Many drifting ships were found in the 2011 Tohoku Earthquake tsunami and these caused various problems.This study aims to simulate the drifting motion of ships caused by the 2011 tsunami in Kesennuma harbor, Miyagi Prefecture. First, we simulated the hydrodynamic features of the 2011 tsunami by numerical simulation. Secondly, we analyzed the drifting motion of large ships using the result of tsunami numerical simulation. In the analysis, several test cases were conducted by changing parameters and initial positions of the ships. Then we verified the results of the ship drifting simulation by comparing with their actual grounding positions. Throughout the comparisons and verifications, we found the grounding position by the simulation was generally consistent with actual position of ships.

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During the 2011 off Pacific Coast of Tohoku Earthquake Tsunami, large vessels that could not escape to safe fields in the tsunami-affected areas were helplessly transported by tsunami-induced currents. The positions of a transported vessel in time are analyzed from the data obtained with the Automatic Identification System (AIS) which large vessels are obliged to install by the International Convention for the Safety of Life at Sea. The AIS data on the vessels in the Port of Kashima during the tsunami is utilized for numerical simulation of the tsunami-transported vessels in the port. Further, validation of the numerical simulation with the AIS data demonstrates problems on the numerical simulation of tsunami-transported large vessels.

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Characteristics of the 2011 Tohoku Earthquake tsunami and resultant damage on the coast of Tokyo Bay were studied using a field survey, an analysis of observed tsunami wave profiles and numerical hindcasting using FVCOM. The tsunami was found to overflow in several fishery ports, leading to unexpectedly high inundation and runup heights of 2.84 m and 2.91 m in Funabashi Fishery Port and Shin-Futtsu Fishery Port, respectively. The observed tsunami wave profiles indicated that the tsunami wave entered the bay with a period and a maximum height of approximately 60 min and 0.9 m, respectively, and propagated along the major axis with nearly uniform height, while the wave was amplified in ports, which characteristics were successfully reproduced by numerical hindcasting.

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The 2011 off the Pacific coast of Tohoku Earthquake Tsunami, off the Tohoku Coast, caused heavy damage to the Pacific coast regions, especially in Iwate, Miyagi and Fukushima prefectures. This paper describes severe damages to local ports, Kinkazan port, Omotehama port and Ogihama port in Ojika Peninsula, Miyagi prefecture. In Kinkazan port, the breakwater subsided 1.4 m by the earthquake and wave dissipation concrete blocks on the top of breakwater were heavily damaged by the tsunami. In Ogihama port, the seawall parapets were overturned by the backwash. The relation between runup heights calculated by the numerical simulation using non-linear shallow water wave theory and the survey results executed by the 2011 Tohoku Earthquake Tsunami joint research groups agreed well.

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A refuge facility is crucial infrastructure to save the human life from a tsunami. It had been thought that the RC and the SRC building were appropriate structures as the refuge facility, conventionally. However, since it was reported that the RC building was destroyed by the 2011 Tohoku Earthquake Tsunami, it is necessary to consider about location planning and structural design matter regarding with the refuge facility now. This paper focused on performance of a shock absorber that was installed to protect the refuge facility from tsunami driftage. The shock absorber is pile structure surrounding the refuge facility. Influences of the shock absorber upon tsunami wave force and scour was studied. It was found that the pile structure makes reduction of tsunami wave force and scour risk by numerical simulation.

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To clarify the structural damage in Sendai Plain along sandy coasts due to huge tsunami attack on 11 March 2011 and its countermeasure, in the present study, we conducted field survey for structural damage and tsunami height in coastal district of Natori City, Sendai Plain in which an artificial sand dune with the height of about 9 m is located. The measured results indicate that devastated buildings were concentrated in coastal district in which a distance from the shoreline was less than 1 km. The fragility functions for tsunami damage in this site were evaluated using the measured inundation depth. It is also found that the sand dune has an effect on reduction of structural damages due to tsunami inundation.

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Laboratory experiments on the collapse of coastal dykes due to overflowing tsunami were performed in a wave channel. In addition to the destruction caused by local scour, two mechanisms were found to be essential. One is the compression of air layer inside the dyke due to the transmission of water pressure suddenly increased by the incident tsunami at the seaside toe of the dyke. The air compression results in the increase in buoyancy force of the structure. The other is the lift force exerted at the top of the landside slope generated by the centrifugal force due to the convex streamline of the overflowing tsunami. Effectiveness of countermeasures against the destruction was also examined in the experiments.

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A climate in September of 2099 based on the SRES A1B scenario was assumed as the future climate affected by the global warming. Initial fields of 200 potential typhoons striking Mikawa Bay under the assumed future climate were provided by using potential vorticity bogussing scheme of a tropical cyclone. Then, distributions of the possible maximum storm surges generated by the 200 potential typhoons were predicted by using an atmosphere-ocean-wave coupled model. The results showed the potential storm tides in the whole area of Mikawa Bay exceed 2.75 m, which is the largest storm tide ever recorded in Mikawa Bay. The maximum storm tide of 4.9 m height in Mikawa Bay was caused in Takahama located at the western inner part of Mikawa Bay.

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In the present study, the authors have focused on the effects of an increased risk of storm surge caused by typhoons affected by climate change and forecasted it by integrating weather, wave, storm surge and tide prediction systems. This model, which the authors developed, makes it possible to calculate weather fields of typhoons not only in the past case but also in the future on the basis of meteorology and simulate waves in a complex geographical area, though many previous studies for storm surge simulation have not been based on meteorology. This model is very important for the analysis of the effect that the increase in tropical cyclone intensity will have on coastal damage. The present work proved that the model can accurately reproduce historical typhoons and coastal damage and then applied it to the field of climate change.

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This paper shows characteristics of the tsunami which arrived to the coast of Ibaraki prefecture in Japan due to The 2011 off the Pacific coast of Tohoku Earthquake, and how a supposed tsunami should be chosen for disaster reduction in the prefecture. The numerical simulation was employed with the tsunami source model by Fujii et al. (2011). The calculated results of tsunami showed the pass of tsunami propagation, the reason that arrival direction of main tsunami was not same as direction of that epicenter, and edge waves two hours after the shaking, along Ibaraki prefecture. The assumption case, of which source heights are 10 to 50% higher than original heights and of which source area is 10 km to 50 km closer to the prefecture also were calculated and will be able to become the supposed tsunami in the Ibaraki coast.

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Coastal forests in large areas of the Tohoku and Kanto districts of Japan were destroyed by the tsunami after the Great East Japan Earthquake on 11 March 2011. A non-linear long wave model that includes the breaking and washout condition of trees and houses estimates the capacity of a coastal forest with 590m in width to reduce the moment of fluid force behind forest and the washout region of houses by around 110m. On the other hand, even the washed out sea embankment has been found to contribute for reducing the washout region of houses by 1520m. Washed out houses applied additional drag force on downstream houses, however it also reduces the washout region by 510m because of the resistance to tsunami current even after the houses were broken and floated.

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The north coast area of Iwate Prefecture was attacked by tsunami due to the 2011 off the Pacific coast of Tohoku Earthquake. Firstly, this study surveyed the tsunami traces in the coast area of Iwate Prefecture. The observed data are changed to the height of the Tokyo datum line by the tide prediction model. Secondary, this study calculated the tsunami wave dynamics in the two domains, one is the large scale area which is the Pacific Ocean include the hypocenter, and the other is the small and detail scale area include the north area of Iwate Prefecture. The results of the simulation are compared with observation data. Finally, this study considered the relationship between the wave velocity and the structure broken scale.

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A new tsunami source inversion method is proposed, which includes both effects of spatio-temporal evolution of tsunami source and estimation of permanent deformation at observation points. The method was applied to the 2011 off the Pacific coast of Tohoku tsunami. The accuracy of source estimation and wave prediction is significantly improved by this method. Ridge-shaped sea-surface uplift along the Japan Trench with the maximum height of about 7 m was estimated in the tsunami source inversion. The uplift is thought to be the origin of waveforms with a sharp peak which were recorded at northern Tohoku observation points. The applicability of real-time estimation of permanent deformation was verified for tsunami prediction. The maximum error of the estimated permanent deformation was less than 10 cm.

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Based on the field surveys in the 2011 Off the Pacific Coast of Tohoku Earthquake, the resistant function of earth banks and the reducing function of the dug pools against Tsunami flood have been indicated by the authors. In this paper, the above functions of earth banks and dug pools have been discussed applying both experimental studies and analytical simulations. As the results of this study, the erosion resistance of earth banks, the flood characteristics such as depth and flow velocity at the back side of earth banks and the function of dug pools to reduce the active force by Tsunami flood can be discussed. Furthermore, the technical possibilities to apply both earth banks and artificial canals proposed as the new countermeasures against Tsunami can be shown.

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The 2011 Tohoku earthquake tsunami occurred on March 11 and struck Tohoku coast. Japan Meteorological Agency forecasted arrival tsunami height and issued underestimated value. Although a lot of tide gauge stations along Tohoku coast were damaged and failed to measure, offshore observation instruments, such as GPS buoy, succeeded to record the tsunami waveform. This study investigates the applicability of the tsunami real-time forecast model by using inversion method for the Tohoku tsunami by incorporating the observed GPS buoy data. Estimated results were compared with the measured inundation height data by the Tsunami Joint Survey Group. The result indicates that the method fairly predicts the initial tsunami source and the peak tsunami height at coast.

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We proposed a method to estimate tsunami inundation area according to tsunami height predicted by Japan Meteorological Agency. Fault models that corresponded to the predicted tsunami height for the southern part of the Sendai plain were extracted from 3,404 combinations of fault model parameters for both near-field tsunamis and far-field tsunamis. Tsunami inundation area was estimated by numerical simulations with the extracted fault models considering ground subsidence caused by the earthquakes. Area and depth of tsunami inundation can be estimated at the time of tsunami warnings by preparing a database system on the largest inundation areas of each tsunami height range based on our method.

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We proposed a method to estimate tsunami setup in front of buildings for prefectural governors to designate tsunami disaster caution districts. In the method, the maximum inundation depth in front of buildings in any points can be calculated from specific energy obtained by a tsunami inundation simulation without buildings. The method shows good agreement with inundation depths observed in the inundation areas of the Great East Japan Earthquake Tsunami.

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This study aims to identify the structural vulnerability against tsunami with the form of tsunami fragility curves by integrating structural damage mapping with field survey data,such as flow depths. The tsunami fragility curves are preliminary obtained from the case studies in the affected areas of the 2011 Tohoku earthquake tsunami. Consequently, we found that structures in Miyagi Prefecture were especially vulnerable when the local flow depth exceeded 2 m, and 6 m flow depth would cause total devastation. Through the analysis, the tsunami fragility curves were obtained for each coastal community to determine the structural vulnerability against the local tsunami heights.

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The 2011 Tohoku earthquake tsunami hit wide stretch of the Pacific coast of Japan and measured tsunami inundation heights showed significant variations even along the coast line within the same bay. Lack of quantitative data of tsunami dynamics around the nearshore and inundating area makes it difficult to fully understand actual behaviors of tsunami. This study focused on the analysis of video imagery taken at Shirahama Beach in Ryori Bay, where locally concentrating tsunami inundation height was also observed. Developed analysis system enabled us to quantify the time-varying surface water fluctuations and surface water velocities. It was found through the analysis that shorter wave fluctuations excited around the nearshore breakwaters appear to have significant impacts on such locally concentrating tsunami dynamics.

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Coastal effects of the 2011 Tohoku Tsunami along central Fukushima coast were investigated based on field survey and numerical calculation. The field survey was conducted in the central region of Fukushima coast with a 40 km stretch, where tsunami surveys were delayed due to the Fukushima Dai-Ichi nuclear power plant accident. Tsunami inundation and runup heights were measured using a VRS type RTK-GPS and laser rangefinders. Numerical tsunami calculation was performed with the model based on the linear long wave theory. The results revealed that the alongshore distribution of the tsunami height was dependent on the characteristics of tsunami source as well as the bathymetry at the depth greater than 200m. The inundation and runup heights appear to be highly influenced by the coastal and inland topography.

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Macroscopic conditions of damage to reinforced concrete buildings and coastal black pine trees in the 2011 Off the Pacific Coast of Tohoku Earthquake Tsunami are discussed through field surveys and tests. Effects of reinforced concrete building's location and arrangement, ratio of the area of windows and/or doorways to the area of submerged vertical wall with them, and foundation piles on the damage condition of the buildings are examined. The damage conditions of the coastal trees are also discussed from the viewpoints of the drag force and moment assessed using an estimated inundation flow velocity. Moreover, effects and limits of coastal forests on tsunami energy reduction are illustrated through the field surveys.

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In this research, as a response to the damage caused by the tsunami that occurred following the 2011 off the Pacific coast of Tohoku Earthquake, the resilience of coastal dikes to tsunami overflow was studied. The degree of damage, structure specifications, and tsunami height at 225 sections of coastal dikes with armored surfaces were reviewed, and the relationships between these three parameters were analyzed. Pair-wise comparisons of the length of damaged dikes suggested the effectiveness of four structural factors. The result of a multivariate analysis indicated that covering on the landward toe of the coastal dike was the most effective in increasing the resilience of the dikes to tsunami overflow. On the basis of these findings, a logistic model was proposed for evaluating the resilience of the coastal dike to tsunami overflow.

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The field survey results obtained by the team of authors in the north of Miyagi Prefecture between April 1 and 6, 2011 are summarized referring to a part of the survey results by other teams of the 2011 Tohoku Earthquake Tsunami Joint Survey Group. The inundation height was generally larger at bay heads, as well as cave tips, except several points, which were sheltered by a peninsula or had a tapering area. The tsunamis reached inland far away from the sea along valleys and rivers. Not only steel frame buildings but also many reinforced concrete buildings were collapsed in Onagawa Town. According to the numerical results, the first tsunami from the west coast and the second tsunami from the east coast should come together in Utatsusaki Peninsula, which is consistent with the interviews to survivors.

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Tsunami flow velocity is important for understanding how tsunami penetrates inland and improving tsunami numerical models, though it is difficult to measure inland tsunami flow velocity. In this paper, in order to measure tsunami flow velocities and the tsunami flow characteristics, the authors analyzed the aerial video by 2-D projective transformation and mapping on GIS. Finally, we compared measured velocities with calculated ones by tsunami numerical analysis and verified its accuracy.

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To understand the impact of the 2011 Tohoku Earthquake tsunami, the authors conducted an image analysis identifying the distribution and the amount of tsunami debris, with aerial photos and satellite images. First, the field survey was conducted at Onagawa Town, Miyagi Prefecture, to acquire Ground Truth Data(GTD). Secondly, we performed a "segmentation", which is processing images with object-based image analysis. Thirdly, we analyzed the post-tsunami images referring the GTD, and developed an algorithm to classify tsunami-debris area. Consequently, the authors estimated a supervised classification to understand the distribution and the land cover area of tsunami debris, and estimate the debris area 0.9 km² as of 19 March, and they were removed to 0.5 km² for a few months.

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We developed a tsunami inundation forecast system which can estimate the tsunami inundation area in real time by seismic and tsunami information. We were able to obtain the tsunami observation data of the GPS buoy as well as inundation by the 2011 Tohoku earthquake. Firstly we verify the system in Sendai and Ishinomaki by using the database with developed before 2011. Agreement with the observed inundation in Sendai is fine but not at Ishinomaki because limitation of earthquake magnitude and location assumed in the system. Therefore, we reconsidered this system and the revised system is applied to Ishinomaki. The result of inundation is improved but calculated inundation at some area is overestimated. So that we selected the location of GPS buoy more closer to Ishinomaki, then the result is again improved.

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Tsunami damages and inundation characteristics on Sanriku southern coast due to The 2011 off the Pacific Coast of Tohoku Earthquake were investigated by conducting field survey and numerical simulation with a two-dimensional depth-integrated tsunami flow model. From the field survey, it was found that the run-up height in Toni Hongo has reached T.P.+20m which corresponds to a four or five-storied building and many coastal structures were destroyed by tsunami attack. The numerical results revealed that the first wave with a height of over T.P.+10m hit Sanriku southern coast after approximately 30 minutes from the occurrence of the earthquake. Moreover, inland area distant from the shoreline was also found to be greatly damaged by river run-up of tsunami.

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This paper investigates tsunami characteristics on the coast of Mie Prefecture due to Tokai-Tonankai-Nankai Earthquake based on the numerical results with a two-dimensional depth-integrated flow model. The earthquake scales were respectively set to M8.7 and M9.0 which corresponds to the 2011 off the Pacific coast of Tohoku Earthquake. As a result, the tsunami propagation and inundation characteristics were confirmed to mainly depend on the magnitude of the earthquake, coastline geometry and bathymetric topography. Comparison of the numerical results and the survey data of the 1707 Hoei earthquake tsunami and the 1854 Ansei-Tokai earthquake tsunami indicated that it is of importance from a viewpoint of disaster mitigation to discuss an earthquake along the Nankai Trough with a large scale of M9.

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This study focuses on the tsunamigenic earthquake on 14 March 2012, which is the first event that the offshore tsunami observation by ocean-bottom pressure gauges had been used as criteria for choice of updating tsunami warning/advisory. We interpret the water pressure disturbances during the earthquake to carry out the time-frequency processing analysis, and followed by comparing with the ocean-bottom seismometers. The water pressure disturbances during the earthquake are dominated by the ocean-bottom acceleration and velocity for the intermediate frequency range and the high frequency range, respectively. In the low frequency range, on the other hand, water pressure amplitude is isolated on the bottom oscillations, suggesting that tsunami signals can be extracted by using its threshold.

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Harbor facilities have been estimated damage and measures due to Tsunami based on mostly water level and velocity. However, it's been reported that they're mostly suffered from sediment transport due to Tsunami by the Great East Japan Earthquake of March 11, 2011. It's necessary to estimate accurately sediment transport for damage estimate and measure examination. Also, there's no study have sufficiently evaluated the accuracy of numerical simulation for the harbor fully improved harbor facilities. This study calculated sediment transport due to Tsunami by this Earthquake for Miyako port and evaluated the accuracy by comparing the results with bathymetry before and after each Tsunami

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The trapping mechanism of floating objects during tsunami due to align trees was investigated through field survey and hydraulic experiments. From the field survey; it was observed that when floating objects flow as a group, it is possible for them to be trapped even if their representative length is narrower than the interval length of trees, from the hydraulic experiments; it was possible to find the associated physical factors, and finally propose a simple formula to evaluate the trapping mechanism.

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Coastal dikes in prefectures of Iwate, Miyagi and Fukushima were damaged by tsunami of The 2011 off the Pacific coast of Tohoku Earthquake in March 11, 2011. We focused on the damage from scour landward of the coastal dike induced by tsunami overflow, and examined the process of scour and the effects of landward toe protection on scour by hydraulic model experiments. The results of the experiments show that landward toe protection with high watertightness can keep scour away from coastal dike by surely bouncing overflowed water.

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The 2011 off the Pacific Coast of Tohoku earthquake tsunami caused the catastrophic damage of bridges as well as other infrastructures such as coastal structures and utilities. First,authors carried out the tsunami flow and inundation simulation at the affected fourteen areas near wash-away bridges by using the finite difference method with a staggered leap frog scheme. From the simulation we obtained the inundation heights at the sites where the wash-away nineteen bridges are located. Second,by using the simulated inundation heights,we estimated the horizontal and vertical hydraulic pressures acting on the bridge decks based on the previously proposed formulas on evaluation of the relationship of the position of a bridge deck to an inundation height with the horizontal and vertical wave pressures acting on a bridge deck.

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The tsunami of 2011 Tohoku Pacific-Coast Earthquake broke river-ice, and generated ice jam in Hokkaido, Japan. This study aimed to clarify the phenomenon of ice jam generated by tsunami in ice covered river. We built the river-ice calculation model. In order to check the accuracy of this calculation model, we conducted ice jam experiment and a calculation value reproduced an experiment value. We understood that it was important to set up "the conditions to generate of ice jam" and "the allowable stress of river-ice" appropriately in this calculation model. This following phenomenon was found by Simulation of Ice Jam. At the time of tsunami intrusion to ice-covered river, River-ice was destroyed and moved to the upstream. River-ice was deposited in narrow river-width. Ice jam was generated at this point.

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Oil slick drift characteristics on the water surface by wind under swell conditions were experimentally studied. In the experiments, drift velocity of the oil slick was measured using a wind wave tunnel tank. It was confirmed that without swell, the drift velocity is nearly 0.03 times faster than the wind velocity 10m high above the sea surface. In the case that the swell exists and propagates to the same direction of the wind, the drift velocity by the wind was found to become smaller as the steepness of the swell increases. This observation agrees with other researchers such as Reisbig et al. (1973) in spite of different experimental tank size. The result of this study will be instructive for precise prediction of the oil slick at oil spill incidents.

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Influences of surface gravity waves on an inner-shelf circulation, such as an interaction between waves' Stokes-drift and Coriolis force and a correlation between Stokes drift and background relative vorticity, are investigated with a quadruple-nested high-resolution modeling framework based on ROMS-WEC (Uchiyama et al., 2010). While the primary momentum balance occurs between the pressure gradient and Coriolis forces, consistent with the geostrophic balance at R_o < 1, the Stokes-Coriolis effect comes in at the same order of magnitude to modify the dynamic balance substantially. Eddy kinetic energy associated with mesoscale and submesoscale momentum fluctuations is also strongly affected by waves. The latter is energized in the nearshore, leading to the dominant submesoscale contribution through vortex force.

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This paper is to investigate wave and current interaction which is an important physical field in the vicinity of river mouth. Hydraulic model experiments have been carried out. In the experiments, changes in the wave heights, flow pattern on bed and horizontal velocities trajectory are observed for current velocities and oblique incident waves under wave-current coexisting fields. In particular, the combined effects of both velocity components under interaction between wave and current indicate to affect to flow field through the horizontal velocities trajectory. It is suggested that there is close relationship between wave-current interaction and sediment transport near river mouth.

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Whereas the Kuroshio drifting up off the eastern coast of Japan is known to be controlled by the mesoscale dynamics,effects of the ageostrophic submesoscale dynamics on the mean structure,eddies,frontal processes,etc. have not been fully understood. Towards a rigorous submesoscale Kuroshio modeling,a detailed numerical downscaling experiment is performed with a double-nested ROMS at horizontal resolutions of 3 km and 1 km,forced by the assimilative JCOPE2 at 1/10 deg. as the boundary condition. According to the analysis on kinetic energy conversion rates along the principal frontal directions,meandering and scale transitions are attributed to baroclinic frontal instability,while suppressed by horizontal shear near the Kuroshio axis.

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The estuarine circulation in Seto Inland Sea (SIS) has been reported to be affected by the intrusion of the Kuroshio through its two narrow channels. Fluvial buoyancy and mass inputs, as well as its complex coastline,topography and thousands of islands, could skew the oceanic influxes through nonlinear processes, and thus substantially enhance intrinsic variability in the estuary. In the present study, a SIS downscaling system is developed based on a double-nested ROMS at a horizontal grid resolution up to 600 m forced by the assimilative JCOPE2 and the JMA GPV-MSM, to examine the interaction between the estuary and the Kuroshio. After validating the SIS model output, subtidal variabilities on the volume exchange at the two channels along with the riverine influxes are investigated.

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Assimilation of 3D observed salinity and temperature data obtained by steady observation stations using 4D-Var (four dimensional variational method) are applied and tested in Osaka Bay. Data assimilation becomes fully effective after around 8 hour calculation. Appropriate horizontal and vertical correlation scales are found to be 10km and more than 3m by calibration with the consideration of density distribution under the influence of river plume and location of the observation stations. Water quality model is modified to represent hypoxia better and run with 4dvar flow model. Without direct data assimilation of dissolved oxygen, the improvement of density profiles has an effect on that of DO profiles.

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Coastal ocean current fields of the surrounding waters in the East China Sea continental shelf are affected not only by the climate change and Kuroshio current, but also by the large river-oriented fresh waters, such as the Changjiang diluted water (CDW) and the Yellow Sea mixed water (YSMW), which are strongly affected by land use, land cover and human activities. In this study, the monthly variation of flow discharges of Kuroshio, CDW, YSMW and Taiwan Strait coastal waters was analyzed for the 19 years (January 1993 to September 2011) using the re-analysis data of ocean currents FRA-JCOPE to investigate the long-term variation of flow properties in the East China Sea. The analysis made clear that Kuroshio off the Taiwan coast is on the increase of 0.2453Sv/yr and 0.00239Sv/yr for Taiwan strait current.

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Numerical experiments on meteorological fields were performed using WRF model with considering latent heat of sea sprays in order to investigate how much contribution does the sea sprays have on the air-sea heat transfer. The contribution of sprays on the entire heat flux on the deep ocean was found to be up to 6% under the present meteorological conditions without extremely strong wind, which could be one-order higher in the coastal region where the amount of sprays is much higher than the deep ocean. The effect of sprays is suggested to be evaluated separately instead of using a bulk model for computing meteorological fields around a coastal region or storm where generation of sea sprays is increased.

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The first stage of the forecasting method for meteotsunamis in coastal areas of the East China Sea was developed using global-covered grid point value dataset provided by Japan Meteorological Agency. The authors analyzed the instability layer occurred at Middle- or South China using Richardson number considering buoyancy of the moist air. The wind speed of lower-middle troposphere over the East China Sea is considered to satisfy the occurrence of Proudman resonance once occurred the pressure disturbance at sea level. As a result, all of 18 cases had unstable layer in the midtroposphere above the stable lower troposphere.

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Coupled atmosphere-ocean model has developed in various agencies. Warner et al. developed COAWST model using the atmosphere model WRF, the ocean model ROMS and the wave model SWAN. Though there are several studies with coupled model, the coupling model using WRF has not been developed in Japan and there is no research analyzing the changes in ocean current and water temperature in detail. In this study targeting Typhoon Melor (2009), several calculations that changed the coupling condition were carried out, and it is estimated the meteorologic and oceanic field at Tanabe bay in Wakayama. The results show that the wave energy dissipation by the wave model is effective in the change of ocean current and the thermal feedback by the atmospheric model is effective in the change of water temperature due to the typhoon passage.

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One of the important procedures for Disaster Prevention Plan is to determine accurately the wind condition of an approaching typhoon. By using the Meteorological Model, it enables the aforementioned situation to be specified. The purpose of this study is for the method application to the Disaster Prevention Plan. The effect examined is due to the difference of several computational condition by Typhoon 5115. This reveals the property model of WRF with Typhoon Bogus. In addition to that, we enumerated the problem issued from the model utilization in order to make the application easy. According to the study, it is proved that the parameters of Rb and Ro greatly influences reproducibility of typhoon. The magnitudes of central pressure and wind velocity speed are susceptible to Nudging coefficient.

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Coral cays may be formed by the high waves in about several days. If the initial formation mechanism of coral cays can be understood, it will be useful for protection, the environmental preservation, and use of the coral reef seashore. Moreover, it can contribute also to protection of islands in Japan and the Pacific Ocean archipelagic country where the sea level rise due to global warming may result in submersion. In the past research, the formation mechanism of coral cays is performed by 2-dimensional tests. But, it includes neither the influence of 3-dimensional wave and current which were caused by waves equipped with open sea, nor the influence of a steep slope reef. In this paper, 3-dimensional hydraulic movable bed model tests were conducted to clarify the coral cays formation process.

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We measured the velocity field and suspended sediment concentration in laboratory surf zones using a Particle Image Velocimetry and an optical concentration probe to clarify the sediment transport process under breaking waves. Turbulent energy is produced downward blow the water surface by large-scale vortices when a wave crest passes, and then the turbulent energy developed in a shallower region is transported offshore by undertow to affect the sediment suspension. The sediments are immediately suspended when the turbulent energy is provided to the bed. The time scale of turbulence developing after a wave crest passed varies by breaker type and the water depth.

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Ibusuki Coast is famous for hot springs and attracts many tourists who enjoy sand bathing along the beach. However, the beach erosion becomes a serious problem there and several attempts to prevent the progress of erosion have been conducted. One of the possible causes of the erosion would be a seepage formation at the beach face during ebb tide. The present work conducted a field survey to investigate the fluctuations of the ground water table and water temperature in the unconfined coastal aquifer considering the response to the tidal level fluctuation. The inherent effects in this site as the high water temperature on the ground water motions and seepage face motions are discussed.

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Gravel movement on sand-gravel mixed beaches was investigated by using RFID technique which detects individual gravel tagged with a passive IC tag. At the same time, variation of the foreshore beach topography was recorded by RTK-GPS. Gravel movement mechanism and the corresponding beach face change were studied on the basis of seven field surveys performed in the period from January to February 2012. On the target beach, storm waves tended to transport many gravels onshore and develop a steep beach face. In contrast, downwash motion by moderate waves moved gravels offshore although a small amount of gravels was exchanged across the shoreline simultaneously. The movement of gravels on the foreshore appeared to be influenced by the presence of submerged breakwaters.

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For understanding the distance over which the sand transport rate by wind will be in equilibrium, large scaled wind-tunnel experiments for two kinds of sand size were carried out varying the sand layer lengths. Results from the vertical distributions of wind speed, blown sand speed, and sand transport rates suggested that the equilibrium distance was 8-10m to the fine sand(d50:0.25mm) when the shear velocity was under 1.3m/s., however it was 15m or more to the coarse sand(d50=0.52mm).

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