge.

Hazard and risk mapping plays an increasing role to prepare population and local authorities for tsunami events. They base on inundation modeling results. Recently, non-linear shallow water type models are the preferred choice to predict runup and inundation of tsunamis on real bathymetries. A validation of model results is very difficult due to complex phenomena occurring during the tsunamigenic earthquake and wave propagation nearshore and onshore, which are not taken into account completely by the models. Apart from consideration of such phenomena, the quality of bathymetrical data influences model results also (Kongko et al., 2008). In this paper, consisting of two parts, the influence of deviations from exact nearshore data has been investigated. Part I is related to the discussion on the data sets. Multi-beam, single-beam with and without tidal correction and C-Map data has been used. In part II the bathymetries will be applied to model runup of the 2006 Java Earthquake tsunami in the region of Cilacap (Indonesia). The study shows that even big local differences between the data do not have noteworthy effects on runup. In recent model applications using a mesh resolution of 20 to 30 m nearshore and onshore to capture local current fields, however, bathymetry variation at this scale show little influence on the results.

Hazard and risk mapping plays an increasing role to prepare population and local authorities for tsunami events. They base on inundation modeling results. Recently, non-linear shallow water type models are the preferred choice to predict runup and inundation of tsunamis on real bathymetries. A validation of model results is very difficult due to complex phenomena occurring during the tsunamigenic earthquake and wave propagation nearshore and onshore, which are not taken into account completely by the models. Apart from consideration of such phenomena, the quality of bathymetrical data influences model results also (Kongko et al., 2008). In this paper, consisting of two parts, the influence of deviations from exact nearshore data has been investigated. Part I has been related to the discussion on different data sets. In part II the model setup and results are presented and discussed. The non-linear shallow water model MIKE 21 FM has been used to calculate runup and inundation of the 2006 Java Earthquake tsunami in the region of Cilacap (Indonesia). The source has been modeled using a time variable bathymetry from Okada's (1985) model. An inverse solution of the fault parameters from tide gauge records lead to the possibility to validate the results using post tsunami field survey data. Bathymetries have been interpolated on a mesh of 20 to 30 m resolution nearshore and onshore from multi-beam measurements, tide corrected single-beam data, single beam data without tidal correction, C-Map data and from multi-beam data, where an artificial reef has been added. Finally, a bathymetry of much finer resolution has been compared with field survey data. The study shows that even big local differences between the data do not have noteworthy effects on runup. In recent model applications using a mesh resolution of 20 to 30 m nearshore and onshore to capture local current fields, however, bathymetry variation at this scale show little influence on the results.

This paper explores physical mechanisms of locally concentrated damages observed on Seisho coast due to typhoon T0709. Field survey was first conducted to capture alongshore distributions of hydrodynamic forces during the storm. The measured water mark elevations showed certain periodic undulation along the coast and their peak corresponded to the most severely damaged area. Time-series of surface water levels and velocities recorded at Hiratsuka Experiment Station, located around 7km east from the most damaged area , were then analyzed and it was found that both free and bounded long waves grew as T0709 approached to the damaged site and short wave heights increased. Numerical analysis was finally carried out to investigate physical mechanisms of local concentration of hydrodynamic forces and it was found that near-shore current and long wave fluctuations appeared to have significant influence on this phenomenon.

Real time forecasts of wind and waves are useful in taking many operation oriented decisions in the ocean. When site specific forecasts are required time series modeling can be viewed as advantageous over elaborate numerical methods. This paper discusses time series models based on the soft computing approaches of genetic programming (GP) artificial neural network (ANN) to obtain real time forecasts of wind speed, its direction as well as the significant wave height at different locations along the Indian coastline where continuous wave buoy observations get collected. All the developed models over various locations have been integrated into a graphical user interface (GUI) to facilitate web based real time implementation of these models. The GUI starts with a figure showing locations of buoys. The user has to click on the concerned location where it is desired to have the forecasts for next 24 hours. The appropriate and calibrated ANN and GP models will then come into background, linking them with the most recently observed data and will accordingly yield the forecasts immediately.

Every year the long-period high waves occur in the East Sea in winter with high amplitude during the atmospheric depression located near Hokkaido, Japan. These waves attack the coast of both Korea and Japan and cause coastal damages. Especially the waves, named Yorimawari in Japanese, caused huge damages especially in Toyama and Niigata area in Japan on 24, Feb. 2008, and the long-term high waves due to the same meteorological condition also were propagated to east coast of Korea and coastal damages was reported in Anmok, Korea.

It is a problem to construct ports in multi-island offshore area with high suspended sediment concentration and high speed flow, especially sediment problems. Numerical simulation of tidal currents has become important technique to port engineering. Yangshan islands of China are representative of the offshore multi-island with high suspended sediment concentration and high speed flow. Based on the characteristic of the currents and sediments in the Yangshan sea area, a 2D numerical model for the currents induced by waves has been established. According to characteristic of the research area, unstructured grids are applied to fit the boundaries of the sea-area. Verifications with the measured data indicate that the present model simulates the current fields in the research region well. Finally, two layouts were simulated to study the changes of the current field. Computational results show that the Branch Channel Layout is advantageous to the present situation.

Wave characteristics including the wave height distribution, the period distribution and their joint distribution of measured data under complicate underwater topography condition in China Yellow Sea were studied and compared with theoretical results in this paper. The wind-wave relationship was established in this area with the regression analysis method. The results indicates the complexity of wave features in the interest area and this may offers some references in studying wave characteristics of similar problems.

Disastrous coastal floods due to typhoons frequently occur along the coast of Guangdong Province of China in summer. A numerical storm water level forecasting model is set up to make the early warning for such kind of coastal floods. The model consists of two parts: one is the high accurate tide prediction model by applying the constituents series automatic optimization technique and the multi-year mean tidal constituents; the other is the multi-domain storm surge model. The conflict between the high resolution grid expected for the complicated topography in the coastal region and the coarse grid to cover the typhoon system with the large spatial magnitude is solved by the on-line nesting technique with four different grid sizes and three-stage nesting. The finer grid is nested to the coarser one with 3 times finer both in spatial and temporal spaces. The calibration of the proposed model against an extensive set of storm water level data along the Guangdong coast in the last two decades shows a good representation of the measured water levels. The model forecasts the storm water levels due to typhoons well and gives the early warning of coastal floods in time in recent years.

The wind-wave-current interface model that consists of an atmosphere model, wave boundary layer model and ocean hydrodynamics model is applied to the hindcast simulation of cyclone Nargis that made a catastrophic landfall in the low-lying areas of the Irrawaddy River delta in Myanmar in May 2008. Wave computations showed that the WW3 model performed inaccurately in the conditions of extreme shallow water depths under extreme meteorological conditions. In contrast to WW3, SWAN model performed reasonably in simulating the cyclone wave fields. The results emphasized that during severe storm events the additional wave breaking shear stress is significant and can't be neglected. The combined effect of both waves and storm surge resulted in the reported severe inundation that was the main killer of the 138,000 people in the Irrawaddy River delta of Myanmar in 2 May 2008.

The instantaneous and complex characters of an estuarine system are primarily subjected to the physical forces which are the driving power in an estuary. Based on the long-term field data in the Schelde estuary (Belgium, the Netherlands), this study is the first attempt of its kind to quantify estuarine energy derived from key physical forces, i.e., river flow, tidal activity and wave action, in an estuarine system. Tidal discharge, river discharge, flow velocity, tidal range and characteristics of geomorphology are the main variables considered in estuarine hydrodynamics analysis and energy calculation. The results show that the Schelde estuary is characterized by a specific total energy pattern dominated by tidal energy. The energy pattern determines the sediment transport and distribution especially the formation and locations of estuarine turbidity maxima (ETM) in the Schelde estuary.

The strategic position of Indonesia gives its waters as International sea cross line. It means users need to understand Indonesian waters characteristic for supporting ship safety. One piece of information needed is sea weather information including wind and wave. The analyzed data is between 2005-2008 from re-analysis windwaves 5.0 model. Research domain includes whole part of Indonesian waters divided by two parts namely outside waters and inside waters. The outside waters defined as waters border on ocean and other countries (18 lines as gateway), whereas inside waters are not adjacent on other countries (13 lines). The used method is manual interpretation of wind wave contour to get information which areas that have potentially high wave, frequency and month of high wave event. The result showed that almost outside waters and inside waters are frequently potentially high wave except Malaka Strait, central and northern Makassar Strait. The high wave event depends on prevailing weather in that area and probably different for each area.

The barotropic tidal characteristics of Han-river estuary (west coast of Korea) were studied with using observed tidal elevation data and numerical model. The estuary consists of 3 main tidal channels and fresh water discharges by three rivers through which major tidal flow and river discharge meet each other. It was found that the type of this estuary can be characterized by different tidal propagation pattern along those three main channels. Although three major channels show a hyper-synchronous type in general, the maximum tidal amplitude were observed at different channel. Numerical model study was performed to find out major physical factors that influence channel-dependent tidal propagation. Model results showed that the important factor for the change of tidal amplitude and phase along each channel were bottom friction, river discharge and tidal flat existences. On the other hand the river discharge modifies phase lag at high and low tide. Model experiment showed that the topographical characteristic was the most important factor for the generation of hyper-synchronous pattern in Gyeonggi Bay Estuary.

By using field data from southwestern Bohai sea, the wave characteristics, the wave seasonal variation, the empirical relationship between wind and waves and the wave breaking range are analyzed and calculated in the paper. The results are useful for the construction of harbor engineering and studies of marine environmental investigation.

This paper presents a two dimensional coastal circulation model, which is implemented on unstructured triangular meshes, and the solution methodology is based upon semi-implicit method to remove stability limitations associated with surface gravity wave. Advection terms in momentum equations are evaluated by Eulerian-Lagrangian approach to avoid the constraint of Courant number, while other terms are computed with a second order finite volume formulation by multiple least square method. Two numerical test cases are employed to demonstrate the ability of the model to simulate flow field, and the model is finally applied to the reclamation project of Caofeidian in the Bohai Bay, China.

Dynamics of Prochlorococcus (Pro), Synechococcus (Syn) and picoeukaryotes (Euk) was studied in the Pearl River Estuary and adjacent shelf waters in the summer. The average cell abundance of photosynthetic picoplankon (Pico) was 10⁴ cells/mL. Synechococcus was the dominant group in the inner estuary and coastal waters. Prochlorococcus was dominant in shelf waters. The proportion of Euk was less variable in the studied area. The abundances of Syn and Euk were positively correlated with nitrogen and silicon concentrations, whereas they were negatively correlated with temperature. However, %Pro had significant negative correlations with nitrogen, phosphorus and silicon, and positive correlations with temperature. There were differences in the niches between Pro and the other 2 groups of Pico in the wet season (summer), which was quite different from the observation in the dry season (winter).

The fish community in the marshes of the Florida Everglades is subject to huge seasonal fluctuations in the amount of flooded marsh, and thus of habitat. During the wet season, as the flooded area increases, the small fish community spreads across the flooded landscape and grows in population size. During the drying phase, the fish are crowded into smaller areas of permanent water. There they are exploited by higher trophic levels, such as wading birds, piscivorous fish, reptiles, and mammals. We develop a landscape simulation model of the lower trophic level food web that includes the small fish community, in which the various trophic levels are described by differential equations. Annual fluctuations in water level are represented by sinusoidally changing hydrology, resulting in dynamic patterns of flooded and non-flooded areas. In this paper we focus on describing the theoretical framework of the model and an analysis on a scenario with annual water level amplitude of 0.6 m. Within these gradients the fish are allowed to disperse and exploit the different habitat resources. To examine how the trophic levels react to annual changes in the water level, long-term simulations over a period of 10 years are performed. The model takes into account the seasonal flooding and drying over an area of many square kilometers, and predicts biomasses of fish across a heterogeneous landscape over time.

The fish community in the marshes of the Florida Everglades is subject to huge seasonal fluctuations in the amount of flooded marsh, and thus of habitat. These annual fluctuations in water level are represented by sinusoidally changing hydrology, resulting in dynamic patterns of flooded and non-flooded areas in the study area. In a previous accompanying paper we have developed a spatially explicit landscape simulation model of the lower trophic level food web that includes the small fish community, where we focus on an analysis of a baseline scenario with annual water level amplitude of 0.6 m. However, in the Everglades the fluctuations in water levels have various amplitudes, ranging from 0.2 m to 0.8 m, which have strong effects on the aquatic communities. In this paper we extend the analysis to cover several representing scenarios in which the water level fluctuation amplitudes vary between 0.2 m to 0.8 m.

Variability during the tidal cycle of the biochemical composition and phytopigment content of suspended particulate matter (SPM) in the bottom water were investigated in the Banzu Intertidal Sand Flat, Tokyo Bay, Japan in relation to the feeding environment and diet of Manila clam, Ruditapes phillippinarum. Biochemical composition of SPM in the bottom water showed large tidal variations, such as the ratio of phytopigment content to SPM (Phy/SPM ratio) and particulate organic carbon (Phy/POC ratio) were both higher during high tide periods compared to low tide periods. Therefore, it was considered that high tide periods form a suitable food environment for the clam. The results also indicated that phytoplankton which is transported from offshore at high tide is an important food source for the clam. In addition, results of stable isotope analyses indicated that R. phillippinarum selectively intakes SPM during high tide periods and assimilate selected components among the SPM.

In this study, the behavior of breasting dolphin caused by the wave force in the coastal area of Incheon, Korea has been investigated. The dynamic deflection, shear stress and moment of piles are analyzed considering the horizontal subgrade reaction coefficient resulted from loading tests for different DWT(Dead Weight Tonnage) of ships. The dynamic characteristics of piles in the accumulated and dredged soils show very similar patterns. It is shown that the resistance of dolphin to external load increases with the increase of pile diameter. The modeled bettered pile dolphin is more than 10 times stable than the vertical pile type based on the study of dynamic characteristics of dolphin.

In order to balance human activities and protection measures and realize the sustainable development of the coastal zone in Shanghai, a sub-project, as a part of Shanghai 908 Project, is conducted based on D-PSR-C framework. Firstly, some main anthropogenic pressures affecting coastal zone in Shanghai are identified. Secondly, environmental and ecological impacts are initially evaluated. Finally, the methodology for analyzing relationships between human activities and environmental and ecological evolution are presented.

In recent years, the environment improvement of marine pollution due to the eutrophication of the clay bed at the sea bottom has been considered. Various methods have been developed as covering method to reduce and to prevent the melting of the eutrophic elements such as phosphorous, nitrogen compound and sulfide from sea bottom sediment to sea water. In this study, a new method for restoration of sea water pollution has been developed to cover sea bottom sediment by using fly ash. The grain size of fly ash ranges from 5 to 40 mm, so that it can be considered that the eutrophic elements will be trapped in pore structure of fly ash. The field experiment and laboratory experiment results suggested that the covering fly ash trapped sediment in the porous media and reduced the suspended sediment on covering layer. Moreover, the covering fly ash restrained the upwelling of sea bottom sediment when the covering fly ash layer is over than 5 cm.

In previous studies, it has been pointed out that mahogany clams live in a deep layer (80 cm from ground surface) of the tidal flat located at the midstream of Hiroshima's Ota River. It is believed that a current of water transports organic matter for food into the deep layer of the tidal flat. In this paper, a series of field experiment and laboratory experiments was undertaken to look into the mechanism of organic matter movement under the effects of groundwater flow. The results suggested that organic matter was transported by groundwater flow into the deep layer of a tidal flat and it was also found that the void ratio and grain size of sand layer influenced on organic matter movement.

For the control and conservation of the ecology in the coastal zone such as tidal flat and bar, it is important to clarify the relationship between the disturbing factor and the behavior of target species living there. In this paper, to examine the relationship between the population dynamics of Uca lactea and sediment property, we have been carried out field observations at Narugashima Island and the Kakogawa River mouth in Hyogo prefecture, west Japan since 2006.

This study was conducted to develop the dissolved oxygen (DO) model in Inohana Lake, a stratified estuary during summer. An intensive field measurement of the current velocity, salinity, dissolved oxygen and phosphorus concentrations was carried out during the summertime of 2007, and the field data were used for the construction and verification of models. For the calculation of the advective and diffusive water flow rates in Inohana Lake system, the box model was constructed based on the mass balance of water and salt. The comparison between the modeled and ADCP-measured water flow rates shows that the model is capable of providing a good estimation of the summer-averaged water flow rates. The DO model was constructed using the advective and diffusive flow rates calculated by the box model and the measurements, which also shows a good estimation of the DO concentration under the stratified condition in Inohana Lake estuary.

This paper establishes a mathematical model of two-dimensional tidal current and migration and diffusion of oil spill in Guanhe River and the estuary where Chenjiagang Power Plant is located. Based on the validation of actual hydrological data and in conjunction with the control project for navigation channel of Guanhe Estuary, three conditions of oil spill under the typical spring tide and typical neap tide are respectively simulated through the mathematical model, i.e., 10t oil spill of ships in the water area of front dock, 100t oil spill at the starting point of channel, and 100t oil spill at the end point of channel. The results provide references for risk forecast and evaluation of accidental oil spill from ships during the operation of power plant to be built.

In this paper, the three-dimensional hydrodynamic and sediment transport model ECOMSED is applied to simulate the hydrodynamic changes of the sea area around the Tianjin Lingang shipbuilding & repairing base. There were four tidal gauge recorders and twelve field sampling stations of current data for model calibration in Bohai Sea. Modeled calculations demonstrate that modeled tidal elevation, tidal current velocity and direction are basically as same as the measurements. Based on the model calibration, the model predicts the effects on the surrounding sea area after the shipbuilding & repairing base is built, as well as the bound and degree of the suspended sediment diffusion caused by the harbor basin dredging and the hydraulic fill during the construction. The model also forecasts the oil-spill bound and transport track when such shipping accidents occur under the condition of no wind or adverse wind direction.

This paper presents new formulations for estimating the effective floc density (Δρ_f) and the relative viscosity (µ_r) of mixture of fine suspended sediments. Fitting parameters of the new models were calibrated using data available in the literature. Good comparisons were obtained when the settling velocities estimated based on the proposed models were compared against the settling velocity estimated from existing models found in the literature. The average value of the primary particle size, D_p for the data used in the analysis, inferred from the new model for Δρ_f was found to vary from 0.05 µm to 100 µm with a mean value of 2.5 µm. The new model for µ_r is applicable to mixtures of both non-cohesive and cohesive sediments.

The following sections are included:

• AUTHOR INDEX

The following sections are included:

• PREFACE

• CONTENTS

Nesting population of Loggerhead Turtles on Miyazaki Coast has been decreasing due to beach erosions and construction of seawalls. In order to restore the suitable coastal environment and retreated shoreline, a beach nourishment project had been carried out on this coast. The project experimentally utilized a large volume of nourishment materials excavated from an adjacent river to confirm an applicability of those materials to the beach nourishment. This study clears the applicability of excavated sediments to the beach nourishment through some soil tests, surveys of beach evolution, and monitoring of nesting population of Loggerhead Turtles.

A field observation, comprising bottom mounted instruments for near-bottom currents and suspended sediment concentrations, was carried out for 1-month at the Tama River mouth in Tokyo Bay. The measurements have captured sediment resuspension during extreme wave conditions during a passage of typhoon near the study site in the early September of 2007. The sediment resuspension occurred by waves and current and combined current-wave induced bottom shear stress reached 0.3 Pa. Based on the SS-flux analysis during the monitoring deployment, the net suspended sediment transport at the site was towards the south west or outer Tokyo Bay.

Study on suspended sediment properties have reached a new phase by the application of laser transmissometry equipments that enable researcher to observe the sediment grain size fluctuation. However, there are still some disagreements on the factor affecting the suspended sediment grain size fluctuation. This study was aimed to investigate properties characteristics of suspended sediment off a river mouth, in terms of grain size, and percentage of organic matter in the deposited sediment. For this purpose, a series of field observations have been conducted at inner shelf of Tenryu river mouth of Japan. The observations were conducted mainly by deploying a set of equipments at a point located 1.4 km from the coastline. The point has a depth of about 18.2 m from the mean sea level. Parameters measured were turbidity at two layers, i.e 60 cm above bed (cmab) and 230 cmab, horizontal and vertical currents profiles, wave heights and periods, salinity, suspended sediment particle size, and deposition rate. A Laser In-Situ Scattering and Transmissometry (LISST) 100 was employed to measure the fluctuation of suspended sediment particle size within the measurements period. To measure the suspended sediment deposition rate, a time series sediment trap was installed to collect the deposited suspended sedimenit at 160 cmab. Results proved that the suspended sediment median grain size fluctuation was relatively affected by tides.

Sedimentation of tidal inlet downstream sluice is universal and becomes more serious with the rapid course of tidal flat reclamation. Comprehensively using coastal geomorphology, estuary & coastal hydrodynamics and sediment hydraulics, WangGang channel, as an example, was studied on the adaptability of tidal flat reclamation and tidal inlet stability in Jiangsu coastal zone. Based on Remote Sensing technology, three reference curves were presented. By 2-D hydrodynamic numerical modeling, influence analysis of allowable maximal tidal flat reclamation was carried out, Using siltation calculation formula subordinated to technical specification for muddy coast, waterway and harbor basin, sedimentation intensity was discussed. After that, allowable maximal tidal flat reclamation was proposed.

Shanghai Nanhuizui inning project is the key project for the development and utilization of shanghai tideland resources. The project is located in Nanhui Beach, where is the confluent point of the Yangtze River Estuary and Hangzhou Bay. Nanhui Beach belongs to muddy coast and sediment movement is mainly based on suspend sediment movement. In this paper, a two-dimensional numerical model of wave, tidal current, sediment movement and seabed deformation process is established by using arbitrary triangle mesh and the numerical simulation which combines both the finite element and finite difference methods. The model is verified thoroughly according to the hydrology and sediment data measured in august 2006 and the bathymetric survey conducted between April 2005 and October 2006. Comparisons of modeled tidal levels, tidal currents velocity, direction, sediment concentration and seabed deformation with measurements indicate good agreement. Another important research area is mainly based on the current changes and seabed evolution of the South Passage of the Changjiang Delta, the north shore of Hangzhou Bay, the Donghai Bridge caused by the inning project.

In order to clarify the effect of pore water infiltration flow on the re-suspension and expansion of organic mud, in-door experiments were performed. The infiltration flow did not re-suspend organic mud. However, however, increase water content about 200% by the water containing ability of organic matters. Water content of organic mud mainly depends on the amount of organic matter (IL) and decomposition rate of organic matter (C/N ratio). And it is experimentally clarified that pore infiltration accelerates the amount of re-suspension and critical erosion threshold of organic mud.

Takase Flood Diversion Channel is usually closed by a sluice gate to retain freshwater creating domestic water sources, and to prevent saltwater intrusion to the lake, at the end of the channel. Closed time of the sluice gate creates a good condition for sand bar formation at the channel entrance under the action of waves. Basing on the conditions of waves and water depth at the entrance of the Takase Flood Diversion Channel as well as combination with the classification of sand bar formation in the previous researches (Nguyen (2005), (2006) and Tanaka (2005)), a demarcation between emergence and submergence of sand bar formation was proposed via the dimensionless water depth at the mouth. This paper shows that emerged sand bar forms certainly at the channel entrance in the winter with a present river mouth depth. In order to limit influences of sand bar on the operation of the channel entrance, water depth at the entrance should be larger as a result sand bar forming under the water level, when sluice gate is opened, the flow in the channel could flush the bar easily.

Scarce natural resources make it imperative for Korea to exploit nuclear power plant technology to supply energy for industrial purposes not to mention for everyday usage. Korea's nuclear power plant started when Gori Nuclear Plant started its operation in 1978 and as of today, there are 4 nuclear plants nationwide including the Gori Nuclear Plant, making up 38.2% of all of Korea's energy supply. Since "waste heat' is generated as a result of plant operation, sea water is needed for cooling purposes and therefore plants are situated near coastal areas. However, the effect on the coastal area such as erosion, deposition, and siltation from the construction of the plant itself is subject of continuing controversy and another being the effects on the coastal environment from warm water that is produced after the cooling process. Generally, topographic change is maintained in equilibrium by the tidal currents' reciprocating motion in the coastal areas where there are dominant tidal currents. However, artificial action on the current flow for operating a nuclear plant operation at the intake and the outlet breaks the equilibrium of the tides and this in the end results in disturbing the equilibrium condition of bottom topography. This research used the results of long term investigation data of water depth and data of flow discharge conducted inside the intake to investigate erosion and the change in siltation at the intake of the nuclear power plant. After having analyzed the changes in water depth of the intake area, the results confirmed that there are 100~140cm/year and 80~300 cm/year of excess siltalion at the middle area and both sides, respectively. After artificial dredging which is conducted every two years, siltation had proceeded at a substantial pace, and after some time, the pace has slowed down to its normal rate, going towards equilibrium condition. This research used the siltation pace change acquired from monitoring results to formulate coupled model in order to predict the change of water depth which will take place due to artificial construction of the intake in the future more precisely.

Contaminant transport in the water environment includes physical, chemical and biological contaminant. This paper deals with physical contaminant, and in particular, suspended sediment in open water. The need for sediment control is gaining importance in this challenging time, especially in regions where extensive dredging, reclamation, nearshore and coastal construction activities are being carried out. These activities are the source of huge amount of sediment flowing into the water and marine environment and may significantly impact the well-being of existing marine ecology, habitat and environment such as those for coral reefs, marine animals, etc. Beside appropriate measures to control the generation of sediment, the only viable means appears to be installation of silt screen to contain and control the spreading of sediment in open water.

Silt screen installation, being one of the most popular best management practices, has been used extensively in many countries to improve and achieve sediment retention and sedimentation. In the marine environment, silt screens represent both a barrier to improve sedimentation and a mean of particles retention. Despite its popular application, the efficiency of a silt screen is indeed subjective at best. The effectiveness of silt screens as a method of turbidity control is highly influenced by various factors such as the site characteristics, sediment properties, screen configuration. etc. In marine projects involving deployment of silt screens, and as part of the environment management process, it is important to conduct regular sediment control/monitoring in addition to appropriate selection of the types of silt screen and deciding on the proper installation method during the planning stage. The planning process of a silt screen system requires careful design, installation and monitoring process, starting from understanding the nature of the area where silt screen is intended to be installed to selection of parameters and criteria used for monitoring. There are certain specific steps/procedures, usually recommended by silt-screen providers, and could be adopted to ensure the suitability of the silt screen for certain sites. These recommended approaches, though differ somewhat from one provider to another, do give due consideration to the flow field, hydraulic properties of the silt-screen and sediment characteristics. These processes are illustrated with application examples in Singapore, Korea and Hong Kong.

Extensive accumulation of soft mud at the head of Tokyo Bay, Japan, is one of the major causes of deterioration of water quality and ecosystems. We performed field observation of sediment quality and numerical simulation of sediment accumulation and grain size distribution to reveal the mechanism of its accumulation and provide suggestions for the future restoration strategy in the bay. We reveal the detailed variation in sediment quality and found that one of the causes is attributed to the lower decomposition rate of organic matter due tu the long–term exposure to hypoxic waters along with the higher rate of accumulation of very fine particles reflecting hydrodynamic properties.

Sediment transport and morphodynamics of the My A inlet are simulated and analyzed using Delft3D process-based numerical model. The processes of waves, tides, river flows, sediment transport and bed level changes are taken into account in the simulation model. Based on the simulation results, inlet morphodynamics are analyzed to gain insight into the cause of inlet closure. The main reason of inlet closure is found due to both wave-driven onshore and longshore sediment transports.

We propose a method for deducing past coastal conditions and creating a predicted image of the former coast, using old site photographs as well as the comparison of old photographs with aerial photographs taken in the same period. The past coastal conditions of the Shonan coast were determined by this method as an example. This method is effective for helping local people remember the past conditions of the coast and for facilitating understanding of the effect of future shore protection works. It is also expected to be useful for coastal planners by providing them with images of the beach to be restored.

This study focuses on long-term quantification of in situ coastal surfers based on video monitoring technique. An algorithm was developed and validated to automatically count surfers in recorded images. Temporal distribution of surfer behaviors was investigated in terms of hourly, daily, weekly and monthly variations of averaged surfer numbers. Dependence on temperature and wave height was also discussed and the favorite physical conditions for surfing were specified.

An X-band nautical radar system was employed to examine along shore structure of low frequency run-up motion in Hasaki beach, Japan. Analyses on series of radar echo images were done to estimate longshore distribution of shoreline positions and inter-tidal foreshore profiles using time-averaged images. Spatio-temporal variation of water fronts were digitized manually from cross-shore time stack images. Run-up heights were then estimated from the digitized water fronts with the help of foreshore profile. Low frequency motion in the run-up variations were observed from their spectral characteristics, which was traveling in the longshore direction. Longshore structure of this motion was examined and compared the motion between different wave incidences during two typhoon events.

The Modified Bayesian Method for estimating directional wave spectra from HF ocean radar has been improved. In this paper, we have proposed methodological approaches in order to overcome the numerical instabilities that remain at the lower spectral frequency. The improvement results show that the estimated directional wave spectra are in good agreement with in situ observation. The effectiveness of the proposed method has been also numerically confirmed by actual field data.

This paper newly develops a monitoring system for nearshore morphology using successive still images. The model consists of: (i) extraction of wave crest lines from the obtained digital images and (ii) estimation of wave phase velocity and corresponding bathymetry. Special stress was put on practical applicability of the entire system to various nearshore conditions. The model was tested against successive still images which might be relatively easy to obtain in various nearshore area. Numerical experiments were also performed to investigate optimum or critical conditions of the system in terms of obtained images and nearshore wave fields. Through the model tests, it was found that, to obtain reasonable estimation of the bathymetry, the system only requires 20 to 30 digital images with time intervals of 20 to 80 percents of the observed wave periods.

To predict and prevent natural disaster such as inundation at the coastal area, the offer of precise forecast and hazard map is necessary. The accuracy of inundation prediction and hazard map is preliminarily determined by the coastal geospalial information's accuracy among other factors. Considering the characteristic of coastal area as an intertidal zone, it has always changed following by the tide and wave having the coexistence of connection sea and land. Thus, there are not exist sufficient geospalial information in the established topographic and bathymetric data.

Therefore, we have measured topography and surveyed bathymetry using terrestrial LiDAR and MBES to make precise and fine-scale resolution coastal map. For the geo-referencing of these two kinds of data, we have done Network-RTK and tide measurement. After unify x, y, z coordinate system, we have constructed accurate fine-scale resolution coastal mapped DEM and DSM through the integration of LiDAR and MBES data with registering other supplementary data. Now it has used to input data for the numerical inundation model and hazard map. It can also possible to use monitoring and analysis of beach process such as an erosion/deposition through cyclic long-term measurement considering with the artificial beach transition based on GIS-based 3D spatial analysis.

Australia is the driest continent on the earth, but its coastal areas receive relatively high rainfall, its relative flat topography limits the size and number of inland reservoirs, consequently more than 90% of runoff runs into the sea without being used. This paper assesses the amount of runoff lost to the sea in rivers near Australian cities, and aims at its development using the coastal reservoir technology: the surface water will be collected by rivers/creeks and temporally stored in the sea by coastal reservoirs, and then it could be recharged to the ground as groundwater and then feed water treatment plants or desalination plants, by-pass canal could prevent contaminants from these cities. The locations of these coastal reservoirs are presented and the feasibility is analyzed.

Natural morphologies, such as sand dunes, river mouth bars and wetlands around a river mouth, are formed by dynamic processes of waves, river currents and wind, and are dynamically stable unless a large-scale anthropogenic effect is induced. Their coastal protection and ecosystem functions for maintaining habitats of many organisms were re-evaluated. The sand dune and wetland in front of an earth dike were maintained as they were, and the overall morphology was regarded as a shore protection facility against storm surges. The setting back of the protection line for maintaining a sand bar and a salt marsh was planned for the first time in Japan with the participation of local citizens and stakeholders, and the construction was completed in 2005. These conservation activities are effective not only for enhancing the safety of the area but also for keeping the sustainability of fishery.

A new high technology dist will be built in the top part of Jiaozhou Bay in Qingdao China within near future. There is a marsh with hundreds of Square Kilometers around the area. So a zoology dist aiming at improving environmental quality has been in plan to be constructed in order to meet the requirement of fresh water of the dist and protection of the marsh. In order to get the fresh water, a fresh water reservoir will be built in front of the existing three small fresh water rivers named as Baisha River, Moshui River and Yangmaogou respectively. Average discharges of those rivers are around 50m³/s. Fresh water in the reservoir will be released of when the flux of fresh water is much enough and the tide level in front of dam is lower than the level of reservoir water, which helps to prevent fresh water from being mixed with salty water. Based on the essential problems being relevant to the reservoir dam and important significance of fresh water reservoir, the present work provides three kinds of location of dam design and demonstrates which one among the three schemes is most reasonable by simulating the ocean, river flow and predicting sedimentation environment. During simulating, the moving boundary technologies are applied since topography of the reservoir is shallow and the area includes large tidal flat. The concrete work consist of: (1) studying the effects of the three layouts of dam on tidal level in detail; (2) calculating the water surface elevation difference between cases of construction and non-construction of the dam: (3) predicting accretion and sedimentation environment induced by the dam construction. Generally, to find the effects induced by the dam is the most important purpose of the present work. As the real case concerned, the values of time series of water level have a good agreement on observed data.

The Tarn Giang - Cau Hai lagoon system in Vietnam is the largest in its kind in South East Asia. Intensification of agriculture and extension of aquaculture is increasing the pressure on the natural resources by introducing fertilizers and pesticides into the system. This study focuses on quantification of the relationship between agriculture in the drainage basin, aquaculture in the lagoon and the water quality of the coastal ecosystem. Based on extensive literature research the use of fertilizers and some popular pesticides is estimated. Through mapping of historic and present spatial extension and analysis of future planning, the load of substances from agriculture and aquaculture to the lagoon system, are quantified. Implementation of a 2D hydrodynamic and water quality model (Delft3D model) allows the estimation of present and future concentrations of substances in the water of the lagoon. Based on this, this study concludes that planned extension and intensification of agriculture and aquaculture will lead to serious exceedance of internationally accepted water quality standards, indicating overexploitation of resources and increasing risk of serious problems with ecosystem functioning. This study also produces relevant information for policymakers to estimate maximum use of the system in relation to spatial differences, seasons and interventions that lead to changed patterns of flushing of the lagoon.

This article discusses the evolution of the Yangtze River Estuary and reveals that it extends towards the sea in the way of node-controlling. The formation, characteristics, and effect of the river rodes are explored. Recent evolution of the Xuliujing-Node and adjacent reaches are analyzed, indicating that any delay of the regulation projects would seriously threaten the stability of the estuary.

Tianjin Port is a typical silt coast port sediment there is very thin, with a median size of d₅₀=0.006mm, and the beach surface is gentle, approximately 1/2000, it was once a world-famous serious back silting port. Since 1952 the port was put into operation, through more than half century's construction and research, it has been gradually regulated to a light back silting port. This article has analyzed the research results of sediment treatment of Tianjin port in different construction time. According to long-term actual measures on hydrology, sediment etc. with many kinds of methods to conduct a long-tents track type experimental study to the Tianjin port, such as original view analysis, physical model, mathematical model, water trough experiment, neutron traces, remote sensing analysis and so on, the article has clarified the sediment origin of Tianjin port area; sediment movement shape; sediment distribution law in the port and channel.

The present paper develops a methodology for estimating the risks and consequences of possible future increases in tropical cyclone intensities that can allow for the cost of mitigation strategies in port infrastructure to be evaluated It uses a Monte Carlo Simulation to obtain the expected number of hours that a certain area can expect to be affected by winds of a certain strength, and then evaluates the relationship between port infrastructure and Japanese economic growth. Finally, the expected increase in expenditure due to climate change can be evaluated

Survival analysis was applied to the lifetime of three types of coastal facilities. From the results, the definition of lifetime should differ depending on the collapse of coastal levee, loss of armor units and subsidence of coastal levee. Compared to the normal lifetime of 50 years, the lifetime of coastal levees is almost the same and that of armor units is almost half. The lifetime of subsidence of coastal levees has a wide range, and in the shortest case, is almost one quarter.

Ocean observations and numerical modeling have performed cyclic long-term routine to measure the various kinds of marine and coastal environment information and analyze the specific phenomenon. From that, numerous data have accumulated and it is hard to handle and utilize without systematic data management and scientific visualization. Therefore, for the rapid interpretation and dissemination of useful information through the web. it is necessary to develop the real-time Web-GIS based integrated coastal information service system of automatic data collection, implementation of marine geo-database and proper data representations and visualization. It will contribute to coastal environment monitoring, forecasting and policy decision. In this work, we have implemented Web-GIS-based coastal environment-information service system about on the Saemangeum coastal area. It can be utilized the coastal environment management and conservation from the development such as improvement of water quality, offer of warning and protection.

The cyclone 'Nargis' hit the southern part of Myanmar on May 2^nd and 3^rd 2008. This devastating cyclone caused enormous number of casualties as well as fatal damages to houses and paddy fields, particularly both the downstream areas of the Irrawaddy and Yangon Rivers. In the present field survey, thought the activities were limited to the area near Yangon city due to certain governmental restrictions, it was found out that the tide due to the storm surge was probably up to 3 – 4m and came up to around 50 kilometers upstream of the river mouth of Yangon River.

A regional vulnerability assessment on impact of sea-level rise due to global warming with storm surge in Asia and Oceania coast was implemented in detail according SRES scenario. The quantity results of this study remarked that population growth is larger factor than sea level rise, especially by the year of 2050. The impacts of sea-level rise will appear the coasts after the year of 2050, but total impacts for coastal inhabitant depend on population change.

In this paper the reliability analysis of sea flood defence systems and the probabilistic approach of the design of the sea flood defences are outlined, The application of probabilistic design methods offers the designer a way to unify the design of engineering structures, processes and management systems. For this reason there is a growing interest in the use of these methods in the design and safety analysis of civil engineering system including coastal flood defences. In this paper these methods are critical reviewed, The so-call probabilistic safety assessment and reliability based design models are developed and applied to a coastal flood defence system in Nam Dinh, Vietnam. Au accurate safety assessment of the existing coastal defence system and a set of reliability based solution are, therefore, of large importance for rehabilitating coastal flood defences of the considered case study area. In accordance with present situation and analysis results, the coastal flood defences in Nam Dinh is not strong enough to withstand the actual sea boundary condition and ensure the safety for protected areas in views of present socio-economic development. As part of knowledge transfers, the analysis results could contribute to fundamental base for long-term: planning rehabilitation of the sea defences in Vietnam.

An image-based system to quantify the temporal-spatial distribution of sediment concentration was developed on the basis of the light-extinction principle. The relation between image signal and concentration is experimentally investigated and formulated using the modified Beer-Lambert law. It was found that the present system provided satisfactory results for concentration measurement in laboratory flume and was applicable for higher concentration than existing techniques.

The velocity field characteristics and variations in coastal water properties around Tama River estuary in Tokyo Bay in winter of 2006 were investigated based on intensive field surveys and numerical simulations. Measurement and simulation results showed that the residual currents off the estuary were strongly affected by winds. A stable north wind intensified the intrusion of oceanic water along the bottom layer, and a sudden increase in the bottom temperature off the estuary occurred. Furthermore, a strong south wind forced the intruded oceanic water to return to the bay mouth region and caused the coastal upwelling along the west coast of the bay. The combination of north and south winds was shown to be an important factor influencing the intrusion of oceanic water into the Tama River estuary.

Modeling of cooled waler discharge has been carried out to investigate whether the cooled water discharged from Open Rack Vaporisers conforms to international standards. CORMIX and VISJET models are applied to simulate the behavior of negative buoyant jet. The results show that the degree of negative buoyancy does not show crucial influence on the dilution rate because initial momentum is dominant in the near-field region. In case of no ambient current, dilution results by empirical equation, CORMIX and VISJET appear to be in good agreement with others. However, as the ambient current speed increases to 1.0 m/s. VISJET gives higher dilution compared with the value of dilution equation or CORMIX. This result arises from the fact that assumption of merging between nearby jets is not adopted in VISJET model. Thus, non-merging plume induces more entrainment effect and dilutes much a lot as it travels away from the outfall port. Dilution rate by empirical equation assumes complete merging of the individual jets and unidirectional dispersion trajectory so that it has a tendency to underestimate dilution rate. Among the cases studied in this simulation, maximum dilution achieved by the staged diffuser occurs at S711 and B711 cases (ambient depth = 7 m, current speed = 1.0 m, discharge = 0.944 cms) since ambient current speed 1.0 m/s and effluent density higher than ambient density prevent the plume from clashing onto the water surface and the plume moves hundreds of meters away without any interference. On the contrary, minimum dilution (maximum temperature differentials) is observed for Case B502 ( =-16 degree, ambient depth =5 m, current speed = 1.0 m, discharge = 4.722 cms). The dilution for this case is 6.3 and 8.2, and ∆T calculated by CORMIX and VISJET are 2.54 and 1.96 degree, respectively. These values conform to international standards (the temperature decrease should be equal to or less than 3 degree within 100 meters of the discharge point).

This paper discusses the effects of the sporadic intrusion of outer sea water into the coastal lagoon of Puerto Galera in the Philippines. The analyses were based on data set obtained from intensive field observations together with hydrodynamic and water quality numerical simulations. Fortnight concurrent measurements of hydrographic, bio-chemical and meteorological properties of the coastal lagoon were carried out in summer 2007. Results suggested that massive intermittent supplies of the outer sea deep water occurred through the north-west channel and could substantially enhance the water exchange between the inner part of the lagoon and the outer sea by rapid replacement of poor quality water inside the lagoon with cooler outer sea water mass characterized by lower nutrient and chlorophyll-a concentrations. Moreover, numerical simulation scenario analyses pointed out that tidal currents were relatively weak at the inner most part of the lagoon. At this location, the overall circulation and corresponding water quality were influenced by the intrusions of outer sea water mass as well as the general circulation driven by wind and density differences dictated by water temperature.

MIKE11 has been used to simulate the process of saline water intrusion into the estuary of the Ca river and its tributaries in a number of scenarios. With the results, the appropriate solutions are recommended to mitigate and control negative effect of saline water intrusion to socio-economic activities at the downstream of Ca river.

Water quality modelling is usually coupled with hydrodynamic simulation, where calculation of concentration is performed after the flow field has been established as an output of hydrodynamic simulation. The compulation of concentration is largely confined to the hydrodynamic grid. In practice this is generally acceptable, as usually the most prominent mixing process with high gradient in concentration is also where the flow is rapid and the resolution of hydrodynamic grid is fine. However, there are cases in which locations of the largest concentration gradient do not coincide with large hydrodynamic flow gradient (such as contaminant spilling from a point source into tranquil ambient water), or where the location of intense mixing is not of special interest (concentration should be estimated somewhere else in more steady flow condition). Under these circumstances, we may wish to design a specific mesh for estimating the concentration, rather than using the same mesh as that with hydrodynamic computation. The writers propose using coupled quadtree grids for hydrodynamic and water quality simulation. The grids are adaptive and allow liner resolution in regions with high gradients of flow and concentration, which constantly vary as the system evolves. As a demonstration of the proposed technique, a test case was presented in which a plume is issued from a multiple ports diffuser system. The results obtained are compared against analytical calculation. The achievable accuracy and the computational efficiency are discussed.

Three-dimensional velocity in the wake of a stationary circular cylinder inclined at an angle α in the rauge of 0°–45° are analysed using the wavelet multiresolution technique. This study aims to examine the dependence of the velocity at different wavelet levels on α. The validity of the Independence Principle (IP) for vortex shedding was also examined. It was found that the peak frequency of energy spectra has the smallest variation among different inclination angles at wavelet level 6: which corresponds to the frequency band of Kármán vortex shedding. The deviation of peak frequency from the IP at α = 45° is much larger than the experimental uncertainty, which may indicate that the IP is only applicable for α < 45°. The energy spectra are very weak at wavelet levels that represent intermediate and small scale structures while they are strong at wavelet levels 6–8 which represent the large scale structures.

Three-dimensional velocity in the wake of an inclined stationary circular cylinder was measured simultaneously using a multi-hot wire vorticity probe at x/d = 10, 20 and 40. The study aimed to examine the dependence of the wake characteristics on cylinder inclination angle α (= 0°~45°). The validity of the independence principle (IP) for vortex shedding was also examined. It was found that the spanwise mean velocity , which represents tie three-dimentionality of the wake flow, increases monotonically with α. The vortex shedding frequency decreases with the increase of α. The Strouhal number (St_N), obtained by using the velocity component normal to the cylinder axis, remains approximately a constant within the experimental uncertainly (±8%) when α is smaller than about 40°. The autocorrelation coefficients of the u and v velocity signals show apparent periodicity for all inclination angles. With increasing α, these coefficients decrease and approach zero quickly. In contrast, the autocorrelation coefficient of w increases with α, implying an enhanced three-dimensionality of the wake.

This paper aims to investigate the effects of angle of attack (α) and gap ratio (η) have on the amplitude of the vortex-induced vibrations (VIV) of a double cylinder system. Two rigid circular cylinders of unequal diameters were elastically mounted and subjected to a transverse air flow in a wind tunnel. The secondary cylinder with a diameter of 40 mm was rigidly attached to a primary cylinder of a diameter 80 mm. The amplitudes of vibration at five angle of attack, namely α = 0°, 45°, 90°, 135° and 180°, and five cylinder gap ratios, namely η = 0.1, 0.2, 0.3, 0.4 and 0.5, were tested. A single cylinder was also tested to validate the current experimental setup and used as a benchmark for the double cylinder system. It was found that both the angle of attack and the gap ratio affect significantly the amplitude of vibrations of the double cylinder system. The amplitude of vibrations increased from α = 0° to α = 90° where it reached larger amplitudes than that for a single cylinder. The amplitude then decreased as the angle of attack of the system was changed from 135° to 180°. Most configurations displayed a consistent decrease in amplitude of vibration as the gap ratio was increased, which was accompanied by a decrease in reduced velocity (V_r) at the peak amplitudes.

One of the critical factors to influence tension of an inclined cylinder is vortex-induced vibration. In this study, the pattern analysis for the vortex induced vibration of an inclined cylinder is presented with the experiment of a towed cable. For a towed cable system, it is found that strength and frequency in VTV with towing speeds are strongly related with an inclined angle of a towed cable. A towed cable fluctuates in local Strouhal frequency. From experiment results, it is shown that VIV strength decreased with increasing speed and VIV frequency is proportional to the value of sin theta due to the change from a circle to an ellipse in the cross section of a towed cable. The results of this study are in a good agreement with them of reference. Prediction in VIV for an inclined cylinder can be done with the results of this study.

This study aims to investigate the flow structure in the near wake of a vertical, circular cylinder in shallow water. The Reynolds number based on the cylinder diameter is 4500 and the approach boundary layer is fully developed with a thickness of the order of the cylinder diameter. The flow fields are extensively measured using a double-frame, double-exposure Particle Image Velocimetry (PIV) system, which has a resolution of 1.6K × 1.2K pixels and a frame rate of 15 Hz. About 1000 instantaneous velocity fields are obtained and ensemble-averaged to obtain the mean and turbulent statistical information of the flow in various planes. The 3-dimensional (3D) flow structures, with the emphasis on the horseshoe vortex system that is inherent in junction flow, are discussed in terms of both instantaneous and mean flow patterns with quantitative representations.

This work is experimental studies of the turbulent vortex structures and momentum transport in the wake of side-by-side multiple circular cylinders. The spacing between the side-by-side cylinders is 3d (d is the cylinder diameter). Velocity fluctuations are measured by a moveable three-dimensional vorticity hot-wire probe. The phase reference is provided by a fixed X-wire probe. Vorticity measurements have been conducted at x/d = 10 at a Reynolds number of 7000 (based on d and the free stream velocity U_∞). In this work, vortical structures after side-by-side multiple cylinders will be examined using phase averaging techniques. For phase averaging, the signals from the reference X-wire are band-pass filtered with the centre frequency set at the vortex shedding frequency detected in the near region of the wake. The vortical structures are then examined by plotting the phase-averaged vorticity contours.

In recent several years, extremely high swell are occasionally occurred in the East Sea of Korea. In this paper, the multi-station wave observation records of high swell event during 23th to 25th February in 2008 and their significant characteristics are reported. At that time, three people were dead at the breakwater of Anmok harbor by being swept by the high swell. The reason for appearance of the high swell is the strong extra-tropical low pressure system that is rapidly developed in the East Sea of Korea. Such a strong low pressure system can be well developed in winter season and may cause severe disaster on the coast of Korea and Japan. Hence, it is needed to enhance predictability of the high swell by carrying out researches in order to more thoroughly understand the detailed mechanism related to the development of winter season low pressure system.

Geo-scientific data is inherently three-dimensional. Despite this many field geo-scientist still rely on paper-based mapping methodologies in which three dimensional real world data are simplified and displayed in two dimensions. Recent technologies have developed sophisticated methods using high resolution 3D survey data to build detailed 3D models of the land surface, useful for studies on impact and vulnerability. Modern optical 3D measurements and visualization techniques now allow land features to be measured at higher orders of accuracy. Real-time Kinematics GPS, with centimetre spatial precision, allows each virtual model to be geospatially positioned correctly and allows several overlapping models to he stitched together seamlessly. In this paper we share our experience in creating a high resolution Digital Elevation Model (DEM) by integrating remote sensing and various field-based data collection techniques. With the DEM thus created a distinctive attempt was made to develop a Geographical Information System (GIS) for spatial inundation modelling for sea level rise at various tide levels.

A modern mapping technology such as, Global Positioning System (GPS) with Real Time Kinematics (RTK) and 3D terrestrial laser scanner have led to quickly obtain high-resolution control on topographical surveying with cm-level position accuracy. Advances in spatial analytical software allow Digital Elevation Model (DEM) to measure and monitor morphological changes across a variety of spatial scale, such as to map the spatial patterns of erosion, deposition and horizontal dune migration, and calculate the volume of mobilized sand. These techniques were applied to the Nakatajima dune. The Nakatajima dune is approximately 1 km length (West to East) and 0.6 km width, located near Magome River mouth on the Enshu-Nada coast. Hamamatsu city of Japan. The dune is being pushed eastward by the predominant westerly wind. In surveying Nakatajima dune over two years period (2007-2008), we have found the Eastern end of the dune developed 6-7 m per year with more than 7 m height. The averaged volume of sand of the eastward migration was approximately 2450 m³/year into the study area. Moreover, the source of the sand transported mostly from the dune itself and limited amount of sand come from the shoreline, resulting in the decrease in the elevation of windward slope in the middle part of the dune, and showed the eastward migration with ranged 3-4 m per year.

In this paper, the structural health monitoring system for "Uldolmok Tidal Current Power Plant (TCPP)" is briefly introduced and the measured data obtained up to now are analyzed. TCPP is basically constructed in the ocean area with high current speed, and therefore the current loading is governing the structural safety than the wave or wind loadings. Usually the soft soils are eroded due to the current and the soft and hard rocks are composing the seabed in strait which tidal current of high speed. Therefore the coring is not so easy due to rock seabed condition and also the operational time is very limited. And also the structural members should not be over designed with large size of steel pipe not to obstruct the tidal current. Due to the difficulties in coastal construction, relatively severe current loadings, and optimized slender structural members, it is very important to monitor the structural safety of the tidal current power plant in normal operation condition and also in severe storm condition. However, the sensor installation is much more difficult for TCPP structure than the in-land structures such as bridges and buildings since the sensors should be fully water-proof and the cables should be able to endure the corrosive condition. In this study, we installed the sensors under the sea level and are going to install the sensors outside sea in this year after the structure is constructed. Now the structure is under construction. The conventional type strain sensors (KM-100B) and smart FBG optical sensors (from Micron Optics) were installed in the bottom part of the jacket legs to measure the dynamic and static strains and the MFC (Macro Fiber Composite) sensors were also installed at the same location to measure the impedance change due to loading and corrosion conditions. Guidelines

The bathymetry data with high precision are derived from multibeam echo-sounder, but this survey is unsustainable for bathymetry monitoring because of high cost. In this study, we suggest the method to get the bathymetry changes in a wide area using fish finder data of shirasu fishing boats. This method is low cost, but possible to operate frequent monitoring. The depth differences of several ten centimeters are shown between the fish finder and multibeam sonar. However, it is confirmed that the trend of sea bottom in both the bathymetry is pretty similar.

AUTHOR INDEX

The following sections are included:

• PREFACE

• CONTENTS

A 30-year long daily volume flow rate data in Seine River were analyzed by box-counting method and Empirical Mode Decomposition(EMD) method to examine the characteristics of flow rate fluctuations. By using the box-counting method, the clustering properties of data are represented by D_B - V_C graph where multi-fractal properties of the data can also be shown to exist. Then, the daily data were decomposed into 12 intrinsic mode functions(IMFs) successfully using the EMD method. It was found that the most energy-containing modes be dominated by annual and El-Nino/Southern Oscillation events. The statistics of first 6 mode functions were then calculated and the most important finding is that the probability density functions of IMFs are not Gaussian, but can be well fitted by an exponential decaying functions except the 1^st IMF mode.

Application of the L-moments method for statistical analysis of extreme wave heights extracted by the POT method is made for storm wave data at eight stations around Japan, which have the record length of 27 to 38 years. The formulas of the L-moments of the Weibull distribution are newly derived for estimation of the shape, scale and location parameters from a sample. A new index called TUD (Twenty-Up Deviation) is developed for judgment of the degree of goodness of data fitting to a candidate distribution. Among eight stations, two stations show the best fitting to the Weibull distribution, four to the General Pareto (GPA) distribution, and two to the General Extreme Value (GEV) distribution. At two stations fitted to the GPA distribution, the theoretical upper bounds of extreme wave heights are only 7% to 11% greater than the observed maximum wave height

Sea current in enclosed coastal sea is composed of tidal current and non-tidal current. In the paper, we investigated the influence of sea-surface wind on tidal current obtained by HF radar. By using harmonic analysis and 25 hours moving average analysis, sea-current is separated to tidal component and non-tidal component. Then, we carried out multi-regression analysis by using to 25 hours average current data and 24 hours moving average wind data. From this study, we found following conclusions. (1) Non-tidal component of tidal current obtained by HF Radar is strongly influenced by sea-surface wind. (2) In the area of the head of Tokyo Bay, it is shown that clock-wise circulation is always generated.

Variations of temperature, salinity and density over the southern continental shelf of the Caspian Sea, off Babolsar port in the north of Iran in autumn 2008 were investigated. Vertical variation of temperature was between 17.9°C to 9.2°C from sea surface to 42 m depth. A seasonal thermocline located below 30 m depths with more than 8°C temperature gradient across it. The salinity and density were found to vary between 12.06–12.67 psu and 1008.6–1010.4 kg/m³, respectively. Due to small salinity values of the Caspian Sea water, the density changes highly correlated with variations of water temperature.

As near-bottom current velocity increases, sandy bed geometries dramatically change from rippled bed to sheet-flow bed and thus it is essentially important for coastal engineers to appropriately evaluate bed conditions and their corresponding equivalent bottom roughness, k_n. This research focuses on development of experimental setup using oscillatory flow tunnel (OFT) to capture interactive relationships between bed geometry and corresponding k_n. A number of experiments with scales comparable to field conditions are performed to investigate k_n on movable bed of uniform sand grains (D₅₀=0.195mm) under pure wave motions. Experimental conditions mainly lie within the "break-off" range, in which bed form changes from rippled to sheet flow bed. Ripple geometries are also measured during the experiments. The experimental setup directly measures the instantaneous pressure gradient and flow velocity, which provide estimation of bottom shear stress, τ , and corresponding wave friction factor, f_w, and k_n. The values of experimentally obtained f_w and computed k_n from ripple geometries exhibit close agreement with previous laboratory studies. This paper presents details of experimental setup using OFT, measurement technique along with data processing and discusses interactive relationships among f_w, k_n, and ripple geometries.

The equivalent resistance coefficient including the effect of drag caused by obstructions as well as a bottom roughness was investigated. The equivalent resistance coefficient can be utilized for inundation simulations that use relatively larger grids as applying the coefficient into the bottom friction term in the shallow water equation model. In order to investigate the equivalent resistance coefficient, the hydraulic experiment was performed with unsubmerged square piers in an open channel. The piers were arranged with an equal interval along longitudinal and transverse directions, and the water depth of a mean uniform flow was measured for various discharges. The equivalent resistance coefficient n-value was evaluated by applying the measured data to the Manning's equation. A coefficient implicating the interaction effect of piers' drag was estimated based on the experimental results. And as including this drag interaction coefficient a semi-analytical formula of the equivalent resistance coefficient was derived from momentum analysis. The semi-analytical formula was compared with the experimental results. From the comparisons it was found that when the unsubmerged piers were aligned in open channel, the equivalent resistance coefficient was strongly dependent on the interval of piers, and the n-value increased nonlinearly with the water depth.

The storm surge data calculated numerically at 52 major harbors in Korea for 56 years from 1951 to 2006 are analyzed by using the annual maxima method, peaks-over-threshold method, and empirical simulation technique. The empirical simulation technique and the peaks-over-threshold method give similar return values, while the annual maxima method gives smaller values. The extreme sea levels are also evaluated by the empirical simulation technique including tide effect, showing good agreement with the result of Jeong et al. who used extreme sea level data observed at tide stations.

Wave-current interaction due to strong ambient currents causes to alter wave properties such as wave height wave profiles and wave spectrum. Numerical experiments have been conducted to examine the change of the design wave properties due to the strong tidal currents over 1m/s at the mouth of Garolim Bay, Korea. For the design wave period of 8~10sec, the design wave height of 3m was increased by up to 40% when the waves encounter the opposing maximum current of 1.4m/s while the wave height was reduced by 26% due to the following currents at the bay mouth. The 16 experimental cases with the different combinations of wave-current-tidal water depth were simulated.

Applicability of two well-regarded Boussinesq-type equations in simulating evolution of nonlinear water waves and currents over submerged breakwaters is further investigated. An artificial energy dissipation term is introduced to overcome unrealistic flow patterns that lead to numerical instabilities near abrupt depth configurations. The predictive skills of the models are investigated using new set of experimenlal data. The simulated wave height, mean water levels, and nearshore circulation patterns show good agreement with the experimental data, if the breaking induced energy dissipation sub-model is properly calibrated.

A new idea to incorporate the wave breaking phenomena in deep and shallow water in wind wave-current interaction process explicitly in atmosphere-wind wave-ocean coupled model has been proposed in this study. The whitecapping in deep water and the depth-induced wave breaking in shallow water are particularly considered in momentum transfer processes explicitly using common exchanging variables between wind wave and current models, while the turbulence production and other phenomena under wave breaking is considered implicitly using wave energy dissipation coefficients due to whitecapping and depth-induced wave breaking. From the preliminary results of three tropical storm events, distinctive features of spatial distribution of momentum flux due to wave breaking were found over the developed shelf areas, which should not be overlooked in shallow water dynamics.

This is study experimentally investigates wave-Current interactions near a river mouth and proposes a numerical model 10 simulate hydrodynamics in wave-current coexisting fields. The experimental results show that the wave height gradually increases as wave approach the river mouth. The current velocity decreases with continuous wave-current interactions. The wave period, the intensity of currents, and the angle of the incident wave are confirmed to be key parameters to govern the wave-current interaction. The proposed numerical model is found to reproduce well the experimental results.

Based on the global meteorological forecasting system starting in 1990's, earth system simulation models, such as earth simulator, have been developed and applied to many kind of environmental assessment. This paper introduces the framework and applications of the Regional Environment Simulator (RES) which consists of main models for atmosphere, land surface, ocean, hydrology, dynamic vegetation, and coastal, river, estuary models and urban air-water environment model. RES has been developed in IDEC, Hiroshima University for international sustainable development and cooperation. This paper shows model structure and its application.

Nonlinear regular and focused waves induced by a piston wave maker were simulated in potential theory based on a fully nonlinear numerical wave tank model. The model is developed by using a time domain higher-order boundary element method (HOBEM) including a mixed Eulerian-Lagrangian technique and a 4th-order Runge-Kutta scheme as a time marching process. As the input boundary condition is different from some traditional methods with fixed input boundary, the instantaneous wave maker position combined with transient free surface are updated at each time step. The physical and geometrical variables of new positions are obtained from the former ones using a quadratic shape function. At the downstream boundary, an artificial damping zone is used to prevent wave reflection back into the computational domain. Image Green function is used in the whole fluid domain so that the integration on the lateral walls and bottom are excluded. To validate the present model, physical experiments on regular and crest/trough focused waves were carried out in a wave flume. Good agreements between numerical results and experimental data are obtained. The nonlinear features and kinematics of waves are further presented.

A model for predicting the process of closing the opening of a river mouth bar due to waves was developed by applying the BG model proposed by Serizawa et al. ^1.2, which was originally based on the study of Bagnold. The numerical model was used to predict the recovery of a river mouth bar of the Tenryu River, where an opening of the river mouth bar was formed owing to the flood that was caused by typhoon No. 4 in July 2007. The predicted changes were in good agreement with the measured ones.

Considering features of the Oujiang Estuary such as the irregular coastline, complex topography, many islands, and moveable boundary, a 3-D tidal current mathematical model with an irregular triangular grid is developed through the σ coordinate transformation technique, and treatment technique for the moveable boundary suitable for the 3-D tidal current model is presented. The model is verified with in situ data, the verification showing that the calculated tidal levels at 12 stations and current velocities and directions in different layers for 14 vertical lines are in good agreement with measured data both in magnitude and in phase. Based on the verification, the 3-D tidal current field is simulated after the deepwater approach channel project of Wenzhou Petrochemical Industry Base (WPIB), the changes of current velocities and current directions in surface layer, middle layer and bottom layer along the channel axis are analyzed, and the maximum crosscurrent of the approach channel is calculated.

Based on collected data of typhoons landfalling on Vietnam coastal areas during period of 1960 -2007 using storm surge simulation model to determine Maximum Envelop of Water (MEOW) for Vietnam coastal areas, the MEOW has been computed by selected families of typhoons. The maps distribution of MEOW used as sea level rise with rare frequencies is especially useful for design coastal engineering areas where there is a lack of sea level stations and the need to know sea level rises.

The mechanism of SLH (Sea Level Height) variation in the whole area of the Seto Inland Sea where there are many river mouths and two entrances facing to the ocean current is investigated from numerical analyses. The long term variations of the sea water exchange, wind, and density field are considered as the external factors of the water environmental change of the Seto Inland Sea. The density field is closely related to river discharge and the ocean current. From numerical simulation, the density effects SLH stronger than wind condition. The seasonal and inter-annual variation of ocean current and river discharge characterize SLH divided into the entrances and the inland sea.

The study investigates abnormal surges occurred with time lags to typhoon's peak at west coasts along the Sea of Japan. To examine the abnormal surge due to Typhoon Songda in 2004 the surge simulations are carried out using different input forces of winds and atmospheric pressures. The response of abnormal surges to the effects of terrain and meteorological fields is also examined. The results indicate that using output from meso-scale weather prediction model successfully reproduces the abnormal surges occurred with time lags of 15 hours.

This paper presents the numerical simulation of coastal inundation caused by typhoon in Noksan area. South Korea. The numerical simulation was carried out using a newly developed dynamically coupled tide-surge-wave model. The inundation area simulated from the developed model was in good agreement with the measured ones. However, the inundation water depths were smaller than the measured ones. We speculate this discrepancy caused by the wave run-up which was not included in the present numerical simulation.

The surface gravity waves generated by a horizontal circular ring of point mass source submerged in an initially quiescent fluid of infinite depth with an inertial surface are analytically investigated. The fluid is assumed to be inviseid, incompressible and homogenous. The inertial surface represents the effect of a thin uniform distribution of non-interacting floating matter, e.g., a broken ice-layer. The strength of the ring source is time-dependent. The linearized initial-boundary-value problem is formulated within the framework of potential flow for infinitesimal-amplitude waves. The perturbed flow is envisaged as the superposition of a singular flow and a regular flow. The former represents the effect of the singularity in an unbounded domain while the latter the influence of the boundary. The solutions in integral form for the velocity potential and the surface elevation are obtained by means of a joint Laplace-Fourier transform. The asymptotic representations of the wave motion for large time with a fixed distance-to-time ratio are derived with the method of stationary phase. The exact solution for the wave number is then given. The effect of the presence of un inertial surface on the wave motion is analyzed. It is found that the wavelengths of the transient dispersive waves increase and the wave amplitudes decrease in comparison with those of conventional free-surface waves. The explicit expressions for the free-surface gravity waves can readily be recovered by taking the inertial parameter to be zero in the present results.

A depth integrated two-horizontal dimension numerical model is developed to simulate the submarine landslide generated tsunamis. The nonlinearity effects and the frequency dispersion of impulse wave are both captured in a higher order. The model is developed using Finite Difference Method in a multi-step sixth-order spatial discretisation scheme. The presented two-horizontal dimension model is validated using available experimental data and a good agreement is obtained. The numerical results are also compared with three-dimensional potential flow models and multilayer models in underwater landslide generated waves and the agreement is excellent.

A spectral model is presented for blocking of long-crested random waves due to non-uniform collinear adverse current in the steady state situation. The spatial evolution of wave components that are blocked by the current is modeled with a spectral wave action balance in the region far from the blocking point, which is matched with a uniformly-valid solution in the region near the blocking point. Wave energy dissipation is taken into account both in the regions far from and near to the "blocking point, including wave energy dissipation due to wave breaking. The fitted model is able to reproduce the observed pattern of the significant wave height variation along the flume well.

The interactions between a solitary wave, which can be used to model a leading tsunamis wave, and a pile breakwater made of circular cylinders are investigated numerically. The propagation of an initial solitary wave into still water with constant depth is modeled by nonlinear depth-averaged shallow water equations, which are solved by the finite volume method based on the Bhatnagar–Gross–Krook (BGK) model. The transmission and reflection coefficients predicted by she numerical simulations agree well with those by the experiments when the ratio of wave height to water depth is small (<0.25), which yields a mean percentage deviation 5% for the transmission coefficient and 20% for the reflection coefficient. As this ratio exceeds the value of 0.25, the larger this ratio is, the bigger deviation of numerical results from experimental data is observed. This fact indicates the limitation of the depth-averaged shallow water equations to such type of problems and the reason for this is discussed.

This study proposes a multi physics model which consists of atmosphere, tide, surge and wave physics. It was applied to storm surge prediction in the Seto Inland Sea with complex topography and large tidal fluctuation. The storm surges generated by Typhoon Chaba and Songda were hindcasted well by the numerical model of SuWAT using the mesoscale weather model output under fluctuating tide condition since the pressure and wind field is well estimated by the weather model. The hindcasted water level variation by an empirical typhoon model under high water sea level is underestimated in comparison with the measurements.

Due to very complex coastlines and shallow depths along the west coast of Korea it should be applied that very fine boundary fitted meshes in modeling. Also it is necessary that fine meshes should be applied to generate nonlinear hydrodynamics with reasonable accuracy. In this study a parallel Linux cluster system is designed and applied for the evaluation of computational efficiency and reliability of the Yellow Sea tidal hydrodynamics. Computational efficiency reaches up to 7 times according to NPB bench-marking test when 8 nodes cluster are used. Model results by pADCIRC model on reproduction of the Yellow Sea resemble well with previous studies. Computed results show remarkable shallow tidal amplification along west coast of Korea. Tidal residuals with coastal currents and eddies are also well generated owing to fine grid system which can resolve complex coasts effectively

The turbulent air flow over water waves with varying wave slope, wave age and the Reynolds number is investigated using LES at both relatively low and high Reynolds numbers. The wave growth rates for the slow moving waves are found to depend strongly on wave slope while the decay rates for the fast moving waves are almost independent of wave slope. The critical value of wave age that marks this transition increases at the high Reynolds number.

The steady-state spectral wave model STWAVE is employed to study the wave climate along the coast of Jiangsu. Three typical cases, i.e., waves resulted by incidence of spectral waves from offshore, waves induced by uniform wind which represents the effect of the typhoon landed at some place along the coast of Zhejiang, and waves induced by uniform wind which is nearly parallel to the coastline and represents a cold snap passing through the coastal area of Jiangsu from north to south. The numerical results are shown to be in good agreement with the real situations. Phenomena including growing of waves, wave decay due to the sandbars, accumulation of wave energy in between of Shandong Peninsular and the sandbars, etc. are all well reproduced.

A 3D Corrected MPS (CMPS [1]) method has been proposed for refined simulation of a plunging breaker and resultant splash-up. The enhanced performance of the 3D-CMPS method with respect to the 3D-MPS method [2] has been shown by simulating a plunging breaker on a plane slope. Furthermore, the parallelization of 3D-CMPS method with two different solvers of simultaneous linear equations has been performed to enhance the computational efficiency of the calculations.

Internal waves in a two-layer system are simulated using a set of nonlinear internal-wave equations, which was derived on the basis of a variational principle without any assumptions concerning wave nonlinearity and dispersion. In the cases where long internal waves reflect in a tank, interface displacements obtained by the proposed model with more than two vertically distributed functions of velocity potential are in harmony with those by the Boussinesq-type model, as well as the existing experimental data especially in the wave number. In the intermediate-wave case, the present model shows different results from those through the Boussinesq-type model, which should not be applied to this case without enough consideration of the wave dispersion. Internal waves propagating over a submerged breakwater are also simulated, where the vertical distribution of horizontal velocity below a crest is remarkably distributed when it starts disintegration after passing over the shoulder.

We developed new types of Boussinesq models which extend the equations of Nwogu (1993) by considering the squared bottom slope effect. Numerical experiments were conducted for wave reflections from the Booij's (1983) planar slope with different wave frequencies. Nwogu's (1993) model results were accurate up to 1:1 (V:H) slope but significantly inaccurate for steep slopes. The present models results were more accurate than Nwogu's model. Numerical experiments were also conducted for wave reflection from a Gaussian shaped trench. The resonant reflection was well predicted by all the Boussinesq models. For the case of steep slopes, Nwogu's model significantly underestimated reflection coefficients while the present models accurately predicted reflection coefficients.

In this study we developed the extended mild-slope equation in terms of the stream function using the Green's second identily and compared to Kim and Bai's (2004) equation which was developed by the Hamilton's principle. For waves over a planar slope, a parabolic mound and an undulating bottom, we compared reflection coefficients by the developed equation. Kim and Bai's equation, mild-slope equation in terms of the stream function against an exact solution or experimental data. The present equation gave most accurate solutions, whereas the mild-slope equation failed to predict the reflection coefficients in whole range of water depth. Kim and Bai's equation overestimated the reflection coefficients for very sleep slopes.

Dongjiakoo Harbor is a multi-functional harbor of heavy passing capacity under planning in China. This article is based on the measurement of waves, currents and sediment suspension as well as COD characteristics on site. Numerical method is used to predict the dispersion and deposition rules in this area. A combined wave-current-sediment model of COHERENS- SED is created through the combination of bydrodynamic model COHERENS and wave model SWAN as well as a sedimentation model SED developed by the authors. The simulated results are agree with observed data very well. The study shows the currents in the waterways and harbor basin water areas are relatively weak due to the narrow water width at the port mouth and the current directions parallel to the wharf directions.

During the dumping of dredged soil, most dredged soil will deposit around the dumping area, the rest will form the high-concentration suspended sediment in the point where the dredge soil is dumped, then being dispersed and transported with the wave, tidal current and wind-driven current. According to the planning, the higher-ton dock will be built in RR port in the future. The large-scale ships from the open ocean to this port area all sail through XX waterway. But the smallest natural depth of waterway outside its month is 18.2m, which means the construction of the deep waterway drops behind the development of port obviously, leading to the restricting capability of large-scale ships. In order to meet with the need of the construction of this port, it is necessary for the waterway outside its mouth to be dredged and regulated. How to deal with the dredged soil is involved in the dredging and regulation of waterway. Solved with finite element method, the dumping areas are set in open sea. There are three dumping areas named 1#, 2#, and 3#. The 2-D tidal current and dispersion & transportation of suspended sediment modeling are developed in this paper,. The dispersion & transportation of dredged soil is simulated after being dumped due to the regulating engineering in the waterway outside its mouth, so that the effect that the increased suspended sediment has on ocean environment near the engineering area is analyzed in this paper.

Implementation of a direct numerical simulation is restricted by Reynolds number. For a direct numerical simulation of a particulate flow, a computational grid scale, which is finer than a representative particle scale, is required. However, a computational grid scale, which can be used in a direct numerical simulation, is restricted due to the limitation of a performance of hardware. Therefore, implementation of a direct numerical simulation for a particulate flow is limited in a low Reynolds number. To overcome of this limitation, an introduction of a turbulence model might be one of the reasonable solution. In the present study, DNS-base solid-liquid two-phase turbulence flow model has been developed by combining DNS-base solid-liquid two-phase flow model with, the LES.

Pollutant and sewage discharge in coastal area is most unmonitored. Its make a slow preventive action by government to protect an ecosystem of coastal area from the environmental damage. The development of mini-submarine vehicle is selected to do the monitoring of pollution and sewage discharge in the coastal area continuously. The robotic technology might be adopted to make the vehicle is most suitable to do the monitoring mission. So that, the vehicle is equipped with the wireless instrument and it can be controlled by an operator on sea surface. The camera is also installed on the vehicle in order to capture the underwater environment and send it to the operator. In this paper, the procedure of a designing mini-submarine for the monitoring of underwater pollutant and sewage discharge in the coastal area is described. Due to the particular mission, the vehicle has to have a good stability and hydrodynamic performances, and also it able to load the entire equipment requirements.

Nowadays, ADCP is commonly applied in the measurement of river flow discharge and flow field. The Doppler shift between the emitting and receiving signals of acoustic is the major methodology of the application in measurement. Since the suspended particles in river are the main objects that cause the acoustic backscattering, the ADCP Acoustic Backscatter (ABS) can be converted to Suspended Sediment Concentration (SSC) using the sonar equation, and the synchronous profile of flow velocity and sediment concentration can be obtained. After the 10 m deep Navigable Channel in the Yangtze Estuary was opened in March 2005. the actually annual amount of maintenance has being risen every year. In the early study phase, it was found that the original operation of dredging and dumping sediment is not effective. In order to understand the effects of the application of the optimized operation method, the synchronous measurements of sediment spread region were carried out while dumping the dredged sediment in the No. 10 Dump Area in the North Passage of the Yangtze Estuary during the tidal fluctuation by 6 ADCP hydrologic survey boats in September 2008. It is concluded that the spread impact of dump sediment is related to the flow velocity; when the velocity is about 1.35 m/s. the sediment spread region presents a narrow strip with greater than 1 km long, but only following the flow, with minor deposit impact on the navigation channel.

The Da Rang river mouth is one of the biggest rivers in the Southern Central Area of Vietnam and it has a typical lagoon type. It usually opens for 3-4 months during the rainy season and closes for 6-7 months during the dry season. In recent years, the topographic change of Da Rang river mouth increases its rate with time. This phenomenon is governed by a micro-tidal regime and a wave dominant coastal dynamics. Strong seasonal variation of the river discharge and the incident wave climate are important factors. The closure of the river mouth during the dry season causes a lot of problems to the socio-economic developments in the area including navigation and flood water discharging. This paper presents an analysis of the morpho-dynamics and the mechanism of seasonally and yearly topographic change of the Da Rang river mouth, which was affected by exogenous causes such as river floods, ocean waves and currents. The calculation results of longshore sediment transport and morphological changes by application of Delft3D models (WL | Delft Hydraulics. 2006) is discussed. Subsequently, this paper points out a trend of sediment movement in the Da Rang river mouth based on the analysis of the Da Rang river mouth using available historical maps, aerial photographs and satellite images. The results show that the Da Rang river mouth has a trend of accretion in long term.

A comprehensive experimental program was carried out to evaluate the variation in pressures on a vertical wall in the presence of single or double wave screens on its seaward side. The variation in pressures due to the obliqueness of the incident waves is studied. Tests were carried out with one screen as well as two screens for four different wave directions of 0°, 15°, 30° and 40°. It is observed that the pressure induced on the wall decreases with an increase in relative water depth. It is also observed that, with an increase in obliquity of the wave incidence the pressure induced on the wall gets reduced.

This study examines theoretically the obliquely incident wave action on a Jarlan-type perforated breakwater with a submerged rock fill. An analytical solution is developed using the matched eigenfunction expansion method to investigate the hydrodynamic performance of the breakwater. The effects of several main factors on the reflection coefficient and the wave force of the structure are analyzed. It is found that the dimensionless wave force acting on the perforated wall decreases with the increasing incident wave angle. But with the increasing incident wave angle, the reflection coefficient of the present breakwater first decreases, reaches its minimum, and then increases monotonously.

The experimental investigation on dynamic pressure and run-up over a vertical faced seawall and a curved face seawall given in Coastal Engineering Manual suggested by US ARMY CORPS were placed over a bed slope of 1 in 30 and subjected to the action of Cnoidal waves. The results of both the models were compared and discussed.

Using typical section structure, the tests of the core material's influence in rubble mound breakwater on wave transmission are done. The relations among the permeable wave height, incident wave element and breakwater width are discussed. The calculation formula is gained. The test results show that the different core materials have obvious influence on wave transmission.

Irregular wave forces acting on the perforated breakwaters are simulated through numerical wave flume. VOF method and k-ε equations are utilized to solve the Reynolds-averaged Navier-Stokes equation (RANS) and continuity equation. In order to simulate successive long-time making wave of irregular waves and absorb the reflected waves from the perforated breakwaters, the internal source generation of wave is applied. The numerical model is well verified by the experimental data. A simplified expression for computing the total horizontal forces is obtained from the linear regression with the main related parameters. In the same way, the total vertical wave forces and the phase difference between the peak of total horizontal forces and the peak of vertical forces are investigated respectively. The expressions of these simplified relations are simple and useful for actual engineering design.

This study presents the results of experimental investigation on the submerged breakwaters made of two different armor blocks of Tetrapod and TP(Triangular Pyramid)-Block. The focus of the study is to compare the wave transmission characteristics of the submerged breakwaters according to the use of different types of armor blocks. For this purpose, the parameter of K_Th_b/h was introduced in the analysis of the measurement data. By using the linear regression line deduced from the analyzed data, it was possible to readily estimate the wave transmission coefficient irrespective of different water depths at the crest of the submerged breakwater.

Wave records at Hualien Harbor during the severest resonance period (12 hrs) caused by Typhoon Tim in 1994 were reanalyzed. The ratios of resonant wave heights among three available wave stations for each of the following three infragravity wave periods: 100, 160 and 220 s were identified as a unique characteristic. A linear, finite difference wave transformation model (RIDE) was used to simulate the observed resonant characteristics. The simulation, however, was successful only if a large (17 km x 45 km) grid is selected. The distribution of wave phase suggested that there are two wave sources for causing the observed resonances: (1) from offshore directly, and (2) from short-crest waves that are traveling along the south shoreline. The along-shore short crest waves were caused by oblique incident waves and strong wave reflection on the beach. The second source of incoming waves is available only if a large computation domain is selected.

In this paper, a 2D numerical model for the tidal bore with actual bottom topography from Fuyang to Ganpu on the Qiantang River was developed using KFVS (Kinetic Flux Vector Splitting) scheme based on Boltzmann equation. On the basis of verification using field data of recent years. the model studied the effect of single bridge and two bridges on the height, propagation speed, fluid velocity of the tidal bore, along with bridge block-water ratio about 4.3%. Furthermore, the combinational effects of two bridges with spacing distance of 2km and 5km was analyzed. The computed results show that the bridge has little influence on the downstream tidal bore, the nearer from the bridge site, the greater effect on the upstream tidal bore. Near the upstream region of the bridge, the bore height decreases by 10cm. The maximum change of the fluid velocity of the bore decreases up to 10%, and the velocity between the piers increases about 0%~5%. The effect of the bridge on propagation speed of the tidal bore is a little. Furthermore, two bridges have combinational influence on the tidal bore upstream region of the bridge site more than single bridge. When the spacing distance of two bridges is greater than or equal to 5km, the lower bridge has no additional combinational influence on the tidal bore. The results can give guidance on the optimum bridge layout.

For breakwater construction, the armour unit stability of breakwater is one of most important factors to be considered by engineering designer. In general, the armour unit stability under normal incident waves is paid more attention than that under oblique incident waves by designers according to regular engineering criterion. In this paper, a series of physical model test were carried out to examine the accropode unit stability of breakwater under normal and oblique incident wave actions. According to the experimental results, it can be found that the accropode units on breakwater become more unstable under oblique incident waves than that in normal incident waves in the same wave conditions. It is suggested that when the breakwater lenght is long enough, the accropode unit stability under oblique waves attack should be paid more attention than the normal incident case. The results of this study may give a good reference for breakwater design of the accropode unit stability in waves.

The following section are included:

• AUTHOR INDEX

The following sections are included:

• PREFACE

• CONTENTS

A tide pool and tidal flat are formed around revetment (coastal structure) in the Ota River in Hiroshima Prefecture, Japan. Formation of various tidal flat environments are predicted when a coastal structure is constructed in a main channel. In order to clarify the variation mechanism of groundwater quality and role of coastal structure for a tidal flat, variation of groundwater with tidal cycle and effects of the existence or non-existence of a tide pool were investigated in the Ota River. It was clarified that keeping high groundwater table, low salinity at the tidal flat surface and recovery to the water conversion of groundwater during flood period were caused by groundwater discharge from the tide pool.

The armor weight is proportional to the cube square of wave height and almost proportional to the cube root of number of incident waves or the impact duration when the wave height is constant over the whole impact duration. But we expect that the longer the impact duration, the smaller the wave height. Data measured at several stations in Korea are analyzed to find the reduction factor of significant wave height with respect to impact duration. The significant wave height is found almost proportional to the power -0.04 ~ -0.01 of impact duration. Therefore the increment rate due to longer duration is found slightly reduced by the power from 0.3 to 0.18 or 0.27.

This study is investigated a cause induced downtime through the field measurement and the downtime monitoring system in Pohang new harbor. The downtime events arose eleven times during November 11, 2008 to February 4, 2009. The causes induced downtime understood as swell at seven times, wave with strong wind at two times, swell with strong wind at one time and waves at one time. We can understand that swell affected in major cause induced downtime of 1,500 GT~23,000 GT size ships in Pohang new harbor.

In the study, characteristics of changes of wave profile and energy spectrum at different depth of submergence and different crest width of submerged breakwater under regular wave passing over a submerged breakwater installed on the 1/20 sloping bed are investigated by two-layer, depth-integrated Boussinesq model. The proposed numerical model is examined by comparison with the experimental results. The numerical result shows that wave profile may become more asymmetry when wave propagates over breakwater. Wave energy may rapidly decrease at the breakwater because turbulent dissipation increases and the energy in lower harmonics are transferred into higher harmonics. The conclusions show the lower the depth of submergence or the wider the crest width of submerged breakwater is, the more remarkable asymmetry wave profile is and the more sharp the decrease of relatively fundamental energy is.

Laboratory investigations have been performed on impulse wave's effects near the coastlines such as shoaling effects and run-up. Wave run-up over on smooth impermeable slope are studied in over than 100 experimental tests. The influences of the bed slope angle, incident impulse wave height and still water depth are investigated. The available empirical equations for impulsive wave run-up have been examined by comparison with the collected experimental data. A new equation has been presented for run-up estimation based on the laboratory measurements. It has been compared with others empirical equations and the differences have been discussed. The shoaling effects on the impulse wave feature have also been considered and a laboratory-based empirical equation has been presented to approximate the shoaling effects on the incident leading wave amplitude.

Vietnam is located in south-eastern of Asia, closed to East Sea and very near the Equator so this country is always influenced by typhoons. Moreover Vietnam has very long coast which runs through 29 provinces and cities and the seadike system is very complicated. In 2005 the big typhoon had occurred in this country and many sections of seadike had been failed, caused much difficulty for people who live behind the seadike. After this occasion the design of seadike has been changed to fit the new situation. In this paper we will present new approaches in design of dike. The cress level of dike should be high enough to prevent the failures, if not the riprap on both side of seadike must be strong to be stable during typhoon.

Significant overtopping over the vertical seawalls of the reclaimed campus of National Taiwan Ocean University (NTOU) had resulted in flooding on campus by the super Typhoon Herb in 1996. In this paper, the wave overtopping discharges are investigated with existing empirical formulae. The temporal evolutions of wave conditions and water levels during typhoon period at three selected sites on the seawall are based on Tsai et al. Two structure types are assumed for the NTOU seawall to account for practical structure conditions before Typhoon Herb. The calculations show that some of the results are greater than the criteria for damages on backfilling soils during typhoon passage with a largest peak value of 0.046 m³/s/m. Goda's formulae can not give predictions throughout the typhoon period due to insufficient data from the design diagram. Formulae by Franco et al. in 1999 can give more reasonable predictions than theirs in 1994. Predictions by Allsop et al. have always given largest values at the selected sites while the revised formulae by Besley et al. accounting for effects of shallow water for composite seawall have resulted in smaller discharge rates.

In the present study, a new type of slit caisson quay wall has been proposed to reduce the wave reflection and the stem wave simultaneously. The specialized configuration of the slit caisson quay wall was devised as a series of detached slit caissons which are connected by the open chamber. In order to verify the wave dissipation induced by the combined effect of the perforated wall and the open chamber, the physical model tests including the two-dimensional and the three-dimensional cases were conducted. As a result of the several tests, it was found that the proposed type of slit caisson quay wall has a sufficient dissipation effect against the oblique wave incidence.

This paper presents the details of the application of geo-tubes as coastal protection measure to serve as a seawall along the coast of Shankarpur, West Bengal, India (lat 21°38’12” and long 87°34’54”). The details of requirement of suitable toe system are discussed. The behaviour of the geo-tubes as a coastal protection measure and the field observations of the coast after their installation are also discussed.

The results of preliminary experimental investigation are presented for the hydraulic characteristics of the pile-deck light beacon, which is recently developed in order to diminish scouring of the light beacon structures due to actions of waves and currents. Both regular and irregular wave trains of different wave heights and periods were used to examine hydraulic characteristics of the structure under wave action. In particular, the load acting on the pile legs and the deck were quantitatively estimated and discussed in some detail.

15 computational formulae of wave transmission coefficient of submerged breakwaters obtained through physical model tests since 1981 are compared and analyzed in this paper. The dimensionless parameters adopted in the comparison are mainly relative submerged depth R_c/h, relative wave height R_c/H_i, relative dimensions of core stones B / D₅₀, relative breakwater width and wave breaker index ξ. It indicates that there are huge differences in research findings, which are mainly caused by different experimental conditions and analytical methods. In order to reduce the differences, it is necessary to conduct influence studies of such factors as dimensions of core stones and surface roughness of breakwaters.

This paper addresses a laboratory study on the effect of vertical crown-wall on the reduction of wave overtopping at seadikes. A set of formulations for the crown-wall reduction coefficient has been derived based on the analysis of the data from 168 experiments on wave overtopping at dikes with and without crown-wall. The new approach is straightforward and can readily be incorporated into the existing overtopping formulae of TAW [1] for more reliable prediction of the mean discharge on seadikes with crown-wall.

Performance of the vertical-wall-type resonator with rectangular resonant basins constructed on the sloped sea bed was examined extensively. As a comparison, the resonator with the same plan configuration, but constructed on the constant depth seabed, was also examined. In order to know the resonant action of a resonator for reducing incoming waves to a harbor, a jetty-type structure was also used as a possible breakwater.

We investigate in details the transport of particles using our DNS database of turbulent channel flow at low Reynolds number (Re_τ = 80), the effects of ejection and sweep events on the transport of fluid particles are analyzed separately. By analyzing trajectories of particles released from sweep and ejection events, it is found that remarkable differences appear for the mean displacement and the dispersion of particles during short and intermediate diffusion times, but for wall-normal direction the differences become negligible for sufficiently long diffusion times larger than Lagrangian integral time. It should be pointed out here that other than the wall-normal direction the initial effects remain for considerably long time.

In the present paper, a numerical model is established to simulate 'flip-though'. In our model, flows are governed by Navier-Stokes equations, air is treated as the compressible fluid, while water is treated as incompressible. A numerical investigation of flip through in depressurized conditions has been dedicated to highlight the role of the air-entrapment during the impact of a breaking wave against a vertical wall. Furthermore, a preliminary comparison between the numerical results and experimental results (Ref. 7) is done.

A three dimensional code is developed for single phase flows. Using SPH method, the Navier-Stokes equations are discretised with fluid particles in Lagrangine sense. Boundary conditions, including both no slip wall, moving wall and symmetry wall, are implemented using ghost particles. Anti-symmetrical or symmetrical velocities are assigned to the ghost particles in the support range of a real fluid particle. For single phase flow, the properties of a fluid particle near the free surface need special treatment because the kernel function is a uniform decay function in each direction. With numerical experiments, 85%~95% of the constant density is a good criterion to identify the particles near the free surface. After identify these particles, the kernel function is renormalized to satisfy the integration rule of SPH method. To check the treatments of boundary conditions, three dimensional cavity flow and dam-breaking tests are carried out. Fairly good agreements between the numerical results and target results are obtained, implying the effectiveness of the usage of ghost particles. With three dimensional simulations, details on water impact on rigid wall are investigated.

Recently, the interest in falling film evaporation method has increased as an efficient method for seawater desalination. In this method, the flow characteristics of the falling film are very important issue to make the system highly efficient. Therefore, this study is undertaken to investigate numerically the falling film thickness. Numerical simulation is performed using FLUENT3.6.26, a commercial CFD code. The flow conditions and falling film thickness are reported for the velocity inlet range from 0.4 m/s to 0.7 m/s in which the Reynolds number vary from 400 to 700. The effect of mass-flow rate on the film flow characteristics is investigated.

The objective of the present study is to develop a new three-dimensional numerical model of solid-gas-liquid phase flow "DOLPHIN-3D" by introducing a bi-viscosity model considering the constitutive law of Bingham fluid. The validity of the model is examined by applying it to the collapse problems of a Bingham fluid column with and without multiple rigid bodies. As a result, it is found that the model is able to simulate the dynamic behavior of Bingham fluid as well as solid-gas-liquid interaction with appropriate accuracy.

Towards the numerical set-up for benchmarking and optimization of fluid-structure interaction among multiple cylinders, this paper presents a numerical study of vortex structures in the wake of side-by-side circular cylinders. SAS SST turbulence model is used to find the 2D vortex shedding pattern in the wake of a single cylinder. The turbulence-resolving capability of the turbulence model has been validated by comparing with experimental investigations using PIV. Vortex patterns after two side-by-side cylinders with different transverse spacing are further investigated based on the single cylinder results. These results together with some discussion on relative merits of various modeling parameters are presented.

On the basis of Fluent software, Renormalization Group (RNG) k - ε model, Volume of Fluid (VOF) method and dynamic meshes are employed to simulate wave and current motions on circular duct. The computational results including surface height, velocities, pressure and force are obtained and analyzed. Computational drag force (CDF) coefficient, computational lift force (CLF) coefficient and computational composite force (CCF) coefficient on the circular duct vary periodically in coincidence with the wave period. It is the wave that causes the periodic changes of CDF, CLF and CCF. The absolute value of CLF is greater than CDF. CLF is the main factor that determines CCF when the circular duct is close to the wall.

A novel Adaptive Mesh Immersed Object Method (AMIOM) is developed for simulating unsteady incompressible viscous flows around stationary or moving bodies. This method combines the main advantages of the existing methods IMM [1] and IOM [2]. The new method makes the solutions near the solid object more accurate than the IOM, while it is more efficient than IMM. In this study, the AMIOM is implemented in an unstructured finite volume incompressible Navier-Stokes solver. Numerical test cases involving stationery and moving objects are investigated for validation purposes. Good agreement with published numerical solutions and experimental measurements has been obtained for the test cases.

Artificial reef refers to a submerged rubble structure with a wide crown, placed near the shore zone and its purpose is to initially dissipate the energy of the incident waves, which consequently decreases the run-up height and volume of overflow of these incident waves. By using the Hudson formula, the weight of the rubbles according to the design wave is calculated. Furthermore, by employing a hydraulic model test, the investigation of stability is also conducted. The weight of the rubbles is calculated by using the Hudson formula and investigation of stability is conducted by employing the hydraulic model test, all of which are based on the design wave. This research aimed to investigate the deformation of artificial reef using a hydraulic model test. Moreover, characteristics of structure deformation and deformation mechanisms in regards to conditions of model tests such as wave height, wave period, slope, and crest depth were analyzed and as a result, damage parameter which describes deformation characteristics of the artificial reef was proposed.

Under the action of typhoon, the freak wave in archipelagos has influence on structure and ship. Based on former study, the freak wave is not an extra low probability event. The purpose of this article is to analysis the probability of occurrence of freak wave in archipelagos and the relation of wave height cumulative frequency.

Non-linear interactions between the waves and a submerged horizontal thin plate are studied experimentally in this paper. A fifth order data fitting method is used to analyze the data recorded by wave gauges. The first order reflection and transmission coefficients and the second order transmission coefficient of both free and locked waves are presented for both breaking and non-breaking waves. For the first order reflection and transmission coefficients, our results agree with those of previous studies; the smaller transmission coefficients of the first harmonic waves, which are found for the cases of small submergences, are due mainly to the energy dissipation associated with the wave breaking in water above the plate. For the second order transmission coefficients of free waves, it is found that they increase with increasing/decreasing wave height/submergence.

In the case that an offshore structure is placed in wave breaking zone, the estimation of wave forces purely based on apparent wave heights may cause an under-design of the structure. Thus, for the stable design of the structure, the breaking wave induced current should be importantly considered in the comprehensive estimation of design loads. In the present study, a Boussinesq equation model to calculate the wave height distribution and breaking wave induced current is set up and applied to the scheme of the hydraulic model test previously undertaken. Based on the results of the Boussinesq model, fluid forces acting on the model structure are calculated and compared with the experimental results. The importance of the breaking wave induced current is then quantitatively assessed by comparing fluid forces with or without the current.

Fluid resonance in the narrow joint gaps of a caisson-type breakwater is investigated experimentally and theoretically. Particular focus is placed on the effect of the incident wave angle on the condition for the occurrence of fluid resonance and the amplification of wave height in the gaps at resonance. A three-dimensional wave basin with a snake-type wave generator is used in the experiments, and the theoretical analysis is carried out using the method of matched asymptotic expansions. It is found that the incident wave period and amplification of the wave height in the gaps as fluid resonance occurred are independent of the incident wave angle.

For the purpose of analyzing economical and structural feasibility and obtaining core technologies in design, fabrication, ballasting, integration and maintenance of a floating mobile quay, one-sixth scale model with 50m x 30m x 5m dimension of pontoon-type concrete floating mobile quay was constructed. After turning out four individual modules (with 25m x 15m x 5m) on a floating dock, they were launched, ballasted, and then integrated by post-tensioning. Two times of ambient vibration tests were carried out for an individual module of floating mobile quay and for an integrated floating quay (with 30m x 50m x 5m) and the resonant frequencies and corresponding mode shapes and damping ratios were estimated. It was found that the global behavior of a structure was dominated by rolling and pitching motions and there was almost no heaving motion. Consequently the rolling and pitching modes can be estimated reasonably while the heaving mode could not be obtained by ambient vibration tests.

This paper presents a nonlinear algorithm applicable for estimating the response spectrums of offshore structures. The key idea of this algorithm is to approximate the nonlinear forces with high-order velocity polynomials. Span response spectrums are derived with related theories in random process and statistics. A case study of the data provided by CNOOC is carried out with the two approaches, to compare with the traditional linearized approach.

Very large floating rectangular caissons can be used in the construction of breakwaters, piers, or harbor terminals. It may need more than one day to tow these large floating caissons to construction sites. The responses of the floating caissons to ocean waves, wind and tidal currents are one of the concerns in practice. In this paper, we report our on-going work on physical and numerical modeling of a deep draft floating caissons in wave environments. The numerical results obtained by WAMIT and CFD (Star-CCM+) are compared with the experimental results.

Wave uplift force acting on the bottom of superstructure of a pillar wharf is an important factor for design. In this paper, a study on the wave uplift force is conducted by a series of physical model tests. Based on the results, two experiential formulas for calculating the maximum wave displacement around the pillars and the wave uplift force on superstructure of a pillar wharf are presented respectively, which are suitable for an open sea area in the range of wave steepness 0.015~0.071, relative wave height 0.13~0.50, relative water depth 0.10~0.54 and relative pillar diameter less than 0.29.

In the construction of artificial reef in deep water, constitutive materials are usually dumped from a barge into the sea directly. However, dumped materials are not accumulated effectively on the seabed in a conventional method because their movement with current and significant diffusion during their fall. In this study, numerical models are proposed to predict the movement and diffusion of the dumped materials. Moreover, construction methods to constrain the diffusion of dumped materials have been developed for the materials of concrete blocks and rubbles. By use of the proposed optimal construction methods, artificial reefs have been successfully constructed in both cases of concrete blocks and rubbles.

The restoration and rehabilitation of mangroves is now an endeavour which is wholeheartedly supported to provide coastal protection from natural flooding disasters events. In the presence of extreme flooding events, such as tidal currents, storm surges and tsunamis, then the restoration and rehabilitation of natural mangrove swamps becomes more complex at exposed sites, where no shelter is provided by other mangroves. Thus, there is a need to duplicate the real natural environment of such shelters. An innovative and environmentally friendly system, referred to herein as the Artificial Mangrove Shelter (AMS), has been introduced in this paper. The hydrodynamic effects of AMS have been studied and modelled. Included in this study is a refined two-dimensional depth-integrated numerical model that considers both the effects of the drag force and blockage effects induced by the AMS. The model study focuses on investigating the influence of an AMS on the tidal flow structure and the consequential impacts of these changes on tsunami currents. Simulations have been undertaken for various conditions, i.e. with different densities and diameters, as well as without an AMS. Comparisons of velocity profiles and water elevations for these cases have also been undertaken. The results suggest that an AMS can have a significant impact on the hydrodynamic processes and, in turn, have a key impact on the response of a natural ecosystem of mangrove swamps from threats of flooding. The study shows that the model developed can be used as a useful hydro-informatics tool to establish planning and management procedures for the long term sustainable use of mangroves as natural resources.

With the continued degradation of coral reefs, terrestrial loadings, both through surface and subsurface pathways, need to be comprehensively assessed. Continuous watershed monitoring through data-logging sensors, in-situ nutrient analyzers and water sampling were carried out in Todoroki River to quantify sediment and nutrient discharges. Total phosphorus (TP) and suspended solids concentration (TSS) in the Todoroki River (discharging into Shiraho Reef) increased with increasing rainfall intensity and river discharge. NO₃^--N concentration decreased drastically during flood events but gradually increased afterwards when base flow starts to dominate. Watershed simulations showed that the volume of discharged sediments increased with increasing areas devoted to sugarcane and decreasing tree cover. In the nearshore portion of the reef. ²²²Rn-estimated groundwater flux during low tide was around 3-5 cm/hour. Nitrate concentrations generally increased in accordance with higher groundwater flux. Analysis of multi-date satellite images revealed that, in the long term, the reef has undergone degradation (e.g., decreased live coral cover), largely due to extensive agricultural land development and intensive farming. Nutrification of reef waters (e.g., due to typhoon-enhanced terrestrial discharges) increases chl-a concentrations and potentially shifts phytoplankton abundance from diatoms and green microalgae to bluegreen microalgae (cyanobacteria). In the nearshore reef, nutrient-rich SGD had a similar effect on phytoplankton. In conclusion, enhanced terrestrial loadings due to agricultural intensification have resulted in the degradation of Shiraho reef with localized eutrophication occurring in areas subjected to relatively higher nutrient discharge.

Laboratory experiments were conducted to study the wave induced set-up over fringing coral reef models under a series of regular wave conditions in a wave flume. Two reef models were examined in this study: one with a smooth reef flat and another with a porous reef flat. Water surface elevations at different locations were measured to obtain the wave set-up. Preliminary analysis shows that the presence of the porous reef flat can alter significantly the wave transformation process on the reef flat, especially the wave breaking and wave damping. Furthermore, the maximum wave-induced set-up over the smooth reef flat is generally larger than that with porous reef flat. However, experiments also showed that the variations of wave-induced set-ups under both cases observe a similar trend with regard to the incident wave conditions.

An equivalent resistance coefficient including the effect of drag caused by structures as well as a bottom friction was investigated for flooded built-up areas. As applying the coefficient into the bottom friction term in the shallow water equation model, relatively larger grids can be used for the drag effect of structures in inundation simulations, In order to investigate the equivalent resistance coefficient, the existing hydraulic experiment using unsubmerged square piers was simulated by using the RANS equation model of FLOW-3D, a 3-dimensional computational fluid dynamics code. The coefficient (n-value) was evaluated by applying the computed data into the Manning's equation. The computations were compared with the experimental results and the semi-analytical formula derived from momentum analysis including drag interaction effects. The computations agreed well with the experimental results and the semi-analytical formula. From the agreement it was confirmed that the drag interaction coefficient evaluated by the measurements was strongly dependent on the interval of piers. From the computations for the case, in which the water depths were much larger than those of the measurements, it was found that when the unsubmerged piers were arranged in a fully developed open channel, the equivalent resistance coefficient increased with 2/3 power of water depth.

Beach erosion of south Kujukuri Beach triggered by compound anthropogenic factors was investigated based on the aerial photographs and field observation. Sand supply by northward longshore sand transport has been decreasing on this coast, causing erosion of the south part of the coast close to the sand source (sea cliff). In contrast, on the north end of the coastline, a long breakwater of the Katakai fishing port was extended and a large amount of sand has been deposited in the wave shelter zone. The ground subsidence up to 60 cm occurred along the coastline due to the pumping-up of the underground water to obtain the water-soluble gas. The south Kujukuri Beach has been devastated year by year due to all these impacts. To save the coast, full scale sand nourishment is required.

Beach changes along the cliffy coasts triggered by the formation of the wave shelter zone associated with the construction of port breakwaters and detached breakwaters were investigated on the basis of the aerial photographs and field observation, taking the coasts in Hitachi City in Ibaraki Prefecture as the example. The shoreline changes between 1984 and 2006 were studied. Sea cliff extends along these coasts, and narrow sandy beaches have been formed mainly by the sand supply from small rivers. After the construction of port breakwaters, longshore sand transport from outside to inside the wave shelter zone was induced, causing erosion outside the wave shelter zone and accretion inside it. In the eroded zone, sea cliff is exposed to waves and abrasion by gravel is underway. To protect these beaches, gravel nourishment is effective for the shore protection, along with the recycle use of fine sand deposited in the port.

A model for predicting long-term shoreline changes along a river delta coast is developed, applying the contour-line-change model to the Enshu-nada coast as an example. We first investigated the shoreline changes between the Magome River mouth and Imakiri-guchi jetty, where beach changes triggered by the decrease in fluvial sand supply from the Tenryu River have been occurring. It was observed that the shoreline retreated downcoast of the Magome River mouth, and the shoreline advanced in parallel further downcoast, while maintaining the curvature in the shoreline configuration. These accretive features of the shoreline along a river delta coast are predicted using a numerical model

Fukiage Beach has been in the equilibrium over the past 40 years. There is a sorting mechanism for the beach, resulting in the sand particle size decreasing from west to east. Therefore, the colonization of coastal plants differs from place to place. Winds in the study area have dominant north-northeast and west-northwest components. The west-northwest component contributes to the longshore sorting of sediment on the backshore. From the view point of wind energy, south-southeast winds in summer and west-northwest winds in winter contribute to sediment transport

A simple numerical model to predict three-dimensional (3D) beach evolution after sand nourishment was proposed. The injection of sand to near shoreline or offshore area was expressed by the depth-averaged advection diffusion equation for suspended concentration. The 3D beach evolution was computed using the hybrid model presented by Kuroiwa et al.[1]. Beach evolutions around two groins after nourishment of sand to near shoreline and offshore area were simulated. The computed results after nourishments were compared with the beach evolution without nourishment and the validity of the presented model was investigated.

The applicability of a three dimensional coastal area model based on a Hybrid model for medium-term beach evolution was investigated. The three dimensional model was first tested against groins for three cases in order to investigate the influence of the time history of the incident waves, and the time stepping techniques to feedback on the predicted final bathymetry. Then, the model was applied to Kunnui fishing port for 1, 3, and 4 years, to calibrate and verify the model. For the model tests, the performane of the model was investagated; and for Kunnui fishing port, the model results show good agreement with the field observations.

A numerical analysis is performed to predict the actual change of beach profile due to cross-shore sediment transport during severe storms. In the existing cross-shore beach erosion studies, calculation of cross-shore sediment transport includes only continuous process of beach erosion, not considering the stability of beach slope which predicts the time of beach breakdown during erosion. In this study, the stability of beach slope using the critical equilibrium analysis is analyzed on every changing beach profile in every given time to predict the actual change of cross-shore beach profile. The process of cross-shore beach erosion and beach profile change at Sumiyoshi beach in Miyazaki, Japan during storm on July, 2007 are simulated and the final beach profile is compared with the measured one. The calculated final beach profile after storm considering the stability of beach slope shows relatively good agreement with the measured final beach profile.

The beach nourishment technique is accepted as one of the effective protection works of the beach erosion.In order to successfully conduct it the beach evolution model is needed to evaluate the environmental changes in the future. In this study, the N-line model for predicting contour line and shoreline changes considering the effect of the mixed grain sand and the beach nourishment was proposed. Firstly, the performance of the model is investigated by model tests. And the presented model is applied to the experimental data presented by Kumada et al. (2003).

The land reclamation area of Saemangeum in Korea is located between 126°10Έ~126°50Έ and 35°35'N~36°05'N at the western coast of the Korea. The 33 km sea dike and 40,100 ha reclamation area is being constructed in the Saemangeum area in Korea. Such large-scale coastal land reclamation project will certainly influence the marine environment and ecosystem in this area. It is necessary that the submerged breakwater could minimize and compensate the negative impacts in the marine environment and ecosystem caused by the marine construction. The submerged breakwater can function as a artificial fish reef and disaster prevention of the coast. The purpose of the study is to investigate hydraulic characteristics by change in the crest width, wave transmission, and porosity in case of permeable, impermeable, and horizontal plate submerged breakwater.

The Korean peninsula has a number of coastal sites where the rhythmic rising and lowering of water surface due to tides results in strong tidal current. The kinetic energy of these currents can be efficiently exploited by the use of tidal current turbines. The in-situ experiment for construction of tidal current power plant was carried out at the Uldolmok narrow channel between Jindo and Haenam in Korea. This paper describes and analyzes some observation results of field test about the efficiency of helical turbine for tidal current power plant. The efficiency of turbines with diameter 2.2 m and height 2.5 m is evaluated measuring RPM, torque, and current velocity. The tested helical turbines had the maximum efficiencies of the bounds of 30 to 35 % in the current velocity range between 1.5 and 2.1 m/s. Also, the turbines had the tip-speed ratios (TSR) of 1.9 and 2.4 with the number of blades. This result shows that the pilot tidal current power plant needs three helical turbines with diameter 3.0 m and height 3.6 m to produce electric power 500 kW.

This research illustrates a wave energy conversion system in the curtain wall type caisson breakwater. Moreover, using hydraulic model test and numerical model test, the effectiveness of wave energy generating system in Caisson on Breakwater was reviewed which is installed in East breakwater of Jeju outer port and planned to be operational in the near future. By comparing and analyzing the results from hydraulic model test and numerical test, this research was able to draw preliminary conclusion regarding the features of the turbine such as size and style and also installation placement within the chamber of the caisson.

This Kyunggi Bay is famous for its large tidal amplitude in the Yellow and East China Seas and some effort is made to use the large tidal energy for the generation of the electricity. Siwha tidal power plant with capacity of 254 Mw is being built inside the Kyunggi Bay and it will be completed by 2010. Again feasibility study with much larger capacity of power is being carried out in the neighboring site named as Inchon Bay. Both medium and large scale of tidal power generation schemes are under consideration for the Inchon Bay.

Large scale of deformation or reclamation of the coastal area in the northeastern area of the Kyunggi Bay deserves a special attention, because tidal wave in the northeastern Kuynggi bay is amplified and some deformation there may cause some larger change in the tidal regime both in the Kyunggi bay and in the Yellow Sea. According to theoretical study for the tidal deformation, the tidal wave was shown to be reflected or deformed due to the northern land effect.

In this presentation the tidal regime change due to the large scale deformation of the coastal area in the northeastern Kyunggi Bay inevitably accompanied by the construction of Inchon tidal power plan (ITPP) is examined in terms of the numerical modeling. Numerical mode for the Yellow and East China Sea model has been established for the purpose. The change of the tidal amplitude and phase lag is investigated as well as the change of tidal current regime in the northeastern Kyunggi Bay and corresponding tidal regime change in the Yellow and East China Seas.

In the recent years, there is an increasing awareness on the important roles of mangrove forests in coastal protection and coastal ecosystems in Vietnam. The country has lost more than 60% of its mangrove area over the last 60 years, putting its mostly low and weak sea dikes into a more vulnerable situation, facing the ever-increasing severe natural disasters approaching from the South China Sea. This experimental study was carried out to highlight the role of mangrove forests in dissipating the wave energy in storm conditions, thus effectively reduce wave load on sea dikes. It showed that with a mangrove forest of average density and appropriate length (about one significant wave length and above) the wave reduction coefficient can be as high as 80% depending on the water level. Again this enhances the necessity of growing and maintaining mangroves in front of the sea-dike as an economical and environmental friendly protection for Vietnamese shoreline.

To reduce the construction costs of seawalls and lower the environmental impact of construction, we have been working to develop a new high mound composite structure. Several studies have focused on the hydraulic characteristics of high mound composite seawall; however sufficient examination has not been carried out on the oblique wave conditions. Three-dimensional hydraulic model experiments were conducted to investigate the wave force characteristics and wave overtopping characteristics under oblique wave conditions. Based on the phase difference of impulsive wave force acting on upright sections, wave force reduction rate for oblique waves were proposed. Furthermore, influence of incident wave angle on wave overtopping rate and wave splash height were studied.

The process of sediment transport has a very complex mechanism due to waves, currents and bottom topography changes. Usually, beach erosion occurs from various causes such as non-equilibrium sediment transport condition, construction of seawall and rip currents. Therefore, the main mode and direction of sediment transport that causes beach erosion should determined to reduce and develop countermeasures for beach erosion. In this study, the process of sediment transport on Jeoncheon-Najeong Beach and main causes of beach erosion have been studied. In addition, countermeasures are planned for reducing the beach erosion. Field investigation data, aerial photos, and the results of numerical and movable hydraulic model tests were used in the analysis. As a result, it was realized that the main causes of beach erosion at Jeoncheon-Najeong Beach were due to the construction of fishery harbors and a seawall. The construction of artificial reef, net process, and hydrophilic shore protection were suggested in order to solve the problems of beach erosion. Also, the effectiveness of the countermeasures has been thoroughly examined by using numerical and hydraulic model tests.

This study presented the accuracy in predicted profile behavior by non-coupling and coupling methods, using both CSHORE and SBEACH models, compared to measurement obtained from the laboratory experiment. The results showed that using the CSHORE model, there was no significant change in the predicted profiles between non-coupling and coupling methods. On the other hand, using the SBEACH model, more accurate results are achieved with the coupling than with the non-coupling method.