The roll-on/roll-off (ro-ro) transport system, which plays a huge role in the transportation and economy of the Philippines, mainly uses piers to provide smooth berthing of ships. However, its structural configuration attracts different hazards causing damage, particularly to piles. Tsunamis produce devastating wave forces. This may heavily result in discontinuity of the whole port operation as there will be no available berthing structure for ships. Hence, this study was conducted to determine the structural resilience of the pile-supported piers of the Port of Batangas against tsunami loads at different variations of wave height and water depth. Structural software was used to model the piers and incorporate calculated tsunami drag forces. Furthermore, pushover analysis was performed to produce the base shear versus displacement curves needed for the calculation of the robustness index. The rapidity index, on one hand, is based on an interview with the Philippine Ports Authority - Port Management Office (PPA-PMO) of Batangas resulting in recovery rates for demolition works and pile replacement. Combining these indices using the concept of resilience triangle, values of the resilience index ranging from 0.0 to 1.0 were calculated at both longitudinal and transverse directions. As a result, the piers were categorized as highly resilient in almost 50% of the tsunami load cases. It proved that the pier with existing batter piles exhibits higher resilience than the other which is only supported by vertical piles.

As part of its economy-wide decarbonization target towards 2050, Japan plans to increase renewable generation, especially offshore wind, for which the country has a high potential. However, this resource is currently under-developed as available turbines are prone to shut-downs and can even suffer damage during the passage of typhoons. With new typhoon proof (T-class) turbines being currently developed by various companies, Japan now aims to develop 10 GW of offshore wind between 2021 and 2030, and 91 GW in the long-term. This research estimates the impact of integrating offshore wind into the Japanese main power grid using T-class turbines by considering three scenarios. First, a business-as-usual (BAU) case with 10 GW offshore wind capacity (following the 6th Strategic Energy Plan of Japan). Second, an offshore wind capacity of 91 GW. Third, the 91 GW offshore capacity being redistributed amongst regions to maximize its integration opportunities (Scenario 2). The simulations were carried out using the Energy System simulation model (EnSym). The results show that the BAU and Scenario 1 resulted in offshore wind achieving 1.7% and 7.28% of generation share, respectively, increasing to 9.77% for Scenario 2. Increasing the share of offshore wind in the energy mix mainly replaced liquefied natural gas (LNG)

The actions of wind and atmospheric pressure associated with tropical cyclones (e.g. typhoons) are considered the primary factors behind the generation of storm surges, though the fields used in meteorological models can sometimes deviate from observations. To improve these, the direct modification method (DMM) has been previously proposed, though this only modifies the wind field of a typhoon, and further development is necessary for applying it to storm surge hindcasts. The present work describes the development of a semi-empirical gradient wind balance-based method (GWB-M) for modifying both the wind and pressure fields in meteorological models, based on the dynamic relationship between the wind and pressure in typhoons (i.e. gradient wind balance). The applicability of GWB-M was assessed through a storm surge hindcast based on Typhoon Faxai in 2019, which generated powerful waves and a storm surge at Tokyo Bay. GWB-M improved the time series of 10 m wind speed and sea level pressure, with their spatial distributions being more realistic than those in DMM and blending parametric typhoon models (BM), which cannot take into account the influence of the complex topography around Tokyo Bay. Further, the maximum sea level anomalies after the typhoon made landfall were also captured by GWB-M with a higher accuracy than DMM.

In the context of Japanese energy targets for 2030 and the long-term strategy towards zero carbon emissions by 2050, this study estimates the impact of several measures for increasing the renewable generation share while maintaining a reliable energy system. To do so, the authors attempted to reproduce the expected 2030 energy mix according to the 5th Strategic Energy Plan, and then formulated two different alternative scenarios: a European-style merit order dispatch in Scenario 1, and the replacement of nuclear generation with renewables in Scenario 2. The simulations were carried out using the Energy System simulation model (EnSym), which was newly developed by the authors. EnSym simulates the hourly generation of all major resources, including variable renewables, using meteorological data. Spatially, EnSym also simulates the electricity transmission grid of Japan, allowing to understand how changes in grid capacity, dispatch framework and energy policy can impact the overall system. The results show that merely switching to a merit order dispatch could increase the use of renewable generation by 1.5% (to 22.6%). Further, replacing nuclear power resulted in a renewable share of 58.2%, which would include 300 GW of solar PV, 45 GW wind, 36 GW biomass and 23 GW geothermal capacity (while leaving all other generating capacity constant at 2021 levels). Based on these results, the authors also provide recommendations for changes to the next, 6th, Strategic Energy Plan.

Following the devastating Typhoon Haiyan, a project initiated by the Philippine government, known as Road Heightening and Tide Embankment (RHTE), was constructed to protect the coastal communities of the Leyte region in the Philippines against future storm surges. This research focuses on this newly built structure, which was investigated for coastal flooding and wave overtopping against extreme waves. Experimental and numerical modeling were conducted to simulate wave-structure interaction under different water level conditions. A 130 scale representative geometry of the tide embankment was set up inside a wave flume containing a scaled beach profile representing areas beyond the No-Build Zone mandated by the government. Dam-break wave flow was used to generate turbulent bores similar to that of a storm surge. For the numerical model, SolidWorks and ANSYS CFX version 17.1 software were used. The multiphase Volume of Fluid (VOF) method was used to track the free surface of the fluid flow and was shown to be an accurate tool for numerical validation, as the maximum wave height distributions in the presence of the structure using both methods were in close agreement with one another, but the numerical results overestimated the wave heights. The final design of the tide embankment with a return wall was modeled using ANSYS CFX. Experimental and numerical models generated wave heights that were higher than Typhoon Haiyan with inundation heights of 6 to 9 m above mean sea level (MSL) approaching the structure while the inland wave height was approximately 2 to 4 m above MSL. Results of the experiment also showed that the presence of the structure reduced the water level by 1 to 5 cm (about 0.3 to 1.5 m in actual scale). Moreover, the presence of a return wall will reduce the inland inundation height between 0.1 and 0.5 m above MSL.

6Haiyan in 2013 was one of the most powerful typhoons to have affected the Philippines, devastating in its path a wide portion of Leyte, and causing extensive damage to structures in Tacloban City. To understand the likely impacts that would be exerted by a storm surge on a structure deemed important, the authors used a coupled model that hindcasted the flooding that took place during Haiyan. This coupled model included the use of the Weather Research and Forecasting (WRF) Model (with Bogussing scheme) to simulate the atmospheric conditions during the passage of Haiyan, the Finite Volume Coastal Ocean Model (FVCOM) to simulate the storm surge and obtain the boundary conditions for the wind and flood (hydrostatic, hydrodynamic, and breaking wave), and the Structural Analysis and Designing Program (STAAD.Pro) to calculate the corresponding axial, shear, and bending moment envelopes based on the storm surge simulation. A 4-floor public school building in Tacloban was modeled and the effects that the storm surge would have on a corner column were analyzed. Based on the results, the axial, shear, and moment at the corner column significantly increased when considering flood loads, indicating the importance of including such loads in the design of essential structures.

A field survey of Fukuura Coast (in Tokyo Bay, Japan) revealed during the passage of Typhoon Faxai in 2019 waves with considerable momentum caused significant wave overtopping, resulting in structural damage to coastal defenses and localized flooding. The hindcasted wave height using a third-generation wave model was not high enough to explain the extent of the local damage at Fukuura Coast, likely due to such methods failing to take into account the strong gust-winds recorded during the passage of the typhoon. To solve such problems the authors developed a new numerical model that takes into account the dynamic interaction of air and water, based on the finite volume method (FVM) and the volume of fluid method (VOF). Although this model still slightly underestimates the measurements in the experiments previously conducted by different authors, it is better than existing methods when estimating the overtopping rates under strong winds. The model was then applied to a real-scale model of Fukuura Coast, where by taking into account strong gust-wind speed of 41 m/s the authors were able to explain the phenomena that took place.

Many countries and stakeholders are increasing their uptake of renewable energy and alternative fuel vehicles to decarbonize. Many countries adopted a technology-neutral paradigm to promote the update of such vehicles. Despite paradigm similarities, developments differ, even in comparable countries such as Germany and Japan. The reasons behind these differences are yet to be explained, and the present work thus examines developments in both groups over the past decade, highlighting how grid-modelling studies can help to plan for future developments in this sector. The main contributions of this work are, first, in providing a better understanding of the outcomes correlating to different implementation approaches of a similar paradigm between countries over a significant timeframe
second, in identifying further areas of research for integrated transport and grid modelling studies
and third, in making policy recommendations toward a more efficient implementation of a technology-neutral approach. Key findings are that while the fleet grows faster early on with a top-down- (Japan) than a bottom-up approach (Germany), both achieved similarly-sized fleets over a decade. For both, technological immaturity likely limited growth. Also, meteorological factors may intensify geographical clustering of specific technologies. The impacts of energy policy on regional transport technology penetration merits further research.

Soft measures such as evacuation planning are recommended to mitigate the loss of life during tsunamis. Two types of evacuation models are widely used: (1) Agent-based modelling (ABM) defines sets of rules that individual agents in a simulation follow during a simulated evacuation. (2) Geographical information systems (GIS) are more accessible to city planners, but cannot incorporate the dynamic behaviours found in ABMs. The two evacuation modelling methodologies were compared through a case study by assessing the state of evacuation preparedness and investigating potential mitigation options. The two models showed different magnitudes for mortality rates and facility demand but had similar trends. Both models agreed on the best solution to reduce the loss of life for the community. GIS may serve as a useful tool for initial investigation or as a validation tool for ABMs. ABMs are recommended for use when modelling evacuation until GIS methodologies are further developed.

A correction to this paper has been published: https://doi.org/10.1007/s11069-021-04687-9.

Solar PV capacity growth in Japan has been facilitated by a number of government schemes that have been implemented since 1994. Publicly available capacity data are provided by a number of agencies and organisations at various resolutions and at different stages within these schemes. This study provides a comprehensive review of solar PV data sources in Japan between 1994 and 2019, as well as an introduction to the subsidy schemes and organisations involved in scheme management and data collection in Japan. As a result, the authors produced their own dataset of installed capacities and generation across time for the various regions. Lastly, this study provides insights and recommendations to policy makers regarding opportunities for improving the accessibility and quality of data from a user perspective and to enhance Japan’s presence in international research.

The September 28, 2018 earthquake and tsunami, which occurred north of Palu City, Indonesia, attracted widespread interest from the scientific community due to the unusually large tsunami that occurred after a strike-slip earthquake with a relatively small moment magnitude (MW = 7.5). To understand the structural performance of buildings and infrastructure under hydrodynamic loads and their associated effects, the authors conducted field surveys in Palu City. Light wooden frame constructions and masonry infill walls were common in the area, some of which were severely damaged by the earthquake and tsunami. Reinforced concrete structures remained predominantly intact, although they suffered soil-related issues such as scour around rigid building members. Local structural failures caused by the loss of supporting soil were also observed during the field survey, resulting in an overall reduction in the stability of the inspected structures. Based on the observations made, knowledge gaps and research needs concerning coastal and structural scouring are discussed. These are tied into the latest community research activities and put in the context of a published ASCE standard chapter that discusses tsunami design.

Wave-flume laboratory experiments were conducted to study the mechanism of fluidization of partially consolidated mud beds, under wave propagation. The mixture of commercial kaolinite and tap water was allowed to partially consolidate under its self-weight before initiating the progressive wave propagation. The vertical changes in pore water pressure in the mud bed were monitored by using sensitive pore pressure transducers, at three levels across the mud layer depth. The experiments revealed that the wave characteristics and bed properties strongly affect the complex fluidization process, in which the accumulated pore water pressure develops through four transitional stages. The accumulated pore water pressure increases sharply at the first stage, which is followed by further gradual increases in the next two stages, with different rates. The breakup of aggregated mud particles, i.e. the generation of fluid mud, is observed at the last stage, resulting in a partial dissipation of accumulated pore pressure and wave height attenuation. The measurements also revealed that the fluidization starts from the top of the mud layer, and proceeds to the underlying layers.

Quantitative assessments on the effect of translate speed of typhoons on wind waves were carried out.A WRF-SWAN coupled model that used observed meteorological data was applied to eight different typhoons in the vicinity of Shiono-Misaki, on the pacific side of Honshu Island, Japan. The authors proposed a new methodology to modify the translate speed and wind field of tropical cyclones using an empirical model in which the gross wind speed is expressed as the summation of two different types of wind generation. Two different trends of the relationship between the significant wave height (H ) and translate speed (V) were found, describing the most dominant parameter. Typhoons with a modest intensity and size (for the case of Japan) generally showed a positive correlation between the change in the maximum H and V, which means translation wind speed was the dominant parameter. In contrast, stronger typhoons were less sensitive to the change in V and could maintain high waves even when almost stationary. With reference to the results, it is important to raise awareness of the future problems that could be caused by large storms that stall for prolonged periods of time. s s

The 2011 Tohoku Tsunami caused severe damage to many coastal defenses along the Japanese coastline, including areas where two adjacent upright sea dikes of different heights met. There are many places along the coastline where structures of different heights and shapes meet due to the various design codes. In this study, the authors aim to examine the tsunami flow around such dikes by conducting three-dimensional hydraulic experiments in a tsunami wave basin and numerical simulations using the fluid dynamics model OpenFOAM. Twelve experimental cases were tested by changing the waveforms, and also by keeping the height of one side of the dike model constant while adjusting the dimensions of the other side. The results show that the difference in height between the structures significantly influences the volume of overtopping over the relatively lower dike and the inundation depth and velocity behind the dikes. Furthermore, different characteristics of inundation patterns are observed between the inundation depth and velocity. Hence, this study illustrates the necessity to re-assess the effectiveness of such structures against tsunami events.

The 2011 Tohoku Earthquake and Tsunami generated a massive tsunami that devastated Kujukuri Beach in Chiba Prefecture, Japan. The possibility that edge waves were involved in the propagation mechanism of the tsunami was investigated by using a numerical method. To detect the components of edge waves, the fluctuations of the simulated sea level, the variations of the power spectral and the phase, coherences, as well as the dispersed relations of the wavelength and the period, were analyzed. As a result, it was possible to conclude that there is a high probability that edge waves could have propagated around this coastline. In addition, to analyze the various types of edge waves that could be expected three additional earthquake scenarios were considered, each of them with a different magnitude and epicenter: The 1896 Sanriku Earthquake, the 1677 Empo Boso-oki Earthquake, and the 1703 Genroku Kanto Earthquake. This comparison indicates that there is a particular risk that edge waves can be generated by large earthquakes with their epicenter in the northern part of the Japan Trench.

The deltaic coast of Myanmar was severely hit by tropical cyclone Nargis in May 2008. In the present study, a top-down numerical simulation approach using the Weather Research and Forecasting (WRF) and Simulating WAves Nearshore (SWAN) models was conducted to study the meteorological and offshore wave characteristics of cyclone Nargis near the coast of Myanmar. The WRF simulation results agree well with the observed data from the India Meteorological Department. SWAN simulation results were compared with the WaveWatch 3 model by National Oceanic and Atmospheric Administration and validated against available measurement data from satellites. The model results show relatively good agreement, and hindcast with satellites data (significant wave height only) shows a correlation coefficient value of 0.89. The SWAN and satellite comparisons also show better fit for high wave conditions. The resulted maximum significant wave height of 7.3 m by SWAN is considerably higher in energy than the seasonal waves normally prevalent at Myanmar’s deltaic coast. The possibility of high energy waves due to cyclones should be considered during the design and operation of coastal and offshore projects in the area, particularly given the risks that climate change can intensify cyclones in the future. Since Myanmar lacks a dense network of in-situ observational stations, the methodology used in the current study presents the potential application of various numerical techniques and satellite data to estimate extreme wave conditions near the Myanmar coast.

Three recent Tropical Cyclones (TCs) over the Arabian Sea, i.e., the super cyclone Gonu, the low intense cyclone Ashobaa, and cyclone Phet (with an unusual track), are studied using a high-resolution atmosphere-wave model and observations. The reliable performances of both atmospheric and wave models were established using the available field measurements, in which the modeling improvement in comparison with the previous studies is met. The effects of input parameterizations on the wave and wind estimations in the presence of TCs were examined. TCs track and intensity were more sensitive to the microphysics and cumulus schemes. Concerning the multi and single peaked wave spectra, three steps of wave generation, growth, and dissipation were addressed. Bimodal seas and swells exist in both generation and dissipation stages, whereas the seas are dominant in the growth stage. The performance of Westhuysen was better in modeling the combination of seas and swells.

Extensive field measurements along the north coast of the Gulf of Oman are analyzed to study the spectral characteristics of the generated waves of Ashobaa along the path of cyclone. The data showed a maximum significant wave height of about 3.2 meters on Iranian coasts. MLMST algorithm was used to process the directional wave. The measured wave spectra were bimodal (or trimodal) when the cyclone was far from the measuring stations. Approaching closer to the stations, the waves turned to unimodal spectra, with the highest measured wave energies at the time of minimum distance between the cyclone eye and the stations. Wave spectrum became bimodal again at the time of landfall, including the local seas and swell waves of the cyclone. After dissipation of the cyclone, swell waves dominate resulting in unimodal wave spectra. Study of 2D wave spectra reveals that minimum values of directional spreading correspond to peak frequencies.

The authors regret that there was an error in the transcribing process of Eq. 20, which can be found in section 2.1.7. of the article. The corrected equation, with added parentheses for further clarity, is as follows: [Formula presented] All computation results, analysis, discussion and conclusions presented throughout the article already reflect the findings based on the correct formula, with the only error being with the transcribing of Eq.20. The authors would like to apologise for any inconvenience caused.

In the present study, three different types of landslide-generated tsunamis (subaerial, partially submerged and submarine) were investigated through laboratory experiments that used 261 different experimental conditions. The results show that, for the near-field region, the subaerial landslide generated a higher leading wave, while the submarine landslide generated a higher second wave. However, frequency dispersion considerably influenced their propagation, with the leading wave decaying and the trailing waves being enhanced. The present study also revealed that the leading wave has higher values for wave celerity, period, and length than the second wave, regardless of landslide type. It was also shown that the celerity of the leading wave and second wave can be approximated by the solitary wave theory and third-order Stokes theory, respectively. Using the extensive experimental dataset obtained, predictive equations to estimate the maximum crest amplitudes generated by partially submerged and submarine landslides were also developed. A comparison with the experiments of previous researchers and field survey data from the 2018 Palu Tsunami indicated that these equations can estimate reasonably well the height of the generated tsunami. It was also shown that the relative mass and initial position of the landslide are influential nondimensional parameters to determine the tsunami amplitudes generated.

Water level oscillations induced by the ground motion of an earthquake have occasionally been observed in a closed or partially enclosed water system. The generated water disturbances can induce localized flooding, boat collisions, breakage/damage of moored cables due to water disturbances, or even the capsizing of vessels. In this study, the authors focused on cases of seismic water level oscillations in canals and attempted to investigate the potential hazards of and effective countermeasures against them through numerical simulations. The proposed numerical simulation model was first validated by reproducing the water level oscillation that was actually observed at a canal in Mexico City (Xochimilco Canal) during the 2017 Central Mexico Earthquake. The method was then applied to one of the canals in Tokyo (Keihin Canal) to clarify the potential water level fluctuations that can take place due to this phenomenon. The results indicate that while the risks of local inundation would be low, small boats, which can be found in many places in the canal, are at risk of capsizing. Finally, the use of wave-dissipating blocks was found to be an effective countermeasure to decrease the potential for a significant seismic water level oscillation to take place in this canal.

Volcanic ashfall can cause considerable social impacts to a wide geographical area. Given the challenge to predict volcanic eruptions, it is essential to simulate the dispersion of ash as soon as possible after an event and promptly estimate the distribution of deposits and necessary removal works. In this study, a series of procedures to improve the accuracy of the WRF-FALL3D model for the case of the eruption of Mt. Kusatsu-Shirane in 2018 are proposed, which were verified through field surveys of ash deposits, showing that the accuracy of the model can be improved by selecting a range of column heights and promptly conducting field surveys following an event. Also, a methodology to estimate the amount of work necessary to clear road networks and river channels is proposed, which was applied to a volcanic event similar to that of the Hoei eruption of Mt. Fuji in 1707. The results also emphasize the need to improve the estimation of column heights in the future, which is of paramount importance to ensure the safety and operational continuity of human infrastructure in the vicinity of major active volcanoes.

A total of 7 reference concentration (C ) models (6 existing and 1 newly proposed) were validated against 119 test cases from 4 recently published datasets collected under the LIP, CROSSTEX, SandT-Pro and SINBAD experimental studies. These models were evaluated for performance in different cross-shore regions: the shoaling zone, breaking (outer surf) zone and inner surf zone, under regular and irregular breaking wave conditions. In almost all existing C models, substantial under-prediction was found particularly around the wave plunging point (point at which breaking wave plunges and surface generated turbulent kinetic energy, TKE, is injected into the water column) where strong localised increases in C were observed. This strong increase in concentration was attributed to the large-scale breaking-generated turbulent vortices invading the wave bottom boundary layer (WBBL) and entraining dense clouds of sediment near the plunging point. Models that were directly or indirectly driven by local wave climate such as the local wave height (H), breaker height (H ) or local water depth (d), were found to perform quite poorly in the breaking region under regular and irregular plunging breaker waves. Formulations that related C to the sand pickup rate (i.e. depending on exerted bed shear exceeding critical bed shear for entrainment) were adept in regions unaffected by external breaking-induced TKE (e.g. the shoaling zone) but could not account for the high levels of concentration observed at the plunging point. This is because these formulations were based on the implicit assumption that sediment entrainment is only induced by the local TKE generated by bed shear; not taking surface-generated breaking-induced TKE into account. This assumption was addressed in more recent studies, by including breaking-induced TKE into sediment pickup rate or reference concentration formulations. Though latest studies have shown promising relationships between near-bed TKE (k ) and reference concentration/sediment pickup, such formulations also face inherent limitations. These formulations are highly dependent on the accuracy of measured or modelled k and are also sensitive to the magnitude of k . For example, the magnitude of measured k was found to vary by a factor of 1.1–1.3 between regular and irregular wave conditions, with k being smaller under irregular wave conditions. This resulted in varied performance between datasets in k -driven reference concentration formulations. The Froude-scaled TKE produced smaller deviations in magnitude of TKE between datasets, suggesting that it may be a more suitable driving parameter for reference concentration models than k . A new reference concentration model, L19, was empirically derived from an inverse relationship observed between d and C , and from the roller energy dissipation rate. The newly proposed L19 model shows good agreement with measured C (with RMSE ranging between 0.36 and 1.79 kg/m over the different datasets) in regular and irregular wave conditions, even at the plunging point where concentration is highest. The modified concentration profile [C(z)] equation also performs well, generally capturing the vertical concentration profile accurately throughout the whole water column. 0 0 0 b 0 b b b b b b b 0 0 3

© 2020 Evacuation plays an important role in saving lives during tsunamis. Although evacuation by vehicle is generally not recommended, it could be helpful for vulnerable people who cannot walk fast (e.g. the disabled, elderly, or infants). In the present study, the authors developed an agent-based tsunami evacuation model that considers the behaviour of both pedestrians and car evacuees, which can be important to formulate effective evacuation plans. The model developed was validated through comparisons with the actual traffic jams observed at Tagajyo City, Japan during the 2011 Tohoku Earthquake Tsunami. The model was then applied to another coastal city in Japan (Shinguu City) to investigate the effectiveness of an evacuation plan that considers vehicle use for evacuation during a future Nankai-Tonankai Earthquake Tsunami. The simulated results indicate that considering the capacity of evacuation places and the choice of route is important for a successful evacuation, especially for a coastal area where the number of evacuees could exceed the total capacity of its evacuation buildings.

© 2020 American Society of Civil Engineers. In the case of a near-field tsunami event, coastal residents must quickly become aware of the potential danger of a tsunami taking place and start taking actions to evacuate. The present paper aims to show which types of evacuation triggers worked amongst coastal residents with different characteristics and backgrounds by conducting a comparative analysis of four recent near-field tsunami events. The results of the analysis showed that basic knowledge about tsunamis had been spreading throughout the areas studied, which triggered many people to evacuate soon after feeling ground motion, almost regardless of how frequently each area had experienced tsunami events in the past. Educational activities and community-based efforts appear to be some of the reasons that can explain this finding. However, because some people in areas with fewer past experiences only evacuated after noticing last-minute signs and there is a nonnegligible number of visitors present in the coastline of certain communities, continuous efforts toward developing tsunami awareness are still needed. The results of the analysis also showed that in areas with fewer past experiences, people were more likely to wait for messages from the authorities to decide to evacuate. This finding highlights the importance of teaching local residents and visitors how a tsunami can reach a given area in a relatively short period of time.

© 2020 Elsevier Ltd The present study proposes a comprehensive investigation of the tsunami-evacuation plans for a popular coastal area considered to be at high risk for tsunami attack. If a coastal region constitutes a renowned sightseeing location or has a popular beach, numerous tourists and beach users could be at risk of a tsunami. However, tsunami risk management strategies have generally been developed considering only local residents, and the effects of the presence of tourist on the effectiveness of countermeasures have rarely been taken into account. To investigate changes in the effectiveness of tsunami countermeasures under different population scenarios, the authors further developed an existing agent-based tsunami evacuation simulation model. Through the application of this model to Yuigahama Beach in Kamakura City, Japan, it was found that the effectiveness of hard measures (i.e., elevating the road embankment) is slightly influenced by the numbers and types of evacuees who are present on or near the beach when a tsunami arrives. However, the effectiveness was greatly influenced by the type of soft measures (i.e., changing the evacuation behaviour) employed. It was also shown that, if there are many evacuees in a coastal area, soft measures merely aiming at early evacuation and guiding evacuees to the closest evacuation place via the shortest route could instead worsen the fatality rate. The present study thus sheds further light on the importance of establishing tsunami mitigation strategies that focus on the tourist population, in order to minimize the number of fatalities that could result from a future event.

© 2020 Sea level rise is one of the major challenges facing humanity in the 21st century, and could compound the risks posed by tsunamis to coastal cities. The authors conducted computer simulations of tsunami inundation and propagation into Tokyo Bay, and analysed the risks that such events pose to the cities of Yokohama and Kawasaki, for different sea level rise scenarios . The results show that unless significant investment in improved coastal defences is made, the area that can potentially be flooded by such events will gradually increase in the course of the 21st century. However, the risk to the life of the inhabitants of these cities will broadly remain unchanged until sea levels become +1.0 m higher than at present. From then, the risk of casualties taking place will rapidly increase, as the depth and velocity of the tsunami wave will substantially rise. Such results provide some indication regarding the long-term planning strategy to manage coastal defences around Tokyo Bay, highlighting the need to eventually reinforce coastal defences and the important contribution of tsunami evacuation to minimize casualties during such events.

© 2019 The accurate modelling of overtopping of coastal defences by tsunami waves is of vital importance for the formulation of disaster management strategies. To improve knowledge of this phenomena the authors conducted experiments on coastal structure overtopping using bores that were generated by a dam-break mechanism. Three types of structures were tested, namely a coastal dyke, a wall, and a wall of infinite height. The results highlight the necessity to consider the energy present in a bore to determine if a structure will be overtopped or not. As a result of these experiments an empirical formula to determine the height of overtopping given the incident bore height and velocity was validated. The study highlights the importance of clearly modelling the velocity and Froude number of a tsunami. Such experiments should be conducted on rough beds, for which a suitable Manning's n seems to be around 0.06 sm-1/3. The study also contrasted the results obtained to those of the ASCE7 method, and concludes that the Manning's n values recommended in ASCE7 are probably too low.

Typhoon Faxai caused severe damages along the western shore of Tokyo Bay, Japan in September 2019. Retaining a relatively small radius of maximum wind, Faxai passed across the center of Tokyo Bay and caused intensive wind and waves. While the sea level anomaly recorded at several tide gauge stations along Tokyo Bay were at most 1 m, and no significant surge-induced inundation was found, locally concentrated damages and wave-induced hazards were observed around Yokohama, on the middle-western shore of Tokyo Bay. The observed inundation height around Yokohama was TP (Tokyo Peil) 4.2 m on average, and the highest runup, TP 10.8 m, was observed at a small hill directly behind the seawall in Fukuura, Yokohama. The estimated wave overtopping directions at each location varied from the northeast to southeast, and no clear correlation was found between the wave overtopping directions and the extent of observed coastal hazards. Based on these findings and investigations of recorded data such as wind and waves, it was deduced that locally concentrated damages and hazards around the middle western shore of Tokyo Bay may be explained by the unique features of a relatively compact Faxai and the topographical characteristics of Tokyo Bay.

Tsunamis can cause large damage to breakwaters and other protection structures placed along the coastline. The strong flows generated by such waves can move the armor units of composite breakwaters, leading to large impact forces on the caissons behind them. In the present work laboratory experiments were carried out in a flume to determine the forces that can result from such impacts. Then, an empirical equation that would allow the estimation of these forces was proposed, with the aim of facilitating the construction of returning walls and parapets situated on top of caissons.

© 2019 Elsevier Ltd On September 28, 2018 significant tsunami waves, which are considered to have been generated by submarine landslides, struck the shorelines of Central Sulawesi, Indonesia. One month after the event, the authors conducted a questionnaire survey of the affected areas (Donggala Regency and Palu City) to collect information on the evacuation behaviour and tsunami awareness of local residents. In the present study, in addition to summarising the overall trend of the survey results using descriptive statistics, a chi-squared test was applied to analyse the significance of the relationship between tsunami awareness and evacuation behaviour and the demographic characteristics of respondents. The analysis of the results demonstrates that although the respondents generally have a high level of tsunami awareness, younger people and Donggala Regency residents have an overall lower understanding of the phenomenon. It was also found that 82.5% of the population evacuated after witnessing others evacuating during the event. As there was no official warning to residents before the arrival of the tsunami, this social trigger played a significant role in prompting evacuation and decreasing the number of casualties. The present study also revealed that many people faced congestion while evacuating (especially in Palu City). This highlights the need to introduce additional tsunami disaster mitigation strategies to ensure that all residents can swiftly evacuate during such incidents.

The authors conducted extensive field surveys in densely populated coastal areas affected by land subsidence in Indonesia, Philippines and Japan. The results indicate that the preferred adaptation mechanism for coastal areas is elevating them using soil, rubble, or coral stones, and then re-surfacing to obtain a smooth surface, and building dykes where possible. Eventually, pumps are installed, and new areas can be reclaimed from the sea. By studying how densely populated coastal communities have attempted to adapt to land subsidence, it is possible to try to understand the effects that future sea level rise will have on other areas of the planet.

Electricity grid decarbonisation requires major changes in resource composition, the size and location of power plants, as well as electricity flow direction capabilities [1]. Coupled with transport sector integration, the introduction of different alternative fuel vehicles (AFVs) creates a new demand source that will require distribution, while also offering flexibility balancing capacities to the grid. Japanese grid operators have so far managed regions that are relatively poorly interconnected, resulting in an overcapacity of thermal power stations [2], which negatively affects renewable integration. Regionally, renewable implementation capacities and strategies differ based on a complex set of factors, such as geography, favourable resource type, connectivity with other regions, population developments, car ownership and use, as well as political strategies [3]. The overall aim of this study is to assess the overall maximum renewable integration and associated vehicle technology composition that Japan could support by the year 2030. To do so, three scenarios were formulated, which were compared to a baseline case study of the present-day electricity sector. In doing so, the authors compared the roles and requirements of different AFV technologies as new demand sources and flexibility management tools between metropolitan and non-metropolitan areas, based on the different car ownership and use profiles, as well as resource compositions. The simulations were carried out using the EnSimGrid model, developed by the authors. This can simulate the hourly supply and demand of electricity of the nine grid operator regions in Japan (excluding Okinawa) together with transmission level interconnection, as well as a parallel hydrogen network. Additionally, in several of these regions the 15 metropolitan areas of the country were separately modelled from non-metropolitan areas. The AFV technologies modelled are fuel cell electric vehicles (FCEVs) and battery electric vehicles (BEVs), with the latter performing vehicle-to-grid services. In all scenarios the renewable generation is based on hourly real-time meteorological data from the JMA, allowing for a realistic simulation of the energy production by these intermittent resources. The results indicate that there are regional differences between the electricity demand of metropolitan and non-metropolitan areas that is required for charging AFVs, and therefore different opportunities for renewable integration at different scales (between regions and within different types of areas in the same region). Secondly, by reducing thermal capacities in historical supplier regions to Kanto (in accordance with their regional strategies), such as Tohoku, transmission chains became more spatially distanced from the receiving region. This future expected reduced thermal plant overcapacity provides a compelling incentive to invest in an efficient transmission grid expansion, which renewables would also profit from. Thirdly, a smoothing impact of compatible AFV technology fleets on renewable generation can be observed, especially for BEV fleets in Kyushu (where solar PV is currently dominant), which confirms previous observations regarding vehicle technology and specific resource relationships [4].

Japan has a long stretch of coastal dykes along its shoreline to protect against storm surges, tsunamis and high wind waves. The 2011 Tohoku Earthquake and Tsunami caused serious damage to these coastal dykes. To improve the coastal dykes along the damaged coast and also to reconsider tsunami risks in other parts of the Japanese coast, it is important to understand the effect that a tsunami can have on a coastal dyke. The present paper thus aims to analyze a tsunami flow around a coastal dyke using a LES numerical model. To simulate both an impact phase and an overtopping phase of a tsunami flow, which were observed in the 2011 tsunami, a dam break flow and a pump flow were used to generate a tsunami-like flow in the numerical model. Based on the numerical results, the pressure and the velocity field around a coastal dyke were ascertained. These effects were considered to have a big influence on the dike failure in the 2011 tsunami, and thus it is recommended that the design of countermeasures should include a calculation of both of these parameters.

Since 2004, there is a growing awareness of the risks that tsunamis pose to coastal communities globally. Despite the fact that these events were already an intrinsic part of the culture of some countries such as Chile and Japan, many other places had virtually not heard about such phenomenon before 2004. Nevertheless, the frequent reoccurrence of major tsunamis in recent years has led to the emergence of a “tsunami culture” in many areas of the world, which has resulted in increased awareness, disaster preparedness and willingness of local populations to evacuate when the threat of these events arises. However, evacuation during a tsunami is still not successfully carried out by the different elements of society, pointing to lack of awareness, an over-reliance in defence mechanisms or lacking in the transmitting of knowledge from previous events. This paper will explore these cultural issues using as a basis questionnaires carried out by the authors during their own field visits to the last three major events (Chile in 2009, Indonesia in 2010 and Japan in 2011), and interpret these through the willingness of coastal communities to build protection measures along the shore and the impact that these can have on sustainable development. The existence of a “traditional tsunami culture” will be explored through an analysis of the existence of multi-layer safety system constructed by previous generations, and whether this is being preserved nowadays or past lessons are being forgotten.

© APAC 2013.All rights reserved. On March 11, 2011, a large earthquake that occurred offshore the northeast coast of Japan generated a large tsunami which devastated extensive areas of the Tohoku coastline and large casualties were recorded. Based on the experiences, coastal protection works in Japan are now in the process of modifications. In the present paper, Tokyo and Kanagawa are taken as examples and new methodologies are explained in the area. For the case of storm surge, a new model is applied to predict the future behavior of storm surge. For the case of tsunami, Genroku Kanto Earthquake (1703), Keicho Earthquake (1605) and Meiou Tokai Earthquake (1498) were mainly discussed in the numerical analysis, since tsunamis caused by these three earthquakes gave strong damages to coastal area of Kamakura, and left influences to Yokohama and Tokyo. New tsunami flood maps over coastal land area based on numerical simulations were presented to the residents of coastal region on April 2012 in Kanagawa prefecture. For Kamakura area, Keicho Earthqueke takes 90 minutes to reach the Kamakura coast and the height is over 12 m. But for the case of Genroku Kanto earthquake it takes 25 minutes and the height is 8 m. It appears that there are two different types of risk, 1) high wave comes but we have time for evacuation and 2) relatively small wave comes quickly and time is limited for evacuation. New countermeasures including soft and hard techniques are also required.

<p> Water–level fluctuations resembling long period waves, which differ from normal wind waves, were observed immediately after the Tohoku earthquake of 2011 in multiple locations, such as lakes in Yamanashi Prefecture, the fjords of Norway, and other sites located far away from the epicenter. Not many research on similar abnormal water–level fluctuations have been conducted thus far and, in many cases, these studies have treated the phenomena as seiches. However, researchers have not established concrete wave generation mechanisms and evaluation methods, and their awareness of this phenomenon and disaster prevention remains low. In this study, the authors sought to select a quantitative impact assessment method and learn more about this phenomenon. The authors used previous research and eyewitness accounts to judge that onsite slosh dynamics caused the waves to generate, and the authors attempted to recreate this phenomenon using a 3-D slosh dynamic analysis. After comparing laboratory results to verify the validity of the analysis, the authors recreated past examples of waves and also made future predictions. As a result, the authors were able to recreate abnormal water–level fluctuations based on this method. In addition, the authors identified water damage risks to in-land lakes and waterways of inner parts of bays. These are different from risks posed by tsunamis. The waves are formed immediately after the onset of an earthquake.</p>

On the 22nd of December 2018 the shorelines of Sunda Strait, Indonesia, were hit by tsunami waves generated by the flank collapse of the Anak Krakatau volcano. The authors conducted a field survey of the affected areas in both Sumatra and Java islands to collect information on tsunami inundation and run-up heights, damage patterns at each coastal community, and the evacuation behaviour and tsunami awareness of the affected people. The survey results showed that in Sumatra island inundation heights of more than 4 m were measured along the coastline that was situated to the north-north-east of Anak Krakatau, while less than 4 m were measured along the north-western direction. Inundation heights of over 10 m were measured at Cipenyu Beach (Pandeglang Regency) in Java island (south-south-eastern direction from Anak Krakatau). A questionnaire survey conducted by the authors revealed residents' perception of danger and evacuation patterns during the event. The results indicate the importance of having an operational tsunami warning system in Sunda Strait and the establishment of an appropriate evacuation plan so that residents can start evacuation immediately and reach a safe place without facing severe congestion along evacuation routes.

© 2019, Springer Nature B.V. Due to gradual sea level rise and changes in the climate system, coastal vulnerability to storm surge hazards is expected to increase in some areas. Studies regarding the effect of storm surge inundation on buildings and human lives, especially when it comes to relatively low-threat level events, have been few, however. In this research, storm surge load impact around coastal residential areas was quantitatively assessed, through fine-resolution numerical modelling. Meso- and street-scale simulation results for a storm surge event in Nemuro, Japan, were comprehensively validated against observations and field measurements, and the simulation results showed good accuracy for sea level, significant wave height and inundation area. A fine-resolution, street-scale coastal flood simulation was carried out with individual and grouped buildings, created with a building block model, and the results showed the significant role of buildings by realistically capturing inundation dynamics. Hydrodynamic results showed that coastal flood impact on buildings was insignificant (consistent with surveys). Lastly, the potential flood impact on people in the streets was investigated, using five human instability equations, where the most pessimistic results showed average values between 0.0 and 0.2 (max 0.6–0.7), and slightly below 0.4 for children and the elderly, respectively. These values indicated that threat levels during the Nemuro storm event were low, which corresponded with observations (no fatalities). This study framework could be applied wherever an accurate local storm surge threat estimate was required.

In the present study, numerical simulations were conducted to estimate the spatio-temporal characteristics of tsunami inundation for municipalities on Vancouver Island, Canada, as a result of various potential Cascadia Subduction Zone earthquake deterministic scenarios. By varying the earthquake magnitude and associated slip distance, the influence of these parameters on the tsunami wave propagation, inundation, and the possible damage on infrastructure and buildings was investigated. A numerical tsunami inundation model based on nonlinear shallow water equations was constructed using publically available bathymetric and topographic data and applied to three study areas: the City of Port Alberni, the District of Ucluelet, and the District of Tofino. The numerical results obtained in this study show that the maximum tsunami inundation depth and spatial extent of inundation are sensitive to the earthquake magnitude, whereas the tsunami arrival time is not. For the worst-case earthquake scenario investigated (M-W 9.3), all of the three study areas were extensively inundated. Results of tsunami wave amplitude and overland inundation depth, flow velocity, hydrodynamic force, and depth-velocity product are analysed in detail to assess the impacts of the tsunami on inland buildings. The potential damage was estimated with previously proposed fragility curves for wood, reinforced concrete, and steel frame buildings. In conjunction with a site reconnaissance visit by the authors for better understanding the general characteristics of these areas, model results suggest that significant damage to buildings would occur, especially to wooden constructions, with considerable risk of loss of human life.

On September 28, 2018, a large earthquake and its accompanying tsunami waves caused severe damage to the coastal area of Palu Bay, in the central western part of Sulawesi Island, Indonesia. To clarify the distribution of tsunami inundation and run-up heights, and damage to coastal communities due to the tsunami, the authors conducted a field survey 1 month after the event. In the inner part of Palu Bay tsunami inundation and run-up heights of more than 4 m were measured at many locations, and severe damage by the tsunami to coastal low-lying settlements was observed. In the areas to the north of the bay and around its entrance the tsunami inundation and run-up heights were lower than in the inner part of the bay. The tsunami inundation distance depended on the topographical features of coastal areas. The southern shore of the bay experienced a longer inundation distance than other shores, though generally severe damage to houses was limited to within around 200 m from the shoreline. The main lessons that can be learnt from the present event are also discussed.

© 2019 Japan Society of Civil Engineers. Typhoon Jebi in 2018 caused severe damage along areas of Osaka Bay, Japan. After the storm, a Japan Society of Civil Engineers (JSCE) coastal survey group surveyed the coastal impacts and recorded watermarks inside Osaka Bay and along the Pacific. The maximum storm tide recorded by a tide gauge was 3.29 m at the Osaka Tide Station, which is a historical high for Osaka Bay. Coastal flooding consisted of both storm surge and wave run-up in almost all locations, with flooding exceeding 5 m and 12 m in elevation from mean sea level in the inner parts of Osaka Bay and along the Pacific coast, respectively. Coastal damage was severe in areas located outside of coastal barriers, such as ports and harbors, while residential areas were mainly well protected and spared due to coastal protection systems. In addition, some inland flooding occurred in the Kobe-Ashiya regions due to the storm surge propagating up several small rivers. This survey report summarizes the findings of the post-event survey by JSCE and analyzes the relation between maximum water level and resulting damage.

© 2019 Japan Society of Civil Engineers. A new semi-empirical formula for calculating the breaking depth of plunging breakers is proposed in this study. The shallow water equation is used as the governing equation, and the wave front slope, which is one of the key parameters that governs the breaking criterion, is obtained from it analytically. The analytical formula was then modified based on both physical considerations and historical laboratory data. The accuracy of the resulting semi-empirical formula was examined using two sets of new laboratory data - including laboratory experiments performed by the authors - in order to verify its applicability. The results indicate that the proposed new formula is more accurate than existing formulas.

In the past two decades there have been fears that many low-lying atoll islands around the world could disappear as a consequence of climate change and sea level rise, leading to mass migration and threatening the existence of several island nations. Here we show how sea level rise does not inevitably lead to coastal areas becoming uninhabitable, and that humans have an innate and often underestimated capacity to adapt to changes in their environment. To do so we showcase three instances of human- and earthquake-induced land subsidence that have taken place in the 21st century, where the coastal/island areas are still inhabited despite the challenge of living with higher water levels: the Tohoku coastline following the 2011 Tohoku Earthquake Tsunami (subsidence similar to 0.4-1.0 m), the present day situation of coastal areas in Jakarta due to ground water extraction (> 5.0 m), and the islands of Tubigon, Bohol in central Philippines after the 2013 Bohol Earthquake (similar to 1.0 m). Humans are able to adapt and arrive at solutions even when confronted with cases of rapid rises in water levels, and thus it is likely that in the future vulnerable coastlines will be engineered and largely remain at present day locations, particularly in densely populated areas. If anything, around densely populated areas it is more likely that humans will continue to encroach on the sea rather than the reverse. We caution, however, that small islands are not homogeneous, and many are unlikely to respond to rising sea levels in the manner that atolls do (in fact, many might just resort to build at higher elevations). Where engineering and other adaptation responses become necessary, the financial and human resource requirements may well be beyond capacity of some small islands, which could lead to impoverishment and associated challenges in many communities.

Heavy precipitation from extratropical cyclones (ETCs) can have serious environmental and societal impacts. The aim of the study is to model changes in ETC-related precipitation in the Baltic Sea area by the end of 21st century. Using the Weather Research and Forecasting model (ARW-WRF), Coupled Model Intercomparison Project (CMIP5) ensemble output, the IPCC proposed RCP8.5 future scenario, and two hindcasted ETCs (Jan 2005, Nov 2008), we study these storms in projected future (i.e. "surrogate") conditions. The results showed up to 20-30% increase in precipitation
the spatial shifts and variability within the modeling domains were still substantial.

The purpose of the paper is to analyse and compare the possible future parameters of four extreme cyclonic storms (Nargis in 2008, Haiyan in 2013, Gudrun in 2005, St. Jude 2013) as they would occur in the end of 21st century under warming climatic conditions. Using a modeling system composed of the Weather Research and Forecasting (ARW-WRF) atmospheric model, Finite Volume Community Ocean Model (FVCOM), and surrogate background conditions taken from Coupled Model Intercomparison Project (CMIP5) output in line with the IPCC proposed RCP4.5 and RCP8.5 future scenarios. The results generally showed an intensification of tropical cyclones (TCs) and corresponding increase in storm surge heights. In case of extratropical cyclones (ETCs), the future changes were either smaller or less clear.

Debris loading has been identified during several forensic engineering field surveys in the aftermath of the 2004 Indian Ocean and 2011 Tohoku Japan tsunamis as a critical design load. However, little research has addressed the assessment of debris loading hazards. The study presented herein examines the entrainment and transport of debris over a 1:10 sloped bed as well as over a flat, horizontal bed in tsunami-like conditions. The study was performed at a 1:50 scale and the debris was modelled as scaled-down shipping containers. The friction between the debris and the bed was varied by modifying the material installed on the slope as well as by covering the surface of the debris surface with materials with different degrees of friction. The debris-bed friction influenced the characteristics of the initial entrainment of the debris, which varied from sliding to rolling, depending on the magnitude of the static friction. This study also determined that the friction did not have a significant effect on the lateral spreading of the debris. However, a significant difference was observed in the case of the longitudinal displacement of debris (in the flow direction).

Typhoon Jebi struck Japan on the 4 September 2018, damaging and inundating many coastal areas along Osaka Bay due to the high winds, a storm surge, and wind driven waves. In order to understand the various damage mechanisms, the authors conducted a field survey two days after the typhoon made landfall, measuring inundation heights and depths at several locations in Hyogo Prefecture. The survey results showed that 0.18-1.27 m inundation depths were caused by Typhoon Jebi. As parts of the survey, local residents were interviewed about the flooding, and a questionnaire survey regarding awareness of typhoons and storm surges, and their response to the typhoon was distributed. The authors also mapped the location of some of the containers that were displaced by the storm surge, aiming to provide information to validate future simulation models of container displacement. Finally, some interesting characteristics of the storm surge are summarized, such as possible overtopping at what had initially been thought to be a low risk area (Suzukaze town), and lessons learnt in terms of disaster risk management are discussed.

© 2018 Elsevier Ltd The upper fluid mud layer in muddy environments absorbs wave energy and, in turn, moves due to the wave action. In addition to these two major phenomena of wave-mud interaction, introduction of current in the wave field also changes the wave characteristics as well as the rates of mud mass transport. The present study offers an experimental investigation of wave-current-mud interaction to address the wave transformation and mud mass transport on a horizontal bed. A number of laboratory tests were conducted to measure the mud particle velocities as well as wave attenuation rates under following, opposing, and no current conditions. Both the wave energy dissipation and mud mass transport increase with the presence of opposing currents and decrease when following currents are introduced. A semi-analytical model was also presented and the numerical results are compared with the laboratory experiments, showing acceptable agreements.

Debris loading during extreme flooding events has been documented by many post-tsunami field surveys of disaster-stricken communities and, as such, it is now considered and accounted for as a critical design consideration in the design of resilient infrastructure. Debris damming is one of the debris loads of concern, occurring when solid objects entrained within the inundating flow accumulate at the face of a structure or structural element. The presence of the debris dam results in increased drag loads on the structure and can have other associated effects, such as flow runup and flow accelerations, that can influence design conditions. The focus of debris damming studies has been within river engineering: therefore, previous studies have been performed in steady-state conditions. The study presented here is the first to examine debris damming in transient, supercritical flow conditions. The study uses a modified dam-break wave as the hydrodynamic forcing condition and the debris are scaled down debris types common in coastal areas (shipping containers, hydro poles, and boards). The analysis includes a qualitative examination of the difference in the debris damming mechanisms as a result of distinct flow conditions associated with a dam-break wave interacting with a surface-piercing obstacle. Additionally, the study determined the influence of the debris dam resulted in a maximum loading condition that occurred earlier and was of greater magnitude than the clear water case.

Tsunamis are some of the most destructive types of natural hazards that can affect coastal areas. To optimize tsunami mitigation measures, it is important to estimate the potential casualties that can result from one of these events. Taking into account tsunami awareness and the possible evacuation behavior of at-risk individuals is necessary to estimate the number of casualties, though most of the research carried out to date has not considered detailed evacuation behavior when conducting simulations. In the present study, the authors proposed a new approach to estimating the number of tsunami casualties, based on a tsunami evacuation simulation model that considers the evacuation behavior of local residents, tourists and beach users. Such behavior parameters were incorporated by analyzing the results from previous questionnaires surveys. The model was applied to Yuigahama Beach in Kamakura City, Japan, with the aim of assessing potential tsunami casualties and providing suggestions regarding tsunami mitigation measures. The authors conducted seven tsunami inundation simulations for different earthquake scenarios, and then casualties were estimated considering six different evacuation scenarios. Based on the simulation results, it appears particularly important to attempt to improve the intended evacuation behavior of both the local population and visitors. Particularly, providing information about safe places and the routes to reach them is necessary, as prompt evacuation and heading to higher ground were found to be insufficient behavior to save lives during a tsunami event.

Awareness about the threats posed by different types of coastal disasters has increased throughout the world, as people are exposed to the nature of these hazards through media reports on events in distant countries. This has resulted in coastal residents being aware about the destructive power of tsunamis, despite no such events having taken place in their country in recent times. Regardless of this increased awareness, it has been hypothesized that there is still need for local governments to enact adequate policies to raise the awareness of local residents, for example, by holding regular evacuation drills. The present research presents a comparative assessment of tsunami awareness in two tourist destinations in Japan and the USA, which was derived through structured questionnaire surveys of beach users in the city of Kamakura and various coastal cities in Florida. The results show how despite relatively high level of awareness tsunamis still pose a considerable risk to each of the communities, for example, due to shortcoming in evacuation knowledge and infrastructure.

© 6th International Disaster Mitigation Specialty Conference 2018, Held as Part of the Canadian Society for Civil Engineering Annual Conference 2018. All rights reserved. Debris loading during extreme flooding events has been documented by many post-tsunami field surveys of disaster-stricken communities and, as such, it is now considered and accounted for as a critical design consideration in building resilient infrastructure. Debris damming is one of the debris loads of concern, occurring when solid objects entrained within the inundating flow accumulate at the face of a structure or a structural element. The presence of the debris dam results in increased drag loads on the structure and can have other associated effects, such as flow runup and flow accelerations, that can cause increased scouring at foundations. The focus of debris damming studies has been within river engineering: Therefore, previous studies have been performed in steady-state conditions. The study presented here is the first to examine debris damming in transient, supercritical flow conditions. The study uses a modified dam-break wave as the hydrodynamic forcing condition and the debris are scaled down debris types common in coastal areas (shipping containers, hydro poles, and boards). The study qualitatively examines the difference in the debris damming mechanisms as a result of distinct flow conditions associated with a dam-break wave interacting with a surface-piercing obstacle. Additionally, the study aimed to determine the influence of the debris dam. It was found that maximum loading condition occurred earlier and of greater magnitude than for the clear water case.

One-month wave simulations were performed from Oct. 1st to Nov. 1st in 2014. The one-way numerical models composed of WRF (Weather Research and Forecasting) and SWAN (Simulating WAve Nearshore) were used. This research focused on evaluations of both a resolution of wind data and a difference between structured SWAN (STSWAN) and unstructured SWAN (UNSWAN). The results show some differences among case studies. High resolution wind data affect peak values of significant waves at typhoon periods. In addition, the overestimation of swell caused by typhoons decreased at the nearshore points, in particular at Shimoda by using UNSWAN. As a conclusion, there is little difference between STSWAN and UNSWAN on the overall simulation of wave climate. However, UNSWAN is useful for simulating nearshore waves and has possibility to predict wave climate with higher precision than STSWAN.

© 2018 World Scientific Publishing Co. Pte. Ltd. Theoretical and laboratory studies are performed to analyze the wave attenuation phenomenon over fluid mud under current. In the theoretical part, a semi-empirical formula is derived to model the attenuation process under current. Based on the linear wave theory, the change of wave amplitude is related with the averaged damping effect of the muddy bed. By solving a differential equation, the exponential decay of the wave amplitude is confirmed. A function called damping function is used in the formula, and it is expanded into a series of wave parameters and some undetermined coefficients called auxiliary damping factors. Based on the assumption that the mud properties do not change under current, the formula is combined with the dispersion relation for linear wave under uniform current to describe the attenuation process under current. Laboratory experiments are conducted first without current. The data of wave attenuation are collected and inserted to the formula obtained in the theoretical analysis to figure out the values of the auxiliary damping factors. The second set of experiments is conducted under current and the collected data are compared with the calculated values obtained by using the newly proposed formula with the dispersion relation. The result of comparison shows good applicability of the new formula to the wave attenuation under current.

© 2018 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. The entrainment of debris within inundating flows in extreme hydrodynamic events results in impact loads and other effects that need to be considered in the design of at-risk structures. The analysis of debris impact loads has been performed following field investigations as well as in an experimental setting. The emphasis of this research has primarily been focused on determining the debris impact loads. Additionally, some work has been performed for assessing the risk of debris impact and entrainment characteristics of the debris. This chapter provides a review of the current research on debris motion, impacts and loads, and analyzes existing design guidelines related to debris loads. The chapter presents the current stateoftheart in the field and also provides recommendations for future research.

Following the 2011 Tohoku Earthquake and Tsunami, Japanese tsunami protection guidelines stipulate that coastal defences should ensure that settlements are shielded from the coastal inundation that would result from Level 1 tsunami events (with return periods in the order of about 100 years). However, the overtopping mechanism and leeward inundation heights of tsunami bores as they hit coastal structures has received little attention in the past. To ascertain this phenomenon, the authors conducted physical experiments using a dam-break mechanism, which could generate bores that overtopped different types of structures. The results indicate that it is necessary to move away from only considering the tsunami inundation height at the beach, and also consider the bore velocity as it approaches the onshore area. The authors also prepared a simple, conservative method of estimating the inundation height after a structure of a given height, provided that the incident bore velocity and height are known.

Weather Research and Forecasting atmosphere model and Finite Volume Community Ocean Model were for the first time used under the pseudo-climate simulation approach, to study the parameters of an extreme storm in the Baltic Sea area. We reconstructed the met-ocean conditions during the historical storm Gudrun (which caused a record-high +275 cm surge in Parnu Bay on 9 January 2005) and simulated the future equivalent of Gudrun by modifying the background conditions using monthly mean value differences in sea surface temperature (SST), atmospheric air temperature and relative humidity from MIROC5 in accordance with the IPCC scenarios RCP4.5 and RCP8.5 for 2050 and 2100. The simulated storm route and storm surge parameters were in good accordance with the observed ones. Despite expecting the continuation of recently observed intensification of cyclonic activity in winter months, our numerical simulations showed that intensity of the strongest storms and storm surges in the Baltic Sea might not increase by the end of twenty-first century. Unlike tropical cyclones, which derive their energy from the increasing SST, the extratropical cyclones (ETCs) harvest their primary energy from the thermal differences on the sides of the polar front, which may decrease if the Arctic warms up. For climatological generalizations on future ETCs, however, it is necessary to re-calculate a larger number of storms, including those with different tracks and in different thermal conditions.

海岸保全施設の粘り強さの向上や避難者同士の共助には人的被害の低減効果が期待されるが，減災効果を定量的に評価・比較した事例は少ない．特に海水浴場を対象とした場合には定量的な効果に不明な点が多い．本研究では，地元住民・来訪者に関する既往のアンケート調査を分析し，来訪者の行動を考慮した津波避難モデルを構築した．構築したモデルを由比ガ浜海水浴場に適用し，これらの津波対策効果を定量的に検討した．その結果，防潮堤の粘り強さの向上は人的被害低減に有効だが，防潮堤高が低い場合は効果が小さくなること，また土地勘のない来訪者がいる状況下では避難誘導が有効な対策であることがわかった．さらに，道幅が狭く避難者が多い地域では道路混雑を考慮して避難計画を策定する必要性を示した．

Debris loads during flood events have been well-documented by forensic engineering field surveys of affected communities. Research has primarily focused on debris impact loading and less emphasis has been placed into quantifying the loads and effects associated with debris damming, which occurs when solid objects accumulate at the front of structures. The formation of the debris dam has been shown to results in increased drag forces, backwater rise, and flow accelerations which can influence the stability of the structure. This study examined the formation of a debris dam in steady-state conditions of debris common to flood-prone communities. The study determined that the hydraulic conditions, in particular flow velocity, influenced the formation of the debris dam. Additionally, the study examined the influence of the blockage ratio on the backwater rise as well as the drag coefficient.

This paper presents a methodology for tsunami risk assessment, which was applied to a case study in Kamakura, Japan. This methodology was developed in order to evaluate the effectiveness of a risk-reducing system against such hazards, also aiming to demonstrate that a risk assessment is possible for these episodic events. The tsunami risk assessment follows these general steps: (1) determination of the probability of flooding, (2) calculation of flood scenarios, (3) assessment of the consequences and (4) integration into a risk number or graph. The probability of flooding was approximated based on the data provided by local institutes, and the flood scenarios were modeled in 1D using the Simulating WAves till SHore model. Results showed that a tsunami in Kamakura can result in thousands of casualties. Interventions such as improvements in evacuation systems, which would directly reduce the number of casualties, would have a large influence in risk reduction. Although this method has its limits and constraints, it illustrates the value it can add to existing tsunami risk management in Japan.

An experimental study was performed to examine multiple debris entrainment and transport in tsunami-like flow conditions. The study was performed in the Tsunami Wave Basin at Waseda University. The wave basin used a falling-head driven elongated solitary wave that broke at the edge of a horizontal apron to generate a tsunami-like surge. The debris, modeled as scaled-down (1:40 length scale) 20-foot standard shipping containers, was placed on the horizontal apron. The debris was tracked using a camera-based object tracking algorithm. The study examined the effect of the debris configuration, the number of debris, and orientation of debris on the entrainment and transport within the inundating surge. In examining the transport of multiple debris, the debris tended to be transported within the surge as an agglomeration. Using a previously derived model of debris transport, the study determined experimentally derived coefficients to explain the difference in debris transport between various configurations.

The present study focuses on analysing the state of the tsunami risk communication strategies, awareness and intended evacuation behaviour amongst tourists in Kamakura City, Japan. A mixed methodologies approach was utilized, using key informant interviews, site surveys and questionnaire surveys to understand the risk awareness of this transient group of the population. The results of the survey showed a relatively high risk awareness and willingness to evacuate, though there was some confusion regarding the direction of evacuation, mode of transportation, and location of evacuation areas in the city. A majority of respondents stated that they would expect to be warned of a threat by an official warning or announcement, whereas a minority mentioned social cues as a way to understand what to do, possibly thus requiring changes to the city's risk management strategies. In Japan, the concept of tendenko has been getting more attention since the 2011 Tohoku Earthquake and Tsunami, which calls for each individual to immediately initiate evacuation by himself or herself, requiring the trust that other members of the family and community will be doing the same. Based on these findings the authors outlined a number of recommendations to improve disaster risk management for the case of tourists visiting Kamakura city.

Currently, it is believed that evacuation is the most effective method of protecting lives from tsunamis, in particular after the events of the 2011 Tohoku Earthquake Tsunami. In many coastal areas tsunamis pose a threat not only to local residents, who know the area well, but also to visiting tourists, and thus it is important to consider both these groups when preparing evacuation plans. However, while numerous studies and simulations on tsunami evacuation have been made, research focusing on the influence of visitors on evacuation processes is limited. To clarify this the authors developed an agent-based tsunami evacuation model which considers the different behavior of local residents and visitors, which can estimate the evacuation time, number of individuals reaching each evacuation area, the location of bottlenecks and the number of casualties. The model was applied to study the case of Yuigahama Beach, Kamakura, Japan, with results indicating that the behavior and number of visitors have a significant impact on evacuation processes, especially the location of bottlenecks and the number of casualties. Results also show that heavy congestion will occur during evacuation in places where there are many visitors and thus, in such a situation, the decrease of the moving speed owing to the congestion needs to be appropriately taken into account to simulate the evacuation process. It can be concluded that reducing congestion (i.e., widening roads, guiding visitors to less congested roads) is a crucial countermeasure for a sightseeing location to reduce the casualties that can result from a tsunami.

This study presents the results of an experimental research program dealing with spatial debris motion on a horizontal apron depicting a typical harbor wharf. Accordingly, scaled-down 6.1-m (20-ft) shipping containers were equipped with a novel yet nonintrusive real-time tracking system and motion sensors. The instrumentation allowed for the spatiotemporal tracking of debris specimens moving across the apron while entrained by an incoming tsunami-like broken bore. The system proved its capabilities and accuracy; this was particularly challenging since this was the first time the system was used in water. The experiments involved using various numbers of shipping containers that were either arranged in one layer or stacked in two layers. In addition, the effect of different numbers of container rows was also investigated to study the influence of the overall container count and placement with respect to their longitudinal displacement and dispersion (spreading) across the apron. Linear relationships were derived for both parameters, suggesting potential guidelines for future design efforts and disaster risk reduction and mitigation. (C) 2016 American Society of Civil Engineers.

The authors have examined the characteristics of Typhoon Haiyan (Yolanda), which made landfall on the coast of the Philippines on November 2013, generating a substantial storm surge. In order to better understand the storm surge phenomenon, its nature and severity were analysed by means of a numerical simulation and a field survey. Unlike most other tropical cyclones that weaken before they hit land, Haiyan struck Leyte Island at near peak strength, with maximum sustained wind speeds of 160 knots, the strongest in the recorded history of the Western North Pacific. Haiyan approached very quickly with a forward speed of 41 km/ h towards Leyte, which was also the fastest among typhoons with similar intensities. As a result of these extreme gusts and the exceptionally low central pressure of the typhoon (895 hPa), Haiyan caused the largest storm surge in the recorded history of the Philippines. Numerical simulations show that the maximum storm surges occurred in Leyte Island and Samar Island. A stormsurge field survey conducted by the authors corroborated this, with maximum inundation height of 7 m recorded in Tacloban, located at the northern end of Leyte Gulf. The simulation results also corroborate the fact that water levels at some locations first lowered and then rapidly began to increase after an hour.

東北地方太平洋沖地震の直後，震源から遠く離れた山梨県の湖やノルウェーの湾など複数の場所で津波の様な異常な水位変動が目撃された．同様の水面変動はこれまでに稀に報告されてきた．しかしながら，具体的な波の発生機構や評価手法は確立されておらず，本現象そのものに対する認識や防災意識は低い．本研究では，定量的な影響評価手法の選定と本現象による水害リスクの把握を目的に，現地調査や目撃情報等の収集・整理により発生要因を実地形でのスロッシング現象と推定し，三次元解析での再現を試みた．実験結果との比較により解析手法の妥当性の検証を行った上で過去の事例の再現と将来予測を行った．その結果，本解析手法により異常な水面変動を再現できること，津波とは別の地震直後の内陸部の湖や湾奥部の運河における水害リスクを明らかにした．

On 11 March 2011, an exceptionally large tsunami event was triggered by a massive earthquake offshore, the northeast coast of Japan, which affected coastal infrastructure such as seawalls, coastal dikes and breakwaters in the Tohoku region. Such infrastructure was built to protect against the Level 1 tsunamis that previously hit the region, but not for events as significant as the 2011 Tohoku tsunami, which was categorized as a Level 2 tsunami [Shibayama, T., Esteban, M., Nistor, I., Takagi, H., Thao, N. D., Matsumaru, R., Mikami, T., Aranguiz, R., Jayaratne, R. & Ohira, K. [2013] "Classification of tsunami and evacuation areas," Nat. Hazards 67(2), 365-386]. The failure mechanisms of concrete-armored dikes, breakwaters and seawalls due to Level 2 tsunamis are still not fully understood by researchers and engineers. This paper investigates the failure modes and mechanisms of damaged coastal structures in Miyagi and Fukushima Prefectures, following the authors' post-disaster field surveys carried out between 2011 and 2013. Six significant failure mechanisms were identified for the coastal dikes and seawalls affected by this tsunami: (1) Leeward toe scour failure, (2) Crown armor failure, (3) Leeward slope armor failure, (4) Seaward toe scour and slope armor failure, (5) Overturning failure, and (6) Parapet wall failure, in which leeward toe scour being recognized as the major failure mechanism in most surveyed locations. The authors also propose a simple practical mathematical model for predicting the scour depth at the leeward toe of the coastal dikes, by considering the effects of the tsunami hydrodynamics, the soil properties and the type of structure. The key advantage of this model is that it depends entirely on quantities that are measurable in the field. Furthermore this model was further refined by conducting a series of hydraulic model experiments aimed to understand the governing factors of the leeward toe scour failure. Finally, based on the results obtained, key recommendations are given for the design of resilient coastal defense structures that can survive a level 2 tsunami event.

Flood disasters such as dam breaks and surges from extreme hurricanes or tsunamis entrain and transport substantial amounts of submerged or floating debris. Understanding of motion and spatiotemporal distribution of debris entrained by a flood is thus of great importance to hydraulic, coastal, and structural engineers; the displacement of debris to a location where it may eventually impact critical infrastructure requires scientific attention at the laboratory scale first. In this context, the design and application of a novel smart debris system utilizing off-the-shelf components is presented and discussed. The system tracks the spatial location and orientation of a multitude of debris specimens and it proposes an accurate tool to assess their individual trajectory, velocity, and momentum in a laboratory environment. Contrary to the traditional camera-based approach of video tracking, which often fails once objects are submerged, the proposed smart debris system delivers six-degree-of-freedom (6DOF) data in a reliable, timely manner. Miniaturized inertial measurement units (IMU), commonly called motion sensors, which are used for attitude heading reference systems are deployed to output time series of spatial orientation along with filtered 3D acceleration readings. A Bluetooth low-energy (BLE) tracking system is applied along with the motion sensor to track the 3D debris positions. A detailed investigation in controlled laboratory conditions reveals the detailed individual performance of the tested spatial orientations and positions. As an application, debris transport tests were conducted in a newly built tsunami wave basin at Waseda University in Tokyo, Japan. For this test series, a typical harbor layout with a vertical quay wall adjacent to a horizontal container-stacking platform was constructed. The advection by a broken tsunamilike bore of multiple down-scaled shipping containers in basic arrangements was then tracked from their initial position. The performance of the innovative smart debris system is qualitatively tested in order to provide guidance for their future application in hydraulic and coastal engineering as well as to provide a solid basis for its application in field studies. (C) 2016 American Society of Civil Engineers.

Experimental research was conducted focusing on debris motion over a horizontal apron featuring vertical obstacles in the path of the debris propagation. The apron was designed as a typical representation of a harbor threatened by an inundating tsunami. The experimental setup idealized often complex harbor settings. The debris was a scaled-down 20-foot shipping container modelled at a 1 in 40 Froude length scale. Offand onshore regions were separated by a vertical quay wall which allowed the incoming elongated solitary wave used to represent the first part of a tsunami to steepen, break and propagate over the initially dry surface as a tsunami-like bore. In the path of propagation, a varying number of debris were entrained within the inundating bore over the horizontal apron. The entrained debris interacted with regularly spaced vertical obstacles representing infrastructure and houses within the propagation path. Varying debris and obstacle arrangements were tested to evaluate the effects the obstacles would have on the debris' maximum longitudinal displacement and the spreading angle. The main conclusion is that the spreading angle of the debris is not as significantly altered by the presence of obstacles on the harbor apron whereas the maximum longitudinal displacement of the debris was significantly affected. (C) 2016 Published by Elsevier B.V.

The present work evaluates potential future typhoon and storm surges around the islands of Samar and Leyte in the Philippines taking into account monthly mean sea surface temperatures, atmospheric air temperature, and relative humidity (hereafter, SST, AAT, and RH) from MIROC5 according to four scenarios proposed by IPCC AR5. Super-typhoon Haiyan (2013), which caused catastrophic damage to coastal areas in the Philippines due to its high winds and storm surge, was used as the case study storm given that it was one of the tropical cyclones recorded in modern history. In this study, the Advanced Research Weather Research and Forecasting Model (ARW-WRF) is used to estimate the characteristics of both the present-day Haiyan and a typhoon with a similar return period under the climate condition of the year 2100. The unstructured, Finite Volume Community Ocean Model (FVCOM) was used to estimate both the present and potential future storm surges. The research has two main focuses. First, both the historical event and its storm surge are simulated and contrasted with field measurements of the storm surge height in order to prove the accuracy of the model. Second, the future typhoon and storm surge are estimated using the monthly mean value differences in SST, AAT, and RH from MIROC5 between 2011-2020 and 2091-2100 for the different scenarios. The characteristics of the simulated typhoon route and storm surge heights agree well with those of the best track data and field measurements. The numerical results of the future typhoon show that, if climate change is considered to only increase SST, its intensity and storm surge will be larger than under the present climate. The minimum sea-level pressure (hereafter, MSLP) of the future typhoon under scenario RCP 8.5 would be about 21 hPa lower and the storm surge 2.7 m higher than in the present climate. However, if SST, AAT, and RH are also taken into account, then the increase in typhoon intensity will not be as marked as if only SST is considered, with the MSLP under RCP 8.5 decreasing only by 13 hPa and the storm surge increasing by 0.7 m. The results of the present research thus suggest that while increases in SST can contribute to the intensification of future typhoons, increases in AAT and RH will somehow moderate this effect. Nevertheless, all scenarios considered point out to stronger typhoons and higher storm surges, clearly highlighting the perils posed by future climate change.

Typhoon Haiyan (Yolanda) struck the islands of Leyte and Samar, the central part of the Philippines, on 8 November 2013, bringing large-scale devastation to coastal areas due to the high winds and large storm surge and waves associated with it. In order to obtain the distribution of storm surge heights and damage covering the wide stretch of affected coastline, the authors carried out a series of field surveys in the aftermath of the typhoon (in December 2013, May 2014, and October 2014). In the present paper, the authors detailed the results of these field surveys and summarized the characteristics of the storm surge and main causes of the damage, especially focusing on the Leyte Gulf coast, which is surrounded by the eastern coast of Leyte and the southern coast of Samar. Finally, the wide range of types of storm surge disasters were also discussed by comparing Typhoon Haiyan with other recent major events.

Category 5 Typhoon Haiyan was one of the strongest typhoons to hit the Philippines in modern times, and introduced the term "storm surge" to the vocabulary of many local residents, who had not heard about such phenomena prior to this event. The storm surge manifested itself on the 8th November 2013 as Haiyan made landfall, devastating large areas in the islands of Leyte and Samar. To attempt to gain an understanding of the level of awareness that local residents had about storm surges the authors conducted structured questionnaires (n = 172) and focus group interviews with local residents, and discussed the results obtained with key informants (government officers and disaster risk managers). One of the key problems identified during the interviews was how people were not able to clearly understand the concept of a storm surge, with many respondents emphasizing how it would have been better for authorities to describe it as a "tsunami". A discussion is also made on the recent evolution in world-wide coastal disaster awareness, comparing it to recent developments in storm surge awareness in the Philippines and other countries in the area, such as Vietnam and Japan. The authors conclude that, in terms of its influence on worldwide disaster awareness, typhoon Haiyan constitutes an event of similar importance to major recent high-impact tsunami events such as the 2004 Indian Ocean and 2011 Tohoku events. As a result, the authors will outline a number of lessons learnt from Haiyan, such as the necessity for creating multi-layer safety strategies and improving how information about storm surges is transmitted to local residents.

The present paper examines the impact of floodwater caused by the storm surge brought about by Typhoon Haiyan in 2013, focusing on downtown Tacloban in Leyte Island, the Philippines. A reliable numerical model for predicting such flooding was developed by calibrating the results of field investigations, including footage from a video clip taken during the storm surge. The simulation reveals that flow velocities along the streets in downtown Tacloban reached up to 7 m/s due to flow contraction along the high-density blocks of houses, and how water levels reached their peak in just 10 min. According to the depth-velocity product criteria, often used for evaluating the vulnerability of people and buildings to floodwaters, only 8% of the length of streets in downtown Tacloban were within the safe limits that allow pedestrian evacuation. Based on these findings, the present research concludes that pedestrian evacuation in the middle of a storm surge generated by a strong typhoon is a high-risk behavior. Thus, clearly and objectively, evacuation during this time should not be encouraged, even when seawater intrudes the houses of local residents. In this respect, it would appear imperative that prior to the arrival of the typhoon all residents should evacuate areas at risk of being flooded. Though the flood height was significant in the downtown area, the damage to these houses was limited. If it was not possible for some reason to evacuate prior to the arrival of the typhoon, those in solid houses should first consider vertical evacuation and the possibility that they could survive in their place, rather than courageously evacuating in an unpredictable water flow. (C) 2015 Elsevier B.V. All rights reserved.

気候変動後の具体的変化として想定される海水面温度（SST），対流圏及び成層圏の気温（TAT，SAT），相対湿度（RH）の変化が，台風とその高潮の強度に与える影響を評価した．CMIP5・RCP8.5シナリオにおけるアンサンブル平均SST，TAT・SAT，RHの将来変化量を独立に加味した疑似気候変動場で，メソ気象モデルを用いて台風を数値計算し，その結果を外力として高潮を算定した．先行研究と同様にSSTの上昇は台風・高潮強度を増加させた．一方でTAT・SATの変化は台風・高潮強度に負の影響を与えること，RHの変化は台風・高潮強度への影響が少ないことを数値モデルで明らかにした．TAT・SATの変化を考慮したケースでは，台風下の潜熱フラックスが減少していた．さらに，SSTが高く，TATが低い大気・海洋物理場は，台風・高潮強度を増加させる潜在的可能性があることを明らかにした．

2011年3月11日東日本大震災が発生し，甚大な津波被害をもたらした．この時気仙沼では津波に流された石油タンクから油が流出する事故が発生した．本研究では，東京湾における津波に対する石油タンクの安全性を評価し，流出する油の移流拡散挙動を明らかにすることを目的とした．慶長地震を想定した津波数値解析の結果，石油タンクへ津波が到達するのは地震発生後95分，最大浸水深は約2.3 mであった．被害を受けるのは貯蔵率が20 %未満の石油タンクのみであった．津波によって流出する油の量の期待値は約5000 klであった．油の移流拡散予測では，油の挙動に与える外力の影響評価を行った．計算結果より，風向，風速が与える影響は大きく，揮発の影響は相対的に小さいことがわかった．

Sea level rise and an increase in typhoon intensity are two of the expected consequences from future climate change. In the present work, a methodology to change the intensity of tropical cyclones in Japan was developed, which can be used to assess the inundation risk to different areas of the country. As a result, the probability of a storm with an equivalent return period in the year 2100 to that of the worst storm in the 20th century overcoming sea defences around Tokyo Bay could be calculated. The risk of higher storm surges, coupled with different sea-level-rise scenarios, highlights how the dykes around Tokyo or Kawasaki could fail unless adaptation measures against climate change are attempted. The cost of adapting to both of these effects by building higher coastal dykes and raising port areas outside them was quantified. Finally, an estimation of the cost of allowing the areas behind the defences to be flooded was also made, clearly showing that the cost of adaptation measures is clearly lower than the cost of inaction.

© 2015, Springer-Verlag Berlin Heidelberg. The dissipation of irregular waves passing over muddy beds is investigated through two series of wave flume laboratory experiments with and without currents, where commercial kaolinite is used as the muddy sediment bed material. The changes in spectral characteristics of waves along the muddy bed and the effects of following and opposing currents are investigated. A numerical multi-layered model was also employed to simulate the attenuation of regular/irregular waves assuming viscoelastic rheological behavior for fluid mud, and the outputs were compared with the laboratory data. The first series of the experiments show that propagation of a wave spectrum over a short fluid mud section does not result in a shift in peak frequencies of wave spectra. The comparisons of spectral width parameters of various wave spectra also reveal that higher values of spectral peakedness parameters generally result in higher rates of wave energy dissipation. This can be related to the frequency dependency of wave energy dissipation on the mud layer. The results of the second series of experiments show higher dissipation rates in the opposing current and lowe

The world's population is expected to increase to over 8 billion by 2020. About 60% of the total population of the world lives in coastal areas and 65% of the cities with a population of over 2.5 million are located in coastal areas. Written by an international panel of experts in the fields of engineering and risk management, The Handbook of Coastal Disasters Mitigation presents a coherent overview of 10 years of coastal disaster risk management and engineering, during which some of the most relevant events of recent time have taken place, including the Indian Ocean tsunami, hurricanes Katrina and Sandy in the United States or the 2011 Japanese tsunami. International case studies offer practical lessons on how disaster resilience can be improved in the future. Contains tools and techniques for analyzing and managing the risk of coastal disasters. Provides engineering measures for mitigating coastal vulnerability to tsunamis, tropical cyclones, and hurricanes. Includes crucial tactics for rehabilitation and reconstruction of the infrastructure.

The breaking-limited (or depth-limited) approach is a traditional method to determine the maximum possible wave height for the design of coastal structures in the surf zone. It is well recognized that the maximum wave height in the surf zone is limited by wave breaking. The maximum possible wave height is usually determined from a breaker height formula. The present study was undertaken to examine the applicability of 14 existing breaker height formulas for computing the maximum possible wave heights. The existing breaker height formulas were examined against measured regular and irregular wave heights. A total of 17 863 data points from 30 sources of published experimental data were used to examine the formulas. The experiments cover a wide range of wave and bottom topography conditions including small-scale, large-scale, and field experiments. It was found that the errors of existing formulas for regular and irregular waves have the same tendency. The existing formulas give considerable underestimation of the maximum possible wave heights in shallow water. The top three formulas were modified by including a new form of relative depth into each formula. Overall, the modified formulas give a considerable better estimation than those of existing formulas.

© 2015 World Scientific Publishing Company and Japan Society of Civil Engineers. The breaking-limited (or depth-limited) approach is a traditional method to determine the maximum possible wave height for the design of coastal structures in the surf zone. It is well recognized that the maximum wave height in the surf zone is limited by wave breaking. The maximum possible wave height is usually determined from a breaker height formula. The present study was undertaken to examine the applicability of 14 existing breaker height formulas for computing the maximum possible wave heights. The existing breaker height formulas were examined against measured regular and irregular wave heights. A total of 17 863 data points from 30 sources of published experimental data were used to examine the formulas. The experiments cover a wide range of wave and bottom topography conditions including small-scale, large-scale, and field experiments. It was found that the errors of existing formulas for regular and irregular waves have the same tendency. The existing formulas give considerable underestimation of the maximum possible wave heights in shallow water. The top three formulas were modified by including a new form of relative depth into each formula. Overall, the modified formulas give a considerable better estimation than those of existing formulas.

The effect of a thin fluid mud layer on nearshore two-dimensional wave transformation is studied through numerical modeling and wave basin experiments. The wave basin experiments were conducted on both muddy and fixed beds. A mixture of commercial kaolinite and tap water was used as fluid mud layer, where its rheological viscoelastic parameters were derived from rheometer cyclic tests. The results can be utilized for better understanding of the complex wave transformation phenomena under real field conditions where the combined effects of shoaling, refraction, and diffraction as well as wave energy dissipation due to existing mud beds and wave breaking jointly occur. A dissipation model was coupled to the combined refraction and diffraction 1 (REF/DIF 1) wave model to develop a numerical wave height transformation model for muddy beaches. The proposed model was utilized to analyze the experimental data on muddy beds. Comparing the computed values of wave heights over mud layer with the corresponding measurements shows a fair agreement.

In this chapter, the authors describe the most signifi cant consequences of a potential increase in typhoon strength and sea level rise to Japanese port infrastructure, though particular emphasis will be placed on the ports in Tokyo Bay (see Figure 9.1), given the disproportionate impact that they have on the country’s economy. Also, a rough economic analysis of the cost of raising port areas in Tokyo Bay will be outlined, which can serve to quantify the magnitude of this aspect of the problem. The Port of Tokyo alone is one of the largest in the Japan and the entire Pacifi c Ocean basin, with an annual capacity of around 100 million tonnes of cargo and 4.5 million TEUs,1 serving 32,000 ships a year and employing 30,000 employees.

2011年東北地方太平洋沖地震津波では，陸地への浸水を防ぐ海岸堤防が多数破壊され被害が拡大した．現地調査より，堤防の主たる破壊原因は，津波が堤防を長時間越流することによって引起こされた洗掘であると考えられる．さらに，堤防被害や洗掘規模と堤防背後の防潮林被害の関係から，堤防とその周辺の状況が，堤防被害に影響を及ぼす可能性があることが分かった．そこで本研究では，海岸堤防を越流する津波に対して防潮林が与える影響を水理実験により検討した．その結果，防潮林により堤防背後に流下する津波が射流から常流へと変化することが分かった．堤防裏法尻部に流下する流速が4割低減され，また堤防裏法肩部に作用する負圧が低減されることが分かった．以上より，背後に防潮林を有することで堤防周囲で生じる津波の挙動が変化し，越流する津波による堤防への被害を軽減し得ることが分かった．

東日本大震災時において，仙台平野沿いに流れる貞山運河を境に津波高さの減少が見られた．本研究では，運河の津波減衰効果を明らかにすることを目的として，現地調査結果の分析および水理実験を行った．現地調査結果の分析から，複数の地点において貞山運河による津波減衰効果を確認することができた．水理実験ではチャンバー式平面津波水槽を用いた．運河の津波減衰効果を明らかにするため，運河模型を越えた越流量に注目した．実験は津波高さ，長さ，運河内水深を変化させて行った．水理実験から運河に越流量を減衰させる効果があることが判明した．また，同一の断面では運河内水深を浅くするほど越流量は減少することや波形によっても越流量は変化することが確認できた．

神奈川県三浦半島の相模湾岸に位置する秋谷海岸では，平成10年代から海岸侵食が顕在化したために，平成19年から8年間にわたって92,600m&lt;sup&gt;3&lt;/sup&gt;の中央粒径15mmの礫を用いた養浜を行った．礫養浜工法の選択は，4年間に及ぶ地元での合意形成会議の議論に基づいて行われている．礫養浜の進行に伴い，地形，底質，生物の各項目について，モニタリングを行っている．モニタリング結果を用いて合意形成会議において順応的な管理方法について話し合いを行い，部分的な手直しを行ってきた．8年を経て，礫浜は岸沖方向には安定しているが，沿岸方向には礫の分布が広がりつつあり，両端部での礫移動の管理方法が課題となっている．

Storm surges are one of the most important risks to coastal communities around the Bay of Bengal, and it is feared that the threat they pose will increase with climate change in the future. To understand the threats that these events pose, a summary of the field surveys performed in Yangon River Basin after cyclone Nargis in Myanmar in 2008 is presented. Though due to government restrictions survey activities were limited to the area near Yangon city, it was found out that the tide due to the storm surge was probably between 3 and 4 m high and travelled around 50 km upstream of the river mouth of Yangon River. Cyclone Nargis could be accurately reproduced using a numerical model that integrated weather, wave, coastal ocean models, and tide prediction system. The application of such an integrated model is relatively new for storm surge simulation and has never been used for the Bay of Bengal storms. The model was then used to also simulate future cyclones over the Bay of Bengal considering a future climate change scenario.

Developing an accurate and reliable time-averaged beach profile evolution model under storm and nonstorm conditions is a challenging task. Over the last few decades, a number of beach deformation models have been developed under limited experimental conditions and uncertainties, and sometimes they required a long computation time. It is quite evident that a large amount of wave, current, sediment and beach profile data is available today. The present study leads to the development of a simple two-dimensional beach profile evolution model with on-offshore sand bar formation under nonstorm and storm conditions based on the time-averaged suspended sediment concentration models of Jayaratne and Shibayama [Jayaratne, M. P. R. and Shibayama, T. [2007] "Suspended sediment concentration on beaches under three different mechanisms," Coastal Eng. J., JSCE 49( 4), 357-392.] and Jayaratne et al. [Jayaratne, M. P. R., Sritharan, S. and Shibayama, T. [2011] "Examination of the suspended sediment concentration formulae using full-scale rippled bed and sheet flow data,"Coastal Eng. J., JSCE 53(4), 451-489.]. These models were formulated for computing sediment concentration in and outside the surf zone under three different mechanisms: (1) suspension due to turbulent motion over sand ripples, (2) suspension from sheet flow layer and (3) suspension due to turbulent motion under breaking waves. The suspended load is calculated by the product of time-averaged sediment concentration and undertow velocity from edge of the wave boundary layer to wave trough and mass transport velocity from wave trough to crest (bore-like wave region). Sediment transport in wave boundary layer is computed from the modified Watanabe [Watanabe, A. [1982] "Numerical model of nearshore currents and beach deformation model,"Coastal Eng. Jpn., JSCE 25, 147-161.] model. Rattanapitikon and Shibayama [Rattanapitikon, W. and Shibayama, T. [1998] "Energy dissipation model for regular and irregular breaking waves,"Coastal Eng. J., JSCE 40(4), 327-346.] wave model is used to calculate the average rate of energy dissipation due to wave breaking. The beach deformation is calculated from the conservation of sediment mass while the avalanching concept of Larson and Kraus [Larson, M. and Kraus, N. C. [1989] SBEACH: Numerical model for simulating storm induced beach change, Report 1, Technical Report CERC-89-9, US Army Eng. Water. Exp. Station.] is used to re-distribute the sediment mass in neighboring grids for a steady solution. Published field-scale experimental and natural beach profiles from five high-quality data sources from 1983-2009 [Kajima et al., 1983; Kraus and Larson, 1988; Port and Airport Research Institute, Japan, 2005, 2009; Hasan and Takewaka, 2007, 2009; Ruessink et al., 2007] are used to verify the performance of the proposed numerical model. The key feature in this process-based model is that it takes about a couple of minutes to simulate beach profiles of a 2-3 days storm qualitatively at a fairly satisfactory level using a standard personal computer. It is found that the present numerical predictions are not better than the null hypothesis as the model is in a stage of ongoing development.
Therefore, it is believed that the final model is often of more value to a practical coastal engineer than a very detailed study of hydrodynamics and sediment transport study, however an incorporation of swash dynamics, more precise evaluation of offshore sand bar formation and continuation to a longer time scale with precise beach deformation are recommended as the next stage of the model.

© 2014 World Scientific Publishing Company and Japan Society of Civil Engineers. Developing an accurate and reliable time-averaged beach profile evolution model under storm and nonstorm conditions is a challenging task. Over the last few decades, a number of beach deformation models have been developed under limited experimental conditions and uncertainties, and sometimes they required a long computation time. It is quite evident that a large amount of wave, current, sediment and beach profile data is available today. The present study leads to the development of a simple two-dimensional beach profile evolution model with on-offshore sand bar formation under nonstorm and storm conditions based on the time-averaged suspended sediment concentration models of Jayaratne and Shibayama [Jayaratne, M. P. R. and Shibayama, T. [2007] &quot;Suspended sediment concentration on beaches under three different mechanisms,&quot; Coastal Eng. J., JSCE 49(4), 357-392.] and Jayaratne et al. [Jayaratne, M. P. R., Sritharan, S. and Shibayama, T. [2011] &quot;Examination of the suspended sediment concentration formulae using full-scale rippled bed and sheet flow data,&quot; Coastal Eng. J., JSCE 53(4), 451-489.]. These models were formulated for computing sediment concentration in and outside the surf zone under three different mechanisms: (1) suspension due to turbulent motion over sand ripples, (2) suspension from sheet flow layer and (3) suspension due to turbulent motion under breaking waves. The suspended load is calculated by the product of time-averaged sediment concentration and undertow velocity from edge of the wave boundary layer to wave trough and mass transport velocity from wave trough to crest (bore-like wave region). Sediment transport in wave boundary layer is computed from the modified Watanabe [Watanabe, A. [1982] &quot;Numerical model of nearshore currents and beach deformation model,&quot; Coastal Eng. Jpn., JSCE 25, 147-161.] model. Rattanapitikon and Shibayama [Rattanapitikon, W. and Shibayama, T. [1998] &quot;Energy dissipation model for regular and irregular breaking waves,&quot; Coastal Eng. J., JSCE 40(4), 327-346.] wave model is used to calculate the average rate of energy dissipation due to wave breaking. The beach deformation is calculated from the conservation of sediment mass while the avalanching concept of Larson and Kraus [Larson, M. and Kraus, N. C. [1989] SBEACH: Numerical model for simulating storm induced beach change, Report 1, Technical Report CERC-89-9, US Army Eng. Water. Exp. Station.] is used to re-distribute the sediment mass in neighboring grids for a steady solution. Published field-scale experimental and natural beach profiles from five high-quality data sources from 1983-2009 [Kajima et al., 1983; Kraus and Larson, 1988; Port and Airport Research Institute, Japan, 2005, 2009; Hasan and Takewaka, 2007, 2009; Ruessink et al., 2007] are used to verify the performance of the proposed numerical model. The key feature in this process-based model is that it takes about a couple of minutes to simulate beach profiles of a 2-3 days storm qualitatively at a fairly satisfactory level using a standard personal computer. It is found that the present numerical predictions are not better than the null hypothesis as the model is in a stage of ongoing development. Therefore, it is believed that the final model is often of more value to a practical coastal engineer than a very detailed study of hydrodynamics and sediment transport study, however an incorporation of swash dynamics, more precise evaluation of offshore sand bar formation and continuation to a longer time scale with precise beach deformation are recommended as the next stage of the model.

On October 25, 2010, a large earthquake occurred off the coast of the Mentawai islands in Indonesia, generating a tsunami that caused damage to the coastal area of North Pagai, South Pagai, and Sipora islands. Field surveys were conducted soon after the event by several international survey teams, including the authors'. These surveys clarified the tsunami height distribution, the damage that took place, and residents' awareness of tsunamis in the affected islands. Heights of over 5 m were recorded on the coastal area of the Indian Ocean side of North and South Pagai islands and the south part of Sipora island. In some villages, it was difficult to evacuate immediately after the earthquake because of the lack of routes to higher ground or the presence of rivers. Residents in some villages had taken part in tsunami drills or education; however, not all villages shared awareness of tsunami threats. In the present paper, based on the results of these field surveys, the vulnerability of these islands with regards to future tsunami threats was analyzed. Three important aspects of this tsunami disaster, namely the geographic disadvantage of the islands, the resilience of buildings and other infrastructure, and people's awareness of tsunamis, are discussed in detail, and corresponding tsunami mitigation strategies are explained.

The last great earthquake in northern Chile took place in 1877, and the ensuing tsunami affected not only that region but also Central Chile. For example, the Bay of Concepcin, which is located 1,500 km south of the tsunami source, experienced an inundation height of around 3 m. Ports are important in the Chilean economy, due to the fact that a large percentage of Chilean exports (excluding copper) use ports located in Central Chile. With this in mind, the authors investigated the potential effect of an 1877-like tsunami on the main ports of Central Chile. To do this, the dispersive wave model Non-hydrostatic Evolution of Ocean WAVEs was used. In addition, the first tsunami forecast model for Talcahuano, inside the Bay of Concepcin, was developed by means of numerical simulation of several events of different moment magnitudes. The results showed that most of the important ports (Valparaiso, San Antonio, San Vicente and Coronel) had inundation heights on the order of just 1 m, while inundation levels in Talcahuano reached up to 3.5 m. The forecast model for Talcahuano uses only earthquake magnitude, focal depth and tide level to determine tsunami inundation heights. In addition, the tsunami arrival time was computed to be 3 h, and the maximum tsunami amplitude takes place at 4 h and 45 min after the earthquake.

The aims of this study are to examine the reproducibility of new Meteorological-Surge-Tide coupled model and to estimate the effect of global warming to storm surge. In order to examine the model, the case of typhoon Roke (2011) is taken to be an example since the sea level elevation in this case is the highest record in Tokyo Bay during recent 10 years. For the case of typhoon Roke, the tendency of time history of water level is well reproduced though the maximum value is underestimated. The future case of typhoon Roke is also calculated. The sea level at Shibaura is increased for around 20cm and it is also increased around 40cm at Funabashi. These results imply that the coupled model has good performance but there are still some differences of sea level at Tokyo Bay due to the effect of complex geography.

The catastrophic typhoon "Yolanda" on Nov. 2013 invoked storm surge in the coastal area of the Philippines. The storm surge made the coastal regions to the devastation and maximum water height reached 5m in the Tacloban area. This paper presents the comparison between storm surge simulated results from atmospheric - storm surge- wave- tide coupled model and the observation measured by The 2013 Philippines Storm Surge Joint Survey Group headed up by Prof T. Shibayama. In this study, the TC-Bogus scheme is used in order to simulate accurate typhoon. The simulated storm surge results reached almost 5m in the Tacloban area. The coupled model including TC-Bogus scheme gives accurate simulations for estimating storm surge.

At 14:46 local time on March 11, 2011, a magnitude 9.0 earthquake occurred off the coast of northeast Japan. This earthquake generated a tsunami that struck Japan as well as various locations around the Pacific Ocean. With the participation of about 300 researchers from throughout Japan, joint research groups conducted a tsunami survey along a 2,000 km stretch of the Japanese coast. More than 5,200 locations have been surveyed to date, generating the largest tsunami survey dataset in the world. The inundation height and run-up height were surveyed by laser, GPS, and other instruments, and the tidal correction has been accurately adjusted using a tidal database and a numerical simulation for Tohoku, an area where tide gauges were destroyed by the tsunami. Based on the survey dataset, the regional and local scale analyses were conducted to understand the basic characteristics of this event. Maximum run-up heights greater than 10 m are distributed along 500 km of coast in direct distance. The affected area of this event was several times larger than historically recorded in Tohoku. The mean inundation height in the southern Sanriku region is 1015 m and there are several peaks of inundation along the coast from the northern to middle part of Sanriku. © 2012 World Scientific Publishing Company and Japan Society of Civil Engineers.

Recently, major tsunami events have resulted in considerable damage to low-lying coastal developments as well as significant loss of life. This is owing to the fact that coastal communities and associated infrastructure are not able to withstand the extreme hydrodynamic forces induced by the overland progression of large tsunami waves. This paper reports the findings of a study, which is part of an ongoing comprehensive (hydraulic-structural engineering) research program initiated at the University of Ottawa in Canada. The goals of the latter are to contribute to the understanding and quantification of extreme hydrodynamic impacts on structural elements, and to the development of design guidelines for structures located in tsunami-prone areas. In this study, a single-phase three-dimensional (3D) weakly compressible smoothed-particle hydrodynamics (WCSPH) model is used to investigate the hydrodynamic forces, induced by the impact of rapidly advancing tsunami-like hydraulic bores, on a freestanding column of a square cross section. Numerical time histories of the water surface elevation and net base horizontal force acting on the column are compared with the results of large-scale physical experiments, conducted by the authors as part of an experimental component of this research program. The experiments were performed on the basis of analogies between tsunami bores and dam-break waves. The bore-structure interaction is analyzed in detail as the validated numerical model is subsequently applied to additionally investigate the influence of laboratory channel geometry on the results. (C) 2014 American Society of Civil Engineers.

The design of breakwater armor units against tsunami attacks has received little attention in the past because of the comparative low frequency of these events and the rarity of structures designed specifically to withstand them. However, field surveys of recent events, such as the 2011 Tohoku Earthquake Tsunami and the Indian Ocean tsunami in 2004, have shown flaws in the design of protection structures. During these extreme events, many breakwaters suffered partial or catastrophic damage. Although it is to be expected that most normal structures fail because of such high-order events, practicing engineers need to possess tools to design certain important breakwaters that should not fail even during Level 2 events. In the future, research into the design of critical structures that only partially fail (i.e., resilient or tenacious structures) during very extreme Level 2 tsunami events should be a priority
in this sense, the present paper proposes a formula that allows the estimation of armor unit damage depending on the tsunami wave height. © 2014 American Society of Civil Engineers.

The 2010 Chile tsunami had different effects along the Chilean coast. Seawater surged hundred meters into many rivers, though field surveys showed that the 2 km wide Biobio River did not experience any flooding. In a similar manner, the coastal zones south of the river had an inundation height of less than 2m. To ascertain why these areas were not greatly affected by the event, the behavior of tsunami waves propagating over a submarine canyon was investigated by means of numerical simulations over a simplified and idealized bathymetry. The main variables which define the size of the canyon were varied, and three different tsunami wave lengths were tested. The results show that submarine canyons have a strong influence on tsunami propagation and run-up such that there is a spatial variation of wave amplitude along the coast and this behavior is very sensitive to the canyon size. The run-up directly behind the canyon is lower than in the case without the canyon, while there are zones of wave amplification at both sides of the canyon. These idealized results compare well with what happened during the 2010 Chile tsunami, and provide a useful insight into the behavior of tsunamis around other submarine canyons in other regions of the world.

Since the 2004 Indian Ocean Tsunami, there is a growing awareness of the risks that tsunamis pose to coastal communities. Despite the fact that the population of some countries such as Chile and Japan were aware of such events, many other places had virtually not heard about such phenomenon before 2004. Nevertheless, the frequent reoccurrence of major tsunamis in recent years has led to a heightened state of tsunami awareness in many areas of the world, which can be described by an increased knowledge, disaster preparedness and willingness of local populations to evacuate when the threat of these events arises. However, the response of different elements of society to tsunami warnings nowadays still appears to be inadequate a times, pointing to lack of awareness by at least some individuals, an over-reliance in defence mechanisms or lacking in the transmission of knowledge from previous events. This paper will explore these cultural issues using as a basis observations made by the authors during field visits to areas afflicted by the last three major events (Chile, Indonesia, and Japan). The level of tsunami awareness prior to these events will be explored through an analysis on the existence of multiple layers of safety against tsunami developed by previous generations, and whether these had been preserved over time. The potential impact of these major tsunamis in the development of tsunami awareness will be analysed based on questionnaires that indicate the willingness of local coastal communities to invest in disaster preparedness. (C) 2013 Elsevier Ltd. All rights reserved,

The present study concentrates on the empirical formulas of Goda [1975, 2009]. The formulas were proposed for computing the transformation of three common representative wave heights (i.e. H-1/3, H-max and H-m0) on plane beaches. The objectives of the present study are to verify the Goda formulas for computing the transformation of H-1/3, H-max and H-m0 on unbarred beaches and to extend the formulas for computing the transformation of H-m, H-rms and H-1/10. Laboratory data from small-scale and large-scale wave flumes with unbarred beach conditions are used to verify the formulas. The verification shows that the formulas give very good predictions of H-1/3 and H-m0, but give fair prediction of H-max. The formulas are rewritten in the form of a general formula. The general form of Goda formulas is recalibrated and extended to compute other representative wave heights (i.e. H-m, H-rms and H-1/10). The general formula gives very good predictions of H-m, H-rms, H-1/3, H-1/10, H-max and H-m0.

On March 11, 2011, a large earthquake that occurred offshore the north-east coast of Japan generated a large tsunami which devastated extensive areas of the Tohoku coastline. Despite Japan being considered a country well prepared for these types of disasters, large casualties were recorded, with numerous discussions amongst the Japanese coastal engineering community ensuing. As a result, two different levels of tsunamis have been proposed and now recognized in Japan, depending on the frequency of such extreme events. The idea that hard measures can protect the lives of inhabitants of coastal areas has been abandoned, and these measures are only considered to be effective in protecting properties against the more frequent but lower magnitude events. Soft measures should always be used to protect against the loss of lives, and to this respect, the authors of the paper propose the introduction of a Classification of Evacuation Areas, to show which of these should be prioritized by residents as they seek to evacuate.

Since 2004 there is a growing global awareness of the risks that tsunamis pose to coastal communities. Despite the fact that these events were already an intrinsic part of the culture of some countries (such as Chile and Japan), in many other places they had been virtually unheard of before 2004. Nevertheless, the frequent reoccurrence of these events in recent years has led to the emergence of a "tsunami culture" in many areas of the world, which has resulted in increased awareness, disaster preparedness and willingness of local populations to evacuate when the threat of these events arises. This paper will explore these cultural issues using as a basis questionnaires carried out by the authors during their own field visits to the last three major events (in Japan, Chile and Indonesia), and interpret these through the willingness of coastal communities to build protection measures along the shore and the impact that these can have on sustainable development. (C) 2013 The Authors. Published by Elsevier B.V.

Sea level rise could threaten the stability of rubble mound breakwaters in the future, as greater water depth will allow larger waves to reach these structures. Particularly worrying, however, is the prospect of an acceleration in the pace of sea level rise as a result of climate change, especially after 2050. This could lead to a change in the philosophy behind the design of breakwaters and ports, leading to substantial increases in the cost to build and maintain these costly structures. Particularly there would have to be a shift in the main parameter used to calculate breakwater sections from the significant wave height (H-s) to the limiting breaker height (H-b), due to future uncertainties in wave climate. The likely increases in breakwater costs due to this shift in design philosophy were evaluated for 4 different rates of sea level rise showing that for the more extreme cases of sea level rise (for a sea level rise of 1.3m over 50 years) a breakwater designed in 2050 would be between around 8% and 66% more expensive than one designed in the 20th century not taking into account sea level rise.

2012年10月29日にアメリカ東海岸に上陸したハリケーンサンディにより，ニューヨーク州やニュージャージー州の沿岸部で高潮災害が発生した．ニューヨーク市では，変電所の浸水による停電や地下鉄を含む地下空間の浸水など，都市機能に大きな被害が生じた．本稿では，現地調査結果とウェブ上で収集した情報をもとに，ニューヨーク市における高潮災害の実態をまとめた．さらにこれらの情報をもとに，日本の臨海都市域での浸水災害を考える際に検討すべき項目として，地下空間における浸水災害の評価，人的被害軽減のための措置，異なる浸水形態（高潮と津波）の想定の3つを取り上げて論じた．

気候変動が現在のペースで100年にわたり継続したと仮定して，将来の気象条件下で強大化した台風が日本に来襲した場合に発生する高潮の危険性を予測し，沿岸域防護手法を提案した．東京湾を例として検討し，算出した高潮より標高の低い地域について，失われる資産額の算出を行った．また，算定した最高高潮水位を水準とした防潮堤の嵩上や新設，堤外地の地盤高の嵩上にかかる費用の算出を行った．約100年後の気象条件下で，190cmの海面上昇を考慮した場合，東京港・川崎港・横浜港には標高にしてそれぞれ4.5m・4.0m・3.9mの高潮高を推算した．これらの標高以下の地域が全て浸水したと想定すると，東京では75兆円，神奈川では4兆円を越える被害が出る．強大化した台風が防潮堤や水門の機能を停止する場合を想定して，将来的に荒川流域の高潮防護計画を確立する必要がある．算出した高潮高への対策として胸壁防潮堤の新設・堤外地の嵩上を行うと，直接的費用は東京港において約2,600億円，川崎港・横浜港において約1,200億円となる．

This work aims to ascertain the wave behavior and possible damage in Tokyo Bay caused by the double effect of a tsunami and long-period ground motion using numerical analysis. Tsunami behavior in Tokyo Bay has not been given enough consideration in the past, though the study of such behavior is very important to develop an adequate protection strategy. The generation of a tsunami-type wave which is affected by long-period ground motion in a bay is a new concept. The target earthquakes, which could occur directly beneath or far from Tokyo Bay, are forecasted to take place within the next 20 years.

Sea level rise and an increase in typhoon intensity are two of the results expected from future climate change. In the present work a methodology to change the intensity of tropical cyclones in Japan is developed based on the work of Knutson and Tuleya (2004). An example of how this would affect one of the worst typhoons to hit the Tokyo Bay area in the 20th century was thus developed, highlighting the considerable dangers associated with this event, and how current sea defences could be under danger of failing by the end of the 21st century.

Susami West Breakwater, a composite caisson breakwater located in Japan, was damaged by high waves caused by typhoon Tokage on the 20th of October 2004. The failure mode was characterized by the sliding/tilting of the caissons and the removal of the concrete armoring units. The failure of these armor units is believed to increase the pressures exerted by the waves on the caisson, and thus exacerbate the expected deformations in the rubble mound foundation, a fact which has thus far been ignored in previous research. The present paper proposes a methodology to take into account the effect of these concrete armor units to estimate the deformations that took place in the rubble mound foundation. The methodology uses a modification of the method by Goda [1985] proposed by Esteban et al. [2009] that can approximate to the right order of magnitude the vertical deformations at the back of the caisson by using a Monte Carlo simulation.

Study of beach morphological changes under storm conditions and its prediction capability are of paramount importance in coastal zone management. Seabed sediment is picked up violently in and outside the surf zone due to suspension mechanisms, therefore a considerable amount of sand is transported in coastal waters due to such mechanisms. For the construction of an accurate beach morphological model, it is necessary to elucidate the sediment suspension and to introduce it properly into the modelling of sediment transport. Jayaratne and Shibayama (2007) developed a complete set of explicit theoretical formulae to predict the time-averaged concentration on sandy beaches due to three suspension mechanisms: a) vortical motion over wave-generated sand ripples, b) from sheet flow, and c) turbulent motion under breaking waves. The present paper focuses on the development of a quasi-3D beach deformation model using the sediment concentration models of Jayaratne and Shibayama (2007), the bed load model of Watanabe (1982), the wave propagation model of Onaka et al. (1988), the nearshore current model of Philips (1977) and the undertow model of Okayasu et al. (1990) to predict the large-scale morphodynamics of sandy beaches. The predicted beach profiles and total sediment transport rates were compared with two sets of large-scale laboratory experimental data [Kajima et al. (1983); Kraus and Larson (1988)] and Seisho beach at Kanagawa Prefecture, Japan. It can be concluded that the present numerical model is capable of predicting sediment transport direction, on-offshore sand bar formation and the general trend of the beach profiles of large-scale erosive- and accretive-type sandy beaches to a satisfactory level.

At 14:46 on March 11, 2011 (local time), a large earthquake of magnitude Mw9.0 took place, generating a tsunami that caused severe damage to the east coast of Japan. To comprehensively record tsunami trace heights and impacts along the coastal region, the Tohoku Earthquake Tsunami Joint Survey Group was organized immediately after the event. As part of this group, the authors conducted a field survey in Miyagi and Fukushima Prefectures. The surveyed area can be divided into 2 parts from the point of view of its geographical features: the northern part (a rias coastal area) and the southern part (a coastal plain area). In this paper, the characteristics of the damage due to the tsunami in each area are analyzed by using both the results of the authors' by using both the results of the authors' own field survey and the Joint Survey Group. In the rias coastal area, inundation heights were more than 10 m, which resulted in the flooding of the low-lying grounds located at the inner part of the bays. The tsunami wave caused widespread destruction in this area, and coastal buildings (including reinforced concrete buildings) suffered severe damage. In the southern coastal plains, inundation heights were 5-10 m and the tsunami reached a few kilometers inland, though unfortunately there were not enough high locations or buildings for the residents to evacuate. In addition, an extensive line of coastal dikes and forests, which had been placed to protect the wide plains behind them, also suffered extensive damage. From these geographically dependent inundation and destruction patterns, a number of important lessons on how to modify and improve future risk management strategies can be obtained.

2011年3月11日に発生した東北地方太平洋沖地震津波の映像の解析を行った. この津波の伝播及び氾濫について気仙沼を対象とした数値計算を行い, 映像から求めた結果と数値計算による結果と比較し, 数値計算の結果の妥当性の検討を行った. 映像の解析結果と数値計算による結果との比較により, 陸上に氾濫した津波の計測結果と数値計算結果がほぼ一致するということ, 氾濫シミュレーションにおいて津波の水位変化が再現できているということがわかった, また津波の陸上部における水位変化の挙動について津波防潮堤の存在が水位の立ち上がりを遅くしていたことも判明した.

本研究では，地震発生の際に長周期地震動により発生する遠隔地での高波に注目し，その発生メカニズムを検討する．2011年3月11日に東北地方太平洋沖でモーメントマグニチュードMw9.0の地震が発生した際，震源より約470km離れた西湖(最大水深73.2m，面積2.12km²)において，波高約1mの波が観測された．本研究では西湖で発生した波浪現象を，現地調査と数値計算を用いて再現した．さらに今後30年以内に70%の確率で発生すると予測されている東南海地震と東海地震の想定に同じ計算モデルを適用し，震源より離れた東京湾での長周期地震動により発生する波の予測を行った．その結果，波が不規則に発生することが分かった．地震が発生した際に，津波とともに注意すべき現象の一つとして，長周期地震動により発生する波を指摘した．

本研究は，東京港での高潮・津波の伝播特性を数値計算モデルにより予測したものである．高潮数値解析では，様々な経路を通過する台風を視野に入れて検討を行い，東京港に発生しうる最高水位とその台風経路を明らかにした．津波数値解析では，元禄地震津波，三浦半島断層群－鴨川低地帯地震津波，慶長地震津波の3つの津波を対象として解析を行った．その結果，慶長地震津波の場合に東京港で最も高い水位上昇が発生すること，東京湾全体では湾奥部よりも湾口部で高い水位が生じることが分かった．氾濫数値解析では，防護構造物の機能不全時を仮定して計算を行い，東京港沿岸部における津波氾濫の可能性を明らかにした．計算により江東デルタ地区や堤外地の多くで陸上氾濫が生じることが予測され，東京湾岸部における津波防災対策の再検討の必要性を示唆する結果を得た．

A set of theoretical models is deduced for computing suspended sediment concentration in coastal waters under the influence of suspension on the bottom boundary layer due to turbulent motion over full-scale sand ripples and sheet-flow, following on from the work of Jayaratne and Shibayama [2007]. Dimensional analysis and best-fit technique are the main methods for the formulation of reference concentrations and vertical distribution of diffusion coefficients of the models. Model parameters (e.g. calibration coefficients) are calibrated with the help of full-scale measured data. Time-averaged concentration profiles are derived from the steady diffusion equation. Two distinct suspension layers (i.e., lower and upper) were identified within the suspension over rippled bed, therefore predictive models were given separately for each layer. In the case of sheet-flow regime, predictive models were given for suspension and upper-sheet-flow layers. Published experimental data from 4 different data sources in the SANTOSS database (75 and 80 full-scale experiments for rippled bed and sheet-flow regimes respectively) from 1994 to 2007 [Van der Werf et al., 2009] are better explained by the proposed formulae, however different sets of calibration coefficients were assigned in each data set primarily due to the flow type (regular or irregular flows) and nature of the laboratory experiments (wave flume and wave tunnel).

Climate change is expected to lead to increases in both sea level and typhoon intensity, which could threaten the stability of break waters in the future. In this study, calculations using the SWAN model showed that a 10% potential increase in the future wind speed of typhoons resulting from the warming of surface sea temperatures can lead to a 21% increase in the significant wave heights generated by these winds. To understand the effect that this would have on break water stability, the expected sliding distances for the break waters at Shibushi Ports in Japan were estimated using a probabilistic design method. The results show that in the future the expected sliding distances may be come five times greater than at present, due to a combination of increases in sea level and wave height.

The objective of this study is to propose the most suitable dissipation model for computing the transformation of spectral significant wave height (H-m0). A wide range of experimental conditions, covering small-scale, large-scale, and field experiments, were used to examine the models. Fourteen existing dissipation models, for computing root-mean-square wave heights (H-rms) were applied to compute H-m0. The coefficients of the models were re-calibrated and the accuracy of the models was compared. It appears that the model of Janssen and Battjes [2007] with new coefficients gives the best overall prediction. The simple model proposed in the present paper was modified by changing the formula of stable wave height in the dissipation model. Comparing with the existing models, the modified model is the simplest one but gives better accuracy than those of existing models.

This article estimates the non-first-order economic loss in Japan due to a future increase in tropical cyclones. One possible effect of global warming could be the increase in intensity of tropical cyclones. Using historical storm tracks between the years 1978 and 2007 and altering their intensities due to this potential increase in their intensity, this paper calculates the future potential regional GDP loss in a certain area that is affected by tropical cyclones. Most of the literature is concerned with physical damage and the loss of lives due to tropical cyclones. However, there are additional economic costs when sustained wind speeds are higher than 30 knots (55.56 km/h), a level that generally will lead to a precautionary cessation of many human activities. Using a Monte Carlo simulation, the paper calculates the potential economic costs for the year 2085 under a climate change scenario with a linear one-per cent yearly increase in CO2. Using a spatial distribution of economic activity in Japan, it is possible to forecast which parts of the country are likely to experience the highest loss risk.

The present paper develops a methodology for estimating the risks and consequences of possible future increases in tropical cyclone intensities that would allow policy makers to relatively quickly evaluate the cost of different mitigation strategies. The methodology simulates future tropical cyclones by modifying the intensity of historical tropical cyclones between the years 1978 and 2007. It then 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 given strength. The methodology outlined has a range of applications, and the present paper shows as an example the calculation of the expected cost of mitigation of the increased downtime for Japanese ports by 2085 for a variety of economic growth scenarios.

This paper aims to understand the characteristics of the tsunami disaster in the Samoan Islands by analyzing the field survey data as well as numerical simulation results. The field survey was performed about one month after the disaster to clarify the tsunami wave height and to understand the reality of the disaster according to the residents. As a result, the followings are concluded. 1) Tsunami height exceeded 5m in a wide area of Upole and Tutuila Islands. 2) In areas that have a wide coral reef, people saw the wave breaking on top of it and quickly became aware of the approaching tsunami. 3) Tsunami education contributed the residents' reaction on the evacuation. 4) Social characteristics especially existence of Matai (the chief of the village) influenced the residents' decision making after the tsunami disaster.

A number of scientists have recently conducted research that shows that tropical cyclone intensity is likely to increase in the future due to the warming effect of greenhouse gases on surface sea temperatures. The aim of this paper is to establish what would be the likely decrease in the productivity of urban workers due to an increase in tropical cyclone-related downtime. The methodology used simulates future tropical cyclones by magnifying the intensity of historical tropical cyclones between the years 1978 and 2008. It then 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 given strength. It shows how annual downtime from tropical cyclones could increase from 1.5% nowadays to up to 2.2% by 2085, an increase of almost 50%. This decrease in productivity could result in a loss of up to 0.7% of the annual Taiwanese GDP by 2085.

This paper presents a method to simulate the construction of a caisson breakwater in order to evaluate the risks involved in its construction. A computer model of the construction process that a contractor would follow to build a caisson breakwater was developed, with the wave climate for each month of the duration of works modeled using data obtained from the NOWPHAS Reports. Possible damage to the caisson was determined using a deformation-based reliability design method that included sliding, tilting, overturning of the caisson and erosion of the toe armour and foundation material. The model included possible delays due to adverse weather, reconstruction of damaged sections and construction accidents. By using the Monte Carlo simulation technique, the expected cost and time to finish the breakwater could be obtained, allowing to determine the risk associated with the breakwater construction. Thus, it is possible to determine when would be the most appropriate time to begin construction and the likelihood of encountering problems during the construction phase. A case study of the breakwater construction for Honshu island in Japan is shown, with the results comparing well with the experience of Japanese contractors.

The present study offers a two-dimensional horizontal wave propagation and morphodynamic model for muddy coasts. The model can be applied on a general three-dimensional bathymetry of a soft muddy coast to calculate wave damping. fluid mud mass transport and resulting bathymetry change under wave actions. The wave propagation model is based on time-dependent mild slope equations including the wave energy dissipation due to the wave-mud interaction of bottom mud layers as well as the combined effects of the wave refraction, diffraction and breaking. The constitutive equations of the visco-elastic-plastic model are adopted for the rheological behavior of fluid mud. The mass transport velocity within the fluid mud layer is calculated combining the Stokes&apos; drift, the mean Eulerian velocity and the gravity-driven mud flow. The results of the numerical model are compared against a series of conducted wave basin experiments, wave flume experiments and field observations. Comparisons between the computed results with both the field and laboratory data reveal the capability of the proposed model to predict the wave transformation and mud mass transport. (C) 2008 Elsevier Ltd. All rights reserved.

Climate change is expected to lead to increases in both sea level and typhoon intensity. Such changes may threaten the stability of breakwaters. In this study, calculations using the SWAN model showed that a 10% increase in wind speed can lead to a 20% increase in wave height. The expected sliding distances for the breakwaters at Shibushi Ports were estimated using a probabilistic method proposed by Takagi et al. (2008). It is noteworthy that in the future sliding distances may become three times greater than current ones due to a combination of increases in sea level and wave height.

Field surveys were performed in the Yangon River Basin to learn lessons out of severe disasters due to Cyclone Nargis. It was found that the tide due to the storm surge was up to 3-4m around 50 kilometers upstream of the river mouth of Yangon River. According to interviews with the local residents, it also appears that significant flooding took place at inland areas as a result of the upsurge through the tributaries or channels from the main river. Apart from the nvestigation, the tracks for the present and past cyclones (1945-2007) have been analyzed based on a string of best track data. The results reveal that quite a small number of cyclone (roughly 2 times on average every 10years) have hit the southern coast of Myanmar compared to the number of cyclones that hit the coast of Bangladesh, and that the route that Nargis traced is rather unique.

2007年9月にインド洋地域に津波警報が発令された際のスリランカ防災当局における災害対応の参与観察およびその後の対応に係る聞き取り調査等の分析。

Total quality management (TQM) has been recognized as a successful management philosophy that can be successfully implemented in the construction industry. By examining the Japanese contractors working in Egypt and comparing their managing systems to the local ones, a comparative analysis of the two contractors working in the Egyptian field is presented in this paper to illustrate how TQM can be implemented effectively in the Egyptian construction industry. Bearing in mind the location bound nature of the production process, the competitive bidding, which emphasizes cost and the absence of the quality culture of the clients, subcontractors and site operatives are some of the constraining factors for implementing the quality policy. Based on the research findings, the paper presents some features of the Japanese construction industry that could be implemented in the Egyptian field in addition to a new model for TQM implementation that appropriates the Egyptian construction industry.

The present study offers a two-dimensional horizontal wave transformation model that can be applied on a general three-dimensional bathymetry of soft muddy coasts. The wave transformation model is based on time-dependent mild slope equations including the high energy dissipation of bottom mud layers as well as the combined effects of wave refraction, diffraction and breaking. The constitutive equations of visco-elastic-plastic model are adopted for rheological behavior of fluid mud. The results of the numerical model are compared with a series of the conducted wave-basin experiments. The performance of the application of the numerical model on a real field condition, i. e. Kumamoto Port of Japan, is also examined. Comparison between the simulated results and measured values in both laboratory and field conditions reveal the capability of the proposed wave transformation model to consider the wave attenuation on fluid mud layers.

近年台風災害の頻発が上がりました。2004年10月20日に台風トカゲが西周参見の防波堤を破損しまりました。Kim et al. (2005) はこの破損の記録をとりました。本論に西周参見の防波堤の破損は算出記載する。Esteban et al. (2007) は波浪の作用によって生じるケーソン式防波堤のマウンドの変形手法を提案した。ブシネスクの解を使用する簡便な土質力学の理論を適用することで, ケーソン式防波堤の鉛直と滑り込み (Sliding) 変位を予測する。

This paper describes the quantitative analysis of landslide on mountainous region of Kanagawa Prefecture, Japan using the records of pervious landslide data along the road network. It determines the landslide susceptibility of an area using the Certainty Factor Model (CF) and uses SINMAP model to indicate Stability Index (SI) and susceptibility classes in GIS application. The affecting parameters such, as lithology, slope angle, slope aspect, elevation, land use and rainfall are derived and spatial database was established. The CF value that was used as GIS attributes to integrate the parameters by summation indicated it is certain that landslide will occur along sandstone and shale area with CF value of 0.38.The slope of 20°-30° had high certainty and slope facing northwest and west showed high certainty for landslide as area unexposed to sun have lower temperature and higher soil moisture which are favorable for landslide occurrence. The land use indicated higher certainity of landslides in barren land with grasses and the rain parameter indicated that certainity increases with an increase of rainfall intensity. The integration of the geomorphological parameters in SINMAP model along with the landslide data indicated the relation between contribution area and the slope. The failure slope range indicated by SINMAP model agreed with that of the CF model. The generated susceptibility class map showed similar trend while comparing with the actual landslide data of the area and also indicated the susceptibile area similar to that with CF model.

Abnormal tides wherein the water level remains high for a few days despite the absence of remarkable meteorological disturbances may occur due to incoming continental-shelf waves. In this study, it is assumed that the continental-shelf wave can be initiated off the Choshi coast; this wave will subsequently reach Tokyo Bay. First, the characteristics of tide anomalies are discussed on the basis of tide, wind, atmospheric pressure, and wave data obtained near Choshi. Second, several obvious cases of water-level propagation from Choshi to Tokyo Bay are collected by scrutinizing the tidal data at both stations. Finally, it is discussed how the adverse effects of abnormal tides induced by the continental-shelf waves may appear to be more serious if the sea level rise is dramatic.

This paper describes the quantitative analysis of landslide on mountainous region of Kanagawa Prefecture, Japan using the records of pervious landslide data along the road network. It determines the landslide susceptibility of an area using the Certainty Factor Model (CF) and uses SINMAP model to indicate Stability Index (SI) and susceptibility classes in GIS application. The affecting parameters such, as lithology, slope angle, slope aspect, elevation, land use and rainfall are derived and spatial database was established. The CF value that was used as GIS attributes to integrate the parameters by summation indicated it is certain that landslide will occur along sandstone and shale area with CF value of 0.38.The slope of 20°-30° had high certainty and slope facing northwest and west showed high certainty for landslide as area unexposed to sun have lower temperature and higher soil moisture which are favorable for landslide occurrence. The land use indicated higher certainity of landslides in barren land with grasses and the rain parameter indicated that certainity increases with an increase of rainfall intensity. The integration of the geomorphological parameters in SINMAP model along with the landslide data indicated the relation between contribution area and the slope. The failure slope range indicated by SINMAP model agreed with that of the CF model. The generated susceptibility class map showed similar trend while comparing with the actual landslide data of the area and also indicated the susceptibile area similar to that with CF model.

A set of predictive models is formulated for computing suspended sediments concentration in and out surf zone under three different mechanisms:
(1) suspension due to turbulance motion over sand ripples,
(2) suspension from sheet flow layer, and
(3) suspension due to turbulance motion under breaking waves.
Dimensional analysis ans best-fit technique are the main methods for the formulation of reference concentration and diffusion coefficient and the model parameters are calibrated with the help of a large amount of published data. Time-averaged concentration profiles are derived from the steady diffusion equation. Published experimental data from 19 sources from 1977 to 1966 are better explained by the proposed formulae than the preceding formulae of Sleath [1982]. Nielsen [1986 and 1988] and, Rattanapitikon and shibayama [1994]. Due to scale effects, models are given for small-scale and large-scale cases seperately. Predominance of each suspension mechanism is verified with newly developed explicit formula. Finally, the applicability of the above sub models for irregular waves is also confirmed by the measured data sets.

The aim of the present paper is to investigate the long-term deformations of the rubble mound of a breakwater during its working life. Understanding these deformations is essential for the sliding and tilting to be able to be measured effectively. In order to do so, laboratory experiments were carried out, from which probability distribution functions of sliding and tilting were obtained for a series of three storms of similar intensity. The laboratory results were then reproduced using a computer model, which decomposed the movement of the caisson into its vertical and horizontal components. The horizontal movement uses the equation of Shimosako and Takahashi [1998] as modified by Kim and Takayama [2005], whereas for the vertical deformation the method of Esteban and Shibayama [2006] is employed. A new methodology for the calculation of the resistance force caused by the caisson tilting is proposed. The results obtained overestimate the deformation slightly during the first storm but can predict well the deformation during the subsequent storms.

If the Rayleigh distribution of wave heights is valid, the representative wave heights can all be converted one to another through the known relationships. In shallow water, it has been pointed out by many researchers that the wave height distribution deviates from the Rayleigh distribution. However, it is not clear whether this deviation can lead to significant errors on the estimation of representative wave heights or not. Experimental data from small-scale, large-scale, and field experiments were used to examine the errors of the relationships derived from the Rayleigh distribution one stimating representative wave heights. The examination indicates that if H-rms is given, the relationships give overall very good estimations on (H) over bar and H-1/3 ,good estimation on H-1/10 but fair estimation on H-max. the effect of wave breaking was empirically incorporated in to the relationships. The new relationships give better estimation than the relationships derived from the Rayleigh distribution.

The major aspects of interactive effects between irregular waves and a soft muddy bed, i. e. wave height attenuation and mud mass transport, are examined using numerical simulation and laboratory experiments. The irregular waves are simulated by spectral calculation method and joint distribution of wave height and wave period. The possibility of applying the representative wave method is also examined. The constitutive equations of visco-elastic-plastic model are selected for the complex rheological behavior of fluid mud. A series of wave flume experiments have been performed to obtain the required data for the veri. cation of the numerical model. The results of the numerical model are also compared with the laboratory data of Zhang and Zhao [1999]. It is concluded that both wave spectra modeling and individual wave analysis are capable to simulate the interactive effects between irregular waves and fluid mud. The wave energy dissipation can also be simulated by using common representative waves. However, mean wave is the only representative wave that offers an acceptable approximation for the prediction of mud mass transport.

A three-dimensional Large Eddy Simulation (LES) model is presented together with a sediment pickup/advection module for the study of spatial and temporal variation of sediment concentration due to three-dimensional fluid motion under breaking waves on a sloping beach. The LES flow module calculates the turbulent flow due to wave breaking where a large-scale turbulence can be directly solved by the governing flow equations and a small-scale turbulence can be evaluated using a sub-grid-scale (SGS) model. In the sediment pickup/advection module, the sediment pickup rate is estimated by a sediment pickup function using the Shield's number at the bottom of the fluid layer, and suspended sediment particles are assumed to move with the ambient fluid. The numerical results show that the flow field including the wave breaking is represented well by the LES model and the sediment pickup/advection module is able to simulate spatial and temporal intermittency of the sediment suspension. Three noticeable sediment pickup areas are defined, namely around the breaking point, break impact area and run-up zone. In the inner region of the surf zone, the sediment concentration distribution shows strong three-dimensionality. The calculated results of the time-averaged and the equi-phase-averaged sediment concentration distributions are compared to earlier laboratory experiment results. The sediment concentration distribution and advection calculated by the model show general correspondence to the experimental results, but the averaged sediment concentration is approximately 1.5 times greater than the experimental value. (c) 2006 Elsevier B.V. All rights reserved.

Accumulation of soft mud (muck) at the head of Tokyo Bay is one of the major causes of deterioration of water quality and ecosystems. We conducted field observation of sediment quality and numerical simulation of grain size distribution to reveal the mechanism of its accumulation, which will provide a suggestion for the future restoration of its estuarine environment. We revealed the detailed variation in sediment quality and one of the causes is attributed to the lower decomposition rate of organic matter due to the long-term exposure to hypoxic waters along with the higher rate of accumulation of very fine particles reflecting hydrodynamic properties.

Many dam projects and dam constructions are increasingly brought forward in Mekong basin. Deposition of sand in dams will causes change of a cycle balance of sediment discharge. It is necessary to integrate numerical information in relation to dam project and sediment discharge. Sediment discharge was calculated by applying MUSLE model. Data of elevation, climate, soil and landuse of the year 1998 were used for calculation. Most of sediment discharge in the area distributed from the upper basin to the middle basin. In the area that has large amount of sediment discharge, the discharge rate will be decreased by Dam development.

This paper presents an approach for optimization of segment-linked maintenance and rehabilitation plan for a pavement network by using shuffled complex evolution. It extends the works of Nunuo and Agyei (2000) by improving the exploration-exploitation balance of the algorithm and by using a realistic pavement deterioration model to solve the problem of multiple maintenance and rehabilitation activities. An example to maximize the serviceability of the road network under a fixed budget and minimum serviceability level policy is also presented. The result of the optimization process using a part of Kanagawa prefecture road network showed very good results with reasonable computational times.

This study was undertaken to find out the suitable breaking wave formulas for computing breaker depth, and corresponding orbital to phase velocity ratio and breaker height converted with linear wave theory. A large amount and wide range of published laboratory data (695 cases collected from 26 sources of published laboratory data) were used to examine and develop the breaker formulas. Examination of some existing formulas indicates that none of them can be used for a wide range of experimental conditions. New breaker formulas were developed based on the re-analysis of the existing formulas. Overall, the new formulas give good predictions over a wide range of experimental conditions.

今後の大水深地点における海域利用の促進や既設防波堤の維持補修の観点からは, 既往の性能評価手法の高度化が重要となってくる. 特に防波堤の設計において主たる外力となる波力を精度良く推定して設計に反映することは, 設計の合理化に大きく寄与するものと考えられる. 本研究では, 砕波時と非砕波時において波力とその時間変化が大きく異なることに着目して, レベル3信頼性設計法の更なる高度化を試みた. その結果, 大水深地点において波浪の砕波と非砕波を区別して設計することの重要性が明らかになった. 本提案の方法を用いることにより, 設置水深を問わずケーソン式防波堤の更なる設計合理化を図ることができる.

防波堤や護岸, 海岸堤防などの波浪制御構造物が長期に渡って安定的に機能するためには, 堤体本体に加えて捨石マウンドや被覆ブロック, 根固ブロック等が長期的に安定なことが必要である. 防波堤・護岸の基部および法尻部では, 砕波に伴って顕著な乱流場が形成されるため, ブロックの飛散や洗掘, 裏埋土の吸出しといった被害がしばしば発生している. 本研究では, 3次元LESモデルを用いた数値計算を利用して, これら設置物の最適な設計を行うために必要な基礎的研究を行った. この結果, 3次元LESは防波堤や護岸の法尻部や端部において発生する有意な渦流れを再現できることがわかった.

Hurricane Katrinaによる高潮, 高波被害の実態を調査し, 日本の高潮, 高波被害対策に資する教訓を得た. 被災の全体的な特徴としては広域性 (延長300km以上に渡る被災, 州を越えての長距離避難), 甚大性 (死者1, 300人余り, 膨大な数の避難者, 都市機能の停止), 長期性 (今も避難を余儀なくされている多数の人々, 都市の衰退への動き) が挙げられる. 自治体ごとに被災時の対応が異なったため, 住民が避難していなかった所と前夜に住民が避難していた所では被害の出現, 復興のプロセスも異なっていた. このような被害の多様性を分析した上で, 防災計画を地域の多様性を前提にして練り上げていく必要がある.

Surveys were performed on disasters caused by Indian Ocean tsunami which occurred in December 26, 2004. Surveys were done in Sri Lanka and in Indonesia. Cooperative works with professors of domestic universities, who graduated from Japanese universities were the core of the survey works. From the survey results, varieties of disaster mechanisms were found. Local natural conditions and social conditions give big influences on the mechanism. In order to promote an appropriate post tsunami rehabilitation and environmental restoration process, cooperative works with local professors and engineers are essential.

河川流域を解析対象として気象, 土壌, 地形のデータを集積し, MUSLE (Modified Universal Soil Loss Equation) を援用して, GIS上のモデルで流域内の土砂の浸食量および河川での浸食, 堆積を考慮して海岸への土砂供給量を推定する方法を開発した. 浸食土砂量の推定には, 降雨量変化, 表土流出, 洪水, 河口への土砂の流出とつながる因果連関を設定している. 酒匂川流域はこれらのデータがそろっているため, 今回開発したモデルを適用し, その妥当性を検討した. 酒匂川における流域生産土砂量を積算して求めた, 河口からの土砂供給量は, 河口付近の取水堰での滞砂量, 浚渫量の合計とほぼ匹敵しており妥当な値を得ることができた. この結果に基づいて, 環境変化に対応する河口への供給土砂量変化の推定方法を提案した.

底泥移動の定量的な評価方法である粘弾塑性体モデルを, 実用に供することを目指して, 不規則波浪下の底泥運動と平面波浪場での底泥運動へと拡張した. まず不規則波浪下への拡張については, 二次元水路での実験結果と波高周期結合分布を対照分析することにより, 質量輸送速度は不規則波を波高周期の結合分布に分類し, 粘弾塑性体モデルを適用することによって精度良く求められることが解った. 次に, 新たに平面波浪下での質量輸送測定実験を行った. 平面波浪場における底泥輸送量の計算方法は, 平面波浪場にBoussinesq方程式を適用して波浪場の波高と波向を求め, 主波向方向に粘弾塑性体モデルを適用し, その沿岸方向成分を沿岸方向質量輸送速度とすることで求められることが解った.

アマモは群落を形成することにより, 群落内部の流速の低減や波高の減衰を促し, また地下茎や根の存在によって底質の安定性を向上させているものと推察される. 本研究では, 現地のアマモ場にて調査を行い, アマモ群落の存在が底質環境へ与える影響について評価した. また天然のアマモを用いた水理実験を行い, アマモ群落内部の底質輸送機構と地下茎や根の存在による底質の安定性向上効果の評価を行った. その結果, アマモの生育域ではその周辺の非生育域に比べ地盤表層付近の強度が高くなっていること, 及びアマモの地上部よりも地下茎や根の存在が底質侵食の抑制に大きな効果を発揮していることを確認した.

3次元Large Eddy Simulationを用いて, 流体運動の3次元性および砕波によるエネルギー減衰を考慮した砕波帯内の流場を計算した.この流速場を用いて, 砕波下の流体運動によって生じる底質の巻き上げと移流を評価できる底質浮遊モデ速ルを構築し, 砕波帯内での時々刻々の3次元浮遊砂濃度分布の算定を行った.その結果, 砕波によって発生する間欠性, 局所性をもった底質の巻き上げと浮遊を計算することができた.また, 浮遊砂濃度場計算結果の検証として, 時間平均した浮遊砂濃度を水理実験結果と比較したところ, 同一オーダーとなっており, 計算の妥当性についても確認することができた.

A comparative study is performed for environmental problems in developing countries. Examples of environmental problems are collected, classified and discussed in relation to the stages of economic development in these countries. Time history of occurrences of these engineering problems is compared with socioeconomic development stage of each country. It is found out that environmental problems are closely related with industrialization and development stages. The developing countries in Asian region including ASEAN nations are accomplishing economic development well for the long terms before the recession period starting in 1997. Industry, agriculture, and the resort development were rapidly advanced. As a result, Asian region faces a rapid change of environmental system as having not experienced by the human race before. Also in African countries, for examples in Tanzania, we can observe the same type of environmental problems.

砕波帯内の浮遊砂濃度を算定するために浮遊機構を, 1) 底面砂漣近傍に発生する渦による浮遊, 2) 底面シートフロー上の乱流による浮遊, 3) 砕波の下での乱流による浮遊に分割して考えることができる.これまでの研究では現地規模の実験, 実測結果と室内実験室規模の実験結果を同列に論じることが多かった.本研究では実験式に寸法効果が含まれていることを前提として, これまでの浮遊砂濃度に関する実験結果を再整理, 分類し, 実規模実験, 現地観測の結果に基づいて新しい算定式を示した.その結果, 乱流機構の相違によって, 濃度分布の関数形が異なることを示した.

Many researchers have pointed out that the use of representative wave approach can give erroneous results in the computation of irregular wave height transformation. However, the representative wave approach seems to be an efficient tool incorporated into beach deformation models because of its simplicity and computational efficiency. It will be useful for practical work, if this approach can be used to compute the irregular wave height transformation. Therefore, this study is carried out to investigate the possibility of simulating irregular wave height transformation by using representative wave approach. A large amount and wide range of experimental conditions, covering small-scale, large-scale, and field experimental conditions, are used to calibrate and examine the model. The rms wave height transformation is computed from the energy flux conservation law. Various energy dissipation models of regular wave breaking are directly applied to the irregular wave model and test their applicability. Surprisingly, it is found that by using an appropriate energy dissipation model with new coefficients, the representative wave approach can be used to compute the rms wave height transformation with very good accuracy.

The present study aims to simulate the various features of wave-mud interaction on fine-grained shore profiles including wave height attenuation, wave-induced mud mass transport, gravity-driven flow of fluid mud and the reconfiguration of profile shape. A two-dimensional mud beach deformation model is presented considering the transport of fluid mud under continued wave action and downward gravity force. The wave height transformation is computed from the energy flux conservation law combining the effects of mud bed, shoaling and wave breaking. The rheological constitutive equations of visco-elastic-plastic model (Shibayama et al., 1990) are selected for numerical simulation. Wave flume experiments are carried out and the results are utilized for the verification of numerical model. The results of the numerical model are also compared with the laboratory data of Nakano (1994). It is concluded that the model is capable to predict the observed phenomena.

A new breaker height formula is developed based on a re-analysis of available laboratory data. The analysis shows that the breaking wave steepness is mainly governed by its deepwater wave steepness. The power form could be used to fit the relationship between breaking wave steepness and its deepwater wave steepness. This finding is new. Although the breaker height has been a subject of study for a century, no researcher has tried to relate the breaking wave steepness to the deepwater wave steepness. Bottom slope effect is included explicitly into the present formula. The present formula and existing formulas are examined and compared with a large number and wide range of published laboratory data (695 cases collected from 26 sources). Overall, the present formula gives very good predictions over a wide range of experimental conditions and is better than existing formulas.

不規則な波の下での軟らかい底泥の移動に関して室内実験により検討した. 含水比143-173%の底泥を造波水路中に敷き, 不規則波浪下でトレーサー法により層内質量輸送量を計測した. 合わせて泥層の前後で波高を計測し, 波高の減衰について検討した. その結果, 波高減衰については波高周期結合分布の変化を分析することにより, 質量輸送については規則波の実験結果および規則波の予測結果との比較によりその傾向を把握することができた. 有義波高が大きいほど, また含水比が高いほど, 波高の減衰量, 減衰率が大きくなる. 次に, 含水比が大きいほど, また有義波高が大きいほど泥層内の輸送量が大きくなる.

砕波帯内の浮遊砂濃度を算定するためには起動力により, 3つの要素に分割して考える必要がある. それらは1) 底面砂漣近傍での渦運動による浮遊量を評価するための基準点濃度と拡散係数, 2) シートフロー状態での浮遊量を評価するための底面近傍基準点濃度と拡散係数, 3) 砕波による渦運動により巻き上げられる浮遊砂量を評価するための底面基準点濃度と拡散係数である. 本論ではこれらの3つの要素それぞれについて既往の実験結果を用いて別々に評価方法を提案し, 最終的にそれらを統合することにより砕波帯内浮遊砂濃度推定の総合的評価方法を提案した.

公共事業の選択における専門家と一般市民との関係を, 海岸事業を主な例として, 科学技術社会論の枠組みを用いて, 工学の公衆的理解という視点から分析した. 海岸事業あるいは治水事業に関する専門家と一般市民の参加する3つの委員会を取り上げ, 公開されている議事録をテキストとして採用し, 分析した. その結果, 既往の分析枠組みである欠乏モデル, 文脈モデルを踏まえて, 新たに協働的相互作用モデルを提案し, 専門家と一般市民がともに参加する会議の運営方法に関するマニュアルを提案した. マニュアルには問いの立て方, 参加者の人選, データの提示方法の基本原則が提示してある.

メコン川など主にアジア地域の大河川の流域を解析対象として気象, 土壌, 地形のデータを集積し, RUSLE (Revised Universal Soil Loss Equation) を援用して, GIS上のモデルで流域内の浸食量を推定する方法を開発した. 浸食土砂量の推定には, 降雨量変化, 表土流出, 洪水, 河口への土砂の流出とつながる因果連関を設定することができる. アジア諸地域の大河川に比べてデータのそろっている日本国内の河川のうち, 安倍川についてまず検討し, モデルの検証を行った. 次にメコン川, 紅河, 長江, イラワジ川の現状についてモデルを適用して検討すると共に, 主に降雨量の変動を考慮して, 将来の環境変化に対応する河口への供給土砂量変化の推定を行った.

波打ち帯 (Swash Zone) を含む砕波帯内乱流現象に起因する底質移動現象を解明するために, 砕波帯内流速場の数値モデルを拡張し, 新たに砕波帯と波打ち帯の乱流場の計算を同時に行なった.この算定法は, 岸側境界を移動境界として波打ち帯までを含めて流速場を一体として算定しており, レイノルズ方程式を直接に数値解析する, 非線形で時間的, 場所的に非対称な浅水波と乱流を含んでいる方法を, 新たに波打ち帯を含む砕波帯全域の流速計算に拡張したものである.計算結果と既往の実験室における計測結果と比較し, その有効性と限界を確かめた.本算定法は砕波帯内水理量の算定に汎用性を有し, 漂砂現象, 物質混合を検討する際に強力な道具となる.

海岸景観に対する世代を越えて存在する共通認識 (集合表象) を踏まえて, 砕波の景観を復元し得る海岸構造物について考察した. その際, エネルギー反射型からエネルギー逸散型への防護方式の遷移をふまえ, エネルギー逸散型の岸沖構造物を対象とした. 数値計算により縦型傾斜式離岸堤, エネルギー逸散型岸沖構造物を代表として水面変動に与える差異を予測し, 景観に配慮した波浪制御を目的とした海岸構造物について, より良き選択方法を提示した.

日本社会の変容の過程で,技術者の倫理の重要性が認識され,工学系の高等教育課程でも,倫理教育が開始されている.工学倫理規定は,技術者が日々の職業活動の中で迫られる,判断や決断を下す際にその拠り所にすべき事項を整理したもので,抽象的な文章で綴られている.これを具体的な日常の場で時宜に応じて活用するためには,具体的な事項についての思考と討論の結果が,技術者として,さらには技術者集団としての判断として徐々に練り上げられていく過程を実際に経験させることが基本となる.

A comparative study was per-formed for coastal processes in Asian countries including Japan, Thailand, and Vietnam. The examples of coastal erosion problems were collected, classified and discussed in relation to the stages of economic development in these countries. Time history of occurrences of these engineering problems was compared with socioeconomic development stage of each country. It was found out that coastal problems were closely related with industrialization and development stages.

This study is undertaken to find out the most reliable breaker height formulas that predict well for a wide range of hydraulic conditions. The applicability of 24 existing formulas, for computing breaking wave heights, is examined by using wide range and large amount of published laboratory data (574 cases collected from 24 sources). It is found that most formulas predict well for the breaking waves on the gentle slope (0 &lt; m &lt;less than or equal to&gt; 0.07), but the prediction is unsatisfactory for the breaking waves on the steep slope (0.1 &lt; m &lt;less than or equal to&gt; 0.44). Three formulas are selected and are modified by including the new form of bottom slope effect into the formulas. The new breaker height formulas predict well for wide range of wave and bottom slope conditions.

Based on a re-analysis of the existing undertow models and the experimental results, a proper explicit model is proposed for computing undertow profile inside the surf zone. The model has been derived by using the eddy viscosity approach. The model is examined using published laboratory data from six sources covering small-scale and large-scale experiments, i.e. the experiments of Nadaoka et al. (1982), Hansen and Svendsen (1984), Okayasu et al. (1988), Cox et al. (1994), CRIEPI (Kajima et al., 1983) and SUPERTANK (Kraus and Smith, 1994). The present undertow model is considerably simpler than most of existing models. Although the model is simple, it shows good agreement with the experimental results above the bottom boundary layer. The calculation is so simple that the undertow profile can be calculated by using a pocket calculator.

本研究は、社会心理学における「信頼研究」を応用し、土木技術者の意思決定過程に信頼関係がどのような影響を及ぼしているのかについて考察している。アンケート調査を行い、個人の対人信頼尺度を計測すると共に、土木技術者が実際に現場で遭遇するであろういくつかの場面を、「土木技術者の倫理規定」を応用して想定し、場面に対する対応の仕方がどのように異なっているのかを調査した。<BR>一般に対人信頼尺度の高い人ほど想定場面に対して積極性をもった回答をする傾向がある。また、対人信頼尺度の高い人ほど個人の回答の問にばらつきが少なく、どの質問に対しても同じような回答を示す傾向がある。さらに、回答の分布を年齢別にみると、33歳以上の回答者はそれ以下の回答者にくらべてその集団内で類似の回答をすることが多い。質問の内容ごとに回答をくらべてみると、入札に関しての事前の話し合いと内部情報の交換に関する回答が顕著にスコアの平均値が低く、この問題に関する警戒心が薄いことがわかる。20歳代では回答にばらつきが大きいのにくらべて、30歳代になると回答が一様になってくるのは技術者としての社会化 (socialization) 過程が完成してくるからだと思われる。<BR>土木社会の信頼社会化はすでにある程度進んでいる。しかし、完全な信頼社会の実現には、事前調整や内部情報の交換のような問題点が障害になる。この問題を解決するためには、技術者の社会化が完成してしまう30歳代半ばになるまでの倫理面での教育や、技術力を裏付ける資格制度の確立などが必要になる。

This paper aims to propose a widely applicable numerical method for the computation of longshore current on the basis of Boussinesq equations. Laboratory data of longshore current of Visser (1991) are used to be compare with the numerical results. The effects of side boundary conditions to the longshore current are discussed. A socalled 'numerical pump' method is proposed in handling the side boundaries for the purpose to obtain a relatively uniform longshore distribution of longshore current and to diminish the circulation of flow outside the surf zone.

Based on a re-analysis of the existing undertow models and the experimental results, a proper explicit model is proposed for computing undertow profile inside the surf zone. The model has been derived by using the eddy viscosity approach. The model is examined using published laboratory data from six sources covering small-scale and large-scale experiments, i.e. the experiments of Nadaoka et al. (1982), Hansen and Svendsen (1984), Okayasu et al. (1988), Cox et al. (1994), CRIEPI and SUPERTANK. The present undertow model is considerably simpler than most of existing models. Although the model is simple, it shows good agreement with the experimental results above the bottom boundary layer. The calculation is so simple that the undertow profile can be calculated by using a pocket calculator.

This paper presents a numerical solution for the bottom boundary, layer (BBL) in the surf zone. The upper boundary of the BBL is determined through the solution of a breaking waves model. Different turbulence models have been tested to determine the distribution of turbulent kinetic energy, energy dissipation and eddy viscosity in the BBL. Finally, the vertical profiles of horizontal velocity can be found out through the solution of the governing equations of the BBL.

Based on a large amount of published laboratory results, reliable models are developed for computing the average rate of energy dissipation in regular and irregular breaking waves The average energy dissipation rate is assumed to be proportional to the difference between the local mean energy density and stable energy density. Wave height transformation is computed from the energy flux conservation law based on the linear wave theory. The models are examined and verified extensively for a variety of wave and bottom conditions including small and large scale laboratory and field experiments. Reasonable good agreements are obtained between the measured and computed wave heights and root mean square wave heights.

The present paper is aimed to formulate a numerical model for calculating the time-dependent velocity field and the space and time distribution of sand concentration inside the bottom boundary layer in the surf zone. The numerical results are compared with recent laboratory data. The 2DV (two-dimensional vertical) numerical module for the velocity field is based on the Reynolds averaged form of the Navier-Stokes equations while the sand transport module uses the turbulent convection-diffusion equation. The equiphase mean values for the horizontal and vertical velocities within the bottom boundary layer (the flow field) and the equi-phase mean values for the sand concentration are obtained. A transformation of the coordinate system is performed in order to enable the easy implementation of the numerical modelling. Details of the numerical modelling together with discussions on the boundary conditions are also presented. The comparison of numerical and laboratory results reveals relatively good agreement within certain limitations of the present model. The laboratory data, which are used to compare the hydrodynamic numerical model have been obtained in the surf zone while the ones for verifying the sand concentration numerical model are obtained as a result of pure oscillatory movement.

Based on a large amount of published laboratory results, reliable models are developed for computing the average rate of energy dissipation in regular and irregular breaking waves The average energy dissipation rate is assumed to be proportional to the difference between the local mean energy density and stable energy density. Wave height transformation is computed from the energy flux conservation law based on the linear wave theory. The models are examined and verified extensively for a variety of wave and bottom conditions including small and large scale laboratory and field experiments. Reasonable good agreements are obtained between the measured and computed wave heights and root mean square wave heights.

Simple formulas to predict time-averaged suspended sediment concentration are formulated using steady diffusion equation. Empirical formulas are developed to compute reference concentration (boundary condition) and diffusion coefficient. For suspended sediment concentration in the field, the same formulas with regular wave condition can be applied by using root mean square wave height and average wave period. Total 139 data sets are used for calibration of empirical formulas and 175 data sets are used for verification.

わが国の工科系大学院教育の国際化へ向けての最重要課題は,いかにして教育と研究の両分野における国際競争力を強めるかにある。本論では大学院レベルにおける(1)教員の自己研鑽の徹底と創造力の強化,(2)共通言語としての英語の使用,(3)研究助手奨学金などの外部奨学金の自由化,の3点を提案する。これらの3つの提案は相互に重要な関連を持っており,同時に実施することが重要である。

Theoretical and laboratory investigations were performed in order to estimate the rate of mud mass transport under wave action. In the theoretical work, the behavior of soft mud over which waves were propagating was assumed to be similar to a viscous fluid. Then a formula to calculate the rate of mud mass transport was derived by using the analytical solution of mud velocity field. In the laboratory work, spatial distributions and time histories of the mud mass transport rate were measured in a wave flume using kaolinite as a bed material.

A simplified simulation model for predicting two-dimentional beach transformation was developed based on the recent results of research works on wave transformation, near bottom velocity and sediment transport. The wave field was calculated by the energy flux method based on either cnoidal or linear wave theory in the offshore zone, and by Mizuguchi's energy dissipation model in the surf zone. The velocity field was calculated by the approximate method of Koyama and Iwata using the cnoidal wave profile or by linear wave theory. The sediment transport formula of Shibayama and Horikawa, which includes the effect of suspended sediment caused by vortices created in the vicinity of ripples, was used to calculate transport rates. The model was found to give reasonable results. The results were compared with various laboratory data and the feasibility of the model was discussed.

In order to investigate on-offshore sediment transport mechanism and two-dimensional beach transformation, sediment movement under the agitation of wave breaking was considered. Sediment movement in the vicinity of wave breaking point was observed in a wave flume and sediment concentration was measured both in the wave flume and on natural beaches. The rate and direction of sediment transport at wave breaking point were calculated by using the data of two-dimensional beach profile change. The governing factors to determine the rate and direction are wave period, sediment fall velocity and suspended distance of sediment particles above bottom.

Model and experimental investigations have been performed to examine a bed load formula and to predict two-dimensional beach transformation. Laboratory experiments were carried out to count the number of sand particles in motion and to measure water particle velocity at each instant of a wave cycle in a wave flume. The results were compared with a bed load formula derived by modifying the Madsen-Grant bed load formula.