Although the amount of dew is not very large, it is a source of water supply to fields, and dew plays a significant role in the reduction of transpiration after sunrise. It is thus important to determine the amount of dew in the fields.
In this paper, the amount of dew in soybean fields was measured by sponges in summer seasons. In addition, some meteorological factors were measured, simultaneously.
The following conclusions were obtained ;
(1) After sunset, the total amount of dew and the amount of dew per hour increased with time until sunrise. The amount of dew on the soil surface was almost 0, however it increased with the elevation. The maximum amount of dew was 0.42 (kg/m²) at height of 1.8m.
(2) The authors considered that dew was an opposite phenomenon to evaporation. The amountof dew were simulated using the equilibrium model. The simulated amount of dew per hour and the total amount of dew in the soybean fields were in close agreement with the observed data.

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A conceptual model was applied to analyze the upward soil moisture flux in soybeanfield consisted of Kanto-loam soil. Growing conditions of soybean was built in the model. Meteorological data and observed root length data were used for simulation on soil moisture flux in the fields.
(1) The obtained results were as follows;(1) The fractions of transpiration and evaporation to evapotranspiration (T_r/E_t, E_s/E_t, respectively) and elongation of root (root length) were built in the model for the simulation analogy on soil moisture flux. It is clarified that the proposed model was useful to explain observed data.
(2) Soil moisture flux was able to be simulated with this model. As the evapotranspiration, T_r/E_t and the depth of effective layer were obtained, it was possible to evaluate the soil moisture flux phenomena throughout crop growing period.

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Meteorological observations were made for the Feasibility Study on Rural Development carried out Namushakende area which is situated on the Zambezi River Flood Plain, Western Province, Zambia. On the basis of on the observed findings, evapotranspiration rates from ground surface were estimated in the cool-dry season. The results are summarized as follows;
(1) Hourly evapotranspiration rates calculated using the Bowen Ratio Method required modifications due to unstable results. On the contrary, potential evapotranspiration rates calculated from the Penman equation were quite stable.
(2) At Namushakende, the ratio of daily evapotranspiration rates calculated from the Bowen Ratio Method on daily evapotranspiration from the Penman equation was 0.33. This ratio, which was calculated using meteorological data observed in the dry season, could be judged as a proper value for this period.
(3) It was clear that both values of daily evapotranspiration rates at Namushakende and Mongu Meteorological Station, showed a good correlation. According to the investigations described above, a result of estimation for mean daily evapotranspiration rates at Namushakende for 100 days from March to June was 1.4mm/d.
(4) From the daily fluctuations of the estimated evapotranspiration at Namushakende, it was verified that the evapotranspiration rate at Namushakende did not decrease rapidly at the end of the rainy season and in the cool-dry season. This phenomenon seems to be related to the existence of a springing water source flowing into the eastern plateau, which influence the evapotranspiration rate. Therefore, the role of this underground water can be important for water use planning.

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Interceptive layer is effective for controlling spring water as it catch spring position in a wide area. In this paper, we report the effect of interceptive layer which was arbitrarily installed to the spread spring source.
The characteristics of groundwater dynamics were analyzed by Yoshida and other's method of finite element methods (1993). The results obtained are summarized as follows:
1) The potential in center of spread spring source greatly influenced groundwater table.
2) When interceptive ratio attained 20 percent or more, the groundwater level lowered remarkably from the initial level. In this case, interceptive layer covering the half area of spring showed nearly the same effect as complete cover.
3) In the case that spring source was located at a special place between both side drains, the drainage effect decreased markedly. This bad condition was improved by moving the center of interceptive layer a little from spring source.

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The finite Markov chain was employed for the prediction of progressively expandingdesolated fields of settlements. It is well known that the Markov chains are commonly used in connection with time series. In this study it was found that a Markov chain is adaptable and useful for evaluating the principal factors of desolated fields, though it is not time series. One hundred and five settlements were selected from large rural areas with progressively desolated fields in Japan, and were classified into 5 groups by the fuzzy set theory. The effect of single principal factor on the multiple social aspects was discussed. For example, from the results of the finite Markov chain, it was found that the road conditions are very important factor of land use planning in restraining of the advance of desolated fields, the increase in the length of the paved road is more desirable than the increase in the length of the road wider than 3.5m. These results were consistent with the study cited above, and were confirmed by concrete cases. From this study a model for a Dynamic Land Use Planning may be developed.

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The amount of roots, physical (dry bulk density, pF, soil hardness etc.) and chemical (Cl^-, SO₄^2-, N_a etc.) properties of soils in each soil profiles were investigated in A₆ field (natural plot, where Phragmites australis (Cv.) Trin. ex Steud. is still alive in the field) and A₁₀ field (hay field, where grass is cultivated continuosly without plowing) of Hachirogata Central Polder, to elucidate the differences in the effects of Phragmites and grass on the drying of Hedoro ground. The results obtained are as follows.
1. The amount of rhizomes and roots of Phragmites are about 83% in the layers between 20cm and 100cm deep of natural plot. On the other hand, the amount of roots of grass is about 90% in the layers between surface and 20cm deep of hay field.
2. In the layers between surface and 20cm deep of hay field, the dry bulk density increases and water retentivity becomes lower, compared to those in the natural plot. In the layers 50cm and 100cm deep of natural plot, the dry bulk density increases remarkably and water retentivity becomes lower, compared to those in the hay field.
3. The volumetric water content and hardness index of the soils in the natural plot and hay field are nearly proportional to the dry bulk density in the region between about 0.35 and 0.6g/cm³ respectively.
4. The depth of the invasion of gaseous phase in the natural plot is greater than that in the hay field.
5. Cl^- content of the soils in the natural plot and hay field are 29ppm and 358 ppm in the layers between surface and 100cm deep respectively.
6. In the layers between 30cm and 100 cm deep, SO₄^2- content of the soil in the natural plot is about three times as much as that in the hay field.
7. Na and Mg content of soils in the natural plot become lower in layers more than 70cm below the ground surface, compared to those in the hay field.
8. EC (mS/cm) of soil in the natural plot is very small in layers more than 70cm below the ground surface, compared to that in the hay field.

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For improvement of river environment, it is important to make clear flow structures around pilelike construction, for example, bridge piers, series of piles, etc. Former hydraulic studies on cylindrical piers paid much attention to scouring process, mechanism and its prediction for the purpose of bridges' safety. As a result, most of these studies above have not brought up the characteristics of water surface profile and mean flow around them. In this paper, plain characteristics of water surface profile around series of piles are studied on the basis of mean velocitydistribution in open channels.
The results obtained in this study are divided into 3 steps as follows;
1. Water surface profiles and velocity distributions around a single pile and three piles (set closely along a line with attack angle against flow) were measured in the flume tests with fixed bed. Water surface profiles around them were characterized by standing waves and interference between them, and had a close relation with velocity distributions (Calculation-I, Chapter II).
2. The two-dimensional modeling of flow around piles was carried out, based on the analysis of experimental results. The computed results were well confirmed by experimental ones (ChapterIII).
3. Transformation of water surface profiles and velocity distributions around two close piles according to the variation of attack angle were calculated by the two-dimensional model (Calculation II). It was suggested that there was a critical attack angle which corresponds to sudden rise phenomenon of scouring magnitude observed in the former experiments on two close piers(Chapter IV).

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Of the three known types of alkali-aggregate reactions, the alkali-silica reaction is considered to be the most damaging to concrete.
This study relates to the alkali-silica reaction in a concrete cylindrical specimen made by using a coarse aggregate with pyroxenic andesite. An effective way to judge the alkali-silica reaction in a coarse aggregate can be done by using the repeated auto-clave curing method on a concrete cylindrical specimen.
This research focuses on the repeated auto-clave curing method on a concrete cylindrical specimen into which alkali and pyroxenic andesite was added.
The concrete cylindrical specimen was cured at 40°C in the container after repeated auto-clave curings. The results, obtained directly after the repeated auto-clave curings, were compared with the results of a 1, 000 day container curing and the effectiveness of the method was confirmed to be the same.

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In order to clarify the possibility of paddy fields reclamation in the desertificating area of Maowusu desert in China, two soil samples were made experiments in percoration control of paddy field reclamation in laboratory. One was at Yulin of the progressively desertificating area, and the other was sampled at Lantian of the southen edge of the Loess Plateau.
A well developed system of soil pores that had been produced by plant roots, named as “pore system formed by roots” was observed in Yulin samples by means of the x-ray stereoradiography using contrast medium. The permeability coefficient of undisturbed soil samples were so high that the countermove against excessive percolation will be necessary for paddy field reclamation in this area.
The results of permeabilty tests of compacted soils showed that the permeability coefficients are lower than 10^-6--7 cm/s, Lantian sample which has hight clay content is the same permeability characteristic of compacted soil with Japan's volcanic ash soil and Kanto loam, but Yulin sample which has high fine sand content is somewhat different with Japan's.
We also obtained the following results: the soil for plow layer which contains lower than 9.5% clay content can not be reclaimed to paddy field by puddling ; and the soil for plow layer which contains higher than 6.0% clay content is necessary for Crushing and Compaction Method in this area. It is possible to reclame paddy field by puddling in Loess Plateau becauce the soil clay content gradually increases from the north to the south.

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Recently, Neogene mudstone is being adopted as foundation of fill-type dam due to the lack of competent rock site in Japan. In this case, engineering problems such as the settlement of foundation due to the weight of embankment would occur. Hence the elastic moduli of material should be carefully evaluated from a very small strain level up to 10^-3 in order to calculate the deformation of the foundation during the embankment construction.
To investigate the deformation characteristics in small strain region, both triaxial compression (UU) and dynamic tests are performed in cylindrical specimens of Diatomaceous mudstone prepared in vertical and horizontal directions with mechanical anisotropy. The triaxial compression tests make it possible to evaluate not only the difference of Young's moduli due to cross-anisotropy, but also the variation of those with strain level at 10^-5-10^-3 obtained by measuring the axial displacements over the central half of a specimen by gap sensors. The dynamic tests comprising both resonant column and pulse methods, five independent elastic constants of cross-anisotropy including Young's moduli are established at small strain (about 10^-6) by measuring the resonant frequencies, compressive (P) and shear (S) wave velocities in vertical and horizontal directions.
The results obtained are summarized as follows:
(1) Specimens with the higher strain level exhibit the greater anisotropy as reflected by the ratio between the horizontal to vertical Young's moduli.
(2) The dynamic test results indicate that the strain dependency of Young's modulus in vertical direction exists to some degree even at 10^-6 strain level.
(3) The ratio between the horizontal to vertical shear modulus is greater than that of Young's modulus; it suggests that the Diatomaceous mudstone behaves as a cross-anisotropic material and the small strain Young's modulus in vertical direction as inferred from down-hole measurements assuming isotropy can be underestimated.
(4) Using laboratory dynamic test data, all elastic parameters of Diatomaceous mudstone with cross-anisotropy are determined.

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Based on the many pioneer works on earth pressure on buried pipes, it is confirmed that arching around the culvert increases the vertical pressures on the top of a culvert and reduces the horizontal pressures on the sides of a culvert. Because of the practitioners' interest in a more rational structural design of buried conduits, much attention has been paid to the vertical load imposed on the top of a conduit than on the sides. In cases of culverts constructed under fill dams, however, the present authors infer that the conditions (of reduced stresses) adjacent to the sides of a conduit are critical to the danger of hydraulic fracturing at a stage when the horizontal stresses exerting on both sides of a culvert become lower than the reservoir water pressure. Based on this inference, the authors further postulate that hydraulic fracturing is the most likely cause of leakage (mostly concentrated leakage) and of failure of many low dams along the outlet conduit especially after heavy rain. Two case studies supplemented by FEM analysis are presented and the results clearly confirm the authors' inference. Some countermeasures to cope with this situation are also recommended.

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The problem studied is associated with the iterative techniques employed in simulating the steady state salinity intrusion in a coastal groundwater. Two widely used iterative methods for simulation, the Picard method (PCM) and the Partial Newton method (PNM), are considered. Properties of both methods are investigated and contrasted in terms of rapidity and stability of solution convergency. It is mathematically elucidated that the solution performance of PCM is identical with that of PNM when properly underrelaxed in its iterative process. With respect to the manner of relaxation in application of PCM, many numerical experiments imply that such relaxation should be done only to the solutions of salinity, but not to those of velocity, and at the same time the value of the relaxation parameter should be iteration by iteration varied in an appropriate manner. As a useful methodology for reasonably varying the parameter value, incorporation of the fuzzy reasoning in the method is proposed. The results show that the variable relaxation induced from the fuzzy reasoning is indeed capable of making iterative process paramount in comparison with PNM and the other conventional relaxed PCM.

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Nocturnal thermal environments in Kanto and Koshin-etsu region of Japan in winter were analyzed using LANDSAT TM thermal-IR images. Four scenes in winter (14th Dec. 1984, 25th Feb. 1986, 26th Dec. 1986, 27th Jan. 1987) and one scene in summer (4th Aug. 1984) were investigated. Digital terrain model data, air temperature data at 68 AMeDAS stations and aerological observation data at Tateno were used simultaneously.
The LANDSAT thermal images were geometrically corrected to UTM coordinates by affin transformation. An atmospheric correction was performed on these images using LOWTRAN 7. Digital numbers of the thermal images were transformed into radiation brightness values using NASA model equation. Radiation brightness values were converted into surface temperatures according to the transmittanse and the pass radiance calculated from LOWTRAN 7.
Changes in surface temperature with elevations were closely related with the vertical profile of atmospheric temperature. The inversion layer due to radiative coolings appeared in the relation between surface temperature and elevation as well as in the relation between aerological data and elevation. The inversion layer did not appear in air temperature profile in the third scene.
Surface temperatures depended on the terrain structures. Scenes in winter showed the cold air lakes in valleys, low surface temperatures due to radiative coolings at plains and the warm layer at ravine hillsides. The cold air lake also existed in summer.
The range of area where the surface temperature affects the air temperature was about from 100 to 300 m. In winter, correlation coefficients between mean surface temperature in the range and air temperature showed the second maximum peak at larger range of several kilometers. Especially, the third scene showed the highest correlation coefficient in the scenes.
Surface temperatures were highly correlated with air temperatures, and the correlation coefficients were about 0.9. Spatial variations in surface temperatures were greater than those in air temperatures.

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In order to prevent thermal cracking in the wall of a concrete box culvert annexed to an agricultural road, caused by thermal stresses due to the hydration between cement and water, inspection and construction aimed at preventing such cracking were carried out in southern Kyushu district. Assuming the lower slope of the fall in temperature of the wall to prevent thermal cracking, the air temperature inside the box was raised slightly using a portable furnace for briquettes in comparison with the temperature outside the box. This preventive construction system abolished the appearance of cracks.

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Detailed measurements of temporal and spatial changes in water and solute contents in soil may improve knowledge of water and solute dynamics in soil. With the knowledge, more appropriate and efficient soil and water management could be explored. Recent development of time domain reflectometry (TDR) techniques enables to simultaneously and promptly measure soil water content, θ, and electrical conductivity, EC. To make automated data collection from several TDR probes, a computer-controlled and multiplexed TDR system was constructed. The system was applied to a field experiment on furrow irrigation with≈0.3 Sm^-1 NaCl solution in a bare sandy loam soil. Twenty four three-wire-type probes were horizontally inserted in a two-dimensional soil profile. Data were collected every 15 min for≈2 months. Spatial and temporal changes in two-dimensional distributions of θ and EC of soil water were successfully measured. The system was also successfully applied to estimate the hydrodynamic dispersion coefficient of loamy sand in the laboratory. This TDR system may be a useful and efficient tool to examine temporal and spatial distributions of water and solute in soil.

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In rural depopulated areas, the difficulty in maintenance of the social system and the increase in derelict land have become serious problems because of depopulation. It is feared that the decreasing in population may have damaging effects in the ecological functions of farmland and woodland.
In this paper, the structure of depopulation, which is important to think about the regional activation due to rural improvement, was investigated as a case study of Shimane Prefecture. First, depopulation factors were drawn from opinions of the persons in charge of depopulation measure in local government, and the interpretive structure of depopulation factors was obtained. The relations of depopulation factors were understood by means of this structure. Next, influential relationships were obtained by using structural modeling (ISM method and Dematel method), and effective measures against depopulation were investigated.
The following results became clear. Insufficiency of improvement of facilities is connected with the decline of farmers' desire for agriculture, the decrease in young generation and the gap in the living environment between urban and rural area, and these factors are connected with the decline of regional vitality and image in the long run. The decrease in young generation is caused by problems about the dullness of agriculture and forestry and working places, and these whole factors bring about the decline of regional vitality and image.

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The number of small reservoirs, which are distributed over the middle and mountainous areas in Ishikawa Prefecture, is around 3, 000. Of all the prefecture, 80% of that type of small reservoir is located in Noto. The high number of small reservoirs in those areas provides us with a good reason to choose this region as a research model. We chose 17 areas in four cities and towns in Noto, and carried out investigation on the water management of those small reservoirs through questionnaire. The results are as follows:
1) Every small reservoir in each of those area has its own function and is operated by small reservoir operators. Several small reservoirs are managed as a group in order to gain complementary merits. This average volume of small reservoir is 231 mm in depth. In general, the inlet water, which is 2 to 3 times as much as individual small reservoir volumes, flows into small reservoirs from catchment areas.
There are 4 kinds of water resources: river water, underground water, water coming from mountain streams and the water from small reservoirs. In combination with these differences of water resources, each area utilizes small reservoirs as integral water resources.
2) In order to puddle and make ridges between rice fields, farmers primarily use rain water stored in the paddy fields and water from mountain streams. After puddling, small reservoir water is begun to use. The standard releasing time of individual small reservoirs is limited to within daytime hours. And, in general, each beneficiary takes irrigation water into paddy fields. Some communities, however, have 60-70-year-old specialists as watermen who are in charge of supplying water into paddy fields.
3) In an average year, precipitation is 496 mm in depth if it is calculated on the condition of 80% as an effective ratio. The amount of irrigation water released from a small reservoir is 613 mm. Therefore, the total amount of irrigation water corresponding to demand is 1, 109 mm. In 1994, the drought year, the amount of both precipitation and small reservoir water was 60% less than those of the average year. That resulted in 665 mm of in-depth water shortage for paddy fields. That was the reason why great efforts were demanded on the part of community farmers to get irrigation water from mid-June to the end of the irrigation period.

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Of the three known types of alkali-aggregate reactions, the alkali-silica reaction is considered to be the most damaging to concrete.
The earliest study in Japan on the alkali-silica reaction was by Fujii (1950), and in the past few decades his work has been followed by a number of reports on this aggregate reaction. The present paper aims to review these studies and survey the current thinking concerning alkali-silica reactive aggregates and methods of testing them regarding their reactivity.
Most of these studies share the view that andesitic rock are generally more liable to the alkali-silica reaction than other types of rocks.
Iiyama (1987) and other authors attributed this type of reactivity to, among others, chart and sandstone. Furthermore, it is known that rocks of the same type can show varying degrees of alkali reactivity depending on their specific formative origins.
Therefore, aggregate rocks to be used for concrete must be thoroughly tested individually for their specific reactive properties.
Standard tests of alkali-aggregate reactivity currently used are the chemical method and the mortar bar method. However, these types of tests are not without problems such as the reliability of reactivity judgments made by means of them and/or the length of time that they will take before the test data are obtained. To deal with these problems, Tamura (1986) and Houzyo (1996) each proposed a special form of testing experiment devised to accelerate possible alkali-aggregate reactions and enable quicker obtainment of the test results.
The researchers' goal at present is to develop optimum testing methods which will not only yield the test results in the shortest time possible but also enhance the reliability of judgment.

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