Abstract
Windstorm events are the primary natural disturbances in the Italian Alps. The combined effects of climate change and windstorm-induced land cover changes are expected to significantly influence the hydrological and erosional responses of forested watersheds. This study presents preliminary results from both plot-scale monitoring and large-scale modeling conducted in the subalpine catchment of Val d'Ega (BZ). At the plot scale, runoff and erosion were monitored in 4.5m x 6m plots, which were characterized by either natural or artificial regeneration following storm events. Water and sediment yields were measured across 75 rainfall events from 2021 to 2023. Initial results reveal considerable inter-plot variability in runoff and erosion dynamics, with artificially regenerated plots exhibiting higher water and sediment transport rates. Furthermore, the pre-storm soil conditions and microtopography appear to play a significant role in these dynamics. At the larger scale, surface runoff and sediment yield were evaluated using the SWAT model, comparing pre- and post-Vaia windstorm (October 2018) conditions. Four different scenarios, varying in both spatial extent and scale of land use changes, were assessed. Results indicate a 3% to 16% increase in annual surface runoff in scenarios accounting for land cover changes, compared to the ‘no-damage’ scenario. Consequently, sediment yield increased by up to four times, with the greatest impact observed in subbasins most affected by the Vaia windstorm. These findings highlight the need for further investigation into effective management strategies in response to the evolving post-windstorm hydrological and erosional dynamics.