Work

Large wood recruitment in the Tegnas torrent (Italy): The impact of the Vaia storm and the role of the riparian forest structure

Year: 2025

Type: article

Abstract: This study investigates large wood (LW) recruitment from the floodplain to the channel in a mountain stream in northeastern Italy, following the exceptional 2018 flood triggered by the Vaia Storm, a severe windstorm and intense precipitation event. It aims to quantify in‐channel LW loads, estimate floodplain‐recruited LW volumes, explore the links between hydraulic forcing, sediment balance, lateral connectivity and recruitment and explore the potential of numerical modelling in such a context. The study focuses on a 9.5 km segment of the Tegnas Torrent, a mountain stream with a catchment area of 52 km 2 . Post‐event in‐channel LW was quantified through field surveys across sampling segments, while to assess recruitment volumes, a combination of pre‐ and post‐event remote sensing data and 2019 field plots was used to estimate standing volumes and identify trees eroded by flood‐induced channel widening. At the reach scale, key variables related to hydraulic forcing, sediment dynamics and lateral connectivity were evaluated, and correlations with LW recruitment were analysed. Finally, a two‐dimensional numerical model was applied to simulate and compare the flood‐driven erosion and wood recruitment. The total in‐channel LW volume was estimated at 496 m 3 ± 220 m 3 , averaging 18 m 3 ha −1 , which is consistent with values from nearby, although undisturbed, mountain streams. In contrast, 2080 m 3 (132 m 3 ha −1 ) of wood was recruited due to lateral channel widening. Our findings revealed that recruitment is influenced by complex factors, with limited correlation to sediment dynamics and hydraulic energy. Wider lateral erosion does not always lead to higher recruitment, as the riparian corridor's forest composition and structure play a key role. The numerical model provided reasonable estimates of channel widening and associated LW recruitment, making it a useful tool for approximating potential flood‐induced planform changes. However, for more accurate results, further refinement in vegetation and sediment transport modelling is necessary.

Source: Earth Surface Processes and Landforms

DOI: 10.1002/esp.70168

Authors: Lorenzo Martini, Giacomo Pellegrini, Guglielmo Stecca, Lorenzo Picco

Institutions: University of Padua, University of Lincoln, Earth Sciences New Zealand, National Institute of Water and Atmospheric Research

Language: English

Topic: Hydrology and Sediment Transport Processes

Subfield: Ecology

Field: Environmental Science

Domain: Physical Sciences

SDG: Life on land

Open Access status: hybrid

Estimated APC paid: $5,330