Abstract
<p indent="0mm">Sand barriers are an engineering measure for sand fixation, and play an important role in promoting dune fixation and vegetation restoration. As the most widely used means of sand control, sand barriers have a variety of materials and configurations. In recent years, some new sand fixation materials have appeared, but their benefits of sand fixation have not been compared and evaluated. Moreover, there is an insufficient amount of research on the sand fixation mechanism of sand barriers. Therefore, an accurate understanding of the sand fixation mechanism of sand barriers and the optimization of its configuration mode is conducive to improving the techniques of wind prevention and sand fixation. In this paper, four barchan dunes developed in the Mu Us sandy land were selected as the research carrier. One of the dunes is a reference dune without sand barriers, and the remaining three dunes are covered with sand barriers of different materials and specifications. There are 9 types of sand barriers, which can be divided into 3 materials (Salix, straw rope and PLA) and 3 specifications (1 m<sc>×1 m,</sc> 2 m<sc>×2 m</sc> and 3 m<sc>×3 m).</sc> This study revealed the surface processes of dunes under each type of sand barrier and evaluated the benefits of each type of sand barrier on sand fixation and ecological restoration through topography measurements, sand drift observations, sediment sampling, vegetation investigations and laboratory analyses. The results show that the sand barriers have the functions of reducing the height of dunes, reshaping the surface micromorphology, decreasing near-surface wind speed, blocking the sand transport and promoting vegetation restoration, and the strength of the functions is controlled by the material of the sand barrier, the configuration mode of the sand barrier and the relative positions on the dune. Detailed analysis of the benefits in sand fixation and vegetation restoration of each type of sand barrier suggests that the Salix barrier is the best choice in this area, the straw rope barrier is the second best choice, and the PLA barrier is the worst. The best configuration mode of the Salix barrier and straw rope barrier is 1 m<sc>×1 m,</sc> while that of the PLA barrier is 2 m<sc>×2 m.</sc> Moreover, this study considered that the effect of sand barriers on wind prevention and sand fixation are decided by multiple factors, and it is not sufficient to take the near-surface wind speed or micromorphology as the measurement standards of these effects. The selection of sand barrier materials and configurations needs to comprehensively consider many issues, such as the efficiency of sand fixation, the ability to promote vegetation restoration, sustainable time, economic cost and secondary pollution. Thus, sand barrier projects should take the regional sand fixation demand and field environment into account and select the most suitable configuration forms according to the main objectives or demand.
Published Version
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