Comparative study of the shelter efficacy of straw checkerboard barriers and rocky checkerboard barriers in a wind tunnel

Abstract

To compare the shelter efficacy of straw checkerboard barriers (SCBs) and rocky checkerboard barriers (RCBs), we measured the flow fields and sand fluxes associated with them in a wind tunnel. For both SCBs and RCBs, a deceleration zone and streamwise vortex formed inside the checkerboards, and an accelerated jet flow emerged at their top. Nevertheless, the material properties of straw and rock are tremendously different, which lead the characteristics of aeolian transport over SCBs and RCBs to be different. 1) Wind velocity decreased gradually across SCBs, reached a minimum in the third checkerboard, and then kept stable; in contrast, wind velocity decreased suddenly and reached a minimum in the first RCB, while it then slightly recovered across the second and third checkerboards and finally kept stable. Moreover, the deceleration zone inside the SCBs decreased gradually as the velocity increased, but that inside the RCBs did not obviously decrease. 2) Under low velocities (≤12.0 m/s), a stronger jet flow presented above RCBs than SCBs, in which more sediments were lifted and transported above RCBs than SCBs, whereas under high velocities (≥16.0 m/s), the results were just the opposite. Therefore, the sand stabilization efficiency of SCBs was better than RCBs when wind velocities were low, while the sand stabilization efficiency of RCBs was better than SCBs when wind velocities were high. This study indicates that SCBs are more suitable for sand fixation in weak wind areas, and RCBs are more suitable in strong wind areas.