藏东南典型冰湖溃决机制及危险性研究

我国西藏地区冰湖分布十分广泛,随着时间的推移,气温逐渐升高,一些冰湖出现消融现象,部分冰湖溃决直接导致灾害级联效应产生,进一步诱发了洪水、泥石流等次生灾害,因此及时开展冰湖溃决机制及其危险性研究十分必要。为了更好地详细分析冰湖溃决的机制及致灾危险性模式,重点选取西藏波密县米堆沟泥石流的源头光谢错为研究对象,开展了野外调查取样、室内物理实验及高精度遥感解译等一系列工作,分析结果表明光谢错溃决外因是由异常气候和水文条件诱发的,内因是在终碛堤溃决过程中存在溢流型和管涌型两种机制。光谢错溃决后逐步完成了由洪水向稀性泥石流的转变过程,泥石流的运移严重威胁到沟道两岸村庄、道路及耕地的安全。通过对光谢错溃决机制的研究能够为藏东南地区冰湖溃决的防治及预警提供科学的依据。

Mechanism and hazards of typical glacier-lake burst in Southeastern Tibet

Many glacier lakes are distributed in Tibet, China. With the passage of time, the temperature gradually raises, and some glacier lakes begin to melt. Their bursts will directly result in disastrous cascade effects and induce secondary disasters such as flood and debris flow. Therefore, it is imperative to timely carry out the study on the mechanism and hazards of glacier lake bursts. In order to better analyze the mechanism and hazard models of glacier lake bursts, we selected the Guangxiecuo glacier lake of Midui Gully in Tibet as the research object, and conducted a series of work including field investigation and sampling, indoor physical experiment, and high-resolution remote-sensing interpretation. The analysis results showed that the burst of Guangxiecuo lake was externally caused by abnormal climate and hydrological conditions and internally caused by the overflow-type and piping-type mechanisms during the burst of the terminal moraine dam. After the burst, the flood gradually transitioned to debris flow. The migration of debris flow seriously threatens the villages, roads, and cultivated land on both sides of the channel. The mechanism research can provide scientific basis for prevention and early warning of glacier lake bursts in the future.