This paper describes a physically-based distributed sediment runoff model for flood and sediment movement in a catchment scale. Grid-cell based KWR model simulates overland flows on each grid-cell and transportation capacities for sheet erosion are calculated based on the Unit Stream Power theory to model sheet erosion and deposit. Constructed model is applied to the upper Brantas River basin, Indonesia. The verification indicated that the model reproduces the sedimentation record. Further, the volume of eroded material at the cultivated hillslope of Mt. Semeru is found larger than other parts of the basin, which is analogous phenomenon to the natural physical process of sediment erosion.

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Luai and Fujita proposed a method to determine the equivalent frequency transfer function (EFTF) between rainfall input and runoff from a mountainside slope using several runoff models. To further develop their proposed method, we used the kinematic wave equation as a runoff model and derived a new EFTF between rainfall and runoff from a whole basin. The parameters of the new EFTF are the time of concentration related to average rainfall at slopes and channels. It is shown in this paper that the newly derived EFTF can be approximated by a second- or third- order delay system and that parameters involved in delay systems depend on the river network structure.

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Method of estimating the permeability of a single rock joint is needed to evaluate the safety of the disposal of the high level radioactive waste. In this paper, we derive an analytical solution to fourth order approximation in order to estimate the permeability of a single rock joint. First, we introduced correlation function of aperture distribution as a parameter to affect the permeability, and to express the anisotropy of fluid flow. Then, we solved Reynolds equation as a stochastic differential equation, and clarified the relation between the characteristic parameters of the aperture distribution and the permeability.

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We have developed an image processing method for simultaneously measuring the water-surface elevation and the velocity vectors in open-channel flows. After taking an image in which both the particles in flowing water and the water-surface are visualized, a boundary growing process is employed for detecting the locations of water-surface using the gradient of luminance in the image and a particle image velocimetry is utilized for measuring the velocity vectors in the channel. Then, the present measuring technique is applied to the supercritical flow in the channel with a concave bed. Analysis of the instantaneous data of the water-surface elevation and velocity using the wavelet transform and principal component analysis indicates that there exists the interaction between dominant water-surface fluctuations and organized motions in amixing layer along the concave.

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When the flow of underground diversion channel shifts from the open channel flow to the pipe flow, the air is enclosed in the tunnel. In this study, the effect of the air enclosed in the tunnel on the flow of underground diversion channel was analyzed using the slot model. It was shown that it was necessary to consider the compressibility of the air and the discharge of the air from vertical shaft in order to analyse the effect of the air, and water level of the vertical shaft and pressure in the tunnel increased when the air is enclosed in the tunnel.

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A depth-varying unsteady compound open-channel flow is one of the most important flows in hydraulic and river engineering. So, the hydrodynamic characteristics of these flows have to be investigated in detail. Recently, many researches on unsteady rectangular open-channel flow were conducted intensively and thus the important knowledge and database are now available. However, 3-D structure of unsteady compound open-channel flows is not available as yet because it has been much difficult to measure them even with LDA. In thjs study, 3-D LDA measurements were conducted successfully in depth-varying unsteady compound open-channel flows and then 3-D structures of secondary currents and turbulence were examined.

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Recently it has been reported that a lot of directional random wave groups with multi-peaked spectra are observed at a place faced to an open sea. They considerably affect technical matters like the tranquility in a harbor. However, their occurrence characteristics have been known little. In the present paper, we have investigated the occurrence characteristics of directional random waves off Omaezaki, Gobo and Kochi. Futhermore the meteorological conditions which generate multi-peaked directional random waves are investigated in reference of weather charts. It is concluded that multi-peaked spectra are composed of long and short period waves from the south and wind waves developed around the observation point and affected by circumferential geography.

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An accuracy of the resolution of water surface profile is an essential factor of the analysis of wave breaking and overtopping. The gridless Lagrangian method, which is generally called the particle method, is highly performing tool to describe complicated behavior of the water surface with fragmentation and coalescence of water. In this paper, a wave overtopping process on a vertical seawall is numerically simulated by the MPS, or Moving Particle Semi-implicit, method, which is categorized as the particle method. An improvement of the listing process of neighboring particle is introduced to accelerate the computational procedure of MPS method. Snapshots of the wave overtopping process in the experiments are well reproduced by the MPS method. The predictions of the MPS method of the overtopping quantity agree well with the experimental results.

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This study carried out random wave experiments to examine the characteristics of wave runup on a seawall with shallow foreshore, with and without an artificial reef in front of the seawall. The measured representative runup heights were compared with the predictions by a revised imaginary slope method for runup estimations and by some runup prediction curves. Emphasis was laid on the relation between the predictions and representative runup heights, because the existing runup estimation curves were obtained and formulated by monochromatic wave experiments. Main results are: 1) the runup height distribution follows the Rayleight distribution, 2) the predictions by the imaginary slope method correspond to the upper limit of mean runup heights and the lower limit of one-third maximum runup heights of random waves.

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A 30-year bathymetric data set obtained during and after construction of jetties at the entrance of Imagireguchi Inlet, Japan, was analyzed. After construction of the jetties, the tidal channel deepened. In the first analysis period from 1983 to 1975, shoals formed on both sides of the jetties and moved shoreward. In the second period from 1980 to 1993, however, the shoal on the up-drift side moved seaward Although the accumulation rate on the up-drift side of the jetties decreased with time, the amount of sediment supplied to the down-drift beach did not increase. The volume of sediment stored in the ebb-tidal delta was estimated, and compared with the equilibrium volume.

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In this study, in order to apply Multi-Soil-Layering (MSL) method to direct treatment of river, a demonstration experiment of the treatment of Kumazoe river and the ability of water treatment of MSL system was examined for 1 year from December 2000. The MSL method could treat BOD of 6 to 105mg/l (30mg/l in average) in river water up to 2mg/l in average stably throughout year under the condition with high hydraulic loading rate of 4m³/m²/day. Coefficients for removal of pollutants in river water by MSL system were also determined. Durable years of MSL system until the system cause clogging by the accumulation of mineral SS in river water into the system was estimated more than 20 years.

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The Typhoon No. 18 in 1999 caused serious dameges along the Suo-nada sea in Yamaguchi prefecture. In the present paper, the histories of tidal levels and sea wave induced by the typhoon were simulated with the Myers and MASCON model respectively. The wave presures on coastal dikes at eleven representative points were deduced according to the tidal levels and wave heights simulated for instant of damage. The mechanism of sliding, overturning and cutting of sea walls and coastal dikes was studied on the basis of analyzing variation of tidal levels and wave heights.

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This paper deals with an economic assessment value on time and regional extended effects by a flood mitigation project to give more value than those, which have been calculated with a standard method in feasibility study. The time extended effect is an integrated benefit accumulated capital by flood mitigation infrastructure for long period. The regional extended effect is an integrated benefit accumulated indirect benefit by flood mitigation infrastructure in the wide area under the influence of direct flooded area. Here an old flood mitigation project on the time extended effect in the Kiso River Basin in Japan and a flood control and drainage project in Metro Manila in Philippine on the regional extended effect are studied respectively.

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A solution is derived for dam-break flow over a uniformly sloping bottom, under the assumption that each receding characteristic line of flow is parabolic. The hydraulic resistance of the bottom is not considered in the derivation. The validity and characteristics of the solution are examined through comparisons with Matsutomi's approximate solution under the same flow conditions, and with Ritter's and Peregrine et al.'s solutions. The solution is expected to be useful in examining or solving practical problems in hydraulic or coastal engineering, and any result obtained from it can be easily compared with experimental data.

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