Abstract
Abstract. To make first-order estimates of the probability of moraine-dammed lake outburst flood (MDLOF) and prioritize the probabilities of breaching posed by potentially dangerous moraine-dammed lakes (PDMDLs) in the Chinese Himalayas, an objective approach is presented. We first select five indicators to identify PDMDLs according to four predesigned criteria. The climatic background was regarded as the climatic precondition of the moraine-dam failure, and under different climatic preconditions, we distinguish the trigger mechanisms of MDLOFs and subdivide them into 17 possible breach modes, with each mode having three or four components; we combined the precondition, modes and components to construct a decision-making tree of moraine-dam failure. Conversion guidelines were established so as to quantify the probabilities of components of a breach mode employing the historic performance method combined with expert knowledge and experience. The region of the Chinese Himalayas was chosen as a study area where there have been frequent MDLOFs in recent decades. The results show that the breaching probabilities (P) of 142 PDMDLs range from 0.037 to 0.345, and they can be further categorized as 43 lakes with very high breach probabilities (P ≥ 0.24), 47 lakes with high breach probabilities (0.18 ≤ P < 0.24), 24 lakes with mid-level breach probabilities (0.12 ≤ P < 0.18), 24 lakes with low breach probabilities (0.06 ≤ P < 0.12), and four lakes with very low breach probabilities (p < 0.06).
Highlights
The moraine-dammed lake outburst flood (MDLOF) is a category of glacial lake outburst flood (GLOF) in which flood/debris flow is triggered by the failure of a morainedammed lake
Photogramparameters of the moraine dam were originally obtained from metric measurements may be inaccurate owing to limitaaerial photographs taken in the 1970s and 1980s; tions imposed by aerial photography and the ASTER image we take the data as representative of the 2000s when calculat- scale, object clarity, and the skill of the interpreter
The region of the Chinese Himalayas was chosen as an area where there have been frequent MDLOFs in recent decades
Summary
The moraine-dammed lake outburst flood (MDLOF) is a category of glacial lake outburst flood (GLOF) in which flood/debris flow is triggered by the failure of a morainedammed lake. With widespread glacier retreat on the one hand and the growing population living close to high mountains on the other, there are more potentially dangerous morainedammed lakes (PDMDLs) appearing in glaciated regions (Clague and Evans, 2000; Richardson and Reynolds, 2000; Bajracharya and Mool, 2009). Wang et al.: An approach for estimating the breach probabilities of moraine-dammed lakes 87 and bridges and farmland both in Nepal and China (Lv et al, 1999; Mool et al, 2001a). X. Wang et al.: An approach for estimating the breach probabilities of moraine-dammed lakes owing to the westward decrease in precipitation. Another notorious disaster was the failure of Zhangzangbu in 1981, which killed more than 200 people and destroyed power stations, roads, bridges and farmland both in Nepal and China (Lv et al, 1999; Mool et al, 2001a)
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