Towards an automated detection of avalanche deposits using their directional properties

Abstract

Snow avalanches killed more people in the Swiss alpine area during the past decades than any other natural hazard. To further improve the avalanche prediction and the protection of people and infrastructure, information about the occurrence and the distribution of avalanche activity is crucial. Nevertheless this information is missing for large parts of the Alpine area. The surface roughness of avalanche deposits differs considerably from the adjacent undisturbed snow cover and is an important factor of the directional reflectance anisotropy. The undisturbed snow-cover exhibits a strong forward scattering, while the structure of an avalanche deposit causes shadow casting and tilt effects. Therefore, the observed reflectance of avalanche deposits and undisturbed snow cover is strongly dependent on the illumination- and viewing angles. This study demonstrates the potential of multiangular remote sensing data for detecting and mapping avalanche deposits. The results indicate, that air- or spaceborne multiangular sensors are suitable for rapid detection and mapping of avalanches in inaccessible and remote regions