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Shelterbelt Efficiency Criteria April 2006

Shelterbelt Efficiency Criteria April 2006. Criteria affecting shelterbelt efficiency . Porosity Height Length and width Orientation Cross profile shape Environment. Porosity ( f ) = Perforated area x 100% Total surface area exposed to the wind. Low porosity (very dense).

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Shelterbelt Efficiency Criteria April 2006

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  1. Shelterbelt Efficiency Criteria April 2006 André Vézina, ITA, La Pocatière Campus

  2. Criteria affecting shelterbelt efficiency • Porosity • Height • Length and width • Orientation • Cross profile shape • Environment André Vézina, ITA, La Pocatière Campus

  3. Porosity (f) = Perforated area x 100% Total surface area exposed to the wind André Vézina, ITA, La Pocatière Campus

  4. Low porosity (very dense) André Vézina, ITA, La Pocatière Campus

  5. Medium porosity André Vézina, ITA, La Pocatière Campus

  6. Windbreak Wind Very dense Moderately dense Average reduction on 20H Wind speed reduction (% of wind measured in open area) at various distances from a windbreak made of very dense and moderately dense common reed screens (adapted from Nägeli, as used in Guyot, 1977) André Vézina, ITA, La Pocatière Campus

  7. Windbreak Wind Average windspeed reduction of 50 % Average windspeed reduction of 25 % 10 H 20 H Average windspeed reduction in the lee of a windbreak (porosity=50%, wind measured at 0,5 H above the ground surface) André Vézina, ITA, La Pocatière Campus

  8. Turbulent zone (plume dilution) Distance from the windbreak (H) Windbreak Quiet zone From Raine (1974) in McNaughton, (1988) André Vézina, ITA, La Pocatière Campus

  9. André Vézina, ITA, La Pocatière Campus

  10. André Vézina, ITA, La Pocatière Campus

  11. Wind speed reduction (%) obtained from a hedge of hybrid poplars spaced at 1 metre (adapted from Vézina, 1985) André Vézina, ITA, La Pocatière Campus

  12. André Vézina, ITA, La Pocatière Campus

  13. Siberian elm spaced at 3 m André Vézina, ITA, La Pocatière Campus

  14. Snow dispersion profile produced by Siberian elm André Vézina, ITA, La Pocatière Campus

  15. Red ash spaced at 3 m André Vézina, ITA, La Pocatière Campus

  16. Snow dispersion profile produced by red ash André Vézina, ITA, La Pocatière Campus

  17. Height impact (from Nägeli 1953, in Guyot, 1989) Relative wind speed (u/u0) Relative heigth Distance (H) André Vézina, ITA, La Pocatière Campus

  18. André Vézina, ITA, La Pocatière Campus

  19. W/H = 8 26% reduction W/H = 0.6 92% reduction Odour reduction at W/H Odour source André Vézina, ITA, La Pocatière Campus

  20. Lateral air circulation around the shelterbelt Wind Protected zone André Vézina, ITA, La Pocatière Campus

  21. Several American researchers (Hintz, 1986; Smith and Scholten, 1980) recommend planting very large windbreaks (up to 10 rows of trees and shrubs). However, Read (1964) has demonstrated that narrower, denser hedges are just as effective as very large ones. André Vézina, ITA, La Pocatière Campus

  22. Orientation Prevailing winds André Vézina, ITA, La Pocatière Campus

  23. Oblique Perpendicular André Vézina, ITA, La Pocatière Campus

  24. Prevailing winds No slope Protected zone Prevailing winds Downward slope Protected zone Prevailing winds Upward slope Protected zone André Vézina, ITA, La Pocatière Campus

  25. André Vézina, ITA, La Pocatière Campus

  26. Hedge spacing (Nägeli, 1969, as used in Guyot,1989) Spacing 20 X H Spacing 15 X H Spacing 10 X H André Vézina, ITA, La Pocatière Campus

  27. Temperature variation at ground level (ºC) Relative spacing (D/H) André Vézina, ITA, La Pocatière Campus

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