Particle Size Variability Of Gobi Surface Sediments And Its Effect On Wind-sand Activities

The gobi desert is one of the desert landscapes in the arid region,with coarse sand on the surface,coverage of gravel,sparse vegetation.Under the action of wind and sand for a long time,a "homogeneous surface" is formed macroscopically,however,there is significant spatial variability in the composition of surface sediments with full particle size.The traditional particle size analysis method plays an important role in characterizing the distribution of particle size components and sorting characteristics,but it is seriously deficient in comprehensively and accurately expressing the surface full particle size distribution and its spatial variability.This variability significantly affects surface correlation processes in arid areas.Therefore,this paper attempts to express the full particle size variability of gobi surface by using the Li model of the distribution of the latest research results.The results show that:1.The model can reflect the spatial variation characteristics of gobi surface with full particle size,and the parameter values have a significant effect on the classification of gobi surface,which can be used for the quantitative expression of gobi surface heterogeneity at both macro and micro scales.The C values of sandy gobi ranged from 47.09 to 998.1,with? values ranging from-0.65 to 0.24,and Dc values ranging from 0.09 to 1.78;The C values of fine gravel gobi ranged from 12.65 to 30.70,with ? values ranging from 0.39 to 0.72,and Dc values ranging from 0.75 to 24.22;The C value of medium gravel gobi ranged from 32.17 to 48.53,with with ? values ranging from 0.22 to 0.41,and Dc values ranging from 2.10 to 26.08.2.The relationship between the model parameters and the moving components and the release of wind-erosion sand dust shows that the full-size model can reveal the transport mode and separation capability of components in the process of wind-sand movement,and also reflect the strength of wind-sand activities.Preliminary studies show:With the increase of suspended components,the C value decreases and the ? value increases;With the increase of skip component,C value increases,and the ? values and Dc decrease;With the increase of the creep component,the C value decreases,the ? value first increases and then decreases,and the value of Dc increases.With the increase of Dc value,the horizontal sediment transport rate and the dust release intensity of wind erosion gradually decrease.3.Although the surface of the gobi is relatively uniform on the macro scale,the spatial variation of its full particle size characteristics on the micro scale is large.Moreover,the variation characteristics of surface full particle size have a certain influence on the micro-scale wind-sand activities,which makes the release intensity of wind-erosion dust show strong spatial variability within 50cm of the surface,while the release intensity of wind-erosion dust over 50cm tends to be unchanged.Therefore,in order to avoid certain errors caused by the sampling scale to the relevant research results of wind and sand movement,the sampling scale range of wind and sand movement on the gobi surface should not be less than 50cm.