This paper aimed to find out the law of three-dimensional airflow patterns around Tamarix ramosissima nebkhas under different background vegetation coverages. In order to reveal erosion and deposition process mechanism and provide a theoretical basis for scientific conservation of nebkhas, the Tamarix ramosissima nebkhas and sparsifolia at southern edge of the Taklimakan Desert-oasis ecotone were chosen as experimental model and wind velocity was investigated through wind tunnel simulation. Results showed that the three-dimensional airflow structure of Tamarix ramosissima nebkhas can be divided into six regions:the deceleration zone before nebkhas, the acceleration region of nebkhas windward, the high speed zone on both sides of nebkhas, the strong vortex area on leeward side of nebkhas, the recovery zone after nebkhas and the mixed acceleration zone above nebkhas. The influence region of nebkhas on airflow patterns was from -10H to 14H in horizontal direction and the width of side influence zone was less than 3/4 of nebkhas width. While in vertical direction, the airflow patterns were significantly affected by the area below the overall height of nebkhas and the maximum influence height was less than 2H. The background vegetation coverage played an important role in affecting the airflow patterns instead of wind velocity. With the increase of background vegetation coverage, the deceleration zone and recovery zone were expanded at front of nebkhas and behind nebkhas, respectively. Meanwhile, the strong vortex zone and high speed zone became shrinked on lee side and both sides of nebkhas. The wind velocity was significantly reduced at the height where the background vegetation existed. The airflow acceleration rates at each region of nebkhas showed a nearly exponential decay with background vegetation coverage. When the coverage was more than 16%, the acceleration rate tended to be steady. From the perspective of maintaining oasis security and according to the principle of wind-blown sand dynamics, background vegetation coverage should be maintained at least at 16% in desert-oasis ecotones so as to maintaining security and stability of oases.
Tan Fengzhu
,
Wang Xueqin
,
Wang Haifeng
,
Xu Junrong
,
Yuan Xinxin
. Wind Tunnel Simulation of the Three-Dimensional Airflow Patterns around Tamarix ramosissima Nebkhas under the Change of Background Vegetation Coverage[J]. Journal of Desert Research, 2018
, 38(1)
: 48
-57
.
DOI: 10.7522/j.issn.1000-694X.2016.00158
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