若尔盖盆地沙丘形成分布影响因素探讨

Impact Factors to Formation and Distribution of Sand Dunes in Zoige Basin

应用遥感数据、DEM数据、野外采样数据和气象数据探讨若尔盖盆地沙丘形成分布的影响因素。气候变化与人类活动等多种因素导致的现代河相沉积物与活化出露的古河相湖相沉积物是重要沙源,风动力条件与沙源的时空结合在堆积床面形成沙丘,沙丘主要分布在河谷与丘陵山坡。沙丘分布随海拔高度增加面积减少,随坡度增大面积下降。河谷沙丘坡度小,主导坡向也不突出。丘陵沙丘坡度相对较大,以分布在斜坡和缓坡为主;主导坡向相对突出,主要分布在背风坡的东坡、东南坡。在沙源地下风方向随距离增大沙丘沉积物平均粒径变小,分选性变好。沙丘形成是沙源、风动力、堆积床面三者耦合作用的结果,这种耦合既表现在时间上,也表现在空间上。

Impact factors in formation and distribution of sand dunes in Zoige Basin are analyzed based on remote sensing data, DEM data, meteorological data and sand samples. Dunes formation and distribution is the result of coupling of sand source, wind force and suitable place. Sand dunes were distributed on valley and low hill slope. Modern river alluvium and ancient lake and river alluvium are the main sand sources. The sorting of sand particles becomes better and median diameter of sand particles grows smaller as sand dunes run way in removal on the lee. Sand dunes reduce as altitude or slope increases. Riverine dunes were mostly distributed on the flat and very flat slope and were almost averagely distributed on every aspect. Hill dunes were distributed on the flat, slanting slope and were mostly distributed on the leeward slope.