Author(s): Yuan-Heng Zhang; Huan-Feng Duan; Xu-Feng Yan

Linked Author(s): HF Duan

Keywords: Vegetation patch; Aspect ratio; Density; Steady wake length; Steady wake velocity

Abstract: This research presents an experimental study on the impact of a center-channel rectangular vegetation patch under an aligned configuration of rigid and emergent stems on the flow adjustment and wake structure. A steady wake region with a length of L1 and a relatively low velocity (U1) and turbulence forms after the patch, facilitating patch elongation. The interior adjustment length (La) in this study is observed to be proportional to the ratio of patch width (W) to patch density (), i. e., W /. Considering the cumulative effect induced by the patch length (L), a cumulative hydraulic resistance was developed based on the ratio of L to W / (i. e.,  L /W) to qualify the L1 and U1. It is observed that both steady wake length and steady wake velocity will be mitigated as the cumulative hydraulic resistance enhances, until the velocity starts to increase immediately downstream of the patch, performing like a solid obstruction, indicating the equilibrium state of the patch. Therefore, the expansion length will be shortened as the patch elongates downstream, which is an iterative process. The formula developed in this study helps to obtain a comprehensive understanding of the patch growth from its initial circular shape to a stable rectangular patch and the flow-vegetation-sediment interaction.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1063-cd

Year: 2023