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| Titel |
Sediment connectivity evolution on an alpine catchment undergoing glacier retreat |
| VerfasserIn |
Beatrice Goldin, Benjamin Rudaz, Eric Bardou |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092381
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| Publikation (Nr.) |
 EGU/EGU2014-6720.pdf |
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| Zusammenfassung |
| Climate changes can result in a wide range of variations of natural environment
including retreating glaciers. Melting from glaciers will have a significant impact on the
sediment transport characteristics of glacierized alpine catchments that can affect
downstream channel network. Sediment connectivity assessment, i.e. the degree of
connections that controls sediment fluxes between different segments of a landscape, can
be useful in order to address management activity on sediment fluxes changes of
alpine streams. Through the spatial characterization of the connectivity patterns of a
catchment and its potential evolution it is possible to both define sediment transport
pathways and estimate different contributions of the sub-catchment as sediment
sources.
In this study, a topography based index (Cavalli et al., 2013) has been applied to assess
spatial sediment connectivity in the Navisence catchment (35 km2), an alpine basin located
in the southern Walliser Alps (Switzerland) characterized by a complex glacier
system with well-developed lateral moraines on glacier margins already crossed by
several lateral channels. Glacier retreat of the main glacial edifice will provide a
new connectivity pattern. At present the glacier disconnects lateral slopes from the
main talweg: it is expected that its retreat will experience an increased connectivity.
In order to study this evolution, two high resolution (2 m) digital terrain models
(DTMs) describing respectively the terrain before and after glacier retreat have been
analyzed. The current DTM was obtained from high resolution photogrammetry (2 m
resolution). The future DTM was derived from application of the sloping local base level
(SLBL) routine (Jaboyedoff et al., 2004) on the current glacier system, allowing to
remove the ice body by reconstituting a U-shaped polynomial bedrock surface. From
this new surface a coherent river network was drawn and slight random noise was
added. Finally the river network was burned into the rough surface of the SLBL
results.
The impact of sediment dynamic changes on the study catchment due to glacier retreat
has been assessed by comparing predictions deriving from model application on different
scenarios. Simulations allowed the analysis of sediment connectivity evolution over decade
scales suggesting an increase of potential sediment transfer and connections in areas close to
the main channel network.
References:
Cavalli, M., Trevisani, S., Comiti, F., Marchi, L., 2013. Geomorphometric assessment of
spatial sediment connectivity in small Alpine catchments. Geomorphology 188,
31–41.
Jaboyedoff M., Bardou E., Derron M.-H. 2004. Sloping local base level: a tool to estimate
potential erodible volume and infilling alluvial sediment of glacial valleys. Swiss
Geo-Scientists meeting, November 2004, Lausanne. |
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