Breakwaters which decrease a tsunami height at baymouth effectively protect bay areas against tsunami damages around the ria coastal line. On the other hand breakwaters have possibilities to harm a water quality environment due to the reduction of water exchange. This study quantitatively evaluates contradictory capabilities of tsunami protection and water purification by tsunami and flow-diffusion simulations. And the method to plan the breakwater construction is proposed.

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 The hydraulic model test was conducted to evaluate the tsunami wave pressure acting on the facility (wall type and bank type) on the embarkment. In the wall type test results,
 1. Tsunami wave pressure is hydrostatic.
 2. Sustained tsunami wave pressure is dominant(in 20, 15min long-period tsunami). Impact tsunami wave pressure occurred (in 10min short-period tunami).
 3. The tsunami pressure coefficient turned out synonymous with the results(proposed byAsakura et al(2000)).

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 Most of coastal structures, especially coastal dikes were destroyed by the 2011 Tohoku Tsunami. It was reported that one a the most important causes was the failure of back slope due to scouring. It is assumed that understanding the relevance between external forces and structure types is important to study robustness of coastal dikes toward the tsunami. In this study, a numerical model using CADMAS-SURF/3D has been applied to consider mechanism of robustness and to make suggestions for design of coastal dikes. As a result, it was clarified that the weak points of coastal dikes were the scouring at the toe, and the negative pressure at the top of the back slope. To deal with these issues, it is considered to be effective to design the dikes without parapets to lower the overflow depth, and to make the back slope moderate to remove the negative pressure at top of the slope.

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 To mitigate tsunami disasters, it is important to prepare for the tsunami overflow. In this study, wave flume experiments and numerical calculations were conducted to examine the characteristics of tsunamis overflowing parapets.
 The results of the experiments were 1) the maximum water surface elevation in front of the parapet was almost equal to the incident tsunami wave height, and 2)when the tsunami wave height was 2. 2times higher than the crown height of the parapet, the ratio of the measured water particle velocity to the analytical one was maximum. And the calculation results showed that the slope gradient of the revetment did not have a significant influence on the overflow depth.

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 The reduction of tsunami inundation flow and tsunami force by a porous vertical barrier installed on a seawall was investigated to give a better understanding of effects of coastal structures on tsunami hazard mitigation. Laboratory experiments of permeable and impermeable wave barriers exposed to breaking bore were carried out to examine variations in wave height amplifications, inundation flows and wave forces acting on barriers. It turns out that the porous barrier can reduce the inundation depth and discharge effectively. The reduction effects on the inundation depth and discharge are mainly governed by the porosity of barrier and the relative tsunami height to barrier height. The reduction of inundation velocity is less than that of inundation depth. When tsunami height in front of a porous barrier is between 0.5 and 1.0 with respect to barrier height, the wave force acting on the barrier can be significantly reduced in comparison with that of the impermeable barrier. This is because that the reduction of wave force is influenced by variations in tsunami height in front of the porous barrier.

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 The fluid forces acting on a cylindrical structure in inundation flow were measured by using a multi component load cell. The time variation of typical principal velocity and water depth of coming inundation flow were also measured exactly by using laser doppler anemometer and wave gage. The drag coefficient of cylindrical structure in inundation flow decreases with increase of instantaneous fluid number of coming inundation flow. This phenomenon is quite similar to the relationship between the drag coefficient and fluid number of cylindrical structure in uniform flow in open channel.

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 Hydraulic experiments are conducted to investigate tsunami-induced wave force acting on the superstructure of a bridge and its effect on the motion of the superstructure. In the hydraulic experiments, a long-period wave without wave breaking are generated against a movable model of the superstructure to determine whether it moves or not and a fixed model of the superstructure to measure tsunami force and wave pressure acting on it. From experimental results, it is found that the horizontal component of the tsunami force can be evaluated using the drag force calculated from the flow velocity at the seaward surface of the superstructure model, and the vertical component of the tsunami force is overestimated by the buoyancy force calculated from the water surface elevation at the position of the superstructure model. Furthermore, it is revealed that whether the superstructure model moves or not and the time of the initiation of its motion can be evaluated by a comparison between the horizontal tsunami force and the static friction force considering the vertical tsunami force, suggesting that the consideration of the vertical tsunami force in the static friction force is essential when assessing the motion of a bridge superstructure.

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 The fluid force and the pressure acting on the model bridge deck with the concave cross-section are measured in a two-dimensional wave flume. The magnitude of the maximum pressure acting on the underside of the model bridge deck with the concave cross-section depends on the occurrence of the wave breaking in front of the model bridge. Bagnold-Mitsuyasu model is applied to estimating the maximum pressure in the case where the air under the model bridge deck is compressed. The magnitude of the maximum pressure acting on the seaward side of the model bridge deck with the concave cross-section is similar to that of the model bridge deck with the rectangular cross-section.

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 The understanding of interactions between tsunami and structure is very important to consider tsunami countermeasures, though the interaction includes complex phenomena. For example, two-phase flow can be found when the tsunami hits a bridge structure with entrapping air beneath it. The air sometimes affects forces acting on the bridge, and the effect of entrapped air has to be taken into account to investigate the tsunami forces. This study is intended to investigate the tsunami forces acting on the bridge with using two-phase flow model. Three bridge models were tested in this study, where the slab bridge without girders beneath it, the slab with two girders, and the slab with three girders. The simulation results were compared with the results obtained from one-phase flow simulation, and also verified with experimental ones. This study revealed that, in the investigation of tsunami forces acting on the slab bridge without girder, the results of both one-phase simulation and two-phase one agree well with experimental results. In the simulation on the slab bridge with girders, the results from two-phase simulation correlate better with experimental results in comparison with the results from one-phase simulation. Furthermore, the entrapped air between girders highly affects the characteristic of uplift force.

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 When the 2011 off the Pacific Coast of Tohoku Earthquake occurred, an associated tsunami struck the coastal area and a number of river structures were damaged. Two spans out of three of the Yanoura water-pipe bridge (Kamaishi city, Iwate Prefecture) were washed away by the tsunami. For prevention of important infrastructures such as water-pipe bridges, it is nessesary to reinforce them against tsunami. Therefore, detailed examination of tsunami attack on the Yanoura water-pipe is important. In this study, a vertical two-dimensional numerical simulation was applied to two longitudinal river profiles, focusing on the effect of the distance between the water-pipe and Yanoura road way bridge which is located just downstream of the water-pipe bridge. The results obtained in each case are compared in regard to horizontal forces, vertical forces and torque. According to the comparison, the effect of these forces upon the damage of water-pipe is discussed. As a result, it is suggested that an especially large torque contributed most considerably to the damage causing the water-pipe to be washed away. For verification of the results from 2D analysis, three-dimensional numerical simulation was also conducted. It is concluded that 2D analysis is sufficient to estimate the wave forces in each case.

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 The effectiveness of countermeasures to prevent the tsunami-induced motion of a bridge superstructure are investigated in terms of tsunami force acting on the superstructure using a three-dimensional coupled fluid-structure-sediment interaction model. Numerical results show that fairings attached to the side of the superstructure and fenders fixed beside the superstructure reduce the horizontal tsunami force acting on the superstructure regardless of the configuration of the fairings and the height of the fenders. In addition, the fairings with the surface facing upward result in an increase in the downward vertical tsunami force and accordingly an increase in the static friction force. From these results, it is suggested that the fairings with the surface facing upward would be an effective countermeasure to delay the initiation of the motion of the superstructure. In contrast, the fairings with the surface facing downward reduce the static friction force, and accordingly the motion of the superstructure begins earlier than that for no fairing. The fenders also reduce the static friction force regardless of the height of the fenders. However, the fender with the same height as the superstructure would be effective to prevent the motion of the superstructure because of a significant reduction in the horizontal tsunami force.

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 Water-level difference induced by tsunami generates seepage flow in a mound of breakwaters. This flow encourages soil piping and/or boiling in a mound, and scour of original ground. The present paper describes the stability of the foundation of breakwaters subjected to seepage flow by using a technique of a centrifuge test. The similarity rule on seepage in a centrifuge was discussed, followed by seepage flow tests. The review of similarity rule demonstrated that centrifuge model tests could simulate the behaviours of piping and boiling. Then, seepage flow tests were conducted, and resulted the occurrence conditions of piping and boiling.

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 Water-level difference induced by tsunami generates seepage flow in a mound of breakwaters. It has been pointed out that the flow weakens a bearing capacity of a mound. The present report describes bearing capacity properties of a mound under seepage flow, by using centrifuge model tests and finite element method analyses. Two types of model tests were conducted in the study: horizontal load tests and combined tests with horizontal load and seepage flow. According to the model tests, seepage flow resulted in a slight decrease of a bearing capacity. In addition, it was confirmed that finite element method analyses could simulate the model tests, and a bearing capacity was also reduced by seepage flow in a commonly-used breakwater as well.

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 Many breakwaters suffered from the huge tsunami caused by the East Japan great earthquake disaster in 2011. It is reported that harbor side mound scoring by the tsunami overflow was one of the main causes of collapse of breakwaters. In this paper, we examined the differences of conditions when collaping occurred and did not occur by hydraulic model tests.We showed the ramming down angle of overflow and the point of action to breakwater mounds de-pended on water depth of overflow. And the most dangerous water level was not necessarily the peak level. In addition, we showed the coping of mounds had big effects in collapse of breakwaters.It is very important to know the most dangerous water level precisely in examining countermeasures for preventing harbor side mound scoring by tsunami overflow.

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 A new tsunami overflow-seepage-coupled centrifuge experiment was developed and applied to the problem of mound scour with high-resolution image analysis. The results demonstrate the way in which the scour front developed accopanying progressive slip failure of rubble mounds at the vicinity of caissons. It is found that the coupled overflow-seepage promoted the development of scour significantly. Furthermore, the results show the occurrence of washout and boiling as a consequence of the coupled overflow-seepage, yielding a cavity formation beneath the caissons. These findings will facilitate better inspection and improvement of the stability of rubble mounds of breakwaters.

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 The mechanism of a decrease in wave pressure at the landward side of a caisson on a rubble mound during tsunami overflow is investigated using a coupled fluid-structure interaction model. Numerical results show that the wave pressure acting on the landward surface of the caisson after the onset of the overflow is overestimated by the hydrostatic pressure calculated from an elevation in the water surface. This discrepancy is caused by vortices formed by the separation of the flow. Furthermore, a temporal decrease in the wave pressure results from an increase in the flow velocity. Based on the numerical results, an approximation equation is proposed to predict the reduction rate of the wave force acting on the landward surface of the caisson from water surface elevations at the seaward and landward sides of the caisson.

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 Flap-gate tsunami breakwater, which lies down on the seabed and rises up with its buoyancy in occurrence of tsunamis has been developing. Flap-gate usually has buoyancy and mooring systems keep it lying down so as to shorten a rising time after earthquakes. Dynamic mooring forces of the gate have to be estimated to design these systems since they have to support wave pressure acting on the lying gate in addition to buoyancy of the gate. This study evaluated these forces through model experiments, field experiments, and calculation using equations of motions of the gate. As a result, it was confirmed that the mooring system that allows slight motions of the gate reduced mooring forces, and a method to estimate these forces was obtained. We can realize reliable coastal structures against tsunamis by using this result.

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 A numerical model based on Reynolds Averaged Navier-Stockes (RANS) equations was developed¹⁾ to account for the effects of wave-induced turbulence. In this study, a NEWFLUME model is applied to simulate the recent Great East Japan Earthquake and Tsunami 2011. A series of numerical experiments, which has topography similar to Sendai Coast in northeast part of Japan where was severely damaged from the 2011 Tsunami event, were carried out to investigate the sensitivity and effects of the shore-parallel canal in reducing tsunami energy. Numerical results show that the Kita-Teizan Canal which is parallel to the shoreline in Sendai Coast has significant effect in reducing tsunami energy and plays an important role in the mitigation of tsunami impacts.

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 In this study, the applicability of tsunami force estimation formula for a three-dimensional structure such as tsunami evacuation building is discussed. For the different values of blockage ratio, structure interaction with tsunami, generated using dam break scenario, was examined. It was found that the tsunami action mechanisms for both two-dimensional and three-dimensional cases are quite similar and tsunami force acting on the structure reaches its maximum concurrently with the maximum tsunami inundation depth in front of the structure. Further, wave pressure distribution indicated a closer profile to the hydrostatic pressure distribution. The applicability of the suggested formula to estimate the tsunami force acting on a three-dimensional structure is verified.

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 To enhance the tenacity of buildings located along coasts such as tsunami evacuation buildings, the effectiveness of small-scale countermeasures that can be constructed by their administrators is investigated using a coupled fluid-structure-sediment interaction numerical model that can compute air-water two-phase flow. The investigation focuses on an impermeable tsunami-resistant wall at the seaward side of a building as the countermeasures, and generates a single leading long-period wave against the building with the wall. Numerical results show that the maximum tsunami force acting on the building can be overestimated by the resultant force of hydrostatic pressure calculated from the maximum inundation depth in front of it, suggesting that the numerical model is a useful tool to evaluate the maximum tsunami force using the vertical distribution of the wave pressure. Furthermore, when the wall is placed in the vicinity of the quay wall, a higher wall can effectively reduce the tsunami force acting on the building. In contrast, when the wall is placed in the vicinity of the building, it can be effective to shorten the wall in terms of the reduction in the tsunami force. In addition, the wall can delay the impingement of the tsunami and the onset of the maximum tsunami force for large tsunami height. From these results, it is demonstrated that the construction of the short wall near the building would be an effective countermeasure.

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 Hydraulic experiments were conducted to estimate tsunami wave pressure acting on a land structure placed in front of steep slope. The vertical distribustions of wave pressure acting on each side of a rectangular structure were measured. In the case of the structure located far from steep slope, impulsive pressures on the front and rear sides of the structure were caused by incident and reflected waves, respectively. On the other hand, pressure acting on each side of the structure near the steep slope was found to correspond to hydrostatic pressure due to the inundation depth.

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 The probability of simultaneous occurrence of tsunami and storm surge is small. Once it happens, however, the impact could be enormous. This study considers the joint probability of the two phenomena in terms of a probabilistic hazard analysis. A probabilistic typhoon model is used to simulate long-term storm surge time series, then the probability distribution of tide and storm surge is produced. Tsunami exceedance probabilities are set hypothetically by tsunami heights and return periods. Then the overall exceedance probability considering tsunami, tide, storm surge, is calculated. We argue the probability level at which the effect of storm surge is significant, and we also test the effect of tsunami height characteristics on the relative strength of storm surge effect.
 Evaluations are performed at Nagoya and Maizuru. In the scope of the present study, the probability level of significant effects of storm surge by simultaneous occurrence of tsunami and storm surge is calculated to be several magnitudes smaller than the occurrence probability of tsunami.

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 Earthquake occurrence probabilities are estimated with the Gutenberg and Richter relation for 5 regions in and around Japanese archipelago. We devided the Japanese islands into 5 regions considering geotopography, geology and plate boundaries to apply the Gutenberg and Richter formula and to estimate the earthquake occurrence probability. As a result, an earthquake with M=7.5 in the eastern margin area of the Japan Sea has a return period of 284 years. The tsunami magnitudes also were estimated from tsunami run-up heights of historical tsunamis by using the Abe's relation. A tsunami generated in 1741, in Kanpo Era, found to be the tsunami magnitude M_t=8.4, and the largest tsunami of the Japan Sea.

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 This paper presents a study on influences of computational conditions on numerical simulation of Tsunami generated by the 2011 off Tohoku-Pacific earthquake. In Tokyo bay, the characteristic reaction of water elevation to the Tohoku tsunami was studied. A relationship between the own natural period of Tokyo bay and the wave period of the tsunami was discussed. Two points on computational conditions are dealt with for the comparison of computational accuracy. The first one is the difference of shape of the initial wave, i.e. difference of the fault models. The second one is the difference of area of computational domain. Each of computational results were compared with observed water elevation in Tokyo bay. Influences of the differences on the accuracy of the tsunami simulation in Tokyo bay were declared from results.

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 The 2011 Tohoku earthquake tsunami caused widespread and serious damage especially to the coastal areas in the Tohoku region. While a number of hydrographic observation facilities were damaged, there exist movies capturing tsunami propagation and inundation, which are considered to be useful for obtaining hydrographic properties of tsunami behaviors. Many of the studies using moving images, however, have mainly focused on determining velocities of tsunami runup or backrush on lands because of their availability and relatively easy manipulation. In this study, we tried to estimate time series of velocities of the tsunami in Ofunato Bay, using a movie that captured the first tsunami wave attack. Time series of the original images were converted to images of brightness values and then their distortion corrections were made using our field survey data. The maximum uprush and downrush velocities of the first tsunami wave were estimated at approximately 6 m/s.

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 This paper presents the results of statistical analysis of measured tide level and numerical simulation of the secondary undulation by using the characteristic method induced by Tsunami at Hinase harbour in Okayama prefecture. Tsunami generated by the earthquake at the offshore of Chile on 27th January 2010 and the offshore of Tohoku on 11th March 2011 propagates to Seto Inland Sea, the secondary undulation is observed at Hinase harbour in Okayama prefecture. In 2010 and 2011, the maximum sea-level departures at Hinase are 0. 53 m and 0. 47 m, respectively. According to the spectral analysis, wave energy that wave period is about 39-93 min is large. The calculated root mean square of sea-level departure at Hinase is about 0. 23m and 0. 16m in 2010 and 2011 respectively, these values are equal to the observed ones approximately. In 2010 and 2011, the calculated root mean square of sea-level departure at Hinase is about 3 times as much as the observed one at Himeji harbour, so the resonance phenomenon is significant.

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 This study investigates water-level oscillation and ice breakup in the Lake Akkeshi by the tsunami caused by the 2011 Tohoku Pacific-Coast Earthquake. We conducted 2D numerical analysis in order to simulate the tsunami intrusion into the semi-closed lake and temporal and spatial water-level fluctuations are clarified. Then we measured the sizes and areas of lake ice by GIS analysis to compare these with the results from other sea ice size measurement and attempted to clarify the difference in sizes from ice formed in sea ice zones. The importance of significant effect of tsunami intrusion on lake ice breakup is elucidated.

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 Many breakwaters were damaged by the 2011 off Pacific Coast of Tohoku Earthquake Tsunami. Especially the breakwater tilted or turned over due to scour at the rubble mound of the breakwater head and a lack of bearing capacity.
 In this study, in order to discuss the stability of the breakwater head, centrifuge model tests to simulate tsunami flow and a numerical analysis using CADMAS-SURF/3D were conducted. As a result, the rubble mound was enormously scoured due to tsunami flow. In addition, it was shown that the area of scour was predicted with the flow velocity distribution in the numerical analysis and the estimation formula for the stability of the rubble mound.
 Moreover, in this study, some preventions against scouring were suggested and the effect of them was velified by model tests. According to results of model tests, in case of covering over the surface of the rubble mound with the units packed gravels and installing the L-shape block at the corner of mound, it was revealed that the prevention was significantly effective although the rubble mound was partially or locally damaged.

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 Many breakwaters were damaged due to the 2011 Tohoku Earthquake Tsunami. The authors have conducted a field survey, and found that damage to the caisson-type breakwater was limited where friction-increasing asphalt mat (herein after referred to as FAM) was used. In order to investigate the resistance performance of FAM against tsunami wave force, a series of hydraulic model experiments were carried out. The remarkable findings are stated as follows. 1) Caissons with FAM can resist larger tsunami wave force compared to those without FAM. 2) In case that FAM is not in use, caisson sliding occurs immediately after caisson starts to move. In contrast, when FAM is installed, caisson moves gradually in proportion to water level increase before sliding. This suggests that FAM can increase toughness of caisson-type breakwaters. 3) The reinforcement block has the ability to increase the resistance force against caisson sliding, especially when it is laid on FAM.

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 This study conducted hydraulic experiments to clarify effectiveness of reinforcement for breakwater stability against abnormal tsunami which exceeds the expected level, seen in the Great East Japan Earthquake Tsunami on 11 March, 2011. Though increasing the width of counter mounds reinforcement can reduce displacement of breakwaters, increase of the height of reinforcement is simulteaneously needed against abnormal tsunami. The resilience of breakwaters differs even if the safety factors of breakwaters are the same for tsunami. The formulas to evaluate the horizontal displacement of breakwaters based on their safety factors against tsunami were proposed from the experimental investigation.

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 Rubble mound cover on the harbor-side of a breakwater using filter units is one possible method to reduce construction cost in countermeasures against tsunami. Hydraulic model experiments were conducted to clarify effective layouts of filter units against tsunami overflow. Filter units proved to be more stable than armor stones. A single-layer placement of filter units, partially overlapping enhanced the stability limit compared to without overlapping. Multi-layer placement delayed the progress of damage. Connecting filter units not only enhanced the stability limit, but also slowed progress in damage. Restraint of stone filling movement by connecting the top and bottom of the units improved stability against tsunami overflow.

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 A lot of properties and lives were lost by the 2011 Tohoku Earthquake. In addition, a large tsunami breakwater (e.g. Kamaishi Port) as well as many breakwaters were collapsed by tsunami attack. There are few studies to clarify the the failure process of composite beakwater consisted of a caisson and mound accompanying with large deformation. In this paper, we developed a numerical model that can analyze the large deformation of composite breakwater using DEM, and confirmed the applicability of numerical model by comparing experimental results and numerically simulated ones. It was found that the discontinuity of friction coefficient is one of important factors for reproducing the tilting and sinking of caisson and mound deformation.

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 Historically, tsunami disasters have been repeated on the Japan Sea coast. Among them, this study focuses on tsunamis that have caused various damages to the Noto Peninsula, Ishikawa, Japan. The propagation of four representative historical tsunamis that originated in the eastern margin of the Japan Sea were simulated on the basis of the Nonlinear Shallow Water Equations. The applicability of the numerical model was verified through comparison with historical records and NOWPHAS observation. Good agreements were obtained. The numerical results for the tsunamis show the occurrence of strong refraction off the Noto Peninsula, which caused significant concentration of tsunami energy.

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 Housing Bureau Ministry of Land, Infrastructure and Transport has proposed building behind obstacle is two times the hydrostatic pressure of the wave height. In this regard, the present study examined the tsunami load acting on the building behind a obstacle from numerical experiments by MPS method. MPS method is a type of particle method. From the re-sults obtained, we have examined the proposal of the Housing Bureau Ministry of Land, Infrastructure and Transport.
 As a result, even in the case of bank overtopping, a=2.0 is effective even behind a seawall. In addition, in the case of the pitch of building is 15m or less, tsunami load is significantly reduced by building on the front.

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 Tsunami-induced local scouring around a movable inland structure on the sand bed is investigated using a three-dimensional coupled fluid-structure-sediment interaction model in terms of the displacement of the structure. From a comparison with experimental data, it is found that the water surface elevation and the bed profile change are predicted reasonably well regardless of the absence or presence of the drawdown. Moreover, the bed profile change at the seaward and landward side of the structure is less affected by whether the calculation of the motion of the structure is implemented in the model. However, it slightly affects local scouring around the seaward corner of the structure because the displacement of the structure changes the flow field around the structure. This suggests that it is essential to consistently calculate the motion of the structure when assessing local scouring around movable structures.

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 We reviewed some damage cases in the past years by tsunami wave with sea ice floes. We also made model experiments on tsunami inunduation flow with sea ice floes in urban area, and examined the additional potencial risks against dameges by tsunami with sea ice floes. After the collision force of ice acts on structures, inunduation flow could be damed up due to the formation of Ice-jam between structures, and relative great force also acts on the structures because of water level rise in front of the structures and because of static water pressure between the structures due to the Ice-jam, and this steady state remains for some time. Further, in light of tsunami evacuation, it was presumed that we should move to higher places of evacuation facilities than usual due to the water level rising and the pile-up by ice floes.

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 The Meiwa tsunami is well known around the world due to the extensive research done in this area. However researchers, Kawana and Nakata and others, suggested that there might have been a larger tsunami before the Meiwa tsunami according to research done on the age of the Tsunami-Ishi. Contrary to the existing explanations on pre-historical tsunamis in the Ryukyu Islands, this research discloses that there are no profound or consistent traces of other tsunamis occurring in the region other then the Meiwa Tsunami.

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 High-quality maintenance of seawalls and cut-off structures by which the contaminated water is stored is strongly required so as to preclude it from leaking into surrounding sea. This paper describes the status-quo of maintenance of waste reclamation sites by means of in-situ survey most all over Japan.
 Taking the facts described from the above survey into account, in case of failure of cut-off structures, which are usually made of geo-membrains or steel sheet piles, seepage and advection-dispersion phenomena are analyzed by using Eulerian-Lagrangian finite element method in order to clear the environmental risk on surrounding sea of waste reclamation sites.

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 The field observation and the numerical model study was carried out to comprehend the sea-cultivated sediment particle behavior. It became clear that the curled up soil particles were transported downstream and diffused to the water mass. From the hydrodynamic model including turbidity calculation, the distribution of sediment particle was strongly effected by the seabed topography and the operation of sea cultivation during the flood to high tide on the spring tide period was efficient at the Ieshima Islands.

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 In Hasunuma Seaside Park Pond where is located on the seafront Kujyukurihama coastal line in Chiba, water bloom has occurred in the past, the deterioration of the landscape and odor problems occurred. Dominant species of this Aoko are Cyanophyceae Anabeana spiroides. It has a feature called nitrogen fixation air, the explosive growth can be as long as there is phosphorus in the water. In this study, the shell collected from sandy beach on Kujyukurihama coastal line was applied as regional unused resources for nutrients remove by phosphorus adsorption. In a restraint rate of phosphorus, 30-40% of suppressant effects were seen. In the COD restraint rate, an increase of the phytoplankton was controlled by having sprayed a shell. Therefore, it showed a high price as quantity of dispersion increased.

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 Flow rate measurement and monitoring of water quality were conducted to reveal characteristics of coastal groundwater at intertidal zone in Matsugaura Beach, Kagoshima Prefecture, Japan. The coastal groundwater flow rate was estimated as much as 12.6m³/day. Nutrients supply by the groundwater was estimated as 45.7g-N/day and 0.5g-P/day. Soil around a study site is of volcanic debris and hinterland is classified as welded tuff. Due to high permeability of the soil, reasonably warm climate, high rainfall, and much utilization of fertilizer to tea filed, local groundwater contains concentrated nitrate and low pH value. It is shown that the coastal groundwater contains concentrated nitrate (300μmol/L) and low pH value (6.3). In addition, salinity of the coastal groundwater is 0.1‰ to 2.9‰. Therefore, it is evident that the coastal groundwater affected less by sea water at this area.The results show that the coastal groundwater is a key mechanism to supply into a coastal zone and maintain the local ecosystem.

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 A water budget method is applied to estimate the freshwater discharge rate and volume in the Fukiagehama area(watershed basin). An average rainfall in the basin is approximately 2,200mm, and is greater than the national annual average rainfall. Based on the average value of the basin, the river flow is 29.7%, the groundwater flow is 36.6 to 37.8% of the total amount of rainfall, and the rest is evaporated. Therefore, the river flow is 44%, the groundwater flow is 55.3 to 56% of the total amount of runoff. Due to the large amount of rainfall and soil condition (much volcanic debris, SHIRASU) for which a permeability is high, estimated quantity of groundwater can be large as 5.6×10⁷m³/year. Even though a macroscopic estimation, the groundwater flow is secondary important as a nutrient supply mechanism in the Fukiagehama basin.

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 The objective of this research is to examine the possibility of water quality monitor in Lake Koyama-ike, Tottori Prefecture, just after brackishing lake water on March 12, 2012. Authors discussed about the relationship between the relationship between spectral reflectance and water quality (Chla: Chlorophyll-a) in the lake based on the field survey of 3 time in 2012. As a result, the following matters became clear. First, the the spectral-reflectance characteristic was shown as that of typical eutrophic water area. Next, the optimal model for Chla estimation in the lake by remote sensing technique was "reflectance ratio between 672 nm (±about 5 nm) and 704 nm (±about 5 nm). Moreover, the significant correlation between "the reflectance ratio between 659 nm (red band) and 724 nm (rededge) of WorldView-2 satellite" and "Chla" was obserbed. Although it was very difficult toestimate Chla in the lake from the results using a simple reflectance ratio model in the present satellite, when using hyper-spectral (HS) sensor which is due to be launched in the near future, Chla estimation in the lake was possible.

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 In the port and coastal construction projects, there is environmental research for environmental assessment. However, the investigation time is often limited for cost and process. In this study, a proposed method using a HEP the following conclusions were obtained. The adhesion of sessile organism and their habitat was affected by waves and tidal fluctuations. The model can reproduce the number of sessile organism by applying the relationship between tidal fluctuations and the number of sessile organism. It can also apply into the environmental assessment evaluation, in the port and coastal construction projects.

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 A harbor water area is calm and precious place to various aquatic lives, but its closure environment often makes water and deposit worse. As one of the measures those aggravation, artificial reefs for waterpurification which uses a shell have been installed in Tsuruga harbor in Fukui pref. In order to quantitatively evaluate the water purification effect of those reefs, we pulled up the test piece through the four seasons, and examined a temporal change by addition to diatoms in the tanks. As a result, the water purification effect was demonstrated by immediate decreasing the amounts of diatoms and organic carbon, and increasing the clarity of the water visually. Although the effect was decreased in low-temperature season, the water purification effect was confirmed through all seasons. Moreover, when those results experimentally calculated to economic effects, with sewage disposal expense, it was corresponded in 4,550,000 yen per year by 16 reefs.

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 In recent years, when constructing structures in harbor, various measures are demanded with consideration for the surrounding ecosystem. We expect a shell substrate is an improvement material since this is good base as habitats for a variety of invertebrate and seaweed. In this report, we tried to visualize the currents around the substrate and measure velocity profiles by the hydraulic model experiment to prove the mechanism. As a result, particles in the drift were taken into aperture of the substrate with the current broken. It is presumed that those processes get boost a variety of invertebrate and seaweed settling down to the shell passing through complicated interior space more efficiently.

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 The authors found that an employment of crushed shells in the lower layer instead of gravel greatly helps to reduce the transport of the finer particles in the upper layer into the lower layer, and to provide an effective function of capillary barriers. In this study, the diversion lengths are measured in the field experiments using crushed shells instead of gravel in the lower layer, and compared it with the estimations calculated by the theoretical equation proposed by Steenhuis, et al. In addition, we compared it with the diversion lengths which were measured in the field experiments using a sand layer underlain by a gravel layer. As the result, the authors make clearly the application of the theoretical equation proposed by Steenhuis, et al. in estimating the divergence length of the capillary barrier.

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 The purpose of this research is to establish the stand-alone power generation system by means of wind power generation in ports and coastal area. It is necessary to know the variance characteristics of demand of electric power in port facilities.
 This paper shows investigated data of electric power usage in a port that is located at the west coast of Hokkaido. The time variance characteristics of electric power consumption in a port are estimated depends on wharf operation data such as cargo handling and refer container in a port.

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 We estimated CO₂ emission caused by port construction based on accounts of all port constructions that Ministry of Land, Infrastructure, Transport and Tourism ran in 2010. Port projects were categorized by structure type, and total construction costs of port project were summed up by structure type. We set unit structures for calculation defined by cross-section view and span, and calculated CO₂ emission and construction cost of each unit structure. Total CO₂ emissions were estimated by multiplying CO₂ emission per cost and total construction cost by each structure type. The results showed that total CO₂ emission of Japan caused by port construction was 960kt. And, characteristics of CO₂ emission per day were drawn by structure type.

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 Balancing a development project with environmental preservation typifies a paradox, especially when the project is for reclamation of the sea surface. Island City Development Project, a project to create some 401-hectare island-shaped land by reclamation at Hakata Bay, and a project to conserve and create the environment of Ecopark Zone, an area of some 550 hectares around Island City which consists of Wajiro Tidal Flat, the shallow waters and shorelines, were both planned as inseparable projects in 1993 and have been under construction until now. The development of Ecopark Zone has been conducted in a manner consistent with the development of the town area of Island City. At Mishima Zone in Ecopark Zone, a number of projects including the improvement of the bottom sediment by sand covering and the shore development have been conducted. In the early planning stages, some residents were concerned about the environmental impact by the reclamation, but the biotope space for the diversified species has been secured and the symbiosis environment for nature and man is being created.

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