KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 天山大陆性雪气候雪崩的特点及其形成机制 | |
| Alternative Title | Characteristics and Formation Mechanism of Snow Avalanche in Continental Snow Climate—Tianshan Mountains |
| 郝建盛 | |
| Subtype | 博士 |
| Thesis Advisor | 李兰海 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 雪崩灾害 诱发因素 诱发机制 雪崩风险评估 雪崩预警 Avalanche disaster Triggering factors Triggering mechanism Avalanche hazard assessment Avalanche forecasting |
| Abstract | 雪崩与滑坡、泥石流、和冰崩类似，是一种由重力驱动的地表流。雪崩具有突发性、难以预测性、破坏力巨大等特点，严重威胁山区交通道路、牧区、旅游区和矿区安全，经常造成基础设施破坏和人畜死伤，从而严重阻碍山区社会和经济的可持续发展。随着气候变化、自然环境变化和人类活动不断向山区扩展，暴露在雪崩风险之下的人口日趋增多，因此雪崩灾害的防治管理需求正在不断增加以保障山区的社会经济可持续发展。雪崩预警和风险评估是雪崩灾害的防治管理的有利手段。天山及其周边大陆性雪气候山区居民深受雪崩荼害，随着该区域社会经济发展，通过构建雪崩防治工程已经难以满足雪崩灾害的防治管理需求。然而由于缺乏对雪崩诱发机理的认识给该区域开展雪崩预警和风险评估带来极大的困难。所以为进一步加强雪崩灾害的防治管理，以下问题亟待解决：1）大陆性雪气候区雪崩类型、发生频率和风险随时间变化的特征及其关键影响因素；2） 降雪、气温升高等外界因素诱发山坡雪层剪切断裂的机理。基于以上问题，本研究通过收集天山巩乃斯河流域雪崩频发区的气象、土壤、地形地貌、积雪和雪崩数据， 分析不同积雪和气象等自然情景下大陆性雪气候雪崩的主要诱发因素，揭示雪崩风险的时空分布规律和影响雪崩风险的关键因素；基于摩尔-库伦剪切理论结合雪层断裂机制， 分析不同诱发因素引起雪层剪切断裂破坏模式，揭示不同诱发因素作用下各种类型雪崩的诱发机制。然后基于雪崩的诱发机制构建雪崩的预警模型，并在天山巩乃斯河流域雪崩频发区进行调试和应用。研究的主要结论如下：1）雪崩发生在每年的 11 月初到次年 3 月底，集中在 29°到 48°范围内的斜坡或沟槽处，发生区地表植被稀疏。雪崩由强降雪、温度剧烈增加、强风、地震等因素诱发形成。50%的雪崩事件是由降雪诱发，并且多发生在降雪量超过 20mm的降雪事件后。 27%的雪崩事件是由温度升高引起，并且多发生在春季温度剧增期间。2） 雪场物理特性、土壤特性和气温随时间不断地演变引起雪崩风险随时间的变化呈现单峰波动。雪崩的风险度在雪深最深，气温呈现回升的二月下半月呈现最大，因此该时期为雪崩预防和防治的加强期。3） 在一个雪季中，不同类型雪崩的危害程度和活跃时间段具有显著差异。大陆性雪气候表层雪崩的释放频率和风险要高于全层雪崩。表层土壤温度高于或等于 0℃，表层土壤含水率高于 0.32 m3/m3，雪场中无可持续脆弱层的时期盛行全层雪崩，其他时期盛行表层雪崩。4） 不同积雪、土壤特性和天气情境下，雪层的剪切强度和剪切应力的差异性变化导致各类型雪崩的诱发机制呈现不同。基于降雪诱发雪崩的诱发机制构建的降雪诱发表层雪崩预警模型（SFAW）能够捕获 75%的区域性雪崩事件，具有良好的雪崩事件和非雪崩事件识别能力。论文在雪崩灾害领域的主要创新点，可归纳为如下：1）定量描述大陆性雪气候积雪、土壤特性和气象等因素与雪崩发生类型和发生概率之间的关系，原创性提出通过实时监测积雪、气象和土壤特性预判潜在雪崩类型的方法。2）提出雪层剪切破坏的五种破坏模式，然后结合各类雪崩类型的特征，揭示了降雪、温度升高和强风等不同诱发情景下不同类型雪崩的诱发机制。基于目前的研究，未来以天山巩乃斯河流域雪崩频发区为示范区域，构建雪崩灾害风险评估、雪崩预警和雪崩防治工程为一体的雪崩灾害防治体系，为其他地区提供参考从而减少雪崩灾害损失。气候变化改变区域积雪特性和气候，将增加对雪崩风险管理的难度，因此评估气候变化对雪崩的风险的影响将在未来工作中展开。 |
| Other Abstract | Snow avalanches, similar to ice avalanches, landslides, and debris flows, arecommon natural phenomena driven by the gravity in snow-covered mountain regions.Among these, snow avalanches are a major natural disaster with the characteristics ofsudden destruction and difficult prediction. It seriously threatens roads, mining andtouristic areas in the mountainous regions and often causes the destruction ofinfrastructure and human casualties. Climate change and human activities enhanceavalanche hazard. Also, as human settlement, transportation network, tourism,agricultural and pastoral areas continue to expand to the alpine mountains， more andmore people are exposed to avalanche hazard. For this, there is an increasing need foravalanche prevention and management through avalanche warning and riskassessment. Tianshan Mountain and its surrounding continental snow climatemountainous regions are deeply affected by avalanches. With the social and economicdevelopment of this region, traditional avalanche prevention facilities cannot meet theneeds of avalanche prevention and management. Meanwhile, it is difficult to carry outavalanche warning and risk assessment in this area due to the lack of understanding ofthe mechanism of avalanche formation. Therefore, in order to strengthen theprevention and management of avalanche disaster, the following problems need to besolved urgently:1） What are the characteristics of avalanche types, frequency and risk incontinental snow climate zones and their key influencing factors.2） What mechanism causes snow layer shear fracture induced by snowfall,temperature rise and other factors.To solve the above problems, the data related to meteorology, soil, terrain,snowpack and avalanche in the Kunse River Valley, located at the middle section ofTianshan Mountains were collected. The main factors triggering avalanche events incontinental snow climate under different snowpack and meteorological conditions were analyzed, and the temporal and spatial distribution of avalanche hazard and thekey factors affecting avalanche hazard were revealed. Based on the Mohr-Coulombyielding criteria and the snow layer fracture mechanism, the snow layer failure modescaused by different triggering factors were investigated, and the triggering mechanismof various types of avalanches under the action of different triggering factors wererevealed. An avalanche warning model was also developed based on the triggeringmechanism of avalanche, which was applied to the study area.The following conclusions are reached:1） Avalanches occurred from the beginning of November to the end of Marchand concentrated in slopes with inclinations between 29° to 48° in a sparse surfacevegetation. Avalanches were triggered by heavy snowfall, a sharp increase intemperature, strong winds, earthquakes and other factors. Half of all avalanche eventswere triggered by snowfall, and there is high probability of avalanche release withsnowfall exceeding 20mm during a snowfall period. Twenty-seven percent ofavalanche events were caused by a sharp increase in temperature, and consecutive risein temperature implied a high probability of temperature-rise-triggered avalancherelease.2） The avalanche hazard showed a single peak fluctuation with time during asnow season due to evolution of snowpack physical characteristics, soil characteristicsand air temperature. The avalanche hazard was greatest in the second half of February,when the snow is deepest associated with the temperature rise. Therefore, avalancheprevention and management should be strengthened during this period.3） The hazard and active period of different types of avalanches variedsignificantly during a snow season. The frequency of surface-layer avalanche releasewas higher than that full-depth avalanche in continental snow season. Full-depthavalanche prevailed in periods when snowpack does not persist weak layer, thesurface soil temperature was higher than or equal to 0℃ and the surface soil watercontent was higher than 0.32 m3/m3.4） It was found that under different snow, soil characteristics and weatherconditions, the triggering mechanisms of avalanche was different due to the differential variation of shear strength and shear stress in the snow layer. Thesnowfall-triggered avalanche warning model （ SFAW） was developed based on themechanism of snowfall-triggering avalanche. The model could capture 75% ofregional avalanche events, and has a good ability to identify avalanche events andnon-avalanche events.The novelties of the study were as follows:1） The relationship between continental snow climate, snow cover, soilcharacteristics, meteorological factors, the types of avalanche and probability ofavalanche release was quantitatively determined. An original method for predictingpotential avalanche types by real-time monitoring of snowpack, soil characteristicsand meteorology was developed.2） Five snow layer shear failure modes were classified. According to thecharacteristics of various avalanche types combined with snow layer shear failuremode, the triggering mechanism of different types of avalanches under the action ofdifferent triggering factors were revealed.Based on the outcomes from this study, an avalanche disaster prevention systemintegrating avalanche risk assessment, avalanche forecasting and avalancheprevention engineering can be developed in the Kunse River Valley in the further toprovide reference for other areas. Climate change will change regional environmentaland snowpack characteristics, which will increase the difficulty for avalanche riskmanagement. Therefore, assessing the impact of climate change on avalanche riskshould be carried out in future work. |
| Subject Area | 自然地理学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15406 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 郝建盛. 天山大陆性雪气候雪崩的特点及其形成机制[D]. 北京. 中国科学院大学,2020. |
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