Windproof Efficiency of Shelterbelt in High-low Pattern and Its Response to Wind Directions
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S727.2

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    Abstract:

    [Objective] To study the windproof efficiency of shelterbelt composed by Haloxylon ammodendron and Caragana korshinskii and its response to wind directions in order to provide theoretical basis for shelterbelt construction on the periphery of desert oasis, desert road and desert railway.[Methods] Prototypes of H. ammodendron and C. korshinskii with different individual characteristics were used to make simulation plants, and then constructed into high-low shelterbelt, which was recorded as AmBn pattern. Here, the capital letter "A" represented the simulated plant H. ammodendron, "m" represented that the planting space was 15 cm×40 cm, the capital letter "B" represented the simulated plant C. korshinskii, and "n" represented that the planting space was 8.5 cm×25 cm. When the wind direction was opposite, the shelterbelt was recorded as BnAm pattern. By the wind tunnel simulation experiments, the airflow field, wind speed acceleration rates and the windproof efficiency were analyzed with the controlled wind speed of 7, 10, 15 m/s.[Results] ① When the airflow reached to the front of the shelterbelt, the wind speed decreased overall. According to the variation intensity of wind speed, the air flow could be divided into 3 layers:the upper layer (above the 30 cm), the middle layer (5-20 cm), and the lower layer (below 3 cm). The speed recover point behind the shelterbelt in AmBn pattern and BnAm pattern was 23 H and 12.5 H, respectively. ② The wind shadow range of AmBn pattern was greater than that of BnAm pattern. The wind shadow core areas were formed at the canopy height of both "A" plant and "B" plant, namely, a dicaryon pattern was formed. ③ Under the controlling wind speed of 7, 10, 15 m/s, the average windproof efficiency of shelterbelt AmBn was 34.44%, 34.98% and 32.51%, respectively. The average windproof efficiency of shelterbelt BnAm was 22.62%, 19.70%, 19.41%, respectively. ④ In vertical direction, the forest belt played a role in slowing down the airflow below the height range of about 1.5 H, which accelerated the airflow above this range. In the horizontal direction, the windbreak efficiency of the AmBn type forest belt was better than that of the BnAm type forest belt before, within and after the belt.[Conclusion] The windproof efficiency of shelterbelts is related to the occurrence order of the plants along the wind direction. In view of the protection efficiency and protection distance, the shelterbelt in AmBn pattern is suggested to be constructed.

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马彦军,李雪琳,马瑞,张莹花,魏林源,张统帅.前高后低型防风固沙林防风效应及其对风向的响应[J].水土保持通报英文版,2018,38(5):28-33,39

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History
  • Received:March 29,2018
  • Revised:April 23,2018
  • Adopted:
  • Online: November 10,2018
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