The basis of reasonable grid design for water hammer analysis using the method of characteristics is given by clarifying theoretically and numerically the actual error characteristics due to the time-line interpolations and the effect of the boundaries on that error. The theoretical expressions of the errors already known are discussed for the linear valve closure problems in the simple piping systems. In applying the reachback time-line interpolations (RTLI), the theoretical predictions of the numerical damping are valid even in only calculations at boundary grids. With the predictions, the time-step sizes can be determined by the RTLI for a given allowable numerical damping rate. Though the implicit time-line interpolations (ITLI) cause the rapid amplitude damping of waves of time-scales inherent to relatively short pipesÅC the time-step sizes are large enough to justify the rigid column approximations in pipelines. The method combined with the ITLI and RTLI is modified to employ larger the time step sizes.

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The methods, in which the cross sections of the flow were divided into several regions, have been applied for prediction in distribution of velocity and water level in a compound sectional channel and a regular cross-sectional channel with locally varied resistance zone. In this paper the resistance zone is assumed to be composed of pile series arranged like vegetation belt or rough stone zone. In the previous methods, lateral distribution of velocity was estimated on the basis of the assumption of uniform flow condition. But the assumption cannot be applied to calculation of non-uniform flow. Because the assumption implies that lateral distribution of velocity has a similar shape in all cross section of overall flow region in spite of non-uniform flow. We give the proof of the above mention and propose a new calculation method for prediction of velocity distribution, in which the assumption of uniformflow condition is not used. Longitudinal water level can be predicted by using the velocity and energy gradient obtained from the calculation of velocity distribution. This calculation method of longitudinal water level will be also made clear in this paper.
The applicability of this calculation method is assured by the results obtained from the experiments in the regular cross-sectional channel and the compound sectional channel with pile zone on the several conditions.

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We examined the nitrification capability and nitrogen removal ability for the contact aeration process using a small experimental apparatus (70 l·d ^-1) where the aeration tanks were placed before the anaerobic tanks. In contrast, the anaerobic tanks were placed before the aeration tanks. The results showed nitrogen removal of effluent T-N concentrations of less than 10mg·l ^-1 was observed. It often, however, being studied that the same results can not be obtained when the size of the treatment plant changes from small to large in the waste treatment process. We have already constructed a pilot plant (8.3m³·d ^-1) at the Maebashi municipal treatment center which uses the JARUS IV contact aeration process. We rearranged the pilot plant in a same way as the small experimental apparatus. Although, we could not examine the treatment conditions in winter because raw sewarage did not flow due to the reconstruction of the Maebashi municipal treatment plants, we observed good T-N removal results when the water temperature was 19°C25°C from May to August, 1997. An average T-N concentration of 5.4mg·l ^-1 was obtained during the experiment. In addition, the average removal of T-N concentrations in the anaerobic tanks was 3.5mg·l ^-1. Therefore, we estimate that T-N concentrations less than 10mg·l ^-1 in treated water may be obtained without anaerobic tanks if treatment conditions are the same when the water temperature is approximately 16°C.

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When radiation in a basin is calculated, slope inclimtion, slope orientation and topography of surraindings hive to be taken into accaint. The method of approximation to topography by triargles proposed by Miura et al. is Employed to take slope characteristics and topography of surraindings into account.
Authors Trepared 360 directions' shades altitudes, L e. every degree of angle, for each triangle in advance, and used these shades' altitudes to calculate both direct radiation on a slope diffuse radiation taldrg topcgraphy of surroundings into accant. And authors show kw to estimate Iturly direct arxi diffuse solar radiation from hourly horizontal global radiation and synthesize hurly, slope global radiation on slopes.

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In the cultivated land, generally, groundwater moves in all direction. Howevernormally, we ignore one direction and approximate that condition to 2-dimensions. In case, there is springwater in the cultivated land, water table is almost always 3-dimensional. In this paper, we have analyzedthe pipe drainage effect for spring water control with a 3-Dimensional Sand Model Experiment depending onrelative installation. The results obtained are summarized as follows:
(1) Y-direction length ratio (Drain interval) of pipe drain significantly affectsthe groundwater table.
(2) In case the X-direction installation ratio (Drain interval) changes from 0.5 to1.0 and the Y-direction ratio (Drain length) changes from 0.8 to 0.6, water table will raise rapidly.
(3) Under the condition that the X-direction installation ratio is 0-0.5 and theY-direction installation ratio is 0.6-0.8, mean groundwater level nearly equal the case of the pipe draininstalled right above the spring

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This research was carried out to develop a method of evaluating conditions in agricultural regions from three perspectives: agricultural productivity, socio-economic conditions, and preservation of the water quality environment. Principal component analysis using 24 indices in prefectural units was carried out to quantitatively evaluate relationships between these three perspectives. And this model was used to perform a time series regional evaluation taking two upland field areas as objects of a case study. As a results, it was possible to clarify the way that the relationships between these changed over time in the two areas. Although some of the indices must be improved in the future, the study has shown that it is possible to objectively understand conditions in various agricultural regions and to study policies for the future conduct of agricultural improvement and rural development using an evaluation method of this kind.

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The critical coagulation concentration (CCC) of pure allophane, an amphoteric colloid, was measured for different electrolytes and pHs. The CCC of monovalent electrolytes under alkaline conditions was Na⁺ > K⁺>NH₄⁺ for cations corresponding to the hydrated radii of cations in water. The sante relationship was noted for anions under alkaline conditions in which NO₃^- > Cl^-. Allophane coagulated under divalent counter-ions, i.e., Ca²⁺, Mg ²⁺ at a higher pH, and SO₄^2- at a lower pH. The CCC was essentially the same regardless of the species or the valence of the co-ions. The CCC of non-deferrated allophane was higher under acidic conditions and lower under alkaline conditions compared to that of deferrated allophane according to the difference in the point of zero net charge of each allophane. The CCC estimated by the DLVO theory, assuming the domain size of dispersed allophane to be 100-500 nm, showed good agreement with that measured for NaCl.

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Direct runoff, which disappears in few days after a storm, was separated to discuss relationships between retention, total rainfall and soil moisture deficit in three experimental catchments of different types of land use. It was concluded that the effect of initial soil moisture condition on the retention could be evaluated quantitatively by the deficit and different properties of the retention were found among the catchments. A water budget concept was applied to investigate a property of percolation as rainfall loss during a storm. Linear relationships were found between duration time and the amount of percolation and it was revealed that the intensity of percolation is dependent on properties of soils and bed rocks and types of land use in the catchments.

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Generally, it is difficult to read the ultimate bearing capacity of flexible batter piles under horizontal loads from load Q-deflection Y curves. Manoppo et. al has been done in case of single flexible batter piles in sand under horizontal loads for determining the ultimate bearing capacity by using the fitting method.
In continuation of the previous investigation the present paper is presented the fitting method for the calculation of the ultimate bearing capacity of single batter pile driven into clay under lateral loads and its applicability is discussed experimentally. Model experiments were carried out using flexible piles of wide-ranging flexibilities.
The piles were pushed into clay at batter angle β=0°, ±15°, ±30° and were subjected to incrementally increasing lateral loads.
The present theory of ultimate bearing capacity was found in reasonable agreement with the theory suggested by Meyerhof, G. G. and Ranjan, G.

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The structure of the air entrained flow in a spillway chute is estimated in the framework of an optimal control problem. The specific gravity of air-water mixture is supposed to be governed by a partial differential equation, which includes the diffusion and the convection coefficients. The coefficients are taken as the control variables to minimize a boundary and domain observation type functional which evaluates the error between measured specific gravity and the solution of the governing equation. The minimum principle is deduced to characterize the optimal control variables using the adjoint partial differential equation. Constraints are imposed on the control variables so that the diffusion coefficient and the air bubble rise velocity do not become negative. Further assumption that these two components of the control variables are functions of the specific gravity is made to simplify the optimization process. An iterative numerical procedure using a finite element scheme to solve the partial differential equations is developed. Test runs of the procedure prove that the method is valid enough and can be used for analysis of air entrained flows.

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Rice husk ashes were produced by controlled field burning operations in Thailand. The ashes obtained were pulverized in a ball mill for 60 min and used as a partial cement replacement material in concrete. The heat of hydration of the cement and the adiabatic temperature rise of the concrete containing up to 60 % rice husk ash by weight of the total cementing material were determined. The evolution of hydration heat of the blended cement decreased as the ash content of the cementing material increased. The adiabatic temperature rise of the concretes containing 20% or 40 % rice husk ash was not significantly reduced compared with the control concrete without rice husk ash. The adiabatic temperature rise of the concrete containing 60% rice husk ash was 17°C lower than that of the control concrete. Influences of the heat generation of the concretes on temperature behaviors in a mass concrete structure were also investigated using finite element thermal analysis.

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For studying the characteristics of a current water wheel to convert flow energy in an irrigation canal into mechanical power, we carried out hydraulic model tests in order to clarify the effect of energy output suchas water wheel output, water wheel efficiency and water surface change, etc.
The test results are summarized as follows;
1) the water level upstream of the water wheel increased as the load (or weight) increased and after the water wheel reached a maximum efficiency of 0.45; as the load increased, efficiency decreased.
2) the water level downstream of the water wheel was running high caused by the set water wheel and its flow profile related to the Froude number.
3) maximum output occurred when the peripheral speed was 45% of velocity.

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Land degradation is a serious problem which is advancing rapidly in Latin America, threatening agricultural productivity, physical infrastructure and economic conditions, as a result of deforestation, agricultural activities, over-grazing, and overexploitation. The regional FAO Project “Support for Agriculture through Land Conservation and Rehabilitation in Latin America”, financed by Japan, has been working on the acquisition of information on types, causes, degree and seriousness of land degradation, as well as on the dissemination of successful participatory planning approaches to achieve sustainable agricultural development. The Project adopted the concept of “Integrated Land Management”, which elicits the participation of farmers in every step of the planning of a programme, and which accepts socio-economic factors as keyfactors to solve land degradation problems together with the farmers. This paper is a proposal of framework of Integrated Land Management programme, which emphasizes the participatory planning approach.

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In the Mu Us Shamo desert in Inner Mongolia, China, small-strip border irrigation method is used on sandy fields with high hydraulic conductivity. The authors investigated application of border irrigation on sandy field in Arid Land Research Center of Tottori University. The authors investigated characteristics of small-strip border irrigation method in Mu Us shamo desert with the relationship between water application efficiency and length of border strip. Considering only deep percolation loss, water application efficiency was found to be small, when runoff loss is not controlled. Considering both deep percolation loss and runoff loss, water application efficiency reached the peak value on a specific length of border strip. This length is thought to be the most suitable length of the border strip for the Mu Us Shamo desert. The lengths of border strip used in the Mu Us Shamo desert fields are close to this suitable value. This is desirable since irrigation time is about 10 minutes. Correct measuring of irrigation time and readjusting the strip are very important.

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In the most of cases, steel pipe (φ=100mm) is used as the bar-screen materials of the Bar-Screen Compound Type Torrent Intake. However, instead of steel pipe, installed iron bar (φ=30mm) can reduce not only the effective length of the bar-screen but also the fall height of the weir. This paper shows the contrast of the hydraulic dimensions between steel pipe and iron bar under the same design conditions. Moreover, through the check on the strength of the bar-screen for boulder stones, the authors clarified that iron bar is more effective for torrent morphology, flow conditions and intake discharge.

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In previous paper, Authors reported the treatment of waste food oil using the cedar chips as a medium in the thermophilic oxic process. In the discussions, the BOD volume (BVL) load was applied as the index showing the load to reactor. But authors wondered if it does not contains the medium in which microbes live. In this study, the new index, BOD medium load (BML) was defined as counting the medium as their homes. Authors tried to investigate the applicability of new index, BOD medium load using the rice hulls as a medium. Furthermore, we discussed the relationships between the BML and kinds of mediums, cedar chips, rice hulls and a mixture of both materials.
The following points were derived from this study. 1) A validity of decomposition rates can be expressed by the BML. Therefore it is found more useful as a management index for the thermophlic oxic process than the BVL. 2) An efficiency decomposition is realized in range of 40-45 gBOD·kg^-1·d^-1 of BML. 3) The mixture of cedar chips and rice hulls is good medium.

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