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| Titel |
Spatial clustering of natural dams at the Tibetan Plateau margin in rivers draining the Himalayan syntaxes |
| VerfasserIn |
O. Korup, D. R. Montgomery, K. Hewitt |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026467
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| Zusammenfassung |
| Despite numerous studies on the age and formation of the Tibetan Plateau, the erosional
decay of its margins remains largely unexplored. Pronounced aridity and localised high rates
of rock uplift are two conventional ways to explain the limited efficacy of fluvial bedrock
incision in dissecting the Plateau’s rim. Yet evidence remains scarce to argue that these
controls are solely responsible for limiting the knickpoint retreat of some of Asia’s largest
rivers into the plateau interior. Here we point out a striking spatial coincidence
of the Tibetan Plateau margin and clusters of large natural dams along the Indus
and Yarlung Tsangpo, the two major rivers draining the Himalayan syntaxes. The
Yarlung Tsangpo and its tributaries near Namche Barwa are largely influenced by
several hundreds of large moraine dams clustered at the plateau margin. Similarly,
the upper Indus is riddled by hundreds of large natural dams mainly formed by
>250 km3 of debris from catastrophic rock avalanches, forming one the largest
clusters of giant landslide dams known worldwide. We present and discuss a model
in which natural dams contribute to protecting bedrock from fluvial incision and
headward knickpoint migration, thereby helping stabilise the margin of the Tibetan
Plateau in concert with the effects of aridity and localised rock uplift. Based on a
comparison of the eastern and western Himalayan syntaxes, we (1) propose that a
zone of high susceptibility to natural river damming that develops along the plateau
rim helps retard river incision, and (2) test the hypothesis that whether such dams
dominantly form by glaciers or landslides depends on regional moisture availability. |
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