塔克拉玛干沙漠的起沙风速

THRESHOLD VELOCITIES OF SAND-DRIVING WIND IN THE TAKLIMAKAN DESERT

起沙风速根据观测高度、风速时距以及流体或冲击起动性质分别确定。本文建立了塔克拉玛干沙漠腹地肖塘地区不同高度、不同时距的流体起动与冲击起动风速的相关方程。结果表明：该地天然沙的瞬时冲击起动风速（２ｍ高度）５．０ｍ／ｓ，流体起动风速６．０ｍ／ｓ；１分钟平均流体起动与冲击起动风速为５．２ｍ／ｓ和４．３ｍ／ｓ。气象站观测高度（１１．４ｍ）瞬时流体起动和冲击起动风速为７．８ｍ／ｓ和６．６ｍ／ｓ；１０分钟平均值为７．４ｍ／ｓ和５．９７（≈６．０）ｍ／ｓ。

Sand-driving wind is one of the important factors in the study of aeolian sand movement, therefore it is of great significance to determine the threshold velocity accurately for the estimation of sand transport rate and recommendaton of proper sand control measures. On the basis of field observation this paper attempts to make out the fluid threshold and impact threshold and adapt them for different heights and time durations. Consequently, the wind data derived from the meteorological observatory will be more efficiently used in the study of sand movement. By means of the work mentioned above, the following results have been reached.At the height 2m above ground surface.for naturally mixed sands,the instant fluid and impact threshold velocities are 6.0 and 5. 0m/s respectively,equivalent to one minute averages of 5.2 and 4. 3m/s respectively. While averaging on ten minutes duration, the fluid and impact threshold velocities are 5.7 and 4. 7m/s respectively. Both fluid and impact thresholds have been adopted for the height of 11.4m (the height of anemometer tower) at which the instant velocities for the former and later are 7.8 and 6.63m/s respectively, equivalent to 7. 4 and 5.97(≈6.0)m/s of ten minute averages.