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The efficiency of vegetative windbreaks in combating wind erosion : simulation and scaling Volume 11, issue 1, Mars 2000

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  • Page(s) : 52-7
  • Published in: 2000

Windbreaks have been used for many years to reduce wind speed as a wind-erosion control measure. However, there is yet no clear answer on what should be the optimal design for windbreaks. In a wind tunnel we tested five single-row barriers, each with different stem and canopy porosity, and a two- and three-row barrier on their efficiency in wind-speed reduction. Zones of erosion and deposition were determined from wind-speed measurements and compared with experimental wind-tunnel data on sand transport. As regards porosity distribution, evenly distributed porosity of stem and canopy resulted in the longest protected area. Dense lower parts were more efficient than more porous lower parts. Two- and three-row barriers were more efficient in terms of wind-speed reduction between 3 H and 8 H only (H in barrier heigth). At higher distances, single-row barriers resulted in higher wind-speed reduction. Also the sheltering zone of single-row barriers was higher. Erosion was almost not observed in the case of a barrier with evenly distributed porosity. Deposition was only significant in front of and up to 5 H leeward of such a barrier. The absence of a dense lower part resulted in an excessive zone of erosion behind the barrier. The experimental data confirmed the graphically determined zones of deposition.