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| Titel |
Spatial gradients in climate, vegetation, and catchment-mean erosion rates in the Arun Valley, Eastern Nepal |
| VerfasserIn |
Stephanie Olen, Bodo Bookhagen, Bernd Hoffmann, Dirk Sachse, Danda Adhikari, Manfred Strecker |
| 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 |
250090558
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| Publikation (Nr.) |
 EGU/EGU2014-4811.pdf |
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| Zusammenfassung |
| A link between climate, vegetation cover, and regional erosion rates has been widely
proposed in the Himalaya, but has proven hard to quantify. We investigate the connection
between Indian Summer Monsoon (ISM) rainfall, vegetation cover, and erosion in the
Arun valley of eastern Nepal. One of the largest trans-Himalayan rivers, the Arun
has cut a natural cross-section through all major Himalayan geological units and
structures from the northern Tethyan sequences in Tibet to the alluvial sediments of
the southern Ganges plain. Located near the monsoonal moisture source in the
Bay of Bengal, the Arun receives significant amounts of ISM rainfall (average 2 m
yr-1 in the Arun gorge). Rainfall in the valley is focused along the Himalayan
mountain front, forced by orographic barriers of the Lesser and Higher Himalayas,
resulting in a steep, two-tiered rainfall gradient (from a peak >4 m yr-1 at the
Higher Himalayan front to ~0.5 m yr-1 at the border with Tibet) [1]. Rainfall along
this gradient is highly seasonal; based on meteorological stations along the Arun,
approximately 80% of annual rainfall occurs during the peak summer monsoon
months, corroborating earlier results [1]. Abundant precipitation and relatively
warm temperatures in the deeply incised Arun gorge result in dense vegetation
cover in much of the valley, ranging from sub-tropical forests to alpine vegetation
cover.
In order to quantify erosion variability in the Arun with respect to climate, vegetation, and
tectonics, we collected 51 river sand samples over two field seasons for catchment-mean
cosmogenic radionuclide (CRN) analysis [2,3]. Samples were collected from the main
stem of the Arun and from tributary watersheds ( |
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