Study On The Change Of Surface Wind-sand Flow In Desertification Grassland

In recent years, wind-sand flow disasters have caused great attention in China, andstudy on mechanism of wind-sand flow is considered to be a key factor of comprehensiveunderstanding and prevention of wind-sand disaster. So, in this paper make the desertgrassland as background, the main researched influencing factors and the law of motion ofthe impact the sand flow near desert grassland surface, and analyzed relativity relationshipbetween sediment concentration of wind-sand flow with wind speed, changes of soilproperties, vegetation cover, etc.. It discussed the difference analysis between height anddirection for Sand Quantity, and revealed the characteristics changes of surface wind-sandflow in the desert steppe, the conclusions are as follows:⑴In spring and autumn, sediment concentration of wind-sand flow and average windspeed was a significant positive correlation; in spring, sediment concentration of wind-sandflow and average soil moisture was a high negative correlation, in winter was a significantpositive correlation; in spring, sediment concentration of wind-sand flow and averagesurface temperature was highly positively correlated; in spring, sediment concentration ofwind-sand flow and the air humidity was a high negative correlation, and in fall was asignificant negative correlation.⑵Sediment concentration of wind-sand flow was highly correlated with each influencefactors in spring. The correlation coefficients were as follows: the average moisture content>the average surface temperature>the average wind speed>the average air humidity. Insummer, sediment concentrations of wind-sand flow with vegetation changes wasgenerally a negative correlation, but due to precipitation effected the data accuracy ofcollecting sand trap, resulting in low correlation between each impact factors and sand trapamount in the summer.⑶Sediment concentration of wind-sand flow was worst correlated with each influencefactors in dominant wind direction. In addition, the high is more significant difference onthe sand amount than the impact on the direction.⑷Each quarter of surface wind-sand flow structure had a big difference in the desertsteppe: in spring and summer, sediment concentration is reduced with altitude increasing, and each layers of sediment content with the height had larger variation; in fall and winter,the sediment concentration with height increase essentially the same, and each layers ofsediment concentration changes less. In spring and summer, sediment concentration withthe height of variation in line with the power function and logarithmic functions, and thecorrelation coefficients of the power function are greater than that of the logarithmicfunction; in autumn and winter, sediment concentration with a high degree of variationcomplies with the polynomial function.⑸The total sediment concentration of wind-sand flow: summer（54.497g）> spring（48.096g）> winte（r10.0081g）> autum（n8.982g）. Each season the maximum of sedimentconcentration of wind-sand flow is in the W, NW; the minimum is in E, which is mainlydetermined by the wind direction frequency.⑹In spring the maximum value of particles composed as the height were followed bysilver sand, thick powder sand, fine powder sand. In summer the maximum value ofparticles composed with height were followed by middle sand, thick powder sand. Inautumn and winter, the maximum of particle composition at different altitudes were thickpowder sand. It indicated that in spring wind-sand current activity strong, low-level leadsilver sand, while more upper layer of fine powder sand floating in the air. In summer dueto more precipitation, lower layer was entered to the middle sand by rain. In other seasons,wind-sand flow is mainly thick powder sand and middle powder sand.