Secondary properties of residual soils are influenced by their fundamental properties and that to a great extent especially by specific surfaces of the latter. In this study, the relationship between specific surfaces and secondary properties (consistency, water retentivity and compaction property) of residual granitic, dioritic, rhyoritic and andesitic soils was examined.
The results are summarized as follows:
1) Consistency:
Liquid limit, plastic limit and plasticity index are closely related to the specific surface.
2) Water retentivity:
Moisture content equivalent to pF 1.8, 3.0 and 4.2 each is closely related to the specific surface.
3) Compaction property:
Optimum moisture content, maximum dry density and steepness are closely related to the specific surface.
It is thought that the difference in compacted soil structure may also be reflected in the relationship between pF value and molding moisture content.

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Efficient sprinkler spraying, arrangement and a rational, economical piping method with a lateral line for agrichemichal spraying of citrus groves were examined. It was clarified that when spraying, the crown of a tree must be done at least by two sprinklers from opposite directions to allow for the agrichemical solution to adhere. Even adhesion of an agrichemical solution can be.obtained by decreasing the spacing distance between the sprinklers, but this is costly. From the viewpoint of intensity of sprinkling and installation cost, square spacing is preferred.
The spraying distance is controlled by the angle of elevation during sprinkling. When the riser is inclined toward the bottom of an inclined field, a formula to figure out the angle (β¹) of sprinkling toward the contour line is as follows:
sinβ¹=sinγ/cosα(°)
γ: angle of the sprinkler nozzle itselt (°)
α: inclining angle of riser (°)
The sprinkling distance at a different slope and angle of sprinkling was obtained from a sprinkling test of M I and M III type sprinklers. Then, the proper spacing and inclination angle of the riser at a different inclined grove were suggested. Lateral lines at an inclined grove must be arranged downward in a comblike shape, because of the loss of the remaining solution in the riser, and the installation cost.
A lateral line at ground level must be arranged in arborescence pipeline system, because it is the most rational and economical method.

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Vegetative growth, yield and fruit qualities under various water saving irrigation systems were examined using a 4 year field test by a drought treatment during July and August at the peak use of water for citrus groves. The drought treatment period was equivalent to a 10 year droght period.
As a result, it was confirmed that the water saving irrigation which uses 70% water of TRAM was economical. The use of water varied according to the irrigation method employed.
The use of water by this method was 87% of ordinary method. On the other hand, water use without irrigation was 43%. These phenomena were considered in which the capillary water of soil rises from the lower layer under the condition of a drought.
Under this irrigation method, the water requirement could be decreased by 30%. By which not only the investment regarding the irrigation facilities could be decreased by increasing the effective rainfall rate, and also it was be possible irrigate more 30% of the acreage with the same reservoir water.
Water stress can be measured clearly and easily from the leaf water potential (ψ) which is measured by pressure chamber method. The leaf water potential of the-6--7 bars (ψ_max) is the index of irrigation starting in case of the water saving irrigation.

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Many models have been developed which are used to estimate pollutant load running off from a watershed at a certain point on a river. This paper discusses one of these runoff models of pollutant load, applying the series tank model which has been used to use for the runoff analysis. The runoff models of pollutant load during a rainfall has been already presented by the authors. A new reformed model which is presented here is the one that can simulate a daily runoff of a pollutant load. The improvements are to build in the model accumulation of pollutant load during the fine weather, and to change the series tank from parallel to series. As a result of the examination of simulations that the authors made applying the reformed model to SS, turbidity, and EC in three different watersheds, the measured values and the calculated values coincided well.

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The quantity of heat supply through the sea surface into a bay can be estimated generally on the basis of the bulk method. However, for this purpose, many observed data become necessary, such as insolation, air temperature, the saturation vapor pressure on sea surface, the water vapor pressure in the atmosphere, wind velocity, the atmospheric pressure and water temperature. But it is by no means easy to obtain the reliable observed data on all these items.
In this report, the simplified calculation method is discussed, which can estimate the quantity of heat supply through the sea surface and the mouth of a bay with the observed data on air temperature and the water temperature inside and outside the bay, which can be obtained relatively easily.
As the result of applying it to Uranouchi Bay, it was found
(1) that this method can estimate the heat balance in a bay with nearly the same accuracy as that of conventional method, and
(2) that in the case of Uranouchi Bay, the heat in flow and outflow through the sea surface were twice as much as those through the mouth of the bay, and play the large role in the stratification and convection in the bay.

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Erosional process of cohesive bottom sediments by flow has been studied using visualization experiments and quantitative measurements of flow velocity and concentration of suspended sediments. Samples of bottom sediments were made by allowing kaolinite suspensions to settle for 3 h.
Erosions of bottom sediments by flow were reproduced in the annular flume, visualized and photographically recorded by a still camera with highly sensitive film (ISO 3200) and a 105 mm micro lens. A constant temperature anemometer was used to measure the profiles of the streamwise, the transveres and the vertical flow velocities. Concentrations of suspended sediments originating in the erosions of bottom sediments were measured by a device built as a trial using an infrared emitting diode (IRED) and a photo-transistor (PT). Using the SS meter, a non-contact measurement and high frequency sampling (i. e., 1 kHz) were carried out.
The results indicated that the critical shear stress of the bottom sediments was 0.3 N/m2, and that the vortices near the bottom were closely related to erosions of bottom sediments and the scale was from 0.16-0.60cm.

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The numerical method is presented herein to study wave refraction and diffraction which appear as a consequence of the wave-current interactions on a slowly varying topography. The model equations are derived from Kirby's (1984) mild slope wave equation. Each iterative computation of the equations is the basis of the finite difference method according to the fixed grid scheme. Numerical results are shown for Liu's (1983) ‘rip-current model’ where the interaction between normal incident waves and jet-like currents occur on a sloping beach.

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The retrospective reasoning for getting the time series of effective rainfall from a direct runoff discharge using the kinematic wave model was discussed as an inverse problem. The procedure for getting effective rainfall was proposed, and the one-to-one correspondence of the series of discharge to the series of effective rainfall as an answer was discussed. This reasoning was examined using the data given in a small field as a basin.
The main procedure for getting these answers is calculating the water depth from the lower end of the slope to the upper end along the characteristic curve. At the lower end of the slope, the water depth is given from a measured direct runoff discharge using an equation involving the roughness coefficient. From boundary condition, the effective rainfall was attempted on the condition that the distance of water depth zero to converge to the upper end of the slope.
It was clarified that no more than one series of rainfall do not exist, because the distance of water depth zero on the characteristic curve is getting large as the numerical order of rainfall at the lower end of the slope on the same characteristic curve.
In the example, not only the plus rainfall but also the minus rainfall were given. The minus rainfall is presumed to be the main reason for no convergence of the distance at the water depth zero. In the case of no convergence, the distance of water depth zero was confirmed changing minus to plus uncontinously for a continuous change in rainfall.
The time series of rainfall including the cases that the boundary condition had not been satisfied exactly was given for some roughness coefficient. These kinds of calculation seem to be effective for the runoff analysis of the field for a small amount of data.

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This study aims at clarifying the realites of entry pores of volcanic ash subsoil and availability of pressure caused entry pores (p_k) that distinguish percolation types consisting of the air separated percolation and the air penetrating one. The author considered that the realites of entry pores consisted of a pore completed air penetration (P₀) over the sample length and its surrounding coarse pores. Stereo-radiography was used because it was simple and suitable for this study. As a result of this study, the following information was obtained.
1) P₀ in the radiographs had a tubular pore shape whose sections were circular with pore diameters being 0.3 to 3 mm. Average diameters of P₀ were 0.7 to 3 mm and these were 1.2-1.7 times longer than the sample length.
2) Coarse pores with entry pores imaged by X-ray radiography had all similar shape to P₀ and the roots of grasses. There appeared many uniform coarse pores in these radiographs. The amount of coarse pores in radiographs nearly equaled that of entry pores. Therefore, p_k's availability of distinguishing percolation types was presumed to be high. Consequently, oxygen diffusion through a tubular pore net that built up the soil matrix was presumed effective in building up the situation oxidated environment.
3) P₀ had a larger neck diameter over the sample length than the other pores. Appearance of the pore necks was likely to result from properties of grass roots and connection of different diameter roots. After air penetrated P⁰, the liquid remained in the rugged part of the inner surface of the pores.
4) Hydraulic conductivity of P₀ was less than 30% of hydraulic conductivity of loam. Agreement rate of diameter between measurement value of radiograph and Juran's equivalent was about 90% when p_k divided by 1.2-1.7 was substituted for pressure of the equivalent.

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Concrete sewer pipes are microbiologically corroded by a two step reaction, i. e., the production of hydrogen sulfide (H₂S) and sulfuric acid (H₂SO₄) caused by sulfate reducing bacteria and sulfide oxidizing bacteria, respectively. These sewer pipes were made with expansive cement, which was more rapidly corroded by sulfuric acid as well assulfate than ordinary Portland cement. Comparing the corrosion rates of the specimens cut from sewer pipes and made with ordinary Portland cement in a sulfuric acid solution between these in-situ corrosion rates showed that the average pH condition was about 1 in the field. A detailed examination showed that corroded materials consisted of not only gypsum but also ettringite beyond a certain pH level. The results are as follows.
i) Expansive cement should not be used for concrete sewer pipes.
ii) Average pH condition is about 1 in the microbiological corrosion field. This value can be used in laboratory corrosion experiments.
iii) Microbial acid attack proceeds step by step from the concrete surface with the generation of gypsum and ettringite alternatively.

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