Aeolian sediment transport over sandy gobi: Field studies in the Nanhu gobi along the Hami-Lop Nor Railway

Abstract

Wind-blown sand over sandy gobi with an abundant sediment supply can cause severe sand hazards. However, compared with the study of aeolian transport over gravel gobi with a limited sediment supply, less attention has been devoted to sandy gobi, and thus, our understanding of wind-blown sand movement on sandy gobi is still poor. Here, we report the results of observations of three transport events on a sandy gobi along the Hami-Lop Nor Railway based on high-frequency saltation particle count and horizontal sediment flux measurements coupled with instantaneous wind velocity measurements. The results reveal that, unlike the notably intermittent aeolian saltation over gravel gobi, continuous transport occurred on the sandy gobi. The mean saltation layer height was 0.23 ± 0.07 m, and it was positively related to both the grain size of surface particles and the wind velocity regardless of the gobi type. The sediment transport rates could be expressed as the power function Q = ap/g[u∗ (u∗2-u∗t2)]b, and the scaling parameter (b) reached to 2.5, which is much larger than that of other gobi areas (b = 1). Our findings suggest that the wind-blown sand over sandy gobi is much more severe than that over gravel gobi, and the Nanhu sandy gobi is the major sand source for sand hazards of the Hami-Lop Nor Railway. Sand-fixation measures such as checkerboard sand barriers with enhanced checkerboard size and barrier height should be the main subject of sand control systems for the Hami-Lop Nor Railway in sandy gobi.

Keywords

• Sandy gobi
• Saltation threshold
• Saltation layer height
• Sediment transport rates
• Wind-blown sand control