The authors examined the relation between the observation scales of land and the variation in the distribution of physical properties of soils sampled from Hachinohe-Heigen region.
The results obtained are summarized as follows:
(1) The population mean x of the primary variation (L₀ population) is equal to the population mean g (L_i) of the L₁ population, L₂ population.
(2) The population variance V (L_i) varies with the different observation scales L.
(3) With increase of sampled area F, the converging ratio into zero of the variation between classes B (F) of the dry density (γ_d) was faster than those of the moisture content (ω) and other physical properties of soils.
(4) In case of hundreds ha scale research, the population mean of sampled area becomes identical with that of total sampled area when the rate of sampled area to total sampled area reaches 30-40% or more for dry density (γ_d), and 70-80% or more for moisture content (ω), respectively.
(5) Conventional sampler (φ 50 mm in diameter and 100 ml in volume) is not so inconvenient to carry out the investigation for dry density (γ_d) and moisture content (ω).
(6) Among sampling density (ρ_s), mesh sampling interval (δ) and sampled area (F), approximate formulas are established as follows:
δ=K₁·F^1/2
ρ_s=K₂·F^-1(K₁, K₂: constants)

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In this paper, the experimental results of the infiltration phenomenon are reported. The experiments are made by using a cylindrical columnof sand, loam and clay loam, and the influences of initial moisture content, soil density and sealed air on this phenomenon are discussed.
The experimental results are expressed by the temporal change of the cumulative infiltration and characterized by the coefficients C and n of the Kostiakov's type equation (D=Ctⁿ). And the effects of the soil texture, initial moisture content, air in the soil and soil density on these C and n are considered. Consequently, it is made clear that the cumulative infiltration may not necessarily be expressed by the kostiakov's type equation with a pair of C and n; but, under most conditions, it is expressed by characteristic equations with two pairs of C and n. The region which is expressed by the equation with one pair of C and n is named the first infiltration, and the region which is expressed by the equation with another pair of C and n is named the second infiltration. That is, the cumulative infiltration is expressed more appropriately by the first and second infiltrations. Furthermore, noticing the transition point in two intake curves of the first and second infiltrations, the author considers the relations between this point and the soil texture etc., and consequently, it is predicted from the view-point of structure of soil pore, that the fine-textured soil, the well moistened soil or, the densely packed soil will lead to the same effect on the cumulative infiltration.

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In an earlier paper, experimental results of the infiltration phenomena were reported. In this paper, using the data of the earlier paper, the infiltration phenomena are discussed physically. The results obtained are as follows:
1. When the gradient of intake curve (log D-log t) is between 0.5 and 1.0, the Green and Ampt's type infiltration equation (eq.(2)) is applicable (Fig. 1). Under the conditions that the first infiltration develops much, this epuation does not hold. This is because the assumption that H_f is constant is not satisfied.
2. The Philip's two-parameter equation is valid under all conditions except for the case of initial soil moisture being G. W. D.
3. The characteristics of the infiltration phenomena shown in the earlier paper are explained successfully by using the moisture profile model of Fig. 6. Namely, 1) The region of the first infiltration is the dominant region of soil suction, and the region of the second infiltration is the dominant region of gravity. 2) In fine-textured soils, particularly, the gradient of intake curve is less than 0.5. This is due to the fact that D_i (or K (θt) and H_f) changes with time. 3) As the soil is finer-textured, or as the initial soil moisture state is wetter, or as the soil is packed densely, the first infiltration develops much, because the ratio S/K (θt) becomes greater. 4) The mechanism of infiltration in the closed system is complex and does not show systematic characteristics, from which it is considered that the entrapped air and its behavior affect the infiltration phenomena much.
4. The coefficient n of the Kostiakov's type equation (D=tⁿ) can be expressed by equation (6) in the region of the second infiltration. In the region of the first infiltration, it is 0.5, however, the value can become less than 0.5 because of the variation of D_i with time.
5. Under the conditions in which the first infiltration develops much, the coefficient C of the Kostiakov's type equation is expressed by the following equation and is significant physically to some degree:
C=S
in which S is sorptivity of the Philip's equation.

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Experiments were made on the dispersion and flocculation behavior of some clayey soil suspensions in relation to the counter cations (Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺) and the properties of electric charge on these soil particles.
The results obtained are as follows:
1. Generally, non-volcanic ash soils were dispersed perfectly by all electrolytes used including Na, K, Mg and Ca cations, but volcanic ash soils did only for special cations (Fig. 1).
2. The concentration of electrolytes which gave perfect dispersion are 10^-1 meq/1 for NaCl and 10^-2 meq/1 for CaCl₂ (Table 3).
3. From the experiments of ion adsorption of soil particles by the Schofield's method, it was estimated that the peculiarity of volcanic ash soils on the dispersion and flocculation behavior is attributed to the existence of electrostatic attractive force derived from the diffused double layers with charges of different signs (Fig. 2, Table 4).

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Whether or not the introduction of reeds formation of drying the sludgy ground of Hachirogata was examined from the measuring results of the cone index, moisture in earth, level of underground water etc. in the bare area and nonintervention area during the period from 1967 to 1970.
As a result, it was clarified that in the period when the dry weather continues for a long time and the growth of reed is enormous, there are various merits such as evaporation down to deep layers and formation of the development of land structure.
On the other hand, it was confirmed that, in a district such as Akita Prefecture there occurs inferior water discharge because the growth of reeds becomes a factor of impeding the flow of earth surface under the meteorological condition of much rainfall particularly in the wet season in September and afterward.
Under the condition of much rainfall, the water discharge of earth surface was rather favorable in the bare area showing better drying state. However, it was revealed that provision of small ditches for discharging the water of farm land is more effective for this purpose than the promotion of water dircharge of earth surface by actually exec uting the treatment of bare ground.

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The process that the primary droplets sprayed from a sprinkler are spread on the surface of leaves after striking against it and the secondary droplets are produced, has been grasped as an energy distribution phenomenon. The relations between the energy and the kind of leaf, kind of liquid, and the moisture on the leaves were experimentally investigated. The results obtained are summarized as follows:
(1) Among the leaves tested, the leaves of tea, orange plants etc, present a large secondary scattering effect in elasticity or hardness of leaves. Pear is the poorest plant in the preventive effect of sprayed liquid from the above point of view.
(2) The weight of oscillating energy occupied in the distribution energy is small to be negligible.
(3) When the surface of leaves is dry, the initial velocity of spread and the acceleration of spread are both larger than those in the wet state. If the adsorbed dirt on the leaves is removed, the aforementioned quantities are further increased.
(4) Although the energy of spread is the largest among the distribution energies, it is lowered to a great extent if the leaves are wet. The energy of spread becomes hardly different by the presence and absence of oscillation of leaves.
(5) The adherent energy does not change by the moisture of leaves. There exists few influence of the energy of primary droplets. However, this value is remarkably affected by surface tension.
(6) The initial diffusion velocity of the secondary droplets is large in case the leavers are wet. And when the surface tension is lowered by the application of a spreading agent, the energy of the secondary droplets is somewhat increased.

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As a statistical prediction method of rainfall runoff, a nonlinear analysis adding an nthdegree moment term has recently been discussed. In this paper, an analytical method by rising a multiple regressive formula added with a term of 2nd-degree as a nonlinear analysis was investigated. Although the multiple regressive analysis is widely utilized, it is difficult to treat the analysis directly, because of high correlation between the nonlinear and linear terms. In this paper, a method is proposed in which, as an analytical method containing a term of 2nd-degree, a linear prediction is first performed and its residue is explained by a term of 2nd-degree. And by using the actually measured daily average flow discharge of river and the daily rainfall, a runoff analysis is made, thereby it was possible to predict the runoff more accurately than the linear analysis.

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Forecast models using historical time series data for intake-water temperature in a reservoir are made by means of a parametric time series model. An exposition of the method and an example of data illustrative of the procedures necessary for making a good forecast model are given.
The daily temperature of intake-water in the Ishibuchi reservoir in Iwate Pref., from January 1, 1965, to December 31, 1969, provide a material for the models. The method is easily extended to the forecast of river water temperature.
The steps of making the forecast models by using the historical time series data that combine both a periodic component and a stochastic component are summarized as follows:
1. When Fourier series is applied to the periodic component in daily average, the first two harmonics (annual and half yearly harmonics) are selected as significant for the temperature of intake-water. The first two harmonics account for 94.7% of the total variance of the original data.
2. When the Fourier coefficients are computed, substitution of the resulting values into Eq. 7 allows the determination of sequence of computed values of the periodic component. These computed values are then subtracted from the original data and a “residual” time series (stochastic component) will result. The analysis of the stochastic component is done by fitting a autoregressive model to the series. The efficiencies of analysis are 78% for the first autoregressive model, and 79% for the second autoregressive model.
3. Thus the succinct models consisting of a cyclic model for the periodic component coupled with an autoregressive model of the order 1 for the stochastic component are postulated for the intake-water temperature (Eq. 13-Eq. 16).
4. These forecast models are employed to simulate the daily water temperature. The simulated temperature trace remarkably resembles the historical data traced (Fig. 7-8).

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In this paper the authors analyze theoretically the wave motion that propagates through a porous medium of semi-infinite length on the assumption that the motion is a shallow surface wave. On the other hand, they tried a few experiments and analyzed the damping of the wave height in the porous medium and confirmed that the experimental values agree well with the theoretical ones. Furthermore, the distribution of water particle velocity and that of mass transport velocity in the porous medium were made clear. As a result, it was recognized that there exists a circulating flow in the porous medium.

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In general, the safety of soil construction is evaluated by the integration of mechanical factors, but their factors are considered to be dealt with as an uncertainty problem, because thay are not decided by a deterministic method.
In this paper, the safety of embankment on soft ground was examined as an uncertainty problem by using the Distinction function and Factor analysis method as an example of sensitivity analysis. Further, the factors picked up here were the compression strength q_u, depth of soft ground D, natural moisture content ratio W_n, specific gravity G_s wich regard to ground, and the height H, crest width B, slope n, compaction density γb, construction rate with regard to embankment, respectively.
The results obtained are summarized as follows;
(1) Most of the failures of embankments of multistaged construction are caused by small q_u on exploration.
(2) It is found from the results of the Distinction Function method that the safety of embankment is dependent on S and D which are not containted in a conventional “safety factor method”.
(3) It is clarified from the results of Factor analysis that the safety of embankment is influenced by the ratio D/H between the depth of soft ground and the height of embankment.

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