Characteristics And Simulation Of Wind Profile Of Farmland Shelterbelt In Alluvial Region Of Dawen River Plain

As farmland shelterbelts is a kind of unique ecological engineering of China it is not so good for its management by copying foreign theory and technology blindly or mechanically.Based on theory and method of vertical ecological field we study the wind speed profilecharacteristics of poplar shelterbelt in alluvial region of Dawen River Plain Dongping County in new perspective. We discuss the windbreak effect in vertical direction of farmland shelterbelt and reveal the spatial and temporal dynamics of wind profile around farmland shelterbelts in vertical direction. We evaluated the windbreak effect of shelterbelts in essence and aimed at choosing suitable shelter forest types for the feature of local agricultural and development of economic. Our study enriched the ecological field theory of farmland shelterbelts construction and promoted the development of the traditional shelterbelts and its construction theory. The aims are to provide with theoretical and technical guidance for the construction and maintenance of farmland shelterbelts. The main study results are as follows:(1) Wind profile near farmland shelterbeltIn the process of wind traveled from the windward side to the leeside the wind speed showed general trend of increased with the decreased of the first except ground layer and crown canopy height. The wind speed near ground and in crown canopy showed a trend of increase firstly then decreased. The main concentration of protection area was near shelterbelt and soon certain heights area, the protection area was honeycomb stitch. The wind speed get decreased first time around the crown canopy and then get decreased in 5.0-13.0 meter in the leeside on the height of crown canopy.The wind speed of different distance from the forest had different distribution characteristics on the vertical space. On the windward side at 1 H and 2 H the speed increased with the increase of observes height, and in the leeside of 1 H 2 H and inside of shelterbelt the characteristics was reduce before it increase. Wind speed severely changed inside of shelterbet and first increased then decreased and then increased quickly with the increase of observation height. The wind speed under branch height were greater than ck Wind speed.The mathematic simulation was conducted on wind speed by using Curve Expert and theresults showed that the relationship between wind speed of windward side and height was linear model. Because of influence of shelterbelt the wind speed of inside shelterbelt and leeside 1 H were complicated and the model of wind speed and height was multi-order polynomial relationship.Model equation between wind speed and height:Ck: Y=2.60+1.64XWindward side of 2H: Y=2.20+1.09XWindward side of 1H: Y=2.42+8.48XInside of shelterbelt: Y=1.28+1.76X-0.51X2+0.051X3-0.0016X4Leeside of 1H: Y=3.930-0.44X+0.032X2Leeside of 2H: Y=2.63+0.11X-0.036X2+0.0025X3The mathematic simulation was conducted on wind speed and distance from shelterbelt,and the model were complicated sine wave fitting in the observation height of 1.5 2.5 12.5meters, other height were multi-order polynomial model. All the correlation coefficient were above 0.93.Model equation between wind speed and distance from shelterbelt:1.5m:Y=2.75+0.50×cos(0.11X+0.83)2.5m:Y=2.81+4.73×cos(1.04X+7.14)4.5m:Y=2.09+4.21X+2.37X2-7.03X3-2.22X46.5m:Y=1.92+0.059X+0.0029X2-0.00009X3-0.000003X48.5m:Y=2.10+0.066X+0.0025X2-0.00008X3-0.000002X410.5m:Y=2.82+0.026X+0.0012X2-0.000032X3-0.000009X412.5m:Y=3.58+0.16×cos(0.14X+0.067)(2) The influence of different wind speed on shelterbelt windbreak effectUnder the condition same angle between wind direction and shelterbelt, the self correlation and consecutiveness of wind speed near shelterbelt increased with the increase of desert wind speed, and also the space continuity and heterogeneity. The bigger of desert wind speed the bigger of average wind speed near shelterbelt, and also the wind speed are more concentrated. The variable coefficient near shelterbelt decreased with the increase of desert wind speed and the bigger of desert wind speed the similar shape of protection zone.(3) The influence of the wind direction on shelterbelt windbreak effectUnder the condition same desert wind speed, the self correlation and consecutiveness of wind speed near shelterbelt increased with the increase of angle between wind direction and shelterbelt, and also the space continuity and heterogeneity. The effectiveness of shelterbelt protection is maximum when the direction of the wind is perpendicular to the shelterbelt. The effectiveness of shelterbelt protection will decrease with the angle between shelterbelt decreases.(4) Protection area in vertical directionThe relationship between wind speed and protection area was that the ratio of protection area decrease with the increase of wind speed. The influence of wind direction on the protection area was that the area of protection increase with the increase of angles between wind direction.