It is said that agricultural water supplies and irrigation channels are an important element of rural landscapes. In this research we made sample photographs based on irrigation channel landscapes comprising the five attributes of viewing angle, channel materials, water depth, fences, and sitting conditions, then conducted a visual evaluation test on 185 subjects who had various attributes. Performing a conjoint analysis of the data resulted in these and other findings:(1) Water depth is the most important attribute affecting the preferences for irrigation channel landscapes. We also determined that subjects tended to have the same preferences in relation to the levels of the attributes that constitute the irrigation channel models.(2) We found differences in subjects' preferences depending on age group, gender, area of residence, and occupation.(3) When keeping channel sitting conditions the same while changing other attributes, subjects had a greater preference for a landscape if its channel water was deep, regardless of channel material, but channel material became a determining factor in the preference for a channel landscape if the water was shallow.

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This study evaluated the uplift resistance of anchor on two-layered sand masses, by comparing a conventional 1g model test with finite element analysis. In the experiment, a sand bed was prepared by pluviating air-dried Toyoura sand. The tests were performed six kinds of sand masses that were uniform dense, uniform medium, uniform loose, lower layer of dense (upper layer of medium and loose) and lower layer of medium (upper layer of dense) conditions. The height of sand mass was 20cm for uniformed condition and 10cm for each upper and lower-layers in two-layered sand mass. From the study, the results of finite element analysis showed good agreement with experimental results in all cases. In the uniform condition, the softening after reaching peak load and the shear band propagation differed according to the density of sand mass. In two-layered sand masses, the shear band propagation was depended on the density regardless of the position of layers. The softening after reaching peak load was remarkable on lower layer of dense condition and not clear on lower layer of medium condition. The loaddisplacement curves were affected the density of lower layer and not sensitive on density of upper layer.

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The dynamics of substances in percolating water were investigated using paddy field models which were planted with rice and fertilized. Percolation patterns of both plow layer and plow sole were set up in these models for closed system percolation. In one of these models, in which the groundwater level was high, the percolation pattern of the subsoil layer was set up as closed system percolation. In another model, in which the groundwater level was low, it was set up as open system percolation in the part above groundwater level, and as closed system percolation in the part below groundwater level.
The results were that concentrations of nitrate nitrogen and nitrite nitrogen in downstream water were higher in the upper part of the subsoil layer with open system percolation than in both the plow layer and plow sole with closed system percolation, whereas they tended to be lower in the lower part of the subsoil layer with closed system percolation than in both those layers. Concentrations of iron and manganese in the subsoil became higher in the part with closed system percolation than in that with open system percolation. Bases such as that of calcium tended to rise in their concentrations, being affected by the increase of iron concentration in the soil water.

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In order to control the methane emission of rice paddy fields, the authors compared both the watering irrigation plot and the conventional plot with respect to methane fluxes. Watering irrigation was done from the 8th day (Tachikawamachi) and the 11 th day (Yamagata University Farm) after rice transplanting, until mid summer drainage.
The results obtained are as follows.
1. In both rice paddy fields in Tachikawa-machi and Yamagata University Farm, the methane emission in the watering irrigation plot was about half as much as that in the conventional plot.
2. A yield of rice in the watering irrigation plot was about the same as much as that in the conventional plot in both rice paddy fields.
For the reasons mentioned above, the method of water management, that is watering irrigation after rice transplanting, was exceedingly effective in order to control the methane emission of rice paddy field. Studied method did not reduce production, but it could control about half methane emission.

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In prediction of water movement in soil accompanied with freezing and thawing in arid cold region, hydraulic conductivity of the frozen soil must be measured precisely. However, such a method which can be applied to various textures of soils and at lower temperature encountered in actual field situation has not been established. In order to measure the unsaturated hydraulic conductivity of the frozen soil, we developed a new method based on Darcy's law by applying centrifugal force as driving force of water instead of gravity, and examined its basic performance at 20°C and-5°C on sandy, loamy and clayey soils. On unfrozen soils, the centrifuge method caused some compression and the obtained hydraulic conductivity under higher rotation speed was relatively smaller value than that under lower rotation speed, however, the results almost agreed with that obtained by upward suction method. On the other hand, no compression effect was found in measurement of the frozen soils. The measured unsaturated hydraulic conductivity values of the frozen soils were in the range of 10^-9 cm/s to 10^-8 cm/s. Thus, it was revealed that the centrifuge method is a promising method to measure the unsaturated hydraulic conductivity of the soils, particularly frozen soils.

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Currently it is in demand to create vegetated open channels. Using plants and rough stones are placed. Unfortunately, these measures multiply water resistance and change water depth andvelocity. Nevertheless, it is important to consider environmental preservation in riverimprovements and irrigation works. In this study, we suggest a new model to estimate thevegetative resistance from Reynolds equations. At the same time, we also analyze the bending ofvegetation by modeling vegetative deformation as the finite deformation of cantilevers andcoupled with flow.

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This research was aimed to differentiate and evaluate the pozzolanic activity offly ash and cinder ash on mechanical properties of massive concrete. Physical properties of both materials were very different but chemical compositions were similar. The replacement ratio of ordinary Portland cement (OPC) with fly ash was 30% and fine aggregate replacement with cinder ash was 10%. The fineness of fly ash particles was the main factor responsible for strength development of massive concrete while the coarser cinder ash had insufficient effect during the early age of the strength development. Results of pulse velocity revealed that the fly ash enhanced strength development than cinder ash. Moreover, the addition of fly ash favored a close relation between central and outer parts of massive concrete mechanical properties, which was similar to those of standard cured specimens. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses showed that the fly ash had higher pozzolanic reaction than cinder ash. The combination of both materials in massive concrete had significant positive effect on strength development. The utilization of cinder ash as pozzolanic material could be acceptable when early strength development is not desired.

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The viscosity equation of coagulated suspension flowing through capillary tube was theoretically derived taking into account effects of the breakup of flocs due to shear stress and the slipping phenomenon along the wall of tube. The validity of the derived equation was tested by the measurement of the apparent viscosity of the coagulated montmorillonite suspension as a function of electrolyte concentration and capillary diameter. In the region of low electrolyte concentration (0.3, 0.45mol/L NaCl), the viscosity decreased with increasing the capillary diameter, while in the region of high electrolyte concentration (0.8, 1.0mol/L NaCl), the viscosity decreased with decreasing the diameter. These results were fully predictable by the derived equation. That is, the former is due to the breakup of flocs and the latter is due to the slipping of flocs along the capillary wall. It was found that the thickness of the slip layer was 0.4 times floc diameter and the floc strength increased with increasing electrolyte concentration.

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The concentrations and loading rates of herbicide (simetryn and mefenacet) were investigated in Ekainuma lagoon basin at Lake Biwa. The concentrations increased during the application period and during a rainfall event occurring immediately after the application. The herbicides were almost undetectable after two months of the application period. The losses of simetryn and mefenacet from the paddy fields in the lagoon basin were estimated to be 24.9% and 10.2% respectively between April and September in 1998. The purification of herbicide loading (simetryn and molinate) in the lagoon was also estimated between May and August in 2000. The high concentration of herbicide in the inflow water caused by the application or the rainfall event was decreased to a lower level at the lagoon outlet. After the application period the concentration of herbicide in the inflow decreased, and it was often exceeded by that in the outflow. The mass balance of simetryn and molinate during the observation period, when water retention time calculated on an average flow rate at the outlet and pondage of the lagoon was about 65 hours, showed that substantial purification of these herbicides in the lagoon did not occur.

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Most of the earlier studies on fishways have been focused on the flow structure by means of hydraulic models. Since the flow structure in a fishway is complicated with free surface and sub-and super-critical flow conditions usually coexist, only a few papers have been published which had applied numerical methods to the flow in fishways. The work presented in this paper consists of a grid generation based on quadtree grids, and a flow solver using Roe's approximate Riemann solver for convection terms of shallow water equations. The shallow water equations are discretized using finite volumes collocated with the grid cells, and integrated in time using a 4th order Runge-Kutta scheme. The flows in four types (three types for single-slot and one for double-slot) of vertical slot fishway are simulated. The numerical results show that the maximum velocity at the slot, which is almost equal to the theoretical value, and the velocity distribution in the pool do not change very much, even if the discharge would largely change. Moreover, it can be said that more calm region, where ascending fish could take a rest, is created in the single-slot fishway than double-slot type.

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The settling patterns of Leda clay suspensions over wide ranges of water content (500 to 6000%) and salinity (0.5 to 30g/L NaCl) are influenced by a series of mineralogical and chemical factors. In order from least flocculating to most flocculating, the settling patterns are: dispersed free settling; flocculated free settling; zone settling; and consolidation settling. In general, higher suspension particulate concentration and higher salinity encourage sedimentation by more-strongly-flocculating patterns. Relative to the control material (a Na-saturated Leda clay, with 59%<2μm material and dominated by low-activity minerals, which exhibited all the settling patterns within the water content/salinity ranges investigated), the water content/salinity boundaries between sedimentation patterns were shifted toward lower salinity and higher water content (in favour of more-strongly-flocculating patterns) by: augmentation of clay content (strong effect); addition of high-swelling smectite (strong effect); presence of ions more strongly flocculating than sodium (strength of effect not tested, but could be strong); and removal of the in-situ, <1%, organic matter by oxidation (small effect). The boundaries were shifted towards higher salinity and lower water content (in favour of less-strongly flocculating patterns) by: addition of co-sedimenting, particulate iron oxide (small effect); decrease in the clay content (strong effect); and augmentation of organic content with fulvic and humic acids extracted from peat (very strong effect).

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In the Ngamoeyeik Irrigation Project Area outside of Yangon City in Lower Myanmar, rainy season paddy cultivation has traditionally been performed from the seedling period in June to the harvesting in November under rain-fed conditions. Summer paddies with irrigation from December to May were added after completion of the project in 1995. However, the project's rainy paddies often suffer from inundation of rain, and the irrigated summer paddies are constrained by limitations in the water-storage reservoirs. To improve this situation, we here propose the development of a paddy cropping schedule for the project, based on our analysis of the 76-year rainfall record at Yangon. The main results of our analysis are as follows:(1) the tendency of farmers to transplant their crops at the end of June, comes from the security of rain water supply, thus increasing the possibility of inundation damage;(2) by shifting the transplantation for the rainy paddies to the end of May, the plant height can be more than doubled, reducing the possibility of inundation damage;(3) such a one-month shift in the transplantation for rainy paddies can be made feasible, even from the viewpoint of water resources management, through proper reservoir operation.

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A laboratory experiment was performed to clarify the fundamental structure of the open channel flow over submerged vegetation. As a result, it was clarified that the horizontal two dimensional turbulence analysis model can calculate mean velocity at vegetation and surface layer, and lateral mixing.
The laboratory experiment shows that the vertical two dimensional flow occurred in both the vegetation layer and surface layer, and organized horizontal vortices were generated along the boundaries of the vegetation.
A numerical computation employing SDS & 2DH turbulence models was introduced to investigate the resistance and the roles the surface and vegetation layers, and the effect of generated turbulence. The results provided the basis for a new method which can apply not only to the flow with non submerged vegetation, but also to the flow over submerged vegetation and roughness.
This model can predict the mean velocity of the surface and vegetation layers, and provide information on the shapes of vortices, lateral distributions of the depth averaged flow velocity and turbulence statistics.

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This study assessed the water depth in the channel that created perception of beauty for channel landscape in terms of preserving and/or creating amenity spaces in rural areas. Visual evaluation tests were carried out to identify the relation between the water depth in the channel and its attractiveness. The results of the tests and analyses were as follows:(1) Excellent visibility of the channel and surrounding landscape results when subjects stand about 1 m apart from a channel or on a bridge across a channel.(2) The effect of water depth on the attractiveness of the channel was assessed by having subjects choose the level that they found most pleasing of the five tested (0%, 25%, 50%, 75%, and 100% of the channel depth). The results show that this method effectively identified the water depth necessary for a favorable impression of the channel and the surrounding landscape.(3) The water depth that creates a perception of beauty is 75% of the maximum depth of a concrete channel, 25%-75% of maximum for an unlined channel, and 25% of maximum for a masonry channel.

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A comprehensive approach to design of sprinkler irrigation systems is to treat a rotation block as one unit. Water utilization efficiency of a designed rotation block should be evaluated, but an evaluation method was not developed yet. The rotation block is now designed with two different criteria. A spacing between sprinklers is determined to achieve an acceptable value of water distribution efficiency on a surface covered by four sprinklers. Lateral and submain lines are designed to achieve an acceptable discharge variation from sprinklers in the rotation block. The coefficient of variation in statistic terms is one of measures to appraise the water distribution efficiency. The coefficient of variation has been related to the Christiansen's uniformity coefficient and the pattern efficiency. The coefficient of variation has also been related to the apllication and storage efficiencies. In this paper, the coefficient of variation of water on the surface covered by four sprinklers will be related to the discharge variation from sprinklers in the rotation block.

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In the Hetao irrigation district, soil salinization and water shortage have been occurring. To study the effect of traditional desalinization techniques, we set up experimental sites near Shahaoqu station and started soil improvement since 1994. The techniques employed were mixing organic materials in soil and ponding irrigation in autumn (leaching). This paper reports the results of annual changes of soil chemical and physical properties at experimental sites. Mixing organic materials in soil did not improve soil physical properties, however EC values (soil surface and profile) were lowered by ponding irrigation in autumn. It was confirmed that soil desalinization can be done by ongoing desalinization techniques.

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