民勤荒漠-绿洲过渡带不同下垫面条件的土壤风蚀特征

为了研究不同下垫面对土壤风蚀特征的影响,根据2009年4月19日、4月22-23日及4月30日3次沙尘事件的实际观测数据,对民勤荒漠-绿洲过渡带不同下垫面土壤风蚀特征进行了试验研究。试验结果表明,民勤荒漠绿洲过渡带各地表挟沙气流中输沙量沿垂线分布呈上段符合传统的指数递减分布规律,而近床面区35cm以下的输沙量较对应的指数分布函数预测值偏大;流沙地表90%以上的输沙量集中在近地表15cm以内,白刺灌丛沙包地带、草方格固沙带及草方格前沿芦苇荒漠带输沙量的80%左右集中在距表35cm高度范围内;不同下垫面条件对风蚀物颗粒大小分布规律的影响主要集中在近地表气流层15cm范围内,而对35～125cm高度范围内风蚀物颗粒粒径大小的影响主要在各粒径颗粒的体积分数上。风在草方格固沙带的搬运能力最弱,白刺灌丛沙包带其次,再次为芦苇荒漠带,在沙丘顶部的搬运能力最强,输沙量最大。

Characteristics of aeolian sediment under different underlying surfaces in oasis-desert transitional region of Minqin

Based on the practical observation materials of three sand storms in Minqin county,the characteristics of aeolian sediment under different underlying surfaces in the oasis-desert transitional region of this area were studied.The sand storms were occurred on April 19,22-23 and 30 in 2009.The results showed that the upper segment of the sediment discharge line of the vertical distribution fit in with exponential rule,and the real sediment near the soil surface(beneath 35 cm) was larger than that of calculated with the exponential function.90% sediment discharge of the sand surface was beneath 15 cm.80% sediment discharge of soil surfaces with Nitraria bushes,straw checkerboard barrier and reed were in the height of 35 cm from the soil surface.The effects of underlying surface with different conditions on sediment particles diameter mainly focus on the near surface at 15 cm range from soil surface,and the effects on the particle size of aeolian sediment at 35 cm to 125 cm range mainly focus on the percentage of different particles.The straw checkerboard barrier is a best way for reducing the wind erosion,which can lower the sediment transport capacity of wind.The function of soil surface with Nitraria bushes takes the second place,and the soil surface with reeds is the third.The surface covered by sand has the biggest sediment discharge.