Influence of large wood transport on river bed structuring processes in steep river reaches

Large wood (LW) has an influence on river morphology and sediment dynamics. Protruding blocks might trap LW and allow the formation of local deposits and scour. Such blocks are used as macro-roughness elements in river engineering structures to protect against bed erosion. We conducted three series of flume experiments investigating the influence LW on the bed morphology and stability of a dynamic ramp. LW deposits formed around protruding blocks and persisted until these were fully submerged. The altered flow conditions downstream of the deposits influenced the erosion of the bed material. The effect was pronounced upon increased hydraulic loading, leading to a formation of persistent and distinct alternate bar features. The final stability of the structure was not compromised by the presence of LW.