Turbulence characteristics of overbank flow in compound river channel with vegetated floodplain

The turbulence characteristic of overbank flow in compound river channel with vegetated floodplain was studied experimentally by model test.The shrubs,arbors and grasses were modeled by using plastic straws,feather and plastic grasses respectively.A 3-D ADV was used to measure the flow velocities.It is found that the distributions of fluctuating velocity in three directions obey the law of normal distribution.The time-averaged velocity is related to the sampling duration.If the floodplain is vegetated,the lateral exchange of momentum becomes intensive and the momentum is transferred from the main channel to its associated floodplain.The effects of different kinds of vegetation on turbulence are not the same.The turbulence intensity increases after the floodplain is vegetated.The lateral and vertical turbulence intensities are in the same order and follow the S-shape distribution law.