DOI: 10.1002/2016GL068713
论文题名: The grain size gap and abrupt gravel-sand transitions in rivers due to suspension fallout
作者: Lamb M.P. ; Venditti J.G.
刊名: Geophysical Research Letters
ISSN: 0094-9073
EISSN: 1944-8804
出版年: 2016
卷: 43, 期: 8 起始页码: 3777
结束页码: 3785
语种: 英语
英文关键词: fluvial
; Fraser River
; gravel
; sand
; sediment transport
; suspension
Scopus关键词: Grain size and shape
; Gravel
; Reynolds number
; Rivers
; Sand
; Sediment transport
; Sediments
; Shear flow
; Suspensions (fluids)
; Abrupt transition
; Bed materials
; Bed sediments
; fluvial
; Fraser river
; Median grain sizes
; Sediment supply
; Shear velocities
; Suspended sediments
英文摘要: Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1-5 mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between gravel- and sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or a bimodal sediment supply, but supporting evidence is lacking. Here we demonstrate that rivers dramatically lose the ability to transport sand as wash load where bed shear velocity drops below ~0.1 m/s, forcing an abrupt transition in bed-material grain size. Using thresholds for wash load and initial motion, we show that the gap emerges only for median bed-material grain sizes of ~1-5 mm due to Reynolds number dependencies in suspension transport. The grain size gap, therefore, is sensitive to material properties and gravity, with coarser gaps predicted on Mars and Titan. ©2016. American Geophysical Union. All Rights Reserved. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968779435&doi=10.1002%2f2016GL068713&partnerID=40&md5=f28b84c3043f909b40795c7cf30f565a
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/10036
Appears in Collections: 科学计划与规划 气候变化与战略
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作者单位: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
Recommended Citation:
Lamb M.P.,Venditti J.G.. The grain size gap and abrupt gravel-sand transitions in rivers due to suspension fallout[J]. Geophysical Research Letters,2016-01-01,43(8).