(2) The standard wooden fence made of slats 3.8 centimeters 

 wide by 1.0 centimeter thick seems to be the most practical and 

 cost-effective type of sand fence. It is readily available in 

 the United States and may be called either a snow or sand fence. 



(3) Fences should be installed parallel to the shoreline. 

 It is not necessary that they be perpendicular to the prevailing 

 wind. Fences are often filled by winds blowing at a sharp angle 

 to them if sufficient sand is moving. 



(4) Placement of the fence at a proper distance shoreward 

 from tne berm crest is critical. If placed too close it will be 

 exposed to wave attack and will likely fail. A location too far 

 back of the berm may encourage ponding of water in front of the 

 resulting dune, causing the dune to wash out and fail. The pro- 

 per distance must be determined for each site. Distance from 

 the berm will usually be more than 90 meters shoreward except 



on rapidly prograding beaches where it should be less. 



(5) Straight fence alinement has usually been more effective 

 than zigzag and side-spur patterns in accumulating sand on large 

 installations. However, where strong winds occasionally blow 

 parallel to the fence, sand moving along the fence will be lost 

 around the fence ends. This may become a significant factor for 

 short fences of less than 200 meters long (Woodhouse, Seneca, and 

 Broome, 1976). In such cases, the addition of lateral spurs may 

 be useful. 



(6) Dunes are usually built with sand fence in one of two 

 ways: (a) by installing a single fence and following it with 

 additional single-fence lifts as each fence fills (Fig. 11); or 

 (b) by installing double-fence rows with the individual fences 

 spaced about 4 times fence height (4h) apart (5 meters in the 

 case of 1.2-meter fence) and following these with succeeding 

 double row lifts as each fills (Fig. 12). 



(7) Single rows of fence are usually the most cost effective 

 particularly at the lower windspeeds, but double fences are likely 

 to trap sand faster at higher windspeeds. Laboratory studies 

 (Manohar and Bruun, 1970) indicate that a single fence ceases 



to trap sand at windspeeds above 58 kilometers per hour while 

 a double fence continues to be effective above that windspeed. 



(8) Dune height is increased most effectively by positioning 

 succeeding lifts near the crest of the existing dune. However, 

 under this system, the effective height of succeeding fences 

 decreases and difficulties arise in supporting fence near the 

 dune crest as the dune becomes higher and steeper. 



(9) Dune width is increased by installing succeeding lifts 

 parallel to and about 4h away from the existing fence. The dune 

 may be widened either landward or seaward in this way if the dune 

 is unvegetated. 



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