| Project/Area Number |
09460071
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MARUTANI Tomomi Kyushu Univ., Fac. Agr., Assoc. Prof., 農学部, 助教授 (40112320)
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| Co-Investigator(Kenkyū-buntansha) |
INOHARA Youji Kagoshima Univ., Fac. Agr., Assoc. Prof., 農学部, 助教授 (60203270)
OKANO Tetsuo Kyushu Univ., Fac. Agr., Assoc. Prof., 農学部, 助教授 (00194374)
OGAWA Shigeru Kyushu Univ., Fac. Agr., Prof., 農学部, 教授 (30037973)
KASAI Mio Kyushu Univ., Fac. Agr., Assst. Prof., 農学部, 助手 (80294966)
TERAKA Yukio Kagoshima Univ., Fac. Agr., Assoc. Prof., 農学部, 助教授 (40264105)
平野 宗夫 九州大学, 工学部, 教授 (50037850)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥9,800,000 (Direct Cost: ¥9,800,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1998: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1997: ¥5,700,000 (Direct Cost: ¥5,700,000)
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| Keywords | Flooding / Magnitude of disturbance / Recurrence interval / Relaxation time / Bank erosion / Rock size distribution / Sediment production / Sediment storage / 河岸浸食 / 河床堆積土砂 / バンクエローション / 支流流域 / セデイメントバジェット / 河床変動 / 生産土砂量 / 河畔生態系 / 水中生態系 / 河岸崩壊 / Bank Erosion / Recurence Interval / 河畔埴生 / Sediment wave |
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| Research Abstract |
Based on three years observation for morphological riverbed changes and sediment transport, the factors disturbing riparian and freshwater ecosystems were analyzed. Rainfall, runoff, sediment storage volume, sediment production volume, bank erosion rate, suspended sediment volume and rock size distribution along the drainage net were measured at the Oyabu creek of a headwater of the Hitotsuse River located in the middle mountain range of Kyushu island, Japan. The following results were gained.
(1) Sediment accumulated after a flood event trended to restore sediment storage volume to the minimum value (4000mィイD13ィエD1/km) with time elapse. (2) Sediment slug associated with riverbed degradations was occurred with 2.65m/day in velocity and that with riverbed aggradations was occurred with 4.6m/day in velocity respectively. (3) The volume of sediment supply from tributary channels decreased exponentially against time elapse. (4) Rock size distribution along a channel related with macroscopically the distance from sediment production source, and slope and catchment area of significant tributaries (slope<0.15, area>10ha) joined with main channel. (5) Bank erosion rate of the upper channel (8m in averaged channel width) of the Oyabu creek was 10cm/year.
These results imply that the recovery of riparian and freshwater ecosystems is likely to be controlled by magnitude of riverbed aggradation, frequency of flooring as the recurrence interval and the time lapse after flood event. Furthermore rock size distribution along drainage net can influence on the relaxation time of ecological property of fresh water.
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