In order to compare the theory or the parameterization of cloud physics and the phenomena occuring really in clouds, we have constructed the experimental facilities with quasi-prototype scale using a vertical long shaft in a mine, and some valuable data such as updraft velocity, temperature, mixing ratio of vapor, cloud particles and rain drops, aerosol and their vertical distribution have been observed. In this shaft it was found that cloud occurred even in the lower condition than saturation point of humidity. The vertical distributions of temperature consists of two descending linear lines, which correspond to the dry and moist adiabatic lapse rate each other. This indicates the release of latent heat at the phase change from vapor to cloud water. Through the experiments, we found the new type of mechanism related to the occurrence of clouds. Finally we compared the above experimental results with the numerical solutions using the model of micro cloud physics proposed by Steven and Hobbs (1983), and we confirmed that this model can explain the experimental results by a slight modification for a condensation term.

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A micro model for flood refuge activity simulation on the family level is designed here by the use of AI techniques such as production system and fuzzy inference. Control factors of individual refuge activity are classified into three categories: initial factors such as the sense of flood damage and daily life pattern, mental factors such as the extent of flood danger recognition and attention to information, and external factors such as provided information and inundation level. And interraction among these factors and refuge activity are modelled with knowledge-based systems. Consequently, the model enables us to incorporate directly the results of questionare reseraches about flood refuge activity into the refuge simulator on a computer. The whole system is implemented in Smalltalk-80 as a object-oriented model.

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In this paper, we propose a two-phase mixture model which represents the moisture movement through porous media, in which moisture is assumed to exist in two phases, namely trapping and free phase. We obtain an analytical solution of a linearly approximated model derived from the two-phase mixture model. We then apply the solution to the experimental results of unsaturated vertical flow for snow samples.
As a result, we find that the solution agree very well with a process of run-off from snow samples in experiments. Moreover, we examine the characteristic of model parameters based on the computational results.

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In this study, an attempt is made to provide a tool for estimating energy balance and thermal load of human body as one of thermal comfort indexes in outdoor environments. This method is applied to four sets of meteorological field observation data. The characteristics of each component of human energy balance are examined in the following view points;
1) seasonal effect (summer and winter), 2) effect of ground cover (concrete and vegetation) and 3) effect of clothes.

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It is well known that the liquefaction of sand bed occurs under the cyclic loading of water pressure on its surface. Recently, many researchers have been carrying out the experimental studies on this problem. But, the similitude on this kind of dynamic behavior between prototype and model has not yet been developed. In this study, we presented the similitude of this phenomenon derived from the one-dimensional mathematical model and investigated its applicability numerically.

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The stress analysis and fracture analysis of pipeline by water hammer has seldom been studied because water hammer effect is the dynamic phenomena except the water hammer created by gradually closed valve in a long line. In this research experiments of pipe fracture were conducted in order to examine the difference between the strength of the PVC test pipes by water hammer in about 0.07 second loading and by static pressure in about two minutes loading. The pressure of dynamic fracture by water hammer was about 25% higher than the static fracture, though the loading time difference is 2, 000 times. From this result it is possible that the static stress analysis could be applied to the pipe to the pipe fracture by water hammer even in a case of sudden valve closure.

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A numerical model is proposed to investigate the characteristics of fiite amplitude bed topography in straight and meandering channel. The model is verified using a series of movable bed experiments performed in a wide range of geometric and hydraulic condition. The effects of geometric and hydraulic factors for finite amplitude bed topography in meandering and straight channels are investigated using the proposed numerical model by controlling the geometric and hydraulic parameters indivisually. By the results of the numerical experiment, a series of figures are presented, which show the effects of each parameter to the finite amplitude bed topography. Some interesting phenomena, including the interaction of free and forced bars, are discussed.

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Large horizontal eddies were observed in aerophotograph taken in the flood of the Tone river with vegetation near bank. Observed flow pattern was examined by applying 2-D shallow water model to flood flow. It was shown that large horizontal structures of flow which meanders along vegetated area near river bank, exist and agree with the structure of the flow calculated by 2-D model. The boundary mixing coefficient predicted by authors was shown to be applicable to the flood flow in actual rivers.

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Turbulence measurements in spatial accelerating and spatial decelerating flows over steep beds were conducted with two component laser Doppler anemometer (LDA). Open-channel flows with moderate to strong pressure gradients can be classified by using the modified shape factor. Ludweig-Tillmann's empirical formula, one of the evaluation methods for friction velocity, was very suitable only in sub-critical flows. The mean velocity profiles in the outer region deviate from the log-law distribution. If the flow is decelerating, the wake strength parameter II that implies the magnitude of deviation increases as the effect of deceleration becomes stronger. In contrast, the II-value decreases in the accelerating flows. The distributions of turbulence intensities and Reynolds stress change gradually from the bed to free surface, and do not indicate universal distributions normalized by the outer variables.

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Spatially growing disturbances of the velocity and the water depth in a mixing shear layer of open channel flows are investigated by means of the plane-2D shallow water equations. The inviscid instability analysis of the basic equations with respect to the space is firstly made for the tanh-type velocity profile in order to derive the spatial amplification rate and the phase velocity of disturbances. Then the plane-2D open channel flows with slender rectangular dead zone are simulated numerically under the hydraulic conditions of experiments. In regard to the characteristics of spatial growing disturbances, it will be shown that the amplification rate, the primary frequency and the phase velocity evaluated by the calculated results are in good agreement with the instability analysis and the laboratory tests.

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The characteristics of water-level fluctuations in simple surge tank are determined as dimensionless solution by means of linearization on the operation causing periodical fluctuation, with large amplitude, of the power output generated at hydraulic power stations. The theoretical solution corresponds to situations under normal operation and full-load rejection operation, and, based on this, a general chart by dimensionless form is made. Concerning to the computation of magnitude of free surge, the four fundamental values (surge-tank area, tunnel length, tunnel area, and discharge) are reduced to two fundamental values through arithmetic procedure. These two values are the relative value of head loss and effective head, and the relative value of surge-tank area and Thoma's minimum-area required for stability criteria.

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In steady open-channel flows, anisotropic turbulence is observed due to the existence of free surface. Open-channel flow has its own peculiar distribution of turbulence characteristics. Especially in the critical open-channel flow in which the Froude number becomes unity, turbulence intensities do not show the universal distributions. This may be caused by Bradshaw (1967)'s hypothesis that the inactive motions composed of low frequency and flow history become more dominant. In unsteady open-channel flows, effects of inactive motions are expected to be more dominant for the distribution of turbulence intensities. In this study, turbulence measurements in the outer region, especially in depth-varying zone, were conducted accurately by using two-component LDA. The effects of free surface on the turbulent structures are discussed in detail.

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Stability of horizontal and periodic vortices formed in compound open channels is studied in terms of shear instability and Karman's vortex street stability. It was found that two arrays of vortex street become very stable when the periods predicted from both instabilities agree with each other. 3-D structure of the organized vortices was observed by employing a conditional sampling technique, in which 2-D laser-Doppler anemometer and hotfilm anemometer were used in tandem. The velocity distribution obtained by spatial averaging for one wave length of vortex shows a typical secondary flow usually seen at the corner of compound channels.

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When a swarm of solid particles is dumped instantaneously from a point source in stagnant water, its falling behaviour and induced flow field are investigated both through a hydraulic experiment and through a theoretical analysis. The experiment shows that characteristics of the falling behaviour of the swarm varies both with particle size and with dumped amount from turbulent thermal-like to free settling-like. The theoretical model on the basis of the turbulent thermal theory which can represent the variation of the falling behaviour and aspects of the induced flow field is developed.

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The experimental and theoretical study are performed to demonstrate the effectiveness of a gentle slope bank against bed scour, in particular, occurring in the outer region of the flow in a curved channel. As the results of this study, the gentle slope bank shows an important effect on the improvement of velocity distribution around the bank and scourring rate without occurrence of water level rising. Those results also indicate the suitable selection of the applied models in accordance with the degree of roughness on the slope, that is, zero equation model for low roughness and k-ε model for high roughness, respectively.

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Field measurements have been carried out at the mouth of the Nanakita River, the catchment area being 229km², with the object of finding difference of topography change between small and large rivers. The cross-sectional area at the mouth attained to its equilibrium state very rapidly as compared with large rivers. Another distinct difference can be seen in the water level rise, or wave set-up, measured in the mouth. Furthermore, time-variation of the water level inside the river showed remarkable reduction of the amplitude and also phase shift behind the tidal variation in the ocean. On assuming a triangular or parabolic section, the width and the maximum depth at the gorge section are determined to minimize the difference between computed and measured water level inside the river.

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Transformation characteristics of double peak spectral waves are investigated by laboratory experiments and numerical calculations by a hybrid theoretical model employing a modified spectral KdV equation model and a probabilistic bore breaking model. Since energy densities of high frequency wave train decrease faster than those of low frequency wave train in shoaling and breaking zone, the high frequency peak becomes diminished resulting in one peak spectral wave; which is the cause that the occurrence probability of double peak spectral waves is higher in offshore region than that in coastal area, as reported in the literatures. The hybrid model can predict the changes of energy spectra, significant wave heights, and significant wave periods.

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A parabolic approximation is applied to a mild slope wave equation, derived by Mase et al. (1994), considering rapid bottom undulations about the mean depth and the effects of seabed permeability. The resulting coupled parabolic equations are used to analyze wave transformations over two-dimensional bottom topography with rippled undulations. When the ripples are permeable, incident and reflected waves become small, due to the energy dissipation in the porous media, compared to the case of rigid ripples. Although a wave control by using the Bragg reflection is effective in one-dimensional case, wave heights behind the ripples cannot be always reduced due to the effects of refraction-diffraction in two-dimensional cases.

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In the analyses of nearshore currents on actual coasts, more knowledge is required on the radiation stress in fields of random waves. Discussions are made on detailed surperposition of the stresses corresponding to constituent waves. Diriving forces thus obtained are not uniform in the longshore direction, and possibly produce rip and meandering longshore currents on a uniformly sloping beach.

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The management of coastal amenity resources was investigated along Hakata Bay having diverse coastline in the city area. It was shown that dominating factors of the coastal amenities were landscape, accessibility, naturalness, intimacy of water and amusement, and that the weight of these factors was different among the styles of coast natural, urban living and urban leisure coast. Further, we evaluated the monetized value of the coast: by use of willingness-to-pay method and the restoration cost method proposed for the sake of natural coast. Then, we discussed the effect of water quality implovement on the value of coastal amenities and what the mitigation of coast in the city area should be.

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Field observation for the salt intrusion in Lamong river in Surabaya, Indonesia has been continued by the teams of Hydraulics in ITS and Toyo University. This research has been done under the cooporative research between STS and Toyo University since 1990. This report is the results of theoretical analysis on the tidal motion in the fish ponds which are connected earch other and also connected to the tidal river. But the fields observations are now proceeding and the data from the fields are not sufficient, so the comparison between the theoritical results and the data from the laboratoly model has been done. In this case two connected fish ponds has been done in experiment and the comparison between the theory is good in the response of amplitude and phase lag.

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Stones are employed in many cases as backfill material to reduce the earth pressure on the rear face of gravity mooring quays etc. At Shirashima Petroleum Storage Base rubble was used for sliding resistance against the wave pressures on a caisson type breakwater. In this study, large scale panel type earth pressure cells were used to measure the earth pressure in the rubble acting on the rear face of the caisson. The coefficient of earth pressure for the rubble had an average value of K=0.2.

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At Shirashima Petroleum Storage Base rubble is used in the foundation mound for a caisson type breakwater. The resistance of the caisson breakwater against waves is expected to be the frictional force between the bottom slab of caisson and the rubble mound foundation. In the design a value of μ=0.6 was used for the coefficient of friction. Laboratory experiments were conducted so that an identical value could be guaranteed with the same grading method as used on site. The results of the experiments give, μ=0.66 as the average maximum coefficient of friction.

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