1887

oa Agrochemophysica - Evaluering van kunsmatige windskutte

Volume 11, Issue 3
  • ISSN : 0302-7112

 

Abstract

Three types of plastic materials which are sold as shade netting, and chicken wire, were evaluated with respect to their efficiency as windbreak materials in the construction of artificial windbreaks. The permeability o f the materials was determined as well as the resistance they offer to the flow of air through them. The latter was expressed as a resistance index. The four types of material were used consecutively during four summers to construct windbreaks. The windbreaks were 75 m long and 6 m high. The windspeeds at distances 4H and 2H in front of, and 2H, 4H, 6H, 8H, 10H and 12H behind the windbreak (where H is the height o f the windbreak) were measured and compared with the windspeed at a point where the wind was not affected by the windbreak. Only data measured on days with a windrun of more than 200 km and on which the wind varied between east-south-east and south-south-east, were considered. The windbreaks themselves were orientated perpendicularly to the prevailing south easterly winds. The most dense windbreak with a permeability o f 22 % caused a 68 % reduction in the windspeed at a distance of 2H behind the windbreak. This high reduction in windspeed quickly decreased and at a distance of 12H behind the windbreak the reduction was only 20%. The windbreak with a permeability o f 50% caused a 44 % reduction in windspeed at a distance o f 2H and 18 % reduction at a distance o f 12H behind the windbreak. In terms of wind reduction over the greatest distance, the latter windbreak can be considered to be the most efficient. The maximum eduction in windspeed obtained by a net of 68 % permeability was 35 %. With the chicken wire only a very slight reduction of windspeed was measured. The permeability of a windbreak gives a better indication of its protective characteristics than its resistance index.

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/content/agro/11/3/AJA03027112_431
1979-01-01
2019-10-18

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