The aims of this study was to clarify temperature differences between big cities and their surrounding small towns of the big cities investigated, forty-seven prefectural capital cities, plusObihiro and Asahikawa were chosen. The surrounding towns were chosen for having quite similar meteorological conditions for each site investigated. Annual mean temperature differences between investigated cities and the small surrounding towns were shown to have positive mean values of 0.8°C, and from 0.0°C to 1.9°C, except in only one case. Thies results show the capital cities had higher temperatures than surrounding small towns, which mainly consist of agricultural land and forests. This phenomena is well known as “heat island” but the details of this phenomenon have not been clear until reccenty. In addition, multiple correlation analysis between the annual mean temperature differences and elements related to the difference were carried out. Using this relationship, the ‘ideal’ temperature difference among city size was evaluated, in which the “ideal” difference means the temperature difference due only to the function of city population regardless of the other elements.

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Although the direct shear box test is commonly used, there have been a few studies on applying the finite element method to the test. We analyzed the test with the finite element method, and compared the results with Rowe's equation and Davis's equation. The constitutive model for this analysis is for non-associated strain hardening-softening elasto-plastic materials. A yield function of the Mohr-Coulomb type and a plastic potential function of the Drucker-Prager type were employed. We attempted to analyze 5 type boundary conditions. There are little differences at stress-displacement curve and good agreement with experiment. The results showed that internal friction angle from FEM are very similar to Rowe's friction angle and Davis's friction angle. The direct shear box is a proper test apparatus although there are non-uniformities in stress and strain.

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A lot of investigations of in-situ measurement methods for saturated hydraulic conductivity for farmland and their comparison have so far been conducted, while few for arid land. Furthermore, few of them consider the measurement and analytical errors in comparing these methods. In the present study, Leonora in Western Australia was selected as a research subject area, and quantitative evaluation was conducted for the effects of measurement condition on the results by various measurement and analytical methods, by comparison with results from numerical simulation. We also evaluated the impermeable layer on the results by Guelph permeameter method and permeability of crust from cylinder intake rate method. As a result, it was showed that the amount of infiltrated water was decreased about 10% by the existence of the impermeable layer at 46cm depth in the Guelph permeameter method. The value of the hydraulic conductivity of the crust layer formed at the soil surface was three-order lower than that of soil body. The quantitative analysis of deviations and errors caused by various non-uniformity of soil structure are possible by comparison of multiple measurement results with numerical predictions.

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The automatic control system of pH was constructed. The system performance was evaluated with 3L mixture of HCl and NaOH solutions. The result is the following;
At first, as the injection process is dependent on the mechanical part of pump, the accuracy of injection was investigated. Relationship between volume of injection and pH agreed well with the theory.
Next, as both the rapid and good control is required for the system performance, the time and quality in controlling pH were investigated. The time and quality to control pH were explained in terms of three parameters such as injection ratio, unit mixing time, and judgment factors of stability. Reliable conditions for good control were attributed to the combination of smaller injection ratio, larger unit mixing time, and severe judgment factors of stability. But those conditions were contract with those of the shortest control time. The shortest control time between 3 and 7, or between 11 and 7 of pH was 6 to 10 minutes. It took less than one minute to control between 3 and 11, or between 11 and 3 of pH.

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The effect of puddling on cracking patterns is substantial in clayey paddy fields. The present study examined the relationship between puddling intensity and the resulting shrinkage characteristics. The experiment was performed in a clayey paddy field. Puddling intensity was examined as a unique factor. Three intensity levels: light (puddling once), medium (puddling three times), and heavy (puddling five times) at each level with three repetitions, were assigned across nine plots (three plots per level). Disturbed soil and undisturbed soil were sampled in each plot just after puddling, and again three months after puddling. Just after puddling, the puddling intensity significantly affected the content of the remaining clods, water retentivity, and the increment of air-filled pores induced by fracturing forces during desiccation, but these differences are estimated to have had little effect on the expected volume of cracks. Three months after puddling, the difference in these properties due to the puddling intensity became unclear, with the exception of the content of clods. Thus, the important properties which control the variation in cracking geometry due to puddling intensity cannot be sensed by the shrinkage test for core samples. The direct measurement of soil structure, such as the content of remaining clods, reflects the differences in the mechanical properties due to puddling intensity.

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The removal of phosphorus by using the electric furnace slag was studied. Tabular slag sample was made of a mixture of the fine slag and Kibushi clay. Chemical component and mechanism for the removal of phosphorus were examined with sample dipped in KH₂PO₄ solution.
Removal ratio of phosphorus of slag sample showed over 90%. High removal of phosphorus can be explained in terms of the calcium of slag. Under the great concentration of calcium of 2.49mmol/L and the pH range from 8 to 11, the precipitate was formed. The precipitate was analyzed with X-ray diffraction and ion chromatography, then it was identified as hydroxylapatite, and both calcium and phosphorus were detected in it. Therefore, dissolved calcium in solution from slag contributed to the removal. Undissolved calcium on slag surface also contributed to it. Phosphorus adsorption of Kibushi clay effectively exerted influences on the removal. Amount of phosphorus adsorption depended on pH and concentration of phosphorus.

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A practical survey on the precipitation, soil water and groundwater transformation was carried out in the cold and dry field. The neutron probe experiment plot was set up for the measuring of the triple waters transformation at Molimiao Farm of Tongliao City, Inner Mongolia Autonomous Region of China. The systematic observations at five sites were carried out from July, 1991 to September, 1992. The results obtained are as follow:(1) The groundwater movement fluctuated with rainfall, evaporation, and freezing and thawing. The variation scale was greatly influenced by the depth of groundwater, the vegetation and landscape; the influence of formation and clay layers in the unsaturated zone also played an important roles.(2) Water storage in the unsaturated zone during the freezing and thawing period varied in intensity from sudden decrease to slow reduction and slight increase, to great reduction and to variable reduction. The maximum storage in the unsaturated zone showed variance from increase to reduction.(3) The soil moisture content during the freezing period increased in frozen soil file period, and decreased in unfrozen soil file. However, there were different characteristics in the groundwater movement that could be found during thawing period due to the impacts of clay layers in unsaturated zone.

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COD removal performance in aerobic filter tank was investigated using observed data on rural sewerage facilities with submerged biological filters. It was found that the probability distribution of influent COD in aerobic filter tank and effluent COD in sedimentation tank agreed with the normal distribution and logarithmic normal distribution. It was found that COD removal in aerobic filter tank was influenced by capability to catch suspended solids and deatchment-and-elution of accumulated matter in filters of aerobic filter tank. It was assumed that an aerobic filter tank was represented as completely mixed reactor and COD reduction was employed with a linear function. The specific surface area of contact filter in aerobic filter tank have influence on COD removal in aerobic filter tank. It is suggested that ORP and DO in aerobic filter tank may be affected significantly by aeration rate so that COD removal shall be governed from aeration rate in aerobic filter tank. COD removal rate was assumed to depend on influent COD concentration, hydraulic loading, specific surface area of packing media, and aeration rate in aerobic filter tank. The multiple regression equation between COD removal rate and these four factors can be derived from observed data. The control of sludge accumulation and substrate removal rate in aerated filter tank is effective in maintaining stable COD removal efficiency.

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In the case of sprayed direct seeding of rice plant, the seed penetration is influenced by surface undulations of paddy eld after puddling. In this paper, the author grasp the influence of field undulations on the seed penetration, especially non-penetration, and consider the possibility to control the seed penetration from the viewpoint of leveling accuracy. As the results; 1) Surface soil hardness of paddy field quickly becomes harder when the soil exposed from the water surface because of undulations, and it causes expansion of the heterogeneity of surface soil hardness. 2) As water depth increases, the ratio of non-penetrating seeds increases because of the resistance of water. 3) The present standard of leveling accuracy, ±3.5cm, cannot avoid non-penetrating seeds completely. To avoid non-penetrating seeds, not only improvement of leveling accuracy is necessary but also precise water management when seeding, even though each of them are hard to practice.

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The load-displacement curves for concrete containing up to 30 % rice husk ash (RHA) by weight of the total cementing material were measured using notched cubic specimens and wedge splitting procedures. The influences of RHA content on fracture properties, such as the specific fracture energy, tension softening diagram, compressive, tensile and flexural strengths, were investigated from the experimental results. The observed differences in the fracture behavior between control and RHA concrete were also analyzed and discussed. The results showed that the behavior in the specific fracture energy was significantly different from the behavior in the compressive or flexural strengths of the concrete. The tension softening diagrams obtained by the trilinear approximation method agreed well with those determined using the polylinear inverse analysis method.

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A parameter estimation procedure that employs a simple genetic algorithm combined with FEM calculation is developed to investigate a head loss property of nonlinear flow through rockfill. The head loss property of nonlinear flow is described by the Forchheimer equation, and two coefficients included in the equation are expressed by genetic chromosomes. In the parameter estimation, the simple genetic algorithm searches a chromosome that minimizes a squared deviation of flow discharge through rockfill between observation and FEM calculation to determine an optimal set of coefficients of nonlinear flow. Two coefficients of nonlinear flow are coded into a binary chromosome. The fitness value of the chromosome is calculated as a reciprocal of a sum of the squared deviation of fl ow discharge mentioned above. The chromosomes with large fitness are selected to reproduce a next generation of offspring. The parameter estimation procedure is applied to stage-discharge data measured in 15 embankment tests in a laboratory water flume to estimate two coefficients of nonlinear flow and to compare them with the results of one dimensional permeability tests which was conducted previously and published elsewhere. Good comparison shows a practical effectiveness of the parameter estimation procedure developed.

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Hysteresis phenomena in the thermal conductivity of frozen soils between freezing and thawing processes were investigated and discussed from a view point of the amount of unfrozen water contained in the frozen soils. Thermal conductivities of frozen alluvial and ando soils have shown hysteresis and these were higher in the thawing process than in the freezing one. The same soils also showed the hysteresis in the amount of unfrozen water which were less in the thawing process than in the freezing one. The differences of the thermal conductivity and the amount of unfrozen water between the two processes became larger with the increase of initial soil water content at freezing, and the differences of the values at-2°C were larger than at-6°C. However, the sand soil have not shown the hysteresis in the thermal conductivity and the amount of unfrozen water between the two processes. It is revealed that the hysteresis of the thermal conductivity was due to the fact that the thermal conductivity of ice was four times larger than unfrozen water and the thawing process contained less unfrozen water or more ice than the freezing process at the same temperature.

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In recent years the consciousness of nature has been improving, the improvement of river water quality has been planned. However, there are many cases that rural sewage is not considered yet about the influence that it exerts on the water quality standard and ecosystem of the river receiving sewage yet. It is very important to grasp the influence that it exerts on the river's ecosystem of the river receiving sewage, but it is not clear yet. Thereupon, we investigated a ‘direct release style’ site where the rural sewage was released directly into the river in order to clarify the influence of rural sewage effluent on the ecosystem in river channels. In this paper, we especially examined the influence to the benthic fauna by rural sewage. As a result, the species composition of the benthic fauna simplifies as following the influence of rural sewage and diversity fell off in the remaining area where rural sewage flows in. And it became clear that the pollution degree of the water became high. Also the evaluation by the benthic fauna that species composition is formed and adapts to the water environment in areas was considered as the one that evaluated and accumulated the water quality in the survey period. These results made clear that the influence of rural sewage had reached approximately 10m downstream.

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This paper discusses possibility to use ground penetrating radar (GPR) for indicating leakage path in small earth dams. It is difficult to indicate leakage paths from one result of GPR investigation because of the difficulty to distinguish reflections of electric wave at leakage paths with reflection at compacted plane. We compared radar profiles at an embankment when leakage was observed on full water level and profiles when leakage stopped on low water level. In the result of model tests and in-situ investigation, the reflections of electric wave at leakage paths are stronger when leakage stopped than that when leakage occurred. It was found that change points in radar profiles that are obtained when leakage occurs and stops indicate the leakage paths.

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There are 250000 small earth dams, which are important water resource of rural area in Japan. Because the collapse of small earth dams occurs every year due to a heavy rain, it is an important problem for the safety of the area. As a result of rainfall data analysis, dams damage occurred in the area recorded more than 200 mm of accumulated rainfall and more than 20 mm of hourly rainfall. A large amount of hourly precipitation showed a tendency to trigger dams damage. Results of site investigation showed that the type of damage can be classified into overflow erosion, sliding and seepage failure. In the case of seepage failure, internal erosion likely occurs from the upstream slope near the full water level. In the case of sliding, a failure likely starts at a toe of an embankment. Overflow failure likely occurs at the crest above the gut of foundation, because overflowing water concentrate the gut area which is lowered by consolidation settlement.

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In order to obtain methane emission in the well-drained and ill-drained paddy fields of the same soil series respectively, it was measured at two sites of irrigation canal and drainage canal of the paddy field.
The following are the main results of this study.
(1) Methane emission from the ill-drained paddy field was about 2.5 times as much as the well-drained paddy field.
(2) Methane emission from the site of irrigation canal was about 2.2 times as much as the site of drainage canal inthe well-drained paddy field.
(3) Methane emission from the site of irrigation canal was about 1.0 times as much as the site of drainage canal in the ill-drained paddy field.
For the reasons mentioned above, it became clear that more or less of methane emission is directly affected by good or bad of drainage.

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The purpose of this paper is to propose a prediction method of adiabatic temperature rise curves of concretes with the simplified adiabatic apparatus which consists of metal frames and foam polystyrene. These testing methods are simpler than ordinary ones, so it is applicable to practical works. Parameters of an adiabatic temperature rise curve are identified so that the temperature-time curve measured at the center of specimen corresponds to that estimated by FEM. To verify the methods, a series of simplified adiabatic and water circulatory type tests with different concreting temperature 11, 21, 32°C, was conducted. The adiabatic temperature rise curves estimated by FEM were almost consistent with those measured by the water circulatory type apparatus. The differences between the estimated and measured results on the final temperature rise of concretes were within 1.5°C.

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A labyrinth weir has high discharge performance and is advantageous when it is used for a dam spillway, a check gate. But its longitudinal length is not short. Therefore, an ordinary labyrinth weir may not be set in limited space, e.g., on the inlet part of a small spillway. In such case, a highdensity or quasi-rectangular labyrinth weir is preferable, because it has a longer crest than an ordinary one, i.e., a low density or triangular one in limited space. A high density or quasi-rectangular one is known to have relatively low discharge coefficient per crest length by contraction or expansion effect. Nevertheless, it is expected to have still better discharge performance by its longer crest in limited space. In this study, we made clear systematically of relations between shapes and discharge coefficent of labyrinth weirs, in wide range of density and various plane shapes including a high density and/or quasi-rectangular one, for its design in limited space.

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