内蒙古高原小叶锦鸡儿灌丛沙堆对气流结构与风蚀的影响  

Impact of Caragana microphylla Nabkhas on Airflow Structure and Wind Erosion in Inner Mongolia Plateau

作　　者：安晶[1] 哈斯[1] 杜会石[1] 杨一[1] 张萍[2] 

机构地区：[1]北京师范大学资源学院,北京100875 [2]宁夏大学农学院,宁夏银川750021

出　　处：《干旱区研究》2015年第2期304-312,共9页Arid Zone Research

基　　金：国家自然科学基金(41171002)

摘　　要：小叶锦鸡儿（Caragana microphylla）灌丛沙堆是内蒙古高原东南部农牧交错区的主要风沙堆积类型。通过对该区典型灌丛沙堆周围风沙气流的野外观测,结果表明,气流方向与强度和输沙率,随沙堆不同位置而发生变化。绕过沙堆两侧的气流和越过沙堆上部的气流在背风侧汇集,并在同等沙堆高度的范围内和1.5倍沙堆高度的水平范围内出现涡流。从灌丛沙堆迎风坡脚经南北两侧至背风坡脚以及背风侧5倍沙堆高度的水平距离间,风速依次出现逐渐增大—最大—逐渐减小—最小—回増至旷野风速的变化过程。在不同风向条件下,灌丛沙堆背风侧气流的风速廓线,并不完全遵循对数变化规律,沙堆南侧气流在0.3~0.6 m高度处出现变异。另外,沙堆周围输沙率在迎风侧和南北两侧与风速变化基本一致,但在背风侧因气流方向紊乱而出现变异。输沙率随高度增加,在沙堆迎风侧至两侧各部位呈有规律递减,但在背风侧无规律。Caragana microphylla Nabkhas is the main aeolian deposit in the agro-pastoral transitional zones in southeast Inner Mongolia Plateau. Field investigations on the airflow structure and wind-sand flow of some typical nebkhas showed that the direction and intensity of the airflow and the sediment transport rate varied with the different positions of the nebkhas. The airflow around the nebkhas and over the top of the nebkhas merged together at leeward and turbulences were developed thereafter with a vertical range of the height of the nebkhas and a horizontal range of 1. 5 times of the height of the nebkhas. The wind velocity increased at windward and kept increase at the north and the south sides of the nebkhas,then reached the lowest velocity at leeward and then gradually increased back to the wildness wind speed. The main wind direction affected the airflow at leeward. Under the different wind directions,the wind velocity profile around the nebkhas showed non-logarithmic regularity. The wind velocity at the height of 0. 3- 0. 6 m changed under different wind directions at the south side of nebkhas. In addition,sediment transport rates at the windward,the north and south the sides of the nebkhas were consistent with the change of the velocity. However,sediment transport rate at leeward changed because of the turbulence. Sediment transport rate decreased with the increase of the height at windward and at the both sides of the nebkhas,but showed no regularity at leeward.

关 键 词：小叶锦鸡儿(Caragana microphylla) 灌丛沙堆 气流结构 输沙率 内蒙古高原 

分 类 号：P461[天文地球—大气科学及气象学]