【作者】 张瑞军；

【导师】 何清；

【作者基本信息】 新疆师范大学 ， 自然地理， 2008， 硕士

【摘要】 研究表明,塔克拉玛干沙漠北部肖塘地区地表沙主要以细沙(0.125～0.25mm)为主,占48.35%,极细沙(0.0625mm～0.125mm)占30.05%,中沙(0.25～0.5mm)占14.34%,粉沙(0.0039～0.0625mm)占6.09%,同时丘间沙有黏土(0.00002～0.0039mm)存在,含量在0.5%～0.8%;以细沙为主的粒度特征就是造成肖塘地区沙尘暴结束后很少出现浮尘天气的主要原因,也是造成该地沙尘暴主要以就地起沙为主,只有少数几次较强的天气系统形成远源沙尘暴;沙丘沙样分选良好,标准偏差(σ1)为0.61,其次是胡杨林带和生态防护林带,为0.65、0.69,古河床的沙样分选最差为1.31,河床沉积土为1.64;沙尘暴输沙贡献以沙为主,河床裸露面积小,表土胶结紧实,对沙尘暴沙源贡献不大。利用的肖塘地区梯度自动站2007年01月01日-2007年05月31日的观测数据,计算出该区域的中性条件下粗糙度范围是1.00×10-11-1.65×10-3m,平均粗糙度为6.05×10-5m,接近沙粒粒径的1/30,与平坦沙面粗糙度相似。摩阻速度的范围是0.14-2.33ms-1,平均值1.24ms-1。粗糙度随下垫面性质变化明显,与稳定度呈正相关,与风速呈负相关,摩阻速度随粗糙度增大减小。利用2007年4月15日-5月14日在塔克拉玛干沙漠北缘肖塘观测沙尘暴贴地层输沙沙样分析表明:沙尘暴贴地层100cm范围内输沙量的多少受下垫面性质和地表沉积物粒度特征影响,输沙量的对数与高度的对数成线性相关;输沙以极细沙、细沙和粗粉沙为主,>1mm的沙粒跃移高度在20cm以下;输沙沙样的平均粒径值随高度增加减小,标准偏差(σ1)的取值范围在0.85～1.71之间,偏度(SK1)呈正偏和极正偏,峰度(KG)值分布在1.19～1.81属于尖锐型和很尖锐型。更多还原

【Abstract】 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.更多还原