The effect of slope length on soil loss was investigated by field test in a new reclaimed fi eld of Pliocene sandy soil, which was rather erosive, similar to decomposed granite soil in Japan.
The test field was selected to have a gentle graded temporary levee at the lower side, and had various slope lengths from 0 to 80 m in the shape of a trapezoid. The slope gradient was 4 degrees. After smoothing the configurations, the process of soil erosion was observed periodically after rainfall over a 2-month-period. As a result, a shallow gully (rill) occurred on the whole slope. Along the temporary levee, eroded sand accumulated downstream to make the longitudinal gradient uniform gradually. The sedimentation along the temporary levee, which was 15 cm of the maximum depth and 2 m of the maximum width, became smaller in scale because of its secondary movement. It was considered that the gully (rill) development on the slope was not so notably influenced by the sedimentation that the effect of slope length on soil loss was able to be analyzed every each of gully (rill) network.
In test field, rill and interrill erosion was observed predominantly. Such is the form of erosion, soil loss per unit area has been considered to increase as the slope becomes longer. However, there were no obvious relations between soil loss per unit area and slope length. In this paper, the relation between soil loss per unit slope width and slope length was proposed from the viewpoint of planning a graded temporary levee along which much eroded sand accumulates.

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In a bay, density stratified layer develops from spring to summer. Following the development of density stratified layer, internal wave which was caused by tide is induced. The scale of induction is related to degrees of development of density stratified layer or the shapes of bay. In a long and slender bay like Uranouchi Bay which is composed of many branches, the influences of branch upon internal wave are supposed very remarkable.
In this study, an equation for calculating interfacial long wave which is induced by tide in branch, was derived, then investigated the influences of branch on interfacial wave, and following results were obtained.
(1) Neumann's impedance method is applicable to natural oscillation of interfacial long wave of branch.
(2) The influences of branch upon natural oscillation of interfacial wave are as follows. The longer the length of bay, the smaller the wave number of natural oscillation, and the influence upon natural oscillation is smaller when branch is located nearer to node of interfacial wave.
(4) The nearer the natural period approach to tidal period, the larger the scale of induced interfacial wave.
(4) Interfacial wave in not induced to branch which is located at the node of interfacial wave.

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There are many studies on borrowing and lending contracts of the large-scale farms, increasing their farm operations as a result of contract farming. However, there are few studies that have been concentrated on the their fields except their scattering.
In this study, two farmers, who are both selfcultivator and farm machine operators, were selected. One operates about a 20 ha paddy fields for rice and wheat in the suburbs of Gyoda, and 2/3 of his machine-operated plots has been consolidated in a 30 a standard plot. The other is one of the largest farm operators of rice land (about 15 ha) in Koshigaya, and paddy fields remain in the former old style of 10 a standard plots and is being influenced by urbanization.
As for the plots by the contract farming (actual contract of borrowing and lending of plots between farmers, without permission of the Agricultural Land Act. The trustee pays his client land rent). or by the contract for machine operation (undertaking opperations such as farm machine-operated and the cultivation of seedlings. The client pays the opperator wages and grows crops), it is feared that the contract will be canceled by the circumstances of its client. So, at first, the transition of the plots by the contract farming and by the contract for machine operation was investigated. As a result, the whole acreage of machine operating area of these two farmers shows a slight increasing tendency, the place of their operating plots are not permanent. The duration of farm operations is, as a whole, a little shorter in the suburbs.
It can be possible to operate many plots with machine efficiently, if the machine are able to work efficiently inside of each plot, and if the machine operation date is able to be selected freely without any influence due to the adjoining plots. So next, the situation of each plot from the view point of the farm machine operation is examined using the following five factors: 1) accessibility of farm roads, 2) plot size and shape, 3) accessibility of ditches and drains, 4) situation of on-farm irrigation, 5) situation of on-farm drainage. As a result, only 1/4 of machine-operated plots is suitable for largescale farm in Gyoda, and none in Koshigaya.

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At present, there are many greenhouses for cultivation of many kinds of vegetables. Generally, they are very lightweight and, therefore, it is easy to be destroyed by aerodynamic forces. However, studies on the windproof characteristics of greenhouse is less than that of the general architecture of buildings. So, this paper discusses the pressure fluctuations on the roof of several rigid model greenhouses using a wind tunnel, in which experiments are carried out in two cases of model shape. One is a gabled roof and the other is round shaped. Wind speeds used are 10-20m/s. Measurements of wind pressure are carried out at 10 points a model roof. Wind pressure coefficients and power spectral densities are calculated from time series data obtained.
Results obtained are as follows: Excellent oscillations appear on the roof of the upstream side of gabled and round-shaped model. These excellent oscillations are due to vortex production in the turbulent boundary layer near the roof. In the case of gabled model except for gently inclined roofs, excellent oscillations were not observed, but were observed in the case of a round-shaped model. So, a round-shaped greenhouse is more influenced regarding vibration by the wake than the case of gabled houses.

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In the previous paper, we discussed the pressure fluctuation on the roofs of several rigid model greenhouses to obtain fundamental knowledge on windproof characteristics. However, many of the greenhouses now being are frame structures vinyl fillmed and, therefore, wind induced oscillation of this type of structure is being influenced by the vibration of the film. So, in this paper, displacement and vibration of vinyl film of a model structure is measured by a gap sensor in a wind tunnel, and power density spectrum is calculated from the obtained time series data. The result obtained shows that the excellent oscillation of film appears and it is similar to that of the pressure fl uctuation on the roof of a rigid model.

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A study on the relations between consolidation of undisturbed soil sample under very wet conditions and soil structural changes evaluated by shrinkage behavior has been made. In addition, the effects of soil structural changes on hydraulic conductivity and moisture characteristic curve have been studied. Results obtained are as follows.
1. Soil consolidation influences the structural shrinkage stage in shrinkage curves. As the consolidation load increases, the structural shrinkage disappears.
2. The values of “Coefficient of structural development (C_sd) ” which is a kind of soil structural index decrease with the increasement of consolidation loads.
3. When the consolidation loads exceed the consolidation yield stress, the C_sd values decrease remarkably.
4. Soil consolidation causes an increase in the shrinking pores and dead pores and the reduction in the structural pores.
5. When the consolidation load is smaller than consolidation yield stress, a rearrangement of the aggregates take places. When the load is larger, the rearrangement of soil particles' in the aggregates take places.
6. The changes of saturated hydraulic conductivity and moisture characteristic curve due to the consolidation correspond very well with the soil structural changes.

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At present, the method which introduces creep of concrete is often used for thermal stress analysis within mass-concrete structures. Concrete is supposed to be a material that has different properties in compression or tension. In the case of analyzing thermal stress, therefore, the most exact analysis must be the method which applies separate creep in compression or tension, respectively. However, it is usual to carry out thermal stress analysis by using compressive creep only, because the computation to use both creep becomes rather complicated. Anyway, if the very accurate analysis of thermal stress is required, it is necessary to distinguish the tensile creep property from compressive creep property. Because of this idea, this paper describes the discrepancy between compressive creep and tensile creep of fly-ash cement concrete.
The test results are as follows.
i) The behavior of compressive creep is different from that of tensile creep; with instantaneous deformation, compression is greater than tension; with time-dependent deformation, tension is greater than compression.
ii) The rate of the flow method which defines a creep is influenced by early age. At early age, therefore, this method can not be used.
iii) Though the ideal method of thermal stress analysis within mass-concrete structures is the method to use separate creep in compression or tension, the method using only one-side creep has the capability to analyze the problem depending on the analyzing conditions.

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An investigation was carried out on cracks appearing in the concrete walls of a large-size farm pond, constructed as a regulating reservoir fot irrigation. Cracks are induced by temperature and shrinkage stresses, which are large as deformations, are restrained.
With relation to the interior concrete temperatures inducing cracks, temperatures varying with time in the model concrete walls were calculated by the three-dimensional finite element method of transient heat conduction, from the viewpoint of applying the finite element method for planning irrigation, drainage and reclamation engineering.
On one hand, temperatures were measured by chromel-almel thermocouples having a diameter of about 0.1 mm embedded at various places in the model concrete walls constructed in the neighborhood of the laboratory.
Good agreement between the measured and calculated temperatures was obtained. Some meshgrading schemes for modeling and step times for direct integration with respect to time were investigated. Calculations were carried out using a microcomputer. The present prediction method for interior temperatures in the concrete walls of a farm pond is useful.

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