This paper explores aggregation of the total infiltration in an inhomogeneous area where infiltration parameters are distributed. The aggregation criteria of the infiltration are introduced based on Philip's equation for five parameters and they are expressed as an inequality of second polynominals of the aggregation index for infiltration introduced here. Using these criteria, the aggregation of the distributing parameters was conducted respectively. Observed hydraulic conductivity and initial saturation degree are difficult to aggregate by the mean parameter method, however the mean values of the other parameters provide better results without taking into account of the distributions.

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A computational method for two-phase flow with moving boundary is presented, in which the GAL (Grid-Averaged Lagrangian) model is used to track the moving boundary. To avoid numerical instability due to high density ratio between the phases, the motion of each phase is separately treated. The accuracy of the GAL model is examined for the capture of the moving boundary and the curvature of the interface through computation for simple cases of moving boundary problems. The comparison between the computational results obtained by the GAL model and those by the previous models indicates that the GAL model has relatively higher accuracy. The present method is applied to the computations for broken-dam problems and a falling droplet problem, showing that the present method gives good agreements with the previous experimental and computational results.

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Some features of scouring and flow at spur-dike-like structures are discussed based on experiments under clear-water scouring. Considering the flow concentration to a restricted region of the scour hole, a simplified analytical model for the prediction of the maximum scour depth at the structures is developed. The model predicts scour depth at sloped-wall as well as at vertical-wall abutments, being verified by the available data and previous formulae. A model constant for flow concentration is identified by the inversion of experimental data. Finally, an interpolated analytical model for the time-change in the maximum scour depth is developed and verified by the experimental data under the higher shear stress condition.

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When the wind blows over the water surface, there occur drift currents and wind waves due to the wind shear across an air-water interface. The turbulence measurements of wind layer and water layer were conducted accurately with a Laser Doppler Anemometer (LDA). The turbulent quantities in the air behave similarly to those in flows over flat plates in open-channels. As for the water layer, wave component and turbulence component were separated by a spectral separation method. Turbulence components show universal characteristics on a 2-D gravity wave. It was clarified that turbulent structures and energy budget on both layers are closely related with each other and also that energy transfer through the air-water interface increases as the wind speed becomes larger. In this study, it was concluded that there exists a close relationship between the wind waves and the turbulent structures across the air-water interface in the laboratory wind tunnel.

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Flow fields of open channel flows with favorable pressure gradients (dp/dx<0) were measured accurately with a laser Doppler anemometer (LDA) and distal-type point gage. The mean velocity profiles of the inner-region and outer-region can not be expressed by the standard log law. However, the mean velocity profiles in the viscous sublayer can be expressed well by the linear formula. Therefore, the evaluation of the friction velocity U by making use of such a linear formula is the most reliable. It should be noted that the turbulent energy is transported back from the turbulence to the mean velocity. Consequently, the turbulent redistribution changes as compared with that of an uniform flow, i. e. non-pressure gradient flow.

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The shear stress distributions in open-channel flows with favorable pressure gradients are predicted by making use of the equation of motion and continuity equation under the assumption that the ratio of the friction velocity U to the maximum velocity U_max is almost constant in the streamwise direction. The values of the predected shear stress are smaller than those of uniform open-channel flows and also decrease with a decrease of the normalized pressure gradient parameter. The predected shear stress distributions are in a good agreement with the experimental values.

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Two new versions of the multi-level models for nonlinear dispersive water, in which vertical profile of horizontal velocity is assumed to be a chain of quadratic portions, are proposed aiming to improvement of efficiency of calculation and applicability to quasi-3-dimensional problem respectively. The properties of the model in dispersion relation and second-order nonlinear interactions are confirmed by comparison with that of the Stokes wave theory. The applicability of the models is examined by reproduction of experimental result for submerged dike and floating body.

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To find the characteristics of short-period variations in the nearshore water environments, and the related crossshore transport process of materials at an open coast in stratified condition, a long-period mooring observation and an intensive survey by means of a research vessel and an observatory pier were performed at the Kajima coast in Japan. The results of the data analysis show that the diurnal variation of water temperature, which is one of the most characteristic features in the nearshore water environment, is induced by the run-up and -down motion of diurnal internal waves at the nearshore region. The internal waves play significant role in the crossshore transport of chlorophyll. a, turbidity and planktonic larvae. The internal waves transport may reach a very shallow water region close to the shore.

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A devasting earthquake; “Hyogo-ken Nanbu Earthquake”, did a great deal of damage to the south area of Hyogo Prefecture. A database on damage to the river structures of the Omoterokko-Rivers is made using the data obtained from the field observations and the specifications of river restoration works. In order to increase the utility of the database, the tabulated informations of the damage are linked with the geographycal informations and the photographic ones. The damage to revetments is analyzed concerning the relationship among the structural type of revetments. the number/length of damaged sites, the damage form of revetments, etc. Collapses of the revetments which appear to be heaviest of damage form have mostly occurred within the disaster belt of seismic intensity 7.

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