1997 Fiscal Year Final Research Report Summary
Field study on suspended sediment, organic matter and water quality in streams and relationships with riffle or step-pool sequences of riverbed
| Project/Area Number |
08660174
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | University of Tsukuba |
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Principal Investigator |
MAITA Hideji Univ.Tsukuba, Inst.of Agricultural and Forest Engineering, Associate Prof., 農林工学系, 助教授 (50015864)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIDA Kohji Univ.Tsukuba, Inst.of Agricultural and Forestry, Associate Prof., 農林学系, 助教授 (10015670)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Step-pool / Suspended sediment / Organic matter / Sediment yield / Water quality / Aquatic ecosystem / Sediment control / Field study |
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| Research Abstract |
We monitoerd water discharge, suspended sediment runoff including organic matter and water quality in the Kurabone stream of Tsukuba University forest at Kawakami and surveyed riverbed morphology in order to clarify the method of sedinment control in torrents harmonaizing with aquatic ecosystem. As a result, first we clarified characteristics of step-pool sequenses which step intervals decreased with increasing slope of riverbed. Secondly we suggested that disturbance to the stream caused by sediment supply owing to a slope failure along the stream was absorbed through forming and diminishing step and/or pool in the stream. Thirdly we suggested that the source of suspended sediment and organic matter in monitored runoff was fine materials and organic matter in the riverbed and bank becuase the peak of suspended sediment and organic matter concentration appeared before the peak of water discharge in floods or it almost appeared simultaneously. Forth we found that a NO_3 ion was different response from the other ions in runoff of floods, it suggested that the NO_3 ion had a relationship with organic matter runoff because nitrogen in condition of nitric acid is not geosphere origin but is atmosphere origin. Fifth we estimated that the annual suspended sediment yield in floods was 22.4t (59.3t/km^2/y) and the annual organic yield in floods was 8.4t (22.23t/km^2/y) using suspended sediment and organic mater rating curves based on monitoring data. The annual suspended yield in floods was roughly 12 times as large as the annual runoff of bed load. Lastly we suggested that a sediment wave is an very important factor for deforming step-pool sequences.
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