The aggregate of soil was classified into 4 groups according to the stability of structure. They were remolded, water-stable, non-water-stable and flocculated ones. And the relation between the physical properties of soil and soil type was researched based on this classification.
Measurements on 22 soil samples for 5 items including 11 factors were carried on, and the following results are achieved.
1) The degree of aggregation is closely related to the moisture characteristic of soil.
2) Natural soil structure corresponds to the stability of soil aggregate.
3) The relation between soil type and aggregate of soil is explained by the numerical expression of soil color.
Based on the above, it may be possible to estimate the macro-physical properties of soil by soil type, through the following processes; soil group→natural structure→stability of aggregate→ physical properties of soil.

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To implement farm land consolidation that takes into consideration mobilization of land for agricultural use and formation of land use order (planning subjects), the “Kande method” as a planning method of a comprehensive district plan is effective. The “Kande method” is composed of planning organization, planning composition and a set of investigations. This paper focuses its attention on the planning organization which is the first condition of the “Kande method”, and clarifies the mechanism of its effectiveness.
The first condition of the “Kande method” is that the planning organization should have both a council of a district and a council of a settlement (two-layer type), but there is also the idea that it should have only one council of a district (single-layer type). This paper examines and compares the experimental results of the first period of making a comprehensive district plan in the Kande district and Nagao district in Kobe city (two-layer type) with the last period of a district (single-layer type), and makes clear the points mentioned below.
(1) The two-layer type is effective, because the two-layer type (which is applied to the last period of making a comprehensive district plan of the Kande district and Nagao district) accomplishes the planning subjects, but the single-layer type (which is applied to the first period of making a comprehensive district plan of the Kande district and Nagao district) dosen't accomplish them.
(2) The reasons why the two-layer type is effective are because the district leaders, municipalities and planners attend a general meeting of a settlement and explain various problems related to a district and the making of a comprehensive district plan and the inhabitants and their supporters discuss them at each stage; examining a written investigation of self survey, a written pilot plan and a written master plan. Therefore the awareness of the residents of a district is reformed and the district leaders and district residents take active interest in making a comprehensive district plan.

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To implement farm land consolidation that takes into consideration mobilization of land for agricultural use and formation of land use order (planning subjects), the “Kande method” as a planning method of a comprehensive district plan is effective. The “Kande method” is composed of planning organization, planning composition and a set of investigations. This paper focuses its attention on planning composition, which is the second condition of the “Kande method”, and clarifies the mechanism of its effectiveness.
The second condition of the “Kande method” has the following three steps;
1) making up and examining a written investigation of self survey, 2) making up and examining a written plan of a pilot plan, and 3) making up and examining a written plan of a master plan (three-step type). On the contrary, there is another idea that it should have only two steps; in which the two steps above, making up and examining a written investigation of self survey, and a written plan of a pilot plan are merged. This paper examines and compares the experimental results of making a comprehensive district plan of the Nagao district in Kobe city, which uses the three-step type, with the Ozo district in Kobe city, which uses two-step type, and makes clear the points mentioned below.
(1) The Nagao district, which uses the three?step type, makes up a master plan which gets synthesis, consistency and effectiveness and accomplishes the planning subjects, but the Ozo district which uses two-step type, does not always accomplish them.
(2) The following three points are the reasons why the three-step type is effective. 1) District leaders and district inhabitants gain a comprehensive understanding of a district and are willing to make up a pilot plan during the process of plan making and discussing. 2) District leaders and district inhabitants recognize the planning subjects of a district, have a shared vision of the district, and assess development and make up frameworks for the land use plan. 3) District leaders and district inhabitants adjust differences of each plan from the viewpoint of the middle or long term, determine priorities of projects, and consent to land consolidation projects.

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The method of decision on the hydraulic dimensions of intake channel for the bar screen type torrent intake has been based on the side channel spillway of the fill dam. And the depth in the side channel spillway has been calculated by application of the momentum equation.
However, speaking of the bar screen compound type torrent intake which has large installation angle of the bar screen such as 45°-50°, the inflow discharge through the bar screen forms secondary flow in the intake channel, then its velocity decreases and the cross-section becomes large. It goes without saying that secondary flow is formed in the side channel spillway, but in case of intake channel, as height of drop is high and width of intake channel is small, the effect of secondary flow is large.
In this paper, the authors make a proposal on the method of decision on the hydraulic dimensions of intake channel adding velocity head to uniform flow depth, and we clarified above method through both of the hydraulic model test and existing works.

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The so-called technique of fictitious coefficient of permeability was utilized as a supplement to the analysis of seepage problems by finite element computer program. The improved program is able to solve seepage problems on various conditions, even non-Darcy flow condition. 3 models of earth dam were taken into consideration, and then the distributions of both horizontal and vertical hydraulic gradient, the engineering value which is necessary for some computations such as the inspection of safety against piping, were derived. In regard to the results presented herein, the critical zone of the computations is the downstream side of earth dam. For non-Darcy flow which has no coefficient of permeability, fictitious coefficient of permeability that is necessary for the filter design of earth dam was found and showed in vertical coefficient to horizontal one form. Flow direction can be estimated from the ratio, water rather flow in horizontal direction for high ratio and in vertical for low ratio.

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In order to take the nonlinear and anisotropic characteristics of permeability into account, technique of fictitious coefficient of permeability was utilized. 36 calculations on miscellaneous conditions were made by FEM. These calculations used relationships between hydraulic gradient and discharge velocity by experiments. The relationships between hydraulic gradient and discharge velocity showed the non?linearity (that is, non-Darcy relationship) and the anisotropy.
Except for the isotropic, non-Darcy and low hydraulic gradient flow condition in which the hydraulic gradient-vertical discharge velocity relationship by an experiment was used for calculation in both of horizontal direction and vertical one, those calculations gave reasonable results. In the exceptional condition, the calculation could not give appreciable result because the hydraulic gradient-discharge velocity relationship provided very low velocity but high threshold gradient.

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Some relationships between the multiplication of phytoplankton and water environment were investigated from the observation in the eutrophicated agricultural water region on the coast of Ariake bay. Similarity of phytoplankton flora estimated by Kimoto's similarity index can be roughly explained by the water use conditions. The similarity index appears high in the case when the first dominant species of both stations are the same, so the first dominant species is important. The diversity index (DI) of phytoplankton decreases as water pollution progresses, and then Chlamydomonas globosa mainly dominates. It is assumed that Chl. globosa is one of the species that can grow easily and dominantly in a eutrophicated condition. To estimate the proportion of individual phytoplankton from the water quality of primarily grown species, regression analysis was applied. Both the proportion of Trachelomonas scabra and Tribonema sp. are in direct proportion to the Cl_- concentration, and Dictyoashaerium pulchellum is to the TN: TP ratio. From the relation between the proportion and water quality of eutrophication, the species could be grouped into two categories, one composed of Chlamydomonas and Trachelomonas and the other composed of Melosira and Dictyoashaerium. Significant regression equations with the proportion of phytoplankton as a target variable, and water quality as explanation variables were carried out for six species.

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There exist several methods for analyzing two-dimensional elastic bodies, and sometimes photoelastic studies have been carried out for foundation problems. In the photoelastic studies a finite plate with free side ends is usually used. Accordingly, boundary conditions for this study do not correspond to those for foundation problems. In addition, the former is plane stress but the latter is plane strain. For these reasons, the results of the photoelastic study may not correspond to those of foundation problems. The main objective of this paper is to investigate discrimination of two-dimensional elastic solutions by the stress function method. The stress functions for plane strain and plane stress were derived separately in this paper. The results obtained indicated the stresses and the displacements were expressed by only one biharmonic function. The formulae for the plane strain corresponded to those of Love's stress function for an axially symmetric elastic body. Several numerical examples were presented, and one of these was compared with the result of the photoelastic study. It was shown that an elastic body with stress only as the boundary condition yielded identical stresses for plane strain and plane stress, but an elastic body with stress and displacement as boundary conditions yielded different stresses for plane strain and plane stress.

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Applicability of a neural network model to the estimation of chlorinity variations in a tidal river has been studied in relation to optimal inputs for the model. Feedforward multi-layered perceptron model was adopted along with the generalized delta learning rule for determining weighs and thresholds of the network and the genetic algorithm for learning steepness parameters of sigmoid functions. The chlorinity data observed during non-irrigation season at the estuary in the Chikugo River, and at Morotomi located at about 7.3 km upstream from the river mouth were analyzed by the model.
To estimate a chlorinity at the present step, observed fresh water discharges and observed or calculated water-stages at the past several time steps were allocated input-layer of three?layered perceptron model. The applicability of the model was estimated using square errors obtained from the difference between calculated and observed chlorinities, and the optimal inputs to represent chlorinity variations were determined at the least square error.
The learning method using both the generalized delta learning rule and the genetic algorithm had good performance to represent chlorinity variations. The model needed longer history of fresh water discharge and water-stage as input at the estuary, because of strong mixture of fresh and salt water compared with the upstream region.

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The Long-and Short-Term Runoff Model (LST Model) is applied to Takayama dam basin of 615km² in which Syorenji and Murou dams with catchment of 100 and 136km², respectively, are situated at tributaries. Hydrological data observed at three dams and in and around their basins for ten years from 1978 are used in this study. In the application of the LST Model to the residual basin of Takayama dam except the above-mentioned two dam basins, discharges from the two dams and their traveling times are considered. The effects of the basin lag time defined as the time lag between peaks of input into and output from a basin are examined on the accuracy of simulated flood runoff hydrographs and on the model parameters identified.
Moreover, the basin scale effect on parameters of the top tank of LST Model is discussed theoretically based on the kinematic runoff model for surface and subsurface rainwater flow. Usefulness of the proposed theoretical equations showing the relationship between a parameter of top tank and basin area is verified by the results of above-mentioned three dam basins and another ones of seven basins which have been already reported.

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The function optimization methods have been widely used to estimate parameter values of rainfall-runoff models, but it is generally difficult to obtain an unique set of optimal parameters by using standard local-type search procedures because of the presence of multiple peaks in the response surfaces of objective function. In this study, several global optimization methods: the genetic algorithm (GA), the shuffled complex evolution method (SCE-UA) and the multistart procedure of local search methods are introduced to cope with such difficulties. Two local-type and sixglobal-type optimization methods are applied to the parameter estimation of the Sugawara's Tank Model with sixteen parameters and the efficiency of parameter estimation and the consistency of estimated parameter values are evaluated by numerical experiments using synthetic data. Results obtained are summarized as follows:
(1) The consistent parameter values are not obtained by using local-type search procedures: the Nelder and Mead's simplex method and the Powell's conjugate direction method.
(2) The Powell method is more effective than the simplex method. Therefore, the multistart Powell method is also more powerful than the multistart simplex method.
(3) The GA is not effective and efficient, but its performance is improved by further tuning by local-type optimization methods.
(4) The SCE-UA method and the multistart Powell method are obviously superior to other methods for the parameter estimation of the Tank Model. Considering the efficiency, the SCE-UA method shows the best performance.

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Until now the problem of abandoned agricultural field is understood as a problem only within mountain region. Certainly the rate of abandoned agricultural field in the mountain region in 1990 is the highest among the four region types. And the region in undulated and mountain region shares more than the half. But now the problem become worse also in urbanized region. The increase rate of abandoned agricultural field in urbanized region is the highest from 1985 to 1990. So the authors studied distribution and factors of abandoned field to analyze agricultural census in1990 in urbanized municipalities in Kanto region.
Firstly, distribution in urbanized municipalities was studied. The municipalities that the rate of abandoned paddy field is high are mainly distributed in a circle between 20km to 50km from theurban core of Tokyo. The municipalities that the rate of abandoned upland field is high are also distributed in a circle between 30km to 60km.
Then, relating factors in urbanized municipalities was studied. The factors of abandoned paddy field and upland field are not the same. The characteristic factors of abandoned paddy field are agricultural infrastructure improvement and land value. The characteristic factor of abandoned upland field is labor force in agriculture. And the main factor of all abandoned agricultural field is existing in agriculture itself. But the factors about the impact from urbanization have a strong influence on abandoned agricultural field. So if farming environment in urbanized area is not so better than undulated and mountain area, the problem in urbanized area become worse.

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There exist many types of plate loading tests for structural design of pavement, and various elastic analyses for semi-infinite axi-symmetric multi-layered system have been carried out. Elastic analysis for a single layered semi-infinite system subjected to normal load along the boundary is the well-known Boussinesq's problem. Recently, elastic analyses for the multi-layered and the single layered axi-symmetric system restrained in a cylinder have been presented by the author, but the boundary conditions of these analyses were perfectly smooth along the side surface of cylinder. The objective of this paper is to present an elastic analysis for a single layered system restrained in a cylinder with a rough side surface. This method is based on Love's stress function using infinite series of Fourier-Bessel expansion and Fourier expansion. Some numerical results were obtained using a computer, and the effects of boundary condition and Poisson's ratio on the deflection of the loading surface were discussed.

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The relation between NO₃-N concentration of outflow water and land use in agricultural area was investigated in Hokkaido. Five areas were selected as follows: 1. Furano; forest area, 2. Kushiro; grass land area, 3. Nemuro; grass land area with high cow density, 4. Obihiro; agricultural area including upland field and grassland, 5. Abashiri; large pig farm area.
Nitrate concentrations and flow rates of stream water were measured. In the forest area, the values of NO₃-N concentration were less than 0.3mg/l. In the agricultural area the values were higher than the values found in the forest area. They depend on the percentage of the agricultural land, consisting of upland field and grass land. The concentration of NO₃-N (y) increases with increase in percentage of the agricultural land (x). The estimated regression line was given by the equation y=0.029x. All values of y (mg/l) are included in the range (0.01-0.05) x. The values measured in Kanto districts were higher than that of this investigated area. It was caused by the larger supply of chemical fertilizer and high density of pig farms without an adequate treatment system for fecal matters.

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Water intake operations by farm household in the paddy field lots in Hokkaido havebeen pigeonholed using results investigated in both open channels and pipeline. The climate in Hokkaido is cooler compared with the other districts of Japan. For that reason, in the early growing process in which water temperature exerts a great influence upon the growth of paddy rice, a water management has been instructed so that water temperature can rise effectively in their paddy field lots. It revealed from actual survey data as well that farm household has carried out their water intakes from the night time to the early morning. Furthermore, it revealed that the hourly concentration of water requirement in the pipeline system is higher than that in any investigated open channel system.
In the early growing process, farm household has carried out their water intake operations in the conditions given to each paddy field lot with the intention to raise their water temperature as high as possible. When water management was freely carried out in certain paddy field lots capable of performing comparatively easy water intake in each irrigation system, the other paddy field lots will fallinto shortage of water. From that reason, in order to make a flexible water distribution possible to all the irrigation systems, a water requirement design has been needed with the actual state of these paddy field lots, especially the hourly concentration of water requirement taking into consideration. Then, with their water intake time zones and hourly fluctuation of their water intake volume taking into consideration, a lot water management model for certain water requirement design and canal system design was presented.

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The synthetic storage function model expressed by considering catchment geomorphological features is useful for engineering convenience. So the following formulae which have the coefficients depending on the land conditions are applied to a reclaimed upland field in order to examine the applicability of the model.
P=0.6, K=βA^0.14, T_e=γA0.14γ_e^-0.4where A is the watershed area (km²), γ_e is the rainfall excess (mm/h), K and P are the parameter (mm-h), T_e is the time lag between rainfall excess and flood runoff discharge and both β and γ are the coefficients depending on the land conditions.
Firstly the characteristics of the parameter P is confirmed by examining the values obtained by applying a mathematical optimization technique.
Nextly the usefulness of the applicability of the synthetic storage function model to a reclaimed upland field is verified by examing a difference between the parameters obtained by using the above-mentioned formulae and the identified parameters, and through comparisons between observed and simulated hydrographs.

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