Author
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Hagen, Lawrence |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 7/23/2006 Publication Date: 7/24/2006 Citation: Hagen, L.J. 2006. Effect of Leaf Distribution on Sand Transport. Meeting Abstract. Interpretive Summary: Abstract only. Technical Abstract: The friction velocity above crop canopies is depleted by the presence of leaves and stalks. But when crop canopies are thin, friction velocities near the soil surface during high winds often drive wind erosion that abrades the plants, uncovers roots, and depletes the soil resource. Several studies have investigated erosion control by standing stalks, but few have considered the effects of both leaves and stalks. In this study we measured the threshold velocities, sand transport capacities, and relative kinetic energy distributions created by simulated, standing dicotyledonous and plants with leaves in a wind tunnel. Both plant heights and populations were varied during the experiments. To estimate relative kinetic energy of saltating particles impacting the canopy, vertical profiles of soil abrasion were measured using sticks constructed from 3-sided electrical conduit channels filled with consolidated, fine sandy soil. Experimental results showed that aerodynamic canopy roughness, displacement height, and threshold velocity varied with both plant height and population. Interception of saltation by stalks and near-surface leaves decreased the sand transport capacity for a given soil surface friction velocity, below that of a bare sand surface with the same friction velocity. Hence, canopy properties near the soil surface are useful to develop interception coefficients. The various leaf arrangements in the simulated canopies also modified the relative vertical kinetic energy distributions as compared with that observed over the sand bed without a canopy. Leaves positioned near the top of the canopy reduced overall sand surface friction velocity more than the same leaves positioned near the bottom of the canopy. |
