1991 Fiscal Year Final Research Report Summary
Fundamental Research on the Origin and Development of Step-pool Sequences in High Gradient Streams
| Project/Area Number |
01460230
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
林学
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| Research Institution | Kyoto University |
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Principal Investigator |
KOBASHI Sumiji Kyoto University, Agriculture, Professor, 農学部, 教授 (40026604)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Masakazu Kyoto University, Agriculture, Assistant Prof., 農学部, 助手 (10144346)
MIZUYAMA Takahisa Kyoto University, Agriculture, Associate Prof., 農学部, 助教授 (00229717)
HUKUSHIMA Yoshihiro Kyoto University, Agriculture, Associate Prof., 農学部, 助教授 (00026402)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Step-pool / Mountain torrent / River morphology / Origin / Drop structure |
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| Research Abstract |
Field survey on step-pool distribution and characteristics were carried out in Mount Rokko, the North Mountains of Kyoto, Kake-town in Hiroshima Prefecture and Tanakami Mountains of Shiga Prefecture. The results were compared with those of State of Oregon, U. S. A. The distribution of step-pool sequences are strongly controlled by torrent gradients. Five percent of torrent gradient is necessary condition for surveyed streams of the both countries. Rock exposed on torrent beds and large stones that never move by flow are other major factors of forming step-pool sequences. They are more common factors originating step-pool sequences in mountain torrents than large bolders. Another factor forming step-pool sequences is a man-made and natural drop.
Origin and shape of step-pool were investigated through flume experiments. The experiments made clear that flow discharge that can move the maxim grain size on torrent beds is necessary to create steps, and a lot of sediment transport prevent step forming steps.
Drops were introduced into the fluine to study its influence to step-pool formation. It was made clear that higher steps made more clear steps below the drops.
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