Enhancing Flood Resilience: Sediment Management in Le Bez Torrent

In the canton of Bern, Switzerland, the “Le Bez” torrent is known for its flash floods, causing sediment and wood debris buildup in Villeret village settled on the alluvial fan. To mitigate this issue, a sediment/wood trap system is being implemented upstream. This system comprises two retention basins with a sill and vertical rack to retain wood debris, alongside a filter check dam equipped with hydraulic/mechanical controls to retain debris during major floods. The objective is to provide enough capacity to retain sediment during floods with over five years’ return period, striking a balance between effective retention and maintaining sediment transport during smaller discharges to prevent downstream bedload depletion. This study aims to find an efficient design of these basins using physical modelling.