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| Titel |
Holocene extreme hydrological events and their climatic implications:
evidence from the middle Satluj valley, western Himalaya, India |
| VerfasserIn |
Shubhra Sharma, Anil Shukla, Bhupinder Marh, Sukesh Bartarya, Navin Juyal |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122848
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| Publikation (Nr.) |
 EGU/EGU2016-1979.pdf |
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| Zusammenfassung |
| Extreme hydrological events and associated climatic processes are investigated and inferred
through palaeoflood deposits preserved in the middle Satluj valley, India. Satluj River is the
largest tributary of the Indus River having third largest catchment area in the Himalaya. Both
Indian summer monsoon (ISM) and the mid-latitude westerlies contribute to the hydrological
budget of the river. The steep southern orographic front prevents the northward penetration of
ISM, while the mid-latitude westerlies bring moisture in form of winter snow to the orogenic
interiors.
It has been observed that the floods in the Himalaya are intimately associated with the
variability in the above climate systems. The optical chronology indicates that floods were
clustered around three time domains. The oldest flood phase-1 is dated to ∼14-12 ka which
climatically occurred during the initiation of the ISM after the Last Glacial Maximum. The
second phase-2 is dated between 8-5 ka and is attributed to the moderate ISM. Whereas, the
youngest phase-3 is assigned the Little Ice Age (LIA) and were associated with
the variability in the mid-latitude westerlies. Geochemical analyses suggest that
floods were generated in higher Himalayan crystalline (HHC) zone, as the extreme
precipitation destabilised the precipitous slopes creating Landslide induced Lake
Outbursts Floods (LLOFs). Further, the average interval between floods has decreased
since 14 ka from 500 years, to 250 years and 100 years during respective flood
phases.
The southern slopes of Himalaya are influenced by both the monsoon and mid-latitude
westerlies and any abrupt changes in the circulation pattern were found to associate with
heavy rainfall events in this region. Although an interaction between the westerlies and the
monsoon is implicated for extreme floods in the western Himalaya. However, exact
mechanism of these interactions is still illusive except for the observational based studies
which state that extreme floods occurred during moderate monsoon. This observation
corroborates well with the chronology of the flood sequences of the middle Satluj valley.
We ascribe the floods to the transient monsoon/westerlies phases in the western
Himalaya. Such phases are known to modulate the temporal changes in the pattern of the
Rossby waves which in turn dictate the southward penetration of the cold arctic
air masses during the Arctic Oscillations (AO). Finally, a steady decrease in the
flood intervals probably suggests more frequent and rapid interaction between the
monsoon and mid-latitude westerlies trough over the western Himalaya. With the
anticipated global warming, the extreme flood events are likely to increase both
in magnitude and frequency. Hence, emphasizes on the re-evaluation of ongoing
infrastructure developmental activity, particularly the river valley projects in the Satluj river. |
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