ABSTRACT
Large woody debris accumulated or impacting at bridge piers may exacerbate localised scour, causing serious problems to the stability of the structure, and increase flood risk. Furthermore, costs for removal of accumulated debris after an event are generally expensive and require disruption to the communities (e.g. traffic interruptions). Recent research focused on the formation of debris jams and their effects. Comparatively less research has been focused on reduction and mitigation of such effects. Here we propose and teste a novel type of a structure for debris retention in medium or small-sized rivers in order to minimise the amount of debris transported in the downstream reach. The structure, formed by a net of wires and placed in the main channel of the river, was tested at flume scale for the efficiency in trapping woody debris out of 100 elements individually released. The structure was tested for different debris lengths and different velocities. Results showed that retention of debris ranged between 90 and 99% of the total amount of debris elements released. The highest retention occurred for the slowest velocities, while it slightly reduced with increase of flow velocity. The development of this structure may open avenues for low-cost and highly efficient measures for debris-related risks reduction.
