Day 4

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Paper title Avalanche detection and mapping by satellite remote sensing
Authors
  1. Regula Frauenfelder Norwegian Geotechnical Institute Speaker
Form of presentation Poster
Topics
  • D1. Managing Risks
    • D1.01 Satellite EO for Geohazard Risks
Abstract text Today, remote sensing is key for the identification, quantification and monitoring of natural hazards. Recent developments in data collection techniques are producing imagery at previously unprecedented and unimaginable spatial, spectral, radiometric and temporal resolution. The advantages of using remotely sensed data vary by topic, but generally include safer evaluation of unstable and/or inaccessible regions, high spatial resolution, spatially continuous and multi-temporal mapping capabilities (change detection) and automated processing possibilities. Of course, as with every method, there are also disadvantages involved with the use of remotely sensed data. These are generally in relation to the lack of ground truth data available during an analysis and to data acquisition costs.

Here we present the use of remote sensing for snow avalanche detection. During the winter season snow avalanches pose a risk to settlements and infrastructure in mountainous regions world-wide. Avalanches affect populated areas and parts of the transport network every year, leading to the damage of buildings and infrastructure and sometimes also to the loss of lives. Avalanche observations are one of the most prized information that avalanche forecasters seek, to form their opinion on the avalanche hazard. Unfortunately, we are only aware of a small fraction of the avalanche occurrences. Novel applications using new Earth Observation satellite capabilities are, therefore, important tools to detect and map avalanches and to characterize avalanche terrain. Detection, mapping and characterisation of avalanches are important for expanding avalanche data inventories. These enable the validation and quality assessment of avalanche danger warnings issued by avalanche warning services.

For an avalanche expert, it takes several hours to visually inspect and map individual avalanche paths. At times this task cannot be accomplished for several days after an avalanche event. Several earlier studies have shown that data from space-borne optical sensors as well as from radar sensors can be used to detect and map avalanche debris. Being able to remotely detect and record avalanche releases aids to target mitigation strategies. While forecasts for avalanche risk management rely mainly on meteorological forecasts, snow cover observations and expert knowledge, satellite-based remote sensing has a large potential in now- and hind-casting. The area covered by remote sensing approaches can be regional to local and stretch over areas where traditionally such measurements are both difficult and time-consuming, or areas that are not accessible at all for in-situ observations.

Here we present the results of several studies on how the analysis of satellite data can yield hind-cast avalanche inventory observations on a regional scale. We have explored the use of imagery from high-resolution and very-high resolution optical satellite data (WorldView, QuickBird, Pléiades) and high-resolution SAR data (Radarsat-2, Sentinel-1), applying automated image segmentation and classification. The results are validated by manual expert mapping.