Effects of Vertical Variation in Vegetation Density on Wave Attenuation

Abstract

AbstractA physical model experiment was used to investigate irregular wave attenuation through emergent vegetation with variations in stem heights. The experiment was conducted with six peak periods, six incident wave heights, and two schemes of vegetation. One scheme used uniform vegetation (constant stem height) and the other scheme approximated vegetation with larger biomass near the bottom and decreasing linearly to the surface, consistent with observed biomass patterns in the field. Although distributions were different, the total vertical projected area was kept constant between the two schemes. The cross shore variation of wave heights across the vegetation were measured, and losses due to sidewall and bottom friction effects were measured and removed from the wave attenuation in the vegetated cases to isolate the influence of vegetation. The normalized wave height attenuation for each case was fit to the decay equation to determine the difference of vegetation transmission coefficients Kv and damp...