This paper discusses an application of the linear elastic finite element method for settlement analysis of the soft ground in Kasaoka-Bay reclaimed land. The ground had been improved with packed sand drains and preloading embankments.
The consolidation of the improved ground should be analyzed three-dimensionally. However, we have had many difficulties in conducting a three-dimensional analysis. Kobayashi has proposed an approximate plane strain analysis using modified permeability in an improved area.
The applicability of Kobayashi method is examined in this paper. The method is preliminarily applied to a plane strain analysis for the effective area of a packed sand drain.The calculation results are then compared with the solution of the Barron equation. Second, the plane strain analysis for the reclaimed land is carried out with Kobayashi method. The calculation results are also compared with observed settlements. The original soil constants for the analysis were determined from the oedometer tests.
Consolidation analyses sometimes fail to estimate settlements correctly. A method for modifying the soil constants with observed data is accordingly proposed. The method modifies Young's modulus with the ratio of the observed settlement to the calculated one.
The concluding remarks of this paper are as follows:
1) The preliminary results of the plane strain analysis with the Kobayashi method are fairy close to the Barron solution. However, the settlements are smaller at the latter part of consolidation.
2) The calculated settlements of the reclaimed land are 25% smaller than the observed ones after the completion of the preloading embankments.
3) The settlements predicted with modified Young's modulus agree with the observed ones satisfactorily. However, the predicted settlement of the point near the edge of the preloading embankment is different from the observed settlement when the adjacent embankment was rapidly constructed.

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Recently, concrete corrosion at sewage treatment facilities has caused trouble in various fields. Specially, the situation at the facility which treats industrial drains is serious and necessary to take some urgent countermeasure.
At Ibo River Regional Sewage Public Works, Hyogo Pref., which is planned to treat sewage from tanners, it has been necessary to protect unused underground drainage (I. D. 1, 650 mm) from corrosion which was drilled by the shield method and successively lined by concrete. For this purpose, suitable corrosion resistant lining materials were selected, FRP test-lining was carried out, and finally fullscale FRP lining was completed. This report also describes the cause of partial peeling of the FRP coating which occurred at the beginning of full-scale FRP lining as a countermeasure to overcome its trouble and further the cross sectional difference of concrete property of concrete drainage.

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Two soils were used for salts leaching measurements under ponded infiltration, these were sampled from ridge in a greenhouse. One is light clay (A-soil) and the other is fine sandy loam (B-Soil).
When infiltration was terminated, soil column was segmented and then, water content and electric conductivity (EC) by 1: 5 dilution water extraction method was measured. The measured EC denotes the absolute salts per unit weight of soil, and salts concentration in soil solution is defined as EC is divided by water content.
A-Soil contains 27% clay and aggregate well than B-Soil, then A-Soil was not leached as well as B-Soil. So, the mobile-immobile water model was used to simulate the movement of salts under ponded infiltration for A, B-Soil.
In the model, the diffusional mass transfer coefficient is defined as follows. The concentration of mobile water at the soil surface approaches to that of ponded water with time. So, it is possible to replace the concentration of mobile water with that of ponded water in the immobile water diffusion equation for a long period of time. Applying the relative concentration ratio data at large infiltration time to the solution of this diffusion equation, the value of mass transfer coefficient divided by immobile water is obtained. Then, the mass transfer coefficient is determined by assuming the volumetric immobile water content (θ_im).
Assuming some θ_im in calculations, and found the suitable value which corresponded with measured data. By this method, good agreement between measured data and calculated results were obatined.

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This research deals with the effect of pixel positioning accuracy on the accuracy of landcover classification of actual Landsat-5 TM image data by the following process.
First, IFOVs of image data over the analyzing region were projected on the ground truth map of landcover both by an usual registration method and by a new registration method which registers IFOVs more accurately than an usual method. Also, image data of the study area were classified to six categories by three kinds of supervised classification methods.
Second, the result of supervised landcover classification were compared for each pixel with the content of landcover within one IFOV of that pixel, which IFOV was projected on the ground truth map by two registration methods, and the accuracy of supervised landcover classification were calculated and compared.
Finally, the classification accuracy for pure pixels and mixed pixels were examined under usual registration accuracy by an usual method and under the higher registration accuracy by a new method.
After the procedures noted above, the results of this research are concluded as follows.
(1) The accuracy of landcover classification in remote sensing data was effected by the accuracy of the registration of IFOVs of pixels. The accuracy of supervised landcover classification for pixels of which IFOVs were registered by a new method was totally about 2% higher than that for pixels of which IFOVs were registered by an usual method in each classification method.
(2) One of the causes of misclassification of landcover in remote sensing data was concluded to be the existence of mixed pixels. The misclassification of landcovers occurred more frequently in mixed pixels than in pure pixels. And the accuracy of landcover classification of mixed pixels of which IFOVs were registered more precisely by a new method was higher than that of mixed pixels of which IFOVs were registered by an usual method.

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This study was carried out to decide the optimum type of porous pipe which was used for the sub-irrigation method by use of the negative pressure difference under exposed condition. Experiments were conducted using torus porous pipes, cylindrical porous pipes, and pod porous pipes and also by using Masa soil, Kuroboku soil, and Fudai field surface soil. In the experiments, the amount of water being suppled and the infiltration distance in the horizontal direction were measured for each type of pipe.
The results obtained are as follows.
1) Water supply and infiltration distance were clarified and seen as being dependent on the shape of the porous pipe.
2) Water supply and infiltration distance of the torus porous pipe was the largest of all porous pipes. Especially, torus porous pipe was judged to be suitable to sandy soil like Masa soil.
3) Pod porous pipe was judged to be the most unsuitable of all porous pipes because water supply was the least and yet the infiltration distance in the horizontal direction was the smallest.

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This study was carried out to decide the optimum type of porous pipe which was used for the sub-irrigation method by use of the negat ive pressure difference under the crop cultivation. The three kinds of porous pipes, that is, torus porous pipes, cylindrical porous pipes, and pod porous pipes were used for the experiments and 10 plants of Melon (Cucumis melo L. cultivar ‘Andes’) were planted to one experimental plot. Also, the soil used in the experiments is called Fudai field surface soil, and its texture is of the loam type.
The results obtained are as follows.
1) Water supply which was necessary to grow melons could be insured by use of cylindrical porous and torus porous pipes.
2) Water which was excluded from cylindrical porous or torus porous pipes was clarified enough to spread sufficiently to the roots of the melons.
3) The merit by using torus porous pipe was clarified to be able to insure much water supply and spread sufficient water to the roots, but it was found that complete elimination of the air bubbles entrapped in torus porous pipes was pretty difficult.

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Numerical unsteady flow analysis is one of the important factors for determining the dimensions and locations of drainage facilities for land reclamation areas. This paper describes the experimental results of hydraulic transients which flow through the sluice gate, so as to set up suitable boundary conditions for a hydraulic simulation model. The experimental results of hydraulic transients in the laboratory flume are as follows.
1. Water level drop down in speed, just after the gate was suddenly opened at the upstream, is not negligible with acceleration of gravity within 0.2 s and water surface shape became the upward curved line (convex) for the rapidly varied unsteady flow.
2. The vertical pressure distribution in the laboratory flume, just after sluice gate was suddenly opened, became hydrostatic pressure at the ponit of 2 times the distance of the initial depth from the gate site to upstream and this distance is coincident with the Pohle solution. Also hydrostatic pressure is preserved continuously during transient flow.
3. The horizontal velocity of rapidly varied unsteady flow is delayed in comparison with the theoretical velocity of shallow water wave, that is u=2√g (√h₀+η-√h₀) (u<0).
If the delay time is considered, the horizontal velocity can be expressed by the delay of the first degree that is u= (1-e^-t/T) ×2√g (√h₀+η-√h₀) T is time constant.
4. When the sluice gate is opened partially, the steady water level after hydraulic transients can be expressed by Eq.(21) and the H. R. Henry coefficient of discharge under the condition of free and submerged flow.
5. The falling speed of water level under the condition of submerged flow is slower than the speed given by Eq.(23). The speed under the condition of this experiment is 0.30-0.49 times of the gate opening speed.
6. Eq.(32) is applicable, as a boundary treatment, to the numerical model of unsteady flow analysis for rapidly varied unsteady flow.

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A simulation model of the fluctuation of the storage content in each reservoir belongingto the multi-reservoir system which consists of many reservoirs connected in parallel or series is presented in an attempt to regulate the imbalance occurring in reserovoirs.
The model is derived from a matrix differential equation, which contains the idea of the regulating discharge to regulate the imbalance. It is derived by transforming the coefficient matrix in matrix differential equation to the Jordan normal form.
The model is adopted to the multi-reservoirs system consisting seven reservoirs. Changing the coefficient of regulation discharge for each reservoir respectively, some sample calculations are carried out and as a result the states of the fluctuation of storage content of each reservoir are shown. Consideration is given to the state of fluctuation by changing the coefficient.

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The objective of this investigation is to consider the mechanism of pore clogging and clogging effects on the change in soil permeability with time.
Experimental results of soil permeability were classified into (i) increase in permeability with time (ii) decrease in permeability in the first stage (iii) constant in permeability. Authors investigated the mechanism of the decrease in permeability with time. Some clogging models of soil are divided into two types, one is the immediate clogging type of which clogging occurs by coarse particles in the pores, the other is the gradual clogging type by adhesion or sedimentation of fine particles to the inner walls. From the results of a microscopic observation of the soil sections and a comparison between calculated values of the clogging models and experimental ones, it was possible to suggest that pore clogging proceeded with the immediate clogging type due to soil suspension flow.
Little is known about the mechanism of immediate clogging due to soil suspension flow. The authors observed the decrease in the percolation volume of soil suspension through a porous medium against the increase in the volume concentration. Also, the changes in percolation volume per unit time were analyzed using the Buckingham-Reiner equation. The conclusion was that the rheological behavior of the soil suspension flow which caused one of immediate clogging was shown as follows.
R_j≤γ_0i (=2Lθ_i/ΔP_i)
where R_j is the pore radius, γ_0i the radius of plug flow, L the pore-length as the tube, θ_i the Bingham yield value, ΔP_i the difference of pressure. To prevent immediate clogging due to soil suspension flow, the radius of plug flow should be at least less than that of the pores.

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At present, various analysis techniques are adopted for the structural design of culverts as hydraulic structures. The coefficient values for calculating the section force for culvert cross sections were calculated by the FEM using beam elements, and in this report, those are tabulated.
In the circular cross section of culverts which is shown in the design standard of Agricultural Structure Improvement Bureau, Ministry of Agriculture, Forestry and Fishery, the calculated cross section is shown definitely, therefore, by using this cross section, the validity of the calculation technique was checked up. Thereafter, as for the other types of culvert cross section, the demand of which is paticularly large in the design field, the coefficient values were calculated and tabulated. Further, when the section force is calculated, the condition of calculation at the time of using the coefficient values was shown clearly, and description was made also on the matters to which attention should be paid at the time of the use.

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The relation between the process of oxidation of sulfur compounds and the water content (water moisture suction) in coastal muddy soil was examined.
The concentration of sulfuric ions increase as oxidation of sulfur compounds contained in pyrite, etc. occurs, and as a consequence, the soil pH decreases in the coastal muddy soil. Especially, the initial oxidation of sulfur compounds occur at pF values of 4.0-4.4 and the lowest soil pH was observed at pF 2.8 over an elapsed time period.
In spite of the difference in the soil pF values, the soil pH decreased from 7.6 to 3.0-4.0, after the soil was allowed to dry over a two year period.
The soil pH decrease occurred to a much greater extent in soil containing a lower salt concentration.
We considered that the treatment of salt removal enhanced the activity of soil microorganisms helping in bring about sulfur oxidation and the formation of sulfuric ions.
The pH decrease in the soil with autoclaved treatment was only slight at pF values lower than pF 3.0.
Accordingly, we concluded, that the decrease in pH in coastal muddy soil mainly occurred due to soil microorganisms which oxidize sulfur compounds under the condition of higher-water than pF 3.0.

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In a desalting reservoir with a desalting conduit, water temperature, chlorine content and wind velocity over the water surface were measured from 1970 to 1974.
The gate attached to the conduit was operated during irrigation seasons, so the chlorine content of the surface layer was less than 1‰.
The gate was not operated during non-irrigation seasons, so the interface rose and chlorine content of the surface layer increased from 2 to 4‰.
Chlorine content of the bottom layer was 4 to 8‰ throughout the year. During typhoons and strong winter winds (Kisetsufu), salt was transported from the bottom to the surface layer due to the wind-induced flow, the interface moved lower and the chlorine content of the surface layer increased.
The validity of the vertical continuous layer model for analyzing chlorine transport was made using the observed data, and the conditions which prevent the transport of chlorine were determined.
Chlorine was not transported from the bottom to the surface layer when the Richardson number was greater than 5, 000.
From the results of numerical experiments for 48 cases and observed data, the chlorine content of the surface layer was expressed with an exponential function using three non-dimensional parameters.

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The aerator applying falling water is effective for oxidation ditches. However, in this aerator, the activated sludge in the bioreactor flows through a water pump, and its diameter becomes smaller. It is feared that the subdivision of the flocs reduces the ability of solid-liquid separation.
In this paper, to investigate the ability of solid-liquid separation, the characteristics and velocity of sedimentation of activated sludge of this oxidation ditch were examined regarding biological flocsize, biota of activated sludge and existence of biopolymer in flocs. Also, the sludge of the other plants using a rotor aerator was compared.
As a result, it was found that in this oxidation ditch, the size of flocs was smaller than that of the other plants. There were also some differences in biota, and the number of, microorganisms of this sludge was about a half that of the other ones. Less biopolymer was found in the flocs of this sludge.
However, the velocity of sludge sedimentation was almost the same. The ability of solid-liquid separation is effective on this oxidation ditch. In the experimental plant applying falling water as the aerator, there was no problems concerning solid-liquid separation.

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It is espected that the ‘alloted rental vegetable garden’ will spread and will raise various types with establishment of alotted Vegetable Garden Law for a background. But to promote such a tendency, we have many technical problems to be solved on planning. One of major problems is to give upper limit of lot size. For, the purpose of this garden is to fill self-consumption of vegetables, so the upper limit of the lot size must be given as to coinside such a condition.
In this paper, estimation on upper limit of lot size were tried by a case study on Saitama Prefecture, on the result of planting acreage investigation of vegetable garden for self-consumption in Hino-town Shiga-prefecture. And following sugestions ware made, it shood be given about 50 m²/man and 150 m²/family as maximum size of planting area of alloted rental vegetable garden lot.

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The Senoogawa drainage pump station was constructed on soft ground consisting of Kojima-Bay clay. In the construction of Senoogawa drainage pump station, which was built on a large site, the soft ground was fortified with a cement hardening agent so as to use the open cut method. In advance of carrying out the excavation, two inclinometers were set up on the rear-side of the excavation area, and ground behavior due to the excavation was closely observed.
In this paper, first the engineering properties of Kojima-Bay clay, which were fortified with a cement hardening agent, were ascertained using laboratory test data. Second, the behavior of the newly fortified ground and soft ground around the fortified one due to the excavation were investigated on the basis of results of a field observation using two inclinometers. Lastly, the results of the numerical analysis using the finite element method (FEM) for the behavior of ground due to the excavation were compared with the results of the field observation.

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This report contains the explanation of results of the triaxial compression test on the-Kuroboku-Shirasu mixed soil classified from organic soil to inorganic one. For using the Kuroboku Soil as a mixing material, the change of strength parameters accompanied with the mechanical variation of the organic matter content is discussed.
The mixed soil has the cohesion and angle of internal friction similar to the organic soil when the organic matter content is above 13 percent. On the other hand, in case that the content is below 5 percent, the mixed soil comes to have strength parameters similar to the Shirasu (volcanic sandy soil). The intermediate property is shown in the range of the content from 5 to 13percent.

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In the case of constructing buried pipes and channels in weak clay zones, the sliding failure due to the weakness of the ground, the sinking due to stress increment and so on are frequently observed. As the cause of the sliding failure of channels, it is regarded as (1) the cracking of ground surface in paddy fields and others and the water pressure acting to it, and R the channel bottom existing on an extremely weakened stratum. And as the cause of the sinking of buried pipes, it was able to be clarified (1) that the foundation of pipes and diversion works is located in ultra-weak clay area with large compressibility, (2) that there is the compacting sinking due to the additional weight of the replaced soil for preventing the rising of the pipes, and (3) that the sinking of the pipes and ground surface occurs when the cavities that arise underground by pulling sheet piles out close.
In order to prevent the lowering of functions of channels and buried pipes, by using the improved cement system materials made by various campanies, the tests were carried out in the laboratory and in a field, and the difference in the improved characteristics was investigated.
The conclusion (1) that as the result of the laboratory test, there was the difference as much as more than ten times in the strength of improved soil according to respective materials on the market, (2) that about 60% of the strength obtained in the laboratory becomes the strength of the improved ground in the field, (3) that unless the proportion of mixing was more than the 6-7%the homogeneity of the improved ground was not obtained, (4) that as for the ground requiring improvement, it is desirable to apply this process to uniaxial compressive strength distribution q_u=8+2·Z (kN/m²) or less and so on were obtained.
Further, by constructing buried pipes and channels in fields, the verification of improved ground zones together with the workability and the economical efficiency was carried out.

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During the progress in the study on evapotranspiration (ET), pan evaporation (Epan) has played an important role as reference evaporation to derive various formulae for estimating ET and to study the ET mechanism. While more physical methods that fit the computerized work have recently been developed, the pan evaporation method is more practical, cost the least, more convenient, and reflects the meteorological environment more clearly than the other methods.
In this series of papers, the purposes of the studies on ET with pan evaporation are grouped into the following four: to scrutinize (1) ET formula, (2) reference evaporation for estimating ET, (3) characteristics of pan, and (4) advection effect. In the present paper, in relation to the standardization of the observation of Epan and the progress of the concept of potential evaporation, studies on purposes (1) and (2), and the results and problems brought by Epan are summarized. Then, the role of Epan as reference evaporation, that has been completed is summarized. Finally, reconsidering the significance of Epan, we review its role in the future.

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In the previous paper, studies based mainly on the measurement of pan evaporation (Epan) aiming at scrutinizing (1) evapotranspiration (ET) formula and (2) reference evaporation for estimating ET were outlined. In the present paper, we summarize the studies on (3) the characteristics of pan evaporimeter as they are the characteristics of radiation and heat balance of pan caused by local advection from the surroundings and its structure. Then, the studies on (4) the advection effect are outlined and it is emphasized that the characteristics can be utilized as they reflect the local meteorological conditions of the spot where the pan is placed. Namely, Epan has a role as local potential evaporation. Further, the concept of complementary relationship is shown to integrate the role of Epan as reference evaporation and local potential evaporation. Finally, it is emphasized that in future studies on evapotranspiration, Epan can play an important role in scrutinizing meteorological environment in a small area.

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