Effects of unsteady supply conditions of water and sediment and sediment sorting on variations in low-waterway morphology
| Project/Area Number |
16560457
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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 |
水工水理学
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| Research Institution | Maizuru National College of Technology |
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Principal Investigator |
MIWA Hiroshi Maizuru National College of Technology, Department of Civil Engineering, Associate Professor (70190832)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | low-watercourse / water discharge condition / sediment supply condition / unsteady / aggradation and degradation / water-route / non-uniform sediment / grain sorting / 流量・土砂供給量の変化間隔 / 河床低下 / 上昇 / 流路変動 / 土砂供給 / 流量変化 / 河床上昇 / 低下 / 河床変動 / 水みち深さ / 交互砂州 |
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| Research Abstract |
Low-waterways with pool and riffle sequence functions as fish and plant habitat in ordinary discharge period. Therefore, it is important to investigate characteristics of low-waterway variation due to change of water and sediment supply conditions. This corresponds to information in order to investigate how controls of water and sediment supply are better for fish and plant habitat in rivers. In this study, effects of the change of water and sediment supply conditions on low-waterway, which developed from alternate bars, variation were investigated by means of flume tests. Results are summarized as follows :
1. The low-waterways fluctuate actively along with bed aggradation during the periods of sediment supply, and they unify and stabilize along with bed degradation during the periods of no-sediment supply.
2. Gentle change of sediment supply rate restricts stabilization of low-waterway, and it effects moderate variations of pool and riffle sequence.
3. The low-waterway changes into alternate bars with erosion of emerged bars during the high-water discharge period ; and the alternate bars change into low-waterways with development of emerged bars during the low-water discharge period. The former occurs along with the bed degradation and the latter occurs along with the bed aggradation.
4. The variation range of the depth of low-waterway in the non-uniform sediment bed is smaller than that in the uniform sediment bed because the erosion of bed sediments is restricted by means of sediment coarsening due to grain sorting.
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Report
(4 results)
Research Products
(25 results)
