Turbulent characteristics in open-channel flow with emergent and submerged macrophytes

Under certain hydrodynamic conditions,different species of aquatic plants will have different impacts on the flow structure and sedmient re-suspension due to the differences in plant morphology.In this study,the sediment collected from the Taihu Lake is placed in a glass tank planting with emergent and submerged macrophytes calam us and water fern.Using the flume expermients,the turbulent flow in the open channel with macrophytes is measured by a three-dmiensional Acoustic Doppler Velocmieter(ADV).The analysis of flow turbulence and sediment re-suspension is conducted.The results show that the vertical velocity distribution has different regularities in open-channel flow with emergent and submerged mcrophytes.Both turbulence intensity and Reynolds Number exhibit obvious anisotropy,and their maximum values are found to be at the junction of submerged plant canopy and at the bifurcation of emergent plant stems and branches,respectively.The sedmient re-suspension process can be inhibited by the presence of emergent and submerged macrophytes under certain conditions.However,when the Reynolds Number reaches a certain value,the presence of these macrophytes can actually exacerbate the sedmient resuspension process.In comparison with emergent plants,submerged mcrophytes would be more effective ininhib iting sedi ent re-suspension.