Artificial island developments are being planned and constructed one after the other in the semi-enclosed coastal area. The decision plan of such a project is made usually on the basis of environmental assessment which is done from the various view points. The analysis of tidal currents is always included in the assessment that is aimed to evaluate the changes of tidal flow pattern due to the existence of an artificial island. Such an evaluation, in many cases, is made through the numerical simulation and/or the physical experiment that deals with the phenomena during a few tidal cycles.
In this paper, a numerical scheme was presented that evaluates the tidal exchange aimed at the environmental assessment. Some imaginary model simulations dealing with the tidal exchange phenomena between the semi-enclosed bay and the outer sea were done by using the presented. scheme. The simulations showed the evidence that a slight change of tidal currents has the possibility to cause a serious influence on the tidal exchange during a long time-span. On the basis of such evidence, it was suggested that the analysis of tidal exchange during a long time-span is important and is necessary in future for the environmental assessment on tidal flow.

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In this research, by applying fuzzy inference to the digital control of pipeline systems, the design of the control system and the simulation assessment of the controllability were carried out.
In the semi-closed pipeline that connects plural intermediate water tanks, by applying digital control to the control system, in which the revolution control of pumps and the constant water level control of values are combined, it was found that the flowing condition in the pipeline was stabilized.
Further, it is considered that by applying fuzzy inference to the digital control of pipelines, the control system which is robust against external turbulence, able to cope with special circumstances with a small number of controlling rules, and stable in a wide range, can be designed.
It was confirmed that as the method of applying fuzzy inference at that time, either the type of using mainly PID control and diverting the fuzzy inference to the support, or the type of directly obtaining control quantity from the fuzzy inference without any control model can be expected to improve the response patterns in control.

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Bay environment is closely related to its stratified intensity. In this study, with the stratified intensity expressed by potential energy in water column, investigations have been carried out for the relationships between the stratified intensity and the stratification of water temperature and salinity as well as the dissolved oxygen of bottom in Uranouchi Bay. These results are described as follows.
(1) Things to weaken the stratified intensity in the bay are considered to be its internal wave other than its tidal stream and convection.
(2) It is possible for the stratification in Uranouchi Bay to control it by utilizing its tidal energy effectively.
(3) The salinity stratification is dominant in the stratified intensity of the bay comparing to the water temperature stratification.
(4) Water temperature stratification and salinity stratification can be evaluated by a density stratified intensity attributing to its water temperature and salinity respectively.
(5) The stratified intensity is a very effective index as far as the increase and decrease mechanism of dissolved oxygen (DO) of bottom is considered.

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In order to predict and control thermal cracks in concrete structures, itis necessary to understand the hysteresis of temperatures calculated from the precise adiabatic temperature rise curve. Therefore, temperatures at the center points of concrete specimens placed and cured in the laboratory were measured at constant temperature and humidity. The constants of the adiabatic temperature rise curve were determined by back-analysis using the measured temperatures, and analysis of heat conduction using these constants was carried out by the three-dimensional finite element method. For an ambient temperature of 30°C, the estimated temperatures fitted well, but for an ambient temperature of 5°C, a considerable difference between the measured and calculated temperatures was demonstrated as the temperature rose. Furthermore, for an ambienttemperature of 5°C, analysis of heat conduction was performed, taking into account the effects of the thermal conductivity of concrete and the convection heat transfer coefficient, but the calculated temperatures did not agree well with the measured ones. Therefore, an adiabatic temperature rise curve for a low ambient temperature, to which the function form of the autocatalytic equation could be applied, was adopted, and analysis of heat conduction was carried out using this new empirical equation. It was found that the temperatures calculated using the new empirical equation approximated the measured ones. Since the hysteresis of the calculated and measured temperatures after the peak point expected to generate thermal cracks showed particularly good agreement, it was possible to apply the new empirical equation for predicting interior concrete temperatures at low ambient temperature.

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When we need hourly solar radiation on slopes, hourly direct and diffuse radiation data are necessary. But it is quite rare that hourly direct radiation data is available at adjacent meteorological observatory. This is the reason that estimation of hourly direct and diffuse radiation from horizontal global radiation is necessary.
For direct radiation, Watanabe et al.(1983) reported formulae to estimate direct radiation from horizontal global radiation, which can be also utilized to estimate diffuse radiation, because summation of direct and diffuse radiation gives global radiation.
In this paper, authors checked the accuracy of estimated diffuse radiation (truly, its standardized dimensionless factor K_s, see below) by applying their formulae to Tateno's data, and also have presented new formulae to estimate the diffuse radiation. Our best formula is as follows.
K_D/K_T=K_D+ (0.786-0.280 sin h) · K_D^0.657·(1-K_D) ^0.716, K_s=K_T-K_D
Where, K_D, K_S, K_T: Standardized direct, diffuse and global radiation, which means horizontal direct, diffuse and global radiation are divided by extraterrestrial horizontal radiation, h: solar altitude.

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Evapotranspiration is one of the most important factors for irrigation management. This study was conducted to develop and test a new method to determine evapotranspiration. Measurements of evapotranspiration, transpiration, soil evaporation, soil water status, sunlit leaf temperature, air temperature, imitation leaf temperature, plant coverage, leaf area index, and micro-meteorological parameters were made in a one hectare grain sorghum (Sorghum bicolor (L.) Moench.) field to verify the proposed method. A new equation was developed to estimate canopy evapotranspiration by introducing the temperature of an imitation leaf. The required parameters of this method were sunlit leaf temperature, imitation leaf temperature, air temperature, plant coverage, and solar radiation. The major advantage of the proposed method was that the plant correction factors, canopy resistance, and aerodynamic resistance were not required. By neglecting the evaporation from the soil surface where it is shadowed by a canopy (canopy shadowed soil), the suggested method was quite accurate to estimate plant transpiration. Field experimental results showed that the calculated daily and longer-period transpiration by the proposed method were consistent with the estimated results by lysimeters. The regression coefficients between daily estimated and calculated transpiration was r=0.94. In addition, the short period transpiration measured by porometer agreed well with the calculated transpiration by the proposed method. Therefore, it can be concluded that the suggested approach is a simple and accurate way to estimate plant transpiration.

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Retaining wall was analyzed and compared with the model experiments using air-dried Toyoura sand. The experiments were performed in passive modes by measuring load-displacement relationships of retaining wall (in conditions of plane strain) which were rotated about the toe into the sand mass when the ratio of the width of the model and the wall height was about 1. The finite element analysis employing a constitutive model in which non-associated strain hardeningsoftening elasto-plastic material was used. The shear band thickness was introduced as characteristic length into the constitutive equation.
In the case of steel wall face (wall friction angle is 6°), the earth pressure coefficients obtained by finite element analyses achieved good agreement with experimental results when the lubrication of side wall was applied. In the case of rough wall face, finite element analyses achieved agreement with experiments when the wall friction was assumed to be equal to the internal friction of sand.

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Four types of experiments using sloping boxes were carried out in order to quantify closely infiltration process of rainwater under the crust formation. Experiments A, B, C and D were made respectively in the box of surface protection and two layers of masa soil (5 mm thick) over sand, bare surface and two layers, surface protection and single layer of masa soil, and bare surface and single layer. Soil moisture suction was measured closely at the surface zone. Vertical one dimensional infiltration model was improved and applied to the three layers model.
Results in this paper were as follows.
1) Infiltration rates under the crust formation receded rapidly after an experiment start, and then showed the same oscillation as the pulsate flow for the term of recession curve.
2) In experiment A, seepage end of rainwater reached quickly to the bottom of the box, and it was observed that with time elapse the suction of soil moisture had declined equally in the whole soil profile. In other experiment B and D, soil moisture suction for the surface zone from 0 to 1 cm depth changed steeply from saturation to-17 cm H₂O at the early stage of the experiment. Since then this state of soil moisture suction had be maintained.
3) The infiltration rate in experiment C and D was still smaller than A and B, because dispersed particles, caused by slaking and impact of raindrops in B and D, and by slaking only in A and C, flowed vertically downward and were captured at the shallow surface zone in C and D more than in A and B.
4) The unsaturated hydraulic conductivity in first layer (0-0.5 cm) was the saturated hydraulic conductivity (terminal infiltration capacity) multiplied by the Brooks-Corey equation for the relative unsaturated conductivity obtained by the measured soil moisture characteristic curve in the first layer. For the soil moisture characteristic curve of the second layer (0.5-1.0 cm), the third layer without the crust formation was used and the saturated hydraulic conductivity of this layer was averaged two logarithmic values, to which two conductivities of the first layer and the third layer were converted.
5) With time elapse, calculated results of soil moisture suctions in soil profiles approximately agreed with observed values in each experiment. After thirty minutes since the experiments started, relative error of calculated value against observed in amount of soil moisture increase, were 1.6%, 18.5% and 4.8% respectively in the experiment A, B and D (after forty minutes)

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Fingerlike partial flow, or fingering flow can occur during vertical downward infiltration with sharp wetting front under the conditions of wetting front instability. To clarify the physical features of fingering flow, in particular, the change of the water pressure at the interlayer plane with increasing finger length and the degree of saturation within fingers, experiments of infiltration into fine over coarse textured layered glass beads were conducted. It was confirmed that distinct fingers occurred and grew in the sublayer when it was initially dry and the criterion for wetting front instability was satisfied. On the other hand, it was observed that when the sublayer was initially wet, the wetted region in the sublayer formed a wavy pattern rather than a fingerlike one. The water pressure at the interlayer plane decreased with the increase of finger length after it reached a maximum value at the onset of water entry into the sublayer when typical fingering occurred under initially dry sublayer conditions. The change of the flux through the top layer was corresponded to the change of the water pressure at the interlayer plane which consisted of one of boundary conditions for percolation in the top layer. Furthermore, it was estimated that it was not saturated within fingers but was under unsaturated condition with entrapped air.

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From 1989, we have carried out experimental studies on the estimation of compressive strength of concrete by non-destructive methods. Among the non-destructive methods, the ultrasonic pulse velocity method was used to estimate the strength development in massive concrete test pieces. Three types of massive concrete test pieces were prepared, that is, the first was 20 cm (height) ×100cm (width) ×100cm (length), the second 20×40×70cm, the third 70×20×40 cm. At the same time, we also prepared cylindrical and prismatic test pieces. We measured the inside temperature of the massive concrete test pieces three or five days earlier which were needed to strip the form. After the required curing duration the cores with a 10cm diameter were removed from the massive concrete test pieces and, their density, ultrasonic pulse velocity and compressive strength were measured.
The results obtained are as follows.
(1) The more massive the concrete becomes, the higher the maximum inside temperature also becomes and the time which is required to reach to a stable ultimate inside temperature, namely, the same as that of room becomes longer.
(2) At the same age, the more massive the concrete becomes, the lower the compressive strength becomes.
(3) For massive concrete, the difference in the ultrasonic pulse velocity between the inside and outside disappears after water curing for about one year.
(4) The tall concrete element such as for massive concrete test pieces with a height 70cm has a lower strength in the upper part with a depth of about 10cm, because this part has many capillary pores and water paths due to bleeding.

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Every farmer customized their consolidated field with leveling works. The load of leveling works is assumed with the amount of transported earth that could be obtained as the product of cutting and banking volume and transport distance. In this paper, the author dealed with the standard land of leveling for large-sized paddy field from the point of earth transportation work.
When current leveling standard for 30 are lot is applied to large-sized paddy field, more load of earth transportation is needed than applying the same standard to 30 are lot. Under the present leveling standard, introducing large-sized paddy field forces the farmers to bear the load of leveling works than present. On the other hand, in state of restricted standard, the builder would bear more load.
Therefore, large-sized paddy field would segment the new leveling standard which is acceptableboth by the farmers population and by the builders.

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A mathematical model is developed on the basis of the equation system of two-phase flow of the conservation of mass and momentum for the fluid and sediment interaction. In the model, the total flow region is divided into three layers composed of the bed load, buffer and suspended load regions over a movable bed. The buffer region has the function of the transition from the bed load motion to the suspension. The interaction between the fluid and sediment, as well as the interaction of sediment particle moving is described on each region. An analysis is done to derive the thickness, the sediment concentration and the velocity of the fluid in each region and the shear stress acting the boundary between each layer. As the results, the distributions of the concentration and the velocity can be predicted for the total flow region. Both distributions obtained from the developed model agrees with the data measured by Vanoni-Nomicos in the movable bed experiments.

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The k-ε turbulence models are used for the numerical calculation of turbulent shear flows. The standard k-ε model cannot be, however, applied to multi-phase flow where sediment interacts with turbulence because the models have been developed for the boundary layer flow analysis of single-phase flow. An analysis is performed to derive a new mathematical formulation of k-ε turbulence model for fluid-sediment two-phase flow on the basis of the equations of mass conservation and motion for two-phase flow. A new numerical calculation model, combined the formulation and the semi-theoretical model developed for analysis of the thickness of bed load layer and buffer layer in the previous report, is proposed to predict the vertical distributions of the fluid velocity and sediment concentration and the turbulent structure in steady uniform flow over a plane bed in open channel. The numerical calculations indicate a well agreement with the experimental data measured by Vanoni and Nomicos.

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The Land Improvement District (LID) is not only for promotion of fundamental maintenance projects to ensure the continuation of agricultural production but is important as an organ for maintaining the area's resources. For this reason it is neccessary to systematically grasp the nature of the LIDs. As a means to systematically study the LID groups, an attempt was made to classify in a case study, F Prefecture's 133 LIDs. First, to grasp the features of the LIDs, 17 variables based on financial and irrigation conditions and the project's progress during the ten years from 1982 to 1991 were selected, and principal component analysis was done using these 17 variables.
From this analysis seven significant principal components were selected and using their component scores, the LIDs were classified according to the cluster analysis method.
The results of these analyses were as follows. The LIDs in F Prefecture were divided into two groups: the farm land consolidation group and the other projects' group. The primary factors of this division are: A) obtainment of government funding, and availability of private finance for repayment of borrowed funds for farm land consolidation and improvement of water canals, B) amount of water reserves, amount of water taken from rivers, and the condition of irrigation system facilities, C) the relationship between the water canal conditions and additional income from the water which ensures the management of the LIDs.

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Reduction of materials in a pipeline can be considered an important element in attempting to reduce the cost of upland field irrigation facilities.
A pressure-reducing valve (automatic control valve), which has so far been used as a constant downstream pressure valve, does not require power and is operated automatically by hydraulic pressure. However, according to circumstances, there is a possibility of continuing downstream pressure with upstream pressure and, in such a case, the same pressure condition as that on the upstream side must be applied to the pipeline on the downstream side.
Consequently, if downstream pressure can be maintained when setting the pressure on discharge or no-discharge, the water hammer can be restrained by valve closure at the end of the pipeline, and thus excess pressure can be reduced and the maximum pressure kept below 980 kPa (10kgf/cm²). Thus, the use of inexpensive plastic pipes becomes possible and the pipeline cost can be reduced considerably.
With regard to the above possibility, we report the results of hydraulic tests in a practical pipeline system and the results of simulations corresponding to the tests. Furthermore, we propose a combination comprising a pressure-reducing valve, safety valve and pressure-absorbing facility as a measure for meeting the demand of facilities for pipeline pressure reduction on the downstream side.

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This research documents the characteristic change of nitrogen in soil profile of a paddy field. Two soil columns (boxes) each comprising of four soil layers were constructed. Free air was introduced in one box and the effect of aerobic and anaerobic conditions was investigated. Soil profiles' performance was evaluated from a chemical (mass balance) perspective (T-N, NO₂-N, NO₃-N, NH₄-N) coupled with a consideration of PO₄-P and ORP when the columns were subjected to certain concentrations of KNO₃ and KH₂PO₄ in the influent. The concentration of NO₃-N decreased abruptly in upper layers and then exhibited a gradual recovery from 20 cm depth to the end of aeration zone under aerobic environment due to continued nitrification process, while its concentration was almost zero in anoxic condition beyond the same depth. NH₄-N had appreciable concentration in the upper layers, and after that it became zero in aerated area. Contrary, it showed certain concentration in anaerobic condition. Such kind of tendency connotes the biochemical reactions of soil layers under the respective environments. T-N concentration demonstrated some diversity and it was considered that some nitrogen converted to gaseous products and emitted out as bubbles. ORP data explained well both the conditions, and water pressure distribution was also investigated. Consequently, the experiments showed comparable characteristic change of nitrogen, and displayed a greater ability for concrete recommendations.

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The contact aeration processes are being widely used for the rural sewage treatment systems. Such processes seem to encourage the nitrogen removal ability even during winter season. The observation data of prototype contact aeration process show that the nitrification did not occur vigorously when the temperature of mixed liquor was less than 15°C. In order to enhance the nitrification capability, the flow pattern of the treatment process was renewed in such a way that the aeration tanks were placed before the anaerobic tanks. On the contrary, the anaerobic tanks were previously placed before the aeration tanks. Return flow circulation was introduced within the aeration tank instead of the waste water after aeration process would return to the first anaerobic tank. Further, the volume of aeration tank was increased to about 1.5 times. The mixed liquor temperature was set around 13°C because it was not below 13°C even in the Tohoku and Hokkaido regions. As the result of the experiments under such conditions, nearly 100% nitrification was achieved.

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In this paper, the authors discussed about the newly proposed method by the Civil Engineering Institute of Ministry of Construction for estimating the seismic stability of embankment dams. The main feature of the method is composed of 2 reforms onto the conventional method. That is, the first is related to the alteration of the computational method of factor of safety against sliding and considerable increase in the magnitude of estimated seismic force in design. The second is related to the alteration in estimation of material shear strength.
In this paper, only the first point is discussed from the view point of the increase in the magnitude of seismic force and effect of the change of acting point of seismic force.
Several examples of computation were carried out, and were compared with the safety factor obtained by the conventional method.
As a result, it is clarified that the newly proposed method gives considerable decrease in thesafety factor compared to the conventional method, especially for shallow top sliding mass of an embankment.

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Recently, importance of temperature cracking control on small concrete structures is increasing. Temperature cracking is complicatedly and compositely influenced by construction size and form, mix proportion of concrete, execution of work, curing method and environmental conditions. Therefore, small concrete structure are examined by means of simplified investigation because of the difficulties of all-round investigation about temperature cracking.
The inner temperature variation of concrete structure is assumed to be influenced by construction size and form.
This paper described how the difference of construction size and form influence the inner temperature variation using three types concrete specimen and the assumed small concrete structures.
As a result, the concrete structure size influenced the time courses of temperature by the results of concrete temperature measurment with thermocouple sensor in the three specimens. Also, the concrete structure size and form influenced the time courses of temperature by the results of simulation about some assumed small concrete structures using the 3-D FEM.
Furthermore, calculated temperature was found to be smaller than measured one with increasing concrete structure size. This cause would be attributed to the difference of the characteristic adiabatic temperature rise curve.

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This paper describes an aseismic performance of the “WBJS” works on the basement of the concrete gravity dam. The “WBJS” works were developed by the authors on collaboration with other researchers to treat the basement of the dams that include large-scaled faults or fractured zones. These works were applied first to the Dondo Dam located in southern Hyogo Prefecture. The works were subjected to the trial of the Hyogo-ken Nanbu Earthquake that took place on January 17, 1995. In particular, the excellent aseismic characteristics of the WBJS works were proved through the response behavior of the Dam during the Earthquake.

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