Integration of Dendrochronology and GIS Techniques to Study Avalanche Phenomena

Snow avalanches are one of the main natural hazards for human activities and infrastructures in the Alpine region. The risk potential of avalanches hazards has increased in the last years because of the opening up of the Alps for tourism. Information about past avalanches frequency and dynamic characteristics is a prerequisite for planning and management at a landscape level in the Alps. Such information is only scarcely provided by historical records, because their spatio-temporal resolution is limited: the longest gauge records capture only a limited portion of the range of possible natural avalanche frequency. The paper illustrates the results of a research carried out in order to evaluate the avalanche risk with the aid of GIS and dendrochronological techniques in an area situated in the north-west part of Trentino Region (North Italy). GRASS GIS has been used to obtain an avalanche risk map based on morphological and vegetation features which has been compared with CLPV (possible avalanche location map). Dendrochronological techniques have been used to analyse cores taken from trees (GPS positioned) growing within the avalanche tracks. The analysis of several features recorded in tree rings (anomalies such as scars, compression wood, traumatic resin canals, abrupt growth releases and reduction and/or the tree death date) and the investigation of the vegetation in avalanche paths (vegetation shape, emission of new stems) have proven to be effective to deduce information about past occurrences. Integrating dendrochronological and GIS techniques it is possible to reconstruct historical data, to map old avalanche paths in each year and to correct CLPV.