Diversities of soil meso-fauna and types and amounts of fertilizer in soil dressed and no-dressed fields around Tama-shi, Tokyo were investigated in this study. Diversity index of Simpson (l/λ) and that of Fisher (α+1) were employed for evaluating bio-diversity. There was no certain difference in population, number of genera and two types of diversity indices between dressed and no-dressed fields. Fisher's diversity index seemed to be larger in soil dressed fields, while Simpson's diversity index seemed larger in no-dressed fields. According to Stabilized soil moisture increases number of soil meso-fauna, we concluded that combination of those indices of soil meso-fauna enables to estimate the degree of farming term of the field after soil dressing. Co-relation analysis showed Fisher's diversity index was significantly affected with amounts of fertilizers. We also concluded fertilizer application support increasing Fisher's diversity index of soil meso-fauna in fields.

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In this paper, two types of direct runoff which include fast or slow runoff component were separated using the observed discharge data in a terraced paddy catchment and a forest one to compare them and discuss the properties. As a result, it was found that the direct runoff in the terraced paddy field catchment was greater than that of forest catchment and direct runoff in irrigation season of the terraced paddy field was also greater than that in non-irrigation season. Then, water balance concept was applied to the period of direct runoff. It was shown that the percolation rate of the terraced paddy filed catchment was less than that of forest one and the rates were similar in non-irrigation and irrigation season of the terraced paddy filed. Furthermore, the effect of initial soil moisture deficit on direct runoff was discussed.

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During excavation of soil from an area with a high groundwater level, seepage failure of soil such as piping or boiling becomes a problem. In recent years, a new type of accident has occurred with respect to seepage failure, because deep excavation has been proceeding due to the construction of large-scale structures. A case study was carried out on seepage failure of excavated bottom soil in a steel-sheet-pile-wall cofferdam. First, evaluations of safety factors with respect to seepage failure of soil were conducted using standards and correction methods for plan view of excavation. Second, seepage flow and stability analyses were performed and the following results were obtained:
(1) H_c, the critical hydraulic head difference between up-and downstream of sheet piles, that is calculated using standards and evaluation methods for seepage failure of soil in front of a single sheet pile wall in two dimensions, is greater than the actual value.
(2) Correction methods give a good estimation of H_c, where the plan view of excavation is thought to approximate the real shape, such as rectangular or circular.
(3) Using Harza's method considering the exit gradient as a seepage failure criterion, H_c is estimated as larger than the actual value.
(4) According to flow conditions, a safety factor with respect to seepage failure F_s is given as follows: F_s (AXSflow) =0.402 F_s (2Dflow), which indicates the decrease in F_s from the 2Dflow to AXSflow condition is very large. The 2Dflow condition represents a two dimensional seepage flow in front of a single sheet pile wall, whereas AXSflow is an axisymmetric seepage flow.

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Pipeline formed with flexible joints is able to apply the curved jointed pipes to bend, where the bend angle is moderate. This curved pipeline with several joints can improve a restricted design and reduce a construction cost by omission of bend pipe. The thrust force generated by internal pressure tends to move the bend of underground pipeline to the back side. However, the behavior of curved pipes and joints is not readily known when this thrust force acts on bend, so application of this method to site is still limited.
In this paper, pit tests were conducted, using a model pipes having a diameter of 250mm acting on internal pressure repetitively, to compare bend pipe to curved jointed pipes in the same bend angle.
As a result, displacement of curved jointed pipes due to thrust force was smaller, and movement of each joint was more even than bend pipe. And resistant soil pressure was widely distributed more than bend pipe. Moreover, it was clarified that current design standard was applicable at the curved pipeline as well as bend pipe. In addition, it was confirmed that the numerical simulation modeled by shell and spring elements agreed well with the experiment acting on internal pressure to bend.

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There is growing interest in the protection of the natural environment and ecosystem, better landscaping, and multifunctionality of agriculture and rural areas. The interest has been expanding stakes in agriculture and rural areas, which, in turn, has been changing the nature of planning administration. Under these circumstances, we need to involve various stakeholders more than ever to deliberate issues at stake and to build consensus among them. In order for us to choose appropriate stakeholders who take part in planning process in an appropriate manner, we need to clarify bases for the participatory planning process. In this study, through reviews of previous research and literature, especially in the field of administrative laws, the authors clarified three critical ideas that underlie participatory planning: 1) to control the discretionary power of the government in the planning process, 2) to protect the rights and interests of the stakeholders and 3) to improve democratic decision making in the planning process.

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We find sometimes natural waterway with the vegetations. Vegetations play a major role in the ecological environment. On the other hand, vegetations are also the flow resistance. So it is important to estimate the flow resistance for the design of a vegetated waterway. At present, the vegetative resistance is calculated by using the fixed Manning roughness coefficient. However, that method cannot evaluate the vegetative resistance correctly. This research proposed the new Manning roughness coefficient of open channel flow with submerged vegetations from the velocity distribution of the flow. The validity of the new Manning roughness coefficient was verified by the comparison with the experiment.

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A feedback artificial neural network model (FBANNM) was applied to the real-time prediction of dissolved oxygen (DO) in an eutrophic lake. The results obtained from an ordinary FBANNM showed that prediction accuracy and possible prediction lead-time varied season by season. In particular, prediction accuracy during summer was relatively low, and the model could only predict variation of DO with two-hour lead-time. To improve prediction accuracy and extend possible prediction lead-time, processing for noise elimination based on wavelet analysis was introduced to the FBANNM. In the processing, the DO time series was divided into low and high frequency components, while noise was eliminated from the high frequency component. Using low and high frequency components, FBANNM was constructed to consider the time-frequency characteristics. Reconstructed FBANNM showed remarkable improvement in both prediction accuracy and possible prediction lead-time. Furthermore, parameters representing the strength of lake stratification were incorporated into the input variables of the model. As a result, prediction accuracy and possible prediction lead-time were scarcely improved. It is therefore concluded that DO can only be sufficiently predicted by using its past time-series.

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The reduction in farmland area associated with the increased number of abandoned paddy fields in Japan today has expanded the instability of the relation between long-term food supply and demand. As a solution to this problem, the authors have proposed an extensive management program for abandoned paddy fields in order to maintain them in a condition to be reused at any time. In this study, in order to evaluate from an economic viewpoint the validity of extensive management of wet farm land-something that was not examined in our previous research-we modeled the aging characteristics of restoration costs for abandoned paddy fields based on case research. Research was conducted in the Oshima area of Kashiwazaki-shi, Niigata, which is a snow coverage zone. As a result, the following points were clarified.(1) In wet farm lands as well as dry ones, the distribution of restoration cost of abandoned paddy fields can correspond to a logistic curve.(2) The restoration cost for abandoned paddy fields and the aggregate total restoration cost follow almost similar aging patterns in wet farm lands and dry ones.(3) The management expenses tend to be lower for wet farm lands than for dry ones.

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The present study performed to investigate the changes of weather, planting pattern and water amount used at zone level for five years of 2000-2004 and to find the actual condition of water utilization from the correlation between those changes in open ordinary field irrigation zone, as a study case, in Hokuso-toubu irrigation project area, Chiba prefecture, where the field irrigation system had been applied for 25 years. And the nice condition of available moisture for normal growth and the appropriateness of elements for irrigation design in this study zone were verified by judging the five years changes of TRAM remainder at zone level computed under irrigation and non-irrigation. Consequently, the suitability to the open ordinary field zone of irrigation design of our country as well as this study zone was verified, too.

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The fundamental and the mechanical characteristics of the dredged sludge cakes are investigated to reuse the cakes. As an experimental material, the dredged sludge cakes of Kojima Lake in Okayama are used here. Considering the case the sludge cakes are used as an embankment material, the compaction effect of the cakes on the permeability and the compressibility is clarified. Then, since there is the possibility that the dredged sludge is used with the dry state, the effect of the desiccation on the physical and mechanical properties is investigated here. According to the results, the compaction of sludge cakes makes the permeability reduce effectively, and the desiccation dramatically increases the permeability. Furthermore, the unconfined compression strengths of the sludge stabilized with cement are compared. The functional relationship is recognized between the water content and the unconfined compression strength. In comparison between the specimens made from wet and desiccated sludges, higher strength is obtained from the latter one.

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The relationships between arsenic content and physical and chemical properties of soil at an arsenic contaminated region in Nepal were investigated. Arsenic content exceeding 150mg/kg was not detected in soils of agricultural land. In this case, it was found out that greater arsenic content occurred concomitantly with soils having higher cation exchange capacity. In boring core samples, accumulated arsenic content exceeding 150mg/kg was detected in the black-colored peat layer found at a depth of 10-11m. It was assumed that the arsenic which was originally contained in this layer could easily leach into groundwater as a result of activity of microorganisms etc. In addition, it was also found out that greater arsenic content occurred concomitantly with boring core samples having higher clay content, pH and cation exchange capacity.

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Farmers' consciousness of an upland irrigation project in the Nansatsu district of Kagoshima prefecture were investigated for the administration to obtain basic knowledge to build consensus for an upland irrigation project. A questionnaire survey was conducted to single crop farmers as well as to settlements classified by farming pattern, and characteristics and problems of the farmers' consciousness. The results are as follows.
The farmers of tea growing or protected horticulture place importance on profitability and workability. They aspire to a positive farming with expectation the irrigation effect. Meanwhile, the farmers of growing manufacturing sweet potato have a low importance on the irrigation effect. They aspire to a conservative farming based on a traditional crop. In the category of open field vegetables, the farmers occupy an intermediate position between positive and conservative. In the promotion of a water management association, therefore, it is important for understanding and discussing of the farmers' consciousness among settlements.

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