For the sake of developing a finite element method, it has been easy to carry out a saturated-unsaturated seepage analysis. However, permeable properties in saturated zone and unsaturated zone have to be known. To know the permeable property in a saturated zone is less of a problem than to know permeable properties in an unsaturated zone. However, to find out the permeable property in a saturated zone has many problems because of the uncertainties involved in measuring, designing and construction. To know permeable properties in an unsaturated zone have a great deal more uncertainties.
To consider uncertainties, permeable properties in saturated and unsaturated zone should be defined by the fuzzy sets which have widths and membership value. Also, observational constructions are important in dealing with these uncertainties.
Back analysis, utilizes the fuzzy theory, has been already developed. Back analysis searches for the permeable properties in the saturated and unsaturated zone. The properties sought for are defined by the fuzzy sets.So, saturated-unsaturated seepage analysis which can utilize fuzzy information is needed to perform observational constructions. The analysis is developed here. The developed analysis uses the concept of level sets and the extended principle in the fuzzy theory.
An experiment was performed to denote the validity of the developed analysis. The experiment used two kinds of glass beads. Two layers are made by the beads. The permeable properties of the beads are obtained by the back analysis utilizing the fuzzy theory. The seepage experiment was performed through the layers. The experimental results were compared with the results computed by the developed analysis. The comparison was in good agreement. This means that the back analysis and seepage analysis developed here are valid.

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The patterns of soil detachment by the impact of water drops have three steps as time elapsed following the development of a underwater cavity. In the first step (process I), soil particles are detached and pushed out following the expansion of a cavity. In the second step (process II), soil particles are lifted up and suspended in the water by the force of hydraulic negative pressure generated by cavity contraction, and the final step (process III) was that the soil particles which have been lifted up by the force of process II settling in the water.
In this paper, at first, the model of detachment by process II was proposed based on the idea that soil particles begin to detach if hydraulic negative pressure impulse (I_ =∫Δpδt) exceed limit valueI₀ which depends on the physical properties of soil, and the total volume of detached particles is proportional to the integrated value of the difference between pressure impulse I_ and I₀ all over the soil surface. This model shows that the total detached volume of soil particles is related to the physical property of soil, impact energy and water depth.
Subsequently, the volume of transported soil particles by rain flow was obtained on the basis of the theoretical consideration of soil detachment by the impact of water drops, assuming that the suspended soil particles in the water cannot be interfered with by the impact of other water drops. The total volume of transported soil can be simply expressed in terms of the following parameters: the rain-drop energy, water depth, mean velocity of surface flow and diameter of soil particles. However, the equation of this model can not be transformed into a non-dimensional form only by non-dimensional tractive force ψ_r and non-dimensional runoff φ_L following the method used in the wash-out theory of open channel hydraulics, but also by the additional two non-dimensional parameters, Π₁, ψ_s. Here, Π₁, ψ_s mean the non-dimensional detached volume of soil particles and non-dimensional suspension force applied to the soil particles in the water, respectively.

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The hydraulic characteristics and the sediment of rain flow were investigated by applying artificial rainfall on a continuous flow which was not able to move soil particles. In other words, the tractive force of flow was under critical one. Also the relationship among the total mass of transported soil, rain-drop energy, water depth, mean velocity of the surface flow and diameter of the soil particles was observed.
Regarding the experiment at results, the coefficient of friction of the flow was laminar, the runoff of soil particles was generated by the impact of rain drops and it reached to its the maximum values when h/H_max was between 0.4 and 0.6 (where h means the water depth and H_max means the maximum height of cavity, generated by the impact of a water drop) and also increases in proportion to the total energy of the rain drops (=(impact energy) ×(frequency of impact)).
The experimental data could not be transformed into the non-dimensional form only by non-dimensional tractive force Ψ_T and non-dimensional runoff Φ_L because the sediment also depends on impact energy and particle diameter. However, all of the experimental results may be explained by the other non-dimensional quantity φ(=q_s (σ-ρ) gW_d/(U_aIV₀²); q_s: sediment, σ: specific weight of sand particles, U_a: mean velocity of surface flow, I: rainfall intensity, W_d: sedimentation speed, V₀: impact velocity of raindrop), ξ(=d/H_max) and II ₃(=h/H_max).

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In this study, evaluation of the transition between a shallow and deep anchor in dry sand was presented by comparing model tests using finite element analyses. The model tests were performed on a circular anchor (diameter 3, 4, 5 cm) in dense Toyoura sand. Also, these tests covered a range of depth/diameter (h/B) ratios up to 7-8. The FEM analyses, employing a constitutive model for non-associated strain softening elastoplastic material and introducing shear band thickness, were performed.
For range h/B>5, the curves in their relationship between a nondimensional parameter (σ/ρ_d.h) and h/B were approximated by a straight line, and failure circles were not observed to develop on the surface of the sand mass, and the direction of the concentrated zone of the apparent maximum shear strain which were calculated by the FEM analyses were not identical with the direction of experimental observed shear band development. These results differed from results of the range h/B<5. Finally, the transition between shallow and deep anchor was defined by h/B=5.

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Retrospective reasoning was discussed for obtaining the time series of variable source area (VSA) in a terraced sorgo field, which was made by cutting the clay layer andbanking.
At the upside cutting area in the field, it is presumed that most of the groundwater flows slowly and affecting the base component of the runoff discharge or loss component, because the slope of the water head is small. On the other hand, at the downside banking area in the field, most of water must flow quickly in the banking soil on the steep slope on the clay layer. As the area of the big discharge under the ground seem to change according to the water level under the ground around the downside in the field, this area is expressed as VSA in this paper.
It is possible to hypothesis that the vertical flux from/into VSA in this field isthe measured precipitation only. Using this kind of hypothesis for getting vertical flux from/intoVSA easily, it becomes practical to introduce common equations for the characteristic curve method of the kinematic wave model to the analysis of VSA. For this analysis, the precipitation and runoff were measured.
The time series of VSA is shown as a group of the characteristic curves on the distance-time plane. The main procedure for arriving at the time series of VSA is by calculatingthe water depth from the lower end of the field to upside along the characteristic curve. It is expected that the water depth on characteristic curve converge to zero in the field. This point of conversion is the upper boundry of VSA.
For obtaining the reasonable time series of VSA, selecting the direct component of runoff or exactly determining the parameters are needed.
In the example, one of the time series of VSA given under the proper conditions was reasonable. Even though the rainfall intensity was weaker than 1.5mm/5min, VSA got larger so long as it was rain. The area of VSA to which the rainfall intensity was strongest was not largest.

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The design of reinforced concrete members is generally realized by comparing the member force at a specified section with its capacity (section check).
However, reinforced concrete members consist of concrete and reinforcing bars, andmoreover, the point of application of the internal force varies with the magnitude of the applied load. Also, the point of application of the resisting force varies with the generation of cracks or reinforcement yield.
The rational and economical design of the member is possible when the member capacity is estimated not only by the information of stress-strain distribution at a specified section but also by the bearing capacity of the whole member. We still do not have enough information on reinforced concrete member as a composite member, however, we can only get knowledge through experiments or precise analysis for special cases.
In this paper a loading test for various shapes of deep beem specimens was carried out with the shear span ratio being 1.0, and investigated their mechanical behavior. Moreover, the test results of a model are verified by FEM analysis. Based on these tests and analysis, the problems involved in estimating the bearing capasity of deep beams are discussed and solved.

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The change in moisture content of soil was predicted using the SMD (soil moisture deficit) model which is based on gross simplification of the real water consumption system. This model is characterized in adopting different regulating functions relating to actual to potential evaporation via the moisture condition of the soil. The data required to operate this model are a timescale of one day data, which can be easily obtained. A SPAC (soil plant atmosphere continuum) model was used to clarify the theoretical bases of the assumptions adopted in the SMD model.
The results are summarized as follows:(1) capilally rise effect can be included in the regulating functions as well as evapotranspiration effect;(2) soil water can be separated into various levels from the viewpoint of a different possible mechanism of root absorption ;(3) the functions once determined can be used repeatedly while the field conditions are unchanged ; and (4) the soil moisture deficit curves produced by the SMD model are in good agreement with the calculated curves of the SPAC model.

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The very little amount of super-water absorbent polymer and the Toyoura standard sand are mixed. The mixed samples of several moisture contents were placed in sealed vessels and then were incubated under the constant temperature gradient for various 1-6 days. Change in the distribution of the soil moisture content by the elapse of time (day) was investigated.
The difference of the distribution of the moisture content was observed distinguishably, between the sand soils with and without the polymer. Namely, in case of the sand soil without polymer, independently on the elapse of time, that is, the tendency of the continuously increasing moisture content from high to low temperature side was observed. On the other hand, in case of the sand soil with the polymer, the tendency of the distribution of the moisture content having wavecurves with both of a maximum limited point and a minimum limited point in the intermediate area.
From the thinking of peculiarity of the moisture distribution in the mixed soil, the phenomenological enhancement factor β of water vapor diffusion in soil resulting from a temperature gradient was calculated. As the results, the pattern of the enhancement factor β vs.saturation curve of the mixed sand soil was rather smaller than that of the Lysimeter sand by Cass et al.(1984).
It can be said that the water transfer in the mixed sand of nonsaturated resulting from a temperature gradint is occupied mostly by not liquid but water vapor diffusion.

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The fundamental disadvantage of the unsteady flow model is that the computer simulation required demands much labor and is time consuming, however much the actual complicated drainage channel network is simplified. As the water level of drainage channels changes very slowly due to a backwater effect in a low-lying drainage basin, the unsteady flow in the channel can be simplified to a non-uniform flow.
This paper proposes the diffusive tank model and discusses several fundamental problems in order to apply its model to flood routing in a low-lying drainage basin.
The results are summarized as follows:
1) The diffusive tank model is a quasi-hydraulic model concentrating on the continuity relationship among the storage, the inflow and outflow and deals with a flood wave motion as the diffusion wave.
2) The results of flood routing analysis show a good coincidence with simulated hydrographs by the unsteady flow model. The diffusive tank model has the great advantage of its computer simulation time being only sixteen percent that of the unsteady flow model.
3) From the viewpoint of engineering practice, the authors discussed separately what criteria should be adopted for simplifying the complicated drainage channel network with the gravitational drainage and the pumping activities system. As a result, it was found that the channel network system could be reduced to a second-order channel system. If each subdrainage area in which rainwater flows into a branch channel is roughly equal to each other, then, the flow capacity of a lumped and abbreviated branch channel may hopefully be included in that of the lumping branch channel.

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Firstly, this paper discusses the efficiency of drainage pumps, water balance of flood runoff and characteristics of rainwater retention at the Gedan zone of low land of 18.7 km2 containing reclaimed land of 10.8 km² in the Ogura basin of 52 km² situated south of Kyoto City.
Secondly, flood runoff analysis by applying the diffusive tank model is performed for heavy rain storms in July, 1972, and the applicability of the model is discussed.
The results are summarized as follows:
1) The approximate efficiency of drainage pumps did not change six years after their installation. but fairly decreased after about 20 to 40 years.
2) The inflow water to the low land consisted of not only rainwater but also the seepage water from river embankments, the leakage from intake gate and sewage from urban areas. As the amount of these inflows except for rainwater come up to a fair quantity according to the magnitude of the flood, it is necessary to check the water balance for the duration of the flood routing.
3) The maximum value of retention of paddy field areas of Gedan zone in the Ogura basin was 34 mm during the irrigation period of June and July.
4) The results of flood routing analysis disclosed that the channel network systems are able to be reduced to a second-order channel system, that is termed “paddy field lots-branch channels-main channel” system and this verifies the usefulness of this simplifying methodology. The parameters of the tank can be estimated completely from the geometry of the drainage channel and paddy fields.

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The study basin (60.8 km²) is a low-lying paddy field area which is located on the right side of the Shin river and enclosed by four rivers. This basin has complicated drainage channel networks as follows. The rain water is drained into different rivers by the pumps at five drainage pump stations. These pumping stations are linked to each other by several main channels. Moreover, there are two small polders from which rain water is separately drained intotwo main channels using pumps and there are two water gates at these main channels.
This basin suffered heavy rainfall of about 320mm in total from June 25 th to 27th, 1978. Locally there were areas inundated for over 3 days. This paper discusses runoff analysis of this flood using the diffusive tank model.
The results are summarized as follows:
1) As a result of investigating the water balance, total percolation of embankment of rivers and levees was 51.3 mm and the maximum retention of paddy fields was 31 mm.
2) Since the water gate and pump of the small polder affect strongly the behavior of runoff water, it is necessary to modelize not only the operations of these drainage pumpsbut also the functions of hydraulic divisions such as the water gates as precisely as possible.
3) The results of flood routing analysis show a good coincidence with observed hydrographs and verify the usefulness of the methodology by which the complicated drainage channelnetworks can be modeled by a second-order channel system.

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This paper emphasizes the role of wedge storage on runoff simulation by astorage function model. The wedge storage is defined as rainwater storage necessary to form a thin sheet flow over a slope with rough surface and weeds. The content is summarized as follows:
First, the relationships of storage, outflow discharge and the time of concentration are discussed theoretically based on the kinematic wave model and phenomenally using the experimental data. The results indicate that the model parameter cannot keep constant to simulate outflow hydrograph and that it is necessary to consider the form process of wedge storage and change model parameters for the flow pattern to explain the runoff phenomena.
Second, the time dependence of parameter of Prasad's model is discussed using the experimental data.
After examining an expedient method to modify the storage function model, finally a new model considering the effects of wedge storage is proposed and good adaptability is shown in the simulation results.

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Rainfall information as a system input is very important to control water systematically by main irrigation and drainage facilities, and its accuracy depends on the suitability of rain gauge networks. Those networks, however, have been set up empirically and techniques of its optimal network design has not yet been developed.
The aim of this paper is to examine the optimal selection of rain gauge stations by applying the Kriging theory to spatial rainfall patterns in basins.
Three basins were selected and heavy rainfall events were used to determine the pattern of variograms for the watershed concerned. The Kriging theory was then applied to estimate the weight of each gauge location, which was, in turn, used to calculate the areal rainfall. Finally, the theory was applied to determine the variance of the rainfall estimate at each rain gauge station. The method thus applied proved useful to provide the following information for the design of rain gauge networks:
1. The major rain gauge station is selected successively out of all stations, based on numerically evaluated values. Hypothetical points can be included in it. The index obtained can be used for the inclusion or elimination of gauge stations.
2. When priority of investment for rain gauges, such as equipment of telemetric system, is considered, the above method guides us in deciding which combination of gauge stations should be selected. The combination number (n) of gauges can be chosen arbitrarily.
3. In installing a new gauge station, the correction of error is evaluated by moving a newly added hypothetical point in the basin, and the equi-line of its correction is drawn to specify the points.

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Rainfall, soil loss and surface runoff were observed using a slope lysimeter at the Agricultural Experiment Farm at Hokkaido University (Sapporo) in 1989. A correlation between soil loss and the EI value caused by intervals of rainfall observations, duration of peak rainfall intensity and definition of erosive rainfall to soil loss were studied. The following results were obtained
1) 19 events within 36 rainfalls with erosion were smaller than 12.7 mm, and 16 events were smaller than 10 mm. In addition, soil loss caused by these rainfalls were 8.0 and 4.4% respectively to that caused by all rainfalls.
2) Mutual relationship between soil loss and intensity of peak rainfall was estimated and the correlation coefficient was increased due to a reduction in the interval to observation.
3) Soil loss with 17 erosive rainfalls of USLE was 92% to that caused by all 36 rainfalls with erosion.
4) The relationship between soil loss and the EI values of different durations of peak rainfall intensity were analyzed. It was proven that the shorter the duration of peak rainfall, the higher the correlation between soil loss and the EI value.
5) There is a close relationship not only between soil loss and the EI value, but also between surface runoff and EI.
6) EI value calculated by 60-min interval rainfall data was 32% smaller than that by the 10-min interval, and mutual relationship was estimated between both the EI values.

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The fundamental properties of concrete to acid were examined in this paper. Dipping test pieces was examined using some kinds of solutions prepared in various concentrations of sulfuric acid and nitric acid, i.e., pH1, 2, 3, 4, 5.
The results obtained are as follows:
It was verified that a pH of 3-2 is a transition pH between acid-proof and non-acid-proof. Although the average pH of acid rainfall is about 4.5 in Japan, it was shown definitely by this study that the influence of acid rain on the deterioration of concrete was not so remarkable. Though the hanging piece of concrete like an icicle is a well-known phenomenon in conection with the deterioration of concrete, it is considered that its influence regarding the deterioration of concrete is not so strong. Considering the results of Ca²⁺ analysis and X-rays diffraction of test pieces, the deterioration of concrete by an acid solution did not occur so quickly for a pH or less than 3. Furthermore, as regards an in-the-field survey, the actual condition of the deterioration of concrete was investigated at a river where acid water flows.

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