[HCG23-P01] Wind Dynamic Process and Ecological Effect in Sand Barrier Environment of Mu Us Sandy land
Keywords:Sand-barrier, Flow field, Structure of drifting sand flux, Erosion accumulation feature, Vegetation restoration
Abstract:Sand barriers are the main measures to control mobile dunes and promote vegetation restoration in sandy areas. In order to analyze the wind speed, wind direction and the characteristics of the structure of the wind-blown sand flow in the horizontal and vertical directions of the section, explore the degree of surface stability within the barrier, and determine the optimal configuration to promote vegetation restoration, we selected the barchan chain in the hinterland of Mu Us Sandy Land as the research object. Through field observations, we carried out quantitative research on the airflow field, wind-sand flow structure, micro surface morphology and erosion volume of different slopes with different materials (salix, PLA, straw rope), different specifications (1m × 1m, 2m × 2m, 3m × 3m) sand barrier measures. And furthermore,field investigation of vegetation restoration under the same conditions was carried out.The results show that: ①The wind speed at the top of dune is 1.3-1.7 times of the wind speed at the inlet due to the air compression and the effect of windbreak at the foot and middle of slope is better than on the slope.There are differences in the arrangement of sand barriers to achieve the best wind prevention effect at different slope positions: the 1m×1m PLA has the best protection effect at the foot of the slope, and the 2m×2m salix sand barrier in the middle and on the slope have the best performance in reducing wind speed.②The maximum difference of sand transport rate of different types of sand barriers appears in the slope of 2m × 2m: Salix is 24.25 times more than PLA material, and with the greatest sand blocking capacity, its effect is better than straw rope than PLA material.③The amount of surface erosion and accumulation in the sand barrier is significantly related to the years of sand barrier laying. With the increase of time, wind erosion gradually appears. And furthmore, the larger size of sand barrier is, the deeper central erosion depth is, and the more serious the erosion is. Besides, under the same specifications, the surface erosion amount of PLA sand barrier is much higher than that of other two materials. The 3m×3m PLA sand barrier reaches the maximum, and its surface inside the barrier is in a severely unstable state.④Among the three materials, salix sand barrier has the best material to promote the vegetation recovery ability, and straw rope sand barrier is the most beneficial to increase the vegetation diversity. In the lower part of the windward slope, the vegetation coverage under the three specifications of salix sand barriers is 2.67 times, 1.79 times, and 3.88 times than the slope, respectively, and the slope is better than the slope. Shrubs and herbaceous vegetation restoration are complementary. And the small size is more beneficial to herbaceous vegetation restoration. Based on comprehensive cost factors, it is considered that in Mu Us Sandy land, the most suitable sand barrier material is salix.As well as, laying 2m × 2m specifications at the foot and middle of the slope, 1m × 1m specification on the slope can exert the best sand control and ecological effect.