Transport of large woody debris in the presence of obstacles

Flume experiments were carried out to investigate the motion of large woody debris (LWD) in rivers as influenced by the presence of obstacles. Non-rooted, defoliated LWD was modelled by placing properly scaled wooden dowels placed into controlled water flow. Obstacles were represented by wooden rods randomly placed into the flume with a specified probability distribution. The results provide the probability of lodging of the dowels and statistics of the distance travelled. Their relationships with flow rate and depth, dowel length and spatial density of the obstacles is explored. This yields a general theoretical framework to approach LWD transport in rivers by combining random factors with deterministic dimensionless variables.