摘要
多风信条件下,沙砾质戈壁与鸣沙山进行着往复式的能量交换及物质运动。部分沙物质在砾石的保护下,形成阻沙。部分沙物质在跃移沙粒的激化下形成戈壁风沙流并对洞窟产生危害。戈壁风沙流是造成沙砾质戈壁从稳定向不稳定状态演化的主要动力因素;而上风向沙源的供给状况又是决定砾石床面阻沙和导沙的主要因素。基于此,戈壁防护带应首先控制来自鸣沙山的沙源,采取以阻断或减少外来沙源,通过固定和覆盖沙砾质戈壁地表以及增加下垫面粗糙度等,来造成一种既利于沙子堆积的条件,又能促进形成天然戈壁输沙场,从而为偏东风反向搬运创造一个适宜场。因此,如何因势利导,使窟顶流场与风沙地貌达到一种动力平衡,是莫高窟综合防护体系成功与否的关键之一。这与以往单风向或双风向条件下所探讨的防护体系效应有着本质的区别。
Under multi-wind directions, the energy exchanging and material transporting repeatedly happened between gravel gobi and the Mingsha Mountain. Part of sands are arrested by gravels, whereas part of sands form gobi sand stream irritated by saltant sand grains and then to threaten the Mogao Grottoes. Sand stream is a main dynamic factor causing gravel gobi to develop from stability to instability; on the other hand, the upwind sand source supply is also a main factor influencing gobi bed arresting or transporting sands. From this view, firstly, the measures must be taken to cut off and decrease sand source coming from the Mingsha Mountain; secondly to increase surface roughness through covering and stabilizing gravel gobi surface. Thereby, gravel gobi will not only form a temporary site for arresting sands under the control of west or south winds, but also promote to develop a passage transporting sand and returned sands to the Mingsha megadune by easterly winds. Therefore, how to use multi-wind directions and gobi bed for arresting and transporting sand, which will achieve a dynamic equilibrium between airflow and aeolian landforms, is a key to construct the comprehensively preventing system. The dynamic equilibrium effect emphasized in the paper differs from others on the condition of single wind direction and bi-wind directions.
出处
《中国沙漠》
CSCD
北大核心
2004年第2期187-190,共4页
Journal of Desert Research
基金
国家 973"沙漠化项目(G2000048705
G2000048702)资助
关键词
戈壁防护带
动力平衡
阻沙
输沙
风沙地貌
莫高窟
Mogao Grottoes
gobi preventing system
dynamic equilibrium
arresting sand and transporting sand
