Sand-fixing and windbreak forests are widely used to protect or/and improve the ecological environments in arid and semi-arid regions. A full understanding of wind flow characteristics is essential to arranging the pa...Sand-fixing and windbreak forests are widely used to protect or/and improve the ecological environments in arid and semi-arid regions. A full understanding of wind flow characteristics is essential to arranging the patterns of these protective forests for enhancing the effectiveness. In this study, the wind velocity over the underlying surface with sand-fixing forests and windbreak forests at the heights of 1–49 m was monitored from two 50-m high observation towers in an oasis of Minqin, Gansu Province of China. The wind velocities were simulated at different locations over these protective forests between those two towers by a two-dimensional Computational Fluid Dynamics（CFD） model. The results showed that at the heights of 1–49 m, the wind velocity profiles followed a classical logarithm law at the edge of the oasis and a multilayer structure inside the oasis. With increasing number of sand-fixing forest and windbreak forest arrays, the wind velocity at the heights of 1–49 m generally decreased along the downstream direction of the prevailing wind. Specifically, below the height of windbreak forests, the wind velocity decelerates as the airflow approaches to the windbreak forests and then accelerates as the airflow passes over the windbreak forests. In contrast, above the height of windbreak forests, the wind velocity accelerates as the airflow approaches to the windbreak forests and then generally decelerates as the airflow passes over the windbreak forests. Both the array number and array spacing of sand-fixing and windbreak forests could influence the wind velocity. The wind protection effects of sand-fixing forests were closely related to the array spacing of windbreak forests and increased with the addition of sand-fixing forests when the array of the forests was adequately spaced. However, if the array spacing of windbreak forests was smaller than seven times of the heights of windbreak forests, the effects were reduced or completely masked by the effects of windbreak forests. The results could offer theoretical guidelines on how to systematically arrange the patterns of sand-fixing and windbreak forests for preventing wind erosion in the most convenient and the cheapest ways.展开更多
干旱区的水资源限制了植物治沙应用范围，将仿真固沙灌木加入退化梭梭林，比较仿真固沙灌木＋梭梭的灌木林与塑料网方格沙障防风固沙效能，为仿真固沙灌木应用提供参考。在野外相同条件下观测比较仿真固沙灌木林与塑料网方格沙障内风速...干旱区的水资源限制了植物治沙应用范围，将仿真固沙灌木加入退化梭梭林，比较仿真固沙灌木＋梭梭的灌木林与塑料网方格沙障防风固沙效能，为仿真固沙灌木应用提供参考。在野外相同条件下观测比较仿真固沙灌木林与塑料网方格沙障内风速，结果显示：仿真固沙灌木＋梭梭灌木林的风速削减率与塑料网方格沙障的差异不显著；随着风速增大，仿真固沙灌木降低风速率与塑料网方格沙障降低风速率差异变小；在风速为8.1~8.9 m s-1时，仿真固沙灌木降低风速率达塑料方格沙障的80%；仿真固沙灌木＋梭梭灌木林的输沙率随高度变化为指数递减，是裸沙地的35%；仿真固沙灌木林的建立不受气候条件影响，可重复应用，与灌木搭配可增强防风固沙效能。展开更多
基金supported by the Forestry Industry Research Special Funds for Public Welfare Projects(201404306)the National Natural Science Foundation of China(41371034,41361001,31560235)+1 种基金the National Key Technologies R&D Program of China(2013BAC07B01)the Gansu Science Foundation for Distinguished Young Scholars(145RJDA327)
文摘Sand-fixing and windbreak forests are widely used to protect or/and improve the ecological environments in arid and semi-arid regions. A full understanding of wind flow characteristics is essential to arranging the patterns of these protective forests for enhancing the effectiveness. In this study, the wind velocity over the underlying surface with sand-fixing forests and windbreak forests at the heights of 1–49 m was monitored from two 50-m high observation towers in an oasis of Minqin, Gansu Province of China. The wind velocities were simulated at different locations over these protective forests between those two towers by a two-dimensional Computational Fluid Dynamics（CFD） model. The results showed that at the heights of 1–49 m, the wind velocity profiles followed a classical logarithm law at the edge of the oasis and a multilayer structure inside the oasis. With increasing number of sand-fixing forest and windbreak forest arrays, the wind velocity at the heights of 1–49 m generally decreased along the downstream direction of the prevailing wind. Specifically, below the height of windbreak forests, the wind velocity decelerates as the airflow approaches to the windbreak forests and then accelerates as the airflow passes over the windbreak forests. In contrast, above the height of windbreak forests, the wind velocity accelerates as the airflow approaches to the windbreak forests and then generally decelerates as the airflow passes over the windbreak forests. Both the array number and array spacing of sand-fixing and windbreak forests could influence the wind velocity. The wind protection effects of sand-fixing forests were closely related to the array spacing of windbreak forests and increased with the addition of sand-fixing forests when the array of the forests was adequately spaced. However, if the array spacing of windbreak forests was smaller than seven times of the heights of windbreak forests, the effects were reduced or completely masked by the effects of windbreak forests. The results could offer theoretical guidelines on how to systematically arrange the patterns of sand-fixing and windbreak forests for preventing wind erosion in the most convenient and the cheapest ways.
文摘干旱区的水资源限制了植物治沙应用范围，将仿真固沙灌木加入退化梭梭林，比较仿真固沙灌木＋梭梭的灌木林与塑料网方格沙障防风固沙效能，为仿真固沙灌木应用提供参考。在野外相同条件下观测比较仿真固沙灌木林与塑料网方格沙障内风速，结果显示：仿真固沙灌木＋梭梭灌木林的风速削减率与塑料网方格沙障的差异不显著；随着风速增大，仿真固沙灌木降低风速率与塑料网方格沙障降低风速率差异变小；在风速为8.1~8.9 m s-1时，仿真固沙灌木降低风速率达塑料方格沙障的80%；仿真固沙灌木＋梭梭灌木林的输沙率随高度变化为指数递减，是裸沙地的35%；仿真固沙灌木林的建立不受气候条件影响，可重复应用，与灌木搭配可增强防风固沙效能。
