Concerns over the global environment and the Gulf (oil) crisis in August 1990's Iraq invasion have improved our understanding of the importance of clean energy such as non-polluting hydroelectric power. By the year 2000, water and oil will be the predominant resources issues of the Middle East. A new cogeneration method for the Israel/Jordan Mediterranean-Dead Sea hydro-solar scheme is proposed herewith, which aims to exploit both electricity and fresh water by desalination from the Mediterranean Sea, would exploit the 400 m elevation difference between the two seas by including hydro-electricstations and seawater reverse osmosis (RO) desalination plants. The co-generation system could produce 480 MW of electricity and 86, 400 m³ per day of fresh water from Mediterranean Sea. The generated power will be shared by the two countries, while the product of freshwater of 30 MCM (×10⁶) per annum will be used exclusively for the water supply in the central Ghor (Jordan Valley).

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Groundwater contamination by agricutural chemicals is getting one of the most serious environmental problems, especially in golf course. The purpose of this study is to investigate the moving characteristics of scattered pesticides caused by heavy rain.
The contents of this study are 1) the investigation of poison characteristics of the main agricultural pesticides in golf course, 2) the analysis of data of sand-column tests based on the method of gaschromatography (GC-FTD), and 3) the analysis of experimental data of surface runoff in the grass channel model by GC-FTD.
Main results obtained are as follows: 1) most of the scattered pesticides are adsorbed by the grass and soil particles, 2) the estimated values of concentration of pesticides in the sand-column tests are a little over the permitted value, and so it is necessary to keep a lookout for the behavior, and 3) the estimated values in the surface runoff tests are no problem.

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Groundwater contamination by agricultural chemicals is getting one of the most serious environmental problems, especially in golf course. This study focuses on the infiltration and dispersion of pesticides (MEP) with rainfall on the patting-green in golf course.
In order to estimate both the hydraulic characteristics of groundwater and the concentration distribution of scattered pesticides in the ground, the experimental research is carried out with sand-layer column models. Experimental data of tensiometers and thermometers are estimated by hydraulic analysis and test samples of polluted water are chemically analyzed by the method of gaschromatography (FTD).
Main results obtained are as follows: 1) values of tensiometer do not change under such rainfall condition as less than or equalto 20 mm/hr intensity and 20 min duration time, except the surface layer and 2) most of the scattered pesticides are adsorbed by the grass and soil particles and therefore the amounts which flow out into the groundwater are very little.

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A description is given of a solute transport model in groundwater which includes multicomponent physico-chemical processes. The processes of cation exchange and of solid dissolution-precipitation are incorporated in the numerical solution of the convective-dispersive equation, using the method of characteristics. It is demonstrated that the converged values of concentration obtained by including the physico-chemical reaction routines satisfiy the mass balance, mass action, and charge balance criteria.

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To estimate probable effects of grobal warming on water resources in Japan, long-term monthly data of temperature, precipitation and depth of snow cover are collected and analysed. Characteristics of precipitation in the period from May to September in defferent regions are compared over the cold decate and the warm decade. The relation between tempreture and yearly maximum depth of snow cover in the snowy regions is also investigated. The results show that drought in summer might become severe and snowmelt water might decrease with grobal warming.

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The rise of temperature by “greenhouse” effect attracts public attention. So far many papers on this problems have been presented, but the results are sometimes different from each others. Such differences are probably caused by data treatment. This paper intends to examine long term variations of temperature and precipitation amount in Kanto District, forcusing on the contrast between urban areas and rural districts, moreover between the Pacific side and the Japan sea side. The main results are as follows: the present state of temperature variations is in low-stage in rural districts and rising state in urban areas, and precipitation amount are decreasing at many observation points.

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Recently, groundwater contamination by chrolinated organic compounds (trichloroethylene, tetrachloroethylene etc.) is broadly observed and its treatment technology is urged in contaminated areas. Physical process of dissolution of such compounds by the groundwater stream should be discussed to understand the mechanism of early stage of contamination near the contaminant source. So, we need some experiments on the movement of contaminants in subsurface and solution process into groundwater. This paper discusses experimentally the dissolution from interface between water and chlorinated organic compounds.

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The cooling effect of rivers was studied in terms of model experiments in which convective heat transfer and fluid velocity were measured for water flow in an open channel. The governing equations indicate that such a phenomenon depends on the Rayleigh number. It is observed that for small Rayleigh number, the flow consists of several longitudinal cells with a dimension of flow depth and weak large scale convective circulations with a scale of channel width. For large Rayleigh number, however, the latter circulation becomes predominant and the velocity on the non-heated area is remarkably large. It was observed that the cooling effect of non-heated area on heated area is limited to a narrow region, which agrees qualitatively with field observations.

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Three dimensional computation process by the Boundary Integral Equation Method has been developed for flows in an unconfined aquifer. An availability of the computation process presented here was applied to a duct flow and two dimensional groundwater flow through a dam, and was confirmed by the comparison of the theoretical values with computed ones concerning the potential, flux and groundwater surface profile. Finally, a transient three dimensional flow pattern arround an underground dam was shown as a typical computation example

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Performance evaluation of the preconditioned conjugate gradient-like methods is made through the numerical simulation of two and three dimensional turbulent flow fields with the finite volume method. Preconditioned solvers examined include conjugate gradient method (PCG), conjugate residual method (PCR), bi-conjugate gradient method (PBCG) and conjugate gradient squared method (PCGS). Comparisons of the performance of the solvers demonstrate that the combination of PCG for the pressure-correction equation and PCR for the other equations requires the least CPU time against both two and three dimensional flows. PCR, PBCG and PCGS are shown to be superior to the vectorized strongly implicit procedure (SIP) proposed by Stone when they are used together with PCG.

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A basic study on scale effects of hydrologic cycle is presented. The interflow and overland flow model which takes into account the variable source area with high permeable surface layer was composed first. Next, the direct runoff simulations were executed for rainfall events in many different size of actual catchments considering various catchment parameters such as length, inclination and hydraulic conductivity of surface soil of slopes. Finally, the relation between catchment scale and maximum direct runoff discharge was discussed. Based on the results of the simulation, the composition of the conventional (maximum) specific discharge curve was also explained.

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Atmospheric vapor flux convergence is introduced for the estimation of the water balance in a river basin. Flux convergence is calculated using the ECMWF global analysis data, and compared with the observed data in Chao Phraya river basin, Thailand. Through the balance equation of hydrological cycle, discharge is estimated from vapor flux convergence and is compared with observations. It was found that the absolute value of flux convergence is not applicable, but inclusion of a factor provided better estimation for the case under study. Such information is expected to give basin scale evaporation or water storage in a basin.

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A Secondary vorticity generated around large eddies in pure and forced plumes by the difference between the directions of the gravity acceleration and the density gradient was modelled and formulated using the Bjerknes theorem and the vorticity equation. As a result, it is found that the direction of secondary vorticity is the same as one of an original vorticity in the large eddy. In addition, the mechanism of turbulent entrainment of an environmental fluid was discussed connected with the secondary vorticity.

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It is well known that the Boussinesq approximation works well in the field of convection flow and heat transfer. However, the basis of this approximation is that temperature in the flow field varies little. Can we extend this assumption to the case in which large temperature difference exists? The engineering answer is definite so far, but from theoretical point of view, it is questionable. What can we do then? This is what we have attempted to do in this paper. In this paper, we propose a new approach to deal with convective heat transfer without using the Boussinesq assumption.

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We have stated about the outline of river bed observation on a flood caused recently, and also stated about a study that has been started concerning this year's concave bank's water basin. Another statement that we presented here is observation on river bed elevation for wide area or at deep area along concave bank which becomes possible by using a hovercraft.

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