Gas exchange and turbulent transport in vegetated open-channel flows

在实验室水槽中进行了湍流度和溶解氧的测量，其中选择了两种床面条件，光滑和植被粗糙条件。结果表明，植被对气/水界面下的气体输送有促进作用，这是由于植被边缘形成的大尺度剪切涡引起了较大的表面速度散度。此外，我们揭示了一个很大的依赖性的气体传输上的植被密度。在此基础上，提出了一种新的表面扩散模型，该模型可以成功地预测光滑床面和植被床面条件下明渠水流中的气体输移速度。

We conducted turbulence and DO measurements 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 open-channel flows for the both of the smooth and vegetated bed conditions.