Research On Grain Sizes And Land Surface Parameters On Source Regions Of Sandstorms In The Northern Of The Taklimakan Desert

The results show the fine sand (0.125～0.25mm) are dominant in surface sand samples in Xiao tong region in the northern of the Taklimakan Desert,which accounted for 48.35 percent, then very fine sand (0.0625mm～0.125mm) accounted for 30.05 percent, medium sand(0.0039～0.0625mm)accounted for 4.23 percent and powder sand(0.0039～0.0625mm)accounted for 6.09 percent, while clay(0.00002～0.0039mm) exist between the dunes, which accounted from 0.5 to 0.8 percent ; The sand characteristics of granularity makeup is main causation why the floating dust weather is rarely seen after the end of sandstorm in Xiao tang region, and why the sand of sandstorms is blew on the pot, Only a few of the several strong weather systems can cause a long-distance Sandstorm; The fine sorting of the sand samples is at the dunes, then the Populus euphratica forest belt and the ecological protection forest belt, standard deviation (σ1) were 0.61, 0.65 and 0.69, the worst sorting is 1.31 of Ancient riverbed samples. The standard deviation (σ1) of all riverbed sediment samples was wore was 1.64. The biggest contribution mostly comes from sandy surface. The bare area is small and tightly cementation in the riverbed surface, have a little contribution to the sand transport.Calculate roughness under the conditions of neutral stratification atmospheric in Xiao Tang through observational data from January 1, 2007 to May 31, 2007 ,that is 1.00×10^-11～1.65×10^-3m , the average roughness is 6.05×10^-5m, close to 1/30 of the sand particle size, and similar to flat sand bed. The scope of friction speed is 0.14-2.33 ms-1.Average is 1.24 ms-1. Roughness changes obviously with the properties of underlying surface. Roughness is positive correlation with stability, and negatively correlated with the wind speed. The friction velocity decreases with increasing roughness.Based on the data of characteristics of grain sizes for samples of transporting sediment in the ground layer from April 15 to May 14 in 2007 in Xiao Tang .We can easily come to these conclusions; The framework of the nature underlying surface sediment grain size and surface characteristics impact on the discharge of landslide during the course of sandstorms in 100cm ground layer. Logarithm of height and discharge of landslide have the linear correlation. the very fine , fine and coarse powder sand are dominant in samples of transporting in Xiao tang region, the saltation load high of sand (the particle size of sand is bigger than 1 mm) is under 20 cm ,the value of particle size decreases with height increased, the standard deviation (σ₁) range is between 0.85 and 1.71,the skewness (SK₁) is positively or extremely positively biased, the kurtosis (KG) (1.19～1.81)is a sharp or very intense type.