In the unsteady, unsaturated flow through layered soils in the state of air in soil contacting with the atmosphere, i. e. the open system, the hysteresis is present between the suction characterizing its flow and the hydraulic conductivity.
The present study was executed to clarify the effects of this hysteresis in the flow through layered soil in open system.
The calculation of values was performed for the case (1) of percolation with the head of ponded water given in the dry soil and the case (2) of percolation from the saturated state maintaining the head of ponded water.
From the result of calculation of values, it was clarified that at the stage of steadiness with flow the pressure value of constant negative pressure zone in the lower layer is larger in the case of wetting process than in that of drying process. And, this result was ascertained also in the experiment for the drying process and the wetting process after the gravity drainage.

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1) It is found that one of the causes of the soil sickness unknown until now is soil borne diseases.
2) The ways of avoiding these diseases consists in flooding treatment, chemical sterilization, and steam sterilization.
3) As a result of technical analysis, the following conditions must be considered: 1) efficiency of the treatment, 2) term of the trearment, 3) costs of the treatment.
4) On the other hand, the commercial conditions are analyzed, then it is found that the cropping system and the shipping system must be taken into consideration in choosing these ways.

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The viscosity and the rigidity of stirred Ca-and Na-montmorillonite paste were measured using a forced oscillation rheometer. The results are summarized as follows:
(1) When the agitation ceased, the viscosity of Ca-and Na-montmonillonite decreased with time. The rigidity of Ca-montmovillonite also decreased. The rigidity of Na-montmorillonite decreased at low concentrations but increased at slightly high concentrations.
(2) The viscosity and rigidity of Ca-montmorillonite changed more quickly with decreasing oscillation frequency, whereas the same Na-montmorillonite properties didn't change more quickly and decreased.
(3) When the oscillation amplitude increased, the rigidity of Ca-montmorillonite increased while the viscosity and rigidity of Ca-montmorillonite decreased.
(4) The effect of concentration on the visco-elastic properties of Na-montmorillonite is greater than in the case of Ca-montmorillonite.
In the present paper, the effect of the non-agitated state, oscillation period, and amplitude on the visco-elastic properties of the clay-water system are considered in the light of the following twofactors:
(1) Dissipation (Disappearance) of the electric double-layer on the surface of the clay particles (by the external energy) and development of thc electric double-layer when the sample is at rest.
(2) Flocculation of the clay particles.

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The water level in the river is banked up at the upstream by completion of the headworks and consequently the neighboring underground water level rises. In such a case, to prevent the rise of underground water, some works such as sheet piling or grouting along the river and the drainage work within the area should be considered.
In this report, we tried to estimate the rough drainage discharge to hold the present underground water level (before the headworks are completed) in the relatively wide area.
In calculation, we used the fundamental equation of underground water (1), substituting the velocity of the drainage discharge into ε₂ (velocity of the water which goes out of the underground).
As an example, we chose the Ohuchi-area (the right side area of the Yoshii river) and obtained the following results:
To hold the present underground water level,
(1) It is required to drain 350 mm/day within the Ohuchi area without any water stopping works along the river.
(2) When the present permeability 1.0×10^-3m/s is assumed to become small to 7.0×10^-4m/s by sheet piling or grouting along the river, it is required to drain 250mm/day within the Ohuchi area.
(3) When the present permeability 1.0×10^-3m/s is assumed to become small to 5.0×10^-4m/s, it is required to drain 220 mm/day within the Ohuchi area.
(4) When the present permeability 1.0×10^-3m/s is assumed to become small to 3.0×10^-4 m/s, it is required to drain 130 mm/day within the Ohuchi area.

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The Yamada River flows into the Dondo Dam Reservoir which is under construction in the Toban Agricultural Water Utilization Project. The catchment area of the reservoir is 49.8km². The water will be used for agricultural and domestic uses.
The population in the area has been increasing recently, and reacheed 34, 000 in 1975 increasing from 6, 000 in 1960. This tendency will continue in the future.
We measured and analyzed the discharge and water quality (BOD, COD, nitrogen, phosphorus) at several points along the Yamada River and also at the tributary confluences. In this paper, we dealt with the 'COD and nitrogen which are important in the Agricultural Water Quality Standards.
From the analysis, we get the general view of the water pollution of the basin as follows:
1) The Water pollution of the Yamada River is mainly caused by the inflow of household wastewater.
2) The daily pollutional load production in the basin is estimated to be 450 kg/day for COD and 270 kg/day for total-N.
3) The sum of the load measured at the tributary confluence was 3.27 g/sec (283 kg/day) for COD and 2.04 g/sec (176 kg/day) for total-N.
4) The greater part of the load production is concentrated in three blocks. The load production in these blocks is estimated to correspond to 71% of the total load of COD and 83% of total-N. The load measured at the tributary confluences for the above-mentioned blocks corresponded to 82% of the total load of COD and 90% of total-N.
5) There was a relationship between the COD load and the total-N load at the tributary confluences.

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What criterion should be adopted for simplifying the complicated drainage channelnetwork was discussed fundamentally in previous papers, in order to apply the mathematical model of unsteady flow to simulate hydrographs of flood runoff in a low-lying drainage basin. As a result, it was disclosed that the channel network system could be reduced to a second-order channel system.
This paper deals with an actual example of flood runoff in the Ogura research basin composed of hills, urban districts and mainly paddy fields. Flood runoff from non-inundated watersheds such as hills and urban districts is estimated by applying the kinematic runoff model, and flood flow in low-lying basin is simulated by solving the equation of unsteady flow numerically after simplification of channel networks.
The results of runoff analysis show good conincidence with observed hydrographs and verify the usefulness of the criterion for simplifying the complicated channel networks.

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In the analysis of water hammer in a composite closed conduit, it is transformed into an equivalent simple conduit with the following mean elastic wave velocity a_m0:
a_m0=∑L_i/∑(L_i/a_i)
where L_i and a_i are the length and the wave velocity of the i-th conduit respectively. In the simple conduit system, which is connected to a large reservoir at one end and to a closed valve at the other, the relation between the period of pressure oscillation T₀ and the wave velocity a_m0 is given by
T₀=4·∑L_i/a_m0
However, it is clarified by a simulation that this relation does not exist in composite conduits.
If the conception-the water hammer is a phase of energy exchanging process between kinematic and elastic energy-is introduced, then the following equations of mean velocity a_m and the period T are deduced:
_??_
where V_i is the volume of the i-th conduit, and f_e and (f·f') ₀ are the coefficients expressing areal changing effect and wave velocity changing effect respectively. From this theory it is shown that the conventional theory is deficient and the inconsistency of it is removed.
Furthermore, the equations by which f_e and (f·f') ₀ are approximately estimated on a two-conduit system are deduced, and appropriateness and adaptability of this theory are examined using simulation. At the same time, the structural characteristics in factors bringing about water hammer are also discussed.

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The author intended to solve the differential equation of flood control of reservoir, by assuming that the curve of a natural reservoir surface area is represented by a parabola with respect to the head on weir. However, the assumption of such a curve is justified when the head change is not large until the head on weir becomes not zero. Also, he computed as an example the inflow and outflow discharges by means of the solution mentioned above.

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It is desirable that mariculture water has no thermal or density stratification for conservation of the water quality. To improve the water quality, destratification methods such as air gun and air lift are being predominantly applied in some lakes and reservoirs. A. B. C. is also one of the destratification methods with mechanical energy.
As to improvement of the DO, for example, the hydraulic phenomenon by destratification should be clarified because the atmospheric oxygen gas dissolves into water and is transferred by water flow.
This paper shows the hydraulic consideration of the destratification by A. B. C., the design standards for its application and the conversion efficiency of supplied mechanical energy.

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The validity of the new theory was proved in the foregoing report through a series of movable bed experiments. Howewer, this is nothing but the absolute proof independent on the other formulas. In the process of development of the theory so far, the author has attempted to compare with the other formultas as far as possible. It is thought to be necessary to prove relatively for the further clarification of its validity by means of comparisons through experiments.
In the present paper, the other formulas are compared relativety with the author's theory through applying them to the experiments and the applicability and the characteristics of each formula is clarified. As representative formulas, Brown's formula, Tsubaki's formula and formula of Sato et al were selected. Formulas for the movable bed were deduced from these formulas and analyses were carried out using the data which had been used to prove the author's theory in the foregoing report. The results were compared and the relative value of the author's theory was examined. As results, the followings were obtained. The values calculated by the author's formula is the most approximate to the observed values with a few exceptions. On the whole Tsubaki's formula and formula of Sato et al show somewhat higher values, while Brown's formula shows slightly lower values. The analysis of variance as in the foregoing report shows that the effect of grain size remains in the Tsubaki's formula and formula of Sato et al. There are also a slight effect of distance in Tsubaki's formula and that of time in formula of Sato et al. However, in Brown's formula, the effects are negligible with respect t. the factors set up for the experiment as controllable ones. Also in the author's formula there is-not any significance with these factors. Thus, the author's theory is proved to be universally valid, at least within the range of these experiments.

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Considering that the soil is a plastic-rigid material, the penetration of a cone or circular footing into the ground considered two-dimensionally as a wedge or footing is analysed under conditions of plane strain based on the theory of plasticity. An experiment was carried out in which the wedge and footing penetrated a clay sample contained in an acrylic box. Slip lines around the wedge or under the footing were photographed. The value of the bearing capacity factor for the wedge or footing N_cα were calculated and compared with the experimental values of the bearing capacity of the wedge or footing q/the undrained shear strength of the clay c_u. The results are summarized as follows:
(1) The analyses based on the theory of plasticity:
i) The weight of soil γ does not practically affect the shape of slip lines when γ/c_u≤0.1
ii) The smaller the value of the angle of internal friction φ, the larger the calculated value of β which is the inclination of the ground surface heaped around the wedge. The value of β is larger when the surface of the wedge is smooth than when it is rough.
iii) The bearing capacity factor for smooth wedges increases with increasing semi angle of the wedge α(α=0-90°), On the other hand, the value of N_cα for rough wedges decreases with decreasing α, reaches a minimum value at a certain α value and increases again with decreasing α. The larger the value of φ, the smaller the value of α at which the bearing capacity factor for th rough wedge is at a minimum.
iv) Generally, the value of N_cα is smaller when calculated considering the effect of β.
(2) The penetration experiment and photographic observation of the slip lines:
i) The analysis made by assuming the existence of slip lines is applicable to the case of clay. ii) The slip line field in Hill's solution occurs under the smooth footing and that in Prandtl's solution occurs under rough footing.
iii) The direction with which the soil mass moves around the wedge largely coincides with the direction predicted from the hodograph.
iv) The smaller cones such as those in common use should be considered to have rough surfaces compared with the wedge used in the present experiment.

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In this study, consideration has been given to the strength constants of soils using two parameters, specific surface and thickness of the water film. The advantages of these parameters in considering the mechanical properties of soils has been reported, previously. The experiments in this study consisted of triaxial compression tests and vibration tests (resonant method). Five kinds of sample soils were used Deitan soil, Nozyo soil, Marine clay, Ryo soil and Simadai soil.
The study led to the following results:
1. The coefficient of internal friction (tan φ) decreases with increasing thickness of the water film.
2. In general, d (tan φ)/d (thickness of water film) increases with increasing specific surface.
3. The coefficient of internal friction is not influenced by the void ratio.
4. Cohesion is greatest for water film thicknesses of 30Å to 40Å.
5. The complex modulus decreases with increasing void ratio.
6. The dynamic elastic modulus is greatest for water film thicknesses of 30Å to 50Å.

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