Application of 1D and 2D hydrodynamic modeling to study glacial lake outburst flood (GLOF) and its impact on a hydropower station in Central Himalaya

Sattar, Ashim and Goswami, Ajanta and Kulkarni, Anil V (2019) Application of 1D and 2D hydrodynamic modeling to study glacial lake outburst flood (GLOF) and its impact on a hydropower station in Central Himalaya. In: NATURAL HAZARDS, 97 (2). pp. 535-553.

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Abstract

The existence of numerous lakes in the higher reaches of the Himalaya makes it a potential natural hazard as it imposes a risk of glacial lake outburst flood (GLOF), which can cause great loss of life and infrastructure in the downstream regions. Hydrodynamic modeling of a natural earth-dam failure and hydraulic routing of the breach hydrograph allow us to characterize the flow behavior of a potential flood along a given flow channel. In the present study, the flow hydraulics of a potential GLOF generated due to the moraine failure of the Satopanth lake located in the Alaknanda basin is analyzed using one-dimensional and two-dimensional hydrodynamic computations. Field measurements and mapping were carried out at the lake site and along the valley using high-resolution DGPS points. The parameters of Manning's roughness coefficient and terrain elevation were derived using satellite-based raster, the accuracy of which is verified using field data. The volume of the lake is calculated using area-based scaling method. Unsteady flood routing of the dam-break outflow hydrograph is performed along the flow channel to compute hydraulic parameters of peak discharge, water depth, flow velocity, inundation and stream power at a hydropower dam site located 28km downstream of the lake. Assuming the potential GLOF event occurs contemporaneously with a 100-year return period flood, unsteady hydraulic routing of the combined flood discharge is performed to evaluate its impact on the hydropower dam. The potential GLOF resulted in a peak discharge of2600 m(3)s(-1) at the dam site which arrived 38min after the initiation of the moraine-failure event. The temporal characteristics of the flood wave analyzed using 2D unsteady simulations revealed maximum inundation depth and flow velocity of 7.12m and 7.6ms(-1), respectively, at the dam site. Assuming that the control gates of the dam remain closed, water depth increases at a rate of 4.5m per minute and overflows the dam approximately 4min after the flood wave arrival.

Item Type:	Journal Article
Publication:	NATURAL HAZARDS
Publisher:	SPRINGER
Additional Information:	copyright for this article belongs to SPRINGER
Keywords:	Glacial lake outburst flood (GLOF); 1D and 2D hydrodynamic modeling; Mountain hazard; Himalaya; HEC-RAS; Hydropower station
Department/Centre:	Division of Mechanical Sciences > Divecha Centre for Climate Change
Date Deposited:	20 Sep 2019 06:28
Last Modified:	20 Sep 2019 06:28
URI:	http://eprints.iisc.ac.in/id/eprint/63612

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