In this study, a total of 29 typhoons occurring in the 2004 Pacific typhoon season are simulated using an axisymmetric 2-D typhoon model (2DTYM) and a regional 3-D typhoon model (3DTYM). 2DTYM is intended to estimate the axisymmetric typhoon structure and its intensity constrained by typhoon's environmental parameters. 3DTYM is developed to evaluate the full structure of a typhoon from the genesis stage to the decaying stage, considering important typhoon-ocean interactions. Comparisons of these results simulated by both the models indicate that 3DTYM is able to predict the realistic typhoon intensity more accurately than 2DTYM, because 3DTYM can capture the internal asymmetric structure in a typhoon, which is responsible for typhoon intensity change especially during the decaying stage.

抄録全体を表示

An advance of the computing technology has evolved climate projection calculations. Resolution of global climate models becomes higher and has reached to several tens of kilometres. Mesoscale models enable to simulate cumulus cloud convection have been developed and applied to extreme weather systems. This study directly uses the downscaling of climate change experiment by high-resolution non-hydrostatic Regional Climate Model with 5km grids (RCM5) for the simulations of storm surges to assess impacts of future change of storm surges around coasts of Japan. Increment of storm surge will not take place uniformly and there are strong regional dependencies influenced by typhoon track and intensity change. Return periods of storm surges will change significantly in the future climate especially in the western Seto Inland Sea, Japan.

抄録全体を表示

Future projections of global and the North West Pacific wave climate under global warming scenario were conducted and the uncertainties related with different Sea Surface Temperatures (SSTs) were investigated, based on SST-ensemble experiments performed by an atmospheric general circulation model and a wave model. Future changes in average wave height show same or opposite signals among the series of experiments depending on the ocean and season. Especially in the North West Pacific, the uncertainties of future wave climate in summer are larger than other oceans due to uncertainty in projection of typhoon characteristics.

抄録全体を表示

Distributions of the maximum sea-level rise (SLR) during the years from 2006 to 2100 were shown globally based on the climate scenario, MIROC-ESM, for the RCP4.5, 6.0, 8.5 scenarios, as well as shown around Japan and South and Southeast Asia in details. The SLR risk index, relative sea-level rise ratio (R-SLR), introduced by Yokoki et al (2012) were modified in this study involved by the changes in sea-level rise and its annual variation. The locations and factors of the anticipated high risky coastal areas were discussed by using the maximum SLR and the modified R-SLR globally as well as around Japan and South and Southeast Asia.

抄録全体を表示

The concentration of the atmospheric CO₂ has been increasing since the middle of the 21^st century. The iron and steel industries have produced extremely large amounts of slag as byproduct of the iron making and steel making processes. The purpose of this study is to estimate CO₂ sequestration capacity using chemical reaction from steel making slags. The chemical extraction of Ca and Mg from steel slag was investigated and the relationship between the gas transfer velocity and turbulent mixing at the water surface was also experimentally investigated. Based on these experimental results, we developed a numerical model for computing physical-chemical processes and for estimating CO₂ sequestration capacity in ocean space.

抄録全体を表示

Field observations and numerical analyses using a wave model,an ocean model and a particle tracking were performed to investigate relationships between distributions of corals,waves and sediment transports in Amitori Bay,Iriomote Island,Japan. At the mouth of the bay,high wave height and low sedimentation,tabular coral groups were dominant. In the inner part of the bay,where is calm and much sedimentation,tabular groups decreased and small coverage of massive and branching types were remained. In tabular coral group, Acropora digitifera, A. millepora and A. hyacinthus were dominant species. Acropora digitifera distributed low wave height and a few sediments. Acropora millepora could distribute as long as the wave is high even in case of much sediments.

抄録全体を表示

For the purpose of considering fishery resources in the future, climate change impact assessment on future water temperatures is important. In this study, future water temperature change of Ise Bay is assessed using coupled river-ocean model. Future climate change of rain fall amount and air temperature from 15 CMIP3 models are used as an atmospheric boundary conditions, and climate change of river discharge and water temperature from Hydro-BEAM prediction are also used as a river mouth boundary condition. Under the A1B scenario, future SST in Ise Bay increases by about 2 degrees. Coastal areas are more strongly influenced. As a result from sensitivity analysis of the external force, it is found that the impact of external forces to the future SST calculation is in the order of open ocean> atmosphere> rivers.

抄録全体を表示

When developing wave power generation, in order to calculate electric power from the existing wave power and wave energy of the Japanese coast, it is important to grasp the characteristic of a wave. This research has grasped the amount of annual wave energy of the Japanese coast based on the annual data of the Nationwide Ocean Wave Information Network for Ports and Harbors (NOWPHAS). Moreover, frequency distribution of the average wave quantity for 20 minutes of NOWPHAS and an average periods is created, comparison with distribution of the past, such as Rayleigh distribution, is performed, and the concept of still newer frequency distribution is proposed.

抄録全体を表示

Current in the Tsugaru strait that is constructed by ocean and tidal currents is one of the potential renewable energy sources in Japan.We investigated the effects of the ocean current on the tidal current field in the strait through numerical experiments using a three dimensional circulation model.Non-linear effects of the ocean current caused difference in the formation of the residual current as well as the harmonic constants of the diurnal and semidiurnal tidal constituents, which also resulted in the difference in median and dispersion of the current velocity.The direction of the current was found to have low standard deviation within 60° as westward tidal current is balanced out by the eastward ocean current.

抄録全体を表示

We have shown that the conversion efficiency of tidal current energy by a vertical Savonius water turbine is significantly improved by introducing a new guide vane device around it. In the target site of a tidal current power plant, typically Kurushima Strait in the Seto Inland Sea, the site usually faces to comparatively wide sea area on both sides of the narrow channel. Therefore, wave actions on the tidal current power plant must be examined from both the points of structural stability and energy conversion efficiency. In this study, the influence of wave actions on the conversion efficiency of tidal energy was examined experimentally through the use of combined flow field of waves and tidal currents. In addition, effectiveness of a vertical Savonius water turbine as a wave energy extraction device was also examined.

抄録全体を表示

In this research, the hydraulic model experiment examined the power generation efficiency of the caisson furnished with PW-OWC type wave power generation equipment. OWC type wave power generation equipment has established the air chamber in which the portion submerged in water carried out the opening in the front of caisson. The problem is that the primary conversion efficiency of energy will decrease rapidly if the period of a wave separates from a resonance period. Therefore the wall called a projecting wall in the normal line right-angled direction was installed in the front of an air chamber. The primary conversion efficiency of energy of OWC breakwater with PW is larger about 10%. that without breakwater.

抄録全体を表示

We have proposed a new type ocean energy harvester, Flexible Piezoelectric Device (FPED), consisting of piezoelectric film and elastic material. In our previous work, we have developed the panel type and roll type of FPED and we have also succeeded in generating electric power form wave, current, wind and several kinds of mechanical vibration. These electric power can be generated by bending stress of external force. In this study, to harvest wave power in shallow water region, we can make the most use of tensile and compressive stress caused by wave force. The tensile and compressible types of the FPED have been developed and we conducted some experiments. We confirmed that the new types can generate electric power and there are some key parameters for high performance of the FPED.

抄録全体を表示

The purpose of this study is to examine practical use of an elastic floating unit with hanging structure (EFHAS) using the flexible piezoelectric device (FPED) we have proposed and developed in our previous works. We investigated electric performance of floating unit in EFHAS, optimized electric circuit and scale effect for electricity generated by FPED. It is cleared that the floating type of EFHAS is suitable for highly electric performance and the impedance matching should be required to work well. It is found that the optimized length of FPED for wave length W/λ is 0.25~0.3 and electric power in full scale could be related to the scale ratio α between experimental model and full scale one.

抄録全体を表示

The pendulum type is one of the most effective devices to extract wave energy from ocean and we are developing new power generation system called 'Wave Rudder'. Although the pendulum type system has been designed based on the two dimensional potential theory, the three dimensional analysis is required in order to consider the directional wave field in practical use. In this study, a depth integrated model was developed to calculate pendulum (Wave Rudder) motion by multi-directional irregular waves. The accuracy of this model was verified by comparing with the conventional theory in cross-sectional cases. Since computational complexity is much less than the three dimensional model, it is useful for the design of Wave Rudder and an electrical generator.

抄録全体を表示

The method of amplifying ship generated waves with both wave concentration structures and a reef to obtain sufficiently high waves for surfing is discussed to build surf points also in a calm area of coastal zone. The most appropriate condition of waves for surfing is defined according to the questionnaire to local surfers in Kagoshima, Japan. The most effective shape of the structures is determined through numerical calculation of amplification factors of wave height. Numerical computations, as well as hydraulic experiments, of ship generated waves amplified using the structures are performed, resulting that it is feasible to build a surf point in Kagoshima Bay by amplifying waves generated by the ferries through the presented method with the structures which consist of the wave concentration structures and the reef.

抄録全体を表示

We overhauled the issues of tsunami disaster prevention management in a school from the disaster example in the Great East Japan Earthquake. It turned out that the school where refuge from tsunami is difficult is concentrating in northern Tokushima by analyzing the tsunami danger of the school in Tokushima. We proposed using an action card at the time of a disaster as a tool for disaster prevention management. In order to improve the effectiveness of school disaster prevention management, it is important that a tsunami disaster prevention specialist cooperates positively.

抄録全体を表示

The social welfare facilities suffered serious damage by the Great East Japan Earthquake. Because the person with a disability and an elderly person could not walk by oneself, they failed to escape at the time of the tsunami disaster. 96 social welfare facilities are installed on the coast in Tokushima Prefecture and those will suffer the damage of tsunami. Those institutions should get to know the risk of tsunami and need to have a suitable evacuation plan. If a tsunami risk is very high, the institutions should relocate at high and safe place.

抄録全体を表示

Unexpected huge tsunamis sweep away shelters near coasts and make the shelters impossible to use for post-disaster refuge life. A prepared disaster response plan for an assumed tsunami becomes unable to use for an unexpected tsunami beyond the scope of assumption. Local municipalities have to find other capacities instead of flooded shelters, and may need to raise the local disaster response level to the prefectural one when a large number of shelters are lost. This study estimates tsunami magnitudes that require policy change of disaster response from a viewpoint of the loss of sheltering capacity by tsunami inundation simulation for different tsunami scenarios and magnitudes. The threshold level has been estimated for Wakayama Prefecture as follows: about 6 m in north area; 7 m in middle area; and 11 m in south area.

抄録全体を表示

This research aims to analyze the characteristics of the tsunami that had stricken Osaka Bay Area in the initial Jomon period. The bathymetry of Osaka Bay and topography of Osaka Plain of 11,000 years before present are reproduced rigorously from boring data and acoustic profiling data for tsunami numerical simulation. Tsunami numerical simulations assuming ordinary level and maximum level of Nankai Trough earthquake tsunami are carried out with the water levels of every 1,000 years of initial Jomon period. It is found that tsunamis in early initial Jomon period were relatively low, and by contrast, tsunamis in late initial Jomon period were high. The area where high tsunami struck in the initial Jomon period were found from the simulation results.

抄録全体を表示

This paper shows the initial results challenged on making tsunami risk map including very extreme tsunami based on the tsunami height records. Extreme value analysis proposed by Goda (1990) was basically employed together with Jackknife method and SLSC method. As number of tsunami height records is small,the extreme distribution functions which were not rejected used for uncertainty of extreme value. The probabilistic hazard areas with the uncertainty of tsunami were calculated by numerical simulation of shallow water equation,of which tsunami height was almost same as the extreme value at the analysis points. The risk maps of house damage and victim were also shown finally. The biggest problem which remained at the end of the study is dealing with the length of tsunami records.

抄録全体を表示

Once the storm surge disaster occurs in the area of land below sea level, it will be inundated seriously. At that time it is difficult for the residents to stay there. Therefore, the residents in such the area should evacuate to the heights. In this study, the intention of evacuation against the storm surge disaster of the residents was examined. As the result, two main problems were clarified. One is many residents don't understand that it's hard to evacuate because of the strong wind, and the other is that they are going to evacuate to the shelters in their living area even though they are on the lowland. On the basis of these results, we developed the tool for the education of disaster prevention against storm surge disaster and the education was carried out with it. Then, the effect of the education was examined.

抄録全体を表示

General tsunami evacuation drills designate evacuation routs, areas such as school facilities and schedule of roll-call, soup-kitchen and fire-fighting exercises. However, in actual evacuation, the appropriate area is to be selected individually as conditions evolve. This paper is to explain a new tsunami evacuation exercise method which has no designated area and the conclusions obtained from actual practices and verification: 1) Active Learning efficiency such as reconsideration of evacuation area originated from not being designated where to evacuate is confirmed. 2) Many participants evacuated to appropriate areas, on the other hand there are some who chose inappropriate areas. 3) Evacuation Drill participation rate must be improved.

抄録全体を表示

The 2011 Tohoku tsunami was 2 to 3 times higher than the existed expectations. Many people were unexpectedly attacked by this devastating tsunami. In this study, the authors focused on an elderly care facility in Minami-sanriku town, Miyagi Pref., Japan, which was located outside the expected inundation zone. 41 users per 69 were killed by this unexpected tsunami. This study finds out the reasons why 28 users could evacuate, using an evacuation simulation, interviews, and a tsunami simulation. As a result, it was clarified that the unexpected huge tsunami shortened the usable time for evacuation because of the drastically delayed start time of evacuation. Quickly wide-spreading sense of crisis, assembly places after shaking, and so on should be considered for a safer society, able to cope with unexpected large tsunami events.

抄録全体を表示

Sand and soil dredged during port improvement work has been returned to dredged trenches as backfill since 2011. Considering the coastal environment,construction work has employed the double pipe tremie process with a suspended turbidity barrier and monitoring of water cloudiness. To gauge the spread of turbidity,an on-site experiment was performed in which soil and sand were loaded into the water with no barrier,in 2012. In light of these findings and the circumstances of construction,it was thought that the suspended turbidity barrier could be replaced with a freestanding type. This would be an effective method as it would prevent the rise of sand and soil lifted up by work barges,render the task of setting up and removing the barrier unnecessary,and enable extension of the construction period.

抄録全体を表示

The authors started field observation mainly around the Musashi Bank in 2009, in connection with a planning of fishing ground development in the exclusive economic zone around Hokkaido. It considered the migration pathway of the larva of alaska pollack that was the target of the resource conservation. Bloom and snowmelt flood occurred in the juvenile stage, the primary production increased at each event, and the diet environment on the pathway was improved. Temporary lack of the nutrient salt on the surface was canceled by the vertical circulation at nighttime, the primary production rate was calculated about 1278 (mg-C/m²/day) in March. It decreased markedly under the assumption of the stratification in summer. It was suggested that bloom and snowmelt flood in this area are suitable for its life history strategy.

抄録全体を表示

We propose in the present paper the combined method of three dimensional water quality model and Computable General Equilibrium(CGE) model to estimate the economic value of the filtration function of a mudflat. The filtration function is valued by some steps which; i) the improvement of COD in the whole of Osaka Bay by the construction of new mudflats is calculated by EFDC 3D water quality model, ii) the total volume control of COD which delivers the equivalent improvement is sought with the water quality model, and iii) economic losses caused by the total volume control are estimated by the CGE model in Kinki region. The economic value of the filtration function of the 225 ha mudflats which are supposed to be located near river mouths in the head of Osaka Bay is estimated at 478 billion yen.

抄録全体を表示

The Great East Japan Earthquake occurred on March 11, 2011 and the coastal zones along the Pacific Ocean in Tohoku area have received severe damage by tsunami. Most of coastal forestations have been severely damaged or swept away due to a gigantic tsunami. In this paper, historical background of coastal forestation was studied by detailed literature surveys. An instructive formula was developed between damage level of houses and a distance from coastal forestation by field investigations at the coast of Sendai plain. Furthermore, damage level of houses was clarified as a function of inundation depth of tsunami with influence of a housing code.

抄録全体を表示

We investigate beach morphology change of the Southern Sendai Coast due to 2011 Tsunami by analyzing beach topography before and after the tsunami and aerial video during the tsunami. The results show the characteristics such as erosion at the landward of seawall and landward sediment transport during tsunami runup, seaward sediment transport from shore during backwash, accumulation of sediment around detached breakwaters and T-shaped headland, and beach stabilization by seawall. At the seriously eroded Yamamoto Beach, more than half of the total amount of eroded shore sand above sea level is estimated to be transported seaward and accumulated at a depth of 2 to 15 m. Characteristics of beach morphology change and its mechanisms are demonstrated in this study

抄録全体を表示

Morphological changes of the coastal area along the south-western part of Bangladesh, specially focused on the areas with mangrove forest, have been studied. LANDSAT satellite images were analyzed to detect shoreline positions and a regional overview of coastal accretion and erosion over three time periods, from years 1989 to 2000, 2000 to 2005 and 2005 to 2010, has been obtained. Most of the area suffered from erosion and the rate of shoreline retreat was approximately 80 m / year at maximum. Variation of normalized difference vegetation index derived from satellite data, river discharge, salinity, tide level and wave action has been analyzed to infer possible factors that caused erosion. Salinity of the river water in the dry season seems a critical factor for prevalence of mangrove forest which stabilizes the morphology.

抄録全体を表示

The 2D-PIV measurements were conducted to obtain air flow distributions above wind waves. Poisson equation was solved numerically to compute air pressure distributions by using the PIV measurement data. Low pressure distributions, less than 1013hPa, appear over a wave crest. High speed air flow over a wave crest makes air pressure decrease. Separation vortices on leeward surface also have low pressure values. The form drag was calculated by integrating of horizontal component of pressure resistance along wave surface. The frictional drag also was calculated in a similar way, using frictional resistance. The form drag is one order larger than the frictional drag. However, the averaged value of form drag is nearly equal to zero.

抄録全体を表示

Wave spectrum analysis was performed using wave forecasted data and observed radar data. Wave spectrum with multiple peaks was estimated effectively by wave spectrum parameterization and data assimilation method corresponding to each peak. By performing optimal interpolation (OI), peak wave period and wave direction approached the radar data without changing the total wave spectrum energy.

抄録全体を表示

A significant development of sandbars can be seen at the entrance of Lake Tofutsu, one of the lagoons located along the Okhotsk Sea in Hokkaido, Japan. The authors have evaluated the sequential sedimentation history of the sand bars by means of MASW (Multi-channel Analysis of Surface Waves). The purpose of this study is to verify this sedimentation history through soil sampling and laboratory testing at some typical points along the arrays of MASW. Sampling method was modified to be suitable for low-cost soil investigation at tidal flats. The samples collected were examined in the laboratory to obtain the depth profiles of grain-size distribution and carbon 14 dating. The results obtained in this study are consistent with the sequential sedimentation history evaluated by MASW.

抄録全体を表示

The Blue Carbon, which is carbon captured by marine living organism, is recently focused as an important factor for the climate change initiative. However, the contribution of Blue Carbon sequestration to atmospheric CO₂ in the shallow water area has been unclear, because the investigation and analysis technology were unmatured. In this study, we selected wind speed, water temperature, salinity, total alkalinity (TA), dissolved inorganic carbon (DIC), and the metabolism as the environmental factors affecting air-sea CO₂ flux. These data sampled at the Furen-ko Lagoon were analyzed using the scatter diagram matrix, tree model, and generalized additive model. Moreover, we proposed the stochastic prediction method using the multiple linear regression models.

抄録全体を表示

A field observation has been conducted near the mouth of Shinano River and on the Niigata West Coast to develop a seabed classification method using ADCP seabed backscatter data. ADCP backscatter intensities are estimated considering the effect of salinity and water temperature. The backscatter data on the bottom surface were evaluated with the data at three locations near the surface. A correlative relationship between the ADCP seabed backscatter and the mean diameter of bottom sediment is found both in the data of the Shinano River and Niigata West Coast. Using the relationship, the mean diameters are estimated and compared with the diameters of sampled bottom sediments.

抄録全体を表示

This paper presents an image-based method for quantifying sediment transport under highly concentrated sediment-laden flows in laboratory flumes. The method is capable of simultaneously obtaining sediment concentration and transport velocity from sediment particle images to evaluate spatial distributions of sediment fluxes at high resolution. The concentration measurement is based on a pre-calibrated relationship with light attenuation, while the velocity measurement is done through PIV. It was found from a simple verification test that sediment fluxes can be measured with up to 10% error unless sediment concentration is so high that traceable particle patterns disappear from the images. A feasibility study suggests that further extension of the method for higher concentration is made possible with help of a stereoscope.

抄録全体を表示

GPS buoys on NOWPHAS acquire deepwater waveforms at a spot of 100-400m in water depth and 10-20km off the shoreline. This study estimated the directional spectrum from the 1-s-long-interval time series of the altitude and two-directional horizontal velocity components of the GPS buoy off the Pacific coast of Owase Port during the passage of Typhoon Melor in 2009 by applying the extended maximum entropy principal method. It confirmed that the peak frequency and direction of the observed spectrum met well those of the hindcasted at major timings in the storm event Furthermore, this study determined the parameter Smax for Mitsuyasu directional spreading function from the observed spectrum. The value was 10-20 in relatively calm wave conditions, 50-70 in swell, and 20-40 in wind waves.

抄録全体を表示

To understand the impact of the 2011 Tohoku earthquake tsunami and to observe the recovery efforts in the tsunami-affected areas, the authors conducted an integrated analysis identifying the spatial distribution and amount of tsunami debris, with aerial photos, satellite images, and LiDAR data. The analysis was conducted in Onagawa Town, Miyagi Prefecture including the ground truth data acquisition. The horizontal mapping of tsunami debris in Onagawa town was performed through object-based image analysis of aerial and satellite images. Integration of horizontal mapping of tsunami debris and the analysis of digital surface model (DSM) of LiDAR data yields an estimate of the volume of the debris to be used as the observation of debris removal efforts.

抄録全体を表示

A method for rapid detection of tsunami devastated areas using multi-temporal TerraSAR-X data is proposed. To develop the method, machine learning algorithm, a branch of artificial intelligence (AI), is applied. We focus on the multiple bounce reflection which is a specific feature on Synthetic Aperture Radar (SAR) data to estimate building devastated areas. Finally, classifiers which enable automated classifications of damage patterns into predicted damage classes were built. The evaluation of the model was conducted through cross-validation and the best accuracy was obtained as 89.2 %.

抄録全体を表示

This paper introduced characteristics of the offshore waves and vertical buoy motions observed by the two sets of the GPS buoy installed at the Northern Pacific Coast of Japan. Wave heights are computed by observed vertical buoy motions obtained RTK-GPS system. However, the vertical response of buoy motions are not taking into account in the computation wave height. Authors show observed wave height is not correct when significant wave periods less than 6.0 s. Then, in this study,modified wave height is proposed taking into account the wave response of vertical buoy motions when significant wave height are less than 6.0 s.

抄録全体を表示

Blue tides, upwelling of anoxic waters, have been a serious environmental problem in Tokyo Bay. It is essential to figure out the behavior of the blue tide distribution occurrence area. To observe the blue tide distribution, the variation of the optical properties for the blue tide was investigated by measuring the backscattering coefficient, the light absorption coefficient and the remote sensing reflectance. Based on the results of the optical properties, we developed the estimation model for blue tide distribution. It was helpful not only monitoring extent of the distribution but also identification of the upwelling region of blue tides because it is able to express color strength of blue tide. In addition, estimated blue tide distribution was verified by 3-dimensional numerical simulation and the reason of the upwelling was understood.

抄録全体を表示

A rapid damage mapping with remote sensing and geoinformatics is essential for effective disaster response and recovery efforts. Among the remote sensorsSynthetic Aperture Radar (SAR) is remarkable for its capability to observe the Earth's surface regardless of wheather conditioins. In this paperin order to acquire the mea- sure of building damage level in the tsunami-affected areasthe authors analyzed a set of pre- and post-event TerraSAR-X intensity images. Focusing on the difference (d) and correlation coefficient (r) between backscat- tering coefficients of pre- and post-event images yields good estimation of structural damage with a form of discriminant regression function of d and r, with the accuracy of more than 70 %.

抄録全体を表示

When natural disasters strike,such as tsunamis or floods, people are sometimes isolated in disaster-affected areas. In this study, the authors propose a method of searching survivors with UAV (Unmanned Aerial Vehicle) to show usefulness and problems when applying to search and rescue operations. First, with the help of the UAV, they took pictures of humans surrounded by conditions similar to disaster-affected areas. Second, they explored possibility of human detection from those images, using object-based image analysis. Through the study, they found that their UAV observation potentially works well for searching survivors in disaster-affected areas.

抄録全体を表示

The experimental data about interacted dynamics between discrete sand and fluid is required for sophistication of the numerical simulation, however the simultaneous measurement method of dynamics of a sand particle and fluid is not yet established. This paper concerned with the fundamental experiment in view of the sediment transport process due to tsunami, particles and fluid were identified based on the particle projected area in the analysis process of Particle Tracking Velocimetry. As a result, particle velocity is lower than the fluid and it is pointed out that the particles are more active regarding the velocity fluctuation of a vertical direction. In particle concentration distribution, it is suggested about the dynamic characteristics of particles based on consideration by the applicability of the Rouse profile that bed-load transport is superior.

抄録全体を表示

This paper presents a novel physical simulation method for tsunami inundation flow with arbitrary flow velocity and inundation depth, which consists of steep front wave, super critical flow, and subcritical flow. In this method, an underflow gate, an overflow gate, and a valve are dynamically controlled to generate arbitrary flows in an experimental flume. Before an experiment, in order to control arbitrary flow velocity and depth at test section, temporal movement of the gates and valve is calculated by numerical calculations of open channel flows. The physical simulation method is verified by an experiment using a Froude scale model of a past tsunami. The result shows that the method is capable of reproducing arbitrary flow velocity and inundation depth of a scaled tsunami.

抄録全体を表示

Red tides off the Japanese coast caused serious damages to aquaculture industries in every year. To reduce fisheries damage due to red tide, it is important to inform short-term scale distribution of red tides for fishermen. We developed a system monitoring data of red tides in real-time. Our system can obtain data from a buoy drifted on the sea. The buoy has a GPS and two sensors that measure temperature and brightness, and can connect to the Internet using mobile phone network. This paper describes a construction of our system, and results from observation in Yatsushiro Sea. According to our results, we could obtain measured data from the buoy in the middle of Yatsushiro Sea, and it was found that movement of the buoy mainly driven by tides current, rather than wind.

抄録全体を表示

This study aims at developing a visualization system of coastal disaster risk which provides static and dynamic information so as to enable to intuitively understand disaster characteristics and its risk. The static information was offered by a web application with Google Maps API. The dynamic information was visualized utilizing three-dimensional animation techniques and a three-dimensional geographical information system with actual image. The utility of the system was confirmed using the tsunami simulation results by Kawasaki et al. (2012). The results showed that the system was capable of providing useful information for considering coastal disaster risk such as tsunami, storm surge and so forth.

抄録全体を表示