Author(s): Hao-Liang Wu; Nian-Sheng Cheng

Linked Author(s):

Keywords: Bed-load transport; Emergent vegetation; Incipient motion; Turbulence; Laboratory flume

Abstract: A laboratory study of the bed-load transport with the presence of emergent vegetation was conducted in the flume mounted with arrays of evenly-distributed rigid dowels. The experiment measured the sediment transport over the moveable bed by collecting sand with a settling tank at the end of the vegetation region. With this setup of sediment collection, the experiment could more accurately measure the relative small amount of sediment transport approaching to the critical condition of incipient motion. The bed-load transport rate has been investigated for one sediment size with different stem diameters and stem spacings. The experiment also measured the turbulence through the vegetation in the longitudinal exchange zone, thereby deriving a semi-empirical formula to predict the incipient motion based on the geometrical information of the vegetation distribution and the turbulence information of the flow. To reveal the mechanism, this study introduced not only the population density and mean flow rate, but several new parameters to indicate the scales of the threshold of incipient motion with multiple cylinders. Thus, the proposed formula was built on a foundation of both reliable data and solid theoretical analysis.

DOI: https://doi.org/10.3850/978-981-11-2731-1_153-cd

Year: 2018