10 soil samples included coarse sand, fine sand, sandy silt, and silty clay wererecompacted in cylindrical and cubic molds for 1 and 2-directions falling-head permeability testrespectively. The results represent that even though unsaturated condition in compacted soilscaused the seepage flow to be non-linear, Darcy's law could be applied approximately. Deviationfrom Darcy's law becomes enormous only if hydraulic gradient is less than 1. Ratio of horizontaldischarge flux to vertical discharge flux is roughly constant when hydraulic gradient is greater than1. The smaller the hydraulic gradient is, the more the ratio varies. Method of compaction hardlyaffected flow behavior in coarse sand. According to 2-directions test results, anisotropy affectedthe soils which is finer than coarse sand.

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This paper deals with a new inverse analysis of identifying the apparent elastic constants of soil and rock foundation with slides and cracks. To solve the inverse problem, RBSM analysis was combined with the extended Kalman filter algorithm. The effectiveness of the method was evaluated through three different types of numerical experiment. It was found that Young's modulus estimated by the RBSM inverse analysis showed a decrease tendency with an increase of slides and cracks. As a result, the numerical tests verified that the RBSM inverse analysis developed in this reserch work was effective to identify directed geotechnical parameters.

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The authors examined how rainfall in CB, RB, and NB blocks affects the diversion requirement of paddy field district in which return flow is reused. Major conclusions obtained in this study are as follows.
1. The rainfall of NB block does not affect the diversion requirement.
2. The maximum effective rainfall of CB block which does not use return flow of upstream RB block is G_CB (water requirement of the CB block).
3. The maximum effective rainfall of CB block which uses return flow of upstream RB block is G_CB if G_RB (return flow of RB block) is greater than Q_CB (irrigation discharge of CB block).
4. The maximum effective rainfall of RB block is G_RB (water requirement of RB block) in case of G_RB≤Q_CB or ET (evapotranspiration) in case of D_RB>Q_CB.
By the forementioned method, estimating the effective rainfall of the paddy field district whose reuse ratio is 150%, the results are as follows.
1. The ratio of effective rainfall to rainfall is 9-15%. It is clear that the effective rainfall of paddy field district in which return flow is reused is very small.
2. The average ratio of observed effective rainfall to estimated effective rainfall is about 70%. This is standard value of paddy field district in which water delivery is controlled by central water management station.

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To estimate the amount of soil eroded from the farmland due to rainfall is very important in agriculture. The present study is aimed at investigating the applicability of an equation (q_e =aK_eL_dα sinβθ q_rγ) to predict soil loss (q_e) directly from rainfall (q_r) by comparing the calculated values of soil losses with the observed soil losses and from the comparison, to determine the values of two unknown coefficients (a_c, b) which lie in the expanded forms of the equation. For this study, planting different types of crops in a free type test field, soil losses and surface runoffs were recorded after every rainfall at different growth-stages of the crops.
Under the analytical outputs of 2 year-long observations, the values of the coefficients (a_c, b) or the individual b, determined from the point of the rate of applicability of the calculated soil losses with respect to the observed soil losses in each crop are as follows:
Meadows: b=1.1-1.6, Carrot: b=1.5, Soybean:(a_c, b) = (0.9, 1.1), Corn:(a_c, b) = (0.9, 1.0), Radish:(a_c, b) = (0.8, 2.0), Komatsuna:(a_c, b) = (0.2-0.3, 1.9-2.0), Red clover:(a_c, b) = (1.0, 1.8).
From the determined values of the coefficients (a_c, b) or the individual b for each cultivated crop, it is found that in cases of the crops where the vertical distance from the ground surface to the mid-point of the leaf area is negligible (such as, meadows, carrot etc.), making no relation with the value of a_c, the only b value needs to assume to calculate the soil loss. On the other hand, in cases of the other crops with their bigger aerial parts (in the present study, soybean, corn, radish, komatsuna and red clover), from their values of (a_c, b), it has also been concluded that the cover rate and the space ratio of vegetation strongly influence the erosion coefficient and thus the soil loss.
Finally, considering the determined (a_c, b) or the only b values of each cultivated crop as the representative values for some categories of field crops having the similar characteristics, the crops have been classified into four groups, namely, i) Vegetables (Root and Leaf); ii) Grasses; iii) Beans and iv) Cereals with their respective (a_c, b) or b values.

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Numerical simulations using finite element method for water movement due to water consumption in artificial bed soil which is sprayed on steep slope were conducted. Practicability of both predicting water movement and application to steep slope were also discussed comparing numerical results with measured values from field experiment. These comparisons indicate that the proposed numerical simulation is able to utilize highly individual data such as meteorological factor, and average relative error of volumetric water content between numerical result and measured values were with in 14% at vegetated field and 9% at bare field.

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A curing method for warm keeping is effective as a method for preventing temperature cracking that occurs on concrete box culvert wall. Any temperature cracking did not occur also on the concrete box culvert, newly constructed this time, using a curing method for warm keeping.
Based on this fact, fundamental studies were carried out about curing method for warm keeping by the results of temperature measurement including a case of the past and the results of temperature analysis using 3-D finite element method of the inside of concrete wall.
As a result, critical gradient of descending temperature and environmental temperature rise of inner box culvert need to prevent of the temperature cracking were obtained.
Finally, summarizing these fundamental studies, we carried out simple systematization of a curing method for warm keeping.

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We propose a set of standard parameter values for the Long-and Short-Term Runoff Model (LST model) based on calibration in eight mountainous basins, varying in area from 21.2 to 1, 717km².
In order to see the difference between the proposed standard LST model and thecalibrated eight LST models, a numerical experiment was made. In the experiment, continuous simulation of flood and long-term runoff using 14 years data including 18 floods was carried out. It is shown that calculated peak discharges of the 18 floods by the standard LST model are practically equal to or slightly greater than the averages of peak discharges by the calibrated eight LST models. Also, flow duration curves by the standard LST model are almost equal to the averages.
Next, the 14 years data were used to compare the standard LST model with the standard tank model which Sugawara (1979, 1984) recommends. The calculated daily runoff in both cases are found to be quite close.
Moreover, for the purpose of applicability, we applied the standard LST model to daily runoff in three other mountainous basins, and found calculated daily runoff to be in good agreement with the observed runoff. The proposed standard parameter values of the LST model is expected to be useful for estimation of river flow in ungauged watersheds.

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In Okinawa, there is a need to forecast the density of suspended soil in river water after land reclamation. The purpose of this study was to develop a model for the analysis of suspended soil density.
In this study, surface water flow is first calculated using a kinematic wave model. Next, models for analysis of suspended soil density, which include the LQ equation, Meyer's model and the model developed in this study, are incorporated in the calculation of surface water flow. The data used in this study was obtained from fields subject to severe erosion in the north of Okinawa island.
The results obtained are summarized as follows:
(1) It is assumed that values of the equivalent roughness of the catchment area in the kinematic wave model differ according to the scale of runoff, in the case that surface water flows in gully.
(2) The simple LQ equation is not suitalde for analysis of suspended soil density.
(3) In application of Meyer's model, it is assumed that amount of eroded soil is affected by the sediment carrying capacity of flowing water when the land is easily eroded.
(4) In was confirmed that the model developed in this study is suitable for calculation of the density of suspended soil, when the quantitative relation between the parameter values and the condition of soil and field are known.

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Residual current (RC) in the Bungo Channel, the Seto Inland Sea, where fishing ground development is ongoing to locally augment upwelling induced by the man-made structures, is estimated using a six-leveled diagnostic numerical model. This model developed can handle the density-driven current, wind-driven current and tide-induced residual current.
To assume the situation that the upwelling effects of the structures are most depressed by stratification, the density field in August is considered. Water temperature and salinity in August from 1989 to 1993 are objectively interpolated to get the density field from the results of field observations by the Prefectural Fisheries Experimental Stations. Wind stress distribution in the same period are also calculated by the objective analysis method from the data of the Automated Meteorological Data Acquisition System, the Meteorological Agency. Moreover the tidal stress is computed from the result of numerical tidal current simulation. Incorporating these conditions obtained into the model, the RC simulation is conducted.
The computed RC field is verified by some field observations conducted in August. In particular, the RC measured directly around the structures was toward the southeast and its velocity was within the range of 15 to 20cm/s. Compared to the data, the computed current is a little small in magnitude, but the same in direction. However, it is considered that the computed RC field can be accepted as a hydraulic environment set in numerically investigating the transport of upwelled nutrients.

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An embankment structure such as an earth dam or a river bank should be designed to ensure its stability under various reservoir or river stages. The stability of an earth slope subjected to the effects of changing external water levels depends on, among other factors, stresses induced within the earth mass due to transient seepage. By using the finite element procedure which combines a saturated-unsaturated seepage analysis, a stress-deformation analysis including a sequential construction analysis and a slope stability analysis, the interaction between transient seepage, effective stress and the stability of earth dams or river banks subjected to storms accompanied by changing external water levels in the reservoir or the river is investigated.
Two main findings are identified in this study:(1) The instability of an embankment structure such as an earth dam or a river bank can be explained fairly well through the stress changes which are induced by transient seepage; and (2) two counterblows which deteriorate earth slopes should be recognized in evaluating the stability of embankment structures subjected to storms, one of which attacks the downstream slope of the embankment structure as the external water level begins to rise after rainfall and the other attacks the upstream slope during the drawdown of the external water level. It will be shown that the numerical procedure developed can offer a tool for analyzing, designing and understanding the behavior of embankment structures subjected to transient seepage conditions. Although the study is only concerned with a hypothetical and simple hydrograph of a storm and an homogeneous cross-section of the earth structure, it is possible to apply the procedure to more complicated problems involving two or more storms or a zoned cross-section of an embankment dam.

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The precise estimates of snow melt are essential to analyze snow melting. Snow melt is estimated based on the DDF method or by the use of the Runoff Model for separation of runoffs due to snow melt. However, since the hydrological surveys regarding the basin are insufficient to analyze snow melting, the both methods may cause frequent errors in estimating snow melt. Especially, the lack of observed data for the vertical distribution of precipitation and snow depth regarding the basin lead have numerous errors.
In this paper, estimated snow melt being based on the DDF method and observed raifall were used as the inputs for LST-II model.
All depths of the LST-II model were regarded as components of the state vector when the Kalman filter was used. The parameters of the Kalman filter were determined for the analysis of snow melting based on daily hydrological data. The details of the procedures and the obtained results are as follows:
1) Value of DDF was set as 6.0mm/(°C·d).
2) Dummy rainfall was adopted for the purpose of improvement of the system.
3) Dummy rainfall was estimated to be 5.0mm/d for the analysis of snow melting in this basin.
4) Covariances of the system noise and observations were determined based on the simulations of the LST-II model using a Kalman filter.
5) The depth of the second tank in LST-II model were controlled within the upper limit restricted by the physical dimensions of the model, so that the Kalman Gains of the four tanks could be modified by referring to the control of the depth of the second tank.
6) It could be shown that the Kalman predictions for daily runoffs by the use of the identified covariances and the dummy rainfall agree well in many cases with observed daily runoffs, with the exception of those with a abrupt rise.

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Nitrate solution with several different pH were percolated into three kinds of soil columns under saturated conditions. These soils were Kantoh loam surface soil, subsoil and Yellow soil respectively. Main clay mineral of Kantoh loam was allophane and Yellow soil was kaolinites. The distribution of water pressure potential, pH of soil water and concentration of salts in the soil columns were measured. The results were as follows.
1) The soil permeability for Kantoh loam subsoil was decraesing with percolation time due to the dispersion of the soil particles at the surface of soil column.
2) The soil organic matter had the mechanism to control the dispersion of soil particles, so the reduction of soil permeability was small in the case of Kantoh loam surface soil.
3) Yellow soil particles were flocculated in low pH nitrate solution, so the reduction of soil permeability with time was small.
4) The soil surface area for ion exchange increased in proportion to the dispersion of soil particles. Then the quantity of salts displaced from the soil surface by the hydrogen ion increased in the case of soil particles dipsersed condition. The degree of salts leaching for Kantoh loam subsoil was large as compared with another two soils.

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This study was conducted to clarify the soil moisture environment in an artificial forest over the course of a year by observing the soil moisture conditions and water consumption properties. Locations where Abelias, Katuras, and Loropetalume chinensis Olives were planted were selected for study. The results are as follows.
The driest conditions were observed where Katsuras planted during summer, and the wettest conditions were observed where Loropetalume chinensis Olives planted.
The soil moisture conditions through the winter season were maintained to be over-wet in all places, so that the drainage should be necessary to improve the poor conditions.
Finally, the highest daily consumption was observed during July or August. On the other hand, the ratio of consumptive use in the lowest soil layer was the smallest, but the differences of that in other soil layers were not so clear.

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This study was conducted to clarify the soil moisture environment in orchard over the course of a year by observing the soil moisture conditions and the properties of water consumption. Locations where Japanese pears and Japanese persimmons planted were selected for study.
Furthermore, the soil moisture environment in the orchards was compared with that in the artificial forest had been reviewed by applying the average of soil moisture tension through all soil layers measured. The results are as follows.
Dry situations of soil layer in the both locations were observed only within 40cm soil layer during the summer season even as well as other general orchards.
Soil moisture conditions during the winter season were maintained to be overwet in both places, probably the drainage should be necessary to improve the bad conditions.
The highest daily consumption occured during August or September. On the other hand, the ratio of the consumption in the upper layer, that is, surface soil layer above 40cm depth, was found to exceed 80%.
Finally, comparing the soil moisture environment in the orchard with that in the artificial forest, the average of soil moisture tension through all soil layers measured in the latter was above pF 2.5 at summer season, but that in the former below pF 2.0. However, both were overwet during the winter season.

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We carried out a questionnaire survey on municipalities of the IntegratedRural Development Model Project districts to grasp an understanding of actual conditionsof development and use of village parks as a basic investigation to develop planning methods for village parks. In this report, we discuss the use and maintenance of village parks, and abstracted the problems of park planning. We obtained the following results:
(1) Uses of parks are tending to diversify (growth of sports and enlargement of community function), and produce various requests for non-typical development.
(2) Municipal officers are tending to feel distrust toward mechanical development in districts with low rates of use, because of depopulation. Unique measures are desired for planning park systems in these districts, such as mountainous areas.
(3) Municipalities are tending to entrust park maintenance to resident organizations. However, role-sharing and clarification of cost-sharing is still inadequate.

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We carried out a questionnaire survey to municipal officers of the Integrated Rural Development Model Project districts to grasp actual conditions of development and use of village parks as a basic investigation to develop planning method for village parks.
In this report, we will discusse the function and form of the ideal village park. We obtained the following results about characteristic tendency:
(1) The desired functions of parks are tending to diversify from specialization ininfantile and juvenail play.
(2) Desires towards park form and green style are changing, and desires for sportsfunctions as well lawn areas and tree shade was also strong.
(3) There are many districts that desiring regional parks such as the multipurposespace and comprehensive park.
(4) Desires towards park form closely approximated study results for city parks inmany ways.

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A two-dimensional unsaturated soil water flow with root uptake under drip irrigation was modelled using numerical techniques. Capillary supply and percolation loss in the root zone, side zone and lower zone were estimated by the model under drip irrigation. The numerical solution used was the Finite Element Method. Soil water distribution was measured by the gamma ray attenuation method. The following results were obtained:
1) Soil water content estimated using the model simulation was compared with measured values and found to be within an average relative error of 39%.
2) Total amount of capillary supply estimated using the model simulation was compared with measured values and found to be within an average relative error of 15%.
3) It was observed that water losses due to percolation later became available to the plant through capillary supply.
4) The study also showed that capillary supply increased with increased remaining soil water.
5) From the model results, using existing sugarcane root distribution field data, it was suggested that the model could be used in irrigation scheduling.

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Water flow in plants closely relates to various plant physiological activities. Nevertheless, most models of soil-plant-atmosphere continuum (SPAC) have been traditionally considered as a totally physical phenomenon. Recent findings in plant physiology have revealed that the stomatal control has nothing to do with the leaf water potential, but with the root signals that are produced at the condition of water deficit in roots. That is, several experiments have demonstrated the mechanism that hormon, like abscisic acid, transfered along with transpiring water flow acts guard cells to close stomatal openings when soil becomes dry. We suggested that this fact might greatly change the SPAC model in future, and discussed the remaining problems.

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