Paleofloods records in Himalaya

Srivastava, P and Kumar, A and Chaudhary, S and Meena, N and Sundriyal, YP and Rawat, S and Rana, N and Perumal, RJ and Bisht, P and Sharma, D and Agnihotri, R and Bagri, DS and Juyal, N and Wasson, RJ and Ziegler, AD (2017) Paleofloods records in Himalaya. In: GEOMORPHOLOGY, 284 (SI). pp. 17-30.

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Abstract

We use paleoflood deposits to reconstruct a record of past floods for the Alaknanda-Mandakini Rivers (Garhwal Himalaya), the Indus River (Ladakh, NW Himalaya) and the Brahmaputra River (NE Himalaya). The deposits are characterized by sand-silt couplets, massive sand beds, and from debris flow sediment. The chronology of paleoflood deposits, established by Optically Stimulated Luminescence (OSL) and C-14 AMS dating techniques, indicates the following: (i) The Alaknanda-Mandakini Rivers experienced large floods during the wet and warm Medieval Climate Anomaly (MCA); (ii) the Indus River experienced at least 14 large floods during the Holocene climatic optimum, when flood discharges were likely an order of magnitude higher than those of modern floods; and (iii) the Brahmaputra River experienced a megaflood between 8 and 6 ka. Magnetic susceptibility of flood sediments indicates that 10 out of 14 floods on the Indus River originated in the catchments draining the Ladakh Batholith, indicating the potential role of glacial lake outbursts (GLOFs) and/or landslide lake outbursts (LLOFs) in compounding flood magnitudes. Pollen recovered from debris flow deposits located in the headwaters of the Mandakini River showed the presence of warmth-loving trees and marshy taxa, thereby corroborating the finding that floods occurred during relatively warm periods. Collectively, our new data indicate that floods in the Himalaya largely occur during warm and wet climatic phases. Further, the evidence supports the notion that the Indian Summer Monsoon front may have penetrated into the Ladakh area during the Holocene climatic optimum. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	GEOMORPHOLOGY
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Department/Centre:	Division of Mechanical Sciences > Centre for Earth Sciences
Date Deposited:	25 May 2017 08:59
Last Modified:	25 Feb 2019 08:39
URI:	http://eprints.iisc.ac.in/id/eprint/57041

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