The origin of stream terraces in the alluvial lower reaches of rivers: an experimental examination of the Complex Response model
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- Akiyama Minako
- Department of Geology and Mineralogy, Kyoto University
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- Muto Tetsuji
- Faculty of Environmental Studies, Nagasaki University
Bibliographic Information
- Other Title
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- 下流域沖積河川系における河岸段丘の形成機構:水路実験による複雑応答説の検証
- カリュウイキ チュウセキ カセンケイ ニ オケル カガン ダンキュウ ノ ケイセイ キコウ スイロ ジッケン ニ ヨル フクザツ オウトウセツ ノ ケンショウ
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Abstract
The Complex Response model originated by Schumm and Parker (1973) claims that multiple paired stream terraces can form as a result of “complex” mutual feedbacks between the downstream and upstream reaches of the river system in response to a single drop in base level whereby the river initially becomes ungraded and then recovers a graded state. To critically test this model, a series of analog flume experiments was conducted, during each of which it was observed how the alluvial lower reaches of a river responded to base level fall under the conditions of constant sediment discharge, constant upstream water discharge to convey the sediment downslope, and a uniform flume slope. The model river was graded using a downstream weir; sudden removal of the weir created a discrete drop in base level. The results of the experiment suggest that (1) even in a graded system, there can form “incipient” stream terraces owing to autogenic or self-organizing geomorphic process of the river, (2) base level fall functions simply to amplify the relief of pre-existing incipient terraces and is not necessarily responsible for the formation of stream terraces, thus, (3) the complex response of river systems is regarded as a manifestation of the alluvial autogenic responses, and (4) the autogenic responses observed in the runs are in the form of fluvial-diffusive processes. The upscaling of a model alluvial river implies that in a prototype, small-scale, high-gradient, gravel-dominated natural system, the diffusive alluvial response will completely regain its graded state in a very short time after becoming ungraded by a discrete drop in base level.<br>
Journal
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- The Journal of the Geological Society of Japan
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The Journal of the Geological Society of Japan 112 (5), 315-330, 2006
The Geological Society of Japan
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Keywords
Details 詳細情報について
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- CRID
- 1390001206238921856
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- NII Article ID
- 110004749696
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- NII Book ID
- AN00141768
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- ISSN
- 13499963
- 00167630
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- NDL BIB ID
- 7978508
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- Abstract License Flag
- Disallowed