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Dynamic simulation of catastrophic late Pleistocene glacial-lake drainage, Altai Mountains, central Asia

Dynamic simulation of catastrophic late Pleistocene glacial-lake drainage, Altai Mountains, central Asia
Dynamic simulation of catastrophic late Pleistocene glacial-lake drainage, Altai Mountains, central Asia
Numerical simulations of the catastrophic draining of Pleistocene glacial-lake Kuray–Chuja quantify the discharge history of the draining event in detail. The plan-view basin flows are modelled as water emptied due to the instantaneous failure of the impounding ice-dam when the lake was at maximum capacity. The Chuja Basin water exited as a jet-flow into the Kuray Basin via a narrow conjoining valley. The peak discharge from the Chuja Basin is etermined to be 1.20 × 107 m3 s?1, and the peak discharge (3.19 × 107 m3 s?1 > Q ? 2.0 × 107 m3 s?1) that flowed from the Kuray Basin at the failed impoundment is also calculated for two limiting conditions. The variations in
lake volume and depth indicate complete drainage within 50 h. In both basins, fields of relict gravel bedforms reflect sediment transport due to entrained lake-bed sediments. Thus, in addition to the general overview of drainage, the detailed temporal and spatial evolutions of drainage
parameters are reported, including for the locations of the bedform fields. Local flow above the bedforms is considered in relation to thresholds for sediment motion, bedform development, and orientations. Within the simple bathymetry of the Chuja Basin, the flow field was fairly uniform
with flow conducive to bedform evolution only occurring close to the exit from the basin, which accords with field evidence. In contrast, within the Kuray Basin, the flow responded sensitively to the complex bathymetry, which included rapid changes in flow direction due to interaction of the Kuray water with the jet-flow from Chuja, and as submerged ridges shoaled. Thus the Kuray flow field was complex but with time-dependent flow conditions in ccordance with bedform development. It is concluded that the location of the bedforms can be explained in terms of the flow modelling and suggestions are made as to how future drainage models might be improved.
0020-6814
Bohorquez, Patricio
02e78904-3547-4c6c-b93a-cd5758e61f91
Carling, Paul
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Herget, Juergen
d0ee8293-218f-42bd-85c4-0fe93c767412
Bohorquez, Patricio
02e78904-3547-4c6c-b93a-cd5758e61f91
Carling, Paul
8d252dd9-3c88-4803-81cc-c2ec4c6fa687
Herget, Juergen
d0ee8293-218f-42bd-85c4-0fe93c767412

Bohorquez, Patricio, Carling, Paul and Herget, Juergen (2015) Dynamic simulation of catastrophic late Pleistocene glacial-lake drainage, Altai Mountains, central Asia. International Geology Review. (doi:10.1080/00206814.2015.1046956).

Record type: Article

Abstract

Numerical simulations of the catastrophic draining of Pleistocene glacial-lake Kuray–Chuja quantify the discharge history of the draining event in detail. The plan-view basin flows are modelled as water emptied due to the instantaneous failure of the impounding ice-dam when the lake was at maximum capacity. The Chuja Basin water exited as a jet-flow into the Kuray Basin via a narrow conjoining valley. The peak discharge from the Chuja Basin is etermined to be 1.20 × 107 m3 s?1, and the peak discharge (3.19 × 107 m3 s?1 > Q ? 2.0 × 107 m3 s?1) that flowed from the Kuray Basin at the failed impoundment is also calculated for two limiting conditions. The variations in
lake volume and depth indicate complete drainage within 50 h. In both basins, fields of relict gravel bedforms reflect sediment transport due to entrained lake-bed sediments. Thus, in addition to the general overview of drainage, the detailed temporal and spatial evolutions of drainage
parameters are reported, including for the locations of the bedform fields. Local flow above the bedforms is considered in relation to thresholds for sediment motion, bedform development, and orientations. Within the simple bathymetry of the Chuja Basin, the flow field was fairly uniform
with flow conducive to bedform evolution only occurring close to the exit from the basin, which accords with field evidence. In contrast, within the Kuray Basin, the flow responded sensitively to the complex bathymetry, which included rapid changes in flow direction due to interaction of the Kuray water with the jet-flow from Chuja, and as submerged ridges shoaled. Thus the Kuray flow field was complex but with time-dependent flow conditions in ccordance with bedform development. It is concluded that the location of the bedforms can be explained in terms of the flow modelling and suggestions are made as to how future drainage models might be improved.

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Accepted/In Press date: 28 April 2015
e-pub ahead of print date: 15 July 2015
Organisations: Earth Surface Dynamics

Identifiers

Local EPrints ID: 379966
URI: https://eprints.soton.ac.uk/id/eprint/379966
ISSN: 0020-6814
PURE UUID: 3c54713c-1565-423a-a582-95940142c84f

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Date deposited: 11 Aug 2015 13:27
Last modified: 18 Jul 2019 14:01

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