Abstract: Wind tunnel tests were conducted to quantitatively simulate the erosion rates of gobi beds with different gravel coverages under sand supply by using weighing sensor and measuring the weight change of the erosion quadrat. Results reveal that gravel coverage is an important factor influencing erosion rates of gobi, and erosion rates decrease exponentially with increasing gravel coverage. When gravel coverage is over 50%, erosion rates decrease slowly with increasing gravel coverage and even no erosion occurring, indicating that the improvement in the protective effect against wind erosion is limited as increasing gravel coverage from 50% to 90%. However, erosion rates decrease markedly as gravel coverage increases from 10% to 50%. Thus, gobi beds composed of 3 and 4 cm gravels have good protective effect against wind erosion as gravel coverage at least reaches 50%. The protective effect of gobi beds against wind erosion can be explained by their effect on the threshold friction velocity for sand movement and shear stress partitioned into the erodible surface between gravels. Experimental results reveal that the threshold friction velocity for sand movement increases with increasing gravel coverage, and compared with the same sandy surface without covering gravels, it increases by 0.8-3.4 times, and only 0.5%-28% of the total shear stress is partitioned into the erodible surface as gravel coverage changes from 10% to 90%. This study has important referential significance for the application of the sand drift control engineering of gravel mulch to wind erosion control.

Key words: gobi, gravel coverage, erosion rates, wind tunnel