Characteristics of Sand Transport on the Surface of Transverse Ridge
Microtopography
Abstract
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.