Vegetation in watercourses can influence different aspects of flow structure, subsequently affecting many processes of flow, such as pollutant transportation, sediment deposition and hydrophyte habitat distribution. Vegetation often occurs on one side of a channel, which requires understanding the effects of partial vegetation on the flow. Although many studies have been done on flows through uniform vegetation, this type of flow is unrealistic, as in natural floodplains, the vegetation in riparian zones is usually non-uniform. There is little study on the hydraulic characteristics of the flow with the co-existence of short and tall vegetation under either emergent or submerged conditions. In this paper, a novel experiment with rigid vegetation of two heights in one side of a channel was conducted to understand flow characteristics such as velocity profile, turbulence intensity, Reynolds stress, and discharge distribution. Experimental results revealed that the velocity is almost constant over the short vegetation height and increases sharply with the depth just above the short vegetation. Similarly, the Reynolds stress had little variation in the short vegetation layer, but started to increase rapidly from the top of the short vegetation to the water surface, which indicates the presence of strong mixing layer near the top of the short vegetation. Additionally, a strong shear layer existed between non-vegetated and vegetated zones, indicating the reduction effect of vegetation on the flow velocity. Furthermore, modifications are needed to properly calculate the hydraulic radius and Manning's coefficient for the flow with double-layered vegetation.

河道中的植被会影响水流结构的各个方面，进而影响水流的许多过程，例如污染物的运输，沉积物的沉积和水生植物栖息地的分布。植被通常发生在河道的一侧，这需要了解部分植被对水流的影响。尽管已经对穿过均匀植被的水流进行了许多研究，但是这种水流是不现实的，因为在自然洪泛区中，河岸带的植被通常是不均匀的。在生长期或淹没条件下，短高植被并存的水流水力特性研究很少。在本文中，进行了一项新的实验，该实验在通道的一侧具有两个高度的刚性植被，以了解流量特征，例如速度分布，湍流强度，雷诺应力和流量分布。实验结果表明，速度在短植被高度上几乎是恒定的，并随短植被上方的深度急剧增加。同样，雷诺应力在短植被层几乎没有变化，但从短植被顶部到水面开始迅速增加，这表明短植被顶部附近存在强混合层。此外，在非植被区和植被区之间存在一个强剪切层，表明植被对流速的降低作用。此外，