DOI: 10.5194/hess-20-2947-2016
Scopus记录号: 2-s2.0-84979529837
论文题名: Morphological dynamics of an englacial channel
作者: Vatne G ; , Irvine-Fynn T ; D ; L
刊名: Hydrology and Earth System Sciences
ISSN: 10275606
出版年: 2016
卷: 20, 期: 7 起始页码: 2947
结束页码: 2964
语种: 英语
Scopus关键词: Energy dissipation
; Surveys
; Decadal timescale
; Dominant process
; Glacier hydrology
; Morphological dynamics
; Quasi equilibrium
; Rapid transitions
; Supraglacial channels
; Upstream migration
; Lakes
; channel
; coupling
; energy dissipation
; englacial process
; geometry
; glaciology
; ice
; meltwater
; morphology
英文摘要: Despite an interest in the hydraulic functioning of supraglacial and englacial channels over the last 4 decades, the processes and forms of such ice-bounded streams have remained poorly documented. Recent glaciological research has demonstrated the potential significance of so-called "cut-and-closure" streams, where englacial or subglacial flow paths are created from the long-term incision of supraglacial channels. These flow paths are reported to exhibit step-pool morphology, comprising knickpoints and/or knickzones, exaggerated in dimensions in comparison to supraglacial channels. However, little is known of the development of such channels' morphology. Here, we examine the spatial organisation of step pools and the upstream migration of steps, many of which form knickzones, with repeated surveys over a 10-year period in an englacial conduit in cold-based Austre Brøggerbreen, Svalbard. The observations show upstream step recession to be the dominant process for channel evolution. This is paralleled by an increase in average step height and conduit gradient over time. Characteristic channel-reach types and step-riser forms are consistently observed in each of the morphological surveys reported. We suggest that the formation of steps has a hydrodynamic origin, where step-pool geometry is more efficient for energy dissipation than meanders. The englacial channel system is one in rapid transition towards a quasi-equilibrium form within a decadal timescale. The evolution and recession of knickzones reported here result in the formation of a 37 m deep moulin shaft, suggesting that over time an incising supraglacial channel may evolve towards an englacial channel form exhibiting a stable end-point characterised by a singular vertical descent, which potentially can reach the glacier bed. This challenges the prevailing notions that crevasses or hydrofractures are needed to form deep moulins. Our observations highlight the need to further examine the adjustment processes in cut-and-closure channels to better understand their coupling to supraglacial meltwater sources and potential significance in cold-based glacier hydrology and ice dynamics. © 2016 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/78783
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Geography, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom
Recommended Citation:
Vatne G,, Irvine-Fynn T,D,et al. Morphological dynamics of an englacial channel[J]. Hydrology and Earth System Sciences,2016-01-01,20(7)