关键词: 莫高窟, 戈壁防护带, 动力平衡, 阻沙与输沙

Abstract: 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.

Key words: Mogao Grottoes, gobi preventing system, dynamic equilibrium, arresting sand and transporting sand