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通过单人系统取样,用筛析法对云南大理盆地隐仙溪河道沉积物进行了粒度分析。结果表明,河流上游以砾石沉积为主,平均质量分数(含量)达57.92%以上,砾石粒径以10～50cm为主,在砂质沉积物中以粗砂为主,其含量达28 35%,中细砂含量只有13.76%;河流中游虽然也以砾石沉积为主,但砾石粒径明显变小,以5～10cm为主;河流下游则以砂质沉积物为主,其中中砂、细砂和粉砂总含量高达77.64%,尤其是细砂和粉砂含量显著升高,分别达到27.96%和32.26%,而粗砂和砾石含量明显降低。不同河段沉积物粒度及其含量的变化主要受水动力条件、地形坡度和搬运距离控制,但搬运距离与沉积物粒度之间不存在简单的线性对应关系。
Through the single-person system sampling, the sediment of the Xianxian River in Dali Basin of Yunnan Province was analyzed by means of sieve analysis. The results show that the upper reaches of the river are dominated by gravel deposits with an average mass fraction of more than 57.92% and gravel with a diameter of 10 ~ 50cm. Sandy sediments dominate the sandy sediments with the content of 28 35% , While the fine sand content is only 13.76%; although the middle reaches of the river are mainly gravel sediments, the gravel size is obviously smaller, with 5 ~ 10cm as the main part; the lower reaches of the river are mainly sandy sediments, of which the sand and fine The total content of sand and silt is as high as 77.64%. The contents of fine sand and silt, in particular, are significantly increased, reaching 27.96% and 32.26% respectively, while the contents of coarse sand and gravel are obviously reduced. The variation of sediment particle size and its content in different river sections is mainly controlled by hydrodynamic conditions, topographic gradient and transport distance, but there is no simple linear correspondence between transport distance and sediment particle size.