Location And Extent of Snow Avalanches

Snow avalanches pose a significant threat not only winter recreationists, but roads, railways, and other infrastructure. Location and extent of avalanche starting zones are of great importance to estimating and forecasting the potential danger that avalanches may pose. I will summarize two published European papers, one from Switzerland, and one from Iceland. I chose papers from Europe as they have much more extensive mapping and GIS efforts thus far than the US. They also have better funding for such research. I also explored several recent publications from the United States to reference.

Specific to my research, I can integrate GIS in several ways. I can overlay raster layers on the area of Hyalite Canyon. Examples of raster layers I could make, as well as find through other resources, include elevation and precipitation per storm. Adding these layers will help differentiate precipitation patterns per each storm.

The greater the knowledge of precipitation per storm event, the better able avalanche forecasters and water resource managers can understand snow dynamics in the canyon.

GIS will also be a helpful skill if I choose to ever map avalanche paths. If I forecast for an avalanche center, I would like to map specific avalanche problems based on avalanche occurrence correlated with aspect of avalanche. Section I: Using GIS for Hazard Mapping in Switzerland The following addresses two papers that deal with GIS in avalanche hazard mapping and management. The first was a study implementing GIS mapping in Switzerland. Hazard maps have long been used in avalanche forecasting, particularly in areas (such as European villages) where extensive historical data is available.

Get quality help now

writer-Charlotte

Verified

Proficient in: Snow

4.7 (348)

“ Amazing as always, gave her a week to finish a big assignment and came through way ahead of time. ”

+84 relevant experts are online

Hire writer

In the winter of 1999, many large avalanches endangered settlements in Switzerland. Thanks to the aforementioned hazard maps available, loss of life and infrastructure was minimal, but also highlighted deficiencies in the existing avalanche hazard mapping procedure.

To overcome these deficiencies, new simulation methods and GIS mapping were applied, in order to avoid a similar situation (per the 1999 winter) in the future. GIS was used to identify and analyze avalanche area release zones. These zones determine friction parameters along the avalanche track, manage digital terrain data, and finally plot hazard maps. From these maps, run-out distance, speed, and deposits can be estimated. GIS can also be used to estimate potential release areas by association of traditional variables, such as slope and forest cover with variables particularly related to snow cover influence on topography. Additionally, a scale dependent roughness parameter and wind shelter parameter can account for varying winter topography and snow deposition patterns with increasing snow depth. The audience for this work includes builders (of housing and infrastructure) as well as forecasters, and even applicable to the public. The work was funded by the Swiss Federal Institute for Snow and Avalanche Research, and funding is provided by the Swiss government (i.e. taxpayers).

The researchers analyzed terrain maps at a scale of 1:10,000 and 1:5,000, and also analyzed aerial photos of avalanche terrain. A map where known historic avalanches were plotted , and additional information was gleaned from local knowledge. Climactic conditions were checked with data taken from observations over 20-60 years of observations. A DEM raster with a spatial resolution of 25m was used, which they found was sufficient for open slopes, but not detailed enough for steep gullies. To improve the quality of the DEM in these areas, structure lines (distinguishing ridge, gully, etc) where interpolated using an ARC tool that provides a linear altitude interpolation tool for breaklines. In this way, the points were interpolated according to their distance to the neighboring contour lines. Some data was created using models (the friction components, fracture zone and depth, and snow cover properties, calculating runout, etc). The avalanche track can be determined by GIS calculations involving the altitudes along the track profile and width of the avalanche track.

The width of track is determined by the closest distance of the track-line vertices to the width polygon arcs on each side of the track line. To highlight avalanche run out zones and potential release areas, the original DEM and a grid containing forested areas (extracted from a digital topography map). Any non-forested areas with a slope angle that was between 30° and 50° were then considered to be avalanche zones. This project proved to be successful as avalanche zones were digitized, and start zones were calculated and modeled accurately. They were able to produce conditions and model an avalanche similar to the 1999 incident. The GIS environment they established proved to be a powerful tool to specify all kinds of spatially varying input parameters, a challenging task. Section II: Using GIS for Avalanche Hazard Management in Iceland The second paper I reviewed was about the use of GIS in avalanche hazard management in Iceland.

The researchers first reviewed information regarding avalanche costs in Iceland over a 26-year period, and found the cost to be around 3.8 billion dollars. They created a GIS avalanche database consisting of spatial information relating avalanches and local terrain. The slope of a hillside is directly related to the possibility of avalanches. If the hillside is too steep, snow will not accumulate, or will sluff frequently, thereby lessening the dangers of avalanches in very steep areas. Similarly, terrain less than 25° is too flat to slide. Using TIN and contour lines to create a grid, a slope map could be calculated, while being able to highlight sloped of interest (between 25°-50°). Shading was applied (red-green) to better visualize steeper slopes (green- lesser angles, red- steeper angles). While reading this paper, I realized that GIS layers could store results of model calculations, fieldwork, and hazard zoning. Model results can be stored as layers and indicate the size and length of avalanches that occur along various paths.

These results, when combined with avalanche outlines, can delineate hazard zones, a very useful tool for forecasting future hazard events. This paper was successful as an extensive database was collected, and showed deficiencies in previous hazard maps. It was funded by the government of Iceland (i.e. taxpayers, again). They were able to digitize 50 years of avalanche data (Tracy,2013), a likely challenging task. All perimeters of these avalanches were digitized which means that their work can be built upon, in addition. They can be analyzed statistically with GIS methods, and patterns can be retroactively found. They also provided ways to analyze and compare real avalanche events. They also found potential release areas where no information of historic avalanche events is available. Discussion A GIS database is incredibly useful as more information can be added and applications written to analyze data within it.

New avalanches can be added, and any changes to avalanche paths or track can be updated. Aerial photographs of avalanches and paths could also be included. The layers and grids will be incorporated into applications to assist forecasters, and one day, likely be tools that the public can access as well. Both papers perform successful geospatial analyses, and create databases that can be built upon and used for areas in the future. Both also used different geospatial analysis methods and different models to arrive at similar results, which was interesting. GIS is established in the field of snow science, and when paired with various models, advanced analysis (see Tier 5, Competency Model, analysis and modeling, referenced below) can be performed. In many places throughout the US, use of GIS for avalanche mapping is still in its infancy; however, with examples like those above, more work and research is being done to include GIS data in avalanche mapping.

GIS analysis is also incredibly useful in that avalanche paths usually have a return period, and a pattern could be mapped particularly well, especially when paired with a model for snow cover. Currently, applications are being developed for smart phones that map frequent avalanche paths in an area and can overlay slope angle and avalanche danger rating over various aspects. Raster Layer Addition for Personal Project A raster layer that I would like to add to my part 1 study map would be a 1 arc-second DEM from the USGS National Map Database for the Hyalite area. I am choosing this layer to integrate into my map, as elevation is a key factor in determining snow patterns throughout a canyon (based on elevation and lapse rate, precipitation can be estimated).

References

1. Buhler, Y., Kumar, S., Veitainger, J., Christen, M., Stoffel, A., and Snehmani, 2013.
2. Automated identification of potential snow avalanche release areas based on digital elevation models, Natural Hazards and Earth System Science, 13, 132-13355.
3. Gruber, U., Maggiono, M. and Gruber, U., 2003, The influence of topographic parameters on avalanche release dimension and frequency, Cold Regions Science and Technology, 37, 407-419.
4. Gruber, U., 2007, Using GIS for Avalanche Mapping in Switzerland, Cold Regions Science and Technology, 41.
5. Schweizer, J., Jamieson, J., and Schneebeli, M., 2003. Snow avalanche formation, Reviews of Geophysics, 41.
6. Tracy, L., 2013, GIS in Avalanche Hazard Management, Official Release from Icelandic Meteorological Journal. Veitiner, J., Sovilla, B., and Purves, R., 2014.
7. Slab avalanche release area estimation: a new GIS tool, WSL Insititute for Snow and Avalanche Research SLF.
8. Clearinghouse Geospatial Competency Model, 2014 https://www.careeronestop.org/competencymodel/competency-models/geospatial-technology.aspx