Through wind tunnel experiments, we measured the surface drifting sand flux structure and sand transport rate at height of 0~70 cm on a bed surface under conditions of ridge microtopography with different height and different spacing. The results show that the percentage of sand transport in 0~10 cm layer above the bed surface is significantly reduced under ridge microtopography condition compared with no ridges condition. Under ridge microtopography condition, the percentage of sand transport in 0~10 cm layer decreases with the increase of ridge height, while it generally increases with the increase of ridge spacing and wind velocity. Under no ridges condition, the sand transport rate decreases in a power function law with the increase of height. The variation of sand transport rate with height under ridge microtopography condition could be divided into two cases: one shows that sand transport rate decreases exponentially with the increase of height, while the other shows that sand transport rate increases with the increase of height under a certain height, and above the certain height it decreases exponentially with the increase of height, known as “elephant nose” effect which seems similar to the structure of drifting sand flux in Gobi desert. For all the ridge heights and spacings, the total sand transport rate at height of 0~70 cm increases with the increase of friction velocity in a power function law, and it increases with the increase of ridge spacing. The simulation of the drifting sand flux structure and the relationship between sand transport rate and height shows that the ridge microtopography reduces the sand transport ratio of near surface air flow compared with no ridges condition. The results will contribute to studies on recognizing the process and mechanism of soil wind erosion in ridge farmland.

Through wind tunnel experiments, we measured the structure of surface drifting sand flux and sand transport rate on a bed surface that contained widely but uniformly spaced and non-erodible ridges. We found that under the condition of no ridges, the sand transport rate within the height of 0~70 cm on the bed surface decreases in a power function law with the increase of height, increases with the increase of friction velocity, and the proportion of sand transport rate at different high layers increases with the increase of height. The variation of sand transport rate with height can be divided into two cases for all the ridge heights and spacings: one shows that sand transport rate decreases exponentially with height, while the other shows that sand transport rate increases with height under a certain height, and above the certain height decreases exponentially with the increase of height, known as “elephant nose” effect which seems similar to the structure of drifting sand flux in Gobi desert. For all the ridge heights and spacings, the total sand transport rate in the height of 0~70 cm increases with the increase of friction velocity in a power function law, and increases with the increase of ridge spacing. When the friction velocity and ridge spacing are both large, the total sand transport rate of some ridge structures are larger than that with no ridges. Our results will contribute to the study on recognize the process and mechanism of soil wind erosion in ridge farmland.