Abstract
Turbulence and DO measurements were conducted in laboratory flume, in which two kinds of bed conditions were chosen, i.e., smooth and vegetation roughness conditions. It was found that the vegetation promotes the gas transfer beneath air/water interface, because a larger surface velocity divergence is induced by a large-scale shear vortex formed in the vegetation edge. Further, we revealed a great dependency of the gas transfer on the vegetation density. Based on the measured results, a new surface divergence model was developed which can predict successfully the gas transfer velocity in the openchannel flows for the both of the smooth and vegetated bed conditions.
