Timing, Size, and Impact of Snow Avalanches

有必要改进对雪崩释放时间、冲击压力和跳动距离的预测，以减少雪崩对人类社会的影响。这个项目将使用实验和理论相结合的方法来调查雪崩的时间、大小和影响。具体目标是：(1)跟踪雪坡稳定性的演变，以改进对雪崩释放时间和大小的预测；(2)将雪崩释放模型的输出与动态流动模型相结合，以估计沿特定几何形状的路径的冲击压力和跳动距离；(3)将斜坡稳定性模型的输入与预测的中尺度气候模型的输出相结合，并开发用于预测区域尺度的雪崩的工具。将利用实地观察的结果和现有的过去天气和雪崩活动存档数据库进行模型开发和验证。雪崩引发和后续流动的物理模型需要详细的瞬变知识，以及对雪不断演变的力学性质的三维描述，这需要特殊的输入数据，而这些数据通常是无法获得的。简化假设是必要的，以开发出不仅现实而且足够容易处理的模型，以便它们可以用于业务预测。模型开发的指导约束是，只有有效的近似和最少的数据输入是可接受的。复杂性降低的模型的结果将与观测结果进行比较，以确定能够充分模拟雪崩行为的最简单可行的模型。雪崩直接影响人们，造成伤亡，限制交通，摧毁建筑物和村庄，限制进入活动区域，并改变自然环境。尽管雪崩的频率在过去一个世纪里没有明显变化，但随着越来越多的人在山区生活、工作和旅行，危险增加了。社会的间接成本也很高，例如与缓解、诉讼、保险以及旅行和商业机会损失相关的成本。这项研究的总体目标是提高公共安全，降低与雪崩相关的成本。

There is a need to improve predictions of the timing of avalanche release, impact pressures, and run-out distances to reduce the impact of avalanches on human society. This project will investigate the timing, size and impact of snow avalanches using a combined experimental and theoretical approach. Specific objectives are to: (i) track the evolution of snow slope stability in order to improve predictions of the timing and size of avalanche release; (ii) couple output from a model of avalanche release to a dynamic flow model in order estimate impact pressures and run-out distances along paths of specified geometry; (iii) couple the input of the slope stability model to output from a predictive meso-scale climate model and develop tools for forecasting avalanches on a regional scale. Model development and verification will be done using results from field observations and existing archived databases of past weather and avalanche activity. Physical models of avalanche initiation and subsequent flow require detailed knowledge of transients as well as a three-dimensional description of the evolving mechanical properties of snow, which requires extraordinary input data that are not generally available. Simplifying assumptions are necessary to develop models that are not only realistic but also sufficiently tractable so that they can be used for operational forecasting. Guiding constraints for model development are that only valid approximations and minimal data inputs are acceptable. Results from models of decreasing complexity will be compared with observations to identify the simplest workable models that adequately simulate avalanche behavior. Snow avalanches directly affect people by causing injury or death, restricting transportation, destroying structures and villages, limiting access to areas of activity and altering the natural environment. Although the frequency of avalanches has not changed significantly over the past century, the hazard has increased as more people live, work and travel in mountain regions. Indirect costs to society such as those associated with mitigation, litigation, insurance, and loss of both travel and business opportunities are also high. The overall goal of this research is to increase public safety and reduce costs associated with snow avalanches.