Abstract
Large Wood (LW) transport during floods presents known impacts on hydraulic risk, such as a higher probability of bridge clogging and the extension of flooded areas. In general, practical countermeasures are adopted to avoid the occlusion of bridge spans or reduce wood jamming. Retention structures, check dams upstream of critical sections or diverging panels at bridge piers are the most common. Numerical models simulating wood transport may be useful to understand LW dynamics, providing additional knowledge on the behaviour of transported wood and on the associated flood risk. The aim of this contribution is to validate the results obtained with two numerical models for LW transport in rivers, highlighting the requirements, strengths and limitations for their application to practical cases. Despite the progresses in developing numerical approaches, high resolution input data is required to properly calibrate and validate the results. However, this data are very often lacking. One exception is the Rienz River (Province of Bolzano), where a full-scale experiment on wood transport was performed by periodically acquiring topographical and
hydraulic data, as well as information about the displacement of tagged logs. The resulting observations contain the key information about the dynamics of LW motion and represent a benchmark dataset to be used for modelling. The application of two 2D Eulerian-Lagrangian models, Iber-Wood and ORSA2D_WT, to this case study enables the identification of the fundamental input data required for reliable simulations. The numerical simulations performed on the reference case try to identify which are the minimum data needed to provide acceptable results, avoiding time-consuming simulations; moreover, they can help in defining which parameters have the largest influence on the model results, setting guidelines for the simulation of LW transport.