Abstract:

The Dunhuang-Germany Railway passes through the desert area in northwest China， with bare surfaces， abundant sand sources and strong windblown sand activities. This paper reveals the wind dynamic environment and surface sediment characteristics of the shrub sections along the railway through field wind fixed position monitoring and surface sediment grain size analysis. The results show that the annual average wind speed and the frequency of sand-driving in the study area are 2.13 m·s^-1 and 3.91%， and the annual sand transport potential is 19.89 VU， which is a low wind environment with little inter-annual variation and obvious seasonal variation， and the highest sand transport potential in winter. The dominant wind direction is relatively homogeneous， mainly south wind and west wind， and with significant seasonal variation. The sediment in the shrub desert is dominated by fine particles， with <250 μm fine particles exceeding 85% and dominated by <63 μm silt； The <250 μm fine particles content on the unvegetated roadbed slopes ranges from 60% to 80%， with >500 μm coarse particles content reaching up to 22%. The mean grain size of the shrub sediment was 43.85 μm， with a skewness of 0.29， kurtosis of 1.41 and sorting coefficient of 2.06， and the corresponding value at roadbed slope is 117.18 μm， 0.16， 1.00 and 2.09， respectively. The sediments on the two sampling points are poor sorting， and the sediments under shrub are finer with a more concentrated grain size distribution， indicating that the surface material is stable due to shrub protection and fine particles are well preserved.

Key words: shrub desert, Dunhuang-Golmud Railway, wind dynamic environment, sand drift potential, grain size characteristics