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| Titel |
Dating abandoned channels in uplifting mountainous terrains: an approach to reconstruct watershed evolution on the absolute time scale |
| VerfasserIn |
Yuki Matsushi, Masahiro Chigira, Ching-Ying Tsou, Narumi Hiraishi, Hiroyuki Matsuzaki |
| 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 |
250048659
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| Zusammenfassung |
| River incision and subsequent gravitational slope deformation pose a grave threat of
deep-seated landslides in an active orogen. Quantitative linkage between channel and
hillslope processes are required for assessment of landslide hazards, which also help
reconstruct long-term landscape evolution of the mountainous watersheds. Determination of
river incision rates provides a clue to understand transient responses of such channel-hillslope
systems to external and/or internal forcing. This study attempts to date fluvial deposits left
above the present river by cosmogenic nuclide exposure dating for revealing spatial and
temporal history of river incision. Study areas are Shihmen reservoir watershed in northern
Taiwan, and Totsukawa watershed in Kii Peninsula, central Japan. Rounded gravels were
collected for the cosmogenic Be-10 and Al-26 analyses, from relict channels around meander
cores, wind gaps on the catchment boundary, and sediment left on the edge of spurs.
Preliminary results from the Totsukawa watershed show ages of ~30 ka for gravels
at 130-160 m above the current river bed, corresponding to the incision rate of
~4-5 mm/kyr. This rapid incision may have led to the formation of inner gorges
in the watershed and resulted in destabilization of the side-slopes along the river. |
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