Effects of a natural windbreak on dust dispersion in the neutral surface layer

Field experiments were conducted in Indian Head, Saskatchewan in order to study the effects of a natural shelterbelt (width-to-height ratio W/H = 0.5) on dust dispersion from a gravel road. Transects of dust concentration sensors running normal to the road were placed both in the lee of the windbreak and in an adjacent unsheltered region. A Lagrangian stochastic (LS) model was developed to compute the theoretical ratio (c/Q) of concentration to emission rate and infer time average concentration ( c¯) and the ensemble mean concentration transient. In about 69% of cases the inferred time average concentration lay within a factor of two of the corresponding observations (FAC2 = 69%). The modeled and experimental results suggest that the natural windbreak is not effective in filtering small dust particles (D ≤ 20 µm), but that windbreak entrapment can be a significant mechanism to remove large dust particles (D ≤ 50 µm).