Author(s): Yuqi Shan; Chao Liu
Linked Author(s):
Keywords: Bedload sediment transport; Plant morphology; Vegetated channels; Turbulent kinetic energy
Abstract: Bedload sediment transport driven by water flow over a sediment bed plays an important role in the evolution and restoration of rivers, marshes and deltas. In aquatic environments, vegetation is widespread, and each plant species has its own morphology. Although bedload transport occurs widely in vegetated regions, it is difficult to precisely predict the bedload transport rate (Yager and Schmeeckle 2013; Yang et al. 2018). Most studies have focused on the impact of vegetation density and distribution on flow and sediment transport (Shan et al. 2020), but the impact of plant morphology on bedload transport is unknown and has not been quantified. To address this research gap, this study reports that plant morphology impacts near-bed flow velocity and turbulent kinetic energy (TKE) and alters bedload transport flux in vegetated regions. A plant morphology coefficient was defined to quantify the impact of plant morphology on flow and bedload transport. This coefficient is valid for plants with natural morphology. We developed a theory accounting for the plant morphology effect to predict near-bed velocities, TKE and bedload transport rates in the context of vegetation canopies. Laboratory experiments confirmed that the new theory can precisely predict near-bed velocity, TKE and transport rate in vegetated regions. The impact of plant morphology on transport rates cannot be ignored; otherwise, the predictive error may be up to an order of magnitude. This new theory is suitable for plants with natural morphology and significantly improves the accuracy of bedload transport predictions in vegetated regions, thereby increasing the accuracy of the predictions made concerning the evolution of vegetated landscapes and providing guidance for the maintenance and restoration of rivers, marshes and deltas.
Year: 2024