Abstract
Recently, many river channels tend to be densely vegetated due to regime shifts in hydrological, fluvial and ecological processes and it is a critical engineering issue to evaluate conveyance capacity of vegetated channels. Although drag force coefficient is popularly used in evaluating drag force of vegetation, it is not always a convenient parameter in determining high water level, HWL, for a design flood. In this study, an equivalent Manning’s coefficient nv, which corresponds to drag force of overgrown vegetation in alternative bars, was theoretically evaluated by the two-dimensional two-layer (2D2L) hydrodynamic model. It was found that nv monotonically increases with increasing discharge as long as vegetation emerged. On the other hand, nv slightly decrease with discharge after vegetation submerged. Findings is to provide useful information for flood management of vegetated river channel.
