In order to grasp distribution characteristics of fish fauna, field investigation was carried out in five hill-bottom valleys located in the upper stream of the Kokai River, Tochigi prefecture. The results obtained by the investigation were as follows: 1) A dense populated zone of Hotokedojyo was identified at Tanigashira, upper reaches of hill-bottom valley, 2) similarly, a dense populated zone of Numamutsu and Simadojyo was found at Tanijiri, lower reaches of hill-bottom valley, 3) on the contrary, dispersive distribution in the central area of the hill-bottom valley was found for Dojyo and Tamoroko. The results of correlation analysis showed a significant level relationship (p<0.01, p<0.05) between fish abundance of the surveyed station and ditch distance from Tanigashira to the surveyed station for Hotokedojyo, Simadojyo and Numamutsu. In terms of environmental factors, a negative correlation was found between fish abundance and water temperature on Hotokedojyo, a positive correlation between fish abundance and water temperature on Simadojyo, and a positive correlation between fish abundance and decrease in accumulated height of weir on Numamutsu as well.

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In this research, strength development of massive concrete specimens, that have comparatively equal unit cement amount to the actual huge concrete structures, were evaluated with the pulse velocity method and extracted cores from the surface and center part of specimens. From the test results of standard cured specimens, it was confirmed that the strength development of low cement content concrete showed slight increment after age 56 days. Applying the pulse velocity method to massive concrete specimens from their initial age, it was possible to evaluate the strength development. Furthermore, it was confirmed that the strength development was influenced from the temperature history at the initial age of concrete. From the test results of cores extracted from massive concrete specimens, test age of standard specimens for managing the strength could be enough at age 56 days, as well as it was necessary to manage the temperature at the initial ages for the affordable development of compressive strength.

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In order to clarify how the lot-management water requirement (LWR) and the delivery water requirement (DWR), which are regarded as independent components the paddy water requirement design of Japan, change, vary and correlate depending on water source stability water distribution in two irrigation areas of gravity-continuous irrigation (GCI) in the Kokai River basin and pumping-intermittent irrigation (PII) in the Kinu River basin was studied. LWR and DWR as well as applied water in the two areas both of which were divided into upper and lower blocks were surveyed once in two weeks for two irrigation seasons. The following findings were obtained: 1) The ratio of water effectively stored in paddy plots was rather less in PII area and the lower block of each area where less water was available. 2) Under the unstable water distribution condition farmers in the upper block tended to take excessive water, thus resulting in insufficiency and unstableness of water in the lower block. 3) The two water requirements of LWR and DWR are not independent; the distributed water in a paddy block was first diverted for storing on paddy plot and LWR, and the rest appeared at the tail-end of ditch as DWR.

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In this research, Tc-To method, Delta method and Short distance detour wave method those are the estimation method of crack depth of concrete by ultrasonic pulse method are targeted, formulation background and applicable condition of estimating equation are examined. Moreover, cause with inferior estimation accuracy of crack depth and the best installation position of oscillator and receiver are examined. As a result, the following was clarified. Though ultrasonic pulse velosity of the sound part and the cracked part should become the same from the construction of estimating equation of the crack depth, the ultrasonic pulse velosity of both was actually different. When the detour wave of ultrasonic pulse become right angle, the estimation value of the crack depth close to the true value. And, the conditional equation to decide the best installation position of oscillator and receiver was derived.

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Zero Flux plane (ZFP) is defined as a plane, which separates two zones of upward and downward movement of water in soil with upward and downward flow occurring simultaneously. In this study, the analysis of the ZFP movements was carried out by two sets of laboratory experiments and numerical simulations, especially paying attention to the effect of the periodical water supply. In the first set of experiment and simulation, surface Andisol soil was used and water was supplied only one time. Evaporation rate was set to 0.15 cm/day, and water was drained from the bottom of the column. The total potential profile and the ZFP movement of experiment and simulation agreed reasonably well. In the second set of experiment and simulation, subsurface Andisol was used and water was supplied periodically. In both experiment and simulation, ZFP appeared at soil surface every time water was supplied, and it gradually moved downward until it reached to the depth of 30 cm, when the ZFP disappeared. We discussed that such disappearance of the ZFP is observed when the initial soil water content at the deep zone is relatively high. In contrast, when the initial soil water content at the deep zone is relatively low, as reported in previous studies, ZFP continues to move downward for a relatively long period. Simulation of ZFP movement was also conducted for different types of soils. Based on the results of this study, a strategy for the periodical water supply in arid and semiarid regions using this ZFP concept was proposed.

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A compacted clay liner is constructed at the bottom of landfill sites, which serves as a hydraulic barrier to flow of leachate from wastes. The performance of clay liners could be degraded when they are exposed to the leachate from bottom and fly ash with various contaminants. In the present study we conducted serial batch tests with 110 repeated washings for different pH solvents to predict long-term leaching patterns for heavy metals and other soluble ions in the bottom and fly ash. The equilibrium pH of leachate for pH 3 solvent began to decrease dramatically immediately after starting of washing. For the solvents of pH 3 and above, a few mg/L, Pb was leached while Zn and Cu were scarcely dissolved. The heavy metals were all dissolved in a geater amount by pH 2 solvent compared to other pH solvents. For the soluble ions other than heavy metals, irrespective of solvent pH, Na, K, Cl, and SO42-were all leached in a great amount in an early washing stage and Ca was leached throughout washings, while Mg was scarcely dissolved for the pH solvents other than pH 2.

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Soil compaction during paddy field consolidation can be managed using TS/GPS positional information about the bulldozer. This method delimits the working area as a grid, and manages the frequency of compaction at every square mesh. However, management accuracy varies depending on the size of the square mesh and the method of determining compaction. In addition, the bulldozer performing paddy field consolidation may travel in various directions over the working area. We examined the size of the square mesh and the method of determining compaction for all directions of bulldozer travel. We recommend the following square mesh size parameter and assessment method for compaction control in paddy field consolidation.
(1) A square mesh size of 20 cm is suitable regardless of the width of the bulldozer's crawler belt.(2) The action ratio method is suitable for determining compaction. This method uses the rate at which the bulldozer crawler belt acts on the square mesh. The cumulative error rate is minimized in this method.

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Farmlands provide with food security benefits for all of Japanese people. Monetary value of food security benefits from farmlands is practical in using cost benefit analysis, but the value has not been estimated yet. The aim of this study is to estimate the value by choice experiment with other programs, and inspect whether food self-sufficiency in the region effect on utility functions. The result indicate that food self-sufficiency in the region does not effect on utility functions, and WTP for food security in 8, 500 ha is about 162.9 yen/year·household.

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The mode I fracture behavior of dam concrete have been tested by notched cubic specimens and wedge splitting procedures allowing for stable crack growth. From the measured load-displacement curves, the specific fracture energy and the tension softening diagrams were derived. In the process to evaluate numerically the tension softening behavior the poly-linear approximation analysis method based on the fictitious crack model was used. Based on the experimental and analytical data a tension softening diagram was proposed for dam concrete and applied to the fracture analysis of concrete specimens. The results showed that the specific fracture energy of dam concrete determined by experiment was larger than that evaluated from both compressive strength and maximum size of aggregate. The load-displacement curves obtained from the fracture analysis using the proposed tension softening diagram agreed well with experimental results compared to those of the bi-linear or exponential function models.

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In order to obtain basic data for producing fertilizer nutrients adjusted compost, biomass materials was classified with standard tables of feed composition in Japan and applicability for controlling fertilizer nutrients was considered. Using criteria based on C/N ratio representing nitrogen mineralization properties, bran, oil seed meals, tea leaf residues and two thirds of crop by-products and food processing by-products were available as material to adjust fertilizer nutrients. However, almost all these biomass contained a large amount of nitrogen as compared to phosphoric acid and potassium. This indicates nitrogen in compost can be adjusted with the biomass classified in this study but not phosphoric acid and potassium.
Demands of compost users for quality were also investigated and methods to fulfill demands by blending biomass were considered. The results indicated that demands activated compost can be produced by selecting the appropriate biomass materials.

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Water and mass budgets of small farm pond and regulation pond were estimated and discussed. As results, 35% of annual rainfall in the forested catchment flowed into the farm pond and 64.7% of that in domestic housing catchment flowed into the regulation pond. Water stored in the farm pond replaced 9.2 times by inflow annually on average (4.6 times based on inflow in low flow periods), and that in the regulation pond replaced 441 times (58 times in low flow periods). In both ponds, influent and effluent mass fluxes were almost balanced in M-Alkalinity and EC. Effluent fluxes were larger than influent fluxes in T-COD, D-COD and Chl-a. Influent fluxes were larger than effluent fluxes in SiO₂. On the contrary, differences in the mass budget of nitrogen (N) and phosphorus (P) were recognized between two ponds. N fluxes were reduced or balances and P fluxes were increased in the regulation pond though total N and P fluxes were increased and dissolved component of N/P were decreased in the farm pond. These differences came from the differences in the speed of water replacement in two ponds, which would cause the differences in the production of the plant biomass inside ponds.

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The integrated environment of computational fluid dynamics by particle methods was developed so that an engineer may be easily able to analyze the phenomenon which free surface has large deformation in an hydraulic structure for irrigation. That has been composed of 3 stages of pre-processing, fluid analysis and post-processing, and has been easily handled by GUI. Following features are proposed: The algorithm which forms calculation point from the drawing data as pre-processing for the particle methods analysis and the treatment method in boundary condition. As an example, The effect of the upstream weir on water surface oscillation in the water-cushion division is analyzed. It is shown that the upstream weir makes water surface oscillation dissipate in water-cushion division by using this integrated environment.

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In this research, the test for autogeneous shrinkage strain of dam concrete specimens that used the coarse aggregate of the full size was executed, and the characteristic of autogeneous shrinkage of a dam concrete was examined. As a result, it was experimentally confirmed the autogeneous shrinkage strain was generated in a dam concrete that used the coarse aggregate of the full size. In the temperature regulation plan of a concrete gravity dam, it was clarified to have to analyze the temperature stress that considered the autogeneous shrinkage strain. Moreover, the validity of the method of test for autogeneous shrinkage strain about dam concrete specimens that used the coarse aggregate of the full size was confirmed by doing a two-dimensional finite element analysis and a three-dimensional finite element analysis.

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Daily precipitation data observed at six meteorological observatories located in the region of Niigata Prefecture were collected, and the periodic variability of precipitation characteristics was investigated and discussed by applying spectral analysis and the moving average method. It is shown that a periodic variability of about 20 years is present in time series of annual precipitation in Niigata and Murakami located in the coastal region, and is similar for both cold (Dec.-April) and warm (May-Nov.) season precipitation, and that a periodic variability of about 10-30 years for annual precipitation in Takada, Nagaoka and Toukamachi in the heavy snowy region is similar to that of cold season precipitation with the exception of Yuzawa district. It is shown that time series of annual snowfall in Niigata, Murakami and Takada are composed of the components of a periodic variability of 10-15 years, and that the periodic variability of annual snowfall in Nagaoka, Toukamachi and Yuzawa is 30-40 years. It was indicated that a distinctive periodic variability of less than 10 years exists in time series of annual maximum daily precipitation and annual maximum storm total at all locations.

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The object of this paper is to establish a prediction equation for strength of porous concretes f_c. The strength values were postulated to be as a function of void ratio e and cement-water ratio α. Compression tests were conducted for porous concretes with No.5 crushed stones or recycled aggregates under different e and α values. Plotting the test data in the space with e, α and f_c, it was found that f_c values laid on a certain surface in the space. An equation was developed by formulating the surface as products of two independent linear equations for e and α. The compression strength values estimated by the equation were within almost less than 10% errors. The proposed equation expressed a good agreement to the experimental results.

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It is known that it is appropriate to maintain non-cultivated or abandoned paddy fields in suitable condition for timing their restoration, as part of a farmland resources management system preparing for the possibility of a food supply shortage in the future. Although it is required to repeat weeding and repairs every year in order to maintain the integrity of fallow paddy fields at a low price, examination of the concrete contents of the method has not been sufficient. So, in this research, we conducted such research for the purpose of proposing a suitable method ofeffective maintenance of a fallow paddy field. As a result, we show that weeding of today's fallow paddy fields is lacking summer fallow cultivation and is dependent on chemical herbicides. Moreover, we demonstrate two points. The first is the importance of inundation management, which not only reduces the need for chemical herbicides but also is a labor saving measure when we focus on restoration of abandoned paddy fields. The second point is the spread of summer fallow cultivation will become a solution for decreasing the use of chemical herbicides. M oreover, we proposed about the spread conditions of summer fallow cultivation.

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A Local Approximation (LA) method was applied to predict dissolved oxygen (DO) at the water surface and at the bottom of Lake Koyama, which is a eutrophic lake. This is to predict in short-term DO by using the orbit information extracted from only its time-series obtained in real time. In the case that the time-series has a noisy signal deriving from observation equipment, however, the noise reduces a prediction accuracy by the LA. In this study, the de-noising based on a wavelet analysis was incorporated into the short-term prediction to improve the prediction accuracy and the prediction term by removing observation noise. As a result, only the prediction accuracy could be improved by applying a level-dependent soft thresholding to the coefficients of the high-level wavelet components in the original time series. Next, it was proposed to predict the time transition by applying the LA to the high and low frequency components to which were decomposed the de-noising time series. As a result, the prediction accuracy and the prediction term could be exceedingly improved. The effectiveness of the proposed short-term prediction method could be admitted from the viewpoint that the improvement of the prediction term for the DO at the bottom during the summer was especially remarkable.

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This paper is devoted to analyze the change in flow properties by changing the longitudinal spacing between submerged semi-spherical obstructions in a series, from the point of view of designing nature-like fishways embedded with stones. A Godunov type numerical model of two dimensional shallow water equations using quadtree grids has been applied to compute the flow over 3D semi-spherical obstructions. The numerical results show that there is a limit to which obstruction spacing can be reduced to create a favorable flow condition for fish ascending. Likewise, the ratio of velocity reduction reduces as the obstructions become closer.

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In order to investigate fertilizer efficiency of rural sewage sludge-rice husk compost (hereinafter, SH compost) and the behavior of nitrogen after application, Komatsuna (Brassica rapa var. peruviridis) cultivation was conducted with three different rates of SH compost application.
Fertilizer efficiency ratio of SH compost was 58% to chemical fertilizer. This suggested SH compost was considered to be readily available fertilizer like poultry compost. However, nitrogen recovery rate decreased as the amount of SH compost application increased.
The measured δ¹⁵N of Komatsuna leaf increased as the amount of SH compost application increased. Nitrification, denitrification and ammonia volatilization in soil might increase the δ¹⁵N of Komatsuna leaf in this experiment. The reason of increase in δ¹⁵N was thought to be not nitrification but the changes of emission rate of N₂O or NH₃ to the atmosphere since nitrogen recovery rate decreased with increase in the amount of SH compost applied.

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There has been increasing awareness on the traceability of agricultural produce, as consumers have become more concerned about the safety of food. Disclosure of the information on cultivation history using information technology has become moreavailable, but such information has not yet been utilized effectively. Possible reasons behind this are the unclear content of traceability information, methods of disclosure and the purpose of disclosure. In order to work out this problem and to assure food safety, this study conducted an experiment on the cultivation sites of apple, a major produce in the Aomori prefecture, aiming to realize a traceability system with visualized infonnation and two-way communication between the producers and the consumers. Obtained results are asfollows.
(1) Consumers can understand the production site intuitionally as a visual image and it will be helpful for the creation of reliance on food and producer as well. On the other hand, information may create the risk of misunderstanding. So it is importantto carry out the interactive traceability that can exchange the opinion between consumers and suppliers.
(2) Producers would be able to express their messages to consumers in visual form. Additionally, we can expect effective risk analysis of production site and improvement of producer's consideration from the utilization of visual images. And a series of activity have possibility of achievement in Good Agricultural Practice.

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Recently in Japan, cultivation abandonment paddy fields in hilly and mountainous area has been increasing because of less favored conditions for cultivating and lack of core farmers due to decrease and aging of farmers there. In this paper, a land consolidation project area in hilly and mountainous area was investigated, where a community farming group whose farm size was 25 ha and cultivated mainly only one full time worker was established and thus whole the paddy fields are cultivated and conserved in spite of the inferior cultivating conditions. As a result, it was made clear that the farming group secured the full time worker by assure sufficient salary to him, zoning-system was adopted and the farming group was cultivating mainly the area of large rice paddy plots for efficient farming work, and moreover, the farming group has been making effort to employ supporters of farming work from not only farmers in the village but also non-farmers in and/or out of the village. However, as it remains less favored conditions for cultivating even after the land consolidation project, increase in farm size of the farming group is difficult; thus it is considered public support will be needed for the group to assure sufficient salary for full-time worker in case rice price decreases.

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Rice terraces in Japan have recently been threatened with the abandoning of cultivation. In order to conserve them, many support systems that involve the investment of money and labor have been implemented. This paper investigates the case of rehabilitated rice terraces of Maruyama-Senmaida, a very famous and typical area for rice terraces. The contents of conservation works and monetary supports are analyzed and the related problems are highlighted. In the Maruyama area, the local government rehabilitated rice terraces with an area of 2.4 ha. A group of farmers began to cultivate and conserve them and invested a total of more than 1200 man days. Approximately 12 million yen was required for these conservation support activities; this amount was obtained through subsidies from local and central governments and from the fees paid by the participants of the Ownership and Trust Program conducted in cities. The total acreage of rice terraces conserved by the Ownership system was limited because of the scarcity of participants from cities and also of farmers who support these participants' agricultural works. As a result, it is discussed that a vast amount of monetary and labor support is necessary for the conservation of rice terraces and that it is difficult to conserve all the terraces in Japan by this method; thus, conservation areas would be limited.

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It is said that the walls of circular arc top or inclined top are preferable for upstream migration of fish in pool and weir type fishway. Hydraulic characteristics for design of this type fishway with walls of circular arc top has been almost clarified. However, hydraulic characteristics about inclined top has not been clarified enough. This research showed that numerical analysis using VOF method in Cartesian coordinates, to which the concept of fraction of cell volume and cell face open to flow are applied, is effective. Additionally, occurrence condition of streaming flow which is thought to be not preferable for upstream migration of fish was indicated.

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This paper aims to systematize the diversity of irrigation modernization through comprehensive review of present prospects and surroundings about the modernization. Focusing on saving water, it was clarified that general movement of the modernization was subject to the strategic concept concerning integrated water management presided by the water sector. Moreover, “spontaneity-based approach” in which irrigation water demand is reduced by means of motivating water users internally, is superior rather than “regulation-based approach” in which the demand is controlled by regulation and restriction externally. In this respect, the agricultural sector should take the lead in a promotion of the demand management putting her advantages for adopting the former approach.
Furthermore, analysis reviewed several modernization projects was indicated that irrigation modernization could be simplified into four categories, namely, 1) improving irrigation water delivery and use service to users, 2) raising management level in quantify of water, 3) raising management level in quality of water, 4) reducing governmental intervention in operation and maintenance.

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