塔克拉玛干沙漠腹地贴地层风沙流结构研究

利用微梯度集沙仪在塔克拉玛干沙漠腹地塔中地区实测的2014年7—8月贴地层输沙量梯度观测资料(观测高度区间0~5 mm、5~15 mm、15~35 mm、35~85 mm),对沙尘天气过程贴地层风沙流结构进行了研究。结果表明:(1)沙尘天气(沙尘暴和扬沙)过程中,随着风速的增大,各高度层输沙量也随之增大。沙尘暴天气中,风速7.5 m·s~(-1)时,15~35 mm处的百分含量超过5~15 mm处的百分含量,风速7.5 m·s~(-1)时,15~35 mm处的百分含量达到最大,其余各高度含量变化不明显。扬沙天气中,风速8.0 m·s~(-1)时,百分含量最大值出现在35~85 mm高度处,占48.9%,风速8.0 m·s~(-1)时,大小依次为:15~35 mm(49.5%)35~85 mm(31.7%)0~5 mm(12.7%)5~15 mm(9.2%)。(2)两种天气过程中,沙粒的平均粒径在垂直高度上均呈现先减小后增大的趋势。粒径峰值均处在125~250 um,极细砂含量最高,细砂次之。与扬沙天气相比,沙尘暴天气过程中极细砂、细砂、中砂在各高度层上的含量略微下降,粉尘含量有所升高。

Tower of gradients of sediment transport by wind-blown sandin distribution

On July to August in 2014 of the column area,Using sand to collect 0~85mm four micro-gradient gradient data of different gradients of sediment distribution was studied,the results show that:(1)in the Taklamakan desert and sand dust storm weather process,as wind speed increases,the various layers and sediment fluxes also increased.Raising sand in weather,when the wind in the 8m.s_-1,the percentage of maximum value occurs at the 35~85mm level,48.9%, wind speed is greater than 8m.s_-1,the order of 15~35mm (49.5%)>35~85mm(31.7%)>0~5mm(12.7%)>5~15mm(9.2%).Dust storm,wind speed is greater than 7.5M.S-1,15~35mm percent more than 5~15mm of content, wind speed is greater than 7.5M.S-1,15~35mm content at max,remaining highly content does not change significantly.(2)two kinds of weather processes,grains of sand average size first decreases and then increases in vertical height trends.Peak are 125~250um of size, highest content of very fine sand, fine sand followed.Compared with the dust weather, sandstorm weather process of very fine sand, fine sand, medium sand content in all levels declined slightly,dust content increased.(3)on the vertical distribution, sediment has good correlation with wind speed and power functions to better describe the vertical distribution of sediment flux in the region,and verify and supplement the previous results of wind tunnel tests.