Flow penetration into the canopy of the submerged vegetation: definitions and quantitative estimates

The focus of this study is on the ranges of flow submergence and vegetation density which well exceed the ranges already studied by other researchers. The penetration distance eδ of large-scale turbulence into vegetation canopies has been assessed using vertical distributions of the normal and shear turbulent stresses. Although the estimates of eδ by the suggested methods are interconnected, their values may differ reflecting different aspects of flow-vegetation interactions. The estimates based on the shear stresses ''uw are most closely correlated with those from the profiles of the variance of the longitudinal velocity ''uuand thus can be used when two-component velocity measurements are not possible. The experimental assessment of the influence of characteristic turbulence scales and energy on flow penetra-tion parameters was made using dimensionless numbers characterizing the interplay between depth-scale, canopy-scale, and wake-scale turbulent eddies. The data suggest that there may be mutually opposing ef-fects leading to unexpected behaviors such as the blockage of depth-scale eddies by enhanced wake-scale turbulence.