In this case study in Hiyoshi town and Maizuru City, Kyoto Prefecture, paddy-field-use under the Rice Production Adjustment System (Seisan-chosei of rice) is analyzed by each lot, to clarify of characteristics of use and management of paddy field in small scale paddy areas. Relative distance between paddy aggregate and settlement, at first, is a factor in alternative choice of converting use and set-a-side of paddy. Secondly, paddy field consolidation is a factor in determining way of use and management, for instance, consolidated paddy field is properly used and managed. In the area where paddy fields are used and managed privately by each farmer, however, one lot of paddy is used and managed divisionally and fixedly.

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Low DO distribution is generally found at the bottom of lakes and ponds. Usually, when wind blows in such condition; the water with low DO content is swept up to the surface at windward, and high DO content is sank into the bottom at leeward. These phenomena were observed at Kitaura of the Lake Kasumigaura as well. However, different phenomenon were observed at Nishiura of the Lake Kasumigaura. The DO concentration was high at both windward and leeward of offshore in Nishiura of the Lake Kasumigaura. Therefore, using 3-D water quality model, we tried to clarify why the different phenomena occured in Nishiura and Kitaura. There were some simulations for the current movements of Kasumigaura; however, there were no water quality 3-D models. The simulated results of the flow directions and velocity distributions were different from those of the other researchers; however, velocity distribution data, which were observed by the hydraulic model experiment, coincide well with our simulationresults. The simulation results suggests that the unique DO distribution observed at Nishiura was correct. Therefore, we estimated that actual lake current will show the movements which are similar to the simulation results.

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In fatigue crack of the asphalt pavement, there are Bottom-up cracking which progresses from the bottom of asphalt mixture layer to the surface and Top-down cracking which progresses from the pavement surface. In the light volume traffic asphalt pavement like as the farm road, it has been considered that the Bottom-up cracking which is manifested as alligator cracking is dominant. And the investigation and analysis of the Top-down cracking which is manifested as longitudinal cracking within the wheel paths have been examined only in the asphalt pavements for heavy volume traffic like as national road and expressway.
In this study, the cores extraction investigation and the traffic census, etc. for the farm road asphalt pavement without repair hysteresis in Fukushima prefecture were carried out. And from the investigations in this area, it was confirmed that the cracking longitudinal cracks which appears at the asphalt pavement surface were the Top-down cracking, and from fatigue analysis it was found that the Top-down cracking is more dominant than the Bottom-up cracking in this area.

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A new approach is proposed to evaluate flood mitigation effect that an irrigation tank with a spillway plays during a storm event. The runoff process in the catchment of an irrigation tank is firstly modeled as a transfer function in the discrete time domain. The parameters of the model are identified from observed data of precipitation intensity and runoff discharge. The identified model is optimized in terms of reproducibility of runoff phenomena. The optimal model is a hybrid model consisting of a runoff separation module and an ARX (autoregressive model with exogenous input) module. The model is transformed into a transfer function in the frequency domain to be associated with a physically based simple linear storage model. Dynamics of flood propagation over the irrigation tank are considered in a linearized system describing the conservation law of water and hydraulic characteristics of the spillway. The transfer function from the inflow discharge, which is equal to the runoff discharge from the catchment, to the outflow discharge, which is the overflow discharge from the spillway, is used for evaluating flood mitigation effect of the irrigation tank. The proposed approach is validated through the application to an existing irrigation tank and its gauged catchment. The irrigation tank turns out to mitigate floods from the catchment in a reasonable range of frequencies.

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The objective of this research was to investigate the internal water movement in tomato and the fruit development under greenhouse culture. Water movement through the main stem of tomato was emerged from daytime until midnight. Cultivation of tomato without top pruning results in plant height becoming very tall and producing a lot of flower buds. Therefore, moisture absorbed by the roots after sunset was used to recover the moisture deficit of plant occurred in daytime and develop the fruits. The water flow at petiole and peduncle indicated symmetrical direction because of the connection of these conductive tissues. During the days with plenty of solar radiation caused abounding transpiration from leaves by high temperature and big saturation deficit such that the water stored in the fruits outflow. From the evening until the next morning, the amount of moisture exceed the outflow rate during daytime was replenished through peduncle as the stem flow, which becomes a maximum around eight o'clock in the night. These were confirmed by the change of fruit's size, which had a little positive correlation with the flow through peduncle while had little correlation with meteorological elements. Irrigation of evening is expected to increase the inflow to fruit by translocation and active water absorption rapidly.

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It is known that habitat use of riverine fish depends on multiplicity among physical environments and waterquality. Habitat selections even differ between conspecific fish in rivers and hatcheries. For this reason, it is necessary to develop habitat preference models in the field studies. In this study, a modeling technique for instream fish habitat preference was proposed. The preference intensity of Japanese Medaka (Oryzias latipes), dwelling in an agricultural canal with the three environmental factors of water depth, current velocity and cover ratio, was quantified using the on-the-spot examination data. For explicitly taking essential vagueness of fish behaviour into consideration and for searching for an optimal model structure, two artificial intelligent techniques were introduced: a simplified fuzzy reasoning method and a simple genetic algorithm, respectively. Therewithal, the uncertainty contained in measurement as errors or dispersions of physical environment were positively taken into the model using symmetric triangular fuzzy numbers. The fuzzy preference intensity model was thus constructed, which resulted in a positive agreement between predicted and observed distribution of the Japanese Medaka resident in an agricultural canal.

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This paper discusses effects of cover plants on surface runoff on the basis of hydrological observations for three years in five plots. Four of these plots were cover-plant plots vegetated with Cynondon dactylon Pers., Dichondra repens Forest. and Artemisia princes Pampan., and the other one was a bare-surface plot. Comparison of runoff records in these plots showed that cover plants reduces both total runoff and peak runoff. The total runoff from cover-plant plots was 26-39% of that from bare-surface plot, and the peak runoff from the cover-plant ones was 24-35% of that from the bare-surface one. A rainfall-runoff model was developed, in which overland flow was described as Manning type and infiltration process was expressed by the Horton's equation. Calculated hydrographs by the model were in good agreement with observed ones. The results of rainfall-runoff analysis using the model showed that infiltration in cover-plant plots exceeded that in the bare-surface plot for the same rainfall pattern. The asymptotic infiltration rates in cover-plant plots were about four times as large as that in the bare-surface plot. Besides, the results showed that occurrence of surface runoff in cover-plant plots was less frequent than that in the bare-surface plot, which suggests that cover plants suppress the occurrence of surface runoff.

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Buried pipelines are subjected to large buoyancy when surrounding soil liquefies. The pipe floats up when the buoyancy acting on it exceeds the effective overburden loads. However, it is considered that the uplift mechanismsare not only due to the equilibrium of vertical force alone, but also the shear deformation of surrounding soil induced by earthquake.
The purpose of this study is to clarify the uplift mechanism of buried pipe subjected to cyclic simple shear in dry sand.
The uplift displacement of buried pipe and contact force distributions between soil particles are calculated by the distinct element method. In addition, void ratios around the pipe are calculated to examine the behavior of surrounding particles.
It was found that the buried pipe model having a large diameter with the same density as the soil particleswas more likely to uplift compared to the soil particle that constitutes the surrounding ground. It was clarified that the buried pipe model uplifts due to the reaction force from the lower ground as the pipe model moves laterally. In addition, the intrusion of soil particles to the bottom of the pipe model was examined from the changes of void ratio of the surrounding ground.

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When the open-channel route is selected, the chute method, in which the longitudinal profile and alignment of the channel are bent at sharp angles, shall be selected in the places where the land around the route is extremely narrow, small, precipitous, and crooked. Therefore, Spiral Flow Channel is developed in order to control the running water flowing on the flexion of the open channel. The side wall of the channel is built in a circular arc shape (210°) and the fast inflow into the flexion is then changed into a spiral flow along the circular arcwall, if it is within 45° degree of largest flexion angle. In this paper, hydraulic model test of spillway of irrigaton pond was carried out on 2 types of 65° and 90° which increased degree of flexion angle of the Spiral Flow Channel, and it was shown that stabilizing flowing water control is possible. In addition, the hydraulic design method was described based on until now research result for the case in which the engineer designed the Spiral Flow Channel.

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