Experimental Investigation of Influence of Vegetation on Flow Turbulence

摘要

Vegetation in channels, rivers, reservoirs, and wetlands alters the flow turbulence characteristics. Vegetation has both positive and negative effects, depending on the objective of the hydraulic conduit. For example, it decreases conveyance capacity by obstructing flow by reducing the flow cross-sectional area and increasing resistance to flow and may, hence, increase flooding. On the other hand, it increases bank stability, reduces erosion and turbidity, provides habitat for aquatic and terrestrial wildlife, presents aesthetic properties, and filters pollutants. Using both field and laboratory experiments, this study investigates the influence of vegetation on turbulent characteristics and flow resistance for a channel with gravel bed and vegetation on banks. The results shows that vegetation affects the velocity distribution, the position of dip phonemenon, turbulent kinematic energy and drag coefficient. These changes can be observed in the distribution of shear stress, the quadrant analysis events and statistics moments.