Effect of plant shapes on sand transport rate and aerodynamic particle entrainment rate from the perspective of plant drag

Abstract

Plant shape is an important factor affecting sand transport rate and aerodynamic particle entrainment rate. Two different types of flexible plant models (one is slender and the other has a large upper part and a small lower part) and a rigid tree-like plant model are selected with approximately zero basal-to-frontal area ratio. The sand transport rate, aerodynamic entrainment rate and shear stress partitioning on vegetated surfaces were measured under different plant densities and incoming wind speeds in a wind tunnel. The results show that the sand transport rate and aerodynamic entrainment rate on vegetated surfaces decrease with an increase in lateral cover and form drag of plant models. The relationship between sand transport rate, aerodynamic entrainment rate and drag parameter β (defined as the drag coefficient ratio of a plant model to the bare surface) is established by introducing the attenuation function of effective wind speed, which decays exponentially with an increase in lateral cover and linearly with an increase in drag coefficient ratio β. The present findings contribute to our understanding of how different vegetation types affect sediment transport rate and aerodynamic entrainment rate.