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| Titel |
Quantification of coarse sediment connectivity in alpine geosystems |
| VerfasserIn |
Markus Thiel, Tobias Heckmann, Florian Haas, Michael Becht |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054864
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| Zusammenfassung |
| In alpine catchments several subsystems (rock face, slope, and valley floor) are
sedimentologically connected by geomorphic processes like rock fall, debris flows,
avalanches, etc. If these processes work together by propagating sediment from source (rock
face) to sink (outlet) they constitute sediment cascades.
Sediment connectivity is a system property which describes the integrated state of
coupling of these processes to sediment cascades in a given catchment. It accounts for the
nonlinearity of the sediment delivery ratio at different scales and is mainly a function of the
topologic configuration of the geomorphic system.
In the presented study numerical GIS-based models are applied to digital elevation
models (DEM) to investigate the coupling of geomorphic process units by delineating the
process domains of important geomorphic processes in high-mountain environments (rock
fall, slope-type debris flows, slope aquatic and fluvial processes). Graph theory is used as an
overarching framework to analyze the individual process domains and to connect them to a
sediment cascade. For a given outlet the coupled area and the sediment transfer
potential can be obtained. The models also generate so-called edge lists that can be
converted to adjacency matrices and graphs which can be used to calculate connectivity
indices.
The results are validated by field mapping and show that only small parts of a catchment
are actually coupled to its outlet with respect to coarse (bed load) sediment. Such
quantification complements the mainly qualitative appraisal of coupling and connectivity; the
effect of connectivity on other catchment properties such as specific sediment yield and
catchment sensitivity can then be studied on the basis of these quantitative measures. |
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