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Title: Hydrodynamic moraine-breach modeling and outburst flood routing - A hazard assessment of the South Lhonak lake, Sikkim
Authors: Sattar A.
Goswami, Ajanta
Kulkarni A.V.
Published in: Science of the Total Environment
Abstract: The presence of glacial lakes in the Himalaya makes it a potential mountain hazard, as catastrophic failure of such waterbodies may lead to high-magnitude glacial lake outburst flood (GLOF) events that can cause significant damage to the low-lying areas. The present study evaluates the hazard potential of the South Lhonak lake located in the state of Sikkim, using both one and two-dimensional hydrodynamic modeling approaches. Different breach parameters were calculated based on the lake bathymetry and moraine dimensions. The worst-case GLOF scenario is revealed during an overtopping failure of the moraine, producing a peak flood of 6064.6 m 3 s ?1 and releasing a total water volume of 25.7 × 10 6 m 3 . The GLOF hydrograph is routed to calculate peak flood (m 3 s ?1 ), inundation depth (m) and flow velocity (ms ?1 ) along the main flow channel. The interaction of the flood wave with a major topographic obstruction located 15.6 km downstream of the lake, shows a significant reduction of the flow energy leading to a minimization of the South Lhonak GLOF impact. The flood wave reaches the nearest town Lachen, located at a distance of 46 km downstream from the lake, at 3 h 38 min after the initiation of the breach, with a peak flood of 3928.16 m 3 s ?1 and a maximum flow velocity of 13.6 ms ?1 . At Chungthang town, located at a distance of 62.35 km from South Lhonak lake, the flood wave potentially inundates settlements along the bank of the flow channel, where a peak flood of 3828.08 m 3 s ?1 is reached after 4 h of the initial dam breach event. The study also incorporates modeling of a framework to propose a potential flood remediation measure of the South Lhonak lake GLOF by demonstrating the effect of a lateral inline structure along the flow channel, to check the flow of the potential flood wave. © 2019 Elsevier B.V.
Citation: Science of the Total Environment (2019), 668(): 362-378
Issue Date: 2019
Publisher: Elsevier B.V.
Keywords: GLOF modeling
Mitigation measures
Mountain hazard
Sikkim Himalaya
South Lhonak
ISSN: 489697
Author Scopus IDs: 57207360550
Author Affiliations: Sattar, A., Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Goswami, A., Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Kulkarni, A.V., Indian Institute of Science Bangalore, Bangalore, Karnataka 560012, India
Funding Details: The authors would like to acknowledge the Indian Institute of Technology, Roorkee, India for providing necessary infrastructure facilities. The authors also acknowledge MHRD, MoES (IMPRINT) and DST INSPIRE fellowship programme for providing the necessary financial support. The authors would further like to acknowledge USGS, Digital Globe, and NavInfo for the remote sensing datasets employed in the study.
Corresponding Author: Sattar, A.; Indian Institute of Technology RoorkeeIndia; email:
Appears in Collections:Journal Publications [ES]

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