Timing, Size, and Impact of Snow Avalanches

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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.