Late Quaternary fluvial aggradation and incision in the monsoon-dominated Alaknanda valley, Central Himalaya, Uttrakhand, India

Juyal, Navin ; Sundriyal, Yaspal ; Rana, Naresh ; Chaudhary, Shipra ; Singhvi, Ashok K. (2010) Late Quaternary fluvial aggradation and incision in the monsoon-dominated Alaknanda valley, Central Himalaya, Uttrakhand, India Journal of Quaternary Science, 25 (8). pp. 1293-1304. ISSN 0267-8179

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/jqs.141...

Related URL: http://dx.doi.org/10.1002/jqs.1413

Abstract

The present study aims to explain the spatial and temporal variability in phases of aggradation/incision in response to changes in climate and seismicity during the late Quaternary in the Alaknanda River valley (a major tributary of the river Ganges or Ganga). Geomorphology, stratigraphy and optical dating of the fluvial sediment reveal that the oldest fluvial landforms preserved in the south of the Main Central Thrust are debris flow terraces developed during the early part of pluvial Marine Isotopic Stage 3. Following this, a period of accelerated incision/erosion owing to an increase in uplift rate and more intense rainfall occurred. In the Lesser Himalaya, three phases of valley fill aggradation around 26±3 ka, 18±2 ka and 15±1 ka and 8±1 ka occurred in response to changes in monsoon intensity and sediment flux. The last phase was regionally extensive and corresponds to a strengthening of the early Holocene Indian Summer Monsoon. A gradual decline in the monsoon strength after 8±1 ka resulted in reduced fluvial discharge and lower sediment transport capacity of the Alaknanda River, leading to valley fill incision and the development of terraces. The study suggests that fluvial dynamics in the Alaknanda valley were modulated by monsoon variability and the role of tectonics was subordinate, limited to providing accommodation space and post-deposition modification of the fluvial landforms.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Late Quaternary; Terraces; Monsoon; Optical Dating; Central Himalaya
ID Code:47857
Deposited On:12 Jul 2011 14:05
Last Modified:12 Jul 2011 14:05

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