Timing, Size, and Impact of Snow Avalanches

有必要改进雪崩释放时间、冲击压力和流出距离的预测，以减少雪崩对人类社会的影响。 该项目将采用实验和理论相结合的方法研究雪崩的时间、规模和影响。具体目标是：（i）跟踪雪坡稳定性的演变，以改进雪崩释放的时间和大小的预测;（ii）将雪崩释放模型的输出耦合到动态流动模型，以估计沿着指定几何形状的路径的冲击压力和跑出距离; ㈢将斜坡稳定性模型的输入与预测性中尺度气候模型的输出结合起来，并开发在区域范围内预测雪崩的工具。模型的开发和验证将利用实地观测结果和过去天气和雪崩活动的现有存档数据库进行。雪崩开始和随后的流动的物理模型需要详细的瞬态知识，以及不断变化的雪的力学性质的三维描述，这需要非凡的输入数据，通常是不可用的。简化假设是必要的，以制定模型，不仅是现实的，但也足够容易处理，使他们可以用于业务预测。模型开发的指导约束是，只有有效的近似值和最小的数据输入是可接受的。从模型的复杂性降低的结果将与观察比较，以确定最简单的可行的模型，充分模拟雪崩的行为。雪崩直接影响到人们，造成伤亡，限制运输，摧毁建筑物和村庄，限制进入活动地区，改变自然环境。虽然雪崩的频率在过去世纪没有显著变化，但随着越来越多的人在山区生活、工作和旅行，雪崩的危险性有所增加。社会的间接成本，如与减轻、诉讼、保险以及旅行和商业机会的损失有关的成本也很高。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.