Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel

Vallé, Brett L.; Pasternack, G. B.

doi:10.1016/j.geomorph.2005.09.024

Cited by 57 publications

(41 citation statements)

References 54 publications

(120 reference statements)

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“…Although rarely described specifically in the literature, step-pool geometry analogous to that found in supraglacial channels is widely reported in speleological investigations of englacial flow paths and conduits (Griselin, 1992;Holmlund, 1988;Piccini et al, 2000;Pulina, 1984;Pulina and Rehak, 1991;Řehák et al, 1990;Schroeder, 1998;Vatne, 2001;Vatne and Refsnes, 2003). The prevalence of the steps (typically 1-5 m in height) in englacial flow paths may mean that > 80 % of an englacial conduits' vertical descent occurs in cascades (e.g.…”

Section: Introductionmentioning

confidence: 92%

“…This insight is coupled with the recognition that hydrologically assisted fracture propagation (Benn et al, 2009;Boon and Sharp, 2003;Hambrey, 1984) and the progressive incision of so-called cut-and-closure supraglacial streams (Gulley et al, 2009a;Vatne, 2001) also represent important mechanisms by which meltwater can be transferred from the supraglacial environment to a glacier's interior (Baelum and Benn, 2011;Naegeli et al, 2014). With suggestions that englacial flow paths, particularly in nontemperate ice masses, may be comparable with karstic systems (e.g.…”

Section: Introductionmentioning

confidence: 97%

“…The prevalence of the steps (typically 1-5 m in height) in englacial flow paths may mean that > 80 % of an englacial conduits' vertical descent occurs in cascades (e.g. Vatne, 2001). Recent studies have referred to individual steps in the longitudinal channel profiles as knickpoints (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Morphological dynamics of an englacial channel

Vatne

Irvine‐Fynn

2016

Hydrol. Earth Syst. Sci.

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Abstract. 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 "cutand-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 steppool 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 cutand-closure channels to better understand their coupling to supraglacial meltwater sources and potential significance in cold-based glacier hydrology and ice dynamics.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 97%

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Morphological dynamics of an englacial channel

Vatne

Irvine‐Fynn

2016

Hydrol. Earth Syst. Sci.

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“…Fourth, modern instrumentation has dramatically changed the nature of field research on river hydraulics (Sukhodolov 2015), and computational and laboratory experiments have addressed a number of issues raised by field observations (e.g., Valle & Pasternack 2006, Thompson & Wohl 2009, Thompson & McCarrick 2010, Gioia et al 2011). Controversies about whether or not supercritical flow occurs in rivers have emerged (e.g., Grant 1997, Magirl et al 2009, Kostic et al 2010, Fricke et al 2015.…”

Section: Related Resourcesmentioning

confidence: 99%

Researching the Earth—and a Few of Its Neighbors

Kieffer

2017

Annu. Rev. Earth Planet. Sci.

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“…The channel morphology determines the flow dynamics [3,28] and vice versa. It is expected that the channel morphology can be derived from the observed flow dynamics [1] mainly using the velocity field and stream power identifications.…”

Section: Applicability Of Uas Data In Fluvial Geomorphologymentioning

confidence: 99%

Multitemporal Monitoring of the Morphodynamics of a Mid-Mountain Stream Using UAS Photogrammetry

Miřijovský

Langhammer

2015

Remote Sensing

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This paper explores the potential of Unmanned Aerial Systems (UASs) for the analysis of variations in the fluvial dynamics of a mid-mountain stream. The UAS photogrammetry was employed to acquire a multitemporal set of high-precision digital terrain models (DTMs) and orthoimages, thereby enabling the reconstruction of variations in riverbed and quantitative analysis of volumetric changes. A hexacopter UAS platform was used for the repeated acquisition of data for the photogrammetric analysis of a stretch of mid-mountain streams with elevated fluvial dynamics. Photogrammetric reconstruction enabled the development of accurate DTMs and orthoimages with spatial resolutions of 2 cm per pixel. These were identified and used to quantitatively assess the segments of channels with active lateral erosion. The UAS-derived data facilitated an analysis of the shifts of stream banks and the calculation of the areal extent of changes and volumetric extent of bank erosion. Comparison of UAS-derived point clouds with aerial LiDAR scanning data demonstrated the high spatial accuracy and precision of the UAS data. The accuracy and high operability of the imaging provide spatial data of a new qualitative level and the potential for the detailed analysis of experimental areas where spatial information is of limited availability. OPEN ACCESSRemote Sens. 2015, 7 8587

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Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel

Cited by 57 publications

References 54 publications

Morphological dynamics of an englacial channel

Morphological dynamics of an englacial channel

Researching the Earth—and a Few of Its Neighbors

Multitemporal Monitoring of the Morphodynamics of a Mid-Mountain Stream Using UAS Photogrammetry

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