Des Ursulines Building
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Snow avalanches are the deadliest natural hazard in Canada. Avalanche forecast operations rely mainly on punctual information to extrapolate the avalanche hazard and represent the main uncertainty in avalanche forecasting. Geostatistical modelling can interpolate the snow stability with topographic indicators. Significant variability remains and this could be explained by microtopographic indicators. The general stability of a slope has been modeled by introducing a spatial variability in the cohesion of the weak layer. The slab thickness, key element for the stability, is considered fixed in this model, but shows an important spatial variability in the field. This mechanical model describes the general stability, and could be compared to the classical methods used in avalanche forecasting. The ALPINE 3D model is used to simulate the stratigraphy from meteorological data and the topography. It represent a promising tool for avalanche forecasting but requires to be tested in Canada.
The main objective of the research project is to spatially model the stability of the snowpack at the scale of the slope. The main objective is based on four specific objectives: 1) Estimate the influence of microtopography on the spatial occurrence of snowpack stability. 2) Model the stability of a slope in a 2 / 3D mechanical model by integrating the slab thickness variation. 3) Evaluate the representability from stability test results of a snow profile with respect to the overall stability of the slope. 4) Measure the performance of the ALPINE 3D model to simulate the mechanical properties of the snowpack in an operational context of avalanche forecasting in Canada.
Research will be conducted at Mt. Fidelity in Roger Pass (BC) and Mt Albert in the Chic-Chocs (QC). Two slopes will be studied in each of the study area. They represent two important areas of avalanche forecasting operations in Canada.
The acquisition of a geospatial dataset is essential for all three types of modelling. The topography and snow surface will be measured from a portable terrestrial LiDAR. Microtopographic indicators will be derived from the digital terrain model. Snow profile observations and stability tests will also be conducted. Finally, snow vertical penetration resistance profiles, measured with a high-resolution penetrometer (SnowMicroPen) and georeferenced, will also be realized. Snowpack stability parameters will be derived from the SnowMicroPen vertical resistance profile. The geospatial dataset will provide the inputs required for model development and validation. Automated weather stations are present in both study areas, and will also provide meteorological inputs for the ALPINE 3D model.
Geostatistical modelling can estimate the influence of microtopographic indicators such as the shape of the terrain, wind-sheltered areas or the proximity of vegetation or rocky outcrop to predict the spatial occurrence of instability. The mechanical modelling, finite element 2D/3D parametric analysis, will allow to better understand the influence of the spatial variation of slab thickness on the general stability of a slope. Stability test results and observations of a typical, often punctual and unique snow profile on the slope will be put into perspective with respect to overall stability. This can be used to criticize the choice of the location and the weight that is attributed to a specific observation of the snowpack in an avalanche forecast context. The geospatial dataset will allow validation of ALPINE 3D model outputs and measure the model performance with the low density of weather stations installed in Canada.