Critical hydrologic conditions for overflow burst of moraine lake

Floodwater and debris flow caused by glacial lake burst is an important land process and a serious mountain disaster in glacial area of Xizang (Tibet) Autonomous Region, and the overflow burst is mainly caused by glacial landslide falling into moraine lake. On the premise that moraine lake is full,...

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Bibliographic Details
Published in:Chinese geographical science 2004, Vol.14 (1), p.39-47
Main Authors: Jiang, Zhong-xin, Cui, Peng, Jiang, Liang-wei
Format: Article
Language:English
Subjects:
Glaciers
Hydrology
Lakes
Studies
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Summary:Floodwater and debris flow caused by glacial lake burst is an important land process and a serious mountain disaster in glacial area of Xizang (Tibet) Autonomous Region, and the overflow burst is mainly caused by glacial landslide falling into moraine lake. On the premise that moraine lake is full, instantaneous burst in part of the lake bank happens, as flow velocity at burst mouth caused by overflow head is higher than threshold flow velocity of glacial till. Under some supposes, d ^sub 90^ and d ^sub 10^ of the glacial till in the bank were used as the threshold sizes of coarse and fine grains respectively. Thus, the formula of calculating threshold flow velocity of uniform sand was simplified, and threshold flow velocity of glacial till was calculated with the formula. Then, with synthesis formula calculating flow velocity of instantaneous part burst, flow velocity at overflow burst mouth was calculated, and calculation formula of critical height (H ^sub 0^) of overflow head was derived. Overflow head was caused by volume and surge of glacial landslide falling into moraine lake, calculation formulas of ascendant height (H ^sub 1^) of lake water surface and surge height (H ^sub 2^) on burst mouth caused by glacial landslide falling into moraine lake were derived. To sum up, critical hydrologic conditions of moraine lake burst with overflow form are: the burst is inevitable as H ^sub 1^>H ^sub 0^; the burst is possible as H ^sub 1^H ^sub 0^; the burst is impossible as (H ^sub 1^+H ^sub 2^)
ISSN:1002-0063
1993-064X
DOI:10.1007/s11769-004-0007-1