Abstract
Large wood (LW) represents one of the main problems for risk prediction in Alpine streams, mostly because of its potential to clog bridges, culverts and narrow sections during flood events. In order to prevent wood from reaching critical sections, wood-trapping structures have long been built, but very often these works have been implemented without a rationale procedure and thus their efficiency has not been satisfactory. This paper presents a case study (the Rienz river just upstream of Bruneck, South Tyrol, Italy) where the design of a system (two structures) for wood trapping entailed – before structure and filter sizing – the determination of LW volumes from the hillslopes and from the river corridor, the definition of flood event scenarios, and hydraulic and morphodynamic modeling. The minimization of environmental impacts and the social acceptance of the structures were finally achieved before the actual implementation of the system.