Aeolian sand transport above three desert surfaces in northern China with different characteristics (shifting sand, straw checkerboard, and gravel): field observations

Abstract

Aeolian sand transport results from interactions between the wind and the ground surface, and is a key link between microscale mechanisms responsible for the movement of individual grains of sand and macroscopic mechanisms that govern the flow of windblown sand. As a result, many studies have been performed to study aeolian transport, but a few studies have simultaneously compared the effects of the surface characteristics on aeolian transport in the same region. In this study, we designed three experimental areas to provide a comparison of the transport rates under different types of boundary layer conditions (shifting sand, straw checkerboard, and gravel), with different sediment availability but under the same wind regime. The study was conducted at the Shapotou Aeolian Experiment Site, Chinese Academy of Sciences, where we studied the sand transport rate and mass-flux-density profiles using synchronous experimental data. The surface characteristics dramatically affected aeolian transport. The mass-flux-density profile above the open shifting sand surface and straw checkerboard reached its maximum value near the surface, and followed an exponential-decay function. For the gravel surface, the maximum transport occurred at a certain height above the ground, but above that height, followed an exponential-decay curve. The transport rate was greatest above the open shifting sand, reaching up to 465 times the rate above the straw checkerboard, with intermediate values above the gravel surface. The average saltation height was highest above the gravel-covered surface, and lowest above the straw checkerboard surface.