Il legname in alveo nei torrenti alpini: analisi quantitativa e modellazione GIS

The present work analyzes the wood presences in Dolomites streams. The processes that contribute to the formation, input, and transfer of such material in network channel have been investigated. Main task is to assess for guidance planning risk management in mountain areas. The study sites are represented by 13 mountain basins (drainage area ranging from 1 to 70 Km2), located in the upper part of Cordevole watershed basin (Province of Belluno). More than 9,000 wood elements were counted during the field survey. Wood storage is highly variable (8-106 m3 per hectare of streambed area), but a significant inverse relationship with drainage area is evident, as well as with occurrence of hillslope instabilities. Median log diameters do not vary considerably among the study basins (0.08 – 0.13 m), whereas large differences exist with regard to log length (0.79 – 3,75 m). The ratio between log length and the average channel width remains close to 1 for channels < 3rd order (A