科尔沁沙地响水河河岸沙丘粒度特征

Grain size distribution of sand dunes at Xiangshui River banks in the Horqin sandy land

以科尔沁沙地西部响水河河岸沙丘为研究对象,野外沿盛行风方向从河流边滩采样至河岸沙带外缘灌草丛沙丘地,室内经激光粒度仪测试,研究河岸沙丘不同地貌部位粒度特征及分布规律,探讨河流对下风侧沙丘发育的影响.结果表明,科尔沁沙地响水河东岸沙丘沙物质组成优势粒径为细沙和中沙,所占比重为43.83%和38.57%,平均粒径在0.09~0.34mm,均值为0.22mm,属中等分选;频率曲线近对称且均为单峰,峰度均值1.01,多为常峰态.植被带对沙丘粒度分布有重要影响,致使在河岸沙带尺度上,因距离河岸远近不同,沙丘粒度参数呈现变化特征.

Field investigation and experiment were done on Xiangshui River bank dune that located in the west of the Horqin sandy land.Along the prevailing wind direction,the sampling work started from the river marginal bank to the shrub dune land at riparian sandy zone edge.Through indoor laser particle size analyzer,grain size characteristics and distribution rules of different landform parts of riparian dune were studied and the influence of the river on the downwind side dune development was discussed.The results showed that the advantage grain sizes of the sand dune material composition in east coast of Xiangshui River in Horqin sandy land are fine and medium sand,account for 43.83% and 38.57%.The average particle size is between 0.09 and 0.34 mm,and the mean value is 0.22 mm,which belongs to medium separation.Frequency curves are nearly symmetrical and they are all single peak.Kurtosis mean value is 1.01,which usually shows as mesokurtosis.Vegetation belt has important influences on grain size distribution of the dunes.Due to the different distance to the river bank,the variation law of dune grain size parameters is obvious on the scale of riparian sandy zone.