2000 Volume 44 Pages 1077-1082
Effect of the depth of trench on diffusional mass transfer from bottom sediment to flowing water in a rectangular trench is formulated as a function of flow velocity and the aspect ratio of the trench. Laboratory experiments are carried out in order to investigate the relation of the diffusional mass transfer for sediment bed in a rectangular trench with the water flow and the depth of the trench. The experimental results have shown that release flux of dissolved substance increases as the flow velocity increases in almost all experiments. It is also found out that release flux increases as the depth of the trench decreases. These results suggest that diffusional mass transfer is influenced by turbulent structure in a rectangular trench. It is considered that exchange of the water body near the sediment-water interface for the upper layer water becomes more frequent as the flow velocity increases or the depth of the trench decreases, so that release flux increases.
