This paper presents an attempt to determine the best way to use water in dynamicirrigation.
Simulations were carried out using different quantities of water each instance of irrigation (1/3 I₃₀, 2/3 I₃₀ and full irrigation) and different soil textures (sand, sandy loam, loam, and clay) to come to an understanding of the mechanism for saving water.
A dynamic numerical model, based on the consumption-transport-retention of water, was designed so as to compute the diurnal fluctuation of water potential in soil layers and evaporation under various characteristics.
The results are follows.
(1) Because of the suppression of water movement and evaporation at dry and wet stages, the amount of evaporation for one year period decreased more when little water was used for irrigation instead of much and when sandy loam and loam were used more than sand and clay.
(2) The amount of water saved for irrigation was more by the suppression of evaporation than from rainfall regardless of the amount of water used for irrigation and soil texture.
(3) The SMEP (soil moisture extraction pattern) obtained by simulation varied greatly according to the amount of water used for irrigation and soil texture. Therefore, it seems that frequent irrigation using little water would be best.

View full abstract

At the present, water quality and energy expended on water transportation compete with water requirements for irrigation.
Water allotments should be made in reference to a careful consideration first of the water requirements for irrigation. In this paper, a description is made of the CB method used for determining regional water requirements in paddy fields and which has been formulated as a linear optimization problem.
A new method is proposed for determining regional water requirements with reference to water quality and energy consumption.
On the basis of the results of the application of this method to fundamental situations, the effectiveness of a supplementary circulation irrigation system is investigated.

View full abstract

A series of supervised technique is the most common procedure in remote sensing data analysis, and is used at the classification step in the digital land condition mapping system (DLC mapping system).
In this paper, theoretical considerations on various types of supervised techniques are reviewed in search of adequate classifiers (decision criteria) in DLC mapping system.
The following items are discussed;
1) Decision criteria and their similarity index
Prerequisite for similarity index and mutual relationships among these indices
Requirements for applicability of decision criteria
2) Refinement of the multi-dimensional feature space
Principal component analysis for information redundancy
Evaluation of feature space by the separability analysis of categories
Dual effects of canonical analysis

View full abstract

Supervised classification in remote sensing data analysis is accomplished by using decision criteria. Various kinds of decision criteria have been developed and selection of the decision criteria became important in the field of remotely sensed data application.
The five decision criteria which were examined through a case study of land use/cover analysis are: maximum likelihood criteria, linear discriminant function and minimum distance criterea based on three types of enclidean distances. Items discussed are, fulfillment of prerequisites for the decision criteria, evaluation of performance by the decision criteria and discriminatory characteristics of land use/cover categories.
Results of the case study are summarized as follows;
1) It is difficult to achieve all prerequisites for the decision criteria in practice and it is better to assume that those decision criteria are applied under unsatisfactory conditions.
2) Under imperfect conditions, decision criteria having less number of estimation-parameter will give better classification results.
3) Simple euclidean distances criteria turns out to be the best in the classification of land use/cover by using airborne MSS data.

View full abstract

The analyses of longitudinal model fill dams with a culvert-type inspection gallery were conducted using a nonlinear finite element procedure for analysis of embankments during construction and of ‘No-tension’ material. Stress and deformation characteristics are discussed varying the valley configurations and material properties of the fill and foundation. As a result of these analyses, the following conclusions were obtained:
(1) The effect of concrete joints in the gallery can be introduced into the finite element analysis by the procedure for analysis of ‘No-tension’ material.
(2) The stress and deformation characteristics of the model dams are significantly effected by the variation of the length of horizontal part of the gallery and of the material property of the foundation. Especially, the vertical displacement of the gallery is effected by the material properties to the extent of a deeper foundation, and extension strain of concrete joints by ones to the extent of a shallower foundation.
(3) From these analytical results, the simplified relations are reduced for estimation of maximum vertical displacement and maximum extension strain of the gallery, without a FEM analysis. These relations are suggested for the preliminary design of the fill dam gallery.

View full abstract

In Miyama dam (facing-type rock fill dam; height: 75.5 m; length of crest: 333.8m; volume: 1, 967, 000m³), various measuring instruments were installed in order to obtain information for administration of dam performance and for development of dam engineering. In this investigation, static measuring data of leakage volume, uplift pressure, settlement of the crest, perfomance of inspection gallery, etc. were analyzed in detail, and the following conclusions were obtained:
(1) Leakage volume showed a tendency to decrease year by year to 200 1/min for the high water level and 100 1/min for the water level.
(2) Uplift pressure showed a tendency to converge a constant value.
(3) Horizontal displacement and settlement of the crest showed a tendency to increase year by year, but both displacement and settlement after 100 years are estimated to have very small 1: ralues
(4) Performance of inspection gallery corresponded to normal performance of the dam subjected to water pressure.
As a result of this investigation, various information for the design and investigation of dams was obtained with regard to the performance of the facing-type rockfill dam.

View full abstract

Since the 1977, active observation has been conducted on Miyamadamo which is 75.5m high and the most representative rock-fill dam with a asphalt-facing in Japan. The purpose of the present study is to investigate the dynamic potential of Miyama dam while static potential has been clarified in the companion paper.
As for the dynamic responses, not less than 51 earthquakes were prominent around this dam site over the past several years. The observed data were analyzed, in this study, numerically in the time and frequency domain, with all the fundamental dynamic characteristics of the dam being shown and discussed first.
Some of the observed data were compared again with the responses calculated by 2-D FEM, in which the dynamic material properties estimated from the observed response acceleration records by the identification method were used.
Reasonable agreement between the observed and calculated response has finally encouraged the authors to do a numerical simulation of the dynamic response for stronger earthquakes. The results obtained from the numerical simulation suggest that Miyama dam may possibly be sufficiently strong enough from the dynamic point of view.

View full abstract

This paper presents the test results of the liquid and plastic limits and the fall cone test for non-swelling kaolinite soil which was carried out by varying the kinds of adsorbing cations and the salt concentration in pore water.
The results are as follows:
1. It was confirmed experimentally that both the flow curve and the penetration curve have polygonal forms. The water content by weight of the breaking point of both the curves were in agreement with each other.
2. We considered the breaking point, flow index and penetration index in relation to the volume concentration φ relative to the cone bearing capacity σ(φ-log σ curve). As a result, the breaking point of the curve was found to be in agreement with the point in which the cone bearing capacity (the parameter of yield value) did not change continuously. Also, the flow index and the penetration index mean that the ratio of change in yield value changes with the constant moisture content.
3. The water content by weight, with a lower salt concentration of kaolinite soil showed a larger value than that of the higher salt concentration under the LL test (the same number of blows) and FCtest (the same amount of penetration). Also, when we compared the salt concentrations which were nearly equal to each other, the water content by weight of the Na-kaolinite soil was larger than those of the Ca-kaolinite soil. This fact can be explained mechanically in that the larger cone bearing capacity of the kaolinite soil could be seen at a lower salt concentration or the kaolinite soil adsorbed Na⁺ ion when compared to the kaolinite soil at the higher salt concentration or the kaolinite soil adsorbed Ca⁺⁺ ion under the same volume concentration (the same water content by weight).
4. The flow index and the penetration index of Ca-kaolinite and 2.5 N Na-kaolinite were smaller than 0.33 N and 0.17 N Na-kaolinite. This means that the change in the strength of Ca-kaolinite and 2.5 N Na-kaolinite reacted m are sharply to the change in the constant moisture content.
5. When the moisture content approached PL, the influence on the cations and salt concentrationwas shown to be less.

View full abstract

The correlation time and activational motion energy of absorbed water molecules in Kaolinite and Allophane clay were experimentally calculated using a. broad line N. M. R. spectra of protons.
(1) The correlation time decreased as the temperature dropped, its values were 6.0×10^-4-1.0×10^-3sec for Allophane clay and 4.0×10^-4-1.0×10^-3 sec for Kaolinite clay (Figs. 1 and 4).
(2) The activational motion energy in the absorbed water molecule was the diffrence between the high and low temperatures (Figs. 6 and 7). It indicates the diffrence in the motional stages in the absorbed water molecules during high and low temperures.

View full abstract