Wood blockage and sediment transport at inclined bar screens

Abstract

Semi-permeable sediment traps are designed to retain sediment during large floods and enable sediment transport continuity during ordinary floods by combining two barriers with a guiding channel. During floods, not only sediment but also large wood (LW) can be transported, that may block the inclined bar screen (mechanical barrier) and inhibit sediment transport. The design of the inclined bar screen has not been tested with LW. We conducted a first set of simplified flume experiments to study the effect of (1) initial conditions, (2) bar screen design, and (3) LW volume on sediment transport. First results demonstrate that a LW volume blocking 20% of the flow cross-section is sufficient to reduce sediment transport by 50%. Hence, LW volume is a relevant parameter for the design of inclined bar screens. We provide future research ideas to enable the local separation of LW and sediment.