A numerical method for hydro-elastic problems was proposed in the present paper. In the method, both fluid and solid phases were described by SPH. We employed the artificial stress proposed by Monaghan (2000) to remove a tensile instability. We also applied to hydro-elastic problems caused by impact pressure due to free surface motion. The present numerical results were in good agreement with experimental results in elastic deformation and stress field. The numerical model also showed the possibility to compute dynamic response and vibration due to wave impact acting on elastic-vertical wall with several material properties.

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There has been a shift in social infrastructure development from quantitative improvements such as efficiency and disaster prevention to those of a more qualitative nature such as amenities, natural resources and the environments. As a result, CVM (Contingent Valuation Method) has been garnering interest as a method to measure the benefits of qualitative objective-oriented projects.
This thesis concretely shows approaches dealing with the extent of aggregation and underscores the need for application of post-project evaluations that has already been in operation in our country.

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It is very important to grasp the hydraulic characteristics of flood flows for the river improvement works and management. This study aims to clarify the propagation mechanism of flood flow in rivers with vegetations. We constructed the model of unsteady quasi-2D flow available for flood flows. By using this method incorporating observed water surface profiles, discharge hydrograph, water storage and propagation speed of flood flow are accurately estimated in compound channels with vegetation. We also derived a theoretical expression for propagation speed of floods and showed that the theory provided a good agreement with observed propagation speed of floods in the Tone river.

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  A new method of flood control by dam gate operation based on runoff characteristics of a basin and nticipatory release is proposed in this paper. In order to consider the several limitation conditions related to the law, capability of discharge gate and flood condition at down stream of river, preparation time for the gate operation and increase rate of river water level at the target points were taken into account as the anticipatory release. It was found, that it is necessary to reduce the preparation time in operating the gate, as an effective flood mitigating measure. Further more, reservoir stage can be recovered to the normal water level after flood event by the use of anticipatory release considering the initial loss for the initial reservoir stage which is lower than normal water level before flood event.

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  Main purpose of this study is to evaluate the erosion rate of cohesive sediment. More than 100 experiments were conducted in a closed conduit, and the test sample was the mixture of kaolin, silica sand, the composition of which was a variable. It was found from this study that a frictional velocity of flow, a water temperature and a water content ratio are the most dominant factors, and the amount of sand or gravel and its grain size contained in the sample, on the other hand, are independent of the erosion rate approximately. Erosion rate formula was derived in this study on the basis of the experimental results. Erosion process was also investigated qualitatively through an image processing.

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  This study addresses procedures for identifying flood-related sedimentary features in view of their future incorporation into community-based hazard mapping. The pilot study area selected is a 400m-wide floodplain to the left of the main channel of the Uji River. The flood-related subsurface features there (such as old river channels) were investigated using non-destructive geophysical explorations, specifically in terms of resistivity prospecting as well as surface-wave seismic profiling. Their validity was examined against extensive surveys by automated Swedish weight sounding. Furthermore, three columns of continuous sediment cores were retrieved from the floodplain, offering “ground truth” through precise facies observations.

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An inflow into the dam reservoir is estimated from a time variation of the hydrostatic water level. Therefore, a noise of the water level time series data originated from a water surface oscillation cause an oscillation of estimated inflow. In Jinzu river, it is confirmed that river discharge is different from outflow from a dam above the river discharge observation station at flood time. But, this problem was not able to explain by the noise in time series of water level.
The accurate outflow from dam is able to estimate by considering the effect of velocity head. The outflow corrected by velocity head is evaluated by analysis using unsteady flow model. These results is able to indicate that the difference between river discharge and outflow of dam is derived from estimation error of outflow.

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