The role of increasing riverbank vegetation density on flow dynamics across an asymmetrical channel

Valyrakis, M. , Liu, D., Turker, U. and Yagci, O. (2021) The role of increasing riverbank vegetation density on flow dynamics across an asymmetrical channel. Environmental Fluid Mechanics, 21(3), pp. 643-666. (doi: 10.1007/s10652-021-09791-9)

Abstract

Over the last two decades, the role of vegetation in the environmental and ecological restoration of surface water bodies has received much attention. In this context, the momentum exchange between the flow through the main channel and the riparian zone is a key mechanism. The primary goal of this study is to investigate the role of bank vegetation density on flow dynamics across the whole channel. This experimental study presents the major findings from a series of flow measurements across a channel having a sloping bank with vegetation at varying densities. The experiments are conducted under the same, uniform flow and fixed bed conditions, for a range of six linear and rectilinear arrangements of incremental streambank vegetation densities. A set of ten velocity profiles is obtained across the test cross-section of the channel, including the riverbank, for each vegetation density. These flow measurements are analyzed to derive roughness coefficients, which are related to the bulk flow velocities through the main channel and the riverbank and discuss the redistribution of flow velocities. An approximate doubling for the estimates of time-averaged boundary shear stress at the main channel, is observed for the case of no to dense vegetation, which enable further discussing implications for the stability of bed surface material. It is found that the vegetation arrangement, in addition to vegetation density, can have a strong impact in modifying the mean flow velocity at the main channel, for low riparian densities (φ < 0.6%).

• Item Type: Articles
• Additional Information: The authors would like to acknowledge the support of The Royal Society (Research Grant RG2015 R1 68793/1) and The Royal Society of Edinburg (Scottish Crucible Award).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Liu, Mr Da and Valyrakis, Dr Manousos
• Authors: Valyrakis, M., Liu, D., Turker, U., and Yagci, O.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Environmental Fluid Mechanics
• Publisher: Springer
• ISSN: 1567-7419
• ISSN (Online): 1573-1510
• Published Online: 15 April 2021
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Environmental Fluid Mechanics 21(3): 643-666
• Publisher Policy: Reproduced under a Creative Commons License