Pellegrini G.; Cazorzi A.; Rainato R.; Martini L.; Picco L.; Cavalli M., 2020, The morphological response of an alpine catchment to a large infrequent disturbance, 10th Conference on Fluvial Hydraulics, pp. 448–454, Delft, Netherlands, 7-10/07/2020,
URL: http://www.cnr.it/prodotto/i/458130

Large disturbances highly affect the morphological settings and the dynamics of mountain river basins, above all if they are dealing with water and wind. The Vaia storm that hit the northeastern part of Italy in late October 2018 caused the activation of new sediment sources, the generation of widespread instabilities and the destruction of hectares. The following research focuses on the Tegnas River basin (Belluno Province) and investigates the morphological changes of the active channel after the Vaia storm as well as the connectivity before the event. Both field surveys and remote sensing data were used to carry out DoD analysis (DEM of difference) and IC (Index of Connectivity) computation. On the one hand, evidence of erosion was identified in the upstream portion of the basin, especially on the Bordina Stream sub-catchment, where the riverbed deepened by more than 3.0 m. On the other hand, the event caused deposition of more than 1.5 m along the valley floor of the Tegnas River basin, modifying catchment-scale sediment connectivity and highlighting the different response of the basin according to the channel steepness. For this reason, in the forthcoming future, second-step consequences will occur producing cascading processes affecting the morphology and the equilibrium of the entire system. Therefore, the comprehension of these mechanisms will give important tips for future management strategies that will permit to decrease risks and to guarantee the maintenance of the natural appearance of the San Lucano valley.

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