Fuji-bashi, completed in 1915 over the Fuji River in Sizuoka Prefecture, is probably the longest span suspension bridge as well as only one railway suspension bridge in Japan before the World War II. However it's existence has been forgotten for a long time. The reason of oblivion will be as follows; that is, it was constructed by a private paper-manufacturing company, and it was used only four years until it was destructed in the stormy night with intent to save disaster. The purpose of this paper is to regain its reputation, and try to emphasize that Fuji-bashi is one of the important structures in the history of civil engineering of the modernized era in Japan. The paper contains lots of original data concerning its construction.

抄録全体を表示

Research on evaluation methodology of ecological conditions in river is needed for preservation and maintenance of its environment. In this study, applicability of the PHABSIM (Physical Habitat Simulation Model) of fishes to a river channel system was examined for getting a method of basin wide evaluation of the habitat suitability.
At first, a new index to evaluate the habitat suitability of fishes (S) was defined from the PHABSIM. In the next, the value of S at each cross section of the Fuji River was calculated using hydraulic conditions in the various stage of the flow, and then distribution of S along the river was discussed. At last, the value of S was compared with field data of total number of fishes caught at representative cross sections of the river. The results show that the index of the suitability has possibility to present a new method of suitability of fish habitat.

抄録全体を表示

本研究では,河川水中のリンの由来を調べることを目的に,富士山麓,八ヶ岳山麓および甲府盆地の地下水,湧水,さらに河川水についてリン濃度[P]とバナジウム濃度[V]を測定した.その結果,富士山麓や八ヶ岳山麓および甲府盆地の地下水と湧水の[P]および[V]には地域性が認められた.即ち,[P],[V]共に富士山麓地域で最も高く,八ヶ岳山麓地域,甲府盆地地域では濃度が低くなった.また,これら地下水と湧水において,これらの元素濃度には正の相関性が認められた.
一方,地下水や湧水における[P]および[V]の濃度比([P]/[V]比)についても地域性が認められた.富士山麓地域の地下水と湧水中の[P]/[V]比は,八ヶ岳山麓と甲府盆地地域より小さかった.水試料中の[P]/[V]比は,富士山麓,八ヶ岳山麓,甲府盆地地域の各々に分布する岩石の濃度比に概ね等しかった.[P],[V]および[P]/[V]比には地域性があることがわかったが,これはこの地域を構成する岩石(玄武岩,安山岩,花歯岩)や地質の地球化学的影響を反映していると考えることができた.
次に,相模川との各河川での[P],[V]および[P]/[V]比は,相模川では河川上流域および集水域の地下水や湧水の特徴に概ね等しかったことから,[P]と[V]起源は,河川流域に分布する岩石や地質の地球化学的特徴として説明できた.[P]は,河川上流域の地下水もしくは湧水中の濃度より僅かに高いのみであった.における[V]は,河川流域の地下水や湧水中のそれとほとんど変わらなかった.ところが,[P]および[P]/[V]比は,集水域および河川上流域の地下水や湧水中の値より極端に高かった.
河川水中の[P]のうち人為的な影響による[P]は,河川流域に分布する地下水や湧水中の[P]/[V]比がほぼ一定であることを基に,河川水の[V]から算出した[P]を河川水中の[P]から減ずることにより捕らえることができた.

抄録全体を表示

In this study, quantitative analysis on the relation between the physical diversity of river channel and the diversity of kinds of fishes has been carried out.
In this paper, the authors tried to find the physical factor of river channel which had an influence effectively to preserve the diversity of kinds of fishes by increasing the rivers and areas to analyze it, in addition to the results until now. The diversity of kinds of fishes was assessed by using the Simpson's diversity index. On the other hand, the diversity of river channel was expressed by standard deviations of the channel hydraulic variables, such as water depth and flow velocity.
The results of this examination showed that the diversity of kinds of fishes was secured in the area which the diversity of kinds of the young fishes was rich. And, as for the rate of the area of the shoreline, it found that it was important as well as “riffle and pool” which was important in the existent research.

抄録全体を表示

This paper deals with a nature made type groyne which can be called laid triangular sharp pyramid type groyne(Tri-Pyra groyne). Original nature made groyne can be seen at some gravel and stone bed river channels. On the other hand, man-made old groynes of similar shape, called arako groyne, are still functioning at ash-mud bed channels in Kyushu, some are for more than 300 years. Here, considering the rationality of these groynes, stability and function of the groyne were evaluated by field consideration, and 2D calculation. Comparison was also made with another similar groynes. As conclusion, adaptation of this type of groynes, especially Tri-Pyra groyne, is proposed for practical application and the direction of its further development is also suggested.

抄録全体を表示