In consideration of life history of fishes, it is necessary to investigate the fish habitat structure not only in main rivers but also in various scales of tributaries and drainage channels connected them. Weirs and abrupt drops in river system could be discontinuity points which divide fish habitats, obstructing fish migration along river channels. Hence, we conducted a field investigation of the environmental characteristics in the Ijira river, a tributary of the Nagara river, and proposed an index expressing the difficulties in runs of fish prevented by these discontinuity points. Evaluating this index and the grade of three type of vegetation covers and introducing these values into a GIS, we showed tentative evaluation maps for fish habitat quality in the Ijira river.

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A report about microorganisms adhered to a river bed in the spring and the summer seasons run on Japanese Journal of Water Treatment Biology, Vol, 29, No.1 (1993) .This time microorganisms adhered to river bed were investigated during the autumn and the winter seasons at every points. A cycle of a year about microorganisms adhered to river bed was round off.The dominant species of the microorganisms adhered to the river bed were also investigated separately.The saprobity in the surface water in terms of saprobic index of the species was following;
autumn winter
Points 1, 2, 4, 6 1, 2, 3, 4, 8 : oligo-saprobity s=1.0±0.5
Points 3, 5, 8, 9, 10, 12 5, 6, 7, 9, 11, 12 : β-meso-saprobity s=2.0±0.5
Points 7, 11 10 : α-meso-saprobity s=3.0±0.5
About 10 species were observed at every points in the four seasons. At the same time, discript the result of the investigation on microorganisms quantities. Microorganisms indicate the past career of water quality for a fairly long time. But because of the differences in temperature, environment of a river bed, the water current and the time of the year the dominant species assume a different aspect. So a deeper understanding of the water environment is the best measure to prevent water pollution. Needless to say, the origin of water pollution should be managed and controlled. Cleaning and putting a river side in good condition is very important. And is necessary to care for the change of a river bed by bridging work.

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The collaboration among administrator, citizens and specialists is needed to approach stream environmental management in Japan. The society's attitude towards streams has changed from flood control and effective utilization of water resources to restoration of biological conditions. In this study, we conclude that biomonitoring based on indicator biology and habitat diversity index such as MILFm97 and HIMm98 effectively assesses the whole aspects of stream environment.

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Microorganisms adhered to river bed were investigated during the spring and the summer seasons. In the spring season, investigation of the water quality was carried out with chemical methods. At the same time, the dominant species of the microorganisms adhered to the river bed were also investigated separately The saprobity in the surface water in terms of saprobic index of the species was following;
Points (1) - (4), (6) and (7) : oligo-saprobity, S=1.0±0.5
Points (5), (8) - (10) : β-meso-saprobity, S=2.0±0.5
Points (11), (12) : α-meso-saprobity, S=3.0±0.5
During the summers, the microorganisms adhered to the river bed at the same points was investigated. About 10 species were observed at every point. This method of deciding the quality of the water with respect to species is quicker and more economical than the chemical method; Microorganisms indicate the past career of water quality for a fairly long time. But because of the differences in temperature, environment of a river bed and the water current, the dominant species assume a different aspect. So a deeper understanding of the water environment is the best measure to prevent water pollution. Needless to say, the origin of water pollution should be managed and controlled. By avoiding disposal of scrap materials into a river side and burning of plants, which thickly grow up in a dry river in winters, we can probably attain our purpose by reducing water pollution more than 10 %

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Lake Narutaki dam is situated in the Kibi Plateau, middle of the smooth hilly regions of Okayama prefecture. This dam has special water quality problems as it supplies city water. These problems are; (1) Coloring is caused by dissolved Mn and Fe from the bottom of the lake where oxygen is almost decreased to zero, (2) A nasty smell and bad taste of city water is originated from vegatative planktons. Therefore, the investigation into the actual condition of this lake was carried out from June to December of 1991. Mn and Fe were always found to be dissolved at the bottom of the lake in high concentration. In the middle of the lake, Fe concentration decreased but Mn had almost the same concentration as that of the bottom. At the surface of the lake, Fe concentration was 0.1-0.3 mg/L while Mn concentration was 0.02-0.4 mg/L. The vertical profile of the vegetative plankton in the water made no great difference until 4 m depth, but it radically decreased in deeper places more than 6 m depth. The following treatment methods are proposed from these data; (1) In order to avoid the influence and transport of Fe and Mn in the filter and subsequent back washing, the income pipe position should be varied in depth according to the season, (2) Longer contact with manganese powder for removing the color and prolonged contact with charcoal for removing nasty smell and bad taste, (3) Introducing advanced treatment for example Ozone treatment for upgrading the taste. With the use of above treatment methods, the problems are thought to alleviate. However, the measure of the origin of pollution is desirable to protect the water quality of this lake, because water is scarece in this region and the only source of water supply is this dam.

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It is necessary to evaluate the characteristics of river environment for planning river works and for setting an environmental target of preservation and improvement of habitats. Therefore the technique to analyze the relation between the distribution of living things and physical, chemical and biological environments of river habitats is required. In this paper, we presented an integrated water quality index and an integrated river flow type index. The latter was based on results of principal component analysis applied to the factors involved in HIM (Morishita, 1998). The integrated indices were used as criterion variables for a multiple regression analysis of fish data and some indicator species were presented. The multiple regression model was used for the estimation of integrated index values of verification rivers and showed good performance.

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Cephalometric analysis of today is based on a line drawing produced by the expert from an original cephalogram and gives the estimation of measurement patterns through measurement points. This analysis causes some kinds of errors as well as troublesome loads for human experts. In order to cope with these problems, the new idea of fully automatic analysis is presented in this paper.

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近年日本において, 流域環境への影響が危惧される水資源開発を行う際には, 関連するステイクホルダー問の合意形成の基での意思決定が重要課題となってきている. しかし, 地域性や住民意識などが十分に考慮されないまま開発計画が立てられることも少なくない.水資源開発の意思決定においては, 結果よりも結果にいたるプロセスが重要であるとの認識に立ち, 本研究では, その意思決定を行う為のシステム論的なプロセスの提案を行うと共に, その吉野川可動堰問題への適用を行う. そこではまず, ステイクホルダーとして開発推進派と環境保護派を設定し, それらの効用関数を構築する. そして凸依存性を考慮したグループ効用関数を用いて, 開発推進派が環境保護派に対して歩み寄りを進めたときの意思決定について述べる.

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本稿では，「共振」という概念を用い，フィールドワークが何を意味するのかということを探究する。ここでの「共振」とは，調査者とフィールドとの間に成立していると観察される相互関係を指す。それは必ずしも同調ではなく，むしろ多層・多面的に共同構築される現実の政治的な現れ方であり，葛藤・軋轢を経て相互の変容をもたらしたり，あるいはそれらが背景となり現実をつくったりする。 　本稿ではこの概念を利用し，地域の日本語支援現場における筆者自身の体験に基づきながら，（a）フィールドワークの再定義，（b）フィールドワークの過程における自身の変容，（c）フィールドエントリーを通じて見えてきた種々の境界，さらに，（d）フィールドにおける行為者のポジションとその変化に伴う「共振」，について議論する。その上で，フィールドワークというのは集合的な学習経験であり，そのプロセスの中で学習を阻む特定の問題を協働で可視化しているのだということを，事例報告を交えながら示す。

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A countermeasure of preventing the eutrophication of lakes and marshes is to use filamentous algae to remove dissolved phosphorus and nitrogen from the waters of rivers flowing into them. In order to establish a procedure for harvesting filamentous algae growing in artificial waterways and a effective use of the harvested algae, it is necessary to clarify the quantity which can be harvested.
In the waterways, the quantity of algae separated from the substratum which are discharged outside the waterway or which accumulate in the interior of the waterways varies for each harvest. Cosequently, it is possible to predict the harvesting yield of algae which is separated from the substratum as the function of the phosphorus content, phosphorus absorbing ability, and the constant of non-harvesting algae.
The results of calculations based on field experiments with filamentous algae have confirmed that the harvesting yield is dependent upon the water temperature, concentration of nutrient in the raw water, and the stream regime. Typical harvesting yield values were obtained. When we treated raw water of dissolved orthophosphate concentration of 30μg·l^-1 at water temperature of 20°C using a gentle-sloped waterway, we found that the harvesting yield was roughly 20g dry weight·m^-2·d^-1.

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The purpose of the study is to evaluate the water quality of rivers from the view point of the human sense by image test of river water. The result indicated 1) The image of “Clear water” has less relation with the value of BOD. 2) The image of “Clear water” has strong relationship with the image of “Transparent”. 3) The image of “Transparent” has strong relationship with “Transparency by cylinder test”, and is explained by “Transparency by cylinder test” and “depth”. 4)“Water color” reflects “Clear water”.
And it's showed that “Transparency by cylinder test” is presumed from the optical absorbance of SS at 610nm, which is percolated with filter papers from river water.

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This paper describes a definition of complexity of questions for a question and answer function in an intelligent support system for English learning, and its evaluation. To realize adaptive question and answer, the system should generates questions depending on both educational intentions and the learner's understanding state. For generating suitable questions for the learner automatically, we must investigate the factors which influence difficulty of questions, and prepare the mechanism to calculate the difficulty. The difficulty is composed of the learner dependent part and the independent part. The former is evaluated by referring to a student model. The latter is defined by enumerating factors which influence complexity of questions. We present a definition of the complexity along with learners' answering flow; understanding text sentences, understanding a question and composing an answer. Moreover, we describe experimentation comparing the complexity of questions calculated by computer according to the definition with the complexity evaluated by human.

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This paper presents the results of an objective evaluation of the natural environment of the Chino River. River improvements were executed by restoring the fireflies’ natural environment in the new channel. The number of flights of fireflies was almost the same as the number before the river improvements. The observed results suggested that the river improvements had been relatively well executed to conserve the habitat of the firefly. In order to evaluate objectively, the natural environment of the four rivers in the southern part of Miyazaki were classified by the principal component analysis. The analyzed result showed that the natural environment in the new channel was classified in the state influenced by human activity. This result showed the importance of the objective evaluation.

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河川開発と環境保全がトレード・オフの関係にあり，ステイクホルダーの間でコンフリクトが生じている際には，各ステイクホルダーの意思や意向を適切に評価した上で意思決定に結び付けていく必要がある．しかし河川開発代替案の総合評価を行うためには，どうしても河川開発と環境保全といった別次元の利害を突き合わせて評価しなければならない．
そのために本研究では，各ステイクホルダーの意思や意向を表現するための「満足関数」というものを，ステイクホルダー間の整合性を満たした形で構築するための手法の提案を行う．そして，「グループ満足関数」という代替案評価モデルの構築を行うが，これは各ステイクホルダーの満足関数により成り立つ．
そして，このモデルを吉野川可動堰問題に適用した．ここでは，治水と生態系に関するステイクホルダーの満足関数の構築を行い，代替案の評価を行った．また，ステイクホルダー間の歩み寄りを明示的に考慮するために，選好構造差独立性の概念に基づくモデル構築を行ったが，これにより歩み寄りの程度と代替案選択の定量的な関係が得られた．

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全国109の一級河川の魚類相について河川水辺の国勢調査データを用いて統計分析を行い, 次の成果を得た. (1) 全国で捕獲確認された魚種は183種であった. このうち, オイカワ, ウグイ, カワムツB型等の上位5魚種で全確認個体数の50%を占めていた. (2) 魚種別構成比に主成分分析を適用して各河川の魚種多様性を4つの主成分 (累積寄与率0.754) で表すことができた. 特に第1主成分は緯度 (河口地点) と強い相関が認められた. (3) 調査地点842箇所で魚類相と河道特性の関係を求めた. 特に多様度指数は河床勾配, 河道内緑被率と相関がみられた. (4) 河川形態や河道セグメントを用いて魚種別構成比や多様度との関係を求めて, 河道縦断的に魚類相の変化を定量化することができた.

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Flood pulses are indispensable for healthy river ecosystem. Reservoir management gives significant impact onriver flow regime including those pulses. This paper intends to clarify those impacts from statistical point of view. Using daily flow data upstream and downstream of reservoirs, we can find hownatural flood pulses are affected by flow control in reservoirs. 24 dams in Japan are chosen and 11 year recordsare analyzed to find out difference between natural and regulated flood pulses. As a result, pulses greater than 7m³/s/100km² were less in number for regulated flow, but pulses smaller than the value were often enhanced by reservoirs. Analysis of occurrence frequency and dam impacts suggest that two kinds of pulses can be identified. Daily fluctuations became more symmetric, losing gradually diminishing stage after flood peaks. Change of flushing seasonality has also detected.

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