Vegetative Flow Resistance: Characterization of Woody Plants for Modeling Applications

Flow-vegetation interaction is a complex process which causes difficulties in hydraulic modeling. The purpose of this paper is to investigate the characterization of natural woody plants, and further, the determination of flow resistance coefficients for modeling applications. Flume studies with both living and artificial plants were performed to investigate the effect of flow velocity, relative submergence, and vegetation density on flow resistance. Large differences between natural and artificial plants were found. Subsequently, a computational approach for determining flow resistance coefficients for complex woody vegetation was discussed. In the approach, woody vegetation was characterized by leaf area index (LAI), a vegetation parameter χ, and a species-specific drag coefficient C_dχ. LAI was used to take the vegetation density into account, and the species-specific vegetation parameter χ considered the effects of plant deformation in a flow.