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对流动、半流动、半固定和固定沙地 4种不同下垫面 0～ 2 0 cm气流层的风沙流结构与变异特征研究表明 :(1 )不同退化沙地在总输沙量及各层输沙量上存在明显的差异 ,在 5月 1 5日的测定中 ,流动沙地的总输沙量是 83 .1g/ cm2 .h,分别是半流动、半固定和固定沙地的 2 .1倍、9.2倍和 33 .9倍 ;而在 5月 1 5日的测定中 ,流动沙地的总输沙量 1 0 5.7g/ cm2 .h,分别是半流动、半固定和固定沙地的 5.6倍、1 4.1倍和 75.6倍。(2 )总输沙量的 60以上分布在 1 0cm的高度内 ,随高度的增加 ,输沙量呈负指数函数下降。(3)风蚀物中粗粒 (粒径 1 .0～ 0 .5mm )与极细颗粒 (粒径0 .1～ 0 .0 5mm)和粉、粘粒 (<0 .0 5mm)的含量均很低 ,而细颗粒 (粒径 0 .2 5～ 0 .1 mm)的含量很高 ,占风蚀物的73 %～ 91 %,说明近地表层沙粒的运动以跃移为主。随高度的增加 ,风蚀物中中颗粒 (粒径 0 .5～ 0 .2 5mm)的含量下降 ,而极细颗粒和粉、粘粒含量增加 ,但其增幅因下垫面不同而异。(4) 0～ 2 0 cm总输沙量及各层输沙量与植被盖度呈显著负相关 ,与植株高度、地表紧实度和地表粗糙度长度呈微弱负相关
The research on the structure and variation of wind-blown sand flow in 0 ~ 20 cm air layer of four kinds of underlying surface in flowing, semi-flow, semi-fixed and fixed sandy land shows that: (1) There was a clear difference in sediment load. In the May 15 test, the total sediment load of the mobile sandy land was 83.1g / cm2h, which was semi-flow, semi-fixed and fixed sandy land, respectively. 1 times, 9.2 times and 33.9 times; and in the May 15 determination, the total sandy sediment transport capacity of 107g / cm2. H, respectively, semi-mobile, semi-fixed and fixed sand 5.6 times, 1 4.1 times and 75.6 times. (2) Above 60% of the total sediment discharge is distributed in the height of 10 cm. With the increase of height, the sediment load decreases with a negative exponential function. (3) The contents of coarse particles (particle size 1.0 ~ 0.5mm) and very fine particles (particle size 0.1-1.0mm) and powder and clay (<0,05mm) Is very low, and the content of fine particles (0-2.5-0.1 mm in diameter) is very high, accounting for 73% -91% of the eroded materials, indicating that the movement of sand in the near surface layer is dominated by the jump. With the increase of height, the content of medium particles (particle size 0.5-0.25 mm) decreased, while the content of ultrafine particles, powder and clay particles increased, but the increase was different due to the underlying surface. (4) There was a significant negative correlation between total sediment load and sediment discharge at all levels and vegetation coverage at 0 ~ 20 cm, negatively correlated with plant height, surface compaction and surface roughness