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| Titel |
A sediment budget from a glaciated catchment: reconciling subglacial and periglacial erosion on short timescales |
| VerfasserIn |
Ian Delaney, Saskia Gindraux, Yvo Weidmann, Andreas Bauder |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146101
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| Publikation (Nr.) |
 EGU/EGU2017-10101.pdf |
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| Zusammenfassung |
| Glaciated catchments are known to expel great amounts of sediment, particularly during
periods of climatic perturbation. Sediment in these catchments either originates subglacially,
where it is eroded by pressurized water below the glacier, or from periglacial areas, which
are commonly comprised of easily erodible, unconsolidated material no longer
buttressed and held in place by ice. To better forecast sediment dynamics and erosion
rates in to the future, contributions of subglacial and periglacial sediment must
be quantified, and the processes controlling erosion in these respective sources
described.
To determine the relative contributions of these sources, we examine the Griesgletscher
catchment in the Swiss Alps. Its rather simplistic geometry, as well as, the presence of a
proglacial reservoir that serves as a sediment trap, provides an unusually constrained
environment to directly measure sediment sources and sinks in the catchment. Subtraction of
three digital elevation models created from structure-from-motion and photogrammetric
techniques over a one year period, from October 2015 to October 2016, were used to
measured sediment flux from the proglacial area. Furthermore, comparison of bathymetries
collected from the proglacial reservoir in fall of 2015 and 2016 determined total sediment
flux from the entire catchment over this 10 km2time period. Data from a turbidity meter,
installed below the reservoir outflow, suggest that negligible amounts of sediment
leave the reservoir. Thus comparison of reservoir bathymetry and sediment fluxes
from the proglacial area give estimates of the relative contribution of proglacial
and subglacial sediment erosion to total catchment sedimentation. Analysis of this
data suggest that while the proglacial area experiences a greater erosion rate, it is
likely more sediment originates subglacially. As proglacial areas are expected to
grow in area and partially stabilize, and glacial areas are predicted to shrink and
possibly loose erosive capacity, these competing processes must be reconciled. |
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